18F-Fluoride PET/CT Scan for Quantification of Bone Metabolism in the Inner Ear in Patients With Otosclerosis—A Pilot Study

Abstract

In otosclerosis, CT of the temporal bone is used to confirm the diagnosis. Whereas CT is a static diagnostic tool displaying the demineralization caused by otosclerosis, imaging of bone metabolism by (18)F-fluoride PET may provide quantitative information. This could be useful for prognosis and stratification of patients. The aim of this study was to assess (18)F-fluoride activity in patients with otosclerosis and to evaluate its use as a complementary diagnostic tool. All patients with otosclerosis underwent a PET/CT scan. Audiometric data were collected. The severity of otosclerosis was assessed using a recognized radiological classification. The control group consisted of patients who had undergone (18)F-fluoride PET/CT scan for orthopedic purpose. Regions of interest were drawn on PET scans which corresponded to standardized anatomical sites as defined on CT, to measure bone metabolism using standardized uptake values (SUV(max) and SUV(mean)). Group 1 consisted of 11 otosclerosis patients (16 eligible temporal bones) and group 2 consisted of 5 control patients (10 temporal bones). On PET scan, visual assessment of temporal bones with otosclerosis showed increased metabolic activity in the otic capsule in 11/16 cases. The SUV(max) in the entire otic capsule was significantly higher in otosclerosis patients compared to control subjects. Significant differences in SUV(mean) were found between otosclerosis and control subjects in the fenestral and saccule area. Moreover, metabolic activity in these regions significantly correlated with hearing loss and CT classification. (18)F-Fluoride PET scanning using SUV measurements has the potential to be a diagnostic tool in otosclerosis.