科研之友
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摘要
Background 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. Aims 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. Methods Permanent middle cerebral artery occlusion was induced in male Sprague-Dawley rats (n = 6) prior to serial multimodal imaging: T2* oxygen challenge, diffusion weighted and perfusion imaging (cerebral blood flow using arterial spin labeling). Results 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 mm(3) (single T2* oxygen challenge-based threshold); 55 +/- 41 to 37 +/- 12 mm(3) (dual T2* oxygen challenge/cerebral blood flow); 84 +/- 64 to 42 +/- 18 mm(3) (dual cerebral blood flow/apparent diffusion coefficient), as ischemic core grew: 155 +/- 37 to 211 +/- 36 mm(3) (single apparent diffusion coefficient threshold); 178 +/- 56 to 205 +/- 33 mm(3) (dual T2* oxygen challenge/cerebral blood flow); 139 +/- 30 to 168 +/- 38 mm(3) (dual cerebral blood flow/apparent diffusion coefficient). There was evidence of further lesion growth beyond four-hours (T2-defined edema-corrected infarct, 231 +/- 19 mm(3)). Conclusions 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.
- 出版日期2015-1
