Abstract:
To evaluate whole body positron emission tomography/computed tomography (PET/CT) imaging for initial metastatic screening of patients with uveal melanoma.
Sixty six patients with uveal melanoma underwent whole body PET/CT as part of their metastatic work up. Of those patients, PET/CT scans were used as a screening tool for 50 patients at the time of their initial diagnosis. Liver function tests (gamma glutamyl transferase, aspartate amino–transferase, alanine amino–transferase, alkaline phosphatase, lactate dehydrogenase, bilirubin) and a baseline chest x–ray (posterior–anterior and lateral views) were obtained. PET/CT scans were obtained [utilizing intravenous18–Fluoro–2–deoxyglucose (FDG)] and studied for the presence of distant metastases. The standards for reference were further imaging and/or subsequent biopsies.
Fifty patients had PET/CT scans and 2 (4%) patients were found to have distant metastases. The most common sites for metastases were the liver (100%), bone (50%) (Figure) and lymph nodes (50%). Brain and cardiac involvement was present in 1 patient. One patient (50%) had involvement of multiple sites. Liver function tests were normal in both patients. PET/CT showed false positive results in 3 patients (6%) when further evaluated by histopathology and/or additional imaging. In 7 patients (14%) PET/CT detected benign lesions in the bone, lung, lymph nodes, colon and rectum.
PET/CT imaging can be used as a screening tool for the detection and localization of metastatic uveal melanoma. In 2 patients: liver enzyme assays were not as sensitive in identifying hepatic lesions, and PET/CT scanning revealed extra–hepatic metastases. PET/CT imaging showed false positive results in 6% and detected benign lesions in 14% of patients. Though a prospective–comparative trial is necessary to determine if our findings are statistically significant, PET/CT imaging appears to be a more sensitive screening tool for the detection of metastatic disease in patients with uveal melanoma.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • oncology • melanoma