Improved prediction of final infarct volume using bolus delay-corrected perfusion-weighted MRI: implications for the ischemic penumbra.
OBJECTIVE
Magnetic resonance imaging (MRI)-based perfusion measures using dynamic susceptibility contrast are extremely useful for identification of ischemic penumbral tissue in acute stroke. However, errors in the measurement of cerebral blood flow (CBF) and mean transit time (MTT) can occur. The aim of this study was to investigate whether bolus delay-corrected (BDC) perfusion measures enable better delineation of the ischemic penumbra.


METHODS
Diffusion-weighted MRI (DWI) and perfusion-weighted MRI data were acquired from 19 acute stroke patients. Perfusion abnormalities were manually defined on BDC perfusion maps (corrected MTT [cMTT] and corrected CBF [cCBF]), and on maps derived from an arterial input function placed within the contralateral (CBF, MTT) and ipsilateral (ipsilateral CBF [iCBF] and ipsilateral MTT [iMTT]) middle cerebral artery. Perfusion lesion volumes were correlated with 30-day T2-weighted MRI lesion volumes and with clinical outcome using the National Institutes of Health Stroke Scale (NIHSS).


RESULTS
Spearman correlation coefficients for comparing lesion volumes delineated on DWI, CBF, iCBF, cCBF, MTT, iMTT, and cMTT maps with 30-day T2-weighted lesion volumes were 0.72, 0.87, 0.88, 0.90, 0.84, 0.92, and 0.96, respectively (all P<0.001). The analogous correlation coefficients for comparing 30-day National Institutes of Health Stroke Scale (NIHSS) scores were 0.39 (NS), 0.69 (NS), 0.75 (P<0.001), 0.62 (NS), 0.72 (P<0.001), 0.78 (P<0.001), and 0.83 (P<0.001), respectively.


CONCLUSIONS
Uncorrected perfusion lesion volumes overestimated the extent of ischemic injury. BDC perfusion measures (cMTT) correlated more accurately with final lesion volume and clinical outcome. Such measures offer an improved estimation of the final infarct size in acute stroke.
Centre for Magnetic Resonance, University of Queensland 4072, Brisbane, Australia. Stephen.Rose@cmr.uq.edu.au
Stephen E
SE
Rose
Andrew L
AL
Janke
Mark
M
Griffin
Simon
S
Finnigan
Jonathan B
JB
Chalk
D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000098:blood supply / Q000473:pathology; D020520:Brain Infarction / Q000175:diagnosis*; D002560:Cerebrovascular Circulation; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged