title: Deformable and rigid registration of MRI and microPET images for photodynamic therapy of cancer in mice.
abstract: We are investigating imaging techniques to study the tumor response to photodynamic therapy (PDT). Positron emission tomography (PET) can provide physiological and functional information. High-resolution magnetic resonance imaging (MRI) can provide anatomical and morphological changes. Image registration can combine MRI and PET images for improved tumor monitoring. In this study, we acquired high-resolution MRI and microPET 18F-fluorodeoxyglucose (FDG) images from C3H mice with RIF-1 tumors that were treated with Pc 4-based PDT. We developed two registration methods for this application. For registration of the whole mouse body, we used an automatic three-dimensional, normalized mutual information algorithm. For tumor registration, we developed a finite element model (FEM)-based deformable registration scheme. To assess the quality of whole body registration, we performed slice-by-slice review of both image volumes; manually segmented feature organs, such as the left and right kidneys and the bladder, in each slice; and computed the distance between corresponding centroids. Over 40 volume registration experiments were performed with MRI and microPET images. The distance between corresponding centroids of organs was 1.5 +/- 0.4 mm which is about 2 pixels of microPET images. The mean volume overlap ratios for tumors were 94.7% and 86.3% for the deformable and rigid registration methods, respectively. Registration of high-resolution MRI and microPET images combines anatomical and functional information of the tumors and provides a useful tool for evaluating photodynamic therapy.
authors.affiliation: Department of Radiology, Case Western Reserve University and University Hospitals of Cleveland, Cleveland, Ohio 44106, USA. baowei.fei@case.edu
authors.forename: Baowei
authors.initials: B
authors.lastname: Fei
authors.forename: Hesheng
authors.initials: H
authors.lastname: Wang
authors.forename: Raymond F
authors.initials: RF
authors.lastname: Muzic
authors.forename: Chris
authors.initials: C
authors.lastname: Flask
authors.forename: David L
authors.initials: DL
authors.lastname: Wilson
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Duerk
authors.forename: Denise K
authors.initials: DK
authors.lastname: Feyes
authors.forename: Nancy L
authors.initials: NL
authors.lastname: Oleinick
mesh_terms: D000818:Animals; D001331:Automation; D004195:Disease Models, Animal; D019788:Fluorodeoxyglucose F18; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional; D007668:Kidney / Q000000981:diagnostic imaging / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D051379:Mice; D009369:Neoplasms / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000473:pathology; D010778:Photochemotherapy / Q000379:methods*; D049268:Positron-Emission Tomography / Q000379:methods*; D011859:Radiography; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013997:Time Factors; D001743:Urinary Bladder / Q000000981:diagnostic imaging / Q000473:pathology; D014915:Whole-Body Counting / Q000662:veterinary
chemical_list: D019788:Fluorodeoxyglucose F18