Clinical role of 123I-IMP SPECT for the differential diagnosis of ocular malignant melanoma: a time-course analysis

Abstract

Objective: To evaluate the efficacy of (123)I-IMP single photon emission computed tomography (SPECT) for the diagnosis of ocular malignant melanoma (MM).

Methods: Thirty-eight patients (18 males, 20 females) clinically suspected of having ocular MM were retrospectively examined in this study. The age of patients ranged from 8 to 81 years (mean 55.6 years). Twelve patients were finally diagnosed as having ocular MM. Orbital SPECT images were taken 15 min, 4 h, 24 h and 48 h after intravenous injection of 111-222 MBq (3-6 mCi) (123)I-IMP. (123)I-IMP uptake in the orbital tumor was visually evaluated as-(negative),+/-(equivocal), or+(positive). The uptake index (UI) and increase ratios (IRs) were calculated.

Results: For visual evaluation, the accuracy of (123)I-IMP for the diagnosis of MM was 73.7% (15 min), 81.6% (4 h), 81.6% (24 h) and 86.8% (48 h). When UI and IR were calculated on both the MM and non-MM groups, the UI and IR of the MM group were significantly higher than those of the non-MM group (P<0.001). Moreover, the highest sensitivity (100%) and accuracy (94.7%) were obtained 48 h after (123)I-IMP administration when the cut-off value of UI was defined as 1.90.

Conclusions: This study shows that (123)I-IMP SPECT is useful for the diagnosis of ocular MM. The UI values 48 h after the injection were efficient for the differentiation between MM and non-MM lesions.