PROSPECTIVE EVALUATION OF 2-[F-18]-2-DEOXY-D-GLUCOSE POSITRON-EMISSION-TOMOGRAPHY IN STAGING OF REGIONAL LYMPH-NODES IN PATIENTS WITH CUTANEOUS MALIGNANT-MELANOMA

Purpose: To assess prospectively the accuracy of 2-[F-18]-2-deoxy-D-gl ucose positron emission tomography (FDG-PET) for predicting regional n ode involvement in cutaneous malignant melanoma (CMM). Patients and Me thods: Twenty-three patients with CMM (primary lesions > 1.5 mm thick) scheduled for lymph node dissection (LND) were preoperatively studied with FDG-PET. Thirteen patients underwent therapeutic LND of 14 node basins, while nine patients had elective LND of 10 node basins. Medica l problems precluded surgery in one patient. Two observers unaware of the clinical node status-apart from whether a recent surgical scar was present-read attenuation-corrected reconstructed transverse images ac quired between 50 and 60 minutes after injection. Intensity of FDG upt ake was scored as 0 to 3 + on a semiquantitative four-point scale: 0, no uptake; 1 +, faint; 2 +, moderate; and 3 +, intense uptake. A node group was considered positive on FDG-PET if it contained at least one focus of FDG uptake of greater than or equal to 2+ intensity. Histopat hologic examination of the 24 dissected node groups served as a refere nce. Results: Considering regional node basins, PET imaging demonstrat ed 11 tree-positive (TP), 10 true-negative (TN), two false-negative (F N), and one false-positive (FP) result, for an overall accuracy of 88% . Histopathologic from one FN case showed seven malignant cells in a m arginal node sinus. The FP was due to reactive changes postbiopsy. In one patient, clinically involved lymph nodes were correctly categorize d TN by PET. At least four additional 2 + foci seen outside the dissec ted regions on PET may represent metastases and are being monitored. C onclusion: FDG-PET accurately predicted regional node status in 88% of CMM cases. The failure to detect micrometastatic disease may be due t o the limitations of the imaging equipment and technique used here. (C ) 1998 by American Society of Clinical Oncology.