Classification of rheumatoid joint inflammation based on laser imaging

We describe a classification system for a novel imaging method for arthritic finger joints. The basis of this system is a laser imaging technique which is sensitive to the optical characteristics of finger joint tissue. From the laser images acquired at baseline and follow-up, finger joints can automatically be classified according to whether the inflammatory status has improved or worsened. To perform the classification task, various linear and kernel-based systems were implemented and their performances were compared. Based on the results presented in this paper, we conclude that the laser-based imaging permits a reliable classification of pathological finger joints, making it a sensitive method for detecting arthritic changes.     

Frequency-domain optical tomographic imaging of arthritic finger joints

We are presenting data from the largest clinical trial on optical tomographic imaging of finger joints to date. Overall we evaluated 99 fingers of patients affected by rheumatoid arthritis (RA) and 120 fingers from healthy volunteers. Using frequency-domain imaging techniques we show that sensitivities and specificities of 0.85 and higher can be achieved in detecting RA. This is accomplished by deriving multiple optical parameters from the optical tomographic images and combining them for the statistical analysis. Parameters derived from the scattering coefficient perform slightly better than absorption derived parameters. Furthermore we found that data obtained at 600 MHz leads to better classification results than data obtained at 0 or 300 MHz.     

The development of a finger joint phantom for the optical simulation of early inflammatory rheumatic changes

A series of 5-aminomethinimino-3-methyl-4-isoxazolecarboxylic acid phenylamides 4 has been prepared by condensation of 5-amino-3-methyl-4-isoxazolecarboxylic acid phenylamides 1 with trichloroacetic aldehyde. Alcoholysis of trichloro derivatives 2 gave 5-alkoxymethine derivatives 3 which, on reaction with an appropriate amine, formed the corresponding compounds 4. The compounds obtained were evaluated for their immunological activity. The properties of three compounds, described in this report, permitted inhibition of the immune response in all possible ways: diminishing both types of immune response (4d), humoral immune response (4a), or cellular immune response (4c). Preparation 4d is comparable in its effectiveness to CsA, so it may be potentially used as an agent for prolongation of the function of transplanted organs. Two other compounds may potentially be used in cases where only one type the immune response is required for combating pathogen invasion.     

The spatial resolution of near-field optical microscope onchromosomes and cell traces

The investigation of biological samples in molecular medicine and biology by near-field optical microscopy is subject to nonconstant experimental conditions, such as humidity and elasticity. Contrary to far-field microscopy, the obtainable spatial resolution in scanning near-field optical microscopy (SNOM) greatly depends on the specific experimental conditions. The experimental determination of the modulation transfer function (MTF), therefore, uses regular solid-state structures. This paper introduces a method for the approximate in situ determination of the MTF using, as an example, SNOM transmission measurements of metaphase humane chromosomes and cell traces. The method has its origins in the linear system transfer theory. In order to eliminate effects of nonconstant optical near-field conditions, the transfer function is determined from the properties of the light source and the measured intensity function at the edge of a chromosome or cell trace, which depends on the transmission of the probe     

Quantitative optical biopsy of liver tissue ex vivo

The intensity of the intrinsic autofluorescence of the reduced form of nicotineamide adenine dinucleotid (NADH) of biological tissue depends on the local, cellular concentration of this coenzyme. It plays a dominant role in the Krebs cycle and, therefore, serves as an indicator for the vitality of the observed cells. Due to the individually and locally varying boundary conditions and optical tissue properties, which are scattering coefficients, absorption coefficients and an anisotropy factor g, the fluorescence signal needs to be rescaled. Rescaling methods use for instance the Kubelka-Munk theory or the photon migration theory. Our rescaling method is partly based on measurements and partly theoretically derived. By combining four methods, i.e., laser-induced fluorescence (LIF) of the time-resolved signal, biochemical concentration measurements. Monte Carlo simulations with typical optical parameters and microscopic investigations, we demonstrate that simultaneous detection of the fluorescence and backscattering signal can easily and accurately provide rescaled, quantitative values for the NADH concentrations     

Multipixel system for gigahertz frequency-domain optical imaging of finger joints

Frequency-domain optical imaging systems have shown great promise for characterizing blood oxygenation, hemodynamics, and other physiological parameters in human and animal tissues. However, most of the frequency domain systems presented so far operate with source modulation frequencies below 150 MHz. At these low frequencies, their ability to provide accurate data for small tissue geometries such as encountered in imaging of finger joints or rodents is limited. Here, we present a new system that can provide data up to 1 GHz using an intensity modulated charged coupled device camera. After data processing, the images show the two-dimensional distribution of amplitude and phase of the light modulation on the finger surface. The system performance was investigated and test measurements on optical tissue phantoms were taken to investigate whether higher frequencies yield better signal-to-noise ratios (SNRs). It could be shown that local changes in optical tissue properties, as they appear in the initial stages of rheumatoid arthritis in a finger joint, are detectable by simple image evaluation, with the range of modulation frequency around 500 MHz proving to yield the highest SNR.