Imaging characteristics of sublingual gland herniation on CT and MRI.

OBJECTIVES

We investigated the imaging characteristics of sublingual gland herniation (SLH) and its occurrence, using CT and MRI.

METHODS

We retrospectively analysed the imaging characteristics and occurrence of SLH in 969 pairs of CT and MRI.

RESULTS

We identified 335 cases of SLH in 227 patients. None of the 227 patients had symptoms in the sublingual gland (SLG) or SLH areas. The primary imaging characteristic of SLH was presence of a mass-like structure beneath the mylohyoid muscle in the submandibular area on CT or MRI. Subjects with mylohyoid muscle defects had a significantly higher prevalence of SLH compared to those without such defects (r = 0.97, P < .01). A correlation was also found between the size of the mylohyoid muscle defect and the size of SLH (r = 0.43, P < .01). The CT number of SLH was significantly lower than that of the SLG (P < .01), and a correlation was also found between the respective CT numbers of SLH and SLG (r = 0.70, P < .01). On MRI, the internal characteristics of SLH were similar to MR signals of SLG. A correlation was also found between the respective MR signals of SLH and SLG (r = 0.71, P < .01). The apparent diffusion coefficient (ADC) value of SLH was significantly lower than that of SLG (P < .01), and a correlation was also found between the respective ADC values of SLH and SLG (r = 0.59, P < .01). SLH was contiguous to SLG.

CONCLUSIONS

SLH is detected at a relatively high rate on CT and MRI, and accurate imaging is necessary to differentiate them from other mass lesions of the oral floor. SLHs have continuity with and similarity to SLGs, and can be differentiated from other lesions based on their slightly lower CT number and ADC value.