Department of Biomedical Engineering, Northwestern University, Evanston, Illinois.
Department of Radiology, University of Chicago, Chicago, Illinois.
Magn Reson Med. 2019 Jun;81(6):3567-3577. doi: 10.1002/mrm.27669. Epub 2019 Feb 8.
This work sought to compare a quantitative T bookend dynamic susceptibility contrast MRI based perfusion protocol for absolute cerebral blood flow (qCBF) against CBF measured by the stable-isotope neutron capture microsphere method, a recognized reference standard for measuring tissue blood flow, at normocapnia, hypercapnia, and in acute stroke.
CBF was measured in anesthetized female canines by MRI and microspheres over 2 consecutive days for each case. On day 1, 5 canines were measured before and during a physiological challenge induced by carbogen inhalation; on day 2, 4 canines were measured following permanent occlusion of the middle cerebral artery. CBF and cerebrovascular reactivity measured by MRI and microsphere deposition were compared.
MRI correlated strongly with microspheres at the hemispheric level for CBF during normo- and hypercapnic states (r = 0.96), for individual cerebrovascular reactivity (r = 0.84), and for postocclusion CBF (r = 0.82). Correction for the delay and dispersion of the contrast bolus resulted in a significant improvement in the correlation between MRI and microsphere deposition in the ischemic state (r = 0.96). In all comparisons, moderate correlations were found at the regional level.
In an experimental canine model with and without permanent occlusion of the middle cerebral artery, MRI-based qCBF yielded moderate to strong correlations for absolute quantitative CBF and cerebrovascular reactivity measurements during normocapnia and hypercapnia. Correction for delay and dispersion greatly improved the quantitation during occlusion of the middle cerebral artery, underscoring the importance for this correction under focal ischemic condition.
本研究旨在比较一种基于定量 T 型双端动态磁敏感对比磁共振成像（DSC-MRI）的灌注方案，以评估绝对脑血流（qCBF），并与稳定同位素中子捕获微球法（一种公认的测量组织血流的参考标准）进行比较，以评估在正常碳酸血症、高碳酸血症和急性卒中时的脑血流。
在麻醉雌性犬中，通过 MRI 和微球在连续两天内测量 CBF。第 1 天，5 只犬在吸入碳氧混合气诱导的生理挑战前和期间进行测量；第 2 天，4 只犬在大脑中动脉永久性闭塞后进行测量。比较 MRI 和微球沉积测量的 CBF 和脑血管反应性。
MRI 在半球水平与微球在正常和高碳酸血症状态下的 CBF （r = 0.96）、个体脑血管反应性（r = 0.84）和闭塞后 CBF （r = 0.82）之间具有很强的相关性。对比剂团块的延迟和弥散校正显著改善了缺血状态下 MRI 和微球沉积之间的相关性（r = 0.96）。在所有比较中，在区域水平上发现了中度相关性。
在伴有和不伴有大脑中动脉永久性闭塞的实验性犬模型中，基于 MRI 的 qCBF 在正常碳酸血症和高碳酸血症期间对绝对定量 CBF 和脑血管反应性测量具有中度至强相关性。延迟和弥散校正大大改善了大脑中动脉闭塞时的定量，强调了在局灶性缺血情况下进行这种校正的重要性。
