Relationship between Detectability of Ischemic Lesions by Diffusion-Weighted Imaging and Embolic Sources in Transient Ischemic Attacks

Abstract

Background/Aims: The aim of this study is to clarify the relationship between lesion detectability by diffusion-weighted magnetic resonance imaging (DWI) and the etiology of transient ischemic attacks (TIAs). Methods: A retrospective study was performed on 72 patients with carotid TIAs who underwent DWI studies within 2 weeks after the last episode. Results: Lesions were detected in 24 of 72 patients (33%). The detectability of lesions was 12% (3/25) in the large-artery atherosclerosis (LA) group, 57% (8/14) in the cardioembolism (CE) group, 8% (1/13) in the small-artery occlusion (SA) group, and 60% (12/20) in the other etiology or undetermined etiology (UD) group. Detectabilities in the CE group and the UD group were higher than those in the LA and SA groups. Of 24 patients with DWI-positive lesions, 17 (71%) had embolic sources in the heart; 9 were classified in the UD group because they had embolic sources both in the heart and large artery. Conclusion: Ischemic DWI lesions in TIAs are most likely caused by a cardioembolic mechanism. In TIA patients showing lesions on DWI, heart disease should be surveyed as the possible embolic source.