Prevalence of Clinically Significant Extraosseous Findings on Unenhanced CT Portions of 18F-Fluoride PET/CT Bone Scans

OBJECTIVE Due to the frequently interrupted supply of (99m)Tc-methylene diphosphonate, the use of ¹⁸F-fluoride positron emission tomography (PET)/computed tomography (CT) has become more popular. The study aims to determine the percentage of extraosseous findings from the unenhanced CT portion of F ¹⁸F-fluoride PET/CT scans. MATERIALS AND METHODS We retrospectively collected ¹⁸F-fluoride PET/CT studies between March 2010 and February 2011. The unenhanced CT portions of ¹⁸F-fluoride PET/CT were reviewed for each patient. Significant extraosseous findings related to malignancy from the unenhanced CT were recorded. RESULTS A total of 158 patients (110 females, 48 males) were included in the study. Clinically significant extraosseous findings from the unenhanced CT were found in 43 patients (27.2%). Previously unknown extraosseous findings were identified in 17 patients (10.8%) after a review of the ¹⁸F-fluoride PET/CT scan results. Most of the extraosseous findings were small pulmonary metastases or enlarged metastatic lymph nodes. CONCLUSION It is not rare to identify new clinically significant extraosseous findings from the unenhanced CT of ¹⁸F-fluoride PET/CT studies. Therefore the clinical management of patients may be altered by the results, and a careful review of the unenhanced CT portion of ¹⁸F-fluoride PET/CT is mandatory.