Ultrasound in diagnosing Rheumatoid Arthritis
I chose to do my last blog on looking at the patient pathway for someone with suspected Rheumatoid Arthritis, within this I found that Ultrasound imaging is a useful way to image Arthritis. From the comments on my last blog it sparked an interest to look further into comparing what is commonly known amongst Radiographers as a good imaging source (MRI) to another more ambiguous way of imaging (Ultrasound). This blog will look into the strengths and weaknesses of ultrasound through diagnosis of the condition, my next blog will investigate monitoring of rheumatoid.
Ultrasound has been used in Rheumatology for around 30 years but with advances in equipment and our knowledge of the clinical signs of RA it is now used much more in diagnosis. Ultrasounds use in Rheumatology is either used in the clinical setting or for research purposes due to there being no use of radiation and its ability to image in multiple plains, giving us a high amount of information. One of the reasons why Ultrasound isn’t more regularly used in imaging RA is due to the skill needed to image the patient and also the knowledge of rheumatic diseases, in this article a way suggested to overcome this problem is either Rheumatology being trained in Ultrasound or Radiologists having a more in-depth knowledge of rheumatic disease (Wakefield, R, et al, 1999). This article picks up on the use of Ultrasound in Rheumatology and uses a number of reliable sources including the initial study on the first clinical use of Ultrasound in 1972 by McDonald and Leopald. Although this article and its’ references could be said to be outdated they are some of the first investigations into the uses of Ultrasound looking at MSK disorders and so are useful to look at. A more recent article has looked into the use of present day Ultrasound and states that there were guidelines produced in 2001 to set the standardisation of ultrasound use for Musculo-skeletal problems. In 2006 EULAR also introduced a new training program which had three different levels, this allowed Rheumatologists to be trained in Ultrasound (Kang, T, et al, 2012). This article is useful as it shows how we have improved our training and guidelines in the 21st century to not only improve inter-professional working but to also lessen the amount of time the patient will spend in hospital by having a scan done at the same time as seeing their Rheumatologist.
Concerning the diagnosis of RA with Ultrasound it’s important to use the correct transducer to get the best properties for the part of the body that’s being imaged e.g a high frequency transducer is of better use for less dense areas of the body due to poor penetration. “Hockey Stick” transducers are good for imaging MCP joints due to its’ small surface area and its ability to get the correct angles so that the joint can be viewed in 3D (Wakefield, R, et al, 2000). This study by Wakefield is useful in looking at the different transducers and equipment used for imaging in Ultrasound however the study itself lacks validity in not having patients with different severities of RA and only having 100 participants making it unrepresentative. Also, intra observer reliability was only looked at in 40 of the scans produced, for this to be more reliable they should have looked at at least 90% of images to reduce any errors in diagnosis.
Joint space widening is an indication of joint inflammation and Ultrasound is useful in distinguishing between these various types of inflammation, synovium is not normally seen in a patient with healthy joints. Synovium is the main target of inflammation and if not recognised can cause irreversible damage to cartilage and bone (Arthritis Research UK, 2011). Joint effusion is another indication of RA and shows up on an ultrasound as being hyperechoic, this is due to a change in the bone structure making it weaker and therefore giving off fewer reflective waves. This compares to the synovium becoming thicker and therefore more echogenic, reflecting more of the ultrasound waves. The comparison of these two pathological changes show the sonographer that there are changes in the structure of bone and synovium and can then begin to make an accurate diagnosis. Looking at the amount of false negatives and positives Ultrasound is good at early detection of RA but isn’t as good to differentiate between the different causes of thickened synovium or bone erosion (Tsou, I, 2014).
Kang,T., Lanni, S., Nam, J., Emery, P and Wakefield, R. (2012) The Evolution of ultrasound in rheumatology. [online] 4 (6). pp. 399-411. [Accessed 2nd December 2014]
Taggart, A., Benson, C and Kane, D. (2011) Arthritis Research UK: Ultrasound in Rheumatology. [online] 6 (9). pp. 1-16. [Accessed 2nd December 2014]
Tsou, I (2014) Rheumatoid Arthritis hand imaging. Available from: http://emedicine.medscape.com/article/401271-overview#a22 [Accessed 2nd December 2014]
Wakefield, R., Gibbon, W and Emery, P (1999) British Society for Rheumatology: The current status of ultrasonography in rheumatology. [online]. 38. pp. 195-201. [Accessed 2nd December 2014]
Wakefield, R., Gibbon, W., Conaghan, P., O’Connor, P., McGonagle, D., Pease, C., Green, M., Veale, I and Emery, P. (2000) Arthritis and Rheumatism: The value of sonography in the detection of bone erosions in patients with rheumatoid arthritis. [online] 43 (12), pp. 2762-2770. [Accessed 2nd December 2014]