The Role of F18-FDG PET-MRI in Necrotising External Otitis Follow-Up: A Single Centre Experience - Abstract
Purpose of the report: Necrotizing external otitis (NEO) is a rare infectious disease arising from the external auditory canal. Follow-up of NEO is challenging, as MRI signal abnormalities can persist after adequate antibiotic treatment, and persistent/recurrent NEO can be clinically silent. The aim of this study is to investigate the clinical value of F-18-FDG PET-MR in NEO follow-up. In addition, the relation between metabolic activity responses during antibiotic treatment on F-18-FDG PET-MR was observed. Materials and methods: This retrospective database study included patients if they had at least two F18-FDG PET-MRI scans; a baseline scan conducted at time of diagnosis/start of antibiotic treatment, and a post-treatment scan. Maximum SUV (SUVmax) on F18-FDG PET-MRI were measured by a nuclear medicine specialist, and MRI’s were scored by a neuroradiologist. Results: In total, 47 F18-FDG PET-MRI scans of 14 patients diagnosed with NEO were acquired. NEO ears show an average SUVmax on baseline scans of 7.6 ± 2.6, and significantly declined (p<0.001) on post-treatment scans to 2.5 ± 0.8. MRI abnormalities persisted in 86% of NEO patients. None of the patients showed clinical NEO disease recurrence Conclusion: The quantification of SUVmax values on F-18-FDG-PET/MRI can be used in NEO to monitor antibiotic treatment response, while the majority of NEO patients have persistent MRI abnormalities on follow-up imaging. The SUVmax of the affected ear significantly declines during antibiotic therapy, and in absence of clinical symptoms, corresponds with successful treatment.