New F-18-based tracers hailed as nuclear cardiology highlight

One of the highlights in nuclear medicine research at the American College of Cardiology conference was the new data on a number of promising new F-18-based PET imaging agents, according to James A. Arrighi, MD, education chair for the American Society for Nuclear Cardiology and the ACC nuclear cardiology spotlight chair.

Stephan G. Nekolla, PhD, and colleagues at the Technical University in Munich, Germany, found that F-18 BMS showed a very high and specific myocardial uptake, an up to threefold increase in target to background ratio and the potential for absolute flow quantification compared with a conventional approach (13N-NH3) in pigs.

Arrighi also noted the increased importance of looking at fatty acid metabolism, which is central to many disease processes that affect the myocardium. In patients with coronary artery disease, left ventricular dysfunction and dilated cardiomyopathy, fatty acid metabolism is reduced. 

A traditional SPECT imaging agent such as I-123 BMIPP looks only at uptake of triglyceride formation and tells nothing of fatty acid oxidation, according to a lecture by Robert J. Gropler, MD, director of the Cardiac Stress Labs and Nuclear Cardiology at Washington University School of Medicine in St. Louis, Mo. Fatty acid analogues such as 18-F FTHA, 18-F FTP and 18-F FCPHA delve further into the oxidation pathways, potentially enabling earlier detection of pathology related to reduced fatty acids.

I-123 BMIPP, however, can be used to look at the concept of ischemic “memory,” Gropler said. Researchers injected I-123 BMIPP into patients a day or two after they experienced chest pain and found metabolic evidence of an ischemic event.

While Arrighi was encouraged by the new tracer research, he cautioned that much of it is in the beginning stages. “Prior to the widespread use of any new imaging agent, which necessarily will involve certain costs, there must be solid data that indicate the clinical utility of the new agent. Ideally, this should include outcomes data,” he told Cardiovascular Business News.

An important highlight, according to Arrighi, is the development of new selective adenosine agonists (A2A agents). In one study, James E. Udelson, MD, and colleagues at Tufts-New England Medical Center in Boston showed that binodenoson detected a measure of the extent and severity of ischemia equivalently to adenosine in the same patients, was associated with fewer and less intense side effects, and was tolerated better than adenosine in a phase 3 trial.

“The use of these agents in practice will depend primarily on price, demonstration of enhanced safety/tolerability, and at least equal efficacy to existing agents,” Arrighi said.

A final highlight from Arrighi is the new gamma camera technology that was discussed at the ACC conference. UltraSPECT, based in Israel, touts wide-beam reconstruction (WBR) technology that allows shortened acquisition times and increased image resolution. The company recently signed an agreement to give Cardinal Health exclusive U.S. distribution rights for UltraSPECT’s WBR image processing packages for cardiac imaging. Philips Medical Systems is working on Astonish, an advanced reconstruction solution to improve resolution.
            
Spectrum Dynamics, also based in Israel, goes further by including innovative hardware designs as well as advanced reconstruction software in its D-SPECT scanner. The BroadView imaging technology provides improved sensitivity by collecting photons using larger collection angles, a novel design of scanning solid state detectors, and proprietary image reconstruction techniques.