title: Self-calibrating 3D-ultrasound-based bone registration for minimally invasive orthopedic surgery.
abstract: Intraoperative freehand three-dimensional (3-D) ultrasound (3D-US) has been proposed as a noninvasive method for registering bones to a preoperative computed tomography image or computer-generated bone model during computer-aided orthopedic surgery (CAOS). In this technique, an US probe is tracked by a 3-D position sensor and acts as a percutaneous device for localizing the bone surface. However, variations in the acoustic properties of soft tissue, such as the average speed of sound, can introduce significant errors in the bone depth estimated from US images, which limits registration accuracy. We describe a new self-calibrating approach to US-based bone registration that addresses this problem, and demonstrate its application within a standard registration scheme. Using realistic US image data acquired from 6 femurs and 3 pelves of intact human cadavers, and accurate Gold Standard registration transformations calculated using bone-implanted fiducial markers, we show that self-calibrating registration is significantly more accurate than a standard method, yielding an average root mean squared target registration error of 1.6 mm. We conclude that self-calibrating registration results in significant improvements in registration accuracy for CAOS applications over conventional approaches where calibration parameters of the 3D-US system remain fixed to values determined using a preoperative phantom-based calibration.
authors.affiliation: Department of Imaging Sciences, Guy's Hospital, GKT School of Medicine, King's College London, UK. d.barratt@ucl.ac.uk
authors.forename: Dean C
authors.initials: DC
authors.lastname: Barratt
authors.forename: Graeme P
authors.initials: GP
authors.lastname: Penney
authors.forename: Carolyn S K
authors.initials: CS
authors.lastname: Chan
authors.forename: Mike
authors.initials: M
authors.lastname: Slomczykowski
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Carter
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Edwards
authors.forename: David J
authors.initials: DJ
authors.lastname: Hawkes
mesh_terms: D000465:Algorithms; D001185:Artificial Intelligence; D002102:Cadaver; D002138:Calibration; D005269:Femur / Q000000981:diagnostic imaging / Q000601:surgery; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D019060:Minimally Invasive Surgical Procedures / Q000379:methods; D019637:Orthopedic Procedures / Q000379:methods*; D010363:Pattern Recognition, Automated / Q000379:methods*; D010384:Pelvic Bones / Q000000981:diagnostic imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique; D025321:Surgery, Computer-Assisted / Q000379:methods*; D014463:Ultrasonography / Q000379:methods* / Q000592:standards