Department of Radiology, New York University Langone Medical Center, 660 First Ave, 4th Floor, New York, NY 10016, USA.
Radiology. 2012 Feb;262(2):550-9. doi: 10.1148/radiol.11110821. Epub 2011 Nov 21.
To investigate technical feasibility, test-retest reproducibility, and the ability to differentiate healthy subjects from subjects with osteoarthritis (OA) with diffusion-tensor (DT) imaging parameters and T2 relaxation time.
This study was approved by the institutional review board and was HIPAA compliant. All subjects provided written informed consent. DT imaging parameters and T2 (resolution=0.6×0.6×2 mm) of patellar cartilage were measured at 7.0 T in 16 healthy volunteers and 10 patients with OA with subtle inhomogeneous signal intensity but no signs of cartilage erosion at clinical magnetic resonance (MR) imaging. Ten volunteers were imaged twice to determine test-retest reproducibility. After cartilage segmentation, maps of mean apparent diffusion coefficient (ADC), fractional anisotropy (FA), and T2 relaxation time were calculated. Differences for ADC, FA, and T2 between the healthy and OA populations were assessed with nonparametric tests. The ability of each MR imaging parameter to help discriminate healthy subjects from subjects with OA was assessed by using receiver operating characteristic curve analysis.
Test-retest reproducibility was better than 10% for mean ADC (8.1%), FA (9.7%), and T2 (5.9%). Mean ADC and FA differed significantly (P<.01) between the OA and healthy populations, but T2 did not. For ADC, the optimal threshold to differentiate both populations was 1.2×10(-3) mm2/sec, achieving specificity of 1.0 (16 of 16) and sensitivity of 0.80 (eight of 10). For FA, the optimal threshold was 0.25, yielding specificity of 0.88 (14 of 16) and sensitivity of 0.80 (eight of 10). T2 showed poor differentiation between groups (optimal threshold=22.9 msec, specificity=0.69 [11 of 16], sensitivity=0.60 [six of 10]).
In vivo DT imaging of patellar cartilage is feasible, has good test-retest reproducibility, and may be accurate in discriminating healthy subjects from subjects with OA. ADC and FA are two promising biomarkers for early OA.
通过弥散张量（DT）成像参数和 T2 弛豫时间来研究技术可行性、重测可重复性以及区分健康受试者和骨关节炎（OA）患者的能力。
本研究经机构审查委员会批准并符合 HIPAA 规定。所有受试者均提供书面知情同意书。在 7.0T 下对 16 名健康志愿者和 10 名临床磁共振成像（MR）显示轻微不均匀信号强度但无软骨侵蚀征象的 OA 患者的髌软骨进行 DT 成像参数和 T2（分辨率=0.6×0.6×2mm）测量。10 名志愿者进行两次成像以确定重测可重复性。在软骨分割后，计算平均表观扩散系数（ADC）、各向异性分数（FA）和 T2 弛豫时间图。使用非参数检验评估健康人群和 OA 人群之间 ADC、FA 和 T2 的差异。使用受试者工作特征曲线分析评估每种 MR 成像参数帮助区分健康受试者和 OA 患者的能力。
平均 ADC（8.1%）、FA（9.7%）和 T2（5.9%）的重测可重复性均优于 10%。OA 组和健康组之间的平均 ADC 和 FA 差异有统计学意义（P<.01），但 T2 无差异。对于 ADC，区分两组的最佳阈值为 1.2×10(-3)mm2/sec，特异性为 1.0（16/16），敏感性为 0.80（10/10）。对于 FA，最佳阈值为 0.25，特异性为 0.88（14/16），敏感性为 0.80（10/10）。T2 对两组的区分能力较差（最佳阈值=22.9msec，特异性=0.69（16/16），敏感性=0.60（10/10））。
髌软骨的体内 DT 成像具有可行性，重测可重复性良好，并且可能能够准确区分健康受试者和 OA 患者。ADC 和 FA 是两种有前途的早期 OA 生物标志物。
