To the Editor:
We read with interest the letter in this issue by Hall-Craggs and colleagues1 discussing the developing field of diffusion-weighted imaging (DWI) and its application for quantification of inflammation in rheumatology. As proponents of quantification in medical imaging, we agree that DWI does indeed have some advantages. Its ability to objectively quantify diffusivity of water molecules in the brain was well established many years ago2 and is now absolutely essential for magnetic resonance imaging (MRI) of stroke, providing unique information about brain cell injury due to hypoxia. DWI is now often used for detection and characterization of tumors3. However, its application for assessment of inflammation outside the brain is at an earlier stage of development. One potentially exciting application may be the assessment of synovitis, where conventional sequences have difficulty distinguishing inflamed synovium from effusion without intravenous (IV) injection of a contrast agent. If DWI turns out to be a suitable substitute for the IV injection4, it would be …
Address correspondence to Prof. R.G. Lambert, Department of Radiology and Diagnostic Imaging, University of Alberta, 2A2.WMC, 8440-112 St., Edmonton, Alberta T6G 2B7, Canada. E-mail: rlambert{at}ualberta.ca