22 results on '"Doring T"'
Search Results
2. Comparing the Response of a SiC and a sCVD Diamond Detectors to 14-MeV Neutron Radiation
- Author
-
Obraztsova, O., primary, Ottaviani, L., additional, Klix, A., additional, Doring, T., additional, Palais, O., additional, and Lyoussi, A., additional
- Published
- 2018
- Full Text
- View/download PDF
3. Development of an integrated pest management strategy for control of pollen beetles in winter oilseed rape (HGCA Project Report No 504)
- Author
-
Cook, S. M., Doring, T. F., Ferguson, A. W., Martin, J. L., Skellern, M. P., Smart, L. E., Watts, N. P., Welham, S. J., Woodcock, C. M., Pickett, J. A., Bardsley, E., Bowman, J., Burns, S., Clarke, M., Davies, J., Gibbard, C., Johnen, A., Jennaway, R., Meredith, R., Murray, D., Nightingale, M., Padbury, N., Patrick, C., Von Richthofen, J-S., Taylor, P., Tait, M., and Werner, P.
- Abstract
We have developed an integrated pest management strategy (IPM) for pollen beetles in winter oilseed rape (OSR) based on risk assessment, monitoring and alternative crop management that can be used as a framework by growers and crop consultants to manage pollen beetles with reduced insecticide inputs - and the confidence to do so. This will prolong insecticide life by reducing selection for resistance, reduce environmental impacts and contribute towards the sustainability and profitability of OSR in the UK. One of the major limitations to the use of action thresholds is that proper monitoring of the populations is time consuming and has to be conducted over a prolonged period. To encourage and facilitate their use, we tested and developed tools to improve risk assessment and monitoring. We conducted a pollen beetle monitoring study over 4 years in 178 OSR crops across the UK. Pollen beetles were sampled using sticky traps and plant sampling along transects in the crop. The data were used to help test a decision support system (DSS) for pollen beetles and to develop a monitoring trap. proPlant Expert is a DSS available in mainland Europe that uses a model of pollen beetle immigration and local meteorological data to forecast the start and end of pollen beetle immigration into the crop and main risk periods and advises when to monitor. We tested the model under UK conditions using data from our study and compared monitoring advice with the current advice system on the CropMonitor website (advises monitoring when the crop is at green-yellow bud stage and temperature >15°C). Both performed reassuringly well in prompting monitoring that would detect breaches of spray thresholds. However there were considerable reductions provided by proPlant in the need for consultation of the system (30%) and advised monitoring days (34-53%) in comparison with current advice. Use of the proPlant DSS could therefore focus monitoring effort to when it is most needed. It could also help to reduce unnecessary sprays in cases where beetle numbers are approaching threshold but consultation of the system returns a poor immigration risk forecast or an immigration complete result. The proPlant tool is now freely available to growers and crop consultants in the UK via the Bayer CropScience website. A monitoring trap for pollen beetles would help to more easily and accurately identify when spray thresholds have been breached than monitoring plants in the crop. We developed a baited monitoring trap for pollen beetles which will be commercially available from Oecos. The trap comprises a yellow sticky card mounted at 45°, baited with phenylacetaldehyde, a floral volatile produced naturally by several plant species. Unfortunately using data from our study we were unable to calibrate the trap catch to a given action threshold expressed as the number of beetles per plant using a simple linear relationship. However, the monitoring trap still has value for risk assessment, especially if used together with DSS. We tested the potential of turnip rape (TR) trap crops, planted as borders to the main OSR crop to reduce pollen beetle numbers in a field scale experiment conducted over three years on two sites. We found evidence that the strategy worked well in some years, but not others. This tactic is probably practically and economically worthwhile only for organic growers.
- Published
- 2013
4. Post 17th century changes of European lead emissions recorded in high-altitude Alpine snow and ice
- Author
-
Schwikowski M., Barbante C., Doring T., Gaggeler H.W., and Boutron C.
- Published
- 2003
5. 40Ar proposed as probe of neutron-induced reactions in a high-density stellar-like plasma at the National Ignition Facility
- Author
-
Paul M., Sahoo R. N., Tessler M., Jeet J., Velsko C., Zylstra A., Avila M., Dickerson C., Fougères C., Jayatissa H., Pardo R. C., Rehm K. E., Scott R., Tolstukhin I., Vondrasek R., Bailey T., Callahan L., Clark A. M., Collon P., Kashiv Y., Nelson A., Köster U., Hoffmann H. F. R., Pichotta M., Zuber K., Döring T., and Schwengner R.
