The compound is given by intravenous injection to do POSITRON-EMISSION TOMOGRAPHY for the assessment of cerebral and myocardial glucose metabolism in various physiological or pathological states including stroke and myocardial ischemia. It is also employed for the detection of malignant tumors including those of the brain, liver, and thyroid gland. (From Martindale, The Extra Pharmacopoeia, 30th ed, p1162)
An imaging technique using compounds labelled with short-lived positron-emitting radionuclides (such as carbon-11, nitrogen-13, oxygen-15 and fluorine-18) to measure cell metabolism. It has been useful in study of soft tissues such as CANCER; CARDIOVASCULAR SYSTEM; and brain. SINGLE-PHOTON EMISSION-COMPUTED TOMOGRAPHY is closely related to positron emission tomography, but uses isotopes with longer half-lives and resolution is lower.
Compounds that are used in medicine as sources of radiation for radiotherapy and for diagnostic purposes. They have numerous uses in research and industry. (Martindale, The Extra Pharmacopoeia, 30th ed, p1161)
Tomography using radioactive emissions from injected RADIONUCLIDES and computer ALGORITHMS to reconstruct an image.
Unstable isotopes of fluorine that decay or disintegrate emitting radiation. F atoms with atomic weights 17, 18, and 20-22 are radioactive fluorine isotopes.
2-Deoxy-D-arabino-hexose. An antimetabolite of glucose with antiviral activity.
'Deoxy sugars' are monosaccharides or oligosaccharides that contain fewer hydroxyl groups than the corresponding hexose or pentose, with deoxyribose being a well-known example of a deoxy sugar.
The use of combination of imaging techniques or platforms (e.g., MRI SCAN and PET SCAN) encompassing aspects of anatomical, functional, or molecular imaging methods.
Tomography using x-ray transmission and a computer algorithm to reconstruct the image.
Binary classification measures to assess test results. Sensitivity or recall rate is the proportion of true positives. Specificity is the probability of correctly determining the absence of a condition. (From Last, Dictionary of Epidemiology, 2d ed)
A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement.
The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.
In screening and diagnostic tests, the probability that a person with a positive test is a true positive (i.e., has the disease), is referred to as the predictive value of a positive test; whereas, the predictive value of a negative test is the probability that the person with a negative test does not have the disease. Predictive value is related to the sensitivity and specificity of the test.
The creation of a visual display of the inside of the entire body of a human or animal for the purposes of diagnostic evaluation. This is most commonly achieved by using MAGNETIC RESONANCE IMAGING; or POSITRON EMISSION TOMOGRAPHY.
A nonmetallic, diatomic gas that is a trace element and member of the halogen family. It is used in dentistry as flouride (FLUORIDES) to prevent dental caries.
Methods which attempt to express in replicable terms the extent of the neoplasm in the patient.
F344 rats are an inbred strain of albino laboratory rats (Rattus norvegicus) that have been widely used in biomedical research due to their consistent and reliable genetic background, which facilitates the study of disease mechanisms and therapeutic interventions.
Unstable isotopes of nitrogen that decay or disintegrate emitting radiation. N atoms with atomic weights 12, 13, 16, 17, and 18 are radioactive nitrogen isotopes.
Non-invasive method of demonstrating internal anatomy based on the principle that atomic nuclei in a strong magnetic field absorb pulses of radiofrequency energy and emit them as radiowaves which can be reconstructed into computerized images. The concept includes proton spin tomographic techniques.
Unstable isotopes of carbon that decay or disintegrate emitting radiation. C atoms with atomic weights 10, 11, and 14-16 are radioactive carbon isotopes.
The span of viability of a tissue or an organ.
Unstable isotopes of gallium that decay or disintegrate emitting radiation. Ga atoms with atomic weights 63-68, 70 and 72-76 are radioactive gallium isotopes.
Tumors or cancer of the LUNG.
A method of computed tomography that uses radionuclides which emit a single photon of a given energy. The camera is rotated 180 or 360 degrees around the patient to capture images at multiple positions along the arc. The computer is then used to reconstruct the transaxial, sagittal, and coronal images from the 3-dimensional distribution of radionuclides in the organ. The advantages of SPECT are that it can be used to observe biochemical and physiological processes as well as size and volume of the organ. The disadvantage is that, unlike positron-emission tomography where the positron-electron annihilation results in the emission of 2 photons at 180 degrees from each other, SPECT requires physical collimation to line up the photons, which results in the loss of many available photons and hence degrades the image.
Tumors or cancer of the MEDIASTINUM.
Electronic instruments that produce photographs or cathode-ray tube images of the gamma-ray emissions from organs containing radionuclide tracers.
INFLAMMATION of any ARTERIES.
Transfer of a neoplasm from its primary site to lymph nodes or to distant parts of the body by way of the lymphatic system.
Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.
Unstable isotopes of thallium that decay or disintegrate emitting radiation. Tl atoms with atomic weights 198-202, 204, and 206-210 are thallium radioisotopes.
A membrane in the midline of the THORAX of mammals. It separates the lungs between the STERNUM in front and the VERTEBRAL COLUMN behind. It also surrounds the HEART, TRACHEA, ESOPHAGUS, THYMUS, and LYMPH NODES.
A non-inherited congenital condition with vascular and neurological abnormalities. It is characterized by facial vascular nevi (PORT-WINE STAIN), and capillary angiomatosis of intracranial membranes (MENINGES; CHOROID). Neurological features include EPILEPSY; cognitive deficits; GLAUCOMA; and visual defects.
A plasmid whose presence in the cell, either extrachromosomal or integrated into the BACTERIAL CHROMOSOME, determines the "sex" of the bacterium, host chromosome mobilization, transfer via conjugation (CONJUGATION, GENETIC) of genetic material, and the formation of SEX PILI.
A prediction of the probable outcome of a disease based on a individual's condition and the usual course of the disease as seen in similar situations.
A single lung lesion that is characterized by a small round mass of tissue, usually less than 1 cm in diameter, and can be detected by chest radiography. A solitary pulmonary nodule can be associated with neoplasm, tuberculosis, cyst, or other anomalies in the lung, the CHEST WALL, or the PLEURA.
A catecholamine derivative with specificity for BETA-1 ADRENERGIC RECEPTORS. It is commonly used as a cardiotonic agent after CARDIAC SURGERY and during DOBUTAMINE STRESS ECHOCARDIOGRAPHY.
A technique of inputting two-dimensional images into a computer and then enhancing or analyzing the imagery into a form that is more useful to the human observer.
The making of a radiograph of an object or tissue by recording on a photographic plate the radiation emitted by radioactive material within the object. (Dorland, 27th ed)
Evaluation undertaken to assess the results or consequences of management and procedures used in combating disease in order to determine the efficacy, effectiveness, safety, and practicability of these interventions in individual cases or series.
Isoprostanes derived from the free radical oxidation of ARACHIDONIC ACID. Although similar in structure to enzymatically synthesized prostaglandin F2alpha (DINOPROST), they occur through non-enzymatic oxidation of cell membrane lipids.
Studies used to test etiologic hypotheses in which inferences about an exposure to putative causal factors are derived from data relating to characteristics of persons under study or to events or experiences in their past. The essential feature is that some of the persons under study have the disease or outcome of interest and their characteristics are compared with those of unaffected persons.
The local recurrence of a neoplasm following treatment. It arises from microscopic cells of the original neoplasm that have escaped therapeutic intervention and later become clinically visible at the original site.
A nitroimidazole that sensitizes normally radio-resistant hypoxic cells to radiation. It may also be directly cytotoxic to hypoxic cells and has been proposed as an antineoplastic.
A malignant disease characterized by progressive enlargement of the lymph nodes, spleen, and general lymphoid tissue. In the classical variant, giant usually multinucleate Hodgkin's and REED-STERNBERG CELLS are present; in the nodular lymphocyte predominant variant, lymphocytic and histiocytic cells are seen.
Fever in which the etiology cannot be ascertained.
Small masses of chromaffin cells found near the SYMPATHETIC GANGLIA along the ABDOMINAL AORTA, beginning cranial to the superior mesenteric artery (MESENTERIC ARTERY, SUPERIOR) or renal arteries and extending to the level of the aortic bifurcation or just beyond. They are also called the organs of Zuckerkandl and sometimes called aortic bodies (not to be confused with AORTIC BODIES in the THORAX). The para-aortic bodies are the dominant source of CATECHOLAMINES in the FETUS and normally regress after BIRTH.
A degenerative disease of the BRAIN characterized by the insidious onset of DEMENTIA. Impairment of MEMORY, judgment, attention span, and problem solving skills are followed by severe APRAXIAS and a global loss of cognitive abilities. The condition primarily occurs after age 60, and is marked pathologically by severe cortical atrophy and the triad of SENILE PLAQUES; NEUROFIBRILLARY TANGLES; and NEUROPIL THREADS. (From Adams et al., Principles of Neurology, 6th ed, pp1049-57)
Unanticipated information discovered in the course of testing or medical care. Used in discussions of information that may have social or psychological consequences, such as when it is learned that a child's biological father is someone other than the putative father, or that a person tested for one disease or disorder has, or is at risk for, something else.
The hollow, muscular organ that maintains the circulation of the blood.
The statistical reproducibility of measurements (often in a clinical context), including the testing of instrumentation or techniques to obtain reproducible results. The concept includes reproducibility of physiological measurements, which may be used to develop rules to assess probability or prognosis, or response to a stimulus; reproducibility of occurrence of a condition; and reproducibility of experimental results.
Remnant of a tumor or cancer after primary, potentially curative therapy. (Dr. Daniel Masys, written communication)
The restoration of blood supply to the myocardium. (From Dorland, 28th ed)
Isotopes that exhibit radioactivity and undergo radioactive decay. (From Grant & Hackh's Chemical Dictionary, 5th ed & McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
A general term for various neoplastic diseases of the lymphoid tissue.
Neoplasms of whatever cell type or origin, occurring in the extraskeletal connective tissue framework of the body including the organs of locomotion and their various component structures, such as nerves, blood vessels, lymphatics, etc.
Aniline compounds, also known as aromatic amines, are organic chemicals derived from aniline (aminobenzene), characterized by the substitution of hydrogen atoms in the benzene ring with amino groups (-NH2).
Studies in which individuals or populations are followed to assess the outcome of exposures, procedures, or effects of a characteristic, e.g., occurrence of disease.
A heterogeneous aggregate of at least three distinct histological types of lung cancer, including SQUAMOUS CELL CARCINOMA; ADENOCARCINOMA; and LARGE CELL CARCINOMA. They are dealt with collectively because of their shared treatment strategy.
A sulfur-containing essential L-amino acid that is important in many body functions.
Accumulation of a drug or chemical substance in various organs (including those not relevant to its pharmacologic or therapeutic action). This distribution depends on the blood flow or perfusion rate of the organ, the ability of the drug to penetrate organ membranes, tissue specificity, protein binding. The distribution is usually expressed as tissue to plasma ratios.
Any of a group of malignant tumors of lymphoid tissue that differ from HODGKIN DISEASE, being more heterogeneous with respect to malignant cell lineage, clinical course, prognosis, and therapy. The only common feature among these tumors is the absence of giant REED-STERNBERG CELLS, a characteristic of Hodgkin's disease.
Positive test results in subjects who do not possess the attribute for which the test is conducted. The labeling of healthy persons as diseased when screening in the detection of disease. (Last, A Dictionary of Epidemiology, 2d ed)
Tumors or cancer located in bone tissue or specific BONES.
Non-invasive methods of visualizing the CENTRAL NERVOUS SYSTEM, especially the brain, by various imaging modalities.
Combination or superimposition of two images for demonstrating differences between them (e.g., radiograph with contrast vs. one without, radionuclide images using different radionuclides, radiograph vs. radionuclide image) and in the preparation of audiovisual materials (e.g., offsetting identical images, coloring of vessels in angiograms).
A guanidine analog with specific affinity for tissues of the sympathetic nervous system and related tumors. The radiolabeled forms are used as antineoplastic agents and radioactive imaging agents. (Merck Index, 12th ed) MIBG serves as a neuron-blocking agent which has a strong affinity for, and retention in, the adrenal medulla and also inhibits ADP-ribosyltransferase.
Any visual display of structural or functional patterns of organs or tissues for diagnostic evaluation. It includes measuring physiologic and metabolic responses to physical and chemical stimuli, as well as ultramicroscopy.
The use of two or more chemicals simultaneously or sequentially in the drug therapy of neoplasms. The drugs need not be in the same dosage form.
The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.
A malignant epithelial tumor with a glandular organization.
An enzyme that catalyzes the conversion of ATP and a D-hexose to ADP and a D-hexose 6-phosphate. D-Glucose, D-mannose, D-fructose, sorbitol, and D-glucosamine can act as acceptors; ITP and dATP can act as donors. The liver isoenzyme has sometimes been called glucokinase. (From Enzyme Nomenclature, 1992) EC 2.7.1.1.
Neoplasms of the thin serous membrane that envelopes the lungs and lines the thoracic cavity. Pleural neoplasms are exceedingly rare and are usually not diagnosed until they are advanced because in the early stages they produce no symptoms.
Care given during the period prior to undergoing surgery when psychological and physical preparations are made according to the special needs of the individual patient. This period spans the time between admission to the hospital to the time the surgery begins. (From Dictionary of Health Services Management, 2d ed)
Nucleosides that have two hydroxy groups removed from the sugar moiety. The majority of these compounds have broad-spectrum antiretroviral activity due to their action as antimetabolites. The nucleosides are phosphorylated intracellularly to their 5'-triphosphates and act as chain-terminating inhibitors of viral reverse transcription.
A technetium imaging agent used to reveal blood-starved cardiac tissue during a heart attack.
A carcinoma derived from stratified SQUAMOUS EPITHELIAL CELLS. It may also occur in sites where glandular or columnar epithelium is normally present. (From Stedman, 25th ed)
They are oval or bean shaped bodies (1 - 30 mm in diameter) located along the lymphatic system.

