Myocardial Perfusion Imaging With PET: A Head-to-Head Comparison of 82Rubidium Versus 15O-water Tracers Using Invasive Coronary Measurements as Reference.

BACKGROUND

Myocardial perfusion imaging by positron emission tomography (PET) is recommended as a first-line test in stable patients with chest pain symptoms and as a selective second-line test after an abnormal coronary computed tomography angiography (CTA). It is, however, unknown whether the use of Rubidium-82 (82Rb) versus [15O]H2O (15O-water) affects the diagnostic performance in coronary artery disease (CAD). The aim of this study was to compare 82Rb-PET versus 15O-water-PET head-to-head for diagnosing obstructive CAD.

METHODS

The study included consecutive patients (n=1000) referred for CTA with symptoms suggestive of obstructive CAD. Patients with suspected stenosis based on CTA were referred for both 82Rb-PET, 15O-water-PET, and subsequently invasive coronary angiography (ICA), including 3-vessel fractional flow reserve and coronary flow reserve measurements.

RESULTS

In total, 196/270 (73%) patients with suspected stenosis on CTA completed 82Rb-PET, 15O-water-PET, and ICA. Myocardial blood flow measurements from 82Rb-PET and 15O-water-PET correlated strongly at rest (ρ, 0.62-0.69) but only moderately during hyperemia (ρ, 0.41-0.59). Only weak correlations were demonstrated between myocardial blood flow reserve by both PET tracers compared with ICA coronary flow reserve (ρ, 0.11-0.38). Hemodynamically obstructive CAD defined as ICA fractional flow reserve ≤0.80, was identified in 86/196 (44%) patients. Using predefined cutoffs, the diagnostic accuracies of 82Rb-PET versus 15O-water-PET were similar (sensitivity 69% [58-78%] versus 71% [60-80%], P=0.59; specificity 85% [76-91%] versus 77% [68-85%], P=0.12). Using ICA diameter stenoses >70% as a reference, only 48/196 (24%) patients had anatomically severe CAD, and 82Rb-PET and 15O-water-PET sensitivities increased to >85%.

CONCLUSIONS

For detection of obstructive CAD by PET myocardial perfusion imaging, 82Rb versus 15O-water have similar diagnostic performance.

REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT04707859.