Page 108 - Imaging of Osteoarthritis and Rheumatoid Arthritis in Hand Joints
P. 108

                                Chapter 6
There was moderate agreement for erosion detection (κ=0.48) between MRI methods. While 1.5T MRI detected 18 more erosions in total, this did not result in more patients having erosions with 1.5T MRI, as 19 patients had erosions with both methods, 1 patient had erosions with 1.5T MRI only, and 2 patients had erosions with 0.2T MRI only. Most erosions in the MCP joints were present in the heads of the second and third metacarpal bone, and most erosions in the wrist were present in the scaphoid, lunate, triquetrum and capitate bone.
BME was uninterpretable on the 1.5T images in one patient, and therefore analysed in 39 patients. There was poor agreement (κ=0.19) for BME detection between the MRI methods, as only 8 bones showed BME on 0.2T. In all patients with BME, BME was present in a wrist bone, with the lunate bone being most affected (11 patients on 1.5T MRI). A typical example of BME not detected with 0.2T is shown in Fig 3.
On the 0.2T scanner, the proximal part of the wrist was partly outside the field of view (FOV) in seven patients. The distal radius (n=6), distal ulna (n=6), distal radioulnar joint (n=7), and lunate bone (n=1) were not analysed with both methods if they were outside the 0.2T FOV.
Low field MRI versus ultrasound
Table 3 displays the amount of detected pathology for both MRI and both ultrasound methods and their agreement in numbers in the ultrasound subset of 26 patients. The clinical ultrasound and MRI methods detected almost the same amount of joints with synovitis, but there was poor agreement between clinical ultrasound and 1.5T MRI (κ=0.26) and between clinical ultrasound and 0.2T MRI (κ=0.25). 9 patients were scored positive for one or more joints with synovitis with both 0.2T MRI and clinical ultrasound, 8 patients were scored positive for synovitis with 1.5T MRI, and 5 patients were scored positive with clinical ultrasound. Standardised US detected less joints with synovitis than the other methods (Table 3), resulting in 5 patients having synovitis. However, almost all joints with synovitis on standardised US also had synovitis on MRI (93% vs 1.5T). 6 erosions were detected with the clinical US method in two different patients. No erosions were detected with the standardized ultrasound method.

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