Predicting cerebral ischemic infarct volume with diffusion and perfusion MR imaging.
OBJECTIVE
Diffusion and perfusion MR imaging have proved useful in the assessment of acute stroke. We evaluated the utility of these techniques in detecting acute ischemic infarction and in predicting final infarct size.


METHODS
Diffusion and hemodynamic images were obtained in 134 patients within a mean of 12.3 hours of onset of acute ischemic stroke symptoms. We retrospectively reviewed patient radiology reports to determine the presence or absence of lesion identification on initial diffusion- (DW) and perfusion-weighted (PW) images. Radiologists were not blinded to the initial clinical assessment. For determination of sensitivity and specificity, the final discharge diagnosis was used as the criterion standard. Neurologists were not blinded to the DW or PW imaging findings. In 81 patients, acute lesions were compared with final infarct volumes.


RESULTS
Sensitivities of DW imaging and cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT) perfusion parameters were 94%, 74%, 84%, and 84%, respectively. Specificities of DW imaging, CBV, CBF, and MTT were 96%, 100%, 96%, and 96%, respectively. Results were similar in 93 patients imaged within 12 hours. In 81 patients with follow-up, regression analysis yielded r(2) = 0.9, slope = 1.24 for DW imaging; r(2) = 0.84, slope = 1.22 for CBV; r(2) = 0.35, slope = 0.44 for CBF; and r(2) = 0.22, slope = 0.32 for MTT, versus follow-up volume. A DW-CBV mismatch predicted additional lesion growth, whereas DW-CBF and DW-MTT mismatches did not. Results were similar in 60 patients imaged within 12 hours.


CONCLUSIONS
Diffusion and hemodynamic images are sensitive and specific for detecting acute infarction. DW imaging and CBV best predict final infarct volume. DW-CBV mismatch predicts lesion growth into the CBV abnormality. CBF and MTT help identify additional tissue with altered perfusion but have lower correlation with final volume.
Schaefer
Pamela W
PW
Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA. pschaefer@partners.org
Hunter
George J
GJ
He
Julian
J
Hamberg
Leena M
LM
Sorensen
A Gregory
AG
Schwamm
Lee H
LH
Koroshetz
Walter J
WJ
Gonzalez
R Gilberto
RG
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001783:Blood Flow Velocity / Q000502:physiology; D002545:Brain Ischemia / Q000175:diagnosis* / Q000503:physiopathology; D002544:Cerebral Infarction / Q000175:diagnosis* / Q000503:physiopathology; D002560:Cerebrovascular Circulation / Q000502:physiology; D038524:Diffusion Magnetic Resonance Imaging; D005189:False Positive Reactions; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D002546:Ischemic Attack, Transient / Q000175:diagnosis / Q000503:physiopathology; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D013997:Time Factors