Yun Tae Jin, Sohn Chul-Ho, Han Moon Hee, Kang Hyun-Seung, Kim Jeong Eun, Yoon Byung-Woo, Paeng Jin Chul, Choi Seung Hong, Kim Ji-hoon, Song In Chan, Chang Kee-Hyun
From the *Institute of Radiation Medicine, Seoul National University Medical Research Center; Departments of †Radiology, ‡Neurosurgery, §Clinical Research Center for Stroke, Clinical Research Institute, Departments of ∥Neurology, ¶Nuclear Medicine, Seoul National University Hospital, Seoul; and #Department of Radiology, Soonchunhyang University Bucheon Hospital, Bucheon, Republic of Korea.
Invest Radiol. 2013 Nov;48(11):795-802. doi: 10.1097/RLI.0b013e3182981137.
Because arterial spin labeling (ASL) is completely noninvasive and provides absolute cerebral blood flow (CBF) information within a brief period, the technique has been increasingly used for patients with acute or chronic cerebrovascular disease. However, the effect of delayed transit time on ASL can generate errors in the quantitative estimation of CBF using ASL. Furthermore, in the clinical setting, in which transit time is uncertain, the variability of the transit time in patients reduces the validity of CBF on ASL images. Therefore, we evaluated the effect of delayed transit time on ASL images compared with dynamic susceptibility contrast (DSC) perfusion magnetic resonance (MR) in patients with moyamoya disease.
Arterial spin labeling and DSC perfusion MR images were acquired in 54 patients with moyamoya disease. Vascular territory and anatomical structure-based regions of interest (ROIs) were applied to the CBF and time-to-peak (TTP) maps from DSC and a CBF map using ASL. The change of the correlation coefficient (r) between normalized CBFs (nCBFs) from DSC and ASL was evaluated with categorization by the TTP. In addition, the dependence of the difference between the nCBF values from DSC and ASL on the TTP obtained using DSC was also analyzed.
The nCBF values from DSC and ASL were strongly correlated (r = 0.877 and r = 0.867 for the internal carotid artery (ICA) and middle cerebral artery territory-based ROIs, respectively; P < 0.0002 for both; r = 0.783 for the anatomical structure-based ROIs; P < 0.0084). However, correlations between nCBFs from DSC and ASL tended to be weaker when the TTP increased, with recovery when the TTP was extremely delayed (>25 seconds). The TTP delay had a positive effect on the difference between the nCBF values from the DSC and ASL for the ICA territory-based and anatomical structure-based ROIs (standardized coefficients, 0.224 for the ICA territory-based ROIs; P = 0.0410; 0.189 for the anatomical structure-based ROIs; P < 0.0084).
Our results demonstrate that the correlation between the CBF values from the ASL and DSC tends to be weaker when the transit time is more delayed, with the restoration of the strength of the correlation when the TTP is extremely delayed (>25 seconds). Understanding the effect of delayed transit time on the CBF from ASL perfusion MR in a clinical setting would facilitate the proper interpretation of ASL images.
由于动脉自旋标记（ASL）完全无创且能在短时间内提供绝对脑血流量（CBF）信息，该技术已越来越多地用于急慢性脑血管疾病患者。然而，延迟通过时间对ASL的影响会在使用ASL定量估算CBF时产生误差。此外，在临床环境中，通过时间不确定，患者通过时间的变异性会降低ASL图像上CBF的有效性。因此，我们比较了烟雾病患者中延迟通过时间对ASL图像与动态磁敏感对比（DSC）灌注磁共振（MR）的影响。
对54例烟雾病患者进行了动脉自旋标记和DSC灌注MR图像采集。基于血管区域和解剖结构的感兴趣区（ROI）应用于DSC的CBF和达峰时间（TTP）图以及使用ASL的CBF图。通过TTP分类评估DSC和ASL的标准化CBF（nCBF）之间相关系数（r）的变化。此外，还分析了DSC和ASL的nCBF值差异对使用DSC获得的TTP的依赖性。
DSC和ASL的nCBF值高度相关（分别以颈内动脉（ICA）和大脑中动脉区域为基础的ROI，r = 0.877和r = 0.867；两者P < 0.0002；以解剖结构为基础的ROI，r = 0.783；P < 0.0084）。然而，当TTP增加时，DSC和ASL的nCBF之间的相关性趋于减弱，当TTP极度延迟（>25秒）时相关性恢复。TTP延迟对基于ICA区域和基于解剖结构的ROI的DSC和ASL的nCBF值差异有正向影响（标准化系数，基于ICA区域的ROI为0.224；P = 0.0410；基于解剖结构的ROI为0.189；P < 0.0084）。
我们的结果表明，当通过时间延迟更多时，ASL和DSC的CBF值之间的相关性趋于减弱，当TTP极度延迟（>25秒）时相关性强度恢复。了解临床环境中延迟通过时间对ASL灌注MR的CBF的影响将有助于正确解读ASL图像。
