Cardiac magnetic resonance imaging characterization of acute rejection in a porcine heterotopic heart transplantation model.

Preclinical disease models are important for the advancement of therapeutics towards human clinical trials. One of the difficult tasks of developing a well-characterized model is having a reliable modality with which to trend the progression of disease. Acute rejection is one of the most devastating complications that can occur following organ transplantation.

Video analysis of beating hearts during preservation on the TransMedics® organ care system.

Background: Reliable biomarkers for assessing the viability of the donor hearts undergoing perfusion remain elusive. A unique feature of normothermic perfusion on the TransMedics® Organ Care System (OCS™) is that the donor heart is maintained in a beating state throughout the preservation period. We applied a video algorithm for an assessment of cardiac kinematics, video kinematic evaluation (Vi.

Reference values of myocardial native T1 and extracellular volume in patients without structural heart disease and had negative 3T cardiac magnetic resonance adenosine stress test.

Background: To establish the reference values of native T1 and extracellular volume (ECV) in patients without structural heart disease and had a negative adenosine stress 3T cardiac magnetic resonance.

Methods: Short-axis T1 mapping images were acquired using a modified Look-Locker inversion recovery technique before and after administration of 0.15 mmol/kg gadobutrol to calculate both native T1 and ECV.

Native T1 Mapping for the Diagnosis of Myocardial Fibrosis in Patients With Chronic Myocardial Infarction.

Background: Myocardial fibrosis is a fundamental process in cardiac injury. Cardiac magnetic resonance native T1 mapping has been proposed for diagnosing myocardial fibrosis without the need for gadolinium contrast. However, recent studies suggest that T1 measurements can be erroneous in the presence of intramyocardial fat.

Targeted Delivery for Cardiac Regeneration: Comparison of Intra-coronary Infusion and Intra-myocardial Injection in Porcine Hearts.

Background: The optimal delivery route to enhance effectiveness of regenerative therapeutics to the human heart is poorly understood. Direct intra-myocardial (IM) injection is the gold standard, however, it is relatively invasive. We thus compared targeted IM against less invasive, catheter-based intra-coronary (IC) delivery to porcine myocardium for the acute retention of nanoparticles using cardiac magnetic resonance (CMR) imaging and viral vector transduction using qPCR.

Patients With Acute Myocarditis Following mRNA COVID-19 Vaccination.

Importance: Vaccine-associated myocarditis is an unusual entity that has been described for the smallpox vaccine, but only anecdotal case reports have been described for other vaccines. Whether COVID-19 vaccination may be linked to the occurrence of myocarditis is unknown.

Objective: To describe a group of 7 patients with acute myocarditis over 3 months, 4 of whom had recent messenger RNA (mRNA) COVID-19 vaccination.

ECG-gated MR angiography provides better reproducibility for standard aortic measurements.

Objective: Cardiac motion and aortic pulsatility can affect the image quality of 3D contrast-enhanced MR angiography (CE-MRA). The addition of ECG gating improves image quality; however, no studies have directly linked image quality improvements to clinically used measures. In this study, we directly compared diameter measurements in the same patient from ECG-gated to non-gated CE-MRA to evaluate the impact of ECG gating upon measurement reproducibility.

Comparison of magnetization transfer-preparation and T2-preparation for dark-blood delayed-enhancement imaging.

Recently developed dark-blood techniques such as Flow-Independent Dark-blood DeLayed Enhancement (FIDDLE) allow simultaneous visualization of tissue contrast-enhancement and blood-pool suppression. Critical to FIDDLE is the magnetization preparation, which accentuates differences between myocardium and blood-pool. Here, we compared magnetization transfer (MT)-preparation and T2-preparation for use with FIDDLE.

Dark-Blood Delayed Enhancement Cardiac Magnetic Resonance of Myocardial Infarction.

Objectives: This study introduced and validated a novel flow-independent delayed enhancement technique that shows hyperenhanced myocardium while simultaneously suppressing blood-pool signal.

Background: The diagnosis and assessment of myocardial infarction (MI) is crucial in determining clinical management and prognosis. Although delayed enhancement cardiac magnetic resonance (DE-CMR) is an in vivo reference standard for imaging MI, an important limitation is poor delineation between hyperenhanced myocardium and bright LV cavity blood-pool, which may cause many infarcts to become invisible.

