Arrow - the anatomically blocked duct area caused by the calculi.
Differential diagnosis includes ranula, plunging ranula, dermoid cyst, epidermoid cyst, haemangioma, and lymphangioma. Examine the submental and submandibular regions for evidence of swelling if any (can be symmerical, asymmetric, or unilateral). Imaging delineate the anatomical boundaries and extent of lesion and helps in the planning the surgical approach.
Figure shows diffuse submental swelling (+) which extends to the anterior border of submandibular fossa and encroaching hyoid bone posteriorly.