Predict Tissue Outcome Research Articles

A Novel Method to Derive Separate Gray and White Matter Cerebral Blood Flow Measures from MR Imaging of Acute Ischemic Stroke Patients

Perfusion-weighted imaging (PWI) measures can predict tissue outcome in acute ischemic stroke. Accuracy might be improved if differential tissue susceptibility to ischemia is considered. We present a novel voxel-by-voxel analysis to characterize cerebral blood flow (CBF) separately in gray (GM) and white matter (WM). Ten patients were scanned with inversion-recovery spin-echo EPI (IRSEPI), diffusion-weighted imaging (DWI), PWI<6 h from onset and fluid attenuated inversion-recovery (FLAIR) at 30 days. Image processing included coregistration to PWI, automatic segmentation of IRSEPI into GM, WM and CSF and semiautomatic segmentation of DWI/FLAIR to derive the acute and 30-day lesions. Five tissue compartments were defined: (1) 'Core' (abnormal acutely and at 30 days), (2) 'Growth' (or 'infarcted penumbra', abnormal only at 30 days), (3) 'Reversed' (abnormal acutely but normal at 30 days), (4) 'MTT-Delayed ' (tissue with delayed mean transit time but not part of the acute or 30-day lesion), and (5) 'Normal' brain. Cerebral blood flow in GM and WM of each compartment was obtained from quantitative maps. Gray matter and WM mean CBF in the growth region differed by 5.5 mL/100 g min (P=0.015). Mean CBF also differed significantly within normal and MTT-Delayed compartments. The difference in the reversed region approached statistical significance. In core, GM and WM CBF did not differ. The results suggest separate ischemic thresholds for GM and WM in stroke penumbra.

Tissue Viability Thresholds in Acute Stroke

Tissue Viability Thresholds in Acute Stroke

CT Perfusion Imaging versus MR Diffusion Weighted Imaging: Prediction of Final Infarct Size in Hyperacute Stroke

10 Background: Both CT perfusion imaging (CTP) and MR diffusion weighted imaging (DWI) have been applied clinically to predict tissue outcome in patients with hyperacute stroke, however these techniques have not been directly compared in the same patient population. In CTP, whole brain CT scanning is performed during the steady state administration of a contrast bolus, creating both perfused blood volume weighted and CT angiographic images. Purpose: To determine the value of CTP imaging, compared to DWI, in predicting final infarct size in hyperacute stroke patients. Materials and Methods: CTP followed by DWI imaging was performed in 23 consecutive patients presenting within 12 hours of stroke onset. Mean time from stroke onset to imaging was 4.6 hours for CTP, 5.4 hours for DWI, and 6.5 days for conventional nonenhanced CT and/or MR follow-up. No patients had secondary events between initial and follow-up scanning. Initial and follow-up ischemic volumes were computed from the CTP, DWI, and follow-up scans using image segmentation software, and compared using linear and multiple regression. Results: CTP and DWI volumes were independent predictors of final infarct size (p=0.02). The regression line for CTP volume vs. final infarct size had slope 1.02 and r 2 = 0.88 (p&lt;0.0001). The regression line for DWI volume vs. final infarct size had slope 1.41 and r 2 = 0.92 (p&lt;0.0001). Overall sensitivity and specificity for parenchymal stroke detection were 83% and 100% for CTP, and 100% and 100% for DWI, respectively. Conclusion: Although DWI is more sensitive than CTP for parenchymal stroke detection, both DWI and CTP are highly accurate predictors of final infarct volume. DWI tends to underestimate final infarct size, whereas CTP more closely approximates final infarct size.

On the theory of the indicator-dilution method for measurement of blood flow and volume.

On the theory of the indicator-dilution method for measurement of blood flow and volume.