by Brendon Nafziger
, DOTmed News Associate Editor | July 18, 2011
Ultrasound units now come with a huge variety of features -- 3-D and 4-D scanning, elastography, noise-reduction software and even ergonomic designs to prevent repetitive stress injuries. That's why Mayo Clinic researchers, writing in the July issue of the Journal of the American College of Radiology, give some practical pointers on what to do when purchasing new equipment. Here are three:
Try before you buy
In order to find out what works best with your department, before buying a unit, take it for a test drive, argues Nicholas J. Hangiandreou, the chair of medical physics at Mayo Clinic in Rochester, Minn., and his colleagues Scott F. Stekel, an imaging informaticist, and Donald J. Tradup, a sonographer.
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Unlike, say, a CT scanner, ultrasound units are generally small, easy to transport and safe to use on volunteers (no ionizing-radiation). That's why, write Hangriandreou and colleagues, most can be evaluated for one or two days before you're required to make a purchase. (A manufacturer confirmed with DOTmed News an in-house evaluation is a common request.) And for larger orders involving multiple units, you might be able to work out even longer evaluation periods, according to the article. "The value of hands-on experience using a system before purchase cannot be overemphasized," they write.
Head-to-head performance tests
Once you have a candidate unit in your office, the team recommends running the same pre-use safety tests on the trial device that you would on one you own.
Equally important, they suggest running head-to-head tests between the candidate scanner and your current device.
First, there's phantom-based testing, preferably computerized, with the help of staff medical physicists. This can reveal subtle differences between the devices. Then, there are the tests on humans.
At Mayo Clinic, the researchers say they use two volunteers -- one thinner and easier to scan, one bigger and therefore harder to image -- and then take nearly two dozen clinical image views using B-mode, spectral Doppler and other types of exams done at their practice. The images are then uploaded to a PACS and judged by the staff, who rank them on a 1-4 scale (1=better than gold standard; 4= unacceptable).
"It is rarely possible to effectively anonymize the images, so each reviewer rates candidate image quality compared with the gold standard," the authors write.
If they have a chance, the Mayo Clinic team said they also like to run the test with patients, too, comparing the potential device with their current one in a truly real-world scenario. After getting consent from patients, they do two scans -- one with their current unit (this is the scan the diagnosis is made off), and another with the candidate scanner.
Acceptance testing and tolerance
At last, once a unit is bought, the group recommends conducting acceptance testing, and then comparing the results with the pre-purchase tests and even vendor specifications. These tests can provide a baseline for later performance and quality control tests, the authors say.
Of course, buyers will also take into account the costs of service support and training users on the new equipment. But one last tip they give when evaluating prospects is to keep an open mind. "[B]e aware of the possible tendency to harshly judge any system that is different from the current one that staff members are most comfortable with and, in some cases, may have trained on," they write. This could prevent staff from selecting a device with innovative features, just because its image doesn't "very closely resemble images on the gold-standard scanner."
For more tips from the Mayo staffers, read "Features to Consider When Selecting New Ultrasound Imaging Systems" in the July JACR.