DOI
10.17077/etd.pl67d1u7
Document Type
Thesis
Date of Degree
Spring 2018
Degree Name
MS (Master of Science)
Degree In
Electrical and Computer Engineering
First Advisor
Punam K. Saha
First Committee Member
Nicole M. Grosland
Second Committee Member
Reinhard R. Beichel
Third Committee Member
Xiaodong Wu
Abstract
Osteoporosis, associated with reduced bone mineral density and structural degeneration, greatly increases the risk of fragility fracture. Magnetic resonance imaging (MRI) has been applied to central skeletal sites including the proximal femur due to its non-ionizing radiation. A major challenge of volumetric bone imaging of the hip is the selection of regions of interest (ROIs) for computation of regional bone measurements. To address this issue, an MRI-based active shape model (ASM) of the human proximal femur is applied to automatically generate ROIs. The challenge in developing the ASM for a complex three-dimensional (3-D) shape lies in determining a large number of anatomically consistent landmarks for a set of training shapes. This thesis proposes a new method of generating the proximal femur ASM, where two types of landmarks, namely fiducial and secondary landmarks, are used. The method consists of—(1) segmentation of the proximal femur bone volume, (2) smoothing the bone surface, (3) drawing fiducial landmark lines on training shapes, (4) drawing secondary landmarks on a reference shape, (5) landmark mesh generation on the reference shape using both fiducial and secondary landmarks, (6) generation of secondary landmarks on other training shapes using the correspondence of fiducial landmarks and an elastic deformation of the landmark mesh, (7) computation of the active shape model. A proximal femur ASM has been developed using hip MR scans of 45 post-menopausal women. The results of secondary landmark generation were visually satisfactory, and no topology violation or notable geometric distortion artifacts were observed. Performance of the method was examined in terms of shape representation errors in a leave-one-out test. The mean and standard deviation of leave-one-out shape representation errors were 0.34mm and 0.09mm respectively. The experimental results suggest that the framework of fiducial and secondary landmarks allows reliable computation of statistical shape models for complex 3-D anatomic structures.
Keywords
active shape model, elastic deformation, femur, landmarks, morphological smoothing, MRI
Pages
vii, 37 pages
Bibliography
Includes bibliographical references (pages 30-37).
Copyright
Copyright © 2018 Xiaoliu Zhang
Recommended Citation
Zhang, Xiaoliu. "MRI-based active shape model of the human proximal femur using fiducial and secondary landmarks and its validation." MS (Master of Science) thesis, University of Iowa, 2018.
https://doi.org/10.17077/etd.pl67d1u7