In vivo MR quantification of superparamagnetic iron oxide nanoparticle leakage during low-frequency-ultrasound-induced blood-brain barrier opening in swine.

Purpose: To verify that low-frequency planar ultrasound can be used to disrupt the BBB in large animals, and the usefulness of MRI to quantitatively monitor the delivery of superparamagnetic iron oxide (SPIO) nanoparticles into the disrupted regions.

Materials And Methods: Two groups of swine subjected to craniotomy were sonicated with burst lengths of 30 or 100 ms, and one group of experiment was also performed to confirm the ability of 28-kHz sonication to open the BBB transcranially. SPIO nanoparticles were administered to the animals after BBB disruption.

Magnetic resonance monitoring of focused ultrasound/magnetic nanoparticle targeting delivery of therapeutic agents to the brain.

The superparamagnetic properties of magnetic nanoparticles (MNPs) allow them to be guided by an externally positioned magnet and also provide contrast for MRI. However, their therapeutic use in treating CNS pathologies in vivo is limited by insufficient local accumulation and retention resulting from their inability to traverse biological barriers. The combined use of focused ultrasound and magnetic targeting synergistically delivers therapeutic MNPs across the blood-brain barrier to enter the brain both passively and actively.

In vivo assessment of macrophage CNS infiltration during disruption of the blood-brain barrier with focused ultrasound: a magnetic resonance imaging study.

Focused ultrasound has been discovered to locally and reversibly increase permeability of the blood-brain barrier (BBB). However, inappropriate sonication of the BBB may cause complications, such as hemorrhage and brain tissue damage. Tissue damage may be controlled by selecting optimal sonication parameters.