Proceedings Volume 4432

Diagnostic Optical Spectroscopy in Biomedicine

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Proceedings Volume 4432

Diagnostic Optical Spectroscopy in Biomedicine

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Volume Details

Date Published: 31 October 2001
Contents: 11 Sessions, 42 Papers, 0 Presentations
Conference: European Conferences on Biomedical Optics 2001
Volume Number: 4432

Table of Contents

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Table of Contents

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  • DOS: Research and Theory I
  • DOS: Research and Theory II
  • DOS: Research and Theory III
  • DOS: Research and Theory IV
  • DOS: Clinical Studies I
  • DOS: Clinical Studies II
  • DOS: Clinical Studies III
  • DOS: Clinical Studies IV
  • DOS: Clinical Studies V
  • Poster Session
  • Postdeadline Session
DOS: Research and Theory I
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Trimodal spectroscopy as a tool for detecting cervical squamous intraepithelial lesions in vivo
Irene Georgakoudi, Ellen E. Sheets, Christopher P. Crum, et al.
Using intrinsic fluorescence, diffuse reflectance and light scattering spectroscopy we extracted quantitative biochemical and morphological information in vivo about the bulk tissue and the epithelial cell nuclei of ectocervical sites from 44 patients. Significant changes were observed in tissue morphology and biochemistry between normal, squamous metaplastic and squamous intraepithelial lesion (SIL) sites. The combined use of all three spectroscopic techniques (tri-modal spectroscopy) yielded superior results for detecting SILs than any one of the techniques alone.
FT-IR spectroscopic imaging of tissue thin sections
Peter Lasch, Matthias Boese, Max Diem
FT-IR microspectroscopy in combination with digital image reassembling methodologies have been used to characterize distinct tissue structures within thin sections from the human prostate. The spatially resolved microspectroscopic data were collected with a resolution near the diffraction limit (about 8 micrometers ) by using a HgCdTe focal plane array detector-based infrared imaging instrument. While IR imaging based on distinct spectral parameters such as intensities, frequency values, or half-widths (the univariate imaging technique of chemical mapping) often gives unsatisfactory results, multivariate data analysis techniques (e.g. hierarchical clustering or principal component analysis) confirmed standard histopathological techniques and turned out to be helpful to discriminate reliably between different tissues structures.
Optical pathlength meter for near-infrared spectroscopy
Iain D. C. Tullis, David T. Delpy
Many commercial clinical Near Infrared Spectroscopy (NIRS) instruments rely upon estimates of the optical pathlength of tissue based upon the optode spacing multiplied by an average differential pathlength factor(DPF) for the tissue under investigation. Significant variation in the published DPF is the major source of error in the NIRS data quantification. To reduce this error, an inexpensive, stand-alone, single wavelength, single frequency optical pathlength meter based on the homodyne phase method was constructed for clinical use with an existing NIRO 300 instrument (Hamamatsu Photonics KK). The construction and testing of the optical pathlength meter is discussed.
Application of low-scattering photon correlation spectroscopy for blood monitoring
Extension of the photon correlation spectroscopy (PCS) technique in low scattering regime was employed to the samples of whole blood studied. A few times scattered light from a weak helium-neon laser beam incident on the cuvette with the blood sample was detected by a photo-multiplier, and both temporal intensity autocorrelation functions and power spectra were measured with digital autocorrelator and spectrum analyzer. The potentialities of the qualitative and quantitative determining of the structural characteristics of blood elements are demonstrated. To analyze the blood samples we propose to use the PCS technique extended for the transition regime of scattering from single to multiple. The studies made permits the use of the technique for the in vitro clinical blood testing.
DOS: Research and Theory II
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Autofluorescence lifetime measurements in images of the human ocular fundus
Measurements of the autofluorescence at the fundus prove to be an important tool in early diagnosis and in discovering the pathomechanism, e.g., in age-related macular degeneration. In addition to the action of lipofuscin in the aging process, flavines play an important role as prosthetic groups. As metabolic changes occur at cellular level, patient-specific optimized therapy should be possible according to endogenous fluorophores, before morphological alterations are manifest. As a first tool for the detection of dynamic autofluorescence, a laser scanner opthalmoscope will be presented permitting lifetime measurements at the living human eye-ground under extremely weak detectable light. Considering histograms of lifetimes after excitation at 457.8 nm and determined at the living human eye ground in parapapillary region, a lifetime (rho) approximately equal to 1.38nm was calculated most frequently in the long-wave emission range ((lambda) $GTR550 nm). This points to the main contribution of lipfuscin. If the emission range is extended down to 515 nm, components with longer lifetimes are additionally detectable. Lifetime measurements at a human fundus specimen confirmed the lifetime of 1.38nm in lipfuscin-rich pigment epithelium, whereas the mean lifetime of an intact fundus was 2.04ns. A comparison of lifetimes before, during, and after breathing 100% oxygen results in a quenching of the mean lifetime of 0.15ns by oxygen.
