Predictive Medicine aims at the detection of changes in patient's disease state prior to the manifestation of deterioration or improvement of the current status. Patient-specific, disease-course predictions with >95% or >99% accuracy during therapy would be highly valuable for everyday medicine. If these predictors were available, disease aggravation or progression, frequently accompanied by irreversible tissue damage or therapeutic side effects, could then potentially be avoided by early preventive therapy. The molecular analysis of heterogeneous cellular systems (Cytomics) by cytometry in conjunction with pattern-oriented bioinformatic analysis of the multiparametric cytometric and other data provides a promising approach to individualized or personalized medical treatment or disease management. Predictive medicine is best implemented by cell oriented measurements e.g. by flow or image cytometry. Cell oriented gene or protein arrays as well as bead arrays for the capture of solute molecules form serum, plasma, urine or liquor are equally of high value. Clinical applications of predictive medicine by Cytomics will include multi organ failure in sepsis or non infectious posttraumatic shock in intensive care, or the pretherapeutic identification of high risk patients in cancer cytostatic. Early individualized therapy may provide better survival chances for individual patient at concomitant cost containment. Predictive medicine guided early reduction or stop of therapy may lower or abrogate potential therapeutic side effects. Further important aspects of predictive medicine concern the preoperative identification of patients with a tendency for postoperative complications or coronary artery disease patients with an increased tendency for restenosis. As a consequence, better patient care and new forms of inductive scientific hypothesis development based on the interpretation of predictive data patterns are at reach.

We demonstrate the application of terahertz pulsed imaging (TPI) in reflection geometry as a diagnostic aid for epithelial cancer, specifically basal cell carcinoma. Epithelial cancer, which includes skin, breast and colon cancer, accounts for about 85% of all cancers. The terahertz (THz) region is typically defined in the frequency range of 0.1-10 THz. The sensitivity of terahertz radiation to water makes TPI an ideal technique for the study of skin, particularly as cancerous tissue has been shown to contain more water than normal tissue. Twenty-one ex vivo skin samples from a previous study, which successfully identified all 17 samples exhibiting basal cell carcinoma, were analysed in detail using time-domain algorithms to determine the role of TPI as a diagnostic aid. Eight parameters were assessed, four of which were identified as uncorrelated. The samples were classified into two groups: diseased tissue, and tissue without disease. A sensitivity and specificity greater than 80 % for six of the parameters was attained. These results demonstrate the potential of TPI as a diagnostic aid.

We describe new methods for the study of zinc in biological specimens. Intracellular free zinc was determined at levels down to picomolar using an excitation ratiometric fluorescence-based biosensing approach using a carbonic anhydrase variant as transducer. A new fiber optic sensor suitable for in vivo use is also described using laser excitation and an emission ratiometric approach; the zinc concentration range of sensor response can be selected to fit the application.

A proof-of-principle prototype Vein Contrast Enhancer (VCE) has been designed and constructed. The VCE is an instrument that makes vein access easier by capturing an infrared image of peripheral veins, enhancing the vein-contrast using software image processing, and projecting the enhanced vein-image back onto the skin using a modified commercial projector. The prototype uses software alignment to achieve alignment accuracy between the captured infrared image and the projected visible image of better than 0.06 mm. Figure 1 shows the prototype demonstrated in our laboratory.

Patients diagnosed with pancreatic cancer have a 5-year survival rate of only 3%. Endoscopic imaging of the pancreas is limited by the small size of the pancreatic duct, which has an average size of 3 mm. To improve imaging capabilities for the pancreatic duct, two small catheter-based imaging systems have been developed that will fit through the therapeutic channel of a clinical endoscope and into the pancreatic duct. One is a miniature endoscope designed to provide macro-imaging of tissue with both white light reflectance and fluorescence imaging modes. The 1.75 mm diameter catheter consists of separate illumination and imaging channels. At a nominal focal distance of 10 mm, the field of view of the system is ~ 10 mm, and the corresponding in-plane resolution is 60 microns. To complement the broadfield view of the tissue, a confocal microendoscope with 2 micron lateral resolution over a field of view of 450 microns and 25 micron axial resolution has been developed. With an outer diameter of 3 mm, the catheter in this system will also fit through the therapeutic channel and into the pancreatic duct. Images of tissue with both the miniature endoscope and confocal microendoscope are presented.

