Despite its great promise in non-invasive treatment of
cancers, magnetic resonance-guided focused
ultrasound surgery (MRgFUS) is currently limited by the insensitivity of magnetic resonance imaging (MRI) for visualization of small
tumors, low efficiency of in vivo ultrasonic energy deposition, and damage to surrounding tissues. We hereby report the development of an active targeting nano-sized
theranostic superparamagnetic
iron oxide (
SPIO) platform for significantly increasing the imaging sensitivity and energy deposition efficiency using a clinical MRgFUS system. The surfaces of these PEGylated
SPIO nanoparticles (NPs) were decorated with anti-EGFR (
epidermal growth factor receptor)
monoclonal antibodies (mAb) for targeted delivery to
lung cancer with EGFR overexpression. The potential of these targeted nano-
theranostic agents for MRI and MRgFUS ablation was evaluated in vitro and in vivo in a rat xenograft model of human
lung cancer (H460). Compared with nontargeting PEGylated
SPIO NPs, the anti-EGFR mAb targeted PEGylated
SPIO NPs demonstrated better targeting capability to H460
tumor cells and greatly improved the MRI contrast at the
tumor site. Meanwhile, this study showed that the targeting NPs, as synergistic agents, could significantly enhance the efficiency for in vivo ultrasonic energy deposition in MRgFUS. Moreover, we demonstrated that a series of MR methods including T2-weighted image (T2WI), T1-weighted image (T1WI), diffusion-weighted imaging (DWI) and contrast-enhanced T1WI imaging, could be utilized to noninvasively and conveniently monitor the therapeutic efficacy in rat models by MRgFUS.