The study find that the ultrasound imaging technique called passive cavitation imaging was able to create an image and estimate the amount of a drug that crossed the blood-brain barrier to reach a specific location in the brain; but according to a study by NIBIB-funded bioengineers at Washington University.
The ultrasound imaging technique
The technique monitors the activity of microbubbles, microscopic bubbles that help create clearer ultrasound images using detectors to estimate the effects they have on the different biological structures in this case; the brain. Therefore The brain is responsible for a person’s most vital functions; therefore; the brain protects itself with a tough-to-penetrate boundary called the blood-brain barrier (BBB).
However, there are times when disease treatments need to get beyond the BBB to treat an illness that has invaded the brain. Hong Chen, Ph.D., assistant professor of biomedical engineering and radiation oncology at Washington University in St. Louis; explained that FUS-BBBD is achieve by concentrating or focusing; sound waves emit from a device called a transducer; to a specific location. Chen compared the concept to focused sunlight passing through a magnifying glass to a localized spot.
In FUS, the ultrasound waves are concentrated with specially design ultrasound generators and help focus the BBB opening at a specific brain location. Microbubbles can be injected into the bloodstream to amplify the effects of the ultrasound waves on the blood vessels; thereby opening the BBB in a localized spot.
Different biological structures
Researchers can store drugs for treatments inside the microbubbles. The pressure generated by ultrasound pulses can cause the microbubbles in the bloodstream to expand, contract, and eventually burst. When the microbubbles break in BBB blood vessels, the pressure created gently massages the blood vessels and makes them permeable to drugs injected into the bloodstream or carried by the microbubbles.
To track the amount and location of the drug delivered by FUS-BBBD, scientists labeled nanoparticles with a radioactive tracer and injected them into the blood circulation following FUS treatment. Then; positron emission tomography (PET) and computed tomography (CT) imaging were employ to measure and visualize the precise amount and location of the nanoparticles in the brain, respectively.
“The caveats to using PET/CT imaging are the associated exposure to radioactivity and higher costs;” explain Chen. The team wanted to find a cheaper, safer way to monitor where drugs go after they cross the BBB; so they explored a technique termed cavitation dose painting through passive cavitation imaging (PCI).
Radioactivity and higher costs
The study was published in Scientific Reports. Yaoheng Yang; the lead author of the study and a graduate student at Washington University, explained that PCI monitors the behavior of microbubbles in the ultrasound field and doesn’t rely on a radioactive particle like PET/CT imaging. .