Tan Hui, Fan Qiuju, Yu Yong, Yu Nan, Wang Shaoyu, Guo Shunlin
The First School of Clinical Medicine, Lanzhou University, Lanzhou, 730000, Gansu, China.
Department of Radiology, Affiliated Hospital of Shaanxi University of Chinese Medicine, Xianyang, 712000, Shaanxi, China.
BMC Musculoskelet Disord. 2025 Apr 22;26(1):402. doi: 10.1186/s12891-025-08660-6.
Fibrosis of the infrapatellar fat pad (IPFP) leads to changes in its stiffness, which may impact knee osteoarthritis. However, few studies have utilized virtual MR elastography to assess the variations of the IPFP. This study aimed to evaluate the value of intravoxel incoherent motion diffusion weighted imaging (IVIM-DWI)-based virtual MR elastography (vMRE) in the IPFP by assessing the test-retest repeatability, as well as intra- and inter-observer reproducibility.
A total of 71 subjects underwent IVIM-DWI examinations, which were conducted twice with an interval of 30-60 min using an 18-channel knee coil at 3T. Shifted apparent diffusion coefficient (sADC) was calculated from two different sets of b-values (b = 200/800 sec/mm and 200/1500 sec/mm) and then converted to IVIM-DWI MRI-based virtual shear modulus (μ and μ). Two readers independently delineated regions of interest (ROI) within the IPFP on the vMRE stiffness map to obtain the mean and standard deviation (SD) values of μ. Short-term test-retest repeatability, as well as intra- and inter-observer agreement were assessed using the intra-class correlation coefficient (ICC), the coefficient of variation (CoV), and Bland-Altman limits of agreement (LoA).
The mean and SD values of μ, along with the mean value of μ exhibited excellent intra- and inter-observer reproducibility agreement (ICC ≥ 0.90 and CoV ≤ 10%, P˂ 0.001). The intra- and inter-observer ICCs for the mean values of μ were 0.917 and 0.901, respectively, while the ICCs for the SD values of μ were 0.870 and 0.863, with CoV exceeding 10% (P˂ 0.001). The test-retest repeatability of the average value of μ was excellent (ICC = 0.902; CoV = 6.8%) compared to μ (ICC = 0.877; CoV = 15.3%). Test-retest repeatability of SD for μ was good (ICC = 0.803; CoV = 11.5%) in comparison to SD for μ (ICC = 0.796; CoV = 13.5%).
IVIM-DWI-based vMRE demonstrated significant potential as a reliable tool for measuring tissue elasticity in the IPFP, exhibiting higher repeatability for μ than for μ.
髌下脂肪垫（IPFP）纤维化会导致其硬度改变，这可能会影响膝关节骨关节炎。然而，很少有研究利用虚拟磁共振弹性成像来评估IPFP的变化。本研究旨在通过评估重测重复性以及观察者内和观察者间的可重复性，来评价基于体素内不相干运动扩散加权成像（IVIM-DWI）的虚拟磁共振弹性成像（vMRE）在IPFP中的价值。
共有71名受试者接受了IVIM-DWI检查，使用18通道膝关节线圈在3T下间隔30 - 60分钟进行两次检查。从两组不同的b值（b = 200/800秒/毫米和200/1500秒/毫米）计算出移位表观扩散系数（sADC），然后转换为基于IVIM-DWI MRI的虚拟剪切模量（μ和μ）。两名读者在vMRE硬度图上独立勾勒出IPFP内的感兴趣区域（ROI），以获得μ的平均值和标准差（SD）值。使用组内相关系数（ICC）、变异系数（CoV）和Bland-Altman一致性界限（LoA）评估短期重测重复性以及观察者内和观察者间的一致性。
μ的平均值和SD值以及μ的平均值在观察者内和观察者间均表现出极好的可重复性一致性（ICC≥0.90且CoV≤10%，P˂0.001）。μ平均值的观察者内和观察者间ICC分别为0.917和0.901，而μ标准差的ICC分别为0.870和0.863，CoV超过10%（P˂0.001）。与μ（ICC = 0.877；CoV = 15.3%）相比，μ平均值的重测重复性极好（ICC = 0.902；CoV = 6.8%）。与μ的标准差（ICC = 0.796；CoV = 13.5%）相比，μ的标准差的重测重复性良好（ICC = 0.803；CoV = 11.5%）。
基于IVIM-DWI的vMRE显示出作为测量IPFP组织弹性的可靠工具的巨大潜力，μ的重复性高于μ。
