Detection of Diffusion-Weighted MRI Abnormalities in Patients With Transient Ischemic Attack

Abstract

Background and Purpose— Although diffusion-weighted MRI (DWI) has demonstrated clear superiority over other conventional imaging modalities in the detection of hyperacute cerebral ischemia, its value in the evaluation of patients with transient symptoms has received only limited attention. We assessed the utility of DWI in patients with transient ischemic attack (TIA) to further evaluate the usefulness of this technique in these individuals. Methods— A retrospective analysis was performed on all patients entered in the Stanford Stroke Center database during 1997–2001 who were clinically diagnosed with a TIA and who had also undergone a DWI scan ≤3 days after symptom onset. The relationship between DWI-detected findings and patients’ clinical presentation was then analyzed. Results— Seventy-five patients experiencing 78 TIAs who also underwent DWI within 3 days of symptom onset were identified. DWI-detected abnormalities were present in 16 of 78 cases (21%). Patients with positive DWI scans were 9.6 times more likely to have had symptom duration ≥1 hour, 16 times more likely to have had motor deficits, and 25 times more likely to have had aphasia than patients with negative DWI scans. The combination of all 3 symptoms was 100% specific for an abnormality on DWI. In 7 of 16 cases (44%), a DWI abnormality was present on both DWI and conventional imaging (T2-weighted imaging or fluid-attenuated inversion recovery [FLAIR]). In all of these cases the DWI clarified the extent or acuity of the lesion (n=7) or identified additional lesions not detected by conventional imaging (n=9). Conclusions— In TIA patients, symptom duration ≥1 hour, motor deficits, and aphasia were each independently correlated with detecting an abnormality with DWI. DWI was also helpful in differentiating between chronic versus acute lesions. These data may be of value in identifying those TIA patients for whom MRI evaluation with DWI is of greatest clinical utility.