Comparative efficacy of positron emission tomography with FDG and computed tomographic scanning in preoperative staging of non-small cell lung cancer. (1/3939)

OBJECTIVE: To determine the sensitivity, specificity, and accuracy of positron emission tomography with 2-fluorine-18-fluorodeoxyglucose (PET-FDG) in the preoperative staging (N and M staging) of patients with lung cancer. The authors wanted to compare the efficacy of PET scanning with currently used computed tomography (CT) scanning. MATERIALS AND METHODS: Results of whole-body PET-FDG imaging and CT scans were compared with histologic findings for the presence or absence of lymph node disease or metastatic sites. Sampling of mediastinal lymph nodes was performed using mediastinoscopy or thoracotomy. RESULTS: PET-FDG imaging was significantly more sensitive, specific, and accurate for detecting N disease than CT. PET changed N staging in 35% and M staging in 11% of patients. CT scans helped in accurate anatomic localization of 6/57 PET lymph node abnormalities. CONCLUSION: PET-FDG is a reliable method for preoperative staging of patients with lung cancer and would help to optimize management of these patients. Accurate lymph node staging of lung cancer may be ideally performed by simultaneous review of PET and CT scans.  (+info)

Enhanced myocardial glucose use in patients with a deficiency in long-chain fatty acid transport (CD36 deficiency). (2/3939)

CD36 is a multifunctional, 88 kDa glycoprotein that is expressed on platelets and monocytes/macrophages. CD36 also has high homology with the long-chain fatty acid (LFA) transporter in the myocardium. Although platelet and monocyte CD36 levels can indicate a CD36 deficiency, they cannot predict specific clinical manifestations in the myocardium of a given person. We examined the hypothesis that a deficiency in LFA transport augments myocardial glucose uptake in patients with a type I CD36 deficiency. METHODS: Seven fasting patients with a type I CD36 deficiency and 9 controls were assessed by cardiac radionuclide imaging using beta-methyl-p-iodophenyl-pentadecanoic acid (BMIPP) as a LFA tracer and by PET with 18F-fluorodeoxyglucose (FDG). RESULTS: None of the patients with a CD36 deficiency showed myocardial uptake of BMIPP. The percentage dose uptake of BMIPP in these subjects was significantly lower than that in normal controls (1.31+/-0.24 versus 2.90+/-0.2; P < 0.005). PET studies revealed that myocardial FDG accumulation was substantially increased in patients with a CD36 deficiency. Quantitative analysis showed that the percentage dose uptake of FDG in patients with a CD36 deficiency was significantly higher than that in normal controls (1.28+/-0.35 versus 0.43+/-0.22; P< 0.01). CONCLUSION: CD36 functions as a major myocardial LFA transporter and its absence may cause a compensatory upregulation of myocardial glucose uptake.  (+info)

Detection of liver metastases from pancreatic cancer using FDG PET. (3/3939)

We evaluated the potential of the glucose analog [18F]fluorodeoxyglucose (FDG) as a PET tracer for the hepatic staging in 168 patients designated for resective pancreatic surgery. METHODS: Metastatic liver disease was confirmed or excluded during surgery or with CT follow-up for at least 6 mo. Proven metastases were then retrospectively identified on preoperative CT (gold standard). Hepatic PET scans of all patients were interpreted blindly. Any focal FDG uptake was considered malignant. Both proven hepatic metastases and suspicious hepatic PET lesions were then compared, lesion by lesion, with CT. Standardized uptake values (SUV) and tumor-to-liver ratios (T/L) were determined for the most intense lesion of each patient. RESULTS: Sensitivity of FDG PET was 68% (15 of 22 patients). The lesion detection rate was 97% (28 of 29 metastases) for lesions >1 cm and 43% (16 of 37 metastases) for lesions < or = 1 cm. Specificity was 95% (138 of 146 patients). Six of eight patients with false-positive results had marked intrahepatic cholestasis (versus 3 of 15 patients with true-positive lesions), one had an infrahepatic abscess and one had a right basal pulmonary metastasis. The SUV and T/L were 4.6+/-1.4 and 2.3+/-1.1, respectively, for malignant lesions and 4.1+/-1.5 and 1.9+/-0.3, respectively, for false-positive lesions and therefore are of limited value. CONCLUSION: FDG PET provides reliable hepatic staging for lesions >1 cm. False-positive results are associated with the presence of marked intrahepatic cholestasis. For lesions < or = 1 cm, FDG PET can define malignancy in 43% of suspicious CT lesions in the absence of dilated bile ducts.  (+info)

Synthesis and evaluation of [18F]1-amino-3-fluorocyclobutane-1-carboxylic acid to image brain tumors. (4/3939)

We have developed a new tumor-avid amino acid, 1-amino-3-fluorocyclobutane-1-carboxylic acid (FACBC), labeled with 18F for nuclear medicine imaging. METHODS: [18F]FACBC was prepared with high specific activity (no carrier added [NCA]) and was evaluated for its potential in tumor localization. A comparative study was performed for [18F]FACBC and [18F]2-fluorodeoxyglucose (FDG) in which the uptake of each agent in 9L gliosarcoma (implanted intracerebrally in Fisher 344 rats) was measured. In addition, the first human PET study of [18F]FACBC was performed on a patient with residual glioblastoma multiforme. Quantitative brain images of the patient were obtained by using a Siemens 921 47-slice PET imaging system. RESULTS: In the rat brain, the initial level of radioactivity accumulation after injection of [18F]FACBC was low (0.11 percentage injected dose per gram [%ID/g]) at 5 min and increased slightly to 0.26 %ID/g at 60 min. The tumor uptake exhibited a maximum at 60 min (1.72 %ID/g), resulting in a tumor-to-brain ratio increase of 5.58 at 5 min to 6.61 at 60 min. In the patient, the uptake of [18F]FACBC in the tumor exhibited a maximum concentration of 146 nCi/mL at 35 min after injection. The uptake of radioactivity in the normal brain tissue was low, 21 nCi/mL at 15 min after injection, and gradually increased to 29 nCi/mL at 60 min after injection. The ratio of tumor to normal tissue was 6 at 20 min after injection. The [18F]FACBC PET scan showed intense uptake in the left frontal region of the brain. CONCLUSION: The amino acid FACBC can be radiofluorinated for clinical use. [18F]FACBC is a potential PET tracer for tumor imaging.  (+info)

Mechanisms related to [18F]fluorodeoxyglucose uptake of human colon cancers transplanted in nude mice. (5/3939)

[18F]Fluorodeoxyglucose ([18F]FDG), a glucose analogue, has been widely used for tumor imaging. To investigate the mechanisms related to [18F]FDG uptake by tumors, an experiment involving nude mice was performed. METHODS: Human colon cancer cell lines SNU-C2A, SNU-C4 and SNU-C5 were transplanted to nude mice. Using immunohistochemical staining and Western blot, the expression of glucose transporter (Glut) isoforms (Glut-1 through -5) in xenografted tumors was analyzed. For the analysis of messenger ribonucleic acid (mRNA) expression, reverse-transcription polymerase chain reaction and Northern blot were used and the enzyme activity of hexokinase in cancer tissues was measured by continuous spectrophotometric rate determination. RESULTS: [18F]FDG uptake in SNU-C4 and SNU-C5 cells was higher than in normal colon cells. Among these cells and xenografted tumors, SNU-C5 showed the highest level of [18F]FDG uptake, followed by SNU-C4 and SNU-C2A. An immunostaining experiment showed intense staining of Glut-1 in SNU-C5 tumors but somewhat faint staining in SNU-C4. SNU-C5 tumors also showed positive staining with Glut-3, although this was not the case with SNU-C2A and SNU-C4. Western blot analysis showed the expression of Glut-1 and Glut-3 in all tumors. Experiments involving Northern blot analysis and reverse-transcription polymerase chain reaction confirmed the overexpression of Glut-1 mRNA in all tumors, with the highest level in SNU-C5. The level of Glut-3 mRNA was also elevated in SNU-C5 tumors but not in SNU-C2A and SNU-C4. The enzyme activity of hexokinase did not vary among different tumors. CONCLUSION: Gluts, especially Glut-1, are responsible for [18F]FDG uptake in a nude mouse model of colon cancer rather than hexokinase activity. Increased numbers of glucose transporters at the plasma membrane of cancer cells is attributed to an increased level of transcripts of glucose transporter genes and may be a cause of increased [18F]FDG uptake, at least in colon cancer tumors.  (+info)

Use of positron emission tomography in evaluation of brachial plexopathy in breast cancer patients. (6/3939)

