Evaluation of Breast Cancer Morphology Using Diffusion-Weighted and Dynamic Contrast-Enhanced MRI: Intermethod and Interobserver Agreement

Background: The capability of diffusion-weighted imaging (DWI) for morphological analysis of breast lesions is underexplored. Purpose: To evaluate the utility of DWI for assessment of morphological features of breast cancer by comparing DWI and dynamic contrast-enhanced (DCE) MRI findings to determine intermethod and interobserver agreement. Study Type: Retrospective. Population: Seventy-eight women with pathohistologically proven breast cancer. Field Strength/Sequence: 1.5T. DWI and DCE images. Assessment: Diffusion-weighted and DCE images were placed in two separate case sets. Three radiologists, blinded to all other information, independently evaluated each case set on two separate occasions. Lesions were interpreted according to the fifth edition of the ACR BI-RADS lexicon. Statistical Analysis: Kappa (κ) statistics were calculated in order to assess intermethod and interobserver agreement. Results: For values that attained statistical significance (P < 0.05), intermethod agreement ranged from fair (κ = 0.22) for nonmass internal patterns to significant (κ = 0.8) for lesion type. On DWI, interobserver agreement varied from fair (κ = 0.34) for mass shape to significant (κ = 0.75) for lesion type. On DCE MRI, interobserver agreement varied from fair (κ = 0.27) for irregular vs. spiculated mass margin to perfect (κ = 1) for circumscribed vs. noncircumscribed mass margin. Data Conclusion: On the whole, there was moderate intermethod agreement. The values of interobserver agreement were mostly similar between DWI and DCE MRI. This suggests that DWI is applicable for morphological assessment of breast cancer, notwithstanding substantially inferior spatial resolution compared to DCE MRI. Level of Evidence: 3. Technical Efficacy: Stage 3. J. Magn. Reson. Imaging 2019;49:1381–1390.