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Special Issue "Optical Sensors in Medicine"

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A special issue of Sensors (ISSN 1424-8220).

Deadline for manuscript submissions: closed (1 December 2011)

Special Issue Editor

Guest Editor
Prof. Dr. Panicos Kyriacou

School of Mathematics, Computer Science and Engineering, City University London, Northampton Square, London, EC1V 0HB, UK
Website1 | Website2 | E-Mail
Interests: biomedical optical sensors; tissue optics; spectrophotometry; bio-instrumentation; physiological measurement

Special Issue Information

Dear Colleagues,

Throughout human history light has played an important role in medicine. New optical technologies, many involving light emitting diodes, laser diodes, lasers, fibre optics or nanotechnologies, providing sensitive and compact electronic like devices, are revolutionising many fields. Applications of new optical technologies to medicine might be described as in an adolescent stage, where their power and potential can be recognised but are still developing rapidly, and much is yet to come. Such technologies, so far, have been used extensively for monitoring, diagnostic, prognostic or therapeutic purposes. There are many new methods of optical monitoring of tissue and other anatomical parts that offer the potential to find widespread use in medicine e.g. spectrophotometry, OCT, photo-acoustic imaging, pulse oximetry, NIRS, etc. The establishment of such techniques often depends on the development of new light sources, detectors, signal and image processing algorithms.

This special issue invites submissions in this area, particularly those that are application-focused. Examples of application areas include real-time (non-invasive or invasive) physiological and biochemical monitoring using optical techniques, spectral analysis, and imaging techniques, including both, point-based or full-field. Mathematical modelling of optical propagation in tissue, as well as signal-processing techniques developed or adapted specifically for extraction of biomedical information arising from optical techniques also lie within the scope of this special issue.

Prof. Dr. Panicos Kyriacou
Guest Editor

Keywords

  • tissue optics
  • photoplethysmography
  • pulse oximetry
  • NIRS
  • photometry
  • spectrophotometry
  • perfusion
  • chromophore concentration
  • optical monitoring
  • OCT

Published Papers (6 papers)

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Research

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Open AccessArticle Detection of Prostate Stem Cell Antigen Expression in Human Prostate Cancer Using Quantum-Dot-Based Technology
Sensors 2012, 12(5), 5461-5470; doi:10.3390/s120505461
Received: 16 March 2012 / Revised: 13 April 2012 / Accepted: 19 April 2012 / Published: 27 April 2012
Cited by 9 | PDF Full-text (311 KB) | HTML Full-text | XML Full-text
Abstract
Quantum dots (QDs) are a new class of fluorescent labeling for biological and biomedical applications. In this study, we detected prostate stem cell antigen (PSCA) expression correlated with tumor grade and stage in human prostate cancer by QDs-based immunolabeling and conventional immunohistochemistry (IHC),
[...] Read more.
Quantum dots (QDs) are a new class of fluorescent labeling for biological and biomedical applications. In this study, we detected prostate stem cell antigen (PSCA) expression correlated with tumor grade and stage in human prostate cancer by QDs-based immunolabeling and conventional immunohistochemistry (IHC), and evaluated the sensitivity and stability of QDs-based immunolabeling in comparison with IHC. Our data revealed that increasing levels of PSCA expression accompanied advanced tumor grade (QDs labeling, r = 0.732, p < 0.001; IHC, r = 0.683, p < 0.001) and stage (QDs labeling, r = 0.514, p = 0.001; IHC, r = 0.432, p = 0.005), and the similar tendency was detected by the two methods. In addition, by comparison between the two methods, QDs labeling was consistent with IHC in detecting the expression of PSCA in human prostate tissue correlated with different pathological types (K = 0.845, p < 0.001). During the observation time, QDs exhibited superior stability. The intensity of QDs fluorescence remained stable for two weeks (p = 0.083) after conjugation to the PSCA protein, and nearly 93% of positive expression with their fluorescence still could be seen after four weeks. Full article
(This article belongs to the Special Issue Optical Sensors in Medicine)
Figures

