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Cardiovascular: Clinical ScienceUpdate on Cardiac PET |
1 Philips Medical Systems, Cleveland, Ohio; 2 University Hospitals of Cleveland, Case Medical Center, Cleveland, Ohio
294
Objectives: Myocardial perfusion imaging with Rb-82 poses unique challenges due to its rapid decay resulting in low count density, having the potential of affecting image quality. The goal of this study was to compare time-of-flight (ToF) image reconstruction to 3-D iterative RAMLA reconstruction in the context of Rb-82 perfusion imaging.
Methods: List mode data were chosen from 10 patients suspected of coronary artery disease and who had undergone a stress-rest cardiac perfusion protocol using 40 to 50 mCi of Rb-82. Data were acquired for 6 minutes, on a Philips GEMINI TF16 scanner and were reconstructed using both RAMLA (non-ToF) and ToF methods, with delays ranging from 120 and 300 seconds of the list mode data. In each case, a mid-ventricular slice from the transaxial images of the left ventricle was chosen for analysis. Regions of interest (ROIs) were manually drawn on the ventricular wall and the cavity, and the contrast-to-noise ratios (CNRs) of the RAMLA and ToF images were compared.
Results: Images reconstructed with the ToF method showed an average increase of 25% in the CNR as compared to those reconstructed with RAMLA. The superior CNR is maintained in the ToF images even with low-count density acquisitions.
Conclusions: Results of this study demonstrate that ToF reconstruction yields to superior quality cardiac perfusion images using Rb, with a higher CNR when compared to non-ToF. Moreover, even using data sets with very low count density, images reconstructed with the ToF method show good image quality, allowing for smaller doses to be used.
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