Embolism, Air
Neurosurgery
Neuronavigation
Amrinone
Meningitis, Bacterial
Central Nervous System Infections
Monitoring, Intraoperative
Postoperative Complications
Brain Neoplasms
Magnetic Resonance Imaging
Relationship of lesion location to clinical outcome following microelectrode-guided pallidotomy for Parkinson's disease. (1/1495)
The purpose of this study was to examine the relationship between lesion location and clinical outcome following globus pallidus internus (GPi) pallidotomy for advanced Parkinson's disease. Thirty-three patients were prospectively studied with extensive neurological examinations before and at 6 and 12 months following microelectrode-guided pallidotomy. Lesion location was characterized using volumetric MRI. The position of lesions within the posteroventral region of the GPi was measured, from anteromedial to posterolateral along an axis parallel to the internal capsule. To relate lesion position to clinical outcome, hierarchical multiple regression analysis was used. The variance in outcome measures that was related to preoperative scores and lesion volume was first calculated, and then the remaining variance attributable to lesion location was determined. Lesion location along the anteromedial-to-posterolateral axis within the GPi influenced the variance in total score on the Unified Parkinson's Disease Rating Scale in the postoperative 'off' period, and in 'on' period dyskinesia scores. Within the posteroventral GPi, anteromedial lesions were associated with greater improvement in 'off' period contralateral rigidity and 'on' period dyskinesia, whereas more centrally located lesions correlated with better postoperative scores of contralateral akinesia and postural instability/gait disturbance. Improvement in contralateral tremor was weakly related to lesion location, being greater with posterolateral lesions. We conclude that improvement in specific motor signs in Parkinson's disease following pallidotomy is related to lesion position within the posteroventral GPi. These findings are consistent with the known segregated but parallel organization of specific motor circuits in the basal ganglia, and may explain the variability in clinical outcome after pallidotomy and therefore have important therapeutic implications. (+info)Reassessment of unilateral pallidotomy in Parkinson's disease. A 2-year follow-up study. (2/1495)
Unilateral pallidotomy has gained popularity in treating the motor symptoms of Parkinson's disease. We present the results of a 2-year post-pallidotomy follow-up study. Using the Unified Parkinson's Disease Rating Scale (UPDRS), the Goetz dyskinesia scale and the Purdue Pegboard Test (PPBT), we evaluated 20 patients at regular intervals both off and on medications for 2 years post-pallidotomy. There were no significant changes in the dosages of antiparkinsonian medications from 3 months pre-pallidotomy to 2 years post-pallidotomy. On the side contralateral to the operation, the improvements were preserved in 'on'-state dyskinesia (83% reduction from pre-pallidotomy to 2 years post-pallidotomy, P < 0.001) and 'off'-state tremor (90% reduction from pre-pallidotomy to 2 years post-pallidotomy, P = 0.005). There were no statistically significant differences between pre-pallidotomy scores and those at 2 years post-pallidotomy in ipsilateral dyskinesia, axial dyskinesia, 'off'- or 'on'-state PPBT, 'off'-state Activities of Daily Living (ADL) and 'off'-state gait and postural stability. After 2 years, the 'on'-state ADL scores worsened by 75%, compared with pre-pallidotomy (P = 0.005). We conclude that 2 years after pallidotomy, the improvements in dyskinesia and tremor on the side contralateral to pallidotomy are preserved, while the initial improvements in most other deficits disappear, either because of progression of pathology or loss of the early efficacy achieved by surgery. (+info)Language outcome following multiple subpial transection for Landau-Kleffner syndrome. (3/1495)
Landau-Kleffner syndrome is an acquired epileptic aphasia occurring in normal children who lose previously acquired speech and language abilities. Although some children recover some of these abilities, many children with Landau-Kleffner syndrome have significant language impairments that persist. Multiple subpial transection is a surgical technique that has been proposed as an appropriate treatment for Landau-Kleffner syndrome in that it is designed to eliminate the capacity of cortical tissue to generate seizures or subclinical epileptiform activity, while preserving the cortical functions subserved by that tissue. We report on the speech and language outcome of 14 children who underwent multiple subpial transection for treatment of Landau-Kleffner syndrome. Eleven children demonstrated significant postoperative improvement on measures of receptive or expressive vocabulary. Results indicate that early diagnosis and treatment optimize outcome, and that gains in language function are most likely to be seen years, rather than months, after surgery. Since an appropriate control group was not available, and that the best predictor of postoperative improvements in language function was that of length of time since surgery, these data might best be used as a benchmark against other Landau-Kleffner syndrome outcome studies. We conclude that multiple subpial transection may be useful in allowing for a restoration of speech and language abilities in children diagnosed with Landau-Kleffner syndrome. (+info)Independent development of sensory and motor innervation patterns in embryonic chick hindlimbs. (4/1495)
