Dynamic 3-dimensional stress cardiac magnetic resonance perfusion imaging: detection of coronary artery disease and volumetry of myocardial hypoenhancement before and after coronary stenting.

Objectives: The aim of this study was to establish a new, dynamic 3-dimensional cardiac magnetic resonance (3D-CMR) perfusion scan technique exploiting data correlation in k-space and time with sensitivity-encoding and to determine its value for the detection of coronary artery disease (CAD) and volumetry of myocardial hypoenhancement (VOLUME(hypo)) before and after percutaneous coronary stenting.

Background: Dynamic 3D-CMR perfusion imaging might improve detection of myocardial perfusion deficits and could facilitate direct volumetry of myocardial hypoenhancement.

Methods: In 146 patients with known or suspected CAD, a 3.

High-resolution magnetic resonance myocardial perfusion imaging at 3.0-Tesla to detect hemodynamically significant coronary stenoses as determined by fractional flow reserve.

Objectives: The objective of this study was to compare visual and quantitative analysis of high spatial resolution cardiac magnetic resonance (CMR) perfusion at 3.0-T against invasively determined fractional flow reserve (FFR).

Background: High spatial resolution CMR myocardial perfusion imaging for the detection of coronary artery disease (CAD) has recently been proposed but requires further clinical validation.

High resolution 3D cardiac perfusion imaging using compartment-based k-t PCA.

k-t PCA is a a regularized image reconstruction method to recover images from highly undersampled dynamic magnetic resonance data. It is based on the decomposition of the training and the undersampled data into temporally and spatially invariant terms using principal component analysis. In this paper, a compartment-based k-t PCA reconstruction approach is presented, with the objective of improving highly undersampled, high-resolution 3D myocardial perfusion magnetic resonance imaging (MRI) by constraining the temporal content of different spatial compartments in the image series based on the bolus arrival times and prior knowledge about the signal intensity-time curves.

Combining cardiac magnetic resonance and computed tomography coronary calcium scoring: added value for the assessment of morphological coronary disease?

To investigate prospectively, in patients with suspicion of coronary artery disease (CAD), the added value of coronary calcium scoring (CS) as adjunct to cardiac magnetic resonance (CMR) for the diagnosis of morphological coronary stenosis in comparison to catheter angiography (CA). Sixty consecutive patients (8 women; 64 ± 10 years) referred to CA underwent CMR (1.5 T) including perfusion and late gadolinium-enhancement imaging as well as CS with computed tomography.

Optimization of on-resonant magnetization transfer contrast in coronary vein MRI.

Magnetization transfer contrast has been used commonly for endogenous tissue contrast improvements in angiography, brain, body, and cardiac imaging. Both off-resonant and on-resonant RF pulses can be used to generate magnetization transfer based contrast. In this study, on-resonant magnetization transfer preparation using binomial pulses were optimized and compared with off-resonant magnetization transfer for imaging of coronary veins.

First-pass contrast-enhanced myocardial perfusion MRI in mice on a 3-T clinical MR scanner.

First-pass contrast-enhanced myocardial perfusion MRI in rodents has so far not been possible due to the temporal and spatial resolution requirements. We developed a new first-pass perfusion MR method for rodent imaging on a clinical 3.0-T scanner (Philips Healthcare, Best, The Netherlands) that employed 10-fold k-space and time domain undersampling with constrained image reconstruction, using temporal basis sets (k-t principle component analysis) to achieve a spatial resolution of 0.

High resolution three-dimensional cardiac perfusion imaging using compartment-based k-t principal component analysis.

Three-dimensional myocardial perfusion imaging requires significant acceleration of data acquisition to achieve whole-heart coverage with adequate spatial and temporal resolution. The present article introduces a compartment-based k-t principal component analysis reconstruction approach, which permits three-dimensional perfusion imaging at 10-fold nominal acceleration. Using numerical simulations, it is shown that the compartment-based method results in accurate representations of dynamic signal intensity changes with significant improvements of temporal fidelity in comparison to conventional k-t principal component analysis reconstructions.

In vivo human 3D cardiac fibre architecture: reconstruction using curvilinear interpolation of diffusion tensor images.

In vivo imaging of the cardiac 3D fibre architecture is still a challenge, but it would have many clinical applications, for instance to better understand pathologies and to follow up remodelling after therapy. Recently, cardiac MRI enabled the acquisition of Diffusion Tensor images (DTI) of 2D slices. We propose a method for the complete 3D reconstruction of cardiac fibre architecture in the left ventricular myocardium from sparse in vivo DTI slices.

