RESUMO
Objective:To evaluate the value of a three-dimensional inversion-recovery with real reconstruction (3D-real IR) sequence with an ultralong repetition time (TR) for the endolymphatic hydrops (EH) of Meniere disease (MD) after intravenous gadolinium administration, and compare it with a heavily T 2-weighted three-dimensional fluid-attenuated inversion recovery (hT 2-3D-FLAIR) sequence. Methods:From July 2021 to July 2022, 52 definite MD patients (58 ears) were retrospectively enrolled at Zhongshan Hospital, Fudan University. The 3D-real IR with an ultralong TR (16 000 ms) and hT 2-3D-FLAIR sequences were performed four hours after intravenous single-dose gadolinium administration. The image quality of the two sequences was rated. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were measured in the two sequence. The EH of cochlear and vestibular was graded, and EH detection rates were calculated. Scores of the two sequences were compared using the paired Wilcoxon signed rank test. Paired t test was used to compare the differences of the SNR and CNR. McNemar test was performed to compare the EH detection rate between the two sequences. Results:The score of the 3D-real IR [3 (3, 4)] was significantly higher than that of the hT 2-3D-FLAIR [2.5 (2, 3), Z=-6.06, P<0.001]. No significant difference was found in SNR of 3D-real IR and hT 2-3D-FLAIR (11.4±6.5 and 12.3±3.7, t=-1.38, P=0.175). CNR of the 3D-real IR (21.7±9.3) was significantly higher than that of the hT 2-3D-FLAIR (9.7±3.8, t=10.67, P<0.001). Using 3D-real IR sequence, the EH detection rate of cochlear (89.7%, 52/58) was higher than using hT 2-3D-FLAIR (67.2%, 39/58, χ 2=11.10, P<0.001). No significant difference was found in the EH detection rate of vestibular between 3D-real IR (77.6%, 45/58) and hT 2-3D-FLAIR (74.1%, 43/58, χ 2=0.50, P=0.500). Conclusion:Compared with hT 2-3D-FLAIR sequence, the 3D-real IR with an ultralong TR can improve the depiction of EH in MD patients after intravenous single-dose gadolinium administration. It can provide higher image quality and detection rate of EH.
RESUMO
Objective To observe whether repetition time (TR) and field strengths have effects on diffusion indices of brain white matter. Methods Seven rhesuses underwent diffusion tensor MR imaging (DT-MRI) with a series of TRs (from 500 to 6000 ms) at 1.5T and 3.0T MR scanners, respectively. The mean diffusivity (MD), fractional anisotropy (FA), primary (λ1) and transverse eigenvalues (λ2, 3) were measured in region of interest (ROI) at the posterior limb of internal capsule. Pearson correlation analysis and two-way ANOVA were performed. Results None of the diffusion indices was correlated with TR (P＞0.05) when SNR was high enough (SNR>35). FA was significantly higher and the MD and λ2, 3 were significantly lower at 3.0T than those at 1.5T (P＜0.001). No significant difference of λ1 was found between the two field strengths (P＞0.05). Conclusion Field strength may influence diffusion quantification, but not for TR, which should be considered in multi-center studies.