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From the Department of Radiology, Medical Physics (MML, TJC), Department of Interventional Radiology (NS, GAC), Department of Surgery and Large Animal Studies (MAN), and the Department of Statistics (MG), University of Chicago, Chicago, IL, USA; Department of Anesthesiology (SPR), University of Illinois, Chicago, IL, USA; Department of Radiology, Biomedical Engineering and Imaging Institute (Current affiliation MML), Icahn School of Medicine at Mount Sinai, New York, NY, USA; Mount Carmel Health Systems (Current affiliation GAC), Columbus, OH, USA.
Published: August 2024
AI Article Synopsis
Article Abstract
Background And Purpose: In ischemic stroke, leptomeningeal collaterals can provide delayed and dispersed compensatory blood flow to tissue-at-risk despite an occlusion and can impact treatment response and infarct growth. The purpose of this work is to test the hypothesis that inclusion of this delayed and dispersed flow with an appropriately calculated Local Arterial Input Function (Local-AIF) is needed to quantify the degree of collateral blood supply in tissue distal to an occlusion.
Materials And Methods: Seven experiments were conducted in a pre-clinical middle cerebral artery occlusion model. Dynamic susceptibility contrast MRI was imaged and post-processed to yield quantitative cerebral blood flow (qCBF) maps with both a traditionally chosen single arterial input function applied globally to the whole brain (i.e. "Global-AIF") and a delay and dispersion corrected AIF (i.e. "Local-AIF") that is sensitive to retrograde flow. Leptomeningeal collateral arterial recruitment was quantified with a pial collateral score from x-ray angiograms, and infarct growth calculated from serially acquired diffusion weighted MRI scans.
Results: The degree of collateralization at x-ray correlated more strongly with qCBF using the Local-AIF in the ischemic penumbra (R=0.81) than traditionally chosen Global-AIF (R=0.05). qCBF using a Local-AIF was negatively correlated (less infarct progression as perfusion increased) with infarct growth (R = 0.79) more strongly than a Global-AIF (R=0.02).
Conclusions: In acute stroke, qCBF calculated with a Local-AIF is more accurate for assessing tissue status and collateral supply than traditionally chosen Global-AIFs. These findings support use of a Local-AIF that corrects for delayed and dispersed retrograde flow in determining quantitative tissue perfusion with collateral supply in occlusive disease.
