Intravoxel incoherent motion (IVIM)-derived parameters in diffusion-weighted MRI: Associations with prognostic factors in invasive ductal carcinoma

Purpose: To investigate relationships between intravoxel incoherent motion (IVIM) metrics of invasive ductal carcinoma of the breast and prognostic factors. Materials and Methods: This retrospective study included a total of 82 masses from 72 patients who underwent 3T breast magnetic resonance imaging (MRI) and diffusion-weighted imaging. IVIM metrics of tissue diffusivity (D_slow), pseudodiffusivity (D_fast), and perfusion fraction (D_pf) were measured using histogram analysis for whole lesion volumes. We evaluated relationships between IVIM metrics and prognostic factors or subtypes of invasive ductal carcinoma. Results: The D_slow 50^th, 75^th, and 90^th percentile metrics were reduced in the estrogen receptor (ER)-positive group compared with the ER-negative group (individually, P = 0.044, 0.024, 0.045). Additionally, the D_slow 75^th percentile value was a significant differentiator of histologic grade, tumor subtype, and Ki-67 grouping (individually, P = 0.024, 0.049, 0.016). The D_pf mean, 75^th, 90^th percentile, skewness, and kurtosis metrics were correlated with the size of ductal carcinoma in situ (DCIS) component (individually, P = 0.034, 0.032, 0.027, 0.013, 0.013). Conclusion: The D_slow metrics differentiated between ER-positive and -negative groups, and the D_pf metrics were associated with the size of the DCIS component. Level of Evidence: 4. J. MAGN. RESON. IMAGING 2017;45:1394–1406.