What is ischemia and how should this be defined based on modern imaging?

Area of Science:

• Cardiology
• Medical Imaging
• Nuclear Cardiology

Background:

• Accurate definition of myocardial ischemia is clinically significant but challenging.
• Various imaging modalities exist, each with inherent strengths and limitations.
• Understanding these methods is key for effective patient management.

Purpose of the Study:

• To review and compare different cardiac imaging techniques for quantifying myocardial ischemia.
• To discuss the practical utility, strengths, and weaknesses of each modality.
• To propose an integrative approach for improved ischemia assessment.

Main Methods:

• Review of existing literature on cardiac imaging for myocardial ischemia.
• Comparison of anatomic assessments (angiography, FFR, IVUS).
• Evaluation of non-invasive metabolic and physiologic assessments (SPECT, PET).

Main Results:

• Anatomic methods like angiography have limitations.
• Invasive measures (FFR, IVUS) offer improvements but have weaknesses.
• Non-invasive metabolic and physiologic assessments provide valuable data but face clinical challenges.
• Cardiac PET with absolute myocardial flow measurement shows promise.

Conclusions:

• No single modality perfectly assesses myocardial ischemia.
• An integrative approach combining relative uptake and absolute myocardial flow with cardiac PET offers enhanced accuracy.
• Cardiac PET imaging provides a comprehensive tool for evaluating myocardial ischemia.