Clinical noninvasive imaging and spectroscopic tools for dermatological applications: Review of recent progress

Abstract

Dermatologists mainly entrust visual clinical examinations in conjunction with histopathology for an informed skin condition diagnosis, which is invasive and not adequate to assess skin conditions still present in subcutaneous skin layers. With emerging complementary imaging and spectroscopic technologies currently available, the assessment of skin conditions is more accessible than before. This review article will cover these technologies including: photoacoustic imaging, reflectance confocal microscopy, multiphoton microscopy, optical coherence tomography and confocal Raman spectroscopy. The basic concepts of these technologies and their configurations will be touched on, together with their limitations and future directions. The review article will discuss how these technologies are utilized for cutaneous applications, examining studies accomplished either in vivo on humans or on ex vivo human specimens.

Quenched coumarin derivatives as fluorescence lifetime phantoms for NADH and FAD

“…The fits to the quadratic function SV2 defined in Equation ( 5 , KD = 1.189 (0.6257,1.752) L mol −1 and R 2 = 0.998 for coumarin 6. In both cases, the measured datapoints are adequately described by the fit function SV2 in the entire range of examined quencher concentrations, as in the case of Figure 4 and the fit function H2 defined in Equation (3).…”

“…For the synthesis of phantom solutions with fluorescence lifetimes corresponding to those of free and bound NADH, τ 1 ≈ 0.4 ns and τ 2 ≈ 2.5 ns, respectively, the required 4-hydroxy-TEMPO concentrations were determined as Q 0.4 = 0.234 mol L −1 and Q 2.5 = 8.55 × 10 −3 mol L −1 , based on the fit function H2 defined in Equation (3).…”

“…To further exploit this valuable information for medical diagnostics (eg, in the form of FLIM endoscopy), new instrumentation (eg, by integration of FLIM capability into devices similar to multiphoton This manuscript is part of the inaugural thesis of Christian Freymüller to be submitted to the Medical Faculty of LMU Munich. systems described in References [2,3]) and investigation protocols need to be devised. For the development, testing or comparison of medical diagnostic systems, it is usually necessary to evaluate a system by a defined calibration protocol/procedure.…”

Spectroscopic methods to quantify molecules of the heme‐biosynthesis pathway: A review of laboratory work and point‐of‐care approaches

“…Next to the described developments in fluorescence and absorption spectroscopy, also, other optical technologies are under strong investigation research, for example, diffuse reflectance spectroscopy, Raman spectroscopy, infrared spectroscopy, fluorescence lifetime measurements, second harmonic generation, or photoacoustics [76–80]. These techniques would allow for detecting fingerprint molecules in body fluids [76, 77] and breath [78] or diagnosing oral and skin cancers [79, 80].…”

A Portable Ultrawideband Confocal Raman Spectroscopy System with a Handheld Probe for Skin Studies

“…Hence, there is a strong unmet need to develop an in vivo and non-invasive technique for skin studies, especially in the molecular level. Among various optical techniques including fluorescence, infrared spectroscopy, optical coherence tomography, photoacoustic imaging, etc., Raman spectroscopy is one of the most powerful tools for biological tissue analysis owing to its excellent specificity, non-destructiveness, and rapid acquisition . Molecules excited by a certain wavelength laser will lead to inelastic photon scattering and generate a characteristic Raman shift immediately, depending on their unique functional groups.…”