Stagnation and Development

Myocardial perfusion imaging is both an old and evolving diagnostic test. Since the 1990s, the development of electrocardiogram-gated imaging reached its peak, enabling quantitative assessment of cardiac function and myocardial perfusion using QGS and QPS software. This method has been recognized as one of the most convenient and valuable tools, particularly for differentiating ischemic from non-ischemic cardiomyopathy.

Furthermore, predicting cardiac events based on ejection fraction and the extent of ischemic myocardium has become a powerful clinical approach. However, advances in medical therapy that reduce cardiac events and lifestyle changes leading to more patients with low pre-test probability have highlighted the limitations of traditional methods. Recently, left ventricular dyssynchrony indices, such as entropy, have gained attention as comprehensive indicators for assessing heart failure, regardless of whether it is ischemic or non-ischemic.

In the United States, the new PET agent ¹⁸F flurpiridaz (brand name FLYRCADO) was approved last year. Compared with ^99mTc agents, it demonstrated significantly higher sensitivity for detecting coronary artery disease (80% vs. 69%, p = 0.0003) and non-inferior specificity (64% vs. 62%, p = 0.0004). This PET agent has shown particular usefulness in women and in patients with a BMI ≥ 30. Moreover, the flurpiridaz group outperformed ^99mTc agents in evaluating defect size and severity, image quality, diagnostic confidence, and radiation dose reduction.

Previously, when ^99mTc agents replaced ²⁰¹Tl, electrocardiogram-gated imaging achieved remarkable progress. Although the development of ¹⁸F flurpiridaz has stalled in Japan, its eventual introduction will undoubtedly bring significant advancement to cardiac nuclear medicine and serve as a new strength in our field.