Tissue Blood Content Research Articles

Fast estimation of adult cerebral blood content and oxygenation with hyperspectral time-resolved near-infrared spectroscopy.

Near-infrared spectroscopy (NIRS) can measure tissue blood content and oxygenation; however, its use for adult neuromonitoring is challenging due to significant contamination from their thick extracerebral layers (ECL; primarily scalp and skull). This report presents a fast method for accurate estimation of adult cerebral blood content and oxygenation from hyperspectral time resolved NIRS (trNIRS) data. A two-phase fitting method, based on a two-layer head model (ECL and brain), was developed. Phase 1 uses spectral constraints to accurately estimate the baseline blood content and oxygenation in both layers, which are then used by Phase 2 to correct for the ECL contamination of the late-arriving photons. The method was validated with in silico data from Monte-Carlo simulations of hyperspectral trNIRS in a realistic model of the adult head obtained from a high-resolution MRI. Phase 1 recovered cerebral blood oxygenation and total hemoglobin with an accuracy of 2.7 ± 2.5 and 2.8 ± 1.8%, respectively, with unknown ECL thickness, and 1.5 ± 1.4 and 1.7 ± 1.1% when the ECL thickness was known. Phase 2 recovered these parameters with an accuracy of 1.5 ± 1.5 and 3.1 ± 0.9%, respectively. Future work will include further validation in tissue-mimicking phantoms with various top layer thicknesses and in a pig model of the adult head before human applications.

A Non-radiometric Approach to Determine Tissue Vascular Blood Volume in Biodistribution Studies.

The aim of this research was to develop a reliable non-radiometric method to measure the residual blood in tissue without the need for perfusion or radiometric measurements in biodistribution studies. It was found that the perfusion method not only was ineffective in removing blood from tissue, but also introduced additional variability in the determination of tissue drug exposure and was not reproducible across studies. In addition, the use of hemoglobin as an endogenous protein and biomarker for tissue blood content was studied and it was found that hemoglobin measurement in tissue was not a reliable and effective approach for determination of residual blood level in tissue. To evaluate an alternative method for addressing the tissue blood level in biodistribution studies, animals were dosed with a Residual Blood Determinant Reagent (RBDR) 5min prior to tissue harvesting. The level of RBDR, an exogenous protein, was measured in whole blood homogenate and in tissue lysate. Based on the level of the RBDR, the vascular blood volume (VBV) in tissue was calculated and then the tissue exposures were corrected based on the blood volumes. The tissue VBVs measured by the RBDR method were comparable with the literature values obtained by radiometric measurements.

A Prospective, Randomized Trial for the Comparison of 19-G and 22-G Endobronchial Ultrasound-Guided Transbronchial Aspiration Needles; Introducing a Novel End Point of Sample Weight Corrected for Blood Content

BackgroundThe use of 22- or 21-gauge (G) endobronchial ultrasound (EBUS) needles are recommended for lung cancer diagnosis and staging. Performance of detailed molecular workup and programmed death ligand 1 (PD-L1) staining in lung cancer patients increases the demand for tissue. The aim of this prospective, randomized two-center trial was to compare 19-G and 22-G EBUS needles regarding tissue quality, diagnostic yield, feasibility, safety, performance, and blood content. Patients and MethodsPatients with a computed tomography scan indicative of lung cancer with mediastinal or hilar lymph node metastases were prospectively enrolled and randomized for the use of either a 19-G or a 22-G EBUS needle. A blood content score from 0 to 2 was applied. Samples were weighed, tumor cells were counted per slide, and complications and final diagnoses were documented. ResultsWe enrolled 107 patients (53 [49.5%] in the 19-G group/54 [50.5%] in the 22-G group) and samples were weighed immediately after performing EBUS. Samples obtained with a 19-G needle contained significantly more tissue (P = .0119). Non–small-cell lung cancer-infiltrated EBUS samples contained significantly more tumor cells when sampled with a 19-G needle (P = .0312). The diagnostic yield was equally adequate in both groups. Four moderate EBUS-related bleedings occurred (2 per group), hemostasis was rapidly achieved in all cases. Further complications did not occur. ConclusionEndobronchial ultrasound-guided transbronchial needle aspirations with a 19-G needle contain significantly more tissue and tumor cells per slide with a safety profile similar to 22-G needles. Further research is needed to investigate the relevance of this finding in terms of molecular analyses and PD-L1 staining.