- Subjects
Physics ,QC1-999 - Abstract
The thermodynamical conditions and the neutron density produced in a laser-induced implosion of a deuterium-tritium (DT) filled capsule at the National Ignition Facility (NIF) are the closest laboratory analog of stellar conditions. We plan to investigate neutron-induced reactions on 40Ar, namely the 40Ar(n, 2n)39Ar(t1/2 =268 y), the 40Ar(n, γ)41Ar(110 min) and the potential rapid two-neutron capture reaction 40Ar(2n, γ)42Ar(33 y) in an Ar-loaded DT capsule. The chemical inertness of noble gas Ar enables reliable collection of the reaction products.
- Published
- 2023
- Full Text
- View/download PDF
6. Changing How We Make and Deliver Smart Devices: When Can I Print Out My New Phone?
- Author
-
Schmidt, A., primary, Doring, T., additional, and Sylvester, A., additional
- Published
- 2011
- Full Text
- View/download PDF
7. Potato virus Y reduction by straw mulch in organic potatoes
- Author
-
SAUCKE, H, primary and DORING, T F, additional
- Published
- 2004
- Full Text
- View/download PDF
8. Comparison between Silicon-Carbide and diamond for fast neutron detection at room temperature
- Author
-
Obraztsova O., Ottaviani L., Klix A., Döring T., Palais O., and Lyoussi A.
- Subjects
4H-SiC ,neutron detector ,SiC neutron detector ,Diamond neutron detector ,fast neutron detection ,Physics ,QC1-999 - Abstract
Neutron radiation detector for nuclear reactor applications plays an important role in getting information about the actual neutron yield and reactor environment. Such detector must be able to operate at high temperature (up to 600° C) and high neutron flux levels. It is worth nothing that a detector for industrial environment applications must have fast and stable response over considerable long period of use as well as high energy resolution. Silicon Carbide is one of the most attractive materials for neutron detection. Thanks to its outstanding properties, such as high displacement threshold energy (20-35 eV), wide band gap energy (3.27 eV) and high thermal conductivity (4.9 W/cm·K), SiC can operate in harsh environment (high temperature, high pressure and high radiation level) without additional cooling system. Our previous analyses reveal that SiC detectors, under irradiation and at elevated temperature, respond to neutrons showing consistent counting rates as function of external reverse bias voltages and radiation intensity. The counting-rate of the thermal neutron-induced peak increases with the area of the detector, and appears to be linear with respect to the reactor power. Diamond is another semi-conductor considered as one of most promising materials for radiation detection. Diamond possesses several advantages in comparison to other semiconductors such as a wider band gap (5.5 eV), higher threshold displacement energy (40-50 eV) and thermal conductivity (22 W/cm·K), which leads to low leakage current values and make it more radiation resistant that its competitors. A comparison is proposed between these two semiconductors for the ability and efficiency to detect fast neutrons. For this purpose the deuterium-tritium neutron generator of Technical University of Dresden with 14 MeV neutron output of 1010 n·s-1 is used. In the present work, we interpret the first measurements and results with both 4H-SiC and chemical vapor deposition (CVD) diamond detectors irradiated with 14 MeV neutrons at room temperature.
- Published
- 2018
- Full Text
- View/download PDF
9. The intensive DT neutron generator of TU Dresden
- Author
-
Klix Axel, DÖring Toralf, Domula Alexander, and Zuber Kai
- Subjects
DT neutron generator ,fusion neutronics ,neutron flux detector ,Physics ,QC1-999 - Abstract
TU Dresden operates an accelerator-based intensive DT neutron generator. Experimental activities comprise investigation into material activation and decay, neutron and photon transport in matter and R&D work on radiation detectors for harsh environments. The intense DT neutron generator is capable to produce a maximum of 1012 n/s. The neutron source is a solid-type water-cooled tritium target based on a titanium matrix on a copper carrier. The neutron yield at a typical deuteron beam current of 1 mA is of the order of 1011 n/s in 4Π. A pneumatic sample transport system is available for short-time irradiations and connected to wo high-purity germanium detector spectrometers for the measurement of induced activities. The overall design of the experimental hall with the neutron generator allows a flexible setup of experiments including the possibility of investigating larger structures and cooled samples or samples at high temperatures.
