A standardized examination procedure in patients with RA is useful for both assessment of disease activity, monitoring of treatment and in clinical trials. The results from this training program suggest that skills in standardized US examination of the hand in patients with RA can be achieved by most rheumatologists, after a short training program. Nearly, all the participating rheumatologists demonstrated scores above the preset cut-off level from the very beginning, without obvious differences due to variation in previous experience. This was also demonstrated by the lack of association between time spent on the standardized US examination and the rheumatologists' US experience. However, it must be noted that nearly all participants had a moderate to high degree of US training including several courses and two full days of hand-on experience with the present technique.
In accordance with recent results from other groups , this study indicates that the pitfall of US operator dependency may be avoided with a short focused training program provided that the anatomical region under investigation is sufficiently small (wrist and mcp-joints in this study). Also, bear in mind that we have only focused on ability to obtain images of a certain quality and not focused on ability to diagnose pathology.
Very low scores were only seen in a few cases and were associated with early exit from the study by some of the participants. Consequently, the study gives no answer to the obvious question whether even such rheumatologists might have achieved US examination at a higher level with further training.
The final average examination time of less than 10 minutes (Figure 4) for the standardized procedure of 16 positions, was below the examination time used in another longitudinal study in which US 17 positions were examined .
Despite the continuous feed-back, many participants made one persistent mistake throughout the entire study: imprecision of the standardized landmarks in the images of the MCP joints. Besides this mistake, only small flaws in the examinations were noted and with the exception of landmarks in MCP images from the analyses, the scoring level would have increased to nearly 100%. The importance of obtaining precise landmarks is recognised in US training programs [12, 13] and precision of landmarks is mandatory in both longitudinal and multicentre studies to achieve comparable images.
We chose the hand as target for this training program, because the joints of the hand are frequently involved in RA ,  Furthermore, it has been indicated that it is difficult to acquire satisfactory skills in US examination of the hand . Thus, by choosing the hand, we avoided the bias that good learning curves were obtained by examining a simple joint.
The good results may also be attributed to our use of the same preset on all machines. This preset ensured comparable images of a relatively high quality in all patients instead of e.g. using the factory preset MSK where each exam would require some adjustments. We wished to investigate the ability to obtain reliable colour Doppler images which in our opinion demands a fixed preset. Therefore, we scored the participants' ability to correctly adjust Doppler focus and not ability to adjust Doppler gain, PRF, wall filter etc. The use of a fixed preset is a prerequisite for monitoring disease activity with Doppler and at the same time it minimises the risk of poor image quality caused by incorrect machine settings .
Perhaps the most important result of our study was the reduction in time spent on the examination to a feasible level for clinical practice. This result was achieved at the cost of a small reduction in score, i.e. quality, which may partly be explained by the very high scores among most of the participants from the very beginning of the study period, causing a ceiling effect, or a type of negative learning progression in a few cases. The scores did not deteriorate in a way that could indicate development of some sort of carelessness with the routine. However, the participants in trials may be more keen and accurate with supervised examinations than in the daily clinic and the results require confirmation in a clinical setting.
Standardized examination procedures improve the validity of US and make it more suitable for both clinical practice and follow-up studies. As the training program had the result that most rheumatologists achieved satisfactory skills in performing a standardized US examination it might be assumed that training will improve the quality of the US procedure and thereby the patient outcome . In order to answer this question satisfactorily the effect of a standardized examination procedure on the monitoring of treatment of patients with RA must be clarified.
The present results indicate that a learning program may ensure the acquisition of standardized high quality images, which is a prerequisite for using US for making reliable diagnoses and follow-up examination e.g. according to the OMERACT filter . Standardization may enable comparison of examinations performed at different institutions and make performance of multicentre trials possible.
In our study the diagnostic skills of the participating rheumatologists were not assessed and it could be assumed that skills in US scanning for a diagnostic purpose will demand more training to achieve a satisfactory level.