MRI guided focal blood brain barrier opening using focused ultrasound

Focal reversible opening of the blood brain barrier (BBB) was induced in rabbit brain using magnetic resonance imaging (MRI) guided focused ultrasound energy. A series of targeted ultrasound bursts were emitted at low pressure levels after intravenous administration of a commercially available ultrasound contrast agent containing preformed gas bubbles. The deposition of acoustic energy bursts resulted in focal MRI signal intensity changes. The opening of the BBB was confirmed by detecting MRI contrast agent at the same location. The correspondence of focal MRI signal change with the uptake of large molecular size contrast agent makes image-guided targeting and control possible. This noninvasive method represents a breakthrough in targeted drug delivery within the central nervous system and could have a huge impact in the treatment of brain disorders.