Visualization of the saccule and utricle with non-contrast-enhanced FLAIR sequences.

Abstract

3D-fluid attenuation inversion recovery (FLAIR) collected 4h after intravenous gadolinium injection can delineate the perilymphatic space (PLS) from the endolymphatic space (ELS) to capture endolymphatic hydrops, the pathological counterpart of Ménière's disease. We aimed to optimize visualization of such inner ear internal anatomy using 3D-FLAIR without injection. 3D-FLAIR signal from different fluid compartments such as PLS and ELS was first simulated. Then, twenty-two healthy subjects were scanned at 3.0-T MRI with non-injected 3D-FLAIR using variable T2 preparations (T2Preps) (OFF, 200, 400, and 600ms) and variable inversion times (TIs) (from 224 to 5000ms) and different resolutions (1.0 × 1.0 × 1.5, 0.6 × 0.6 × 0.8, and 0.6 × 0.6 × 0.6 mm3). The relative contrast between PLS and ELS and the visibility of the saccule and utricle were assessed. Additionally, non-injected 3D-FLAIR with the optimal setting was tested in a Ménière patient and compared with gadolinium-injected 3D-FLAIR. The PLS and ELS were differentiated when T2Prep was used but not without. The relative contrast was larger with T2Prep at 400ms than at 200 or 600ms (0.72 ± 0.22 vs. 0.44 ± 0.11, p = 0.019; and 0.72 ± 0.22 vs. 0.46 ± 0.28, p = 0.034, respectively). The saccule and utricle were best delineated in 87. % cases with T2Prep = 400 and TI = 2100ms at the highest resolution. Visualization of the saccule and utricle in the optimized non-injected 3D-FLAIR was similar to conventional injected 3D-FLAIR in a patient. Combining a specific T2Prep and TI in non-injected 3D-FLAIR could separate PLS and ELS and even the saccule and utricle, paving the way toward future application to diagnose Ménière's disease. • MRI can capture the internal anatomy of inner ear without injection of contrast media. • Specific parameters consisting of a T2 preparation of 400ms and an inversion time of 2100ms must be used to visualize the saccule and utricle on non-injected 3D-FLAIR.