Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, USA.
Magn Reson Med. 2018 Feb;79(2):815-825. doi: 10.1002/mrm.26742. Epub 2017 May 9.
To evaluate the feasibility of quantitative single breath-hold renal arterial spin labeling (ASL) imaging at 7T.
A single-shot fast spin echo FAIR (flow-sensitive alternating inversion recovery) method was used to perform two studies. First, a multi-delay perfusion study was performed to estimate the spin labeling temporal bolus width achievable with a local transceiver array coil at 7T. Second, with a conservatively defined bolus width, a quantitative perfusion study was performed using the single subtraction approach. To address issues of B1+ inhomogeneity/efficiency and excessive short-term specific absorption rates, various strategies were used, such as dynamic radiofrequency shimming and optimization.
A conservative temporal bolus width of 600 ms determined from the multi-delay study was applied for single-subtraction imaging to measure the renal blood flow in the cortex and medulla: 303 ± 31.8 and 91.3 ± 15.2 (mL/100 g/min), respectively. The estimated spatial and temporal signal-to-noise ratios of renal perfusion measurements were 3.8 ± 0.7 and 2.4 ± 0.6 for the cortex, and 2.2 ± 0.6 and 1.4 ± 0.2 for the medulla.
With proper management of field strength specific challenges, quantitative renal ASL imaging can be achieved at 7T within a single breath-hold. Magn Reson Med 79:815-825, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
评估在 7T 下进行定量单屏息肾动脉磁共振自旋标记（ASL）成像的可行性。
使用单次快速自旋回波 FAIR（流动敏感交替反转恢复）方法进行了两项研究。首先，进行了多延迟灌注研究，以估计在 7T 下使用局部收发器阵列线圈可实现的自旋标记时间脉冲宽度。其次，使用单减方法，在保守定义的脉冲宽度下进行定量灌注研究。为了解决 B1+不均匀性/效率和短期特定吸收率过高的问题，采用了各种策略，如动态射频调谐和优化。
多延迟研究确定的保守时间脉冲宽度为 600ms，用于单减成像以测量皮质和髓质的肾血流量：分别为 303±31.8 和 91.3±15.2（mL/100g/min）。皮质和髓质肾灌注测量的估计空间和时间信噪比分别为 3.8±0.7 和 2.4±0.6，以及 2.2±0.6 和 1.4±0.2。
通过适当管理场强特定挑战，可以在单次屏息下在 7T 下实现定量肾 ASL 成像。磁共振医学 79：815-825，2018. © 2017 国际磁共振学会。
