Automatic tractography and segmentation using finsler geometry based on higher-order tensor fields.

BACKGROUND AND OBJECTIVE: We focus on three-dimensional higher-order tensorial (HOT) images using Finsler geometry. In biomedical image analysis, these images are widely used, and they are based on the diffusion profiles inside the voxels. The diffusion information is stored in the so-called diffusion tensor D. Our objective is to present new methods revealing the architecture of neural fibers in presence of crossings and high curvatures. After tracking the fibers, we achieve direct 3D image segmentation to analyse the brain's white matter structures. METHODS: To deal with the construction of the underlying fibers, the inverse of the second-order diffusion tensor D, understood as the metric tensor D-1, is commonly used in DTI modality. For crossing and highly curved fibers, higher order tensors are more relevant, but it is challenging to find an analogue of such an inverse in the HOT case. We employ an innovative approach to metrics based on higher order tensors to track the fibers properly. We propose to feed the tracked fibers as the internal initial contours in an efficient version of 3D segmentation. RESULTS: We propose a brand-new approach to the inversion of a diffusion HOT, and an effective way of fiber tracking in the Finsler setting, based on innovative classification of the individual voxels. Thus, we can handle complex structures with high curvatures and crossings, even in the presence of noise. Based on our novel tractography approach, we also introduce a new segmentation method. We feed the detected fibers as the initial position of the contour surfaces to segment the image using a relevant active contour method (i.e., initiating the segmentation from inside the structures). CONCLUSIONS: This is a pilot work, enhancing methods for fiber tracking and segmentation. The implemented algorithms were successfully tested on both synthetic and real data. The new features make our algorithms robust and fast, and they allow distinguishing individual objects in complex structures, even under noise.

Geodesic fiber tracking in white matter using activation function.

BACKGROUND AND OBJECTIVE: The geodesic ray-tracing method has shown its effectiveness for the reconstruction of fibers in white matter structure. Based on reasonable metrics on the spaces of the diffusion tensors, it can provide multiple solutions and get robust to noise and curvatures of fibers. The choice of the metric on the spaces of diffusion tensors has a significant impact on the outcome of this method. Our objective is to suggest metrics and modifications of the algorithms leading to more satisfactory results in the construction of white matter tracts as geodesics. METHODS: Starting with the DTI modality, we propose to rescale the initially chosen metric on the space of diffusion tensors to increase the geodetic cost in the isotropic regions. This change should be conformal in order to preserve the angles between crossing fibers. We also suggest to enhance the methods to be more robust to noise and to employ the fourth order tensor data in order to handle the fiber crossings properly. RESULTS: We propose a way to choose the appropriate conformal class of metrics where the metric gets scaled according to tensor anisotropy. We use the logistic functions, which are commonly used in statistics as cumulative distribution functions. To prevent deviation of geodesics from the actual paths, we propose a hybrid ray-tracing approach. Furthermore, we suggest how to employ diagonal projections of 4th order tensors to perform fiber tracking in crossing regions. CONCLUSIONS: The algorithms based on the newly suggested methods were succesfuly implemented, their performance was tested on both synthetic and real data, and compared to some of the previously known approaches.

Antimalarial activity of hydromethanolic extract and its solvent fractions of Vernonia amygdalina leaves in mice infected with Plasmodium berghei.

