Integrated Myocardial Perfusion Imaging Diagnostics Improve Detection of Functionally Significant Coronary Artery Stenosis by 13 N-ammonia Positron Emission Tomography

Exploring Coronary Circulatory Response to Stenosis and Its Association With Invasive Physiologic Indexes Using Absolute Myocardial Blood Flow and Coronary Pressure

Background:

Although invasive physiological assessment for coronary stenosis has become a standard practice to guide treatment strategy, coronary circulatory response and changes in invasive physiological indexes, according to different anatomic and hemodynamic lesion severity, have not been fully demonstrated in patients with coronary artery disease.

Methods:

One hundred fifteen patients with left anterior descending artery stenosis who underwent both 13 N-ammonia positron emission tomography and invasive physiological measurement were analyzed. Myocardial blood flow (MBF) measured with positron emission tomography and invasively measured coronary pressures were used to calculate microvascular resistance and stenosis resistance.

Results:

With progressive worsening of angiographic stenosis severity, both resting and hyperemic transstenotic pressure gradient and stenosis resistance increased ( P <0.001 for all) and hyperemic MBF ( P <0.001) and resting microvascular resistance ( P =0.012) decreased. Resting MBF ( P =0.383) and hyperemic microvascular resistance ( P =0.431) were not changed and maintained stable. Both fractional flow reserve and instantaneous wave-free ratio decreased as angiographic stenosis severity, stenosis resistance, and transstenotic pressure gradient increased and hyperemic MBF decreased (all P <0.001). When the presence of myocardial ischemia was defined by both low hyperemic MBF and low coronary flow reserve, the diagnostic accuracy of fractional flow reserve and instantaneous wave-free ratio did not differ, regardless of cutoff values of hyperemic MBF and coronary flow reserve.

Conclusions:

This study demonstrated how the coronary circulation changes in response to increasing coronary stenosis severity using 13 N-ammonium positron emission tomography–derived MBF and invasively measured pressure data. Currently used resting and hyperemic pressure–derived invasive physiological indexes have similar patterns of relationships to the different anatomic and hemodynamic lesion severities.

Clinical Trial Registration:

URL: https://www.clinicaltrials.gov . Unique identifier: NCT01366404.

Fully quantitative cardiovascular magnetic resonance myocardial perfusion ready for clinical use: a comparison between cardiovascular magnetic resonance imaging and positron emission tomography

BACKGROUND

Recent studies have shown that quantification of myocardial perfusion (MP) at stress and myocardial perfusion reserve (MPR) offer additional diagnostic and prognostic information compared to qualitative and semi-quantitative assessment of myocardial perfusion distribution in patients with coronary artery disease (CAD). Technical advancements have enabled fully automatic quantification of MP using cardiovascular magnetic resonance (CMR) to be performed in-line in a clinical workflow. The aim of this study was to validate the use of the automated CMR perfusion mapping technique for quantification of MP using 13N-NH3 cardiac positron emission tomography (PET) as the reference method.

METHODS

Twenty-one patients with stable CAD were included in the study. All patients underwent adenosine stress and rest perfusion imaging with 13N-NH3 PET and a dual sequence, single contrast bolus CMR on the same day. Global and regional MP were quantified both at stress and rest using PET and CMR.

RESULTS

There was good agreement between global MP quantified by PET and CMR both at stress (-0.1 ± 0.5 ml/min/g) and at rest (0 ± 0.2 ml/min/g) with a strong correlation (r = 0.92, p < 0.001; y = 0.94× + 0.14). Furthermore, there was strong correlation between CMR and PET with regards to regional MP (r = 0.83, p < 0.001; y = 0.87× + 0.26) with a good agreement (-0.1 ± 0.6 ml/min/g). There was also a significant correlation between CMR and PET with regard to global and regional MPR (r = 0.69, p = 0.001 and r = 0.57, p < 0.001, respectively).

CONCLUSIONS

There is good agreement between MP quantified by 13N-NH3 PET and dual sequence, single contrast bolus CMR in patients with stable CAD. Thus, CMR is viable in clinical practice for quantification of MP.