Multi-functional ultrasound contrast agents for in vitro ultrasound/MR dual-mode imaging and high-intensity focused ultrasound synergism

Abstract

Objective To prepare the multi-functional ultrasound contrast agents,which were investigated for ultrasound(US)/MR dual-mode imaging and high-intensity focused ultrasound(HIFU)synergism in vitro.Methods Double emulsion method was used to prepare the superparamagnetic iron oxide(SPIO)-loaded PLGA microcapsules(s-PLGA),and its morphology,size,Fe3O4 loading capacity were assessed.Then,the prepared s-PLGA microcapsules with different concentrations were applied to perform ultrasound and MR imaging in vitro.In addition,the degassed bovine liver in vitro was directly injected into 200 μl s-PLGA in saline(0.5 mg Fe/ml)just before HIFU ablation,the saline(200 μl)and pure PLGA (200 μl)were employed for control.After HIFU ablation,the volume of coagulated tissue irradiated by HIFU was calculated.Results The s-PLGA microcapsules were observed with regular spherical morphology and its average size was(885.6 ± 133.2)nm.In vitro,the s-PLGA showed hyperechogenicity in US imaging and MR negatively enhanced effeet in T2WI,the volume of coagulated tissue irradiated by HIFU after local injection of s-PLGA was larger than that of saline and pure PLGA(P＜0.05).Conclusions The prepared s-PLGA microcapsules are successfully acted as dual-mode biological imaging contrast agents for ultrasound and MR imaging and HIFU synergism in vitro. Key words: Ultrasonography; Microbubbles; Nanotechnology; Magnetic resonance imaging; Ultrasound,high-intensity focused