Platelet extracellular vesicles preserve lymphatic endothelial cell integrity and enhance lymphatic vessel function.

Lymphatic vessels are essential for preventing the accumulation of harmful components within peripheral tissues, including the artery wall. Various endogenous mechanisms maintain adequate lymphatic function throughout life, with platelets being essential for preserving lymphatic vessel integrity. However, since lymph lacks platelets, their impact on the lymphatic system has long been viewed as restricted to areas where lymphatics intersect with blood vessels.

Impact of rubidium imaging availability on management of patients with acute chest pain.

Objective: Evaluate the impact of 82-Rubidium positron emission tomography (PET) myocardial perfusion imaging (MPI) availability on patient management presenting at the emergency department (ED) with chest pain (CP).

Methods: This is a single-center retrospective study of clinical databases. Patients presenting with CP with a non-definitive suspicion of acute coronary syndrome (ACS) at the ED between April 2016 and February 2020 were divided into 2 groups based on PET availability.

SPECT imaging of pulmonary vascular disease in bleomycin-induced lung fibrosis using a vascular endothelium tracer.

Background: Pulmonary hypertension (PH) complicating idiopathic pulmonary fibrosis (IPF) is associated to worse outcome. There is a great need for a non-invasive diagnostic modality to detect and evaluate the severity of pulmonary vascular disease (PVD). Tc-PulmoBind is a novel imaging agent that binds to the adrenomedullin (AM) receptor on the pulmonary microvascular endothelium.

Comparison of 18F-sodium fluoride positron emission tomography imaging and 99mTc-pyrophosphate in cardiac amyloidosis.

Background: Pyrophosphate (PYP) scintigraphy provides high diagnostic accuracy for the detection of transthyretin (ATTR) cardiac amyloidosis (CA). There has recently been emerging interest in using 18F-sodium fluoride (NaF) for this application, yet its sensitivity has never been directly compared to that of PYP, the current molecular gold standard METHODS: Twelve subjects with ATTR-CA and 5 controls referred for PYP-SPECT were prospectively enrolled. 18F-NaF PET/CT scans were performed at 1 and 3 hours.

Site qualification and clinical interpretation standards for Tc-SPECT perfusion imaging in a multi-center study of MITNEC (Medical Imaging Trials Network of Canada).

Background: Qualification and interpretation standards are essential for establishing Tc-SPECT MPI accuracy vs. alternative modalities.

Methods: Rest-stress Tc-SPECT phantom scans were acquired on 35 cameras.

[F]FDG-PET CT for the evaluation of native valve endocarditis.

Background: We examined the use of [F]FDG-PET/CT for the diagnosis of native valve endocarditis (NVE).

Methods: PET/CT images in patients with suspected NVE were retrospectively reviewed independently by two experienced physicians blinded to all clinical information. The gold standard consisted of surgical findings, when available, or the modified Duke criteria.

SPECT and PET imaging of adrenomedullin receptors: a promising strategy for studying pulmonary vascular diseases.

Circulating adrenomedullin (AM) levels are elevated in several cardiovascular diseases, including pulmonary vascular diseases causing pulmonary hypertension. To date the perfusion agent Tc-albumin macroaggregates (MAA) is the only approved radiopharmaceutical used for imaging of pulmonary circulation. Unlike Tc-MAA, imaging the AM receptors involves a molecular process dependent on the density of the receptors and the affinity of specific radioligands.

Utility of FDG-PET/CT for the Detection and Characterization of Sternal Wound Infection Following Sternotomy.

Purpose: FDG-PET/CT has the potential to play an important role in the diagnosis of sternal wound infections (SWI). The purpose of this study was to analyze the diagnostic accuracy of FDG-PET/CT for SWI in patients following sternotomy.

Methods: We performed a single-center, retrospective analysis of patients who had undergone median sternotomy and FDG-PET/CT imaging.

Examining the sensitivity of 18F-NaF PET for the imaging of cardiac amyloidosis.

Background: Conventional nuclear imaging with bone-seeking radiopharmaceuticals has been shown to be a sensitive test for the detection of transthyretin cardiac amyloidosis (ATTR); however, to date, few data exist on the utility of F-sodium fluoride (NaF) positron emission tomography (PET) in subjects with cardiac amyloidosis (CA).