18-Fluoro-2-deoxyglucose (FDG) positron emission tomography (PET) has previously been used successfully to image primary and metastatic breast cancer. In this pilot study, 19 breast cancer patients with symptoms/signs referrable to the brachial plexus were evaluated with 18FDG-PET. In 11 cases computerized tomography (CT) scanning was also performed. Of the 19 patients referred for PET study, 14 had abnormal uptake of 18FDG in the region of the symptomatic plexus. Four patients had normal PET studies and one had increased FDG uptake in the chest wall that accounted for her axillary pain. CT scans were performed in 9 of the 14 patients who had positive brachial plexus PET studies; six of these were either normal or showed no clear evidence of recurrent disease, while three CTs demonstrated clear brachial plexus involvement. Of two of the four patients with normal PET studies, one has had complete resolution of symptoms untreated while the other was found to have cervical disc herniation on magnetic resonance imaging (MRI) scan. The remaining two patients almost certainly had radiation-induced plexopathy and had normal CT, MRI and PET study. These data suggest that 18FDG-PET scanning is a useful tool in evaluation of patients with suspected metastatic plexopathy, particularly if other imaging studies are normal. It may also be useful in distinguishing between radiation-induced and metastatic plexopathy.  (+info)

Imaging adenoviral-directed reporter gene expression in living animals with positron emission tomography. (7/3939)

We are developing quantitative assays to repeatedly and noninvasively image expression of reporter genes in living animals, using positron emission tomography (PET). We synthesized positron-emitting 8-[18F]fluoroganciclovir (FGCV) and demonstrated that this compound is a substrate for the herpes simplex virus 1 thymidine kinase enzyme (HSV1-TK). Using positron-emitting FGCV as a PET reporter probe, we imaged adenovirus-directed hepatic expression of the HSV1-tk reporter gene in living mice. There is a significant positive correlation between the percent injected dose of FGCV retained per gram of liver and the levels of hepatic HSV1-tk reporter gene expression (r2 > 0.80). Over a similar range of HSV1-tk expression in vivo, the percent injected dose retained per gram of liver was 0-23% for ganciclovir and 0-3% for FGCV. Repeated, noninvasive, and quantitative imaging of PET reporter gene expression should be a valuable tool for studies of human gene therapy, of organ/cell transplantation, and of both environmental and behavioral modulation of gene expression in transgenic mice.  (+info)

Reciprocal ST-segment depression associated with exercise-induced ST-segment elevation indicates residual viability after myocardial infarction. (8/3939)

OBJECTIVES: We evaluated the clinical significance of reciprocal ST-segment depression associated with exercise-induced ST-segment elevation for detecting residual viability within the infarcted area. BACKGROUND: Although the relation between residual viability and exercise-induced ST-segment elevation has been described, there are no reports focusing on the relation between myocardial viability and reciprocal ST-segment depression associated with exercise-induced ST-segment elevation. METHODS: We evaluated regional blood flow and glucose utilization using N-13 ammonia (NH3) and F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) in 30 patients with a previous Q-wave myocardial infarction (anterior in 15, inferior in 15). All subjects had single-vessel disease and had exercise-induced ST-segment elevations (> or =1 mm) in electrocardiographic leads. RESULTS: Reciprocal ST-segment depression (> or =1 mm) was present in 16 patients (Group A; anterior in 6, inferior in 10) but not in the remaining 14 patients (Group B). The degree of exercise-induced ST-segment elevation (1.8+/-0.2 vs. 2.0+/-0.2 mm) and the time from the onset of infarction to the study (75+/-49 vs. 74+/-52 days) did not differ between groups. There were no significant differences between groups in the severity of left ventricular dysfunction and the residual luminal narrowing in the infarct-related artery (45+/-21 vs. 48+/-25%). The presence and site of infarction were confirmed by NH3-PET in all patients. FDG-PET demonstrated residual tissue viability within infarct-related area in all patients in Group A and in 3 (21%) of 14 patients in Group B (p < 0.01). The sensitivity, specificity and accuracy of reciprocal ST-segment depression associated with exercise-induced ST-segment elevation for detecting residual viability were 84%, 100% and 90%, respectively. CONCLUSIONS: The occurrence of reciprocal ST-segment depression associated with exercise-induced ST segment elevation in patients with a previous Q-wave infarction who had single-vessel disease indicates residual tissue viability within the infarct-related area.  (+info)

Fluorodeoxyglucose F18 (FDG-18) is not a medical condition, but a radiopharmaceutical used in medical imaging. It is a type of glucose (a simple sugar) that has been chemically combined with a small amount of a radioactive isotope called fluorine-18.

FDG-18 is used in positron emission tomography (PET) scans to help identify areas of the body where cells are using more energy than normal, such as cancerous tumors. The FDG-18 is injected into the patient's vein and travels throughout the body. Because cancer cells often use more glucose than normal cells, they tend to absorb more FDG-18.

Once inside the body, the FDG-18 emits positrons, which interact with electrons in nearby tissue, producing gamma rays that can be detected by a PET scanner. The resulting images can help doctors locate and assess the size and activity of cancerous tumors, as well as monitor the effectiveness of treatment.

Positron-Emission Tomography (PET) is a type of nuclear medicine imaging that uses small amounts of radioactive material, called a radiotracer, to produce detailed, three-dimensional images. This technique measures metabolic activity within the body, such as sugar metabolism, to help distinguish between healthy and diseased tissue, identify cancerous cells, or examine the function of organs.

During a PET scan, the patient is injected with a radiotracer, typically a sugar-based compound labeled with a positron-emitting radioisotope, such as fluorine-18 (^18^F). The radiotracer accumulates in cells that are metabolically active, like cancer cells. As the radiotracer decays, it emits positrons, which then collide with electrons in nearby tissue, producing gamma rays. A special camera, called a PET scanner, detects these gamma rays and uses this information to create detailed images of the body's internal structures and processes.

PET is often used in conjunction with computed tomography (CT) or magnetic resonance imaging (MRI) to provide both functional and anatomical information, allowing for more accurate diagnosis and treatment planning. Common applications include detecting cancer recurrence, staging and monitoring cancer, evaluating heart function, and assessing brain function in conditions like dementia and epilepsy.

Radiopharmaceuticals are defined as pharmaceutical preparations that contain radioactive isotopes and are used for diagnosis or therapy in nuclear medicine. These compounds are designed to interact specifically with certain biological targets, such as cells, tissues, or organs, and emit radiation that can be detected and measured to provide diagnostic information or used to destroy abnormal cells or tissue in therapeutic applications.

The radioactive isotopes used in radiopharmaceuticals have carefully controlled half-lives, which determine how long they remain radioactive and how long the pharmaceutical preparation remains effective. The choice of radioisotope depends on the intended use of the radiopharmaceutical, as well as factors such as its energy, range of emission, and chemical properties.

Radiopharmaceuticals are used in a wide range of medical applications, including imaging, cancer therapy, and treatment of other diseases and conditions. Examples of radiopharmaceuticals include technetium-99m for imaging the heart, lungs, and bones; iodine-131 for treating thyroid cancer; and samarium-153 for palliative treatment of bone metastases.

The use of radiopharmaceuticals requires specialized training and expertise in nuclear medicine, as well as strict adherence to safety protocols to minimize radiation exposure to patients and healthcare workers.

Emission computed tomography (ECT) is a type of tomographic imaging technique in which an emission signal from within the body is detected to create cross-sectional images of that signal's distribution. In Emission-Computed Tomography (ECT), a radionuclide is introduced into the body, usually through injection, inhalation or ingestion. The radionuclide emits gamma rays that are then detected by external gamma cameras.

The data collected from these cameras is then used to create cross-sectional images of the distribution of the radiopharmaceutical within the body. This allows for the identification and quantification of functional information about specific organs or systems within the body, such as blood flow, metabolic activity, or receptor density.

One common type of Emission-Computed Tomography is Single Photon Emission Computed Tomography (SPECT), which uses a single gamma camera that rotates around the patient to collect data from multiple angles. Another type is Positron Emission Tomography (PET), which uses positron-emitting radionuclides and detects the coincident gamma rays emitted by the annihilation of positrons and electrons.

Overall, ECT is a valuable tool in medical imaging for diagnosing and monitoring various diseases, including cancer, heart disease, and neurological disorders.

Fluorine radioisotopes are radioactive isotopes or variants of the chemical element Fluorine (F, atomic number 9). These radioisotopes have an unstable nucleus that emits radiation in the form of alpha particles, beta particles, or gamma rays. Examples of Fluorine radioisotopes include Fluorine-18 and Fluorine-19.

Fluorine-18 is a positron-emitting radionuclide with a half-life of approximately 110 minutes, making it useful for medical imaging techniques such as Positron Emission Tomography (PET) scans. It is commonly used in the production of fluorodeoxyglucose (FDG), a radiopharmaceutical that can be used to detect cancer and other metabolic disorders.

Fluorine-19, on the other hand, is a stable isotope of Fluorine and does not emit radiation. However, it can be enriched and used as a non-radioactive tracer in medical research and diagnostic applications.

Deoxyglucose is a glucose molecule that has had one oxygen atom removed, resulting in the absence of a hydroxyl group (-OH) at the 2' position of the carbon chain. It is used in research and medical settings as a metabolic tracer to study glucose uptake and metabolism in cells and organisms.

Deoxyglucose can be taken up by cells through glucose transporters, but it cannot be further metabolized by glycolysis or other glucose-utilizing pathways. This leads to the accumulation of deoxyglucose within the cell, which can interfere with normal cellular processes and cause toxicity in high concentrations.

In medical research, deoxyglucose is sometimes labeled with radioactive isotopes such as carbon-14 or fluorine-18 to create radiolabeled deoxyglucose (FDG), which can be used in positron emission tomography (PET) scans to visualize and measure glucose uptake in tissues. This technique is commonly used in cancer imaging, as tumors often have increased glucose metabolism compared to normal tissue.

Deoxy sugars, also known as deoxyriboses, are sugars that have one or more hydroxyl (-OH) groups replaced by a hydrogen atom. The most well-known deoxy sugar is deoxyribose, which is a component of DNA (deoxyribonucleic acid).

Deoxyribose is a pentose sugar, meaning it has five carbon atoms, and it differs from the related sugar ribose by having a hydrogen atom instead of a hydroxyl group at the 2' position. This structural difference affects the ability of DNA to form double-stranded helices through hydrogen bonding between complementary base pairs, which is critical for the storage and replication of genetic information.

Other deoxy sugars may also be important in biology, such as L-deoxyribose, a component of certain antibiotics, and various deoxyhexoses, which are found in some natural products and bacterial polysaccharides.

Multimodal imaging is a medical term that refers to the combination of two or more imaging techniques to obtain complementary information about the structure, function, and/or physiology of tissues, organs, or organ systems. This approach allows for a more comprehensive assessment of normal and abnormal processes in the body than can be achieved with any single imaging modality alone.

Commonly used imaging modalities in multimodal imaging include computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), single-photon emission computed tomography (SPECT), ultrasound, and optical imaging techniques. Each modality provides unique information that can be integrated to improve diagnostic accuracy, guide treatment planning, and monitor response to therapy.

