Optimized protocol for high resolution functional magnetic resonance imaging at 3T using single-shot echo planar imaging.

Background: To translate highly accelerated EPI-fMRI protocols as commonly used at ultra-high field strengths to clinical 3T settings.

New Method: EPI protocols with increasing matrix sizes and parallel imaging (PI) factors were tested in two separate fMRI studies, a simple motor-task and a complex motivation-task experiment with focus on the sensorimotor cortex (SMC) and the nucleus accumbens (NAcc), respectively.

Results: By increasing the matrix size and the PI-factor simultaneously, BOLD-sensitivity in terms of maximal t-values and numbers of activated clusters was uncompromised in single individuals in both fMRI experiments.

Neurofeedback of the difference in activation of the anterior cingulate cortex and posterior insular cortex: two functionally connected areas in the processing of pain.

The aim of this study was the analysis of the effect of a learned increase in the dissociation between the rostral anterior cingulate cortex (rACC) and the left posterior insula (pInsL) on pain intensity and unpleasantness and the contribution of each region to the effect, exploring the possibility to influence the perception of pain with neurofeedback methods. We trained ten healthy subjects to increase the difference in the blood oxygenation level-dependent response between the rACC and pInsL to painful electric stimuli. Subjects learned to increase the dissociation with either the rACC (state 1) or the pInsL (state 2) being higher.

Free-breathing combined three-dimensional phase sensitive late gadolinium enhancement and T1 mapping for myocardial tissue characterization.

Purpose: To develop a novel MR sequence for combined three-dimensional (3D) phase-sensitive (PS) late gadolinium enhancement (LGE) and T1 mapping to allow for simultaneous assessment of focal and diffuse myocardial fibrosis.

Methods: In the proposed sequence, four 3D imaging volumes are acquired with different T1 weightings using a combined saturation and inversion preparation, after administration of a gadolinium contrast agent. One image is acquired fully sampled with the inversion time selected to null the healthy myocardial signal (the LGE image).

Scan time reduction in ²³Na-Magnetic Resonance Imaging using the chemical shift imaging sequence: Evaluation of an iterative reconstruction method.

Aim: To evaluate potential scan time reduction in (23)Na-Magnetic Resonance Imaging with the chemical shift imaging sequence (CSI) using undersampled data of high-quality datasets, reconstructed with an iterative constrained reconstruction, compared to reduced resolution or reduced signal-to-noise ratio.

Materials And Methods: CSI (23)Na-images were retrospectively undersampled and reconstructed with a constrained reconstruction scheme. The results were compared to conventional methods of scan time reduction.

Free-breathing multislice native myocardial T mapping using the slice-interleaved T (STONE) sequence.

Purpose: To develop a novel pulse sequence for free-breathing, multislice, native myocardial T mapping.

Methods: The slice-interleaved T (STONE) sequence consists of multiple sets of single-shot images of different slices, acquired after a single nonselective inversion pulse. Each slice is only selectively excited once after each inversion pulse to allow sampling of the unperturbed longitudinal magnetization in the adjacent slices.

Improved quantitative myocardial T mapping: Impact of the fitting model.

Purpose: To develop an improved T prepared (T prep) balanced steady-state free-precession (bSSFP) sequence and signal relaxation curve fitting method for myocardial T mapping.

Methods: Myocardial T mapping is commonly performed by acquisition of multiple T prep bSSFP images and estimating the voxel-wise T values using a two-parameter fit for relaxation. However, a two-parameter fit model does not take into account the effect of imaging pulses in a bSSFP sequence or other imperfections in T prep RF pulses, which may decrease the robustness of T mapping.

Pre-clinical functional Magnetic Resonance Imaging Part II: The heart.

One third of all deaths worldwide in 2008 were caused by cardiovascular diseases (CVD), and the incidence of CVD related deaths rises ever more. Thus, improved imaging techniques and modalities are needed for the evaluation of cardiac morphology and function. Cardiac magnetic resonance imaging (CMRI) is a minimally invasive technique that is increasingly important due to its high spatial and temporal resolution, its high soft tissue contrast and its ability of functional and quantitative imaging.

