title: A nonrigid registration of MR breast images using complex-valued wavelet transform.
abstract: In this paper, a fast, slice-by-slice, nonrigid registration algorithm of dynamic magnetic resonance breast images is presented. The method is based on a multiresolution motion estimation of the breast using complex discrete wavelet transform (CDWT): the pyramid of oriented complex subimages is used to implement a hierarchical phase-matching-based motion estimation algorithm. The resulting motion estimate is nonrigid and pixel-independent. To assess the method performance, we computed the correlation coefficient and the normalized mutual information between pre- and postcontrast images with and without realignment. The indices increased after using our approach and the improvement was superior to rigid or affine registration. A set of clinical scores was also evaluated. The clinical validation demonstrated an increased readability in the subtraction images. In particular, CDWT registration allowed a best definition of breast and lesion borders and greater detail detectability.
authors.affiliation: Department of Biomedical Engineering, Polytechnic University of Milan, Piazza Leonardo da Vinci 32, 20133, Milan, Italy. luca.mainardi@biomed.polimi.it
authors.forename: L
authors.initials: L
authors.lastname: Mainardi
authors.forename: K M
authors.initials: KM
authors.lastname: Passera
authors.forename: A
authors.initials: A
authors.lastname: Lucesoli
authors.forename: D
authors.initials: D
authors.lastname: Vergnaghi
authors.forename: G
authors.initials: G
authors.lastname: Trecate
authors.forename: E
authors.initials: E
authors.lastname: Setti
authors.forename: R
authors.initials: R
authors.lastname: Musumeci
authors.forename: S
authors.initials: S
authors.lastname: Cerutti
mesh_terms: D000465:Algorithms; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging; D003287:Contrast Media; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D011859:Radiography
chemical_list: D003287:Contrast Media