Diffusion-Weighted MRI: Association Between Patient Characteristics and Apparent Diffusion Coefficients of Normal Breast Fibroglandular Tissue at 3 T

Abstract

OBJECTIVE To assess associations between patient characteristics and apparent diffusion coefficient (ADC) values of normal breast fibroglandular tissue on diffusion-weighted imaging (DWI) at 3 tesla. MATERIALS and METHODS The retrospective study included 103 women with negative bilateral findings on 3T breast MR examinations (BI-RADS 1). DWI was acquired during clinical breast MRI scans using b = 0, 800 s/mm2. Mean ADC of normal breast fibroglandular tissue was calculated for each breast using a semi-automated software tool in which parenchyma pixels were selected by interactive thresholding of the b=0 s/mm2 image to exclude fat. Intrasubject right and left breast ADC values were compared and averaged together to evaluate the association of mean breast ADC with age, mammographic breast density and background parenchymal enhancement (BPE). RESULTS Overall mean breast ADC was 1.62±0.30 ×10−3mm2/s. Intrasubject right and left breast ADC measurements were highly correlated (R2=0.89, p<0.0001). Increased breast density was strongly associated with increased ADC (p=<0.0001). Age and BPE were not associated with ADC. CONCLUSION Normal breast parenchymal ADC values increase with mammographic density, but are independent of age and BPE. Since breast malignancies have been shown to have low ADC values, DWI may be particularly valuable in women with dense breasts due to greater lesion to normal tissue contrast.

Diffusion tensor imaging in the normal breast: influences of fibroglandular tissue composition and background parenchymal enhancement

“…This supports our hypothesis that the reason other DTI parameters do not show differences in our study among the BPE groups is that they are not as sensitive to subtle differences in tissue architecture. Previous work using DWI showed no differences in ADC based on BPE consistent with what we found with our DTI-derived ADC [15]. …”

“…This previous study was limited by small sample size and evaluated diffusion weighted imaging rather than diffusion tensor imaging. McDonald and colleagues also evaluated ADC in normal tissue using diffusion weighted imaging rather than DTI and found ADC values to increase with increased breast density [15]. Another major difference from our analysis is that previous evaluation of DWI in normal breasts grouped patients by density which is a mammographic assessment rather than by FGT as seen on MRI.…”

Diffusion-Weighted Breast Magnetic Resonance Imaging

“…To perform semi-automated ADC measurements, a software algorithm was developed that allowed the reader to dynamically adjust the signal threshold on the DW image for lesion measures to mask out voxels exhibiting signal lower than the specified threshold 11 . This allowed the reader to subjectively exclude normal fibroglandular and/or adipose tissue adjacent to the lesion in real time and prior to drawing an ROI.…”

Assessment and quantification of sources of variability in breast apparent diffusion coefficient (ADC) measurements at diffusion weighted imaging

“…Whereas some authors report that early changes in ADC values predict response before significant changes in tumor size occur [1,2,8], others have found no such relationship [3]. This may be partially attributable to the heterogeneity of the studies and indeed of the subjects [9]. However, the lack of standardization of DWI parameters and a uniform method of interpretation [10] may also be a contributory factor in the under-utilization of DWI.…”