In Vivo Evaluation of the Presence of Bone Marrow in Cortical Porosity in Postmenopausal Osteopenic Women

This is the first observational study examining cortical porosity in vivo in postmenopausal osteopenic women and to incorporate data from two different imaging modalities to further examine the nature of cortical porosity. The goal of this study was to combine high-resolution peripheral computed tomography (HR-pQCT) images, which contain high spatial resolution information of the cortical structure, and magnetic resonance (MR) images, which allow the visualization of soft tissues such as bone marrow, to observe the amount of cortical porosity that contains bone marrow in postmenopausal osteopenic women. The radius of 49 and the tibia of 51 postmenopausal osteopenic women (age 56 ± 3.7) were scanned using both HR-pQCT and MR imaging. A normalized mutual information registration algorithm was used to obtain a three-dimensional rigid transform which aligned the MR image to the HR-pQCT image. The aligned images allowed for the visualization of bone marrow in cortical pores. From the HR-pQCT image, the percent cortical porosity, the number of cortical pores, and the size of each cortical pore was determined. By overlaying the aligned MR and HR-pQCT images, the percent of cortical pores containing marrow, the number of cortical pores containing marrow, and the size of each cortical pore containing marrow were measured. While the amount of cortical porosity did not vary greatly between subjects, the type of cortical pore, containing marrow vs. not containing marrow, varied highly between subjects. The results suggest that cortical pore spaces contain components of varying composition, and that there may be more than one mechanism for the development of cortical porosity

Review of \u3ci\u3eOhiyesa: Charles Eastman, Santee Sioux\u3c/i\u3e By Raymond Wilson

Charles Eastman, Ohiyesa, was a Santee Sioux whose life invites curiosity in a different way than for great Native American leaders like Sitting Bull, Chief Joseph, or Crazy Horse. Eastman was one of a very few Native Americans of his time who lived competently in two worlds. Raymond Wilson offers a picture of the whole lifetime in one concise, readable volume, showing Eastman\u27s\u27 life as fraught with difficulties and controversies. The work is based primarily on government documents, correspondence, others\u27 accounts, and Eastman\u27s own books and articles. Eastman\u27s maternal grandfather, Seth Eastman, was a U.S. Army captain who left his native wife and daughter. Because his mother died while Eastman was an infant, his paternal grandmother reared him in the traditional Sioux ways until he was nearly fifteen, when his father, who had adopted Christianity, took him to live in Flandreau. Ohiyesa became Charles Eastman and began the formal education that led through an M.D. at Boston University School of Medicine in 1890. Soon after Eastman began his service as the government physician at the Pine Ridge Reservation, disagreements with the agent marred his dreams of helping his people and he soon left. In 1891 Eastman married Elaine Goodale, a teacher from New England. They moved to St. Paul in 1893 where Eastman began working for the YMCA. Though Eastman appears to have reconciled the differences between his traditional past and Christianity, Wilson contends that his approach was an oversimplification. At this time Eastman also became involved in what would become a complex battle to resolve Santee claims against the federal government. Wilson suggests that Eastman\u27s motives were financial as well as altruistic. In 1900 Eastman served another short, unpleasant term as a government physician, this time· at the Crow Creek Reservation, then moved to the project of renaming the Sioux. According to Wilson, this task satisfied Eastman\u27s superiors but caused him some personal discomfort since the objective was clearly assimilation. Between 1910 and 1921 Eastman wrote and lectured on his own life experiences, on Native American culture, and on Native American relationships with Euroamericans. Although he was an early supporter of the Dawes Act of 1887 he later repudiated it, and generally promoted the idea that Native Americans must accept the ways of the mainstream without the total sacrifice of native beliefs and practices. Eastman once more rejoined government service in 1923, not as a physician but as an Indian inspector, but was again enmeshed in internal conflict. Eastman devoted his final years to research and lecturing, including a speaking tour in England. Because he was estranged from his wife, he often retreated to a lodge that he had built in southern Ontario or lived with his son in Detroit. Charles Eastman/ Ohiyesa died at the age of eighty in 1939

Registration of Musculoskeletal Images for the Analysis of Bone Structure

The accurate and early diagnosis of osteoporosis and the assessment in response to therapy are critical for patient management but still remain a challenge for clinicians. There have been recent advancements in diagnostic imaging techniques to improve the assessment of bone quality. There are several different imaging techniques which can be used for the assessment of bone quality both in vivo and in vitro including multi-detector Quantitative Computed Tomography (QCT), High Resolution peripheral Quantitative Computed Tomography (HR-pQCT), Micro Computed Tomography (μCT), Synchrotron Radiation Micro Computed Tomography(SRμCT), and Magnetic Resonance Imaging (MRI) which each have advantages and limitations. The purpose of this thesis is to develop robust image registration techniques for CT and MR-based musculoskeletal images and determine if there is an improvement in the accuracy of longitudinal studies or an enhancement in the understanding of bone quality by combining images from different imaging techniques.An automatic inter-modal rigid registration method based on normalized mutual information was implemented to allow for the direct spatial comparison of tissue mineralization distributions of ex vivo bone tissue specimens in μCT and SRμCT images. The registration method successfully aligned images acquired using μCT and SRμCT in five specimens of the femoral head, four specimens of the vertebral body, and five specimens of the proximal tibia. This allowed the first direct comparison of tissue mineral density (TMD) between the two modalities.A normalized mutual information registration method was applied to a set of 49 radius images and 51 tibia images of postmenopausal osteopenic women acquired on MRI and HR-pQCT. The registration method successfully registered all images and the robustness of the method was established. The amount of cortical porosity identified in the HR-pQCT images that contained bone marrow as visualized on the MR images was then quantified.Image registration methodologies to align MR images in longitudinal studies were also developed. An automatic registration method based on a mutual information measure was implemented for the alignment of high-resolution MR images of trabecular bone in vivo. The robustness and reproducibly of the registration method was established on MR images of the proximal femur of six normal healthy volunteers. The improvement in measurement accuracy in a longitudinal study was demonstrated on MR images of the proximal femur of twenty-four postmenopausal osteopenic women who were scanned at 0 and 12 months. The automatic registration method was then extended to prospective registration that allowed follow-up images to be acquired in the same orientation as baseline images. The feasibility of prospective registration for MR images of trabecular bone was demonstrated on the distal tibia of five volunteers and the knee of one volunteer. The prospective registration ensured that the same region was analyzed in both the baseline and follow-up images, saved post processing time, preserved the reproducibility of the trabecular bone parameters, and required no interpolation. The results of this project suggest that the adoption of image registration into the analysis of musculoskeletal images of bone improves the accuracy, reproducibility, and precision of longitudinal and comparative studies