Differentiating benign and malignant inflammatory breast lesions: Value of T2 weighted and diffusion weighted MR images

Objectives: Benign and malignant inflammatory breast lesions demonstrate similar findings on both T2 weighted imaging (T2WI) and dynamic contrast enhanced (DCE) images. We hypothesized that benign inflammatory lesions might be differentiated form malignancies using a combination of apparent diffusion coefficient (ADC) values derived from diffusion weighted images (DWI) and T2WI. Materials and methods: We retrospectively reviewed 162 patients undergoing breast MRI (T2WI, DWI and DCE images) between 2008 and 2015 who had breast lesions with high T2WI signal intensity (High T2 SI) including 14 benign inflammatory lesions, 69 benign non-inflammatory lesions, 16 malignant inflammatory lesions and 63 malignant non-inflammatory lesions. On the High T2 SI and low T2WI signal intensity (Low T2 SI) areas in these breast lesions, we calculated ADC values from b values of 0 and 1000 s/mm(2). Results: The mean ADC values +/- standard deviation (10(-3) mm(2)/s) of the High T2 SI areas in benign inflammatory, benign non-inflammatory, malignant inflammatory and malignant non-inflammatory breast lesions were 0.75 +/- 0.18, 1.77 +/- 0.33, 2.06 +/- 0.32 and 1.88 +/- 0.41, respectively. Those of the Low T2 SI areas in benign inflammatory, benign non-inflammatory, malignant inflammatory and malignant non-inflammatory lesions were 0.89 +/- 0.15, 1.31 +/- 0.28, 0.87 +/- 0.20 and 0.94 +/- 0.27 respectively. ADC values of High T2 SI areas of the benign inflammatory lesions were significantly lower than those of benign non-inflammatory, malignant inflammatory, and malignant non-inflammatory lesions (p < 0.001). ADC values of Low T2 SI areas in benign inflammatory lesions were not significantly different from those of malignant inflammatory (p = 0.99) or malignant non-inflammatory lesions (p = 0.72). Conclusion: For breast lesions with High T2 SI, segmenting the High T2 SI for ADC mapping distinguishes benign from malignant inflammatory conditions. Using ADC mapping of the Low T2 SI areas will not result in this distinction.