Image Registration Using Free-Form Deformation with A New Joint Histogram Estimation
Shengxian Tu · 2007
Inthispaper,we present a voxel-based non-rigid registration algorithm usingan improved interpolation method basedonPV (partial volume) interpolation toestimate thejoint histogram. Traditionally, thelocal deformation ismodeledbya free-form deformation basedonB-splines, andthecostfunction is theweighted combination ofmutualinformation anda smooth constraint penalty term.Inordertoreduce thelocal extreme, we employan approximate function ofHanningwindowedsincas kernelfunction ofPV interpolation, and usea new method computing thegradient ofmutualinformation withrespect tothe modelparameters efficiently. Theexperiment on CT abdomen images showsthatthealgorithm iseasier toconverge attheglobal optimum andrestrain thelocal extreme. I.INTRODUCTION Non-rigid medical imageregistration includes transform, interpolation, metric andoptimization (1). Someresearchers havealready described non-rigid transform inmedical image usingvarious models. Rueckert etal.employed free-form deformation modelbasedonB-splines todescribe thelocal deformation ofthree-dimensional (3-D) breast MR images (2). Thesmaller thespacing ofmeshcontrol points is, thehigher the degree ofthelocal deformation is.Tustison etal.presented a nonuniform rational B-splines (NURBS)modelfornon-rigid registration (3). A viscous fluid physical modelwasapplied to multimodal medical image registration byAgostino etal.(4). It issuitable forlarge local deformation between thedifferent objects. Maximization ofmutualinformation (MMI)iswidely proposed tomatchmultimodal medical images asa metric (2)(4)(13). Butitisliable tocause local extreme andaffect the registration accuracy asaresult ofinterpolation. Thereisthe analysis aboutthecauseoflocal extremeusingseveral interpolation algorithms indetail in(5). Sosomeresearchers correspondingly improved these algorithms. HuameiChenetal. modified partial volume (PV)interpolation method (5)using B- *Corresponding author. Tel: +86-21-34205821; Fax:+86-21-62823524; Email: