MAGNETIC-RESONANCE-IMAGING CORRELATES OF TRANSIENT CEREBRAL ISCHEMIC ATTACKS

Background and Purpose MRI of patients with a transient ischemic attac k (TIA) may provide more detailed morphological insights than CT. We t herefore studied the frequency and type of TLA-related infarcts shown by MRI, examined the utility of intravenous contrast material, and sea rched for potential predictors of infarct occurrence. Methods We perfo rmed 1.5-T MRI of the brain on 62 patients (age range, 28 to 93 years; mean, 61 years) with a hemispheric TIA. Contrast material (Cd-DTPA) w as given to 45 individuals. We recorded type, number, size, and locati on of ischemic brain lesions and related the presence of acute infarct ion to features of clinical presentation and probable causes for the T IA. Results MRI showed focal ischemic lesions in 50 patients (81%), bu t an acute TIA-associated infarct was seen in only 19 subjects (31%). In patients with an acute lesion, the infarcts were smaller than 1.5 c m in 13 (68%), purely cortical in 11 (58%), and multiple in 7 (37%) in dividuals. Contrast enhancement contributed to the delineation of an a cute lesion in only 2 of 45 patients (4%). Acute infarction was unpred ictable by clinical TIA features, but the frequency of identifiable va scular or cardiac causes was significantly higher in those patients wi th TLA-related morphological damage (odds ratio, 5.2 [95% confidence i nterval, 1.6 to 17.3]). Conclusions More than two thirds of TIA patien ts showed no associated brain lesion even when MRI and contrast materi al were used, but the overall frequency of ischemic damage was high. T IA-related infarcts on MRT were mostly small and limited to the cortex and tended to consist of multiple lesions. A positive MRI underscores the need for comprehensive diagnostic workup since evidence of infarc tion appears to be associated with a higher frequency of significant v ascular or cardiac disorders.