Scientists at Duke University have developed an ultrafast optoacoustic imaging system that can capture the functional and molecular changes that occur in major brain disorders.
Imaging techniques that provide real-time, detailed information related to complex cerebrovascular networks are important for a better understanding of neurovascular disorders such as stroke, dementia, and acute brain injury.
Positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) provide decent images, but have poor spatial resolution, difficulty distinguishing adjacent body structures, and poor temporal resolution. , it takes a long time to get the measurements. and build the image.
Similarly, optical microscopy produces high-resolution images, but is hampered by slow imaging speed and insufficient penetration depth. Microbubble-enhanced ultrasound provides high resolution and deep penetration, but lacks functional sensitivity.
An alternative method of imaging, photoacoustic microscopy (PAM), uses pulses of laser light fired into the organ. The pulses generate ultrasound waves, which are captured to form an image.
Importantly, PAM uses laser light of different wavelengths and can target specific structures in the body down to the molecular level. This means that PAM can measure important hemodynamic parameters such as blood oxygenation, blood flow, and oxygen metabolic rate.
A drawback of PAM is that scanning is slow. However, this problem was solved by researchers at the Duke Institute for Brain Science (DIBS) with the development of his Ultrafast Functional Photoacoustic Microscope (UFF-PAM), which is twice as fast as his existing PAM system. rice field.
UFF-PAM enables imaging of the brain microvasculature and works with a wide field of view and high spatial resolution that other imaging techniques lack.
In proof-of-concept experiments, Duke researchers used UFF-PAM to successfully capture induced hypoxia, sodium nitroprusside-induced hypotension, and the hemodynamic response of the mouse brain to stroke. UFF-PAM was able to capture rapid changes throughout the brain in real time.
Stroke experiments had unexpected consequences. UFF-PAM detects diffuse depolarization (SD) waves emanating from the stroke area across the brain, causing narrowing of blood vessels (vasoconstriction) as they spread. SD waves are of great interest to researchers and scientists because their function is poorly understood.
“SD waves can indicate the severity of the injury and are a potential diagnostic tool.
“The nature of the waves may also provide clues to the type and extent of brain damage, allowing us to inform and optimize treatments,” Yao said.
Duke’s team is now considering using UFF-PAM to study other diseases. UFF-PAM is currently only used on animals, but Yao has revealed plans to develop a handheld version of his UFF-PAM for use on humans.
The study was published in the journal Light: science and application.
Source: National Institutes of Health
