The modern picture archiving and communication system (PACS) has done an amazing job of organizing a massive amount of digital information. However, PACS manufacturers focused so much energy on archiving and communicating that the mechanics of moving that data often fell by the wayside.
Is it the law of unintended consequences, or a way for some vendors to encourage brand loyalty? Whatever the case, the cost of data migration amounts to another outlay of money during a time when dollars are already flowing out the door. “When you go from old PACS to new PACS, even if you stay with the same vendor, you must pay to migrate that data,” says Michael Gray, principal, Gray Consulting. “It’s time- consuming, complicated, and expensive, because PACS vendors went out of their way to interpret the DICOM standard to their benefit. There are proprietary aspects to how they have created the DICOM header.”
Despite the DICOM conformity, many PACS are differentiated from one another by pesky idiosyncrasies. Avoiding the costs associated with these differences is the ultimate goal of the much-talked-about vendor neutral archive (VNA).
Hospitals are increasingly willing to pay for VNAs to prevent multiple headaches down the road, Gray says. “At the core of the VNA is the promise that if you pay to move all of your data one more time, from all of your PACS systems, and turn it into a neutral format—you will never have to pay this ugly migration fee again,” he notes. “When you change PACS downstream, the VNA will adapt the data on the fly to the new PACS. You’ll have to move some percentage of the data into the new PACS, but it’s not close to the complications and cost of a DICOM migration from an old PACS to a new PACS.”
The first leg of the VNA strategy typically involves consolidating all storage for the image data into a single archive. In the process of migrating the data to the VNA, it is neutralized and standardized—all of it. “There is a huge cost avoidance downstream once you do this,” Gray says. “You don’t ever again have to pay to migrate the data. Then there is the issue of cross-PACS compatibility. If you had only one PACS system, header idiosyncrasies wouldn’t be a problem, but when you end up with three, and they are generally from different vendors, or sometimes even from the same vendor, they don’t talk very well with each other because they can’t, because of those proprietary aspects to the headers.”
DICOM standards are almost enough to do the heavy lifting of standardization, but not quite. In addition to the header tags that identify the study itself, another bit of information labels that type of study, and may be inconsistent from system to system: for example, Gray says, a CT from one manufacturer might be labeled “CT Head,” while another opts for “Head CT.”
When two entities attempt to share the image, problems can emerge. “When you send that study from the ABC Corp PACS into the XYZ Corp PACS, it isn’t going to recognize what it is, so it can’t possibly look for it and find it and know how to put the study in a hanging protocol,” Gray says. “The system won’t recognize it. It can’t put it side by side with the other study because it doesn’t know what it is.”
A VNA facilitates the exchange of data between these disparate PACS, converting “Head CT” to “CT Head” on the fly. “If a cardiologist sitting at a cardiology PACS wanted to look at a relevant prior study that happened to be a radiology study, in general he cannot do that,” Gray explains. “The systems cannot speak to each other. A VNA managing all of the data from all of the different departments’ systems can bring relevant information from other departments—so they can use it in the interpretation of studies.”
For those who spend the time and money to consolidate images in the VNA to eliminate migrations and facilitate image exchange, the fourth task is to interface to one system for the purpose of viewing all images. “One way to accomplish this is putting a viewer on top of the VNA,” Gray says. “I call it a uni-viewer, short for universal viewer. The uni-viewer is an independent viewing system that accesses data from the VNA and delivers it to physicians who are using the physician portal of the electronic medical record (EMR). I look at reports and I click on a link that goes to the single uni-viewer, and the uni-viewer goes and gets the images from whatever record it has—from cardiology, radiology, or elsewhere—and all that stuff can