For example, a patient with a suspected brain tumor may undergo both MRI and PET scans. The MRI provides detailed anatomical information about the size, shape, and location of the tumor, while the PET scan shows metabolic activity within the tumor, which can help distinguish between benign and malignant lesions.

Multimodal imaging is also used in research settings to study various physiological processes, such as blood flow, oxygenation, and neurotransmission, in both health and disease.

X-ray computed tomography (CT or CAT scan) is a medical imaging method that uses computer-processed combinations of many X-ray images taken from different angles to produce cross-sectional (tomographic) images (virtual "slices") of the body. These cross-sectional images can then be used to display detailed internal views of organs, bones, and soft tissues in the body.

The term "computed tomography" is used instead of "CT scan" or "CAT scan" because the machines take a series of X-ray measurements from different angles around the body and then use a computer to process these data to create detailed images of internal structures within the body.

CT scanning is a noninvasive, painless medical test that helps physicians diagnose and treat medical conditions. CT imaging provides detailed information about many types of tissue including lung, bone, soft tissue and blood vessels. CT examinations can be performed on every part of the body for a variety of reasons including diagnosis, surgical planning, and monitoring of therapeutic responses.

In computed tomography (CT), an X-ray source and detector rotate around the patient, measuring the X-ray attenuation at many different angles. A computer uses this data to construct a cross-sectional image by the process of reconstruction. This technique is called "tomography". The term "computed" refers to the use of a computer to reconstruct the images.

CT has become an important tool in medical imaging and diagnosis, allowing radiologists and other physicians to view detailed internal images of the body. It can help identify many different medical conditions including cancer, heart disease, lung nodules, liver tumors, and internal injuries from trauma. CT is also commonly used for guiding biopsies and other minimally invasive procedures.

In summary, X-ray computed tomography (CT or CAT scan) is a medical imaging technique that uses computer-processed combinations of many X-ray images taken from different angles to produce cross-sectional images of the body. It provides detailed internal views of organs, bones, and soft tissues in the body, allowing physicians to diagnose and treat medical conditions.

Sensitivity and specificity are statistical measures used to describe the performance of a diagnostic test or screening tool in identifying true positive and true negative results.

* Sensitivity refers to the proportion of people who have a particular condition (true positives) who are correctly identified by the test. It is also known as the "true positive rate" or "recall." A highly sensitive test will identify most or all of the people with the condition, but may also produce more false positives.
* Specificity refers to the proportion of people who do not have a particular condition (true negatives) who are correctly identified by the test. It is also known as the "true negative rate." A highly specific test will identify most or all of the people without the condition, but may also produce more false negatives.

In medical testing, both sensitivity and specificity are important considerations when evaluating a diagnostic test. High sensitivity is desirable for screening tests that aim to identify as many cases of a condition as possible, while high specificity is desirable for confirmatory tests that aim to rule out the condition in people who do not have it.

It's worth noting that sensitivity and specificity are often influenced by factors such as the prevalence of the condition in the population being tested, the threshold used to define a positive result, and the reliability and validity of the test itself. Therefore, it's important to consider these factors when interpreting the results of a diagnostic test.

Glucose is a simple monosaccharide (or single sugar) that serves as the primary source of energy for living organisms. It's a fundamental molecule in biology, often referred to as "dextrose" or "grape sugar." Glucose has the molecular formula C6H12O6 and is vital to the functioning of cells, especially those in the brain and nervous system.

In the body, glucose is derived from the digestion of carbohydrates in food, and it's transported around the body via the bloodstream to cells where it can be used for energy. Cells convert glucose into a usable form through a process called cellular respiration, which involves a series of metabolic reactions that generate adenosine triphosphate (ATP)—the main currency of energy in cells.

Glucose is also stored in the liver and muscles as glycogen, a polysaccharide (multiple sugar) that can be broken down back into glucose when needed for energy between meals or during physical activity. Maintaining appropriate blood glucose levels is crucial for overall health, and imbalances can lead to conditions such as diabetes mellitus.

The brain is the central organ of the nervous system, responsible for receiving and processing sensory information, regulating vital functions, and controlling behavior, movement, and cognition. It is divided into several distinct regions, each with specific functions:

1. Cerebrum: The largest part of the brain, responsible for higher cognitive functions such as thinking, learning, memory, language, and perception. It is divided into two hemispheres, each controlling the opposite side of the body.
2. Cerebellum: Located at the back of the brain, it is responsible for coordinating muscle movements, maintaining balance, and fine-tuning motor skills.
3. Brainstem: Connects the cerebrum and cerebellum to the spinal cord, controlling vital functions such as breathing, heart rate, and blood pressure. It also serves as a relay center for sensory information and motor commands between the brain and the rest of the body.
4. Diencephalon: A region that includes the thalamus (a major sensory relay station) and hypothalamus (regulates hormones, temperature, hunger, thirst, and sleep).
5. Limbic system: A group of structures involved in emotional processing, memory formation, and motivation, including the hippocampus, amygdala, and cingulate gyrus.

The brain is composed of billions of interconnected neurons that communicate through electrical and chemical signals. It is protected by the skull and surrounded by three layers of membranes called meninges, as well as cerebrospinal fluid that provides cushioning and nutrients.

The Predictive Value of Tests, specifically the Positive Predictive Value (PPV) and Negative Predictive Value (NPV), are measures used in diagnostic tests to determine the probability that a positive or negative test result is correct.

Positive Predictive Value (PPV) is the proportion of patients with a positive test result who actually have the disease. It is calculated as the number of true positives divided by the total number of positive results (true positives + false positives). A higher PPV indicates that a positive test result is more likely to be a true positive, and therefore the disease is more likely to be present.

Negative Predictive Value (NPV) is the proportion of patients with a negative test result who do not have the disease. It is calculated as the number of true negatives divided by the total number of negative results (true negatives + false negatives). A higher NPV indicates that a negative test result is more likely to be a true negative, and therefore the disease is less likely to be present.

The predictive value of tests depends on the prevalence of the disease in the population being tested, as well as the sensitivity and specificity of the test. A test with high sensitivity and specificity will generally have higher predictive values than a test with low sensitivity and specificity. However, even a highly sensitive and specific test can have low predictive values if the prevalence of the disease is low in the population being tested.

Whole Body Imaging (WBI) is a diagnostic technique that involves obtaining images of the entire body or significant portions of it, typically for the purpose of detecting abnormalities such as tumors, fractures, infections, or other diseases. This can be achieved through various imaging modalities including:

1. Whole Body Computed Tomography (WBCT): This is a series of CT scans taken from head to toe to create detailed cross-sectional images of the body. It's often used in trauma situations to identify internal injuries.

2. Whole Body Magnetic Resonance Imaging (WBMRI): This uses magnetic fields and radio waves to produce detailed images of the body's internal structures. It's particularly useful for detecting soft tissue abnormalities.

3. Positron Emission Tomography - Computed Tomography (PET-CT): This combines PET and CT scans to create detailed, 3D images of the body's functional processes, such as metabolism or blood flow. It's often used in cancer diagnosis and staging.

4. Whole Body Bone Scan: This uses a small amount of radioactive material to highlight areas of increased bone turnover, which can indicate conditions like fractures, tumors, or infections.

5. Whole Body PET: Similar to WBMRI, this uses positron emission tomography to create detailed images of the body's metabolic processes, but it doesn't provide the same level of anatomical detail as PET-CT.

It's important to note that while WBI can be a powerful diagnostic tool, it also involves higher doses of radiation (in the case of WBCT and Whole Body Bone Scan) and greater costs compared to single or limited area imaging studies. Therefore, its use is typically reserved for specific clinical scenarios where the benefits outweigh the risks and costs.

Fluorine is not a medical term itself, but it is a chemical element that is often discussed in the context of dental health. Here's a brief scientific/chemical definition:

Fluorine is a chemical element with the symbol F and atomic number 9. It is the most reactive and electronegative of all elements. Fluorine is never found in its free state in nature, but it is abundant in minerals such as fluorspar (calcium fluoride).

In dental health, fluoride, which is a compound containing fluorine, is used to help prevent tooth decay. It can be found in many water supplies, some foods, and various dental products like toothpaste and mouthwash. Fluoride works by strengthening the enamel on teeth, making them more resistant to acid attacks that can lead to cavities.

Neoplasm staging is a systematic process used in medicine to describe the extent of spread of a cancer, including the size and location of the original (primary) tumor and whether it has metastasized (spread) to other parts of the body. The most widely accepted system for this purpose is the TNM classification system developed by the American Joint Committee on Cancer (AJCC) and the Union for International Cancer Control (UICC).

In this system, T stands for tumor, and it describes the size and extent of the primary tumor. N stands for nodes, and it indicates whether the cancer has spread to nearby lymph nodes. M stands for metastasis, and it shows whether the cancer has spread to distant parts of the body.

Each letter is followed by a number that provides more details about the extent of the disease. For example, a T1N0M0 cancer means that the primary tumor is small and has not spread to nearby lymph nodes or distant sites. The higher the numbers, the more advanced the cancer.

Staging helps doctors determine the most appropriate treatment for each patient and estimate the patient's prognosis. It is an essential tool for communication among members of the healthcare team and for comparing outcomes of treatments in clinical trials.

F344 is a strain code used to designate an outbred stock of rats that has been inbreeded for over 100 generations. The F344 rats, also known as Fischer 344 rats, were originally developed at the National Institutes of Health (NIH) and are now widely used in biomedical research due to their consistent and reliable genetic background.

Inbred strains, like the F344, are created by mating genetically identical individuals (siblings or parents and offspring) for many generations until a state of complete homozygosity is reached, meaning that all members of the strain have identical genomes. This genetic uniformity makes inbred strains ideal for use in studies where consistent and reproducible results are important.

F344 rats are known for their longevity, with a median lifespan of around 27-31 months, making them useful for aging research. They also have a relatively low incidence of spontaneous tumors compared to other rat strains. However, they may be more susceptible to certain types of cancer and other diseases due to their inbred status.

It's important to note that while F344 rats are often used as a standard laboratory rat strain, there can still be some genetic variation between individual animals within the same strain, particularly if they come from different suppliers or breeding colonies. Therefore, it's always important to consider the source and history of any animal model when designing experiments and interpreting results.

Nitrogen radioisotopes are unstable isotopes of the element nitrogen that emit radiation as they decay into more stable forms. Nitrogen has several radioisotopes, with the most common being nitrogen-13 and nitrogen-15. These isotopes have 7 protons in their nucleus, but differ in the number of neutrons.

Nitrogen-13 has a half-life of about 10 minutes, making it useful for medical imaging studies such as positron emission tomography (PET) scans. When nitrogen-13 decays, it emits a positron, which then collides with an electron and produces gamma rays that can be detected by a PET scanner.

Nitrogen-15, on the other hand, has a half-life of about 3 minutes and is not typically used for medical imaging. However, it is widely used in research settings as a stable isotope tracer to study metabolic processes in the body.

It's important to note that handling and using radioisotopes requires specialized training and equipment due to their potential radiation hazards.

Medical Definition:

Magnetic Resonance Imaging (MRI) is a non-invasive diagnostic imaging technique that uses a strong magnetic field and radio waves to create detailed cross-sectional or three-dimensional images of the internal structures of the body. The patient lies within a large, cylindrical magnet, and the scanner detects changes in the direction of the magnetic field caused by protons in the body. These changes are then converted into detailed images that help medical professionals to diagnose and monitor various medical conditions, such as tumors, injuries, or diseases affecting the brain, spinal cord, heart, blood vessels, joints, and other internal organs. MRI does not use radiation like computed tomography (CT) scans.

