Absolute PET Myocardial Blood Flow Quantification in the Diagnosis and Risk Stratification of Coronary Microvascular Dysfunction

Figures

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  Fig. 1.. Schematic overview of the coronary arterial system with associated functional and structural indices. Under physiological conditions, arterioles and capillaries contain the largest fraction of IMBV, while pre-arterioles and arterioles serve as the primary determinants of coronary vascular resistance. Epicardial coronary arteries contribute negligibly to both total coronary resistance and IMBV. FFR, fractional flow reserve; IMR, index of microcirculatory resistance; MFR, myocardial flow reserve; IMBV, intramyocardial blood volume.

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  Fig. 2.. Schematic overview of the measurement of MBF using PET. The association between myocardial tracer uptake and MBF for PET radiotracers demonstrates a roll-off phenomenon at high flow rates, as the uptake of some radiotracers becomes diffusion-limited at higher flows. This contributes to reduced accuracy when quantifying hyperemic coronary flow and MFR. PET, positron emission tomography; MBF, myocardial blood flow; LV, left ventricular.

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  Fig. 3.. Standardized workflow for dynamic PET-based absolute myocardial blood flow quantification in clinical practice and research. PET, positron emission tomography; MBF, myocardial blood flow; HR, heart rate; BP, blood pressure; ECG, electrocardiogram; ROI, region of interest; TAC, time-activity curve; MFR, myocardial flow reserve.

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  Fig. 4.. Cardiac PET imaging and invasive coronary angiography in a 59-year-old woman with coronary microvascular dysfunction. (A) Hyperemic flow stimulation with regadenoson and rest 13N-ammonia PET images in corresponding short-axis (top), horizontal long-axis (middle), and vertical long-axis (bottom) slices. (B) Quantification of myocardial blood flow. Regional MBF quantification of hyperemic MBF and at rest with resulting MFR calculation using 13N-ammonia PET and tracer kinetic modeling. A global reduction in hyperemic MBF was observed across all three coronary territories (all <1.85 mL/g/min). Hyperemic MBF was less impaired in the LCx territory, such that MFR was considered borderline-normal (2.00). Preserved MFR was evident in the RCA territory (2.16) despite a significant reduction in hyperemic MBF, with this finding being explained by the relatively lower resting MBF for this territory (0.64 mL/g/min). (C) Invasive coronary angiography confirmed the absence of clinically significant coronary artery stenoses. MFR, myocardial flow reserve; PET, positron emission tomography; MBF, myocardial blood flow; LAD, left anterior descending; LCx, left circumflex; RCA, right coronary artery.

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  Fig. 5.. PET-guided diagnostic and prognostic algorithm for patients with suspected angina and ischemia with no obstructive coronary artery disease. ANOCA, angina with no obstructive coronary artery disease; INOCA, ischemia with no obstructive coronary artery disease; CAD, coronary artery disease; CAG, invasive coronary angiography; CTA, computed tomography angiography; FFR, fractional flow reserve; MFR, myocardial flow reserve; MACE, major adverse cardiovascular events; HFpEF, heart failure with preserved ejection fraction; CKD, chronic kidney disease; ACEI, angiotensin-converting enzyme inhibitor; ARB, angiotensin II receptor blocker; CCB, calcium channel blocker.