- Published
- 2018
- Full Text
- View/download PDF
10. Studies on Flat Sandwich-type Self-Powered Detectors for Flux Measurements in ITER Test Blanket Modules
- Author
-
Raj Prasoon, Angelone Maurizio, Döring Toralf, Eberhardt Klaus, Fischer Ulrich, Klix Axel, and Schwengner Ronald
- Subjects
Physics ,QC1-999 - Abstract
Neutron and gamma flux measurements in designated positions in the test blanket modules (TBM) of ITER will be important tasks during ITER’s campaigns. As part of the ongoing task on development of nuclear instrumentation for application in European ITER TBMs, experimental investigations on self-powered detectors (SPD) are undertaken. This paper reports the findings of neutron and photon irradiation tests performed with a test SPD in flat sandwich-like geometry. Whereas both neutrons and gammas can be detected with appropriate optimization of geometries, materials and sizes of the components, the present sandwich-like design is more sensitive to gammas than 14 MeV neutrons. Range of SPD current signals achievable under TBM conditions are predicted based on the SPD sensitivities measured in this work.
- Published
- 2018
- Full Text
- View/download PDF
11. Assessing the bearing capacity of pillars in the room method.
- Author
-
Doring T. and Doring T.
12. Interrelations between rock kinematics and rock mechanics.
- Author
-
Doring T. and Doring T.
13. Proposal on shaft plugging by reinforced concrete plates in a district of old mining.
- Author
-
Reuter F., Doring T., Meier G., Reuter F., Doring T., and Meier G.
14. Synthesis of 7-Acyl-2,4-disubstituted Pteridines by Radical Nucleophilic Substitution and Displacement Reactions
- Author
-
Döring Thomas, Boruah Romesh C., and Pfleiderer Wolfgang
- Subjects
pteridines ,synthesis ,displacement reaction ,nucleophilic substitution ,radical ,Crystallography ,QD901-999 - Abstract
2,4-Disubstituted pteridine derivatives (1-3) react with acyl radicals very selectively in position 7 by a nucleophilic Substitution mechanism (4-10). Oxidation of the 2-methylthio group proceeds with m-chloroperbenzoic acid in good yields to the corresponding 7-acyl-2-methylsulfonyl-4-aminopteridines (11-16). The methylsulfonyl group can easily been displaced by nucleophiles such as aliphatic amines (27, 29, 32-42, 45), cyclic amines (56-61), aromatic amines (30, 31) and amino acids (43-54). Oxygen nucleophiles lead to 7-acyl-isopterin derivatives (62-66). The acyl side-chain is also prone to structural modifications leading to the corresponding secondary alcohols on NaBH4 reduction (74-77) or to imino derivatives on reactions with amines (67-73) which can analogously been reduced to 2,4-disubstituted 7-( l-aminoalkyl)pteridines (80-85). An interesting H-shift was observed during heating of 32, 78 and 79 with benzylamine leading not to the benzylimines but the isomeric benzylideneamino derivatives 86-88. Various acetylations by acetic anhydride (AC2O) gave 89-93 and reduction of the pyrazine moiety to the 5,6,7,8-tetrahydro-pteridine derivatives 94-96 proceeded in the expected manner. The characterization of ther newly synthesized pteridine derivatives was performed by 1H-NMR spectra, UV-spectra and elemental analyses. Measurements of the basic pKa values of a selection of 2,4,7-trisubstituted pteridines were pteridines to characterize the dication, monocation and the neutral species by their UV-spectra.