Influence of the phase function on the determination of the optical properties of biological media
We investigated the influence of the phase function on the determination of the optical properties of turbid media by measuring the spatially resolved reflectance, R((rho) ). Monte Carlo simulations of R((rho) ) using different experimental and theoretical phase functions served as experimental data. We show that the errors in the optical properties are as high as 100%, if these data are fitted with a standard solution of the diffusion equation. In addition, Monte Carlo simulations are applied to fit the `experimental data' using the scattering coefficient, the absorption coefficient and an additional parameter, that characterizes the phase function, as fitting parameters. It is shown that the errors in the optical parameters are < 20%.
Optical properties of tissue simulators based on laser-induced spectroscopy and scattering measurements
Helen Drakaki, Mersini I. Makropoulou, Alexander A. Serafetinides
Measurements of the tissue optical parameters and the theoretical modeling of the light propagation in biological tissues is very important for real time laser treatment dosimetry and non- invasive diagnosis. An integrating sphere based technique was used to determine the tissue optical properties. Soft tissue - like phantoms were irradiated with visible lasers and the optical parameters were compared with results calculated from the Beer's law model of light propagation and the Kubelka - Munk simulation.
Simultaneous near-IR spectroscopy and magnetic resonance imaging to assess cerebral oxygenation and brain water during hypoxia-ischemia in two-week-old rats
R. A. Shaw, U. I. Tuor, T. Foniok, et al.
Cerebral near-infrared spectroscopy can potentially probe several parameters related to the onset of stroke and the ensuing tissue damage. One obvious marker of ischemia is cerebral oxygenation, which can be lowered sharply in stroke-affected tissue. Also commonly assessed, though less straightforward to recover, is the redox state of the cytochrome aa3 copper center. Finally, parameters that are in principle available but seldom recovered from in vivo near-IR spectra are changes in water concentration and scattering properties of the tissue. We have evaluated the potential for near-IR spectroscopy to detect relevant changes in cerebral oxygenation, blood volume, water content, and scattering properties in an infant rat stroke model that is well characterized by magnetic resonance imaging methods. The specific aim was to acquire near-IR spectra simultaneously with MR images and to correlate stroke-associated changes detected via these two modalities prior to, during and after a hypoxia-ischemia episode within this stroke model. Presented here are results from the design and testing of a near-IR illumination/detection system that is compatible with an MR imaging system, and the recovery of trends in the near-IR spectra that complement the hypoxic-ischemic changes observed in the MR images. Unexpectedly large intensity changes observed for the in vivo near-IR water absorptions are ascribed to hypoxia-induced variations in effective optical pathlength, suggesting that the water absorptions may prove generally useful as a means to track such changes.
Detection of optical inhomogeneity by Monte Carlo simulation
D. Kumar, Megha Singh
Light propagation in simulated tissue models was analysed by Monte Carlo method. For this purpose three tissue models were considered. Heart tissue without abnormality was considered as control. For other two models small spherical size tissues of different optical parameters inside the control tissue, at different depths, were introduced. Depending on the optical properties of the abnormalities the photon distributions within and on the surface of the tissues were altered. These results showed that the variation in the backscattered fraction of photons on the tissue surface helps in identifying and characterising the abnormality.
DOS: Research and Theory III
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Real-time inversion using Monte Carlo results for the determination of absorption coefficients in multilayered tissues: application to noninvasive muscle oximetry: II
Sigrid Avrillier, Eric Tinet, Jean-Michel Tualle, et al.
A clinical study of the evolution of the space resolved near infrared reflectance with the subcutaneous layers thickness, at rest, on the vastus lateralis, is used to determine convenient sets of muscle and fat optical coefficients at 850 nm and 780 nm. These coefficients are then used to establish pre-calculated 3 layers MC simulations tables of the reflectance as a function of the fat thickness. Real time inversion during effort is then performed to determine the absolute muscle oxygenation.
In-vivo absorption spectroscopy in brain using small optical fiber probes: effect of blood confinement
Adrian Bradu, Raphael Sablong, C. Julien, et al.
