Ruth A. Mendonsa
Researchers at the University of Pennsylvania are focusing on the application of near-IR light to probe the oxygenation states of tissues for diagnostic and functional imaging purposes. As part of a breast cancer study, the team is using a technique that involves the automatic repositioning of light to multiple locations. A fiber optic switch from DiCon Fiberoptics Inc. is playing an important role in this effort.
Leading the group are Britton Chance, head of near-IR light application research at the university, and Mitchell Schnall, head of magnetic resonance imaging breast cancer research at the Hospital of the University of Pennsylvania. Their goal is to acquire simultaneous near-IR images and magnetic resonance images to increase the specificity of the magnetic resonance examination in breast cancer cases and to develop the optical method as a stand-alone breast cancer screening and diagnostic technique.
In studies of phantoms or tissues, researchers typically use stepper motors to position the light-delivery source fiber in multiple locations.
Because of the incompatibility of the ferric materials used in these devices with the magnetic resonance examination, as well as the examination time limits and the limited space inside the magnetic bore, simultaneous measurements are not feasible with stepper motors.
The researchers accomplished their goal with the aid of DiCon Fiberoptics' GP700 fiber optic switch. Their near-IR imager is a multichannel time-resolved system that employs two laser diodes at 780 and 830 nm and eight GaAs photomultiplier tubes as detectors.
Away from the magnet
To keep the instruments away from the magnetic field, they use 10-m-long optical fibers that are attached to special breast compression plates, which also hold the magnetic resonance coils. The GP700 directs the light to the different positions of the breast automatically with almost instantaneous switching time and low light loss. The team chose the GP700 because of its flexibility and also for the service and technical support DiCon Fiberoptics provided.
PhD candidate Vasilis Ntziachristos, who is responsible for this project, said the team is in the clinical stage with human subjects and that the results look very promising.