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Fast reconstruction is crucial for the implementation of CS-SENSE onclinical scanners. Thus, improvements of the reconstruction speed are desirable, both in terms of algorithms with improved convergence and parallel implementation. In this work, we propose a modified CS-SENSE reconstruction method based on the Nesterov’s optimal gradientscheme, which is less sensitive to inaccuracies in the coil sensitivity estimation and has an improved convergence speed.

In this work, we investigate the influence of the sampling pattern on the convergence behaviour of {1-regularized SENSE reconstruction at different reduction factors. In other words, we try to answer the question what improvement can CS-SENSE provide over {1-denoised SENSE.

In this work, we present a CS reconstruction based on statistical non-local self-similarity filtering (STAINLeSS), in which the parameters are entirely determined by the noise estimation in the receive channels obtained from a standard noise measurement. The method achieves improved image quality compared to wavelet based CS reconstruction in particular in SENSE based multi-coil reconstruction due to itsadaptivity to spatially varying noise. The proposed method providesimproved robustness due to the lack of free parameters which is crucial for the clinical applicability of CS.

A central issue of parallel RF transmission is the SAR management toensure patient safety. The additional degrees of freedom availablein parallel transmission hamper straight-forward SAR estimations asapplied for single channel transmission. As an alternative to the usually applied model-based SAR estimation, a new method has been proposed to estimate SAR from the acquired B1 maps. This B1-based SAR determination has been successfully tested for quadrature (single channel) excitation in vivo and non-quadrature (multi-channel) excitation in a phantom study. This study adapts B1-based SAR determination for non-quadrature excitation in vivo. To this goal, the local SAR inthighs and pelvis of a volunteer is investigated and compared withresults of corresponding FDTD simulations based on the same volunteer.

Transmit SENSE is typically applied to improve spatially selective RF pulses in two or three dimensions. This study investigates the application of Transmit SENSE to one-dimensional RF pulses. For these RF pulses, Transmit SENSE is applicable in case of large B1 variations across the slice or slab to be excited. Typically, such large B1 variations are found across the slabs excited in 3D volume imaging orin the framework of the REgional Saturation Technique (REST). 1D Transmit SENSE can improve the excitation slab profile, and particularly can result in a significant reduction of RF power and the relatedspecific absorption rate (SAR). Since the involved RF pulses have the same duration as standard slice-selection pulses, they can easilybe incorporated in standard sequences without changing sequence timing. The approach was tested using synthetic and realistic coil sensitivity profiles.

Fast and robust in vivo B1 mapping is an essential prerequisite forquantitative MRI or multi-element transmit applications like RF-shimming or accelerated multi-dimensional RF pulses. However, especially at higher field strength, the acquisition speed of current B1-mapping approaches is typically limited by SAR constraints, T1 relaxation times, or characteristic sequence properties, which makes a multi-transmit element B1 calibration scan rather time consuming. Moreover, existing B1 mapping approaches are typically prone to motion,since the flip angle is calculated from two or more acquisitions separated in time. In this work, a novel multi-slice B1 mapping approach dubbed DREAM (Dual Refocusing Echo Acquisition Mode) is proposed, which derives a 2D B1 map from a single, ultra-short acquisitionof about 130 ms duration, which is more than an order of magni- tudefaster than most existing B1 mapping techniques. Moreover, the transceive phase and B0 are delivered in addition and for free. The performance of the approach is demonstrated in vivo by B1 mapping experiments in the abdomen at 3T.

A Simultaneous Non-contrast Angiography and intraPlaque hemorrhage (SNAP) MR imaging technique was proposed to detect both luminal stenosis and hemorrhage in atherosclerosis patients in a single scan. 13patients with diagnosed carotid atherosclerotic plaque were recruited after informed consent. All scans were performed on a 3T MR imaging system with SNAP, 2D time-of-flight (TOF) and magnetization-prepared 3D rapid acquisition gradient echo (MP-RAGE) sequences. The SNAPsequence utilized a phase sensitive acquisition, and was designed toprovide positive signals corresponding to intraplaque hemorrhage (IPH) and negative signals corresponding to lumen. SNAP images were compared to TOF images to validate lumen area measurements using linear mixed models and the intraclass correlation coefficient (ICC). IPHidentification accuracy was evaluated by comparing to MP-RAGE images using Cohen’s Kappa. Diagnostic quality SNAP images were generatedfrom all subjects. Quantitatively, the lumen area measurements by SNAP were strongly correlated (ICC=0.96, p<0.001) with those measuredby TOF. For IPH detection, strong agreement (&#954;=0.82, p<0.001)was also identified between SNAP and MP-RAGE images. The SNAP technique was proposed and validated to reliably detect in a single acquisition both luminal size and intraplaque hemorrhage in the patients with carotid atherosclerosis.