bms-747158-02 and Myocardial-Ischemia

As the second term of our commitment to Journal begins, we, the editors, would like to reflect on a few topics that have relevance today. These include prognostication and paradigm shifts; Serial testing: How to handle data? Is the change in perfusion predictive of outcome and which one? Ischemia-guided therapy: fractional flow reserve vs perfusion vs myocardial blood flow; positron emission tomography (PET) imaging using Rubidium-82 vs N-13 ammonia vs F-18 Flurpiridaz; How to differentiate microvascular disease from 3-vessel disease by PET? The imaging scene outside the United States, what are the differences and similarities? Radiation exposure; Special issues with the new cameras? Is attenuation correction needed? Are there normal databases and are these specific to each camera system? And finally, hybrid imaging with single-photon emission tomography or PET combined with computed tomography angiography or coronary calcium score. We hope these topics are of interest to our readers.

Topics: Ammonia; Coronary Artery Disease; Coronary Circulation; Coronary Vessels; Databases, Factual; Fractional Flow Reserve, Myocardial; Humans; Microcirculation; Multimodal Imaging; Myocardial Ischemia; Myocardial Perfusion Imaging; Nitrogen Radioisotopes; Positron Emission Tomography Computed Tomography; Positron-Emission Tomography; Predictive Value of Tests; Prognosis; Pyridazines; Rubidium Radioisotopes; Tomography, Emission-Computed, Single-Photon; United States

Positron emission tomography (PET) myocardial perfusion imaging (MPI) has high diagnostic accuracy and prognostic value. PET-MPI can also be used to quantitatively evaluate regional myocardial blood flow (MBF). This technique also allows the calculation of the coronary flow reserve (CFR)/myocardial flow reserve (MFR), which is the ratio of MBF at peak hyperemia to resting MBF. Coronary computed tomography angiography (CTA) is a non-invasive method for accurate detection and exclusion of high-grade coronary stenoses, when compared to an invasive coronary angiography reference standard. However, CTA assessment of coronary stenoses tends toward overestimation, and CTA cannot determine physiologic significance of lesions. Recent advances in computational fluid dynamics and image-based modeling permit calculation of non-invasive fractional flow reserve derived from CT (FFRCT), without the need for additional imaging, modification of acquisition protocols, or administration of medications. In this review, we cover the CFR/MFR assessment by PET and FFR assessment by CT.

Topics: Contrast Media; Coronary Angiography; Coronary Circulation; Coronary Stenosis; Female; Fractional Flow Reserve, Myocardial; Humans; Male; Models, Cardiovascular; Myocardial Ischemia; Positron-Emission Tomography; Prognosis; Pyridazines; Reference Standards; Regional Blood Flow; Reproducibility of Results

Absolute quantitation of myocardial blood flow (MBF) by PET is an established method of analyzing coronary artery disease (CAD) but subject to the various shortcomings of available radiotracers. Flurpiridaz F 18 is a novel PET radiotracer that exhibits properties of an ideal tracer.. A new absolute perfusion quantitation method with flurpiridaz was developed, taking advantage of the early kinetics and high first-pass extraction by the myocardium of this radiotracer, and the first-in-human measurements of MBF performed in 7 healthy subjects and 8 patients with documented CAD. PET images with time-activity curves were acquired at rest and during adenosine stress.. In healthy subjects, regional MBF between coronary artery territories did not differ significantly, leading to a mean global MBF of 0.73 mL/min/g at rest and 2.53 mL/min/g during stress, with a mean global myocardial flow reserve (MFR) of 3.70. CAD vascular territories with <50% stenosis demonstrated a mean MBF of 0.73 at rest and 2.02 during stress, leading to a mean MFR of 2.97. CAD vascular territories with ≥50% stenosis exhibited a mean MBF of 0.86 at rest and 1.43 during stress, leading to a mean MFR of 1.86. Differences in stress MBF and MFR between normal and CAD territories, as well as between <50% and ≥50% stenosis vascular territories, were significant (P < 0.01).. Absolute quantitation of MBF in humans with the novel PET radiotracer flurpiridaz is feasible over a wide range of cardiac flow in the presence or absence of stress-inducible myocardial ischemia. The significant decrease in stress MBF and ensuing MFR in CAD territories allows a clear distinction between vascular territories exhibiting stress-inducible myocardial ischemia and those with normal perfusion.

Topics: Aged; Coronary Circulation; Female; Fluorine Radioisotopes; Humans; Male; Myocardial Ischemia; Positron-Emission Tomography; Pyridazines