Effect of improving spatial or temporal resolution on image quality and quantitative perfusion assessment with k-t SENSE acceleration in first-pass CMR myocardial perfusion imaging.

k-t Sensitivity-encoded (k-t SENSE) acceleration has been used to improve spatial resolution, temporal resolution, and slice coverage in first-pass cardiac magnetic resonance myocardial perfusion imaging. This study compares the effect of investing the speed-up afforded by k-t SENSE acceleration in spatial or temporal resolution. Ten healthy volunteers underwent adenosine stress myocardial perfusion imaging using four saturation-recovery gradient echo perfusion sequences: a reference sequence accelerated by sensitivity encoding (SENSE), and three k-t SENSE-accelerated sequences with higher spatial resolution ("k-t High"), shorter acquisition window ("k-t Fast"), or a shared increase in both parameters ("k-t Hybrid") relative to the reference.

Coronary artery disease: which degree of coronary artery stenosis is indicative of ischemia?

Purpose: To prospectively determine the best cut-off value of stenosis degree for low-dose computed tomography coronary angiography (CTCA) to predict the hemodynamic significance of coronary artery stenoses compared to catheter angiography (CA) using a cardiac magnetic resonance based approach as standard of reference.

Materials And Methods: Fifty-two patients (mean age, 64±10 years) scheduled for CA underwent cardiac magnetic resonance (CMR) at 1.5-T and dual-source CTCA using prospective ECG-triggering the same day.

Clinical feasibility of accelerated, high spatial resolution myocardial perfusion imaging.

Objectives: The aim of this study was to assess the clinical feasibility and diagnostic performance of an acceleration technique based on k-space and time (k-t) sensitivity encoding (SENSE) for rapid, high-spatial resolution cardiac magnetic resonance (CMR) myocardial perfusion imaging.

Background: The assessment of myocardial perfusion is of crucial importance in the evaluation of patients with known or suspected coronary artery disease. CMR myocardial perfusion imaging performs favorably compared to single photon-emission computed tomography and offers higher spatial resolution, particularly when combined with scan acceleration techniques such as k-t SENSE.

Comparison of k-t SENSE/k-t BLAST with conventional SENSE applied to BOLD fMRI.

Purpose: To compare k-t BLAST (broad-use linear-acquisition speedup technique)/k-t SENSE (sensitivity encoding) with conventional SENSE applied to a simple fMRI paradigm.

Materials And Methods: Blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) was performed at 3 T using a displaced ultra-fast low-angle refocused echo (UFLARE) pulse sequence with a visual stimulus in a block paradigm. Conventional SENSE and k-t BLAST/k-t SENSE data were acquired.

Performance of simultaneous cardiac-respiratory self-gated three-dimensional MR imaging of the heart: initial experience.

This study was approved by the local institutional ethics committee, and informed consent was obtained from all volunteers and patients. The objective of the present study was to assess the performance of high-spatial-resolution three-dimensional prospective cardiac-respiratory self-gated (CRSG) magnetic resonance (MR) imaging for determining left ventricular (LV) volumes and mass, as well as right ventricular (RV) volumes, in comparison with standard electrocardiography (ECG)-triggered, two-dimensional multisection, multiple-breath-hold cine imaging. The self-gated method derives cardiac triggering and respiratory gating information prospectively on the basis of additional MR imaging signals acquired in every repetition time and, thereby, eliminates the need for ECG triggering and multiple-breath-hold procedures.

Image fusion of coronary CT angiography and cardiac perfusion MRI: a pilot study.

Objective: To develop a tool for the image fusion of computed tomography coronary angiography (CTCA) and cardiac magnetic resonance imaging (CMR).

Methods: Surface representations and volume-rendered images from fused CTCA/CMR data of five patients with significant coronary artery disease (CAD) on CTCA and perfusion deficits on CMR were generated using a newly developed software prototype. The spatial relationship of significant coronary artery stenosis at CTCA and myocardial defects at CMR was evaluated.

Low-dose CT and cardiac MR for the diagnosis of coronary artery disease: accuracy of single and combined approaches.

To prospectively compare the diagnostic performance of low-dose computed tomography coronary angiography (CTCA) and cardiac magnetic resonance imaging (CMR) and combinations thereof for the diagnosis of significant coronary stenoses. Forty-three consecutive patients with known or suspected coronary artery disease underwent catheter coronary angiography (CA), dual-source CTCA with prospective electrocardiography-gating, and cardiac CMR (1.5 Tesla).

Low-dose CT coronary angiography for the prediction of myocardial ischaemia.

The purpose of this study was to prospectively determine the accuracy of low-dose computed tomography coronary angiography (CTCA) for the diagnosis of functionally relevant coronary artery disease (CAD) using cardiac magnetic resonance (CMR) as a standard of reference. Forty-one consecutive patients (age 64 +/- 10 years) underwent k-space and time broad-use linear acquisition speed-up technique accelerated CMR (1.5 T) and dual-source CTCA using prospective electrocardiography gating within 1 day.

