Contrast-Enhanced MRI Combined With the Glycerol Test Reveals the Heterogeneous Dynamics of Endolymphatic Hydrops in Patients With Menière's Disease.

Background: The sensitivity of endolymphatic hydrops (EH) to the glycerol test varies in patients with Menière's disease (MD).

Purpose: To explore the features of EH and its glycerol-induced dynamics in MD.

Study Type: Case-control study.

Population: Twenty patients with MD (24 affected ears) were included.

Field Strength/sequence: 3.0T 3D-FLAIR (fluid-attenuated inversion recovery) MRI and late gadolinium enhancement.

Assessment: Intratympanic gadolinium-enhanced MRI was performed in the MD-affected ears before and after the glycerol test. The borders of the endolymphatic and total lymphatic space were contoured on the axial MRI slices to evaluate the volume of hydrops in both the cochlear and vestibular regions.

Statistical Tests: Paired and unpaired t-tests, the Mann-Whitney U-test, linear discriminant analysis, Pearson's correlation, and linear regression.

Results: After glycerol ingestion, vestibular EH decreased in all patients, whereas cochlear EH significantly decreased only in patients with positive glycerol test results (all P < 0.01). At baseline, cochlear EH in the positive result group was greater than in the negative result group (P = 0.007). Unexpectedly, in the positive result group a drastic glycerol-induced dehydrating effect was observed in patients whose pretest cochlear EH ratio was >16% (P = 0.011). Moreover, the dehydrating role of glycerol was positively correlated with the baseline cochlear hydrops level (r = 0.7691, P < 0.001).

Data Conclusion: MRI provides evidence that glycerol administration improves the hearing threshold via dehydrating the EH. In the cochlear region, the baseline level of cochlear EH is a closely related factor for the validity of the glycerol test, whereas EH is consistently dehydrated in the vestibular component.

Level Of Evidence: 2 TECHNICAL EFFICACY STAGE: 3 J. Magn. Reson. Imaging 2020;52:1066-1073.