Motivational incentives lead to a strong increase in lateral prefrontal activity after self-control exertion.

Self-control is key to success in life. Initial acts of self-control temporarily impair subsequent self-control performance. Why such self-control failures occur is unclear, with prominent models postulating a loss of a limited resource vs a loss of motivation, respectively.

Abnormal structure and function of the esophagogastric junction and proximal stomach in gastroesophageal reflux disease.

Objectives: This study applies concurrent magnetic resonance imaging (MRI) and high-resolution manometry (HRM) to test the hypothesis that structural factors involved in reflux protection, in particular, the acute insertion angle of the esophagus into the stomach, are impaired in gastroesophageal reflux disease (GERD) patients.

Methods: A total of 24 healthy volunteers and 24 patients with mild-moderate GERD ingested a test meal. Three-dimensional models of the esophagogastric junction (EGJ) were reconstructed from MRI images.

Detecting analogies unconsciously.

Analogies may arise from the conscious detection of similarities between a present and a past situation. In this functional magnetic resonance imaging study, we tested whether young volunteers would detect analogies unconsciously between a current supraliminal (visible) and a past subliminal (invisible) situation. The subliminal encoding of the past situation precludes awareness of analogy detection in the current situation.

Validation of a golden angle radial sequence (GOLD) for abdominal T1 mapping during free breathing: demonstrating clinical feasibility for quantifying gastric secretion and emptying.

Purpose: To validate a magnetic resonance imaging sequence suitable for quantitative assessment of acid suppression by a proton pump inhibitor (PPI) on gastric secretion and emptying in clinical practice.

Methods: A golden angle radial sequence (GOLD) was validated in a series of in vitro and in vivo experiments and clinical feasibility was shown in two studies. The impact of free breathing and image plane orientation on T1 values was evaluated in a controlled in vivo experiment.

Suppressing emotions impairs subsequent stroop performance and reduces prefrontal brain activation.

Abundant behavioral evidence suggests that the ability to self-control is limited, and that any exertion of self-control will increase the likelihood of subsequent self-control failures. Here we investigated the neural correlates underlying the aftereffects of self-control on future control processes using functional magnetic resonance imaging (fMRI). An initial act of self-control (suppressing emotions) impaired subsequent performance in a second task requiring control (Stroop task).

ProFit revisited.

Purpose: An enhanced version of the ProFit fitting tool was developed and validated to improve the quantification of two-dimensional JRPESS spectroscopic data.

Methods: The proposed enhancements were achieved by flexible organization of prior knowledge, configurations for different situations, the inclusion of measured macromolecular baseline contribution, additional baseline splines and a model-free lineshape based on self-deconvolution. The new software was tested and tuned on simulated data and subsequently applied to in vivo intrasubject and intersubject data.

Spinal cord diffusion-tensor imaging and motor-evoked potentials in multiple sclerosis patients: microstructural and functional asymmetry.

Purpose: To assess possible association between intrinsic structural damage and clinical disability by correlating spinal cord diffusion-tensor (DT) imaging data with electrophysiological parameters in patients with a diagnosis of multiple sclerosis (MS).

Materials And Methods: This study was approved by the local ethical committee according to the declaration of Helsinki and written informed consent was obtained. DT images and T1- and T2-weighted images of the spinal cord were acquired in 28 healthy volunteers and 41 MS patients.

Real-time multipoint gastrointestinal 19-fluorine catheter tracking.

Purpose: To develop MR based real-time gastrointestinal 19-Fluorine (19F) catheter tracking and visualization allowing for real-time detection and feedback of 3D catheter shape and movement as well as catheter-driven adjustments of 1H imaging geometry parameters.

Methods: Data were acquired on a 3T clinical system using 3D Golden Angle radial sampling. Two gastrointestinal catheters incorporating four fiducial 19F markers (65 or 50 µL marker volume) were tracked while being pulled through a gel phantom by an operator inside the MR room with velocities of 2-18 mm/s.

Monitoring and compensating phase imperfections in cine balanced steady-state free precession.

Purpose: To analyze and correct for eddy current-induced phase imperfections in cardiac cine balanced steady-state free precession (bSSFP) imaging.

Methods: Eddy current-induced phase offsets were measured for different phase-encoding schemes using a higher order dynamic field camera. Based on these measurements, offset phases were corrected for in postprocessing and by run-time phase compensation applying radiofrequency phase increments and additional compensatory gradient areas.

