Department of Radiology, University of Michigan, Ann Arbor, Michigan.
School of Kinesiology, University of Michigan, Ann Arbor, Michigan.
Magn Reson Med. 2019 Jun;81(6):3763-3774. doi: 10.1002/mrm.27621. Epub 2019 Feb 22.
Anisotropic transverse R (1/T ) relaxation of water proton is sensitive to cartilage degenerative changes. The purpose is to develop an efficient method to extract this relaxation metric in clinical studies.
Anisotropic R can be measured inefficiently by standard R mapping after removing an isotropic contribution obtained from R mapping. In the proposed method, named as a unique anisotropic R of collagen degeneration (ARCADE) mapping, an assumed uniform isotropic R was estimated at magic angle locations in the deep cartilage, and an anisotropic R was thus isolated in a single T2W sagittal image. Five human knees from 4 volunteers were studied with standard R and R mappings at 3T, and anisotropic R derived from ARCADE on the T2W (TE = 48.8 ms) image from R mapping was compared with the composite relaxation (R - R ) using statistical analysis including Student's t-test and Pearson's correlation coefficient.
Anisotropic R (1/s) from ARCADE was highly positively correlated with but not significantly different from standard R - R (1/s) in the segmented deep (r = 0.83 ± 0.06; 8.3 ± 2.9 vs. 7.3 ± 1.9, P = .50) and the superficial (r = 0.82 ± 0.05; 3.5 ± 2.4 vs. 4.5 ± 1.6, P = .39) zones. However, after eliminating systematic errors by the normalization in terms of zonal contrast, anisotropic R was significantly higher (60.2 ± 18.5% vs. 38.4 ± 16.6%, P < .01) than R - R as predicted.
The proposed anisotropic R mapping could be an efficient alternative to the conventional approach, holding great promise in providing both high-resolution morphological and more sensitive transverse relaxation imaging from a single T2W scan in a clinical setting.
水质子各向异性横向弛豫率 R1/T1 对软骨退行性变敏感。目的是开发一种在临床研究中提取这种弛豫指标的有效方法。
通过从 R 映射中去除各向同性贡献来低效地测量各向异性 R1。在提出的方法中，称为胶原退变的各向异性 R1 专用图谱（ARCADE），在深软骨的魔角位置估计了一个假定的均匀各向同性 R1，并且在单个 T2W 矢状图像中分离了各向异性 R1。在 3T 下，对来自 4 名志愿者的 5 个膝关节进行了标准 R 和 R 映射研究，并使用统计分析比较了从 R 映射的 T2W（TE = 48.8ms）图像获得的 ARCADE 衍生的各向异性 R1 与复合弛豫（R-R），包括学生 t 检验和 Pearson 相关系数。
ARCADE 中的各向异性 R1/s 与分割的深层（r = 0.83 ± 0.06；8.3 ± 2.9 vs. 7.3 ± 1.9，P =.50）和浅层（r = 0.82 ± 0.05；3.5 ± 2.4 vs. 4.5 ± 1.6，P =.39）区域的标准 R-R 高度正相关，但通过基于区域对比度的归一化消除系统误差后，各向异性 R1 显著更高（60.2 ± 18.5% vs. 38.4 ± 16.6%，P <.01），正如预期的那样。
所提出的各向异性 R 图谱可以作为传统方法的有效替代方法，有望在临床环境中从单个 T2W 扫描提供高分辨率形态学和更敏感的横向弛豫成像。
