MRI signal changes in the skull base bone after endoscopic nasopharyngectomy for recurrent NPC: A serial study of 9 patients

Purpose: This study was focused on the serial changes in magnetic resonance images (MRI) of the skull-base bone that occur after endoscopic nasopharyngectomy in patients with local recurrent nasopharyngeal carcinoma (rNPC). Materials and methods: Nine patients with histologically proven rNPC were enrolled in this study. Two experienced radiologists independently reviewed all presurgical and postsurgical MR images for each patient. Results: At 36 sites on the skull base, the MRI signal underwent a change after surgery, which took the form of a heterogeneous pattern of hypointense regions with moderate contrast enhancement on T1WI. The onset of changes ranged between 2 weeks and 3 months after surgery. For 21 of the sites, the changes subsided over the course of follow-up, while in 6 they remained stable. At 9 sites, the alteration MRI signal became more pronounced with time. Changes were more common on the homolateral side of the skull base with respect to the recurrent tumor (P < 0.05). The skull-base bone adjacent to the resection boundary had a higher incidence of signal change than nonadjacent areas (P < 0.05). Conclusions: MRI changes in the skull base bone, having a number of distinguishing characteristics, appear to be a common sequel to endoscopic nasopharyngectomy for rNPC