Abstract 13363: Cardiac Rubidium-82 Positron Emission Tomography as an ‘Area at Risk’ Marker. Comparison to the Gold Standard, Cardiac SPECT
Introduction: Determination of the area at risk (AaR) is essential in assessing myocardial salvage, which is an important surrogate marker when assessing new cardioprotective strategies. Single-photon emission computed tomography (SPECT) is considered the gold standard for measuring these parameters, however, it is logistically challenging and requires tracer injection prior to revascularization.
Hypothesis: We hypothesized that Rubidium (Rb)-82 Positron Emission Tomography (PET) can determine the AaR in myocardial infarction after the initial treatment with percutaneous coronary intervention.
Methods: Twelve patients with ST-elevation myocardial infarction were prospectively enrolled and prior to revascularization injected with Tc-99m-Sestamibi and after revascularization underwent cardiac SPECT imaging followed by cardiac Rb-82 PET. Quantitation of perfusion defect from both PET and SPECT was determined by an automated algorithm with a threshold of <50 % of normal counts considered as AaR and estimated as % of the left ventricle. In addition, absolute flow values (Lortie’s) from PET were compared to SPECT segments identified as AaR to obtain cut-off values with ROC analysis.
Results: Eleven patients (age 61±9 years) were included in the analysis (one patient excluded due to previous infarction). Time from onset of pain to treatment was 4.0±2.5h. SPECT and PET were performed 3.2±0.3 h and 32±7 h after Tc-Sestamibi injection, respectively. Mean AaR was 35.2±16.6% (SPECT extent) versus 28.1±16.1% (PET extent), resulting in a mean difference of 7.1% (p<0.05). The two modalities correlated well despite intervening revascularization, and differences in reconstruction algorithms (Spearman’s rho=0.86, p<0.001). Absolute rest flow (optimal cut-off value 0.99 mL/min/g) detected segments as AaR with sensitivity, specificity, accuracy, positive and negative predictive values of 70, 69, 70, 54 and 82%, respectively. Area under the ROC curve was 0.75 (CI: 0.68-0.83, p<0.0001)
Conclusions: Rb-82 PET performed after revascularization depicts a significant smaller AaR but correlates strongly with the established gold standard, SPECT. In contrast, absolute rest flows do not appear to be suitable for discriminating AaR from non-AaR areas
- Perfusion imaging
- Positron emission tomography
- Infarct size
- Percutaneous coronary intervention (PCI)
- Cardiac imaging
Author Disclosures: A.A. Ghotbi: None. P. Hasbak: None. T. Christensen: None. T. Engstrøm: None. H. Kelbæk: None. A. Kjær: None.
- © 2014 by American Heart Association, Inc.