Histogram-Based Texture Characterization and Classification of Brain Tissues in Non-Contrast CT Images of Stroke Patients

This chapter describes histogram-based texture characterization and classification of brain tissue in CT images of stroke patients using a case study. It explored texture analysis in medical imaging. In the case study, two radiologists independently inspected non-contrast CT images of 164 stroke to identify and categorize brain tissue into normal, ischaemic and haemorrhagic strokes. Four regions of interest (ROIs) in each CT slice with lesion were selected for analysis; two each represented the lesion and normal tissue. Histogram texture parameters were calculated for them. Raw data analysis identified parameters that discriminated between normal brain tissue, ischaemic and haemorrhagic stroke lesions. The artificial neural network (ANN) and k-nearest neighbour (k-NN) algorithms were used to classify the ROIs into normal tissue, ischaemic and haemorrhagic lesions using the radiologists’ categorization as the gold standard, and further analysed using the ROC curve. Three parameters namely mean, 90 and 99 percentiles discriminated between normal brain tissue, ischaemic and haemorrhagic stroke lesions. With ANN and k-NN, the weighted sensitivity and specificity were above 0.9 while the false positive and false negative rates were negligible. The characterization and classification of brain tissue using histogram parameters were satisfactory and may be suitable for automated diagnosis of stroke

Assessment of Indoor Radon Concentration Levels in Offices of University of Nigeria, Enugu Campus, Nigeria

Background: Indoor radon concentration levels are an essential component for assessing radiation exposure to populations. Indoor Radon levels have not been reported for offices of academic staff of The University of Nigeria, Enugu, which is located on a hilly rocky plain.Purpose: To establish potential for radiation hazards to persons using offices for extended periods of time.Materials and Methods: Four offices were randomly selected from each of the five faculties in the campus, making a total of twenty surveyed offices. Short term Electret Ion Chamber Technology (EIC) with the trade name E-PERMTM was employed for the measurement of radon concentration in the offices.Results: Average indoor radon concentration in the offices range between 2.5 Bq m-3 to 21.3 Bq m-3 with an arithmetic mean of 11.8 Bq m-3.Conclusion: Indoor Radon levels in University of Nigeria, Enugu Campus offices is currently within acceptable safe limits

Characterization and Classification of Brain Tissue and Stroke Lesions in Non-Contrast Computed Tomography Images of Stroke Patients Using Statistical Texture Descriptors and Artificial Neural Network

  Aim: To characterize and classify stroke lesions and normal brain tissue in computed tomography (CT) images using statistical texture descriptors. Patients and methods: Two experienced radiologists blinded to each other inspected CT images of 164 stroke patients to identify and categorize stroke lesions into ischaemic and haemorrhagic subtypes. Four regions of interest (ROIs) in each CT slice that demonstrated the lesion; two each representing the lesion and normal tissue were selected. Statistical texture descriptors namely, co-occurrence matrix, run-length matrix, absolute gradient and histogram were calculated for them.  Raw data analysis was performed to identify the parameters that best discriminate between normal brain tissue and stroke lesions. Artificial neural network (ANN) was used to classify the ROIs into normal tissue, ischaemic and haemorrhagic lesions using the radiologists’ identification and categorization as the gold standard, and further analyzed using the receiver operating characteristic curve. Results: Three parameters in each texture class discriminated between normal tissue, ischaemic and haemorrhagic stroke lesions. The discriminating co-occurrence matrix parameters were sum average parameters namely S1-1 SumAverg, S1-0 SumAverg and S0-1 SumAverg.  For the run-length matrix, short run emphasis in horizontal, 1350 and 450 directions were the discriminating features. The discriminating absolute gradient parameters were gradient non-zeros, gradient variance and gradient mean. For the histogram class, the mean, 90th and 99th percentiles were the discriminating parameters. The ANN achieved a sensitivity of 0.637, specificity 0.753, false positive rate (FPR) 0.247, and false negative rate (FNR) 0.363 with co-occurrence matrix. With run-length matrix the sensitivity was 0.544, specificity 0.607, FPR 0.393, and FNR 0.456 while with absolute gradient the sensitivity was 0.546, specificity 0.586, FPR 0.414, FNR 0.454. With histogram, the sensitivity was 0.947, specificity 0.962, FPR 0.038, and FNR 0.053. Conclusion: The histogram texture features showed the highest sensitivity and specificity in the classification of brain tissue and stroke lesions using the artificial neural network.    &nbsp

Sonographic assessment of petroleum-induced hepatotoxicity in Nigerians: does biochemical assessment underestimate liver damage?

Background: Exposure to petroleum products has been shown to have significant adverse effects on the liver which can manifest either as morphological or physiological changes.Objectives: The aim of the study was to assess the effects of chronic exposure to some petroleum products on the liver of exposed workers using sonography and to determine whether biochemical assessments underestimated hepatotoxicity.Methods: Abdominal ultrasound was performed on 415 exposed workers in order to evaluate liver echogenicity and size. Also, biochemical assessment of the liver was done to evaluate its functionResults: Statistically significant increase in the liver parenchymal echogenicity and the liver size was seen in the exposed workers compared with control (p ≤ 0.05). These increased as the exposure duration increased. It was also noted that out of 16.87% (N=70) exposed workers with abnormal liver echopattern, only 2.65% (N=11) had alanine aminotransferase above the reference range.Conclusion: The study revealed evidence of ultrasound detectable hepatotoxicity among the exposed subjects. Sonography appeared to detect petroleum products-induced hepatic toxicity more than biochemical assays suggesting that biochemical assessment may have underestimated toxicity.Keywords: Petroleum Products, Exposure, Hepatotoxicity, Sonography, Biochemical assessment, Nigeri

