Compartment-based reconstruction of 3D acquisition-weighted P cardiac magnetic resonance spectroscopic imaging at 7 T: A reproducibility study.

Even at 7 T, cardiac P magnetic resonance spectroscopic imaging (MRSI) is fundamentally limited by low signal-to-noise ratio (SNR), leading to long scan times and poor temporal and spatial resolutions. Compartment-based reconstruction algorithms such as magnetic resonance spectroscopy with linear algebraic modeling (SLAM) and spectral localization by imaging (SLIM) may improve SNR or reduce scan time without changes to acquisition. Here, we compare the repeatability and SNR performance of these compartment-based methods, applied to three different acquisition schemes at 7 T.

Myocardial ATP depletion detected noninvasively predicts sudden cardiac death risk in patients with heart failure.

BACKGROUNDSudden cardiac death (SCD) remains a worldwide public health problem in need of better noninvasive predictive tools. Current guidelines for primary preventive SCD therapies, such as implantable cardioverter defibrillators (ICDs), are based on left ventricular ejection fraction (LVEF), but these guidelines are imprecise: fewer than 5% of ICDs deliver lifesaving therapy per year. Impaired cardiac metabolism and ATP depletion cause arrhythmias in experimental models, but to our knowledge a link between arrhythmias and cardiac energetic abnormalities in people has not been explored, nor has the potential for metabolically predicting clinical SCD risk.

Real-Time High-Resolution MRI Endoscopy at up to 10 Frames per Second.

. Atherosclerosis is a leading cause of mortality and morbidity. Optical endoscopy, ultrasound, and X-ray offer minimally invasive imaging assessments but have limited sensitivity for characterizing disease and therapeutic response.

Rapid, -insensitive, dual-band quasi-adiabatic saturation transfer with optimal control for complete quantification of myocardial ATP flux.

Purpose: Phosphorus saturation-transfer experiments can quantify metabolic fluxes noninvasively. Typically, the forward flux through the creatine kinase reaction is investigated by observing the decrease in phosphocreatine (PCr) after saturation of γ-ATP. The quantification of total ATP utilization is currently underexplored, as it requires simultaneous saturation of inorganic phosphate ( ) and PCr.

Exercise intolerance and rapid skeletal muscle energetic decline in human age-associated frailty.

BACKGROUNDPhysical frailty in older individuals is characterized by subjective symptoms of fatigue and exercise intolerance (EI). Objective abnormalities in skeletal muscle (SM) mitochondrial high-energy phosphate (HEP) metabolism contribute to EI in inherited myopathies; however, their presence or link to EI in the frail older adult is unknown.METHODSHere, we studied 3 groups of ambulatory, community-dwelling adults with no history of significant coronary disease: frail older (FO) individuals (81 ± 2.

High-resolution intravascular MRI-guided perivascular ultrasound ablation.

Purpose: To develop and test in animal studies ex vivo and in vivo, an intravascular (IV) MRI-guided high-intensity focused ultrasound (HIFU) ablation method for targeting perivascular pathology with minimal injury to the vessel wall.

Methods: IV-MRI antennas were combined with 2- to 4-mm diameter water-cooled IV-ultrasound ablation catheters for IV-MRI on a 3T clinical MRI scanner. A software interface was developed for monitoring thermal dose with real-time MRI thermometry, and an MRI-guided ablation protocol developed by repeat testing on muscle and liver tissue ex vivo.

Neural-network classification of cardiac disease from P cardiovascular magnetic resonance spectroscopy measures of creatine kinase energy metabolism.

Background: The heart's energy demand per gram of tissue is the body's highest and creatine kinase (CK) metabolism, its primary energy reserve, is compromised in common heart diseases. Here, neural-network analysis is used to test whether noninvasive phosphorus (P) cardiovascular magnetic resonance spectroscopy (CMRS) measurements of cardiac adenosine triphosphate (ATP) energy, phosphocreatine (PCr), the first-order CK reaction rate k, and the rate of ATP synthesis through CK (CK flux), can predict specific human heart disease and clinical severity.

