Figueiredo Patrícia M, Clare Stuart, Jezzard Peter
Centre for Functional Magnetic Resonance Imaging of the Brain (FMRIB), Department of Clinical Neurology, University of Oxford, John Radcliffe Hospital, Oxford, UK.
J Magn Reson Imaging. 2005 Jun;21(6):676-82. doi: 10.1002/jmri.20329.
To study arterial spin labeling (ASL) MRI techniques and to investigate various problematic issues that still hinder the accurate and robust quantitative analysis of ASL data.
A pulsed-ASL (PASL) sequence was implemented on a 3-T imaging system and a protocol was developed for the measurement of perfusion based on fitting to a standard kinetic model. Both numerical simulations and multi-inversion time MRI data were analyzed. The effect of fitting a kinetic curve to a large region of interest (ROI) with a distribution of arterial transit times was compared to a pixel-by-pixel (PBP) method.
It was found that a significant underestimation of perfusion of approximately 17+/-6% (P<0.001) occurs in gray matter, when comparing an ROI with a PBP analysis over a group of 12 healthy subjects.
Analysis of ASL data based on a large ROI may suffer from inaccuracies arising from a distribution of transit times, implying that averaging of ASL kinetic data over such regions should therefore be avoided. When possible, a PBP fit should be performed.
研究动脉自旋标记（ASL）MRI技术，并探讨仍阻碍对ASL数据进行准确且可靠定量分析的各种问题。
在3-T成像系统上实施脉冲ASL（PASL）序列，并制定了基于拟合标准动力学模型进行灌注测量的方案。对数值模拟和多反转时间MRI数据进行了分析。将对具有动脉通过时间分布的大感兴趣区域（ROI）拟合动力学曲线的效果与逐像素（PBP）方法进行了比较。
在一组12名健康受试者中，当将ROI与PBP分析进行比较时，发现灰质灌注明显低估约17±6%（P<0.001）。
基于大ROI对ASL数据进行分析可能会因通过时间分布而产生不准确结果，这意味着应避免在此类区域对ASL动力学数据进行平均。可能的话，应进行PBP拟合。
