Computed tomography characterization of masticatory muscle tendon-aponeurosis hyperplasia through morphological analysis of the coronoid process, mandibular condyle, and peritemporal adipose layer.

PURPOSE: To characterize the computed tomography (CT) features of masticatory muscle tendon-aponeurosis hyperplasia (MMTAH) and evaluate their diagnostic discriminative ability. METHODS: This retrospective study evaluated 17 patients with MMTAH and 41 controls who underwent CT for non-MMTAH indications. The anteroposterior and transverse diameters of the coronoid process at its central portion, the long, and short axes of the mandibular condyle at its largest cross-section, and the area of the peritemporal adipose layer at the level of the coronoid tip were measured on axial CT using attenuation-based semi-automated segmentation. Two board-certified oral and maxillofacial radiologists performed duplicate measurements twice with a 2 week minimum interval. Group comparisons used the Mann-Whitney U test (two-tailed, P < 0.05). RESULTS: Most variables had high reliability (ICC > 0.90). The coronoid diameters and condylar axes were significantly larger, whereas the peritemporal adipose areas were significantly smaller in MMTAH patients than in controls (all P < 0.01). Box and whisker plots demonstrated complete interquartile range separation for coronoid transverse diameters between groups, indicating the strongest discriminative performance among the tested metrics. CONCLUSION: MMTAH is characterized by coronoid enlargement, adjunctive condylar enlargement, and a reduction in the peritemporal adipose layer on axial CT. CT-based morphometry may aid the diagnostic assessment of MMTAH.