Fast three-dimensional inner volume excitations using parallel transmission and optimized k-space trajectories.

Purpose: To design short parallel transmission (pTx) pulses for excitation of arbitrary three-dimensional (3D) magnetization patterns.

Methods: We propose a joint optimization of the pTx radiofrequency (RF) and gradient waveforms for excitation of arbitrary 3D magnetization patterns. Our optimization of the gradient waveforms is based on the parameterization of k-space trajectories (3D shells, stack-of-spirals, and cross) using a small number of shape parameters that are well-suited for optimization.

N-octanoyl dopamine treatment exerts renoprotective properties in acute kidney injury but not in renal allograft recipients.

Background: N-octanoyl dopamine (NOD) treatment improves renal function when applied to brain dead donors and in the setting of warm ischaemia-induced acute kidney injury (AKI). Because it also activates transient receptor potential vanilloid type 1 (TRPV1) channels, we first assessed if NOD conveys its renoprotective properties in warm ischaemia-induced AKI via TRPV1 and secondly, if renal transplant recipients also benefit from NOD treatment.

Methods: We induced warm renal ischaemia in Lewis, wild-type (WT) and TRPV1(-/-) Sprague-Dawley (sd) rats by clamping the left renal artery for 45 min.

Heterogeneity of acute multiple sclerosis lesions on sodium (23Na) MRI.

Background: Advanced magnetic resonance imaging (MRI) techniques provide a window into pathological processes in multiple sclerosis (MS). Nevertheless, to date only few studies have performed sodium MRI in MS.

Objectives: We analysed total sodium concentration (TSC) in hyperacute, acute and chronic lesions in MS with (23)Na MRI.

Joint myocardial T1 and T2 mapping using a combination of saturation recovery and T2 -preparation.

Purpose: To develop a heart-rate independent breath-held joint T1 -T2 mapping sequence for accurate simultaneous estimation of coregistered myocardial T1 and T2 maps.

Methods: A novel preparation scheme combining both a saturation pulse and T2 -preparation in a single R-R interval is introduced. The time between these two pulses, as well as the duration of the T2 -preparation is varied in each heartbeat, acquiring images with different T1 and T2 weightings, and no magnetization dependence on previous images.

Three-dimensional accurate detection of lung emphysema in rats using ultra-short and zero echo time MRI.

Emphysema is a life-threatening pathology that causes irreversible destruction of alveolar walls. In vivo imaging techniques play a fundamental role in the early non-invasive pre-clinical and clinical detection and longitudinal follow-up of this pathology. In the present study, we aimed to evaluate the feasibility of using high resolution radial three-dimensional (3D) zero echo time (ZTE) and 3D ultra-short echo time (UTE) MRI to accurately detect lung pathomorphological changes in a rodent model of emphysema.

On the representation of cells in bone marrow pathology by a scalar field: propagation through serial sections, co-localization and spatial interaction analysis.

Background: Immunohistochemical analysis of cellular interactions in the bone marrow in situ is demanding, due to its heterogeneous cellular composition, the poor delineation and overlap of functional compartments and highly complex immunophenotypes of several cell populations (e.g. regulatory T-cells) that require immunohistochemical marker sets for unambiguous characterization.

Neural reward processing in individuals remitted from major depression.

Background: Dysfunctional behavioural and neural processing of reward has been found in currently depressed individuals. However, little is known about altered reward processing in remitted depressed individuals.

Method: A total of 23 medication-free individuals with remitted major depressive disorder (rMDD) and 23 matched healthy controls (HCs) performed a reward task during functional magnetic resonance imaging.

Semi-automatic lung segmentation of DCE-MRI data sets of 2-year old children after congenital diaphragmatic hernia repair: Initial results.

In congenital diaphragmatic hernia (CDH), lung hypoplasia and secondary pulmonary hypertension are the major causes of death and severe disability. Based on new therapeutic strategies survival rates could be improved to up to 80%. However, after surgical repair of CDH, long-term follow-up of these pediatric patients is necessary.