BACKGROUND: Vernonia amygdalina Del. (Asteraceae) is reported to be traditionally used for the treatment of malaria. Based on folkloric repute of this plant in Ethiopian traditional medicine and crude extract-based ethnopharmacological studies conducted in few countries, this study was undertaken to evaluate the in vivo antimalarial activity of 80% methanol extract and its solvent fractions of the leaves of V. amygdalina in mice infected with Plasmodium berghei. METHODS: A 4-day suppressive test was conducted on mice infected with P. berghei to find out antimalarial effect of chloroform, butanol and aqueous fractions obtained from the 80% methanol crude extract. In all the activity tests, mice were randomly assigned in five groups (three tests and two controls) of six animals in each and received respective treatments. Data were analyzed using one way analysis of variance followed by Tukey's post hoc test for multiple comparisons. RESULTS: Acute oral toxicity test showed that all solvent fractions of the leaves of V. amygdalina revealed neither mortality nor overt signs of toxicity up to 2000 mg/kg. This study indicated that the percentage parasitemia suppression of 80% methanol extract was 32.47% (±2.65), 35.40% (±3.14) and 37.67% (±2.50) at 200, 400 and 600 mg/kg, respectively. All doses of the 80% methanol extract of V. amygdalina prolonged survival time and prevented weight loss and packed cell volume reduction in infected mice. All doses of chloroform and butanol fractions significantly suppressed parasitemia (p < 0.05), increased survival time (p < 0.05) compared to negative control and exhibited a significant reduction in rectal temperature (p < 0.05). All solvent fractions significantly prevented weight loss (p < 0.05) at all tested doses. The 80% methanol extract and chloroform and butanol fractions significantly (p < 0.05) prevented further reduction in rectal temperature of P. berghei-infected mice at all doses. CONCLUSION: The results of this study indicated that 80% methanol extract and solvent fractions of the leaves of V. amygdalina demonstrated promising antimalarial activity. The study corroborated the folklore use of this plant for the treatment of malaria in ethnomedicine in Ethiopia.

Appropriateness of Cotrimoxazole Prophylactic Therapy Among HIV/AIDS Patients in Public Hospitals in Eastern Ethiopia: A Retrospective Evaluation of Clinical Practice.

Background: Cotrimoxazole prophylactic therapy (CPT) is a feasible, cost-effective, and safe way of using cotrimoxazole intervention to reduce HIV/AIDS related morbidities and mortalities associated with opportunistic infections. Despite its effectiveness in reducing the incidence of opportunistic infections, the actual drug utilization process has been shown to deviate from World Health Organization (WHO) guideline in Ethiopia. This study, therefore, aims to evaluate CPT among HIV/AIDS patients in Jugel Hospital (JH), Harar and Dilchora Referral Hospital (DRH), Dire Dawa, Eastern Ethiopia. Methods: A cross sectional study was conducted to evaluate the use of cotrimoxazole as prophylactic therapy. In this study, 556 medical records (305 in JH and 251 in DRH) of HIV/AIDS patients who had been taking CPT within September 2015-August 2016 were reviewed. Systematic random sampling was employed to obtain medical records from the sampling frame. Data were abstracted from the patient medical records using structured checklist customized from the WHO guideline. The data were entered into Epi-data 3.1 and exported to and analyzed with statistical Package for Social Sciences (SPSS) version 20. The finding was evaluated against the WHO guideline on the use of cotrimoxazole prophylaxis in HIV/AIDS patients. Descriptive statistics was used to present the data in tables, figures and pie chart. Results: Majority of the HIV/AIDS patients who had been taking CPT were adults (95.9%), female (61.2%), married (43.7%), Orthodox Christian (54.3%), and attended primary school (40.1%). At the initiation of CPT, most of the patients were at WHO clinical stage III (40.8%). The major comorbid illnesses identified were tuberculosis and pneumocystis-jiroveci pneumonia. Initially, majority of the patients were at CD4 count of less than 350 cells/mm3 (n = 504, 90.6%). Greater proportion of patients started CPT prior to initiating antiretroviral therapy (ART). Most of the patients took CPT for greater than 6 months. The primary reasons for premature discontinuation of CPT were CD4 greater than 350 cells/mm3, severe sulfa allergy and first trimester of pregnancy. Generally, the use of cotrimoxazole prophylaxis was consistent with the WHO guideline for indication to start (n = 519, 93.3%) and dose (n = 552, 99.28%), despite the presence of contraindication in 6.65% patients. Conclusion: In reference to the WHO guideline, the use of CPT was found to be fully appropriate in nearly two-thirds of HIV/AIDS patients. For the rest patients, inappropriate use of cotrimoxazole was observed based on the WHO criteria for initiation, discontinuation, continuation and dose with rate of discontinuation being the dominant one. Such practice may lead to adverse health outcomes including adverse drug reactions and negative treatment outcome.