A 32-channel high-impedance honeycomb-shaped receive array for temporal lobes exploration at 11.7T.

Purpose: The newly operational 11.7T Iseult scanner provides an improved global SNR in the human brain. This gain in SNR can be pushed even further locally by designing region-focused dense receive arrays.

Slice-specific B shimming improves the repeatability of multishot DWI at 7 T.

Purpose: Compared with lower field strengths, DWI at 7 T faces the combined challenges of increased distortion and blurring due to B inhomogeneity, and increased signal dropouts due to B inhomogeneity. This study addresses the B limitations using slice-specific static parallel transmission (pTx) in a multi-shot, readout-segmented EPI diffusion imaging sequence.

Methods: DWI was performed in 7 healthy subjects using MRI at 7 T and readout-segmented EPI.

Acoustic noise reduction in the NexGen 7 T scanner.

Purpose: Driven by the Lorentz force, acoustic noise may arguably be the next physiological challenge associated with ultra-high field MRI scanners and powerful gradient coils. This work consisted of isolating and mitigating the main sound pathway in the NexGen 7 T scanner equipped with the investigational Impulse head gradient coil.

Methods: Sound pressure level (SPL) measurements were performed with and without the RF coil to assess its acoustic impact.

Next-generation MRI scanner designed for ultra-high-resolution human brain imaging at 7 Tesla.

To increase granularity in human neuroimaging science, we designed and built a next-generation 7 Tesla magnetic resonance imaging scanner to reach ultra-high resolution by implementing several advances in hardware. To improve spatial encoding and increase the image signal-to-noise ratio, we developed a head-only asymmetric gradient coil (200 mT m, 900 T ms) with an additional third layer of windings. We integrated a 128-channel receiver system with 64- and 96-channel receiver coil arrays to boost signal in the cerebral cortex while reducing g-factor noise to enable higher accelerations.

Electromagnetic and RF pulse design simulation based optimization of an eight-channel loop array for 11.7T brain imaging.

Purpose: Optimization of transmit array performance is crucial in ultra-high-field MRI scanners such as 11.7T because of the increased RF losses and RF nonuniformity. This work presents a new workflow to investigate and minimize RF coil losses, and to choose the optimum coil configuration for imaging.

The effects of RF coils and SAR supervision strategies for clinically applicable nonselective parallel-transmit pulses at 7 T.

Purpose: To investigate the effects of using different parallel-transmit (pTx) head coils and specific absorption rate (SAR) supervision strategies on pTx pulse design for ultrahigh-field MRI using a 3D-MPRAGE sequence.

Methods: The PTx universal pulses (UPs) and fast online-customized (FOCUS) pulses were designed with pre-acquired data sets (B , B maps, specific absorption rate [SAR] supervision data) from two different 8 transmit/32 receive head coils on two 7T whole-body MR systems. For one coil, the SAR supervision model consisted of per-channel RF power limits.

Ultra-high field MRI: parallel-transmit arrays and RF pulse design.

This paper reviews the field of multiple or parallel radiofrequency (RF) transmission for magnetic resonance imaging (MRI). Currently the use of ultra-high field (UHF) MRI at 7 tesla and above is gaining popularity, yet faces challenges with non-uniformity of the RF field and higher RF power deposition. Since its introduction in the early 2000s, parallel transmission (pTx) has been recognized as a powerful tool for accelerating spatially selective RF pulses and combating the challenges associated with RF inhomogeneity at UHF.

A self-decoupled 32-channel receive array for human-brain MRI at 10.5 T.

Purpose: Receive array layout, noise mitigation, and B field strength are crucial contributors to SNR and parallel-imaging performance. Here, we investigate SNR and parallel-imaging gains at 10.5 T compared with 7 T using 32-channel receive arrays at both fields.

Double-row 18-loop transceive-32-loop receive tight-fit array provides for whole-brain coverage, high transmit performance, and SNR improvement near the brain center at 9.4T.

Purpose: To improve the transmit (Tx) and receive (Rx) performance of a human head array and provide whole-brain coverage at 9.4T, a novel 32-element array design was developed, constructed, and tested.

Methods: The array consists of 18 transceiver (TxRx) surface loops and 14 Rx-only vertical loops all placed in a single layer.

Decoupling of a double-row 16-element tight-fit transceiver phased array for human whole-brain imaging at 9.4 T.

One of the major challenges in constructing multi-channel and multi-row transmit (Tx) or transceiver (TxRx) arrays is the decoupling of the array's loop elements. Overlapping of the surface loops allows the decoupling of adjacent elements and also helps to improve the radiofrequency field profile by increasing the penetration depth and eliminating voids between the loops. This also simplifies the design by reducing the number of decoupling circuits.

Fast and efficient free induction decay MR spectroscopic imaging of the human brain at 9.4 Tesla.

Purpose: The purpose of this work was to develop a fast and efficient MRSI-FID acquisition scheme and test its performance in vivo. The aim was to find a trade-off between the minimal total acquisition time and signal-to-noise ratio of the acquired spectra.

Methods: Measurements were performed on a 9.

Volumetric imaging with homogenised excitation and static field at 9.4 T.

Objectives: To overcome the challenges of B0 and RF excitation inhomogeneity at ultra-high field MRI, a workflow for volumetric B0 and flip-angle homogenisation was implemented on a human 9.4 T scanner.

Materials And Methods: Imaging was performed with a 9.

(31)P CSI of the human brain in healthy subjects and tumor patients at 9.4 T with a three-layered multi-nuclear coil: initial results.

Objective: Investigation of the feasibility and performance of phosphorus ((31)P) magnetic resonance spectroscopic imaging (MRSI) at 9.4 T with a three-layered phosphorus/proton coil in human normal brain tissue and tumor.

Materials And Methods: A multi-channel (31)P coil was designed to enable MRSI of the entire human brain.

In vivo proton magnetic resonance spectroscopic imaging of the healthy human brain at 9.4 T: initial experience.

Object: In this study, the feasibility of in vivo proton magnetic resonance spectroscopic imaging ((1)H MRSI) of the healthy human brain at a field strength of 9.4 T, using conventional acquisition techniques, is examined and the initial experience is summarized.

Materials And Methods: MRSI measurements were performed on a 9.

Numerical and experimental evaluation of RF shimming in the human brain at 9.4 T using a dual-row transmit array.

Objective: To provide a numerical and experimental investigation of the static RF shimming capabilities in the human brain at 9.4 T using a dual-row transmit array.

Materials And Methods: A detailed numerical model of an existing 16-channel, inductively decoupled dual-row array was constructed using time-domain software together with circuit co-simulation.