CT appearances of normal and obstructed submandibular duct.

CT scans of 40 patients without pathology in the floor of the mouth or the submandibular glands were reviewed. Intraglandular ducts were visualized in 27 and extraglandular ducts in 3 patients. The CT appearances of dilated submandibular ducts are described in 4 patients with proven causes of obstruction. Widening of the narrow gutter between the mylohyoid and hyoglossus muscles in one scan level is a prominent feature. An intra- or extraglandular duct diameter of 3 mm or more indicates possible obstruction, and the CT images should be scrutinized to reveal the cause.