Scintimetric detection of choroidal malignant melanoma with [123I]-5-iodo-2-thiouracil.
[123I]-5-iodo-2-thiouracil (123I-ITU) was evaluated as a radiopharmaceutical for tumor detection in 10 patients with proven choroidal melanoma. Uptake of 123I-ITU was measured with a specially designed single eye probe collimator, 24 h after administration of 123I-ITU. Increased uptake in the tumor-bearing eye as compared to the fellow nontumor bearing eye was found in 7 out of 10 cases when the probe was located 3.5 cm in front of the eye (p less than 0.01). By using a double pinhole collimator tests were positive in 3 out of 10 123I-ITU studies only. Tests with 123I-ITU were compared with 67Ga tests in the same patients. The 67Ga tests with the single eye probe collimator were positive in 6 out 10 cases when the probe was located 6 cm in front of the eye. With the double pinhole collimator tests were positive in 7 out of 10 67Ga studies. It is concluded that 123I-labeled thiouracil is at least as useful as a radiopharmaceutical for ocular melanoma diagnosis as 67Ga-citrate, provided measurements are performed with a single eye probe.
D002830:Choroid Neoplasms / Q000000981:diagnostic imaging*; D005189:False Positive Reactions; D005710:Gallium Radioisotopes; D006801:Humans; D008545:Melanoma / Q000000981:diagnostic imaging*; D011877:Radionuclide Imaging; D013889:Thiouracil / Q000031:analogs & derivatives*
D005710:Gallium Radioisotopes; D013889:Thiouracil; C036667:iodothiouracil