Keywords: Vessels, Heart, NMR spectroscopy

Motivation: Heart valve disease (HVD) is a multifactorial process and its pathophysiology has not been fully understood. 

Goal(s): To investigate and determine the metabolite tissue using the ¹H-NMR based metabolomics study to discriminate the aortic valve and mitral valve. 

Approach: proton NMR spectroscopy 

Results: The results obtained from PLS-DA and VIP score plots of metabolites in tissue showed a separation between patients with aortic valves and mitral valves.

Impact: The present study revealed discrimination of metabolic profiling of tissue of aortic valve patients from mitral valve replacement implying that 1H-NMR-based metabolomics may provide an insight into understanding the potential metabolic alteration. 

Keywords: Myocardium, Cardiomyopathy

Motivation: Alterations in cardiac metabolism are implicated in numerous heart diseases, including cardiomyopathies, heart failure, and ischemic disease. Patients with hypertrophic cardiomyopathy (HCM) have known dysregulation of cardiac metabolism and energetics, and studies group aim to provide non-invasive measurements of dysregulation to allow for earlier diagnoses as well as monitoring of treatments.

Goal(s): In this project, we aim to translate HP 13C-MRI into human studies of cardiac metabolism.

Approach: This project will include studies of healthy subjects for normative values as well patients with HCM.

Results: Preliminary results show clear abnormalities in metabolic imaging but no one metabolic phenotype across all five HCM patients

Impact: In this project, we aim to translate HP 13C-MRI into human studies of cardiac metabolism. Alterations in cardiac metabolism are implicated in numerous heart diseases, including cardiomyopathies, heart failure, and ischemic disease.

Keywords: Heart Failure, Cardiomyopathy

Motivation:  ^31­P heart applications can be used to monitor cardiac energetics, treatment response in vivo and metabolic inflexibility, a key feature of the failing heart.

Goal(s): We present here a 7T and 3T protocol for  ^31­P heart application, including the validation of a dipole array coil design.

Approach: We evaluated the performance of the coil at 7T with B₁ maps and through in vivo scans of 8 healthy with a long ³¹P CSI protocol, and tested the 3T protocol on 5.

Results: Results show spectra of excellent quality. PCr/gATP ratios lie within the expected range and B1+ maps show good uniformity. 

Impact: This coil design has the potential of lifting the current limitations associated with the wider use of   ^31­P cardiac MRSI to study the heart energetics. It can also help the diagnosis and the design of new drugs in the future. 

Keywords: Heart Failure, Spectroscopy, Cardiac 31P-MRS, Iron deficiency

Motivation: Determining the impact of iron repletion on muscle energetics in non-ischaemic cardiomyopathy with reduced ejection fraction (EF).

Goal(s): Use cardiac and skeletal muscle 31P MRS to assess cardiac and skeletal muscle energetics pre and post iron repletion therapy.

Approach: Participants and ID underwent CMR to assess cardiac function, MRS to assess Phosphocreatine to Adenosine triphosphate (PCr/ATP) ratio in cardiomyocyte and relation to skeletal muscle PCr consumption, end-exercise intracellular pH and PCr recovery rate before and after Ferric carboxymaltose (FCM).

Results: FCM improves ejection fraction, 6-minute-walk-distance. It didn’t change in myocardial resting or dynamic energetics or skeletal muscle oxidative metabolism.

Impact: Iron infusion didn’t change PCr/ATP, however increased left ventricular ejection fraction,  therefor increase ATP requirement. We hypothesise that iron replacement resulted in increase in energy efficiency, or improved flux through Creatine Kinase, which was not assessed during this study. 

Keywords: Heart Failure, Oxygenation, Quantitative Susceptibility Mapping (QSM), Venography, Cardiorespiratory fitness, Cognition

Motivation: There is a lack of knowledge about the physiological underpinnings of the effects of coronary artery disease (CAD) on human brain health.

Goal(s): Here we investigated the effect of CAD on brain oxygen extraction fraction (OEF) 

Approach: Using quantitative susceptibility mapping (QSM) and its relation to cognitive performance and cardiorespiratory fitness.

Results: The results of the sex-disaggregated analysis in a preliminary dataset show that CAD male patients have significantly higher OEF in whole gray matter, frontal, occipital, and temporal lobes. Furthermore, higher OEF in males is associated with lower  cognitive performance, and higher OEF is associated with lower VO2max.

Impact: Sex differences in the effects of coronary artery disease (CAD) on brain health are unknown. Our results show that CAD increases OEF, and that higher OEF is associated with lower cognitive performance , and lower cardiorespiratory fitness in males.

Keywords: Myocardium, Cardiovascular, Quantitative Susceptibility Mapping (QSM); Myocardial Blood Volume(MBV)

Motivation: Myocardial Blood Volume (MBV) is an important factor in the progression of cardiac pathologies.

