Left ventricular ejection fraction, myocardial blood flow and hemodynamic variables in adenosine and regadenoson vasodilator 82-Rubidium PET

AIMS

In most Rubidium-(Rb)-positron emission tomography (PET) studies, dipyridamole was used as vasodilator. The aim was to evaluate vasodilator PET left ventricular ejection fraction (LVEF), myocardial blood flow (MBF), hemodynamics, and the influence of adenosine and regadenoson on these variables.

METHODS AND RESULTS

Consecutive patients (N = 2299) with prior coronary artery disease (CAD) or no prior CAD undergoing adenosine/regadenoson 82Rb-PET were studied and compared according to CAD status and normal/abnormal PET (summed stress score 0-3 vs. ≥4). Rest and stress LVEF differed significantly depending on CAD status and scan results. In patients with no prior CAD, rest/stress LVEF were 68% and 72%, in patients with prior CAD 60% and 63%. LVEF during stress increased 5 ± 6% in normal compared to 1 ± 8% in abnormal PET (P<0.001). Global rest myocardial blood flow(rMBF), stress MBF(sMBF) and myocardial flow reserve (sMBF/rMBF) were significantly higher in no prior CAD patients compared to prior CAD patients(1.3 ± 0.5, 3.3 ± 0.9, 2.6 ± 0.8 and 1.2 ± 0.4, 2.6 ± 0.8, 2.4 ± 0.8 ml/g/min, respectively, P<0.001) and in normal versus abnormal scans, irrespective of CAD status(no prior CAD: 1.4 ± 0.5, 3.5 ± 0.8, 2.8 ± 0.8 and 1.2 ± 0.8, 2.5 ± 0.8, 2.2 ± 0.7; prior CAD: 1.3 ± 0.4, 3.1 ± 0.8, 2.7 ± 0.8 and 1.1 ± 0.4, 2.3 ± 0.7, 2.2 ± 0.7 ml/g/min, respectively, P<0.001). LVEF and hemodynamic values were similar for adenosine and regadenoson stress. Stress LVEF ≥70% excluded relevant ischemia (≥10%) with a negative predictive value (NPV) of 94% (CI 92-95%).

CONCLUSIONS

Rest/stress LVEF, LVEF reserve and MBF values are lower in abnormal compared to normal scans. Adenosine and regadenoson seem to have similar effect on stress LVEF, MBF and hemodynamics. A stress LVEF ≥70% has a high NPV to exclude relevant ischemia.

Quantification of Myocardial Perfusion With Vasodilation Using Arterial Spin Labeling at 1.5T

BACKGROUND

Myocardial perfusion is evaluated in first-pass MRI using a gadolinium-based contrast agent, which limits its repeatability and restricts its use in patients with abnormal kidney function. Arterial spin labeling (ASL) is a promising technique for measuring myocardial perfusion without contrast injection. The ratio of stress to rest perfusion, termed myocardial perfusion reserve (MPR), is an indicator of the severity of stenosis in patients with coronary artery disease (CAD).

PURPOSE

To quantify perfusion increases with pharmacological vasodilation, explore MPR differences between segments with and without perfusion defects, and examine the correlations between quantitative ASL and semiquantitative first-pass measurements.

STUDY TYPE

Prospective.

SUBJECTS

Sixteen patients with suspected CAD: 10 classified as "healthy," having normal perfusion on first-pass and no enhancement on late gadolinium enhancement (LGE), and six as "nonhealthy," having hypoperfused segments including ischemic and infarcted.

FIELD STRENGTH/SEQUENCE

Flow-sensitive alternating inversion recovery (FAIR) rest-stress cardiac ASL with balanced steady-state free precession (bSSFP), rest-stress first-pass imaging using gradient-echo and LGE using a phase-sensitive inversion-recovery bSSFP at 1.5T.

ASSESSMENT

For healthy subjects, rest-stress perfusion data were compared in global, coronary artery territory, and segment regions of interest (ROIs). A segmental MPR comparison was performed between normal segments from healthy subjects and abnormal segments from nonhealthy subjects. Correlations between ASL and first-pass parameters were explored.

STATISTICAL TESTS

Wilcoxon-signed-rank test, nonparametric factorial analysis of variance (ANOVA), and Pearson's/Spearman's correlations.

RESULTS

Perfusion increases were significant globally (P = 0.005), per coronary artery territory (P = 0.015), and per segment (P = 0.03 for all segments in ASL and first-pass, except anteroseptal in ASL P = 0.04). MPR differences between normal and abnormal segments were significant (P = 0.0028: ASL, P = 0.033: first-pass). ASL and first-pass measurements were correlated (MPR: r = 0.64, P = 0.008 and perfusion: rho = 0.47, P = 0.007).

DATA CONCLUSION

This study demonstrates the feasibility of ASL to detect hyperemia, the potential to differentiate segments with and without perfusion defects, and significant correlations between ASL and semiquantitative first-pass.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY STAGE: 1.