Removing silicone artifacts in diffusion-weighted breast MRI by means of shift-resolved spatiotemporally encoding

Abstract

# These authors contributed equally to this work. AbstractPurpose-Evaluate the usefulness of diffusion-weighted spatiotemporally-encoded (SPEN) methods to obtain ADC maps of fibroglandular human breast tissue, in the presence of silicone implants.Methods-Seven healthy volunteers with breast augmentation were scanned at 3T using customized SPEN sequences yielding separate silicone and water 1 H images in one scan, together with their corresponding diffusion-weightings.Results-SPEN's ability to deliver multiple spectrally-resolved images in a single scan, coupled to the method's substantial robustness to magnetic field heterogeneities, served to acquire ADC maps that could be freed from contributions that did not belong to fibroglandular tissue.Conclusion-SPEN-based sequences incorporating spectral discrimination and diffusionweighting enable the acquisition of reliable ADC maps despite the presence of silicone implants, thereby opening new screening possibilities for the identification of malignancies in breast augmented patients.

Diffusion‐weighted breast MRI of malignancies with submillimeter resolution and immunity to artifacts by spatiotemporal encoding at 3T

“…SPEN is a single‐shot imaging modality that can also be extended to multishot interleaved operation with certain benefits in the ensuing spatial resolution and sensitivity. SPEN relies on performing a consecutive excitation or refocusing of the spins, achieved by applying a linearly chirped radio frequency (RF) pulse acting in the presence of an encoding gradient G e . In the multislice, fully refocused pulse sequence here assayed (Figure ), spins are first excited by a slice‐selective 90° pulse and then acted upon by a swept 180° inversion pulse, linearly chirping over a bandwidth BW during a time T e while in the presence of a y ‐axis G e gradient.…”

“…Additional resolution improvements can result from SPEN’s built‐in ability to restrict the targeted FOVs. Single‐shot studies incorporating SPEN into diffusion schemes have shown this method’s potential for overcoming SE EPI’s characteristic limitations in animals and humans . The purpose of the study is to explore SPEN’s ability to deliver quantitative diffusion breast maps at sub‐millimeter in‐plane resolutions, in clinically relevant situations.…”

Diffusion MRI measurements in challenging head and brain regions via cross-term spatiotemporally encoding

“…These include multi-shot schemes liable to motion-derived errors, as well as single-shot acquisitions based on radial samplings or on the use of multiple rf-driven spin echoes 15 – 19 . Recently introduced single-shot 2D SPEN methods can achieve many of these goals 20 , 35 , 45 – 47 , yet if overwhelmed by inhomogeneities even these methods are liable to yield corrupted images reflecting ΔB o displacements. xSPEN by contrast shows unprecedented resilience to in-plane field inhomogeneities, with the sole distortions identified in their single-scan 2D images arising from limitations in the slice selection process 31 .…”

“…35,[44][45][46], yet if overwhelmed by inhomogeneities even these methods are liable to yield corrupted images reflecting ΔB o displacements. xSPEN by contrast shows unprecedented resilience to in-plane field inhomogeneities, with the sole distortions identified in their singlescan 2D images arising from limitations in the slice selection process(30).…”

Parallel nuclear magnetic resonance spectroscopy

“…Homonuclear single-scan 2D correlations relying on enhancements derived from para-hydrogen have also been implemented 120 . Single-scan 2D spectral-spatial correlations have also been demonstrated in this manner, including in hyperpolarized and thermal preclinical, as well as in clinical human MRI settings [121][122][123][124][125] . As mentioned, the spatial extent of a homogeneous sample can also be used to encode other sorts of information besides chemical shifts of evolving spins.…”