BREAST IMAGING D iffusion-weighted imaging (DWI) measures the apparent diffusion coefficient (ADC) of tissue, which is often lower because of cancer. There is growing interest in the use of DWI for breast cancer imaging for screening, disease characterization, and monitoring treatment response (1). DWI is typically acquired by using single-shot spin-echo (SE) echo-planar imaging, which faces several challenges that are often exacerbated in breast imaging because of the large field of view, adipose signal, and respiratory motion that alters the B 0 field. Standard breast DWI has low spatial resolution, large geometric distortions, chemical shift artifacts, and Nyquist ghost artifacts, which can limit its clinical value. Higher spatial resolution may also enable the use of DWI for additional analyses, including minimum ADC, DWI radiomics, histogram analysis, and rim sign (2,3).Several strategies to improve the image quality of SE echo-planar imaging in breast DWI have been explored, including readout segmentation (RS) (4-7), reduced field of view (8,9), and multiband encoding in the phase encoding direction (10). A proposed strategy uses simultaneous multislice (SMS) imaging (11-13) to improve image quality in breast DWI (14-16). Because the SMS potential is greater in the right-to-left directions based on the coil geometry, this approach acquires sagittal images with aggressive SMS to cover a large volume with many thin slices. The images are axially reformatted (AR) for interpretation, according to standard clinical practice. Thus, the axial images are encoded Purpose: To compare the resolution and image quality of standard SE echo-planar imaging DWI with two high-spatial-resolution alternatives, RS echo-planar and AR-SMS imaging, for breast imaging. Materials and Methods:In a prospective study (2016-2018), three 5-minute DWI protocols were acquired at 3.0 T, including standard SE echo-planar imaging, RS echo-planar imaging with five segments, and AR-SMS imaging with four times slice acceleration. Participants were women undergoing breast MRI either as part of a treatment response clinical trial or undergoing breast MRI for screening or suspected cancer. A commercial breast phantom was imaged for resolution comparison. Three breast radiologists reviewed images in random order, including clinical images indicating the lesion, images with b value of 800 sec/mm 2 , and apparent diffusion coefficient (ADC) maps from the three randomly labeled DWI methods. Readers measured the longest dimension and lesion-average ADC on three DWI methods, reported measurement confidence, and rated or ranked the quality of each image. The scores were fit to a linear mixed-effects model with intercepts for reader and subject. Results:The smallest feature (1 mm) was only detectible in a phantom on images from AR-SMS DWI. Thirty lesions from 28 women (mean age, 50 years 6 13 [standard deviation]) were evaluated. On the five-point Likert scale for image quality, AR-SMS imaging scored 1.31 points higher than SE echo-planar imaging and 0.74 ...

Purpose Correction of Nyquist ghosts for single‐shot spin‐echo EPI using the standard 3‐line navigator often fails in breast DWI because of incomplete fat suppression, respiration, and greater B0 inhomogeneity. The purpose of this work is to compare the performance of the 3‐line navigator with 4 data‐driven methods termed “referenceless methods,” including 2 previously proposed in literature, 1 introduced in this work, and finally a combination of all 3, in breast DWI. Methods Breast DWI was acquired for 41 patients with SS SE‐EPI. Raw data was corrected offline with the standard 3‐line navigator and 4 referenceless methods, which modeled the ghost as a linear phase error and minimized 3 unique cost functions as well as the median solution of all 3. Ghost levels were evaluated based on the signal intensity in the background region, defined by a mask auto‐generated from a T1‐weighted anatomical image. Ghost intensity measurements were fit to a linear mixed model including ghost correction method and b‐value as covariates. Results All 4 referenceless methods outperformed the standard 3‐line navigator with statistical significance at all 4 b‐values tested (b = 0, 100, 600, and 800 s/mm2). Conclusions Referenceless methods provide a robust way to reduce Nyquist ghosts in breast DWI without the need for any additional calibration scan.