Pre-clinical functional Magnetic Resonance Imaging Part I: The kidney.

The prevalence of chronic kidney disease (CKD) is increasing worldwide. In Europe alone, at least 8% of the population currently has some degree of CKD. CKD is associated with serious comorbidity, reduced life expectancy, and high economic costs; hence, the early detection and adequate treatment of kidney disease is important.

Fourier decomposition pulmonary MRI using a variable flip angle balanced steady-state free precession technique.

Purpose: Fourier decomposition (FD) is a noninvasive method for assessing ventilation and perfusion-related information in the lungs. However, the technique has a low signal-to-noise ratio (SNR) in the lung parenchyma. We present an approach to increase the SNR in both morphological and functional images.

Non-invasive multiparametric qBOLD approach for robust mapping of the oxygen extraction fraction.

Introduction: The quantitative blood oxygenation level-dependent (qBOLD) method has not become clinically established yet because long acquisition times are necessary to achieve an acceptable certainty of the parameter estimates. In this work, a non-invasive multiparametric (nimp) qBOLD approach based on a simple analytical model is proposed to facilitate robust oxygen extraction fraction (OEF) mapping within clinically acceptable acquisition times by using separate measurements.

Methods: The protocol consisted of a gradient-echo sampled spin-echo sequence (GESSE), a T2-weighted Carr-Purcell-Meiboom-Gill (CPMG) sequence, and a T2(*)-weighted multi-slice multi-echo gradient echo (MMGE) sequence.

Renal perfusion in acute kidney injury with DCE-MRI: deconvolution analysis versus two-compartment filtration model.

Purpose: To investigate the results of different pharmacokinetic models of a quantitative analysis of renal blood flow (RBF) in acute kidney injury using deconvolution analysis and a two-compartment renal filtration model.

Materials And Methods: MRI data of ten male Lewis rats were analyzed retrospectively. Six animals were subjected to unilateral acute kidney injury and underwent perfusion imaging by dynamic contrast-enhanced MRI (DCE-MRI).

Functional imaging of acute kidney injury at 3 Tesla: investigating multiple parameters using DCE-MRI and a two-compartment filtration model.

Object: To investigate how MR-based parameters reflect functional changes in kidneys with acute kidney injury (AKI) using dynamic contrast enhanced MRI and a two-compartment renal filtration model.

Materials And Methods: MRI data of eight male Lewis rats were analyzed retrospectively. Five animals were subjected to AKI, three native rats served as control.

Fully-automated quality assurance in multi-center studies using MRI phantom measurements.

Phantom measurements allow for investigating the overall quality characteristics of an MRI scanner. Especially within multicenter studies, these characteristics ensure the comparability of the results across different sites, in addition to the performance stability of a single scanner over time. This comparability requires consistent phantoms, sequence protocols, and quality assurance criteria.

Free-breathing post-contrast three-dimensional T1 mapping: Volumetric assessment of myocardial T1 values.

Purpose: To develop a three-dimensional (3D) free-breathing myocardial T1 mapping sequence for assessment of left ventricle diffuse fibrosis after contrast administration.

Methods: In the proposed sequence, multiple 3D inversion recovery images are acquired in an interleaved manner. A mixed prospective/retrospective navigator scheme is used to obtain the 3D Cartesian k-space data with fully sampled center and randomly undersampled outer k-space.

Quantitative lung ventilation using Fourier decomposition MRI; comparison and initial study.

Objective: The Fourier decomposition (FD) method is a noninvasive method for assessing ventilation and perfusion-related information in the lungs, but the lack of quantifiable values is a drawback. We demonstrate a novel technique for quantification of the FD ventilation maps, compare it to two published methods, and show results from both healthy volunteers and patients diagnosed with lung cancer.

Materials And Methods: We quantified the standard FD ventilation images by utilizing additional information, i.

