title: Improving In Vivo High-Resolution CT Imaging of the Tumour Vasculature in Xenograft Mouse Models through Reduction of Motion and Bone-Streak Artefacts.
abstract: BACKGROUND
  Preclinical in vivo CT is commonly used to visualise vessels at a macroscopic scale. However, it is prone to many artefacts which can degrade the quality of CT images significantly. Although some artefacts can be partially corrected for during image processing, they are best avoided during acquisition. Here, a novel imaging cradle and tumour holder was designed to maximise CT resolution. This approach was used to improve preclinical in vivo imaging of the tumour vasculature.
  
  
  METHODS
  A custom built cradle containing a tumour holder was developed and fix-mounted to the CT system gantry to avoid artefacts arising from scanner vibrations and out-of-field sample positioning. The tumour holder separated the tumour from bones along the axis of rotation of the CT scanner to avoid bone-streaking. It also kept the tumour stationary and insensitive to respiratory motion. System performance was evaluated in terms of tumour immobilisation and reduction of motion and bone artefacts. Pre- and post-contrast CT followed by sequential DCE-MRI of the tumour vasculature in xenograft transplanted mice was performed to confirm vessel patency and demonstrate the multimodal capacity of the new cradle. Vessel characteristics such as diameter, and branching were quantified.
  
  
  RESULTS
  Image artefacts originating from bones and out-of-field sample positioning were avoided whilst those resulting from motions were reduced significantly, thereby maximising the resolution that can be achieved with CT imaging in vivo. Tumour vessels ≥ 77 μm could be resolved and blood flow to the tumour remained functional. The diameter of each tumour vessel was determined and plotted as histograms and vessel branching maps were created. Multimodal imaging using this cradle assembly was preserved and demonstrated.
  
  
  CONCLUSIONS
  The presented imaging workflow minimised image artefacts arising from scanner induced vibrations, respiratory motion and radiopaque structures and enabled in vivo CT imaging and quantitative analysis of the tumour vasculature at higher resolution than was possible before. Moreover, it can be applied in a multimodal setting, therefore combining anatomical and dynamic information.
authors.affiliation: Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, United Kingdom.
authors.forename: Veerle
authors.initials: V
authors.lastname: Kersemans
authors.affiliation: Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, United Kingdom.
authors.forename: Pavitra
authors.initials: P
authors.lastname: Kannan
authors.affiliation: Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, United Kingdom.
authors.forename: John S
authors.initials: JS
authors.lastname: Beech
authors.affiliation: The Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, United Kingdom.
authors.forename: Russell
authors.initials: R
authors.lastname: Bates
authors.affiliation: The Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, United Kingdom.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Irving
authors.affiliation: Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, United Kingdom.
authors.forename: Stuart
authors.initials: S
authors.lastname: Gilchrist
authors.affiliation: Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, United Kingdom.
authors.forename: Philip D
authors.initials: PD
authors.lastname: Allen
authors.affiliation: Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, United Kingdom.
authors.forename: James
authors.initials: J
authors.lastname: Thompson
authors.affiliation: Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, United Kingdom.
authors.forename: Paul
authors.initials: P
authors.lastname: Kinchesh
authors.affiliation: Laboratory for Applied Veterinary Morphology, Department of Veterinary Sciences, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Wilrijk, Belgium.
authors.forename: Christophe
authors.initials: C
authors.lastname: Casteleyn
authors.affiliation: The Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, United Kingdom.
authors.forename: Julia
authors.initials: J
authors.lastname: Schnabel
authors.affiliation: Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, United Kingdom.
authors.forename: Mike
authors.initials: M
authors.lastname: Partridge
authors.affiliation: Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, United Kingdom.
authors.forename: Ruth J
authors.initials: RJ
authors.lastname: Muschel
authors.affiliation: Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, United Kingdom.
authors.forename: Sean C
authors.initials: SC
authors.lastname: Smart
mesh_terms: D000230:Adenocarcinoma / Q000098:blood supply / Q000000981:diagnostic imaging / Q000473:pathology; D000818:Animals; D016477:Artifacts; D004195:Disease Models, Animal; D005260:Female; D005471:Fluoroscopy; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D051379:Mice; D008808:Mice, Inbred CBA; D009369:Neoplasms / Q000098:blood supply / Q000000981:diagnostic imaging* / Q000473:pathology; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*; D014183:Transplantation, Heterologous