Carbon radioisotopes are radioactive isotopes of carbon, which is an naturally occurring chemical element with the atomic number 6. The most common and stable isotope of carbon is carbon-12 (^12C), but there are also several radioactive isotopes, including carbon-11 (^11C), carbon-14 (^14C), and carbon-13 (^13C). These radioisotopes have different numbers of neutrons in their nuclei, which makes them unstable and causes them to emit radiation.

Carbon-11 has a half-life of about 20 minutes and is used in medical imaging techniques such as positron emission tomography (PET) scans. It is produced by bombarding nitrogen-14 with protons in a cyclotron.

Carbon-14, also known as radiocarbon, has a half-life of about 5730 years and is used in archaeology and geology to date organic materials. It is produced naturally in the atmosphere by cosmic rays.

Carbon-13 is stable and has a natural abundance of about 1.1% in carbon. It is not radioactive, but it can be used as a tracer in medical research and in the study of metabolic processes.

Tissue survival, in the context of medical and surgical sciences, refers to the ability of tissues to maintain their structural and functional integrity after being subjected to various stressors such as injury, surgery, ischemia (restriction in blood supply), or disease. The maintenance of tissue survival is crucial for ensuring proper healing, reducing the risk of complications, and preserving organ function.

Factors that contribute to tissue survival include adequate blood flow, sufficient oxygen and nutrient supply, removal of waste products, maintenance of a healthy cellular environment (pH, temperature, etc.), and minimal exposure to harmful substances or damaging agents. In some cases, therapeutic interventions such as hypothermia, pharmacological treatments, or tissue engineering strategies may be employed to enhance tissue survival in challenging clinical scenarios.

Gallium radioisotopes refer to specific types of gallium atoms that have unstable nuclei and emit radiation as they decay towards a more stable state. These isotopes are commonly used in medical imaging, such as in gallium scans, to help diagnose conditions like inflammation, infection, or cancer.

Gallium-67 (^67^Ga) is one of the most commonly used radioisotopes for medical purposes. It has a half-life of about 3.26 days and decays by emitting gamma rays. When administered to a patient, gallium-67 binds to transferrin, a protein that carries iron in the blood, and is taken up by cells with increased metabolic activity, such as cancer cells or immune cells responding to infection or inflammation. The distribution of gallium-67 in the body can then be visualized using a gamma camera, providing valuable diagnostic information.

Lung neoplasms refer to abnormal growths or tumors in the lung tissue. These tumors can be benign (non-cancerous) or malignant (cancerous). Malignant lung neoplasms are further classified into two main types: small cell lung carcinoma and non-small cell lung carcinoma. Lung neoplasms can cause symptoms such as cough, chest pain, shortness of breath, and weight loss. They are often caused by smoking or exposure to secondhand smoke, but can also occur due to genetic factors, radiation exposure, and other environmental carcinogens. Early detection and treatment of lung neoplasms is crucial for improving outcomes and survival rates.

Emission-Computed Tomography, Single-Photon (SPECT) is a type of nuclear medicine imaging procedure that generates detailed, three-dimensional images of the distribution of radioactive pharmaceuticals within the body. It uses gamma rays emitted by a radiopharmaceutical that is introduced into the patient's body, and a specialized gamma camera to detect these gamma rays and create tomographic images. The data obtained from the SPECT imaging can be used to diagnose various medical conditions, evaluate organ function, and guide treatment decisions. It is commonly used to image the heart, brain, and bones, among other organs and systems.

Mediastinal neoplasms refer to abnormal growths or tumors located in the mediastinum, which is the central compartment of the thoracic cavity that lies between the lungs and contains various vital structures such as the heart, esophagus, trachea, blood vessels, lymph nodes, and nerves. Mediastinal neoplasms can be benign (non-cancerous) or malignant (cancerous), and they can arise from any of the tissues or organs within the mediastinum.

Benign mediastinal neoplasms may include thymomas, lipomas, neurofibromas, or teratomas, among others. These tumors are typically slow-growing and rarely spread to other parts of the body. However, they can still cause symptoms or complications by compressing adjacent structures within the mediastinum, such as the airways, blood vessels, or nerves.

Malignant mediastinal neoplasms are cancerous tumors that can invade and destroy surrounding tissues and may spread (metastasize) to other parts of the body. Common types of malignant mediastinal neoplasms include thymic carcinomas, lymphomas, germ cell tumors, and neuroendocrine tumors. These tumors often require aggressive treatment, such as surgery, radiation therapy, and chemotherapy, to control their growth and spread.

It is important to note that mediastinal neoplasms can present with various symptoms depending on their location, size, and type. Some patients may be asymptomatic, while others may experience cough, chest pain, difficulty breathing, hoarseness, or swallowing difficulties. A thorough diagnostic workup, including imaging studies and biopsies, is necessary to confirm the diagnosis and determine the best course of treatment for mediastinal neoplasms.

A gamma camera, also known as a scintillation camera, is a device used in nuclear medicine to image gamma-emitting radionuclides in the body. It detects gamma radiation emitted by radioisotopes that have been introduced into the body, usually through injection or ingestion. The camera consists of a large flat crystal (often sodium iodide) that scintillates when struck by gamma rays, producing light flashes that are detected by an array of photomultiplier tubes.

The resulting signals are then processed by a computer to generate images that reflect the distribution and concentration of the radionuclide in the body. Gamma cameras are used in a variety of medical imaging procedures, including bone scans, lung scans, heart scans (such as myocardial perfusion imaging), and brain scans. They can help diagnose conditions such as cancer, heart disease, and neurological disorders.

Arteritis is a medical condition characterized by inflammation of the arteries. It is also known as vasculitis of the arteries. The inflammation can cause the walls of the arteries to thicken and narrow, reducing blood flow to affected organs or tissues. There are several types of arteritis, including:

1. Giant cell arteritis (GCA): Also known as temporal arteritis, it is a condition that mainly affects the large and medium-sized arteries in the head and neck. The inflammation can cause headaches, jaw pain, scalp tenderness, and vision problems.
2. Takayasu's arteritis: This type of arteritis affects the aorta and its major branches, mainly affecting young women. Symptoms include fever, weight loss, fatigue, and decreased pulse in the arms or legs.
3. Polyarteritis nodosa (PAN): PAN is a rare systemic vasculitis that can affect medium-sized arteries throughout the body. It can cause a wide range of symptoms, including fever, rash, abdominal pain, and muscle weakness.
4. Kawasaki disease: This is a type of arteritis that mainly affects children under the age of 5. It causes inflammation in the blood vessels throughout the body, leading to fever, rash, swollen lymph nodes, and red eyes.

The exact cause of arteritis is not fully understood, but it is believed to be an autoimmune disorder, where the body's immune system mistakenly attacks its own tissues. Treatment for arteritis typically involves medications to reduce inflammation and suppress the immune system.

Lymphatic metastasis is the spread of cancer cells from a primary tumor to distant lymph nodes through the lymphatic system. It occurs when malignant cells break away from the original tumor, enter the lymphatic vessels, and travel to nearby or remote lymph nodes. Once there, these cancer cells can multiply and form new tumors, leading to further progression of the disease. Lymphatic metastasis is a common way for many types of cancer to spread and can have significant implications for prognosis and treatment strategies.

Prospective studies, also known as longitudinal studies, are a type of cohort study in which data is collected forward in time, following a group of individuals who share a common characteristic or exposure over a period of time. The researchers clearly define the study population and exposure of interest at the beginning of the study and follow up with the participants to determine the outcomes that develop over time. This type of study design allows for the investigation of causal relationships between exposures and outcomes, as well as the identification of risk factors and the estimation of disease incidence rates. Prospective studies are particularly useful in epidemiology and medical research when studying diseases with long latency periods or rare outcomes.

Thallium radioisotopes are radioactive isotopes or variants of the element thallium (Tl), which decays and emits radiation. Thallium has several radioisotopes, with the most commonly used being thallium-201 (^201Tl). This radioisotope is used in medical imaging, specifically in myocardial perfusion scintigraphy, to evaluate blood flow to the heart muscle. It decays by electron capture and emits gamma radiation with a half-life of 73 hours, making it suitable for diagnostic procedures.

It's important to note that handling and using radioisotopes require proper training and safety measures due to their ionizing radiation properties.

The mediastinum is the medical term for the area in the middle of the chest that separates the two lungs. It contains various vital organs and structures, including:

* The heart and its blood vessels
* The trachea (windpipe) and esophagus (tube connecting the throat to the stomach)
* The thymus gland
* Lymph nodes
* Nerves, including the vagus nerve and phrenic nerves
* Connective tissue and fat

The mediastinum is enclosed by the breastbone in front, the spine in back, and the lungs on either side. Abnormalities in the structures contained within the mediastinum can lead to various medical conditions, such as tumors or infections.

Sturge-Weber syndrome is a rare neurocutaneous disorder characterized by the combination of a facial port-wine birthmark and neurological abnormalities. The facial birthmark, which is typically located on one side of the face, occurs due to the malformation of small blood vessels (capillaries) in the skin and eye.

Neurological features often include seizures that begin in infancy, muscle weakness or paralysis on one side of the body (hemiparesis), developmental delay, and intellectual disability. These neurological symptoms are caused by abnormal blood vessel formation in the brain (leptomeningeal angiomatosis) leading to increased pressure, reduced blood flow, and potential damage to the brain tissue.

Sturge-Weber syndrome can also affect the eyes, with glaucoma being a common occurrence due to increased pressure within the eye. Early diagnosis and appropriate management of this condition are crucial for improving the quality of life and reducing potential complications.

I'm not aware of a widely recognized or established medical term called "F factor." It is possible that it could be a term specific to certain medical specialties, research, or publications. In order to provide an accurate and helpful response, I would need more context or information about where you encountered this term.

If you meant to ask about the F-plasmid, which is sometimes referred to as the "F factor" in bacteriology, it is a type of plasmid that can be found in certain strains of bacteria and carries genes related to conjugation (the process by which bacteria transfer genetic material between each other). The F-plasmid can exist as an independent circular DNA molecule or integrate into the chromosome of the host bacterium.

If this is not the term you were looking for, please provide more context so I can give a better answer.

Prognosis is a medical term that refers to the prediction of the likely outcome or course of a disease, including the chances of recovery or recurrence, based on the patient's symptoms, medical history, physical examination, and diagnostic tests. It is an important aspect of clinical decision-making and patient communication, as it helps doctors and patients make informed decisions about treatment options, set realistic expectations, and plan for future care.

Prognosis can be expressed in various ways, such as percentages, categories (e.g., good, fair, poor), or survival rates, depending on the nature of the disease and the available evidence. However, it is important to note that prognosis is not an exact science and may vary depending on individual factors, such as age, overall health status, and response to treatment. Therefore, it should be used as a guide rather than a definitive forecast.

A Solitary Pulmonary Nodule (SPN) is a single, round or oval-shaped lung shadow that measures up to 3 cm in diameter on a chest radiograph. It is also known as a "coin lesion" due to its appearance. SPNs are usually discovered incidentally during routine chest X-rays or CT scans. They can be benign or malignant, and their nature is determined through further diagnostic tests such as PET scans, biopsies, or follow-up imaging studies.