BootGraph: probabilistic fiber tractography using bootstrap algorithms and graph theory.

Bootstrap methods have recently been introduced to diffusion-weighted magnetic resonance imaging to estimate the measurement uncertainty of ensuing diffusion parameters directly from the acquired data without the necessity to assume a noise model. These methods have been previously combined with deterministic streamline tractography algorithms to allow for the assessment of connection probabilities in the human brain. Thereby, the local noise induced disturbance in the diffusion data is accumulated additively due to the incremental progression of streamline tractography algorithms.

Electrocardiogram-triggered, higher order, projection-based B₀ shimming allows for fast and reproducible shim convergence in spinal cord ¹H MRS.

¹H MRS allows insight into the chemical composition of the central nervous system. However, as a result of technical challenges, it has rarely been applied to the spinal cord. In particular, the strong susceptibility changes around the spinal cord and the pulsatile flow of the cerebrospinal fluid lead to distinct B₀ field distortions which often considerably degrade the spectral quality.

Ketamine decreases resting state functional network connectivity in healthy subjects: implications for antidepressant drug action.

Increasing preclinical and clinical evidence underscores the strong and rapid antidepressant properties of the glutamate-modulating NMDA receptor antagonist ketamine. Targeting the glutamatergic system might thus provide a novel molecular strategy for antidepressant treatment. Since glutamate is the most abundant and major excitatory neurotransmitter in the brain, pathophysiological changes in glutamatergic signaling are likely to affect neurobehavioral plasticity, information processing and large-scale changes in functional brain connectivity underlying certain symptoms of major depressive disorder.

19F MR imaging golden angle-based capsule tracking for intestinal transit and catheter tracking: initial in vivo experience.

Purpose: To combine fluorine 19 ((19)F) magnetic resonance (MR) imaging and golden angle radial acquisition and to assess the feasibility of (19)F MR imaging golden angle-based tracking for catheter tracking applications and simultaneous three-dimensional (3D) intestinal tracking of ingested (19)F-labeled capsules in vivo.

Materials And Methods: Approval from the local ethical committee and informed consent from the subject were obtained. In vitro studies were performed to assess (19)F MR imaging golden angle-based tracking reliability with regard to temporal resolution and different tracking strategies (boundary condition-free tracking, composite image-based tracking, and model-based tracking).

Undersampled cine 3D tagging for rapid assessment of cardiac motion.

Background: CMR allows investigating cardiac contraction, rotation and torsion non-invasively by the use of tagging sequences. Three-dimensional tagging has been proposed to cover the whole-heart but data acquisition requires three consecutive breath holds and hence demands considerable patient cooperation. In this study we have implemented and studied k-t undersampled cine 3D tagging in conjunction with k-t PCA reconstruction to potentially permit for single breath-hold acquisitions.

Cardiac proton spectroscopy using large coil arrays.

Large coil arrays are widely used in clinical routine for cardiovascular imaging providing extended spatial coverage and enabling accelerated acquisition using parallel imaging approaches. This work investigates the use of large coil arrays in single-voxel cardiac spectroscopy for the detection of myocardial creatine and triglyceride content. For this purpose, a navigator-gated and cardiac-triggered point-resolved spectroscopy sequence was implemented, and data obtained in 11 healthy volunteers using 32- and 5-element coil arrays were compared.

Sparsity transform k-t principal component analysis for accelerating cine three-dimensional flow measurements.

Time-resolved three-dimensional flow measurements are limited by long acquisition times. Among the various acceleration techniques available, k-t methods have shown potential as they permit significant scan time reduction even with a single receive coil by exploiting spatiotemporal correlations. In this work, an extension of k-t principal component analysis is proposed utilizing signal differences between the velocity encodings of three-directional flow measurements to further compact the signal representation and hence improve reconstruction accuracy.

A CMR study of the effects of tissue edema and necrosis on left ventricular dyssynchrony in acute myocardial infarction: implications for cardiac resynchronization therapy.

Background: In acute myocardial infarction (AMI), both tissue necrosis and edema are present and both might be implicated in the development of intraventricular dyssynchrony. However, their relative contribution to transient dyssynchrony is not known. Cardiovascular magnetic resonance (CMR) can detect necrosis and edema with high spatial resolution and it can quantify dyssynchrony by tagging techniques.

