MRI scan
During a MRI scan, pictures of almost all the tissue in the body are taken. The tissue that has the least hydrogen atoms, such as the bones turns out dark. The tissues that have many hydrogen atoms, such as fatty tissue looks much brighter. The timing of the radio wave pulses is constantly changed to gain information about the different types of tissues present. An MRI scan is normally used as an extremely accurate method of disease detection and structural abnormalities throughout the body.
Patient with any metallic materials within the body must notify their physician prior to the MRI scan. This is because, metallic chips, materials, metal implants, surgical clips or foreign materials (artificial joints, metallic bone plates or prosthetic devices, etc) can significantly distort the images obtained by an MRI scanner. Patients with pacemakers, metal chips or clips in and around the eyeballs cannot be scanned by an MRI because of the risk that the magnet may move the metal in these areas. Patients with artificial heart valves, metallic ear implants, bullet fragments and chemotherapy or insulin pumps should not undergo MRI scanning.
MRI scan can cause a small risk to the fetus in the first 12 weeks of pregnancy. Therefore scans are not performed on pregnant women. The MRI machine produces loud thumping and humming noise when the procedure is performed. Therefore ear plugs are usually given to the patients to reduce the noise. MRI scans are a useful aid in the assessment of certain back conditions. MRI is an aid to detail studies of nerve root injuries like lumbar disc herniation and lumbar spinal stenosis. It is also extensively used in spinal disc and lumbar disc diseases and isthmic spondylolisthesis. It is also useful to rule out tumors and spinal infections.
Myelogram
Myelogram is a diagnostic test that helps in detecting abnormalities of the spine, spinal cord and spinal fluid. A contrast dye is injected into the the neck area (cisternal myelogram) or in the lower back area (lumbar myelogram). Any abnormality or indentation on the spinal cord can be identified with a myelogram test. A bulging disc, tumor or herniated disk can lead to indentations on the spinal cord. A myelogram is conducted for patients who suffer spinal stenosis, herniated disc or inflammation of the arachnoid membrane. Myelogram aids in diagnosing problems of blood supply to the spine and tumors.
A myelogram is ideal for patients who have had metal implants in their spine, preventing them from undergoing an MRI scan or CT scan. A spinal tap is performed to inject the dye into the spinal sac. When combined with a CT scan, a myelogram helps in understanding the condition of the spinal bones and muscles. A patient scheduled for a myelogram must not eat for few hours prior to the test. Pregnant women and those with a history of asthma or epilepsy must keep the doctor informed.
Fluid intake must be maintained so as to remain well hydrated. Medications such as blood thinners, antidepressants and diabetes medicines may need to be temporarily stopped. A person is asked to lie down with head in elevated position for few hours after the myelogram test. The risks associated with a myelogram include meningitis, spinal headache and allergic reactions.
Stenosis
Unusual narrowing of the blood vessels or other tubular structures or organs is referred to as stenosis. In simple words stenosis means narrowing of the various body parts. The common causes for stenosis include birth defects, inflammation, neoplasm (abnormal proliferation of cells), ischemia (reduction of blood supply thus damaging tissues), infection, iatrogenic (complications arising from any treatment) and atherosclerosis.
Spinal stenosis: Specific causes include rheumatoid arthritis, osteoarthritis, aging, spinal injury or tumor and spondylosis. Symptoms include pain and weakness in the legs along with cramps, imbalance and loss of control over bladder and bowel movements.
Mitral valve stenosis: Specific causes include endocarditis, atrial myoxma, rheumatic fever and Lutembacher syndrome. Symptoms of mitral valve stenosis are fatigue, recurrent respiratory infections and swelling in the feet.
Aortic valve stenosis: This type of stenois may be caused by rheumatic fever, Williams syndrome, LDL receptor deficiency and senile or bicuspid aortic valves. The typical symptoms of aortic valve stenosis are chest pain and heart murmur, fatigue and shortness of breath and heart palpitations.
Pulmonary valve stenosis: Specific causes include deformity during fetal development, rheumatic fever and endocarditis. This type of stenosis is symptomized by cough and fatigue, fluid retention and shortness of breath.
Treatment differs according to the type of stenosis. While physical therapy, drugs like analgesics and lumbar brace are used to manage spinal stenosis, aortic valve stenosis and pulmonary valve stenosis are treated with valve replacement surgery.
Bibliography / Reference
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