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Sample records for jnis vtra mra

  1. 3MRA UNCERTAINTY AND SENSITIVITY ANALYSIS

    EPA Science Inventory

    This presentation discusses the Multimedia, Multipathway, Multireceptor Risk Assessment (3MRA) modeling system. The outline of the presentation is: modeling system overview - 3MRA versions; 3MRA version 1.0; national-scale assessment dimensionality; SuperMUSE: windows-based super...

  2. Uterine cirsoid aneurysm: MRI and MRA

    SciTech Connect

    Joja, Ikuo; Asakawa, Mari; Motoyama, Kazumi

    1996-03-01

    Uterine cirsoid aneurysm is uncommon. It is important to make a diagnosis of this disease preoperatively, because repeated curettages may induce life-threatening massive genital bleeding. We present a case of a 51-year-old woman with uterine cirsoid aneurysm in whom MRI and MRA were very useful for the preoperative diagnosis. The radiologic appearances on ultrasonography, CT, conventional SE MRI, MRA, dynamic MRI, and pelvic angiography are presented. Conventional SE T1-weighted and T2-weighted images demonstrated multiple flow voids in the uterus and bilateral adnexal regions. MRA demonstrated a cluster of distinct, tortuous, and coiled vascular channels in the pelvis. MRA could obtain images almost equal to angiography and was considered to be an excellent noninvasive imaging technique for the diagnosis of uterine cirsoid aneurysm. 28 refs., 7 figs

  3. Your Radiologist Explains Magnetic Resonance Angiography (MRA)

    MedlinePlus

    ... this Site RadiologyInfo.org is produced by: Image/Video Gallery Your Radiologist Explains Magnetic Resonance Angiography (MRA) ... time and for your attention! Spotlight Recently posted: Video: Ultrasound-guided Breast Biopsy Video: Breast MRI Video: ...

  4. Nonenhanced peripheral MR-angiography (MRA) at 3 Tesla: evaluation of quiescent-interval single-shot MRA in patients undergoing digital subtraction angiography.

    PubMed

    Wagner, Moritz; Knobloch, Gesine; Gielen, Martin; Lauff, Marie-Teres; Romano, Valentina; Hamm, Bernd; Kröncke, Thomas

    2015-04-01

    Quiescent-interval single-shot MRA (QISS-MRA) is a promising nonenhanced imaging technique for assessment of peripheral arterial disease (PAD). Previous studies at 3 Tesla included only very limited numbers of patients for correlation of QISS-MRA with digital subtraction angiography (DSA) as standard of reference (SOR). The aim of this prospective institutional review board-approved study was to compare QISS-MRA at 3 Tesla with DSA in a larger patient group. Our study included 32 consecutive patients who underwent QISS-MRA, contrast-enhanced MRA (CE-MRA), and DSA. Two readers independently performed a per-segment evaluation of QISS-MRA and CE-MRA for image quality and identification of non-significant stenosis (<50%) versus significant stenosis (50-100%). The final dataset included 1,027 vessel segments. Reader 1 and 2 rated image quality as diagnostic in 96.8 and 98.0% of the vessel segments on QISS-MRA and in 99.3 and 98.4% of the vessel segments on CE-MRA, respectively. DSA was available for 922 segments and detected significant stenosis in 133 segments (14.4%). Consensus reading yielded the following diagnostic parameters for QISS-MRA versus CE-MRA: sensitivity: 83.5% (111/133) versus 82.7% (110/133), p = 0.80; specificity: 93.9% (741/789) versus 95.7% (755/789), p = 0.25; and diagnostic accuracy: 92.4% (852/922) versus 93.8% (865/922), p = 0.35. In conclusion, using DSA as SOR, QISS-MRA and CE-MRA at 3 Tesla showed similar diagnostic accuracy in the assessment of PAD. A limitation of QISS-MRA was the lower rate of assessable vessel segments compared to CE-MRA.

  5. CBCT-based 3D MRA and angiographic image fusion and MRA image navigation for neuro interventions

    PubMed Central

    Zhang, Qiang; Zhang, Zhiqiang; Yang, Jiakang; Sun, Qi; Luo, Yongchun; Shan, Tonghui; Zhang, Hao; Han, Jingfeng; Liang, Chunyang; Pan, Wenlong; Gu, Chuanqi; Mao, Gengsheng; Xu, Ruxiang

    2016-01-01

    Abstract Digital subtracted angiography (DSA) remains the gold standard for diagnosis of cerebral vascular diseases and provides intraprocedural guidance. This practice involves extensive usage of x-ray and iodinated contrast medium, which can induce side effects. In this study, we examined the accuracy of 3-dimensional (3D) registration of magnetic resonance angiography (MRA) and DSA imaging for cerebral vessels, and tested the feasibility of using preprocedural MRA for real-time guidance during endovascular procedures. Twenty-three patients with suspected intracranial arterial lesions were enrolled. The contrast medium-enhanced 3D DSA of target vessels were acquired in 19 patients during endovascular procedures, and the images were registered with preprocedural MRA for fusion accuracy evaluation. Low-dose noncontrasted 3D angiography of the skull was performed in the other 4 patients, and registered with the MRA. The MRA was overlaid afterwards with 2D live fluoroscopy to guide endovascular procedures. The 3D registration of the MRA and angiography demonstrated a high accuracy for vessel lesion visualization in all 19 patients examined. Moreover, MRA of the intracranial vessels, registered to the noncontrasted 3D angiography in the 4 patients, provided real-time 3D roadmap to successfully guide the endovascular procedures. Radiation dose to patients and contrast medium usage were shown to be significantly reduced. Three-dimensional MRA and angiography fusion can accurately generate cerebral vasculature images to guide endovascular procedures. The use of the fusion technology could enhance clinical workflow while minimizing contrast medium usage and radiation dose, and hence lowering procedure risks and increasing treatment safety. PMID:27512846

  6. CBCT-based 3D MRA and angiographic image fusion and MRA image navigation for neuro interventions.

    PubMed

    Zhang, Qiang; Zhang, Zhiqiang; Yang, Jiakang; Sun, Qi; Luo, Yongchun; Shan, Tonghui; Zhang, Hao; Han, Jingfeng; Liang, Chunyang; Pan, Wenlong; Gu, Chuanqi; Mao, Gengsheng; Xu, Ruxiang

    2016-08-01

    Digital subtracted angiography (DSA) remains the gold standard for diagnosis of cerebral vascular diseases and provides intraprocedural guidance. This practice involves extensive usage of x-ray and iodinated contrast medium, which can induce side effects. In this study, we examined the accuracy of 3-dimensional (3D) registration of magnetic resonance angiography (MRA) and DSA imaging for cerebral vessels, and tested the feasibility of using preprocedural MRA for real-time guidance during endovascular procedures.Twenty-three patients with suspected intracranial arterial lesions were enrolled. The contrast medium-enhanced 3D DSA of target vessels were acquired in 19 patients during endovascular procedures, and the images were registered with preprocedural MRA for fusion accuracy evaluation. Low-dose noncontrasted 3D angiography of the skull was performed in the other 4 patients, and registered with the MRA. The MRA was overlaid afterwards with 2D live fluoroscopy to guide endovascular procedures.The 3D registration of the MRA and angiography demonstrated a high accuracy for vessel lesion visualization in all 19 patients examined. Moreover, MRA of the intracranial vessels, registered to the noncontrasted 3D angiography in the 4 patients, provided real-time 3D roadmap to successfully guide the endovascular procedures. Radiation dose to patients and contrast medium usage were shown to be significantly reduced.Three-dimensional MRA and angiography fusion can accurately generate cerebral vasculature images to guide endovascular procedures. The use of the fusion technology could enhance clinical workflow while minimizing contrast medium usage and radiation dose, and hence lowering procedure risks and increasing treatment safety. PMID:27512846

  7. The highly conserved MraZ protein is a transcriptional regulator in Escherichia coli

    SciTech Connect

    Eraso, Jesus M.; Markillie, Lye Meng; Mitchell, Hugh D.; Taylor, Ronald C.; Orr, Galya; Margolin, William

    2014-05-05

    The mraZ and mraW genes are highly conserved in bacteria, both in sequence and location at the head of the division and cell wall (dcw) gene cluster. Although MraZ has structural similarity to the AbrB transition state regulator and the MazE antitoxin, and MraW is known to methylate ribosomal RNA, mraZ and mraW null mutants have no detectable growth phenotype in any species tested to date, hampering progress in understanding their physiological role. Here we show that overproduction of Escherichia coli MraZ perturbs cell division and the cell envelope, is more lethal at high levels or in minimal growth medium, and that MraW antagonizes these effects. MraZGFP localizes to the nucleoid, suggesting that it binds DNA. Indeed, purified MraZ directly binds a region upstream from its own promoter containing three direct repeats to regulate its own expression and that of downstream cell division and cell wall genes. MraZ-LacZ fusions are repressed by excess MraZ but not when DNA binding by MraZ is inhibited. RNAseq analysis indicates that MraZ is a global transcriptional regulator with numerous targets in addition to dcw genes. One of these targets, mioC, is directly bound by MraZ in a region with three direct repeats.

  8. Structural Investigation of Park’s Nucleotide on Bacterial Translocase MraY: Discovery of Unexpected MraY Inhibitors

    PubMed Central

    Chen, Kuo-Ting; Chen, Po-Ting; Lin, Cheng-Kun; Huang, Lin-Ya; Hu, Chia-Ming; Chang, Yi-Fan; Hsu, Hua-Ting; Cheng, Ting-Jen R.; Wu, Ying-Ta; Cheng, Wei-Chieh

    2016-01-01

    Systematic structural modifications of the muramic acid, peptide, and nucleotide moieties of Park’s nucleotide were performed to investigate the substrate specificity of B. subtilis MraY (MraYBS). It was found that the simplest analogue of Park’s nucleotide only bearing the first two amino acids, l-alanine-iso-d-glutamic acid, could function as a MraYBS substrate. Also, the acid group attached to the Cα of iso-d-glutamic acid was found to play an important role for substrate activity. Epimerization of the C4-hydroxyl group of muramic acid and modification at the 5-position of the uracil in Park’s nucleotide were both found to dramatically impair their substrate activity. Unexpectedly, structural modifications on the uracil moiety changed the parent molecule from a substrate to an inhibitor, blocking the MraYBS translocation. One unoptimized inhibitor was found to have a Ki value of 4 ± 1 μM against MraYBS, more potent than tunicamycins. PMID:27531195

  9. Automated diagnosis of rolling bearings using MRA and neural networks

    NASA Astrophysics Data System (ADS)

    Castejón, C.; Lara, O.; García-Prada, J. C.

    2010-01-01

    Any industry needs an efficient predictive plan in order to optimize the management of resources and improve the economy of the plant by reducing unnecessary costs and increasing the level of safety. A great percentage of breakdowns in productive processes are caused by bearings. They begin to deteriorate from early stages of their functional life, also called the incipient level. This manuscript develops an automated diagnosis of rolling bearings based on the analysis and classification of signature vibrations. The novelty of this work is the application of the methodology proposed for data collected from a quasi-real industrial machine, where rolling bearings support the radial and axial loads the bearings are designed for. Multiresolution analysis (MRA) is used in a first stage in order to extract the most interesting features from signals. Features will be used in a second stage as inputs of a supervised neural network (NN) for classification purposes. Experimental results carried out in a real system show the soundness of the method which detects four bearing conditions (normal, inner race fault, outer race fault and ball fault) in a very incipient stage.

  10. Natural Products at Work: Structural Insights into Inhibition of the Bacterial Membrane Protein MraY.

    PubMed

    Koppermann, Stefan; Ducho, Christian

    2016-09-19

    Natural(ly) fit: The X-ray crystal structure of the bacterial membrane protein MraY in complex with its natural product inhibitor muraymycin D2 is discussed. MraY catalyzes one of the membrane-associated steps in peptidoglycan biosynthesis and, therefore, represents a promising target for novel antibiotics. Structural insights derived from the protein-inhibitor complex might now pave the way for the development of new antimicrobial drugs. PMID:27511599

  11. New Insight into the Catalytic Mechanism of Bacterial MraY from Enzyme Kinetics and Docking Studies.

    PubMed

    Liu, Yao; Rodrigues, João P G L M; Bonvin, Alexandre M J J; Zaal, Esther A; Berkers, Celia R; Heger, Michal; Gawarecka, Katarzyna; Swiezewska, Ewa; Breukink, Eefjan; Egmond, Maarten R

    2016-07-15

    Phospho-MurNAc-pentapeptide translocase (MraY) catalyzes the synthesis of Lipid I, a bacterial peptidoglycan precursor. As such, MraY is essential for bacterial survival and therefore is an ideal target for developing novel antibiotics. However, the understanding of its catalytic mechanism, despite the recently determined crystal structure, remains limited. In the present study, the kinetic properties of Bacillus subtilis MraY (BsMraY) were investigated by fluorescence enhancement using dansylated UDP-MurNAc-pentapeptide and heptaprenyl phosphate (C35-P, short-chain homolog of undecaprenyl phosphate, the endogenous substrate of MraY) as second substrate. Varying the concentrations of both of these substrates and fitting the kinetics data to two-substrate models showed that the concomitant binding of both UDP-MurNAc-pentapeptide-DNS and C35-P to the enzyme is required before the release of the two products, Lipid I and UMP. We built a model of BsMraY and performed docking studies with the substrate C35-P to further deepen our understanding of how MraY accommodates this lipid substrate. Based on these modeling studies, a novel catalytic role was put forward for a fully conserved histidine residue in MraY (His-289 in BsMraY), which has been experimentally confirmed to be essential for MraY activity. Using the current model of BsMraY, we propose that a small conformational change is necessary to relocate the His-289 residue, such that the translocase reaction can proceed via a nucleophilic attack of the phosphate moiety of C35-P on bound UDP-MurNAc-pentapeptide. PMID:27226570

  12. High temporal and high spatial resolution MR angiography (4D-MRA).

    PubMed

    Hadizadeh, D R; Marx, C; Gieseke, J; Schild, H H; Willinek, W A

    2014-09-01

    In the first decade of the twenty-first century, whole-body magnetic resonance scanners with high field strengths (and thus potentially better signal-to-noise ratios) were developed. At the same time, parallel imaging and "echo-sharing" techniques were refined to allow for increasingly high spatial and temporal resolution in dynamic magnetic resonance angiography ("time-resolved" = TR-MRA). This technological progress facilitated tracking the passage of intra-venously administered contrast agent boluses as well as the acquisition of volume data sets at high image refresh rates ("4D-MRA"). This opened doors for many new applications in non-invasive vascular imaging, including simultaneous anatomic and functional analysis of many vascular pathologies including arterio-venous malformations. Different methods were established to acquire 4D-MRA using various strategies to acquire k-space trajectories over time in order to optimize imaging according to clinical needs. These include "keyhole"-based techniques (e. g. 4D-TRAK), TRICKS - both with and without projection - and HYPR-reconstruction, TREAT, and TWIST. Some of these techniques were first introduced in the 1980 s and 1990 s, were later enhanced and modified, and finally implemented in the products of major vendors. In the last decade, a large number of studies on the clinical applications of TR-MRA was published. This manuscript provides an overview of the development of TR-MRA methods and the 4D-MRA techniques as they are currently used in the diagnosis, treatment and follow-up of vascular diseases in various parts of the body. PMID:24955647

  13. Diagnostic value of 3D time-of-flight MRA in trigeminal neuralgia.

    PubMed

    Cai, Jing; Xin, Zhen-Xue; Zhang, Yu-Qiang; Sun, Jie; Lu, Ji-Liang; Xie, Feng

    2015-08-01

    The aim of this meta-analysis was to evaluate the diagnostic value of 3D time-of-flight magnetic resonance angiography (3D-TOF-MRA) in trigeminal neuralgia (TN). Relevant studies were identified by computerized database searches supplemented by manual search strategies. The studies were included in accordance with stringent inclusion and exclusion criteria. Following a multistep screening process, high quality studies related to the diagnostic value of 3D-TOF-MRA in TN were selected for meta-analysis. Statistical analyses were conducted using Statistical Analysis Software (version 8.2; SAS Institute, Cary, NC, USA) and Meta Disc (version 1.4; Unit of Clinical Biostatistics, Ramon y Cajal Hospital, Madrid, Spain). For the present meta-analysis, we initially retrieved 95 studies from database searches. A total of 13 studies were eventually enrolled containing a combined total of 1084 TN patients. The meta-analysis results demonstrated that the sensitivity and specificity of the diagnostic value of 3D-TOF-MRA in TN were 95% (95% confidence interval [CI] 0.93-0.96) and 77% (95% CI 0.66-0.86), respectively. The pooled positive likelihood ratio and negative likelihood ratio were 2.72 (95% CI 1.81-4.09) and 0.08 (95% CI 0.06-0.12), respectively. The pooled diagnostic odds ratio of 3D-TOF-MRA in TN was 52.92 (95% CI 26.39-106.11), and the corresponding area under the curve in the summary receiver operating characteristic curve based on the 3D-TOF-MRA diagnostic image of observers was 0.9695 (standard error 0.0165). Our results suggest that 3D-TOF-MRA has excellent sensitivity and specificity as a diagnostic tool for TN, and that it can accurately identify neurovascular compression in TN patients. PMID:26077938

  14. 3D DCE-MRA of pedal arteries in patients with diabetes mellitus

    NASA Astrophysics Data System (ADS)

    Zamyshevskaya, M.; Zavadovskaya, V.; Zorkaltsev, M.; Udodov, V.; Grigorev, E.

    2016-02-01

    Purpose was identification and evaluation of pedal vascularization in diabetic patients of using contrast MR-angiography (3D DCE-MRA). 23 diabetic feet of 23 patients (15 male, 8 female; mean age 56 ± 14.6) underwent 3D DCE-MRA (Gadobutrol 15ml) at 1.5 T. Imaging analysis included blood-flow's speed, vascular architectonic's condition and character of contrast's accumulation. Osteomyelitis was verified by surgery in 15 cases. All patients were divided in 3 groups: neuropathic, neuroischemic, ischemic forms of diabetic foot. First- pass MRA detected significant delay of contrast's arrival in ischemic group. There were no significant differences between the values of neuropathic and neuroischemic forms of diabetic foot. Pedal vessels in patients were absent. Contrast MRA revealed three types of contrast distribution in soft tissues: uniform, local increase and local absence. Osteomyelitis was associated with diffuse enhanced contrast accumulation in all cases. In summary, MRI blood vessel imaging is a promising and valuable method for examining peripheral arterial changes in diabetic foot and might be useful for treatment planning in different forms of diabetic foot.

  15. The Mycobacterium tuberculosis H37Ra gene MRA_1916 causes growth defects upon down-regulation

    PubMed Central

    Singh, Kumar Sachin; Singh, Sudheer Kumar

    2015-01-01

    D-amino acid oxidases play an important role in converting D-amino acids to their corresponding α-keto acids. MRA_1916 of Mycobacterium tuberculosis H37Ra (Mtb-Ra) is annotated to be a D-amino acid oxidase (DAO). However, not much information is available about its physiological role during Mtb-Ra growth and survival. The present study was taken-up to understand the role of DAO during different stages of growth and effect of its down-regulation on growth. Recombinant Mtb-Ra strains with DAO and GlcB (malate synthase: MRA_1848) gene knockdown were developed and their growth was studied using Microtiter Alamar Blue Assay (MABA) with glycerol, acetate and glycine as a carbon source. Ethyl bromopyruvate (BrP) was used as an inhibitor of GlcB. MABA study showed inhibition of wild-type (WT) and knockdowns in the presence of BrP (2.5mM). However, growth inhibition of WT was less noticeable at lower concentrations of BrP. Mtb-Ra with DAO knockdown showed poor utilization of glycine in the presence of BrP. The DAO localization study showed its prominent distribution in cytosolic fraction and to some extent in cell wall and membrane fractions. Growth profile of WT under oxygen and nutritional stress showed changes in expression of DAO, GlcB, PckA (phosphoenolpyruvate carboxykinase: MRA_0219) and GlyA1 (serine hydroxymethyltransferase: MRA_1104). PMID:26531045

  16. Detection of cerebral aneurysms in MRA, CTA and 3D-RA data sets

    NASA Astrophysics Data System (ADS)

    Hentschke, Clemens M.; Beuing, Oliver; Nickl, Rosa; Tönnies, Klaus D.

    2012-03-01

    We propose a system to automatically detect cerebral aneurysms in 3D X-ray rotational angiography images (3D-RA), magnetic resonance angiography images (MRA) and computed tomography angiography images (CTA). After image normalization, initial candidates are found by applying a blob-enhancing filter on the data sets. Clusters are computed by a modified k-means algorithm. A post-processing step reduces the false positive (FP) rate on the basis of computed features. This is implemented as a rule-based system that is adapted according to the modality. In MRA, clusters are excluded that are not neighbored to a vessel. As a final step, FP are further reduced by applying a threshold classification on a feature. Our method was tested on 93 angiographic data sets containing aneurysm and non-aneurysm cases. We achieved 95 % sensitivity with an average rate of 2.6 FP per data set (FP/DS) in case of 3D-RA, 89 % sensitivity at 6.6 FP/DS for MRA and 95 % sensitivity at 37.6 FP/DS with CTA, respectively. We showed that our post-processing approach eliminates FP in MRA with only a slight decrease of sensitivity. In contrast to other approaches, our algorithm does not require a vessel segmentation and does not require training of distributional properties.

  17. Non-Invasive Follow-up Evaluation of Post-Embolized AVM with Time-Resolved MRA: A Case Report

    PubMed Central

    Shim, Yong Woon; Kang, Won-Suk; Joo, Jin-Yang; Strecker, Ralph; Hennig, Juergen

    2002-01-01

    We report the hemodynamic assessment in a patient with cerebral arteriovenous malformation using time-resolved magnetic resonance angiography (TR-MRA), a non-invasive modality, and catheter-based digital subtraction angiography (DSA), before and after embolization. Comparison of the results showed that TR-MRA produced very fast dynamic images and the findings closely matched those obtained at DSA. For initial work-up and follow-up studies in patients with vascular lesions, TR-MRA and DSA are therefore comparable. PMID:12514347

  18. 5 CFR 875.203 - Am I eligible if I separated under the FERS MRA+10 provision?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... (CONTINUED) CIVIL SERVICE REGULATIONS (CONTINUED) FEDERAL LONG TERM CARE INSURANCE PROGRAM Eligibility § 875... under the FERS Minimum Retirement Age and 10 years of service (MRA+10) provision of 5 U.S.C....

  19. Systolically gated 3D phase contrast MRA of mesenteric arteries in suspected mesenteric ischemia

    SciTech Connect

    Wasser, M.N.; Schultze Kool, L.J.; Roos, A. de

    1996-03-01

    Our goal was to assess the value of MRA for detecting stenoses in the celiac (CA) and superior mesenteric (SMA) arteries in patients suspected of having chronic mesenteric ischemia, using an optimized systolically gated 3D phase contrast technique. In an initial study in 24 patients who underwent conventional angiography of the abdominal vessels for different clinical indications, a 3D phase contrast MRA technique (3D-PCA) was evaluated and optimized to image the CAs and SMAs. Subsequently, a prospective study was performed to assess the value of systolically gated 3D-PCA in evaluation of the mesenteric arteries in 10 patients with signs and symptoms of chronic mesenteric ischemia. Intraarterial digital subtraction angiography and surgical findings were used as the reference standard. In the initial study, systolic gating appeared to be essential in imaging the SMA on 3D-PCA. In 10 patients suspected of mesenteric ischemia, systolically gated 3D-PCA identified significant proximal disease in the two mesenteric vessels in 4 patients. These patients underwent successful reconstruction of their stenotic vessels. Cardiac-gated MRA may become a useful tool in selection of patients suspected of having mesenteric ischemia who may benefit from surgery. 16 refs., 6 figs., 4 tabs.

  20. Anatomic vascular phantom for the verification of MRA and XRA visualization and fusion

    SciTech Connect

    Mankovich, N.J. |; Lambert, T.; Zrimec, T.; Hiller, J.

