How Do PET Myocardial Blood Flow Reserve and FFR Differ?

Area of Science:

• Cardiology
• Medical Imaging
• Physiology

Background:

• Cardiac positron emission tomography (PET) and invasive fractional flow reserve (FFR) are key diagnostic tools in cardiology.
• Both techniques assess coronary hemodynamics and guide revascularization decisions.
• FFR is the invasive reference standard, supported by extensive randomized evidence.

Purpose of the Study:

• To compare cardiac PET and FFR, highlighting their similarities and differences.
• To discuss absolute myocardial blood flow (MBF) measured by PET versus relative flow reserve assessed by FFR.
• To review the evolving roles of both modalities in clinical practice.

Main Methods:

• Comparative review of cardiac PET and invasive FFR.
• Analysis of diagnostic capabilities, including absolute vs. relative flow assessment.
• Evaluation of spatial resolution and imaging scope (entire left ventricle vs. specific lesions).

Main Results:

• Cardiac PET measures absolute myocardial blood flow non-invasively, imaging the entire left ventricle.
• FFR provides a relative flow reserve with high spatial resolution, particularly for specific lesions.
• Both methods are repeatable, technically successful, and account for distal myocardial mass.
• Recent evidence supports both techniques in guiding revascularization based on high-quality physiology.

Conclusions:

• Cardiac PET offers a lower-risk, non-invasive alternative for assessing global myocardial blood flow.
• FFR remains the invasive gold standard with unparalleled spatial resolution and evidence base.
• Both modalities are crucial for guiding revascularization decisions, with complementary strengths.
• Cardiac PET's clinical outcome data is expanding, while FFR's role as a reference standard is solidified.