Longitudinal myocardial blood flow gradient and CAD detection

Area of Science:

• Cardiovascular Imaging
• Nuclear Cardiology
• Radiology

Background:

• Conventional SPECT/CT and PET/CT are key for diagnosing obstructive coronary artery disease (CAD) and risk stratification.
• Assessing relative radiotracer uptake identifies the most severe CAD lesion but may miss flow-limiting effects of other lesions.
• Myocardial flow-limiting effects of less severe epicardial lesions in multivessel disease can be overlooked by standard imaging.

Purpose of the Study:

• To explore the utility of PET/CT with kinetic modeling for assessing myocardial blood flow (MBF) and myocardial flow reserve (MFR).
• To investigate the potential of combining MFR with longitudinal flow gradients for improved CAD characterization.
• To enhance the identification and characterization of hemodynamic CAD burden in patients with multivessel disease.

Main Methods:

• Utilized PET/CT with radiotracer-kinetic modeling to measure resting and stress MBF (ml/g/min).
• Calculated myocardial flow reserve (MFR) from resting and stress MBF measurements.
• Assessed longitudinal flow gradients (decrease in MBF from base to apex) during hyperemia.

Main Results:

• Reduced MFR can reflect both epicardial stenosis and microvascular dysfunction, limiting specificity.
• Longitudinal flow gradients during hyperemia show promise in reflecting fluid dynamic consequences of epicardial CAD.
• Combined evaluation of MFR and longitudinal MBF gradients may offer a novel approach to assess hemodynamic CAD burden.

Conclusions:

• PET/CT with kinetic modeling offers advanced assessment of MBF and MFR beyond relative uptake.
• Longitudinal flow gradients may help differentiate epicardial from microvascular contributions to reduced MFR.
• Combined MFR and longitudinal flow gradient analysis warrants further clinical validation for optimizing CAD assessment.