Dynamic breast MR imaging: Are signal intensity time course data useful for differential diagnosis of enhancing lesions?

PURPOSE: To assess the relevance of the signal intensity time course for th e differential diagnosis of enhancing lesions in dynamic magnetic resonance (MR) imaging of the breast. MATERIALS AND METHODS: Two hundred sixty-six breast lesions were examined w ith a two-dimensional dynamic MR imaging series and subtraction postprocess ing. Time-signal intensity curves of the lesions were obtained and classifi ed according to their shapes as type I, which was steady enhancement; type II, plateau of signal intensity; or type III, washout of signal intensity. Enhancement rates and curve types of benign and malignant lesions were comp ared. RESULTS: There were 101 malignant and 165 benign lesions. The distribution of curve types for breast cancers was type I, 8.9%; type II, 33.6%; and typ e III, 57.4%. The distribution of curve types for benign lesions was type I , 83.0%; type II, 11.5%; and type III, 5.5%. The distributions proved signi ficantly different (chi(2) = 139.6; P < .001). The diagnostic indices for s ignal intensity time course were sensitivity, 91%; specificity, 83%; and di agnostic accuracy, 86%. The diagnostic indices for the enhancement rate wer e sensitivity, 91%; specificity, 37%; and diagnostic accuracy, 58%. CONCLUSION: The shape of the time-signal intensity curve is an important cr iterion in differentiating benign and malignant enhancing lesions in dynami c breast MR imaging. A type III time course is a strong indicator of malign ancy and is independent of other criteria.