Digital Sharing for Medical Images: PACS vs. VNAs
Health care providers are virtually required to have digital infrastructure that includes sharable medical images these days. But if you’re looking to upgrade your system, or you’re implementing your first digital image archive, you have many software products to choose from.
The leading technologies for storing and retrieving medical imaging files are picture archiving and communications systems (PACS) and vendor neutral archives (VNAs). While the two competing formats look similar on first glance, there are notable differences between them. Before we get to the contrasts, though, it’s important to note what PACS and VNAs have in common. Here are a few of the constants across both types of imaging technologies:
- Both PACS and VNAs provide remote access to images. Radiologists can upload images on one terminal, while physicians in a different office can log in to access them. This is the crucial requirement of all digital image-sharing systems.
- Both systems operate with the same file format and transmission protocol: DICOM, which stands for “digital imaging and communications in medicine.” File formats can lead to accessibility problems, as each application is only equipped to handle certain types of files. The universal use of DICOMs between PACS and VNAs seems to suggest that migrating images between the two systems would be seamless. Unfortunately, that’s rarely the case. We’ll get into that a little later.
- Both options may or may not also operate as a platform for non-DICOM images. This is an important question to ask when considering changes to an image-sharing system for medical care. If departments other than radiology are hoping to upload and access images through the same system, it is vital to choose software that can support non-DICOM images.
- Designers of both PACS and VNAs are working to improve mobility and access to images across different types of devices. That’s one of the leading requests by radiologists and other health care providers — physicians want to be able to call up an image, safely and with full HIPAA compliance, on a tablet or even a phone in the examination room with their patients. They also want access at office desktops for consultation and reporting.
Despite these similarities, PACS and VNAs have very different sets of advantages. To complicate matters, many PACS are beginning to provide some of the features that initially launched the popularity of the VNA. Before making a system-wide purchase (or subscription service, which is also available from many vendors), it’s important to consult all stakeholders in your health care system, and to get to know your vendor and their product well.
That said, there are some broad-strokes difference between your average PACS and a typical VNA. We’ll get into those next.
PACS vs. VNAs: Differences Between Medical Image-Sharing Platforms
According to the trade publication Diagnostic Imaging, the VNA tends to focus on archiving and backing up data, while the PACS usually emphasizes workflow and user experience. Of course, these general principles are less significant in today’s market, where there are a wide variety of VNAs and PACS, and their strong points have begun to overlap.
That said, here are some of the differences between PACS and VNAs that users and medical industry analysts have pointed out:
- The PACS is the original technology used to archive and retrieve digital medical images. As such, it’s often the choice of individual radiology departments, which were among the first to adopt digital imaging. VNAs, on the other hand, are more often found in multiple departments.
- PAC systems are more highly proprietary than most VNAs. That is, each individual PACS will require its own user interface and its own log-in information. VNAs were designed to support storage and access across systems and vendors. Of course, new developments in PACS technology renders this difference conditional, but it remains the conventional wisdom among medical technology experts.
- A VNA, by definition, divorces the storage/access functions of a PAC from a particular workstation or data silo. It uses its own application engine, allowing users to access images from multiple sources with the same user interface. That’s what makes VNAs typically better for interoperability between systems compared to a traditional PACS.
While the above list does seem to argue for the dominance of VNAs over PACS, in actual practice, implementation isn’t always the best choice for every provider. It can be expensive and time-consuming to migrate data from an existing PACS to a brand new VNA.
That’s because DICOM files contain both metadata and location pointers. The former attached patient information to the image; the latter helps the system find and pull up the specific image the user searches for.
During transition, all of this supplemental information can become scrambled, preventing access to images. In order to avoid this outcome, vendors often must reset DICOM headers and location pointers to ensure accuracy and access in the new system. That can be a lengthy and cost-intensive process.
Ultimately, then, institutions with the time and the money will benefit from an upgraded VNA system. More practically, some users will choose a PACS, with or without newly developed features. Regardless of the archiving and retrieval system, digital transmission for diagnostic images is practically a requirement in today’s medical system. Choose an imaging software product that makes it easy to share images with other departments and institutions.
Jackson, Whitney. “What You Need to Know About VACS and VNA.” DiagnosticImaging.” UBM, 4 Sept. 2014. Web. 15 Oct. 2018.
O’Dowd, Elizabeth. “Pros and Cons of PACS, VNAs for Medical Image Data Storage.” HitInfrastructure. Xtelligent Healthcare Media, LLC, n.d. Web. 15 Oct. 2018.