Cartilage Restoration Center, Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA.
Osteoarthritis Cartilage. 2011 Jan;19(1):84-8. doi: 10.1016/j.joca.2010.10.018. Epub 2010 Oct 28.
Ultrashort echo-time enhanced T2∗ (UTE-T2∗) mapping of articular cartilage is a novel quantitative MRI technique with the potential to visualize deep cartilage characteristics better than standard T2 mapping. The feasibility and intersession repeatability of UTE-T2∗ mapping of cartilage in vivo has not previously been evaluated.
Eleven asymptomatic subjects underwent repeat UTE-T2∗ imaging on a whole-body 3T MRI scanner on three consecutive days. Full-thickness, superficial and deep regions of interest (ROIs) were evaluated in the central weight-bearing zones of the medial femoral condyle (cMFC) and tibial plateau (cMTP). Intersession precision error across subjects was evaluated by the root-mean-square average coefficients of variation (RMSA-CV) and by the median of intra-subject standard deviations (SDs) of UTE-T2∗ values in each ROI.
UTE-T2∗ values in vivo were found to be repeatable with relative (RMSA-CV) intersession precision errors of 8%, 6%, 16% for full-thickness, superficial and deep cMFC ROIs, corresponding to absolute errors (SD) of 1.2, 1.5, 1.5 ms, respectively. In cMTP tissue, UTE-T2∗ relative repeatability was 8%, 8%, 13%, corresponding to absolute repeatability of 1.0, 1.5, 2.1 ms (full-thickness, superficial, deep). UTE-T2∗ values were higher in superficial cartilage compared to deep in both cMFC (P≪0.001) and cMTP (P=0.0004) regions.
In vivo 3D UTE-T2∗ mapping at 3T is feasible and can be implemented using a standard clinical MRI scanner and knee coil. Intersession precision error of UTE-T2∗ values in full-thickness ROIs in the weight-bearing regions of asymptomatic subjects is under 1.2 ms or 8% (RMSA-CV). Significant zonal and regional variations of UTE-T2∗ were seen.
超短回波时间增强 T2*（UTE-T2*）成像技术是一种新型的定量磁共振成像技术，与标准 T2 映射相比，它具有更好地显示深层软骨特征的潜力。在活体中，UTE-T2*软骨成像的可行性和可重复性尚未得到评估。
11 名无症状受试者在连续 3 天内在全身 3T MRI 扫描仪上进行重复 UTE-T2成像。在中央负重区的内侧股骨髁（cMFC）和胫骨平台（cMTP）中评估全层、浅层和深层的兴趣区（ROI）。通过受试者间均方根平均变异系数（RMSA-CV）和每个 ROI 中 UTE-T2值的受试者内标准差（SD）中位数评估跨节次的精密度误差。
体内 UTE-T2值具有可重复性，全层、浅层和深层 cMFC ROI 的相对（RMSA-CV）跨节次精密度误差分别为 8%、6%和 16%，对应的绝对误差（SD）分别为 1.2、1.5 和 1.5 ms。在 cMTP 组织中，UTE-T2的相对重复性为 8%、8%和 13%，对应的绝对重复性为 1.0、1.5 和 2.1 ms（全层、浅层和深层）。在 cMFC（P≪0.001）和 cMTP（P=0.0004）区域中，浅层软骨的 UTE-T2*值均高于深层软骨。
在 3T 下，活体 3D UTE-T2成像可行，并且可以使用标准的临床 MRI 扫描仪和膝关节线圈来实现。在无症状受试者负重区的全层 ROI 中，UTE-T2值的跨节次精密度误差小于 1.2 ms 或 8%（RMSA-CV）。观察到 UTE-T2*的明显的区域性和区域性变化。
