Pre-operative magnetic resonance imaging for evaluating depth of invasion in oral tongue cancer: Precision and predictive value.

BACKGROUND: Accurate evaluation of the depth of invasion (DOI) in oral tongue squamous cell carcinoma (OTSCC) is essential for staging and treatment planning. Magnetic resonance imaging (MRI) is increasingly used as a non-invasive method for preoperative DOI assessment, though further validation against histopathology is needed. AIM: This study aims to assess the precision and predictive value of MRI-derived DOI in preoperative evaluation of oral tongue cancer. METHODS: Thirty-two patients underwent preoperative MRI, providing sufficient power to detect a strong correlation with pathological DOI (pDOI) (80% power, α = 0.05). DOI measurements were obtained from axial and coronal MRI sequences and compared to pDOI from postoperative histopathology. Accuracy of MRI-derived DOI was assessed against tumor staging and pathological parameters. RESULTS: MRI-derived depth of invasion (rDOI) strongly correlated with pDOI, achieving a correlation coefficient of 0.89. MRI showed 81.3% accuracy in DOI-based staging, with high concordance in T1 and T4a tumors, but lower accuracy for intermediate lesions (DOI 5-10 mm). Factors significantly affecting rDOI accuracy included tumor morphology, boundary clarity, size, cervical nodal status, and invasiveness on MRI. ROC analysis demonstrated high predictive value for muscle invasion (optimal rDOI: 7.0 mm), moderate accuracy for perineural invasion (8.6 mm), and good prediction of nodal metastasis (10 mm). However, rDOI had limited sensitivity for detecting lymphovascular invasion. CONCLUSIONS: MRI-based DOI provides a reliable, non-invasive tool for preoperative assessment of OTSCC, with strong correlation to pathological findings. While effective in detecting local invasion and nodal risk, overestimation in intermediate-stage tumors warrants cautious interpretation in treatment-decision.