The Neurovascular Response is Attenuated by Focused Ultrasound–mediated Disruption of the Blood-brain Barrier
A Boston research group led by Nathan McDannold, PhD, sought to determine whether using focused ultrasound to disrupt the blood-brain barrier (BBB) altered the neurovascular response or produced secondary effects (besides the desired effect of increasing vascular permeability). To measure changes, the group used functional MRI to study BBB opening in the right somatosensory cortex in the brains of rats. What changes were found when measuring the blood oxygen level—dependent signal and cerebral blood flow measurements? Did the procedure hinder the brain’s ability to increase blood flow to the region?
MR-guided Focused Ultrasound Facilitates Sonodynamic Therapy with 5-Aminolevulinic Acid in a Rat Glioma Model
While testing ideas for treating glioblastoma brain tumors, scientists at Sunnybrook Research Institute have taken an important step toward determining whether focused ultrasound—based activation of 5-aminolevulinic acid HCl (5-ALA), a sonosensitizer agent, might have the ability to control tumor growth and prolong survival. The use of focused ultrasound with a sonosensitizing agent is called sonodynamic therapy, and the idea is to use the energy to activate a therapeutic agent that can produce a cancer-killing “cytotoxic” effect at the site of the tumor. In this study, the group led by Kullervo Hynynen, PhD, used various parameters to activate 5-ALA in a rat model of glioblastoma multiforme and demonstrated that low power focused ultrasound (which is easier and safer to deliver) is sufficient to produce an effect. Importantly, 5-ALA is already FDA approved for use in glioblastoma as a tumor visualization tool, paving the way for rapid clinical translation. Was the team able to determine how to achieve a measurable difference in tumor growth response and survival after treatment?