2011 IEEE Nuclear Science Symposium Conference Record MICI2.M-47 Respiratory Gating for A Stationary Dedicated Cardiac SPECT System Chi Liu l , Chung Chan l , Mark Harris 2 , Max Le 2 , James Biondi 2 , Lana Volokh 3 , and Albert Sinusas l , 4 I Department of Diagnostic Radiology, Yale University, New Haven, CT, USA 2 Ivy Biomedical Systems, Branford, CT, USA 3 GE Healthcare, Haifa, Israel 4 Section of Cardiovascular Medicine, Yale University, New Haven, CT, USA Abstract - Respiratory motion correction is challenging for conventional SPECT systems due to slow rotational data acquisition that leads to inconsistent temporal data. In this study, we developed respiratory gating techniques for a commercially available stationary cardiac SPECT system with multiple pinhole collimators, which acquire all projections simultaneously and avoid the limitation of slow gantry rotation. Respiratory motion was monitored by a compressive sensor attached to the patientllarge animal's lower chest and/or upper abdomen. Respiratory triggers at each end-inspiration peak or cardiac triggers only during end-expiration phases were sent to the GE 570c SPECT/CT system. Respiratory-gated and end-expiration gated images were generated and evaluated with respect to ungated images visually, and quantitatively using contrast recovery on a physical phantom, a canine study and human studies. The results demonstrated that respiratory gating can effectively improve the image quality and contrast for the stationary myocardial perfusion SPECT imaging. I. INTRODUCTION Respiratory motion is a major degrading factor of image quality in myocardial perusion SPECT due to added image blurring. Conventional SPECT systems use parallel-hole collimators and slowly rotate the detectors to acquire data rom all angles for image reconstruction. Therefore, a conventional SPECT projection set is temporally inconsistent and, at a given time point, is not able to provide all the projection data required for complete angle image reconstruction. Thus, correcting for respiratory motion is very challenging for conventional SPECT system due to the data acquisition methods with slow gantry rotation operated in step-and-shoot mode. A recently commercially introduced dedicated cardiac SPECT system (Discovery 530c/570c, GE Healthcare) uses 19 pinhole collimators instead of conventional parallel-hole collimators to focus the imaging ield-of-view to the heart and simultaneously acquires projections rom all viewing angles (as shown in igure 1). The detector and collimator geometry does not require gantry movement during data acquisition. Thus this is a truly stationary scanner that provides complete data for image reconstruction at any time period to facilitate respiratory motion correction. In this study, we developed respiratory monitoring systems and respiratory gating techniques for this stationary cardiac SPECT system, and evaluated the improvement in image quality with a phantom experiment, a large animal study, and human studies. 530c SPECT system 570c SPECT/CT system Figure I. GE Discovery 530c SPECT system and 570c hybrid SPECT/CT system (upper panel), and the arrangement of multiple pinhole collimators that allow stationary data acquisition (left) [I]. II. METHODS A. Respiratoy Monitoring Respiratory motion was monitored by a compressive sensor pillow attached to the patient/large animal's lower chest or upper abdomen, as illustrated in igure 2. Figure 2. Illustration of the pillow attached to a patient with an elasticized strap, and the air pressure changes as the chest or abdomen moves and compresses the pillow. The pillow detects pressure changes during respiratory cycle and sends respiratory motion information into a dual respiratory-cardiac gating box as shown in igure 3 (Ivy Biomedical Systems, Branford, CT), which will process the motion signal and send triggers to the ECG input of the GE Discovery 530c/570c scanners. B. Phantom Experiment A Data Spectrum cardiac phantom illed with Tc-99m was 978-1-4673-0120-6/11/$26.00 ©2011 IEEE 2898