    1995-12-31

    A project is underway to develop automated methods of fusing cerebral magnetic resonance angiography (MRA) and x-ray angiography (XRA) for creating accurate visualizations used in planning treatment of vascular disease. The authors have developed a vascular phantom suitable for testing segmentation and fusion algorithms with either derived images (pseudo-MRA/pseudo-XRA) or actual MRA or XRA image sequences. The initial unilateral arterial phantom design, based on normal human anatomy, contains 48 tapering vascular segments with lumen diameters from 2.5 millimeter to 0.25 millimeter. The initial phantom used rapid prototyping technology (stereolithography) with a 0.9 millimeter vessel wall fabricated in an ultraviolet-cured plastic. The model fabrication resulted in a hollow vessel model comprising the internal carotid artery, the ophthalmic artery, and the proximal segments of the anterior, middle, and posterior cerebral arteries. The complete model was fabricated but the model`s lumen could not be cleared for vessels with less than 1 millimeter diameter. Measurements of selected vascular outer diameters as judged against the CAD specification showed an accuracy of 0.14 mm and precision (standard deviation) of 0.15 mm. The plastic vascular model produced provides a fixed geometric framework for the evaluation of imaging protocols and the development of algorithms for both segmentation and fusion.

  1. Examining the resting-state vascular connectivity using fMRA in comparison with fMRI: a preliminary study.

    PubMed

    Park, Chan-A; Kang, Chang-Ki; Kim, Young-Bo; Cho, Zang-Hee

    2015-08-01

    This study examined resting-state functional connectivity in the vascular system of the brain using functional magnetic resonance angiography (fMRA) with an ultra-high-field 7 T MRI. Four healthy individuals participated in the functional imaging study using fMRA and functional MRI (fMRI) for determination of vascular and blood oxygenation level-dependent (BOLD) connectivity, respectively. We calculated voxel-wise connectivity maps and measured the correlation coefficients of the region of interest (ROI)-wise connectivity in the resting-state human brain. Z-map in the posterior cingulate cortex showed more correlated voxels in fMRA than fMRI. There was little or weak interhemispheric vascular connectivity using fMRA in the lateral parietal cortex and the lateral temporal cortex. In contrast, both vascular and BOLD interhemispheric correlations in the precentral gyrus were strong. Correlation coefficients for ROI-wise connectivity analysis were statistically different between fMRA and fMRI in the left and right lateral parietal cortex and lateral temporal cortex (P=0.029). Unlike BOLD connectivity, vascular connectivity showed little interhemispheric correlation in the default mode network. These results could provide the vascular connectivity on the basis of arterial response that can only be obtained by fMRA with an ultra-high-field environment along with further studies. Therefore, this method could provide additional and supplementary information for investigating the vascular effect in patients with cerebrovascular disease. PMID:26076337

  2. MRA Images Identification of the Artery Blood Vessel of the Knee with SOM LVQ Neural Networks as Auxiliary.

    PubMed

    Huang, Hung-Chun; Chien, Chia-Hung; Shih, Ting-Fang; Chong, Fok-Ching

    2005-01-01

    The ways of angiography are divided into two kinds at present: the invasive type and the non invasive type. Because the magnetic resonance angiography (MRA) has advantages of the non invasive type, thus people can accept MRA more easily. Presently, to diagnoses for the initial stage triage of the blood vessel on clinic by MRA mostly. We to be allowed to see clearly that the shape of lower limb artery which like the dendrite and the blood vessel is thick from the trunk to the thin branch, also we can see the narrow embolism and the blocked place through MRA. This study is aiming at the image of artery of blood vessel by MRA assay, and is attempting to use two-dimensional structure of SOM and LVQ to make out topologies for the shape of artery of blood vessel. We expect that MRA could be useful tools for earlier on the quick triage and auxiliary diagnosis of doctors. By actual examples truly prove that patients after peripheral arterial occlusive disease (PAOD) treatment can diagnose effectively, shorten the time of patients waiting for reports and improve the whole efficiency of the medical treatment system.

  3. Artery-vein separation via MRA--an image processing approach.

    PubMed

    Lei, T; Udupa, J K; Saha, P K; Odhner, D

    2001-08-01

    This paper presents a near-automatic process for separating vessels from background and other clutter as well as for separating arteries and veins in contrast-enhanced magnetic resonance angiographic (CE-MRA) image data, and an optimal method for three-dimensional visualization of vascular structures. The separation process utilizes fuzzy connected object delineation principles and algorithms. The first step of this separation process is the segmentation of the entire vessel structure from the background and other clutter via absolute fuzzy connectedness. The second step is to separate artery from vein within this entire vessel structure via iterative relative fuzzy connectedness. After seed voxels are specified inside artery and vein in the CE-MRA image, the small regions of the bigger aspects of artery and vein are separated in the initial iterations, and further detailed aspects of artery and vein are included in later iterations. At each iteration, the artery and vein compete among themselves to grab membership of each voxel in the vessel structure based on the relative strength of connectedness of the voxel in the artery and vein. This approach has been implemented in a software package for routine use in a clinical setting and tested on 133 CE-MRA studies of the pelvic region and two studies of the carotid system from six different hospitals. In all studies, unified parameter settings produced correct artery-vein separation. When compared with manual segmentation/separation, our algorithms were able to separate higher order branches, and therefore produced vastly more details in the segmented vascular structure. The total operator and computer time taken per study is on the average about 4.5 min. To date, this technique seems to be the only image processing approach that can be routinely applied for artery and vein separation.

  4. Computerized detection of unruptured aneurysms in MRA images: reduction of false positives using anatomical location features

    NASA Astrophysics Data System (ADS)

    Uchiyama, Yoshikazu; Gao, Xin; Hara, Takeshi; Fujita, Hiroshi; Ando, Hiromichi; Yamakawa, Hiroyasu; Asano, Takahiko; Kato, Hiroki; Iwama, Toru; Kanematsu, Masayuki; Hoshi, Hiroaki

    2008-03-01

    The detection of unruptured aneurysms is a major subject in magnetic resonance angiography (MRA). However, their accurate detection is often difficult because of the overlapping between the aneurysm and the adjacent vessels on maximum intensity projection images. The purpose of this study is to develop a computerized method for the detection of unruptured aneurysms in order to assist radiologists in image interpretation. The vessel regions were first segmented using gray-level thresholding and a region growing technique. The gradient concentration (GC) filter was then employed for the enhancement of the aneurysms. The initial candidates were identified in the GC image using a gray-level threshold. For the elimination of false positives (FPs), we determined shape features and an anatomical location feature. Finally, rule-based schemes and quadratic discriminant analysis were employed along with these features for distinguishing between the aneurysms and the FPs. The sensitivity for the detection of unruptured aneurysms was 90.0% with 1.52 FPs per patient. Our computerized scheme can be useful in assisting the radiologists in the detection of unruptured aneurysms in MRA images.

  5. Combined Dynamic Contrast Enhanced Liver MRI and MRA Using Interleaved Variable Density Sampling

    PubMed Central

    Rahimi, Mahdi Salmani; Korosec, Frank R.; Wang, Kang; Holmes, James H.; Motosugi, Utaroh; Bannas, Peter; Reeder, Scott B.

    2014-01-01

    Purpose To develop and evaluate a method for volumetric contrast-enhanced MR imaging of the liver, with high spatial and temporal resolutions, for combined dynamic imaging and MR angiography using a single injection of contrast. Methods An interleaved variable density (IVD) undersampling pattern was implemented in combination with a real-time-triggered, time-resolved, dual-echo 3D spoiled gradient echo sequence. Parallel imaging autocalibration lines were acquired only once during the first time-frame. Imaging was performed in ten subjects with focal nodular hyperplasia (FNH) and compared with their clinical MRI. The angiographic phase of the proposed method was compared to a dedicated MR angiogram acquired during a second injection of contrast. Results A total of 21 FNH, 3 cavernous hemangiomas, and 109 arterial segments were visualized in 10 subjects. The temporally-resolved images depicted the characteristic arterial enhancement pattern of the lesions with a 4 s update rate. Images were graded as having significantly higher quality compared to the clinical MRI. Angiograms produced from the IVD method provided non-inferior diagnostic assessment compared to the dedicated MRA. Conclusion Using an undersampled IVD imaging method, we have demonstrated the feasibility of obtaining high spatial and temporal resolution dynamic contrast-enhanced imaging and simultaneous MRA of the liver. PMID:24639130

  6. Thoracic outlet syndrome in a throwing athlete diagnosed with MRI and MRA.

    PubMed

    Esposito, M D; Arrington, J A; Blackshear, M N; Murtagh, F R; Silbiger, M L

    1997-01-01

    Thoracic outlet syndrome comprises the clinical manifestations in the arm caused by compression of the neurovascular bundle as it leaves the thoracic inlet. The neurovascular bundle is composed of the subclavian artery, the subclavian vein, and the brachial plexus. The symptoms of thoracic outlet or inlet syndrome are most often caused by compression of the nerves of the brachial plexus, which is involved in up to 98% of cases; the remainder are due to vascular compression. MRI with MRA demonstrates well the anatomy of the brachial plexus as well as any vascular compression or occlusion. The relationship of the axillary and subclavian vein to the first rib and subclavius muscle also can be demonstrated. We present a college baseball player who presented with numbness in the fingers of his throwing hand when throwing a baseball. Evaluation with spin-echo and two-dimensional time-of-flight MR angiographic (MRA) imaging of the thoracic outlet region revealed obstruction of the subclavian vein with the arm abducted. To our knowledge, no such cases have been diagnosed previously with MRI.

  7. 3MRA: A MULTI-MEDIA HUMAN AND ECOLOGICAL MODELING SYSTEM FOR SITE-SPECIFIC TO NATIONAL SCALE REGULATORY APPLICATIONS

    EPA Science Inventory

    3MRA provides a technology that fully integrates the full dimensionality of human and ecological exposure and risk assessment, thus allowing regulatory decisions a more complete expression of potential adverse health effects related to the disposal and reuse of contaminated waste...

  8. [Identification of offending vessels in trigeminal neuralgia and hemifacial spasm using SPGR-MRI and 3D-TOF-MRA].

    PubMed

    Niwa, Y; Shiotani, M; Karasawa, H; Ohseto, K; Naganuma, Y

    1996-04-01

    We investigated 100 consecutive patients with trigeminal neuralgia (TN) and 53 patients with hemifacial spasm (HFS) concerning the anatomical relationship between the root entry (exit) zone (REZ) of cranial nerve and the offending artery, using spoiled GRASS MRI (SPGR-MRI) and three dimensional-time of fly-MRA (MRA). In 67 of 100 (67%) patiets with TN, this new radiological method, SPGR-MRI and MRA demonstrated the relationship between the fifth cranial nerve root and offending artery causing neurovascular compression (NVC), and in 46 of 53 (87%) with HFS, demonstrated the similar relationship between seventh and eighth nerve complex and offending artery. Microvascular decompression (MVD) was performed in 10 with HFS, and NVC of the REZ of the facial nerve caused by the offending artery was exactly predicted by SPGR-MRI and MRA in 9 (90%). The combination of SPGR-MRI and MRA is very useful for demonstrating NVC as the cause of TN and HFS. On the other hand, we investigated asymptomatic 206 trigeminal and 253 facial nerves about the relationship between their REZ and the surrounding structures using the similar method. The contact of REZ of cranial nerve with surrounding artery is demonstrated in 31.6% of trigeminal nerves and in 22.5% of facial nerves. These results indicate that the contact of REZ of cranial nerve with surrounding artery is not rare in healthy subjects, though causing TN and HFS in particular patients. In this context, we discussed the difference between the contact which is asymptomatic and the compression which is symptomatic.

  9. Sparse-CAPR: Highly-Accelerated 4D CE-MRA with Parallel Imaging and Nonconvex Compressive Sensing

    PubMed Central

    Trzasko, Joshua D.; Haider, Clifton R.; Borisch, Eric A.; Campeau, Norbert G.; Glockner, James F.; Riederer, Stephen J.; Manduca, Armando

    2012-01-01

    CAPR is a SENSE-type parallel 3DFT acquisition paradigm for 4D contrast-enhanced magnetic resonance angiography (CE-MRA) that has been demonstrated capable of providing high spatial and temporal resolution, diagnostic-quality images at very high acceleration rates. However, CAPR images are typically reconstructed online using Tikhonov regularization and partial Fourier methods, which are prone to exhibit noise amplification and undersampling artifacts when operating at very high acceleration rates. In this work, a sparsity-driven offline reconstruction framework for CAPR is developed and demonstrated to consistently provide improvements over the currently-employed reconstruction strategy against these ill-effects. Moreover, the proposed reconstruction strategy requires no changes to the existing CAPR acquisition protocol, and an efficient numerical optimization and hardware system are described that allow for a 256×160×80 volume CE-MRA volume to be reconstructed from an 8-channel data set in less than two minutes. PMID:21608028

  10. A primitive study of voxel feature generation by multiple stacked denoising autoencoders for detecting cerebral aneurysms on MRA

    NASA Astrophysics Data System (ADS)

    Nemoto, Mitsutaka; Hayashi, Naoto; Hanaoka, Shouhei; Nomura, Yukihiro; Miki, Soichiro; Yoshikawa, Takeharu; Ohtomo, Kuni

    2016-03-01

    The purpose of this study is to evaluate the feasibility of a novel feature generation, which is based on multiple deep neural networks (DNNs) with boosting, for computer-assisted detection (CADe). It is hard and time-consuming to optimize the hyperparameters for DNNs such as stacked denoising autoencoder (SdA). The proposed method allows using SdA based features without the burden of the hyperparameter setting. The proposed method was evaluated by an application for detecting cerebral aneurysms on magnetic resonance angiogram (MRA). A baseline CADe process included four components; scaling, candidate area limitation, candidate detection, and candidate classification. Proposed feature generation method was applied to extract the optimal features for candidate classification. Proposed method only required setting range of the hyperparameters for SdA. The optimal feature set was selected from a large quantity of SdA based features by multiple SdAs, each of which was trained using different hyperparameter set. The feature selection was operated through ada-boost ensemble learning method. Training of the baseline CADe process and proposed feature generation were operated with 200 MRA cases, and the evaluation was performed with 100 MRA cases. Proposed method successfully provided SdA based features just setting the range of some hyperparameters for SdA. The CADe process by using both previous voxel features and SdA based features had the best performance with 0.838 of an area under ROC curve and 0.312 of ANODE score. The results showed that proposed method was effective in the application for detecting cerebral aneurysms on MRA.

  11. In-vivo study of the thermoregulation of the rat tail using magnetic resonance angiography (MRA)

    NASA Astrophysics Data System (ADS)

    Vanhoutte, Greet; Verhoye, Marleen; Raman, Erik R.; Van der Linden, Anne-Marie

    2000-04-01

    In the rat, almost 20% of the total body heat-loss occurs by sympathetically mediated increases in blood flow through a system of arteriovenous anastomoses (AVAs) in the skin of the tail which are absent at the base and abundant at the tip. To study the mechanisms of thermoregulation in the rat tail we monitored online the blood vessel temperature and the arterial and venous vessel size and their mutual vascular volume interactions using in vivo MRA. During a gradual rise in rectal temperature from 36 degrees Celsius to 40 degrees Celsius, tail surface temperatures were measured at ventral (Ta) and lateral (Tv) sits overlying the respective vascular bundles. At the base, middle and tip, diameter of the ventral artery and the lateral veins of the heat-loaded animal increased clearly upon rising body temperature. Calculation of (Ta - Tv) in function of the rectal temperature during heating showed that at the tail base (Ta - Tv) was maximum at rectal temperature of 38 degrees Celsius and minimum at 39 degrees Celsius. At the middle and the tip of the tail, a steady rise of (Ta - Tv) was observed. If we assume that vasodilatation is a synchronical process along the length of the tail, then the difference in (Ta - Tv) is due to the presence of AVAs.

  12. 3DVIEWNIX-AVS: a software package for the separate visualization of arteries and veins in CE-MRA images.

    PubMed

    Lei, Tianhu; Udupa, Jayaram K; Odhner, Dewey; Nyúl, László G; Saha, Punam K

    2003-01-01

    Our earlier study developed a computerized method, based on fuzzy connected object delineation principles and algorithms, for artery and vein separation in contrast enhanced Magnetic Resonance Angiography (CE-MRA) images. This paper reports its current development-a software package-for routine clinical use. The software package, termed 3DVIEWNIX-AVS, consists of the following major operational parts: (1) converting data from DICOM3 to 3DVIEWNIX format, (2) previewing slices and creating VOI and MIP Shell, (3) segmenting vessel, (4) separating artery and vein, (5) shell rendering vascular structures and creating animations. This package has been applied to EPIX Medical Inc's CE-MRA data (AngioMark MS-325). One hundred and thirty-five original CE-MRA data sets (of 52 patients) from 6 hospitals have been processed. In all case studies, unified parameter settings produce correct artery-vein separation. The current package is running on a Pentium PC under Linux and the total computation time per study is about 3 min. The strengths of this software package are (1) minimal user interaction, (2) minimal anatomic knowledge requirements on human vascular system, (3) clinically required speed, (4) free entry to any operational stages, (5) reproducible, reliable, high quality of results, and (6) cost effective computer implementation. To date, it seems to be the only software package (using an image processing approach) available for artery and vein separation of the human vascular system for routine use in a clinical setting. PMID:12821028

  13. Performance evaluation of an automatic segmentation method of cerebral arteries in MRA images by use of a large image database

    NASA Astrophysics Data System (ADS)

    Uchiyama, Yoshikazu; Asano, Tatsunori; Hara, Takeshi; Fujita, Hiroshi; Kinosada, Yasutomi; Asano, Takahiko; Kato, Hiroki; Kanematsu, Masayuki; Hoshi, Hiroaki; Iwama, Toru

    2009-02-01

    The detection of cerebrovascular diseases such as unruptured aneurysm, stenosis, and occlusion is a major application of magnetic resonance angiography (MRA). However, their accurate detection is often difficult for radiologists. Therefore, several computer-aided diagnosis (CAD) schemes have been developed in order to assist radiologists with image interpretation. The purpose of this study was to develop a computerized method for segmenting cerebral arteries, which is an essential component of CAD schemes. For the segmentation of vessel regions, we first used a gray level transformation to calibrate voxel values. To adjust for variations in the positioning of patients, registration was subsequently employed to maximize the overlapping of the vessel regions in the target image and reference image. The vessel regions were then segmented from the background using gray-level thresholding and region growing techniques. Finally, rule-based schemes with features such as size, shape, and anatomical location were employed to distinguish between vessel regions and false positives. Our method was applied to 854 clinical cases obtained from two different hospitals. The segmentation of cerebral arteries in 97.1%(829/854) of the MRA studies was attained as an acceptable result. Therefore, our computerized method would be useful in CAD schemes for the detection of cerebrovascular diseases in MRA images.

  14. The role of time-resolved imaging of contrast kinetics (TRICKS) magnetic resonance angiography (MRA) in the evaluation of head–neck vascular anomalies: a preliminary experience

    PubMed Central

    Tavanti, F; Rossi Espagnet, M C; Terenzi, V; Cassoni, A; Suma, G; Boellis, A; Pierallini, A; Valentini, V; Bozzao, A

    2015-01-01

    Objectives: In this preliminary report, we describe our experience with time-resolved imaging of contrast kinetics–MR angiography (TRICKS-MRA) in the assessment of head–neck vascular anomalies (HNVAs). Methods: We prospectively studied six consecutive patients with clinically suspected or diagnosed HNVAs. All of them underwent TRICKS-MRA of the head and neck as part of the routine for treatment planning. A digital subtraction angiography (DSA) was also performed. Results: TRICKS-MRA could be achieved in all cases. Three subjects were treated based on TRICKS-MRA imaging findings and subsequent DSA examination. In all of them, DSA confirmed the vascular architecture of HNVAs shown by TRICKS-MRA. In the other three patients, a close follow up to assess the evolution of the suspected haemangioma was preferred. Conclusions: TRICKS sequences add important diagnostic information in cases of HNVAs, helpful for therapeutic decisions and post-treatment follow up. We recommend TRICKS-MRA use (if technically possible) as part of routine MRI protocol for HNVAs, representing a possible alternative imaging tool to conventional DSA. PMID:25410709

  15. Cervical Vascular and Upper Airway Asymmetry in Velo-Cardio-Facial Syndrome: Correlation of Nasopharyngoscopy with MRA

    PubMed Central

    Oppenheimer, Avi G.; Fulmer, Susan; Shifteh, Keivan; Chang, Ja-Kwei; Brook, Allan; Shanske, Alan L.; Shprintzen, Robert J.

    2010-01-01

    Purpose Velo-cardio-facial syndrome (VCFS), the most common genetic syndrome causing cleft palate, is associated with internal carotid and vertebral artery anomalies, as well as upper airway asymmetry. Medially displaced internal carotid arteries, often immediately submucosal, present a risk of vascular injury during pharyngeal flap surgery for velopharyngeal insufficiency (VPI). We evaluate the frequency and spectrum of cervical vascular anomalies in a large cohort of VCFS patients correlating MRA with nasopharyngolaryngoscopy in detecting at-risk carotid arteries. Furthermore, we assess the relationship with respect to laterality between cervical vascular patterns and the asymmetric abnormalities of these subjects' upper airways. Methods Cervical MRAs of 86 subjects with VCFS and 50 control subjects were independently reviewed by three neuroradiologists. The course of the internal carotid and vertebral arteries were identified within the pharyngeal soft tissues. Medial deviation, level of bifurcation, dominance, anomalous origin, and vessel tortuosity were recorded. Nasopharyngoscopy examinations were available for retrospective review in 43 patients and were assessed for palatal and posterior pharyngeal wall symmetry, true vocal cord motion and size, and for the presence or absence of carotid pulsations. The endoscopic findings were compared with MRA results. Results Of the 86 subjects, 80 (93%) had one or more vascular anomalies. 42 subjects (49%) were found to have medial deviation of at least one internal carotid artery. In 24 subjects (28%) the anomalous internal carotid artery were directly submucosal; four of these were bilateral (5% of the total sample, 17% of those with a submucosal internal carotid). Other carotid anomalies included low carotid bifurcation (44 subjects or 51%), anomalous origin of the right common carotid (32 cases, or 37%), and two cases of internal carotid agenesis/hypoplasia. Vertebral artery anomalies included vessel tortuosity (34

  16. Lipid Requirements for the Enzymatic Activity of MraY Translocases and in Vitro Reconstitution of the Lipid II Synthesis Pathway.

    PubMed

    Henrich, Erik; Ma, Yi; Engels, Ina; Münch, Daniela; Otten, Christian; Schneider, Tanja; Henrichfreise, Beate; Sahl, Hans-Georg; Dötsch, Volker; Bernhard, Frank

    2016-01-29

    Screening of new compounds directed against key protein targets must continually keep pace with emerging antibiotic resistances. Although periplasmic enzymes of bacterial cell wall biosynthesis have been among the first drug targets, compounds directed against the membrane-integrated catalysts are hardly available. A promising future target is the integral membrane protein MraY catalyzing the first membrane associated step within the cytoplasmic pathway of bacterial peptidoglycan biosynthesis. However, the expression of most MraY homologues in cellular expression systems is challenging and limits biochemical analysis. We report the efficient production of MraY homologues from various human pathogens by synthetic cell-free expression approaches and their subsequent characterization. MraY homologues originating from Bordetella pertussis, Helicobacter pylori, Chlamydia pneumoniae, Borrelia burgdorferi, and Escherichia coli as well as Bacillus subtilis were co-translationally solubilized using either detergent micelles or preformed nanodiscs assembled with defined membranes. All MraY enzymes originating from Gram-negative bacteria were sensitive to detergents and required nanodiscs containing negatively charged lipids for obtaining a stable and functionally folded conformation. In contrast, the Gram-positive B. subtilis MraY not only tolerates detergent but is also less specific for its lipid environment. The MraY·nanodisc complexes were able to reconstitute a complete in vitro lipid I and lipid II forming pipeline in combination with the cell-free expressed soluble enzymes MurA-F and with the membrane-associated protein MurG. As a proof of principle for future screening platforms, we demonstrate the inhibition of the in vitro lipid II biosynthesis with the specific inhibitors fosfomycin, feglymycin, and tunicamycin.