Dobutamine is a synthetic catecholamine used in medical treatment, specifically as a positive inotrope and vasodilator. It works by stimulating the beta-1 adrenergic receptors of the heart, thereby increasing its contractility and stroke volume. This results in an improved cardiac output, making dobutamine beneficial in treating heart failure, cardiogenic shock, and other conditions where heart function is compromised.

It's important to note that dobutamine should be administered under strict medical supervision due to its potential to cause adverse effects such as arrhythmias, hypotension, or hypertension. The dosage, frequency, and duration of administration are determined by the patient's specific condition and response to treatment.

Computer-assisted image processing is a medical term that refers to the use of computer systems and specialized software to improve, analyze, and interpret medical images obtained through various imaging techniques such as X-ray, CT (computed tomography), MRI (magnetic resonance imaging), ultrasound, and others.

The process typically involves several steps, including image acquisition, enhancement, segmentation, restoration, and analysis. Image processing algorithms can be used to enhance the quality of medical images by adjusting contrast, brightness, and sharpness, as well as removing noise and artifacts that may interfere with accurate diagnosis. Segmentation techniques can be used to isolate specific regions or structures of interest within an image, allowing for more detailed analysis.

Computer-assisted image processing has numerous applications in medical imaging, including detection and characterization of lesions, tumors, and other abnormalities; assessment of organ function and morphology; and guidance of interventional procedures such as biopsies and surgeries. By automating and standardizing image analysis tasks, computer-assisted image processing can help to improve diagnostic accuracy, efficiency, and consistency, while reducing the potential for human error.

Autoradiography is a medical imaging technique used to visualize and localize the distribution of radioactively labeled compounds within tissues or organisms. In this process, the subject is first exposed to a radioactive tracer that binds to specific molecules or structures of interest. The tissue is then placed in close contact with a radiation-sensitive film or detector, such as X-ray film or an imaging plate.

As the radioactive atoms decay, they emit particles (such as beta particles) that interact with the film or detector, causing chemical changes and leaving behind a visible image of the distribution of the labeled compound. The resulting autoradiogram provides information about the location, quantity, and sometimes even the identity of the molecules or structures that have taken up the radioactive tracer.

Autoradiography has been widely used in various fields of biology and medical research, including pharmacology, neuroscience, genetics, and cell biology, to study processes such as protein-DNA interactions, gene expression, drug metabolism, and neuronal connectivity. However, due to the use of radioactive materials and potential hazards associated with them, this technique has been gradually replaced by non-radioactive alternatives like fluorescence in situ hybridization (FISH) or immunofluorescence techniques.

Treatment outcome is a term used to describe the result or effect of medical treatment on a patient's health status. It can be measured in various ways, such as through symptoms improvement, disease remission, reduced disability, improved quality of life, or survival rates. The treatment outcome helps healthcare providers evaluate the effectiveness of a particular treatment plan and make informed decisions about future care. It is also used in clinical research to compare the efficacy of different treatments and improve patient care.

F2-isoprostanes are a type of prostaglandin-like compound that is formed in the body through the free radical-catalyzed peroxidation of arachidonic acid, a polyunsaturated fatty acid found in cell membranes. They are produced in response to oxidative stress and are often used as a biomarker for lipid peroxidation and oxidative damage in various diseases, including atherosclerosis, cancer, and neurodegenerative disorders. F2-isoprostanes are chemically stable and can be measured in biological fluids such as blood, urine, and breath condensate. They have been shown to cause vasoconstriction, platelet aggregation, and inflammation, which may contribute to the pathogenesis of various diseases.

Retrospective studies, also known as retrospective research or looking back studies, are a type of observational study that examines data from the past to draw conclusions about possible causal relationships between risk factors and outcomes. In these studies, researchers analyze existing records, medical charts, or previously collected data to test a hypothesis or answer a specific research question.

Retrospective studies can be useful for generating hypotheses and identifying trends, but they have limitations compared to prospective studies, which follow participants forward in time from exposure to outcome. Retrospective studies are subject to biases such as recall bias, selection bias, and information bias, which can affect the validity of the results. Therefore, retrospective studies should be interpreted with caution and used primarily to generate hypotheses for further testing in prospective studies.

Local neoplasm recurrence is the return or regrowth of a tumor in the same location where it was originally removed or treated. This means that cancer cells have survived the initial treatment and started to grow again in the same area. It's essential to monitor and detect any local recurrence as early as possible, as it can affect the prognosis and may require additional treatment.

Misonidazole is defined as a radiosensitizer drug, which is primarily used in the field of radiation oncology. It works by making cancer cells more sensitive to radiation therapy, thereby increasing the effectiveness of the treatment. Misonidazole is an nitroimidazole compound that gets reduced under hypoxic conditions (when there is a lack of oxygen) and forms free radicals, which can damage DNA and kill the cells.

It's important to note that misonidazole is not commonly used in current clinical practice due to its narrow therapeutic index and significant side effects, such as neurotoxicity. Other nitroimidazole radiosensitizers, such as nimorazole, have been developed and are more widely used because they have a lower risk of neurotoxicity.

Hodgkin disease, also known as Hodgkin lymphoma, is a type of cancer that originates in the white blood cells called lymphocytes. It typically affects the lymphatic system, which is a network of vessels and glands spread throughout the body. The disease is characterized by the presence of a specific type of abnormal cell, known as a Reed-Sternberg cell, within the affected lymph nodes.

The symptoms of Hodgkin disease may include painless swelling of the lymph nodes in the neck, armpits, or groin; fever; night sweats; weight loss; and fatigue. The exact cause of Hodgkin disease is unknown, but it is thought to involve a combination of genetic, environmental, and infectious factors.

Hodgkin disease is typically treated with a combination of chemotherapy, radiation therapy, and/or immunotherapy, depending on the stage and extent of the disease. With appropriate treatment, the prognosis for Hodgkin disease is generally very good, with a high cure rate. However, long-term side effects of treatment may include an increased risk of secondary cancers and other health problems.

Fever of Unknown Origin (FUO) is a medical condition defined as a fever that remains undiagnosed after one week of inpatient evaluation or three days of outpatient evaluation, with temperatures repeatedly measuring at or above 38.3°C (101°F). The fevers can be continuous or intermittent and are often associated with symptoms such as fatigue, weight loss, and general malaise.

The causes of FUO can be broadly categorized into four groups: infections, inflammatory diseases, neoplasms (cancers), and miscellaneous conditions. Infections account for a significant proportion of cases, particularly in immunocompromised individuals. Other possible causes include connective tissue disorders, vasculitides, drug reactions, and factitious fever.

The diagnostic approach to FUO involves a thorough history and physical examination, laboratory tests, and imaging studies. The goal is to identify the underlying cause of the fever and provide appropriate treatment. In some cases, despite extensive evaluation, the cause may remain undiagnosed, and management focuses on supportive care and monitoring for any new symptoms or complications.

Para-aortic bodies, also known as autonomic ganglia or para-aortic chains, are clusters of nerve cells (ganglia) located near the aorta, the largest artery in the body. These ganglia are part of the autonomic nervous system, which controls involuntary bodily functions such as heart rate, digestion, and respiratory rate.

The para-aortic bodies are primarily responsible for regulating the function of the organs in the abdomen and pelvis. They receive input from sensory neurons and send output to effector organs through a complex network of nerves. The neurotransmitters acetylcholine and noradrenaline are released at these ganglia to mediate the transmission of signals between nerve cells.

These structures can be important in the diagnosis and treatment of certain medical conditions, such as neuroblastoma, a type of cancer that arises from immature nerve cells in infants and children. In some cases, surgical removal of para-aortic bodies may be necessary to treat this condition.

Alzheimer's disease is a progressive disorder that causes brain cells to waste away (degenerate) and die. It's the most common cause of dementia — a continuous decline in thinking, behavioral and social skills that disrupts a person's ability to function independently.

The early signs of the disease include forgetting recent events or conversations. As the disease progresses, a person with Alzheimer's disease will develop severe memory impairment and lose the ability to carry out everyday tasks.

Currently, there's no cure for Alzheimer's disease. However, treatments can temporarily slow the worsening of dementia symptoms and improve quality of life.

Incidental findings are diagnoses or conditions that are discovered unintentionally while evaluating a patient for a different condition or symptom. These findings are not related to the primary reason for the medical examination, investigation, or procedure. They can occur in various contexts such as radiology studies, laboratory tests, or physical examinations.

Incidental findings can sometimes lead to further evaluation and management, depending on their nature and potential clinical significance. However, they also pose challenges related to communication, informed consent, and potential patient anxiety or harm. Therefore, it is essential to have clear guidelines for managing incidental findings in clinical practice.

In medical terms, the heart is a muscular organ located in the thoracic cavity that functions as a pump to circulate blood throughout the body. It's responsible for delivering oxygen and nutrients to the tissues and removing carbon dioxide and other wastes. The human heart is divided into four chambers: two atria on the top and two ventricles on the bottom. The right side of the heart receives deoxygenated blood from the body and pumps it to the lungs, while the left side receives oxygenated blood from the lungs and pumps it out to the rest of the body. The heart's rhythmic contractions and relaxations are regulated by a complex electrical conduction system.

Reproducibility of results in a medical context refers to the ability to obtain consistent and comparable findings when a particular experiment or study is repeated, either by the same researcher or by different researchers, following the same experimental protocol. It is an essential principle in scientific research that helps to ensure the validity and reliability of research findings.

In medical research, reproducibility of results is crucial for establishing the effectiveness and safety of new treatments, interventions, or diagnostic tools. It involves conducting well-designed studies with adequate sample sizes, appropriate statistical analyses, and transparent reporting of methods and findings to allow other researchers to replicate the study and confirm or refute the results.

The lack of reproducibility in medical research has become a significant concern in recent years, as several high-profile studies have failed to produce consistent findings when replicated by other researchers. This has led to increased scrutiny of research practices and a call for greater transparency, rigor, and standardization in the conduct and reporting of medical research.

A residual neoplasm is a term used in pathology and oncology to describe the remaining abnormal tissue or cancer cells after a surgical procedure or treatment aimed at completely removing a tumor. This means that some cancer cells have been left behind and continue to persist in the body. The presence of residual neoplasm can increase the risk of recurrence or progression of the disease, as these remaining cells may continue to grow and divide.

Residual neoplasm is often assessed during follow-up appointments and monitoring, using imaging techniques like CT scans, MRIs, or PET scans, and sometimes through biopsies. The extent of residual neoplasm can influence the choice of further treatment options, such as additional surgery, radiation therapy, chemotherapy, or targeted therapies, to eliminate the remaining cancer cells and reduce the risk of recurrence.

Myocardial revascularization is a medical term that refers to the restoration of blood flow to the heart muscle (myocardium), typically through a surgical or interventional procedure. This is often performed in patients with coronary artery disease, where the buildup of plaque in the coronary arteries restricts blood flow to the heart muscle, causing symptoms such as chest pain (angina) or shortness of breath, and increasing the risk of a heart attack (myocardial infarction).

