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Biomedical subjects

Michael W Vannier

Publications and source records attributed to Michael W Vannier.

8 recordsLinked to original sources
PubMed2003

Cancer imaging informatics workshop report from the Biomedical Imaging Program of the National Cancer Institute.

A group of experts on very large databases, quantitative imaging, data format standards development, image management and communications, and related technologies for cancer imaging met at a recent workshop sponsored by the BIP and discussed the key issues confronting this field. The BIP received recommendations regarding steps that can be taken to advance the technology and take advantage of the opportunities to improve collaboration and utility in cancer imaging. There are tremendous opportunities to change radically the way we use image information. These opportunities are most obvious in clinical research, in which we seek to advance the dissemination and use of cancer image data in research and practice. Important opportunities and new modes of information use are provided by supporting the entire "information cycle" of creation, dissemination, and collaboration in addition to image organization, access, presentation, and preservation. To learn more, visit the BIP Web site at www3 .cancer.gov/bip/steer_iasc.htm and join the image archive listserver at the NIH (ARCHIVE-COMM-L, available online at list.nihgov). These resources are open and available to all.

Diagnostic Imaging↗
PubMed2003

Blind deblurring of spiral CT images.

To discriminate fine anatomical features in the inner ear, it has been desirable that spiral computed tomography (CT) may perform beyond their current resolution limits with the aid of digital image processing techniques. In this paper, we develop a blind deblurring approach to enhance image resolution retrospectively without complete knowledge of the underlying point spread function (PSF). An oblique CT image can be approximated as the convolution of an isotropic Gaussian PSF and the actual cross section. Practically, the parameter of the PSF is often unavailable. Hence, estimation of the parameter for the underlying PSF is crucially important for blind image deblurring. Based on the iterative deblurring theory, we formulate an edge-to-noise ratio (ENR) to characterize the image quality change due to deblurring. Our blind deblurring algorithm estimates the parameter of the PSF by maximizing the ENR, and deblurs images. In the phantom studies, the blind deblurring algorithm reduces image blurring by about 24%, according to our blurring residual measure. Also, the blind deblurring algorithm works well in patient studies. After fully automatic blind deblurring, the conspicuity of the submillimeter features of the cochlea is substantially improved.

Algorithms↗
PubMed2003

Sharing images.

Explore the source record for details and available documents.

Information Dissemination↗
PubMed2002

Blind deblurring of spiral CT images-comparative studies on edge-to-noise ratios.

A recently developed blind deblurring algorithm based on the edge-to-noise ratio has been applied to improve the quality of spiral CT images. Since the discrepancy measure used to quantify the edge and noise effects is not symmetric, there are several ways to formulate the edge-to-noise ratio. This article is to investigate the performance of those ratios with phantom and patient data. In the phantom study, it is shown that all the ratios share similar properties, validating the blind deblurring algorithm. The image fidelity improvement varies from 29% to 33% for different ratios, according to the root mean square error (RMSE) criterion; the optimal iteration number determined for each ratio varies from 25 to 35. Those ratios that are associated with most satisfactory performance are singled out for the image fidelity improvement of about 33% in the numerical simulation. After automatic blind deblurring with the selected ratios, the spatial resolution of CT is substantially refined in all the cases tested.

Algorithms↗
PubMed2002

The pattern of alveolar crest height change in healthy postmenopausal women after 3 years of hormone/estrogen replacement therapy.

BACKGROUND: The loss of ovarian function at menopause is associated with loss of postcranial and oral bone. Hormone/estrogen replacement therapy (HRT/ERT) has a positive effect on both postcranial and oral bone. The objective of the study was to determine if the positive effect of HRT/ERT on alveolar crest height (ACH) is generalized or site specific. METHODS: The sample consisted of 49 women who completed a 3-year, HRT/ERT prospective study. Cemento-enamel junction distances (ACH) were measured on digitized images of bitewing radiographs. Lumbar spine and proximal femur bone mineral densities (BMDs) were determined with dual-energy x-ray absorptiometric scans. Measurements were made at baseline and at the end of year 3. For the 3-year study period, mean change in ACH was determined for each patient. In addition, the sites with the greatest, second and third greatest ACH changes were determined for each patient. Correlations between changes in ACH (as determined by the various methods) and postcranial BMD were determined. RESULTS: Mean ACH changes had an average correlation (r) of -0.24 with femoral and lumbar spine BMDs. Although the largest site-specific change in ACH resulted in a mean correlation of -0.21, the correlations for the second and third largest changes in ACH dropped to -0.15 and -0.12. Overall, the correlations for site-specific changes were substantively smaller than those for generalized change. CONCLUSIONS: The data of this study indicate that ACH change attributable to HRT/ERT is generalized rather than site specific. Studies of the effect of HRT/ERT on ACH should employ multiple measurements to minimize measurement errors associated with site-specific measurements.

Absorptiometry, Photon↗