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Matrix-assisted laser desorption ionization (MALDI) mass spectrometry imaging (MSI) brings unique combined information on molecular identity and molecular distribution of a sample surface. During the past decade, it has matured and is now routinely employed for biomedical tissue sections analysis. However, owing to the high molecular complexity of tissue, MALDI-MSI suffers from ionization suppression effects. This directly results in a reduced ability to detect low-abundant molecular species. At the same time, the spatial resolution of separation techniques can be insufficient for an unambiguous determination of the local composition of a mixture. As analytical separation techniques can significantly reduce ion suppression, and MALDI-MSI has an ability to improve their spatial resolution, the two analytical approaches can successfully be combined in a pursuit of comprehensive local sample composition information. In the following review we summarize strategies of mutually beneficial combinations of MALDI-MSI and different separation techniques and discuss limitations and future developments.

FTIR microscopy is a powerful technique which has become popular due to its ability to provide complementary information during histopathological assessment of biomedical tissue samples. Recently however, questions have been raised on the suitability of the transflection mode of operation for clinical diagnosis due to the so called Electric Field Standing Wave (EFSW) effect. In this paper we compare chemical images measured in transmission and transflection from prostate tissue obtained from five different patients, and discuss the variability of the spectra acquired with each sampling modality. We find that spectra obtained in transflection undergo a non-linear distortion, i.e. non-linear variations in absorption band strength across the spectra, and that there are significant differences in spectra measured from the same area of tissue depending on the mode of operation. Principal Component Analysis (PCA) is used to highlight that poorer discrimination between benign and cancerous tissue is obtained in transflection mode. In addition we show that use of second derivatives, while qualitatively improves spectral discrimination, does not completely alleviate the underlying problem.

This study describes a basic theory for reconstructing pure Raman signals of materials composing a multilayer sample from Raman spectra obtained using two types of miniaturized Raman probes. An illustrative example is demonstrated using a multilayer system of samples composed of the transparent plastics polymethylmethacrylate (PMMA) and polyethylene (PE) as a model of thin-layered biomedical tissues. When the same region of an object is measured using Raman probes with different focal properties, the Raman spectra provide different depth profile information depending on the level of light penetration. Thus, a detailed comparison of the spectra can provide an interesting opportunity to probe the differences between the layers. A simple analytic form is presented for reconstructing the pure Raman spectra of the embedded layer. The method applies an understanding of the Raman sampling volume in layered transparent materials to the interpretation of Raman spectra experimentally measured by multiple probes. The basic theory described here is necessary for the expansion of the technique to turbid media, such as biological samples, where light-scattering effects must be considered. The potential applications of the proposed method include material and catalyst subsurface probing through different embedded materials, such as assessment of silicon wafers, effective noninvasive screening for catalyst synthesis, and biomedical tissue research.

A specialized transient digitizer system was developed for spectroscopic collection of fluorescence wavelength-time matrices (WTMs) from biological tissues. The system is compact, utilizes fiber optic probes for clinical compatibility, and offers rapid collection of high signal-to-noise ratio (>100) time- and wavelength- resolved fluorescence. The system is compatible with excitation sources operating in excess of 25 kHz. Wavelength-resolved measurement range is 300?800 nm with ≥ 0.01 nm steps. Time-resolved measurement depth is 128 ns with fixed 0.2 ns steps. The information-rich WTM data provides comprehensive fluorescence sensing capabilities, as demonstrated on tissue simulating phantoms. Extracting wavelength-resolved fluorophore lifetimes illustrates the potential of using the technology to resolve exogenous or endogenous fluorophore contributions in tissue samples in a clinical setting for tissue diagnostics and monitoring.

In this work, a prototype polyvinylidene fluoride (PVDF) palpation sensor has been developed. The sensor aims to measure stiffness, which is one of the information of biomedical tissue by palpation. The sensor is composed of two PVDF films, a silicone cylindrical column, and an aluminum cylinder. And the classification of hardness is concerned with the ratio of these PVDF outputs. In this paper, the output behavior of the palpation sensor was evaluated in detail by the experimental and numerical approach, and the suitable design to diagnose by the stiffness of tissue was investigated. Using the finite element analysis, the sensor output behavior was predicted. It is confirmed that the analysis is available for investigation of the dimension and the limitation of the sensor against the measuring object.

Fluorescence lifetime imaging microscopy is a technique in which the fluorescence lifetime(s) of a fluorophore is measured at each spatially resolvable element of a microscope image. Imaging of fluorescence lifetimes enables biochemical reactions to be followed at each microscopically resolvable location within the cell. FLIM has thus become very useful for biomedical tissue imaging. Global analysis [1] is a method of recovering fluorescence decay parameters from either time-resolved emission spectra to yield Decay-Associated Spectra [2], or equivalently, from FLIM datasets to yield Decay-Associated Images. Global analysis offers a sensitive and non-invasive probe of metabolic state of intracellular molecules such as NADH. Using prior information, such as the spatial invariance of the lifetime of each fluorescent species in the image, to better refine the relevant parameters, global analysis can recover lifetimes and amplitudes more accurately than traditional pixel-by-pixel analysis. Here, we explain a method to analyze FLIM data so that more accurate lifetimes and DAIs can be computed in a reasonable time. This approach involves coupling an iterative global analysis with linear algebraic operations. It can be successfully applied to image, e.g. metabolic states of live cardiac myocytes, etc.

