Bhavya R. Shah, MD, on Advanced MRI Techniques for Transcranial HIFU Targeting
In this podcast, Dr Shah discusses the imaging and treatment modalities he and his colleagues reviewed in their recent article, "Advanced MRI Techniques for Transcranial High Intensity Focused Ultrasound Targeting," which was published in the journal Brain.
*If you have a question for Dr Shah, you may reach him at bhavya.shah@UTSouthwestern.edu.
- Shah BR, Lehman VT, Kaufmann TJ, et al. Advanced MRI techniques for transcranial high intensity focused ultrasound targeting. Published online June 15, 2020. doi:10.1093/brain/awaa107
Bhavya R. Shah, MD, is an assistant professor of Radiology in the Neuroradiology Section; assistant professor of Neurosurgery; assistant professor in the Advanced Imaging Research Center in the Department of Radiology; and co-director of the Focused Ultrasound Lab at the University of Texas Southwestern.
Christina Vogt: Hello everyone, and welcome back to another podcast. I’m Christina Vogt, associate editor of the Consultant360 Specialty Network. Today, I’m joined by Dr Bhavya Shah, from the University of Texas Southwestern Medical Center. Thank you for joining me today, Dr Shah.
Today, we will be discussing Dr Shah’s recent review, “Advanced MRI techniques for transcranial high intensity focused ultrasound targeting.” So first, what prompted you to perform this review?
Dr Shah: Thanks for the question. I'm leading the efforts at UT Southwestern to develop our clinical neuroscience, MRI-guided, high-intensity focused ultrasound program. The FDA-approved indications for HIFU are essential tremor and tremor in the setting of Parkinson disease. Currently, the target for both of these treatments is the ventral intermediate nucleus, the VIM of the thalamus. A major limitation of targeting the VIM is that you can't see it on standard high-resolution MRI sequences. So, to target the VIM landmark or atlas-based methods have been used. The issue with this is that every brain is slightly different, or if there is another intracranial pathology, the VIM may not be where you expect it to be.
So, our team, in collaboration with Dr Tim Kaufmann's group at the Mayo Clinic in Rochester, have been working on optimizing a few alternate methods to directly visualize the VIM. Our group and others have shown that by using advanced imaging techniques to target the VIM, we can reduce adverse offsite effects. Additionally, there are ongoing clinical trials to determine if it is safe to do the procedure bilaterally. Historically, bilateral surgical thalamotamies left people with speech and motor deficits. I think using advanced MRI sequences to target the VIM may reduce those adverse effects and improve patient outcomes.
In short, we now have transcranial focused ultrasound, a very powerful, noninvasive, image-guided procedure. By combining it with advanced MRI sequences, we can expand the horizon of what we can do with it. For example, various groups are looking at treating other symptoms in Parkinson disease. Our group is also looking at treating other neurodegenerative diseases like Alzheimer disease.
Christina Vogt: Could you give an overview of the new advanced MRI techniques you discussed your review and what they add to the landscape of imaging and treatment modalities for essential tremor and Parkinson disease?
Dr Shah: Yes, sure. The methods described are quantitative susceptibility mapping, which creates contrast in the image by detecting distortions in the magnetic field caused by substances such as iron or blood, and fast gray matter acquisition T1 inversion recovery, which works by inverting the white matter signal so it's dark, and the gray matter signal so it's white, in order to provide greater contrast for the deep brain nuclei. I think the current winner is diffusion tractography because with it, we can create a map of white matter connections between nuclei. So, instead of treating a nucleus, we can start to think of ways to disconnect a white matter tract.
Christina Vogt: What is the next step in terms of future research in this area?
Dr Shah: So, the use of tractography to target the aim for HIFU or DBS has become popular with some groups. I think validating this technology and treating patients will be really important. With the launch of bilateral procedures, I think precise targeting will help overcome a lot of the historical comorbidities and complications. For us, we will be doing a clinical trial with the Mayo Clinic in Rochester to see how these techniques improve patient outcomes. I also think this is an opportunity to create better ways to treat neurological and psychiatric diseases. I'm the co-director of the Focused Ultrasound Lab at UT Southwestern, and there are lots of neurologic focused ultrasound applications on the horizon in neuro-oncology, neurodegenerative diseases, and genetic neurologic diseases. I think using advanced MRI sequences to better delineate and target tissue will benefit patients.
Christina Vogt: And lastly, what key takeaways do you hope to leave with neurologists on this topic?
Dr Shah: Transcranial focused ultrasound is a noninvasive procedure that is currently FDA-approved for the treatment of essential tremor and tremor in the setting of Parkinson disease. There are no incisions, no anesthesia, and no implantable devices. Clinical trials have shown that the procedure is well-tolerated and is efficacious. By using advanced MRI methods for targeting, we can create a precision medicine model for our patients and reduce adverse effects and improve patient outcomes.
I think it is the beginning of the future of noninvasive therapies for other neurologic and psychiatric diseases. If I can help answer any questions, anyone can feel free to reach out to me at my email address [Bhavya.Shah@UTSouthwestern.edu]. Thank you.
Christina Vogt: Thanks again for joining me today, Dr Shah.
Dr Shah: Thank you so much for the opportunity to show the implications of this exciting technology.
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