Wavelet based feature extraction and visualization in hyperspectral tissue characterization.

Hyperspectral images of tissue contain extensive and complex information relevant for clinical applications. In this work, wavelet decomposition is explored for feature extraction from such data. Wavelet methods are simple and computationally effective, and can be implemented in real-time. The aim of this study was to correlate results from wavelet decomposition in the spectral domain with physical parameters (tissue oxygenation, blood and melanin content). Wavelet decomposition was tested on Monte Carlo simulations, measurements of a tissue phantom and hyperspectral data from a human volunteer during an occlusion experiment. Reflectance spectra were decomposed, and the coefficients were correlated to tissue parameters. This approach was used to identify wavelet components that can be utilized to map levels of blood, melanin and oxygen saturation. The results show a significant correlation (p <0.02) between the chosen tissue parameters and the selected wavelet components. The tissue parameters could be mapped using a subset of the calculated components due to redundancy in spectral information. Vessel structures are well visualized. Wavelet analysis appears as a promising tool for extraction of spectral features in skin. Future studies will aim at developing quantitative mapping of optical properties based on wavelet decomposition.

Earl Wood--a research career noted for development of novel instruments driven by the power of the indicator dilution concept.

During World War 2, Earl Wood was charged with elucidating the biomedical factors in acceleration-induced loss of consciousness experienced by pilots in high-performance aircraft. For this, he developed devices for measurement and recording of blood pressure and tissue blood content. Those data lead to the design and fabrication of successful countermeasures to acceleration-induced loss of consciousness with an inflatable "G-suit" and "M1" breath-holding maneuver. After World War 2, he utilized and modified these instruments and made use of indicator dilution techniques by continuous intracardiac blood sampling to greatly increase the specificity and sensitivity of diagnosis of intracardiac anatomic and functional abnormalities in patients with congenital heart disease. This contributed to the greatly increased success rate of open-heart surgery in the 1950s. In the 1960s, he built on the then recently available video-coupled electronic X-ray image intensifier to develop X-ray fluoroscopy-based recording of indicator dilution signals in all cardiac chambers and surrounding great vessels without the need for placing catheter tips at those locations for blood sampling. However, these blood flow-related data were of limited value, as they were not measured concurrent with myocardial functional demand for perfusion. In the 1970s, he overcame this limitation by developing a high-speed multislice X-ray imaging scanner to provide tomographic images of concurrent dynamic cardiac anatomy and the indicator dilution-based estimates of blood flow distributions. On his retirement at age 70 in 1982, he had accomplished his 2 decade-old goal of the ability to make accurate concurrent, minimally invasive, and indicator dilution-based measurement of cardiovascular structure to function relationships.

An Automatic Occlusion Device for Remote Control of Tumor Tissue Ischemia

We developed an automatic occlusion device for remote control of tumor tissue ischemia. The device consists of a flexible cannula encasing a shape memory alloy wire with its distal end connected to surgical suture. Regional tissue occlusion was tested on both the benchtop and the animal models. In the benchtop test, the occlusion device introduced quantitative and reproducible changes of blood flow in a tissue simulating phantom embedding a vessel simulator. In the animal test, the device generated a cyclic pattern of reversible ischemia in the right hinder leg tissue of a black male C57BL/6 mouse. We also developed a multimodal detector that integrates near infrared spectroscopy and electron paramagnetic resonance spectroscopy for continuous monitoring of tumor tissue oxygenation, blood content, and oxygen tension changes. The multimodal detector was tested on a cancer xenograft nude mouse undergoing reversible tumor ischemia. The automatic occlusion device and the multimodal detector can be potentially integrated for closed-loop feedback control of tumor tissue ischemia. Such an integrated occlusion device may be used in multiple clinical applications such as regional hypoperfusion control in tumor resection surgeries and thermal ablation processes. In addition, the proposed occlusion device can also be used as a research tool to understand tumor oxygen transport and hemodynamic characteristics.