- Published
- 2004
- Full Text
- View/download PDF
15. Quality of life of patients after retropubic prostatectomy - Pre- and postoperative scores of the EORTC QLQ-C30 and QLQ-PR25
- Author
-
Bach Peter, Döring Tanja, Gesenberg Andreas, Möhring Cornelia, and Goepel Mark
- Subjects
Computer applications to medicine. Medical informatics ,R858-859.7 - Abstract
Abstract Background Patients with newly diagnosed early stage prostate cancer (PCa) face a difficult choice of different treatment options with curative intention. They must consider both goals of optimising quantity and quality of life. The quality of life (QoL) is a psychometric outcome which is measured using validated questionnaires. Only few data are published concerning pre - and postoperative QoL. Methods This study investigated pre perative QoL of 185 patients who consecutively underwent open radical retropubic prostatectomy for organ-confined PCa to postoperative QoL of another 185 patients. The EORTC QLQ-C30, EORTC QLQPR25 module and 24 h ICS pad test were used (mean follow-up 28.6 months). Results The examined symptom scores of the EORTC QLQ-PR25 were on lowest level. In the dyspnoea symptom score differences of age emerged: the amount of patients who are short of breath rose significantly in older patients after surgery (p < 0.05 paired, two-tailed student's t-test).. Lastly, the urinary symptom score was found postal-therapeutically low; this fact was age independent. The results of sexual symptom score need to be taken into consideration, since prostatectomy resulted in a significant reduction of sexual activity independent of age. All functioning scales postoperatively reached high values without significant changes (p > 0.05 student's t-test ), which implies a high QoL after surgery. A reliable and satisfying status of continence was found in our patients after retropubic prostatectomy. A high rate of patients (89.2%) would choose retropubic prostatectomy again. Conclusion Retropubic prostatectomy represents a reliable and accepted procedure in the treatment of organ-confined PCa. For the first time it could be shown that patients` QoL remained on a high level after retropubic prostatectomy. Nevertheless, the primary avoidance or postoperative therapy of erectile dysfunction should be in the focus of surgeons.
- Published
- 2011
- Full Text
- View/download PDF
16. Severity of white matter microstructural damage in a Brazilian relapsing-remitting multiple sclerosis cohort: A possible window to optimize treatment.
- Author
-
Correia R, Corrêa D, Doring T, Theodoro C, Correia A, Coelho V, Dib JG, Marchiori E, Alves Leon SV, and Rueda Lopes FC
- Subjects
- Young Adult, Humans, Diffusion Tensor Imaging methods, Brazil, Anisotropy, Brain, White Matter diagnostic imaging, Multiple Sclerosis, Relapsing-Remitting diagnostic imaging, Multiple Sclerosis
- Abstract
Background: Multiple sclerosis (MS) is an important cause of acquired neurological disability in young adults, characterized by multicentric inflammation, demyelination, and axonal damage., Objective: The objective is to investigate white matter (WM) damage progression in a Brazilian MS patient cohort, using diffusion tensor imaging (DTI) post-processed by tract-based spatial statistics (TBSS)., Methods: DTI scans were acquired from 76 MS patients and 37 sex-and-age matched controls. Patients were divided into three groups based on disease duration. DTI was performed along 30 non-collinear directions by using a 1.5T imager. For TBSS analysis, the WM skeleton was created, and a 5000 permutation-based inference with a threshold of p < .05 was used, to enable the identification of abnormalities in fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD)., Results: Decreased FA and increased RD, MD, and AD were seen in patients compared to controls and a decreased FA and increased MD and RD were seen, predominantly after the first 5 years of disease, when compared between groups., Conclusion: Progressive WM deterioration is seen over time with a more prominent pattern after 5 years of disease onset, providing evidence that the early years might be a window to optimize treatment and prevent disability., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
- Published
- 2024
- Full Text
- View/download PDF
17. Widespread white matter DTI alterations in mesial temporal sclerosis independent of disease side.
- Author
-
Corrêa DG, Pereira M, Zimmermann N, Doring T, Ventura N, Rêgo C, Marcondes J, Alves-Leon SV, and Gasparetto EL
- Subjects
- Adolescent, Adult, Epilepsy, Temporal Lobe diagnostic imaging, Female, Humans, Male, Middle Aged, Sclerosis pathology, White Matter diagnostic imaging, Young Adult, Diffusion Tensor Imaging methods, Epilepsy, Temporal Lobe pathology, White Matter pathology
- Abstract
Purpose: The aim of this study was to evaluate white matter (WM) integrity in vivo in patients with unilateral mesial temporal sclerosis (MTS)., Methods: Diffusion tensor imaging (DTI) findings from patients with left-sided MTS (L-MTS; N = 14) and right-sided MTS (R-MTS; N = 13), all taking antiepileptic medication, were compared with those from gender- and age-matched controls; DTI was performed along 30 noncollinear directions in a 1.5-T scanner. Tract-based spatial statistics (TBSS) analysis was performed by creating a WM skeleton; 5000-permutation-based inference (threshold, p < 0.05) was used to identify fractional anisotropy (FA) abnormalities. Mean (MD), radial (RD), and axial diffusivities (AD) were projected onto the mean FA skeleton., Results: Compared with the control groups, patients with MTS had decreased FA affecting widespread WM tracts as well as extensive areas with increased RD, bilaterally and independent of the disease side. Areas with decreased FA and increased RD overlapped substantially. There were no significant differences in DTI parameters between L-MTS and R-MTS patients., Conclusion: Diffusion tensor imaging abnormalities were observed within and beyond the temporal lobe in patients with MTS. Patients with R- and L-MTS had extensive bilateral abnormalities in comparison to controls. These findings suggest that MTS pathobiology involves diffuse dysfunction of WM tracts, even in areas with no direct connections to the hippocampus., (Copyright © 2018 Elsevier Inc. All rights reserved.)