Optical topography is a brain function imaging technology based on near-infrared spectroscopy, whereby changes in oxygenated hemoglobin (oxy-Hb) and deoxygenated hemoglobin (deoxy-Hb) are observed. There are several components other than hemoglobin in biomedical tissue such as cytochrome oxidase (cyt-ox) and water, and it is important to measure them. We investig ated the possibilities of multi-wavelength measurement of the changes in oxy- and deoxy-Hb, the redox state of cyt-ox, and water based on a modified Beer-Lambert law. According to error propagation theory, we searched for the wavelength combination where the estimation errors were minimal in the wavelength range from 650 to 900 nm under several conditions of measured components and number of wavelengths. Next, using the experimental data, we performed the same search. The signal-to-noise ratio (SNR) loss depended on measured components and wavelengths used in the measurement. We calculated the necessary improvement in precision of absorbance measurement when we estimated the changes in the redox state of cyt-ox and water, for maintaining the same level of SNRs in the hemoglobin-only measurement. The measurements of both the redox state of cyt-ox and water were not practical because the SNR losses of Hb became more than 30 dB, while the measurement where only one of them was performed was more feasible. We calculated the required ratio of absorbance change to its noise for the acquisition of cyt-ox at the same SNR of oxy-hemoglobin in hemoglobin-only measurements when the absorbance change caused by cyt-ox was assumed to be one tenth of that of oxy-hemoglobin. Keywords: Optical topography, multi-wavelength measurement, hemoglobin, cytochrome oxidase, water, signal-to-noise ratio

In this work, a prototype Polyvinylidene Fluoride (PVDF) tactile sensor for endoscopic application has been developed. The sensor aims to measure hardness, which is one of the information of tactile perceptions, of biomedical tissue. This sensor is composed of two PVDF films, a silicone cylindrical column, and an aluminum cylinder. And the classification of hardness is concerned with the ratio of these PVDF outputs. In this paper, two sensors are fabricated using two silicone cylindrical columns with different Young's modulus. The performance evaluation of each sensor is conducted using 6 silicone rubbers as measuring object. The experimental results correspond with the simplified theoretical analysis and the proposed sensor can distinguish a difference of elastic property.

Spectral-Domain Optical Coherence Tomography (SDOCT) allows for in-vivo video-rate investigation of biomedical tissue depth structure with the purpose of non-invasive optical diagnostics. In ophthalmic applications, it has been suggested that Optical Coherence Tomography (OCT) can be used for diagnosis of glaucoma by measuring the thickness of the Retinal Nerve Fiber Layer (RNLF). We present here an automated method for determining the RNFL thickness map from a 3-D dataset. Boundary detection has been studied since the early days of computer vision and image processing, and different approaches have been proposed. The procedure described here is based on edge detection using a deformable spline (snake) algorithm. As the snake seeks to minimize its overall energy, its shape will converge on the image contour, the boundaries of the nerve fiber layer. In general, the snake is not allowed to travel too much, and therefore, proper initialization is required. The snake parameters, elasticity, rigidity, viscosity, and external force weight are set to allow the snake to follow the boundary for a large number of retinal topographies. The RNFL thickness map is combined with an integrated reflectance map of the retina and retinal cross-sectional images (OCT movie), to provide the ophthalmologist with a familiar image for interpreting the OCT data. The video-rate capabilities of our SDOCT system allow for mapping the true retinal topography since the motion artifacts are significantly reduced as compared to slower time-domain systems.

Today's fast developing technological based society places ever accelerating demands for new materials and materials processing methods. Leading edge fields as diverse as biomedical tissue engineering, quantum device, optical and magnetic information storage technology as well as immobilization of actinides, all require nanoscale engineering through controlled materials modification. The evolution of these advances from the research science stage to the industrial applications is a particular challenging task. Amongst the beam processing methods for materials modification MeV ions occupy a unique place. They interact strongly with both the atomic and electronic structures of the target material to produce a broad plethora of modifications with well-defined penetration characteristics. These modifications can be precisely controlled because MeV ion can be steered and focused using electrostatic and magnetic fields and also close process control is possible because their delivery can be monitored electrically. Materials engineering with MeV ions is described in this chapter with some practical examples of their use in advanced materials.

Background and Objective: The detailed multivariate analysis of endometrial tissue fluorescence spectra was done. Spectra underlying features and classification algorithm were analyzed. An effort has been made to determine the importance of neopterin component in endometrial premalignization. Study Design/Materials and Methods: Biomedical tissue fluorescence was measured by excitation with the Nd YAG laser third harmonic. Multivariate analysis techniques were used to analyze fluorescence spectra. Biomedical optics group at Vilnius University analyzed the neopterin substance supplied by the Institute of Medical Chemistry and Biochemistry of Innsbruck University. Results: Seven statistically significant spectral compounds were found. The classification algorithm classifying samples to histopathological categories was developed and resulted in sensitivity of 80% and specificity 93% for malignant vs. hyperplastic and normal. Conclusions: Fluorescence spectra could be classified with high accuracy. Spectral variation underlying features can be extracted. Neopterin component might play an important role in endometrial hyperplasia development.

Imaging mass spectrometry is currently receiving a significant amount of attention in the mass spectrometric community. It offers the potential of direct examination of biomolecular patterns from cells and tissue. This makes it a seemingly ideal tool for biomedical diagnostics and molecular histology. It is able to generate beautiful molecular images from a large variety of surfaces, ranging from cancer tissue sections to polished cross sections from old-master paintings. What are the parameters that define and control the implications, challenges, opportunities, and (im)possibilities associated with the application of imaging MS to biomedical tissue studies. Is this just another technological hype or does it really offer the hope to gain new insights in molecular processes in living tissue? In this critical insight this question is addressed through the discussion of a number of aspects of MS imaging technology and sample preparation that strongly determine the outcome of imaging MS experiments.