The value of whole body (18) fluorodeoxyglucose (FDG) positron emission tomography (PET)/ computed tomography (CT) and abdominal ultrasound in staging of patients with uveal melanoma

Abstract

Purpose: To determine the value of whole body (18) fluorodeoxyglucose (FDG) positron emission tomography (PET)/ computed tomography (CT) and abdominal ultrasound in staging of patients with uveal melanoma.

Methods: From January 2012 patients with uveal malignant melanoma over 4 mm in thickness, were staged with whole body (18) fluorodeoxyglucose (FDG) PET/CT and abdominal ultrasound. The incidence and location of metastatic disease at diagnosis was recorded. The imaging findings were compared.

Results: 108 patients had a whole body FDG PET/CT and abdominal ultrasound at primary diagnosis. 3 patients (2.8%) were found to have metastatic disease. All 3 had liver metastases, confirmed with biopsy in only one case. 1 of 3 had additional extrahepatic widespread metastases in the lungs, lymph nodes and bone seen on whole body FDG PET/CT. In the 3 patients with metastatic disease, the liver findings using both imaging techniques were consistent in one patient. In the second case abdominal ultrasound misdiagnosed metastatic disease as liver cysts; however, FDG PET/CT revealed several foci of intense metabolic activity in both lobes of the liver. In the third case, PET/CT missed the presence of liver metastases as no metabolic activity was detected, however a hypodense liver lesion was identified on abdominal ultrasound. An abdominal CT scan with contrast confirmed the presence of an enlarging liver metastasis. PET/CT identified second primary malignancies in 9 patients (8.3%) and incidental extrahepatic pathology in another 9 patients (8.1%). Coincidental liver findings, such as fatty liver and haemangiomata, were seen in 20 patients (18.5%) using abdominal ultrasound but only 4 (3.7%) using whole body PET/CT.

Conclusions: Whole body PET/CT and abdominal ultrasound complement each other in the staging of uveal melanoma. PET/CT is useful to detect extrahepatic disease including widespread metastases and other primary malignancies. The metabolic activity of uveal melanoma metastases is variable. Abdominal ultrasound provides more detailed description of the liver and detected an abnormality in all 3 cases with liver metastases.

Keywords: 744 tumors • 745 uvea • 550 imaging/image analysis: clinical