Page 134 - Imaging of Osteoarthritis and Rheumatoid Arthritis in Hand Joints
P. 134

                                Chapter 8
The validity of direct cartilage imaging in small hand joints with high resolution MRI (hrMRI) is assessed in chapter 4. Here patients with thumb base OA scheduled for trapeziectomy underwent hrMRI of the CMC1 joint before surgery. Afterwards histological sections of the removed trapezium were compared with MRI findings. Severe cartilage loss was present in these patients, and MRI accurately visualized the size of overall areas of cartilage damage. However, the depth of the cartilage loss was often underestimated by MRI. This was caused by thin lines of high signal intensity which were visible with MRI on the eroded articular which resembled remaining cartilage.
Chapter 5 continues the evaluation of direct cartilage imaging with hrMRI, by comparing it to indirect MRI cartilage evaluation using inter-bone distance in both hand OA patients and healthy controls. Reliability of the both methods was comparable. With direct cartilage imaging more joints with subtle cartilage damage were detected in hand OA patients, and less false positive joints were detected in healthy controls, suggesting better validity.
Finally, in chapter 6, a less expensive low field MRI was compared with normal high field MRI and ultrasound for the detection of synovitis, bone marrow edema, and erosions, in patients with hand arthralgia and early arthritis. Compared with high field MRI, low field MRI was as good in detecting synovitis, better than ultrasound; low field MRI had poor sensitivity for detecting bone marrow edema; and for erosions, low field MRI was better than ultrasound but less sensitive than high field MRI. Chapter 7 is a general discussion about the acquired results, limitations of the performed research and future research opportunities concerning direct cartilage imaging with MRI; use of CT in the thumb base OA; and use of low field MRI and ultrasound in early arthritis. The main conclusions of this thesis were:
• Direct cartilage imaging with high resolution MRI in small hand joints has a higher accuracy than indirect cartilage imaging.
• CT has a better detection rate of OA features in the STT joint than conventional radiography, and may therefore be recommend pre-surgery if this influences the surgical plan.

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