There are two main types of myocardial revascularization:

1. Coronary artery bypass grafting (CABG): This is a surgical procedure in which a healthy blood vessel from another part of the body is used to create a detour around the blocked or narrowed coronary artery, allowing blood to flow more freely to the heart muscle.
2. Percutaneous coronary intervention (PCI), also known as angioplasty and stenting: This is a minimally invasive procedure in which a thin catheter is inserted into an artery in the groin or arm and threaded up to the blocked or narrowed coronary artery. A balloon is then inflated to widen the artery, and a stent may be placed to keep it open.

Both procedures aim to improve symptoms, reduce the risk of heart attack, and prolong survival in appropriately selected patients with coronary artery disease.

Radioisotopes, also known as radioactive isotopes or radionuclides, are variants of chemical elements that have unstable nuclei and emit radiation in the form of alpha particles, beta particles, gamma rays, or conversion electrons. These isotopes are formed when an element's nucleus undergoes natural or artificial radioactive decay.

Radioisotopes can be produced through various processes, including nuclear fission, nuclear fusion, and particle bombardment in a cyclotron or other types of particle accelerators. They have a wide range of applications in medicine, industry, agriculture, research, and energy production. In the medical field, radioisotopes are used for diagnostic imaging, radiation therapy, and in the labeling of molecules for research purposes.

It is important to note that handling and using radioisotopes requires proper training, safety measures, and regulatory compliance due to their ionizing radiation properties, which can pose potential health risks if not handled correctly.

Lymphoma is a type of cancer that originates from the white blood cells called lymphocytes, which are part of the immune system. These cells are found in various parts of the body such as the lymph nodes, spleen, bone marrow, and other organs. Lymphoma can be classified into two main types: Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL).

HL is characterized by the presence of a specific type of abnormal lymphocyte called Reed-Sternberg cells, while NHL includes a diverse group of lymphomas that lack these cells. The symptoms of lymphoma may include swollen lymph nodes, fever, night sweats, weight loss, and fatigue.

The exact cause of lymphoma is not known, but it is believed to result from genetic mutations in the lymphocytes that lead to uncontrolled cell growth and division. Exposure to certain viruses, chemicals, and radiation may increase the risk of developing lymphoma. Treatment options for lymphoma depend on various factors such as the type and stage of the disease, age, and overall health of the patient. Common treatments include chemotherapy, radiation therapy, immunotherapy, and stem cell transplantation.

Soft tissue neoplasms refer to abnormal growths or tumors that develop in the soft tissues of the body. Soft tissues include muscles, tendons, ligaments, fascia, nerves, blood vessels, fat, and synovial membranes (the thin layer of cells that line joints and tendons). Neoplasms can be benign (non-cancerous) or malignant (cancerous), and their behavior and potential for spread depend on the specific type of neoplasm.

Benign soft tissue neoplasms are typically slow-growing, well-circumscribed, and rarely spread to other parts of the body. They can often be removed surgically with a low risk of recurrence. Examples of benign soft tissue neoplasms include lipomas (fat tumors), schwannomas (nerve sheath tumors), and hemangiomas (blood vessel tumors).

Malignant soft tissue neoplasms, on the other hand, can grow rapidly, invade surrounding tissues, and may metastasize (spread) to distant parts of the body. They are often more difficult to treat than benign neoplasms and require a multidisciplinary approach, including surgery, radiation therapy, and chemotherapy. Examples of malignant soft tissue neoplasms include sarcomas, such as rhabdomyosarcoma (arising from skeletal muscle), leiomyosarcoma (arising from smooth muscle), and angiosarcoma (arising from blood vessels).

It is important to note that soft tissue neoplasms can occur in any part of the body, and their diagnosis and treatment require a thorough evaluation by a healthcare professional with expertise in this area.

Aniline compounds, also known as aromatic amines, are organic compounds that contain a benzene ring substituted with an amino group (-NH2). Aniline itself is the simplest and most common aniline compound, with the formula C6H5NH2.

Aniline compounds are important in the chemical industry and are used in the synthesis of a wide range of products, including dyes, pharmaceuticals, and rubber chemicals. They can be produced by reducing nitrobenzene or by directly substituting ammonia onto benzene in a process called amination.

It is important to note that aniline compounds are toxic and can cause serious health effects, including damage to the liver, kidneys, and central nervous system. They can also be absorbed through the skin and are known to have carcinogenic properties. Therefore, appropriate safety measures must be taken when handling aniline compounds.

Follow-up studies are a type of longitudinal research that involve repeated observations or measurements of the same variables over a period of time, in order to understand their long-term effects or outcomes. In medical context, follow-up studies are often used to evaluate the safety and efficacy of medical treatments, interventions, or procedures.

In a typical follow-up study, a group of individuals (called a cohort) who have received a particular treatment or intervention are identified and then followed over time through periodic assessments or data collection. The data collected may include information on clinical outcomes, adverse events, changes in symptoms or functional status, and other relevant measures.

The results of follow-up studies can provide important insights into the long-term benefits and risks of medical interventions, as well as help to identify factors that may influence treatment effectiveness or patient outcomes. However, it is important to note that follow-up studies can be subject to various biases and limitations, such as loss to follow-up, recall bias, and changes in clinical practice over time, which must be carefully considered when interpreting the results.

Carcinoma, non-small-cell lung (NSCLC) is a type of lung cancer that includes several subtypes of malignant tumors arising from the epithelial cells of the lung. These subtypes are classified based on the appearance of the cancer cells under a microscope and include adenocarcinoma, squamous cell carcinoma, and large cell carcinoma. NSCLC accounts for about 85% of all lung cancers and tends to grow and spread more slowly than small-cell lung cancer (SCLC).

NSCLC is often asymptomatic in its early stages, but as the tumor grows, symptoms such as coughing, chest pain, shortness of breath, hoarseness, and weight loss may develop. Treatment options for NSCLC depend on the stage and location of the cancer, as well as the patient's overall health and lung function. Common treatments include surgery, radiation therapy, chemotherapy, targeted therapy, or a combination of these approaches.

Methionine is an essential amino acid, which means that it cannot be synthesized by the human body and must be obtained through the diet. It plays a crucial role in various biological processes, including:

1. Protein synthesis: Methionine is one of the building blocks of proteins, helping to create new proteins and maintain the structure and function of cells.
2. Methylation: Methionine serves as a methyl group donor in various biochemical reactions, which are essential for DNA synthesis, gene regulation, and neurotransmitter production.
3. Antioxidant defense: Methionine can be converted to cysteine, which is involved in the formation of glutathione, a potent antioxidant that helps protect cells from oxidative damage.
4. Homocysteine metabolism: Methionine is involved in the conversion of homocysteine back to methionine through a process called remethylation, which is essential for maintaining normal homocysteine levels and preventing cardiovascular disease.
5. Fat metabolism: Methionine helps facilitate the breakdown and metabolism of fats in the body.

Foods rich in methionine include meat, fish, dairy products, eggs, and some nuts and seeds.

Tissue distribution, in the context of pharmacology and toxicology, refers to the way that a drug or xenobiotic (a chemical substance found within an organism that is not naturally produced by or expected to be present within that organism) is distributed throughout the body's tissues after administration. It describes how much of the drug or xenobiotic can be found in various tissues and organs, and is influenced by factors such as blood flow, lipid solubility, protein binding, and the permeability of cell membranes. Understanding tissue distribution is important for predicting the potential effects of a drug or toxin on different parts of the body, and for designing drugs with improved safety and efficacy profiles.

Non-Hodgkin lymphoma (NHL) is a type of cancer that originates in the lymphatic system, which is part of the immune system. It involves the abnormal growth and proliferation of malignant lymphocytes (a type of white blood cell), leading to the formation of tumors in lymph nodes, spleen, bone marrow, or other organs. NHL can be further classified into various subtypes based on the specific type of lymphocyte involved and its characteristics.

The symptoms of Non-Hodgkin lymphoma may include:

* Painless swelling of lymph nodes in the neck, armpits, or groin
* Persistent fatigue
* Unexplained weight loss
* Fever
* Night sweats
* Itchy skin

The exact cause of Non-Hodgkin lymphoma is not well understood, but it has been associated with certain risk factors such as age (most common in people over 60), exposure to certain chemicals, immune system deficiencies, and infection with viruses like Epstein-Barr virus or HIV.

Treatment for Non-Hodgkin lymphoma depends on the stage and subtype of the disease, as well as the patient's overall health. Treatment options may include chemotherapy, radiation therapy, immunotherapy, targeted therapy, stem cell transplantation, or a combination of these approaches. Regular follow-up care is essential to monitor the progression of the disease and manage any potential long-term side effects of treatment.

A "false positive reaction" in medical testing refers to a situation where a diagnostic test incorrectly indicates the presence of a specific condition or disease in an individual who does not actually have it. This occurs when the test results give a positive outcome, while the true health status of the person is negative or free from the condition being tested for.

False positive reactions can be caused by various factors including:

1. Presence of unrelated substances that interfere with the test result (e.g., cross-reactivity between similar molecules).
2. Low specificity of the test, which means it may detect other conditions or irrelevant factors as positive.
3. Contamination during sample collection, storage, or analysis.
4. Human errors in performing or interpreting the test results.

False positive reactions can have significant consequences, such as unnecessary treatments, anxiety, and increased healthcare costs. Therefore, it is essential to confirm any positive test result with additional tests or clinical evaluations before making a definitive diagnosis.

Bone neoplasms are abnormal growths or tumors that develop in the bone. They can be benign (non-cancerous) or malignant (cancerous). Benign bone neoplasms do not spread to other parts of the body and are rarely a threat to life, although they may cause problems if they grow large enough to press on surrounding tissues or cause fractures. Malignant bone neoplasms, on the other hand, can invade and destroy nearby tissue and may spread (metastasize) to other parts of the body.

There are many different types of bone neoplasms, including:

1. Osteochondroma - a benign tumor that develops from cartilage and bone
2. Enchondroma - a benign tumor that forms in the cartilage that lines the inside of the bones
3. Chondrosarcoma - a malignant tumor that develops from cartilage
4. Osteosarcoma - a malignant tumor that develops from bone cells
5. Ewing sarcoma - a malignant tumor that develops in the bones or soft tissues around the bones
6. Giant cell tumor of bone - a benign or occasionally malignant tumor that develops from bone tissue
7. Fibrosarcoma - a malignant tumor that develops from fibrous tissue in the bone

The symptoms of bone neoplasms vary depending on the type, size, and location of the tumor. They may include pain, swelling, stiffness, fractures, or limited mobility. Treatment options depend on the type and stage of the tumor but may include surgery, radiation therapy, chemotherapy, or a combination of these treatments.

Neuroimaging is a medical term that refers to the use of various techniques to either directly or indirectly image the structure, function, or pharmacology of the nervous system. It includes techniques such as computed tomography (CT), magnetic resonance imaging (MRI), functional MRI (fMRI), positron emission tomography (PET), single-photon emission computed tomography (SPECT), and diffusion tensor imaging (DTI). These techniques are used to diagnose and monitor various neurological and psychiatric conditions, as well as to understand the underlying mechanisms of brain function in health and disease.

The "subtraction technique" is not a widely recognized or established term in medical terminology. It may refer to various methods used in different medical contexts that involve subtracting or comparing measurements, values, or observations to diagnose, monitor, or treat medical conditions. However, without more specific context, it's difficult to provide an accurate medical definition of the term.

