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Re: A probable flaw of the RAMRIS atlas

Dear Editor,

I have read with interest the series of articles presenting the development of a working atlas for Rheumatoid Arthritis scoring with MRI. It will surely prove to be a useful and objective tool for the evaluation, prognosis and follow-up of these patients. I find however, a practical issue that could render this scoring system as somewhat cumbersome, unless a better protocol for clinical MRI is developed. In clinical practice, I have been increasingly receiving requisitions from our rheumatologists for "bilateral hands and wrists, before and after Gadolinium enhancement". Although I do have a hi-resolution 1.5 T system with a dedicated wrist coil that can offer adequate spatial, contrast and temporal resolution for the detection and scoring of bone erosion and edema, Gadolinium enhancement for synovitis scoring is hindered by time constraints already mentioned in the OMERACT- RAMRIS series of articles: Since each wrist has to be imaged individually, after gadolinium is administered, only one side could be adequately imaged in terms of time-after injection effects (temporal resolution). In cases of unilateral symptoms, some would be inclined to image only the clinically affected side; this could lead to non-detection of early changes in the contralateral side. In order to apply adequately the RAMRIS, two separate imaging sessions would have to be scheduled, probably a couple of days apart. This is also obviously impractical, especially for RA patients that are in pain.

Although I have no hard evidence, I do believe that STIR imaging with current state-of-the art equipment, in which different weightings can be achieved, should be capable of demonstrating clinically significant degrees of edema and inflammation, not only of bones but of soft tissues, and that STIR imaging in at least two planes, transverse and coronal, may prove to be a better and more practical solution for this issue, allowing complete imaging in a single appointment; even for patients that are not in pain, this would be a significant improvement in medical care.

I would urge the OMERACT group experts to consider the development of a similar scoring system and reference atlas based on images that can be achieved in clinical practice without the mentioned limitations, such as STIR images. Several questions remain to be answered: optimal planes of imaging, FOVs, inversion times, TR/TE and all the other possible or relevant technical parameter selection remain to be standardized at common magnet strengths. Such a multicenter task group should be able to fulfill the sample requirements and other methodological aspects needed for a well -designed correlation between STIR images and gadolinium enhancement that could answer this practical issue.

Sincerely Yours,