Detection of malignant melanoma with iodine-123 iodoamphetamine.

Iodoamphetamine (IMP) was shown by in vitro assay to have a high uptake by human melanotic melanoma cells, as compared to amelanotic melanoma cells. Eleven patients with proven malignant melanoma (MM) and 3 normal subjects were imaged at 2-4 hr and 16-24 hr after the i.v. injection 5 mCi (185 MBq) of [123I]IMP. One patient had a recurrent tumor that was subsequently shown to be squamous cell carcinoma. The index lesion was not visualized in the three patients with amelanotic melanomas. The index lesion/lesions were visualized in six of the seven other patients, except for 4/16 nodules in one patient. The seventh patient had a large, necrotic melanotic tumor that was not visualized, but an unsuspected lesion in the iliac nodes was detected. Multiple unsuspected lesions were detected in a second patient. While many lesions were seen at 2-4 hr, all lesions (other than a patient with small bowel disease) were seen best at 16-24 hr. No eye uptake was observed in any patient or control subject. Testicular uptake was seen in all males at 16-24 hr. Iodine-123 IMP appears to be a useful agent for the detection and follow-up of patients with melanotic MM.