Novel, near-infrared spectroscopic, label-free, techniques to assess bone abnormalities such as Paget's disease, osteoporosis and bone fractures

Abstract

Near- infrared (NIR) light with wavelengths from 650 nm to 950 nm (known as the first NIR window) has conventionally been used as a non-invasive technique that can reach deeper penetration depths through media than light at shorter wavelengths. Recently, several novel, NIR, label-free, techniques have been developed to assess Paget’s disease of bone, osteoporosis and bone microfractures. We designed a Bone Optical Analyzer (BOA) which utilizes the first window to measure changes of Hb and HbO2. Paget’s disease is marked by an increase in vascularization in bones, and this device can enable easy diagnosis and more frequent monitoring of the patient’s condition, without exposing him to a high cumulative dose of radiation. We have also used inverse imaging algorithms to reconstruct 2D and 3D maps of the bone’s structure. This device could be used to assess diseases such as osteoporosis. Using 800 nm femtosecond excitation with two-photon (2P) microscopy, we acquired 2PM images of the periosteum and spatial frequency spectra (based on emission of collagen) from the periosteal regions. This technique can provide information on the structure of the periosteum and can detect abnormalities which may be an indication of disease. Most recently, we showed that longer NIR wavelengths in the second and third NIR windows (1100 nm-1350 nm, 1600 nm-1870 nm), could be used to image bone microfractures. Use of NIR light could allow for repeated studies in patients with diseases such as Paget’s and osteoporosis quickly and non-invasively, and could impact the current management for these diseases.