Introduction
Transcranial ultrasound has emerged as a cutting-edge technology with the potential to non-invasively stimulate specific brain regions, promising new treatments for neuropsychiatric disorders. Despite its potential, the application of focused ultrasound through the skull poses challenges such as beam defocusing and attenuation. Addressing these issues, researchers at Brigham & Women’s Hospital, Harvard Medical School, led by Spencer T. Brinker, have developed a novel method called virtual brain projection to evaluate the behavior of trans-skull ultrasound beams from single-element piezoelectric transducers.
The study published in “Ultrasound in Medicine & Biology” in 2019 utilizes virtual brain projection to overlay magnetic resonance images of the brain onto ex vivo human skulls. This approach aids in targeting during pressure field mapping with the transducer. Real-time tracking of transducer, skull, and hydrophone positions is achieved using a stereoscopic navigation camera and 3-D Slicer software. The aim is to precisely focus the ultrasound on regions such as the left dorsolateral prefrontal cortex, left hippocampus, and cerebellar vermis, which are implicated in non-invasive brain stimulation treatments for neuropsychiatric disorders.
Advantages of Virtual Brain Projection
Virtual brain projection offers several benefits in the field of transcranial ultrasound.
1. Enhanced Accuracy:
The technique provides a high degree of accuracy in targeting, vital for the treatment’s effectiveness and minimizing off-target effects. Moreover, this accuracy is essential for research and clinical applications where precise stimulation is required.
2. Operator Reliability Assessment:
Virtual brain projection enables the assessment of operator positioning reliability, ensuring consistent results across different users and sessions.
3. Beam Behavior Understanding:
Understanding intracranial beam behavior is critical for safe and effective ultrasound application. This method aids in visualizing and quantifying focal-zone distortion and attenuation due to the skull, thus improving treatment protocols.
4. Computational Model Validation:
This approach supports the validation of computational models, which are indispensable tools for predicting transcranial ultrasound effects and optimizing treatment parameters without invasive measurements.
Challenges and Future Directions:
Despite the advantages, the method has some limitations and areas for further research. Human studies are needed to confirm the findings from ex vivo experiments. Developing more sophisticated computational models and the use of advanced imaging techniques can enhance the accuracy and reliability of brain targeting with ultrasound.
Conclusion:
The virtual brain projection method marks a significant step forward in the application of transcranial ultrasound, bridging the gap between theoretical models and real-world clinical practice. The work by Spencer T. Brinker and colleagues paves the way for more precise and reliable ultrasound therapies for brain disorders.
Keywords
1. Virtual Brain Projection
2. Transcranial Ultrasound
3. Focused Ultrasound
4. Neuropsychiatric Treatments
5. Single-Element Piezoelectric Transducers
References
1. Brinker, S.T., Preiswerk, F., McDannold, N.J., Parker, K.L., & Mariano, T.Y. (2019). Virtual Brain Projection for Evaluating Trans-skull Beam Behavior of Transcranial Ultrasound Devices. Ultrasound in Medicine & Biology, 45(7), 1850–1856. https://doi.org/10.1016/j.ultrasmedbio.2019.03.009
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DOI: 10.1016/j.ultrasmedbio.2019.03.009