Long-term follow-up of proton irradiated malignant melanoma by glucose-fructose enhanced magnetic resonance imaging.

MR imaging is frequently used to diagnose uveal melanomas due to the characteristic short T2 relaxation time. T2 may be significantly prolonged within 2 h after ingestion of glucose and fructose due to changed water distribution in the melanoma. This method is used to follow melanomas for up to 6 years after proton beam irradiation. In the tumours, T2 was shortened in parallel in all the lesions during the first 9 months. After this, T2 increased only in tumours which showed recurrence. T2 determination and histopathological examination revealed no signs of recurrence in eyes which were enucleated due to neovascular glaucoma. It is concluded that MR imaging performed with carbohydrate loading, registers metabolic changes induced in the tumour, giving this method great validity in the follow-up of choroidal malignant melanoma after irradiation. Eighteen patients treated with proton beam for uveal melanoma at the cyclotron in Uppsala, Sweden, were followed.