Miniaturized and robust sensing modules are required for the development of portable integrated biological analysis systems or micro total analysis systems (μ-TAS). This work uses vertical cavity surface emitting lasers (VCSELs), optical emission filters and PIN photodetectors to realize a monolithically integrated, near-infrared, fluorescence detection system. The integration of these optoelectronic devices with biochips will drastically reduce cost of current systems and increase parallelism and portability. The sensor has been implemented on a micro-fluidic format, and sensitivity was evaluated. A theoretical limit of detection of IR-800 dye in methanol is reported to be 40 nM. The sensor sensitivity is limited by laser background as a result of integrating the optoelectronic elements in such close proximity. Significant reduction in laser background from reflections above the sensor is possible by increasing the distance between the sensor and optical interfaces to greater than 3 mm. Also, for distances greater than 500 microns between the sensor and optical interfaces above the sensor, it is found that background from indirect spontaneous emission is much smaller than the background caused by specular reflections of the laser.

It has been recently shown that the favorable effects of enhanced fluorescent intensities, reduced lifetimes (increased probe photostabilities), enhanced and localized rates of multiphoton excitation, and modified rates of energy transfer can occur for fluorophores or biological species of interest, in close proximity to noble metallic nano-structures and surfaces. Subsequently, nano-metal-enhanced fluorescence (NanoMEF) is yielding enormous opportunities for enhanced fluorescence sensing and imaging in microfluidics, lab-on-a-chip, clinical diagnostics, and cellular applications. NanoMEF is a through-space phenomenon relying on interaction of fluorophores with metallic nanoparticles in the presence of excitation light. MEF can be utilized to produce nanometer-size sensors, which display enhanced spectral properties, whie still potentially maintaining a probes free space-sensing functionalities. In this presentation we report our recent findings on the effects of silver nano-particles on the spectral properties of two representative fluorescent probes for pH and Ca²⁺ measurements. We demonstrate that quantum efficiencies of probes are greatly enhanced providing more reliable chemical sensing capabilities. Our findings promise a new class of potential sensors, which we believe could constitute a new breed of composite nanosensors based on metal-enhanced fluorescence and their applications in miniaturized systems.

Results of in-vitro studies of bactericidal effects of ultraviolet (UV) irradiation on strains causing drug-resistant endo-cavital infections (Enterococcus, Staphylococcus aureus, Pseudomonas aeruginosa, and others) are presented. An original technique to measure effects of UV-irradiation on bacterial growth at different wavelengths has been developed. Spectral dependences of the bactericidal effect have been observed, and spectral maxima of bactericidal efficiency have been found. Applications to curative treatments of wounds, post-surgical intra-abdominal abscesses and other diseases are discussed.

Goal: To investigate the influence of skin on the accuracy and precision of regional cerebral oxygenation measurements using CW-NIRS and to reduce the inter individual variability of NIRS measurements by normalization with data from an extra wavelength. Method: Three piglets (7.8-9.3 kg) were anesthetized, paralyzed and mechanically ventilated. Receiving optodes were placed over the left and right hemisphere (C3, C4 EEG placement code) and one emitting optode on C_z position (optode distance=1.8cm). Optical densities (OD) were measured for 3 wavelengths (767, 850, 905 nm) (OXYMON) during stable normoxic, mild and deep hypoxemic conditions (SaO₂=100%, 80% and 60%) of one minute in each region. This was repeated 3 times: all optodes with skin (condition 1); one receiving optode directly on the skull (2); emitting and also receiving optode on the skull (3). The absolute cO₂Hb, cHHb, ctHb concentrations (μmol/L) were calculated from the OD's and changes with respect to the SaO₂=100% condition were estimated. Because ODs varied over a large range, the light intensity was externally attenuated to adapt to the range of the spectrophotometer. The data were then corrected for these attenuation effects and for pathlength changes caused by skin removal using the OD at the independent wavelength (λ=975nm). Results: Removal of the skin resulted in an increase of the absorption values (average 0.25 OD in condition 2 and 0.42 OD in condition 3 with respect to condition 1). The change from normoxic to medium, and to deep hypoxic conditions produced a decrease of cO2Hb (-15, and -29 μmol/L, respectively), an increase in cHHb (+16, and +35 μmol/L) and in ctHb (+1, and +5 μmol/L). Total skin removal yielded an extra change in cO₂Hb (-5, -1 μmol/L), cHHb (+8, +9 μmol/L), and ctHb (+3, +8 μmol /L). The coefficient of variability of the absolute concentration changes was considerably decreased by the normalization of densities by the density obtained at 795 nm. Conclusion: Skin and subcutaneous layers influence the regional oxygenation measurements but the estimated concentration changes are dominated by changes of the oxygenation levels in the brain. Inter individual variability can be considerably reduced by the normalization.

