Bone allografts are used to replace the tissue surgically removed in cases of osteosarcoma, a malignant bone tumor that forms during adolescence, and other bone cancers. The allografts are taken from the sterilized bone tissue of cadaveric donors, and sometimes fail to integrate into the healthy tissue once implanted. Currently, researchers from both Dartmouth and the University of Michigan Ann Arbor are working to develop noninvasive methods for examining the early success of these transplants using medical optics.
Jennifer Lynn-Demers, a fourth year graduate student in Dartmouth’s Optics in Medicine Laboratory, is developing a noninvasive diffuse Raman tomographic methodology for evaluating the state of bone allografts in a rat model, and other problems in bone repair and healing. Based upon Raman scattering—the inelastic scattering of a photon discovered by Indian scientist Sir. C. V. Raman in 1923—Raman tomography is a method of optical imaging that examines a number of low-frequency modes in a system to analyze the vibrational properties of matter. While Demers’ research is based out of Hanover, she conducted doctoral research with Professor Michael Morris for two months at the University of Michigan Ann Arbor in 2011.
To develop a Raman-based imaging machine capable of analyzing bone structures, Jenn is modifying a fluorescence imaging system designed by Scott Davis, a Research Scientist in the Optics in Medicine Laboratory who received his PhD from the Thayer School of Engineering. Unlike fluorescence and Magnetic Resonance Imaging (MRI), both of which analyze the properties of a tissue on a subatomic level, Raman spectroscopy measures tissue on the molecular level, thus enabling Demers’ machine to profile the molecular and chemical structures of a bone.
The funding from NIH seeks to develop a new type of imaging technology that provides chemical-specific information. To develop this new imaging system, prototypes are tested on tissue phantoms and rat hind limbs that accurately simulate bone and tissue geometry. As these imaging technologies are created, new mathematical methodologies will also be developed to extract data sets from the remitted Raman-scattered light.
Currently, Demers’ Raman-based imaging machine is being calibrated on tissue phantoms and lab rats, and has not actually been used to analyze bone structures in vivo. However, when this machine is used in a clinical setting, it will provide practitioners with essential information regarding bone health in a non-invasive manner.