From the Faculty of Medicine of the University of Geneva (M.v.d.T., P.G., N.G., D.v.d.V., S.H.), Geneva, Switzerland.
Institute of Bioengineering (M.v.d.T., N.G., D.v.d.V.), School of Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
AJNR Am J Neuroradiol. 2018 Aug;39(8):1432-1438. doi: 10.3174/ajnr.A5717. Epub 2018 Jul 5.
Multidelay arterial spin-labeling is a promising emerging method in clinical practice. The effect of imaging parameters in multidelay arterial spin-labeling on estimated cerebral blood flow measurements remains unknown. We directly compared 3-delay versus 7-delay sequences, assessing the difference in the estimated transit time and blood flow.
This study included 87 cognitively healthy controls (78.7 ± 3.8 years of age; 49 women). We assessed delay and transit time-uncorrected and transit time-corrected CBF maps. Data analysis included voxelwise permutation-based between-sequence comparisons of 3-delay versus 7-delay, within-sequence comparison of transit time-uncorrected versus transit time-corrected maps, and average CBF calculations in regions that have been shown to differ.
The 7-delay sequence estimated a higher CBF value than the 3-delay for the transit time-uncorrected and transit time-corrected maps in regions corresponding to the watershed areas (transit time-uncorrected = 27.62 ± 12.23 versus 24.58 ± 11.70 mL/min/100 g, Cohen's = 0.25; transit time-corrected = 33.48 ± 14.92 versus 30.16 ± 14.32 mL/min/100 g, Cohen's = 0.23). In the peripheral regions of the brain, the estimated delay was found to be longer for the 3-delay sequence (1.52408 ± 0.25236 seconds versus 1.47755 ± 0.24242 seconds, Cohen's = 0.19), while the inverse was found in the center of the brain (1.39388 ± 0.22056 seconds versus 1.42565 ± 0.21872 seconds, Cohen's = 0.14). Moreover, 7-delay had lower hemispheric asymmetry.
The results of this study support the necessity of standardizing acquisition parameters in multidelay arterial spin-labeling and identifying basic parameters as a confounding factor in CBF quantification studies. Our findings conclude that multidelay arterial spin-labeling sequences with a high number of delays estimate higher CBF values than those with a lower number of delays.
多延迟动脉自旋标记是临床实践中一种很有前途的新兴方法。多延迟动脉自旋标记的成像参数对估计脑血流测量的影响尚不清楚。我们直接比较了 3 延迟与 7 延迟序列，评估了估计的渡越时间和血流之间的差异。
本研究纳入了 87 名认知健康的对照者（78.7±3.8 岁；49 名女性）。我们评估了延迟和未校正和校正渡越时间的 CBF 图。数据分析包括基于置换的序列间 3 延迟与 7 延迟比较、序列内未校正与校正渡越时间图比较，以及在已有差异的区域进行平均 CBF 计算。
7 延迟序列在对应分水岭区域的未校正和校正渡越时间的 CBF 值均高于 3 延迟序列（未校正渡越时间=27.62±12.23 与 24.58±11.70 mL/min/100 g，Cohen's =0.25；校正渡越时间=33.48±14.92 与 30.16±14.32 mL/min/100 g，Cohen's =0.23）。在大脑的外周区域，3 延迟序列的估计延迟时间更长（1.52408±0.25236 秒与 1.47755±0.24242 秒，Cohen's =0.19），而在大脑中心则相反（1.39388±0.22056 秒与 1.42565±0.21872 秒，Cohen's =0.14）。此外，7 延迟的半球间不对称性更低。
本研究结果支持在多延迟动脉自旋标记中标准化采集参数的必要性，并确定基本参数是 CBF 定量研究中的混杂因素。我们的研究结果表明，具有较多延迟的多延迟动脉自旋标记序列估计的 CBF 值高于具有较少延迟的序列。
