title: Noninvasive evaluation of sympathetic nervous system in human heart by positron emission tomography.
abstract: The noninvasive functional characterization of the cardiac sympathetic nervous system by imaging techniques may provide important pathophysiological information in various cardiac disease states. Hydroxyephedrine labeled with carbon 11 has been developed as a new catecholamine analogue to be used in the in vivo evaluation of presynaptic adrenergic nerve terminals by positron emission tomography (PET). To determine the feasibility of this imaging approach in the human heart, six normal volunteers and five patients with recent cardiac transplants underwent dynamic PET imaging after intravenous injection of 20 mCi [11C]hydroxyephedrine. Blood and myocardial tracer kinetics were assessed using a regions-of-interest approach. In normal volunteers, blood 11C activity cleared rapidly, whereas myocardium retained 11C activity with a long tissue half-life. Relative tracer retention in the myocardium averaged 79 +/- 31% of peak activity at 60 minutes after tracer injection. The heart-to-blood 11C activity ratio exceeded 6:1 as soon as 30 minutes after tracer injection, yielding excellent image quality. Little regional variation of tracer retention was observed, indicating homogeneous sympathetic innervation throughout the left ventricle. In the transplant recipients, myocardial [11C]hydroxyephedrine retention at 60 minutes was significantly less (-82%) than that of normal volunteers, indicating only little non-neuronal binding of the tracer in the denervated human heart. Thus, [11C]hydroxyephedrine, in combination with dynamic PET imaging, allows the noninvasive delineation of myocardial adrenergic nerve terminals. Tracer kinetic modeling may permit quantitative assessment of myocardial catecholamine uptake, which will in turn provide insights into the effects of various disease processes on the neuronal integrity of the heart.
authors.affiliation: University of Michigan Medical Center, Department of Internal Medicine, Ann Arbor 48109-0028.
authors.forename: M
authors.initials: M
authors.lastname: Schwaiger
authors.forename: V
authors.initials: V
authors.lastname: Kalff
authors.forename: K
authors.initials: K
authors.lastname: Rosenspire
authors.forename: M S
authors.initials: MS
authors.lastname: Haka
authors.forename: E
authors.initials: E
authors.lastname: Molina
authors.forename: G D
authors.initials: GD
authors.lastname: Hutchins
authors.forename: M
authors.initials: M
authors.lastname: Deeb
authors.forename: E
authors.initials: E
authors.lastname: Wolfe
authors.forename: D M
authors.initials: DM
authors.lastname: Wieland
mesh_terms: D000328:Adult; D002250:Carbon Radioisotopes; D055598:Chemical Phenomena; D002621:Chemistry; D004809:Ephedrine / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D005240:Feasibility Studies; D006329:Heart Conduction System / Q000000981:diagnostic imaging*; D016027:Heart Transplantation; D006352:Heart Ventricles; D006801:Humans; D009206:Myocardium / Q000378:metabolism; D012016:Reference Values; D013564:Sympathetic Nervous System / Q000000981:diagnostic imaging*; D013997:Time Factors; D014018:Tissue Distribution; D014055:Tomography, Emission-Computed
chemical_list: D002250:Carbon Radioisotopes; C026055:oxilofrine; D004809:Ephedrine