title: In vitro evaluation of three-dimensional ultrasonography based on magnetic scanhead tracking.
abstract: The objective of this study was to evaluate the accuracy and precision of a magnetic position sensor system for acquisition of three-dimensional (3D) ultrasound images in volume estimation of phantoms in vitro. Installation of either 0.9% solution of saline at 37 degrees C or distilled water at 20 degrees C to a condom was performed. Scanning was performed either by a continuous or stepwise acquisition. This 3D ultrasound system demonstrated good correlation (r = 0.99-1.0, n = 8) between estimated (EV) and true volumes (TV). The errors were in the range 1.3%+/-0.3% (SEM) to 1.9%+/-0.6%, independent of sound velocity. Scanning through a porcine abdominal wall positioned at the fluid surface yielded a systematic underestimation of the volume: mean (EV - TV) = -7.2+/-0.8 ml. Eight repeated scans of the same volume yielded a coefficient of variation of 1.1%. Interobserver error of the tracing procedure was 2.6%+/-0.9%. This 3D ultrasound system gave high accuracy and precision in volume estimation in vitro, and yielded low interobserver error. A change in ultrasound velocity of approximately 60 m/s did not influence the accuracy significantly. Scanning through an abdominal wall underestimated volumes slightly.
authors.affiliation: Medical Department A, Haukeland University Hospital, University of Bergen, Norway. Odd.Gilja@meda.uib.no
authors.forename: O H
authors.initials: OH
authors.lastname: Gilja
authors.forename: T
authors.initials: T
authors.lastname: Hausken
authors.forename: S
authors.initials: S
authors.lastname: Olafsson
authors.forename: K
authors.initials: K
authors.lastname: Matre
authors.forename: S
authors.initials: S
authors.lastname: Odegaard
mesh_terms: D000005:Abdomen / Q000000981:diagnostic imaging*; D000818:Animals; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation*; D008280:Magnetics; D015588:Observer Variation; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D013552:Swine; D014463:Ultrasonography