  17. Lipid Requirements for the Enzymatic Activity of MraY Translocases and in Vitro Reconstitution of the Lipid II Synthesis Pathway.

    PubMed

    Henrich, Erik; Ma, Yi; Engels, Ina; Münch, Daniela; Otten, Christian; Schneider, Tanja; Henrichfreise, Beate; Sahl, Hans-Georg; Dötsch, Volker; Bernhard, Frank

    2016-01-29

    Screening of new compounds directed against key protein targets must continually keep pace with emerging antibiotic resistances. Although periplasmic enzymes of bacterial cell wall biosynthesis have been among the first drug targets, compounds directed against the membrane-integrated catalysts are hardly available. A promising future target is the integral membrane protein MraY catalyzing the first membrane associated step within the cytoplasmic pathway of bacterial peptidoglycan biosynthesis. However, the expression of most MraY homologues in cellular expression systems is challenging and limits biochemical analysis. We report the efficient production of MraY homologues from various human pathogens by synthetic cell-free expression approaches and their subsequent characterization. MraY homologues originating from Bordetella pertussis, Helicobacter pylori, Chlamydia pneumoniae, Borrelia burgdorferi, and Escherichia coli as well as Bacillus subtilis were co-translationally solubilized using either detergent micelles or preformed nanodiscs assembled with defined membranes. All MraY enzymes originating from Gram-negative bacteria were sensitive to detergents and required nanodiscs containing negatively charged lipids for obtaining a stable and functionally folded conformation. In contrast, the Gram-positive B. subtilis MraY not only tolerates detergent but is also less specific for its lipid environment. The MraY·nanodisc complexes were able to reconstitute a complete in vitro lipid I and lipid II forming pipeline in combination with the cell-free expressed soluble enzymes MurA-F and with the membrane-associated protein MurG. As a proof of principle for future screening platforms, we demonstrate the inhibition of the in vitro lipid II biosynthesis with the specific inhibitors fosfomycin, feglymycin, and tunicamycin. PMID:26620564

  18. Automatic 3D Segmentation and Quantification of Lenticulostriate Arteries from High-Resolution 7 Tesla MRA Images.

    PubMed

    Wei Liao; Rohr, Karl; Chang-Ki Kang; Zang-Hee Cho; Worz, Stefan

    2016-01-01

    We propose a novel hybrid approach for automatic 3D segmentation and quantification of high-resolution 7 Tesla magnetic resonance angiography (MRA) images of the human cerebral vasculature. Our approach consists of two main steps. First, a 3D model-based approach is used to segment and quantify thick vessels and most parts of thin vessels. Second, remaining vessel gaps of the first step in low-contrast and noisy regions are completed using a 3D minimal path approach, which exploits directional information. We present two novel minimal path approaches. The first is an explicit approach based on energy minimization using probabilistic sampling, and the second is an implicit approach based on fast marching with anisotropic directional prior. We conducted an extensive evaluation with over 2300 3D synthetic images and 40 real 3D 7 Tesla MRA images. Quantitative and qualitative evaluation shows that our approach achieves superior results compared with a previous minimal path approach. Furthermore, our approach was successfully used in two clinical studies on stroke and vascular dementia.

  19. Automatic 3D Segmentation and Quantification of Lenticulostriate Arteries from High-Resolution 7 Tesla MRA Images.

    PubMed

    Wei Liao; Rohr, Karl; Chang-Ki Kang; Zang-Hee Cho; Worz, Stefan

    2016-01-01

    We propose a novel hybrid approach for automatic 3D segmentation and quantification of high-resolution 7 Tesla magnetic resonance angiography (MRA) images of the human cerebral vasculature. Our approach consists of two main steps. First, a 3D model-based approach is used to segment and quantify thick vessels and most parts of thin vessels. Second, remaining vessel gaps of the first step in low-contrast and noisy regions are completed using a 3D minimal path approach, which exploits directional information. We present two novel minimal path approaches. The first is an explicit approach based on energy minimization using probabilistic sampling, and the second is an implicit approach based on fast marching with anisotropic directional prior. We conducted an extensive evaluation with over 2300 3D synthetic images and 40 real 3D 7 Tesla MRA images. Quantitative and qualitative evaluation shows that our approach achieves superior results compared with a previous minimal path approach. Furthermore, our approach was successfully used in two clinical studies on stroke and vascular dementia. PMID:26571526

  20. Accelerated Whole-Heart Coronary MRA Using Motion-Corrected Sensitivity Encoding with Three-Dimensional Projection Reconstruction

    PubMed Central

    Pang, Jianing; Sharif, Behzad; Arsanjani, Reza; Bi, Xiaoming; Fan, Zhaoyang; Yang, Qi; Li, Kuncheng; Berman, Daniel S.; Li, Debiao

    2014-01-01

    Purpose To achieve whole-heart coronary magnetic resonance angiography (MRA) with (1.0 mm)3 spatial resolution and 5 min of free-breathing scan time. Methods We used an electrocardiograph-gated, T2-prepared and fat-saturated balanced steady state free precession sequence with 3DPR trajectory for free-breathing data acquisition with 100% gating efficiency. For image reconstruction, we used a self-calibrating iterative SENSE scheme with integrated retrospective motion correction. We performed healthy volunteer study to compare the proposed method with motion-corrected gridding at different retrospective undersampling levels on apparent signal-to-noise ratio (aSNR) and subjective coronary artery (CA) visualization scores. Results Compared with gridding, the proposed method significantly improved both image quality metrics for undersampled datasets with 6000, 8000, and 10,000 projections. With as few as 10,000 projections, the proposed method yielded good CA visualization scores (3.02 of 4) and aSNR values comparable to those with 20,000 projections. Conclusion Using the proposed method, good image quality was observed for free breathing whole-heart coronary MRA at (1.0 mm)3 resolution with an achievable scan time of 5 min. PMID:24435956

  1. Catalytic mechanism of MraY and WecA, two paralogues of the polyprenyl-phosphate N-acetylhexosamine 1-phosphate transferase superfamily.

    PubMed

    Al-Dabbagh, Bayan; Olatunji, Samir; Crouvoisier, Muriel; El Ghachi, Meriem; Blanot, Didier; Mengin-Lecreulx, Dominique; Bouhss, Ahmed

    2016-08-01

    The MraY transferase catalyzes the first membrane step of bacterial cell wall peptidoglycan biosynthesis, namely the transfer of the N-acetylmuramoyl-pentapeptide moiety of the cytoplasmic precursor UDP-MurNAc-pentapeptide to the membrane transporter undecaprenyl phosphate (C55P), yielding C55-PP-MurNAc-pentapeptide (lipid I). A paralogue of MraY, WecA, catalyzes the transfer of the phospho-GlcNAc moiety of UDP-N-acetylglucosamine onto the same lipid carrier, leading to the formation of C55-PP-GlcNAc that is essential for the synthesis of various bacterial cell envelope components. These two enzymes are members of the polyprenyl-phosphate N-acetylhexosamine 1-phosphate transferase superfamily, which are essential for bacterial envelope biogenesis. Despite the availability of detailed biochemical information on the MraY enzyme, and the recently published crystal structure of MraY of Aquifex aeolicus, the molecular basis for its catalysis remains poorly understood. This knowledge can contribute to the design of potential inhibitors. Here, we report a detailed catalytic study of the Bacillus subtilis MraY and Thermotoga maritima WecA transferases. Both forward and reverse exchange reactions required the presence of the second substrate, C55P and uridine monophosphate (UMP), respectively. Both enzymes did not display any pyrophosphatase activity on the nucleotide substrate. Moreover, we showed that the nucleotide substrate UDP-MurNAc-pentapeptide, as well as the nucleotide product UMP, can bind to MraY in the absence of lipid ligands. Therefore, our data are in favour of a single displacement mechanism. During this "one-step" mechanism, the oxyanion of the polyprenyl-phosphate attacks the β-phosphate of the nucleotide substrate, leading to the formation of lipid product and the liberation of UMP. The involvement of an invariant aspartyl residue in the deprotonation of the lipid substrate is discussed.

  2. MEETING IN TUCSON: 3MRA: A MULTI-MEDIA HUMAN AND ECOLOGICAL MODELING SYSTEM FOR SITE-SPECIFIC TO NATIONAL SCALE REGULATORY APPLICATIONS

    EPA Science Inventory

    3MRA provides a technology that fully integrates the full dimensionality of human and ecological exposure and risk assessment, thus allowing regulatory decisions a more complete expression of potential adverse health effects related to the disposal and reuse of contaminated waste...

  3. A COMPARATIVE RISK REDUCTION ANALYSIS OF THE OFFICE OF SOLID WASTE'S WASTE MINIMIZATION PRIORITY CHEMICALS INITIATIVE USING THE 3MRA MULTIMEDIA MODELING SYSTEM

    EPA Science Inventory

    A study was initiated by the EPA/ORD National Exposure Research Lab (NERL) in FY05 to quantify risk reduction resulting from this national EPA initiative to reduce WMPC disposal. Using the 3MRA modeling system, which was recommended for use by the EPA Science Advisory Board for ...

  4. ECG and Navigator-Free 4D Whole-Heart Coronary MRA for Simultaneous Visualization of Cardiac Anatomy and Function

    PubMed Central

    Pang, Jianing; Sharif, Behzad; Fan, Zhaoyang; Bi, Xiaoming; Arsanjani, Reza; Berman, Daniel S.; Li, Debiao

    2014-01-01

    Purpose To develop a cardiac and respiratory self-gated 4D coronary MRA technique for simultaneous cardiac anatomy and function visualization. Methods A contrast-enhanced, ungated spoiled gradient echo sequence with self-gating (SG) and 3DPR trajectory was used for image acquisition. Data was retrospectively binned into different cardiac and respiratory phases based on information extracted from SG projections using principal component analysis. Each cardiac phase was reconstructed using a respiratory motion-corrected self-calibrating SENSE framework, and those belong to the quiescent period were retrospectively combined for coronary visualization. Healthy volunteer studies were conducted to evaluate the efficacy of the SG method, the accuracy of the left ventricle (LV) function parameters and the quality of coronary artery visualization. Results SG performed reliably for all subjects including one with poor ECG. The LV function parameters showed excellent agreement with those from a conventional cine protocol. For coronary imaging, the proposed method yielded comparable apparent SNR and coronary sharpness and lower apparent CNR on three subjects compared with an ECG and navigator-gated Cartesian protocol and an ECG-gated, respiratory motion-corrected 3DPR protocol. Conclusion A fully self-gated 4D whole-heart imaging technique was developed, potentially allowing cardiac anatomy and function assessment from a single measurement. PMID:25216287

  5. MRA_1571 is required for isoleucine biosynthesis and improves Mycobacterium tuberculosis H37Ra survival under stress

    PubMed Central

    Sharma, Rishabh; Keshari, Deepa; Singh, Kumar Sachin; Yadav, Shailendra; Singh, Sudheer Kumar

    2016-01-01

    Threonine dehydratase is a pyridoxal 5-phosphate dependent enzyme required for isoleucine biosynthesis. Threonine dehydratase (IlvA) participates in conversion of threonine to 2-oxobutanoate and ammonia is released as a by-product. MRA_1571 is annotated to be coding for IlvA in Mycobacterium tuberculosis H37Ra (Mtb-Ra). We developed a recombinant (KD) Mtb-Ra strain by down-regulating IlvA. The growth studies on different carbon sources suggested reduced growth of KD compared to wild-type (WT), also, isoleucine concentration dependent KD growth restoration was observed. The expression profiling of IlvA suggested increased expression of IlvA during oxygen, acid and oxidative stress. In addition, KD showed reduced survival under pH, starvation, nitric oxide and peroxide stresses. KD was more susceptible to antimycobacterial agents such as streptomycin (STR), rifampicin (RIF) and levofloxacin (LVF), while, no such effect was noticeable when exposed to isoniazid. Also, an increase in expression of IlvA was observed when exposed to STR, RIF and LVF. The dye accumulation studies suggested increased permeability of KD to ethidium bromide and Nile Red as compared to WT. TLC and Mass studies confirmed altered lipid profile of KD. In summary down-regulation of IlvA affects Mtb growth, increases its susceptibility to stress and leads to altered cell wall lipid profile. PMID:27353854

  6. Mapping of arterial location for the design of automated identification and analysis algorithms in whole body MRA.

    PubMed

    McCormick, Lynne; Weir-McCall, Jonathan; Gandy, Stephen; White, Richard; McNeil, Andrew; Trucco, Emanuele; Houston, J Graeme

    2015-01-01

    Technological and medical advances have led to the realisation of full body imaging, with systemic diagnostic approaches becoming increasingly more prevalent. In the imaging of atherosclerotic disease, contrast -enhanced whole-body MRA has been demonstrated to enable detection of stenosis with a high sensitivity and specificity. Characterization of the systemic cardiovascular disease burden has significant prognostic value. A whole-body acquisition does however generate a large volume of three-dimensional data and as such there are expected to be significant advantages in developing automated techniques for the analysis of these images. Improved radiological workflow, reduced analysis time and increased analytical standardization are expected to be among the benefits offered by this approach. As part of a process of automated software development this study aimed to collect and validate arterial location ground truth. The data will be used to inform the development of semi-automated vascular identity tools, and allow the potential for the further development of semi-automated anatomically informed cardiovascular disease analysis and reporting. PMID:26738130

  7. MRA_1571 is required for isoleucine biosynthesis and improves Mycobacterium tuberculosis H37Ra survival under stress.

    PubMed

    Sharma, Rishabh; Keshari, Deepa; Singh, Kumar Sachin; Yadav, Shailendra; Singh, Sudheer Kumar

    2016-01-01

    Threonine dehydratase is a pyridoxal 5-phosphate dependent enzyme required for isoleucine biosynthesis. Threonine dehydratase (IlvA) participates in conversion of threonine to 2-oxobutanoate and ammonia is released as a by-product. MRA_1571 is annotated to be coding for IlvA in Mycobacterium tuberculosis H37Ra (Mtb-Ra). We developed a recombinant (KD) Mtb-Ra strain by down-regulating IlvA. The growth studies on different carbon sources suggested reduced growth of KD compared to wild-type (WT), also, isoleucine concentration dependent KD growth restoration was observed. The expression profiling of IlvA suggested increased expression of IlvA during oxygen, acid and oxidative stress. In addition, KD showed reduced survival under pH, starvation, nitric oxide and peroxide stresses. KD was more susceptible to antimycobacterial agents such as streptomycin (STR), rifampicin (RIF) and levofloxacin (LVF), while, no such effect was noticeable when exposed to isoniazid. Also, an increase in expression of IlvA was observed when exposed to STR, RIF and LVF. The dye accumulation studies suggested increased permeability of KD to ethidium bromide and Nile Red as compared to WT. TLC and Mass studies confirmed altered lipid profile of KD. In summary down-regulation of IlvA affects Mtb growth, increases its susceptibility to stress and leads to altered cell wall lipid profile.

  8. Mapping of arterial location for the design of automated identification and analysis algorithms in whole body MRA.

    PubMed

    McCormick, Lynne; Weir-McCall, Jonathan; Gandy, Stephen; White, Richard; McNeil, Andrew; Trucco, Emanuele; Houston, J Graeme

    2015-01-01

    Technological and medical advances have led to the realisation of full body imaging, with systemic diagnostic approaches becoming increasingly more prevalent. In the imaging of atherosclerotic disease, contrast -enhanced whole-body MRA has been demonstrated to enable detection of stenosis with a high sensitivity and specificity. Characterization of the systemic cardiovascular disease burden has significant prognostic value. A whole-body acquisition does however generate a large volume of three-dimensional data and as such there are expected to be significant advantages in developing automated techniques for the analysis of these images. Improved radiological workflow, reduced analysis time and increased analytical standardization are expected to be among the benefits offered by this approach. As part of a process of automated software development this study aimed to collect and validate arterial location ground truth. The data will be used to inform the development of semi-automated vascular identity tools, and allow the potential for the further development of semi-automated anatomically informed cardiovascular disease analysis and reporting.

  9. The Relative Importance of the Vadose Zone in Multimedia Risk Assessment Modeling Applied at a National Scale: An Analysis of Benzene Using 3MRA

    NASA Astrophysics Data System (ADS)

    Babendreier, J. E.

    2002-05-01

    Evaluating uncertainty and parameter sensitivity in environmental models can be a difficult task, even for low-order, single-media constructs driven by a unique set of site-specific data. The challenge of examining ever more complex, integrated, higher-order models is a formidable one, particularly in regulatory settings applied on a national scale. Quantitative assessment of uncertainty and sensitivity within integrated, multimedia models that simulate hundreds of sites, spanning multiple geographical and ecological regions, will ultimately require a systematic, comparative approach coupled with sufficient computational power. The Multimedia, Multipathway, and Multireceptor Risk Assessment Model (3MRA) is an important code being developed by the United States Environmental Protection Agency for use in site-scale risk assessment (e.g. hazardous waste management facilities). The model currently entails over 700 variables, 185 of which are explicitly stochastic. The 3MRA can start with a chemical concentration in a waste management unit (WMU). It estimates the release and transport of the chemical throughout the environment, and predicts associated exposure and risk. The 3MRA simulates multimedia (air, water, soil, sediments), pollutant fate and transport, multipathway exposure routes (food ingestion, water ingestion, soil ingestion, air inhalation, etc.), multireceptor exposures (resident, gardener, farmer, fisher, ecological habitats and populations), and resulting risk (human cancer and non-cancer effects, ecological population and community effects). The 3MRA collates the output for an overall national risk assessment, offering a probabilistic strategy as a basis for regulatory decisions. To facilitate model execution of 3MRA for purposes of conducting uncertainty and sensitivity analysis, a PC-based supercomputer cluster was constructed. Design of SuperMUSE, a 125 GHz Windows-based Supercomputer for Model Uncertainty and Sensitivity Evaluation is described

  10. Automated segmentation of cerebral vasculature with aneurysms in 3DRA and TOF-MRA using geodesic active regions: An evaluation study

    SciTech Connect

    Bogunovic, Hrvoje; Pozo, Jose Maria; Villa-Uriol, Maria Cruz; and others

    2011-01-15

    Purpose: To evaluate the suitability of an improved version of an automatic segmentation method based on geodesic active regions (GAR) for segmenting cerebral vasculature with aneurysms from 3D x-ray reconstruction angiography (3DRA) and time of flight magnetic resonance angiography (TOF-MRA) images available in the clinical routine. Methods: Three aspects of the GAR method have been improved: execution time, robustness to variability in imaging protocols, and robustness to variability in image spatial resolutions. The improved GAR was retrospectively evaluated on images from patients containing intracranial aneurysms in the area of the Circle of Willis and imaged with two modalities: 3DRA and TOF-MRA. Images were obtained from two clinical centers, each using different imaging equipment. Evaluation included qualitative and quantitative analyses of the segmentation results on 20 images from 10 patients. The gold standard was built from 660 cross-sections (33 per image) of vessels and aneurysms, manually measured by interventional neuroradiologists. GAR has also been compared to an interactive segmentation method: isointensity surface extraction (ISE). In addition, since patients had been imaged with the two modalities, we performed an intermodality agreement analysis with respect to both the manual measurements and each of the two segmentation methods. Results: Both GAR and ISE differed from the gold standard within acceptable limits compared to the imaging resolution. GAR (ISE) had an average accuracy of 0.20 (0.24) mm for 3DRA and 0.27 (0.30) mm for TOF-MRA, and had a repeatability of 0.05 (0.20) mm. Compared to ISE, GAR had a lower qualitative error in the vessel region and a lower quantitative error in the aneurysm region. The repeatability of GAR was superior to manual measurements and ISE. The intermodality agreement was similar between GAR and the manual measurements. Conclusions: The improved GAR method outperformed ISE qualitatively as well as

  11. MR Angiography (MRA)

    MedlinePlus

    ... can be performed with one of three imaging technologies and, in some cases contrast material is administered. ... identify a small aneurysm or arteriovenous malformation (abnormal communications between blood vessels) inside the brain or other ...

  12. Total-body contrast-enhanced MRA on a short, wide-bore 1.5-T system: intra-individual comparison of Gd-BOPTA and Gd-DOTA.

    PubMed

    Rasmus, M; Bremerich, J; Egelhof, T; Huegli, R W; Bongartz, G; Bilecen, D

    2008-10-01

    Total-body contrast-enhanced MRA (CE-MRA) provides information of the entire vascular system according to a one-stop-shop approach. Short, wide-bore scanners have not yet been used for total-body CE-MRA, probably due to their restricted field of view in the z-direction. The purpose of this feasibility study is to introduce an image protocol for total-body MRA on a short, wide-bore system. The protocol includes five to six table-moving steps and two injection runs. Two pharmacologically different contrast materials (CM) were applied in ten healthy volunteers in view of possible CM-dependent influences on the protocol outcome (Gd-Bopta, Gd-Dota). Differences consisted of significantly higher CNR with Gd-Bopta with a mean of 73.8+/-38.7 versus 69.1+/-34.3 (p=0.008), significantly better arterial visualization values with Gd-Dota with a mean of 1.26+/-0.44 versus 1.53+/-0.73 (p=0.003) and a tendency to less venous overlay with Gd-Dota, mean 1.19+/-0.44 and 1.34+/-0.72, respectively (p=0.065) (two-tailed Wilcoxon matched-pairs test). Overall 94% of the steps were valued as qualitatively excellent or good. The good results with both CM suggest a transfer to further patient evaluation.

  13. A Cylindrical, Inner Volume Selecting 2D-T2-Prep Improves GRAPPA-Accelerated Image Quality in MRA of the Right Coronary Artery

    PubMed Central

    Coristine, Andrew J.; Yerly, Jerome; Stuber, Matthias

    2016-01-01

    Background Two-dimensional (2D) spatially selective radiofrequency (RF) pulses may be used to excite restricted volumes. By incorporating a "pencil beam" 2D pulse into a T2-Prep, one may create a "2D-T2-Prep" that combines T2-weighting with an intrinsic outer volume suppression. This may particularly benefit parallel imaging techniques, where artefacts typically originate from residual foldover signal. By suppressing foldover signal with a 2D-T2-Prep, image quality may therefore improve. We present numerical simulations, phantom and in vivo validations to address this hypothesis. Methods A 2D-T2-Prep and a conventional T2-Prep were used with GRAPPA-accelerated MRI (R = 1.6). The techniques were first compared in numerical phantoms, where per pixel maps of SNR (SNRmulti), noise, and g-factor were predicted for idealized sequences. Physical phantoms, with compartments doped to mimic blood, myocardium, fat, and coronary vasculature, were scanned with both T2-Preparation techniques to determine the actual SNRmulti and vessel sharpness. For in vivo experiments, the right coronary artery (RCA) was imaged in 10 healthy adults, using accelerations of R = 1,3, and 6, and vessel sharpness was measured for each. Results In both simulations and phantom experiments, the 2D-T2-Prep improved SNR relative to the conventional T2-Prep, by an amount that depended on both the acceleration factor and the degree of outer volume suppression. For in vivo images of the RCA, vessel sharpness improved most at higher acceleration factors, demonstrating that the 2D-T2-Prep especially benefits accelerated coronary MRA. Conclusion Suppressing outer volume signal with a 2D-T2-Prep improves image quality particularly well in GRAPPA-accelerated acquisitions in simulations, phantoms, and volunteers, demonstrating that it should be considered when performing accelerated coronary MRA. PMID:27736866

  14. Analysis of MreB interactors in Chlamydia reveals a RodZ homolog but fails to detect an interaction with MraY

    PubMed Central

    Ouellette, Scot P.; Rueden, Kelsey J.; Gauliard, Emilie; Persons, Logan; de Boer, Piet A.; Ladant, Daniel

    2014-01-01

    Chlamydia is an obligate intracellular bacterial pathogen that has significantly reduced its genome in adapting to the intracellular environment. One class of genes for which the bacterium has few annotated examples is cell division, and Chlamydia lacks FtsZ, a central coordinator of the division apparatus. We have previously implicated MreB as a potential substitute for FtsZ in Chlamydia (Ouellette et al., 2012). Thus, to identify new chlamydial cell division components, we searched for proteins that interacted with MreB. We performed a small-scale screen using a Gateway® compatible version of the Bacterial Adenylate Cyclase Two Hybrid (BACTH) system, BACTHGW, to detect proteins interacting with chlamydial MreB and identified a RodZ (YfgA) homolog. The chlamydial RodZ aligns well with the cytoplasmic domain of E. coli RodZ but lacks the periplasmic domain that is dispensable for rod cell shape maintenance in E. coli. The expression pattern of yfgA/rodZ was similar to that of mreB and ftsI, suggesting that these genes may operate in a common functional pathway. The chlamydial RodZ correctly localized to the membrane of E. coli but was unable to complement an E. coli rodZ mutant strain, likely because of the inability of chlamydial RodZ to interact with the native E. coli MreB. Finally, we also tested whether chlamydial MreB could interact with MraY, as suggested by Gaballah et al. (2011). However, we did not detect an interaction between these proteins even when using an implementation of the BACTH system to allow native orientation of the N- and C-termini of MraY in the periplasm. Thus, further work will be needed to establish this proposed interaction. In sum, we have added to the repertoire of potential cell division proteins of Chlamydia. PMID:24936201

  15. A promoter for the first nine genes of the Escherichia coli mra cluster of cell division and cell envelope biosynthesis genes, including ftsI and ftsW.

