Refining the perfusion-diffusion mismatch hypothesis

Butcher, K. S., Parsons, M., MacGregor, L., Barber, P. A., Chalk, J., Bladin, C., Levi, C., Kimber, T., Schultz, D., Fink, J., Tress, B., Donnan, G and Davis, S. (2005) Refining the perfusion-diffusion mismatch hypothesis. Stroke, 36 6: 1153-1159. doi:10.1161/01.STR.0000166181.86928.8b

Author Butcher, K. S.
Parsons, M.
MacGregor, L.
Barber, P. A.
Chalk, J.
Bladin, C.
Levi, C.
Kimber, T.
Schultz, D.
Fink, J.
Tress, B.
Donnan, G
Davis, S.
Title Refining the perfusion-diffusion mismatch hypothesis
Journal name Stroke   Check publisher's open access policy
ISSN 0039-2499
Publication date 2005
Sub-type Article (original research)
DOI 10.1161/01.STR.0000166181.86928.8b
Volume 36
Issue 6
Start page 1153
End page 1159
Total pages 7
Language eng
Subject 321003 Cardiology (incl. Cardiovascular Diseases)
Abstract Background and Purpose-The Echoplanar Imaging Thrombolysis Evaluation Trial ( EPITHET) tests the hypothesis that perfusion-weighted imaging (PWI)-diffusion-weighted imaging (DWI) mismatch predicts the response to thrombolysis. There is no accepted standardized definition of PWI-DWI mismatch. We compared common mismatch definitions in the initial 40 EPITHET patients. Methods-Raw perfusion images were used to generate maps of time to peak (TTP), mean transit time (MTT), time to peak of the impulse response (Tmax) and first moment transit time (FMT). DWI, apparent diffusion coefficient ( ADC), and PWI volumes were measured with planimetric and thresholding techniques. Correlations between mismatch volume (PWIvol-DWIvol) and DWI expansion (T2(Day) (90-vol)-DWIAcute-vol) were also assessed. Results-Mean age was 68 +/- 11, time to MRI 4.5 +/- 0.7 hours, and median National Institutes of Health Stroke Scale (NIHSS) score 11 (range 4 to 23). Tmax and MTT hypoperfusion volumes were significantly lower than those calculated with TTP and FMT maps (P < 0.001). Mismatch >= 20% was observed in 89% (Tmax) to 92% (TTP/FMT/MTT) of patients. Application of a +4s ( relative to the contralateral hemisphere) PWI threshold reduced the frequency of positive mismatch volumes (TTP 73%/FMT 68%/Tmax 54%/MTT 43%). Mismatch was not significantly different when assessed with ADC maps. Mismatch volume, calculated with all parameters and thresholds, was not significantly correlated with DWI expansion. In contrast, reperfusion was correlated inversely with infarct growth (R= -0.51; P = 0.009). Conclusions-Deconvolution and application of PWI thresholds provide more conservative estimates of tissue at risk and decrease the frequency of mismatch accordingly. The precise definition may not be critical; however, because reperfusion alters tissue fate irrespective of mismatch.
Keyword Clinical Neurology
Peripheral Vascular Disease
Magnetic Resonance Imaging, Diffusion-weighted
Magnetic Resonance Imaging, Perfusion-weighted
Acute Ischemic-stroke
Tissue-plasminogen Activator
Weighted Mri
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Medicine Publications
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Created: Mon, 13 Aug 2007, 15:14:16 EST