Assessment of Background Radioactivity of Surface Soils in Ondo City, Ondo State, Nigeria

The natural radioactivity of surface soils collected from various locations in Ondo City were measured by means of well calibrated High Purity Germanium (HPGe) detector, Canberra model coupled to a versatile Canberra Multichannel Analyzer, at the Centre for Energy Research and Development of Obafemi Awolowo University. Ile Ife. The soil samples were collected from the fourteen zones that constituted the town with four samples taken from each zone. The emission line spectra used in identifying the natural radioisotopes belong to 238U and 232Th decay series and that of naturally occurring 40K. The gamma activity obtained for 40K ranged from 212.1 Bq/kg to 895.7 Bq/kg with a mean value of 470.4 ± 26.8 Bq/kg. For 232Th, the gamma activity ranged from 30.2 Bq/kg to 72.4 Bq/kg with a mean value of 48.8 ± 8.4 Bq/kg, and from 3.6 Bq/kg to 14.2 Bq/kg with a mean value of 6.9 ± 1.2 Bq/kg for 238U. The mean absorbed dose rate in these locations amounts to 45.36 nGy/h which by approximate conversion gives an indoor annual effective dose of 0.223 mSv/year and outdoor annual effective dose of 0.056 mSv/year. These values constitute the baseline dose equivalent, which is below the 1.0 mSv/year recommended by the International Commission for Radiological Protection (ICRP, 1990) as the maximum permissible dose equivalent for members of public. The results obtained showed that the study area is free from radiological contamination. Keywords: Radioactivity, Absorbed dose, Radioisotopes, Environment

SONOGRAPHIC REFERENCE LUMINAL DIAMETER OF THE ABDOMINAL AORTA AMONG SUBJECTS IN NIGERIA

Objective: The objective of the study was to develop a reference luminal diameter (LD) of the abdominal aorta (AA) in Abuja, Nigeria. Methods: The LD of the AA of 422 male and female healthy subjects was measured sonographically using standard protocol. The relationship between age, body mass index (BMI), gender, and the LD of the AA was determined in the subjects. Statistical analysis was performed by the Student’s t-test and Pearson’s correlation coefficient at p < 0.05 level of significance. Results: The values of the LD of the AA in the healthy subjects were 15.16 ± 0.55 mm in males and 15.15 ± 0.55 mm in females. The 5th and 95th percentile normal reference limits of the AA were 14.20–16.10 mm, respectively. There were no significant differences in the LD measurements in male and female subjects. Age correlated strongly positively with LD (ɼ=0.90) of the AA in both genders. BMI showed weak positive correlation with LD (ɼ=0.136) of the AA in female healthy subjects only. Conclusion: The reference LD of the AA in the study population was 15.16 ± 0.55 mm in males and 15.15 ± 0.55 mm in females. The LD of the AA increased proportionately with age

GONGRONEMA LATIFOLIUM DELAYS GASTRIC EMPTYING OF SEMI-SOLID MEALS IN DIABETIC DOGS.

ABSTRACT The aim of the study was to investigate sonographically the effect of Gonogronema latifolium on gastric emptying of semi-solid meals in diabetic dogs. Twenty-five alloxan-induced diabetic dogs were randomly allotted into five groups of five dogs each in a randomized placebo-controlled study. These are placebo, prokinetic dose, low dose, moderate dose and high dose groups. The placebo group served as the control. The low, moderate and high dose groups ingested methanolic leaf extract of G. latifolium at 100 mg/kg, 250 mg/kg, 500 mg/kg respectively while the prokinetic group ingested 0.5 mg/kg of metoclopramide. After a 12- hour fast, each group ingested its treatment capsules 30 minutes before the administration of test meal. Measurements of gastric emptying and blood glucose levels were obtained from each dog 30 minutes before and immediately after the ingestion of a test meal, every 15 minutes for another 4 hours and then every 30 minutes for further 2 hours. Gastric emptying of the moderate and high dose groups were 227.8 ± 9.9 min and 261.3 ± 19.3 min respectively and significantly (p 0.05). A strong inverse relationship between gastric emptying and the incremental blood glucose levels was noted in the diabetic dogs after the ingestion of Gonogronema latifolium (r = - 0.90; p < 0.0001). Gonogronema latifolium delayed gastric emptying in diabetic dogs

Sonographic assessment of petroleum-induced hepatotoxicity in Nigerians: does biochemical assessment underestimate liver damage?

Background: Exposure to petroleum products has been shown to have significant adverse effects on the liver which can manifest either as morphological or physiological changes. Objectives: The aim of the study was to assess the effects of chronic exposure to some petroleum products on the liver of exposed workers using sonography and to determine whether biochemical assessments underestimated hepatotoxicity. Methods: Abdominal ultrasound was performed on 415 exposed workers in order to evaluate liver echogenicity and size. Also, biochemical assessment of the liver was done to evaluate its function Results: Statistically significant increase in the liver parenchymal echogenicity and the liver size was seen in the exposed workers compared with control (p 64 0.05). These increased as the exposure duration increased. It was also noted that out of 16.87% (N=70) exposed workers with abnormal liver echopattern, only 2.65% (N=11) had alanine aminotransferase above the reference range. Conclusion: The study revealed evidence of ultrasound detectable hepatotoxicity among the exposed subjects. Sonography appeared to detect petroleum products-induced hepatic toxicity more than biochemical assays suggesting that biochemical assessment may have underestimated toxicity

Impact of Age on Retention in Care and Viral Suppression

Retention in care is important for all HIV-infected persons and is strongly associated with initiation of antiretroviral therapy and viral suppression. However, it is unclear how retention in care and age interact to effect viral suppression. We evaluated whether the association between retention and viral suppression differed by age at entry into care