Non-Mass Enhancement of Breast MRI: The Comparison of Benign and Malignant Pathological Diagnosis and Association of Internal Enhancement Pattern and Distribution with Breast Cancer Molecular Sub-Types

Abstract

Objective: The aim of our study is to investigate the distribution of lesions (focal, linear, segmental, regional, multiple regions, diffuse) and internal enhancement patterns (IEP) (homogeneous, heterogeneous, clumped, clustered ring) between benign and malignant type of NME and to evaluate the difference between Ki-67 and molecular subtypes (Luminal A, Luminal B, Basal-like, and HER2(+)) in malignant group.
 Methods: A total of 923 women who underwent routine breast MRI between January 2015 and May 2018 were retrospectively reviewed. 88 MR images were included in the study. Histopathological results were 46 benign and 35 malignant lesions. We compared the distribution and IEPs between benign and malignant type of NME. In the malignant group, distribution and IEPs of different molecular subtypes and Ki-67 values were compared. 
 Results: Clustered ring internal enhancement were significantly associated with malignancy, while focal distribution and homogeneous enhancement pattern were associated with benignancy. A binomial logistic regression model explained 52.4% of the variance in benign-malignant status and correctly classified 77.3% of cases. Model sensitivity was 74.3%, specificity was 79.2%, positive predictive value was 70.2% and negative predictive value was 82.3%. There were not statistically significant differences in either distribution type of lesions or IEPs between molecular subtypes of malignant NME with different Ki-67 values.
 Conclusion: 3-T MRI findings of focal distribution and homogeneous enhancement pattern were found to be a significant predictor of benign NME. Clustered ring enhancement can predict the probability of malignancy for non-mass like enhancement lesions.