Distribution of Rubidium-82, Nitrogen-13 Ammonia, and Fluorine-18 Fluorodeoxyglucose in Normal Volunteers

Overview

Establish the normal distributions of Rb-82, N-13 ammonia, and F-18 FDG (radioactive tracers) in the heart using PET imaging. These tracers would be eventually used in evaluating the hearts of patients with heart disease. Normal healthy volunteers will be carefully screened for this study. Subjects will be given IV administration of Rb-82 and N-13 to acquire rest/stress imaging. Normal subjects not excluded by any unexpected abnormality during the Rb-82 or N-13 rest/stress studies will undergo a glucose loading F-18 FDG imaging protocol, viability protocol using the hyperinsulinemic euglycemic clamp with simultaneous IV infusions of dextrose and insulin according to standard procedures in our laboratory. These same subjects will have a F-18 FDG protocol after following a high fat, protein permitted, no carbohydrate diet for approximately 30 hours prior to F-18 FDG injection. The F-18 FDG radiotracer will be given through an IV.

Cardiac rubidium-82(Rb-82)and N-13 ammonia heart perfusion (blood flow) studies and florine-18 fluorodeoxyglucose (F-18FDG) heart PET glucose metabolism studies are important tools for evaluating patients with coronary heart disease. This includes patients with known or suspected heart disease and patients with congestive heart failure following myocardial infarction (heart attack) with indeterminant assessments of cardiac health from other types of imaging, such as SPECT perfusion imaging and echocardiography. These studies help physicians plan potentially life saving procedures to re-establish coronary blood flow to living but severely compromised heart muscle. Rb-82 and N-13 ammonia studies can tell if there is reduced blood flow to the heart muscle either at rest or during stress. FDG studies can tell whether there is any chance of a beneficial effect from coronary revascularization procedures, for example coronary angioplasties and stents or coronary artery bypass. Revascularization procedures in patients like these may be technically difficult, risky and costly. Unfortunately the normal cardiac distributions of Rb-82, N-13 and ammonia, and F-18FDG for computer analysis of human studies are not well known and what is known is not widely available for clinical use. The latest imaging guidelines from the American Society of Nuclear Cardiology recommend that Rb-82, N-13 ammonia, and FDG cardiac studies be compared to normal distributions or patterns of these radiotracers in the heart developed from a series of normal individuals. The purpose for these studies is to generate databases of normal Rb-82, N-13 ammonia, and F-18FDG cardiac distributions so that they can be used in the analysis of clinical patient studies at the University of Michigan Hospital.