Healthcare Imaging & IT - July 2008 - (Page 38)

TeChnology ouTlook By Sarah Lamberti pressed studies at different ratios and DeLago, in a blinded evaluation, determined that using a compression ratio of 15:1 still preserved image quality and for whole-body studies, 14:1 preserved diagnostic quality. “Obviously, when we are looking at vessel size in 2.5 millimeters and down, the compression got out of whack when it got over 15 or 20, but below that, I could not tell the difference in image quality,” DeLago says. Normally, remote facilities use a low-bandwidth link and data are acquired and stored in the central repository at the hospital. If a remote While the demand for immediate transmission of digital images is high, physician wants to download a study, it takes a and radiologic image compression offers a reduction in data volume, while over low-bandwidth links. For modern the debate continues as to whether there is degradation in diagnostic CT studies, this could take 10 minutes. “From image quality. With storage prices dropping, many still question an economical perspective, that is just a waste of time. We wanted to create whether image compression is even necessary. a way to compress data on the fly, send it in a compressed way to radiology, but since that If we go back to basics: Image compression and then decompressed at the high level of bandwidth is not can be divided into two categories: lossless remote workstation, in a seamavailable everywhere in the and lossy. Lossless compression uses redunless manner,” says Vadim hospital, “everyone is utilizing dancy within an image to decrease the medSheinin, manager of multimelossy compression either by ical image size by 2:1 to 4:1. Lossy, or irredia technologies, IBM Research, creating a compressed copy and versible, techniques can reduce images by a who participated in the project. then later sending a lossy comfar greater ratio and while it does not perHowever, Siegel says that “this pressed image or by doing this on fectly reproduce the original image, the relatively steep level of comdemand for studies that are reproduction may be sufficient for diagnospression is greater than the being served up outside and, in tic purposes, with no visible degradation or 8:1 that is usually cited in the some cases, inside the radiolloss in diagnostic value. imaging literature for CT.” ogy department,” Siegel adds. Why is image compression still a hot topIt may be acceptable for Teleradiology groups experiic? According to Eliot Siegel, MD, professor images displayed in cine or ence longer download times due and vice chair of information systems, Unimovie mode since the eye and to the lack of availability of bandversity of Maryland Department of Diagbrain integrate noise out of width, which tends to be signifinostic Radiology, and director of imaging at [ Top: Original image captured moving images, but image cantly less than is available VA Maryland Healthcare Systems, there is from cardiac CT study. Bottom: Same cardiac CT study image quality is likely to suffer when within hospitals, he says. “an increasing mismatch between our cliniafter being compressed and As a way to combat the issue decompressed at compresssion of reviewing a single image. cal image production and our storage and 14.5:1. Images courtesy of IBM. ] “Our research suggests that of transmission to remote locanetwork capacity and bandwidth.” the proposed JPEG 2000 3D compression tions, Augustin DeLago, MD, FACC, FSCAI, The critical issue is not the cost of storage standard works in an analogous way to the director of the cath lab at Albany Medical of data. “It is about the time required to video compression standard and makes up Center in New York, who, in collaboration move data from one location to another,” he for the noisier images associated with very with IBM, started work on a project to apply says. Most vendors today are storing the thin slices. However, 8:1 still seems to be the digital video compression on CT studies. images using only lossless compression. upper limit for compression of these noisier DeLago, along with a team from IBM, Lossy compression is typically used for thin slices even using 3D compression.” examined cardiac CT studies using a H264 enterprise web distribution systems while It is clear that further investigation and video compression algorithm to view them lossless compression is more often used for product development is needed so that the as video clips because “CT cuts the body primary review by the radiologists. entire digital radiology community can very thinly so the correlation between the Most PACS vendors rely on ultrafast gigareap the benefits. successive slice is very high.” IBM sent combit Ethernet connections to muscle images Compressing Images for Remote Transmission 38 Health Imaging & IT | July 2008 HealthImaging.com http://HealthImaging.com

Table of Contents Feed for the Digital Edition of Healthcare Imaging & IT - July 2008

Healthcare Imaging & IT - July 2008 On the Web The Enterprise News Update Convention Spotlight: AHRA 2008 Cover Story: Driving Metrics to Drive Business: Digital Dashboards Deliver Mammography CAD Comes of Age Breast MR CAD: Earlier Detection, Increased Efficiency Lung CAD Earning a Spot in Day-to-Day Practice Colon CAD: Breaking Down Barriers Modality Review: Cardiac CT Angiography: A Clear Pathway to Better Cardiac Patient Management Practice Management: RIS Rights Efficiency & Productivity Wrongs In Practice: Advanced Visualization Across the Enterprise Regulatory Update: Beware: Recovery Audit Contractors Poised for Permanent Status Technology Outlook: Compressing Images for Remote Transmission Reader's Resource Stat Sheet

Healthcare Imaging & IT - July 2008

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