Amit Kumar Ray

Segmentation and classification of medical images using texture-primitive features: Application of BAM-type artificial neural network

The objective of developing this software is to achieve auto-segmentation and tissue characterization. Therefore, the present algorithm has been designed and developed for analysis of medical images based on hybridization of syntactic and statistical approaches, using artificial neural network (ANN). This algorithm performs segmentation and classification as is done in human vision system, which recognizes objects; perceives depth; identifies different textures, curved surfaces, or a surface inclination by texture information and brightness. The analysis of medical image is directly based on four steps: 1) image filtering, 2) segmentation, 3) feature extraction, and 4) analysis of extracted features by pattern recognition system or classifier. In this paper, an attempt has been made to present an approach for soft tissue characterization utilizing texture-primitive features with ANN as segmentation and classifier tool. The present approach directly combines second, third, and fourth steps into one algorithm. This is a semisupervised approach in which supervision is involved only at the level of defining texture-primitive cell; afterwards, algorithm itself scans the whole image and performs the segmentation and classification in unsupervised mode. The algorithm was first tested on Markov textures, and the success rate achieved in classification was 100%; further, the algorithm was able to give results on the test images impregnated with distorted Markov texture cell. In addition to this, the output also indicated the level of distortion in distorted Markov texture cell as compared to standard Markov texture cell. Finally, algorithm was applied to selected medical images for segmentation and classification. Results were in agreement with those with manual segmentation and were clinically correlated.

Segmentation of medical images using Simulated Annealing Based Fuzzy C Means algorithm

Accurate segmentation is desirable for analysis and diagnosis of medical images. This study provides methodology for fully automated simulated annealing based fuzzy c-means algorithm, modelled as graph search method. The approach is unsupervised based on pixel clustering using textural features. The virtually training free algorithm needs initial temperature and cooling rate as input parameters. Experimentation on more than 180 MR and CT images for different parameter values, has suggested the best-suited values for accurate segmentation. An overall 97% correct segmentation has been achieved. The results, evaluated by radiologists, are of clinical importance for segmentation and classification of Region of Interest.

Sleep–wake study in an animal model of acute and chronic heat stress

The study of the variations in different parameters of sleep-wake states following exposure to high environmental heat in three different age groups of freely moving rats have been presented in this paper. Each age group of rats was subdivided in three group (i) acute heat stress--subjected to a single exposure for 4 h in the BOD (Biological Oxygen Demand) incubator at 38 degrees C; (ii) chronic heat stress--exposed for 21 days daily for 1 h in the incubator at 38 degrees C, and (iii) handling control groups. The polygraphic, analog as well as digital sleep-wake recordings were performed just after the heat exposure from acute stressed rats and on 22nd day from chronic stressed rats. The results of this study revealed that acute exposure to high environmental heat increases sleep efficiency with significant increase in SWS (slow wave sleep) decrease in AWA (awake) time in all three age groups of rats. The increase in SWS and the sleep efficiency in these groups of rats at the cost of decreased time of AWA, indicates the involvement of the hypothalamus in thermoregulatory mechanism to conserve the energy of the body following sudden exposure to high heat. However, the reverse results were observed in the chronic stressed groups of rats, which have occurred mostly owing to the adaptations of the brain functions due to repetitive exposure to environmental heat. In consequence, the present study exhibits that the sleep is highly susceptible to the environmental heat and it is sensitive to the intensity, duration and the mode of exposure.

Blood-Central Nervous System Barriers in Morphine Dependence and Withdrawal

Abstract The status of blood-central nervous system barriers during morphine dependence or withdrawal is still unknown. Morphine withdrawal is associated with profound stress response, immediate early gene expression in the CNS and alterations in neurochemical metabolism. Thus, a possibility exists that stress caused by morphine withdrawal will impair blood-CNS barriers function. Experiments carried out in our laboratory show that spontaneous morphine withdrawal in rats is associated with a selective and specific breakdown of the blood-brain, blood-CSF and blood-spinal cord barriers to Evans blue albumin, radioactive iodine and lanthanum (La3+) tracers. Several brain regions show pronounced structural alterations during morphine dependence and withdrawal. Pharmacological manipulations of nitric oxide (NO), serotonin (5-hydroxytryptamine) or Ca2+ channel during morphine dependence and withdrawal attenuates the blood-CNS barrier dysfunction and structural changes. These observations suggest that morphine dependence and withdrawal is associated with alterations in CNS microfluid environment and cellular damage. The functional significance of these findings and the probable mechanisms are discussed.

Zinc protoporphyrin IX attenuates closed head injury-induced edema formation, blood-brain barrier disruption, and serotonin levels in the rat

The role of heme oxygenase (HO) in closed head injury (CHI) was examined using a potent HO and guanylyl cyclase inhibitor, zinc protoporphyrin (Zn-PP) in the rat. Blood-brain barrier (BBB) permeability to Evans blue and radioiodine, edema formation, and plasma and brain levels of serotonin were measured in control, CHI, and Zn-PP-treated CHI rats. CHI was produced by an impact of 0.224 N on the right parietal bone by dropping 114.6 g weight from a height of 20 cm in anesthetized rats. This concussive injury resulted in edema formation and brain swelling 5 hours after insult that was most pronounced in the contralateral hemisphere. The whole brain was edematous and remained in a semi-fluid state. Microvascular permeability disturbances to protein tracers were prominent in both cerebral hemispheres and the underlying cerebral structures. Plasma and brain serotonin showed pronounced increases and correlated with edema formation. Pretreatment with Zn-PP (10 mg/ kg, i.p) 30 minutes before or after CHI attenuated edema formation, brain swelling, plasma and brain serotonin levels, and microvascular permeability at 5 hours. Brain edema, BBB permeability, and serotonin levels were not attenuated when the compound was administered 60 minutes post-CHI suggesting that HO is involved in cellular and molecular mechanisms of edema formation and BBB breakdown early after CHI.

Thromboresistance of functionalized poly(methylmethacrylate): the effect of surface polarity

An implant material when comes in contact with blood fluids (e.g., blood and lymph), adsorb proteins spontaneously on its surface. Notably, blood coagulation is influenced by many factors, including mainly chemical structure and polarity (charge) of the material. The present study describes the methodology to improve the blood compatibility of poly(methylmethacrylate) (PMMA) by incorporating ionic groups with varying polarities. PMMA has been functionalized with different groups containing positive, negative and neutral polarity by the free radical polymerization technique and such modification were further confirmed through Fourier transform infrared (FTIR) spectroscopy. The level of thrombogenicity was found three times lower with negatively charged PMMA in comparison to those of positively charged and neutral PMMA. Platelet adhesion was noted almost negligible in all samples after 10 s of blood exposure. High adsorption of fibrinogen from the blood was noticed in the test sample containing a group with positive polarity (thiouronium chloride) while there was no platelet adhesion observed even after 120 s of blood exposure in the test samples containing negatively charged (sulphate) and neutral (hydroxyl group) functional groups.