T1847 Optical Fiber Spectroscopy: A Novel Application to Measure Tissue Oxygenation and Blood Content in the At Risk Gastrointestinal Anastomosis

T1847 Optical Fiber Spectroscopy: A Novel Application to Measure Tissue Oxygenation and Blood Content in the At Risk Gastrointestinal Anastomosis

Topical negative pressure therapy of a sternotomy wound increases sternal fluid content but does not affect internal thoracic artery blood flow: Assessment using magnetic resonance imaging

Topical negative pressure therapy has excellent healing effects in poststernotomy mediastinitis. Topical negative pressure therapy reduces bacterial counts, increases wound edge microvascular blood flow and granulation tissue formation, and facilitates healing. No study has yet been performed to examine the effect of topical negative pressure on the blood and fluid content in the sternal bone marrow, which is a crucial component in osteitis. Eight pigs underwent median sternotomy, left internal thoracic artery harvesting, followed by topical negative pressure treatment. Magnetic resonance imaging was used to quantify both tissue fluid and/or blood content (T2-weighted short tau inversion recovery [T2-STIR]) and internal thoracic artery blood flow (flow quantification). Before application of topical negative pressure, the T2-STIR signal intensity ratio was lower for the left than for the right hemisternum (left, 1.3; right, 2.6), indicating lower levels of tissue fluid content on the left, devascularized side. On application of topical negative pressure, the T2-STIR signal intensity ratio increased immediately for both the sternal bone and the pectoral muscle (left hemisternum after 4 minutes of topical negative pressure: 2.3), leveled off after 4 minutes, and remained unchanged for the ensuing 40 minutes, suggesting movement of fluid and/or blood into the tissue of the wound edge. Topical negative pressure did not affect blood flow in the right internal thoracic artery. T2-STIR measurements show that topical negative pressure increases sternotomy wound edge tissue fluid and/or blood content. Topical negative pressure creates a pressure gradient that presumably draws fluid from the surrounding tissue to the sternal wound edge and into the vacuum source. This "endogenous drainage" may be one possible mechanism by which osteitis is resolved by topical negative pressure in poststernotomy mediastinitis.

Monte Carlo simulation of light propagation in adult brain: influence of tissue blood content and indocyanine green

AbstractNear-infrared spectroscopy (NIRS), applied to a human head, is a noninvasive method in neurointensive care to monitor cerebral hemodynamics and oxygenation. The method is particularly powerful when it is applied in combination with indocyanine green (ICG) as a tracer substance. In order to assess contributions to the measured optical density (OD) which are due to extracerebral circulation and disturb the clinically significant intracerebral signals, we simulated the light propagation in an anatomically representative model of the adult head derived from MRI measurements with the aid of Monte Carlo methods. Since the measured OD signal depends largely on the relative blood content in various transilluminated tissues, we weighted the calculated densities of the photon distribution under baseline conditions within the tissues with the changes and aberrations of the relative blood volumes which we expect to prevail under physiological conditions. Furthermore, the influence of the IGC dye as a tracer substance was assessed. We conclude that up to about different 70% of the measured OD signal may have its origin in the tissues of interest under optimal conditions, which is mainly due to the extrapolated high relative blood content of brain tissue along with the influence of ICG.

Peripheral circulation in the hand during natural ontogeny and under the conditions of prolonged graded traction

On the basis of the data of rheovasography (RVG) and laser Doppler flowmetry, comparative analysis of age-related changes in the peripheral blood circulation in hand tissues has been performed in 36 apparently healthy subjects aged 4–30 years and in 19 patients aged 18–50 years under the conditions of prolonged traction during surgical lengthening of finger bone stumps. The age-related changes in RVG are characterized by a higher volumetric blood content of tissues in children and adolescents, a decrease in the peripheral vascular tone, and wavelike recovery of capillary blood flow during reactive hyperemia, which is evidence for an unstable capillary tone. The dynamics of RVG indices during graded stretching in vivo (distraction) shows the dominance of an enhanced peripheral tone of arterioles and venules, and the response of the hand skin capillary bed to a 3-min ischemic test is analogous to the dynamics of indices of capillary blood flow in the hand skin of children.

Assessing and influencing the fractional contribution of erythrocyte-bound 59Fe to individual 59Fe tissue content in murine 59Fe distribution studies

