DYNAMIC MR-IMAGING OF THE BREAST COMBINED WITH ANALYSIS OF CONTRAST AGENT KINETICS IN THE DIFFERENTIATION OF PRIMARY BREAST-TUMORS

Objective: To assess dynamic Gd-DTPA-enhanced magnetic resonance (MR) imaging in the diagnosis of primary breast pathology, and to test the hypothesis that analysis of contrast agent kinetics increases specific ity. Methods: Forty-seven women underwent breast MR imaging using thre e-dimensional and dynamic spoiled gradient-recalled sequences, Image i nterpretation was based on the evaluation of lesion conspicuity, signa l intensity, contour and enhancement pattern from the static acquisiti ons, Assessment of contrast kinetics was based on pixel-by-pixel analy sis of the dynamic data, A two-compartment model described by three pa rameters (amplitude of uptake, exchange rate and washout rate), and a three-compartment model described by two parameters (permeability and exchange rate) were used, Regions of interest were drawn for all lesio ns found in the dynamic sections, Mean regional pixel values were calc ulated for each parameter and tested for diagnostic efficacy, Results: Twenty-two malignant and 36 benign lesions were examined, Fibroadenom as accounted for 86% of the benign tumours, Image interpretation had a sensitivity of 0.95 and specificity of 0.86. The fat-suppressed post- contrast images permitted good visualization of the contour and matrix characteristics of fibroadenomas, but all non-fibroadenomatous benign lesions were classified as indeterminate or suspicious, Significant d ifferences were found between benign and malignant lesions in the ampl itude of uptake (P = 0.0008) and exchange rate (P < 0.00005) of the tw o-compartment model, and permeability (P = 0.0001) and exchange rate ( P < 0.00005) of the three-compartment model, However, image interpreta tion was superior to the isolated use of quantitative indices (P = 0.0 2). The most discriminating parameters were the exchange rates of both models, with no significant difference between them, Conclusion: Asse ssment of lesion morphology is essential and probably sufficient for t he differentiation of fibroadenomas from malignant tumours, However, s pecificity of conventional MR imaging may be much lower for other type s of primary benign breast pathology, Analysis of Gd-DTPA kinetics imp roves the specificity obtained using simple enhancement measurements a nd can be used to produce parametric images that provide information a bout lesion heterogeneity, permeability and vascularity.