Katsuhiko Kato MD, Presenter: Nothing to Disclose

Shinji Abe RT, Abstract Co-Author: Nothing to Disclose

Takashi Nihashi MD,PhD, Abstract Co-Author: Nothing to Disclose

Mitsuru Ikeda MD, Abstract Co-Author: Nothing to Disclose

Hiroko Terasaki MD,PhD, Abstract Co-Author: Nothing to Disclose

Shinji Naganawa MD, Abstract Co-Author: Nothing to Disclose

I-123 IMP SPECT is a sensitive and accurate method for the detection of uveal malignant melanoma, whereas the efficacy of F18 -FDG PET for this purpose is low due to a high incidence of false negative results (Kato K, et al. J Nucl Med. 2006;47:404-409). The efficacy of F-18 Dopa PET/CT for detection of uveal malignant melanoma is unknown. The purpose of this study is to compare the efficacy of I-123 IMP SPECT, F-18 FDG PET/CT, and F-18 Dopa PET/CT for detection of uveal malignant melanoma.

Seven patients with suspected uveal malignant melanoma were examined by I-123 IMP SPECT, F-18 FDG-PET/CT, and F-18 Dopa PET/CT. I-123 IMP SPECT was performed 24 hours after intravenous administration of I-123 IMP using a gamma camera (Symbia; Siemens, E.com Toshiba) with LEHR Fan-beam collimator. F-18 FDG-PET/CT and F-18 Dopa PET/CT was performed 60 minutes after intravenous administration of F-18 FDG using a PET/CT camera (Biograph, Siemens).

One case was positive in F-18 FDG PET/CT, whereas 4 cases were positive in I-123 IMP SPECT and F-18 Dopa PET/CT. In two cases which showed negative results with all these three examinations, there was no uveal melanoma lesion. One case is positive in I-123 IMP SPECT and in F-18 Dopa PET/CT, respectively, and these two cases were negative in the other two examinations; and in these two cases there were uveal malignant melanoma. In the cases which showed positive results with all these three examinations, the tumor diameter was longer than 1cm. On the other hand, the tumors with a diameter less than 1cm exhibited positive results in both I-123 IMP SPECT and F-18 Dopa PET/CT but negative results in F-18 FDG PET/CT. I-123 IMP SPECT seems to show higher tracer accumulation than F-18 Dopa PET/CT.

Uveal malignant melanoma with a diameter longer than 1cm exhibited positive results in all of I-123 IMP SPECT, F-18 FDG PET/CT, and F-18 Dopa PET/CT. The tumors with a diameter less than 1cm exhibited positive results in both I-123 IMP SPECT and F-18 Dopa PET/CT but negative results in F-18 FDG PET/CT. I-123 IMP SPECT seems to show higher accumulation than F-18 Dopa PET/CT in detecting uveal malignant melanoma with a diameter shorter than 1cm.

F-18 FDG PET/CT is nearly equal to I-123 IMP SPECT in detecting uveal malignant melanoma and both are recommended for the diagnosis of such lesions.

Kato, K, Abe, S, Nihashi, T, Ikeda, M, Terasaki, H, Naganawa, S, Comparison of I-123 IMP SPECT, F-18 FDG PET/CT, and F-18 Dopa PET/CT in Detection of Uveal Malignant Melanoma.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8007153.html