Independent slab‐phase modulation combined with parallel imaging in bilateral breast MRI

Abstract

Independent slab-phase modulation allows three-dimensional imaging of multiple volumes without encoding the space between volumes, thus reducing scan time. Parallel imaging further accelerates data acquisition by exploiting coil sensitivity differences between volumes. This work compared bilateral breast image quality from self-calibrated parallel imaging reconstruction methods such as modified sensitivity encoding, generalized autocalibrating partially parallel acquisitions and autocalibrated reconstruction for Cartesian sampling (ARC) for data with and without slab-phase modulation. A study showed an improvement of image quality by incorporating slab-phase modulation. Geometry factors measured from phantom images were more homogenous and lower on average when slab-phase modulation was used for both mSENSE and GRAPPA reconstructions. The resulting improved signal-tonoise ratio (SNR) was validated for in vivo images as well using ARC instead of GRAPPA, illustrating average SNR efficiency increases in mSENSE by 5% and ARC by 8% based on region of interest analysis. Furthermore, aliasing artifacts from mSENSE reconstruction were reduced when slab-phase modulation was used. Overall, slab-phase modulation with parallel imaging improved image quality and efficiency for 3D While breast cancer is the second leading cause of death due to cancer among American women (1), early diagnosis and treatment can reduce mortality rates (2). Currently, the most common breast cancer screening method is X-ray mammography, which has limited ability to detect tumors in young women who have more dense breasts than postmenopausal women (3). Several studies show that MRI has much higher sensitivity for detecting cancer, especially in high-risk patients (4,5). Recently, breast MRI has been recommended by the American Cancer Society for women at 20-25% or greater lifetime risk of breast cancer (6). The ability of MRI to detect breast cancer is dependent on high-quality images, particularly with high signal-to-noise ratio (SNR) and spatial resolution. In addition, for dynamic contrast-enhanced breast imaging (7,8) resolution is also helpful for accurate characterization of contrast kinetics.Bilateral breast imaging can be more cost-effective than unilateral breast imaging and helps to detect contralateral tumors (9). Normally, bilateral breast MRI is conducted by exciting and imaging the two separated breasts together, using a volume-selective excitation. The region between the two breasts might provide useful information for diagnosis; however, when high temporal resolution is needed, not imaging that region can be beneficial as it usually occupies 20-30% of total volume. In addition, not exciting that region provides better shims over the two breasts and reduces cardiac motion artifacts. A dual-band spectralspatial excitation pulse (10,11) excites the two separate breast slabs simultaneously but independently with their own center frequencies and linear shims and thus provides robust fat suppression over each slab (12). It also allows ind...

Volumetric Arterial Spin-labeled Perfusion Imaging of the Kidneys with a Three-dimensional Fast Spin Echo Acquisition

“…For studies of bilateral disease or cortical thinning, a different resolution or scan time may be better. It is worth noting that this acquisition did not yet employ techniques of parallel imaging for dual slab acquisition (61) or phase encode acceleration, both of which could provide options for faster scanning and greater coverage. Image acceleration could also be especially helpful for accelerating the reference image used for quantification, since this image is not SNR challenged.…”

Parallel MR imaging

“…Accelerated imaging with high temporal resolution has been applied to correct for metal artifacts (75), develop more accurate pharmacokinetic models for dynamic contrast‐enhanced imaging (76), and perform fetal cine imaging (77). Reduction in scan time has allowed for volumetric imaging of various organs, from the breast imaging (78) to whole‐body imaging of parasites (79).…”

The influence of radial undersampling schemes on compressed sensing reconstruction in breast MRI

“…CS has been rapidly gaining popularity in different areas of science, and shown to dramatically improve the quality of undersampled images in MRI (15). Parallel imaging methods using Cartesian imaging (21–24) and CS methods (25, 26) have been used in breast DCE‐MRI to increase spatiotemporal resolution.…”