By Dr Roberto Russo, Rheumatologist & Nuclear Medicine Physician
Awareness of Entheseal disease (enthesopathy) is increasing, which in part relates to the increasing use of imaging. Modalities such as Magnetic Resonance Imaging, Ultrasonography, and Nuclear scintigraphy are able to assess the enthesis organ in detail. These imaging tests are quite sensitive in their ability to detect disease, meaning that when disease is present these tests are able to detect an abnormality.
However, are these investigations clinically useful?
That is, despite their sensitivity in detecting disease, do they actually play an important role in diagnosis?
Although an obvious and simple answer to this question may be ‘yes’; the reality however is that clinical assessment, including a thorough history and examination, has a similarly high sensitivity in diagnosis such that, in general, imaging probably does not play a significant role in diagnosis of this disease.
However, the point I am wishing to make by stating ‘in general’ is that perhaps imaging may instead be of greater value in differentiating entheseal disease of mechanical origin versus that which is due to inflammatory rheumatic diseases, such as the spondyloarthropathies.
This idea arises from preliminary work that has shown that when adjacent bone is affected at the enthesis, it is more likely to represent Rheumatic enthesitis compared to a mechanical cause. The involvement of the bone can be demonstrated on an MRI scan, as it can show swollen bone that is called bone marrow oedema. Nuclear scintigraphy is in fact considered even more sensitive in this regard because it reflects the activity of the bone forming cells called Osteoblasts. Further research in this area is eagerly awaited, specifically in terms of the implications that such findings may have upon the approach towards treatment.
Treatment of entheseal disease can also be guided by the imaging findings, in addition to what has been discussed above. What I am specifically referring to is that a common treatment used in the management of this condition involves injection therapy. This may be in the form of corticosteroids, platelet rich plasma, autologous (ie your own) blood, and even dextrose (sugar) termed prolotherapy. This simple list highlights that a vast number of options are available, of which many of them work via different mechanisms. And so it is left to the clinician to face the difficult task of having to choose which form of these therapies is best for their particular patient; a decision that is currently made on very little evidence. It is with this decision that I feel imaging can be most valuable.
I will expand on this in my next blog when I discuss the features present on nuclear scintigraphy and ultrasonography that can predict the response to corticosteroid injection in enthesopathy.
Dr Roberto Russo is both a rheumatologist and a nuclear medicine physician, as well as a director of BJC Health.
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