Visualizing ocular melanoma using iodine-123-N-(2-diethylaminoethyl)4-iodobenzamide SPECT.

Abstract

Radiolabeled benzamides have recently been introduced for the detection of melanoma. We evaluated the potential clinical applicability of 123I-N-(2-diethylaminoethyl) 4-iodobenzamide ([123I]IDAB) for SPECT imaging of ocular melanoma. Fourteen patients were studied, 10 with or suspected of malignant ocular melanoma and four with ocular naevi. All patients underwent SPECT imaging of the head and whole-body scintigraphy 4-5 hr after injection of 170 MBq [123I]IDAB. A definite tracer hyperfixation was observed in the pathological eye in 9 of 10 (90%) patients with ocular melanoma. The pathological-to-normal eye ratio averaged 1.46 (range 1.07-2.86). The melanoma nature of the scintigraphic lesions was confirmed after enucleation in eight cases and by clinical evolution in two. A false-negative scan was reported in a patient with a small and hypochromic lesion. In patients with ocular naevi, no false-positive scintigrams were documented. Iodine-123-IDAB scintigraphy may contribute significantly to decide about enucleation in cases where some doubt persists with conventional techniques.