Methods: The data comprised the extant 178 complete sets of PCr and ATP concentrations, k, and CK flux data from human CMRS studies performed on clinical 1.

Fast 3D chemical exchange saturation transfer imaging with variably-accelerated sensitivity encoding (vSENSE).

Purpose: To extend the variably-accelerated sensitivity encoding (vSENSE) method from 2D to 3D for fast chemical exchange saturation transfer (CEST) imaging, and prospectively implement it for clinical MRI.

Methods: The CEST scans were acquired from 7 normal volunteers and 15 brain tumor patients using a 3T clinical scanner. The 2D and 3D "artifact suppression" (AS) vSENSE algorithms were applied to generate sensitivity maps from a first scan acquired with conventional SENSE-accelerated 2D and 3D CEST data.

The relative age effect in European elite soccer: A practical guide to Poisson regression modelling.

Many disciplines of scholarship are interested in the Relative Age Effect (RAE), whereby age-banding confers advantages on older members of the cohort over younger ones. Most research does not test this relationship in a manner consistent with theory (which requires a decline in frequency across the cohort year), instead resorting to non-parametric, non-directional approaches. In this article, the authors address this disconnect, provide an overview of the benefits associated with Poisson regression modelling, and two managerially useful measures for quantifying RAE bias, namely the Indices of Discrimination and Wastage.

Cardiac work is related to creatine kinase energy supply in human heart failure: a cardiovascular magnetic resonance spectroscopy study.

Background: It has been hypothesized that the supply of chemical energy may be insufficient to fuel normal mechanical pump function in heart failure (HF). The creatine kinase (CK) reaction serves as the heart's primary energy reserve, and the supply of adenosine triphosphate (ATP flux) it provides is reduced in human HF. However, the relationship between the CK energy supply and the mechanical energy expended has never been quantified in the human heart.

Relative age effect in elite soccer: More early-born players, but no better valued, and no paragon clubs or countries.

The paper analyses two datasets of elite soccer players (top 1000 professionals and UEFA Under-19 Youth League). In both, we find a Relative Age Effect (RAE) for frequency, but not for value. That is, while there are more players born at the start of the competition year, their transfer values are no higher, nor are they given more game time.

High-resolution and accelerated multi-parametric mapping with automated characterization of vessel disease using intravascular MRI.

Background: Atherosclerosis is prevalent in cardiovascular disease, but present imaging modalities have limited capabilities for characterizing lesion stage, progression and response to intervention. This study tests whether intravascular magnetic resonance imaging (IVMRI) measures of relaxation times (T, T) and proton density (PD) in a clinical 3 Tesla scanner could characterize vessel disease, and evaluates a practical strategy for accelerated quantification.

Methods: IVMRI was performed in fresh human artery segments and swine vessels in vivo, using fast multi-parametric sequences, 1-2 mm diameter loopless antennae and 200-300 μm resolution.

Fast, Reliable 3D Amide Proton Transfer Imaging of Brain Tumors at 3T with Variably-accelerated Sensitivity Encoding (vSENSE).

The clinical use of amide proton transfer (APT) imaging is hindered by long scan times. Accuracy generally limits the use of conventional sensitivity encoding (SENSE) methods in APT, to an acceleration factor of 2. A novel variably-accelerated sensitivity encoding (vSENSE) method can provide more accurate results and therefore substantially higher overall acceleration factors than conventional SENSE.

Ultrafast compartmental relaxation time mapping with linear algebraic modeling.

Image contrast afforded by tissue longitudinal (T) and transverse (T) relaxation times is central to the success of modern MRI. Here, a recently-proposed 'spectroscopy with linear algebraic modeling' (SLAM) method is adapted to dramatically accelerate relaxation time imaging at 3 Tesla in phantoms, the abdomens of six volunteers and in six brain tumor patients..

A Combined Intravascular MRI Endoscope and Intravascular Ultrasound (IVUS) Transducer for High-Resolution Image-Guided Ablation.