    PubMed Central

    Hara, H; Yasuda, S; Horiuchi, K; Park, J T

    1997-01-01

    We constructed a null allele of the ftsI gene encoding penicillin-binding protein 3 of Escherichia coli. It caused blockage of septation and loss of viability when expression of an extrachromosomal copy of ftsI was repressed, providing a final proof that ftsI is an essential cell division gene. In order to complement this null allele, the ftsI gene cloned on a single-copy mini-F plasmid required a region 1.9 kb upstream, which was found to contain a promoter sequence that could direct expression of a promoterless lacZ gene on a mini-F plasmid. This promoter sequence lies at the beginning of the mra cluster in the 2 min region of the E. coli chromosome, a cluster of 16 genes which, except for the first 2, are known to be involved in cell division and cell envelope biosynthesis. Disruption of this promoter, named the mra promoter, on the chromosome by inserting the lac promoter led to cell lysis in the absence of a lac inducer. The defect was complemented by a plasmid carrying a chromosomal fragment ranging from the mra promoter to ftsW, the fifth gene downstream of ftsI, but not by a plasmid lacking ftsW. Although several potential promoter sequences in this region of the mra cluster have been reported, we conclude that the promoter identified in this study is required for the first nine genes of the cluster to be fully expressed. PMID:9294438

  16. Inter- and intra-breed comparative study of sperm motility and viability in Iberian and Duroc boar semen during long-term storage in MR-A and XCell extenders.

    PubMed

    Martín-Hidalgo, D; Barón, F J; Robina, A; Bragado, M J; Llera, A Hurtado de; García-Marín, L J; Gil, M C

    2013-06-01

    During boar semen liquid preservation, extender is one of the factors that influence storage tolerance of spermatozoa. However, there are few studies about intra-breed variation in the preservation of semen quality during storage in different extenders. Similarly, boar breed is generally not considered a possible factor influencing variation in the semen storage tolerance in a particular extender. The aim of this study was to compare boar semen storage potential, in terms of the ability to maintain sperm viability and motility, of two currently used long-term extenders, MR-A and XCell. Extended semen from two breeds, Iberian and Duroc that had been stored at 17°C for up to 7 days was used. Intra- and inter-breed effect was studied. On Days 1, 4 and 7 (Day 0=day of semen collection), motility parameters and the percentage of total motile sperm and progressively motile sperm using a CASA system was evaluated. Viability (SYBR-14/PI) was evaluated by flow cytometry. Within each breed and for each storage day, there were differences between extenders, although semen tolerance to preservation was more influenced by the extender in the Iberian than in the Duroc breed. Neither breed nor extender influenced the percentage of viable spermatozoa during the storage time. Moreover, differences in motility parameters were observed between breeds, although the differences were greater when the XCell extender was used. In conclusion, both extender and breed influence motility characteristics of liquid-stored boar semen, so both aspects have to be considered in the design of comparative studies about stored boar semen quality from different breeds or with different extenders. Further studies are needed to corroborate these findings. PMID:23660365

  17. Reliability of vascular geometry factors derived from clinical MRA

    NASA Astrophysics Data System (ADS)

    Bijari, Payam B.; Antiga, Luca; Steinman, David A.

    2009-02-01

    Recent work from our group has demonstrated that the amount of disturbed flow at the carotid bifurcation, believed to be a local risk factor for carotid atherosclerosis, can be predicted from luminal geometric factors. The next step along the way to a large-scale retrospective or prospective imaging study of such local risk factors for atherosclerosis is to investigate whether these geometric features are reproducible and accurate from routine 3D contrast-enhanced magnetic resonance angiography (CEMRA) using a fast and practical method of extraction. Motivated by this fact, we examined the reproducibility of multiple geometric features that are believed important in atherosclerosis risk assessment. We reconstructed three-dimensional carotid bifurcations from 15 clinical study participants who had previously undergone baseline and repeat CEMRA acquisitions. Certain geometric factors were extracted and compared between the baseline and the repeat scan. As the spatial resolution of the CEMRA data was noticeably coarse and anisotropic, we also investigated whether this might affect the measurement of the same geometric risk factors by simulating the CEMRA acquisition for 15 normal carotid bifurcations previously acquired at high resolution. Our results show that the extracted geometric factors are reproducible and faithful, with intra-subject uncertainties well below inter-subject variabilities. More importantly, these geometric risk factors can be extracted consistently and quickly for potential use as disturbed flow predictors.

  18. High-Resolution Variable-Density 3D Cones Coronary MRA

    PubMed Central

    Addy, Nii Okai; Ingle, R. Reeve; Wu, Holden H.; Hu, Bob S.; Nishimura, Dwight G.

    2015-01-01

    Purpose To improve the spatial/temporal resolution of whole-heart coronary MR angiography (CMRA) by developing a variable-density (VD) 3D cones acquisition suitable for image reconstruction with parallel imaging and compressed sensing techniques. Methods A VD 3D cones trajectory design incorporates both radial and spiral trajectory undersampling techniques to achieve higher resolution. This design is used to generate a VD cones trajectory with 0.8 mm/66 ms isotropic spatial/temporal resolution, using a similar number of readouts as our previous fully sampled cones trajectory (1.2 mm/100 ms). Scans of volunteers and patients are performed to evaluate the performance of the VD trajectory, using non-Cartesian L1-ESPIRiT for high-resolution image reconstruction. Results With gridding reconstruction, the high-resolution scans experience an expected drop in signal-to-noise and contrast-to-noise ratios, but with L1-ESPIRiT, the apparent noise is substantially reduced. Compared to 1.2 mm images, in each volunteer, the L1-ESPIRiT 0.8 mm images exhibit higher vessel sharpness values in the right and left anterior descending arteries. Conclusion CMRA with isotropic sub-millimeter spatial resolution and high temporal resolution can be performed with VD 3D cones to improve the depiction of coronary arteries. PMID:26172829

  19. A wavelet-MRA-based adaptive semi-Lagrangian method for the relativistic Vlasov Maxwell system

    NASA Astrophysics Data System (ADS)

    Besse, Nicolas; Latu, Guillaume; Ghizzo, Alain; Sonnendrücker, Eric; Bertrand, Pierre

    2008-08-01

    In this paper we present a new method for the numerical solution of the relativistic Vlasov-Maxwell system on a phase-space grid using an adaptive semi-Lagrangian method. The adaptivity is performed through a wavelet multiresolution analysis, which gives a powerful and natural refinement criterion based on the local measurement of the approximation error and regularity of the distribution function. Therefore, the multiscale expansion of the distribution function allows to get a sparse representation of the data and thus save memory space and CPU time. We apply this numerical scheme to reduced Vlasov-Maxwell systems arising in laser-plasma physics. Interaction of relativistically strong laser pulses with overdense plasma slabs is investigated. These Vlasov simulations revealed a rich variety of phenomena associated with the fast particle dynamics induced by electromagnetic waves as electron trapping, particle acceleration, and electron plasma wavebreaking. However, the wavelet based adaptive method that we developed here, does not yield significant improvements compared to Vlasov solvers on a uniform mesh due to the substantial overhead that the method introduces. Nonetheless they might be a first step towards more efficient adaptive solvers based on different ideas for the grid refinement or on a more efficient implementation. Here the Vlasov simulations are performed in a two-dimensional phase-space where the development of thin filaments, strongly amplified by relativistic effects requires an important increase of the total number of points of the phase-space grid as they get finer as time goes on. The adaptive method could be more useful in cases where these thin filaments that need to be resolved are a very small fraction of the hyper-volume, which arises in higher dimensions because of the surface-to-volume scaling and the essentially one-dimensional structure of the filaments. Moreover, the main way to improve the efficiency of the adaptive method is to increase the local character in phase-space of the numerical scheme, by considering multiscale reconstruction with more compact support and by replacing the semi-Lagrangian method with more local - in space - numerical scheme as compact finite difference schemes, discontinuous-Galerkin method or finite element residual schemes which are well suited for parallel domain decomposition techniques.

  20. INVESTIGATING UNCERTAINTY AND SENSITIVITY IN INTEGRATED, MULTIMEDIA ENVIRONMENTAL MODELS: TOOLS FOR FRAMES-3MRA

    EPA Science Inventory

    Elucidating uncertainty and sensitivity structures in environmental models can be a difficult task, even for low-order, single-medium constructs driven by a unique set of site-specific data. Quantitative assessment of integrated, multimedia models that simulate hundreds of sites...

  1. Artery and vein separation using susceptibility-dependent phase in contrast-enhanced MRA.

    PubMed

    Wang, Y; Yu, Y; Li, D; Bae, K T; Brown, J J; Lin, W; Haacke, E M

    2000-11-01

    In magnetic resonance angiography, contrast agents are frequently used to help highlight arteries over background tissue. Unfortunately, enhancing veins hamper the visualization of arteries when data are collected over a long period of time after the arterial phase of the contrast agent. To overcome this problem, we have developed a novel imaging and postprocessing method that is capable of eliminating veins by utilizing the susceptibility difference between veins and surrounding tissue. This method was applied in the peripheral vasculature where the vessels are predominantly parallel to the main field and where the blood oxygen level-dependent effect is most pronounced. Results are presented for both long (15.8 msec) and short echo times (7.8 msec) and for sequential and centrally reordered acquisition schemes. The short echo scan approach appears to be the most promising, making it possible to obtain good suppression of the venous signal even when the timing is not perfect or when repeat scans are necessary.

  2. INVESTIGATING UNCERTAINTY AND SENSITIVITY IN INTEGRATED MULTIMEDIA ENVIRONMENTAL MODELS: TOOLS FOR 3MRA

    EPA Science Inventory

    Sufficiently elucidating uncertainty and sensitivity structures in environmental models can be a difficult task, even for low-order, single-media constructs driven by a unique set of site-specific data. The ensuing challenge of examining ever more complex, integrated, higher-ord...

  3. Ecosystem Services Modeling Infrastructures: Simile/MIMES (Gund Institute) and FRAMES/3MRA (US EPA) Integrated Modeling for Forecasting

    EPA Science Inventory

    The Ecological Research Program (ERP) of the EPA Office of Research and Development has the vision of a comprehensive theory and practice for characterizing, quantifying, and valuing ecosystem services and their relationship to human well-being for environmental decision making. ...

  4. A wavelet-MRA-based adaptive semi-Lagrangian method for the relativistic Vlasov-Maxwell system

    SciTech Connect

    Besse, Nicolas Latu, Guillaume Ghizzo, Alain Sonnendruecker, Eric Bertrand, Pierre

    2008-08-10

    In this paper we present a new method for the numerical solution of the relativistic Vlasov-Maxwell system on a phase-space grid using an adaptive semi-Lagrangian method. The adaptivity is performed through a wavelet multiresolution analysis, which gives a powerful and natural refinement criterion based on the local measurement of the approximation error and regularity of the distribution function. Therefore, the multiscale expansion of the distribution function allows to get a sparse representation of the data and thus save memory space and CPU time. We apply this numerical scheme to reduced Vlasov-Maxwell systems arising in laser-plasma physics. Interaction of relativistically strong laser pulses with overdense plasma slabs is investigated. These Vlasov simulations revealed a rich variety of phenomena associated with the fast particle dynamics induced by electromagnetic waves as electron trapping, particle acceleration, and electron plasma wavebreaking. However, the wavelet based adaptive method that we developed here, does not yield significant improvements compared to Vlasov solvers on a uniform mesh due to the substantial overhead that the method introduces. Nonetheless they might be a first step towards more efficient adaptive solvers based on different ideas for the grid refinement or on a more efficient implementation. Here the Vlasov simulations are performed in a two-dimensional phase-space where the development of thin filaments, strongly amplified by relativistic effects requires an important increase of the total number of points of the phase-space grid as they get finer as time goes on. The adaptive method could be more useful in cases where these thin filaments that need to be resolved are a very small fraction of the hyper-volume, which arises in higher dimensions because of the surface-to-volume scaling and the essentially one-dimensional structure of the filaments. Moreover, the main way to improve the efficiency of the adaptive method is to increase the local character in phase-space of the numerical scheme, by considering multiscale reconstruction with more compact support and by replacing the semi-Lagrangian method with more local - in space - numerical scheme as compact finite difference schemes, discontinuous-Galerkin method or finite element residual schemes which are well suited for parallel domain decomposition techniques.

  5. Right Cervical Aortic Arch and Pseudocoarctation of the Aorta Associated with Aneurysms and Steal Phenomena: US, CTA, and MRA Findings

    SciTech Connect

    Tanju, Sumru Ustuner, Evren; Erden, Ilhan; Aytac, Suat Kemal

    2007-02-15

    A 55-year-old woman presented with right cervical aortic arch with pseudocoarctation of the aorta further complicated by the presence of multiple aneurysms and a high-grade stenosis at the origin of the left subclavian trunk from the aorta causing a discrepancy in blood pressure between the right and left arms. The branching pattern and the resulting complex steal syndromes involving the left carotid and the subclavian system are unique. The computed tomography angiography, magnetic resonance angiography, and Doppler ultrasound findings are described.

  6. Identification and management of chronic shoulder pain in the presence of an MRA-confirmed humeral avulsion of the inferior glenohumeral ligament (HAGL) lesion

    PubMed Central

    Karmali, Arif; McLeod, Jennifer

    2016-01-01

    Objective: To present the assessment and conservative management of chronic shoulder pain in the presence of a humeral avulsion of the inferior glenohumeral ligament (HAGL) lesion in an active individual. Clinical Features: A 47 year-old female office-worker with constant, deep, right shoulder pain with occasional clicking and catching claimed to have “tore something” in her right shoulder five years ago while performing reverse bicep curls. A physical exam led to differential diagnoses of a Superior Labrum Anterior to Posterior (SLAP) lesion, Bankart lesion, and bicipital tendinopathy. A Magnetic Resonance Arthrogram revealed a HAGL lesion. Intervention and Outcome: A conservative chiropractic treatment plan in addition to physical therapy was initiated. The patient reported 75% improvement in symptoms after 4 treatments over a four-week duration. Summary: This case demonstrates the successful implementation of a conservative plan of management suggesting that the treatment provided to this patient should be considered and attempted prior to arthroscopic surgery. PMID:27385837

  7. THE RELATIVE IMPORTANCE OF THE VADOSE ZONE IN MULTIMEDIA RISK ASSESSMENT MODELING APPLIED AT A NATIONAL SCALE: AN ANALYSIS OF BENZENE USING 3MRA

    EPA Science Inventory

    Evaluating uncertainty and parameter sensitivity in environmental models can be a difficult task, even for low-order, single-media constructs driven by a unique set of site-specific data. The challenge of examining ever more complex, integrated, higher-order models is a formidab...

  8. Magnetic Resonance Angiography in the Diagnosis of Cerebral Arteriovenous Malformation and Dural Arteriovenous Fistulas: Comparison of Time-Resolved Magnetic Resonance Angiography and Three Dimensional Time-of-Flight Magnetic Resonance Angiography

    PubMed Central

    Cheng, Yu-Ching; Chen, Hung-Chieh; Wu, Chen-Hao; Wu, Yi-Ying; Sun, Ming-His; Chen, Wen-Hsien; Chai, Jyh-Wen; Chi-Chang Chen, Clayton

    2016-01-01

    Background Traditional digital subtraction angiography (DSA) is currently the gold standard diagnostic method for the diagnosis and evaluation of cerebral arteriovenous malformation (AVM) and dural arteriovenous fistulas (dAVF). Objectives The aim of this study was to analyze different less invasive magnetic resonance angiography (MRA) images, time-resolved MRA (TR-MRA) and three-dimensional time-of-flight MRA (3D TOF MRA) to identify their diagnostic accuracy and to determine which approach is most similar to DSA. Patients and Methods A total of 41 patients with AVM and dAVF at their initial evaluation or follow-up after treatment were recruited in this study. We applied time-resolved angiography using keyhole (4D-TRAK) MRA to perform TR-MRA and 3D TOF MRA examinations simultaneously followed by DSA, which was considered as a standard reference. Two experienced neuroradiologists reviewed the images to compare the diagnostic accuracy, arterial feeder and venous drainage between these two MRA images. Inter-observer agreement for different MRA images was assessed by Kappa coefficient and the differences of diagnostic accuracy between MRA images were evaluated by the Wilcoxon rank sum test. Results Almost all vascular lesions (92.68%) were correctly diagnosed using 4D-TRAK MRA. However, 3D TOF MRA only diagnosed 26 patients (63.41%) accurately. There were statistically significant differences regarding lesion diagnostic accuracy (P = 0.008) and venous drainage identification (P < 0.0001) between 4D-TRAK MRA and 3D TOF MRA. The results indicate that 4D-TRAK MRA is superior to 3D TOF MRA in the assessment of lesions. Conclusion Compared with 3D TOF MRA, 4D-TRAK MRA proved to be a more reliable screening modality and follow-up method for the diagnosis of cerebral AVM and dAVF.

  9. Magnetic Resonance Angiography in the Diagnosis of Cerebral Arteriovenous Malformation and Dural Arteriovenous Fistulas: Comparison of Time-Resolved Magnetic Resonance Angiography and Three Dimensional Time-of-Flight Magnetic Resonance Angiography

    PubMed Central

    Cheng, Yu-Ching; Chen, Hung-Chieh; Wu, Chen-Hao; Wu, Yi-Ying; Sun, Ming-His; Chen, Wen-Hsien; Chai, Jyh-Wen; Chi-Chang Chen, Clayton

    2016-01-01

    Background Traditional digital subtraction angiography (DSA) is currently the gold standard diagnostic method for the diagnosis and evaluation of cerebral arteriovenous malformation (AVM) and dural arteriovenous fistulas (dAVF). Objectives The aim of this study was to analyze different less invasive magnetic resonance angiography (MRA) images, time-resolved MRA (TR-MRA) and three-dimensional time-of-flight MRA (3D TOF MRA) to identify their diagnostic accuracy and to determine which approach is most similar to DSA. Patients and Methods A total of 41 patients with AVM and dAVF at their initial evaluation or follow-up after treatment were recruited in this study. We applied time-resolved angiography using keyhole (4D-TRAK) MRA to perform TR-MRA and 3D TOF MRA examinations simultaneously followed by DSA, which was considered as a standard reference. Two experienced neuroradiologists reviewed the images to compare the diagnostic accuracy, arterial feeder and venous drainage between these two MRA images. Inter-observer agreement for different MRA images was assessed by Kappa coefficient and the differences of diagnostic accuracy between MRA images were evaluated by the Wilcoxon rank sum test. Results Almost all vascular lesions (92.68%) were correctly diagnosed using 4D-TRAK MRA. However, 3D TOF MRA only diagnosed 26 patients (63.41%) accurately. There were statistically significant differences regarding lesion diagnostic accuracy (P = 0.008) and venous drainage identification (P < 0.0001) between 4D-TRAK MRA and 3D TOF MRA. The results indicate that 4D-TRAK MRA is superior to 3D TOF MRA in the assessment of lesions. Conclusion Compared with 3D TOF MRA, 4D-TRAK MRA proved to be a more reliable screening modality and follow-up method for the diagnosis of cerebral AVM and dAVF. PMID:27679690

  10. 32 CFR 70.4 - Responsibilities.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... (Manpower, Reserve Affairs, and Logistics) (ASD(MRA&L)) shall: (1) Resolve all issues concerning DRBs that... to the ASD(MRA&L) for decision; and include appropriate documentation through the Office of the...

  11. 32 CFR 56.6 - Information requirements.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... memorandum to the ASD(MRA&L), or designee, before July 15 and January 15 of each year. This reporting... narrative report by memorandum to the ASD(MRA&L), or designee, whenever, pursuant to enclosure 4 of...

  12. 32 CFR 56.6 - Information requirements.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... memorandum to the ASD(MRA&L), or designee, before July 15 and January 15 of each year. This reporting... narrative report by memorandum to the ASD(MRA&L), or designee, whenever, pursuant to enclosure 4 of...

  13. 32 CFR 56.6 - Information requirements.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... memorandum to the ASD(MRA&L), or designee, before July 15 and January 15 of each year. This reporting... narrative report by memorandum to the ASD(MRA&L), or designee, whenever, pursuant to enclosure 4 of...

  14. 23 CFR 637.209 - Laboratory and sampling and testing personnel qualifications.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... the National Cooperation for Laboratory Accreditation (NACLA), is a signatory to the Asia Pacific Laboratory Accreditation Cooperation (APLAC) Mutual Recognition Arrangement (MRA), is a signatory to the International Laboratory Accreditation Cooperation (ILAC) Mutual Recognition Arrangement (MRA), or...

  15. 32 CFR 56.10 - Ensuring compliance with this part in programs and activities conducted by the Department of...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Defense. (a) Supplementary guidelines. (1) Whenever necessary, the ASD(MRA&L), or designee, shall publish... to this Directive. Prior to their issuance, the ASD(MRA&L), or designee, shall submit supplementary... official shall notify the ASD(MRA&L), or designee, in writing. (b) Staff responsibilities. The...

  16. 32 CFR 56.10 - Ensuring compliance with this part in programs and activities conducted by the Department of...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Defense. (a) Supplementary guidelines. (1) Whenever necessary, the ASD(MRA&L), or designee, shall publish... to this Directive. Prior to their issuance, the ASD(MRA&L), or designee, shall submit supplementary... official shall notify the ASD(MRA&L), or designee, in writing. (b) Staff responsibilities. The...

  17. 32 CFR 56.5 - Responsibilities.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Logistics) (ASD(MRA&L)), or designee, shall monitor compliance with this part. In discharging this responsibility, the ASD(MRA&L), or designee, shall: (1) Coordinate efforts of DoD Components to enforce this part... the responsibilities assigned to the ASD(MRA&L) in § 56.8, 9, and 10. (4) Otherwise assist...

  18. 32 CFR 56.10 - Ensuring compliance with this part in programs and activities conducted by the Department of...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Defense. (a) Supplementary guidelines. (1) Whenever necessary, the ASD(MRA&L), or designee, shall publish... to this Directive. Prior to their issuance, the ASD(MRA&L), or designee, shall submit supplementary... official shall notify the ASD(MRA&L), or designee, in writing. (b) Staff responsibilities. The...

  19. 32 CFR 56.10 - Ensuring compliance with this part in programs and activities conducted by the Department of...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Defense. (a) Supplementary guidelines. (1) Whenever necessary, the ASD(MRA&L), or designee, shall publish... to this Directive. Prior to their issuance, the ASD(MRA&L), or designee, shall submit supplementary... official shall notify the ASD(MRA&L), or designee, in writing. (b) Staff responsibilities. The...

