TY - JOUR
T1 - Effects of Reperfusion on ADC and CBF Pixel-by-Pixel Dynamics in Stroke
T2 - Characterizing Tissue Fates using Quantitative Diffusion and Perfusion Imaging
AU - Shen, Qiang
AU - Fisher, Marc
AU - Sotak, Christopher H.
AU - Duong, Timothy Q.
PY - 2004/3
Y1 - 2004/3
N2 - The effects of reperfusion on the spatiotemporal dynamics of transient (60 minutes) focal ischemic brain injury in rats were evaluated on a pixel-by-pixel basis using quantitative cerebral blood flow (CBF) and apparent diffusion coefficient (ADC) measurements every 30 minutes for 3 hours and compared to post-mortem histology at 24 hours. Four biologically relevant clusters were classified based on ADC (0.53 ± 0.02 × 10-3mm 2/s, SD) and CBF (0.30 ± 0.09ml/g/min) viability thresholds, namely: (1) the "normal" cluster with ADC and CBF > thresholds; (2) the "mismatch" cluster with ADC > threshold but CBF < threshold; (3) the "core" cluster with ADC and CBF < thresholds; and (4) "non-nourishing reperfusion zone" where ADC < threshold but CBF > threshold. The spatio-temporal progression of tissue volumes, ADC and CBF of each cluster were evaluated. Pixels of each cluster on the CBF-ADC space were mapped onto the image space. Following reperfusion, 28% of the "core" pixels and 90% of the "mismatch" (defined at 60 minutes) pixels were salvaged at 180 minutes, which correlated with histology. The ADC and CBF of subsequently salvaged tissues were significantly higher than those became infarcted. Salvaging "core" pixels indicated that reduced ADC was not synonymous with irreversible injury; duration of exposure and severity of reduced ADC and CBF were likely critical. Projection profiles showed a bimodal ADC, but uni-modal CBF, distributions. The ADC bimodal minima, obtained without histological correlation, were similar to the histology-derived ADC and CBF viability thresholds, and could have potential clinical applications. This study demonstrated a simple but powerful approach to evaluate, on a pixel-by-pixel basis, the spatio-temporal evolution of ischemic brain injury, and a potential for statistical prediction of tissue fate.
AB - The effects of reperfusion on the spatiotemporal dynamics of transient (60 minutes) focal ischemic brain injury in rats were evaluated on a pixel-by-pixel basis using quantitative cerebral blood flow (CBF) and apparent diffusion coefficient (ADC) measurements every 30 minutes for 3 hours and compared to post-mortem histology at 24 hours. Four biologically relevant clusters were classified based on ADC (0.53 ± 0.02 × 10-3mm 2/s, SD) and CBF (0.30 ± 0.09ml/g/min) viability thresholds, namely: (1) the "normal" cluster with ADC and CBF > thresholds; (2) the "mismatch" cluster with ADC > threshold but CBF < threshold; (3) the "core" cluster with ADC and CBF < thresholds; and (4) "non-nourishing reperfusion zone" where ADC < threshold but CBF > threshold. The spatio-temporal progression of tissue volumes, ADC and CBF of each cluster were evaluated. Pixels of each cluster on the CBF-ADC space were mapped onto the image space. Following reperfusion, 28% of the "core" pixels and 90% of the "mismatch" (defined at 60 minutes) pixels were salvaged at 180 minutes, which correlated with histology. The ADC and CBF of subsequently salvaged tissues were significantly higher than those became infarcted. Salvaging "core" pixels indicated that reduced ADC was not synonymous with irreversible injury; duration of exposure and severity of reduced ADC and CBF were likely critical. Projection profiles showed a bimodal ADC, but uni-modal CBF, distributions. The ADC bimodal minima, obtained without histological correlation, were similar to the histology-derived ADC and CBF viability thresholds, and could have potential clinical applications. This study demonstrated a simple but powerful approach to evaluate, on a pixel-by-pixel basis, the spatio-temporal evolution of ischemic brain injury, and a potential for statistical prediction of tissue fate.
KW - DWI
KW - Hyperemia
KW - Oligemia
KW - PWI
KW - Penumbra
KW - Perfusion-diffusion mismatch
KW - Stroke
KW - Viability thresholds
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U2 - 10.1097/01.WCB.0000110048.43905.E5
DO - 10.1097/01.WCB.0000110048.43905.E5
M3 - Article
C2 - 15091108
AN - SCOPUS:1542376867
SN - 0271-678X
VL - 24
SP - 280
EP - 290
JO - Journal of Cerebral Blood Flow and Metabolism
JF - Journal of Cerebral Blood Flow and Metabolism
IS - 3
ER -