- Published
- 2018
- Full Text
- View/download PDF
18. Longitudinal evaluation of resting-state connectivity, white matter integrity and cortical thickness in stable HIV infection: Preliminary results.
- Author
-
Corrêa DG, Zimmermann N, Ventura N, Tukamoto G, Doring T, Leite SC, Fonseca RP, Bahia PR, Lopes FC, and Gasparetto EL
- Subjects
- Adult, CD4 Lymphocyte Count, Diffusion Tensor Imaging, Female, Gray Matter pathology, Humans, Image Interpretation, Computer-Assisted, Longitudinal Studies, Male, Middle Aged, Neuropsychological Tests, Viral Load, Antiretroviral Therapy, Highly Active, HIV Infections drug therapy, HIV Infections pathology, Magnetic Resonance Imaging methods, White Matter pathology
- Abstract
Purpose The objectives of this study were to determine if HIV-infected patients treated with highly active antiretroviral therapy (HAART), without dementia, suffer from longitudinal gray matter (GM) volume loss, changes in white matter (WM) integrity and deterioration in functional connectivity at rest, in an average interval of 30 months. Methods Clinically stable HIV-positive patients (on HAART, CD4 + T lymphocyte > 200 cells/μl, and viral loads <50 copies/μl) were recruited. None of them had HIV-associated dementia. Each patient underwent two scans, performed in a 1.5-T magnetic resonance imaging (MRI) scanner. FreeSurfer was used to perform cortical volumetric reconstruction and segmentation of GM structures. WM integrity was assessed using tract-based spatial statistics to post-process diffusion tensor imaging data, and FMRIB's Software Library tools were used to post-process resting-state functional magnetic resonance imaging (RS-fMRI). Results There were no significant differences in cortical thickness, deep GM volumes, or diffusivity parameters between the scans at the two time points. Five resting-state networks were identified in our patients. In the second MRI, HIV-positive patients presented increased areas of functional connectivity in visual pathways, frontoparietal and cerebellar networks, compared with the first MRI (considering p < 0.05). Conclusions RS-fMRI revealed potentially compensatory longitudinal alterations in the brains of HIV-positive patients, attempting to compensate for brain damage related to the infection.
- Published
- 2017
- Full Text
- View/download PDF
19. Longitudinal assessment of subcortical gray matter volume, cortical thickness, and white matter integrity in HIV-positive patients.
