STEAM-SASHA: a novel approach for blood- and fat-suppressed native T1 measurement in the right ventricular myocardium.

Objective: The excellent blood and fat suppression of stimulated echo acquisition mode (STEAM) can be combined with saturation recovery single-shot acquisition (SASHA) in a novel STEAM-SASHA sequence for right ventricular (RV) native T1 mapping.

Materials And Methods: STEAM-SASHA splits magnetization preparation over two cardiac cycles, nulling blood signal and allowing fat signal to decay. Breath-hold T1 mapping was performed in a T1 phantom and twice in 10 volunteers using STEAM-SASHA and a modified Look-Locker sequence at peak systole at 3T.

Field camera input to virtual phantom (ViP) scanner acquisitions for quality assurance of derived MRI quantities: first implementation and proof-of-principle.

Introduction: Quality assurance (QA) of measurements derived from MRI can require complicated test phantoms. This work introduces a new QA concept using gradient and transmit RF recordings by a limited field camera (FC) to govern the previous Virtual Phantom (ViP) method. The purpose is to describe the first technical implementation of combined FC+ViP, and illustrate its performance in examples, including quantitative first-pass myocardial perfusion.

Influence of right coronary artery motion, flow pulsatility and non-Newtonian rheology on wall shear stress metrics.

The patchy distribution of atherosclerosis within the arterial system is consistent with a controlling influence of hemodynamic wall shear stress (WSS). Patterns of low, oscillatory and transverse WSS have been invoked to explain the distribution of disease in the aorta. Disease of coronary arteries has greater clinical importance but blood flow in these vessels may be complicated by their movement during the cardiac cycle.

Minimisation of slab-selective radiofrequency excitation pulse durations constrained by an acceptable aliasing coefficient.

A technical note is presented on the slab-direction aliasing of 3D imaging, introducing a simple methodology for determining the minimised duration of low flip-angle sinc radiofrequency (RF) excitation pulses, with respect to a required slab profile accuracy. The various interdependent factors affected in modifying an RF pulse duration are considered and analysed in the context of a new metric for quantifying the levels of permitted slab-aliasing. A general framework is presented for the selection of standard sinc RF excitation pulses with system-minimised durations, as well as their analysis and validation, and a demonstration of this methodology is performed for an example requirement and scanner.

Initial investigation of free-breathing 3D whole-heart stress myocardial perfusion MRI.

Myocardial first-pass perfusion imaging with MRI is well-established clinically. However, it is potentially weakened by limited myocardial coverage compared to nuclear medicine. Clinical evaluations of whole-heart MRI perfusion by 3D methods, while promising, have to date had the limit of breathhold requirements at stress.

Quantitative 3D myocardial perfusion with an efficient arterial input function.

Purpose: The purpose of this study was to further develop and combine several innovative sequence designs to achieve quantitative 3D myocardial perfusion. These developments include an optimized 3D stack-of-stars readout (150 ms per beat), efficient acquisition of a 2D arterial input function, tailored saturation pulse design, and potential whole heart coverage during quantitative stress perfusion.

Theory And Methods: All studies were performed free-breathing on a Prisma 3T MRI scanner.

In-vivo validation of interpolation-based phase offset correction in cardiovascular magnetic resonance flow quantification: a multi-vendor, multi-center study.

Background: A velocity offset error in phase contrast cardiovascular magnetic resonance (CMR) imaging is a known problem in clinical assessment of flow volumes in vessels around the heart. Earlier studies have shown that this offset error is clinically relevant over different systems, and cannot be removed by protocol optimization. Correction methods using phantom measurements are time consuming, and assume reproducibility of the offsets which is not the case for all systems.

High resolution in-vivo DT-CMR using an interleaved variable density spiral STEAM sequence.

Purpose: Diffusion tensor cardiovascular magnetic resonance (DT-CMR) has a limited spatial resolution. The purpose of this study was to demonstrate high-resolution DT-CMR using a segmented variable density spiral sequence with correction for motion, off-resonance, and T2*-related blurring.

Methods: A single-shot stimulated echo acquisition mode (STEAM) echo-planar-imaging (EPI) DT-CMR sequence at 2.

