Robert J. Gropler

Myocardial perfusion imaging: Lessons learned and work to be done—update

As the second term of our commitment to Journal begins, we, the editors, would like to reflect on a few topics that have relevance today. These include prognostication and paradigm shifts; Serial testing: How to handle data? Is the change in perfusion predictive of outcome and which one? Ischemia-guided therapy: fractional flow reserve vs perfusion vs myocardial blood flow; positron emission tomography (PET) imaging using Rubidium-82 vs N-13 ammonia vs F-18 Flurpiridaz; How to differentiate microvascular disease from 3-vessel disease by PET? The imaging scene outside the United States, what are the differences and similarities? Radiation exposure; Special issues with the new cameras? Is attenuation correction needed? Are there normal databases and are these specific to each camera system? And finally, hybrid imaging with single-photon emission tomography or PET combined with computed tomography angiography or coronary calcium score. We hope these topics are of interest to our readers.

Single Photon Emission Computed Tomography (SPECT) Myocardial Perfusion Imaging Guidelines: Instrumentation, Acquisition, Processing, and Interpretation

Single Photon Emission Computed Tomography (SPECT) Myocardial Perfusion Imaging Guidelines: Instrumentation, Acquisition, Processing, and Interpretation Sharmila Dorbala, MD, MPH, Karthik Ananthasubramaniam, MD, Ian S. Armstrong, PhD, MIPEM, Panithaya Chareonthaitawee, MD, E. Gordon DePuey, MD, Andrew J. Einstein, MD, PhD, Robert J. Gropler, MD, Thomas A. Holly, MD, John J. Mahmarian, MD, Mi-Ae Park, PhD, Donna M. Polk, MD, MPH, Raymond Russell III, MD, PhD, Piotr J. Slomka, PhD, Randall C. Thompson, MD, and R. Glenn Wells, PhD

Quantification of Myocardial Oxygen Consumption Using 11C-Acetate

Normal cardiac performance reflects the codependency of myocardial mechanical function, oxygen consumption (MVO2), and blood flow. It is well established that physiological processes directly associated with contraction (e.g., wall stress, shortening, heart rate, and contractility) are major determinants of MVO2. The rapid cessation of MVO2 and systolic function with interruption of blood flow (supply) is equally well known. Because of this close coupling of mechanical function, MVO2, and perfusion, and the primacy of oxidation of substrates for myocardial energy production, most disease processes involving the heart manifest as imbalances in myocardial oxygen supply and demand. For example, it is the imbalance of inadequate myocardial oxygen supply in the face of a given demand that typifies the myocardial manifestations of coronary artery disease. In contrast, in patients with dilated cardiomyopathy, mechanical function is diminished despite adequate oxygen supply.

Type 2 Diabetes, Obesity, and Gender Affect the Fate of Glucose in the Human Heart

Type 2 diabetes, obesity, and sex difference affect myocardial glucose uptake and utilization. However, their effect on the intramyocellular fate of glucose in humans has been unknown. How the heart uses glucose is important, because it affects energy production and oxygen efficiency, which in turn affect heart function and adaptability. We hypothesized that type 2 diabetes, sex difference, and obesity affect myocardial glucose oxidation, glycolysis, and glycogen production. In a first-in-human study, we measured intramyocardiocellular glucose metabolism from time-activity curves generated from previously obtained positron emission tomography scans of 110 subjects in 3 groups: nonobese, obese, and diabetes. Group and sex difference interacted in the prediction of all glucose uptake, utilization, and metabolism rates. Group independently predicted fractional glucose uptake and its components: glycolysis, glycogen deposition, and glucose oxidation rates. Sex difference predicted glycolysis rates. However, there were fewer differences in glucose metabolism between diabetic patients and others when plasma glucose levels were included in the modeling. The potentially detrimental effects of obesity and diabetes on myocardial glucose metabolism are more pronounced in men than women. This sex difference dimorphism needs to be taken into account in the design, trials, and application of metabolic modulator therapy. Slightly higher plasma glucose levels improve depressed glucose oxidation and glycogen deposition rates in diabetic patients.

2101 Role of hemodynamic forces on plaque development: non-invasive assessment with MRI methods

Purpose Fluid shear stress was thought to lead to atherosclerotic plaque progression, but such measurement procedures are often invasive. The goal of the present study is to address the biomechanical pathways of atherosclerosis progression and regression with our non-invasive MRI methods and a 3D fluid-structure interaction (FSI) model. The study was performed in a large animal atherosclerotic model.