MRI features of retronasopharyngeal space / 中国医学影像技术

ABSTRACT

Objective: To investigate the value of MRI in displaying posterior wall of nasopharynx. Methods: Plain MR scanning were performed in volunteers without head and neck lesions, including axial T1W and high-resolution T2W, and MRI manifestations of the posterior wall of nasopharynx were observed. Five formalin-fixed head and neck of adult cadavers were first evaluated with MRI, and then were frozen, cut into cross-section and stained with HE. The manifestations of the posterior wall of nasopharynx were observed contrastively with MRI and microscopic examination. Results: At the upper level of nasopharynx, the posterior wall of nasopharynx consisted of nasopharyngeal mucosa, fascia, prevertebral muscle and clivus from the outside. The heterogeneous signal was detected in bilateral prevertebral muscle, which was unable to clearly distinguish the posterior boundary of bilateral prevertebral muscles from the basilar clivus. Bilateral anterior edge of the prevertebral muscle was smooth and continuous low signal fascia shadow by gross observation, which was the fascia layer that consisted of the pharyngobasilar fascia, buccopharyngeal fascia, alar fascia and prevertebral fascia at the microscopic level. At the lower 1/2 level of nasopharynx, homogeneous signal was detected in bilateral prevertebral muscles, and the anterior edge was smooth while the shadow of the fascia was ambiguous, where the fibrous membranes of the pharyngeal constrictor turned thin distinctly and the pharyngeal constrictor separated it from the posterior fascia (consisted of buccopharyngeal fascia, alar fascia and prevertebral fascia) at the microscopic level. Furthermore, there was a high signal of the fat strip between posterior edge of bilateral prevertebral muscles and the lower clivus. Conclusion: MRI can clearly show the structures of fascia, prevertebral muscles and fat space in the posterior wall of nasopharynx.