Positron emission tomography using F-18-fluorodeoxyglucose in advanced stages of malignant melanoma: A comparison of ultrasonographic and radiological methods of diagnosis

The diagnostic and therapeutic impact and the cost-effectiveness of positro n emission tomography (PET) using F-18-fluorodeoxyglucose (FDG) will depend on the role for which the tests are used. In 68 patients with advanced mal ignant melanoma, original sets of FDG-PET images from various institutes we re compared with findings obtained by ultrasonography, conventional radiolo gy computed tomography (CT) and magnetic resonance imaging. In 22 patients, all examinations were undertaken within 2 weeks and strategies of staging were analysed. In 46 patients, only some of these examinations were perform ed within this time period, and comparison of methods was restricted to the examined organs. The occur ence of metastases, without specifying the numb er of foci, was detected by either conventional staging with CT or by PET i n 20 of 22 patients. None of these patients were up- or down-staged by FDG- PET compared with CT staging. In the 68 patients as a whole, FDG-PET detect ed fewer pulmonary and hepatic metastases and fewer cerebral foci, but more lymph node and bone metastases than conventional radiology or CT. For the detection of lymph node or skeletal metastases, false-positive FDG-PET find ings were taken into account when compared with follow-up data. In advanced melanoma, FDG-PET did not influence the pattern of subsequent diagnostic t esting. Thus, indications for FDG-PET include pre-metastatic melanoma, loca lized lymph node metastases and monitoring of the response to treatment. (( C) 1999 Lippincott Williams & Wilkins).