Radiological-pathological correlation of tumour size and depth of invasion of oral squamous cell carcinoma using Dual-Energy CT in comparison to MRI and the impact on T-stage

OBJECTIVE: This study aimed to evaluate Dual-energy CT (DECT) reconstructions for tumour size determination including depth of invasion of primary oral squamous cell carcinoma (OSCC) compared to MRI. METHODS: Retrospectively forty-six consecutive patients with primary OSCC who underwent contrast-enhanced DECT and MRI were included. Tumour size, including maximum diameter (MD), tumour thickness (TT), and depth of invasion (DOI), was assessed using DECT weighted average (WA) images, virtual monoenergetic imaging at 40 keV (VMI), iodine overlay maps (IOM), and MRI, and compared to pathology as the reference standard. RESULTS: DECT DOI showed stronger correlations with pathological DOI (pDOI) than TT or MD (.85 to .88 for DOI compared to .69 to .78 for TT and MD, p<.001 for all). ICC between DECT DOI and pDOI was highest for DECT VMI (.79). MRI measurements resulted in the highest overestimation of TT, MD and DOI. Bland-Altman plots showed acceptable mean differences. T-stage based on rDOI instead of tumour size increased agreement for all imaging. A DECT and MRI cut-off score of 5 mm could accurately discriminate pDOI >5mm achieving a sensitivity of 100%. CONCLUSION: While DECT DOI showed stronger correlations and agreement with pDOI than MRI, both DECT and MRI showed high discriminative ability for pDOI > 5 mm. ADVANCES IN KNOWLEDGE: This study provides new insights into the capability of DECT for radiologically assessing the depth of invasion in OSCC offering a reliable alternative to MRI and potentially improving preoperative tumour diagnosis.