Comparison of automated brain segmentation using a brain phantom and patients with early Alzheimer's dementia or mild cognitive impairment.

Magnetic resonance imaging (MRI) and brain volumetry allow for the quantification of changes in brain volume using automatic algorithms which are widely used in both, clinical and scientific studies. However, studies comparing the reliability of these programmes are scarce and mainly involved MRI derived from younger healthy controls. This study evaluates the reliability of frequently used segmentation programmes (SPM, FreeSurfer, FSL) using a realistic digital brain phantom and MRI brain acquisitions from patients with manifest Alzheimer's disease (AD, n=34), mild cognitive impairment (MCI, n=60), and healthy subjects (n=32) matched for age and sex.

Multistage self-gated lung imaging in small rodents.

Purpose: To investigate the exploitation of the self-gating signal in ultrashort echo time (UTE) two-dimensional (2D) acquisitions of freely breathing rats to reconstruct multiple respiratory stages.

Methods: Twelve rats were investigated with a 2D golden angle UTE protocol (12 coronal slices, echo time 0.343 ms, repetition time 120 ms, thickness 1 mm, flip angle 30°, matrix 256 × 256, 20-fold oversampling).

Functional Proton MRI in Emphysematous Rats.

Objective: To demonstrate the feasibility of proton magnetic resonance imaging (MRI) ventilation-related maps in rodents for the evaluation of lung function in the presence of pancreatic porcine elastase (PPE)-induced emphysema.

Materials And Methods: Twelve rats were equally divided into 3 groups: group 1 (no administration of PPE); group 2 (PPE selectively only in the left lung); and group 3 (PPE administered in both lungs). Magnetic resonance imaging (MRI) and computed tomographic (CT) data were acquired at baseline, at 2 weeks and 4 weeks after administration, after which the animals were euthanized.

A double-tuned (1) H/(23) Na resonator allows (1) H-guided (23) Na-MRI in ischemic stroke patients in one session.

Background: Established imaging methods are still not confident in the determination of stroke onset. Sodium imaging in animal models and lately in humans implicates that the sodium signal intensity within the ischemic lesion increases in a time-dependent fashion. Sodium imaging usually requires a time-consuming change of resonators or magnetic resonance imaging systems.

Impact of motion correction on reproducibility and spatial variability of quantitative myocardial T2 mapping.

Background: To evaluate and quantify the impact of a novel image-based motion correction technique in myocardial T2 mapping in terms of measurement reproducibility and spatial variability.

Methods: Twelve healthy adult subjects were imaged using breath-hold (BH), free breathing (FB), and free breathing with respiratory navigator gating (FB + NAV) myocardial T2 mapping sequences. Fifty patients referred for clinical CMR were imaged using the FB + NAV sequence.

Continuous representation of tumor microvessel density and detection of angiogenic hotspots in histological whole-slide images.

Blood vessels in solid tumors are not randomly distributed, but are clustered in angiogenic hotspots. Tumor microvessel density (MVD) within these hotspots correlates with patient survival and is widely used both in diagnostic routine and in clinical trials. Still, these hotspots are usually subjectively defined.

Enhancing the quantification of tissue sodium content by MRI: time-efficient sodium B1 mapping at clinical field strengths.

Tissue sodium content (TSC) is a sensitive measure of pathological changes and can be detected non-invasively by MRI. For the absolute quantification of TSC, B1 inhomogeneities must be corrected, which is not well established beyond research applications. An in-depth analysis of B1 mapping methods which are suitable for application in TSC quantification is presented.

Sodium-23 MRI of whole spine at 3 Tesla using a 5-channel receive-only phased-array and a whole-body transmit resonator.

Sodium magnetic resonance imaging ((23)Na MRI) is a unique and non-invasive imaging technique which provides important information on cellular level about the tissue of the human body. Several applications for (23)Na MRI were investigated with regard to the examination of the tissue viability and functionality for example in the brain, the heart or the breast. The (23)Na MRI technique can also be integrated as a potential monitoring instrument after radiotherapy or chemotherapy.

