Kat-ARC accelerated 4D flow CMR: clinical validation for transvalvular flow and peak velocity assessment.

Background: To validate the k-adaptive-t autocalibrating reconstruction for Cartesian sampling (kat-ARC), an exclusive sparse reconstruction technique for four-dimensional (4D) flow cardiac magnetic resonance (CMR) using conservation of mass principle applied to transvalvular flow.

Methods: This observational retrospective study (2020/21-075) was approved by the local ethics committee at the University of East Anglia. Consent was waived.

Motion corrected silent ZTE neuroimaging.

Purpose: To develop self-navigated motion correction for 3D silent zero echo time (ZTE) based neuroimaging and characterize its performance for different types of head motion.

Methods: The proposed method termed MERLIN (Motion Estimation & Retrospective correction Leveraging Interleaved Navigators) achieves self-navigation by using interleaved 3D phyllotaxis k-space sampling. Low resolution navigator images are reconstructed continuously throughout the ZTE acquisition using a sliding window and co-registered in image space relative to a fixed reference position.

Silent zero TE MR neuroimaging: Current state-of-the-art and future directions.

Magnetic Resonance Imaging (MRI) scanners produce loud acoustic noise originating from vibrational Lorentz forces induced by rapidly changing currents in the magnetic field gradient coils. Using zero echo time (ZTE) MRI pulse sequences, gradient switching can be reduced to a minimum, which enables near silent operation.Besides silent MRI, ZTE offers further interesting characteristics, including a nominal echo time of TE = 0 (thus capturing short-lived signals from MR tissues which are otherwise MR-invisible), 3D radial sampling (providing motion robustness), and ultra-short repetition times (providing fast and efficient scanning).

Revealing the mechanisms behind novel auditory stimuli discrimination: An evaluation of silent functional MRI using looping star.

Looping Star is a near-silent, multi-echo, 3D functional magnetic resonance imaging (fMRI) technique. It reduces acoustic noise by at least 25dBA, with respect to gradient-recalled echo echo-planar imaging (GRE-EPI)-based fMRI. Looping Star has successfully demonstrated sensitivity to the cerebral blood-oxygen-level-dependent (BOLD) response during block design paradigms but has not been applied to event-related auditory perception tasks.

Silent myelin-weighted magnetic resonance imaging.

 Inhomogeneous Magnetization Transfer (ihMT) is an emerging, uniquely myelin-specific magnetic resonance imaging (MRI) contrast. Current ihMT acquisitions utilise fast Gradient Echo sequences which are among the most acoustically noisy MRI sequences, reducing patient comfort during acquisition. We sought to address this by modifying a near silent MRI sequence to include ihMT contrast.

Silent 3D MR sequence for quantitative and multicontrast T1 and proton density imaging.

This study aims to develop a silent, fast and 3D method for T1 and proton density (PD) mapping, while generating time series of T1-weighted (T1w) images with bias-field correction. Undersampled T1w images at different effective inversion times (TIs) were acquired using the inversion recovery prepared RUFIS sequence with an interleaved k-space trajectory. Unaliased images were reconstructed by constraining the signal evolution to a temporal subspace which was learned from the signal model.

Looping Star fMRI in Cognitive Tasks and Resting State.

Background: Conventional T *-weighted functional magnetic resonance imaging (fMRI) is performed with echo-planar imaging (EPI) sequences that create substantial acoustic noise. The loud acoustic noise not only affects the activation of the auditory cortex, but may also interfere with resting state and task fMRI experiments.

Purpose: To demonstrate the feasibility of a novel, quiet, T *, whole-brain blood oxygenation level-dependent (BOLD)-fMRI method, termed Looping Star, compared to conventional multislice gradient-echo EPI.

Evaluation of self-calibrated non-linear phase-contrast correction in pediatric and congenital cardiovascular magnetic resonance imaging.

Background: The need for background error correction in phase-contrast flow analysis has historically posed a challenge in cardiac magnetic resonance (MR) imaging. While previous studies have shown that phantom correction improves flow measurements, it impedes scanner workflow.

Objective: To evaluate the efficacy of self-calibrated non-linear phase-contrast correction on flows in pediatric and congenital cardiac MR compared to phantom correction as the standard.

