Abstract:Obective To explore the clinical value of contrast-enhanced ultrasound(CEUS)in evaluating the early vascularization of bone grafts. Methods Ectopic bone formation models were established in 25 male SD rats and implanted with recombinant human bone morpho genetic protein-2 (rhBMP-2) and calcium phosphate cement(CPC) composite material in the left posterior leg proximal femoral head muscle space (rhBMP-2 group) and CPC grafting material in the right posterior leg proximal femoral head muscle space(common group).At 3-,7-,14-,21- and 28-day after operation,ultrasound examination were carried out,and samples were taken in 5 rats at each time point. Results Pathological examination showed that the number of neovascularization increased with time gradually from the outside to the inside after modeling.The percentage of new blood vessels reached the maximum on the 14-day after modeling in rhBMP-2 group and on the 21-day in common group.On the 28-day,the peripheral new bone formation was more mature in rhBMP-2 group than that in common group.The time-intensity-curve(TIC) analysis of CEUS showed that arrival time(AT)and time to peak(TTP)in rhBMP-2 group were earlier than those in common group on the 21- and 28-day after modeling,peak intensity(PI)in rhBMP-2 group was stronger than that in common group on the 7-,14-,21- and 28-day after modeling,and there were statistical differences in them at the same time point between two groups(P＜0.05,P＜0.01).In rhBMP-2 group,PI was positively correlated with the percentage of neovascularization (r=0.888,P<0.05);AT and TTP were negatively correlated with time (r=-0.839,-0.902,all P<0.05).In evaluating the early vascularization of bone grafts,CEUS results are consistent with pathological diagnosis. Conclusion Neovascularization of early bone regeneration can be dynamically displayed with CEUS which can provide a valuable diagnostic evidence for early non-invasive evaluation of vascularization of early bone regeneration with different bone grafting materials.