Historical Milestones in Neurophotonics
本文摘选自书籍《Neurophotonics and Brain Mapping》，仅为学习使用，未经许可，请勿转发。
NEAR-INFRARED SPECTROSCOPY AND IMAGING
The spectroscopy system was pioneered at Cambridge University (Hartridge and Roughton, 1923; Roughton and Millikan, 1936). Since tissue is typically opaque, light absorption is disrupted by scat-tering. In 1950, Britton Chance invented the “double beam spectrometer” using two wavelengths in the visible region with a small spectral interval to eliminate scattering effects (Chance, 1951). The first demonstration of near-infrared (NIR) light with human tissue in vivo was reported by Franz Jobsis in 1977 (Jobsis, 1977). Since then, many papers have been published on the use of NIR spec-troscopy (NIRS) for brain mapping. Many researchers use continuous-wave (CW) technology, as the system is simple, has low cost, and is robust (Chance et al., 2005). Time-resolved spectroscopy provided a solution for the absolute quantification of chemical concentrations in tissues (Chance et al., 1988; Patterson et al., 1989). Alternatively, frequency-domain NIRS may be also used for quantization (Fishkin and Gratton, 1993; Madsen et al., 1994; Chen et al., 2003). Since Seiji Ogawa’s discovery in the early 1990s that signal changes associated with deoxyhe-moglobin in NMR can detect brain cognition (Ogawa et al., 1990), researchers have been interested in using NIR light to detect brain function (Chance et al., 1993; Villringer and Chance, 1997; Hoshi et al., 2003). NIRS may quantify the concentrations of both Hb and HbO2, thereby revealing the blood volume and oxygenation saturation changes associated with various brain functions. NIRS may be extended to imaging mode by employing multiple source-detector channels. Images can be formed using back-projection and interpolation algorithms, sometimes referred to as diffuse optical topography, which may provide an estimate of the 2D spatial distribution of the optical properties of tissues (Hielscher et al., 2002). Another approach is to perform 3D tomographic reconstruction, which is typically referred to as diffuse optical tomography (DOT). DOT is similar to x-ray CT and involves image reconstruction by solving the inverse problem (Arridge, 1999). NIR imaging has found extensive applications in clinical settings (Hillman, 2007; Wolf et al., 2007). One major research area involves the elucidation of how the brain functions. Optical imaging offers the unique capability to noninvasively monitor functional activations in vivo without disturb-ing the organ. Various applications such as visual responses (Takahashi et al., 2000; Zeff et al., 2007), somatosensory responses (Becerra et al., 2009), auditory responses (Sato et al., 1999), lan-guage stimuli (Watanabe et al., 1998; Pena et al., 2003), and problem solving (Chance et al., 2007) have been explored. Another important area for optical brain imaging is to diagnose and monitor conditions such as stroke (Kirkpatrick et al., 1998; Durduran et al., 2009), epilepsy (Watanabe et al., 2002), brain injury (Kim et al., 2010), and post-traumatic stress disorder (Matsuo et al., 2003). Optical techniques are well suited for the early detection of hemorrhage (Stankovic et al., 2000) and to discriminate between ischemic and hemorrhagic stroke, which leads to improved management of therapeutics for patients (Intes and Chance, 2005). Chapters 2 through 5 review the applications of fNIRS for pain management and neurological disease monitoring. Chapters 15 through 17 review the application of optical imaging that is based on ultraviolet (UV), visible, and infrared (IR) light for neurosurgical guidance.