2½-minute 3D 7T 31 P-MRSI of the human heart using concentric rings (CRT)
2½-minute 3D 7T 31 P-MRSI of the human heart using concentric rings (CRT)
复制标题
使用同心环 (CRT) 对人体心脏进行 2 分钟 3D 7T 31 P-MRSI
DOI：
10.1101/2021.12.10.472120
复制
发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Clarke W
中科院分区：
文献类型：
--
作者：
Clarke W
本文采用3D密度加权同心环轨迹（CRT）MRSI序列对7 T心脏31 P-MRS进行了研究。传统相位编码CSI序列的逐点k空间采样严重限制了在较高空间分辨率下的最小扫描时间。我们提出的CRT序列实现了一堆同心环轨迹，具有可变数量的环和平面，以优化k空间加权的密度。这创造了灵活的采集时间，允许收购大大快于传统的相位编码CSI序列，同时保持高SNR.We首先在幻影的CRT序列的信噪比和点扩散函数。然后，我们在五个不同的采集时间和空间分辨率在7 T的五个健康参与者的心脏进行评估。将这些不同的序列持续时间与具有匹配的采集时间和空间分辨率的现有公布的3D采集加权CSI序列进行比较。为了最大限度地减少噪声对短期采集的影响，采集后还对时空数据进行了低秩去噪。拟议的序列在2.5分钟内测量人体心肌的3D局部PCr/ATP比，比采集加权相位编码CSI的最小扫描时间快2.6倍。或者，在相同的扫描时间内，可以实现1.7倍的标称体素体积。在所有协议中，低秩去噪将测得的PCr/ATP比值的方差降低了11%。7 T CRT 31 P-MRSI允许的更快采集可以使心脏应力方案或肌酸激酶速率测量（涉及重复扫描）更易于患者耐受，而不会牺牲空间分辨率。
A 3D density-weighted concentric ring trajectory (CRT) MRSI sequence is implemented for cardiac31P-MRS at 7T.The point-by-point k-space sampling of traditional phase-encoded CSI sequences severely restricts the minimum scan time at higher spatial resolutions. Our proposed CRT sequence implements a stack of concentric rings trajectory, with a variable number of rings and planes spaced to optimise the density of k-space weighting. This creates flexibility in acquisition time, allowing acquisitions substantially faster than traditional phase-encoded CSI sequences, while retaining high SNR.We first characterise the signal-to-noise ratio and point spread function of the CRT sequence in phantoms. We then evaluate it at five different acquisition times and spatial resolutions in the hearts of five healthy participants at 7T. These different sequence durations are compared with existing published 3D acquisition-weighted CSI sequences with matched acquisition times and spatial resolutions. To minimise the effect of noise on the short acquisitions, low-rank denoising of the spatio-temporal data was also performed after acquisition.The proposed sequence measures 3D localised PCr/ATP ratios of the human myocardium in 2.5 minutes, 2.6 times faster than the minimum scan time for the acquisition-weighted phase-encoded CSI. Alternatively, in the same scan time a 1.7-times smaller nominal voxel volume can be achieved. Low-rank denoising reduced the variance of measured PCr/ATP ratios by 11% across all protocols. The faster acquisitions permitted by 7T CRT31P-MRSI could make cardiac stress protocols or creatine kinase rate measurements (which involve repeated scans) more tolerable for patients without sacrificing spatial resolution.