Broad band light absorption spectroscopy in the visible range (520-590nm) has been carried out using implanted small optical fibers to probe the hemodynamics of deep tissues (striatum) in rat brain subjected to hypoxia. We observe a decrease of the cerebral blood oxygenation by a factor of up to two, while the cerebral blood volume (CBV) does not seem to increase significantly. However, nuclear magnetic resonance measurements of CBV in the same conditions using a magnetic contrast agent show that CBV increases by about 50%. This shows that absorption spectroscopy in the visible range strongly underestimates the CBV, probably due to the confinement of blood in vessels. This effect is confirmed by absorption spectroscopy measurements performed in phantoms with similar geometry.
Optical diffusion imaging data from speckle pattern frequency correlations
Mark A. Webster, Kevin J. Webb, Andrew M. Weiner
We demonstrate a convenient technique for determining the temporal response and scattering parameters of a diffusive medium using laser speckle pattern frequency correlations. Experimental results using an external-cavity tunable laser diode are presented. This approach can be extended to provide data for image reconstruction based on a diffusion model.
In vivo and in vitro study of immersion clearing dynamics of the skin
Experimental results on in vivo and in vitro immersion clearing dynamics of the skin under action of the osmotic agent are presented. The significant decrease of the human skin reflectance in vivo under action of glucose solution is demonstrated. In vitro experiments with dyed immersion agents have shown that the immersion mostly penetrates into skin tissue though the dermal layer. Diffusion of the immersion agent through the stratum corneum barrier was insignificant. It was shown the hypodermic injection of the immersion agent is an effective way for the agent administration. The time-dependent contrast of the blood perfused areas in the cleared skin was estimated. The diffusion coefficient of 40%-glucose solution in skin in vivo was estimated as D equals (2.56+/- 0.13)(DOT)10-6cm2sec.
DOS: Research and Theory IV
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Determination of the optical parameters of dentin from spatially resolved reflectance and transmittance measurements
Measurements of the absolute spatially resolved reflectance and transmittance from dentin slabs were performed using a HeNe laser at (lambda) equals633 mm as source and a CCD camera as detector. Solid phantom slabs were used to test the experimental setup and to enable absolute measurements. The reduced scattering and absorption coefficients were derived by applying a solution of the diffusion theory for a slab geometry as theoretical model. Monte Carlo simulations were used to investigate the validity of the diffusion solution. Compared to other biological tissues large values were found for the reduced scattering coefficient of dry dentin slabs, in which the tubuli were parallel to the slab extension. In addition, we measured a strong dependence of the optical properties on the water content of the dentin slabs. We also found that the anisotropic structure of dentin strongly influences the light propagation and, thus, the derived optical properties.
Diagnosis of dental caries using quantitative light-induced fluorescence
Bennett T. Amaechi, Susan M. Higham
Current dental diagnostic methods can detect caries but cannot quantify the mineral status of the lesion. Quantitative Light-induced Fluorescence (QLF) measures the percentage fluorescence radiance change of demineralised enamel with respect to surround sound enamel, and related it directly to the amount of mineral lost during demineralisation. Demineralisation of teeth to produce caries-like lesions and the subsequent remineralisation of the lesions were monitored quantitatively and longitudinally with QLF. The influence of factors such as presence of plaque or saliva, lesion staining, lesion magnification, tooth thickness and developmental hypomineralisation, on the reproducibility of QLF imaging and analysis were investigated, Results showed that the integrated fluorescence change (hence the mineral loss) increased linearly with demineralisation time and decreased with increasing remineralisation time. Caries detection was limited by saliva or plaque, but enhanced by staining. QLF could not discriminate between developmental hypomineralisation and caries. Neither the variation in tooth thickness nor lesion magnification within the limit of a sharp image made a significant difference in QLF analysis. It was concluded that QLF could detect and quantitatively monitor the mineral changes in an incipient caries on a longitudinal basis, however detection may be limited by the presence of saliva or plaque or enhanced by staining.
Changes in in-vivo autofluorescence spectra at different periods in rat colorectal tumor progression
S. Fu, Chee Teck Chia, C. L. Tang, et al.
The study focuses on the Laser-Induced Autofluorescence (LIAF) diagnosis technique to identify early tumor tissue. 442nm light from a Helium-Cadmium Laser is excited to investigate the spectra of the in vivo normal and tumor rat colorectal tissues. The experiment results show that the LIAF spectra of the normal and tumor colorectal tissues exhibit the significant differences. The results are potentially useful for the development of a clinical study for early colorectal cancer diagnosis.