Background Murine proteins of iron homoeostasis are frequently manipulated to investigate the mechanisms of iron-distribution and their toxicological consequences. Beyond subtracting erythrocyte-bound 59Fe of the residual blood content determined for each tissue (subtraction method), procedures are needed to determine 59Fe distribution in murine models of, e.g. inflammation or diabetes that cause local hyperaemia and changes in microcirculation. Aim Two new methods were developed to correct total 59Fe tissue content individually for erythrocyte-bound 59Fe-labelled haem iron. Methods Iron-deficiency and iron-overload was induced in male C57BL6 mice by feeding of respective diets. Distribution of 59Fe between different tissues was determined 24 h, 14, and 28 days after intravenous injection of 59Fe trace amounts. Haem-bound 59Fe was separated from non-haem 59Fe in homogenates from all tissues by dispersion in a mix of lipophilic cyclohexanone and hydrophilic H 3PO 4 (separation method). Moreover, the reduction of 59Fe-labelled tissue blood content was determined in all organs after in vivo saline perfusion via the left ventricle (perfusion method). Results and discussion 59Fe-labelled non-haem iron determined by the separation method was not significantly different from values determined by the subtraction method, except for the iron-deficient spleen 14 and 28 days after 59Fe injection when the separation method yielded ∼20% higher values. Approximately 20% of 59Fe-labelled haem iron spilled over into the hydrophilic phase. The impact of this error decreases in parallel to 59Fe radioactivity in the residual tissue blood content: thus, it is higher in iron-deficient mice which accumulate more 59Fe in their erythrocytes than iron-adequate and iron-rich mice. For the same reason this type of error is more marked after long distribution periods and in organs with high residual blood content. Saline perfusion via the left ventricle reduced total blood content in mice to less than 10%. Liver (95%) and duodenum (94%) showed the highest removal of blood while it is lowest in spleen (66%) and lungs (69%). Conclusions The separation and the perfusion method can be used to correct the impact of erythrocyte-bound haem iron individually. A margin of error below 10% was determined for all organs except for spleen, lungs, and fat. Both methods can be applied sequentially to obtain satisfactory results in spleen, lungs, and fat.

Microwave tomography for functional imaging of extremity soft tissues: feasibility assessment

It is important to assess the viability of extremity soft tissues, as this component is often the determinant of the final outcome of fracture treatment. Microwave tomography (MWT) and sensing might be able to provide a fast and mobile assessment of such properties. MWT imaging of extremities possesses a complicated, nonlinear, high dielectric contrast inverse problem of diffraction tomography. There is a high dielectric contrast between bone and soft tissue in the extremities. A contrast between soft tissue abnormalities is less pronounced when compared with the high bone–soft tissue contrast. The goal of this study was to assess the feasibility of MWT for functional imaging of extremity soft tissues, i.e. to detect a relatively small contrast within soft tissues in closer proximity to high contrast boney areas.Both experimental studies and computer simulation were performed. Experiments were conducted using live pigs with compromised blood flow and compartment syndrome within an extremity. A whole 2D tomographic imaging cycle at 1 GHz was computer simulated and images were reconstructed using the Newton, MR-CSI and modified Born methods.Results of experimental studies demonstrate that microwave technology is sensitive to changes in the soft tissue blood content and elevated compartment pressure. It was demonstrated that MWT is feasible for functional imaging of extremity soft tissues, circulatory-related changes, blood flow and elevated compartment pressure.

A method to assess 59Fe in residual tissue blood content in mice and its use to correct 59Fe-distribution kinetics accordingly

Background Dysregulation of body iron-distribution may induce oxidative damage. To investigate the molecular mechanisms of iron homeostasis, corresponding essential genes are manipulated by many working groups. This asks for a simple method to pursue the resulting impact on body iron-distribution in mice. Aim To develop a method for the assessment of 59Fe in residual tissue blood content and to correct this influence in 59Fe body distribution studies. Methods Iron status in male adult C57BL6 mice was adjusted by feeding diets with different iron content. Fractional contribution of organs to total body weight was determined after dissection. 59Fe-labelled blood was injected in recipient mice to estimate total blood volume and residual blood content in all organs and tissues. The main experiment used these data to correct total 59Fe tissue content at six intervals after 59Fe injection (12 h–28 days). Results and discussion The sum of 59Fe in all organs was the same as determined in each mouse before dissection. 59Fe in whole blood remained constant from the 4th day after injection on, and was highest in iron-deficiency. As in other species, residual blood content was highest in spleen and lungs. Nevertheless, 59Fe in the iron-deficient spleen decreased to zero and intestinal 59Fe-content also decreased significantly over time after correction for 59Fe in residual blood. These findings suggest correct assessment of compartment sizes and 59Fe in residual blood in each organ. Conclusions Differences in 59Fe-distribution between iron status reflected changes in the expression of proteins of iron-transport and its regulation correctly. Thus, the method seems suitable to analyse body iron-distribution in consequence to genetic manipulations of murine iron homeostasis which is a prerequisite to assess possible toxicological consequences of iron supplementation.

