title: Automatic Cardiac Self-Gating of Small-Animal PET Data.
abstract: OBJECTIVE
  The cardiac gating signal (CGS) in positron emission tomography (PET) studies is usually obtained from an electrocardiography (ECG) monitor. In this work, we propose a method to obtain the CGS in small-animal PET using the acquired list-mode data without using any hardware or end-user input.
  
  
  METHODS
  The CGS was obtained from the number of coincidences over time acquired in the lines-of-response connected with the cardiac region. This region is identified in the image as its value changes with frequencies in the range of 3 to 12 Hz. The procedure was tested in a study with 29 Wistar rats and 6 mice injected with 2-deoxy-2-[(18)F]fluoro-D-glucose, which underwent a 45-min single-bed list-mode PET scan of the heart syncronized with an ECG. The estimated signals and the reconstructed images using eight-gated frames were compared with the ones obtained using the ECG signal from the monitor.
  
  
  RESULTS
  The differences of the PET-based CGS with respect to the ECG relative to the duration of the heartbeats were 5.6 % in rats and 11.0 % in mice. The reconstructed gated images obtained from the proposed method do not differ qualitatively with respect to the ones obtained with the ECG. The quantitative analysis of both set of images were performed measuring the volume of the left ventricle (LV) of the rats in the end-of-systole and end-of-diastole phase. The differences found in these parameters between both methods were below 12.1 % in the ESV and 9.3 % in the EDV with a 95 % confidence interval, which are comparable to the accuracy (7 %) of the method used for segmenting the LV.
  
  
  CONCLUSIONS
  The proposed method is able to provide a valid and accurate CGS in small-animal PET list-mode data.
authors.affiliation: Madrid-MIT M+Vision Consortium, Massachusetts Institute of Technology, Cambridge, MA, USA. herraiz@mit.edu.|Grupo de Física Nuclear, Universidad Complutense de Madrid, CEI Moncloa, Madrid, Spain. herraiz@mit.edu.
authors.forename: Joaquin L
authors.initials: JL
authors.lastname: Herraiz
authors.affiliation: A.A.Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA.|Harvard Medical School, Boston, MA, USA.
authors.forename: Elena
authors.initials: E
authors.lastname: Herranz
authors.affiliation: Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.
authors.forename: Jacobo
authors.initials: J
authors.lastname: Cal-González
authors.affiliation: Departamento de Ingenieria Biomedica e Ingeniería Aeroespacial, Universidad Carlos III de Madrid, Leganés, Spain.|Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain.
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Vaquero
authors.affiliation: Departamento de Ingenieria Biomedica e Ingeniería Aeroespacial, Universidad Carlos III de Madrid, Leganés, Spain.|Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain.|Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Madrid, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Desco
authors.affiliation: Departamento de Ingenieria Biomedica e Ingeniería Aeroespacial, Universidad Carlos III de Madrid, Leganés, Spain.|Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain.|Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Madrid, Spain.
authors.forename: Lorena
authors.initials: L
authors.lastname: Cussó
authors.affiliation: Grupo de Física Nuclear, Universidad Complutense de Madrid, CEI Moncloa, Madrid, Spain.
authors.forename: Jose M
authors.initials: JM
authors.lastname: Udias
mesh_terms: D000818:Animals; D001331:Automation; D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D003971:Diastole; D006339:Heart Rate; D051379:Mice; D049268:Positron-Emission Tomography / Q000379:methods*; D017208:Rats, Wistar; D059629:Signal-To-Noise Ratio; D013599:Systole
keywords: Cardiac gating; List-mode; PET; Self-gating; Small animal