Identification of bone lesions on PET/CT imaging: A comparison of PET to CT detection capabilities.

2723 Objectives In cancer patients, the detection of bone metastases has a direct impact on the staging and management of their disease. The purpose of this study is to assess the ability of PET/CT in the detection of bone metastases and to compare the sensitivity of PET to that of CT. Methods 2000 PET/CT reports from January 2013 to November 2014 were retrospectively reviewed for the presence of bone lesions with or without corresponding CT changes in the low dose unenhanced CT portion of PET/CT. A log was kept to record the presence of PET and CT bone lesions. A negative CT recording referred to having no lytic or blastic change on the bone window. The presence or absence of bone metastasis was evaluated based on all available pathological and clinical data. Results Of the 2000 cancer patients’ PET/CT reports reviewed, 146 reported suspected bone lesions (7.3%). Of those 146 scans, 105 (72%) were positive on both PET and CT. The remaining 41 (28%) had PET positive/ CT negative bone lesions. Bone metastasis was confirmed in 38 of the 41 (93%) detected only by PET, which was based on biopsy, imaging or clinical follow-up. The primary malignancies in these 38 patients included: 8 lymphoma, 10 lung, 6 breast, 4 melanoma, 3 head and neck, 2 gastrointestinal, 2 multiple myeloma, and 3 leukemia. Of the remaining 3/41 (7%), one had a negative bone biopsy and 2 had no follow-up. Conclusions The detection of bone metastasis is not uncommon in FDG PET/CT imaging (7.3%). When bone lesions were detected by PET/CT, 72% were positive on both PET and CT. However, PET demonstrated an FDG-avid lesion without a CT abnormality in at least 38/146 (26%) of cases. We conclude that PET is more sensitive than CT in patients with cancer.