Uptake and metabolism of plasma-derived erucic acid by rat brain

We examined the ability of erucic acid (22:1n-9) to cross the blood-brain barrier (BBB) by infusing [14-14C]22:1n-9 (170 microCi/kg, iv and icv) into awake, male rats. [1-14C]arachidonic acid (20:4n-6) [intravenous (i.v.)] was the positive control. After i.v. infusion, 0.011% of the plasma [14-14C]22:1n-9 was extracted by the brain, compared with 0.055% of the plasma [1-14C]20:4n-6. The [14-14C]22:1n-9 was extensively beta-oxidized (60%), compared with 30% for [1-14C]20:4n-6. Although 20:4n-6 was targeted primarily to phospholipid pools, 22:1n-9 was targeted to cholesteryl esters, triglycerides, and phospholipids. When [14-14C]22:1n-9 was infused directly into the fourth ventricle of the brain [intracerebroventricular (i.c.v.)] for 7 days, 60% of the tracer entered the phospholipid pools, similar to the distribution observed for [1-14C]20:4n-6. This demonstrates plasticity in the ability of the brain to esterify 22:1n-9 in an exposure-dependent manner. In i.v. and i.c.v. infused rats, a significant amount of tracer found in the phospholipid pools underwent sequential rounds of chain shortening and was found as [12-14C]20:1n-9 and [10-14C]oleic acid. These results demonstrate for the first time that intact 22:1n-9 crosses the BBB, is incorporated into specific lipid pools, and is chain-shortened.

Optical biopsy of breast tissue using differential path-length spectroscopy

Differential path-length spectroscopy (DPS) was used to determine the local optical properties of breast tissue in vivo. DPS measurements were made on healthy and malignant breast tissue using a fibre-optic needle probe, and were correlated to the histological outcome of core-needle biopsies taken from the same location as the measurements. DPS yields information on the local tissue blood content, the local blood oxygenation, the average micro-vessel diameter, the β-carotene concentration and the scatter slope. Our data show that malignant breast tissue is characterized by a significant decrease in tissue oxygenation and a higher blood content compared to normal breast tissue.

Optical spectroscopy and prevention of deleterious cerebral vascular effects of ethanol by magnesium ions

Previously, it has been suggested that acute ethanol (alcohol) administration can result in concentration-dependent vasoconstriction and decreased cerebral blood flow. Here, we present in vivo results using rapid (240 nm/min) optical backscatter measurements, with an intact cranial preparation in the rat, indicating that acute infusion of ethanol directly into the rat brain rapidly produces dose-dependent vasoconstriction of the cerebral microcirculation associated with a pronounced reduction in tissue blood content, pronounced rises in deoxyhemoglobin, significantly increased levels of reduced cytochrome oxidase and microvascular damage as the dose increases. Furthermore, we present in vivo experiments demonstrating the capability of magnesium ions (Mg 2+) to attenuate and prevent these deleterious responses. Optical backscatter spectra (500–800 nm) were obtained by directing a single sending and receiving fiber to a portion of the left parietal cranium (in anesthetized rats), shaved to a translucent appearance to facilitate optical penetration. In the absence of added Mg 2+, infusion of a 10% solution of ethanol at 0.34 ml/min (∼26.8 mg/min) produced prompt vasoconstriction as evidenced by a greater than 90% loss of oxyhemoglobin from the field-of-view and increases in levels of reduced cytochrome oxidase to between 50% and >90%. These effects were partially, to nearly completely, attenuated by the addition of MgCl 2 to the infusate containing added ethanol. Of special interest was the observation that attenuation of the vasoconstrictive effect of ethanol by Mg 2+ persisted despite a subsequent ethanol challenge without added Mg 2+. The results obtained demonstrate that, depending on dose, ethanol can produce prompt and severe vasoconstriction of the intact cerebral microcirculation and that infusion of moderate doses of Mg 2+ can largely attenuate and prevent this response. We conclude that appreciable, graded changes in cerebral cytochrome oxidase aa 3, blood volume and the state of hemoglobin occur at minimal tissue levels of ethanol which can be modulated by Mg 2+.

