title: Markerless motion tracking of awake animals in positron emission tomography.
abstract: Noninvasive functional imaging of awake, unrestrained small animals using motion-compensation removes the need for anesthetics and enables an animal's behavioral response to stimuli or administered drugs to be studied concurrently with imaging. While the feasibility of motion-compensated radiotracer imaging of awake rodents using marker-based optical motion tracking has been shown, markerless motion tracking would avoid the risk of marker detachment, streamline the experimental workflow, and potentially provide more accurate pose estimates over a greater range of motion. We have developed a stereoscopic tracking system which relies on native features on the head to estimate motion. Features are detected and matched across multiple camera views to accumulate a database of head landmarks and pose is estimated based on 3D-2D registration of the landmarks to features in each image. Pose estimates of a taxidermal rat head phantom undergoing realistic rat head motion via robot control had a root mean square error of 0.15 and 1.8 mm using markerless and marker-based motion tracking, respectively. Markerless motion tracking also led to an appreciable reduction in motion artifacts in motion-compensated positron emission tomography imaging of a live, unanesthetized rat. The results suggest that further improvements in live subjects are likely if nonrigid features are discriminated robustly and excluded from the pose estimation process.
authors.forename: Andre
authors.initials: A
authors.lastname: Kyme
authors.forename: Stephen
authors.initials: S
authors.lastname: Se
authors.forename: Steven
authors.initials: S
authors.lastname: Meikle
authors.forename: Georgios
authors.initials: G
authors.lastname: Angelis
authors.forename: Will
authors.initials: W
authors.lastname: Ryder
authors.forename: Kata
authors.initials: K
authors.lastname: Popovic
authors.forename: Dylan
authors.initials: D
authors.lastname: Yatigammana
authors.forename: Roger
authors.initials: R
authors.lastname: Fulton
mesh_terms: D000818:Animals; D019788:Fluorodeoxyglucose F18; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008297:Male; D009068:Movement; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18