Evaluation of Factors Affecting Depth of Invasion Measurement in Tongue Squmous Cell Carcinoma Using Intraoral Ultrasonography

OBJECTIVE: Intraoral ultrasonography (US) is known for its high accuracy in evaluating the depth of invasion (DOI) in tongue squamous cell carcinoma (SCC). However, measurement discrepancies, such as overestimation or underestimation, can occur in certain cases. This study aimed to identify factors affecting the measurement accuracy of intraoral US. METHODS: A total of 96 cases were included in this study. Patients who underwent imaging diagnosis for primary tongue SCC by oral and maxillofacial radiologists, followed by surgical resection by oral surgeons at our institution between April 2014 and March 2022, were included in the study. Cases were classified according to their clinical and histopathological characteristics, including clinical growth pattern, maximum pathological tumor diameter, pathological T classification, and pattern of invasion (Yamamoto-Kohama (YK) classification). Measurement accuracy was evaluated using Spearman's rank correlation coefficient and Bland-Altman analysis. RESULTS: A total of 76 cases were analyzed. Intraoral US demonstrated high diagnostic accuracy across various tumor characteristics. However, greater DOI and larger maximum tumor diameter were associated with increased variability in measurements. Exophytic lesions were more likely to be overestimated, whereas lesions with diffuse infiltration tended to be underestimated. CONCLUSION: Although intraoral US provides high accuracy in the preoperative evaluation of tongue SCC, clinicians should be aware of specific tumor characteristics that may influence measurement precision, leading to potential overestimation or underestimation.