Comparison study of four imaging modalities in diagnosis of primary synovial osteochondromatosis

Objective To compare the diagnostic value of X-ray, CT, MRI, and ultrasound in primary synovial osteochondromatosis ( PSO ). Methods The imaging data of X-ray, CT, MRI, and ultrasound of 42 patients with 44 knees with PSO proved by surgery and pathology were retrospectively collected and analyzed. Results The Plain X-ray demonstrated 197 calcific nodules in 28 joints, 96 ossific nodules in 24 joints, and 5 mixed type nodules in 3 joints. Compared with the data of surgery and pathology,36 joints (81.8 ％, 36/44) were diagnosed correctly by X-ray. The CT showed 8 big cartilaginous nodules in 5 joints, 255 calcific nodules in 30 joints, 146 ossific nodules in 28 joints, and 16 mixed type nodules in 7 joints. Twenty-four knees underwent volume rendering technique reconstruction which displayed the quantity, size, shape, and position of non-cartilaginous nodules clearly. Compared with the data of surgery and pathology, 40 joints (90. 9％ , 40/44)were diagnosed correctly by CT. The MRI demonstrated 8 big cartilaginous nodules in 5 joints, 70 small cartilaginous nodules in 4 joints, 248 calcific nodules in 29 joints,146 ossific nodules in 28 joints, and 16 mixed type nodules in 7 joints. All nodules displayed low signal in DWI and there was no enhancement. Compared with the data of surgery and pathology, 43 joints (97.7％,43/44) were diagnosed correctly by MRI. The ultrasound showed 8 big cartilaginous nodules in 5 joints,70 small cartilaginous nodules in 4 joints, 232 calcific nodules in 30 joints, 142 ossific nodules in 28 joints,and 16 mixed type nodules in 7 joints. Compared with the data of surgery and pathology, 43 joints (97. 7％,43/44) were diagnosed correctly by ultrasound. Conclusions The less common manifestations of the PSO require multimodality imaging to make the diagnosis. Multimodalities (X-ray,CT, MRI and ultrasound) are particularly useful in fully characterising PSO and to allow for appropriate clinical planning. Key words: Chondromatosis synovial;  Diagnostic imaging