Emotion suppression reduces hippocampal activity during successful memory encoding.

People suppressing their emotions while facing an emotional event typically remember it less well. However, the neural mechanisms underlying the impairing effect of emotion suppression on successful memory encoding are not well understood. Because successful memory encoding relies on the hippocampus and the amygdala, we hypothesized that memory impairments due to emotion suppression are associated with down-regulated activity in these brain areas.

Non-water-suppressed proton MR spectroscopy improves spectral quality in the human spinal cord.

Magnetic resonance spectroscopy enables insight into the chemical composition of spinal cord tissue. However, spinal cord magnetic resonance spectroscopy has rarely been applied in clinical work due to technical challenges, including strong susceptibility changes in the region and the small cord diameter, which distort the lineshape and limit the attainable signal to noise ratio. Hence, extensive signal averaging is required, which increases the likelihood of static magnetic field changes caused by subject motion (respiration, swallowing), cord motion, and scanner-induced frequency drift.

In vivo precision of bootstrap algorithms applied to diffusion tensor imaging data.

Purpose: To determine the precision for in vivo applications of model and non-model-based bootstrap algorithms for estimating the measurement uncertainty of diffusion parameters derived from diffusion tensor imaging data.

Materials And Methods: Four different bootstrap methods were applied to diffusion datasets acquired during 10 repeated imaging sessions. Measurement uncertainty was derived in eight manually selected regions of interest and in the entire brain white matter and gray matter.

Whole-heart dynamic three-dimensional magnetic resonance perfusion imaging for the detection of coronary artery disease defined by fractional flow reserve: determination of volumetric myocardial ischaemic burden and coronary lesion location.

Aims: Dynamic three-dimensional-cardiac magnetic resonance (3D-CMR) perfusion proved highly diagnostic for the detection of angiographically defined coronary artery disease (CAD) and has been used to assess the efficacy of coronary stenting procedures. The present study aimed to relate significant coronary lesions as assessed by fractional flow reserve (FFR) to the volume of myocardial hypoenhancement on 3D-CMR adenosine stress perfusion imaging and to define the inter-study reproducibility of stress inducible 3D-CMR hypoperfusion.

Methods And Results: A total of 120 patients with known or suspected CAD were examined in two CMR centres using 1.

Age-specific characteristics and coupling of cerebral arterial inflow and cerebrospinal fluid dynamics.

The objective of this work is to quantify age-related differences in the characteristics and coupling of cerebral arterial inflow and cerebrospinal fluid (CSF) dynamics. To this end, 3T phase-contrast magnetic resonance imaging blood and CSF flow data of eleven young (24 ± 3 years) and eleven elderly subjects (70 ± 5 years) with a comparable sex-ratio were acquired. Flow waveforms and their frequency composition, transfer functions from blood to CSF flows and cross-correlations were analyzed.

PKCα is genetically linked to memory capacity in healthy subjects and to risk for posttraumatic stress disorder in genocide survivors.

Strong memory of a traumatic event is thought to contribute to the development and symptoms of posttraumatic stress disorder (PTSD). Therefore, a genetic predisposition to build strong memories could lead to increased risk for PTSD after a traumatic event. Here we show that genetic variability of the gene encoding PKCα (PRKCA) was associated with memory capacity--including aversive memory--in nontraumatized subjects of European descent.

Unconscious relational inference recruits the hippocampus.

Relational inference denotes the capacity to encode, flexibly retrieve, and integrate multiple memories to combine past experiences to update knowledge and improve decision-making in new situations. Although relational inference is thought to depend on the hippocampus and consciousness, we now show in young, healthy men that it may occur outside consciousness but still recruits the hippocampus. In temporally distinct and unique subliminal episodes, we presented word pairs that either overlapped ("winter-red", "red-computer") or not.

Optimizing the functional diffusion map using Monte Carlo simulations.

Purpose: To optimize the diagnostic accuracy of the functional diffusion map for monitoring tumor treatment response in cancer patients.

Materials And Methods: Using Monte Carlo simulations, measurement precision of the apparent diffusion coefficient (ADC), and particularly accuracy of threshold determination from healthy reference tissue, are evaluated by investigating the repeatability limit of the ADC as a function of different degrees of diffusion weighting of the sequence. Phantom and in-vivo experiments are performed to verify and illustrate the results of the simulations.