A soft (silicone) probe, containing six light emitting diodes (880 nm) and three photo detectors, utilizes photoplethysmography (PPG) to monitor pulsations from the brachialis artery under an occluding cuff during deflation. When the arterial pulse returns, measured by PPG, the corresponding pressure in the cuff is determined. This pressure is assumed to equal the systolic pressure. An assessment trial was performed on 21 patients (9 women and 12 men, aged 27-69) at the Neuro-Intensive care unit. Since the patients were already provided with arterial needles, invasive blood pressure could be used as the reference. By choosing a threshold, for detecting pulses, as a fraction (4%) of the maximum amplitude, the systolic blood pressure was underestimated (-0.57 mmHg, SD 12.1). The range of systolic pressure for the patients was 95.5 - 199.0 mmHg, n=14. The method is promising, but improvements still have to be made in order to improve the technique.

Photothermal tomography (PTT) can provide volumetric images of chromophore heating. To evaluate the accuracy of PTT for blood vessel imaging, we used a computational model to simulate an object vessel at various depths and calculate resultant infrared emission frame sequences after pulsed laser excitation. We then applied an inversion algorithm to obtain three-dimensional PTT images, which were then compared with the respective modeled objects. We found that PTT can determine accurately vessel depth, but lateral and longitudinal spatial resolution degrade considerably with increasing depth. To improve the performance of PTT, we propose a simple technique to estimate the actual vessel diameter using an empirically determined, depth resolved linespread function.

For noninvasive measurement of bio-fluid substances in human body based on optical spectroscopy, optical measurement system is one of the most important parts. We studied glucose specificities by analyzing the factors in the partial least squares regression models for the two cases of reflectance and transmittance measurements. Glucose -intralipid solutions were used as the samples whose scatterer's concentrations were varied. We used intralipid concentrations of 4%, 4.08% and 4.16% in the solution and these values were comparable to tissue scattering. Temperature was maintained at 30°C during measurement. Factor analysis for reflectance data didn't show glucose absorption feature and the factors were very noisy particularly in the combination band. It is speculated that light does not have enough information of glucose since the pathlength in reflectance is very short. On the other hand, the factors obtained from the PLS analysis of transmittance revealed glucose signatures. We suggest that transmittance measurement is preferred for in vivo glucose monitoring than reflectance measurement.

Time resolved detection and analysis of the skin back-scattered optical signals (reflection photoplethysmography or PPG) provide rich information on skin blood volume pulsations and can serve for cardiovascular assessment. The multichannel PPG concept has been developed and clinically verified in this work. Simultaneous data flow from several body locations allows to study the heartbeat pulse wave propagation in real time and to evaluate the vascular resistance. Portable two- and four-channel PPG monitoring devices and special software have been designed for real-time data acquisition and processing. The multi-channel devices were successfully applied for cardiovascular fitness tests and for early detection of arterial occlusions.

Selection of infrared (IR) detector is a key consideration in designing an experimental setup for temperature depth profiling using pulsed photothermal radiometry (PPTR). In addition to common detector characteristics, such as the spectral response, detector noise, and response speed, application-specific details must be taken into account to ensure optimal system performance. When comparing detectors with different spectral responses, blackbody emission characteristics must be considered in terms of influence on radiometric signal amplitude, as well as on background shot noise. In PPTR, optical penetration depth of the sample in the acquisition spectral band is also an important factor, affecting the stability of the temperature profile reconstruction. Moreover, due to spectral variation of IR absorption coefficient in watery tissues, the acquisition band must be appropriately narrowed to ensure the validity of the customary approximation of a constant absorption coefficient value in signal analysis. This reduces the signal-to-noise ratio, adversely affecting the stability and quality of the temperature profile reconstruction. We present a performance analysis of PPTR depth profiling in human skin using commercially available IR detectors (InSb, HgCdTe), operating in different spectral bands. A measurement simulation example, involving a simple, hyper-Gaussian temperature profile, and realistic noise levels, illustrates their expected performance.

