BACKGROUND: The aim of this study was to analyze the diagnostic usefulnessof dynamic MRI with determination of the coefficient of enhancement rate and the character of tumor enhancement,and to assess both parameters in the differentiation of malignant lesions. MATERIAL/METHODS: The materialconsisted of 45 patients (30 sarcomas, 15 non-malignant lesions), age 16-64 years. MRI was done usingan Elscint 2T unit, gradient echo techniques, apex angle 80 degrees. The repetition time (TR) was 80-200ms, the echo time (TE) was 2-6 ms, 1 excitation; the acquisition time (TA) was 70-80 ms. The coefficientof tissue enhancement rate was calculated in the region of interest, and expressed as percent per second(erc%/s). The limit value of erc%/s was determined. The sensitivity and specificity of MRI were calculatedin the differentiation of malignant tumors. The method of contrast filling of the tumors was assessedin successive phases after administration of gadolinium Gd-DTPA. RESULTS: Dynamic MRI with determinationof the index of tumor enhancement rate is highly sensitive (93%) and specific (73%) in the differentiationof malignant and benign lesions. The usefulness of the assessment of tumor enhancement character wasnot confirmed, since the sensitivity and specificity were 73% and 33%. Dynamic MRI with determinationof erc%/s and tumor enhancement character is highly sensitive (93%) and specific (87%). CONCLUSIONS:Dynamic MRI with determination of erc%/s and tumor enhancement character is the best method for differentialdiagnosis.

Keywords: Adolescent, Magnetic Resonance Imaging, Soft Tissue Neoplasms