CENTRAL-NERVOUS-SYSTEM IMAGING - WHEN IS CT MORE APPROPRIATE THAN MRI

Over the past 25 years, the development of noninvasive imaging techniq ues has allowed exquisite display of the anatomic structures of the br ain and spinal cord in normal and disease states. CT remains useful be cause of short imaging times, widespread availability, ease of access, sensitive detection of calcification and hemorrhage, and resolution o f bony detail. MRI offers superior soft-tissue contrast, excellent vis ualization of vascular structures, fewer artifacts, and imaging in any plane. Cost and use of ionizing radiation are considerations in choos ing the most appropriate procedure. In the future, CT and MRI applicat ions that concentrate on functional and physiologic display of die CNS will add greatly to the clinical utility of these imaging tools.