R* Impact on Hepatic Fat Quantification With a Commercial Single Voxel Technique at 1.5 and 3.0 T.

Fat quantification accuracy using a commercial single-voxel high speed T-corrected multi-echo (HISTO) technique and its robustness to R* variations at 3.0 T, such as those introduced by iron in liver, has not been fully established. This study evaluated HISTO at 3.

Repeat it without me: Crowdsourcing the T mapping common ground via the ISMRM reproducibility challenge.

Purpose: T mapping is a widely used quantitative MRI technique, but its tissue-specific values remain inconsistent across protocols, sites, and vendors. The ISMRM Reproducible Research and Quantitative MR study groups jointly launched a challenge to assess the reproducibility of a well-established inversion-recovery T mapping technique, using acquisition details from a seminal T mapping paper on a standardized phantom and in human brains.

Methods: The challenge used the acquisition protocol from Barral et al.

MR-oximetry with fat DESPOT.

Purpose: The R relaxation rate of fat is a promising marker of tissue oxygenation. Existing techniques to map fat R in MR-oximetry offer limited spatial coverage, require long scan times, or pulse sequences that are not readily available on clinical scanners. This work addresses these limitations with a 3D voxel-wise fat R mapping technique for MR-oximetry based on a variable flip angle (VFA) approach at 3 T.

Longitudinal relaxation in fat-water mixtures and its dependence on fat content at 3 T.

Longitudinal (T ) relaxation of triglyceride molecules and water is of interest for fat-water separation and fat quantification. A better understanding of T relaxation could benefit modeling for applications in fat quantification and relaxation mapping. This work investigated T relaxation of spectral resonances of triglyceride molecules and water in liquid fat-water mixtures and its dependence on the fat fraction.

A role for magnetic susceptibility in synthetic computed tomography.

Purpose: Radiotherapy treatment planning based on magnetic resonance imaging (MRI) benefits from increased soft-tissue contrast and functional imaging. MRI-only planning is attractive but limited by the lack of electron density information required for dose calculation, and the difficulty to differentiate air and bone. MRI can map magnetic susceptibility to separate bone from air.

Phase processing for quantitative susceptibility mapping of regions with large susceptibility and lack of signal.

Purpose: Phase processing impacts the accuracy of quantitative susceptibility mapping (QSM). Techniques for phase unwrapping and background removal have been proposed and demonstrated mostly in brain. In this work, phase processing was evaluated in the context of large susceptibility variations (Δχ) and negligible signal, in particular for susceptibility estimation using the iterative phase replacement (IPR) algorithm.