Fluor-18-fluorodeoxyglucose positron emission tomography (FGD-PET) in malignant melanoma - Diagnostic comparison with conventional imaging methods

Purpose: To assess the diagnostic value of fluor-18-fluorodeoxyglucose posi tron emission tomography (FDG-PET) in screening for melanoma metastases. Material and Methods: The case records of 94 melanoma patients who had been examined by whole-body FDG-PET between 1995 and 1999 were evaluated retros pectively. Forty patients showed evidence of lymphogenous and 42 of hematog enous metastasis. The maximal interval between PET and the diagnostic proce dure under comparison was 2 weeks. Confirmation of the findings was based o n histology or the clinical or radiological course. Results: In 24 patients, all diagnostic examinations including CT had been performed within 2 weeks from PET. In no case did PET change the staging. I n 13 patients, PET agreed with morphological diagnosis in the number of met astatically invaded organs. This included 3 patients without metastases. Th e estimated number of organs invaded by metastases was higher with PET in 5 patients and higher with morphological imaging techniques in 6 patients. A mong the PET findings with higher or equivocal counts of organs with metast ases there were 2 confirmed false-positive findings. Conclusion: In a selected patient population, FDG-PET was found to be infer ior to CT for diagnosing lung and liver metastases. The supplementary use o f FDG-PET is not generally of value once metastasis has been established.