  20. 32 CFR 56.5 - Responsibilities.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Logistics) (ASD(MRA&L)), or designee, shall monitor compliance with this part. In discharging this responsibility, the ASD(MRA&L), or designee, shall: (1) Coordinate efforts of DoD Components to enforce this part... the responsibilities assigned to the ASD(MRA&L) in § 56.8, 9, and 10. (4) Otherwise assist...

  1. 32 CFR 56.10 - Ensuring compliance with this part in programs and activities conducted by the Department of...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Defense. (a) Supplementary guidelines. (1) Whenever necessary, the ASD(MRA&L), or designee, shall publish... to this Directive. Prior to their issuance, the ASD(MRA&L), or designee, shall submit supplementary... official shall notify the ASD(MRA&L), or designee, in writing. (b) Staff responsibilities. The...

  2. Whole-Body Magnetic Resonance Angiography with Additional Steady-State Acquisition of the Infragenicular Arteries in Patients with Peripheral Arterial Disease

    SciTech Connect

    Nielsen, Yousef W.; Eiberg, Jonas P.; Logager, Vibeke B.; Just, Sven; Schroeder, Torben V.; Thomsen, Henrik S.

    2010-06-15

    The purpose of this investigation was to determine if addition of infragenicular steady-state (SS) magnetic resonance angiography (MRA) to first-pass imaging improves diagnostic performance compared with first-pass imaging alone in patients with peripheral arterial disease (PAD) undergoing whole-body (WB) MRA. Twenty consecutive patients with PAD referred to digital-subtraction angiography (DSA) underwent WB-MRA. Using a bolus-chase technique, first-pass WB-MRA was performed from the supra-aortic vessels to the ankles. The blood-pool contrast agent gadofosveset trisodium was used at a dose of 0.03 mmol/kg body weight. Ten minutes after injection of the contrast agent, high-resolution (0.7-mm isotropic voxels) SS-MRA of the infragenicular arteries was performed. Using DSA as the 'gold standard,' sensitivities and specificities for detecting significant arterial stenoses ({>=}50% luminal narrowing) with first-pass WB-MRA, SS-MRA, and combined first-pass and SS-MRA were calculated. Kappa statistics were used to determine intermodality agreement between MRA and DSA. Overall sensitivity and specificity for detecting significant arterial stenoses with first-pass WB-MRA was 0.70 (95% confidence interval 0.61 to 0.78) and 0.97 (0.94 to 0.99), respectively. In first-pass WB-MRA, the lowest sensitivity was in the infragenicular region, with a value of 0.42 (0.23 to 0.63). Combined analysis of first-pass WB-MRA and SS-MRA increased sensitivity to 0.81 (0.60 to 0.93) in the infragenicular region, with specificity of 0.94 (0.88 to 0.97). Sensitivity and specificity for detecting significant arterial stenoses with isolated infragenicular SS-MRA was 0.47 (0.27 to 0.69) and 0.86 (0.78 to 0.91), respectively. Intermodality agreement between MRA and DSA in the infragenicular region was moderate for first-pass WB-MRA ({kappa} = 0.49), fair for SS-MRA ({kappa} = 0.31), and good for combined first-pass/SS-MRA ({kappa} = 0.71). Addition of infragenicular SS-MRA to first-pass WB MRA

  3. Meta-analysis on Diagnostic Accuracy of MR Angiography in the Follow-Up of Residual Intracranial Aneurysms Treated with Guglielmi Detachable Coils

    PubMed Central

    Weng, Hsu-Huei; Jao, Shaner-Yeun; Yang, Chun-Yuh; Tsai, Yuan-Hsiung

    2008-01-01

    Summary Patients with intracranial aneurysm after coiling with Guglielmi detachable coils (GDC) require imaging follow-up. The accuracy of noninvasive magnetic resonance angiography (MRA) techniques including time-of-flight (TOF) and contrast-enhancement (CE) have been compared with the gold standard digital subtraction angiography (DSA). We systematically reviewed the diagnostic accuracy of these imaging methods in follow-up study of patients with residual intracranial aneurysms after GDC treatment. The authors used MEDLINE, bibliographies, review articles, textbooks, and expert opinion to retrieve English-and non-English-language articles published from 1966 to December 2007. Sixteen suitable MRA original articles (14 TOF-MRA and six CE-MRA) with comparison to DSA have met the inclusion criteria. TOF-MRA had a pooled sensitivity of 90% (95% CI, 79% to 95%), a specificity of 95% (95% CI, 88% to 98%), and a diagnostic odds ratio (DOR) of 168.4 (95% CI, 60.3 to 470.3). CE-MRA had an overall sensitivity of 92% (95% CI, 79% to 97%), a specificity of 96% (95% CI, 91% to 98%), and a DOR of 280.4 (95% CI, 64.8 to 1212.6). The areas under two summary ROC curves of TOF-MRA and CE-MRA were 0.97 (95% CI, 0.96 to 0.99) and 0.98 (95% CI, 0.96 to 0.99), respectively. Compared with DS angiography, both TOF-MRA and CE-MRA can accurately depict the residual aneurysm. The diagnostic accuracy of TOF-MRA and CE-MRA tests offer comparable and equal results and may obviate the invasive DS angiography PMID:20557802

  4. 76 FR 66323 - National Register of Historic Places; Notification of Pending Nominations and Related Actions

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-26

    ...., Fagatogo, 11000789 GEORGIA Crawford County Hawkins, Col. Benjamin, Gravesite, Benjamin Hawkins Rd., Roberta... Wilson Pike, Franklin, 88000299 Russwurm, John S., House, (Williamson County MRA) Spann Town Rd. \\1/...

  5. MR Angiography of the Lower Extremities with a Moving-Bed Infusion-Tracking Technique

    SciTech Connect

    Klein, W.M.; Schlejen, P.M.; Eikelboom, B.C.; Graaf, Y. van der; Mali, W.P.T.M.

    2003-02-15

    Purpose: To assess the value of MR angiography (MRA) with automatic table movement in a consecutive series of patients with peripheral arterial disease. Methods: Seventy-two patients underwent both conventional angiography (CA) and MRA for peripheral arterial occlusive disease. Both techniques were scored in a masked way. Consensus scoring for CA was compared with MRA scoring per observer. If there was a discrepancy in scoring of asegment on MRA and CA, the images were reviewed and a consensus arrived at. Results: Observer A found 7.4% and observer B found 6.5% of the segments could not be analyzed on MRA. Observer A scored 11.4% dissimilar on MRA and CA, observer B 15.2%. In the aortoiliacarteries, this was mainly caused by stents and overestimation of stenoses; in the crural arteries it resulted from underestimation of the stenoses on MRA. Overall sensitivity and specificity for the aortoiliac, femoropopliteal and crural vessels were respectively 90% and 91%, 90% and 96%, 59% and 96% for observer A, and 85% and 91%, 84% and 89%, 68% and 85% for observer B. Conclusion: Although MRA of the lower extremities is a promising technique, improvements still need to be made. In particular, MRA below the knee is suboptimal for clinical use.

  6. Intracranial MR angiography: Its role in the integrated approach to brain infarction

    SciTech Connect

    Johnson, B.A.; Heiserman, J.E.; Drayer, B.P.; Keller, P.J.

    1994-05-01

    To determine the contribution of cranial MR angiography (MRA) for the evaluation of patients with acute and subacute brain infarction. MR and MRA studies performed on 78 adult patients with acute and subacute stroke were retrospectively reviewed and correlated with the clinical records. There were 50 acute and 28 subacute infarctions in our series. Five of 78 MRA exams (6%) were nondiagnostic. Sixty examinations (80%) were positive for stenosis or occlusion. The distribution of stenotic or occlusive vascular lesions correlated with the location of infarction in 56 of the 60 positive cases (93%). MRA provided information not obtained from the MR images in 40 cases (55%). One hundred four individual vessels in 8 patients who underwent conventional cerebral angiography were compared with the MRA appearance. The MRA interpretations correlated with the conventional angiographic evaluations for 90 vessels (87%). Vascular lesions demonstrated on intracranial MRA show a high correlation with infarct distribution. MRA provides information adjunctive to conventional MR in a majority of cases. We conclude that MRA is an important component of the complete evaluation of brain infarction. 39 refs., 3 figs., 2 tabs.

  7. Using qPCR for Water Microbial Risk Assessments

    EPA Science Inventory

    Microbial risk assessment (MRA) has traditionally utilized microbiological data that was obtained by culture-based techniques that are expensive and time consuming. With the advent of PCR methods there is a realistic opportunity to conduct MRA studies economically, in less time,...

  8. Qualitative analysis of the elliptical centric technique and the TRICKS technique

    NASA Astrophysics Data System (ADS)

    Dong, Kyung-Rae; Goo, Eun-Hoe; Lee, Jae-Seung; Chung, Woon-Kwan

    2013-02-01

    This study evaluated the usefulness of time resolved imaging of contrast kinetics (TRICKS) magnetic resonance angiography (MRA) and elliptical centric MRA according to the type of cerebral disease. From February 2010 to January 2012, elliptical centric MRA and TRICKS MRA images were acquired from 50 normal individuals and 50 patients with cerebral diseases by using 3.0-Tesla magnetic resonance imaging (MRI) equipment. The images were analyzed qualitatively by examining areas such as the presence or absence of artifacts on the images, the distinctness of boundaries of blood vessels, accurate representation of the lesions, and the subtraction level. In addition, the sensitivity, specificity, positive prediction rate, negative prediction rate and accuracy were assessed by comparing the diagnostic efficacy of the two techniques. The results revealed TRICKS MRA to have superior image quality to elliptical centric MRA. Regarding each disease, TRICKS MRA showed higher diagnostic efficacy for artery venous malformation (AVM) and middle cerebral artery (MCA) bypass patients whereas elliptical centric MRA was more suitable for patients with brain tumors, cerebral infarction, cerebral stenosis or sinus mass.

  9. 32 CFR 56.9 - Ensuring compliance with this part in Federal financial assistance programs and activities.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., and the regulations thereunder (41 CFR part 60-741) and if a DoD Component has reason to believe that... approval of these supplementary guidelines from the ASD(MRA&L), or designee, before issuing them. Prior to their issuance, the ASD(MRA&L), or designee, shall submit supplementary guidelines prepared pursuant...

  10. 32 CFR 56.9 - Ensuring compliance with this part in Federal financial assistance programs and activities.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., and the regulations thereunder (41 CFR part 60-741) and if a DoD Component has reason to believe that... approval of these supplementary guidelines from the ASD(MRA&L), or designee, before issuing them. Prior to their issuance, the ASD(MRA&L), or designee, shall submit supplementary guidelines prepared pursuant...

  11. 32 CFR 56.9 - Ensuring compliance with this part in Federal financial assistance programs and activities.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., and the regulations thereunder (41 CFR part 60-741) and if a DoD Component has reason to believe that... approval of these supplementary guidelines from the ASD(MRA&L), or designee, before issuing them. Prior to their issuance, the ASD(MRA&L), or designee, shall submit supplementary guidelines prepared pursuant...

  12. 32 CFR 56.9 - Ensuring compliance with this part in Federal financial assistance programs and activities.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., and the regulations thereunder (41 CFR part 60-741) and if a DoD Component has reason to believe that... approval of these supplementary guidelines from the ASD(MRA&L), or designee, before issuing them. Prior to their issuance, the ASD(MRA&L), or designee, shall submit supplementary guidelines prepared pursuant...

  13. Does Marketing Attract Less Ethical Students? An Assessment of the Moral Reasoning Ability of Undergraduate Marketing Students

    ERIC Educational Resources Information Center

    Herington, Carmel; Weaven, Scott

    2007-01-01

    This article assesses the level of moral reasoning ability (MRA) of undergraduate marketing students and compares the results with the MRA of students in a range of other business disciplines. The aim was to determine if marketing attracts individuals who have a greater predisposition to unethical behaviors given that marketing is often reported…

  14. Institutional Innovation and Public Extension Services Provision: The Marche Regional Administration Reform in Central Italy

    ERIC Educational Resources Information Center

    Pascucci, Stefano; De Magistris, Tiziana

    2011-01-01

    This paper describes how Marche Regional Administration (MRA) introduced an innovative institutional reform of an Agricultural Knowledge and Information System (AKIS) in central Italy. In order to study the main features of the MRA reform we used a methodological approach based on three steps: (i) first we applied a desk analysis to sketch the…

  15. Microbiological risk assessment in developing countries.

    PubMed

    Cahill, Sarah M; Jouve, Jean-Louis R

    2004-09-01

    Microbiological risk assessment (MRA) has been evolving at the national and international levels as a systematic and objective approach for evaluating information pertaining to microbiological hazards in foods and the risks they pose. This process has been catalyzed by international food trade requirements to base sanitary measures on sound scientific evidence and appropriate risk assessments. All countries, including developing countries, need to understand and use MRA. MRA is resource intensive, as has been demonstrated by some of the the assessments undertaken in industrialized countries. However, when used in the appropriate circumstances MRA offers many benefits. The process of undertaking MRA improves the understanding of key issues, enables an objective evaluation of risk management options, and provides a scientific justification for actions. Although the gap between developing countries and some industrialized countries is quite extensive with regard to MRA, many developing countries recognize the need to at least understand and move toward using MRA. This process requires development of infrastructure and enhancement of scientific and technical expertise while making optimal use of limited resources. International organizations, such as the Food and Agriculture Organization of the United Nations, are in a position to provide countries with guidance, training, information resources, and technical assistance to develop and/or strengthen food safety infrastructure. Enhanced cooperation and collaboration at all levels are needed for such efforts to be successful and to ensure that MRA, as a food safety tool, is available to all countries. PMID:15453597

  16. 75 FR 52437 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-26

    ... ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does.../DME.. *DEBOW, WI FIX **4000 *10000--MRA **3000--GNSS MEA JANESVILLE R-044 UNUSABLE, USE BADGER R-226. *DEBOW, WI FIX RASTT, WI FIX **4000 *10000--MRA **4000--GNSS MEA RASTT, WI FIX BADGER, WI...

  17. Development of a surgical site infection (SSI) surveillance system, calculation of SSI rates and specification of important factors affecting SSI in a digestive organ surgical department.

    PubMed

    Kimura, Koji; Sawa, Akihiro; Akagi, Shinji; Kihira, Kenji

    2007-06-01

    We have developed an original system to conduct surgical site infection (SSI) surveillance. This system accumulates SSI surveillance information based on the National Nosocomial Infections Surveillance (NNIS) System and the Japanese Nosocomial Infections Surveillance (JNIS) System. The features of this system are as follows: easy input of data, high generality, data accuracy, SSI rate by operative procedure and risk index category (RIC) can be promptly calculated and compared with the current NNIS SSI rate, and the SSI rates and accumulated data can be exported electronically. Using this system, we monitored 798 patients in 24 operative procedure categories in the Digestive Organs Surgery Department of Mazda Hospital, Mazda Motor Corporation, from January 2004 through December 2005. The total number and rate of SSI were 47 and 5.89%, respectively. The SSI rates of 777 patients were calculated based on 15 operative procedure categories and Risk Index Categories (RIC). The highest SSI rate was observed in the rectum surgery of RIC 1 (30%), followed by the colon surgery of RIC3 (28.57%). About 30% of the isolated infecting bacteria were Enterococcus faecalis, Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Escherichia coli. Using quantification theory type 2, the American Society of Anesthesiology score (4.531), volume of hemorrhage under operation (3.075), wound classification (1.76), operation time (1.352), and history of diabetes (0.989) increased to higher ranks as factors for SSI. Therefore, we evaluated this system as a useful tool in safety control for operative procedures. PMID:17760267

  18. Lessons in Medical Record Abstraction from the Prostate, Lung, Colorectal, and Ovarian (PLCO) National Screening Trial.

    PubMed

    Bazzi, Latifa; Lamerato, Lois E; Varner, Julie; Shambaugh, Vicki L; Cordes, Jill E; Ragard, Lawrence R; Marcus, Pamela M

    2015-01-01

    The most rigorous and accurate approach to evaluating clinical events in cancer screening studies is to use data obtained through medical record abstraction (MRA). Although MRA is complex, the particulars of the procedure-such as the specific training and quality assurance processes, challenges of implementation, and other factors that influence the quality of abstraction--are usually not described in reports of studies that employed the technique. In this paper, we present the details of MRA activities used in the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial, which used MRA to determine primary and secondary outcomes and collect data on other clinical events. We describe triggers of the MRA cycle and the specific tasks that were part of the abstraction process. We also discuss training and certification of abstracting staff, and technical methods and communication procedures used for data quality assurance. We include discussion of challenges faced and lessons learned.

  19. Comparison of imaging modalities for the accurate delineation of arteriovenous malformation, with reference to stereotactic radiosurgery

    SciTech Connect

    Aoyama, Hidefumi . E-mail: hao@radi.med.hokudai.ac.jp; Shirato, Hiroki; Katoh, Norio; Kudo, Kohsuke; Asano, Takeshi; Kuroda, Satoshi; Ishikawa, Tatsuya; Miyasaka, Kazuo

    2005-07-15

    Purpose: To investigate the discrepancy between the arteriovenous malformations seen on magnetic resonance angiography (MRA) and on stereotactic digital subtracted angiography (DSA). Methods and Materials: The target volume on stereotactic DSA (V{sub DSA} ) and the target volume on MRA (V{sub MRA} ) were separately delineated in 28 intracranial arteriovenous malformations. The coordinates of the center and the outer edges of V{sub DSA} and V{sub MRA} were calculated and used for the analyses. Results: The standard deviations (mean value) of the displacement of centers of V{sub MRA} from V{sub DSA} were 2.67 mm (-1.82 mm) in the left-right direction, 3.23 mm (-0.08 mm) in the anterior-posterior direction, and 2.16 mm (0.91 mm) in the craniocaudal direction. V{sub MRA} covered less than 80% of V{sub DSA} in any dimensions in 9 cases (32%), although no significant difference was seen in the target volume between each method, with a mean value of 11.9 cc for V{sub DSA} and 12.3 cc for V{sub MRA} (p = 0.948). Conclusion: The shift of centers between each modality is not negligible. Considering no significant difference between V{sub DSA} and V{sub MRA} , but inadequate coverage of the V{sub DSA} by V{sub MRA} , it is reasonable to consider that the target on MRA might include the feeding artery and draining vein and possibly miss a portion of the nidus.

  20. Three-dimensional time-of-flight MR angiography for evaluation of intracranial aneurysms after endosaccular packing with Guglielmi detachable coils: comparison with 3D digital subtraction angiography.

    PubMed

    Okahara, Mika; Kiyosue, Hiro; Hori, Yuzo; Yamashita, Masanori; Nagatomi, Hirofumi; Mori, Hiromu

    2004-07-01

    The sensitivities and specificities of three-dimensional time-of-flight MR angiography (3D-TOF MRA) and 3D digital subtraction angiography (3D-DSA) were compared for evaluation of cerebral aneurysms after endosaccular packing with Guglielmi detachable coils (GDCs). Thirty-three patients with 33 aneurysms were included in this prospective study. 3D-TOF MRA and 3D-DSA were performed in the same week on all patients. Maximal intensity projection (MIP) and 3D reconstructed MRA images were compared with 3D-DSA images. The diameters of residual/recurrent aneurysms detected on 3D-DSA were calculated on a workstation. In 3 (9%) of 33 aneurysms, 3D-TOF MRA did not provide reliable information due to significant susceptibility artifacts on MRA. The sensitivity and specificity rates of MRA were 72.7 and 90.9%, respectively, for the diagnosis of residual/recurrent aneurysm. The diameters of residual/recurrent aneurysms that could not be detected by MRA were significantly smaller than those of detected aneurysms (mean 1.1 vs mean 2.3 mm). In one aneurysm of the anterior communicating artery (ACoA), the relationship between the residual aneurysm and the ACoA was more evident on MRA than DSA images. MRA can detect the recurrent/residual lumen of aneurysms treated with GDCs of up to at least 1.8 mm in diameter. 3D-TOF MRA is useful for follow-up of intracranial aneurysms treated with GDCs, and could partly replace DSA.

  1. Structural insights into inhibition of lipid I production in bacterial cell wall synthesis.

    PubMed

    Chung, Ben C; Mashalidis, Ellene H; Tanino, Tetsuya; Kim, Mijung; Matsuda, Akira; Hong, Jiyong; Ichikawa, Satoshi; Lee, Seok-Yong

    2016-05-26

    Antibiotic-resistant bacterial infection is a serious threat to public health. Peptidoglycan biosynthesis is a well-established target for antibiotic development. MraY (phospho-MurNAc-pentapeptide translocase) catalyses the first and an essential membrane step of peptidoglycan biosynthesis. It is considered a very promising target for the development of new antibiotics, as many naturally occurring nucleoside inhibitors with antibacterial activity target this enzyme. However, antibiotics targeting MraY have not been developed for clinical use, mainly owing to a lack of structural insight into inhibition of this enzyme. Here we present the crystal structure of MraY from Aquifex aeolicus (MraYAA) in complex with its naturally occurring inhibitor, muraymycin D2 (MD2). We show that after binding MD2, MraYAA undergoes remarkably large conformational rearrangements near the active site, which lead to the formation of a nucleoside-binding pocket and a peptide-binding site. MD2 binds the nucleoside-binding pocket like a two-pronged plug inserting into a socket. Further interactions it makes in the adjacent peptide-binding site anchor MD2 to and enhance its affinity for MraYAA. Surprisingly, MD2 does not interact with three acidic residues or the Mg(2+) cofactor required for catalysis, suggesting that MD2 binds to MraYAA in a manner that overlaps with, but is distinct from, its natural substrate, UDP-MurNAc-pentapeptide. We have determined the principles of MD2 binding to MraYAA, including how it avoids the need for pyrophosphate and sugar moieties, which are essential features for substrate binding. The conformational plasticity of MraY could be the reason that it is the target of many structurally distinct inhibitors. These findings can inform the design of new inhibitors targeting MraY as well as its paralogues, WecA and TarO. PMID:27088606

  2. Structural insights into inhibition of Lipid I production in bacterial cell wall synthesis

    PubMed Central

    Tanino, Tetsuya; Kim, Mijung; Matsuda, Akira; Hong, Jiyong; Ichikawa, Satoshi; Lee, Seok-Yong

    2016-01-01

    Summary Antibiotic-resistant bacterial infection is a serious threat to public health. Peptidoglycan biosynthesis is a well-established target for antibiotic development. MraY (phospho-MurNAc-pentapeptide translocase) catalyzes the first and an essential membrane step of peptidoglycan biosynthesis. It is considered a very promising target for the development of new antibiotics, as many naturally occuring nucleoside inhibitors with antibacterial activity target this enzyme1-4. However, antibiotics targeting MraY have not been developed for clinical use mainly due to a lack of structural insight into inhibition of this enzyme. Here we present the crystal structure of MraY from Aquifex aeolicus (MraYAA) in complex with its naturally occurring inhibitor, muraymycin D2 (MD2). Upon binding MD2, MraYAA undergoes remarkably large conformational rearrangements near the active site, which lead to the formation of a nucleoside-binding pocket and a peptide-binding site. MD2 binds the nucleoside-binding pocket like a two-pronged plug inserting into a socket. Additional interactions it makes in the adjacent peptide-binding site anchor MD2 to and enhance its affinity for MraYAA. Surprisingly, MD2 does not interact with three acidic residues or the Mg2+ cofactor required for catalysis, suggesting that MD2 binds to MraYAA in a manner that overlaps with, but is distinct from its natural substrate, UDP-MurNAc-pentapeptide. We have deciphered the chemical logic of MD2 binding to MraYAA, including how it avoids the need for pyrophosphate and sugar moieties, which are essential features for substrate binding. The conformational plasticity of MraY could be the reason that it is the target of many structurally distinct inhibitors. These findings can inform the design of new inhibitors targeting MraY as well as its paralogs, WecA and TarO. PMID:27088606

  3. Analysis and dynamic 3D visualization of cerebral blood flow combining 3D and 4D MR image sequences

    NASA Astrophysics Data System (ADS)

    Forkert, Nils Daniel; Säring, Dennis; Fiehler, Jens; Illies, Till; Möller, Dietmar; Handels, Heinz

    2009-02-01

    In this paper we present a method for the dynamic visualization of cerebral blood flow. Spatio-temporal 4D magnetic resonance angiography (MRA) image datasets and 3D MRA datasets with high spatial resolution were acquired for the analysis of arteriovenous malformations (AVMs). One of the main tasks is the combination of the information of the 3D and 4D MRA image sequences. Initially, in the 3D MRA dataset the vessel system is segmented and a 3D surface model is generated. Then, temporal intensity curves are analyzed voxelwise in the 4D MRA image sequences. A curve fitting of the temporal intensity curves to a patient individual reference curve is used to extract the bolus arrival times in the 4D MRA sequences. After non-linear registration of both MRA datasets the extracted hemodynamic information is transferred to the surface model where the time points of inflow can be visualized color coded dynamically over time. The dynamic visualizations computed using the curve fitting method for the estimation of the bolus arrival times were rated superior compared to those computed using conventional approaches for bolus arrival time estimation. In summary the procedure suggested allows a dynamic visualization of the individual hemodynamic situation and better understanding during the visual evaluation of cerebral vascular diseases.

