Versatile MRI acquisition and processing protocol for population-based neuroimaging.

Neuroimaging has an essential role in studies of brain health and of cerebrovascular and neurodegenerative diseases, requiring the availability of versatile magnetic resonance imaging (MRI) acquisition and processing protocols. We designed and developed a multipurpose high-resolution MRI protocol for large-scale and long-term population neuroimaging studies that includes structural, diffusion-weighted and functional MRI modalities. This modular protocol takes almost 1 h of scan time and is, apart from a concluding abdominal scan, entirely dedicated to the brain.

Calibration-free whole-brain CEST imaging at 7T with parallel transmit pulse design for saturation homogeneity utilizing universal pulses (PUSHUP).

Purpose: Chemical exchange saturation transfer (CEST) measurements at ultra-high field (UHF) suffer from strong saturation inhomogeneity. Retrospective correction of this inhomogeneity is possible to some extent, but requires a time-consuming repetition of the measurement. Here, we propose a calibration-free parallel transmit (pTx)-based saturation scheme that homogenizes the saturation over the imaging volume, which we call PUlse design for Saturation Homogeneity utilizing Universal Pulses (PUSHUP).

Design of calibration-free RF pulses for T -weighted single-slab 3D turbo-spin-echo sequences at 7T utilizing parallel transmission.

Purpose: T -weighted turbo-spin-echo (TSE) sequences are a fundamental technique in brain imaging but suffer from field inhomogeneities at ultra-high fields. Several methods have been proposed to mitigate the problem, but were limited so far to nonselective three-dimensional (3D) measurements, making short acquisitions difficult to achieve when targeting very high resolution images, or needed additional calibration procedures, thus complicating their application.

Methods: Slab-selective excitation pulses were designed for flexible placement utilizing the concept of k -spokes.

Interleaved binomial k -points for water-selective imaging at 7T.

Purpose: We present a time-efficient water-selective, parallel transmit RF excitation pulse design for ultra-high field applications.

Methods: The proposed pulse design method achieves flip angle homogenization at ultra-high fields by employing spatially nonselective -points pulses. In order to introduce water-selection, the concept of binomial pulses is applied.

Effects of freediving on middle ear and eustachian tube function.

Introduction: During descent in freediving there is exposure to rapidly increasing pressure. Inability to quickly equalise middle ear pressure may cause trauma to the ear. This study aimed to evaluate the occurrence of pressure-related damage to the middle ear and the Eustachian tube during freediving and to identify possible risk factors.

On the reproducibility of hippocampal MEGA-sLASER GABA MRS at 7T using an optimized analysis pipeline.

Objectives: GABA is the most important inhibitory neurotransmitter. Thus, variation in its concentration is connected to a wide variety of diseases. However, the low concentration and the overlap of more prominent resonances hamper GABA quantification using MR spectroscopy.

Whole-brain B -mapping using three-dimensional DREAM.

Purpose: Demonstration of a 3D version of the DREAM sequence (3DREAM) for rapid 3D flip angle and mapping of the human brain.

Methods: A rectangular non-selective STE preparation is followed by a 3D readout with a Cartesian center-out spiral phase encoding order. This enables parallel imaging acceleration in both phase encoding dimensions as well as early capture of the prepared magnetization.

Robust nonadiabatic T preparation using universal parallel-transmit k -point pulses for 3D FLAIR imaging at 7 T.

Purpose: The fluid attenuated inversion recovery sequence is a pillar technique to detect brain lesions in MRI. At ultrahigh field, the lengthening of T often advocates a T -weighting preparation module to regain signal and contrast between tissues, which can be affected by transmit RF field inhomogeneity. In this note, we report an extension of a previous fluid attenuated inversion recovery study that now incorporates the T preparation with parallel transmission calibration-free universal pulses to mitigate the problem.

Accelerated 3D-GRASE imaging improves quantitative multiple post labeling delay arterial spin labeling.

Purpose: To investigate the impact of accelerated, single-shot 3D-GRASE acquisition on quantitative arterial spin labeling (ASL) with multiple and single post-labeling delay (PLD) in terms of perfusion-weighted SNR per unit scan time (TSNR ) and quantification accuracy.

Methods: Five subjects were scanned on a 3T MRI scanner using the pseudo-continuous arterial spin labeling (PCASL) technique with a 3D-GRASE imaging sequence capable of parallel imaging acceleration. A 3-inversion pulse background suppression was simulated and implemented in the sequence.

GRAPPA reconstructed wave-CAIPI MP-RAGE at 7 Tesla.

Purpose: The aim of this project was to develop a GRAPPA-based reconstruction for wave-CAIPI data. Wave-CAIPI fully exploits the 3D coil sensitivity variations by combining corkscrew k-space trajectories with CAIPIRINHA sampling. It reduces artifacts and limits reconstruction induced spatially varying noise enhancement.

Influence of repetitive diving in freshwater on pressure equalization and Eustachian tube function in recreational scuba divers.

Introduction: We investigated the effect of repetitive pressure exposure during freshwater dives on Eustachian tube function and the middle ear, assessed by the Eustachian tube function test (ETFT).

Methods: This prospective observational cohort study included 23 divers over three consecutive days of diving in freshwater lakes in Nordhausen, Germany. Participants underwent otoscopy and ETFT before the first dive, between each dive and after the last dive.

Influence of repetitive diving in saltwater on pressure equalization and Eustachian tube function in recreational scuba divers.

Introduction: We investigated in a prospective, observational trial the feasibility of using the Eustachian tube function test (ETFT) to measure the effect of repetitive pressure exposure during open seawater dives on Eustachian tube function.

Methods: The study included 28 adult divers during six consecutive days of diving in the Red Sea. Participants underwent otoscopy and ETFT before the first dive, between each dive and after the last dive.

