Diffusion-weighted magnetic resonance imaging and ultrasound evaluation of choroideal melanomas after proton-beam therapy

PURPOSE: This study was undertaken to compare the ultrasound and magnetic resonance imaging parameters of ocular melanoma and to assess their variation after proton-beam therapy. MATERIALS AND METHODS: Fifteen choroidal melanoma patients treated with proton-beam therapy were enroled in the study. All patients underwent ophthalmologic evaluations, ultrasound, conventional magnetic resonance (MR) imaging and diffusion-weighted MR imaging before the start of therapy and 3 and 6 months after therapy. Basal diameters, thickness, internal reflectivity, tumour volumes and apparent diffusion coefficient (ADC) values of ocular melanomas were measured at each examination. Correlations between internal reflectivity and ADC were investigated. RESULTS: No significant changes were seen in tumour diameters and tumour height as assessed by B-scan and A-scan, respectively. Significant increase in mean tumour internal reflectivity was detected at 6 months (baseline 35 % ± 11; 6 months 48 % ± 8, Tukey-Kramer p = 0.005). On MRI, compared to baseline (mean 547 ± 262 mm(3)), a significant reduction in volume was seen at 6 months (Tukey-Kramer p = 0.045) (mean volume 339 ± 170 mm(3), mean reduction 38 %). A significant increase in ADC (baseline 1,002 ± 109 mm(2)/s) was detected both at 3 and 6 months after proton therapy (respectively, 1,454 ± 90 and 1,833 ± 261 mm(2)/s, both p < 0.001). CONCLUSIONS: By MRI, in particular by ADC assessment, it is possible to detect early variations in melanoma treated by proton-beam therapy. This examination could be used together with ultrasound in the follow-up of this treatment.