  4. A feasibility study for compressed sensing combined phase contrast MR angiography reconstruction

    NASA Astrophysics Data System (ADS)

    Lee, Dong-Hoon; Hong, Cheol-Pyo; Lee, Man-Woo; Han, Bong-Soo

    2012-02-01

    Phase contrast magnetic resonance angiography (PC MRA) is a technique for flow velocity measurement and vessels visualization, simultaneously. The PC MRA takes long scan time because each flow encoding gradients which are composed bipolar gradient type need to reconstruct the angiography image. Moreover, it takes more image acquisition time when we use the PC MRA at the low-tesla MRI system. In this study, we studied and evaluation of feasibility for CS MRI reconstruction combined PC MRA which data acquired by low-tesla MRI system. We used non-linear reconstruction algorithm which named Bregman iteration for CS image reconstruction and validate the usefulness of CS combined PC MRA reconstruction technique. The results of CS reconstructed PC MRA images provide similar level of image quality between fully sampled reconstruction data and sparse sampled reconstruction using CS technique. Although our results used half of sampling ratio and do not used specification hardware device or performance which are improving the temporal resolution of MR image acquisition such as parallel imaging reconstruction using phased array coil or non-cartesian trajectory, we think that CS combined PC MRA technique will be helpful to increase the temporal resolution and at low-tesla MRI system.

  5. Detection of Type II Endoleak After Endovascular Aortic Repair: Comparison Between Magnetic Resonance Angiography and Blood-Pool Contrast Agent and Dual-Phase Computed Tomography Angiography

    SciTech Connect

    Wieners, Gero; Meyer, Frank; Halloul, Zuhir; Peters, Nils; Ruehl, Ricarda; Dudeck, Oliver; Tautenhahn, Joerg; Ricke, Jens; Pech, Maciej

    2010-12-15

    PurposeThis prospective study was designed to assess the diagnostic value of magnetic resonance angiography (MRA) with blood-pool contrast agent (gadofosveset) in the detection of type-II endoleak after endovascular aortic repair (EVAR).MethodsThirty-two patients with aortic aneurysms who had undergone EVAR were included in this study. All patients were examined by dual-phase computed tomography angiography (CTA) as well as MRA with gadofosveset in the first-pass and steady-state phases. Two independent readers evaluated the images of CTA and MRA in terms of endoleak type II, feeding vessel, and image quality.ResultsMedian follow-up-time after EVAR was 22 months (range 4 to 59). Endoleak type II was detected by CTA in 12 of 32 patients (37.5%); MRA detected endoleak in all of these patients as well as in another 9 patients (n = 21, 65.6%), of whom the endoleaks in 6 patients showed an increasing diameter. Most endoleaks were detected in the steady-state phase (n = 14). The decrease in diameter of the aneurysmal sac was significantly greater in the patients without a visible endoleak that was visible on MRA (P = 0.004). In the overall estimation of diagnostic accuracy, MRA was judged superior to CTA in 66% of all examinations.ConclusionMRA with gadofosveset appeared superior to CTA, and has higher diagnostic accuracy, in the detection of endoleak after EVAR.

  6. Evaluation of the lower limb vasculature before free fibula flap transfer. A prospective blinded comparison between magnetic resonance angiography and digital subtraction angiography.

    PubMed

    Klein, Steven; Van Lienden, Krijn P; Van't Veer, Marcel; Smit, Jeroen M; Werker, Paul M N

    2013-10-01

    Introduction The aim of this study was to compare magnetic resonance angiography (MRA) with digital subtraction angiography (DSA) in the preoperative assessment of crural arteries and their skin perforators prior to free fibular transfer. Patients and methods Fifteen consecutive patients, scheduled for free vascularized fibular flap transfer, were subjected to DSA as well as MRA of the crural arteries of both legs (n = 30). All DSA and MRA images were assessed randomly, blindly, and independently by two radiologists. Each of the assessors scored the degree of stenosis of various segments on a 5 point scale from 0 (occlusive) to 4 (no stenosis). The Cohen's Kappa coefficient was used to assess the agreement between DSA and MRA scores. In addition, the number of cutaneous perforators were scored and the assessors were asked if they would advise against fibula harvest and transplantation based on the images. Results A Cohen's Kappa of 0.64, indicating "substantial agreement of stenosis severity scores" was found between the two imaging techniques. The sensitivity of MRA to detect a stenosis compared with DSA was 79% (CI 95%:60-91), and a specificity of 98% (CI 95%: 97-99). In 53 out of 60 assessments, advice on suitability for transfer were equal between DSA and MRA. The median number of cutaneous perforators that perfuse the skin overlying the fibula per leg was one for DSA as well as MRA (P = 0.142).Conclusions A substantial agreement in the assessment of stenosis severity was found between DSA and MRA. The results suggest that MRA is a good alternative to DSA in the preoperative planning of free fibula flap transplantation. PMID:24038374

  7. Magnetic Resonance Arthrogram Referrals by Subspecialist and Non-Subspecialist Orthopaedic Surgeons: What are the Findings?

    PubMed Central

    Al-Ani, Zeid; Ali, Syed; Beardmore, Simon; Parmar, Vinay; Chooi Oh, Teik

    2016-01-01

    Background: Although subspecialist orthopaedic surgeons usually request Magnetic Resonance Arthrogram (MRA) examinations, some orthopaedic surgeons may request this examination for a body part that is different from their subspecialty. The purpose of the study is to compare the MRA and the clinical findings in the subspecialist and non-subspecialist groups. Method: Retrospective analysis of MRA examinations over a 6-month period. Findings were compared with the clinical information. Results: There were 144 examinations (69 shoulder, 42 wrist and 33 hip). 85% of these were subspecialist referrals; 60% of them showed findings compatible with the clinical diagnosis. 15% of the MRA examinations were non-subspecialist referrals; 52% of them correlated with the clinical findings. Overall, clinical information agreed with MRA findings for shoulder labral tears, hip labral tears and wrist triangular fibrocartilage complex tears in 63.3%, 64.5% and 61.5% respectively. The subspecialist group were more accurate than the non-subspecialist group in diagnosing hip labral tears (68% vs. 50%) and triangular fibrocartilage complex tears (62.5% vs. 50%). On the contrary, shoulder MRA and clinical findings correlated better in the non-subspecialist group (77.8%) compared to the subspecialist group (63.3%). However, the small number of requests generated by the non-subspecialist group may affect the results. Suspected scapholunate ligament injury showed low correlation with MRA at 26.7% (33.3% in the subspecialist group and 0% in the non-subspecialist group). Conclusion: Generally, the clinical findings are more accurate in the subspecialist referrals when compared to MRA findings and therefore a subspecialist referral is preferred. The low agreement between clinically suspected scapholunate ligament injuries and wrist MRA probably reflects the relative difficulty in establishing this diagnosis clinically. PMID:27733882

  8. Factors Affecting Accuracy of Data Abstracted from Medical Records

    PubMed Central

    Zozus, Meredith N.; Pieper, Carl; Johnson, Constance M.; Johnson, Todd R.; Franklin, Amy; Smith, Jack; Zhang, Jiajie

    2015-01-01

    Objective Medical record abstraction (MRA) is often cited as a significant source of error in research data, yet MRA methodology has rarely been the subject of investigation. Lack of a common framework has hindered application of the extant literature in practice, and, until now, there were no evidence-based guidelines for ensuring data quality in MRA. We aimed to identify the factors affecting the accuracy of data abstracted from medical records and to generate a framework for data quality assurance and control in MRA. Methods Candidate factors were identified from published reports of MRA. Content validity of the top candidate factors was assessed via a four-round two-group Delphi process with expert abstractors with experience in clinical research, registries, and quality improvement. The resulting coded factors were categorized into a control theory-based framework of MRA. Coverage of the framework was evaluated using the recent published literature. Results Analysis of the identified articles yielded 292 unique factors that affect the accuracy of abstracted data. Delphi processes overall refuted three of the top factors identified from the literature based on importance and five based on reliability (six total factors refuted). Four new factors were identified by the Delphi. The generated framework demonstrated comprehensive coverage. Significant underreporting of MRA methodology in recent studies was discovered. Conclusion The framework generated from this research provides a guide for planning data quality assurance and control for studies using MRA. The large number and variability of factors indicate that while prospective quality assurance likely increases the accuracy of abstracted data, monitoring the accuracy during the abstraction process is also required. Recent studies reporting research results based on MRA rarely reported data quality assurance or control measures, and even less frequently reported data quality metrics with research results. Given

  9. Bile salt receptor complex activates a pathogenic type III secretion system.

    PubMed

    Li, Peng; Rivera-Cancel, Giomar; Kinch, Lisa N; Salomon, Dor; Tomchick, Diana R; Grishin, Nick V; Orth, Kim

    2016-01-01

    Bile is an important component of the human gastrointestinal tract with an essential role in food absorption and antimicrobial activities. Enteric bacterial pathogens have developed strategies to sense bile as an environmental cue to regulate virulence genes during infection. We discovered that Vibrio parahaemolyticus VtrC, along with VtrA and VtrB, are required for activating the virulence type III secretion system 2 in response to bile salts. The VtrA/VtrC complex activates VtrB in the presence of bile salts. The crystal structure of the periplasmic domains of the VtrA/VtrC heterodimer reveals a β-barrel with a hydrophobic inner chamber. A co-crystal structure of VtrA/VtrC with bile salt, along with biophysical and mutational analysis, demonstrates that the hydrophobic chamber binds bile salts and activates the virulence network. As part of a family of conserved signaling receptors, VtrA/VtrC provides structural and functional insights into the evolutionarily conserved mechanism used by bacteria to sense their environment. PMID:27377244

  10. Bile salt receptor complex activates a pathogenic type III secretion system

    PubMed Central

    Li, Peng; Rivera-Cancel, Giomar; Kinch, Lisa N; Salomon, Dor; Tomchick, Diana R; Grishin, Nick V; Orth, Kim

    2016-01-01

    Bile is an important component of the human gastrointestinal tract with an essential role in food absorption and antimicrobial activities. Enteric bacterial pathogens have developed strategies to sense bile as an environmental cue to regulate virulence genes during infection. We discovered that Vibrio parahaemolyticus VtrC, along with VtrA and VtrB, are required for activating the virulence type III secretion system 2 in response to bile salts. The VtrA/VtrC complex activates VtrB in the presence of bile salts. The crystal structure of the periplasmic domains of the VtrA/VtrC heterodimer reveals a β-barrel with a hydrophobic inner chamber. A co-crystal structure of VtrA/VtrC with bile salt, along with biophysical and mutational analysis, demonstrates that the hydrophobic chamber binds bile salts and activates the virulence network. As part of a family of conserved signaling receptors, VtrA/VtrC provides structural and functional insights into the evolutionarily conserved mechanism used by bacteria to sense their environment. DOI: http://dx.doi.org/10.7554/eLife.15718.001 PMID:27377244

  11. The Harvard Catalyst Common Reciprocal IRB Reliance Agreement: an innovative approach to multisite IRB review and oversight.

    PubMed

    Winkler, Sabune J; Witte, Elizabeth; Bierer, Barbara E

    2015-02-01

    Reduction of duplicative Institutional Review Board (IRB) review for multiinstitutional studies is a desirable goal to improve IRB efficiency while enhancing human subject protections. Here we describe the Harvard Catalyst Master Reciprocal Common IRB Reliance Agreement (MRA), a system that provides a legal framework for IRB reliance, with the potential to streamline IRB review processes and reduce administrative burden and barriers to collaborative, multiinstitutional research. The MRA respects the legal autonomy of the signatory institutions while offering a pathway to eliminate duplicative IRB review when appropriate. The Harvard Catalyst MRA provides a robust and flexible model for reciprocal reliance that is both adaptable and scalable.

  12. Imaging Evaluation of Superior Labral Anteroposterior (SLAP) Tears.

    PubMed

    Grubin, Jeremy; Maderazo, Alex; Fitzpatrick, Darren

    2015-10-01

    Superior labral anteroposterior (SLAP) tears are common injuries that are best evaluated with magnetic resonance arthrography (MRA), as it provides the most detailed evaluation of the bicipital labral complex. Given the variety and complexity of SLAP tears, distention of the joint with intra-articular dilute gadolinium contrast properly separates the intra-articular biceps tendon, superior labrum, glenoid cartilage and glenohumeral ligaments to optimize assessment of these structures. This allows for increased diagnostic confidence of the interpreting radiologist and provides a better road map for the surgeon prior to arthroscopy. Indirect MRA and high-field magnetic resonance imaging are sensitive and specific alternative modalities if MRA cannot be performed.

  13. The Harvard Catalyst Common Reciprocal IRB Reliance Agreement

    PubMed Central

    Winkler, Sabune J.; Witte, Elizabeth; Bierer, Barbara E.

    2014-01-01

    Reduction of duplicative Institutional Review Board (IRB) review for multi-institutional studies is a desirable goal to improve IRB efficiency while enhancing human subject protections. Here we describe the Harvard Catalyst Master Reciprocal Common IRB Reliance Agreement (MRA), a system that provides a legal framework for IRB reliance, with the potential to streamline IRB review processes and reduce administrative burden and barriers to collaborative, multi-institutional research. The MRA respects the legal autonomy of the signatory institutions while offering a pathway to eliminate duplicative IRB review when appropriate. The Harvard Catalyst MRA provides a robust and flexible model for reciprocal reliance that is both adaptable and scalable. PMID:25196592

  14. Magnetic resonance angiography in perforator flap breast reconstruction

    PubMed Central

    Levine, Joshua L.

    2016-01-01

    Magnetic resonance angiography (MRA) is an extremely useful preoperative imaging test for evaluation of the vasculature of donor tissue to be used in autologous breast reconstruction. MRA has sufficient spacial resolution to reliably visualize 1 mm perforating vessels and to accurately locate vessels in reference to a patient’s anatomic landmarks without exposing patients to ionizing radiation or iodinated contrast. The use of a blood pool contrast agent and the lack of radiation exposure allow multiple studies of multiple anatomic regions in one examination. The following article is a detailed description of our MRA protocol developed with our radiologists with examples that illustrate the utility of MRA in perforator flap breast reconstruction. PMID:27047787

  15. Magnetic Resonance Angiography: Current Status in the Planning and Follow-Up of Endovascular Treatment in Lower-Limb Arterial Disease

    SciTech Connect

    Lakshminarayan, Raghuram; Simpson, James O.; Ettles, Duncan F.

    2009-05-15

    Magnetic resonance angiography (MRA) has become an established imaging modality in the management of lower-limb arterial disease, with emerging roles in treatment planning and follow-up. Contrast-enhanced MRA is now the most widely used technique with clinically acceptable results in the majority of patients. Difficulties in imaging and image interpretation are recognised in certain subgroups, including patients with critical limb ischaemia as well as patients with stents. Although newer contrast agents and refined imaging protocols may offer some solutions to these problems, this optimism is balanced by concerns about the toxicity of certain gadolinium chelates. Further development of interventional MRA remains one of the most significant challenges in the development of magnetic resonance imaging-guided peripheral vascular intervention. The status of MRA in managing patients with lower-limb arterial disease in current clinical practice is reviewed.

  16. Time-Resolved Magnetic Resonance Angiography in the Evaluation of Intracranial Vascular Lesions and Tumors: A Pictorial Essay of Our Experience.

    PubMed

    Liu, Ming-Cheng; Chen, Hung-Chieh; Wu, Chen-Hao; Chen, Wen-Hsien; Tsuei, Yuang-Seng; Chen, Clayton Chi-Chang

    2015-11-01

    Time-resolved magnetic resonance angiography (TR MRA) is a promising less invasive technique for the diagnosis of intracranial vascular lesions and hypervascular tumors. Similar to 4-dimensional computed tomographic angiography obtaining high frame rate images, TR MRA utilizes acceleration techniques to acquire sequential arterial and venous phase images for identifying, localizing, and classifying vascular lesions. Because of the good agreement with digital subtraction angiography for grading brain arteriovenous malformations with the Spetzler-Martin classification and the good sensitivity for visualizing arteriovenous fistulas, studies have suggested that TR MRA could serve as a screening or routine follow-up tool for diagnosing intracranial vascular disorders. In this pictorial essay, we report on the use of TR MRA at 3.0 T to diagnose intracranial vascular lesions and hypervascular tumors, employing DSA as the reference technique.

  17. Validity of computational hemodynamics in human arteries based on 3D time-of-flight MR angiography and 2D electrocardiogram gated phase contrast images

    NASA Astrophysics Data System (ADS)

    Yu, Huidan (Whitney); Chen, Xi; Chen, Rou; Wang, Zhiqiang; Lin, Chen; Kralik, Stephen; Zhao, Ye

    2015-11-01

    In this work, we demonstrate the validity of 4-D patient-specific computational hemodynamics (PSCH) based on 3-D time-of-flight (TOF) MR angiography (MRA) and 2-D electrocardiogram (ECG) gated phase contrast (PC) images. The mesoscale lattice Boltzmann method (LBM) is employed to segment morphological arterial geometry from TOF MRA, to extract velocity profiles from ECG PC images, and to simulate fluid dynamics on a unified GPU accelerated computational platform. Two healthy volunteers are recruited to participate in the study. For each volunteer, a 3-D high resolution TOF MRA image and 10 2-D ECG gated PC images are acquired to provide the morphological geometry and the time-varying flow velocity profiles for necessary inputs of the PSCH. Validation results will be presented through comparisons of LBM vs. 4D Flow Software for flow rates and LBM simulation vs. MRA measurement for blood flow velocity maps. Indiana University Health (IUH) Values Fund.

  18. Optical Coherence Tomography

    MedlinePlus

    ... Cardiac Magnetic Resonance Imaging (MRI and MRA) Computed Tomography (CT) Scan Diagnostic Tests and Procedures Echocardiography Electrocardiogram ... Ultrasound Nuclear Stress Test Nuclear Ventriculography Positron Emission Tomography (PET) Stress ... Optical Coherence Tomography | ...

  19. EVALUATION OF POLLUTION PREVENTION OPPORTUNITIES FOR MOLD RELEASE AGENTS

    EPA Science Inventory

    The report gives results of an assessment of the processes, materials, installation practices, and emission characteristics associated with the application of mold release agents (MRAs). Emissions were estimated based on available information on MRA composition and consumption. V...

  20. How Are Brain and Spinal Cord Tumors in Children Diagnosed?

    MedlinePlus

    ... spinal cord tumors in children staged? How are brain and spinal cord tumors diagnosed in children? Brain ... resonance angiography (MRA) or computerized tomographic angiography (CTA). Brain or spinal cord tumor biopsy Imaging tests such ...

  1. Lunotriquetral instability in a climber – case report and review

    PubMed Central

    Avrahami, Daniel

    2010-01-01

    Wrist injuries and carpal instability may result from various sport-related acitivites. Lunotriquetral instability (LTI) is an infrequently recognized cause of wrist pain in athletes. The diagnosis of LTI through history and physical examination can be confirmed by Magnetic Resonance Arthrogram (MRA). This case report describes a case of clinically suspected LTI confirmed by MRA. Relevant literature on lunotriquetral injuries is discussed. Lunotriquetral joint injury can present itself and should be considered within a differential diagnosis of a wrist injury. The diagnosis of LTI through clinical history and physical examination can be confirmed by MRA. This case report demonstrates the importance of MRA in the accurate diagnosis and management of a patient with wrist pain. PMID:21120017

  2. Diagnostic yield and accuracy of CT angiography, MR angiography, and digital subtraction angiography for detection of macrovascular causes of intracerebral haemorrhage: prospective, multicentre cohort study

    PubMed Central

    Velthuis, Birgitta K; Rinkel, Gabriël J E; Algra, Ale; de Kort, Gérard A P; Witkamp, Theo D; de Ridder, Johanna C M; van Nieuwenhuizen, Koen M; de Leeuw, Frank-Erik; Schonewille, Wouter J; de Kort, Paul L M; Dippel, Diederik W; Raaymakers, Theodora W M; Hofmeijer, Jeannette; Wermer, Marieke J H; Kerkhoff, Henk; Jellema, Korné; Bronner, Irene M; Remmers, Michel J M; Bienfait, Henri Paul; Witjes, Ron J G M; Greving, Jacoba P; Klijn, Catharina J M

    2015-01-01

    Study question What are the diagnostic yield and accuracy of early computed tomography (CT) angiography followed by magnetic resonance imaging/angiography (MRI/MRA) and digital subtraction angiography (DSA) in patients with non-traumatic intracerebral haemorrhage? Methods This prospective diagnostic study enrolled 298 adults (18-70 years) treated in 22 hospitals in the Netherlands over six years. CT angiography was performed within seven days of haemorrhage. If the result was negative, MRI/MRA was performed four to eight weeks later. DSA was performed when the CT angiography or MRI/MRA results were inconclusive or negative. The main outcome was a macrovascular cause, including arteriovenous malformation, aneurysm, dural arteriovenous fistula, and cavernoma. Three blinded neuroradiologists independently evaluated the images for macrovascular causes of haemorrhage. The reference standard was the best available evidence from all findings during one year’s follow-up. Study answer and limitations A macrovascular cause was identified in 69 patients (23%). 291 patients (98%) underwent CT angiography; 214 with a negative result underwent additional MRI/MRA and 97 with a negative result for both CT angiography and MRI/MRA underwent DSA. Early CT angiography detected 51 macrovascular causes (yield 17%, 95% confidence interval 13% to 22%). CT angiography with MRI/MRA identified two additional macrovascular causes (18%, 14% to 23%) and these modalities combined with DSA another 15 (23%, 18% to 28%). This last extensive strategy failed to detect a cavernoma, which was identified on MRI during follow-up (reference strategy). The positive predictive value of CT angiography was 72% (60% to 82%), of additional MRI/MRA was 35% (14% to 62%), and of additional DSA was 100% (75% to 100%). None of the patients experienced complications with CT angiography or MRI/MRA; 0.6% of patients who underwent DSA experienced permanent sequelae. Not all patients with negative CT angiography and

  3. The Prognostic Value of Plasma Galectin-3 in Chronic Heart Failure Patients Is Maintained when Treated with Mineralocorticoid Receptor Antagonists

    PubMed Central

    Koukoui, François; Desmoulin, Franck; Galinier, Michel; Barutaut, Manon; Caubère, Celine; Evaristi, Maria Francesca; Murat, Gurbuz; De Boer, Rudolf; Berry, Matthieu; Smih, Fatima; Rouet, Philippe

    2015-01-01

    Objective Galectin-3 (Gal-3) is considered as a myocardial fibrosis biomarker with prognostic value in heart failure (HF). Since aldosterone is a neurohormone with established fibrotic properties, we aimed to investigate if mineralocorticoid receptor antagonists (MRAs) would modulate the prognostic value of Gal-3. Methods The IBLOMAVED cohort comprised 427 eligible chronic HF patients (CHF) with echocardiography and heart failure biomarkers assessments (BNP). After propensity score matching CHF patients for cardiovascular risk factors, to form balanced groups, Gal-3 levels were measured at baseline in plasma from patients treated with MRAs (MRA-Plus, n=101) or not (MRA-Neg, n=101). The primary end point was all-cause mortality with a follow-up of 3 years. Results Gal-3 in plasma from these patients were similar with median values of 14.0 ng/mL [IQR, 9.9–19.3] and 14.4 ng/mL [IQR, 12.3–19.8] (P = 0.132) in MRA-Neg and MRA-Plus, respectively. Patients with Gal-3 ≤17.8 ng/mL had an HR of 1 (reference group) and 1.5 [0.4–5.7] in MRA-Neg and MRA-Plus, respectively (p=0.509). Patients with Gal-3 ≥ 17.8 ng/mL had an HR of 7.4 [2.2–24.6] and 9.0 [2.9–27.8] in MRA-Plus and MRA-Neg, respectively (p=0.539) and a median survival time of 2.4 years [95%CI,1.8–2.4]. Multivariate Cox proportional hazard analysis confirmed that MRA and the interaction term between MRA treatment and Gal-3 >17.8 ng/mL were not factors associated with survival. Conclusions MRA treatment did not impair the prognostic value of Gal-3 assessed with a 17.8 ng/mL cut off. Gal-3 levels maintained its strong prognostic value in CHF also in patients treated with MRAs. The significance of the observed lack of an interaction between Gal-3 and treatment effect of MRAs remains to be elucidated. PMID:25786035

  4. High spatial resolution time-resolved magnetic resonance angiography of lower extremity tumors at 3T: Comparison with computed tomography angiography.

