Clinical and therapeutic impact of 18F-FDG PET/CT whole-body acquisition including lower limbs in patients with malignant melanoma

International audience; OBJECTIVES: To assess the added benefit of scanning lower limbs in addition to the usual whole-body positron emission tomography/computed tomography (PET/CT) scan in patients with no known or suspected primary or metastatic melanoma involving the lower limbs. MATERIALS AND METHODS: This is a retrospective study of 122 consecutive patients [174 2-[¹⁸F]-fluoro-2-deoxy-D-glucose (FDG) PET/CT] who underwent FDG PET/CT for staging of melanoma at different time points in the course of the disease from October 2005 to February 2009 at the Brest University Hospital. Reports of whole-body PET/CT scans including lower limbs were reviewed. PET/CT abnormalities on the lower extremities were tabulated by location and correlated with pathology, other imaging studies and at least a 6-month clinical follow-up. The usefulness of lower limbs acquisition in clinical management was evaluated according to imagery findings. RESULTS: Among the 174 consecutive PET/CT scans performed in 122 patients, 33 scans in 28 patients highlighted abnormal FDG uptakes considered as equivocal or suggestive of malignancy in the lower limbs. In 28 cases, uptakes were located at once in the lower limbs and in the rest of the body (lung, liver, mediastinal and sub-diaphragmatic lymph nodes, adrenal glands, bone) corresponding to disseminated disease. In five cases, PET/CT uptakes were located only in lower limbs; each pathological uptake corresponded to benign lesions. Lower limbs findings never impacted clinical and therapeutic decision. CONCLUSION: Lower limbs additional PET/CT acquisition seems to offer poor additional benefit with none unexpected lesion detected and routine skull base to upper thigh images might be sufficient for this subset of patients.