Evaluation of E test as a rapid method for determining MICs for nutritionally variant streptococci.

E test was evaluated as an alternative rapid and simple method of MIC estimation for nutritionally variant streptococci. E test with various media was compared with conventional broth and plate dilution techniques supplemented with 0.001% (wt/vol) pyridoxal hydrochloride (vitamin B6). Of the 14 strains tested with E test, isosensitest agar supplemented with 5% defibrinated horse blood and 0.001% pyridoxal HCl, with and without 0.01% cysteine, gave complete agreement within one twofold-dilution titer of the agar reference method and between 93 and 86% agreement within one twofold-dilution titer of the broth reference method. E test MICs with other media were comparable; however, these were considerably more difficult to interpret. Use of Mueller-Hinton and Columbia-based supplemented agar showed hazy growth and double zoning around the endpoint, respectively. The addition of 0.01% (wt/vol) cysteine to media exhibited no significant effect, and incubation in 5% carbon dioxide (CO2) did not affect MICs.     

Assessment of noise in a digital image using the join-count statistic and the Moran test.

We assume that the data bits of a pixel in digital images can be divided into signal and noise bits. The signal bits occupy the most significant part of the pixel and the noise bits the least significant part. The signal part of each pixel are correlated while the noise parts are uncorrelated. Two statistical methods, the Moran test and the join-count statistic, are used to examine the noise parts. Images from three digital modalities--computerized tomography, magnetic resonance and computed radiography--are used for the evaluation of the noise bits. A residual image is formed by subtracting the original image from its smoothed version. The noise level in the residual image is then identical to that in the original image. Both statistical tests are then performed on the bit planes of the residual image. The results show that most digital images contain only 8-9 bits of correlated information. Both methods are easy to implement and fast to perform.     

A method for determination of optimal image enhancement for the detection of mammographic abnormalities

We present a paradigm for empirical evaluation of digital image enhancement algorithms for mammography that uses psychophysical methods for implementation and analysis of a clinically relevant detection task. In the experiment, the observer is asked to detect and assign to a quadrant, or indicate the absence of, a simulated mammographic structure characteristic of cancer embedded in a background image of normal breast tissue. Responses are indicated interactively on a computer workstation. The parameter values for the enhancement applied to the composite image may be varied on each trial, and structure detection performance is estimated for each enhancement condition. Preliminary investigations have provided insight into an appropriate viewing duration, and furthermore, suggest that nonradiologists may be used under this methodology for the tasks investigated thus far, for predicting parameter values for clinical investigation. We are presently using this method in evaluating several contrast enhancement algorithms of possible benefit in mammography. These methods enable an objective, clinically relevant evaluation, for the purpose of optimal parameter determination or performance assessment, of digital image-processing methods potentially used in mammography.     

A method of determining the thickness of a histologic section using a spectrophotometer

The authors show the possibility of determining the thickness of a histological section using a spectrophotometer with automatic recording of absorption spectrum. The thickness of the section in nanometers is calculated by graphic records of the sample interference pattern. Experimental setting has been defined which warrants stable results.     

Kinetic dialysis as a method for determining mixed micelle composition

A new method for the determination of the cmc using a dialysis technique which allows monomeric species to diffuse through but not micelles has been applied for determining the mixed micelle composition. The method is based on determining the amount of surfactant that diffuses through at two different times which allows for the calculation of the cmc by use of the appropriate equation. This method requires the preparation of only one concentration of solution and lends itself particularly well to the determination of the composition of mixed micelles.     

Automatic disease screening method using image processing for dried blood microfluidic drop stain pattern recognition

