In Vivo Detection of Ampullary T2 Hypointensity as a Marker of Vestibular Atelectasis

Background and purpose: Vestibular atelectasis (VA) is a histologically defined collapse of the membranous labyrinth, often accompanied by dense basophilic deposits. While delayed postcontrast 3D-FLAIR imaging allows indirect visualization of VA, no in vivo correlate of the basophilic deposits has been reported. This study describes a novel T2-weighted hypointense signal within the ampullae and utricle as a potential imaging biomarker of VA and explores its clinical relevance in patients with bilateral vestibular areflexia. Materials and methods: This retrospective study included 47 patients with bilateral vestibular areflexia, confirmed by video Head Impulse Test and vestibular-evoked myogenic potentials. All underwent 3T MRI with delayed postcontrast 3D-FLAIR and high-resolution T2-weighted sequences. The presence and distribution of ampullary or utricular T2 hypointensities were evaluated and correlated with radiological VA, clinical presentation, and vestibular function. Results: Among the 47 patients included, VA was identified in 32 (68.1%). A distinct T2 hypointense signal was observed in 25 patients (53.2%), exclusively within the VA group. These hypointensities were significantly more prevalent in the superior and posterior ampullae compared to the lateral (FDR- P <0.001). VA patients were significantly younger, had better hearing thresholds and more severe posterior canal dysfunction; short vertigo episodes were more frequent in this group without reaching statistical significance. In age-adjusted Firth logistic regression, ampullary hypointensity was the only variable independently associated with VA (odds ratio: 124.59, 95% CI: 5.35-2900.22; apparent area under the curve: 0.973, 95% CI: 0.890-0.994), although the estimate was imprecise owing to quasi-complete separation (FDR- P =0.0104). Conclusion: A T2 hypointense signal within the ampullae and utricle was observed exclusively in patients with radiological vestibular atelectasis in this cohort. Its anatomical distribution is compatible with the basophilic deposits described in histopathological series, although this correspondence remains hypothetical in the absence of tissue analysis. This MRI sign may raise suspicion of VA when delayed postcontrast 3D-FLAIR imaging is unavailable or contraindicated, rather than replace it.