Methods: Myocardial perfusion imaging and cardiac F-NaF PET/CT of 7 subjects with ATTR, four with light-chain CA (AL), and four controls were retrospectively reviewed. Qualitative interpretation and quantitative analyses with average left ventricular standardized uptake values (SUV) and target-to-background ratios (TBR) were performed.

Al[F]F-complexation of DFH17, a NOTA-conjugated adrenomedullin analog, for PET imaging of pulmonary circulation.

Introduction: Adrenomedullin receptors are highly expressed in human alveolar capillaries and provide a molecular target for imaging the integrity of pulmonary microcirculation. In this work, we aimed to develop a NOTA-derivatized adrenomedullin analog (DFH17), radiolabeled with [F]AlF, for PET imaging of pulmonary microcirculation.

Methods: Highly concentrated [F](AlF) (15 μL) was produced from purified fluorine-18 in NaCl 0.

Comparison of two dipyridamole infusion protocols for myocardial perfusion imaging in subjects with low likelihood of significant obstructive coronary artery disease.

Background: Myocardial perfusion imaging (MPI) with positron emission tomography allows accurate measurements of myocardial blood flow (MBF). Stress MBF thresholds have been proposed to provide diagnostic and prognostic information in different pathology. Most studies relying on dipyridamole use a 5-minute infusion protocol, while current guidelines recommend a 4-minute infusion.

Cardiopulmonary, biomarkers, and vascular responses to acute hypoxia following cardiac transplantation.

Previous studies have suggested good adaptation of cardiac transplant (CTx) recipients to exposure to a high altitude. No studies have investigated the cardiopulmonary and biomarker responses to acute hypoxic challenges following CTx. Thirty-six CTx recipients and 17 age-matched healthy controls (HC) were recruited.

Assessment of left ventricular ejection fraction with cardiofocal collimators: Comparison between IQ-SPECT, planar equilibrium radionuclide angiography, and cardiac magnetic resonance.

Background: IQ-SPECT has been shown to significantly reduce acquisition time and administered dose while preserving image quality in myocardial perfusion imaging. Whether IQ-SPECT provides accurate left ventricular ejection fractions (LVEF) with gated blood pool SPECT (GBPS) remains unknown.

Methods: Sixty patients underwent IQ-SPECT GBPS and planar imaging.

Molecular imaging of the human pulmonary vascular endothelium in pulmonary hypertension: a phase II safety and proof of principle trial.

Purpose: The adrenomedullin receptor is densely expressed in the pulmonary vascular endothelium. PulmoBind, an adrenomedullin receptor ligand, was developed for molecular diagnosis of pulmonary vascular disease. We evaluated the safety of PulmoBind SPECT imaging and its capacity to detect pulmonary vascular disease associated with pulmonary hypertension (PH) in a human phase II study.

Evaluation of pulmonary perfusion by SPECT imaging using an endothelial cell tracer in supine humans and dogs.

Background: Pulmonary perfusion is not spatially homogeneously distributed, and its variations could be of diagnostic value in lung vascular disease. PulmoBind is a ligand of the adrenomedullin receptor densely expressed in endothelial cells of lung capillaries. The aim of this study was to evaluate spatial distribution of human lung perfusion by using this novel molecular tracer of the pulmonary vascular endothelium.

Phase analysis of gated blood pool SPECT for multiple stress testing assessments of ventricular mechanical dyssynchrony in a tachycardia-induced dilated cardiomyopathy canine model.

Background: Stress-induced dyssynchrony has been shown to be independently correlated with clinical outcomes in patients with dilated cardiomyopathy (DCM) and narrow QRS complexes. However, the extent to which stress levels affect inter- and intraventricular dyssynchrony parameters remains unknown.

Methods: Ten large dogs were submitted to tachycardia-induced DCM by pacing the right ventricular apex for 3-4 weeks to reach a target ejection fraction (EF) of 35% or less.

Molecular Imaging of the Human Pulmonary Vascular Endothelium Using an Adrenomedullin Receptor Ligand.