This paper examines programmed automatic recognition of infection from samples of dried stains of micro-scale drops of patient blood. This technique has the upside of being low-cost and less-intrusive and not requiring puncturing the patient with a needle for drawing blood, which is especially critical for infants and the matured. It also does not require expensive pathological blood test laboratory equipment. The method is shown in this work to be successful for ailment identification in patients suffering from tuberculosis and anaemia. Illness affects the physical properties of blood, which thus influence the samples of dried micro-scale blood drop stains. For instance, if a patient has a severe drop in platelet count, which is often the case of dengue or malaria patients, the blood’s physical property of viscosity drops substantially, i.e. the blood is thinner. Thus, the blood micro-scale drop stain samples can be utilised for diagnosing maladies. This paper presents programmed automatic examination of the dried micro-scale drop blood stain designs utilising an algorithm based on pattern recognition. The samples of micro-scale blood drop stains of ordinary non-infected people are clearly recognisable as well as the samples of micro-scale blood drop stains of sick people, due to key distinguishing features. As a contextual analysis, the micro-scale blood drop stains of patients infected with tuberculosis have been contrasted with the micro-scale blood drop stains of typical normal healthy people. The paper dives into the fundamental flow mechanics behind how the samples of the dried micro-scale blood drop stain is shaped. What has been found is a thick ring like feature in the dried micro-scale blood drop stains of non-ailing people and thin shape like lines in the dried micro-scale blood drop stains of patients with anaemia or tuberculosis disease. The ring like feature at the periphery is caused by an outward stream conveying suspended particles to the edge. Concentric rings (brought on by internal Marangoni flow) and deposition in the centre of the stain are patterns that were found in the dried micro-scale drop blood stain samples of ordinary healthy people.     

A procedure for image enhancement in chromosome painting

An image enhancement procedure was developed to produce high-contrast chromosome paint images. This procedure is well suited for images where brightness–contrast enhancement is subjective. Three examples are given to show that the procedure is very efficient to remove non-specific hybridization signals from the chromosome paint image. Chromosomes of roe deer contain large amounts of centromeric heterochromatic DNA. Echidna chromosomes show specific heterochromatic DNA distributed over several chromosomes. In both cases chromosome identification was hampered by bright heterochromatic regions. The enhancement tool was fully used in cross-species chromosome painting, which is the last example. The three examples show that the procedure is very simple to use and removes background in a controlled and defined manner.     

A computational method for determining tissue material properties in ovine fracture calluses using electronic speckle pattern interferometry and finite element analysis

For numerical simulations of biological processes the assignment of reliable material properties is essential. Since literature data show huge variations for each parameter, this study presents a method for determining tissue properties straight from the investigated specimens by combining electronic speckle pattern interferometry (ESPI) with finite element (FE) analysis in a two-step parameter analysis procedure. ESPI displacement data from two mid-sagittal ovine fracture callus slices under 5 N compressive load were directly compared to data from FE simulations of the respective experimental setup. In the first step a parameter sensitivity analysis quantified the influence of single tissues on the mechanical behavior of the callus specimens. In the second step, material properties (i.e. Young's moduli and Poisson's ratios) for the most dominant material of each callus specimen were determined through a parameter sampling procedure minimizing the mean local deviations between the simulated (FE) and measured (ESPI) equivalent element strains. The resulting material properties showed reasonable ranges downsizing the variability of previous published values, especially for Young's modulus which was 1881 MPa for woven bone and 16 MPa for cartilage in average. In conclusion, a numerical method was developed to determine material properties straight from independent fracture callus specimens based on experimentally derived local mechanical conditions.     

A unified noise analysis for iterative image estimation

Iterative image estimation methods have been widely used in emission tomography. Accurate estimation of the uncertainty of the reconstructed images is essential for quantitative applications. While both iteration-based noise analysis and fixed-point noise analysis have been developed, current iteration-based results are limited to only a few algorithms that have an explicit multiplicative update equation and some may not converge to the fixed-point result. This paper presents a theoretical noise analysis that is applicable to a wide range of preconditioned gradient-type algorithms. Under a certain condition, the proposed method does not require an explicit expression of the preconditioner. By deriving the fixed-point expression from the iteration-based result, we show that the proposed iteration-based noise analysis is consistent with fixed-point analysis. Examples in emission tomography and transmission tomography are shown. The results are validated using Monte Carlo simulations.     

Selection of biorthogonal filters for image compression of MR images using wavelet packets

We present an analysis of different filter banks for the compression of magnetic resonance (MR) images of the human brain using wavelet packets based on biorthogonal filters. Initially, peak signal to noise ratio (PSNR) and normalized root mean square (RMS) error criteria are calculated for a series of images compressed with a 33:1 ratio, using filter banks based on biorthogonal wavelet packets. The results lead us to choose a few of these filter banks as optimal for image compression. One of these filters is employed to compress several images at four different compression ratios: 12.5:1, 25:1, 37.5:1 and 50:1. The quality of these images was evaluated by visual analysis by a group of seven experts who graded image quality on a 0-7 scale. Results show that using these filters, we can compress images to a rate of around 30:1 without introducing noticeable differences. Other applications for these filters are currently under study and include the compression/fusion of MR image stacks in order to obtain even better reductions in the amount of data needed to reconstruct complete MRI studies.     