    PubMed

    Wu, Gang; Jin, Teng; Li, Ting; Morelli, John; Li, Xiaoming

    2016-09-01

    The aim of this study was to compare diagnostic value of high spatial resolution time-resolved magnetic resonance angiography with interleaved stochastic trajectory (TWIST) using Gadobutrol to Computed tomography angiography (CTA) for preoperative evaluation of lower extremity tumors.This prospective study was approved by the institutional review board. Fifty consecutive patients (31 men, 19 women, age range 18-80 years, average age 42.7 years) with lower extremity tumors underwent TWIST magnetic resonance angiography (MRA) and CTA. Digital subtraction angiography was available for 8 patients. Image quality of MRA was compared with CTA by 2 radiologists according to a 4-point Likert scale. Arterial involvement by tumor was compared using kappa test between MRA and CTA. The ability to identify feeding arteries and arterio-venous fistulae (AVF) was compared using Wilcoxon signed rank test and McNemar test, respectively.Image quality of MRA and CTA was rated without a statistically significant difference (3.88 ± 0.37 vs. 3.97 ± 0.16, P = 0.135). Intramodality agreement was high for the identification of arterial invasion (kappa = 0.806 ± 0.073 for Reader 1, kappa = 0.805 ± 0.073 for Reader 2). Readers found AVF in 27 of 50 MRA cases and 14 of 50 CTA cases (P < 0.001). Mean feeding arteries identified with MRA were significantly more than that with CTA (2.08 ± 1.72 vs. 1.62 ± 1.52, P = .02).TWIST MRA is a reliable imaging modality for the assessment of lower extremity tumors. TWIST MRA is comparable to CTA for the identification of AVF and feeding arteries. PMID:27631262

  5. Incorporate Imaging Characteristics Into an Arteriovenous Malformation Radiosurgery Plan Evaluation Model

    SciTech Connect

    Zhang Pengpeng Wu, Leester; Liu Tian; Kutcher, Gerald J..; Isaacson, Steven

    2008-04-01

    Purpose: To integrate imaging performance characteristics, specifically sensitivity and specificity, of magnetic resonance angiography (MRA) and digital subtraction angiography (DSA) into arteriovenous malformation (AVM) radiosurgery planning and evaluation. Methods and Materials: Images of 10 patients with AVMs located in critical brain areas were analyzed in this retrospective planning study. The image findings were first used to estimate the sensitivity and specificity of MRA and DSA. Instead of accepting the imaging observation as a binary (yes or no) mapping of AVM location, our alternative is to translate the image into an AVM probability distribution map by incorporating imagers' sensitivity and specificity, and to use this map as a basis for planning and evaluation. Three sets of radiosurgery plans, targeting the MRA and DSA positive overlap, MRA positive, and DSA positive were optimized for best conformality. The AVM obliteration rate (ORAVM) and brain complication rate served as endpoints for plan comparison. Results: In our 10-patient study, the specificities and sensitivities of MRA and DSA were estimated to be (0.95, 0.74) and (0.71, 0.95), respectively. The positive overlap of MRA and DSA accounted for 67.8% {+-} 4.9% of the estimated true AVM volume. Compared with plans targeting MRA and DSA-positive overlap, plans targeting MRA-positive or DSA-positive improved ORAVM by 4.1% {+-} 1.9% and 15.7% {+-} 8.3%, while also increasing the complication rate by 1.0% {+-} 0.8% and 4.4% {+-} 2.3%, respectively. Conclusions: The impact of imagers' quality should be quantified and incorporated in AVM radiosurgery planning and evaluation to facilitate clinical decision making.

  6. Modified CHROMagar Acinetobacter Medium for Direct Detection of Multidrug-Resistant Acinetobacter Strains in Nasal and Rectal Swab Samples

    PubMed Central

    Lee, Jacob; Kim, Taek-Kyung; Park, Min-Jeong; Kim, Han-Sung; Kim, Jae-Seok

    2013-01-01

    This study aimed to investigate whether CHROMagar Acinetobacter medium (CHROMagar, France) in combination with an antimicrobial supplement (modified CHROMagar Acinetobacter; CHROMagar, France) can be used for detecting and isolating multidrug-resistant Acinetobacter species (MRA) in nasal and rectal surveillance cultures. Nasal and rectal swab samples were collected from patients in an intensive care unit at a teaching hospital. The samples were used to inoculate modified CHROMagar Acinetobacter plates, which were examined after 24 and 48 hr of incubation at 37℃. Their susceptibility against the antimicrobial agents meropenem, imipenem, ciprofloxacin, and amikacin was analyzed using the Etest (bioMerieux, France). A total of 406 paired samples (406 nasal swabs and 406 rectal swabs) were obtained from 226 patients, and 120 samples (28 nasal and 28 rectal cultures, 47 nasal cultures only, and 17 rectal cultures only) yielded MRA. Seventy-five MRA isolates (18.5%) were recovered from the 406 nasal samples, and 45 MRA isolates (11.1%) were recovered from the 406 rectal samples. Of the 120 MRA isolates, 3 (2.5%) were detected only after 48 hr of incubation. The use of modified CHROMagar Acinetobacter together with nasal and rectal swabs and 1-day incubation is an effective surveillance tool for detecting MRA colonization. PMID:23667846

  7. Examining the feasibility of mixture risk assessment: A case study using a tiered approach with data of 67 pesticides from the Joint FAO/WHO Meeting on Pesticide Residues (JMPR).

    PubMed

    Evans, Richard M; Scholze, Martin; Kortenkamp, Andreas

    2015-10-01

    The way in which mixture risk assessment (MRA) should be included in chemical risk assessment is a current topic of debate. We used data from 67 recent pesticide evaluations to build a case study using Hazard Index calculations to form risk estimates in a tiered MRA approach in line with a Framework proposed by WHO/IPCS. The case study is used to illustrate the approach and to add detail to the existing Framework, and includes many more chemicals than previous case studies. A low-tier MRA identified risk as being greater than acceptable, but refining risk estimates in higher tiers was not possible due to data requirements not being readily met. Our analysis identifies data requirements, which typically expand dramatically in higher tiers, as being the likely cause for an MRA to fail in many realistic cases. This forms a major obstacle to routine implementation of MRA and shows the need for systematic generation and collection of toxicological data. In low tiers, hazard quotient inspection identifies chemicals that contribute most to the HI value and thus require attention if further refinement is needed. Implementing MRA requires consensus on issues such as scope setting, criteria for performing refinement, and decision criteria for actions.

  8. Failing Hemodialysis Arteriovenous Fistula and Percutaneous Treatment: Imaging with CT, MRI and Digital Subtraction Angiography

    SciTech Connect

    Cavagna, Enrico; D'Andrea, Paolo; Schiavon, Francesco; Tarroni, Giovanni

    2000-07-15

    Purpose: To evaluate failing hemodialysis arteriovenous fistulas with helical CT angiography (CTA), MR angiography (MRA), and digital subtraction angiography (DSA), and to compare the efficacy of the three techniques in detecting the number, location, grade, and extent of stenoses and in assessing the technical results of percutaneous transluminal angioplasty (PTA) and stenting.Methods: Thirteen patients with Brescia-Cimino arteriovenous fistula malfunction underwent MRA and CTA of the fistula and, within 1 week, DSA. A total of 11 PTAs were performed; in three cases an MR-compatible stent was placed. DSA served as the gold standard for comparison in all patients. The presence, site, and number of stenoses or occlusions and the technical results of percutaneous procedures were assessed with DSA, CTA, and MRA.Results: MRA underestimated a single stenosis in one patient; CTA and MRA did not overestimate any stenosis. Significant artifacts related to stent geometry and/or underlying metal were seen in MRA sequences in two cases.Conclusions: CT and MRI can provide information regarding the degree of vascular impairment, helping to stratify patients into those who can have PTA (single or multiple stenoses) versus those who require an operative procedure (occlusion). Conventional angiography can be reserved for candidates for percutaneous intervention.

  9. Magnetic Resonance Angiography of the Peripheral Vessels in Patients with Peripheral Arterial Occlusive Disease: When Is an Additional Conventional Angiography Required?

    SciTech Connect

    Janka, R. Wenkel, E.; Fellner, C.; Lang, W.; Bautz, W.; Uder, M.

    2006-04-15

    The purpose of this work was to find out how often the clinician asks for a conventional angiography (CA) in patients with peripheral arterial occlusive disease (PAOD) after a magnetic resonance angiography (MRA) has been performed and how often the CA reveals additional information for therapy planning. Quality criteria for the MRA were defined and tested to see whether they can predict the need for an additional CA. In this prospective study, 81 patients suffering from PAOD (Fontaine classification IIa, n = 13; IIb, n = 33; III, n = 10; IV, n = 25) were examined with a 1.5-T MR-scanner with dedicated coils using a step-by-step technique. The vascular surgeon decided whether he could plan the therapy on the basis of the MRA or if he needed an additional CA. The MRA was assessed in terms of the image quality of the MRA and regarding therapeutic management of the patient in a two-grade scale: sufficient and insufficient. In 27/81 (33%) patients, the clinician asked for a CA, which revealed new information in only 11 patients. The relative number of MRAs with insufficient image quality was significantly higher (p < 0.01) in the group with additional information on CA (8/11) compared to the group without additional information (0/16). The assessment of an MRA based on image quality and regarding therapeutic management of the patient might reduce the number of CAs for therapy planning in patients with PAOD.

  10. Contrast enhanced pulmonary magnetic resonance angiography for pulmonary embolism: Building a successful program.

    PubMed

    Nagle, Scott K; Schiebler, Mark L; Repplinger, Michael D; François, Christopher J; Vigen, Karl K; Yarlagadda, Rajkumar; Grist, Thomas M; Reeder, Scott B

    2016-03-01

    The performance of contrast enhanced pulmonary magnetic resonance angiography (MRA) for the diagnosis of pulmonary embolism (PE) is an effective non-ionizing alternative to contrast enhanced computed tomography and nuclear medicine ventilation/perfusion scanning. However, the technical success of these exams is very dependent on careful attention to the details of the MRA acquisition protocol and requires reader familiarity with MRI and its artifacts. Most practicing radiologists are very comfortable with the performance and interpretation of computed tomographic angiography (CTA) performed to detect pulmonary embolism but not all are as comfortable with the use of MRA in this setting. The purpose of this review is to provide the general radiologist with the tools necessary to build a successful pulmonary embolism MRA program. This review will cover in detail image acquisition, image interpretation, and some key elements of outreach that help to frame the role of MRA to consulting clinicians and hospital administrators. It is our aim that this resource will help build successful clinical pulmonary embolism MRA programs that are well received by patients and physicians, reduce the burden of medical imaging radiation, and maintain good patient outcomes. PMID:26860667

  11. Magnetic Resonance Angiography of Uterine Artery: Changes with Embolization Using Gelatin Sponge Particles Alone for Fibroids

    SciTech Connect

    Katsumori, Tetsuya Kasahara, Toshiyuki; Kin, Yoko; Ichihashi, Shigeo

    2007-06-15

    Purpose. To assess uterine artery recanalization, together with tumor devascularization, after embolization using gelatin sponge particles alone for fibroids. Methods. Twenty-seven patients underwent uterine artery embolization (UAE) for fibroids using only gelatin sponge particles. The angiographic endpoint of embolization was defined as near stasis of contrast medium in the ascending segment of the uterine artery. All patients underwent contrast-enhanced magnetic resonance angiography (MRA) before and 4 months after UAE, and contrast-enhanced magnetic resonance imaging (CE-MRI) before, 1 week after, and 4 months after UAE. The visualization of the uterine arteries before and 4 months after UAE was assessed using MRA. The infarction rates of the largest tumor were assessed using CE-MRI 1 week after UAE. Results. MRA 4 months after UAE showed 100% (53/53) of the descending and transverse segments, and 88% (43/49) of the ascending segments that had been noted on baseline MRA. The visualization of the ascending segments on MRA 4 months after UAE was identical to that on baseline MRA in 20 of 27 patients (74%). CE-MRI showed complete infarction of the largest tumor in 22 of 27 patients (81%), and 90-99% infarction of the largest tumor in the remaining 5 of 27 patients (19%). Conclusion. Based on the MR study, in most cases uterine artery recanalization occurred, together with sufficient devascularization of fibroids, after UAE using gelatin sponge particles alone.

  12. The effect of Mycoplasma and mycoplasma removal agent on the hydrolase activity in fibroblasts of patients with lysosomal diseases.

    PubMed

    Souza, F T S; Sostruznik, L S; Scolari, R C; Castro, K J M; Andrade, C V; Giugliani, R; Coelho, J C

    2010-01-01

    This study was designed to evaluate the effect of mycoplasma contamination on acid hydrolase activity and the action of the mycoplasma removal agent (MRA), in cultures of human fibroblasts from individuals with lysosomal diseases. For this purpose, we measured the activity of the b-galactosidase, arylsulphatase B (ASB), hexosaminidase A and a-glucosidase enzymes. The activity of the above mentioned enzymes in fibroblasts contaminated by mycoplasma was measured before and after the addition of the MRA. The results were then compared to the enzymatic activity in contamination-free cultures. Only the ASB enzyme showed significant alteration in activity both in the presence of mycoplasma and MRA. The remaining enzymes did not suffer significant interference by the presence of the two agents. Of the four enzymes tested, three did not suffer significant alterations by the presence of the mycoplasma nor from the MRA. However, the activity measured in the ASB enzyme increased significantly in the presence of mycoplasma and MRA and could lead to a doubtful diagnosis. Therefore, we suggest that contamination should be prevented by using aseptic techniques as well as the MRA in those fibroblast cultures that cannot be discarded.

  13. Highly porous activated carbons prepared from carbon rich Mongolian anthracite by direct NaOH activation

    NASA Astrophysics Data System (ADS)

    Byamba-Ochir, Narandalai; Shim, Wang Geun; Balathanigaimani, M. S.; Moon, Hee

    2016-08-01

    Highly porous activated carbons (ACs) were prepared from Mongolian raw anthracite (MRA) using sodium hydroxide as an activation agent by varying the mass ratio (powdered MRA/NaOH) as well as the mixing method of chemical agent and powdered MRA. The specific BET surface area and total pore volume of the prepared MRA-based activated carbons (MACs) are in the range of 816-2063 m2/g and of 0.55-1.61 cm3/g, respectively. The pore size distribution of MACs show that most of the pores are in the range from large micropores to small mesopores and their distribution can be controlled by the mass ratio and mixing method of the activating agent. As expected from the intrinsic property of the MRA, the highly graphitic surface morphology of prepared carbons was confirmed from Raman spectra and transmission electron microscopy (TEM) studies. Furthermore the FTIR and XPS results reveal that the preparation of MACs with hydrophobic in nature is highly possible by controlling the mixing conditions of activating agent and powdered MRA. Based on all the results, it is suggested that the prepared MACs could be used for many specific applications, requiring high surface area, optimal pore size distribution, proper surface hydrophobicity as well as strong physical strength.

  14. Role of Elastin in Spontaneously Hypertensive Rat Small Mesenteric Artery Remodelling

    PubMed Central

    Briones, Ana M; González, José M; Somoza, Beatriz; Giraldo, Jesús; Daly, Craig J; Vila, Elisabet; Carmen González, M; McGrath, John C; Arribas, Silvia M

    2003-01-01

    Chronic hypertension is associated with resistance artery remodelling and mechanical alterations. However, the contribution of elastin has not been thoroughly studied. Our objective was to evaluate the role of elastin in vascular remodelling of mesenteric resistance arteries (MRA) from spontaneously hypertensive rats (SHR). MRA segments from Wistar Kyoto rats (WKY) and SHR were pressurised under passive conditions at a range of physiological pressures with pressure myography. Confocal microscopy was used to determine differences in the quantity and organisation of elastin in intact pressure-fixed arteries. To assess the contribution of elastin to MRA structure and mechanics, myograph-mounted vessels were studied before and after elastase incubation. When compared with WKY, MRA from SHR showed: (1) a smaller lumen, (2) decreased distensibility at low pressures, (3) a leftward shift of the stress-strain relationship, (4) redistribution of elastin within the internal elastic lamina (IEL) leading to smaller fenestrae but no change in fenestrae number or elastin amount. Elastase incubation (1) fragmented the structure of IEL in a concentration-dependent fashion, (2) abolished all the structural and mechanical differences between strains, and (3) decreased distensibility at low pressures. The study shows the overriding role of elastin in determining vascular dimensions and mechanical properties in a resistance artery. In addition, it informs hypertensive remodelling. MRA remodelling and increased stiffness are accompanied by elastin restructuring within the IEL and elastin degradation reverses structural and mechanical alterations of SHR MRA. Differences in elastin organisation are, therefore, a central element in small artery remodelling in hypertension. PMID:12844513

  15. Multimodality Imaging of Carotid Stenosis

    PubMed Central

    Adla, Theodor; Adlova, Radka

    2015-01-01

    Four diagnostic modalities are used to image the following internal carotid artery: digital subtraction angiography (DSA), duplex ultrasound (DUS), computed tomography angiography (CTA), and magnetic resonance angiography (MRA). The aim of this article is to describe the potentials of these techniques and to discuss their advantages and disadvantages. Invasive DSA is still considered the gold standard and is an indivisible part of the carotid stenting procedure. DUS is an inexpensive but operator-dependent tool with limited visibility of the carotid artery course. Conversely, CTA and MRA allow assessment of the carotid artery from the aortic arch to intracranial parts. The disadvantages of CTA are radiation and iodine contrast medium administration. MRA is without radiation but contrast-enhanced MRA is more accurate than noncontrast MRA. The choice of methods depends on the clinical indications and the availability of methods in individual centers. However, the general approach to patient with suspected carotid artery stenosis is to first perform DUS and then other noninvasive methods such as CTA, MRA, or transcranial Doppler US. PMID:26417185

  16. Planning Evaluation of C-Arm Cone Beam CT Angiography for Target Delineation in Stereotactic Radiation Surgery of Brain Arteriovenous Malformations

    SciTech Connect

    Kang, Jun; Huang, Judy; Gailloud, Philippe; Rigamonti, Daniele; Lim, Michael; Bernard, Vincent; Ehtiati, Tina; Ford, Eric C.

    2014-10-01

    Purpose: Stereotactic radiation surgery (SRS) is one of the therapeutic modalities currently available to treat cerebral arteriovenous malformations (AVM). Conventionally, magnetic resonance imaging (MRI) and MR angiography (MRA) and digital subtraction angiography (DSA) are used in combination to identify the target volume for SRS treatment. The purpose of this study was to evaluate the use of C-arm cone beam computed tomography (CBCT) in the treatment planning of SRS for cerebral AVMs. Methods and Materials: Sixteen consecutive patients treated for brain AVMs at our institution were included in this retrospective study. Prior to treatment, all patients underwent MRA, DSA, and C-arm CBCT. All images were coregistered using the GammaPlan planning system. AVM regions were delineated independently by 2 physicians using either C-arm CBCT or MRA, resulting in 2 volumes: a CBCT volume (VCBCT) and an MRA volume (V{sub MRA}). SRS plans were generated based on the delineated regions. Results: The average volume of treatment targets delineated using C-arm CBCT and MRA were similar, 6.40 cm{sup 3} and 6.98 cm{sup 3}, respectively (P=.82). However, significant regions of nonoverlap existed. On average, the overlap of the MRA with the C-arm CBCT was only 52.8% of the total volume. In most cases, radiation plans based on V{sub MRA} did not provide adequate dose to the region identified on C-arm CBCT; the mean minimum dose to V{sub CBCT} was 29.5%, whereas the intended goal was 45% (P<.001). The mean volume of normal brain receiving 12 Gy or more in C-arm CBCT-based plans was not greater than in the MRA-based plans. Conclusions: Use of C-arm CBCT images significantly alters the delineated regions of AVMs for SRS planning, compared to that of MRA/MRI images. CT-based planning can be accomplished without increasing the dose to normal brain and may represent a more accurate definition of the nidus, increasing the chances for successful obliteration.

  17. Whole-Body Magnetic Resonance Angiography at 3 Tesla Using a Hybrid Protocol in Patients with Peripheral Arterial Disease

    SciTech Connect

    Nielsen, Yousef W.; Eiberg, Jonas P.; Logager, Vibeke B.; Schroeder, Torben V.; Just, Sven; Thomsen, Henrik S.

    2009-09-15

    The purpose of this study was to determine the diagnostic performance of 3T whole-body magnetic resonance angiography (WB-MRA) using a hybrid protocol in comparison with a standard protocol in patients with peripheral arterial disease (PAD). In 26 consecutive patients with PAD two different protocols were used for WB-MRA: a standard sequential protocol (n = 13) and a hybrid protocol (n = 13). WB-MRA was performed using a gradient echo sequence, body coil for signal reception, and gadoterate meglumine as contrast agent (0.3 mmol/kg body weight). Two blinded observers evaluated all WB-MRA examinations with regard to presence of stenoses, as well as diagnostic quality and degree of venous contamination in each of the four stations used in WB-MRA. Digital subtraction angiography served as the method of reference. Sensitivity for detecting significant arterial disease (luminal narrowing {>=} 50%) using standard-protocol WB-MRA for the two observers was 0.63 (95%CI: 0.51-0.73) and 0.66 (0.58-0.78). Specificities were 0.94 (0.91-0.97) and 0.96 (0.92-0.98), respectively. In the hybrid protocol WB-MRA sensitivities were 0.75 (0.64-0.84) and 0.70 (0.58-0.8), respectively. Specificities were 0.93 (0.88-0.96) and 0.95 (0.91-0.97). Interobserver agreement was good using both the standard and the hybrid protocol, with {kappa} = 0.62 (0.44-0.67) and {kappa} = 0.70 (0.59-0.79), respectively. WB-MRA quality scores were significantly higher in the lower leg using the hybrid protocol compared to standard protocol (p = 0.003 and p = 0.03, observers 1 and 2). Distal venous contamination scores were significantly lower with the hybrid protocol (p = 0.02 and p = 0.01, observers 1 and 2). In conclusion, hybrid-protocol WB-MRA shows a better diagnostic performance than standard protocol WB-MRA at 3 T in patients with PAD.

