C. A. Robertson, C. McCabe, L. Gallagher, R. Lopez-Gonzalez Mdel, W. M. Holmes, B. Condon, K. W. Muir, C. Santosh, I. M. Macrae


1559-7016 (Electronic) 0271-678X (Linking)

Publication year



J Cereb Blood Flow Metab

Periodical Number






Author Address

Glasgow Experimental MRI Centre, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.

Full version

Magnetic resonance imaging (MRI) with oxygen challenge (T(2)(*) OC) uses oxygen as a metabolic biotracer to define penumbral tissue based on CMRO(2) and oxygen extraction fraction. Penumbra displays a greater T(2)(*) signal change during OC than surrounding tissue. Since timely restoration of cerebral blood flow (CBF) should salvage penumbra, T(2)(*) OC was tested by examining the consequences of reperfusion on T(2)(*) OC-defined penumbra. Transient ischemia (109 +/- 20 minutes) was induced in male Sprague-Dawley rats (n=8). Penumbra was identified on T(2)(*)-weighted MRI during OC. Ischemia and ischemic injury were identified on CBF and apparent diffusion coefficient maps, respectively. Reperfusion was induced and scans repeated. T(2) for final infarct and T(2)(*) OC were run on day 7. T(2)(*) signal increase to OC was 3.4% in contralateral cortex and caudate nucleus and was unaffected by reperfusion. In OC-defined penumbra, T(2)(*) signal increased by 8.4% +/- 4.1% during ischemia and returned to 3.25% +/- 0.8% following reperfusion. Ischemic core T(2)(*) signal increase was 0.39% +/- 0.47% during ischemia and 0.84% +/- 1.8% on reperfusion. Penumbral CBF increased from 41.94 +/- 13 to 116.5 +/- 25 mL per 100 g per minute on reperfusion. On day 7, OC-defined penumbra gave a normal OC response and was located outside the infarct. T(2)(*) OC-defined penumbra recovered when CBF was restored, providing further validation of the utility of T(2)(*) OC for acute stroke management.