Stroke is a common and serious disorder. On average, every 40 seconds, someone in the United States has a stroke with an estimated mortality rate of 5.5%.
MRI has been demonstrated to be very sensitive for early detection of acute stroke (ischemia )- as early as 15 min. It is an essential examination for all stroke patients.
A comprehensive MR stroke protocol has three essential components:
Magnetic resonance angiography (MRA) is one of the innovations in the field of MRI to evaluate both healthy and diseased vessels in the brain ,neck and other parts of body without the use of any IV contrast. However , contrast may be given in some cases.
MRA is particularly valuable in screening for atherosclerosis, or hardening of the arteries. Over time, fat can be deposited along the walls of medium and large arteries in the body, causing them to become narrowed or even blocked. This blockage can eventually lead to a transient ischemic attack or even a stroke.
MRA helps to detect a brain aneurysm, which is an abnormal widening or ballooning of a cerebral vessel. Brain aneurysms occur when an injury or congenital defect weakens the wall of the vessel. Aneurysms are particularly dangerous because they can burst and cause potentially fatal intracranial bleeding.
MRA is helpful in assessing vascular malformations, which occur when blood fail to develop normally before birth. The affected vessels become tangled and change the normal flow of the blood through the brain. Some patients have headaches and seizures, but others have hemorrhage and subsequent neurologic damage
MRA may aid in evaluating some types of headaches.
In addition, because MRA relies on the natural magnetic properties of hydrogen atoms in the body, injections of contrast material are not always needed. This feature is especially important in patients who have had allergic reactions to contrast agents or have renal impairmrnt.
One drawback of MRA is that it does not depict small vessels or extremely slow blood flow as well as conventional angiography does. However, with its advantages, MRA is a good examination for many patients.
The advent of high-resolution MRI with a dedicated epilepsy protocol has significantly increased the frequency with which pathologic causes for epilepsy are identified. This has had a dramatic clinical impact on the evaluation and management of epilepsy, because MRI findings can assist with classification, determine prognosis for remission, predict long-term intractability to antiepileptic medications, and identify potential surgical candidates.The International League Against Epilepsy (ILAE) guidelines for neuroimaging in patients with epilepsy (1997) recommends a dedicated epilepsy protocol MRI for all patients with a new-onset seizure.
Epilepsy protocol includes the entire brain from nasion to inion, T1-weighted MPRAGE or SPGR images 1.5-mm slice thickness with no intervening gap. These images are acquired in a coronal oblique plane perpendicular to the long axis of the hippocampus, which is particularly important when evaluating temporal lobe epilepsy (TLE).
The sequence enhances gray/white matter differentiation, which is crucial to the analysis of cortical architecture.An epilepsy protocol MRI also includes coronal and axial FLAIR sequences with a 2- to 3-mm slice thickness and a 0- to 1-mm interslice gap. A conventional thin-slice (3-mm), T2-weighted, axial and coronal sequence is also obtained.
Hippocampal sclerosis (HS) is characterized by neuronal loss and gliosis. HS is the most common pathologic substrate of surgically treated epilepsy in adults and is seen in 67% of patients. When evaluating the medial temporal structures (hippocampus, amygdala, entorhinal cortex, and parahippocampal gyrus), one should evaluate the size, signal, shape, and dual pathology (SSSD).
Magnetic resonance cholangiopancreatography (MRCP) is a special type of MRI exam that produces detailed images mainly of gallbladder, bile ducts, pancreas and pancreaticduct..
It provides a non invasive alternative to Endoscopic Retrograde Cholangiopancreatography (ERCP).
MRCP beautifully demonstrates the CBD without use of any oral or intravenous contrast. It helps to examine diseases of the liver, gallbladder, bile ducts, pancreas and pancreatic duct. These may includes stones, tumors or infection.
Magnetic Resonance (MR) spectroscopy is a noninvasive diagnostic test for measuring biochemical changes in the brain, especially the presence of tumors. While magnetic resonance imaging (MRI) identifies the anatomical location of a tumor, MR spectroscopy compares the chemical composition of normal brain tissue with abnormal tumor tissue. This test can also be used to detect tissue changes in stroke and epilepsy.
MR spectroscopy is conducted on the same machine as conventional MRI . Spectroscopy is a series of tests that are added to the MRI scan of your brain or spine to measure the chemical metabolism of a suspected tumor.
There are several different metabolites, or products of metabolism, that can be measured to differentiate between tumor types:
The frequency of these metabolites is measured in units called parts per million (ppm) and plotted on a graph as peaks of varying height By measuring each metabolite’s ppm and comparing it to normal brain tissue, the neuroradiologist can determine the type of tissue present.
The following MR spectroscopy graph shows the different chemical peaks of a suspected brain tumor-
MRS of brain tumor showing different chemical metabolite.
MR spectroscopy can be used to determine tumor type and aggressiveness, and distinguish between tumor recurrence and radiation necrosis. Different metabolites can indicate:
Unlike a mammogram, which uses X-rays to create images of the breast, breast MRI uses magnets and radio waves to produce detailed 3-dimensional images of the breast tissue. You may need to have a contrast (dye) injected into your arm through an intravenous line. The contrast will help any potentially cancerous breast tissue show up more clearly.This helps the radiologist determine which areas could possibly be cancerous. More tests may be needed after breast MRI to confirm whether or not any suspicious areas are actually cancer.
You will need to open your hospital gown in front to expose your breasts. Then you lie on your stomach on a padded platform with cushioned openings for your breasts. Each opening is surrounded by a breast coil, which is a signal receiver that works with the MRI unit to create the images. The platform then slides into the center of the tube-shaped MRI machine. You won’t feel the magnetic field and radio waves around you, but you will hear a loud thumping sound. You will need to be very still during the test, which takes around 30 to 45 minutes.
We have MR compatible Boyle's apparatus in our MR suite to deliver anesthesia for patient requiring sedation during MRI