Dr. Jamshid Maddahi

DMBN Web Exclusive: PET vs. SPECT in CAD detection

June 27, 2011
by Olga Deshchenko, DOTmed News Reporter
The PET industry is hoping to get a boost from the approval of new radiopharmaceutical agents in the next few years.

And one company, Lantheus Medical Imaging, Inc, recently shared the results of its phase 2 clinical trial of Flurpiridaz F 18, a novel myocardial perfusion PET agent.

To learn more about the agent, DOTmed News caught up with Dr. Jamshid Maddahi, the study's lead principal investigator. He is also a professor of molecular and medical pharmacology and cardiology at the David Geffen School of Medicine at the University of California, Los Angeles.

Can you provide some background on your involvement and work in cardiology?

Dr. Maddahi: I began my research work in the field of Nuclear Cardiology in 1977. I have been conducting most of my research in two main areas: 1) assessment of myocardial perfusion for noninvasive detection and evaluation of coronary artery disease, and 2) evaluation of myocardial viability in the management of heart failure patients. Our research work in myocardial perfusion assessment evolved from the planar imaging modality to SPECT and then the PET method. We have also evaluated various myocardial perfusion imaging agents; initially thallium-201, then Tc-99m labeled agents and more recently flurpiridaz F 18.

You presented on Phase 2 clinical trial data on flurpiridaz F 18 at ICNC10. What is this PET agent and what potential does it hold?

Dr. Maddahi: Flurpiridaz F 18 is a new myocardial perfusion PET agent that has several advantages as compared to the most commonly used current alternative agent, rubidium-82. It is more practical because it can be produced by existing regional cyclotron facilities and can be used in conjunction with treadmill exercise testing. Also, flurpiridaz F 18 image quality is expected to be superior because of a higher image resolution and myocardial extraction fraction. These properties would potentially translate to improved detection of coronary artery disease and better quantitation of myocardial blood flow.

In the Phase 2 trial, 143 patients from 21 centers underwent rest and stress PET and SPECT myocardial perfusion imaging and were evaluated for safety. Can you share some of the major highlights from the results of this trial?

Dr. Maddahi: Results from this Phase 2 trial show that PET myocardial perfusion imaging with flurpiridaz F 18 demonstrate a strong safety profile and is superior to Tc-99m labeled SPECT imaging with respect to the quality of rest and stress images, certainty of image interpretation, and diagnostic performance as measured by standard Receiver Operating Characteristic (ROC) analysis for detecting coronary artery disease.

Were you expecting to see such results or were you surprised by any of the study's findings?

Dr. Maddahi: We were not surprised. The results were in line with what we expected based on this agent’s properties and our earlier preliminary findings.

Currently, SPECT is the leading modality for the detection of cardiovascular disease. What are the advantages of MPI with PET? If and when this agent is approved, do you think PET will rival or outpace SPECT in this imaging area?

Dr. Maddahi: It is well documented that PET MPI with the currently approved agents (such as rubidium-82 and N-13 ammonia) is superior to SPECT because of better image quality, faster imaging protocols, higher diagnostic performance, and the ability to quantify myocardial blood flow. As I stated earlier, PET MPI with flurpiridaz F 18 has the potential to be more desirable than these current PET agents.

If flurpiridaz F 18 is approved, we believe that PET will ultimately outpace SPECT in cardiac imaging. But, we should not lose sight of the fact that we have a long road ahead, with much research and development, to accomplish this goal.