Abstract: Objective To investigate the diagnostic value of multi-slice spiral CT (MSCT) combined with dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in osteosarcoma. 

Methods A total of 200 patients with suspected osteosarcoma admitted to our hospital were retrospectively analyzed. All patients were examined by MSCT and DCE-MRI, and the clinical diagnosis and pathological examination results were taken as the gold standard. The imaging findings of the two examinations were analyzed, and the examination results, diagnostic value and pathological features of osteosarcoma of MSCT and DCE-MRI alone and in combination were compared. 
Results MSCT scan showed irregular destruction of cortical bone, relatively clear boundary, infiltration in bone marrow, and uneven density of surrounding soft tissue mass. There could be high density of tumor bone in the bone, and the tumor bone could be seen at the articular cartilage surface, protruding into the articular cartilage surface to form an intra-articular mass. DCE-MRI showed bone destruction, periosteal hyperplasia, cortical bone thinning, interruption or absence, and the destruction area that was occupied by soft tissue mass invading the muscle, presenting as medium to high mixed signal mass. When invading the epiphyseal plate and joint, it was clearly shown. The invasion of tumor in bone marrow showed a clear boundary with the normal bone marrow and a tendency to jump and spread. Ktrans was 0.967 min-1, and Kep was 3.548 min-1. The consistency between the results of MSCT combined with DCE-MRI and pathological examination (kappa=0.755) was significantly higher than that of MSCT (kappa=0.416) and DCE-MRI (kappa=0.439) (P＜0.05). The negative predictive value, positive predictive value, sensitivity, specificity and accuracy of MSCT combined with DCE-MRI were higher than those of single detection (P＜0.05). The accuracy of MSCT combined with DCE-MRI in the pathological features of osteosarcoma was higher than that of single detection (P＜0.05). 
Conclusion The negative predictive value, positive predictive value, sensitivity, specificity and accuracy of MSCT combined with DCE-MRI are higher than those of single detection, which has high diagnostic value for osteosarcoma.

Key words: osteosarcoma, multidetector computed tomography, magnetic resonance imaging ,