Fatal parvovirus myocarditis in a 5-year-old girl

Infection with parvovirus B19 is common in children and typically causes mild illness. We report here the case of a 5-year-old girl who died suddenly, 2 weeks after the clinical diagnosis of a parvoviral infection (erythema infectiosum). Microscopic examination of the heart showed severe myocarditis with extensive T-cell and macrophage infiltration. Cultures, serology, and molecular analyses of serum for enteroviridae, adenovirus, influenza, varicella zoster, cytomegalovirus, and herpes simplex viruses were negative. Quantitative polymerase chain reaction (PCR) analysis for parvovirus B19 in peripheral blood, however, showed active infection (91,000 genomes/mL serum; 2.4 genomes/mononuclear cell). Despite the presence of myocarditis, immunostaining for parvoviral surface antigens was negative in the heart. Quantitative PCR analysis of paraffin sections showed that myocardial parvoviral content was significantly less than that of the normal appearing kidney and within the range predicted simply by tissue blood content. Thus, parvovirus B19 infection can be complicated by fatal myocarditis. Because the virus does not appear to have infected the heart, per se, we speculate that myocarditis arose from immunological cross-reaction to epitopes shared between the virus and the myocardium. HUM PATHOL 32:342-345. Copyright © 2001 by W.B. Saunders Company

Modelling the sampling volume for skin blood oxygenation measurements.

The absolute quantified measurement of haemoglobin skin blood saturation from collected reflectance spectra of the skin is complicated by the fact that the blood content of tissues can vary both in the spatial distribution and in the amount. These measurements require an understanding of which vascular bed is primarily responsible for the detected signal. Knowing the spatial detector depth sensitivity makes it possible to find the best range of different probe geometries for the measurements of signal from the required zones and group of vessels inside the skin. To facilitate this, a Monte Carlo simulation has been developed to estimate the sampling volume offered by fibre-optic probes with a small source-detector spacing (in the current report 250 microm, 400 microm and 800 microm). The optical properties of the modelled medium are taken to be the optical properties of the Caucasian type of skin tissue in the visible range of the spectrum. It is shown that, for a small source-detector separation (800 microm and smaller), rough boundaries between layers of different refractive index can play a significant role in skin optics. Wavy layer interfaces produce a deeper and more homogeneous distribution of photons within the skin and tend to suppress the direct channelling of photons from source to detector. The model predicts that a probe spacing of 250 microm samples primarily epidermal layers and papillary dermis, whereas spacings of 400-800 microm sample upper blood net dermis and dermis.

Physical model for the spectroscopic analysis of cortical intrinsicoptical signals

We used Monte Carlo simulations and the diffusion approximation to estimatecorrection terms for the analysis of reflectance spectra of cortical intrinsicoptical signals. These corrections depend on scattering and absorptionproperties, i.e. they are dependent on assumptions on the tissue bloodcontent and oxygen saturation. The analysis was applied to reflectance spectraacquired during whisker barrel stimulation in the rat where attenuationspectra were converted to changes in oxygenated and deoxygenated haemoglobinconcentration. The description of the experimental data as judged by theresidual and sensitivity to variations of wavelength was considerably improvedwhen the correction terms were included. Inclusion of the correction does havea considerable impact on the time course of deoxyhaemoglobin concentrationchanges. In contrast to the calculation without correction terms, there is noindication for an early increase in deoxyhaemoglobin (`early dip'). Thisfinding might further current interpretation of the coupling between neuronalactivation and oxygen extraction and supply.

Preliminary study of in vivo autofluorescence of nasopharyngeal carcinoma and normal tissue.

In nasopharyngeal cancer, conventional white light endoscopy does not provide adequate information to detect the flat/small lesion and identify the margin of observable tumor. In the present study, we evaluate the potential of light-induced fluorescence spectroscopic imaging for the localization of cancerous nasopharyngeal tissue. We built a multiple channel spectrometer specifically for the investigation of fluorescence collected by a conventional endoscopic system. Nasopharyngeal fluorescence were measured in vivo from 27 subjects during the routine endoscopy. The biopsy specimens for histologic analysis were taken from the tissue sites where the fluorescence were measured. Two algorithms to discriminate the nasopharyngeal carcinoma from normal tissue were created based on the good correlation between the tissue autofluorescence and histologic diagnosis. For the two-wavelength algorithm, carcinoma can be differentiated from normal tissue with a sensitivity and specificity of 93% and 92%, respectively. For the three-wavelength algorithm with compensation of variation of blood content in tissue, a sensitivity of 98% and specificity of 95% were achieved. Fluorescence endoscopic imaging used with the algorithms developed in this report is an efficient method for detecting the nasopharyngeal carcinoma.