Abstract:
To evaluate ability of Fluorine–18 Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography (FDG–PET/CT) scan to visualize primary uveal melanoma and to evaluate the tumor characteristics that correlate with tumor identification. FDG is a glucose analogue that measures metabolic activity.
Prospective, consecutive case–series of 8 patients. All patients were clinically diagnosed with primary uveal melanoma, and subsequently underwent whole body FDG–PET/CT scan prior to treatment on the Siemens Biograph16 system. The PET scanner was capable of 4.5 ns coincidence resolving time, 400–650 keV energy window and had 162 nm axial field of view. 4 eyes were enucleated and histopathologic correlation with imaging findings was also undertaken.
Primary uveal melanoma could be detected with FDG–PET/CT scan in 5 of 8 (63%) patients. The maximum standardized uptake value (SUV) ranged from 3.5 to 6.1. The detection of uveal melanoma was related to tumor size. Tumors that were at least 16 mm in diameter, 4.5 mm in height, 81 mm2 in scleral contact area, or 1070 mm3 volume were consistently visualized. All 4 enucleated eyes showed mixed cell type and 3 of these lesions were visualized by FDG–PET/CT scan.
Primary uveal melanoma can be visualized by FDG–PET/CT scan. Larger tumors were readily visualized. FDG–PET/CT is a functional scan that detects tumor viability. Therefore, it may have potential in evaluating tumor response to conservative therapies.
Keywords: oncology • melanoma • imaging/image analysis: clinical