Quantitation of mitral regurgitation using positron emission tomography.

Background: Cardiac positron emission tomography (PET) offers non-invasive assessment of perfusion and left ventricular (LV) function from a single dynamic scan. However, no prior assessment of mitral regurgitation severity by PET has been presented. Application of indicator dilution techniques and gated image analyses to PET data enables calculation of forward stroke volume and total LV stroke volume.

PET myocardial perfusion imaging: Trends, challenges, and opportunities.

Various non-invasive images are used in clinical practice for the diagnosis and prognostication of chronic coronary syndromes. Notably, quantitative myocardial perfusion imaging (MPI) through positron emission tomography (PET) has seen significant technical advancements and a substantial increase in its use over the past two decades. This progress has generated an unprecedented wealth of clinical information, which, when properly applied, can diagnose and fine-tune the management of patients with different types of ischemic syndromes.

Validation of resting full-cycle ratio and diastolic pressure ratio with [O]HO positron emission tomography myocardial perfusion.

Fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) are invasive techniques used to evaluate the hemodynamic significance of coronary artery stenosis. These methods have been validated through perfusion imaging and clinical trials. New invasive pressure ratios that do not require hyperemia have recently emerged, and it is essential to confirm their diagnostic efficacy.

Quantitative and qualitative comparison of Rubidium-82 and Oxygen-15 water cardiac PET.

Background: Differences in tracer characteristics may influence the interpretation of positron emission tomography myocardial perfusion imaging (MPI). We compare the reading of MPIs with a low-extraction retention tracer (Rb) and a high-extraction non-retention tracer (O-water) in a selected cohort of patients with known coronary artery disease (CAD).

Methods: Thirty-nine patients with known CAD referred to Rb MPI due to angina underwent rest and stress imaging with both tracers and experienced MPI readers provided blinded consensus reads of all studies.

Outcome prediction by myocardial external efficiency from C-acetate positron emission tomography in cardiac amyloidosis.

Aims: This study aimed to study the prognostic value of myocardial oxygen consumption (MVO ) and myocardial external efficiency (MEE) from C-acetate positron emission tomography (PET) in cardiac amyloidosis (CA) patients.

Methods And Results: Forty-eight CA patients, both transthyretin (ATTR) and immunoglobulin light chain (AL) amyloidosis, and 20 controls were included. All subjects were examined with C-acetate PET and echocardiography.

Association of Right Ventricular Myocardial Blood Flow With Pulmonary Pressures and Outcome in Cardiac Amyloidosis.

Background: Cardiac amyloidosis (CA) is a restrictive and infiltrative cardiomyopathy, characterized by increased biventricular filling pressures and low output. Symptoms are predominantly of right heart origin. The role of right ventricular (RV) myocardial blood flow (MBF) in CA has not been studied.

Myocardial External Efficiency in Asymptomatic Severe Primary Mitral Regurgitation Using C-Acetate PET.

Subjects with asymptomatic moderate-to-severe or severe primary mitral regurgitation are closely observed for signs of progression or symptoms requiring surgical intervention. The role of myocardial metabolic function in progression of mitral regurgitation is poorly understood. We used C-acetate PET to noninvasively measure myocardial mechanical external efficiency (MEE), which is the energetic ratio of external cardiac work and left ventricular (LV) oxygen consumption.

Left-ventricular volumes and ejection fraction from cardiac ECG-gated O-water positron emission tomography compared to cardiac magnetic resonance imaging using simultaneous hybrid PET/MR.

Background: O-water PET is the gold standard for noninvasive quantification of myocardial blood flow. In addition to evaluation of ischemia, the assessment of cardiac function and remodeling is important in all cardiac diseases. However, since O-water is freely diffusible and standard uptake images show little contrast between the myocardium and blood pool, the assessment of left-ventricular (LV) volumes and ejection fraction (EF) is challenging.

Myocardial efficiency in patients with different aetiologies and stages of heart failure.

Aims: Myocardial external efficiency (MEE) is the ratio of cardiac work in relation with energy expenditure. We studied MEE in patients with different aetiologies and stages of heart failure (HF) to discover the role and causes of deranged MEE. In addition, we explored the impact of patient characteristics such as sex, body mass index (BMI), and age on myocardial energetics.

Functional cross-talk between phosphorylation and disease-causing mutations in the cardiac sodium channel Na1.5.

The voltage-gated sodium channel Na1.5 initiates the cardiac action potential. Alterations of its activation and inactivation properties due to mutations can cause severe, life-threatening arrhythmias.

Diagnosis of left ventricular hypertrophy using non-ECG-gated O-water PET.

Aim: To develop a method for diagnosing left ventricular (LV) hypertrophy from cardiac perfusion O-water positron emission tomography (PET).

Methods: We retrospectively pooled data from 139 subjects in four research cohorts. LV remodeling patterns ranged from normal to severe eccentric and concentric hypertrophy.

Right ventricular hemodynamics and performance in relation to perfusion during first year after heart transplantation.

Aims: We aim to evaluate changes in invasive haemodynamics, right ventricular (RV) function, and perfusion during the first year after heart transplantation (HTx) and to determine the relation between RV function and myocardial perfusion.

Methods And Results: Thirty patients were prospectively enrolled at the time of HTx. Right heart catheterization (RHC), comprehensive 2D and 3D echocardiography and cardiac biomarkers were performed at baseline (≤2 weeks after HTx) and at follow-up 1, 3, 6, and 12 months after HTx.

Ion channel engineering using protein trans-splicing.