Serum fluorescence and Raman spectra for diagnosis of cancer
Xiao Zhou Li, Jing Bai, Junxiu Lin, et al.
Optical spectroscopy for tumor demarcation was investigated in this study. Laser-induced fluorescence and Raman spectra were measured from normal and tumorous human blood serum in an attempt to discover some values useful in discrimination between normal and tumorous cases. Three Raman peaks were consistently observed from normal blood serum emission using 488.0nm and 514.5nm excitation of an Ar-ion laser, whereas no peak or only slight Raman peaks were detected from tumorous cases. In addition, red shift of fluorescence peak and decrease of fluorescence intensity were observed after samples radiated by laser. According to one thousand twenty-two samplesí» spectra, three parameters (alpha) , (beta) and (delta) (lambda) are introduced to distinguish normal, benign and malignant from one another. The application of such parameters in clinical diagnosis was researched. Four hundred and fifty-nine samples were investigated before knowing the result of clinical diagnosis in order to estimate the availability of our criteria.
DOS: Clinical Studies I
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Detection of early bronchial carcinoma by imaging of the tissue autofluorescence
Didier Goujon, Thomas M. Glanzmann, Tanja Gabrecht, et al.
Early detection and localisation of bronchial cancer remains a challenging task. One approach is to exploit the changes in the autofluorescence characteristics of the bronchial tissue as a diagnostic tool with improved sensitivity. Evidence exists that this native fluorescence or autofluorescence of bronchial tissues changes when they turn dysplastic and to carcinoma in situ. There is an agreement in the literature that the lesions display a decrease of autofluorescence in the green region of the spectrum under illumination with violet light and a relative increase in the red region of the spectrum is often reported. Imaging devices rely on this principle to detect early cancerous lesions in the bronchi. Based on a previous spectroscopic study, an industrial imaging prototype has been developed to detect early cancerous lesions in collaboration with the firm 'Richard Wolf Endoskope GmbH'. A preliminary clinical trial involving 20 patients with this spectrally optimised system proved that autofluorescence can detect lesions that would otherwise have remained invisible even to an experienced endoscopist under white light illumination. A systematic analysis of the autofluorescence images pointed out that real-time decisional functions can be defined in order to reduce the number of false positive results. Using this method, a Positive Predictive Value (PPV) of 75% was achieved using autofluorescence only. A PPV of even 100% were obtained when white light mode and autofluorescence mode were combined under the applied conditions. Furthermore, the sensitivity was estimated to be twice as high in AF mode than in WL mode.
Fluorescence imaging in the uppper gastrointestinal tract for the detection of dysplasic changes
Uwe Sukowski, Bernd Ebert, Marianne Ortner, et al.
During endoscopy of the esophagus fluorescence images were recorded at a delay of 20 ns after pulsed laser excitation simultaneously with conventional reflected white light images. To label malignant cells (dysplasia, tumor) 5-aminolaevulinic acid was applied prior to fluorescence guided bi-opsy. In this way pre-malignant and malignant lesions were detected not seen previously during routine endoscopy.
Optical biopsy for the diagnosis of breast tumors
David C. O. Pickard, Irving J. Bigio, Stephen G. Bown, et al.
Elastic scattering or spectroscopy offers the possibility of distinguishing between cancerous and non-cancerous tissue in suspicious breast lumps with a relatively simple optical measurement. The measurement of the relative reflection of light has previously been shown to be sensitive to both the size and distribution of intra and inter-cellular structures as well as absorption from chromophores present in the tissue. Coupling a white light source and spectrometer to optic fibres makes it possible to construct probes that can be inserted through the skin or used during the operation or on excised tissue such as the sentinel node. This `optical biopsy' is correlated with a conventional histopathological specimen obtained at the same point. Spectra have been obtained from a large number of patients with benign and malignant lesions. Some of the differences that appear in these spectra have been identified and these are discussed. To a relatively high degree of sensitivity and specificity it is shown to be possible to distinguish between malignant tumours, benign lesions and normal tissue.
DOS: Clinical Studies II
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Fluorescence spectroscopy and imaging for detection of colonic dysplasia
Norman E. Marcon M.D.
