ROLE OF HIGH-RESOLUTION MAGNETIC-RESONANCE-IMAGING FOR DIFFERENTIATING MELANIN-CONTAINING SKIN TUMORS

RATIONALE AND OBJECTIVES. The aim of the study was to evaluate the use of high resolution magnetic resonance imaging (MRI) for differentiati on of melanin-containing skin tumors. METHODS. Twenty-seven melanocyti c nevi and 18 malignant melanomas were examined by high resolution MRI , Signal intensities and signal-to-noise (SNR) and contrast-to-noise r atios (CNR) of the tumors were determined in unenhanced (T1, T2, water -suppression, and fat-suppression sequences) and contrast-enhanced ima ges (T1 and fat-suppression sequences), The differences were tested fo r significance by a Wilcoxon test. RESULTS. Malignant melanomas differ ed from melanocytic nevi in that they displayed a higher SNR in T2-wei ghted and unenhanced and contrast-enhanced fat-suppression scans, Mali gnant melanomas exhibited a higher CNR than did benign lesions in unen hanced and contrast-enhanced fat-suppression sequences with dermis as reference tissue (P < 0.05) and in enhanced fat-suppression sequences with subcutis as reference tissue (P < 0.05), CONCLUSIONS. The usefuln ess of SNR and CNR analysis on MRI for the differentiation of malignan t skin tumors from benign skin tumors of the melanin-containing system is limited, Clinical and histologic examinations are, further, the im portant step in evaluation of melanin-containing skin tumors.