Previous studies suggest that sensory axon outgrowth is guided by motoneurons, which are specified to innervate particular target muscles. Here we present evidence that questions this conclusion. We have used a new approach to assess the pathfinding abilities of bona fide sensory neurons, first by eliminating motoneurons after neural crest cells have coalesced into dorsal root ganglia (DRG) and second by challenging sensory neurons to innervate muscles in a novel environment created by shifting a limb bud rostrally. The resulting sensory innervation patterns mapped with the lipophilic dyes DiI and DiA showed that sensory axons projected robustly to muscles in the absence of motoneurons, if motoneurons were eliminated after DRG formation. Moreover, sensory neurons projected appropriately to their usual target muscles under these conditions. In contrast, following limb shifts, muscle sensory innervation was often derived from inappropriate segments. In this novel environment, sensory neurons tended to make more "mistakes" than motoneurons. Whereas motoneurons tended to innervate their embryologically correct muscles, sensory innervation was more widespread and was generally from more rostral segments than normal. Similar results were obtained when motoneurons were eliminated in embryos with limb shifts. These findings show that sensory neurons are capable of navigating through their usual terrain without guidance from motor axons. However, unlike motor axons, sensory axons do not appear to actively seek out appropriate target muscles when confronted with a novel terrain. These findings suggest that sensory neuron identity with regard to pathway and target choice may be unspecified or quite plastic at the time of initial axon outgrowth. (+info)Cerebrospinal fluid concentrations of propofol during anaesthesia in humans. (5/1495)
The concentration of propofol in and surrounding the human brain during propofol anaesthesia is unknown. We measured simultaneously the concentration of propofol in cerebrospinal fluid (CSF) from an indwelling intraventricular catheter and the concentration in arterial blood in five neurosurgical patients before, during induction (at 2.5 and 5 min) and during a maintenance propofol infusion (at 15 and 30 min). After induction of anaesthesia with propofol 2 mg kg-1, anaesthesia was maintained with an infusion of 8 mg kg-1 h-1 for 15 min and then reduced to 6 mg kg-1 h-1. The plasma concentration of propofol increased rapidly during induction and reached a plateau concentration of mean 2.24 (SD 0.66) micrograms ml-1 after 5 min. The concentration of propofol in CSF showed a slower increase during induction and remained almost constant at 35.5 (19.6) ng ml-1 at 15-30 min after induction. The CSF concentration of propofol that we measured was 1.6% of the plasma concentration and consistent with the high protein binding of the drug in plasma. (+info)Update on Parkinson's disease. (6/1495)
Parkinson's disease is a progressive degenerative disorder of the central nervous system. The hallmark physical signs are tremor, rigidity and bradykinesia. Idiopathic Parkinson's disease is caused by the progressive loss of dopaminergic neurons in the substantia nigra and nigrostriatal pathway of the midbrain. Secondary parkinsonism may be caused by certain drugs (e.g., metoclopramide and haloperidol) or by cerebrovascular disease (e.g., multiple lacunar strokes). The disease can usually be diagnosed based on the history and physical findings. Dopamine replacement is still considered the most efficacious treatment for Parkinson's disease, but dopamine agonists, formerly prescribed only as adjunctive therapy, are emerging as useful initial therapy. Other pharmacologic treatments include drugs that inhibit dopamine-metabolizing enzymes (monoamine oxidase-B and catechol O-methyltransferase). Injections of botulinum toxin can be helpful in patients with associated dystonia or blepharospasm. Surgery may be indicated for certain patients or when symptoms do not respond to medical therapy. Additional adjunctive therapies include physical therapy, nutritional counseling and techniques to help patients manage emotional and cognitive changes related to the disease. (+info)Neurosurgical tools and techniques--modern image-guided surgery. (7/1495)
