Quantitative Diffusion-Weighted Imaging as an Adjunct to Conventional Breast MRI for Improved Positive Predictive Value

TLDR

Overlap in ADC values between benign and malignant breast lesions necessitates validation of these findings in larger studies. The study investigates whether adding diffusion‑weighted imaging to dynamic contrast‑enhanced MRI can improve the positive predictive value of breast MRI. DWI was acquired during clinical breast MRI at b = 0 and 600 s/mm², and apparent diffusion coefficient values were compared between benign and malignant lesions to calculate PPV for DCE‑MRI alone and for DCE‑MRI plus DWI using an ADC threshold. In 83 suspicious lesions (52 benign, 31 malignant), malignant lesions had lower mean ADC than benign lesions, and applying an ADC threshold of 1.81 × 10⁻³ mm²/s increased PPV from 37 % to 47 %, potentially avoiding biopsy in 33 % of benign lesions without missing cancers, with greater benefit for smaller lesions.

Abstract

The purpose of our study was to investigate whether adding diffusion-weighted imaging (DWI) to dynamic contrast-enhanced MRI (DCE-MRI) could improve the positive predictive value (PPV) of breast MRI.The retrospective study included 70 women with 83 suspicious breast lesions on DCE-MRI (BI-RADS 4 or 5) who underwent subsequent biopsy. DWI was acquired during clinical breast MRI using b = 0 and 600 s/mm(2). Apparent diffusion coefficient (ADC) values were compared for benign and malignant lesions. PPV was calculated for DCE-MRI alone (based on biopsy recommendations) and DCE-MRI plus DWI (adding an ADC threshold) for the same set of lesions. Results were further compared by lesion type (mass, nonmasslike enhancement) and size.Of the 83 suspicious lesions, 52 were benign and 31 were malignant (11 ductal carcinoma in situ [DCIS], 20 invasive carcinoma). Both DCIS (mean ADC, 1.31 +/- 0.24 x 10(-3) mm(2)/s) and invasive carcinoma (mean ADC, 1.29 +/- 0.29 x 10(-3) mm(2)/s) exhibited lower mean ADC than benign lesions (1.70 +/- 0.44 x 10(-3) mm(2)/s, p < 0.001). Applying an ADC threshold of 1.81 x 10(-3) mm(2)/s for 100% sensitivity produced a PPV of 47% versus 37% for DCE-MRI alone, which would have avoided biopsy for 33% (17/52) of benign lesions without missing any cancers. DWI increased PPV similarly for masses and nonmasslike enhancement and preferentially improved PPV for smaller (< or = 1 cm) versus larger lesions.DWI shows potential for improving the PPV of breast MRI for lesions of varied types and sizes. However, considerable overlap in ADC of benign and malignant lesions necessitates validation of these findings in larger studies.