Myocardial imaging with technetium-99m CPI: initial experience in the human

Area of Science:

• Nuclear Medicine
• Radiopharmaceutical Chemistry
• Cardiology

Background:

• Hexakis(isonitrile)technetium(I) analogs like [99mTc]carbomethoxyisopropyl isonitrile (CPI) exhibit promising myocardial uptake and clearance characteristics in preclinical studies.
• Evaluating novel radiotracers is crucial for advancing diagnostic capabilities in cardiovascular imaging.

Purpose of the Study:

• To assess the safety and efficacy of [99mTc]CPI as a myocardial imaging agent in humans.
• To determine the biodistribution and clearance kinetics of [99mTc]CPI in healthy individuals and patients with coronary artery disease (CAD).

Main Methods:

• Human studies involving three healthy volunteers and six patients diagnosed with CAD.
• Administration of [99mTc]CPI and subsequent planar imaging at various time points post-injection.
• Comparative analysis of imaging results during exercise and at rest, including repeat studies.

Main Results:

• [99mTc]CPI demonstrated rapid lung and liver clearance, with peak liver activity at 10-15 minutes.
• Excellent image quality with high myocardial to background ratios was achieved as early as 10 minutes post-injection.
• Myocardial defects indicative of CAD were visualized, with some defects resolving over time or with rest, while others persisted in patients with ongoing ischemia.

Conclusions:

• Technetium-99m CPI possesses favorable physical and biological properties for myocardial perfusion imaging, particularly in conjunction with exercise protocols.
• The tracer allows for effective visualization of myocardial perfusion deficits in patients with coronary artery disease.
• Further investigation may refine its role in diagnosing and managing CAD.