A Novel Dual-Frequency Method for Selective Ultrasound Imaging of Targeted Nanoparticles

Current methods for ultrasound (US) molecular imaging suffer the lack of image processing techniques specifically designed to identify the newer nanosized contrast agents (CAs). The available pulse sequences and signal analysis methods for US contrast detection, in fact, were developed for the older microbubble CAs, whose acoustic properties differ significantly from those of nanoparticles. This work illustrates the implementation and experimental testing of a new contrast detection scheme, tailored to enhance the contribution of solid nanosized CAs in echographic images. The proposed protocol, including a novel pulse sequence and a two-step image processing algorithm, was evaluated on a phantom consisting of silica nanospheres dispersed into an agarose gel matrix that was imaged through a conventional echographic transducer. Obtained results demonstrated the capability of selectively suppressing non-contrast echoes, without any loss in spatial resolution and maintaining the characteristics of real-time imaging, therefore showing very promising perspectives for clinical applications.