Clinical significance of three-dimensional measurement of tumour thickness on magnetic resonance imaging in patients with oral tongue squamous cell carcinoma.

OBJECTIVES: To identify the clinical significance of primary tumour thickness (TT) and its direction in patients with oral tongue squamous cell carcinoma (OTSCC), we measured TT in all axial/coronal/sagittal views on magnetic resonance imaging (MRI) and evaluated their meaning.

METHODS: A total of 53 OTSCC patients were analysed who had undergone preoperative three-dimensional MRI and had been surgically treated. TT measured on axial (mediolateral direction), coronal (superoinferior direction), and sagittal (anteroposterior direction) views was compared to that in pathologic specimens. The association between TT on MRI and other pathologic parameters was also evaluated.

RESULTS: TT on MRI in each plane showed relatively high concordance rates with the histological measurements. TT in all three planes was significantly correlated with lymph node (LN) metastasis. Occult LN metastasis was found in 15 of 39 (38.5%) patients, and the cutoff value of TT in axial/coronal/sagittal MRI predicting occult LN metastasis was 6.7 mm, 7.2 mm, and 12.3 mm, respectively. TT on MRI did not show any significant association with recurrence and survival.

CONCLUSIONS: TT on MRI in all three planes showed relatively high coincidence with TT on histopathology and presented a potential cut-off value as a predictive indicator for occult LN metastasis.

KEY POINTS: Three-dimensional measurement of tumour thickness (TT) is important for oral cancer treatment. Magnetic resonance imaging (MRI) is a useful diagnostic tool for oral cancer. TT on MRI has a high coincidence with TT on histopathology. TT on MRI is a predictive marker for occult lymph node metastasis.