Efficient Blood-Brain Barrier Opening in Primates with Neuronavigation-Guided Ultrasound and Real-Time Acoustic Mapping.
Authors: Wu SY, Aurup C, Sanchez CS, Grondin J, Zheng W, Kamimura H, Ferrera VP, Konofagou EE
Brain diseases including neurological disorders and tumors remain under treated due to the challenge to access the brain, and blood-brain barrier (BBB) restricting drug delivery which, also profoundly limits the development of pharmacological treatment. Focused ultrasound (FUS) with microbubbles is the sole method to open the BBB noninvasively, locally, and transiently and facilitate drug delivery, while translation to the clinic is challenging due to long procedure, targeting limitations, or invasiveness of current systems. In order to provide rapid, flexible yet precise applications, we have designed a noninvasive FUS and monitoring system with the protocol tested in monkeys (from in silico preplanning and simulation, real-time targeting and acoustic mapping, to post-treatment assessment). With a short procedure (30 min) similar to current clinical imaging duration or radiation therapy, the achieved targeting (both cerebral cortex and subcortical structures) and monitoring accuracy was close to the predicted 2-mm lower limit. This system would enable rapid clinical transcranial FUS applications outside of the MRI system without a stereotactic frame, thereby benefiting patients especially in the elderly population.
Introduction
Purpose
Drug delivery with BBB opening
Study Objective
To develop an efficient transcranial focused ultrasound and acoustic mapping system for primates aided by neuronavigation to enable rapid, precise, noninvasive blood–brain barrier opening.
Animal model / Human subject
NHP (Macaca mulatta, Macaca fascicularis); age 8-20 years-old; sex: male)
Disease model
Healthy
MRI or image guidance method
Neuronavigation guidance
Targeted brain region(s)
Caudate, Putamen, Primary Motor Cortex, Central Sulcus, Precentral Gyrus
Outcomes and Safety
Summary of Outcomes
Neuronavigation-guided transcranial focused ultrasound with circulating microbubbles produced safe, transient, and localized blood–brain barrier opening in both cortical and subcortical regions of non-human primates, with accurate targeting and real-time cavitation mapping and no acute hemmorhage or edema observed
Safety-related matter
No acute damage was observed: radiologic exams 2 hours after sonication showed no hemorrhage (SWI) or edema (T2-weighted imaging). The authors state that safety mainly depends on acoustic parameters and microbubble dose and emphasize pre-treatment simulation to ensure safety and effectiveness.
Brain Region
Ultrasound Parameters
Ultrasound instrument
Single-element focused ultrasound transducer (H-107, Sonic Concepts)
FUS Frequency
0.5 MHz
FUS Pressure
0.3, 0.45, 0.6 Mpa
FUS Mode
pulsed
Pulse duration
10 ms
Duration of a single FUS session
2 minutes
Focal Characteristics
Focal depth: 62.6 mm; Focal length: None; Aperture size: None
Treatment frequency
Single session
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