Medical Physics Seminar – Monday, April 3, 2017
Neurosurgical Device Tracking with Real-time MRI in Preclinical Gene Therapy and Stem Cell Therapy Experiments
Miles Olsen (student of Dr. Walter Block)
Research Assistant, Dept of Medical Physics, UW-School of Medicine & Public Health, Madison, WI - USA
Preoperative MR images are often used in conventional stereotactic operating rooms to guide neurosurgical devices to precise anatomical locations. In the stereotactic OR, the preoperative MRI is coregistered with optical device tracking which yields updates about the device orientation at video frame rates (30+ f/s). We present an intraoperative MR platform that goes beyond anatomical guidance to provide pre-surgical planning, device guidance, drug distribution monitoring and control, and validation of the delivered therapy.
Although MRI is inherently a slow imaging modality, we have developed real-time, interactive MR device guidance techniques that enable OR-like device tracking performance while operating inside the bore of a conventional diagnostic MRI scanner. The performance increases are derived from using a priori information to model and detect the device orientation rather than image the entire device at high resolution. At five updates per second, our approach is much more interactive than previous MRI-based tracking, which took several seconds to minutes per update.
In collaboration with Ned Kalin’s lab, our technique has been applied to deliver gene therapies in 16 survival surgeries to study the neural circuitry of anxiety in non-human primates. We have also employed this technique to perform 12 stem cell transplantation surgeries in survival NHPs with Marina Emborg’s lab, to investigate treatments for Parkinson's disease. We demonstrate the value of interactive MR device guidance, real-time monitoring, and validation of the delivered agents.
Radiation Induces Prompt Metabolic Fluxes in Cancer: An In-vitro Demonstration
David Campos (student of Dr. Michael Kissick)
Research Assistant, Dept of Medical Physics, UW-School of Medicine & Public Health, Madison, WI - USA
Radiosensitivity is a key factor in the efficacy of radiotherapy and may indeed be affected by radiation therapy itself within the time scale of a treatment fraction. In this work, we present measurements of the changes in metabolic fluxes in live cells within tens of minutes of large doses of radiation. We hypothesize that these metabolic fluxes may be a mechanism by which these particular cells protect themselves against radiation within the timescale of a typical fraction. This observation is important for severely hypofractionated radiation therapy. It may also play a role in better than expected clinical outcomes from large doses of radiation.