Cushing and other great neurosurgeons made their mental preparations for surgical procedures through extensive, beautiful drawings. Three-dimensional visualization was in those days supported through interpretation of pneumoencephalograms with displacements of structures indicating where a space-occupying process might be located. Today this visualization necessary for each neurosurgeon is partly lost in the teaching process due to axial magnetic resonance imaging and computed tomography scans and of minimal invasive techniques. Microsurgical navigation on the brain surface is like sailing along a coastline. Navigating in the brain is like sailing in fog and tools for navigation must be developed accordingly. The robotic microscope Surgiscope enables the surgeon to have at the same time a microscope, a pointing devise and a bidirectional tool for automatic maneuverability in the brain. A neurosurgeon may be distracted and thereby perform less adequate. Computer technology and virtual reality models enhances possibilities for rehearsal of difficult operations and of controlling the surgical performance. Computer technology is thus a supporter of future neurosurgeons and a part of quality control. Future education must be linked to this fact. (+info)The sitting position in neurosurgery: a critical appraisal. (8/1495)
The potential for serious complications after venous air embolism and successful malpractice liability claims are the principle reasons for the dramatic decline in the use of the sitting position in neurosurgical practice. Although there have been several studies substantiating the relative safety compared with the prone or park bench positions, its use will continue to decline as neurosurgeons abandon its application and trainees in neurosurgery are not exposed to its relative merits. How can individual surgeons continue to use this position? Will individual, difficult surgical access cases be denied the obvious technical advantages of the sitting position? Limited use of the sitting position should remain in the neurosurgeon's armamentarium. However, several caveats must be emphasized. Assessment of the relative risk-benefit, based on the individual patient's physical status and surgical implications for the particular intracranial pathology, is of paramount importance. The patient should be informed of the specific risks of venous air embolism, quadriparesis and peripheral nerve palsies. Appropriate charting of patient information provided and special consent issues are essential. An anaesthetic input into the decision to use the sitting position is a sine qua non. The presence of a patient foramen ovale is an absolute contraindication. Preoperative contrast echocardiography should be used as a screening technique to detect the population at risk of paradoxical air embolism caused by the presence of a patent foramen ovale. The technique involves i.v. injection of saline agitated with air and a Valsalva manoeuvre is applied and released. Use of this position necessitates supplementary monitoring to promptly detect and treat venous air embolism. Doppler ultrasonography is the most sensitive of the generally available monitors to detect intracardiac air. The use of a central venous catheter is recommended, with the tip positioned close to the superior vena cava junction with the right atrium, to aspirate intravascular gas. Measures to minimize hypotension associated with the sitting position include a slow, staged positioning over 5-10 min and use of the 'G suit' inflated with compressed air applied to the lower extremities and pelvis. Use of the sitting or upright position for patients undergoing posterior fossa and cervical spine surgery presents unique challenges for the anaesthetist. With appropriate patient selection and preparation, and using prudent intraoperative monitoring and anaesthetic techniques, selected patients should still benefit from the optimum access to mid-line lesions, improved cerebral venous decompression, lower intracranial pressure and enhanced gravity drainage of blood and CSF associated with the sitting position. (+info)Neurosurgical procedures are operations that are performed on the brain, spinal cord, and peripheral nerves. These procedures are typically carried out by neurosurgeons, who are medical doctors with specialized training in the diagnosis and treatment of disorders of the nervous system. Neurosurgical procedures can be used to treat a wide range of conditions, including traumatic injuries, tumors, aneurysms, vascular malformations, infections, degenerative diseases, and congenital abnormalities.
Some common types of neurosurgical procedures include:
* Craniotomy: A procedure in which a bone flap is temporarily removed from the skull to gain access to the brain. This type of procedure may be performed to remove a tumor, repair a blood vessel, or relieve pressure on the brain.
* Spinal fusion: A procedure in which two or more vertebrae in the spine are fused together using bone grafts and metal hardware. This is often done to stabilize the spine and alleviate pain caused by degenerative conditions or spinal deformities.
* Microvascular decompression: A procedure in which a blood vessel that is causing pressure on a nerve is repositioned or removed. This type of procedure is often used to treat trigeminal neuralgia, a condition that causes severe facial pain.
