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Penumbra detection using PWI/DWI mismatch MRI in a rat stroke model with and without comorbidity: comparison of methods

Author(s): E. Reid, D. Graham, M. R. Lopez-Gonzalez, W. M. Holmes, I. M. Macrae, C. McCabe

Perfusion-diffusion (perfusion-weighted imaging (PWI)/diffusion-weighted imaging (DWI)) mismatch is used to identify penumbra in acute stroke. However, limitations in penumbra detection with mismatch are recognized, with a lack of consensus on thresholds, quantification and validation of mismatch. We determined perfusion and diffusion thresholds from final infarct in the clinically relevant spontaneously hypertensive stroke-prone (SHRSP) rat and its normotensive control strain, Wistar-Kyoto (WKY) and compared three methods for penumbra calculation. After permanent middle cerebral artery occlusion (MCAO) (WKY n = 12, SHRSP n = 15), diffusion-weighted (DWI) and perfusion-weighted (PWI) images were obtained for 4 hours post stroke and final infarct determined at 24 hours on T-2 scans. The PWI/DWI mismatch was calculated from volumetric assessment (perfusion deficit volume minus apparent diffusion coefficient (ADC)-defined lesion volume) or spatial assessment of mismatch area on each coronal slice. The ADC-derived lesion growth provided the third, retrospective measure of penumbra. At 1 hour after MCAO, volumetric mismatch detected smaller volumes of penumbra in both strains (SHRSP: 31 +/- 50 mm(3), WKY: 22 +/- 59 mm(3), mean +/- s.d.) compared with spatial assessment (SHRSP: 36 +/- 15 mm(3), WKY: 43 +/- 43 mm(3)) and ADC lesion expansion (SHRSP: 41 +/- 45 mm(3), WKY: 65 +/- 41 mm(3)), although these differences were not statistically significant. Spatial assessment appears most informative, using both diffusion and perfusion data, eliminating the influence of negative mismatch and allowing the anatomical location of penumbra to be assessed at given time points after stroke. Journal of Cerebral Blood Flow & Metabolism (2012) 32, 1765-1777; doi:10.1038/jcbfm.2012.69; published online 6 June 2012

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ISBN: 0271-678X
Publication Year: 2012
Periodical: Journal of Cerebral Blood Flow and Metabolism
Periodical Number: 9
Volume: 32
Pages: 1765-1777
Author Address: McCabe, C Univ Glasgow, Wellcome Surg Inst, Coll Med Vet & Life Sci, Inst Neurosci & Psychol,Glasgow Expt MRI Ctr,MLVS, Garscube Estate, Glasgow G61 1QH, Lanark, Scotland Univ Glasgow, Wellcome Surg Inst, Coll Med Vet & Life Sci, Inst Neurosci & Psychol,Glasgow Expt MRI Ctr,MLVS, Glasgow G61 1QH, Lanark, Scotland Univ Glasgow, Inst Cardiovasc & Med Sci, Coll MVLS, BHF Glasgow Cardiovasc Res Ctr, Glasgow G61 1QH, Lanark, Scotland Univ Glasgow, SINAPSE Collaborat, Dept Clin Phys, Coll MVLS, Glasgow G61 1QH, Lanark, Scotland