30 research outputs found

    Hadamard Slice Encoding for Reduced-FOV Diffusion-Weighted Imaging

    Get PDF
    Cataloged from PDF version of article.Methods: A 2D echo-planar RF pulse and matching multiband refocusing RF pulses were designed using the Shinnar-Le Roux algorithm to reduce band interference, and variable-rate selective excitation to shorten the pulse durations. Hadamardencoded images were resolved through a phase-preserving image reconstruction. The performance of the method was evaluated via simulations, phantom experiments, and in vivo high-resolution axial DWI of spinal cord. Purpose: To improve the clinical utility of diffusion-weighted imaging (DWI) by extending the slice coverage of a highresolution reduced field-of-view technique. Theory: Challenges in achieving high spatial resolution restrict the use of DWI in assessment of small structures such as the spinal cord. A reduced field-of-view method with 2D echo-planar radiofrequency (RF) excitation was recently proposed for high-resolution DWI. Here, a Hadamard sliceencoding scheme is proposed to double the slice coverage by exploiting the periodicity of the 2D echo-planar RF excitation profile. Results: The proposed scheme successfully extends the slice coverage, while preserving the sharp excitation profile and the reliable fat suppression of the original method. For in vivo axial DWI of the spinal cord, an in-plane resolution of 0.7 × 0.7 mm2 was achieved with 16 slices. Conclusion: The proposed Hadamard slice-encoding scheme doubles the slice coverage of the 2D echo-planar RF reduced field-of-view method without any scan-time penalty. © 2013 Wiley Periodicals, Inc

    Mutations in APC, CTNNB1 and K-ras genes and expression of hMLH1 in sporadic colorectal carcinomas from the Netherlands Cohort Study

    Get PDF
    BACKGROUND: The early to intermediate stages of the majority of colorectal tumours are thought to be driven by aberrations in the Wnt (APC, CTNNB1) and Ras (K-ras) pathways. A smaller proportion of cancers shows mismatch repair deficiency. The aim of this study was to analyse the co-occurrence of these genetic alterations in relation to tumour and patient characteristics. METHODS: In a group of 656 unselected sporadic colorectal cancer patients, aberrations in the APC, K-ras, CTNNB1 genes, and expression of hMLH1 were investigated. Additionally, tumours were divided in groups based on molecular features and compared with respect to patient's age at diagnosis, sex, family history of colorectal cancer, tumour sub-localisation, Dukes' stage and differentiation. RESULTS: Mutations at the phosphorylation sites (codons 31, 33, 37, and 45) in the CTNNB1 gene were observed in tumours from only 5/464 patients. Tumours with truncating APC mutations and activating K-ras mutations in codons 12 and 13 occurred at similar frequencies (37% (245/656) and 36% (235/656), respectively). Seventeen percent of tumours harboured both an APC and a K-ras mutation (109/656). Nine percent of all tumours (58/656) lacked hMLH1 expression. Patients harbouring a tumour with absent hMLH1 expression were older, more often women, more often had proximal colon tumours that showed poorer differentiation when compared to patients harbouring tumours with an APC and/or K-ras mutation. CONCLUSION: CTNNB1 mutations seem to be of minor importance in sporadic colorectal cancer. The main differences in tumour and patient characteristics are found between groups of patients based on mismatch repair deficiency

    Age- and region-specific hepatitis B prevalence in Turkey estimated using generalized linear mixed models: a systematic review

    Get PDF
    Toy M, Önder FO, Wörmann T, et al. Age- and region-specific hepatitis B prevalence in Turkey estimated using generalized linear mixed models: a systematic review. BMC infectious diseases. 2011;11(1): 337.BACKGROUND: To provide a clear picture of the current hepatitis B situation, the authors performed a systematic review to estimate the age- and region-specific prevalence of chronic hepatitis B (CHB) in Turkey. METHODS: A total of 339 studies with original data on the prevalence of hepatitis B surface antigen (HBsAg) in Turkey and published between 1999 and 2009 were identified through a search of electronic databases, by reviewing citations, and by writing to authors. After a critical assessment, the authors included 129 studies, divided into categories: 'age-specific'; 'region-specific'; and 'specific population group'. To account for the differences among the studies, a generalized linear mixed model was used to estimate the overall prevalence across all age groups and regions. For specific population groups, the authors calculated the weighted mean prevalence. RESULTS: The estimated overall population prevalence was 4.57, 95% confidence interval (CI): 3.58, 5.76, and the estimated total number of CHB cases was about 3.3 million. The outcomes of the age-specific groups varied from 2.84, (95% CI: 2.60, 3.10) for the 0-14-year olds to 6.36 (95% CI: 5.83, 6.90) in the 25-34-year-old group. CONCLUSION: There are large age-group and regional differences in CHB prevalence in Turkey, where CHB remains a serious health problem

    Organigrama de la Escuela Superior de Enfermería y Obstetricia

    No full text
    Representación gráfica de la estructura orgánica que debe reflejar en forma esquemática, la posición de las unidades administrativas que la componen, los tramos de control, el nivel jerárquico, canales formales de comunicación y coordinación, así como las líneas de mando

