IN VIVO T2, T1R, AND SODIUM IMAGING OF ARTICULAR CARTILAGE AT 30T

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 早期骨关节炎关节软骨基质变化的检测对药物发现具有重要意义。 我们研究了在3.0T下比较健康志愿者和一名膝关节疼痛受试者的T2、T1 r和钠成像的可行性。T2标测采用T2准备螺旋法。T1 r成像使用连续自旋锁定脉冲在几个锁定频率。 使用定制表面线圈和短回波时间3D锥体轨迹进行钠成像。 我们的研究结果表明，这是可行的，在体内比较这些方法在3.0T的早期软骨matrix changes.Introduction：早期检测软骨中的蛋白多糖耗竭是重要的骨关节炎治疗的发展。 T1 r成像，即射频场影响下的自旋弛豫，已被证明对软骨基质的变化敏感。T2映射被认为反映了软骨胶原基质的变化。 钠成像也被用于测量软骨中的蛋白聚糖含量。 我们研究了在3.0T下在体内使用这些技术的可行性。 方法：在GE Signa MRI（GE Healthcare，密尔沃基，WI）上，使用3英寸线圈，在3.0 T轴向平面内对4名志愿者（年龄34-43岁）进行成像。 1名志愿者有膝前疼痛史。T1 r的测量是在相同的解剖位置用连续RF自旋锁定脉冲进行的，自旋锁定频率为300、500、700和1000 Hz。 连续RF序列中的最大自旋锁定频率受到RF功率沉积极限的限制。 使用T2准备的螺旋序列测量相同位置处的T2弛豫时间。 T1 r和CPMG T2序列具有相同的成像参数：TR为2000 ms，14个旋臂，4096个点，带宽为+125 kHz。 平面内分辨率为0.7 mm，FOV为16 cm，层厚为4 mm。 在5分钟内获得穿过髌骨软骨的单个切片，具有两个信号平均值。 T1 r序列采集了3、15、35和80 ms的4个自旋锁定时间（TSL）。 CPMG T2序列在大约6、17、28、49、71和92 ms处采集6个回波。 使用定制的3英寸表面线圈和短回波时间“锥体”轨迹进行钠成像。在1.25x1.25x4 mm的体素尺寸下获得钠采集。扫描参数为：TR/TE = 50/0.6 ms，FOV = 16x16x12.8 cm，矩阵= 128 x128 x32，读出时间= 8 ms，α = 70 deg，16个平均值，总扫描时间为17 min 8 s。 在内侧和外侧髌骨小平面上的10个软骨位置测量每个受试者的T1 p和T2弛豫时间。 还在内侧和外侧关节面上的10个位置以及膝关节疼痛受试者中松弛时间增加的区域测量了钠SNR。 使用Osirix软件创建弛豫测量和图。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Detection of matrix changes of articular cartilage in early osteoarthritis is important for drug discovery. We studied the fesability of comparing T2, T1r, and sodium imaging in healthy volunteers and one subject with knee pain at 3.0T. T2 mapping was done with a T2-prepared spiral method. T1r imaging was performed using a continious spin-lock pulse at several locking frequencies. Sodium imaging was done with a custom surface coil and a short echo-time 3D cones trajectory. Our results indicate it is feasible to compare these methods in vivo at 3.0T for early cartilage matrix changes.Introduction: Early detection of proteoglycan depletion in cartilage is important in development of treatments for osteoarthritis. T1r imaging, or relaxation of spins under the influence of a radio-frequency field, has been shown to be sensitive to changes in the cartilage matrix . T2 mapping is thought to reflect changes in the collagen matrix of cartilage. Sodium imaging has also been used to measure proteoglycan content in cartilage. We studied the feasibility of using these techniques in vivo at 3.0T. Methods: Four volunteers (ages 34-43) were imaged in the axial plane at 3.0T on a GE Signa MRI (GE Healthcare, Milwaukee, WI) using 3-inch coil. One volunteer had a history of anterior knee pain. Measurements of T1r were made with a continuous RF spin locking pulse at the same anatomic locations with spin lock frequencies of 300, 500, 700 and 1000 Hz. The maximum spin-lock frequency in the continuous RF sequence was limited by RF power deposition limits. T2 relaxation time at the same location was measured using a T2-prepared spiral sequence. The T1r and CPMG T2 sequences had identical imaging parameters: TR of 2000 ms, 14 spiral arms, 4096 points, and bandwidth +125 kHz. In-plane resolution was 0.7 mm with a 16 cm FOV, 4 mm slice thickness. A single slice through the patella cartilage was acquired in 5 minutes with two signal averages. The T1r sequences acquired 4 spin lock times (TSL) of 3, 15, 35, and 80 ms. The CPMG T2 sequence acquired 6 echoes at approximately 6, 17, 28, 49, 71 and 92 ms. Sodium imaging was performed with a custom 3-inch surfaces coil and a short echo time "cones" trajectory . Sodium acquisitions were obtained at a voxel size of 1.25x1.25x4 mm. Parameters for the scan were: TR/TE = 50/0.6 ms, FOV = 16x16x12.8cm, matrix = 128x128x32, readout time = 8 ms, alpha = 70 deg, and 16 averages for a total scan time of 17 min 8 s. T1p and T2 relaxation times for each subject were measured in 10 cartilage locations on the medial and lateral patella facets. Sodium SNR was also measured in 10 locations on the medial and lateral facets, and in an area of increased relaxation times in the subject with knee pain. Relaxation measurements and maps were created using Osirix software .