Carr John P, Buckley David L, Tessier Jean, Parker Geoff J M
Imaging Science and Biomedical Engineering, University of Manchester, Manchester, UK.
Magn Reson Med. 2007 Aug;58(2):281-9. doi: 10.1002/mrm.21317.
We examine the use of arterial spin labeling (ASL) in normal brains of rats and humans to measure perfusion (F) and capillary permeability surface area product (PS) using a previously described two-compartment model. We investigate the experimental limits on F and PS quantification using simulations and experimental verification in rat brain at 9.4T. A sensitivity analysis on the two-compartment model is presented to estimate optimal experimental inversion times (TIs) for F and PS quantification and indicate how sensitive the model would be to changes in F and PS. We present the expected error on flow-sensitive alternating inversion recovery (FAIR)-based F and PS measurements and quantify the precision with which these parameters could be estimated at various signal-to-noise ratios (SNRs). Perfusion was measured in four rat brains using FAIR ASL, and we conclude that perfusion could be quantified with an acceptable level of precision using this technique. However, we found that to measure PS with even a 100% coefficient of variation (CV) would require an SNR increase of approximately 2 orders of magnitude over our acquired data. We conclude that with current MR capabilities and with the experimental approach used in this study, acceptable levels of precision in the measurement of PS are not possible.
我们使用先前描述的双室模型，研究动脉自旋标记（ASL）在大鼠和人类正常大脑中测量灌注（F）和毛细血管通透性表面积乘积（PS）的应用。我们通过模拟和在9.4T大鼠脑上的实验验证，研究F和PS定量的实验限制。对双室模型进行敏感性分析，以估计F和PS定量的最佳实验反转时间（TIs），并指出该模型对F和PS变化的敏感程度。我们给出基于流动敏感交替反转恢复（FAIR）的F和PS测量的预期误差，并量化在各种信噪比（SNR）下估计这些参数的精度。使用FAIR ASL测量了四只大鼠脑的灌注，我们得出结论，使用该技术可以以可接受的精度对灌注进行量化。然而，我们发现，即使要以100%的变异系数（CV）测量PS，也需要比我们采集的数据的SNR提高大约2个数量级。我们得出结论，就目前的磁共振能力以及本研究中使用的实验方法而言，不可能实现对PS测量的可接受精度水平。
