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Is there any chance that these techniques could be equally effective for other cancers? For example Liver, Kidney, Lung cancers?

ceejayoz 7y ago
My understanding is prostate cancer has a particular need for this sort of less invasive approach, as surgical procedures there tend to damage the sensitive equipment nearby - incontinence and impotence are common side effects of it, and often not worth it when prostate cancer tends not to be deadly. Things like liver cancer you're probably better off just doing a surgery for, as you'll have more chance of getting it all, spotting metastasized offshoots, etc., and it's fairly accessible.
HorizonXP 7y ago
Yes, very much so. Ultrasound in medicine is very cool technology. Obviously many of us have experience with ultrasound imaging, which has revolutionized medicine in a number of ways. But we also learned that if you crank up the amplitude and frequency, you can heat the tissue. Our research group was one of several that figured out that you can use MRI-based thermometry to measure that heating, and use it as the input to your control loop. Then, it's a matter of adjusting the frequency, amplitude, and positioning (i.e. in this case, rotation) to "paint" your heat pattern. Thus, at least at our site, it was used to develop treatments for uterine fibroids, some types of breast cancer, and some types of brain cancer (using transcranial ultrasound, which is much harder to do because you have to go through bone and adjust for that medium). Generally, areas that you can reach from the skin and/or with a special probe, are potential treatment targets. Lung cancers are hard to treat with ultrasound, for a few reasons. The biggest is that it moves, which makes it hell for the MRI and system as a whole to keep up without hitting unwanted areas. The other is that ultrasound doesn't travel well through air. For ultrasound ablation to work, you need a good conduction interface. That's why ultrasound technicians slather that clear gel on you when they're imaging you. It's possible to do in the lungs, just exceedingly difficult. It's unlikely that someone will commercialize something there. The liver and kidneys won't be targeted either because the only way to reach them is by performing an incision. You might as well use other techniques like laparoscopy.
- _Microft 7y ago
  Would transcranial ultrasound have the problem of unwanted hotspots because of reflections and a focusing effect of the curvature of the skull? I would assume that this could only be done by scanning the head with a MRI, modelling the tissues in detail, simulating the process and then constructing a wave front from many emitters that does what one wants. Ideally all of that in real time as I guess the heating process will change the properties of the treated tissue in a way that would require it.
  - HorizonXP 7y ago
    Precisely. See Ultrasound attenuation coefficient (https://en.wikipedia.org/wiki/Attenuation#Attenuation_coefficient https://en.wikipedia.org/wiki/Attenuation#Attenuation_coeffi...) You'll note that it's measured in dB/(MHz-cm), and that soft tissue is 0.5, while bone is 6.9. Just like light, anytime ultrasound hits an interface, there are reflections and refractions. Furthermore, since bone attenuates ultrasound so much, you have to increase your amplitude greatly (and even more so with higher frequencies) in order to get enough thermal energy to be deposited at your target. If you don't do it right, you can create dangerous hotspots at the bone-tissue interface, and you can also deposit energy where you didn't intend to. Given that ultrasound therapy intends to be more precise than other techniques, you're kind of defeating the purpose! Edit: in response to your edit, yes that's exactly what they do. They create an array of transmitters to be able to precisely target various locations within the skull. It wasn't my area of research, but I'm pretty sure they used them to create interference patterns as well, so many emitters were activated to work in concert to target one area. See this image: https://sunnybrook.ca/uploads/1/_research/about/fus/3-ultrasoundbraindevice.jpg https://sunnybrook.ca/uploads/1/_research/about/fus/3-ultras...
  - beering 7y ago
    Here's an application of ultrasound towards essential tremors that is already being used on people! https://www.usnews.com/news/health-news/articles/2019-11-20/ultrasound-may-ease-common-form-of-hand-tremor https://www.usnews.com/news/health-news/articles/2019-11-20/... Transcranial ultrasound + monitoring via MRI. Requires a rock-solid transmitter clamped on the skull.
js2 7y ago
A similar treatment is available for uterine fibroids (benign smooth muscle tumors, which affect many to most women by age 50): https://www.uclahealth.org/fibroids/mr-guided-focused-ultrasound https://www.uclahealth.org/fibroids/mr-guided-focused-ultras...

ceejayoz 7y ago

My understanding is prostate cancer has a particular need for this sort of less invasive approach, as surgical procedures there tend to damage the sensitive equipment nearby - incontinence and impotence are common side effects of it, and often not worth it when prostate cancer tends not to be deadly. Things like liver cancer you're probably better off just doing a surgery for, as you'll have more chance of getting it all, spotting metastasized offshoots, etc., and it's fairly accessible.