* Deep brain stimulation: A procedure in which electrodes are implanted in specific areas of the brain and connected to a battery-operated device called a neurostimulator. The neurostimulator sends electrical impulses to the brain to help alleviate symptoms of movement disorders such as Parkinson's disease or dystonia.
* Stereotactic radiosurgery: A non-invasive procedure that uses focused beams of radiation to treat tumors, vascular malformations, and other abnormalities in the brain or spine. This type of procedure is often used for patients who are not good candidates for traditional surgery due to age, health status, or location of the lesion.
Neurosurgical procedures can be complex and require a high degree of skill and expertise. Patients considering neurosurgical treatment should consult with a qualified neurosurgeon to discuss their options and determine the best course of action for their individual situation.
A craniotomy is a surgical procedure where a bone flap is temporarily removed from the skull to access the brain. This procedure is typically performed to treat various neurological conditions, such as brain tumors, aneurysms, arteriovenous malformations, or traumatic brain injuries. After the underlying brain condition is addressed, the bone flap is usually replaced and secured back in place with plates and screws. The purpose of a craniotomy is to provide access to the brain for diagnostic or therapeutic interventions while minimizing potential damage to surrounding tissues.
An air embolism is a medical condition that occurs when one or more air bubbles enter the bloodstream and block or obstruct blood vessels. This can lead to various symptoms depending on the severity and location of the obstruction, including shortness of breath, chest pain, confusion, stroke, or even death.
Air embolisms can occur in a variety of ways, such as during certain medical procedures (e.g., when air is accidentally introduced into a vein or artery), trauma to the lungs or blood vessels, scuba diving, or mountain climbing. Treatment typically involves administering oxygen and supportive care, as well as removing the source of the air bubbles if possible. In severe cases, hyperbaric oxygen therapy may be used to help reduce the size of the air bubbles and improve outcomes.
Neurosurgery, also known as neurological surgery, is a medical specialty that involves the diagnosis, surgical treatment, and rehabilitation of disorders of the nervous system. This includes the brain, spinal cord, peripheral nerves, and extra-cranial cerebrovascular system. Neurosurgeons use both traditional open and minimally invasive techniques to treat various conditions such as tumors, trauma, vascular disorders, infections, stroke, epilepsy, pain, and congenital anomalies. They work closely with other healthcare professionals including neurologists, radiologists, oncologists, and critical care specialists to provide comprehensive patient care.
Neuronavigation is a surgical technique that uses imaging technology, such as MRI or CT scans, to create a 3D map of the patient's brain in real-time during surgery. This allows surgeons to accurately locate and navigate to specific areas of the brain with greater precision and less invasiveness, improving surgical outcomes and reducing the risk of complications.
The neuronavigation system typically consists of a computer workstation, tracking systems, and instruments that are equipped with sensors. The system is able to track the position and orientation of these instruments relative to the patient's brain, allowing the surgeon to visualize the location of the instruments on the 3D map in real-time.
Neuronavigation has become an essential tool in many neurosurgical procedures, including tumor resection, functional neurosurgery, and deep brain stimulation. It enables surgeons to perform more complex surgeries with increased safety and efficacy, ultimately improving the quality of care for patients undergoing these procedures.
Amrinone is a pharmacological agent, specifically a positive inotrope, that is used in the treatment of heart failure. It works by increasing the force of heart muscle contractions and improving cardiac output. Amrinone belongs to a class of drugs called phosphodiesterase inhibitors, which increase cyclic AMP levels in the heart, leading to increased contractility.
Here is the medical definition of 'Amrinone':
Amrinone: A synthetic cardiac drug that acts as a positive inotrope and vasodilator. It works by increasing the force of heart muscle contractions and reducing afterload, which improves cardiac output. Amrinone inhibits phosphodiesterase III, leading to increased intracellular cyclic AMP levels and enhanced calcium sensitivity in myocardial cells. It is used in the treatment of congestive heart failure and is administered intravenously.
Rewarming, in a medical context, refers to the process of gradually increasing the body temperature of a person who is experiencing hypothermia. Hypothermia is a condition in which the core body temperature drops below 95°F (35°C), which can be caused by exposure to cold environments or certain medical conditions.
