Nasopharynx on Cone-beam Computed Tomography

Nasopharyngeal carcinoma (NPC) is endemic in Asians and North Africans. Radiologically it is first identified as asymmetry of the Fossa of Rosenmüller (FR) in the nasopharynx, which is also visible on the cone-beam computed tomography (CBCT).

Eighty three consecutive CBCTs including the whole nasopharynx (10 × 10 cm and 10 × 5 cm fields-of-view (FOVs)) of 28 males and 55 females. The CBCTs and the prints of their air-filled pharynxes were reviewed and assigned to one of Takasugi's 3 types: Type A, no FR; Type B, some FR; and Type C, full and open FR.

The Types A/B/C were 12/11/5 for males and 10/22/23 for females, respectively. Type C was more common in females. Nasopharynx shape on CBCT appeared tadpole-shaped, not cuboidal for the 10 × 10 FOVs, revealing the main difference between medical imaging of the supine patient and dental CBCT of the vertical patient.

The nasopharynx, an important site of malignancies, is prominently displayed on medium-to-large FOV CBCT. The minority of CBCTs which display asymmetry, particularly the Fossa of Rosenmüller, is easily recognised by dentists. To avoid undue referral of false positives, care should also be taken with regard to the clinical history and examination of the neck, especially for lymphadenopathy.