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利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 早期骨性关节炎关节软骨基质改变的检测对药物开发具有重要意义。我们研究了在3.0T下比较T2、T1r和钠成像在健康志愿者和一名膝关节疼痛患者中的可行性。T2作图采用T2螺旋法。使用连续的自旋锁定脉冲在几个锁定频率下进行T1R成像。钠成像使用定制的表面线圈和短回声时间的3D视锥轨迹。我们的结果表明，在3.0T的体内比较这些方法对于早期软骨基质的改变是可行的。简介：早期检测软骨中蛋白多糖的耗竭对于开发骨关节炎的治疗方法非常重要。T1R成像，即在射频磁场影响下的自旋松弛，已被证明对软骨基质的变化很敏感。T2图被认为反映了软骨胶原基质的变化。钠成像也被用来测量软骨中蛋白多糖的含量。我们研究了这些技术在3.0T活体条件下应用的可行性。 方法：4名志愿者(年龄34-43岁)在GE Signa MRI(GE Healthcare，密尔沃基，威斯康星州)上以3.0T的速度使用3英寸线圈进行轴位成像。一名志愿者有膝盖前疼痛的病史。T1r的测量是用连续的RF自旋锁定脉冲在相同的解剖位置上进行的，自旋锁定频率分别为300、500、700和1000 Hz。连续射频序列的最大自旋锁定频率受到射频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的T2弛豫时间。T1R和CPMG T2序列具有相同的成像参数：TR为2000ms，14个螺旋臂，4096个点，带宽125 kHz。平面内分辨率为0.7 mm，视野16 cm，层厚4 mm。在5分钟内通过两个平均信号采集到一个穿过髌骨软骨的单层。T1序列获得了4个自旋锁定时间(TSL)，分别为3、15、35和80ms。CPMG T2序列在大约6、17、28、49、71和92ms处采集了6个回波。 钠成像采用定制的3英寸表面线圈和回声时间较短的“锥体”轨迹。以1.25×1.25×4 mm的体素大小获得钠的采集。扫描参数：TR/TE=50/0.6ms，FOV=16×16×12.8 cm，矩阵=128×128×32，读出时间=8ms，α=70°，平均16次，总扫描时间17分钟8 S。 在内侧和外侧的10个软骨位置测量每个受试者的T1p和T2松弛时间。在有膝关节疼痛的受试者中，还在内侧和外侧小关节的10个位置以及松弛时间延长的区域测量了钠信噪比。使用Osirix软件创建松弛测量和地图。

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 .