Multi b-value Reverse Polarity Gradient Distortion Correction for Breast Diffusion-Weighted MRI

Motivation: DW-MRI holds great potential in improving specificity in breast cancer screening (BCS). This technique uses Echo-Planar imaging (EPI) and is sensitive to distortion due to spatial magnetic inhomogeneity. Correcting such distortion is key, especially when evaluating quantitative biomarkers. Goal(s): To study multi b-value Reverse Polarity Gradient (mRPG), originally developed for prostate DWI (abstract #4789), in comparison to standard RPG and FSL topup. Approach: A breast phantom scan and a BCS patient dataset were distortion corrected with the three methods. Results: mRPG showed better performance than RPG and topup, especially in ADC maps where they yield a misleading improvement of EPI distortions. Impact: mRPG demonstrated improved performance compared to RPG and topup in correcting distortions. Normalizing DWI volumes across b-values eliminates intensity changes resulting from distortions and solves overfitting issue where Jacobian intensity correction (JIC) makes up for underestimation of tissue displacement.