    Science and Art Centers (SAC) According to the Parents

    No full text
    The aim of this study is to investigate the views of parents on SAC, whose children enroll Science and Art Centers (SAC) at the primary school level. Designed as a phenomenological study. Interviews were conducted with 10 volunteers. The participants are of different age and occupation groups and have children in SAC in different levels. Data was gathered through interviews with the parents, and analyzed by descriptive analysis. According to the analysis, four themes were constructed under the main theme of Parents' SAC, which was "Being with SAC", "The contributions of SAC", "Problems about SAC", and "Suggestions for SAC. Parents indicated that they are proud of their children for being enrolled in SAC, and moreover their children are happy to be there. Parents also stated that SAC curriculum should include different activities to develop the children's' creativity, there should be more communication with the parents, there should be different criteria for the teacher selection in SAC, and SAC buildings are physically insufficient.C1 [Saritas, Emel; Sahin, Umran; Catalbas, Gulsum] Pamukkale Univ, Egitim Fak, Temel Egitim Bolumu, Denizli, Turkey

    Fully automated gridding reconstruction for non-Cartesian x-space magnetic particle imaging

    No full text
    Magnetic particle imaging (MPI) is a fast emerging biomedical imaging modality that exploits the nonlinear response of superparamagnetic iron oxide (SPIO) nanoparticles to image their spatial distribution. Previously, various scanning trajectories were analyzed for the system function reconstruction (SFR) approach, providing important insight regarding their image quality performances. While Cartesian trajectories remain the most popular choice for x-space-based reconstruction, recent work suggests that non-Cartesian trajectories such as the Lissajous trajectory may prove beneficial for improving image quality. In this work, we propose a generalized reconstruction scheme for x-space MPI that can be used in conjunction with any scanning trajectory. The proposed technique automatically tunes the reconstruction parameters from the scanning trajectory, and does not induce any additional blurring. To demonstrate the proposed technique, we utilize five different trajectories with varying density levels. Comparison to alternative reconstruction methods show significant improvement in image quality achieved by the proposed technique. Among the tested trajectories, the Lissajous and bidirectional Cartesian trajectories prove more favorable for x-space MPI, and the resolution of the images from these two trajectories can further be improved via deblurring. The proposed fully automated gridding reconstruction can be utilized with these trajectories to improve the image quality in x-space MPI

    Identifying individuals at risk of needing CKD associated medications in a European kidney disease cohort

    No full text
    Background The consequences of chronic kidney disease (CKD) can be addressed with a range of pharmacotherapies primarily prescribed by nephrologists. More accurate information regarding future CKD-related pharmacotherapy requirements could guide clinical decisions including follow-up frequency. Methods Following assignment to derivation and validation groups (2,1), variables predicting individually future use of vitamin D receptor agonists (VDRA), phosphate binders, erythropoiesis stimulating agents (ESAs) and iron were identified using logistic regression in a prospective cohort study containing demography, comorbidity, hospitalization, laboratory, and mortality data in patients with CKD stage G4/G5 across six European countries. Discriminative ability was measured using C-statistics, and predicted probability of medication use used to inform follow-up frequency. Results A total of 2196 patients were included in the analysis. During a median follow-up of 735 days 648 initiated hemodialysis and 1548 did not. Combinations of age, diabetes status and iPTH, calcium, hemoglobin and serum albumin levels predicted the use of ESA, iron, phosphate binder or VDRA, with C-statistics of 0.70, 0.64, 0.73 and 0.63 in derivation cohorts respectively. Model performance in validation cohorts were similar. Sixteen percent of patients were predicted to have a likelihood of receiving any of these medications of less than 20%. Conclusions In a multi-country CKD cohort, prediction of ESA and phosphate binder use over a two-year period can be made based on patient characteristics with the potential to reduce frequency of follow-up in individuals with low risk for requiring these medications

    Effect of Mg2SO4 usage on spinal cord ischemia-reperfusion injury: Electron microscopic and functional evaluation

    No full text
    Objectives: To evaluate the effects of intravenous magnesium sulfate (Mg2SO4) administration on ischemia-reperfusion injury of the spinal cord. Material and Methods: Sixteen rabbits were randomly assigned to the control ( group I, 8 rabbits) and the study group ( group II, 8 rabbits). The abdominal aorta was clamped for a period of 30 min followed by a reperfusion period of 60 min. The animals in group II received 0.25 ml/kg/h Mg2SO4 intravenous infusion (15% Mg2SO4) throughout this procedure. The animals were then observed for 24 h after which their neurological states were evaluated and tissue samples obtained from the spinal cord were examined with electron microscopy. Results: Aortic pressure distal to the cross-clamp during the occlusion period was 9 +/- 3 mm Hg in group I and 19 +/- 6 mm Hg in group II. All animals in group I were paraplegic at the end of the study. In group II the neurological outcome of 1 animal was poor while the other 7 animals were neurologically in a good condition. Electron microscopic examinations of the spinal cord tissues of group I revealed severe injury but the ultrastructure was well preserved in group II. Conclusions: Intravenous Mg2SO4 administration may have protective effects on the ischemia-reperfusion injury of the spinal cord. We propose that Mg2SO4 may be an additional protective pharmacological agent in thoracal and thoracoabdominal aortic surgery. Copyright (C) 2004 S. Karger AG, Basel
    corecore