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Proceedings Paper

The impact of skull bone intensity on the quality of compressed CT neuro images
Author(s): Ilona Kowalik-Urbaniak; Edward R. Vrscay; Zhou Wang; Christine Cavaro-Menard; David Koff; Bill Wallace; Boguslaw Obara
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Paper Abstract

The increasing use of technologies such as CT and MRI, along with a continuing improvement in their resolution, has contributed to the explosive growth of digital image data being generated. Medical communities around the world have recognized the need for efficient storage, transmission and display of medical images. For example, the Canadian Association of Radiologists (CAR) has recommended compression ratios for various modalities and anatomical regions to be employed by lossy JPEG and JPEG2000 compression in order to preserve diagnostic quality. Here we investigate the effects of the sharp skull edges present in CT neuro images on JPEG and JPEG2000 lossy compression. We conjecture that this atypical effect is caused by the sharp edges between the skull bone and the background regions as well as between the skull bone and the interior regions. These strong edges create large wavelet coefficients that consume an unnecessarily large number of bits in JPEG2000 compression because of its bitplane coding scheme, and thus result in reduced quality at the interior region, which contains most diagnostic information in the image. To validate the conjecture, we investigate a segmentation based compression algorithm based on simple thresholding and morphological operators. As expected, quality is improved in terms of PSNR as well as the structural similarity (SSIM) image quality measure, and its multiscale (MS-SSIM) and informationweighted (IW-SSIM) versions. This study not only supports our conjecture, but also provides a solution to improve the performance of JPEG and JPEG2000 compression for specific types of CT images.

Paper Details

Date Published: 16 February 2012
PDF: 9 pages
Proc. SPIE 8319, Medical Imaging 2012: Advanced PACS-based Imaging Informatics and Therapeutic Applications, 83190L (16 February 2012); doi: 10.1117/12.912467
Show Author Affiliations
Ilona Kowalik-Urbaniak, Univ. of Waterloo (Canada)
Edward R. Vrscay, Univ. of Waterloo (Canada)
Zhou Wang, Univ. of Waterloo (Canada)
Christine Cavaro-Menard, Univ. de Angers (France)
David Koff, McMaster Univ. (Canada)
Bill Wallace, Agfa Healthcare, Inc. (Canada)
Boguslaw Obara, Univ. of Oxford (United Kingdom)

Published in SPIE Proceedings Vol. 8319:
Medical Imaging 2012: Advanced PACS-based Imaging Informatics and Therapeutic Applications
William W. Boonn; Brent J. Liu, Editor(s)

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