UdS, Université de Strasbourg, Strasbourg, France; INSERM U666-Physiopathologie et Psychopathologie Cognitive de la Schizophrénie, Strasbourg, France.
J Magn Reson Imaging. 2011 Oct;34(4):785-90. doi: 10.1002/jmri.22678. Epub 2011 Jul 18.
To take into account the echo time (TE) influence on arterial spin labeling (ASL) signal when converting it in regional cerebral blood flow (rCBF). Gray matter ASL signal decrease with increasing TE as a consequence of the difference in the apparent transverse relaxation rates between labeled water in capillaries and nonlabeled water in the tissue (δR 2*). We aimed to measure ASL/rCBF changes in different parts of the brain and correct them.
Fifteen participants underwent ASL measurements at TEs of 9.7-30 ms. Decreases in ASL values were localized by statistical parametric mapping. The corrections assessed were a subject-per-subject adjustment, an average δR 2* value adjustment, and a two-compartment model adjustment.
rCBF decreases associated with increasing TEs were found for gray matter and were corrected using an average δR 2* value of 20 s(-1) . Conversely, for white matter, rCBF values increased with increasing TEs (δR 2* = -23 s(-1)).
Our correction was as good as using a two-compartment model. However, it must be done separately for the gray and white matter rCBF values because the capillary R 2* values are, respectively, larger and smaller than those of surrounding tissues.
在将动脉自旋标记（ASL）信号转换为局部脑血流（rCBF）时，考虑回波时间（TE）的影响。由于毛细血管中标记水和组织中非标记水之间表观横向弛豫率的差异（δR2*），灰质 ASL 信号随 TE 的增加而降低。我们旨在测量大脑不同部位的 ASL/rCBF 变化并进行校正。
15 名参与者在 9.7-30 ms 的 TE 下进行 ASL 测量。通过统计参数映射定位 ASL 值的降低。评估的校正方法包括个体内调整、平均 δR2*值调整和两室模型调整。
发现灰质的 rCBF 随 TE 的增加而降低，并使用平均 δR2值为 20 s(-1)进行校正。相反，对于白质，rCBF 值随 TE 的增加而增加（δR2 = -23 s(-1)）。
我们的校正与使用两室模型一样好。然而，由于毛细血管 R2值分别大于和小于周围组织的 R2值，因此必须分别对灰质和白质 rCBF 值进行校正。