Rewarming can be accomplished through various methods, including:
1. Passive rewarming: This involves removing wet clothing and covering the person with warm blankets to allow their body to naturally increase its temperature.
2. Active external rewarming: This involves using warming devices such as heating pads or warm water bottles to apply heat to the skin surface.
3. Active core rewarming: This involves using more invasive methods, such as warmed intravenous fluids, warm air insufflation, or extracorporeal membrane oxygenation (ECMO) with a heat exchanger, to directly warm the internal organs and blood.
The choice of rewarming method depends on the severity of hypothermia, the presence of other medical conditions, and the resources available. It is important to monitor the person's vital signs and core temperature during rewarming to avoid complications such as rewarming shock or arrhythmias.
The intraoperative period is the phase of surgical treatment that refers to the time during which the surgery is being performed. It begins when the anesthesia is administered and the patient is prepared for the operation, and it ends when the surgery is completed, the anesthesia is discontinued, and the patient is transferred to the recovery room or intensive care unit (ICU).
During the intraoperative period, the surgical team, including surgeons, anesthesiologists, nurses, and other healthcare professionals, work together to carry out the surgical procedure safely and effectively. The anesthesiologist monitors the patient's vital signs, such as heart rate, blood pressure, oxygen saturation, and body temperature, throughout the surgery to ensure that the patient remains stable and does not experience any complications.
The surgeon performs the operation, using various surgical techniques and instruments to achieve the desired outcome. The surgical team also takes measures to prevent infection, control bleeding, and manage pain during and after the surgery.
Overall, the intraoperative period is a critical phase of surgical treatment that requires close collaboration and communication among members of the healthcare team to ensure the best possible outcomes for the patient.
Bacterial meningitis is a serious infection that causes the membranes (meninges) surrounding the brain and spinal cord to become inflamed. It's caused by various types of bacteria, such as Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae type b.
The infection can develop quickly, over a few hours or days, and is considered a medical emergency. Symptoms may include sudden high fever, severe headache, stiff neck, nausea, vomiting, confusion, and sensitivity to light. In some cases, a rash may also be present.
Bacterial meningitis can lead to serious complications such as brain damage, hearing loss, learning disabilities, and even death if not treated promptly with appropriate antibiotics and supportive care. It is important to seek immediate medical attention if you suspect bacterial meningitis. Vaccines are available to prevent certain types of bacterial meningitis.
Central nervous system (CNS) infections refer to infectious processes that affect the brain, spinal cord, and their surrounding membranes, known as meninges. These infections can be caused by various microorganisms, including bacteria, viruses, fungi, and parasites. Examples of CNS infections are:
1. Meningitis: Inflammation of the meninges, usually caused by bacterial or viral infections. Bacterial meningitis is a medical emergency that requires immediate treatment.
2. Encephalitis: Inflammation of the brain parenchyma, often caused by viral infections. Some viruses associated with encephalitis include herpes simplex virus, enteroviruses, and arboviruses.
3. Meningoencephalitis: A combined inflammation of both the brain and meninges, commonly seen in certain viral infections or when bacterial pathogens directly invade the brain.
4. Brain abscess: A localized collection of pus within the brain caused by a bacterial or fungal infection.
5. Spinal epidural abscess: An infection in the space surrounding the spinal cord, usually caused by bacteria.
6. Myelitis: Inflammation of the spinal cord, which can result from viral, bacterial, or fungal infections.
7. Rarely, parasitic infections like toxoplasmosis and cysticercosis can also affect the CNS.
Symptoms of CNS infections may include fever, headache, stiff neck, altered mental status, seizures, focal neurological deficits, or meningeal signs (e.g., Brudzinski's and Kernig's signs). The specific symptoms depend on the location and extent of the infection, as well as the causative organism. Prompt diagnosis and treatment are crucial to prevent long-term neurological complications or death.
Intraoperative monitoring (IOM) is the practice of using specialized techniques to monitor physiological functions or neural structures in real-time during surgical procedures. The primary goal of IOM is to provide continuous information about the patient's status and the effects of surgery on neurological function, allowing surgeons to make informed decisions and minimize potential risks.
IOM can involve various methods such as:
1. Electrophysiological monitoring: This includes techniques like somatosensory evoked potentials (SSEP), motor evoked potentials (MEP), and electroencephalography (EEG) to assess the integrity of neural pathways and brain function during surgery.
