ORLANDO, FL - Given their relatively low usage rate by in-house staff, imported images from external institutions shouldn't be stored permanently within an enterprise PACS archive, according to research presented on Thursday at the Society for Imaging Informatics in Medicine (SIIM) annual meeting.
In a retrospective study that examined utilization patterns of external images imported to PACS, researchers from the University of Utah found that nearly half of the outside exams were not viewed at all. In addition, those studies that were viewed were accessed nearly always within the first month.
As such, the institution now only stores external images for 18 months, said Logan Baker, operations manager for radiology IT.
The University of Utah Health Sciences Center encompasses 120 specialties and performs more than 250,000 radiology studies per year. By the end of 2012, the institution is on pace to store more than 50,000 external exams permanently in its PACS database as comparison studies. Because the university uses a fee-per-use PACS storage model, external exams affect the institution's bottom line, Baker said.
The center has an imaging referral area that extends about 325 miles outside of Salt Lake City, covering 300,000 square miles that consist of 10% of the continental U.S. Until recently, external studies were imported and permanently stored on the institution's enterprise PACS.
The volume of these studies has been increasing, with approximately 4,000 images per month currently being stored in the PACS database. This growth can be attributed to a number of factors, including an increase in the number of imaging collaborators, Baker said.
In 2009, 10 hospitals in two states were connected to the institution via virtual private network (VPN) connections. By 2012, 125 hospitals in 22 states are now connected, Baker said.
With the growing impact of external imaging studies, the researchers sought to test the hypothesis that imaging studies imported from outside facilities are underutilized and should not be stored permanently within the PACS environment.
They retrospectively examined usage by clinical staff of externally performed studies in a random sampling of cases over an 18-month period.
Utilization of external studies imported into PACS
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Of the studies viewed, nearly all were viewed within 20 to 30 days of arriving in the PACS database.
"Permanent storage seemed like a bit of overkill when it comes to external comparison [studies]," he said.
Based on the study results, the institution shifted from permanent storage to 18-month temporary storage for external studies. After 18 months, these exams are purged from the archive. This has led to a lower fee-per-study expense with the institution's PACS vendor, Baker said.
"We have had a reduction of about 40% in our storage costs for external PACS studies," he noted.
The team has also been able to use the results to identify "high-use" studies for targeted permanent storage, including most recent CT, MRI, and digital mammography exams, he said.
The researchers also expanded their electronic image transfer network to allow the retrieval of purged studies if necessary. Studies that have been purged can be retrieved from the institutions that performed them in minutes, rather than days, Baker said.
