title: Imaging of cardiac perfusion of free-breathing small animals using dynamic phase-correlated micro-CT.
abstract: OBJECTIVE
  Mouse models of cardiac diseases have proven to be a valuable tool in preclinical research. The high cardiac and respiratory rates of free breathing mice prohibit conventional in vivo cardiac perfusion studies using computed tomography even if gating methods are applied. This makes a sacrification of the animals unavoidable and only allows for the application of ex vivo methods.
  
  
  METHODS
  To overcome this issue the authors propose a low dose scan protocol and an associated reconstruction algorithm that allows for in vivo imaging of cardiac perfusion and associated processes that are retrospectively synchronized to the respiratory and cardiac motion of the animal. The scan protocol consists of repetitive injections of contrast media within several consecutive scans while the ECG, respiratory motion, and timestamp of contrast injection are recorded and synchronized to the acquired projections. The iterative reconstruction algorithm employs a six-dimensional edge-preserving filter to provide low-noise, motion artifact-free images of the animal examined using the authors' low dose scan protocol.
  
  
  RESULTS
  The reconstructions obtained show that the complete temporal bolus evolution can be visualized and quantified in any desired combination of cardiac and respiratory phase including reperfusion phases. The proposed reconstruction method thereby keeps the administered radiation dose at a minimum and thus reduces metabolic inference to the animal allowing for longitudinal studies.
  
  
  CONCLUSIONS
  The authors' low dose scan protocol and phase-correlated dynamic reconstruction algorithm allow for an easy and effective way to visualize phase-correlated perfusion processes in routine laboratory studies using free-breathing mice.
authors.affiliation: Institute of Medical Physics, Friedrich-Alexander-University, Erlangen, Germany. stefan.sawall@dkfz.de
authors.forename: Stefan
authors.initials: S
authors.lastname: Sawall
authors.forename: Jan
authors.initials: J
authors.lastname: Kuntz
authors.forename: Michaela
authors.initials: M
authors.lastname: Socher
authors.forename: Michael
authors.initials: M
authors.lastname: Knaup
authors.forename: Andreas
authors.initials: A
authors.lastname: Hess
authors.forename: Sonke
authors.initials: S
authors.lastname: Bartling
authors.forename: Marc
authors.initials: M
authors.lastname: Kachelrieß
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology; D055424:Cardiac-Gated Imaging Techniques / Q000379:methods / Q000662:veterinary*; D003326:Coronary Circulation / Q000502:physiology*; D003331:Coronary Vessels / Q000503:physiopathology*; D051379:Mice; D055414:Myocardial Perfusion Imaging / Q000379:methods / Q000662:veterinary*; D015203:Reproducibility of Results; D015656:Respiratory Mechanics; D055425:Respiratory-Gated Imaging Techniques / Q000379:methods / Q000662:veterinary*; D012680:Sensitivity and Specificity; D055114:X-Ray Microtomography / Q000379:methods / Q000662:veterinary*