Feasibility of cardiac gating free of interference with electro-magnetic fields at 1.5 Tesla, 3.0 Tesla and 7.0 Tesla using an MR-stethoscope.

Objectives: To circumvent the challenges of conventional electrocardiographic (ECG)-gating by examining the efficacy of an MR stethoscope, which offers (i) no risk of high voltage induction or patient burns, (ii) immunity to electromagnetic interference, (iii) suitability for all magnetic field strengths, and (iv) patient comfort together with ease of use for the pursuit of reliable and safe (ultra)high field cardiac gated magnetic resonance imaging (MRI).

Materials And Methods: The acoustic gating device consists of 3 main components: an acoustic sensor, a signal processing unit, and a coupler unit to the MRI system. Signal conditioning and conversion are conducted outside the 0.

Feasibility of k-t BLAST for BOLD fMRI with a spin-echo based acquisition at 3 T and 7 T.

Objectives: This study tested the feasibility of applying k-t BLAST to blood oxygen level dependent functional MRI of the brain at 3 Tesla (T) and at 7 T. Shorter echo train lengths, achieved through the application of k-t BLAST, are expected to counteract increased sensitivity to inhomogeneities in B0 at higher magnetic field strengths, especially in echo planar images, and reduce the relatively long acquisition times and high RF power deposition in spin-echo based methods.

Materials And Methods: k-t BLAST was combined with displaced UFLARE at 3 T and 7 T.

Three-dimensional alignment of the aggregated myocytes in the normal and hypertrophic murine heart.

Several observations suggest that the transmission of myocardial forces is influenced in part by the spatial arrangement of the myocytes aggregated together within ventricular mass. Our aim was to assess, using diffusion tensor magnetic resonance imaging (DT-MRI), any differences in the three-dimensional arrangement of these myocytes in the normal heart compared with the hypertrophic murine myocardium. We induced ventricular hypertrophy in seven mice by infusion of angiotensin II through a subcutaneous pump, with seven other mice serving as controls.

k-t PCA: temporally constrained k-t BLAST reconstruction using principal component analysis.

The k-t broad-use linear acquisition speed-up technique (BLAST) has become widespread for reducing image acquisition time in dynamic MRI. In its basic form k-t BLAST speeds up the data acquisition by undersampling k-space over time (referred to as k-t space). The resulting aliasing is resolved in the Fourier reciprocal x-f space (x = spatial position, f = temporal frequency) using an adaptive filter derived from a low-resolution estimate of the signal covariance.

Accelerated cardiac perfusion imaging using k-t SENSE with SENSE training.

In k-t sensitivity encoding (SENSE), MR data acquisition performed in parallel by multiple coils is accelerated by sparsely sampling the k-space over time. The resulting aliasing is resolved by exploiting spatiotemporal correlations inherent in dynamic images of natural objects. In this article, a modified k-t SENSE reconstruction approach is presented, which aims at improving the temporal fidelity of first-pass, contrast-enhanced myocardial perfusion images at high accelerations.

Toward true 3D visualization of active catheters using compressed sensing.

A crucial requirement in MR-guided interventions is the visualization of catheter devices in real time. However, true 3D visualization of the full length of catheters has hitherto been impossible given scan time constraints. Compressed sensing (CS) has recently been proposed as a method to accelerate MR imaging of sparse objects.

Myocardial T2* mapping free of distortion using susceptibility-weighted fast spin-echo imaging: a feasibility study at 1.5 T and 3.0 T.

This study demonstrates the feasibility of applying free-breathing, cardiac-gated, susceptibility-weighted fast spin-echo imaging together with black blood preparation and navigator-gated respiratory motion compensation for anatomically accurate T2* mapping of the heart. First, T2* maps are presented for oil phantoms without and with respiratory motion emulation T2* = (22.1 +/- 1.

Left ventricular dyssynchrony in patients with left bundle branch block and patients after myocardial infarction: integration of mechanics and viability by cardiac magnetic resonance.

Aims: To quantify left ventricular (LV) dyssynchrony in patients with left bundle branch block (LBBB) and in patients after myocardial infarction (MI) applying an accelerated three-dimensional (3D) tagging cardiac magnetic resonance (CMR) technique, and to combine dyssynchrony information with viability data obtained by late gadolinium enhancement (LGE) CMR.

Methods And Results: Thirty-two patients (59 +/- 11 years) after first MI (Pats(MI)), 10 patients (63 +/- 10 years) with LBBB (ejection fraction < 40%; Pats(LBBB<40)), 13 patients (63 +/- 11) with LBBB (ejection fraction >or= 40%; Pats(LBBB >or=40 )), and 15 healthy controls (53 +/- 10 years) underwent 3D tagging CMR and LGE imaging at 1.5 T.