Therapeutic focused ultrasound and tissue fields

5 problems

• Transcranial focusing without a prior CT scan

  Open

  The skull bends and absorbs sound unevenly, smearing the focus inside the head. Correcting for it currently needs an x-ray scan of the skull.

• A dose quantity for microbubble-mediated barrier opening

  Open

  Injected gas bubbles made to oscillate by ultrasound can temporarily open the barrier that keeps drugs out of the brain. There is no agreed measure of how much of this was delivered.

• Predicting and controlling histotripsy bubble clouds

  Open

  Very short, very intense sound pulses tear tissue apart mechanically by creating clouds of bubbles. Where and when those clouds form is only partly predictable.

• How focused ultrasound changes neural activity

  Contested

  Low-intensity sound aimed at the brain changes how neurons fire, and the reason is disputed. Part of the measured effect may come from the subject simply hearing the pulse.

• Real-time tissue thermometry without magnetic resonance

  Open

  Heating treatments need to know the temperature at the focus as it rises, which today requires an expensive magnetic resonance scanner.