Richard M. Lucas Center for Imaging, Stanford University, Stanford, California, USA.
Magn Reson Med. 2009 Nov;62(5):1202-10. doi: 10.1002/mrm.22111.
The saturation-recovery method using two and three recovery times is studied for conditions in which the sum of recovery times is 1.5T(1) to 3T(1), where T(1) is the longitudinal relaxation time. These conditions can reduce scan time considerably for long T(1) species and make longitudinal relaxation rate R(1) (R(1) = 1/T(1)) mapping for body fluids clinically feasible. Monte Carlo computer simulation is carried out to determine the ideal set of recovery times under various constraints of the sum of recovery times. The ideal set is found to be approximately invariant to the signal-to-noise ratio. For the three-point method, two of the recovery times should be set the same or approximately the same and should be shorter than the third one. Only marginal improvements in accuracy and precision can be achieved by the three-point method over the two-point method under a common constraint of the sum of recovery times. Three-dimensional, high resolution, whole-brain saturation-recovery scans on volunteers with a fast-spin-echo technique (XETA) and completed in a scan time of 10 min generated R(1) measurements of cerebrospinal fluid (T(1) approximately 4 s) in agreement with the computer simulation and literature results, which demonstrates the clinical feasibility of applying the two-point saturation-recovery method for R(1) mapping for long relaxation components.
使用两个和三个恢复时间的饱和恢复方法进行了研究，其中恢复时间的总和为 1.5T(1)至 3T(1)，其中 T(1)是纵向弛豫时间。这些条件可以大大减少长 T(1)物质的扫描时间，并使体液的纵向弛豫率 R(1) (R(1) = 1/T(1))映射在临床上成为可行的。进行了蒙特卡罗计算机模拟，以确定在各种恢复时间总和约束下的理想恢复时间集。发现理想集几乎不受信噪比的影响。对于三点法，两个恢复时间应该设置为相同或近似相同，并且应该短于第三个恢复时间。在恢复时间总和的常见约束下，三点法相对于两点法仅能略微提高准确性和精密度。志愿者的快速自旋回波技术（XETA）的三维、高分辨率、全脑饱和恢复扫描，扫描时间为 10 分钟，生成了与计算机模拟和文献结果一致的脑脊液 R(1)测量值（T(1)约为 4 秒），这证明了两点饱和恢复方法在长弛豫分量的 R(1)映射中的临床可行性。