Cancer of the colon is the second leading cause of cancer related death in North America and Europe. Colonoscopy is currently the gold standard for the detection and removal of polyps and the diagnosis of cancer. Although a field of intense research, there are currently no surrogate serum or stool markers that accurately identify patients at risk who may have adenomatous colon polyps or curable cancer. Clinicians therefore rely on white light colonoscopy to survey colonic mucosa in their search for poiyps. White light endoscopy has some limitations. It cannot detect flat, non raised lesions. It cannot distinguish easily between hyperplastic and adenomatous polyps. Subtle, flat lesions may be missed. Scars at the sites ofprevious sessile polyps are difficult to evaluate for recurrence. Endoscopies utilizing fluorescence techniques either on the basis of intrinsic fluorescence or exogenous (prodrug) compounds, have the potential to compliment white light endoscopy by improving detection of mucosal dysplasia and ultimately improve outcomes for cancer detection before the date of escape from cure.
Optical biopsy for the diagnosis of dysplasia in Barrett's oesophagus
David C. O. Pickard, Irving J. Bigio, Stephen G. Bown, et al.
Barrett's oesophagus is an increasingly common pre-cancerous condition, which occurs in patients suffering from acid reflux into their gullet. Biopsies must be taken from patients diagnosed with this condition regularly to pick up signs of pre-cancerous changes. Elastic scattering spectroscopy offers the possibility of distinguishing between benign and pre-cancerous changes in the lower oesophagus with a relatively simple optical measurement. This optical biopsy is correlated with a conventional histopathological specimen obtained at the same point. It is shown that to a relatively high degree of sensitivity and specificity it is possible to distinguish between pre-malignant patches, benign lesions and normal tissue.
Light-induced autofluorescence for detection of nasopharyngeal carcinoma in vivo
Hanpeng Chang, Yue Wen, Siu Lung Lee, et al.
To improve the accuracy of conventional white light endoscopy in detecting the small lesion and identifying the margin of observable tumors, in vivo, the potential of light-induced fluorescence (LIF) spectroscopic imaging, using a general multivariate spectral classification algorithm, was evaluated. A conventional endoscopic system with a multiple channel spectrometer was used to measure the autofluorescence of nasopharyngeal tissue in vivo. Classification was based on the spectral difference between the carcinoma and normal tissue. A sophisticated algorithm based on Principal Component Analysis (PCA) was developed to differentiate between the nasopharyngeal carcinoma (NPC) from the normal tissue. Firstly, preprocessing was done to reduce noise and to calibrate the different measurement distances and geometry. Secondly, processing by PCA was done to effectively reduce the variable dimensions while maintaining useful information for analysis. Thirdly, various post-processing techniques were investigated and the classification performance was compared. Algorithms based on ratio of autofluorescence at two-wavelength and three-wavelength bands were used for comparison. The PCA based method shows a significant improvement over the two-wavelength and three-wavelength algorithm. Based on the entire spectra, the sensitivity of 92% and specificity of 96% were achieved using the PCA based algorithm for the detection of nasopharyngeal carcinomas. In conclusion, the PCA based statistical algorithm is efficient to achieve high spectral classification performance of NPC.
Optical detection of (pre-)malignant lesions of the oral mucosa: autofluorescence characteristics of healthy mucosa
Diana C. G. de Veld, Max Witjes, Jan L.N. Roodenburg, et al.
Previous clinical results demonstrate the potential of in vivo autofluorescence spectroscopy for early detection of (pre-)malignant lesions of the oral mucosa. For reliable diagnosis, it is necessary to study autofluorescence spectra of healthy mucosa first. We measured excitation-emission maps in healthy subjects and subjects with a history of cancer in the head -neck region. Our results show that different anatomical locations produce distinct autofluorescence spectra. Influences of, among others, smoking and drinking habits require further investigation.
DOS: Clinical Studies III
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Time-resolved autofluorescence spectroscopy of the bronchial mucosa for the detection of early cancer: clinical results
Thomas M. Glanzmann, Pascal Uehlinger, Jean-Pierre Ballini, et al.
Time-resolved measurements of endogenous tissue autofluorescence were carried out on the bronchial mucosa of 18 patients during endoscopy by the means of a optical fibre-based spectrometer. The objective was to assess the fluorescence lifetime as a new contrast parameter between normal and malignant tissue and to explain the origin of a previously observed contrast in fluorescence intensity. The intra- and interpatient variation of tissue autofluorescence intensity and decay on normal tissue was determined with the outcome that a strong fluctuation in autofluorescence intensity but not in lifetime was observed on the normal tissue. Preliminary results were obtained by comparing fluorescence decays on normal mucosa and dysplasia/carcinoma in situ. No significant change in fluorescence decay nor in spectrum between 510 and 650 nm was found. Measurements in parallel with an endoscopic autofluorescence imaging device, on the other hand, indicated a contrast in intensity and spectrum on the same lesions. This suggests that the spectral contrast might be due to an enhanced blood concentration in deeper lying layers of the lesion the optical fibre-based contact measurements are less sensitive to. The difference in intensity might be due to a lower concentration in fluorophores or to the thickening of the epithelium in the neoplastic mucous membrane. However, no indication for fluorescence quenching in the upper layers of the mucous membrane as the reason for the reduced fluorescence intensity was found. The fluorescence decays showed a quite stable behaviour with three decay times of 6.9 ns, 2.0 ns and 0.2 ns in the spectral range between 430 and 680 nm. This can be an indication that there is one dominant fluorophore involved, the calculated decay times suggest that it might be elastin. However, a slight spectral dependence of the fluorescence decays let presume that there is a contribution from other fluorophores, probably flavins and NADH.
