HIGH SIGNAL INTENSITY ON T2-WEIGHTED MAGNETIC-RESONANCE-IMAGING AND CEREBRAL HEMODYNAMIC RESERVE IN CAROTID OCCLUSIVE DISEASE

Background and Purpose The importance of MR imaging in carotid artery disease is unclear. We evaluated the sensitivity and specificity of th e high signal intensity changes on MR images for diagnosis of hemodyna mically compromised unilateral internal carotid artery disease, Method s We evaluated tile association of high signal intensities on T2-weigh ted MR images with changes in cerebral per fusion reserve measured usi ng Tc-99m-hexamethylpropyleneamine oxime single-photon emission CT and acetazolamide in 23 patients. Results Eleven patients had a type I re sponse (normal flow and normal perfusion reserve), 8 patients had a ty pe II response (normal flow and decreased perfusion reserve), and 4 pa tients had a type III response (decreased flow and decreased perfusion reserve). High signal intensities in the centrum semiovale (11/12) an d/or posterior periventricular white matter (6/12) were frequently see n in the hemodynamically compromised groups. Extensive high signal int ensities were associated with severely impaired cerebral circulation. MR imaging had high sensitivity (0.92) and specificity (1.0) in predic ting hemodynamically compromised patients when we used the presence of T2 high intensity in the centrum semiovale as a criterion. Conclusion s The centrum semiovale T2 hyperintensities lateralized to the side of carotid occlusion are specific and sensitive for the presence and sev erity of hemodynamic compromise from carotid occlusive disease.