title: Registration of a statistical shape model of the lumbar spine to 3D ultrasound images.
abstract: BACKGROUND
  Spinal needle injections are technically demanding procedures. The use of ultrasound image guidance without prior CT and MR imagery promises to improve the efficacy and safety of these procedures in an affordable manner.
  
  
  METHODS
  We propose to create a statistical shape model of the lumbar spine and warp this atlas to patient-specific ultrasound images during the needle placement procedure. From CT image volumes of 35 patients, statistical shape model of the L3 vertebra is built, including mean shape and main modes of variation. This shape model is registered to the ultrasound data by simultaneously optimizing the parameters of the model and its relative pose. Ground-truth data was established by printing 3D anatomical models of 3 patients using a rapid prototyping. CT and ultrasound data of these models were registered using fiducial markers.
  
  
  RESULTS
  Pairwise registration of the statistical shape model and 3D ultrasound images led to a mean target registration error of 3.4 mm, while 81% of all cases yielded clinically acceptable accuracy below the 3.5 mm threshold.
authors.affiliation: Queen's University, Kingston, ON, Canada.
authors.forename: Siavash
authors.initials: S
authors.lastname: Khallaghi
authors.forename: Parvin
authors.initials: P
authors.lastname: Mousavi
authors.forename: Ren Hui
authors.initials: RH
authors.lastname: Gong
authors.forename: Sean
authors.initials: S
authors.lastname: Gill
authors.forename: Jonathan
authors.initials: J
authors.lastname: Boisvert
authors.forename: Gabor
authors.initials: G
authors.lastname: Fichtinger
authors.forename: David
authors.initials: D
authors.lastname: Pichora
authors.forename: Dan
authors.initials: D
authors.lastname: Borschneck
authors.forename: Purang
authors.initials: P
authors.lastname: Abolmaesumi
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging*; D008954:Models, Biological; D015233:Models, Statistical; D010363:Pattern Recognition, Automated / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique; D014463:Ultrasonography / Q000379:methods*