In radiology, for example, the subtraction technique is a method used in imaging to enhance the visibility of certain structures by digitally subtracting one image from another. This technique is often used in angiography to visualize blood vessels more clearly.

Therefore, it's essential to provide more context or specify the medical field when using the term "subtraction technique" to ensure accurate communication and understanding.

3-Iodobenzylguanidine (3-IBG) is a radioactive tracer drug that is used in nuclear medicine to help diagnose and evaluate pheochromocytomas and paragangliomas, which are rare tumors of the adrenal glands or nearby nerve tissue. It works by accumulating in the cells of these tumors, allowing them to be detected through imaging techniques such as single-photon emission computed tomography (SPECT) scans.

The drug contains a radioactive isotope of iodine (I-123 or I-131) that emits gamma rays, which can be detected by a gamma camera during the imaging procedure. The 3-IBG molecule also includes a guanidine group, which selectively binds to the norepinephrine transporter (NET) on the surface of the tumor cells, allowing the drug to accumulate within the tumor tissue.

It is important to note that the use of 3-IBG should be under the supervision of a qualified healthcare professional, as it involves exposure to radiation and may have potential side effects.

Diagnostic imaging is a medical specialty that uses various technologies to produce visual representations of the internal structures and functioning of the body. These images are used to diagnose injury, disease, or other abnormalities and to monitor the effectiveness of treatment. Common modalities of diagnostic imaging include:

1. Radiography (X-ray): Uses ionizing radiation to produce detailed images of bones, teeth, and some organs.
2. Computed Tomography (CT) Scan: Combines X-ray technology with computer processing to create cross-sectional images of the body.
3. Magnetic Resonance Imaging (MRI): Uses a strong magnetic field and radio waves to generate detailed images of soft tissues, organs, and bones.
4. Ultrasound: Employs high-frequency sound waves to produce real-time images of internal structures, often used for obstetrics and gynecology.
5. Nuclear Medicine: Involves the administration of radioactive tracers to assess organ function or detect abnormalities within the body.
6. Positron Emission Tomography (PET) Scan: Uses a small amount of radioactive material to produce detailed images of metabolic activity in the body, often used for cancer detection and monitoring treatment response.
7. Fluoroscopy: Utilizes continuous X-ray imaging to observe moving structures or processes within the body, such as swallowing studies or angiography.

Diagnostic imaging plays a crucial role in modern medicine, allowing healthcare providers to make informed decisions about patient care and treatment plans.

Antineoplastic combined chemotherapy protocols refer to a treatment plan for cancer that involves the use of more than one antineoplastic (chemotherapy) drug given in a specific sequence and schedule. The combination of drugs is used because they may work better together to destroy cancer cells compared to using a single agent alone. This approach can also help to reduce the likelihood of cancer cells becoming resistant to the treatment.

The choice of drugs, dose, duration, and frequency are determined by various factors such as the type and stage of cancer, patient's overall health, and potential side effects. Combination chemotherapy protocols can be used in various settings, including as a primary treatment, adjuvant therapy (given after surgery or radiation to kill any remaining cancer cells), neoadjuvant therapy (given before surgery or radiation to shrink the tumor), or palliative care (to alleviate symptoms and prolong survival).

It is important to note that while combined chemotherapy protocols can be effective in treating certain types of cancer, they can also cause significant side effects, including nausea, vomiting, hair loss, fatigue, and an increased risk of infection. Therefore, patients undergoing such treatment should be closely monitored and managed by a healthcare team experienced in administering chemotherapy.

The myocardium is the middle layer of the heart wall, composed of specialized cardiac muscle cells that are responsible for pumping blood throughout the body. It forms the thickest part of the heart wall and is divided into two sections: the left ventricle, which pumps oxygenated blood to the rest of the body, and the right ventricle, which pumps deoxygenated blood to the lungs.

The myocardium contains several types of cells, including cardiac muscle fibers, connective tissue, nerves, and blood vessels. The muscle fibers are arranged in a highly organized pattern that allows them to contract in a coordinated manner, generating the force necessary to pump blood through the heart and circulatory system.

Damage to the myocardium can occur due to various factors such as ischemia (reduced blood flow), infection, inflammation, or genetic disorders. This damage can lead to several cardiac conditions, including heart failure, arrhythmias, and cardiomyopathy.

Adenocarcinoma is a type of cancer that arises from glandular epithelial cells. These cells line the inside of many internal organs, including the breasts, prostate, colon, and lungs. Adenocarcinomas can occur in any of these organs, as well as in other locations where glands are present.

The term "adenocarcinoma" is used to describe a cancer that has features of glandular tissue, such as mucus-secreting cells or cells that produce hormones. These cancers often form glandular structures within the tumor mass and may produce mucus or other substances.

Adenocarcinomas are typically slow-growing and tend to spread (metastasize) to other parts of the body through the lymphatic system or bloodstream. They can be treated with surgery, radiation therapy, chemotherapy, targeted therapy, or a combination of these treatments. The prognosis for adenocarcinoma depends on several factors, including the location and stage of the cancer, as well as the patient's overall health and age.

Hexokinase is an enzyme that plays a crucial role in the initial step of glucose metabolism, which is the phosphorylation of glucose to form glucose-6-phosphate. This reaction is the first step in most glucose catabolic pathways, including glycolysis, pentose phosphate pathway, and glycogen synthesis.

Hexokinase has a high affinity for glucose, meaning it can bind and phosphorylate glucose even at low concentrations. This property makes hexokinase an important regulator of glucose metabolism in cells. There are four isoforms of hexokinase (I-IV) found in different tissues, with hexokinase IV (also known as glucokinase) being primarily expressed in the liver and pancreas.

In summary, hexokinase is a vital enzyme involved in glucose metabolism, catalyzing the conversion of glucose to glucose-6-phosphate, and playing a crucial role in regulating cellular energy homeostasis.

Pleural neoplasms refer to abnormal growths or tumors that develop in the pleura, which is the thin, double layered membrane that surrounds the lungs and lines the inside of the chest wall. These neoplasms can be benign (non-cancerous) or malignant (cancerous).

Malignant pleural neoplasms are often associated with lung cancer, mesothelioma, or metastasis from other types of cancer. They can cause symptoms such as chest pain, cough, shortness of breath, and weight loss. Diagnosis typically involves imaging tests like X-rays or CT scans, followed by biopsy to confirm the type of tumor. Treatment options may include surgery, radiation therapy, chemotherapy, or a combination of these approaches.

Preoperative care refers to the series of procedures, interventions, and preparations that are conducted before a surgical operation. The primary goal of preoperative care is to ensure the patient's well-being, optimize their physical condition, reduce potential risks, and prepare them mentally and emotionally for the upcoming surgery.

Preoperative care typically includes:

1. Preoperative assessment: A thorough evaluation of the patient's overall health status, including medical history, physical examination, laboratory tests, and diagnostic imaging, to identify any potential risk factors or comorbidities that may impact the surgical procedure and postoperative recovery.
2. Informed consent: The process of ensuring the patient understands the nature of the surgery, its purpose, associated risks, benefits, and alternative treatment options. The patient signs a consent form indicating they have been informed and voluntarily agree to undergo the surgery.
3. Preoperative instructions: Guidelines provided to the patient regarding their diet, medication use, and other activities in the days leading up to the surgery. These instructions may include fasting guidelines, discontinuing certain medications, or arranging for transportation after the procedure.
4. Anesthesia consultation: A meeting with the anesthesiologist to discuss the type of anesthesia that will be used during the surgery and address any concerns related to anesthesia risks, side effects, or postoperative pain management.
5. Preparation of the surgical site: Cleaning and shaving the area where the incision will be made, as well as administering appropriate antimicrobial agents to minimize the risk of infection.
6. Medical optimization: Addressing any underlying medical conditions or correcting abnormalities that may negatively impact the surgical outcome. This may involve adjusting medications, treating infections, or managing chronic diseases such as diabetes.
7. Emotional and psychological support: Providing counseling, reassurance, and education to help alleviate anxiety, fear, or emotional distress related to the surgery.
8. Preoperative holding area: The patient is transferred to a designated area near the operating room where they are prepared for surgery by changing into a gown, having intravenous (IV) lines inserted, and receiving monitoring equipment.

By following these preoperative care guidelines, healthcare professionals aim to ensure that patients undergo safe and successful surgical procedures with optimal outcomes.

Dideoxynucleosides are a type of modified nucleoside used in the treatment of certain viral infections, such as HIV and HBV. These compounds lack a hydroxyl group (-OH) at the 3'-carbon position of the sugar moiety, which prevents them from being further metabolized into DNA.

When incorporated into a growing DNA chain during reverse transcription, dideoxynucleosides act as chain terminators, inhibiting viral replication. Common examples of dideoxynucleosides include zidovudine (AZT), didanosine (ddI), stavudine (d4T), and lamivudine (3TC). These drugs are often used in combination with other antiretroviral agents to form highly active antiretroviral therapy (HAART) regimens for the treatment of HIV infection.

Technetium Tc 99m Sestamibi is a radiopharmaceutical compound used in medical imaging, specifically in myocardial perfusion scintigraphy. It is a technetium-labeled isonitrile chelate that is taken up by mitochondria in cells with high metabolic activity, such as cardiomyocytes (heart muscle cells).

Once injected into the patient's body, Technetium Tc 99m Sestamibi emits gamma rays, which can be detected by a gamma camera. This allows for the creation of images that reflect the distribution and function of the radiopharmaceutical within the heart muscle. The images can help identify areas of reduced blood flow or ischemia, which may indicate coronary artery disease.

The uptake of Technetium Tc 99m Sestamibi in other organs, such as the breast and thyroid, can also be used for imaging purposes, although its primary use remains in cardiac imaging.

Squamous cell carcinoma is a type of skin cancer that begins in the squamous cells, which are flat, thin cells that form the outer layer of the skin (epidermis). It commonly occurs on sun-exposed areas such as the face, ears, lips, and backs of the hands. Squamous cell carcinoma can also develop in other areas of the body including the mouth, lungs, and cervix.

This type of cancer usually develops slowly and may appear as a rough or scaly patch of skin, a red, firm nodule, or a sore or ulcer that doesn't heal. While squamous cell carcinoma is not as aggressive as some other types of cancer, it can metastasize (spread) to other parts of the body if left untreated, making early detection and treatment important.

Risk factors for developing squamous cell carcinoma include prolonged exposure to ultraviolet (UV) radiation from the sun or tanning beds, fair skin, a history of sunburns, a weakened immune system, and older age. Prevention measures include protecting your skin from the sun by wearing protective clothing, using a broad-spectrum sunscreen with an SPF of at least 30, avoiding tanning beds, and getting regular skin examinations.

Lymph nodes are small, bean-shaped organs that are part of the immune system. They are found throughout the body, especially in the neck, armpits, groin, and abdomen. Lymph nodes filter lymph fluid, which carries waste and unwanted substances such as bacteria, viruses, and cancer cells. They contain white blood cells called lymphocytes that help fight infections and diseases by attacking and destroying the harmful substances found in the lymph fluid. When an infection or disease is present, lymph nodes may swell due to the increased number of immune cells and fluid accumulation as they work to fight off the invaders.

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