Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA.
Veterinary Clinical Sciences Department, University of Minnesota, Saint Paul, MN, USA.
Sci Rep. 2020 Mar 24;10(1):5260. doi: 10.1038/s41598-020-62110-y.
Bone perfusion is an essential physiological measure reflecting vasculature status and tissue viability of the skeletal system. Arterial spin labeling (ASL), as a non-invasive and non-contrast enhanced perfusion imaging method, is an attractive approach for human research studies. To evaluate the feasibility of ASL perfusion imaging of knee bone marrow in the distal femoral condyle at a 3 T MRI scanner, a study was performed with eight healthy volunteers (three males and five females, 26 ± 2 years old) and two patients (male, 15 and 11 years old) with diagnosed stage II juvenile osteochondritis dissecans (JOCD). ASL imaging utilized a flow-sensitive alternating inversion recovery method for labeling and a single-shot fast spin echo sequence for image readout. In addition to quantitative knee bone marrow ASL imaging, studies were also performed to evaluate the effects of prolonged post-bolus delay and varied labeling size. ASL imaging was successfully performed with all volunteers. Despite the benefits of hyper-intensive signal suppression within bone marrow, the use of a prolonged post-bolus delay caused excessive perfusion signal decay, resulting in low perfusion signal-to-noise ratio (SNR) and poor image quality. Bone marrow perfusion signal changed with the labeling size, suggesting that the measured bone marrow perfusion signal is flow-associated. The means and standard deviations of bone marrow blood flow, spatial SNR, and temporal SNR from the quantitative perfusion study were 38.3 ± 5.2 mL/100 g/min, 3.31 ± 0.48, and 1.33 ± 0.31, respectively. The imaging results from JOCD patients demonstrated the potential of ASL imaging to detect disease-associated bone marrow perfusion changes. This study demonstrates that it is feasible to perform ASL imaging of knee bone marrow in the distal femoral condyle at 3 T.
骨灌注是反映骨骼系统血管状态和组织活力的基本生理指标。动脉自旋标记（ASL）作为一种非侵入性和非对比增强的灌注成像方法，是人体研究的一种有吸引力的方法。为了评估在 3T MRI 扫描仪上对股骨远端髁的膝关节骨髓进行 ASL 灌注成像的可行性，对 8 名健康志愿者（3 名男性和 5 名女性，26±2 岁）和 2 名患有诊断为 II 期青少年剥脱性骨软骨炎（JOCD）的患者（男性，15 和 11 岁）进行了一项研究。ASL 成像采用流量敏感交替反转恢复方法进行标记，采用单次快速自旋回波序列进行图像读取。除了膝关节骨髓的定量 ASL 成像外，还进行了研究以评估延长的 post-bolus 延迟和不同的标记大小的影响。所有志愿者均成功进行了 ASL 成像。尽管骨髓内高强度信号抑制有其优势，但使用延长的 post-bolus 延迟会导致灌注信号过度衰减，导致低灌注信噪比（SNR）和图像质量差。骨髓灌注信号随标记大小而变化，表明测量的骨髓灌注信号与流动有关。定量灌注研究中骨髓血流量、空间 SNR 和时间 SNR 的平均值和标准差分别为 38.3±5.2 mL/100g/min、3.31±0.48 和 1.33±0.31。JOCD 患者的成像结果表明，ASL 成像有可能检测到与疾病相关的骨髓灌注变化。本研究表明，在 3T 下对股骨远端髁的膝关节骨髓进行 ASL 成像是可行的。