Clinical NIR spectroscopy and optical tomography of the testis
Uwe Hampel, Eckhard Schleicher, H. Zepnick, et al.
Optical tomography and NIR spectroscopy are potential methods to improve the diagnosis of testicular pathologies. To evaluate the methods clinically we developed a special measurement device with the capability of spatially resolved laser spectroscopy and optical tomography of the testis. Simple spectroscopy is primarily used to obtain global tissue optical properties of the testis and to find correlations of optical parameters with type and stage of certain pathologies. Optical tomography is applied to visualize spectral contrasts in limited tissue volumes, such as tumors. In the course of the study we will determine whether NIR techniques posses the required specifity and sensitivity to give additional quantitative information about tissue perfusion parameters and to serve for a tumor differentiation.
DOS: Clinical Studies IV
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Clinical results with UV-excited autofluorescence spectroscopy in different organs
Herbert G. Stepp, Alexander H. Hohla
UV-excitation with 308 nm was applied clinically to normal and diseased tissues from the urinary bladder, the brain and the lungs. With a multifiber catheter, fluorescence spectra were recorded and evaluated using the most significant wavelength ratios. Correlation with histology showed the following sensitivities / specificities for the detection of malignant tissue: bladder 90% / 81%, brain 62% / 100%, lungs 80% / 76%. Compared to 5-ALA induced PPIX-fluorescence (bladder), a higher specificity was observed. The results obtained intraoperatively were compared with UV-imaging and spectroscopy on frozen tissue sections.
DOS: Clinical Studies V
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Laser-induced normal human skin in-vivo autofluorescence spectra
S. Fu, Teck-Chee Chia, Paul Choon Keat Lee, et al.
The results of the experimental investigation of laser induced autofluorescence (LIAF) spectra of normal human skin in vivo are presented. The autofluorescence (AF) spectra changes of skin in vivo during continuous exposure to 442nm Helium-Cadmium laser light are measured. 28 volunteers' arm and hand skin have been detected via non-invasive optical spectroscopy detection system. The methods explore the potentiality of the application of the LIAF technique in clinical skin disease diagnosis.
Poster Session
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Noninvasive optical monitoring of rat brain and effects of the injection of tracers for blood flow measurements
Raphael Sablong, E. Grillon, Oliver Hugon, et al.
Near infrared spectroscopy using either broad band reflectance spectrophotometry or monochromatic illumination has been carried out to monitor non invasively the changes of the concentrations of chromophores in rat brain induced by the intravenous injection of various contrast agents (indocyanine green, ultrasmall magnetic particles suspension, albumine, dextran, or saline solution alone). Depending of the wavelength and of the absorption spectrum of the injected compound the bolus can be seen either by a decrease or an increase of the transmitted light, this latter due to the induced dilution of the blood by the bolus. We suggest that this could be used to determine the arterial input function of the contrast agent needed to perform absolute cerebral blood flow imaging by nuclear magnetic resonance.
Influence of strong static magnetic field on human cancer HT 1080 cells
Juris Rodins, Vadims Korhovs, Talivaldis Freivalds, et al.
The aim of this study was to investigate strong uniform magnetic field influence on the human cancer cells HT 1080. The cells were treated with magnetic field of intensity 1,16 Tesla and with anticancer agent - cis-platinum 0.025 mg/ml or vincristinum 2-3 ng/ml. The intact and the treated cell samples were incubated in a medium with acridine orange (AO). The magnetic field after 15 minutes of influence significantly increased cytoplasmic red fluorescence. Increased AO accumulation in lysosomes suggested to cancer cell metabolic activity stimulation.
Monte Carlo simulation of light propagation in multilayered tissue with cleared inclusions
In this paper, we described our results of Monte-Carlo simulation of light propagation in a multi-layered biological tissue, such as the human brain and the skin with optical clearing. The main goal of our simulation was a study of a time delay of the detected signal and the signal form. This report includes optical clearing simulation with some variants of clearing tissue structure. As well as we described general principles of our algorithms construction.
