Page 123 - Imaging of Osteoarthritis and Rheumatoid Arthritis in Hand Joints
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 CT versus CR in thumb base OA
CT seems a better imaging modality than CR for detection of thumb base OA. In chapter 3 we have shown that CT has a higher reliability than radiography for detection of OA features in the thumb base, and detects more OA features than radiography in patients with severe thumb base OA. It is known that CR has low sensitivity, but high specificity for detection of scaphotrapeziotrapezoidal (STT) OA5. We detected with CT more OA features in the STT joint, and expect most of these findings to be accurate. We therefore assume that CT has a better sensitivity than CR. However, we have no indication on how the specificity of CT relates to CR and future studies could determine this and it’s sensitivity by comparing pre-operative CT with arthroscopy.
CT is advised above CR only in certain pre-operative situations. In daily practice,
the higher sensitivity of CT would not matter in most clinical settings, as in
most cases it will not lead to a changes in clinical management, as there are
limited therapeutical options. However, in severe thumb base OA surgical
resection may be considered, and the presence or absence of OA on adjacent
joint surfaces may influence the type of surgery. Some hand surgeons advocate
the use of imaging in severe OA to pre-operatively determine the joint status
and plan the type of surgery, while others rather determine the joint state peroperatively6. We realize that it is unknown if use of pre-operative CT leads to
any improved patient outcome, and to prove this a large trial is needed, which
is probably not feasible. However, for those surgeons preferring to know the
joint state pre-operatively, we would advise to use CT above CR for detection 7 of OA in the STT joint.
Low field MRI and ultrasound in early arthritis
Contrast-enhanced low field MRI is good method for detection of synovitis. As shown in chapter 6 contrast-enhanced low field MRI is as good as contrast- enhanced high field MRI for detection of synovitis in arthralgia and early arthritis patients. Standardized ultrasound examination had a lower sensitivity than MRI, but in comparison with high field MRI, was highly specific. The field strength of the MRI machine does not matter in the diagnostic capability
General discussion

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