- Author
-
Corrêa DG, Zimmermann N, Tukamoto G, Doring T, Ventura N, Leite SC, Cabral RF, Fonseca RP, Bahia PR, and Gasparetto EL
- Subjects
- Adult, Antiretroviral Therapy, Highly Active methods, Encephalitis, Viral immunology, Female, Gray Matter immunology, HIV Infections immunology, Humans, Longitudinal Studies, Male, Middle Aged, Organ Size immunology, Treatment Outcome, Viral Load immunology, White Matter immunology, Diffusion Tensor Imaging methods, Encephalitis, Viral drug therapy, Encephalitis, Viral pathology, Gray Matter pathology, HIV Infections drug therapy, HIV Infections pathology, White Matter pathology
- Abstract
Purpose: To longitudinally evaluate the cortical thickness and deep gray matter structures volume, measured from T1 three-dimensional (3D) Gradient echo-weighted imaging, and white matter integrity, assessed from diffusion tensor imaging (DTI) of HIV-positive patients., Materials and Methods: Twenty-one HIV-positive patients on stable highly active antiretroviral therapy (HAART) with CD4+ T lymphocytes count >200 cells/mL and viral load <50 copies/mL underwent two magnetic resonance imaging (MRI) scans with a median interval of 26.6 months. None of the patients had HIV-related dementia. T1 3D magnetization prepared rapid gradient echo-weighted imaging and DTI along 30 noncolinear directions were performed using a 1.5 Tesla MR scanner. FreeSurfer was used to perform cortical volumetric reconstruction and segmentation of deep gray matter structures. For tract-based spatial statistics analysis, a white matter skeleton was created, and a permutation-based inference with 5000 permutations, with a threshold of P < 0.05 was used to identify abnormalities in fractional anisotropy (FA). The median, radial, and axial diffusivities were also projected onto the mean FA skeleton., Results: There were no significant differences in cortical thickness, deep gray matter structures volumes or diffusivity parameters between scans at the two time points (considering P < 0.05)., Conclusion: No longitudinal differences in cortical thickness, deep gray matter volumes, or white matter integrity were observed in an HIV-positive population on stable HAART, with undetectable viral load and high CD4+ T lymphocytes count. J. Magn. Reson. Imaging 2016;44:1262-1269., (© 2016 International Society for Magnetic Resonance in Medicine.)
- Published
- 2016
- Full Text
- View/download PDF
20. Diffusion tensor imaging and tract-based spatial statistics analysis in Friedreich's ataxia patients.
- Author
-
Vieira Karuta SC, Raskin S, de Carvalho Neto A, Gasparetto EL, Doring T, and Teive HA
- Subjects
- Adolescent, Adult, Female, Humans, Magnetic Resonance Imaging methods, Male, Young Adult, Diffusion Tensor Imaging methods, Friedreich Ataxia diagnosis, Friedreich Ataxia metabolism
- Abstract
Introduction: Friedreich's ataxia (FRDA) is the most common hereditary ataxia and thinning of the cervical spinal cord is a consistent observation in Magnetic resonance imaging (MRI), although neuropathological examination in FRDA reveals neuronal loss in gray matter (GM) nuclei and degeneration of white matter (WM) tracts in the spinal cord, brainstem and cerebellum. Using diffusion-tensor (DTI) imaging and tract-based spatial statistics (TBSS) we tested the hypothesis that WM damage in FRDA is more extensive than previously described and probably involves normal-appearing WM., Methods: This transversal study included 21 genetically confirmed FRDA patients and seventeen healthy controls that underwent structural MRI of the brain on a 1.5 T scanner. We quantify the severity of ataxia using SARA scale. DTI was performed and diffusion data were analyzed using FMRIB's Diffusion Toolbox in FSL 4.1 in order to identify Fractional anisotropy (FA) decreases in specific brain regions and also the mean, radial and axial diffusivities (MD, RD, AD)., Results: The greatest decreases in FA were in the left superior cerebellar peduncle, left posterior thalamic radiation, major forceps, left inferior fronto-occipital fasciculus and corpus callosum and had a significance level of p < 0.01. No significant correlation between FA, AD, MD and RD values and the clinical findings, SARA scores and genetic expansion was found., Conclusion: DTI and TBSS techniques clearly demonstrate the extensive cerebral and cerebellar involvement in FRDA, partially explaining the clinical phenotype of the disease. Further studies are needed with larger samples to correlate clinical, genetic findings and ataxia scores., (Copyright © 2015 Elsevier Ltd. All rights reserved.)