Optical coherence tomography (OCT) is an imaging modality capable of acquiring cross-sectional images of tissue using back-reflected light. Conventional OCT images have a resolution of 10-15μm, and are thus best suited for visualizing tissue layers and structures. OCT images of collagen (with and without endothelial cells) have no resolvable features and may appear to simply show an exponential decrease in intensity with depth. However, examination of these images reveals that they display a characteristic repetitive structure due to speckle. The purpose of this study is to evaluate the application of statistical and spectral texture analysis techniques for differentiating living and non-living tissue phantoms containing various sizes and distributions of scatterers based on speckle content in OCT images. Statistically significant differences between texture parameters and excellent classification rates were obtained when comparing various endothelial cell concentrations ranging from 0 cells/ml to 25 million/ml. Statistically significant results and excellent classification rates were also obtained using various sizes of microspheres with concentrations ranging from 0 microspheres/ml to 500 million microspheres/ml. This study has shown that texture analysis of OCT images may be capable of differentiating tissue phantoms containing various sizes and distributions of scatterers.

Finding malignant cells in Pap smear images is a "needle in a haystack"-type problem, tedious, labor-intensive and error-prone. It is therefore desirable to have an automatic screening tool in order that human experts can concentrate on the evaluation of the more difficult cases. Most research on automatic cervical screening tries to extract morphometric and texture features at the cell level, in accordance with the NIH "The Bethesda System" rules. Due to variances in image quality and features, such as brightness, magnification and focus, morphometric and texture analysis is insufficient to provide robust cervical cancer detection. Using a microscopic spectral imaging system, we have produced a set of multispectral Pap smear images with wavelengths from 400 nm to 690 nm, containing both spectral signatures and spatial attributes. We describe a novel scheme that combines spatial information (including texture and morphometric features) with spectral information to significantly improve abnormal cell detection. Three kinds of wavelet features, orthogonal, bi-orthogonal and non-orthogonal, are carefully chosen to optimize recognition performance. Multispectral feature sets are then extracted in the wavelet domain. Using a Back-Propagation Neural Network classifier that greatly decreases the influence of spurious events, we obtain a classification error rate of 5%. Cell morphometric features, such as area and shape, are then used to eliminate most remaining small artifacts. We report initial results from 149 cells from 40 separate image sets, in which only one abnormal cell was missed (TPR = 97.6%) and one normal cell was falsely classified as cancerous (FPR = 1%).

Based on an in-vitro preparation of an adult human lung combined with high-resolution tomography we developed a realistic graph representation of the bronchial tree of a particular human lung. The graph contains topological information about spatial coordinates, connectivities, diameters and branching angles of 1453 bronchi up to the 17th Horsfield order, and is characterized by asymmetric and multifractal properties. This geometrical model was the basis for the development of an unstructured, multiphase CFD model of the trachea and upper airways. This is directly relevant to research in that intricate anatomical system geometries are employed. Based on medical imaging data CFD modeling associated with complex moving geometries, multi-phase/multi-species physics, and turbulence is incorporated. We contrast this approach with the use of mass-transport equations that describe the gas transport axially. Results show that many of the transport processes within the airways depend quite sensitively on the geometry of the bronchial bifurcations and the structure of the boundaries.

Osteoarthritis is a prevalent medical condition that presents a diagnostic and therapeutic challenge to physicians today because of the inability to assess the integrity of the articular cartilage early in the disease. Polarization sensitive optical coherence tomography (PS-OCT) is a high resolution, non-contact imaging modality that provides cross-sectional images with additional information regarding the integrity of the collagen matrix. Using PS-OCT to image provides information regarding thickness of the articular cartilage and gives an index of biochemical changes based on alterations in optical properties (i.e. birefringence) of the tissue. We demonstrate initial experiments performed on specimens collected following total knee replacement surgery. Articular cartilage was imaged using a 1310 nm PS-OCT system where both intensity and phase images were acquired. PS-OCT images were compared with histology, and the changes in tissue optical properties were characterized. Analysis of the intensity images demonstrates differences between healthy and diseased cartilage surface and thickness. Phase maps of the tissue demonstrated distinct differences between healthy and diseased tissue. PS-OCT was able to image a gradual loss of birefringence as the tissue became more diseased. In this way, determining the rate of change of the phase provides a quantitative measure of pathology. Thus, imaging and evaluation of osteoarthritis using PS-OCT can be a useful means of quantitative assessment of the disease.