Repetitive freshwater diving: risk factors and prevalence of barotrauma.

Objective: The aim was to investigate the influence of repetitive scuba diving in fresh water on the middle ear mucosa. The prevalence of middle ear barotrauma (MEB) and risk factors for MEB were evaluated.

Study Design: Prospective cohort study, Level of evidence 1b.

SAR and scan-time optimized 3D whole-brain double inversion recovery imaging at 7T.

Purpose: The aim of this project was to implement an ultra-high field (UHF) optimized double inversion recovery (DIR) sequence for gray matter (GM) imaging, enabling whole brain coverage in short acquisition times ( ≈5 min, image resolution 1 mm ).

Methods: A 3D variable flip angle DIR turbo spin echo (TSE) sequence was optimized for UHF application. We implemented an improved, fast, and specific absorption rate (SAR) efficient TSE imaging module, utilizing improved reordering.

Multimodal MEMPRAGE, FLAIR, and [Formula: see text] Segmentation to Resolve Dura and Vessels from Cortical Gray Matter.

While widely in use in automated segmentation approaches for the detection of group differences or of changes associated with continuous predictors in gray matter volume, T1-weighted images are known to represent dura and cortical vessels with signal intensities similar to those of gray matter. By considering multiple signal sources at once, multimodal segmentation approaches may be able to resolve these different tissue classes and address this potential confound. We explored here the simultaneous use of FLAIR and apparent transverse relaxation rates (a signal related to [Formula: see text] relaxation maps and having similar contrast) with T1-weighted images.

Prevalence of Barotrauma in Recreational Scuba Divers After Repetitive Saltwater Dives.

Introduction: The aim was to investigate the prevalence of middle ear barotrauma (MEB) and to establish risk factors of MEB after repeated saltwater dives.

Methods: In this prospective observational cohort study 28 divers were examined over 6 consecutive days of diving in the Red Sea, Egypt. Participants underwent an otoscopic examination before the first dive, between each dive and after the last dive.

Two-dimensional accelerated MP-RAGE imaging with flexible linear reordering.

Object: Implementation of an accelerated Magnetization Prepared RApid Gradient Echo (MP-RAGE) sequence for T1 weighted neuroimaging; exploiting modern MRI technologies to minimize scan time while preserving the image quality.

Materials And Methods: A custom MP-RAGE sequence was implemented on a state-of-the-art 3T MR scanner equipped with a 32-channel receiver array head coil. The sequence utilized a shifted CAIPIRINHA k y -k z under-sampling pattern combined with elliptical scanning and a two-dimensional view ordering scheme to achieve high parallel imaging acceleration factors at maintained image contrast.

In vivo 19F MRI for cell tracking.

In vivo (19)F MRI allows quantitative cell tracking without the use of ionizing radiation. It is a noninvasive technique that can be applied to humans. Here, we describe a general protocol for cell labeling, imaging, and image processing.

Lung imaging under free-breathing conditions.

Respiratory motion and pulsatile blood flow can generate artifacts in morphological and functional lung imaging. Total acquisition time, and thus the achievable signal to noise ratio, is limited when performing breath-hold and/or electrocardiogram-triggered imaging. To overcome these limitations, imaging during free respiration can be performed using respiratory gating/triggering devices or navigator echoes.

Potential of magnetization transfer MRI for target volume definition in patients with non-small-cell lung cancer.

Purpose: To develop a magnetization transfer (MT) module in conjunction with a single-shot MRI readout technique and to investigate the MT phenomenon in non-small-cell lung cancer (NSCLC) as an adjunct for radiation therapy planning.

Materials And Methods: A total of 10 patients with inoperable NSCLC were investigated using a 1.5T MR scanner.

MRI thermometry: Fast mapping of RF-induced heating along conductive wires.

Conductive implants are in most cases a strict contraindication for MRI examinations, as RF pulses applied during the MRI measurement can lead to severe heating of the surrounding tissue. Understanding and mapping of these heating effects is therefore crucial for determining the circumstances under which patient examinations are safe. The use of fluoroptic probes is the standard procedure for monitoring these heating effects.

Assessment of pulmonary perfusion in a single shot using SEEPAGE.

Purpose: To present a single-shot perfusion imaging sequence that does not require contrast agents or a subtraction of a tag and a control image to create the perfusion-weighted contrast. The proposed method is based on SEEPAGE.

Materials And Methods: Experiments with healthy volunteers were performed to qualitatively and quantitatively obtain pulmonary perfusion values in coronal as well as sagittal orientation.

Lung MRI using an MR-compatible active breathing control (MR-ABC).

This work introduces an MR-compatible active breathing control device (MR-ABC) that can be applied to lung imaging. An MR-ABC consists of a pneumotachograph for respiratory monitoring and an airway-sealing unit. Using an MR-ABC, the subjects were forced to suspend breathing for short time intervals, which were used in turn for data acquisition.

Quantitative regional oxygen transfer imaging of the human lung.

Purpose: To demonstrate that the use of nonquantitative methods in oxygen-enhanced (OE) lung imaging can be problematic and to present a new approach for quantitative OE lung imaging, which fulfills the requirements for easy application in clinical practice.

Materials And Methods: A total of 10 healthy volunteers and three non-small-cell lung cancer (NSCLC) patients were examined using a 1.5T scanner.

Single-shot quantitative perfusion imaging of the human lung.

The major drawback to quantitative perfusion imaging using arterial spin labeling (ASL) techniques is the need to acquire two images (tag and control), which must be subtracted in order to obtain a perfusion-weighted image. This can potentially result in misregistration artifacts, especially in lung imaging, due to varying lung inflation levels in different breath-holds. In this work a double inversion recovery (DIR) imaging technique that yields perfusion-weighted images of the human lung in a single shot is presented.