Characterization of breast masses as benign or malignant at 3.0T MRI with whole‐lesion histogram analysis of the apparent diffusion coefficient

PurposeTo investigate the utility of whole-lesion apparent diffusion coefficient (ADC) histogram analysis in capturing breast lesion heterogeneity and determine which ADC metric may help best differentiate benign from malignant breast mass lesions at 3.0T magnetic resonance imaging (MRI). Materials and MethodsWe retrospectively included 101 women with breast mass lesions (benign:malignant=36:65) who underwent 3.0T diffusion-weighted imaging (DWI) and subsequently had histopathologic confirmation. ADC histogram parameters, including the mean, minimum, maximum, 10th/25th/50th/75th/90th percentile, skewness, kurtosis, and entropy ADCs, were derived for the whole-lesion volume in each patient. Mann-Whitney U-test, univariate and multivariate logistic regression, area under the receiver-operating characteristic curve (A(z)), intraclass correlation coefficient (ICC), and Bland-Altman test were used for statistical analysis. ResultsMean, minimum, maximum, and 10th/25th/50th/75th/90th percentile ADCs were significantly lower (all P < 0.0001), while skewness and entropy ADCs were significantly higher (P < 0.001 and P=0.001, respectively) in malignant lesions compared with benign ones. The A(z) values of minimum and 25th percentile ADCs were significantly higher than that of mean ADC (P=0.0194 and P=0.0154, respectively) or that of median ADC (P=0.0300 and P=0.0401, respectively), indicating that minimum and 25th percentile ADCs may be more accurate for lesion discrimination. Multivariate logistic regression showed that the minimum ADC was the unique independent predictor of breast malignancy. Minimum and 25th percentile ADCs had excellent interobserver agreement (ICC=0.943 and 0.989, respectively; narrow width of 95% limits of agreement). ConclusionThese results suggest that whole-lesion ADC histogram analysis may facilitate the differentiation between benign and malignant breast mass lesions. J. Magn. Reson. Imaging 2016;43:894-902