title: Simultaneous ECG-gated PET imaging of multiple mice.
abstract: BACKGROUND
  We describe and illustrate a method for creating ECG-gated PET images of the heart for each of several mice imaged at the same time. The method is intended to increase "throughput" in PET research studies of cardiac dynamics or to obtain information derived from such studies, e.g. tracer concentration in end-diastolic left ventricular blood.
  
  
  METHODS
  An imaging bed with provisions for warming, anesthetic delivery, etc., was fabricated by 3D printing to allow simultaneous PET imaging of two side-by-side mice. After electrode attachment, tracer injection and placement of the animals in the scanner field of view, ECG signals from each animal were continuously analyzed and independent trigger markers generated whenever an R-wave was detected in each signal. PET image data were acquired in "list" mode and these trigger markers were inserted into this list along with the image data. Since each mouse is in a different spatial location in the FOV, sorting of these data using trigger markers first from one animal and then the other yields two independent and correctly formed ECG-gated image sequences that reflect the dynamical properties of the heart during an "average" cardiac cycle.
  
  
  RESULTS
  The described method yields two independent ECG-gated image sequences that exhibit the expected properties in each animal, e.g. variation of the ventricular cavity volumes from maximum to minimum and back during the cardiac cycle in the processed animal with little or no variation in these volumes during the cardiac cycle in the unprocessed animal.
  
  
  CONCLUSIONS
  ECG-gated image sequences for each of several animals can be created from a single list mode data collection using the described method. In principle, this method can be extended to more than two mice (or other animals) and to other forms of physiological gating, e.g. respiratory gating, when several subjects are imaged at the same time.
authors.affiliation: Molecular Imaging Program, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA; Contractor to Leidos Biomedical Research, Inc., Frederick, MD, USA. Electronic address: jseidel1@mail.nih.gov.
authors.forename: Jurgen
authors.initials: J
authors.lastname: Seidel
authors.affiliation: Molecular Imaging Program, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA; Leidos Biomedical Research, Inc., Frederick, MD, USA.
authors.forename: Marcelino L
authors.initials: ML
authors.lastname: Bernardo
authors.affiliation: Molecular Imaging Program, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
authors.forename: Karen J
authors.initials: KJ
authors.lastname: Wong
authors.affiliation: Imaging Probe Development Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA; Kelly Services Inc., Troy, MI, USA.
authors.forename: Biying
authors.initials: B
authors.lastname: Xu
authors.affiliation: Molecular Imaging Program, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA; Leidos Biomedical Research, Inc., Frederick, MD, USA.
authors.forename: Mark R
authors.initials: MR
authors.lastname: Williams
authors.affiliation: Molecular Imaging Program, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA; Warren Grant Magnuson Clinical Center, National Institutes of Health, Bethesda, MD, USA.
authors.forename: Frank
authors.initials: F
authors.lastname: Kuo
authors.affiliation: Molecular Imaging Program, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
authors.forename: Elaine M
authors.initials: EM
authors.lastname: Jagoda
authors.affiliation: Imaging Probe Development Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA; Kelly Services Inc., Troy, MI, USA.
authors.forename: Falguni
authors.initials: F
authors.lastname: Basuli
authors.affiliation: Imaging Probe Development Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA; Kelly Services Inc., Troy, MI, USA.
authors.forename: Changhui
authors.initials: C
authors.lastname: Li
authors.affiliation: Molecular Imaging Program, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA; Clinical Research Directorate/CMRP, Leidos Biomedical Research, Inc. (formerly SAIC-Frederick, Inc.) Frederick National Laboratory for Cancer Research, Frederick, MD, USA.
authors.forename: Gary L
authors.initials: GL
authors.lastname: Griffiths
authors.affiliation: Molecular Imaging Program, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA; Contractor to Leidos Biomedical Research, Inc., Frederick, MD, USA.
authors.forename: Michael V
authors.initials: MV
authors.lastname: Green
authors.affiliation: Molecular Imaging Program, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
authors.forename: Peter L
authors.initials: PL
authors.lastname: Choyke
mesh_terms: D000818:Animals; D055424:Cardiac-Gated Imaging Techniques / Q000295:instrumentation / Q000379:methods*; D051379:Mice; D049268:Positron-Emission Tomography / Q000295:instrumentation / Q000379:methods*; D013997:Time Factors
keywords: Blood pool imaging; ECG-gated PET imaging; Pre-clinical cardiac PET imaging; [(18)F] albumin