Optimal MRI protocol for acute unilateral vestibulopathy: 3D-fsFLAIR vs 3D-fsT1WI at multiple post-contrast time points.

Abstract

To compare three-dimensional fat-suppressed fluid-attenuated inversion recovery (3D-fsFLAIR) with three-dimensional fat-suppressed T1-weighted imaging (3D-fsT1WI) for detecting superior vestibular nerve (SVN) enhancement in acute unilateral vestibulopathy (AUVP), and to determine the optimal post-contrast imaging time. This single-center prospective cohort study enrolled consecutive patients who underwent 3D-fsFLAIR and 3D-fsT1WI at 0 min, 15 min, 1 h, and 4 h post-contrast between April 2022 and May 2023. Two blinded radiologists independently scored asymmetric enhancement of the SVN on both sequences and, using 3D-fsFLAIR alone, measured the SVN signal intensity ratio (SIR) and signal-to-noise ratio (SNR) quantitatively while also qualitatively grading asymmetric inner-ear enhancement. Statistical analyses employed generalized linear mixed models, nested linear mixed-effects models, and Friedman tests. The study included 54 AUVP patients (mean age, 44.87 ± 11.47 years; 29 men). 3D-fsFLAIR yielded significantly higher asymmetric SVN enhancement scores than 3D-fsT1WI at every time point, with both sequences achieving peak visualization at 1 h (all p < 0.001). Quantitative analysis on 3D-fsFLAIR showed significantly elevated SIR and SNR in the affected SVN at 1 h and 4 h compared with 0 min and 15 min (all p < 0.001), with no significant difference between the 1 h and 4 h. Similarly, asymmetric inner-ear enhancement scores were greater at 1 h and 4 h than in the early phases (all p < 0.05), but plateaued after 1 h (p = 0.29). The 1 h delayed 3D-fsFLAIR protocol optimized AUVP evaluation, offered superior lesion detection, and clinical practicality. Question The optimal sequence selection between 3D-fsFLAIR and 3D-fsT1WI for AUVP evaluation and the ideal post-contrast timing remain to be determined. Findings The optimal protocol for AUVP evaluation is the 1 h post-contrast delayed 3D-fsFLAIR sequence, which provides superior lesion detection capability and enhanced clinical practicality. Clinical relevance The 1 h delayed 3D-fsFLAIR protocol provides optimal visualization of vestibular nerve and inner ear abnormalities in AUVP, enabling more confident clinical assessment without requiring longer delays (e.g., 4 h).