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SP0124 How to Enhance Synovitis Detection: Impact of Joint Position and Scanning Technique
  1. H.B. Hammer
  1. Dept Of Rheumatology, Diakonhjemmet Hospital, Oslo, Norway

Abstract

Ultrasound (US) is a clinical tool for evaluating inflammatory and degenerative changes in patients with different sorts of rheumatic diseases. As all clinical and imaging assessments, it is dependent on the assessor's level of theoretical and practical knowledge in the different sorts of evaluations. However, several studies have shown that with increasing experience as well as agreement on scoring systems, the reliability increases in assessments of different imaging modalities, including US, while similar increased reliability has not been shown for clinical evaluations including swollen joints. The difficulty in clinical assessments is the lack of golden standards that is agreed upon by all rheumatologists, while this has been developed for the imaging methods including US.

Basic knowledge of US is fundamental for expanding the scanning technique. The present high-end US machines give us the possibilities to search for new areas to be examined by US scanning. Based on good anatomical knowledge, US could be used to examine for synovitis also in areas not often assessed, as carp-metacarpal joints in the hands. In addition, it is of major importance to bear in mind the physical limitations of this method, including the awareness of being light-handed when exploring Doppler activity, using optimal amount of gel, and always taking care of using the optimal frequency for assessing different tissues.

To do optimal clinical US examinations, it is of importance to be focussed on the goal for each examination. When the purpose is to evaluate degree of synovitis in for instance the elbow as part of a general search for joint inflammation, it is usually sufficient to perform one or two scans (anterior and/or posterior longitudinal) and not include all the six standard elbow scans. However, if the patient has pain in for example the wrist, it is not sufficient to use the standard scans for evaluation of synovitis in the wrist, but you have to search for synovitis in as many of the 17 wrist joints as possible as well as including all the flexor and extensor tendons and evaluate the nerves, malalignments and possibly ligaments as well.

With the scope of examine for inflammation, it is of importance to evaluate the joints in positions that are most sensitive for detection of synovitis. In the shoulder, the most sensitive method is by external rotation of the lower arm, causing the synovitis/fluid to bulge out and easily detected by US with a posterior transvers scan. Another example of joint positioning is the evaluation of the knee for enthesitis. When flexion of the knee joint, the quadriceps and patellar tendons are stretched, giving nice grey scale images, but highly decreasing the Doppler activity in the tendons. This will cause decreased sensitivity for detection of enthesitis or tendinitis. All examinations for Doppler demands the structure to be relaxed, and thus, it is of major importance to constantly be aware of this issue when performing US to assess inflammatory activity.

Thus, to optimize the US scanning, a constant awareness of joint positioning and scanning technique will highly increase the value of the US examination.

Disclosure of Interest None declared

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