Treating a 20 mm Hg gradient alleviates myocardial hypertrophy in experimental aortic coarctation.

Background: Children with coarctation of the aorta (CoA) can have a hyperdynamic and remodeled left ventricle (LV) from increased afterload. Literature from an experimental model suggests the putative 20 mm Hg blood pressure gradient (BPG) treatment guideline frequently implemented in CoA studies may permit irreversible vascular changes. LV remodeling from pressure overload has been studied, but data are limited following correction and using a clinically representative BPG.

Suppression of ghost artifacts arising from long T species in segmented inversion-recovery imaging.

Purpose: We demonstrate an improved segmented inversion-recovery sequence that suppresses ghost artifacts arising from tissues with long T ( > 1.5 s).

Theory And Methods: Long T species such as pericardial fluid can create bright ghost artifacts in segmented, inversion-recovery MRI because of oscillations in longitudinal magnetization between segments.

The Impact of Cardiac Motion on Aortic Valve Flow Used in Computational Simulations of the Thoracic Aorta.

Advancements in image-based computational modeling are producing increasingly more realistic representations of vasculature and hemodynamics, but so far have not compensated for cardiac motion when imposing inflow boundary conditions. The effect of cardiac motion on aortic flow is important when assessing sequelae in this region including coarctation of the aorta (CoA) or regurgitant fraction. The objective of this investigation was to develop a method to assess and correct for the influence of cardiac motion on blood flow measurements through the aortic valve (AoV) and to determine its impact on patient-specific local hemodynamics quantified by computational fluid dynamics (CFD).

Relationship of T2-Weighted MRI Myocardial Hyperintensity and the Ischemic Area-At-Risk.

Rationale: After acute myocardial infarction (MI), delineating the area-at-risk (AAR) is crucial for measuring how much, if any, ischemic myocardium has been salvaged. T2-weighted MRI is promoted as an excellent method to delineate the AAR. However, the evidence supporting the validity of this method to measure the AAR is indirect, and it has never been validated with direct anatomic measurements.

CMR imaging with rapid visual T1 assessment predicts mortality in patients suspected of cardiac amyloidosis.

Objectives: This study tested the diagnostic and prognostic utility of a rapid, visual T1 assessment method for identification of cardiac amyloidosis (CA) in a "real-life" referral population undergoing cardiac magnetic resonance for suspected CA.

Background: In patients with confirmed CA, delayed-enhancement cardiac magnetic resonance (DE-CMR) frequently shows a diffuse, global hyperenhancement (HE) pattern. However, imaging is often technically challenging, and the prognostic significance of diffuse HE is unclear.

Altered hemodynamics, endothelial function, and protein expression occur with aortic coarctation and persist after repair.

Coarctation of the aorta (CoA) is associated with substantial morbidity despite treatment. Mechanically induced structural and functional vascular changes are implicated; however, their relationship with smooth muscle (SM) phenotypic expression is not fully understood. Using a clinically representative rabbit model of CoA and correction, we quantified mechanical alterations from a 20-mmHg blood pressure (BP) gradient in the thoracic aorta and related the expression of key SM contractile and focal adhesion proteins with remodeling, relaxation, and stiffness.

Including aortic valve morphology in computational fluid dynamics simulations: initial findings and application to aortic coarctation.

Computational fluid dynamics (CFD) simulations quantifying thoracic aortic flow patterns have not included disturbances from the aortic valve (AoV). 80% of patients with aortic coarctation (CoA) have a bicuspid aortic valve (BAV) which may cause adverse flow patterns contributing to morbidity. Our objectives were to develop a method to account for the AoV in CFD simulations, and quantify its impact on local hemodynamics.

A coupled experimental and computational approach to quantify deleterious hemodynamics, vascular alterations, and mechanisms of long-term morbidity in response to aortic coarctation.

Introduction: Coarctation of the aorta (CoA) is associated with morbidity despite treatment. Although mechanisms remain elusive, abnormal hemodynamics and vascular biomechanics are implicated. We present a novel approach that facilitates quantification of coarctation-induced mechanical alterations and their impact on vascular structure and function, without genetic or confounding factors.