Non-invasive quantitative pulmonary V/Q imaging using Fourier decomposition MRI at 1.5T.

Objectives: Techniques for quantitative pulmonary perfusion and ventilation using the Fourier Decomposition method were recently demonstrated. We combine these two techniques and show that ventilation-perfusion (V/Q) imaging is possible using only a single MR acquisition of less than thirty seconds.

Methods: The Fourier Decomposition method is used in combination with two quantification techniques, which extract baselines from within the images themselves and thus allows quantification.

Review of potential improvements using MRI in the radiotherapy workflow.

The goal of modern radiotherapy is to deliver a lethal amount of dose to tissue volumes that contain a significant amount of tumour cells while sparing surrounding unaffected or healthy tissue. Online image guided radiotherapy with stereotactic ultrasound, fiducial-based planar X-ray imaging or helical/conebeam CT has dramatically improved the precision of radiotherapy, with moving targets still posing some methodical problems regarding positioning. Therefore, requirements for precise target delineation and identification of functional body structures to be spared by high doses become more evident.

Quantitative sodium MRI of kidney.

One of the main tasks of the human kidneys is to maintain the homeostasis of the body's fluid and electrolyte balance by filtration of the plasma and excretion of the end products. Herein, the regulation of extracellular sodium in the kidney is of particular importance. Sodium MRI ((23)Na MRI) allows for the absolute quantification of the tissue sodium concentration (TSC) and thereby provides a direct link between TSC and tissue viability.

Brain morphology correlates of interindividual differences in conditioned fear acquisition and extinction learning.

The neural circuits underlying fear learning have been intensively investigated in pavlovian fear conditioning paradigms across species. These studies established a predominant role for the amygdala in fear acquisition, while the ventromedial prefrontal cortex (vmPFC) has been shown to be important in the extinction of conditioned fear. However, studies on morphological correlates of fear learning could not consistently confirm an association with these structures.

Neural Mechanism of a Sex-Specific Risk Variant for Posttraumatic Stress Disorder in the Type I Receptor of the Pituitary Adenylate Cyclase Activating Polypeptide.

Background: Posttraumatic stress disorder (PTSD) is a frequent anxiety disorder with higher prevalence rates in female patients than in male patients (2.5:1). Association with a single nucleotide polymorphism (rs2267735) in the gene ADCYAP1R1 encoding the type I receptor (PAC1-R) of the pituitary adenylate cyclase activating polypeptide has been reported with PTSD in female patients.

Comparison of grey matter volume and thickness for analysing cortical changes in chronic schizophrenia: a matter of surface area, grey/white matter intensity contrast, and curvature.

Grey matter volume and cortical thickness are the two most widely used measures for detecting grey matter morphometric changes in various diseases such as schizophrenia. However, these two measures only share partial overlapping regions in identifying morphometric changes. Few studies have investigated the contributions of the potential factors to the differences of grey matter volume and cortical thickness.

Altered neural reward and loss processing and prediction error signalling in depression.

Dysfunctional processing of reward and punishment may play an important role in depression. However, functional magnetic resonance imaging (fMRI) studies have shown heterogeneous results for reward processing in fronto-striatal regions. We examined neural responsivity associated with the processing of reward and loss during anticipation and receipt of incentives and related prediction error (PE) signalling in depressed individuals.

Sodium magnetic resonance imaging using ultra-short echo time sequences with anisotropic resolution and uniform k-space sampling.

A method for uniform k-space sampling of 3D ultra-short echo time (UTE) techniques with anisotropic resolution in one direction is introduced to increase signal-to-noise ratio (SNR). State-of-the-art acquisition schemes for sodium MRI with radial (projection reconstruction) and twisting (twisted projection imaging (TPI)) trajectories are investigated regarding SNR efficiency, blurring behavior under T2(⁎) decay, and measurement time in case of anisotropic field-of-view and resolution. 3D radial and twisting trajectories are redistributed in k-space for UTE sodium MRI with homogeneous noise distribution and optimal SNR efficiency, if T2(⁎) decay can be neglected.