If ever there were a workhorse imaging modality for brain applications, magnetic resonance imaging (MRI) would fit that description. Using a variety of specific techniques to assess both anatomy and function, MRI methods have been propelled by improved image quality facilitated by higher field strength magnets, and development of new techniques for evaluating specific portions of the complex structures in the brain.
“MRI is the primary imaging tool in the brain for all indications with the exception perhaps for trauma,” says Vincent Matthews, M.D., chief of neuroradiology and professor of radiology at the Indiana University School of Medicine in Indianapolis. “For every other indication, it has supplanted CT [computed tomography] as the definitive imaging test for neurologic symptoms.”
“If you’re serious about finding something in the brain, MR is best,” concurs R. Anthony Lloyd, II, M.D., director of neuroradiology, Mercy Medical Center in Baltimore (Md.). However, for patients with head trauma, CT remains the best alternative because skull anatomy provides critical data, while MR contributes the best visualization of soft tissues in the brain.
Lloyd notes that often patients experience a seizure, but have a normal CT scan. An MR study through the temporal lobes that demonstrates mesotemporal sclerosis furnishes additional diagnostic information not available through CT.
William P. Dillon, M.D., professor of radiology at the University of California San Francisco Medical Center describes many roles for brain MRI from vascular disease, stroke and Transient Ischemic Attack (TIA), to localizing specific structures important to treatment. Dillon describes their use of 1.5 Tesla scanners from both GE Medical Systems (Waukesha, Wis.) and Siemens Medical Solutions (Iselin, N.J.) to perform anatomic studies to direct Gamma Knife therapy for epilepsy, and to examine metabolic function during clinical research trials of MR spectroscopy that allows monitoring of brain neoplasms. Additionally, MRI studies are useful in evaluation of developmental delays in pediatric patients.
Stroke management
Victims of stroke require expert time-sensitive management. Current treatment protocols define a three hour window of opportunity in administering thrombolytic drugs such as tPA.
Norman J. Beauchamp, Jr. M.D., M.H.S., a neuroradiologist at Johns Hopkins University Hospital in Baltimore, Md., explains that increasing that treatment window to six hours would enable benefit to additional patients who do not seek treatment in the shorter time period. Since strokes may not produce pain patients often ignore initial symptoms. Confusion is a hallmark of stroke, which often results in a lack of action. Additionally, strokes occur most frequently among elderly patients who may live alone.
Please refer to the July 2002 issue for the complete story. For information on article reprints, contact Martin St. Denis
