Center for Brain Imaging Science and Technology, Key Laboratory for Biomedical Engineering of Ministry of Education, College of Biomedical Engineering and Instrumental Science, Zhejiang University, Hangzhou, Zhejiang, China.
State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou, Zhejiang, China.
Magn Reson Med. 2019 Oct;82(4):1359-1372. doi: 10.1002/mrm.27812. Epub 2019 May 27.
To demonstrate an ultrashort echo time magnetic resonance fingerprinting (UTE-MRF) method that allows quantifying relaxation times for muscle and bone in the musculoskeletal system and generating bone enhanced images that mimic CT scans.
A fast imaging steady-state free precession MRF sequence with half pulse excitation and half projection readout was designed to sample fast T decay signals. Varying echo time (TE) of a sinusoidal pattern was applied to enhance sensitivity for tissues with short and ultrashort T values. The performance of UTE-MRF was evaluated via simulations, phantom, and in vivo experiments.
A minimal TE of 0.05 ms was achieved. Simulations indicated the sinusoidal TE sampling increased T quantification accuracy in the cortical bone and tendon but had little impact on long T muscle quantifications. For the rubber phantom, the averaged relaxometries from UTE-MRF (T = 162 ms and T = 1.07 ms) compared well with the gold standard (T = 190 ms and = 1.03 ms). For the long T agarose phantom, the linear regression slope between UTE-MRF and gold standard was 1.07 (R = 0.991) for T and 1.04 (R = 0.994) for T . In vivo experiments showed the detection of the cortical bone (averaged T = 1.0 ms) and Achilles tendon (averaged T = 15 ms). Scalp structures from the bone enhanced image show high similarity with CT.
The UTE-MRF with sinusoidal TEs can simultaneously quantify T , T , proton density, and B in long, short, even ultrashort T musculoskeletal structures. Bone enhanced images can be achieved in the brain with UTE-MRF.
展示一种超短回波时间磁共振指纹成像(UTE-MRF)方法,该方法可用于定量测量骨骼肌肉系统中肌肉和骨骼的弛豫时间,并生成模拟 CT 扫描的增强骨图像。
设计了一种快速成像稳态自由进动 MRF 序列,采用半脉冲激励和半投影读出方式来采集快速 T 衰减信号。应用正弦形的可变回波时间(TE)来增强对短和超短 T 值组织的灵敏度。通过模拟、体模和活体实验来评估 UTE-MRF 的性能。
实现了最小的 TE 为 0.05 ms。模拟结果表明,正弦 TE 采样提高了皮质骨和肌腱的 T 定量准确性,但对长 T 肌肉的定量影响很小。对于橡胶体模,UTE-MRF 的平均弛豫率(T = 162 ms 和 T = 1.07 ms)与金标准(T = 190 ms 和 = 1.03 ms)相比非常吻合。对于长 T 琼脂糖体模,UTE-MRF 与金标准之间的线性回归斜率为 T 为 1.07(R = 0.991),T 为 1.04(R = 0.994)。活体实验显示了皮质骨(平均 T = 1.0 ms)和跟腱(平均 T = 15 ms)的检测。骨增强图像中的头皮结构与 CT 高度相似。
具有正弦 TE 的 UTE-MRF 可以同时定量测量长、短、甚至超短 T 骨骼肌肉结构中的 T 、T 、质子密度和 B。可以通过 UTE-MRF 在大脑中获得增强骨图像。