Diffusion-weighted MRI: Detection of cerebral ischemia before and after carotid thromboendarterectomy

Purpose: Conventional postoperative evaluation of patients following caroti d thromboendarterectomy (TEA) consists bf a clinical neurologic examination to assess neurologic deficits, color duplex ultrasound to document the sur gically reestablished patency of the carotid artery, and CT for exclusion o f postoperative ischemic infarctions. Recent studies prove that diffusion-w eighted MRI is more sensitive in the detection of fresh insults than conven tional MRI and CT. The objective of the study was to ascertain the incidenc e of clinically asymptomatic peri- and postoperative ischemic infarctions V isualized at MRI. Method: We included 52 patients in the study. Fifty-one patients (31 men, 2 0 women; average age 68 years) underwent cranial MR examination including a diffusion-weighted sequence at 24 h prior to carotid TEA and again 24 h fo llowing the procedure. One patient did not agree to participate. Results: In 29 of 51 patients (56%), neither the pre- nor the postoperative MR scans showed any diffusion abnormalities. In 16 patients (31%), however , preoperative MRI detected fresh ischemic insults. In nine patients (17.6% ), the size of the insult resulted in surgery being postponed for 4 weeks. In six patients (11.8%), postoperative MRI returned findings of fresh distu rbances of diffusion suggestive of ischemia that were not visualized on pre operative scans. Discrete neurologic deficits were observed in only two (3. 9%) of these patients. Deficits were transient and disappeared within 72 h. Conclusion: Our findings underscore MRI's capacity for visualizing perioper ative ischemic events. Moreover, MRI provides evidence of clinically asympt omatic embolisms that occur perioperatively.