Isolated Congenital Middle Ear Malformations: Comparison of preoperative 0.1 mm Ultra-High-Resolution CT and Conventional High-Resolution CT.

Abstract

Background and purpose: Isolated congenital middle ear malformation contributes significantly to congenital hearing loss and growth problems. This study aims to compare 0.1 mm isotropic ultra-high-resolution computed tomography and conventional high-resolution computed tomography for assessing isolated congenital middle ear malformation, using surgical exploration as the gold standard.

Materials and methods: This single-center retrospective study included patients with surgically confirmed isolated congenital middle ear malformation who underwent ultra-high-resolution CT or high-resolution CT from January 2015 to April 2025. Middle ear abnormalities were identified based on operative outcomes and four subtypes were classified via the Teunissen standard. Two neuroradiologists blinded to surgical outcomes reviewed CT images for ten subtle structural abnormalities and specific subtypes. The comparison of ultra-high-resolution CT and high-resolution CT in terms of inter-observer and intra-observer agreement and detection of structural abnormalities and subtypes of congenital middle ear malformation were analyzed.

Results: The ultra-high-resolution CT and high-resolution CT groups included 61 patients (69 ears) and 37 patients (44 ears), respectively. Ultra-high-resolution CT exhibited significantly higher inter-observer and intra-observer agreement and stronger concordance with surgical findings for all 10 abnormalities compared to high-resolution CT. It also showed superior diagnostic sensitivity for congenital middle ear malformation (100.0% vs. 90.9%, P=0.013) and outperformed high-resolution CT in differentiating clinical subtypes (0.774 vs. 0.352, P< 0.001). Ultra-high-resolution CT achieved accuracies exceeding 0.85 in identifying all abnormalities and outperformed high-resolution CT in detecting specific abnormalities including abnormal long process of the incus, lenticular process, abnormal stapes superstructure, stapes footplate fixation, and oval window atresia (P< 0.05).

Conclusions: Isotropic 0.1 mm ultra-high-resolution CT significantly outperforms conventional high-resolution CT in diagnosing congenital middle ear malformation, differencing subtypes and detecting subtle abnormalities, supporting its clinical superiority for precise preoperative evaluation.

Abbreviations: CMEM= congenital middle ear malformation; HRCT= high-resolution computed tomography; U-HRCT=ultra-highresolution computed tomography; PCD-CT= photon-counting detector CT.