Researchers use PET/CT for molecular imaging of the heart

For the first time, researchers used positron emission tomography (PET)/computed tomography (CT) for imaging the subcellar function of the heart - from its subcellular function to its morphologic appearance. The results of the study were reported at the Society of Nuclear Medicine's 52nd Annual Meeting June 18–22 in Toronto.

"Our vision is to use PET/CT to dissect the biologic processes from gene expression to physiologic function to the morphologic appearance," said Frank M. Bengel, M.D., Nuklearmedizinische Klinik der TU-Muenchen, Munich, Germany. "In this study we explored the potential of PET/CT to achieve this goal, and the results of our experimental study with animals mark a new application of PET/CT for molecular imaging of the heart," added the co-author of "Hybrid PET/CT for Functional/Biological Characterization of Myocardial Molecular Interventions--A Multitracer Study in a Pig Model of Adenoviral VEGF Gene Transfer."

"To my knowledge, this is the first study using PET/CT for biologic characterization of a molecular intervention, showing the full potential of PET/CT as a translational imaging technique," said Bengel. "PET/CT will provide a better understanding of the basic mechanisms of cardiac gene therapy and, because it is applicable in animals and humans, will refine the translation of results obtained in experimental animals to a clinical setting in humans," he explained.

PET/CT is a novel diagnostic technique, combining imaging of the morphologic appearance with imaging of biology on the cellular and subcellular levels. "The latest generation of PET/CT cameras is equipped with a fast, multislice CT, which allows for imaging of the heart," detailed Bengel. "This multitracer, multimodality approach is already considered a breakthrough in tumor imaging," he added.

Within a single PET/CT imaging session, recently developed tracer techniques--which target the expression of genes that are transferred to the heart muscle and the expression of proteins involved in the growth of new blood vessels--were combined with techniques for measuring blood flow to the heart and for imaging morphologic appearance and contractile function of heart muscle, said Bengel. "In an experimental setting in pigs, these techniques allowed for profound insights into the effects of the transfer of a therapeutic gene to the heart muscle," he noted.

The transfer was achieved using an adenoviral vector. The transferred gene encodes for the vascular endothelial growth factor (VEGF), which has been used in previous studies to induce angiogenesis, a novel gene therapeutic approach that seeks to induce the growth of new blood vessels in areas of the heart that are not sufficiently supplied by blood due to severe coronary artery disease, detailed Bengel. "The PET/CT technique showed that successful transfer of the VEGF gene results in an increase of tissue perfusion (blood flow) without impairing cardiac contractile function or morphology. All information was obtained within a single, repeatable, noninvasive imaging session," he said.

"Hybrid PET/CT for Functional/Biological Characterization of Myocardial Molecular Interventions--A Multitracer Study in a Pig Model of Adenoviral VEGF Gene Transfer" was written by Bettina Wagner and Sybille Reder, Nuklearmedizinische Klinik, TU München, Munich, Germany; Martina Anton, Institut für Experimentelle Onkologie und Therapieforschung, TU München, Munich, Germany; Roland Haubner, Nuklearmedizinische Klinik, TU München, Munich, Germany; Julia Henke and Wolf Erhardt, Institut für Experimentelle Onkologie und Therapieforschung, TU München, Munich, Germany; Masao Miyagawa, Nuklearmedizinische Klinik, TU München, Munich, Germany; Renate Hegenloh and Stefan Seidl, Institut für Allgemeine Pathologie und Pathologische Anatomie, TU München, Munich, Germany; and Markus Schwaiger and Frank Bengel, Nuklearmedizinische Klinik, TU München, Munich, Germany.