Page 122 - Imaging of Osteoarthritis and Rheumatoid Arthritis in Hand Joints

Chapter 7
interesting for research purposes, as the presence or absence of cartilage damage does not have clinical implications.
MRI Cartilage evaluation in hand joints can be further improved by using quantitative cartilage measurements. In this thesis we mostly used semi- quantitative scoring systems to assess the imaged cartilage. Fully quantitative measurements have the advantage of being less dependent on reader experience 2 and may be able to pinpoint smaller changes, but are very time- consuming when performed manually. Semi-automated and fully automated quantification of cartilage thickness programs are available for the knee joint and should be translated for use in small hand joints, so quantitative cartilage measurements can be used in larger hand OA studies. However, software for (fully)-automated cartilage quantification requires sufficient quality of the images. The in-plane resolution of the acquired hrMRI images in our studies should be high enough for (semi)-automatic quantification. However, the contrast between cartilage and joint fluid was low in some patients, which may hinder automatic quantification. This low contrast may partly be caused by partial volume averaging in the slice direction. Future studies should therefore also focus on improving the images for automated cartilage volume measurements, which could be done by creating more isometric voxel sizes, or optimizing other often used MRI sequences for knee cartilage, for use in small hand joints, to acquire better contrast.
Other promising MRI features for cartilage evaluation are markers of cartilage composition. All previously mentioned measurements asses the morphology of the cartilage. The MRI acquired techniques delayed gadolinium enhanced MRI of cartilage (dGEMRIC), T2-mapping and T1ρ-mapping each depict different aspects of the composition of the cartilage, and can display degeneration of the cartilage before morphological cartilage changes are present 3. These biomarkers are still under investigation in knee OA and show promising, but varying results. Of these techniques, dGEMRIC seems to be the most robust method 4, and the only method investigated so far in small hand joints. Future studies should further investigate the additional worth of compositional cartilage biomarkers in small hand joints.
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