Abstract
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Objectives: The purpose of this investigation was to evaluate the feasibility of combining cardiac PET (CPET) with coronary CT angiography (CTA) in a single test interval, and to document the degree of concordance of the two studies.
Methods: 34 patients (11 with CAD) were prospectively enrolled and imaged with a PET/CT scanner (Discovery, General Electric Healthcare). Gated coronary CTA was performed with 120 kVp, 320 mA, 0.5sec rotation. CPET studies were performed with NH13 Ammonia 15 mCi at rest and 30 mCi at stress (exercise or pharmacologic). A 17 segment with 5 grade severity score system was used for interpretation of the CPET studies. All coronary arteries greater than 2 mm in size were graded on the CTA images for flow limiting stenosis 75% as well as for calcification.
Results: Imaging time was 90 minutes and average LVEF was 62%. Of the 34 patients, 8 demonstrated flow-limiting disease on coronary CTA. Of these, 7 had positive CPET studies in the same vascular distribution. Four of the patients without critical coronary stenosis on CTA had perfusion abnormalities on CPET. Overall concordance was 85% with most of the discordant findings likely representing different biological measurements. Discordant findings was also related to misregistration during attenuation correction and uninterpretable CTA due to severe vessel calcifications.
Conclusions: It is feasible to perform exercise or pharmacologic stress cardiac PET studies and CTA at a single testing interval to evaluate myocardial perfusion, LV function and coronary artery anatomy. Discordance between the two imaging modalities potentially may represent incremental information provided by the two tests. A more precise assessment of the relative importance of this imaging technology in patient management needs to be defined in a larger prospective trial.
Research Support (if any): GE Healthcare
- Society of Nuclear Medicine, Inc.