The purpose of this study is to verify by Receiver Operating Characteristics (ROC) a mathematical model supporting the hypothesis that IUGR can be diagnosed by estimating growth velocity. The ROC compare computerized simulation results with clinical data from 325 pregnant British women. Each patient had 6 consecutive ultrasound examinations for fetal abdominal circumference (fac). Customized and un-customized fetal weights were calculated according to Hadlock’s formula. IUGR was diagnosed by the clinical standard, i.e. estimated weight below the tenth percentile. Growth velocity was estimated by calculating the changes of fac (Dz_fac/dt) at various time intervals from 3 to 10 weeks. Finally, ROC was used to compare the methods. At 3~4 weeks scan interval, the area under the ROC curve is 0.68 for customized data and 0.66 for the uncustomized data with 95% confidence interval. Comparison between simulation data and real pregnancies verified that the model is clinically acceptable.

The objective of this study is to characterize the quantum efficiency of a digital x-ray imaging system. This system is designed for small animal experiments. It is equipped with an x-ray tube with a Be-filtered tungsten target, 0.02 mm focal spot and 0.3 mA operating current. The fiber optically coupled CCD module, through a scintillating screen, covers a field of 5 cm 10 cm, at 1024 2048 pixel format. To analyze the impact of x-ray photon flux and CCD electronic noise to the quantum efficiency of the system, the noise power spectrum (NPS) and detective quantum efficiency (DQE) were measured as a function of x-ray exposure and detector integration time. A BR-12 phantom was placed between the x-ray tube and the detector during measurements. The results showed consistent DQE when exposure/integration is in the range of 2 to 7 seconds (for a 0.5cm thick phantom), and 3 to 15 seconds (for a 2cm thick phantom). With a 0.5cm phantom, DQE are approximately 36.7%, 25% and 5.4% at frequencies of 0 lp/mm, 3 lp/mm and 8 lp/mm respectively. With a 2 cm BR-12 slab, hardened x-ray beam at 26 KVp doesn’t have much impact on DQE, approximately 36.2%, 27.3% and 6% for 0 lp/mm, 3 lp/mm and 8 lp/mm frequencies. In summary, the CCD based digital x-ray imaging system investigated in this study is an efficient, x-ray quantum noise limited system for small animal experiments.

Next generation nanomedicine technologies are being developed to provide for continuous and linked molecular diagnostics and therapeutics. Research is being performed to develop "sentinel nanoparticles" which will seek out diseased (e.g. cancerous) cells, enter those living cells, and either perform repairs or induce those cells to die through apoptosis. These nanoparticles are envisioned as multifunctional "smart drug delivery systems". The nanosystems are being developed as multilayered nanoparticles (nanocrystals, nanocapsules) containing cell targeting molecules, intracellular re-targeting molecules, molecular biosensor molecules, and drugs/enzymes/gene therapy. These "nanomedicine systems" are being constructed to be autonomous, much like present-day vaccines, but will have sophisticated targeting, sensing, and feedback control systems-much more sophisticated than conventional antibody-based therapies. The fundamental concept of nanomedicine is to not to just kill all aberrant cells by surgery, radiation therapy, or chemotherapy. Rather it is to fix cells, when appropriate, one cell-at-a-time, to preserve and re-build organ systems. When cells should not be fixed, such as in cases where an improperly repaired cell might give rise to cancer cells, the nanomedical therapy would be to induce apoptosis in those cells to eliminate them without the damagin bystander effects of the inflammatory immune response system reacting to necrotic cells or those which have died from trauma or injury. The ultimate aim of nanomedicine is to combine diagnostics and therapeutics into "real-time medicine", using where possible in-vivo cytometry techniques for diagnostics and therapeutics. A number of individual components of these multi-component nanoparticles are already working in in-vitro and ex-vivo cell and tissue systems. Work has begun on construction of integrated nanomedical systems.