Detection of ischemic penumbra using combined perfusion and T2* oxygen challenge imaging

Robertson, C. A., McCabe, C. , Lopez-Gonzalez, M. R., Deuchar, G. A., Dani, K., Holmes, W. M. , Muir, K. W. , Santosh, C. and Macrae, I. M. (2014) Detection of ischemic penumbra using combined perfusion and T2* oxygen challenge imaging. International Journal of Stroke, 10(1), pp. 42-50. (doi: 10.1111/ijs.12327)

Abstract

<b>Background</b> Acute ischemic stroke is common and disabling, but there remains a paucity of acute treatment options and available treatment (thrombolysis) is underutilized. Advanced brain imaging, designed to identify viable hypoperfused tissue (penumbra), could target treatment to a wider population. Existing magnetic resonance imaging and computed tomography-based technologies are not widely used pending validation in ongoing clinical trials. T2* oxygen challenge magnetic resonance imaging, by providing a more direct readout of tissue viability, has the potential to identify more patients likely to benefit from thrombolysis – irrespective of time from stroke onset – and patients within and beyond the 4•5 h thrombolysis treatment window who are unlikely to benefit and are at an increased risk of hemorrhage.<p></p> <b>Aims</b> This study employs serial multimodal imaging and voxel-based analysis to develop optimal data processing for T2* oxygen challenge penumbra assessment. Tissue in the ischemic hemisphere is compartmentalized into penumbra, ischemic core, or normal using T2* oxygen challenge (single threshold) or T2* oxygen challenge plus cerebral blood flow (dual threshold) data. Penumbra defined by perfusion imaging/apparent diffusion coefficient mismatch (dual threshold) is included for comparison.<p></p> <b>Methods</b> Permanent middle cerebral artery occlusion was induced in male Sprague-Dawley rats (<i>n</i> = 6) prior to serial multimodal imaging: T2* oxygen challenge, diffusion-weighted and perfusion imaging (cerebral blood flow using arterial spin labeling).<p></p> <b>Results</b> Across the different methods evaluated, T2* oxygen challenge combined with perfusion imaging most closely predicted 24 h infarct volume. Penumbra volume declined from one to four-hours post-stroke: mean ± SD, 77 ± 44 to 49 ± 37 mm³ (single T2* oxygen challenge-based threshold); 55 ± 41 to 37 ± 12  mm³ (dual T2* oxygen challenge/cerebral blood flow); 84 ± 64 to 42 ± 18  mm³ (dual cerebral blood flow/apparent diffusion coefficient), as ischemic core grew: 155 ± 37 to 211 ± 36  mm³ (single apparent diffusion coefficient threshold); 178 ± 56 to 205 ± 33  mm³ (dual T2* oxygen challenge/cerebral blood flow); 139 ± 30 to 168 ± 38  mm³ (dual cerebral blood flow/apparent diffusion coefficient). There was evidence of further lesion growth beyond four-hours (T2-defined edema-corrected infarct, 231 ± 19 mm³).<p></p> <b>Conclusions</b> In conclusion, T2* oxygen challenge combined with perfusion imaging has advantages over alternative magnetic resonance imaging techniques for penumbra detection by providing serial assessment of available penumbra based on tissue viability.<p></p>

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Deuchar, Dr Graeme and Macrae, Professor Mhairi and Santosh, Dr Celestine and Holmes, Dr William and Muir, Professor Keith and Lopez Gonzalez, Dr Maria Del and McCabe, Dr Chris and Dani, Dr Krishna
• Authors: Robertson, C. A., McCabe, C., Lopez-Gonzalez, M. R., Deuchar, G. A., Dani, K., Holmes, W. M., Muir, K. W., Santosh, C., and Macrae, I. M.
• College/School: College of Medical Veterinary and Life Sciences > School of Psychology & Neuroscience
• Journal Name: International Journal of Stroke
• Publisher: Wiley
• ISSN: 1747-4930
• ISSN (Online): 1747-4949
• Copyright Holders: Copyright © 2014 The Authors
• First Published: First published in International Journal of Stroke
• Publisher Policy: Reproduced under a Creative Commons License