Fragmentation of the classical magnetic resonance mismatch "penumbral" pattern with time.
OBJECTIVE
The classical mismatch pattern in the middle cerebral artery territory stroke on MR is defined by a central diffusion-weighted image core with surrounding mismatch tissue. Because of variable rates of tissue salvage, we hypothesized that this pattern may fragment over time and may be influenced by vessel patency, mismatch volume, and infarct core location.


METHODS
Patients were recruited with MR studies performed within 48 hours of ischemic stroke. Mismatch patterns based on diffusion-weighted/perfusion-weighted images were categorized as classical (majority of the diffusion-weighted image within the perfusion-weighted image lesion) or nonclassical (fragmented) patterns. The proportion of patterns was assessed with reference to time, vessel patency, mismatch volume, and infarct core location.


RESULTS
Sixty-seven patients (33 classical [49.3%] and 34 nonclassical patterns [50.7%]) were studied within 48 hours (median age, 74.0 years). Compared to the nonclassical pattern, the classical pattern had a shorter time to MR (3.4 hours vs 10.4 hours; P=0.004) and a larger mismatch volume (62.0 mL vs 3.5 mL; P<0.0001). The positive predictors for the classical pattern were earlier time, vessel occlusion, superficial core location, and larger mismatch volume.


CONCLUSIONS
The classical mismatch pattern may fragment with time. Over 48 hours the classical pattern is seen earlier after stroke onset, with higher rates of vessel occlusion and larger mismatch volumes.
Ma
Henry
H
National Stroke Research Institute, Austin Health, University of Melbourne, 300 Waterdale Rd, Heidelberg West, Vic 3081, Australia.
Zavala
Jorge A
JA
Teoh
Hock
H
Churilov
Leonid
L
Gunawan
Marveyles
M
Ly
John
J
Wright
Peter
P
Phan
Thanh
T
Arakawa
Shuji
S
Davis
Stephen M
SM
Donnan
Geoffrey A
GA
D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000098:blood supply* / Q000473:pathology* / Q000503:physiopathology; D020520:Brain Infarction / Q000175:diagnosis / Q000503:physiopathology; D002545:Brain Ischemia / Q000175:diagnosis / Q000503:physiopathology; D015331:Cohort Studies; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D018450:Disease Progression; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D020244:Infarction, Middle Cerebral Artery / Q000175:diagnosis* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000473:pathology* / Q000503:physiopathology; D055420:Perfusion Imaging / Q000379:methods; D011237:Predictive Value of Tests; D011379:Prognosis; D012680:Sensitivity and Specificity; D013997:Time Factors