Near‐infrared Spectroscopy, In Vivo Tissue Analysis by

Abstract

Applications of in vivo near‐infrared (NIR) spectroscopy have emerged in various segments of clinical medicine and medical research. Developments in photonics, wireless connectivity, and smart devices that have been spurred on by the communication revolution have set the stage for even more rapid advancement of noninvasive or minimally invasive medical applications of NIR spectroscopy. The goal of this article is to review the current capabilities and limitations of in vivo NIR spectroscopy and highlight the impact of these capabilities and limitations in selected areas where NIR spectroscopy is being used to address clinical problems. The optical properties of tissues are briefly reviewed as these properties largely dictate the feasibility of an in vivo spectroscopic diagnostic approach and constrain the scope of problems that can be tackled using NIR spectroscopy. Some of the more successful applications of NIR spectroscopy in medicine are described. The number and magnitude of confounding factors that confuse in vivo spectroscopy can be daunting to the experimentalist and may represent the largest barrier in transforming in vivo spectroscopic measurements into clinically meaningful and reliable information. In vivo NIR spectroscopy abounds with opportunity and challenge.

Conjugation of Antibodies to Gold Nanorods through Fc Portion: Synthesis and Molecular Specific Imaging

“…Plasmonic gold nanoparticles have become an area of intense focus in biology and medicine due to their small size and intrinsic properties that offer the potential to solve otherwise intractable problems. − In general, plasmonic nanoparticles are intrinsically multimodal contrast agents since they exhibit strong scattering and absorption cross sections as well as nonlinear optical phenomena such as two-photon luminescence and second harmonic generation when excited at the plasmon resonance frequency. Gold nanoparticles provide high contrast in cellular and tissue imaging using confocal reflectance microscopy, , dark-field imaging, ,− two-photon luminescence, − phase-sensitive optical coherence tomography, and photoacoustic imaging. ,,− Furthermore, gold nanoparticles have been used to transform light energy into heat in photothermal therapy of cancer either by using near-IR (NIR) absorbing gold nanoshells, ,,, nanorods, and nanocages ,, or by applying molecular-targeted spherical nanoparticles which undergo molecular specific aggregation upon interaction with cancer cells that results in strong absorption in the red- to NIR-spectral region due to plasmon resonance coupling. , The use of NIR irradiation is essential for in vivo applications because NIR light has the best tissue penetration depth. , In more recent developments, gold nanoparticles have been explored as carriers of nucleic acids such as siRNA or antisense DNA molecules that can be selectively activated or released using light irradiation, which results in remotely triggered gene silencing. − …”

“…12,48 The use of NIR irradiation is essential for in vivo applications because NIR light has the best tissue penetration depth. 49,50 In more recent developments, gold nanoparticles have been explored as carriers of nucleic acids such as siRNA or antisense DNA molecules that can be selectively activated or released using light irradiation, which results in remotely triggered gene silencing. 51−53 Among all available nanoparticle geometries anisotropic gold nanorods provide a convenient combination of properties for biomedical applications.…”

Review of near-infrared methods for wound assessment

“…The measure light remittance between a "baseline" and "activated" state can be analyzed in terms of a modified Beer-Lambert (MBL) approach to provide an estimate of the difference in hemoglobin oxygenation between the two states. 1 Pulse oximetry uses this approach by measuring the difference of remitted light at the systolic and diastolic phases of the cardiac cycle at a "red" and "NIR" wavelength. The modulation of the remitted light due to the pulsatile blood volume change is largely localized in the arterial compartment of the circulatory system, and the measured oxygenation, S p O 2 , can be related to the systemic arterial hemoglobin oxygenation, S a O 2 .…”

“…NIR light is weakly absorbed but highly scattered by tissue, thereby enabling this light to penetrate tissue more deeply than ultraviolet, visible, and infrared radiation. 1 This deeper penetration is one of the factors why NIR light is employed for the assessment of wounds. This manuscript will review some of the NIR based methods that are used for wound assessment.…”

SnapshotNIR: a handheld multispectral imaging system for tissue viability assessment

“…The visible and short wavelength near infrared regions of the electromagnetic spectrum have a long history of being used to provide a measure of hemoglobin oxygen saturation. 1 When the measurement is made in-vivo, the short wavelength near infrared region is usually preferred because of its ability to penetrate more deeply into tissue. This becomes particularly important when trying to make trans-cutaneous measurements.…”