Goal(s): We proposed to combine a motion-resolved cardiac high-dynamic-range quantitative susceptibility mapping (HDR-QSM) approach with ferumoxytol (an iron-based intravascular contrast agent) to accurately measure myocardial blood volume (MBV).

Approach: HDR-QSM was prescribed in pigs with and without AMI after ferumoxytol administration to investigate the cyclic MBV changes and infarct-induced MBV redistribution in AMI.

Results: Significant MBV difference was observed between systolic and diastolic phases between healthy and infarcted hearts. 

Impact: Ferumoxytol-enhanced cardiac QSM has the potential to accurately quantify motion resolved MBV in healthy and diseased hearts.

Keywords: Heart Failure, Cardiovascular

Motivation: Right ventricular (RV) failure in pulmonary arterial hypertension (PAH) increases mortality risk, yet its metabolic characteristics is largely unknown, primarily due to limitations of imaging the RV.

Goal(s): This study examines the relative contribution of oxidative metabolism versus glycolysis in the failing RV before and after initiation of pulmonary vasodilator therapy for PAH.

Approach: Patients with newly diagnosed PAH are examined by HP [1-¹³C]pyruvate MRI at baseline and again 4-6 months after initiation of pulmonary vasodilator therapy.

Results: Patients exhibited hyperintense HP bicarbonate signals in RV free wall. After treatment, normalized myocardial [¹³C]bicarbonate production increased.

Impact: Importance of metabolic flexibility in RV heart failure is underexplored. A better understanding of how the RV myocardium remodels in RV failure from PAH and in response to therapy may allow for development of RV-targeted therapies to maintain RV function.

Keywords: Myocardium, Contrast Agent, manganese-enhanced MRI

Motivation: Manganese-enhanced MRI (MEMRI) appears to be an interesting alternative to late-gadolinium enhancement (LGE) since manganese ions can enter cardiomyocytes through calcium channels, thus allowing intracellular characterization of living cells.

Goal(s): This study aims to evaluate the sensitivity of 3D-MEMRI for the characterizing MI scars heterogeneity compared to the clinical gold standard LGE.

Approach: Manganese has a long retention time in cardiomyocytes, allowing a longer acquisition time exploited to improve the spatial resolution of 3D MR images (~1 mm³ isotropic).

Results: This study confirms the potential of 3D-MEMRI as a more specific method than the clinical gold standard LGE for characterizing MI scars heterogeneity.

Impact: The ability of high-resolution 3D manganese-enhanced MRI (3D-MEMRI) to produce a finer characterization of the heterogeneity of the scar constitutes an important step forward in the management of myocardial infarction in the context of cardiac arrhythmias

Keywords: Vascular, Vessels, MRA

Motivation: Visualizing vascular calcifications is crucial for atherosclerosis assessment, guiding interventions, and predicting risks. Existing MRI techniques fall short in this regard, necessitating additional time-consuming scans or resorting to CTA.

Goal(s): To develop a new non-contrast, single-scan solution to simultaneously acquire MR angiography (MRA) and calcification-weighted images (CWI).

Approach: We redesigned and extended the existing Relaxation-Enhanced Angiography without ContrasT (REACT) framework with different pre-pulses, termed REACT-MIX. Volunteers were used for feasibility testing, comparisons with existing techniques, and subsequent patient evaluations to assess vascular lesions.

Results: Initial findings indicated good feasibility of simultaneous MRA and CWI, encouraging further clinical evaluation.

Impact: REACT-MIX introduces a new approach enabling simultaneous non-contrast MR angiography and calcification-weighted imaging across a wide FOV in a single scan. It offers promise for clinical assessments of systemic atherosclerosis. Further studies are warranted to confirm its full potential.

Keywords: Myocardium, Machine Learning/Artificial Intelligence

Motivation: Exploring metabolic markers for detecting cardiac remodeling (CR) in athletes to differentiate adaptive from harmful changes.

Goal(s): To use ¹H-MRS for identifying metabolites predictive of CR in athletes.

Approach: Recruitment of male athletes and controls for CMR examination, analysis of myocardial metabolites using ¹H-MRS, and application of machine learning algorithms to construct predictive models for CR.

Results: Discovery of a correlation between increased myocardial creatine levels and lipid ratios in athletes with CR, with ¹H-MRS proving effective in predicting CR, highlighting MYCL-CH3/W as a particularly predictive metabolite, and positioning the KNN algorithm as a robust predictive tool.

Impact: The study advanced sports cardiology by identifying myocardial metabolites as noninvasive markers for differentiating between healthy and adverse cardiac remodeling in athletes, enhancing training strategies and early detection of cardiac risk.

