Biomedical subjects

Normand Robert

Publications and source records attributed to Normand Robert.

7 recordsLinked to original sources

PubMed2005

Polyphasic characterization of the lactic acid bacteria in kefir.

The lactic acid bacteria of kefir were isolated and characterized using phenotypical, biochemical, and genotypical methods. Polyphasic analyses of results permitted the identification of the microflora to the strain level. The genus Lactobacillus was represented by the species Lb. kefir and Lb. kefiranofaciens. Both subspecies of Lactococcus lactis (lactis and cremoris) were isolated. Leuconostoc mesenteroides subsp. cremoris was also found. The kefir studied contained few species of lactic acid bacteria but showed a high number of different strains. We found that the polyphasic analysis approach increases the confidence in strain determination. It helped confirm strain groupings and it showed that it could have an impact on the phylogeny of the strains.

Cultured Milk Products↗

PubMed2005

A lesion stabilization method for coronary angiography.

A method to make a coronary artery segment of interest appear stationary when viewing a sequence of angiographic images is proposed. The purpose of this method is to facilitate the assessment of lesions caused by coronary artery disease by improving detectability. A description of the stabilization algorithm based on template matching is given. Stabilization was performed on 41 clinical coronary angiograms exhibiting various stenoses and was successful in 39/41 cases. A quantitative analysis of stabilization errors was performed by introducing simulated moving vessels of decreasing contrast into sequences of clinical images.

Algorithms↗

PubMed2005

Real-time image equalization for coronary X-ray angiography.

Coronary angiograms, which provide detailed images of contrast-filled coronary arteries, also show other large structures such as the diaphragm, spine and adjacent lung field. A real-time image processing method to attenuate these unwanted features is presented. Side-by-side comparisons of images selected from cine runs before and after processing show that the arteries in the processed images can be visualized more easily due to their higher contrast as other structures are made less prominent. It is also shown experimentally that this method allows more quantitative comparisons of the contrast of vessels in different parts of an image.

Angiography, Digital Subtraction↗

PubMed2004

Adaptive averaging for improved SNR in real-time coronary artery MRI.

A technique has been developed for combining a series of low signal-to-noise ratio (SNR) real-time magnetic resonance (MR) images to produce composite images with high SNR and minimal artifact in the presence of motion. The main challenge is identifying a set of real-time images with sufficiently small systematic differences to avoid introducing significant artifact into the composite image. To accomplish this task, one must: 1) identify images identical within the limits of noise; 2) detect systematic errors within such images with sufficient sensitivity. These steps are achieved by evaluating the correlation coefficient (CC) between regions in prospective images and a template containing the anatomy of interest. Images identical within noise are selected by comparing the measured CC values to the theoretical distribution expected due to noise. Sensitivity for systematic error depends on the SNR of the CC (=SNR(CCmax)), which in turn depends on the noise, and the template size and structure. By varying the template size, SNR(CCmax) may be altered. Experiments on phantoms and coronary artery images demonstrate that the SNR(CCmax) necessary to avoid introducing significant artifact varies with the target composite SNR. The future potential of this technique is demonstrated on high-resolution (approximately 0.9 mm), reduced field-of-view real-time coronary images.

Algorithms↗

PubMed2002

Variable-density adaptive imaging for high-resolution coronary artery MRI.

Variable-density (VD) spiral k-space acquisitions are used to acquire high-resolution (0.78 mm), motion-compensated images of the coronary arteries. Unlike conventional methods, information for motion compensation is obtained directly from the coronary anatomy itself. Specifically, periods of minimal coronary distortion are identified by applying the correlation coefficient template matching algorithm to real-time images generated from the inner, high-density portions of the VD spirals. Combining the data associated with these images together, high-resolution, motion-compensated coronary images are generated. Because coronary motion is visualized directly, the need for cardiac-triggering, breath-holding, and navigator echoes is eliminated. The motion compensation capability of the technique is determined by the inner-spiral spatial and temporal resolution. Results indicate that the best performance is achieved using inner-spiral images with high spatial resolution (1.6-2.9 mm), even though temporal resolution (four to six independent frames per second) suffers as a result. Image quality within the template region in healthy volunteers was found to be comparable to that achieved with cardiac-triggered breath-hold scans, although extended acquisition times of around 5 min were needed to overcome reduced SNR efficiency.

Algorithms↗

PubMed2002

A filtering method for signal equalization in region-of-interest fluoroscopy.

A method to significantly reduce the exposure area product in fluoroscopy using a pre-patient region-of-interest (ROI) attenuator is presented. The attenuator has a thin central region and a gradually increasing thickness away from the center. It is shown that the unwanted brightening artifact caused by the attenuator can be eliminated by attenuating the low spatial frequencies in the detected image using digital image processing techniques. An investigation of the best image processing method to correct for the presence of the attenuator is undertaken. The correction procedure selected is suitable for use with real-time image processors and the ROI attenuator can be permitted to move during image acquisition. Images of an anthropomorphic chest phantom acquired in the presence of the ROI attenuator using an x-ray image intensifier/video chain are corrected to illustrate the clinical feasibility of our approach.

Biophysical Phenomena↗

PubMedDate not supplied

Biotechnological methods to accelerate cheddar cheese ripening.

Cheese is one of the dairy products that can result from the enzymatic coagulation of milk. The basic steps of the transformation of milk into cheese are coagulation, draining, and ripening. Ripening is the complex process required for the development of a cheese's flavor, texture and aroma. Proteolysis, lipolysis and glycolysis are the three main biochemical reactions that are responsible for the basic changes during the maturation period. As ripening is a relatively expensive process for the cheese industry, reducing maturation time without destroying the quality of the ripened cheese has economic and technological benefits. Elevated ripening temperatures, addition of enzymes, addition of cheese slurry, attenuated starters, adjunct cultures, genetically engineered starters and recombinant enzymes and microencapsulation of ripening enzymes are traditional and modern methods used to accelerate cheese ripening. In this context, an up to date review of Cheddar cheese ripening is presented.

Biotechnology↗