This phase I study (NCT01539889) evaluated the safety, efficacy, and dosing of PulmoBind for molecular imaging of pulmonary circulation. PulmoBind is a ligand of the adrenomedullin receptor abundantly distributed in lung capillaries. Labeled with Tc, it allows single-photon emission computed tomographic (SPECT) imaging of lung perfusion.

Molecular imaging of the human pulmonary vascular endothelium using an adrenomedullin receptor ligand.

This phase I study (NCT01539889) evaluated the safety, efficacy, and dosing of PulmoBind for molecular imaging of pulmonary circulation. PulmoBind is a ligand of the adrenomedullin receptor abundantly distributed in lung capillaries. Labeled with 99mTc, it allows single-photon emission computed tomographic (SPECT) imaging of lung perfusion.

The effects of dobutamine stress on cardiac mechanical synchrony determined by phase analysis of gated SPECT myocardial perfusion imaging in a canine model.

Background: Precise identification of left ventricular (LV) systolic mechanical dyssynchrony may be useful in optimizing the response to cardiac resynchronization therapy in heart failure (HF) patients. However, LV dyssynchrony is mostly measured at rest; patients often suffer from the HF symptoms during exercise.

Objectives: Our objective was to examine the impacts of stress on LV synchronism with phase analysis of gated SPECT myocardial perfusion imaging (GMPS) within a normal animal cohort.

Evaluation of the right ventricle: comparison of gated blood-pool single photon electron computed tomography and echocardiography with cardiac magnetic resonance.

Background: The evaluation of the right ventricle (RV) is a challenge; as a result six transthoracic echocardiography (TTE) parameters have been suggested. While gated blood-pool single photon electron computed tomography (GBPS) is a promising technique, there is currently no completely automated and validated processing software available clinically. Consequently, cardiac magnetic resonance (CMR) imaging remains the gold standard for RV assessment.

Effects of dobutamine stress on cardiac contraction synchronism in a canine model.

In cardiac resynchronization therapy, many devices need to be optimized to take into account the magnitude and characteristics of patients' ventricular mechanical dyssynchrony. The optimization process is mostly performed at rest; however, mechanical resynchronization might be more important under stress, while patients need to improve their cardiac efficiency. The objective of this study was to observe if levels of cardiac stress could modify the ventricular contraction synchronism.

Canine left ventricle electromechanical behavior under different pacing modes.

Background: Cardiac resynchronization therapy may improve survival and quality of life in patients suffering from heart failure with left ventricular (LV) contraction dyssynchrony. While several studies have investigated electrical or mechanical determinants of synchronous contraction, few have focused on activation contraction coupling at a macroscopic level.

Objective: The objective of the study was to characterize LV electromechanical behavior and response to pacing in a heart failure model.

Characterization and reproducibility of forearm arterial flow during reactive hyperemia.

Peripheral arterial flow has been assessed for a variety of indications including characterization of endothelial function during reactive hyperemia. However, quantification of this blood flow as a surrogate remains an imperfect reflection of endothelial function. We sought to better characterize hyperemic reaction to (1) elucidate the influence of the endothelial function and (2) assess the reproducibility of our modeling over time.

Gated blood-pool SPECT versus cardiac magnetic resonance imaging for the assessment of left ventricular volumes and ejection fraction.

Background: We evaluated the accuracy of planar radionuclide angiography and different count-based and space-based electrocardiogram (ECG)-gated blood-pool single-photon emission computed tomography (GBPS) algorithms for assessment of left ventricular end-diastolic volume (LVEDV), end-systolic volume (LVESV), and ejection fraction (LVEF) compared with the gold standard of cardiac magnetic resonance imaging (cMRI). The goal is to assess the accuracy of a recently developed GBPS algorithm.

Methods And Results: Subjects had planar, GBPS, and cMRI sequentially.

Comparison of left ventricular contraction homogeneity index using SPECT gated blood pool imaging and planar phase analysis.

Background: There is growing interest in developing a practical technique to accurately assess ventricular synchrony. We describe a novel 3-dimensional (3D) gated blood pool single photon emission computed tomography (SPECT) approach, from which a contraction homogeneity index (CHI) is derived and compared with planar phase analyses.

Methods And Results: Subjects underwent planar and SPECT blood pool acquisition.