Keywords: Myocardium, Non-Proton, sodium, X-nuclei, chronic kidney disease, hemodialysis, cardiomyopathy

Motivation: Cardiovascular risk is elevated in chronic kidney disease (CKD) patients on hemodialysis (HD) and may be associated with tissue sodium accumulation in the heart.

Goal(s): To compare tissue sodium concentration (TSC) in the interventricular septum of HD patients and healthy controls using sodium (²³Na) MRI.

Approach: ²³Na MRI was performed on 3 HD patients and 6 controls to quantify TSC in the interventricular septum.

Results: TSC in the septum was higher in HD patients compared to controls but was not statistically significant. These results may be limited by sample size and age and sex effects, which will be explored in a larger cohort.

Impact: For the first time, ²³Na MRI was used to directly measure TSC in the heart of CKD patients on HD. These findings may provide insight on the cardiovascular risk associated with sodium accumulation in this group.

Keywords: Myocardium, Spectroscopy, MRS, Phosphorus

Motivation: In cardiac ³¹P-CSI MRS, the signals containing ³¹P are important markers of myocardial health. Optimizing metabolite quantification is essential for understanding myocardial bioenergetics and related pathologies. 

Goal(s): The aim was to quantify an extended range of low-signal metabolites including PME, Pi, GPE, GPC, PEP, and NAD.

Approach: 36 of the existing ³¹P-CSI MRS volunteer data at 7T were analysed using an optimized and extended prior knowledge. 

Results: The results, presented as chemical shift, line-width, amplitude, and their CRBs, demonstrated successful quantification of low-signal metabolites alongside with 2,3-DPG, PCr, and ATP in the same spectra, demonstrating the feasibility of quantifying these signals at 7T. 
 

Impact: The 7T cardiac ³¹P-CSI MRS data provide valuable insight and demonstrates that low-signal metabolite quantification is possible. Looking at these signals in patient data may add to cardiac ³¹P MRS and could provide new markers of myocardial health.

Keywords: Myocardium, Spectroscopy, RF Coils, Metabolism

Motivation: Cardiac ³¹P MRS is limited by the low sensitivity of commonly used transmit-receive surface coils at larger distances from the coil. Therefore, with transmit-receive surface coils, data is often acquired in prone position, which brings the heart closer to the coil.

Goal(s): Determine the sensitivity of cardiac 3D ³¹P MRSI in prone and supine positions using an integrated ³¹P whole-body birdcage transmit coil at 7T.

Approach: A male and female subject were scanned in prone and supine position.

Results: 3D ³¹P MRSI data were obtained with good sensitivity throughout the whole heart, regardless of the position of the subject.

Impact: With an integrated ³¹P whole-body transmit coil at 7T, cardiac ³¹P MRS can be performed in the more comfortable supine position, with good sensitivity also in the posterior cardiac wall.

Keywords: Atherosclerosis, Kidney, chronic kidney disease, zero echo time, deep learning

Motivation: Screening opportunity might increase detection of calcium presence in cardiac tissues. Calcium deposit in cardiac tissues especially vessels alter flow hemodynamics. A non-invasive zero echo time magnetic resonance imaging (ZTE-MRI) may offer additional information when patients receive routine cardiac magnetic resonance imaging (CMR).

Goal(s): To propose a three-minute, high-resolution, high-SNR free-breathing ZTE-MRI in detection of coronary artery calcification.

Approach: To subjectively and objectively evaluation of ZTE-MRI respectively using conventional and deep learning reconstruction using CT as reference.

Results: DLR ZTE-MRI had superior image quality to noDLR ZTE-MRI and showed fair to good performance on calcium deposit by visual observation.  

Impact: DLR ZTE-MRI with the featurs of fee-radiation, silence, and comfort (free-breathing) during scan can provide extra information – calcium deposite, for whoever, especially a CKD patient, plans to receive a physical examination especially CMR examinaition.

Keywords: Flow, Heart, Heart failure, ejection fraction, radiomics

Motivation: HFpEF (heart failure with preserved ejection fraction) patients show similar diagnostic parameter values to healthy subjects in the quantitative evaluation of cardiac magnetic resonance imaging (CMR). Improving the performance of CMR-based HF characterization is desirable.

Goal(s): Evaluation of radiomics features from 2D flow MRI of the aorta for the classification into healthy, HFpEF, HFmrEF (mildly reduced) and HFrEF (reduced).

Approach: Training and evaluation of a decision tree classifier using 70 CMR datasets with conventional diagnostic parameters and 2D flow radiomics features to find relevant flow descriptors.

Results: The classifier achieved excellent results, considering the local flow homogeneity during diastole.

Impact: We evaluate adding 2D flow MRI radiomics to standard EF measurements for the classification of heart failure subtypes. This would enable the diagnosis of the subtypes with one imaging modality without the need for stress testing.