Perfusion Diffusion imaging for assessment of penumbra

Diffusion and perfusion weighted imaging (DWI & PI) can be used for approximation of the potentially salvageable ischaemic penumbra following stroke.  The acute diffusion weighted lesion shows ischaemic damage (due to cytotoxic oedema) while the perfusion weighted lesion shows the area of hypoperfusion.  Therefore the mismatch represents the region of tissue which is hypoperfused but is not yet showing signs of ischaemic damage.  We have characterised the acute evolution of ischaemic damage during the critical first hours following stroke and investigated the impact of stroke co-morbidities on this evolution (see relevant references).  This technique allows us to characterise the acute evolution of ischaemic damage over time and identify whether therapeutic approaches can impact on the amount and lifespan of mismatch.

Diffusion & perfusion weighted imaging for assessing the ischaemic penumbra following permanent MCAO in the rat.  Quantitative CBF (top row) and ADC (middle row) maps show the perfusion and diffusion deficit on 4 slices throughout the MCA territory at 1 hour following stroke.  Thresholded CBF and ADC maps show the diffusion perfusion mismatch (bottom row: mismatch shown in black).

Relevant references: 

Baskerville T.A, Macrae IM, Holmes WM & McCabe C.  (2016).  The influence of gender on ‘tissue at risk’ in acute stroke: an MRI DWI study in a rat model of focal cerebral ischaemia.  Journal of Cerebral Blood Flow and Metabolism. Feb;36(2):381-6. doi: 10.1177/0271678X15606137. Epub 2015 Sep.

Tarr, D., Graham, D., Roy, L.A., Holmes, W.M.McCabe, C.Macrae, I.M.Muir, K.W., and Dewar, D. (2013) Hyperglycemia accelerates apparent diffusion coefficient-defined lesion growth after focal cerebral ischemia in rats with and without features of metabolic syndrome.Journal of Cerebral Blood Flow and Metabolism, 33 (10). pp. 1556-1563. ISSN 0271-678X (doi:10.1038/jcbfm.2013.107).

Reid, E.Graham, D., Lopez-Gonzalez, M.R., Holmes, W.M.Macrae, I.M., and McCabe, C. (2012) Penumbra detection using PWI/DWI mismatch MRI in a rat stroke model with and without comorbidity: comparison of methods. Journal of Cerebral Blood Flow and Metabolism, 32 (9). pp. 1765-1777. ISSN 0271-678X (doi:10.1038/jcbfm.2012.69).

McCabe, C.Gallagher, L., Gsell, W., Graham, D.Dominiczak, A. F., and Macrae, I. M. (2009) Differences in the evolution of the ischemic penumbra in stroke-prone spontaneously hypertensive and Wistar-Kyoto rats. Stroke, 40 (12). pp. 3864-3868. ISSN 0039-2499(doi:10.1161/STROKEAHA.109.559021)