Magnetic resonance imaging: Physics basics for the cardiologist.

Magnetic resonance imaging physics can be a complex and challenging topic for the practising cardiologist. Its evolving nature and the increasing number of novel sequences used in clinical scanning have been topics of excellent reviews; however, the basic understanding of physics underlying the creation of images remains difficult for many cardiologists. In this review, we go back to the basic physics theories underpinning magnetic resonance and explain their application and use in achieving good quality cardiac imaging, whilst describing established and novel magnetic resonance sequences.

An in-vivo comparison of stimulated-echo and motion compensated spin-echo sequences for 3 T diffusion tensor cardiovascular magnetic resonance at multiple cardiac phases.

Background: Stimulated-echo (STEAM) and, more recently, motion-compensated spin-echo (M2-SE) techniques have been used for in-vivo diffusion tensor cardiovascular magnetic resonance (DT-CMR) assessment of cardiac microstructure. The two techniques differ in the length scales of diffusion interrogated, their signal-to-noise ratio efficiency and sensitivity to both motion and strain. Previous comparisons of the techniques have used high performance gradients at 1.

Towards accurate and precise T and extracellular volume mapping in the myocardium: a guide to current pitfalls and their solutions.

Mapping of the longitudinal relaxation time (T ) and extracellular volume (ECV) offers a means of identifying pathological changes in myocardial tissue, including diffuse changes that may be invisible to existing T -weighted methods. This technique has recently shown strong clinical utility for pathologies such as Anderson-Fabry disease and amyloidosis and has generated clinical interest as a possible means of detecting small changes in diffuse fibrosis; however, scatter in T and ECV estimates offers challenges for detecting these changes, and bias limits comparisons between sites and vendors. There are several technical and physiological pitfalls that influence the accuracy (bias) and precision (repeatability) of T and ECV mapping methods.

Myocardial Architecture, Mechanics, and Fibrosis in Congenital Heart Disease.

Congenital heart disease (CHD) is the most common category of birth defect, affecting 1% of the population and requiring cardiovascular surgery in the first months of life in many patients. Due to advances in congenital cardiovascular surgery and patient management, most children with CHD now survive into adulthood. However, residual and postoperative defects are common resulting in abnormal hemodynamics, which may interact further with scar formation related to surgical procedures.

Apheresis as novel treatment for refractory angina with raised lipoprotein(a): a randomized controlled cross-over trial.

Aims: To determine the clinical impact of lipoprotein apheresis in patients with refractory angina and raised lipoprotein(a) > 500 mg/L on the primary end point of quantitative myocardial perfusion, as well as secondary end points including atheroma burden, exercise capacity, symptoms, and quality of life.

Methods: We conducted a single-blinded randomized controlled trial in 20 patients with refractory angina and raised lipoprotein(a) > 500 mg/L, with 3 months of blinded weekly lipoprotein apheresis or sham, followed by crossover. The primary endpoint was change in quantitative myocardial perfusion reserve (MPR) assessed by cardiovascular magnetic resonance.

Effects of renal denervation on vascular remodelling in patients with heart failure and preserved ejection fraction: A randomised control trial.

Objective: To assess the effect of renal denervation (RDT) on micro- and macro-vascular function in patients with heart failure with preserved ejection fraction (HFpEF).

Design: A prospective, randomised, open-controlled trial with blinded end-point analysis.

Setting: A single-centre London teaching hospital.

Assessment of Myocardial Microstructural Dynamics by In Vivo Diffusion Tensor Cardiac Magnetic Resonance.

Background: Cardiomyocytes are organized in microstructures termed sheetlets that reorientate during left ventricular thickening. Diffusion tensor cardiac magnetic resonance (DT-CMR) may enable noninvasive interrogation of in vivo cardiac microstructural dynamics. Dilated cardiomyopathy (DCM) is a condition of abnormal myocardium with unknown sheetlet function.

CMR Guidance for Recanalization of Coronary Chronic Total Occlusion.

Objectives: This study explored whether cardiac magnetic resonance (CMR) could help select patients who could benefit from revascularization by identifying inducible myocardial ischemia and viability in the perfusion territory of the artery with chronic total occlusion (CTO).

