PET-CT image registration in the chest using free-form deformations.
We have implemented and validated an algorithm for three-dimensional positron emission tomography transmission-to-computed tomography registration in the chest, using mutual information as a similarity criterion. Inherent differences in the two imaging protocols produce significant nonrigid motion between the two acquisitions. A rigid body deformation combined with localized cubic B-splines is used to capture this motion. The deformation is defined on a regular grid and is parameterized by potentially several thousand coefficients. Together with a spline-based continuous representation of images and Parzen histogram estimates, our deformation model allows closed-form expressions for the criterion and its gradient. A limited-memory quasi-Newton optimization algorithm is used in a hierarchical multiresolution framework to automatically align the images. To characterize the performance of the method, 27 scans from patients involved in routine lung cancer staging were used in a validation study. The registrations were assessed visually by two expert observers in specific anatomic locations using a split window validation technique. The visually reported errors are in the 0- to 6-mm range and the average computation time is 100 min on a moderate-performance workstation.
Mattes
David
D
The Boeing Company, Phantom Works, M&CT, Advanced Systems Laboratory, PO Box 3707, MC 7L-40, Seattle, WA 98124-2207, USA. david.mattes@boeing.com
Haynor
David R
DR
Vesselle
Hubert
H
Lewellen
Thomas K
TK
Eubank
William
W
D000465:Algorithms; D016477:Artifacts; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging; D009038:Motion; D013902:Radiography, Thoracic / Q000379:methods*; D019275:Radiopharmaceuticals; D013382:Subtraction Technique; D013909:Thorax / Q000000981:diagnostic imaging*; D014055:Tomography, Emission-Computed / Q000379:methods*
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18