Added Clinical Value of 'True' Whole Body 18F-FDG PET/CT Imaging in Patients with Malignant Melanoma
Accurate and reliable staging of disease extent in patients with malignant melanoma is essential to ensure appropriate treatment planning. The detection of occult recurrent or residual malignancy after primary treatment is important to allow for early intervention. FDG PET or PET/CT is indicated for staging, restaging and surveillance of malignant melanoma due to its high sensitivity and specificity for soft-tissue or nodal recurrences and metastases.
To assess the added benefit of scanning lower extremities and skull in addition to 'eyes to thigh’ images in PET/CT evaluation of metastatic melanoma, the reports of whole-body PET/CT scans from January 2006 to December 2007 in patients with melanoma were retrospectively reviewed. PET abnormalities in the brain/scalp and lower extremities were tabulated by location and whether they were 'expected' or 'unexpected'. Findings were correlated with pathology, other imaging and clinical follow-up.
145 PET/CT examinations in 116 patients with melanoma were included. 5 scans showed brain/scalp abnormalities, with only 1 showing unexpected abnormalities. 14 scans showed lower extremity abnormalities, with only 4 showing unexpected abnormalities. In no case was an unexpected isolated malignant lesion identified in the brain/scalp or lower extremities.
In patients with no known or suspected primary or metastatic melanoma involving the head or lower extremities, inclusion of these regions on PET/CT is of low yield and appears to offer little significant additional benefit, as detection of additional metastases in these patients is unlikely to change clinical management. Routine ‘eyes to thighs’ images may be adequate for this subset of patients with melanoma.