Conventional site-directed mutagenesis and genetic code expansion approaches have been instrumental in providing detailed functional and pharmacological insight into membrane proteins such as ion channels. Recently, this has increasingly been complemented by semi-synthetic strategies, in which part of the protein is generated synthetically. This means a vast range of chemical modifications, including non-canonical amino acids (ncAA), backbone modifications, chemical handles, fluorescent or spectroscopic labels and any combination of these can be incorporated.

Influence of patient motion on quantitative accuracy in cardiac O-water positron emission tomography.

Background: Patient motion is a common problem during cardiac PET. The purpose of the present study was to investigate to what extent motions influence the quantitative accuracy of cardiac O-water PET/CT and to develop a method for automated motion detection.

Method: Frequency and magnitude of motion was assessed visually using data from 50 clinical O-water PET/CT scans.

Effect of PET-CT misalignment on the quantitative accuracy of cardiac O-water PET.

Background: Quantification of myocardial blood flow (MBF) with PET requires accurate attenuation correction, which is performed using a separate CT. Misalignment between PET and CT scans has been reported to be a common problem. The purpose of the present study was to assess the effect of PET CT misalignment on the quantitative accuracy of cardiac O-water PET.

PET Imaging of Tumor Perfusion: A Potential Cancer Biomarker?

Perfusion, as measured by imaging, is considered a standard of care biomarker for the evaluation of many tumors. Measurements of tumor perfusion may be used in a number of ways, including improving the visual detection of lesions, differentiating malignant from benign findings, assessing aggressiveness of tumors, identifying ischemia and by extension hypoxia within tumors, and assessing treatment response. While most clinical perfusion imaging is currently performed with CT or MR, a number of methods for PET imaging of tumor perfusion have been described.

First-Pass Techniques Applied to Standard Dynamic Cardiac PET: A reappraisal of Old Invasive Techniques to Assess Cardiac Function.

Cardiac PET is increasingly performed with dynamic imaging to measure tracer pharmacokinetics in the myocardium. If the early time frames of the PET protocol are sufficiently short and the total amount of injected radioactivity is correctly measured the indicator dilution principle can be applied to PET with most tracers in clinical use, similar to invasive and other noninvasive techniques. The first-pass of the tracer through the heart and lungs can be used to quantify some highly important aspects of cardiovascular function, such as forward cardiac output, transit times, and partial volumes in the central compartments.

Diagnostic Accuracy of [C]PIB Positron Emission Tomography for Detection of Cardiac Amyloidosis.

Objectives: This dual-site study evaluated the diagnostic accuracy of the method.

Background: Pittsburgh compound ([C]PIB) positron emission tomography (PIB-PET) has shown promise as a specific and noninvasive method for the diagnosis of cardiac amyloidosis (CA).

Methods: The study had 2 parts.

Bisoprolol therapy does not reduce right ventricular sympathetic activity in pulmonary arterial hypertension patients.

Right ventricular (RV) function and autonomic dysfunction are important determinants of morbidity and mortality in patients with pulmonary arterial hypertension (PAH). Although successful in animal studies, effects of beta-blocker therapy on RV function in clinical trials were disappointing. To understand this discrepancy, we studied whether beta-blocker therapy changes RV sympathetic activity.

Value of CMR and PET in Predicting Ventricular Arrhythmias in Ischemic Cardiomyopathy Patients Eligible for ICD.

Objectives: This study presents a head-to-head comparison of the value of cardiac magnetic resonance (CMR)-derived left-ventricular (LV) function and scar burden and positron emission tomography (PET)-derived perfusion and innervation in predicting ventricular arrhythmias (VAs).

Background: Improved risk stratification of VA is important to identify patients who should benefit of prophylactic implantable cardioverter-defibrillator (ICD) implantation. Perfusion abnormalities, sympathetic denervation, and scar burden have all been linked to VA, although comparative studies are lacking.

Increased Myocardial Oxygen Consumption Precedes Contractile Dysfunction in Hypertrophic Cardiomyopathy Caused by Pathogenic Gene Variants.

Background Hypertrophic cardiomyopathy is caused by pathogenic sarcomere gene variants. Individuals with a thin-filament variant present with milder hypertrophy than carriers of thick-filament variants, although prognosis is poorer. Herein, we defined if decreased energetic status of the heart is an early pathomechanism in (troponin T gene) variant carriers.

Positron emission tomography (O-water, C-acetate, C-HED) risk markers and nonsustained ventricular tachycardia in hypertrophic cardiomyopathy.

Background: The objectives of the study were to describe positron emission tomography (PET) parameters, using the tracers O-water at rest/stress, C-acetate, and C-HED, with regard to nonsustained ventricular tachycardia (NSVT) in hypertrophic cardiomyopathy (HCM). PET offers quantitative assessment of pathophysiology throughout the left ventricular segments, including the endocardium/epicardium. The potential use PET in risk stratification remains to be elucidated.

Myocardial Efficiency: A Fundamental Physiological Concept on the Verge of Clinical Impact.

Myocardial external efficiency is the relation of mechanical energy generated by the left (or right) ventricle to the consumed chemical energy from aerobic metabolism. Efficiency can be calculated invasively, and, more importantly, noninvasively by using positron emission tomography, providing a single parameter by which to judge the adequacy of myocardial metabolism to generated mechanical output. This parameter has been found to be impaired in heart failure of myocardial or valvular etiology, and it changes in a characteristic manner with medical or interventional cardiac therapy.