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Increased use of diagnostic tests needs imaging data storage plans

Clinicians are ordering more diagnostic tests than ever before. Hospitals need to store all that imaging data somewhere, often for 10 years or more.

Diagnostic imaging -- such as X-rays, magnetic resonance imaging (MRI) and computed tomography (CT) -- are commonly ordered by healthcare providers, and their effective usage is critical to the delivery of modern healthcare, but the rapid increase in use over the last decade is leading to obstacles in storage technology and policy around access.

This article highlights just a few of the key issues that healthcare organizations must address as they continue the adoption and use of digital imaging technologies. New diagnostic imaging technology holds exciting potential. This potential may, at times, be constrained by an institution's storage capacity and network infrastructure to support the number and size of imaging data files generated by advanced technologies.

According to estimates from the Canadian Institute for Health Information, Canadians underwent 1.7 million MRI exams and 4.4 million CT exams in 2012. These numbers represent almost double the number of such exams compared to 2003. In Canada in 2011-2012, the national rate for MRI exams was 49 per 1,000 people, and 126 per 1,000 people for CT scans.

Canada is certainly not the only country to experience these trends; similar trends exist in the United States and elsewhere. As stated in a report by the Journal of the American Medical Association, a review of electronic records from six large integrated health systems from different regions of the United States revealed that:

  • Enrollees underwent an average of 1.18 imaging tests per year
  • 35% of tests were considered to be advanced imaging (for example, CT, MRI, nuclear medicine and ultrasound)
  • Radiography increased 1.2% per year, but angiography/fluoroscopy decreased 1.3 percent per year
  • CT examinations nearly tripled from 52/1,000 enrollees in 1996 to 149/1,000 in 2010
  • MRIs quadrupled (17/1,000 to 65/1,000, 10% annual growth)
  • Ultrasounds approximately doubled over the same period (134/1,000 to 230/1,000, 3.9% annual growth)

Aside from the valid clinical question of whether all these tests are medically necessary, there are technical challenges associated with the acquisition, transfer, storage and retrieval of the large imaging data generated from imaging procedures.

Volume of imaging data

One obvious issue with the number of imaging tests being performed is related to the storage and management of the digital data associated with these images and their corresponding reports. A Frost & Sullivan estimate states that "even if diagnostic imaging volumes continue to plateau around the 600 million procedures per year mark, overall storage and archiving volume requirements for U.S. medical imaging data will cross the 1 exabyte mark by 2016." For reference, 1 exabyte is 1,000 petabytes or 1,000,000 terabytes, which "marks medical imaging's definitive entry into Big Data territory" according to the report.

Storage of imaging data

Of course, this data needs to be stored, and there are many different types of storage to accommodate imaging data, ranging from tape to solid-state storage to the "cloud," depending on the needs of the organization and the stage of the patient's healthcare journey the image or data represents. An e-book on imaging storage and management from the Society for Imaging Informatics in Medicine (SIIM) suggests that data from images "tends to move between categories of 'in use,' 'needed shortly' or 'archive purposes only,' based upon clinical events."

The SIIM article also suggests that images are most clinically useful around the time of diagnosis and treatment and typically spans a period of days to several weeks. Once an image is archived, however, "after a period of six months to two years, there is less than a 5% chance that an image will ever be requested from the archive." Consider, however, that for legal purposes, most developed countries require that these images be stored for five to 10 years.

The two main options for storage of diagnostic imaging data are local storage and cloud storage. A SearchHealthIT article identifies seven key factors to examine when considering storage alternatives, including:

  • Price -- what storage options (including costs of ongoing support and maintenance) exist within the organization's price range. According to the Canadian Association of Radiologists, "while the cost of storage is falling, the savings are largely surpassed by the increasing volume of data being generated. In addition, the cost of operating a digital environment with high performance and resiliency is rising and is exacerbated by factors such as mandatory data migration and long or indefinite retention periods for digital images."
  • Capacity -- This relates to how much storage capacity your organization requires; what risks are associated with not having enough storage or with having and paying for too much excess storage.
  • Compliance -- how your organization can best assure and maintain compliance with HIPAA regulations.

Network infrastructure

The use of and storage requirements for digital imaging modalities in healthcare require a network infrastructure to support the storage and retrieval of large data files in a timely manner that does not interrupt the workflow of the technologists or clinicians accessing the files.

PACS and other imaging technology

Meaningful use making new use of PACS

Five easy steps to achieve PACS integration

Clinical decision support tech driving radiology

For localized access and use, the network bandwidth within an institution is typically sufficient for the required timely access to imaging data. Because of the "hub-and-spoke" design of many radiology information system and picture archiving and communication system architectures, however, and the growing use of the cloud for storage, most image files are not stored on a local computer for any significant amount of time, if any. Because of this emerging architecture, most radiological services require "the transfer of large electronic images to and from remote locations."

Healthcare organizations must address not only current network requirements, but likely future requirements as well. For example, a Health Management Technology article states that "Today's 16-slice CAT scan can generate a 2,000-image, 2-gigabit file and tomorrow's will only grow. Network speed and bandwidth are critical to real-time transfer and analysis in the medical field and the cabling needs to be ready to support it."

Healthcare providers continue to adopt mobile technology at a rapid pace. The ability of mobile devices to function in a clinical environment, however, may be limited by their ability to receive and display large imaging files (which is, primarily, a function of the bandwidth available). Although the potential for the use of mobile devices in healthcare is truly exciting, recent studies demonstrate that mobile bandwidth can still be a limiting factor in the use of smartphones and tablets for image viewing.

About the author:
Trevor Strome, M.S., PMP, leads the development of informatics and analytics tools that enable evidence-informed decision making by clinicians and healthcare leaders. His experience spans public, private and startup-phase organizations. A popular speaker, author and blogger, Strome is the founder of, and his book, Healthcare Analytics for Quality and Performance Improvement, was recently published by John Wiley & Sons Inc.

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