Abstract WMP14: Perfusion Weighted Imaging Findings in Acute TIA Patients Predict Subsequent Infarction

Abstract

Introduction: Perfusion weighted imaging (PWI) increases the yield of MRI for the detection of ischemic lesions in TIA patients. We investigate whether PWI predicts the occurrence of acute diffusion weighted imaging (DWI) lesions on follow-up MRI. Methods: Consecutive patients over the age of 18 who were suspected to have a TIA were prospectively enrolled. Patients with technically adequate baseline DWI/PWI and 5 day follow-up DWI were eligible. PWI lesions were identified, blinded to clinical information, as a focal delay on MTT and/or TTP maps. Lesions were confirmed by two stroke neurologists. The baseline and follow-up MRIs were then compared to determine if a new DWI lesion had developed on follow-up and if it was located in the same brain region as the baseline PWI lesion. Results: Seventy percent (94/120) of the enrolled patients were eligible for these analyses. Mean age was 63 years (SD 13) and median ABCD 2 score was 5 (IQR 3, 5). The median delay from symptom onset to baseline MRI was 261 minutes (IQR 131-587); median delay to follow-up MRI was 5 days (IQR 3, 7). Acute ischemic lesions were present on the baseline DWI in 20 patients (21%). The baseline PWI revealed an ischemic lesion in 38 patients (41%). Acute PWI lesion were detected on both MTT and TTP maps in 34 (90%); MTT alone 2 (5%) and TTP alone 2 (5%). Combining DWI and PWI revealed an acute ischemic lesion in 42 patients (45%) distributed as follows: DWI+/PWI+ =16 (17%); DWI+/PWI- 4 (4%), DWI-/PWI+ 22 (23%), DWI-/PWI- 52 (55%). Every positive DWI lesion at baseline (n=20) continued to be DWI positive at follow up. In addition, 10 new DWI lesions were detected. Seven of these were in the same location as a positive baseline PWI lesion and 2 were both outside and inside the area of the initial perfusion deficit ; 1 was in a region that was normal at baseline. Therefore, 9/22 (41%) of the solated PWI lesions at baseline progressed to infarction. Conclusions: Early DWI lesions in patients presenting with transient neurologic symptoms were not reversible at 5 days. Early isolated PWI lesions were seen in about one fourth of these patients and nearly half progressed to infarction. These results substantiate the value of PWI for confirming the diagnosis of an ischemic lesion in patients with suspected TIA.