- Published
- 2015
- Full Text
- View/download PDF
21. Neuromyelitis optica: a diffusional kurtosis imaging study.
- Author
-
Doring TM, Lopes FC, Kubo TT, Tukamoto G, Kimura MC, Strecker RM, Domingues RC, and Gasparetto EL
- Subjects
- Adolescent, Adult, Anisotropy, Biometry, Corpus Callosum pathology, Female, Humans, Male, Middle Aged, Neuromyelitis Optica pathology, Young Adult, Diffusion Tensor Imaging methods, Neuromyelitis Optica diagnosis, White Matter pathology
- Abstract
Background and Purpose: Conventional MR imaging typically yields normal images of the brain or indicates lesions in areas of high aquaporin expression in patients with neuromyelitis optica. Diffusional kurtosis imaging was applied in patients with neuromyelitis optica to determine whether this technique could detect alterations in diffusion and diffusional kurtosis parameters in normal-appearing white matter and to explore the relationship between diffusional kurtosis imaging and DTI parameters., Materials and Methods: Thirteen patients with neuromyelitis optica and 13 healthy controls underwent MR imaging of the brain with conventional and diffusional kurtosis imaging sequences. Tract-based spatial statistics and region-of-interest-based analyses were conducted to identify differences between patients with neuromyelitis optica and controls through conventional DTI and diffusional kurtosis imaging parameters. The parameters were correlated to determine the potential relationship between them., Results: Compared with healthy controls, several diffusional kurtosis imaging and DTI parameters were altered in various fiber tracts of patients with neuromyelitis optica (P < .05). A significant decrease (P < .05) in radial kurtosis was observed in the corpus callosum and anterior corona radiata and left optic radiation. Differences (P < .1) in mean kurtosis were found in patients with neuromyelitis optica. We found a negative correlation between diffusional kurtosis imaging (radial kurtosis, axial kurtosis, mean kurtosis) and the corresponding DTI parameters (radial diffusivity, axial diffusivity, mean diffusivity). Positive correlations were found for radial kurtosis and mean kurtosis with fractional anisotropy., Conclusions: This study demonstrated differences in conventional diffusion and diffusional kurtosis parameters, especially radial kurtosis, in the normal-appearing white matter of patients with neuromyelitis optica compared with healthy controls. Larger studies of patients with neuromyelitis optica should be performed to assess the potential clinical impact of these findings., (© 2014 by American Journal of Neuroradiology.)
- Published
- 2014
- Full Text
- View/download PDF
22. The role of demyelination in neuromyelitis optica damage: diffusion-tensor MR imaging study.
- Author
-
Rueda Lopes FC, Doring T, Martins C, Cabral FC, Malfetano FR, Pereira VC, Alves-Leon S, and Gasparetto EL
- Subjects
- Adult, Aged, Contrast Media, Female, Gadolinium DTPA, Humans, Male, Middle Aged, Statistics, Nonparametric, Diffusion Tensor Imaging methods, Nerve Fibers, Myelinated pathology, Neuromyelitis Optica pathology
- Abstract
Purpose: To test the hypothesis that white matter damage in neuromyelitis optica (NMO) is more extensive than previously described and likely includes involvement of normal-appearing white matter and to explore by using diffusion-tensor (DT) imaging whether white matter lesions are not only related to wallerian degeneration but are also caused by demyelination., Materials and Methods: Seventeen patients with NMO (mean age, 45 years; 14 women) were compared with 17 sex- and age-matched control subjects. The institutional review board approved the study, and all subjects gave written informed consent. In addition to conventional magnetic resonance imaging sequences, DT imaging was performed along 30 noncollinear directions by using a 1.5-T imager. For tract-based spatial statistics (TBSS) analysis, the white matter skeleton was created, and a permutation-based inference with 5000 permutations with a threshold of P less than .05 to enable the identification of abnormalities in fractional anisotropy (FA), radial diffusivity (RD), and axial diffusivity (AD) was used. Partial correlation was applied to identify whether the number of clinical relapses and disease duration were correlated with all TBSS parameters., Results: TBSS showed multiple areas with significant FA decrease in patients with NMO, mainly located in the corona radiata, uncinate fasciculus, corpus callosum, optic radiation, internal and external capsules, and cerebral peduncles. The mean FA, RD, and AD in the abnormal voxels located on the corpus callosum were, respectively, 0.69 ± 0.03 (standard deviation), 0.39 × 10(23) mm(2)/sec ± 0.04, and 1.53 × 10(23) mm(2)/sec ± 0.04 in patients with NMO compared with 0.75 ± 0.02, 0.33 × 10(23) mm(2)/sec ± 0.03, and 1.57 × 10(23) mm(2)/sec ± 0.04 in control subjects (P < .0001, P < .0001, and P = .007, respectively). There was a highly significant inverse correlation between FA and RD (r = 20.976, P < .0001)., Conclusion: The use of TBSS allowed the identification of extensive white matter damage in patients with NMO. Multiple white matter tracts were involved, including the pyramidal tract, optic radiation, and corpus callosum, likely related to both demyelination and wallerian degeneration., (© RSNA, 2012.)
- Published
- 2012
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.