Microspectral investigation of hair of one girl during six years by laser emission analysis
Multiple chemical elements of clinical and nutritional interest were measured in the hair of a girl - cerebral palsy patient. Sixteen samples of hair were cut and investigated to determine time and nutrition trends by using laser and arc emission spectroscopy.
Spectral characteristic analysis of lung cancer serum
Xiao Zhou Li, Huiqiang Jin, Huasheng Liu, et al.
Spectral changes of lung cancer serum in the process of tumor evolution were investigated in this study. We kept close watch on the tumor progression of a group of patients, and measured their serum spectra using 488.0nm and 514.5nm excitation of an Ar-ion laser once a week. There was no apparent change observed in fluorescence spectrum in different period. However, the relative intensity of three Raman peaks (mode A, B and C) decreased every week later. For quantitative analysis of such changes, a parameter Ir (relative intensity of C Raman peak) was introduced and Ir-value was calculated. Calculation showed that Ir-value was degressive with tumor evolution, but (beta) (Ir5145 /Ir4880) varied irregularly. To the end, no Raman peak was observed. We assumed that three Raman peaks were derived from beta carotene. It indicated that the content of beta carotene decreased with the aggravation of lung cancer.
Separation of myoglobin and hemoglobin in isolated perfused pig heart
Robert Rauh M.D., Michael Hiller, Tobias Trinks, et al.
For the quantitative determination of hemoglobin concentration in heart muscle it is important to distinguish between myoglobin and hemoglobin, two dyes with very similar optical absorption properties. With an isolated perfused pig heart model and EMPHO II SSK we measured tissue spectra in the visible range before and after adding erythrocytes to the perfusate. By calculating light intensity differences we were able to show spatial hemoglobin distribution in heart muscle.
Measurement of subcutaneous adipose tissue development in children by the optical device LIPOMETER
Reinhard Moeller, Renate Horejsi, Karl Sudi, et al.
The new optical device LIPOMETER enables the non-invasive, quick and save determination of the thickness of subcutantous adipose tissue (SAT) layers (in nm) at any site of the human body. The topographic specification of 15 evenly distributed body sites allows the precise measurement of subcutaneous body fat distribution, so called subcutaneous adipose tissue topopgraphy (SAT-Top). SAT-Top was determined in more than 1000 children aging from 7 to 21 yr. We describe the SAT-Top development of these subjects through different age groups and the differences between male and female SAT-Top development in each age group. SAT layer profiles (medians of the 15 body sites) for boys and girls in age group (7-9 yr) show a very similar pattern for both sexes, followed by decreasing SAT layer thicknesses in boys and increasing values in girls in the subsequent age groups. Between age group 3 (11-13 yr) and age group 7 (19- 21 yr) male and female SAT-Top is significantly different in (almost) all body sites. We present a precise description of SAT-Top development in boys and girls, providing a basis for further investigations in different fields such as obesity, sport sciences or metabolic disorders, and suggesting the LIPOMETER technique as an appropriate measurement tool.
Improvement of resolution in detection of 3D-functional structures in isolated perfused pig heart
Robert Rauh M.D., Michael Hiller, Tobias Trinks, et al.
Subcellular structures play a decisive role in light scattering properties of tissue. Our recent efforts aimed at monitoring these structures by use of micro lightguides and scanning tissue spectroscopy technique (EMPHO II SSK) at isolated perfused organs. With application of 70micrometers lightguides at an isolated perfused pig heart model we were able to improve the resolution to a step size of 20micrometers .
Application of NIR spectroscopy in the assessment of diabetic foot disorders
Eckhard Schleicher, Uwe Hampel, Richard Freyer
Diabetic foot syndrome (DFS) is a common sequel of long-term diabetes mellitus. There is a urgent need of noninvasive, objective and quantitative diagnostic tools to assess tissue viability and perfusion for a successful therapy. NIR spectroscopy seems to be qualified to measure local capillary hemoglobin saturation of the outer extremities in patients with progressive diabetic disorders. We investigate how NIR spectroscopy can be applied to the assessment of diabetic foot problems such as neuropathy and angiopathy. Thereby we use spatially resolved spectroscopy in conjunction with a specially developed continuous-wave laser spectrometer. Comparison of intra- and interindividual measurements is expected to yield quantitative measures of local tissue viability which is a prerequisite for a successful therapy.
