Oral Cavity, Pharynx, and Suprahyoid Neck Axial 1
Note the enhancement of the mucosal surfaces of the aerodigestive tract on the lower magnetic resonance (MR) image in Axial 1 after gadolinium contrast administration. The subcutaneous adipose tissue and the adipose planes between the structures in the neck are visible on both the upper pre-contrast T1-weighted MR image and the lower post-contrast T1-weighted MR image.
Oral Cavity, Pharynx, and Suprahyoid Neck Axial 2
An axial image of the nasopharynx at the level of the foramen magnum is visible on typically every brain study. Fluid in the mastoid air cells on one side may indicate a mass obstructing the Eustachian canal opening anterior to the torus tubarius (posterior protuberance of pharyngeal opening of auditory tube). The fossa of Rosenmüller is a blind-ending divot between the torus tubarius and the longus capitis muscle more posteriorly. Asymmetric loss of this fossa may be the first sign of a nasopharyngeal lesion. Malignant spread of a nasopharyngeal carcinoma may first reach the retropharyngeal lymph node. This lymph node is normally less than 8 mm in long axis and located between the longus capitis muscle and the internal carotid artery more posterolaterally.
Oral Cavity, Pharynx, and Suprahyoid Neck Axial 5
Lesions of the head and neck are often most easily detected by loss of normal fat planes. On these T1-weighted precontrast (upper) and postcontrast (lower) MR images, note the fat within the retromolar trigone (retromandibular triangle) located posterior to the third molar. Once a malignancy or infection has reached the parapharyngeal fat located more posteriorly, it has an easy route of spread craniocaudally from the skull base down to the inferior pericardial recess.