FDG-PET/CT for diagnosis and follow-up of necrotizing (malignant) external otitis

Objective: Imaging is important for the diagnosis and follow-up of necrotizing external otitis (NEO). The best imaging modality is controversy. To suggest 2-deoxy-2-[fluorine-18] fluoro-D-glucose-positron emission tomography/computed tomography (18F-FDG-PET/CT) as an alternative to technetium-99m and gallium-67 scans for diagnosis and assessment of response to treatment for patients with NEO.

Study design: Case series.

Methods: Tertiary referral center. From 2013 through 2017, 12 patients were diagnosed with NEO based on clinical features and positive FDG uptake within the temporal bone on PET/CT. Mean age was 74 ± 11.5; 83% of the patients were male; and 83% had diabetes.

Results: PET/CT scans were reviewed independently by two nuclear medicine specialists. Imaging located osteomyelitis in external ear canal, mastoid, temporomandibular joint, and nasopharyngeal region (100%, 50%, 16%, 8%, respectively). Mean follow-up was 16 months. Eight patients (67%) underwent a second PET/CT scan after active otitis resolved and after at least 6 weeks of antibiotic treatment. The scan demonstrated no or substantially reduced FDG uptake and treatment was stopped. The patients had no NEO symptoms at the end of follow-up. One patient had significant uptake, and antibiotic treatment was continued until a third scan demonstrated no FDG uptake. Two patients died before the second PET/CT, and two were lost to follow-up.

Conclusion: 18F-FDG-PET/CT is a reliable imaging modality for diagnosis, disease localization, and decision making regarding treatment cessation. 18F-FDG-PET/CT should be considered as the imaging modality of choice for initial diagnosis and follow-up in NEO patients. Larger, controlled studies are warranted.

Level of evidence: 4 Laryngoscope, 129:961-966, 2019.