Clinical feasibility of diffuse optical spectroscopic imaging in sarcoma

Abstract

Sarcomas are broadly defined as cancers that form in the bone, soft tissue, or connective tissue. While they represent only 1% of all cancers in the United States, sarcomas constitute 12% of all childhood cancers. Five-year survival has not changed in over 40 years. The only clinically accepted indicator of pathologic response and disease-free survival is percent tumor-cell necrosis at time of surgery---there are no established prognostic markers before surgery. Unfortunately, 40--70% of patients have a poor pathologic response and attempts to modify treatment to improve their outcomes have been unsuccessful. Diffuse Optical Spectroscopic Imaging (DOSI) is a non-invasive, functional imagining technique that has been previously implemented to predict pathologic response in patients with breast cancer. Specifically, DOSI combines frequency amplitude modulated near-infrared light and broadband continuous wave light to measure quantitative concentrations of oxyhemoglobin, deoxyhemoglobin, water, and lipids. This project developed and validated DOSI as a new non-invasive measurement modality to track treatment for sarcomas. For the first time, the optical properties and functional hemodynamic information of the distal femur, tibia, and humerus were characterized in normal volunteers. DOSI demonstrated the ability to measure optical properties and functional information at several sarcoma locations throughout the course of treatment. It was able to differentiate between healthy and sarcoma tissues within a patient. Improvements made to the instrumentation will facilitate future measurements in this patient population. In the future, DOSI may provide a way to monitor treatment response and improve patient outcomes.