Near‐Infrared Diffuse Optical Tomography

Abstract

Diffuse optical tomography (DOT) is emerging as a viable new biomedical imaging modality. Using near-infrared (NIR) light, this technique probes absorption as well as scattering properties of biological tissues. First commercial instruments are now available that allow users to obtain cross-sectional and volumetric views of various body parts. Currently, the main applications are brain, breast, limb, joint, and fluorescence/bioluminescence imaging. Although the spatial resolution is limited when compared with other imaging modalities, such as magnetic resonance imaging (MRI) or X-ray computerized tomography (CT), DOT provides access to a variety of physiological parameters that otherwise are not accessible, including sub-second imaging of hemodynamics and other fast-changing processes. Furthermore, DOT can be realized in compact, portable instrumentation that allows for bedside monitoring at relatively low cost. In this paper, we present an overview of current state-of-the -art technology, including hardware and image-reconstruction algorithms, and focus on applications in brain and joint imaging. In addition, we present recent results of work on optical tomographic imaging in small animals.

Frequency Domain Optical Tomography Based on the Equation of Radiative Transfer

“…Main domains of application of the proposed method will be functional imaging of rheumatoid arthritis of human finger joints and small animal imaging [30,32], where the diffusion equation typically fails to generate accurate forward predictions. Extensive numerical reconstructions in practically relevant geometries for these applications and based on possibly multifrequency experimental data will be performed in the near future.…”

“…While this is often the case in biomedical applications there remain many important applications, for which reconstructions based on the ERT are needed. Some examples include brain imaging, where the presence of low-absorbing and low-scattering cerebrospinal fluid leads to nondiffusive light propagation; imaging of joints, where clear synovial fluid has the same effects as cerebrospinal fluid in the brain; and small animal imaging, where small object dimensions (1-2 cm in diameter) invalidate the classical diffusion approximation [30,32]; see, however, [6,8] for ways to generalize the diffusion equation in certain situations.…”

Notice of Violation of IEEE Publication Principles: Peptide coated quantum dots for biological applications

“…In the visible range, fluorescence imaging is limited by the autofluorescence in the visceral tissues, and scattering and absorption in the skin. However, in the nearinfrared (NIR) region, between 700 and 900 nm, hemoglobin absorption drops, and water absorption is low [7], [9], [10]. This increases the transmission of light into and out of deep tissue, thereby improving sensitivity.…”

The role of photodynamic therapy (PDT) physics

“…Diffuse optical tomography ͑DOT͒ is a viable new biomedical imaging modality. 36 This technique images the absorption and scattering properties of biological tissues and has been explored as a diagnosis tool in breast, [37][38][39][40][41][42] brain, 43,44 and bones and joints. 45 Some preliminary attempts have been made to perform DOT for prostate.…”