Open AccessArticle Gen-2 Hand-Held Optical Imager towards Cancer Imaging: Reflectance and Transillumination Phantom Studies
Sensors 2012, 12(2), 1885-1897; doi:10.3390/s120201885
Received: 31 December 2011 / Revised: 31 January 2012 / Accepted: 3 February 2012 / Published: 10 February 2012
Cited by 9 | PDF Full-text (755 KB) | HTML Full-text | XML Full-text
Abstract
Hand-held near-infrared (NIR) optical imagers are developed by various researchers towards non-invasive clinical breast imaging. Unlike these existing imagers that can perform only reflectance imaging, a generation-2 (Gen-2) hand-held optical imager has been recently developed to perform both reflectance and transillumination imaging. The
[...] Read more.
Hand-held near-infrared (NIR) optical imagers are developed by various researchers towards non-invasive clinical breast imaging. Unlike these existing imagers that can perform only reflectance imaging, a generation-2 (Gen-2) hand-held optical imager has been recently developed to perform both reflectance and transillumination imaging. The unique forked design of the hand-held probe head(s) allows for reflectance imaging (as in ultrasound) and transillumination or compressed imaging (as in X-ray mammography). Phantom studies were performed to demonstrate two-dimensional (2D) target detection via reflectance and transillumination imaging at various target depths (1–5 cm deep) and using simultaneous multiple point illumination approach. It was observed that 0.45 cc targets were detected up to 5 cm deep during transillumination, but limited to 2.5 cm deep during reflectance imaging. Additionally, implementing appropriate data post-processing techniques along with a polynomial fitting approach, to plot 2D surface contours of the detected signal, yields distinct target detectability and localization. The ability of the gen-2 imager to perform both reflectance and transillumination imaging allows its direct comparison to ultrasound and X-ray mammography results, respectively, in future clinical breast imaging studies. Full article
(This article belongs to the Special Issue Optical Sensors in Medicine)
Open AccessArticle Evaluation of Electrical and Optical Plethysmography Sensors for Noninvasive Monitoring of Hemoglobin Concentration
Sensors 2012, 12(2), 1816-1826; doi:10.3390/s120201816
Received: 14 December 2011 / Revised: 31 January 2012 / Accepted: 3 February 2012 / Published: 9 February 2012
Cited by 6 | PDF Full-text (924 KB) | HTML Full-text | XML Full-text
Abstract
Completely noninvasive monitoring of hemoglobin concentration has not yet been fully realized in the clinical setting. This study investigates the viability of measuring hemoglobin concentration noninvasively by evaluating the performance of two types of sensor using a tissue phantom perfused with a blood
[...] Read more.
Completely noninvasive monitoring of hemoglobin concentration has not yet been fully realized in the clinical setting. This study investigates the viability of measuring hemoglobin concentration noninvasively by evaluating the performance of two types of sensor using a tissue phantom perfused with a blood substitute. An electrical sensor designed to measure blood volume changes during the cardiac cycle was used together with an infrared optical sensor for detection of erythrocyte-bound hemoglobin. Both sensors demonstrated sensitivity to changes in pulse volume (plethysmography). The electrical sensor produced a signal referred to as capacitance plethysmograph (CPG) a quantity which was invariant to the concentration of an infrared absorbing dye present in the blood substitute. The optical sensor signal (photoplethysmograph) increased in amplitude with increasing absorber concentration. The ratio PPG:CPG is invariant to pulse pressure. This quantity is discussed as a possible index of in vivo hemoglobin concentration. Full article
(This article belongs to the Special Issue Optical Sensors in Medicine)
Open AccessArticle Phantom with Pulsatile Arteries to Investigate the Influence of Blood Vessel Depth on Pulse Oximeter Signal Strength
Sensors 2012, 12(1), 895-904; doi:10.3390/s120100895
Received: 29 November 2011 / Revised: 29 December 2011 / Accepted: 10 January 2012 / Published: 16 January 2012
Cited by 5 | PDF Full-text (446 KB) | HTML Full-text | XML Full-text
Abstract
This paper describes a three-layer head phantom with artificial pulsating arteries at five different depths (1.2 mm, 3.7 mm, 6.8 mm, 9.6 mm and 11.8 mm). The structure enables formation of spatially and temporally varying tissue properties similar to those of living tissues.
[...] Read more.
This paper describes a three-layer head phantom with artificial pulsating arteries at five different depths (1.2 mm, 3.7 mm, 6.8 mm, 9.6 mm and 11.8 mm). The structure enables formation of spatially and temporally varying tissue properties similar to those of living tissues. In our experiment, pressure pulses were generated in the arteries by an electronically controlled pump. The physical and optical parameters of the layers and the liquid in the artificial arteries were similar to those of real tissues and blood. The amplitude of the pulsating component of the light returning from the phantom tissues was measured at each artery depth mentioned above. The build-up of the in-house-developed pulse oximeter used for performing the measurements and the physical layout of the measuring head are described. The radiant flux generated by the LED on the measuring head was measured to be 1.8 mW at 910 nm. The backscattered radiant flux was measured, and found to be 0.46 nW (0.26 ppm), 0.55 nW (0.31 ppm), and 0.18 nW (0.10 ppm) for the 1.2 mm, 3.7 mm and 6.8 mm arteries, respectively. In the case of the 9.6 mm and 11.8 mm arteries, useful measurement data were not obtained owing to weak signals. We simulated the phantom with the arteries at the above-mentioned five depths and at two additional ones (2.5 mm and 5.3 mm in depth) using the Monte Carlo method. The measurement results were verified by the simulation results. We concluded that in case of 11 mm source-detector separation the arteries at a depth of about 2.5 mm generate the strongest pulse oximeter signal level in a tissue system comprising three layers of thicknesses: 1.5 mm (skin), 5.0 mm (skull), and > 50 mm (brain). Full article
(This article belongs to the Special Issue Optical Sensors in Medicine)
Figures

