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

Objective. - To assess the added benefit of scanning lower limbs in addition to usual whole-body 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 133 consecutive patients (189 FDG PET/CT) who underwent FDG PET/CT for staging of melanoma at different time points in the course of disease from October 2005 to July 2009 at 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. Results. - Among the 189 consecutive PET/CT scans performed in 133 patients, 34 scans in 29 patients highlighted abnormal FDG uptakes considered as equivocal or suggestive of malignancy on lower limbs. In 29 cases, uptakes were located both on lower limbs and on 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 on 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 appears to offer poor additional benefit with no unexpected solitary lesion detected and routine skull base to upper thigh images may be sufficient for this subset of patients. (authors)