Clinical application of different shimming methods for two-dimensional and three-dimensional T 2 weighted imaging at 7.0 T MR / 中华放射学杂志

ABSTRACT

Objective:To evaluate the clinical value of different shimming methods at 7.0 T MR in two-dimensional (2D) and three-dimensional (3D) T 2WI. Methods:Totally 23 healthy volunteers were prospectively recruited from the First Medical Center of PLA General Hospital from November, 2022 to May, 2023, including 12 volunteers who underwent 2D shimming mode and 14 volunteers who underwent 3D shimming mode. 2D shimming mode included patient-specific (PS) mode, direct signal control (DSC) mode, the standard circularly polarized (CP) mode, and volume-specific (VS) mode. 3D shimming mode included universal pulses (UP) mode and CP mode. The image quality for the subtentorial and supratentorial region was assessed by the subjective image quality score and signal-to-noise ratio. Comparisons of quantitative indices between multiple groups were performed using repeated-measures ANOVA or Friedman′s test; comparisons of quantitative indices between 2 groups were performed using paired-samples t test or Wilcoxon signed-rank test. Results:The image quality of subtentorial region and SNR was significant differences in 2D T 2WI with PS mode, DSC mode, CP mode and VS mode ( F=26.74, P<0.001; F=28.24, P<0.001), and the image quality score and SNR of PS mode, DSC mode, VS mode were better than CP mode ( P<0.05). In 2D T 2WI, there was no significant difference in image quality score and SNR of supratentorial region in PS mode, DSC mode, CP mode ( P>0.05). Besides, in 3D T 2WI, the image quality score for subtentorial and supratentorial region of UP mode were better than those of CP mode ( Z=-2.74, P=0.006; Z=-3.24, P=0.001); SNR of subtentorial region was significantly better in UP mode than those in CP mode ( t=3.49, P=0.004). But there was no significant difference in SNR of supratentorial region between the UP mode and CP mode in 3D T 2WI ( P>0.05). Conclusion:T 2WI with different shimming methods at 7.0 T MR can provide data support for the clinical application, which is helpful for the accurate diagnosis of patients with subtentorial lesions.