June 1, 2009
Diagnostic Imaging Europe.
No. 4
Sonoelastography displays promise in tendon injuries
Distinct tissue softening linked to musculoskeletal disorders can be detected in real-time strain imaging
BY ANDREA S. KLAUSER, M.D., TOBIAS DE ZORDO, M.D., AND RALPH FASCHINGBAUER, M.D.
DR. KLAUSER is an associate professor of radiology at the University Hospital of Innsbruck in Austria. DR. DE ZORDO is a radiology fellow at the same institution and also a research fellow at the London Health Science Centre, University Hospital, in London, Ontario, Canada. DR. FASCHINGBAUER is a radiology fellow at the University Hospital of Innsbruck.
Operator dependency is a known challenge for all imaging techniques based on ultrasound. We attempted to obtain appropriate images by moderating the pressure exerted with the ultrasound probe, avoiding overly high and low pressures. The aim was to maintain a near-proportional relationship between pressure exerted and tissue strain. This could be monitored using the visual indicator scale on the machine.4 In images in which the pressure decreased below a certain level, the pattern of the elasticity image started to change drastically. Tissue shifting due to unilateral compression is another potential limitation. The use of a gel standoff pad can help to alleviate this problem. This was confirmed before we started the study from a comparison of images obtained with and without a gel pad.  RTSE construction of images also led to soft-tissue artifacts in the Achilles tendon and common extensor tendons, as well as in surrounding bony structures. It became easy to differentiate artifacts from reliable findings after some practice. Each RTSE scan was repeated three times to minimize the problem.
In summary, our preliminary results using RTSE for the first time in musculoskeletal disorders revealed that the elastic properties of normal tendons are altered under pathological conditions and that this distinct intratendinous softening can be detected. We believe that more lesions could be found by using this method instead of conventional ultrasound and that this could result in earlier and more accurate diagnoses of tendinopathy. This new technique might, in the future, be used as an adjunct to conventional ultrasound to increase diagnostic accuracy. It could also potentially be used as a screening tool, allowing athletes to modify their exercise regimen to prevent further tendon damage.
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