LOCALIZED DELIVERY OF DIAGNOSTIC OR THERAPEUTIC AGENTS USING FOCUSED ULTRASOUND

In a method for enhancing localized delivery of a diagnostic or therapeutic agent using focused ultrasound (FUS), ultrasound-controllable drug carriers are administered into a blood vessel. Each drug carrier comprises an ultrasound-sensitive microbubble loaded with the diagnostic or therapeutic agent. The drug carriers are aggregated inside the vessel both along a radial direction and a longitudinal direction by application of an aggregation FUS sequence. Subsequently the diagnostic or therapeutic agent is released from the drug carriers by application of an uncaging FUS sequence. The aggregation and uncaging sequences are applied using FUS below a threshold power level such that harmful cavitation is avoided, as evidenced by the absence of broadband emissions and preferably non-integer harmonics from an emission spectrum of the drug carriers. Thereby damage to the vasculature by the FUS sequence is avoided. The method can in particular be employed to deliver drugs to the brain without opening the blood-brain barrier.