Open AccessArticle Micro-Raman Spectroscopy and Univariate Analysis for Monitoring Disease Follow-Up
Sensors 2011, 11(9), 8309-8322; doi:10.3390/s110908309
Received: 7 July 2011 / Revised: 17 August 2011 / Accepted: 18 August 2011 / Published: 25 August 2011
Cited by 8 | PDF Full-text (314 KB) | HTML Full-text | XML Full-text
Abstract
Micro-Raman spectroscopy is a very promising tool for medical applications, thanks to its sensitivity to subtle changes in the chemical and structural characteristics of biological specimens. To fully exploit these promises, building a method of data analysis properly suited for the case under
[...] Read more.
Micro-Raman spectroscopy is a very promising tool for medical applications, thanks to its sensitivity to subtle changes in the chemical and structural characteristics of biological specimens. To fully exploit these promises, building a method of data analysis properly suited for the case under study is crucial. Here, a linear or univariate approach using a R2 determination coefficient is proposed for discriminating Raman spectra even with small differences. The validity of the proposed approach has been tested using Raman spectra of high purity glucose solutions collected in the 600 to 1,600 cm−1 region and also from solutions with two known solutes at different concentrations. After this validation step, the proposed analysis has been applied to Raman spectra from oral human tissues affected by Pemphigus Vulgaris (PV), a rare life-threatening autoimmune disease, for monitoring disease follow-up. Raman spectra have been obtained in the wavenumber regions from 1,050 to 1,700 cm−1 and 2,700 to 3,200 cm−1 from tissues of patients at different stages of pathology (active PV, under therapy and PV in remission stage) as confirmed by histopathological and immunofluorescence analysis. Differences in the spectra depending on tissue illness stage have been detected at 1,150–1,250 cm−1 (amide III) and 1,420–1,450 cm−1 (CH3 deformation) regions and around 1,650 cm−1 (amide I) and 2,930 cm−1 (CH3 symmetric stretch). The analysis of tissue Raman spectra by the proposed univariate method has allowed us to effectively differentiate tissues at different stages of pathology. Full article
(This article belongs to the Special Issue Optical Sensors in Medicine)

Review

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Open AccessReview Respiratory Physiology and the Impact of Different Modes of Ventilation on the Photoplethysmographic Waveform
Sensors 2012, 12(2), 2236-2254; doi:10.3390/s120202236
Received: 13 December 2011 / Revised: 7 February 2012 / Accepted: 8 February 2012 / Published: 16 February 2012
Cited by 4 | PDF Full-text (3524 KB) | HTML Full-text | XML Full-text
Abstract
The photoplethysmographic waveform sits at the core of the most used, and arguably the most important, clinical monitor, the pulse oximeter. Interestingly, the pulse oximeter was discovered while examining an artifact during the development of a noninvasive cardiac output monitor. This article will
[...] Read more.
The photoplethysmographic waveform sits at the core of the most used, and arguably the most important, clinical monitor, the pulse oximeter. Interestingly, the pulse oximeter was discovered while examining an artifact during the development of a noninvasive cardiac output monitor. This article will explore the response of the pulse oximeter waveform to various modes of ventilation. Modern digital signal processing is allowing for a re-examination of this ubiquitous signal. The effect of ventilation on the photoplethysmographic waveform has long been thought of as a source of artifact. The primary goal of this article is to improve the understanding of the underlying physiology responsible for the observed phenomena, thereby encouraging the utilization of this understanding to develop new methods of patient monitoring. The reader will be presented with a review of respiratory physiology followed by numerous examples of the impact of ventilation on the photoplethysmographic waveform. Full article
(This article belongs to the Special Issue Optical Sensors in Medicine)

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