Background: The benefit of revascularization using percutaneous coronary intervention (PCI) in CTO is controversial. CMR offers incomparable left ventricular (LV) systolic function assessment in addition to potent ischemic burden quantification and reliable myocardial viability analysis.

Cardiovascular magnetic resonance phase contrast imaging.

Cardiovascular magnetic resonance (CMR) phase contrast imaging has undergone a wide range of changes with the development and availability of improved calibration procedures, visualization tools, and analysis methods. This article provides a comprehensive review of the current state-of-the-art in CMR phase contrast imaging methodology, clinical applications including summaries of past clinical performance, and emerging research and clinical applications that utilize today's latest technology.

A review of 3D first-pass, whole-heart, myocardial perfusion cardiovascular magnetic resonance.

A comprehensive review is undertaken of the methods available for 3D whole-heart first-pass perfusion (FPP) and their application to date, with particular focus on possible acceleration techniques. Following a summary of the parameters typically desired of 3D FPP methods, the review explains the mechanisms of key acceleration techniques and their potential use in FPP for attaining 3D acquisitions. The mechanisms include rapid sequences, non-Cartesian k-space trajectories, reduced k-space acquisitions, parallel imaging reconstructions and compressed sensing.

Heterogeneity of Fractional Anisotropy and Mean Diffusivity Measurements by In Vivo Diffusion Tensor Imaging in Normal Human Hearts.

Background: Cardiac diffusion tensor imaging (cDTI) by cardiovascular magnetic resonance has the potential to assess microstructural changes through measures of fractional anisotropy (FA) and mean diffusivity (MD). However, normal variation in regional and transmural FA and MD is not well described.

Methods: Twenty normal subjects were scanned using an optimised cDTI sequence at 3T in systole.

Improved dynamic parallel imaging coil calibration method robust to respiratory motion with application to first-pass contrast-enhanced myocardial perfusion imaging.

Purpose: To develop an accurate method of performing free-breathing coil calibration for application to parallel imaging reconstructions of dynamic single-shot datasets.

Methods: Coil calibration data are produced through acquisition of multiple prescans before the accelerated scan, applied during free-breathing. These multiple free-breathing prescans (MFPs) provide the necessary coil information for accurate parallel imaging reconstruction of each accelerated frame of a dynamic series, under guidance of an appropriate respiratory position based matching algorithm.

In vivo cardiovascular magnetic resonance diffusion tensor imaging shows evidence of abnormal myocardial laminar orientations and mobility in hypertrophic cardiomyopathy.

Background: Cardiac diffusion tensor imaging (cDTI) measures the magnitudes and directions of intramyocardial water diffusion. Assuming the cross-myocyte components to be constrained by the laminar microstructures of myocardium, we hypothesized that cDTI at two cardiac phases might identify any abnormalities of laminar orientation and mobility in hypertrophic cardiomyopathy (HCM).

Methods: We performed cDTI in vivo at 3 Tesla at end-systole and late diastole in 11 healthy controls and 11 patients with HCM, as well as late gadolinium enhancement (LGE) for detection of regional fibrosis.

Magnetic resonance imaging of vein wall thickness in patients with Behçet's syndrome.

Objectives: Vascular disease is a serious complication of Behçet's syndrome (BS), occurring in up to 20% of subjects. Superficial thrombophlebitis, deep vein thrombosis, and arterial aneurysm formation are the most common manifestations. Venous thrombosis is thought to result from vessel wall inflammation.

Free-breathing 3D late gadolinium enhancement imaging of the left ventricle using a stack of spirals at 3T.

Purpose: To develop navigator-gated free-breathing 3D spiral late gadolinium enhancement (LGE) imaging of the left ventricle at 3T and compare it with conventional breath-hold 2D Cartesian imaging.

Materials And Methods: Equivalent slices from 3D spiral and multislice 2D Cartesian acquisitions were compared in 15 subjects in terms of image quality (1, nondiagnostic to 5, excellent), sharpness (1-3), and presence of artifacts (0-2). Blood signal-to-noise ratio (SNR), blood/myocardium contrast-to-noise ratio (CNR), and quantitative sharpness were also compared.