Significance of magnetic resonance angiography-diffusion weighted imaging mismatch in hyperacute cerebral infarction.

Therapeutic results with respect to lesion size were analyzed and compared in patients with hyperacute cerebral infarction with and without major artery lesions on magnetic resonance angiography (MRA) and in those who did and did not receive intravenous (IV) tissue plasminogen activator (t-PA). Of the patients with cerebral infarction who visited the hospital within 3 hours of onset between April 2007 and September 2009, 127 patients with cerebral infarction in the anterior circulation region in whom head magnetic resonance imaging (diffusion-weighted imaging [DWI]) or MRA was performed (81 men and 46 women; mean age, 71 ± 11 years) were enrolled. Major artery lesions (+) were defined as internal carotid artery occlusion and middle cerebral artery (M1/M2 segment) occlusion and ≥50% stenosis. Based on the presence or absence of major artery lesions and the size of DWI lesions, the subjects were divided into 3 groups: MRA-DWI mismatch (+) group [major artery lesion (+) and DWI-ASPECTS ≥6], MRA-DWI mismatch (-) group [major artery lesion (+) and DWI-ASPECTS <6], and major artery lesion (-) group. IV t-PA was given to 21 of the 64 patients in the MRA-DWI mismatch (+) group, to 1 of the 24 patients in the MRA-DWI mismatch (-) group, and to 9 of the 39 patients in the major artery lesion (-) group. In the MRA-DWI mismatch (+) group (n = 64), the median National Institutes of Health Stroke Scale (NIHSS) score on admission was higher in t-PA-treated patients than in t-PA-untreated patients (15 vs 11). The modified Rankin scale (mRS) score at day 90 after onset was more favorable in t-PA-treated patients (0-2 in 10 patients [48%] and 3-6 in 11 patients [52%]) than in t-PA-untreated patients (0-2 in 12 patients [28%] and 3-6 in 31 patients [72%]). After adjusting for admission NIHSS score, there was a significant difference in outcome (mRS score) between t-PA-treated patients (0-2 in 10 patients [48%] and 3-6 in 11 patients [52%]) and t-PA-untreated patients (0-2 in 3 patients [9%] and 3-6 in 29 patients [91%]) (P = .002). In the MRA-DWI mismatch (-) group (n = 24), mRS scores at day 90 after onset were poor in both t-PA-treated (3-6 in 1 patient [100%]) and t-PA-untreated patients (0-2 in 1 patient [4%] and 3-6 in 22 patients [96%]). In the major artery lesion (-) group (n = 39), mRS scores at day 90 after onset were favorable in both t-PA-treated (0-2 in 9 patients [100%]) and t-PA-untreated patients (0-2 in 28 patients [93%] and 3-6 in 2 patients [7%]). When comparing major artery lesions in the MRA-DWI mismatch (+) group, outcomes were more favorable in patients with M1/M2 segment lesions who received t-PA than in those who did not receive t-PA. In the MRA-DWI mismatch (+) group, the prognosis was significantly better for t-PA-treated patients than for t-PA-untreated patients, suggesting that IV t-PA is indicated in patients with MRA-DWI mismatch.