Silent T mapping using the variable flip angle method with B correction.

Purpose: To compare the silent rotating ultrafast imaging sequence (RUFIS) to a traditional Cartesian spoiled gradient-echo (SPGR) acquisition scheme for variable flip angle (VFA) mapping.

Methods: A two-point VFA measurement was performed using RUFIS and Cartesian SPGR in a quantitative phantom and healthy volunteers. To correct for errors, a novel silent magnetization prepared map acquisition (SIMBA) was developed, which combined with RUFIS VFA allows for a completely silent mapping protocol.

Accelerated multi-snapshot free-breathing mapping based on the dual refocusing echo acquisition mode technique (DREAM): An alternative to measure RF nonuniformity for cardiac MRI.

Background: Field inhomogeneities in MRI caused by interactions between the radiofrequency field and the patient anatomy can lead to artifacts and contrast variations, consequently degrading the overall image quality and thereby compromising diagnostic value of the images.

Purpose: To develop an efficient free-breathing and motion-robust mapping method that allows for the investigation of spatial homogeneity of the transmitted radiofrequency field in the myocardium at 3.0T.

Silent T and T encoding using ZTE combined with BURST.

Purpose: To obtain T and T -weighted images as well as quantitative T , T , and susceptibility maps with a novel, silent 3D imaging method, which combines zero-echo-time (ZTE) imaging with gradient- and spin-echo BURST encoding.

Methods: After a segment of standard ZTE encoding with multiple 3D radial k-space spokes, the direction of traversing k-space is reversed while excitation is switched off. This recalls gradient echoes for each spoke/excitation.

Looping Star.

Purpose: To introduce a novel MR pulse sequence, termed Looping Star, for fast, robust, and yet quiet, 3D radial multi-gradient echo T2* MR imaging.

Methods: The Looping Star pulse sequence is based on the 3D radial Rotating Ultra-Fast Imaging Sequence (RUFIS) extended by a time-multiplexed gradient-refocusing mechanism. First, multiple magnetic coherences are excited, which are subsequently gradient-refocused in form of a looping k-space trajectory.

Altered brain rhythms and functional network disruptions involved in patients with generalized fixation-off epilepsy.

Generalized Fixation-off Sensitivity (CGE-FoS) patients present abnormal EEG patterns when losing fixation. In the present work, we studied two CGE-FoS epileptic patients with simultaneous EEG-fMRI. We aim to identify brain areas that are specifically related to the pathology by identifying the brain networks that are related to the EEG brain altered rhythms.

Quiet and distortion-free, whole brain BOLD fMRI using T2 -prepared RUFIS.

Purpose: To develop and evaluate a novel MR method that addresses some of the most eminent technical challenges of current BOLD-based fMRI in terms of 1) acoustic noise and 2) geometric distortions and signal dropouts.

Methods: A BOLD-sensitive fMRI pulse sequence was designed that first generates T2-weighted magnetization (using a T2 preparation module) and subsequently undergoes three-dimensional (3D) radial encoding using a rotating ultrafast imaging sequence (RUFIS). The method was tested on healthy volunteers at 3T with motor, visual, and auditory tasks, and compared relative to standard gradient and spin echo planar imaging (EPI) methods.

Disparate connectivity for structural and functional networks is revealed when physical location of the connected nodes is considered.

Macroscopic brain networks have been widely described with the manifold of metrics available using graph theory. However, most analyses do not incorporate information about the physical position of network nodes. Here, we provide a multimodal macroscopic network characterization while considering the physical positions of nodes.

Changes in resting-state functionally connected parietofrontal networks after videogame practice.

Neuroimaging studies provide evidence for organized intrinsic activity under task-free conditions. This activity serves functionally relevant brain systems supporting cognition. Here, we analyze changes in resting-state functional connectivity after videogame practice applying a test-retest design.

Objective assessment of olfactory function using functional magnetic resonance imaging.

Objective: To show the results of a device that generates automated olfactory stimuli suitable for functional magnetic resonance imaging (fMRI) experiments.

Material And Methods: Ten normal volunteers, 5 women and 5 men, were studied. The system allows the programming of several sequences, providing the capability to synchronise the onset of odour presentation with acquisition by a trigger signal of the MRI scanner.