R2*-corrected water-fat imaging using compressed sensing and parallel imaging.

Purpose: To demonstrate an approach to water-fat separation with R2* correction using compressed sensing and parallel imaging.

Methods: Acquisition times for chemical shift based water-fat separation imaging are lengthy, and many applications rely on image acceleration techniques. In this study, we present an integrated compressed sensing, parallel imaging, R2* corrected water-fat separation technique for water-fat imaging of highly accelerated acquisitions.

Magnetic resonance thermal imaging combined with SMASH navigators in the presence of motion.

This study develops and tests an MR thermometry method combined with SMASH navigators in phantom experiments mimicking human liver motion with the purpose of detecting and correcting motion artifacts in thermal MR images. Experimental data were acquired on a 3T MRI scanner. Motion artifacts of mobile phantoms mimicking human liver motion were detected and corrected using the SMASH navigators and then MR temperature maps were obtained using a proton resonant frequency (PRF) shift method with complex image subtraction.

Computationally rapid method of estimating signal-to-noise ratio for phased array image reconstructions.

Measuring signal-to-noise ratio (SNR) for parallel MRI reconstructions is difficult due to spatially dependent noise amplification. Existing approaches for measuring parallel MRI SNR are limited because they are not applicable to all reconstructions, require significant computation time, or rely on repeated image acquisitions. A new SNR estimation approach is proposed, a hybrid of the repeated image acquisitions method detailed in the National Electrical Manufacturers Association (NEMA) standard and the Monte Carlo based pseudo-multiple replica method, in which the difference between images reconstructed from the unaltered acquired data and that same data reconstructed after the addition of calibrated pseudo-noise is used to estimate the noise in the parallel MRI image reconstruction.

Studies of the interactions of an MRI system with the shielding in a combined PET/MRI scanner.

A positron emission tomography (PET) system or 'insert' has been constructed for placement and operation in the bore of a small animal magnetic resonance imaging (MRI) scanner to allow simultaneous MR and PET imaging. The insert contains electronics, components with a variety of magnetic properties and large continuous sheets of metal--all characteristics of an object that should, by conventional wisdom, never be placed in the bore of an MR scanner, especially near the imaging volume. There are a variety of ways the two systems might be expected to interact that could negatively impact the performance of either or both.

Phase-constrained parallel MR image reconstruction.

A generalized method for phase-constrained parallel MR image reconstruction is presented that combines and extends the concepts of partial-Fourier reconstruction and parallel imaging. It provides a framework for reconstructing images employing either or both techniques and for comparing image quality achieved by varying k-space sampling schemes. The method can be used as a parallel image reconstruction with a partial-Fourier reconstruction built in.

Inherently self-calibrating non-Cartesian parallel imaging.

The use of self-calibrating techniques in parallel magnetic resonance imaging eliminates the need for coil sensitivity calibration scans and avoids potential mismatches between calibration scans and subsequent accelerated acquisitions (e.g., as a result of patient motion).