HIV detection by optical spectroscopy
Narahari V. Joshi, M. Doria, Honorio Medina
Reliable and economical Human Immnodeficiency Virus (HIV) testing was achieved by optical absorption spectroscopy of the core of the hair in the range of 400 nm to 800 nm. In HIV+ patients, extra optical active material is deposited in the core and optical absorption spectra, recorded in polarized radiation reveal special features, which can be used for guidance, detection, monitoring and control.
Optical body fat measurement might contribute to the search for a predictor of type-2 diabetes mellitus
Erwin Tafeit, Renate Horejsi, Karl Sudi, et al.
The optical device LIPOMETER allows for non-invasive, quick, precise and safe determination of subcutaneous fat distribution, so-called subcutaneous adipose tissue topography (SAT-Top). Previously we showed how the high-dimensional SAT-Top information of women with type-2 diabetes mellitus (NIDDM) and a health control group can be analysed and represented in low-dimensional plots by applying special artificial neural networks (ANNs). Three top-down sorted subcutaneous adipose tissue compartments were determined (upper trunk, lower trunk, legs). NIDDM women provided significantly higher upper trunk obesity and significantly lower leg obesity (apple type), as compared with their healthy control group. Now we apply those ANN results on SAT-Top measurements of young and healthy women, comparing their individual subcutaneous fat pattern to the body fat distribution of NIDDM women and to the normal fat development of healthy women. Some of these young and healthy women provide a subcutaneous fat distribution very similar to the SAT-Top results of NIDDM women, which might increase their risk for this disease later in life.
Postdeadline Session
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Time-resolved fluorescence studies of porphycene and tetrasulfonated phthalocyanine dyes in varying solvents
Sarah L. Gundy, Wilhelm J.M. van der Putten, Andrew Shearer, et al.
Various chemicals used for photodynamic therapy, a promising treatment for cancer, exhibit high fluorescence yields, which can be used for tumour detection. For a chosen few such compounds fluorescence lifetimes, absorption, and steady state fluorescence spectra were measured at different concentrations (ranging from 10-5 M to 10-8 M) in a variety of solvents. The lifetimes were repeated at three different concentrations (ranging from 10-5 M to 10-6 M) in suspensions of 3T3 fibroblast cells.
Near-infrared spectroscopy (NIRS) as a diagnostic tool in patients with suspected stroke or traumatic brain injury
Sonja Goldberg, Carsten Lott, M. Ostermeyer, et al.
Near-Infrared Spectroscopy (NIRS) as a diagnostic tool in patients with suspected stroke or brain injury S. Goldberg, C. Lott, M. Ostermeyer, H.-J. Hennes Absorption of Near-Infrared (NIR) light in the brain is mainly caused by hemoglobin. Superficial intracranial hematoma with a higher concentration of hemoglobin causes a higher absorption in NIRS. The existence of hemorrhage can be demonstrated by the difference of optical density, comparing identical measuring points at both hemispheres of the brain: absorption of NIR light is greater at the side of the hemorrhage, causing less reflection in NIRS. In a prospective, blinded study, 100 patients who were scheduled for CCT-scan for brain injury or symptoms of stroke have been measured by NIRS. The measurement results were proved by the CCT-diagnosis. A sensitivity of the NIR measurement of 65% and a specificity of 87% was achieved including all patients with any pathology, whereas the subgroup of 58 patients with suspected superficial hematoma and without other pathology showed pathologic findings by NIRS in all of 16 patients indicating superficial bleeding by CCT, pathology could be excluded by NIRS and CCT in 41 patients, one false positive and no false negative result. The results (sensitivity 98%, specificity 100%) support the hypothesis that NIRS is a reliable device for the detection of superficial intracranial hematoma.
Preliminary results from multicenter clinical trials for detection of cervical squamous intraepithelial lesions using a novel full-field evoked-tissue-flourescence-based imaging instrument
Anupam K. Dattamajumdar, D. Wells, Julie R. Parnell, et al.
We report preliminary results from a multi-center trial of evaluating the performance of a novel, full-field multi-spectral tissue fluorescence imaging system (CerviscanTM) designed to detect cervical squamous intraepithelial lesions. Spectral data from multiple regions of 48 patients enrolled from clinical performance sites in the US and Canada are included in this preliminary analysis. This includes 30 women used for the training set and 18 used for the testing set. In the testing set, 37/43 SIL and 70/80 NonSIL regions were correctly identified for a sensitivity of 86% and specificity of 87.5%. CerviscanTM locates cervical precancerous lesions with high sensitivity and specificity and has the potential to permit 'see and treat' patient management.