QUANTIFICATION OF MELANIN AND IRON CONTENT IN UVEAL MALIGNANT MELANOMAS AND CORRELATION WITH MAGNETIC-RESONANCE IMAGE

Eleven patients with uveal malignant melanomas (MM) were studied by ma gnetic resonance (MR) imaging before enucleation. The MR appearances v aried, but often were different from those previously reported to be c haracteristic of these tumours. Using an image analyser to assess quan titatively the melanin and iron content of each tumour, a wide range o f tumour melanin concentrations was found, but universally low tumour iron concentrations. These values were compared with MR appearances th at were quantified and expressed as contrast to noise ratios. The corr elation between Tl and T2 shortening and increasing melanin content di d not reach statistical significance. There was no correlation between MR appearances and iron content. The theories postulated to explain t he diverse MR appearances of uveal MMs are discussed and variations in tumour melanin content and differences in scanner strengths are sugge sted as the most likely explanations.