An intravascular MRI (IMRI) loopless antenna is combined for the first time with an intravascular water-cooled ultrasound ablation transducer as a possible tool for providing high-resolution MRI-guided ablations of pathological tissue via intravascular access. High resolution anatomical MRI, and real-time MRI thermometry were used to monitor ablation delivery in phantoms and tissue specimens. Results show that IMRI can guide IVUS-mediated directional ablation with minimal image artifacts.

Fatigability, Exercise Intolerance, and Abnormal Skeletal Muscle Energetics in Heart Failure.

Background: Among central and peripheral factors contributing to exercise intolerance (EI) in heart failure (HF), the extent to which skeletal muscle (SM) energy metabolic abnormalities occur and contribute to EI and increased fatigability in HF patients with reduced or preserved ejection fraction (HFrEF and HFpEF, respectively) are not known. An energetic plantar flexion exercise fatigability test and magnetic resonance spectroscopy were used to probe the mechanistic in vivo relationships among SM high-energy phosphate concentrations, mitochondrial function, and EI in HFrEF and HFpEF patients and in healthy controls.

Methods And Results: Resting SM high-energy phosphate concentrations and ATP flux rates were normal in HFrEF and HFpEF patients.

Highly Accelerated, Intravascular T1, T2, and Proton Density Mapping with Linear Algebraic Modeling and Sensitivity Profile Correction at 3T.

Vessel wall MRI with intravascular (IV) detectors can produce superior local signal-to-noise ratios (SNR) and generate high-resolution T, T, and proton density (PD) maps that could be used to automatically classify atherosclerotic lesion stage. However, long acquisition times potentially limit multi-parametric mapping. Here, for the first time, spectroscopy with linear algebraic modeling (SLAM) is applied to yield accurate compartment-average T, T and PD measures at least 10 times faster compared to a standard full k-space reconstructed MIX-TSE sequence at 3T.

Highly-accelerated CEST Measurements in Three Dimensions with Linear Algebraic Modeling.

CEST MRI can provide valuable molecular level information in vivo, but its translation to routine clinics is hindered by long imaging times. Regional average CEST measurements often suffice for quantitative evaluation, diagnosis, and treatment assessment, while allowing much shorter scan times. Recently, the spectroscopy with linear algebraic modeling (SLAM) method was adapted for CEST MRI in two dimensions (2D), directly obtaining compartmental-average measurements manifold faster than conventional CEST.

Fast Chemical Exchange Saturation Transfer (CEST) Imaging with Variably-accelerated Sensitivity Encoding (vSENSE).

CEST imaging has numerous applications, but its widespread clinical use is hampered by relatively long acquisition times. Here, a novel variably-accelerated sensitivity encoding (vSENSE) method is proposed that provides faster CEST acquisitions than conventional SENSE. The vSENSE approach undersamples k-space variably for images acquired at different saturation frequencies to maximize acquisition speed.

Tails of the Travelling Gaussian model and the relative age effect: Tales of age discrimination and wasted talent.

The Relative Age Effect (RAE) documents the inherent disadvantages of being younger rather than older in an age-banded cohort, typically a school- or competition-year, to the detriment of career-progression, earnings and wellbeing into adulthood. We develop the Tails of the Travelling Gaussian (TTG) to model the mechanisms behind RAE. TTG has notable advantages over existing approaches, which have been largely descriptive, potentially confounded, and non-comparable across contexts.

Ultrafast compartmentalized relaxation time mapping with linear algebraic modeling.

Purpose: To dramatically accelerate compartmental-average longitudinal (T ) and transverse (T ) relaxation measurements using the minimal-acquisition linear algebraic modeling (SLAM) method, and to validate it in phantoms and humans.

Methods: Relaxation times were imaged at 3 Tesla in phantoms, in the abdomens of six volunteers, and in six brain tumor patients using standard inversion recovery and multi-spin-echo sequences. k-space was fully sampled to provide reference T and T measurements, and SLAM was performed using a limited set of phase encodes from central k-space.