Department of Radiology, University of Michigan, Ann Arbor, Michigan.
School of Kinesiology, University of Michigan, Ann Arbor, Michigan.
NMR Biomed. 2021 Jun;34(6):e4500. doi: 10.1002/nbm.4500. Epub 2021 Mar 6.
This work aimed to develop an efficient R dispersion imaging method for clinical studies of human knee cartilage at 3 T. Eight constant magnetizations (M ) were prepared by tailoring both the duration and amplitude (ω ) of a fully refocused spin-lock preparation pulse. The limited M dynamic range was expanded by the measure, equivalent to that with ω = ∞, from the magic angle location in the deep femoral cartilage. The developed protocol with M = 60% was demonstrated on one subject's bilateral and two subjects' unilateral asymptomatic knees. The repeatability of the proposed protocol was estimated by two repeated scans with a three-month gap for the last two subjects. The synthetic R and R derived from R dispersions were compared with the published references using state-of-the-art R and R mapping (MAPSS). The proposed protocol demonstrated good (<5%) repeatability quantified by the intra- and intersubject coefficients of variation in the femoral and tibial cartilage. The synthetic R (1/s) and the references were comparable in the femoral (23.0 ± 5.3 versus 24.1 ± 3.8, P = 0.67) and the tibial (29.1 ± 8.8 versus 27.1 ± 5.1, P = 0.62), but not the patellar (16.5 ± 4.9 versus 22.7 ± 1.6, P < 0.01) cartilage. The same trends were also observed for the current and the previous R . In conclusion, the developed R dispersion imaging scheme has been revealed to be not only efficient but also robust for clinical studies of human knee cartilage at 3 T.
本研究旨在开发一种高效的 R 弥散成像方法，用于 3T 下的人类膝关节软骨临床研究。通过定制完全重聚焦自旋锁定准备脉冲的持续时间和幅度（ω），制备了 8 个恒定磁化率（M）。通过测量从深股骨软骨的魔角位置扩展了有限的 M 动态范围，相当于 ω = ∞时的范围。该方法在 1 名受试者的双侧和 2 名受试者的单侧无症状膝关节上进行了验证。对于最后两名受试者，在相隔三个月的两次重复扫描中评估了该方案的重复性。使用最新的 R 和 R 映射（MAPSS）将合成 R 和 R 从 R 弥散中得出的 R 与已发表的参考文献进行了比较。所提出的方案在股骨和胫骨软骨中，通过受试者内和受试者间变异系数来评估重复性良好（<5%）。在股骨（23.0 ± 5.3 与 24.1 ± 3.8，P = 0.67）和胫骨（29.1 ± 8.8 与 27.1 ± 5.1，P = 0.62）软骨中，合成 R（1/s）和参考文献相当，但在髌骨（16.5 ± 4.9 与 22.7 ± 1.6，P < 0.01）软骨中则不然。当前和先前的 R 也观察到了相同的趋势。总之，所开发的 R 弥散成像方案不仅高效，而且在 3T 下的人类膝关节软骨临床研究中也具有稳健性。
