title: Prospective-gated cardiac micro-CT imaging of free-breathing mice using carbon nanotube field emission x-ray.
abstract: OBJECTIVE
  Carbon nanotube (CNT) based field emission x-ray source technology has recently been investigated for diagnostic imaging applications because of its attractive characteristics including electronic programmability, fast switching, distributed source, and multiplexing. The purpose of this article is to demonstrate the potential of this technology for high-resolution prospective-gated cardiac micro-CT imaging.
  
  
  METHODS
  A dynamic cone-beam micro-CT scanner was constructed using a rotating gantry, a stationary mouse bed, a flat-panel detector, and a sealed CNT based microfocus x-ray source. The compact single-beam CNT x-ray source was operated at 50 KVp and 2 mA anode current with 100 microm x 100 microm effective focal spot size. Using an intravenously administered iodinated blood-pool contrast agent, prospective cardiac and respiratory-gated micro-CT images of beating mouse hearts were obtained from ten anesthetized free-breathing mice in their natural position. Four-dimensional cardiac images were also obtained by gating the image acquisition to different phases in the cardiac cycle.
  
  
  RESULTS
  High-resolution CT images of beating mouse hearts were obtained at 15 ms temporal resolution and 6.2 lp/mm spatial resolution at 10% of system MTF. The images were reconstructed at 76 microm isotropic voxel size. The data acquisition time for two cardiac phases was 44 +/- 9 min. The CT values observed within the ventricles and the ventricle wall were 455 +/- 49 and 120 +/- 48 HU, respectively. The entrance dose for the acquisition of a single phase of the cardiac cycle was 0.10 Gy.
  
  
  CONCLUSIONS
  A high-resolution dynamic micro-CT scanner was developed from a compact CNT microfocus x-ray source and its feasibility for prospective-gated cardiac micro-CT imaging of free-breathing mice under their natural position was demonstrated.
authors.affiliation: Department of Physics and Astronomy, University of North Carolina, Chapel Hill, North Carolina 27599, USA. gcao@physics.unc.edu
authors.forename: Guohua
authors.initials: G
authors.lastname: Cao
authors.forename: Laurel M
authors.initials: LM
authors.lastname: Burk
authors.forename: Yueh Z
authors.initials: YZ
authors.lastname: Lee
authors.forename: Xiomara
authors.initials: X
authors.lastname: Calderon-Colon
authors.forename: Shabana
authors.initials: S
authors.lastname: Sultana
authors.forename: Jianping
authors.initials: J
authors.lastname: Lu
authors.forename: Otto
authors.initials: O
authors.lastname: Zhou
mesh_terms: D000818:Animals; D055592:Biophysical Phenomena; D055424:Cardiac-Gated Imaging Techniques / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data; D006321:Heart / Q000000981:diagnostic imaging*; D051379:Mice; D008810:Mice, Inbred C57BL; D037742:Nanotubes, Carbon; D011857:Radiographic Image Interpretation, Computer-Assisted; D012143:Respiratory Physiological Phenomena; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data
chemical_list: D037742:Nanotubes, Carbon