2. Neuromonitoring: Direct electrical stimulation of nerves or spinal cord structures can help identify critical neuroanatomical structures, evaluate their functional status, and guide surgical interventions.
3. Hemodynamic monitoring: Measuring blood pressure, heart rate, cardiac output, and oxygen saturation helps assess the patient's overall physiological status during surgery.
4. Imaging modalities: Intraoperative imaging techniques like ultrasound, computed tomography (CT), or magnetic resonance imaging (MRI) can provide real-time visualization of anatomical structures and surgical progress.
The specific IOM methods employed depend on the type of surgery, patient characteristics, and potential risks involved. Intraoperative monitoring is particularly crucial in procedures where there is a risk of neurological injury, such as spinal cord or brain surgeries, vascular interventions, or tumor resections near critical neural structures.
A surgical wound infection, also known as a surgical site infection (SSI), is defined by the Centers for Disease Control and Prevention (CDC) as an infection that occurs within 30 days after surgery (or within one year if an implant is left in place) and involves either:
1. Purulent drainage from the incision;
2. Organisms isolated from an aseptically obtained culture of fluid or tissue from the incision;
3. At least one of the following signs or symptoms of infection: pain or tenderness, localized swelling, redness, or heat; and
4. Diagnosis of surgical site infection by the surgeon or attending physician.
SSIs can be classified as superficial incisional, deep incisional, or organ/space infections, depending on the depth and extent of tissue involvement. They are a common healthcare-associated infection and can lead to increased morbidity, mortality, and healthcare costs.
Postoperative complications refer to any unfavorable condition or event that occurs during the recovery period after a surgical procedure. These complications can vary in severity and may include, but are not limited to:
1. Infection: This can occur at the site of the incision or inside the body, such as pneumonia or urinary tract infection.
2. Bleeding: Excessive bleeding (hemorrhage) can lead to a drop in blood pressure and may require further surgical intervention.
3. Blood clots: These can form in the deep veins of the legs (deep vein thrombosis) and can potentially travel to the lungs (pulmonary embolism).
4. Wound dehiscence: This is when the surgical wound opens up, which can lead to infection and further complications.
5. Pulmonary issues: These include atelectasis (collapsed lung), pneumonia, or respiratory failure.
6. Cardiovascular problems: These include abnormal heart rhythms (arrhythmias), heart attack, or stroke.
7. Renal failure: This can occur due to various reasons such as dehydration, blood loss, or the use of certain medications.
8. Pain management issues: Inadequate pain control can lead to increased stress, anxiety, and decreased mobility.
9. Nausea and vomiting: These can be caused by anesthesia, opioid pain medication, or other factors.
10. Delirium: This is a state of confusion and disorientation that can occur in the elderly or those with certain medical conditions.
Prompt identification and management of these complications are crucial to ensure the best possible outcome for the patient.
Brain neoplasms, also known as brain tumors, are abnormal growths of cells within the brain. These growths can be benign (non-cancerous) or malignant (cancerous). Benign brain tumors typically grow slowly and do not spread to other parts of the body. However, they can still cause serious problems if they press on sensitive areas of the brain. Malignant brain tumors, on the other hand, are cancerous and can grow quickly, invading surrounding brain tissue and spreading to other parts of the brain or spinal cord.
Brain neoplasms can arise from various types of cells within the brain, including glial cells (which provide support and insulation for nerve cells), neurons (nerve cells that transmit signals in the brain), and meninges (the membranes that cover the brain and spinal cord). They can also result from the spread of cancer cells from other parts of the body, known as metastatic brain tumors.
Symptoms of brain neoplasms may vary depending on their size, location, and growth rate. Common symptoms include headaches, seizures, weakness or paralysis in the limbs, difficulty with balance and coordination, changes in speech or vision, confusion, memory loss, and changes in behavior or personality.
Treatment for brain neoplasms depends on several factors, including the type, size, location, and grade of the tumor, as well as the patient's age and overall health. Treatment options may include surgery, radiation therapy, chemotherapy, targeted therapy, or a combination of these approaches. Regular follow-up care is essential to monitor for recurrence and manage any long-term effects of treatment.
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.