Automated quantitative Rb-82 3D PET/CT myocardial perfusion imaging: normal limits and correlation with invasive coronary angiography

Abstract

Background: We aimed to characterize normal limits and to determine the diagnostic accuracy for an automated quantification of 3D 82-Rubidium (Rb-82) PET/CT myocardial perfusion imaging (MPI).

Methods: We studied 125 consecutive patients undergoing Rb-82 PET/CT MPI, including patients with suspected coronary artery disease (CAD) and invasive coronary angiography, and 42 patients with a low likelihood (LLk) of CAD. Normal limits for perfusion and function were derived from LLk patients. QPET software was used to quantify perfusion abnormality at rest and stress expressed as total perfusion deficit (TPD).

Results: Relative perfusion databases did not differ in any of the 17 segments between males and females. The areas under the receiver operating characteristic curve for detection of CAD were 0.86 for identification of ≥50% and ≥70% stenosis. The sensitivity/specificity was 86%/86% for detecting ≥50% stenosis and 93%/77% for ≥70% stenosis, respectively. In regard to normal limits, mean rest and stress left ventricular ejection fraction (LVEF) were 67% ± 10% and 75% ± 9%, respectively. Mean transient ischemic dilation ratio was 1.06 ± 0.14 and mean increase in LVEF with stress was 7.4% ± 6.1% (95th percentile of 0%).

Conclusion: Normal limits have been established for 3D Rb-82 PET/CT analysis with QPET software. Fully automated quantification of myocardial perfusion PET data shows high diagnostic accuracy for detecting obstructive CAD.

Figure 1

Rest/stress Rb-82 PET/CT protocol. * Adenosine; 140 µg/kg/min for 7 minutes ** CT transmission scan end-tidal expiration

Figure 2

Sex-independent polar map for rest and stress Rb-82 PET/CT mean normal myocardium distribution and SD in LLk of CAD patients (n = 42).

Figure 3

Mean normal distribution of wall motion (WM, mm) and wall thickening (WT, %) in LLk of CAD patients (n = 42).

Figure 4

PET images and quantitative polar maps from a patient with normal limits database (A). Uniform tracer distribution is noted with no quantitative abnormality. Abnormal PET images in patient with a 90% proximal LAD stenosis (B). A reversible perfusion defect is seen in the anterior, septal and apical walls both on the images and the polar maps. Stress and ischemic TPD were both 15%.

Figure 5

ROC curves for detection of CAD [≥50% diameter stenosis (A), ≥70% diameter stenosis (B)] by measurements of stress TPD and ischemic TPD in angiographic population (n = 83). Percentage TPD was compared with presence or absence of hemodynamically significant CAD as observed by ICA. Stress TPD ≥5% and ischemia TPD≥ 5% were used as cutoff points.

Figure 6

Sensitivity and specificity per patient (A) and per vessel [B (≥50% diameter stenosis), C (≥70% diameter stenosis)] for detection of CAD by stress TPD in angiographic population.