HorizonXP 7y ago

Yes, very much so. Ultrasound in medicine is very cool technology. Obviously many of us have experience with ultrasound imaging, which has revolutionized medicine in a number of ways. But we also learned that if you crank up the amplitude and frequency, you can heat the tissue. Our research group was one of several that figured out that you can use MRI-based thermometry to measure that heating, and use it as the input to your control loop. Then, it's a matter of adjusting the frequency, amplitude, and positioning (i.e. in this case, rotation) to "paint" your heat pattern. Thus, at least at our site, it was used to develop treatments for uterine fibroids, some types of breast cancer, and some types of brain cancer (using transcranial ultrasound, which is much harder to do because you have to go through bone and adjust for that medium). Generally, areas that you can reach from the skin and/or with a special probe, are potential treatment targets. Lung cancers are hard to treat with ultrasound, for a few reasons. The biggest is that it moves, which makes it hell for the MRI and system as a whole to keep up without hitting unwanted areas. The other is that ultrasound doesn't travel well through air. For ultrasound ablation to work, you need a good conduction interface. That's why ultrasound technicians slather that clear gel on you when they're imaging you. It's possible to do in the lungs, just exceedingly difficult. It's unlikely that someone will commercialize something there. The liver and kidneys won't be targeted either because the only way to reach them is by performing an incision. You might as well use other techniques like laparoscopy.

_Microft 7y ago
Would transcranial ultrasound have the problem of unwanted hotspots because of reflections and a focusing effect of the curvature of the skull? I would assume that this could only be done by scanning the head with a MRI, modelling the tissues in detail, simulating the process and then constructing a wave front from many emitters that does what one wants. Ideally all of that in real time as I guess the heating process will change the properties of the treated tissue in a way that would require it.
- HorizonXP 7y ago
  Precisely. See Ultrasound attenuation coefficient (https://en.wikipedia.org/wiki/Attenuation#Attenuation_coefficient https://en.wikipedia.org/wiki/Attenuation#Attenuation_coeffi...) You'll note that it's measured in dB/(MHz-cm), and that soft tissue is 0.5, while bone is 6.9. Just like light, anytime ultrasound hits an interface, there are reflections and refractions. Furthermore, since bone attenuates ultrasound so much, you have to increase your amplitude greatly (and even more so with higher frequencies) in order to get enough thermal energy to be deposited at your target. If you don't do it right, you can create dangerous hotspots at the bone-tissue interface, and you can also deposit energy where you didn't intend to. Given that ultrasound therapy intends to be more precise than other techniques, you're kind of defeating the purpose! Edit: in response to your edit, yes that's exactly what they do. They create an array of transmitters to be able to precisely target various locations within the skull. It wasn't my area of research, but I'm pretty sure they used them to create interference patterns as well, so many emitters were activated to work in concert to target one area. See this image: https://sunnybrook.ca/uploads/1/_research/about/fus/3-ultrasoundbraindevice.jpg https://sunnybrook.ca/uploads/1/_research/about/fus/3-ultras...
- beering 7y ago
  Here's an application of ultrasound towards essential tremors that is already being used on people! https://www.usnews.com/news/health-news/articles/2019-11-20/ultrasound-may-ease-common-form-of-hand-tremor https://www.usnews.com/news/health-news/articles/2019-11-20/... Transcranial ultrasound + monitoring via MRI. Requires a rock-solid transmitter clamped on the skull.

js2 7y ago

A similar treatment is available for uterine fibroids (benign smooth muscle tumors, which affect many to most women by age 50): https://www.uclahealth.org/fibroids/mr-guided-focused-ultrasound https://www.uclahealth.org/fibroids/mr-guided-focused-ultras...