Intravenous infusions rely on the bloodstream to carry drugs to where they are needed. Normally, a material such as a chemotherapy drug crosses into a tissue on the principle of concentration equalization ?the material diffuses from an area of high concentration to one of low concentration until the concentrations become equal all around. However, in some cancers, even though the material "wants" to spread out evenly, fluids inside the tumor may be exerting pressure to prevent this. When the internal pressure created by these fluids rises above a certain level, it acts as a barrier that keeps drugs and other materials from entering the tumor.
The method the Institute scientists developed can measure, with a non-invasive MRI scan, whether the fluid pressure in cancer tissues is at levels that could render chemotherapy ineffective. Their research, which led to the method, was done with MRI equipment similar to that found in hospitals and clinics. A contrast agent often employed in MRI was used as a stand-in for chemotherapy drugs, and this material was injected into special mice with different cancerous growths. The team created computer algorithms (instructions for computers) that allowed them to verify the connection between the amount of material that found its way into the growth and the pressure o
Source:American Committee for the Weizmann Institute of Science