Comparison of computed tomographic and pathological depth of invasion in lip squamous cell carcinomas

Akın Gündoğdu, R. Comparison of Computed Tomographic and Pathological Depth of Invasion in Lip Squamous Cell Carcinomas, Medical Specialty Thesis, Department of Radiology, Faculty of Medicine, Eskişehir Osmangazi University, Eskişehir, 2025. The aim of this study is to investigate the correlation between radiological depth of invasion (rDOI), measured by computed tomography (CT), and pathological depth of invasion (pDOI) in patients diagnosed with lip squamous cell carcinoma (SCC). In addition, intra- and interobserver agreement were assessed, and the diagnostic accuracy of CT was evaluated in terms of tumor thickness (TT), maximum tumor diameter, tumor density, and lymph node parameters. A retrospective review was conducted on 101 patients diagnosed with lip SCC between January 2010 and April 2024. Among them, 72 patients with available preoperative neck CT scans were evaluated. Twenty-one patients were excluded due to insufficient image quality, presence of artifacts, or inability to identify the primary lesion, resulting in a final study cohort of 51 patients. CT measurements were independently performed twice by Observer-1 (a radiology resident) and Observer-2 (a senior radiologist specialized in head and neck imaging). Maximum tumor diameter, tumor density, TT, rDOI, and lymph node size and density were recorded. In 27 patients who underwent lymph node dissection, CT findings were compared with histopathological results. A significant correlation was observed between rDOI and pDOI (r=0.685 for Observer 1 and r=0.781 for Observer 2; p<0.001). Measurements of TT and maximum tumor diameter also showed high concordance with pathological data. Inter- and intraobserver correlation coefficients generally ranged from good to excellent. The detectability of lymph node metastases by CT was found to be high; however, reactive lymph nodes may lead to false-positive interpretations. No statistically significant difference was observed between the density values of metastatic and reactive lymph nodes. The agreement between CT-derived data and pathological findings supports the effective role of CT in diagnostic and therapeutic planning. Key Words: Lip cancer, Computed tomography, Depth of invasion, Tumor thickness, Lymph node metastasis, Radiologic concordance