A new method for determining lumbar spine motion using Bayesian belief network

A Bayesian network dynamic model was developed to determine the kinematics of the intervertebral joints of the lumbar spine. Radiographic images in flexion and extension postures were used as input data for modeling, together with movement information from the skin surface using an electromagnetic motion tracking system. Intervertebral joint movements were then estimated by the graphic network. The validity of the model was tested by comparing the predicted position of the vertebrae in the neutral position with those obtained from the radiographic image in the neutral posture. The correlation between the measured and predicted movements was 0.99 (p < 0.01) with a mean error of less than 1.5°. The movement sequence of the various vertebrae was examined based on the model output, and wide variations in the kinematic patterns were observed. The technique is non-invasive and has potential to be used clinically to measure the kinematics of lumbar intervertebral movement. This work was supported by the Hong Kong Research Grant Council (Competitive Earmarked Research Grant CERG CUHK5251/04E).     

A method for toxicity screening of biomaterials using cells cultured on millipore filters.

In the present paper a tissue culture technique is described whereby the toxicity of setting and solid materials may be evaluated. A cell monolayer was established on a millipore filter which was placed on an agar medium, cell side down. Test specimens were placed on top of the millipore filter and were allowed to influence the cells through the filter for two hours. The cell reaction was assessed by incubating the cells, still adherent to the filter, for the demonstration of succinate dehydrogenase activity. Materials with a cytotoxic effect caused a zone of inhibited enzyme activity in the cell-material contact area. The filters were examined macroscopically and scores from 0 to 3 were given to grade the severity of the cell response. Unset and set silicate cement, zinc phosphate cement and an acrylic resin were tested. The results obtained were consistent and in accordance with those of previous reports. The method was simple and rapid and appeared suitable for the assay of larger test series.     

Statistical and heuristic image noise extraction (SHINE): a new method for processing Poisson noise in scintigraphic images

Poisson noise is one of the factors degrading scintigraphic images, especially at low count level, due to the statistical nature of photon detection. We have developed an original procedure, named statistical and heuristic image noise extraction (SHINE), to reduce the Poisson noise contained in the scintigraphic images, preserving the resolution, the contrast and the texture. The SHINE procedure consists in dividing the image into 4 x 4 blocks and performing a correspondence analysis on these blocks. Each block is then reconstructed using its own significant factors which are selected using an original statistical variance test. The SHINE procedure has been validated using a line numerical phantom and a hot spots and cold spots real phantom. The reference images are the noise-free simulated images for the numerical phantom and an extremely high counts image for the real phantom. The SHINE procedure has then been applied to the Jaszczak phantom and clinical data including planar bone scintigraphy, planar Sestamibi scintigraphy and Tl-201 myocardial SPECT. The SHINE procedure reduces the mean normalized error between the noisy images and the corresponding reference images. This reduction is constant and does not change with the count level. The SNR in a SHINE processed image is close to that of the corresponding raw image with twice the number of counts. The visual results with the Jaszczak phantom SPECT have shown that SHINE preserves the contrast and the resolution of the slices well. Clinical examples have shown no visual difference between the SHINE images and the corresponding raw images obtained with twice the acquisition duration. SHINE is an entirely automatic procedure which enables halving the acquisition time or the injected dose in scintigraphic acquisitions. It can be applied to all scintigraphic images, including PET data, and to all low-count photon images.     

A new method for determining physician decision thresholds using empiric,uncertain recommendations

Background  

The concept of risk thresholds has been studied in medical decision making for over 30 years. During that time, physicians have been shown to be poor at estimating the probabilities required to use this method. To better assess physician risk thresholds and to more closely model medical decision making, we set out to design and test a method that derives thresholds from actual physician treatment recommendations. Such an approach would avoid the need to ask physicians for estimates of patient risk when trying to determine individual thresholds for treatment. Assessments of physician decision making are increasingly relevant as new data are generated from clinical research. For example, recommendations made in the setting of ocular hypertension are of interest as a large clinical trial has identified new risk factors that should be considered by physicians. Precisely how physicians use this new information when making treatment recommendations has not yet been determined.     

A method for staining multiple chemotaxis filters.

A device is described which holds chemotaxis filters on glass slides so that the cells on as many as 128 filters can be stained simultaneously. The procedure for using the batch stainer with Wright's stain is outlined.