To the Editor:
We read with interest the recent paper on diffusion-weighted imaging (DWI) as a means of supporting the diagnosis of ankylosing spondylitis1, and the corresponding editorial questioning the role of DWI2. The paper1 adds to the growing body of evidence supporting the use of DWI to characterize and quantify inflammation in patients with spondyloarthritis (SpA)3,4. The corresponding editorial argues that DWI is of limited clinical use, and the authors’ main criticisms are summarized as follows:
Any sequence can be measured numerically, and this is a facility not confined to DWI.
The number of steps required for normalizing measurements and choosing regions of interest (ROI) depends on review of the initial qualitative images and is subjective.
The variable diffusion of background marrow poses further challenges for DWI.
However, if we look in greater detail at the existing literature on quantitative imaging, it is apparent that many of these issues can be addressed, and indeed there are multiple advantages that quantitative techniques …
Address correspondence to Prof. M.A. Hall-Craggs, 2nd Floor, Charles Bell House, 43-45 Foley St., London W1W 7TS, UK. E-mail: margaret.hall-craggs{at}nhs.net