23Na-magnetic resonance imaging of the human lumbar vertebral discs: in vivo measurements at 3.0 T in healthy volunteers and patients with low back pain.

Background Context: 1H magnetic resonance imaging (MRI) of the spine can rule out common causes of low back pain (LBP), such as disc protrusions or nerve root compression; however, no significant causal relation exists between morphology and the extent of symptoms. Functional MRI techniques, such as 23Na, may provide additional information, allowing indirect assessment of vertebral glycosaminoglycan concentrations, decreases in which are associated with early degenerative changes.

Purpose: To evaluate 23Na-MRI of asymptomatic healthy volunteers and symptomatic patients with LPB and correlate the results to the Pfirrmann classification of MRI disc morphology.

30 Years of sodium/X-nuclei magnetic resonance imaging.

In principle, all nuclei with nonzero spin can be employed for magnetic resonance imaging (MRI). Special scanner hardware and MR sequences are required to select the nucleus-specific frequency and to enable imaging with "sufficient" signal-to-noise ratio. This Special Issue starts with an overview of different nuclei that can be used for MRI today, followed by a review article about techniques required for imaging of quadrupolar nuclei with short relaxation times.

Simultaneous measurement of kidney function by dynamic contrast enhanced MRI and FITC-sinistrin clearance in rats at 3 tesla: initial results.

Glomerular filtration rate (GFR) is an essential parameter of kidney function which can be measured by dynamic contrast enhanced magnetic resonance imaging (MRI-GFR) and transcutaneous approaches based on fluorescent tracer molecules (optical-GFR). In an initial study comparing both techniques in separate measurements on the same animal, the correlation of the obtained GFR was poor. The goal of this study was to investigate if a simultaneous measurement was feasible and if thereby, the discrepancies in MRI-GFR and optical-GFR could be reduced.

Quantitative lung perfusion evaluation using Fourier decomposition perfusion MRI.

Purpose: To quantitatively evaluate lung perfusion using Fourier decomposition perfusion MRI. The Fourier decomposition (FD) method is a noninvasive method for assessing ventilation- and perfusion-related information in the lungs, where the perfusion maps in particular have shown promise for clinical use. However, the perfusion maps are nonquantitative and dimensionless, making follow-ups and direct comparisons between patients difficult.

Measurement techniques for magnetic resonance imaging of fast relaxing nuclei.

In this review article, techniques for sodium ((23)Na) magnetic resonance imaging (MRI) are presented. These techniques can also be used to image other nuclei with short relaxation times (e.g.

Cortico-subcortical activation patterns for itch and pain imagery.

The imagery of itch and pain evokes emotional responses and covert motor responses (scratching to itch and withdrawal to pain). This suggests some similarity in cerebral mechanisms. However, itch is more socially contagious than pain, as evidenced by the fact that scratching behaviors can be easily initiated by watching itch-inducing situations, whereas withdrawal is less easily initiated by watching painful situations.

Combined saturation/inversion recovery sequences for improved evaluation of scar and diffuse fibrosis in patients with arrhythmia or heart rate variability.

Purpose: To develop arrhythmia-insensitive inversion recovery sequences for improved visualization of myocardial scar and quantification of diffuse fibrosis.

Methods: A novel preparation pre-pulse, called saturation pulse prepared heart-rate-independent inversion recovery, is introduced, which consists of a combination of saturation and inversion pulses to remove the magnetization history in each heartbeat in late gadolinium enhancement (LGE) imaging and eliminate the need for rest periods in T1 mapping. The proposed LGE and T1 mapping sequences were evaluated against conventional LGE and modified Look-Locker inversion sequences using numerical simulations, phantom and imaging in healthy subjects and patients with suspected or known cardiovascular disease.

In vitro mapping of 1H ultrashort T2* and T2 of porcine menisci.

In this study, mapping of ultrashort T2 and T2* of acutely isolated porcine menisci at B0 = 9.4 T was investigated. Maps of T2 were measured from a slice through the pars intermedia with a spin echo-prepared two-dimensional ultrashort-TE T2 mapping technique published previously.