Fukunaga Kota, Enzaki Masahiro, Komi Masanori, Azuma Minako, Hirai Toshinori, Fujiwara Yasuhiro
Graduate School of Health Sciences, Kumamoto University.
Radiology Section, University of Miyazaki Hospital.
Nihon Hoshasen Gijutsu Gakkai Zasshi. 2023 Jul 20;79(7):663-673. doi: 10.6009/jjrt.2023-1343. Epub 2023 May 19.
Three-dimensional (3D) quantification using an interleaved Look-Locker acquisition sequence with a T preparation pulse (QALAS) is a quantitative sequence used to measure relaxation times. The accuracy of the relaxation time measurement of 3D-QALAS at 3.0 T and the bias of 3D-QALAS have not yet been assessed. The purpose of this study was to clarify the accuracy of the relaxation time measurements using 3D-QALAS at 3.0 T MRI.
The accuracy of the T and T values for 3D-QALAS was evaluated using a phantom. Subsequently, the T and T values and proton density of the brain parenchyma in healthy subjects were measured using 3D-QALAS and compared with those of 2D multi-dynamic multi-echo (MDME).
In the phantom study, the average T value of 3D-QALAS was 8.3% prolonged than that for conventional inversion recovery spin-echo; the average T value for 3D-QALAS was 18.4% shorter than that for multi-echo spin-echo. The in vivo assessment showed that the mean T and T values and PD for 3D-QALAS were prolonged by 5.3%, shortened by 9.6%, and increased by 7.0%, respectively, compared with those for 2D-MDME.
Although 3D-QALAS at 3.0 T has high accuracy T value, which is less than 1000 ms, the T value could be overestimated for tissues with it longer than that T value. The T value for 3D-QALAS could be underestimated for tissues with T values, and this tendency increases with longer T values.
使用带有T准备脉冲的交错式Look-Locker采集序列进行三维（3D）定量（QALAS）是一种用于测量弛豫时间的定量序列。尚未评估3D-QALAS在3.0 T时弛豫时间测量的准确性以及3D-QALAS的偏差。本研究的目的是阐明在3.0 T磁共振成像（MRI）中使用3D-QALAS进行弛豫时间测量的准确性。
使用体模评估3D-QALAS的T1和T2值的准确性。随后，使用3D-QALAS测量健康受试者脑实质的T1和T2值以及质子密度，并与二维多动态多回波（MDME）的测量结果进行比较。
在体模研究中，3D-QALAS的平均T1值比传统反转恢复自旋回波延长了8.3%；3D-QALAS的平均T2值比多回波自旋回波缩短了18.4%。体内评估显示，与二维MDME相比，3D-QALAS的平均T1和T2值以及质子密度分别延长了5.3%、缩短了9.6%和增加了7.0%。
尽管3.0 T时的3D-QALAS对于T1值小于1000 ms的组织具有较高的准确性，但对于T1值较长的组织，T1值可能会被高估。对于T2值较短的组织，3D-QALAS的T2值可能会被低估，并且这种趋势随着T2值的延长而增加。
