Implementation of an online and CD-based image transfer system helped reduce repeat imaging, costs and radiation dose to patients transferred to a level 1 regional trauma center, according to a study published in the September issue of Journal of American College of Radiology.
In the past decade, CT rates in the emergency department (ED) have escalated, as have CT repeat rates among transferred trauma patients. Previous research has documented CT repeat rates for trauma patients in the 29 to 58 percent range, and repeat lab tests and imaging exams were estimated to cost an additional $600 per trauma patient in 2000.
“Unnecessary reimaging adds extra cost, time, and potentially extra radiation and iodinated contrast exposure to patients,” wrote Patrick T. Flanagan, MD, of the department of radiology at Santa Clara Medical Center in San Jose, Calif., and colleagues. The researchers explained that regional image transfer networks might address some of these challenges.
Harborview Medical Center (HMC) in Seattle established an internet-based virtual private network with direct connections between outside hospitals and the trauma center, and also supports CD-based image transfer.
Flanagan and colleagues devised a retrospective cohort study to examine the impact of the network on imaging repeat rates, costs and radiation dose and compared these metrics with previously published repeat rates.
The image transfer network encompassed 109 referring community hospitals and radiology practices. The primary mode of image transfer uses a separate HMC PACS for temporary storage prior to transfer to the main PACS. If a virtual private network connection is unavailable, CD-based image transfer is used.
The HMC radiology department developed and shared with community hospitals minimum CT imaging standards for trauma exams, and “indicated that if a patient underwent a CT study that met these standards, the study would not be repeated at the trauma center unless indicated for a change in clinical status.”
The study encompassed 491 trauma patients transferred to HMC between June 1, 2009 and July 15, 2009.
Flanagan and colleagues identified all CT and x-ray exams performed at the sending hospital and transferred into PACS, and all trauma studies, on each transferred trauma patient. Imaging exams performed at HMC were classified as completion or repeat studies. A completion exam entailed imaging of a different body region than the initial outside study or an additional study of the initial body part based on a change in clinical status or need for follow-up. A repeat exam was performed after an initial outside study of the same body part.
Among the transferred patients, 53 percent had outside x-rays, 65 percent had outside CT studies and 78 percent had some form of imaging exam imported into the trauma center.
A total of 17 percent of patients who had CT exams imported underwent repeat exams. “Reasons for repeat CT were inadequate outside CT for 36 patients, unknown for 21 patients, 3D reconstructions required for nine patients and images inaccessible on PACS for three patients,” wrote the researchers.
Twelve percent of x-ray exams, which represented more than half of all imported x-ray studies, were repeated in the trauma center ED.
Flanagan and colleagues estimated the cost of CT imaging transferred at $768.09 per patient who had CT studies transferred. The estimated value of CT exams repeated at the trauma center was $84.65 per patient who had imported outside CT exams.
Among the 318 patients with outside CT exams imported into PACS, the average effective radiation dose attributable to the imported exam was 11.3 mSv. Repeat CT imaging accounted for an additional 1 mSv per patient in these 318 patients.
The researchers emphasized the lower repeat CT rates at HMC compared with previous literature reports and attributed these results to four reasons:
- Dissemination of trauma CT standards to referring hospitals;
- Use of a radiologist gatekeeper to review acceptability and determine the necessity of repeat imaging for incoming CT studies;
- A low rate of CD incompatibility issues (HMC prioritized internet links for hospitals that had difficulty importing CDs); and
- Capability to phone outside hospitals to request transmission of additional CT reconstructions after the patient’s arrival.
In addition to the documented benefits of reduced CT imaging, radiation exposure and costs, Flanagan et al noted additional potential