NON-INVASIVE and continuous monitoring of cerebral blood flow is now possible with a conformal ultrasound patch designed for hands-free volumetric imaging. Accurate and continuous monitoring of cerebral blood flow is crucial for both clinical neurocritical care and fundamental neurovascular research. Traditional methods, such as Transcranial Doppler (TCD) ultrasonography, have limited accuracy when measuring 3D vascular networks, and are impractical for long-term use due to the hands-on approach required by a technician. Therefore, researchers developed a hands-free, comfortable wearable patch that can be worn continuously during a patient’s hospital stay.
The patch operates using 2 MHz ultrasound waves, which significantly reduce attenuation and phase aberration caused by the skull. Additionally, the patch features a copper mesh shielding layer that ensures conformal contact with the skin, enhancing the signal-to-noise ratio by 5 dB. To achieve 3D monitoring, the patch employs ultrafast ultrasound imaging based on diverging waves, which accurately renders the circle of Willis in 3D, minimizing human errors during examinations. Custom algorithms are used to reconstruct 3D information such as the size, angle and position of the brain’s major arteries. Additionally, focused ultrasound waves allow continuous recording of blood flow spectra at specific locations.
The accuracy of the patch was validated through a comparison with a conventional TCD probe in a study involving 36 participants engaged in activities affecting blood flow, such as hand-gripping, breath-holding and reading. The results demonstrated mean differences and standard deviations of -1.51 ± 4.34 cm/s, -0.84 ± 3.06 cm/s, and -0.50 ± 2.55 cm/s, respectively, which closely matched the results obtained with a conventional TCD probe. Furthermore, the patch identified cascades of intracranial B waves during drowsiness within a 4-hour recording period.
This conformal ultrasound patch represents a significant advancement in cerebral blood flow monitoring, offering a more accurate and practical solution for clinical and research applications. In summary, the conformal ultrasound patch improves upon traditional TCD ultrasonography by providing a non-invasive, hands-free method for continuous and accurate 3D imaging of cerebral blood flow. Its design enhancements and operational capabilities make it a valuable tool for neurocritical care and neurovascular research.
Katrina Thornber, EMJ
Reference
Zhou S et al. Transcranial volumetric imaging using a conformal ultrasound patch. Nature. 2024;629:810-8.