  18. Fusion Guidance in Endovascular Peripheral Artery Interventions: A Feasibility Study

    SciTech Connect

    Sailer, Anna M. Haan, Michiel W. de Graaf, Rick de Zwam, Willem H. van; Schurink, Geert Willem H.; Nelemans, Patricia J.; Wildberger, Joachim E. Das, Marco

    2015-04-15

    PurposeThis study was designed to evaluate the feasibility of endovascular guidance by means of live fluoroscopy fusion with magnetic resonance angiography (MRA) and computed tomography angiography (CTA).MethodsFusion guidance was evaluated in 20 endovascular peripheral artery interventions in 17 patients. Fifteen patients had received preinterventional diagnostic MRA and two patients had undergone CTA. Time for fluoroscopy with MRA/CTA coregistration was recorded. Feasibility of fusion guidance was evaluated according to the following criteria: for every procedure the executing interventional radiologists recorded whether 3D road-mapping provided added value (yes vs. no) and whether PTA and/or stenting could be performed relying on the fusion road-map without need for diagnostic contrast-enhanced angiogram series (CEAS) (yes vs. no). Precision of the fusion road-map was evaluated by recording maximum differences between the position of the vasculature on the virtual CTA/MRA images and conventional angiography.ResultsAverage time needed for image coregistration was 5 ± 2 min. Three-dimensional road-map added value was experienced in 15 procedures in 12 patients. In half of the patients (8/17), intervention was performed relying on the fusion road-map only, without diagnostic CEAS. In two patients, MRA roadmap showed a false-positive lesion. Excluding three patients with inordinate movements, mean difference in position of vasculature on angiography and MRA/CTA road-map was 1.86 ± 0.95 mm, implying that approximately 95 % of differences were between 0 and 3.72 mm (2 ± 1.96 standard deviation).ConclusionsFluoroscopy with MRA/CTA fusion guidance for peripheral artery interventions is feasible. By reducing the number of CEAS, this technology may contribute to enhance procedural safety.

  19. Mineralocorticoid Receptor Antagonist Use in Hospitalized Patients with Heart Failure, Reduced Ejection Fraction, and Diabetes Mellitus (from the EVEREST Trial)

    PubMed Central

    Vaduganathan, Muthiah; Cas, Alessandra Dei; Mentz, Robert J.; Greene, Stephen J.; Khan, Sadiya; Subacius, Haris P.; Chioncel, Ovidiu; Maggioni, Aldo P.; Konstam, Marvin A.; Senni, Michele; Fonarow, Gregg C.; Butler, Javed; Gheorghiade, Mihai

    2014-01-01

    Despite the well-established benefits of mineralocorticoid receptor agonists (MRAs) in heart failure with reduced ejection fraction, safety concerns remain in patients with concomitant diabetes mellitus (DM) because of common renal and electrolyte abnormalities in this population. We analyzed all-cause mortality and composite cardiovascular mortality and HF hospitalization over a median 9.9 months among 1,998 patients in the placebo arm of the Efficacy of Vasopressin Antagonism in Heart Failure Outcome Study With Tolvaptan (EVEREST) trial by DM status and discharge MRA use. Of the 750 patients with DM, 59.2% were receiving MRAs compared with 62.5% in the non-DM patients. DM patients not receiving MRAs were older, more likely to be men, with an ischemic heart failure etiology and slightly worse renal function compared with those receiving MRAs. After adjustment for baseline risk factors, among DM patients, MRA use was not associated with either mortality (hazard ratio [HR] 0.93; 95% confidence interval [CI] 0.75 to 1.15) or the composite end point (HR 0.94; 95% CI 0.80 to 1.10). Similar findings were seen in non-DM patients (mortality [HR 1.01; 95% CI 0.84 to 1.22] or the composite end point [HR 0.98; 95% CI 0.85 to 1.13] [p >0.43 for DM interaction]). In conclusion, in-hospital initiation of MRA therapy was low (15% to 20%), and overall discharge MRA use was only 60% (with regional variation), regardless of DM status. There does not appear to be clear, clinically significant in-hospital hemodynamic or even renal differences between those on and off MRA. Discharge MRA use was not associated with postdischarge end points in patients hospitalized for worsening heart failure with reduced ejection fraction and co-morbid DM. DM does not appear to influence the effectiveness of MRA therapy. PMID:25060414

  20. Ouabain-induced hypertension alters the participation of endothelial factors in α-adrenergic responses differently in rat resistance and conductance mesenteric arteries

    PubMed Central

    Xavier, Fabiano E; Rossoni, Luciana V; Alonso, María J; Balfagón, Gloria; Vassallo, Dalton V; Salaices, Mercedes

    2004-01-01

    This study compares the role of endothelial factors in α-adrenoceptor contractile responses in mesenteric resistance (MRA) and superior (SMA) mesenteric arteries from ouabain-treated (8.0 μg day−1, 5 weeks) and untreated rats. The role of the renin–angiotensin system was also evaluated. Ouabain treatment increased systolic blood pressure. In addition, ouabain reduced the phenylephrine response in SMA but did not alter noradrenaline responses in MRA. Endothelium removal or the nitric oxide synthase (NOS) inhibitor (L-NAME, 100 μM) increased the responses to α-adrenergic agonists in both vessels. After ouabain treatment, both endothelial modulation and the L-NAME effect were increased in SMA, while only the L-NAME effect was increased in MRA. Endothelial NOS expression remained unaltered after ouabain treatment. Indomethacin (10 μM) similarly reduced the noradrenaline contraction in MRA from both groups; in contrast, in SMA, indomethacin only reduced phenylephrine-induced contractions in segments from untreated rats. Co-incubation of L-NAME and indomethacin leftward shifted the concentration–response curves for noradrenaline more in MRA from ouabain-treated rats; tetraethylammonium (2 mM) shifted the noradrenaline curves further leftward only in MRA from untreated rats. Losartan treatment prevents the development of hypertension but not all vascular changes observed after ouabain treatment. In conclusion, a rise in endothelial NO and impaired prostanoid participation might explain the reduction in phenylephrine-induced contraction in SMA after ouabain treatment. An increase in the modulatory effect of endothelial NO and impairment of endothelium-dependent hyperpolarizing factor effect might explain why the ouabain treatment had no effect on noradrenaline responses in MRA. PMID:15302685

  1. A unified hydrogeological conceptual model of the Milk River transboundary aquifer, traversing Alberta (Canada) and Montana (USA)

    NASA Astrophysics Data System (ADS)

    Pétré, Marie-Amélie; Rivera, Alfonso; Lefebvre, René; Hendry, M. Jim; Folnagy, Attila J. B.

    2016-06-01

    A conceptual model of the transboundary Milk River Aquifer (MRA), extending across the Canada-USA border, was developed based on literature, focused fieldwork and a three-dimensional geological model. The MRA corresponds to the Virgelle Member of the Milk River Formation (Eagle Formation in Montana, USA) and it is an important groundwater resource over a large area (25,000 km2). The Virgelle outcrops near the international border and along the Sweet Grass Arch in Montana. The down-gradient limit of the MRA is the unconformity separating the Virgelle from the gas-bearing sandy shale of the Alderson Member. The MRA is confined above by the Pakowki/Claggett Formations aquitards and below by the Colorado Group aquitard. The MRA contains higher transmissivity areas resulting in preferential flowpaths, confirmed by natural geochemical tracers. Tritium and 14C delineate restricted recharge areas along the outcrops on both sides of the international border. Drastic decreases in horizontal hydraulic gradients indicate that the Milk River intercepts a large proportion of groundwater flowing to the north from the recharge area. Downgradient of the Milk River, groundwater movement is slow, as shown by 36Cl residence times exceeding 1 Ma. These slow velocities imply that groundwater discharge downgradient of the Milk River is via vertical leakage through the Colorado Group and upward along buried valleys, which act as drains and correspond to artesian areas. When confined, the MRA contains a fossil groundwater resource, not significantly renewed by modern recharge. Groundwater exploitation thus far exceeds recharge, a situation requiring properly managed MRA groundwater depletion.

  2. The eye of the beholder: Can patterns in eye movement reveal aptitudes for spatial reasoning?

    PubMed

    Roach, Victoria A; Fraser, Graham M; Kryklywy, James H; Mitchell, Derek G V; Wilson, Timothy D

    2016-07-01

    Mental rotation ability (MRA) is linked to academic success in the spatially complex Science, Technology, Engineering, Medicine, and Mathematics (STEMM) disciplines, and anatomical sciences. Mental rotation literature suggests that MRA may manifest in the movement of the eyes. Quantification of eye movement data may serve to distinguish MRA across individuals, and serve as a consideration when designing visualizations for instruction. It is hypothesized that high-MRA individuals will demonstrate fewer eye fixations, conduct shorter average fixation durations (AFD), and demonstrate shorter response times, than low-MRA individuals. Additionally, individuals with different levels of MRA will attend to different features of the block-figures presented in the electronic mental rotations test (EMRT). All participants (n = 23) completed the EMRT while metrics of eye movement were collected. The test required participants view pairs of three-dimensional (3D) shapes, and identify if the pair is rotated but identical, or two different structures. Temporal analysis revealed no significant correlations between response time, average fixation durations, or number of fixations and mental rotation ability. Further analysis of within-participant variability yielded a significant correlation for response time variability, but no correlation between AFD variability and variability in the number of fixations. Additional analysis of salience revealed that during problem solving, individuals of differing MRA attended to different features of the block images; suggesting that eye movements directed at salient features may contribute to differences in mental rotations ability, and may ultimately serve to predict success in anatomy. Anat Sci Educ 9: 357-366. © 2015 American Association of Anatomists. PMID:26599398

  3. Blood Pool Contrast-enhanced Magnetic Resonance Angiography with Correlation to Digital Subtraction Angiography: A Pictorial Review.

    PubMed

    Knuttinen, Martha-Grace; Karow, Jillian; Mar, Winnie; Golden, Margaret; Xie, Karen L

    2014-01-01

    Magnetic resonance angiography (MRA) provides noninvasive visualization of the vascular supply of soft tissue masses and vascular pathology, without harmful radiation. This is important for planning an endovascular intervention, and helps to evaluate the efficiency and effectiveness of the treatment. MRA with conventional extracellular contrast agents relies on accurate contrast bolus timing, limiting the imaging window to first-pass arterial phase. The recently introduced blood pool contrast agent (BPCA), gadofosveset trisodium, reversibly binds to human serum albumin, resulting in increased T1 relaxivity and prolonged intravascular retention time, permitting both first-pass and steady-state phase high-resolution imaging. In our practice, high-quality MRA serves as a detailed "roadmap" for the needed endovascular intervention. Cases of aortoiliac occlusive disease, inferior vena cava thrombus, pelvic congestion syndrome, and lower extremity arteriovenous malformation are discussed in this article. MRA was acquired at 1.5 T with an 8-channel phased array coil after intravenous administration of gadofosveset (0.03 mmol/kg body weight), at the first-pass phase. In the steady-state, serial T1-weighted 3D spoiled gradient echo images were obtained with high resolution. All patients underwent digital subtraction angiography (DSA) and endovascular treatment. MRA and DSA findings of vascular anatomy and pathology are discussed and correlated. BPCA-enhanced MRA provides high-quality first-pass and steady-state vascular imaging. This could increase the diagnostic accuracy and create a detailed map for pre-intervention planning. Understanding the pharmacokinetics of BPCA and being familiar with the indications and technique of MRA are important for diagnosis and endovascular intervention. PMID:25558430

  4. Delineation of brain AVMs on MR-Angiography for the purpose of stereotactic radiosurgery

    SciTech Connect

    Buis, Dennis R. . E-mail: dr.buis@vumc.nl; Lagerwaard, Frank J.; Dirven, Clemens M.F.; Barkhof, Frederik; Knol, Dirk L.; Berg, Rene van den; Slotman, Ben J.; Vandertop, W. Peter

    2007-01-01

    Purpose: To assess the dosimetric consequences of brain arteriovenous malformation (bAVM) delineation on magnetic resonance angiography (MRA) for the purpose of stereotactic radiosurgery. Methods and Materials: Three observers contoured a bAVM in 20 patients, using digital subtraction angiography (V{sub DSA}) and three-dimensional time-of-flight MRA (V{sub MRA}). Displacement between contours was calculated. Agreement and differences between observers and imaging modalities were assessed. A standardized treatment plan with dynamic conformal arcs was generated and dosimetric coverage of all contours and the volume of normal brain tissue within the high dose region was determined. Results: The generalized reliability coefficient was 'fair' for target volume (0.79), but 'poor' for displacement (0.35). V{sub MRA} was larger than V{sub DSA} (5.0 vs. 4.0 mL, p = 0.001). No difference in displacement was found (2.8 vs. 2.5 mm, p = 0.156). Dosimetric coverage of V{sub MRA} was 62.9% (95% CI, 56.9-68.8) when V{sub DSA} was used as planning target volume, and coverage of V{sub DSA} was 83.5% (95% CI, 78.1-88.8) when V{sub MRA} was used for planning (p < 0.001). The mean volume of normal brain within the 80% isodose was larger when the bAVM was delineated on MRA (0.7 vs. 1.0 mL (p = 0.02) for targets {<=}3 mL and 3.7 vs. 7.0 mL (p = 0.01) for targets >3 mL). Conclusions: Brain arteriovenous malformations delineated on MRA are larger and more randomly displaced. However, for bAVMs {<=}3 mL, the difference in volume of normal brain tissue within the high-dose region does not seem to be clinically relevant. Therefore, MRA-images might be used as the sole imaging modality for the radiosurgical treatment of bAVMs {<=}3 mL when the bAVM is located in a noneloquent position.

  5. Preoperative evaluation of renal artery in patients with renal tumor

    PubMed Central

    Zhu, Liangsong; Wu, Guangyu; Wang, Jianfeng; Huang, Jiwei; Kong, Wen; Chen, Yonghui; Xue, Wei; Huang, Yiran; Zhang, Jin

    2016-01-01

    Abstract To investigate the feasibility of the noncontrast-enhanced magnetic resonance angiography (NCE-MRA) to evaluate renal arteries before partial nephrectomy (PN). Retrospective analyzed 479 patients who underwent renal surgery between January 2013 and December 2015 with NCE-MRA or computed tomographic angiography (CTA) renal artery image reconstruction preoperative in our department. The renal artery reconstruction score (RARS) was based on the level of artery visualization in a 4-class criterion, and the R.E.N.A.L nephrometry score (R.E.N.A.L), arterial based complexity (ABC) were also analyzed. Of the 479 patients, the overall-lever RARS was 3.62, and the average in 2 groups was no significant difference (NCE-MRA vs CTA, P = 0.072). The performance of NCE-MRA in PN group was similar with CTA. Further comparison demonstrated that the efficiency of NCE-MRA in moderate- or low-degree tumor according to the R.E.N.A.L and ABC complexity less than 3S was equal to CTA. However, high degree (P < 0.001), 3S (P = 0.027), or 3H (P < 0.001) would affect the imaging of renal artery. Intragroup analysis showed that tumor complexity such as max tumor size (r = −o.351, P < 0.001), R.E.N.A.L (r = −0.439, P < 0.001), and ABC (r = −0.619, P < 0.001) were closely correlated with the NCE-MRA performance. The images of 2 sides of the kidney were compared in single person as well, which was meaningful for NCE-MRA patients only (NCE-MRA, P < 0.001; CTA, P = 0.182). The renal artery reconstruction performed by NCE-MRA is feasible and has a similar achievement in the PN potential recipients, with a lower side effect, and meets the requirements for making surgical decision. It has a broad application prospect in clinical practice; however, it still needs to further improve the ability in more complex tumors. PMID:27759632

  6. [Fusion imaging of 3D MR cisternography/angiography for differential diagnosis of internal carotid-posterior communicating artery aneurysms and infundibular dilations].

    PubMed

    Satoh, Toru; Sasahara, Wataru; Omi, Megumi; Ohsako, Chika

    2006-05-01

    By using a fusion imaging of three-dimensional (3D) magnetic resonance cisternography (MRC) and coregistered magnetic resonance angiography (MRA), protrusions at the bifurcation of the internal carotid-posterior communication artery, detected by MRA, were investigated to differentiate between the infundibular dilations and aneurysms. The MRA, obtained by the 3D time-of-flight sequence, showed the flow-related arterial structures by means of an inflow effect mainly induced by the peak systolic flow velocity. The MRC, obtained by 3D fast spin-echo sequence, depicted the contours of the vascular structures within the cisternal space in contrast to the surrounding cerebrospinal fluid. Fusion images of 3D MRC/MRA showed the anatomy of protrusions from the different viewpoints with flow-related intraluminal images (MRA) in conjunction with outer-wall configuration images of the vascular structures (MRC). This imaging technique may be useful to differentiate the infundibular dilations from the internal carotid-posterior communicating artery aneurysms.

  7. Long term outcome of Aldosteronism after target treatments

    PubMed Central

    Wu, Vin-Cent; Wang, Shuo-Meng; Chang, Chia-Hui; Hu, Ya-Hui; Lin, Lian-Yu; Lin, Yen-Hung; Chueh, Shih-Chieh Jeff; Chen, Likwang; Wu, Kwan-Dun

    2016-01-01

    There exists a great knowledge gap in terms of long-term effects of various surgical and pharmacological treatments on outcomes among primary aldosteronism (PA) patients. Using a validated algorithm, we extracted longitudinal data for all PA patients diagnosed in 1997–2010 and treated in the Taiwan National Health Insurance. We identified 3362 PA patients for whom the mean length of follow-up was 5.75 years. PA has higher major cardiovascular events (MACE) than essential hypertension (23.3% vs 19.3%, p = 0.015). Results from the Cox model suggest a strong effect of adrenalectomy on lowering mortality (HR = 0.23 with residual hypertension and 0.21 with resolved hypertension). While need for receptor antagonist (MRA) MRA after diagnosis suggests that a defined daily dose (DDD) of MRA between 12.5 and 50 mg may alleviate risk of death in a U-shape pattern. A specificity test identified patients who has aldosterone producing adenoma (HR = 0.50, p = 0.005) also confirmed adrenalectomy attenuated all-cause mortality. Adrenalectomy decreases long-term all-cause mortality independently from PA cure from hypertension. Prescription corresponding to a DDD between 12.5 and 50 mg may decrease mortality for patients needing MRA. It calls for more attention on early diagnosis, early treatment and prescription of appropriate dosage of MRA for PA patients. PMID:27586402

  8. High-Performance Upconversion Nanoprobes for Multimodal MR Imaging of Acute Ischemic Stroke.

    PubMed

    Wang, Jing; Zhang, Hua; Ni, Dalong; Fan, Wenpei; Qu, Jianxun; Liu, Yanyan; Jin, Yingying; Cui, Zhaowen; Xu, Tianyong; Wu, Yue; Bu, Wenbo; Yao, Zhenwei

    2016-07-01

    Multimodal magnetic resonance (MR) imaging, including MR angiography (MRA) and MR perfusion (MRP), plays a critical role in the diagnosis and surveillance of acute ischemic stroke. However, these techniques are hindered by the low T1 relaxivity, short circulation time, and high leakage rate from vessels of clinical Magnevist. To address these problems, nontoxic polyethylene glycol (PEG)ylated upconversion nanoprobes (PEG-UCNPs) are synthesized and first adopted for excellent MRA and MRP imaging, featuring high diagnostic sensitivity toward acute ischemic stroke in high-resolution imaging. The investigations show that the agent possesses superior advantages over clinical Magnevist, such as much higher relaxivity, longer circulation time, and lower leakage rate, which guarantee much better imaging efficiency. Remarkably, an extremely small dosage (5 mg Gd kg(-1) ) of PEG-UCNPs provides high-resolution MRA imaging with the vascular system delineated much clearer than the Magnevist with clinical dosage as high as 108 mg Gd kg(-1) . On the other hand, the long circulation time of PEG-UCNPs enables the surveillance of the progression of ischemic stroke using MRA or MRP. Once translated, these PEG-UCNPs are expected to be a promising candidate for substituting the clinical Magnevist in MRA and MRP, which will significantly lengthen the imaging time window and improve the overall diagnostic efficiency. PMID:27219071

  9. Long term outcome of Aldosteronism after target treatments.

    PubMed

    Wu, Vin-Cent; Wang, Shuo-Meng; Chang, Chia-Hui; Hu, Ya-Hui; Lin, Lian-Yu; Lin, Yen-Hung; Chueh, Shih-Chieh Jeff; Chen, Likwang; Wu, Kwan-Dun

    2016-01-01

    There exists a great knowledge gap in terms of long-term effects of various surgical and pharmacological treatments on outcomes among primary aldosteronism (PA) patients. Using a validated algorithm, we extracted longitudinal data for all PA patients diagnosed in 1997-2010 and treated in the Taiwan National Health Insurance. We identified 3362 PA patients for whom the mean length of follow-up was 5.75 years. PA has higher major cardiovascular events (MACE) than essential hypertension (23.3% vs 19.3%, p = 0.015). Results from the Cox model suggest a strong effect of adrenalectomy on lowering mortality (HR = 0.23 with residual hypertension and 0.21 with resolved hypertension). While need for receptor antagonist (MRA) MRA after diagnosis suggests that a defined daily dose (DDD) of MRA between 12.5 and 50 mg may alleviate risk of death in a U-shape pattern. A specificity test identified patients who has aldosterone producing adenoma (HR = 0.50, p = 0.005) also confirmed adrenalectomy attenuated all-cause mortality. Adrenalectomy decreases long-term all-cause mortality independently from PA cure from hypertension. Prescription corresponding to a DDD between 12.5 and 50 mg may decrease mortality for patients needing MRA. It calls for more attention on early diagnosis, early treatment and prescription of appropriate dosage of MRA for PA patients. PMID:27586402

  10. Relationship between systolic and diastolic function with improvements in forward stroke volume following reduction in mitral regurgitation

    NASA Technical Reports Server (NTRS)

    Firstenberg, M. S.; Greenberg, N. L.; Smedira, N. G.; McCarthy, P. M.; Garcia, M. J.; Thomas, J. D.

    2001-01-01

    Efforts to improve mitral regurgitation (MR) are often performed in conjunction with coronary revascularization. However, the independent effects of a reduced MR area (MRa) are difficult to quantify. Using a previously developed cardiovascular model, ventricular contractility (elastance 1-8 mmHg/ml) and relaxation (tau: 40-150 msec) were independently adjusted for four grades of MR orifice areas (0.0 to 0.8 cm2). Improvements in forward stroke volume (fSV) were determined for the permutations of reduced MRa. For all conditions, LV end-diastolic pressure and volumes ranged from 7.3-24.2 mmHg and 64.8-174.3 ml, respectively. Overall, fSV ranged from 36.0-89.4 (mean: 64.2 +/- 12.8) ml, improved between 6.4 and 35.3% (mean: 15.6 +/- 8.1%), and was best predicted by (r=0.97, p<0.01) %delta(fSV)[correction of fVS]=34[MRa initial] - 46[MRa final] -0.5[elastance]. Reduced MRa, independent of relaxation and minimally influence by contractility, yield improved fSVs.

  11. Chemoenzymatic syntheses of water-soluble lipid I fluorescent probes

    PubMed Central

    Mitachi, Katsuhiko; Siricilla, Shajila; Klaic, Lada; Clemons, William M.; Kurosu, Michio

    2015-01-01

    Peptidoglycan (PG) is unique to bacteria, and thus, the enzymes responsible for its biosynthesis are promising antibacterial drug targets. The membrane-embedded enzymes in PG remain significant challenges in studying their mechanisms due to the fact that preparations of suitable enzymatic substrates require time-consuming biological transformations or chemical synthesis. Lipid I (prenyl diphosphoryl-MurNAc-pentapeptide) is an important PG biosynthesis intermediate to study the central enzymes, translocase I (MraY/MurX) and MurG. Lipid I isolated from nature contains the C50-or C55-prenyl unit that shows extremely poor water-solubility that renders studies of translocase I and MurG enzymes difficult. We have studied biological transformation of water soluble lipid I fluorescent probes using bacterial membrane fractions and purified MraY enzymes. In our investigation of the minimum structural requirements of the prenyl phosphates in MraY-catalyzed lipid I synthesis, we found that (2Z,6E)-farnesyl phosphate (C15-phosphate) can be recognized by E. coli MraY to generate the water-soluble lipid I fluorescent probes in high-yield. Under the optimized conditions, the same reaction was performed by using the purified MraY from Hydrogenivirga spp. to afford the lipid I analog with high-yield in a short reaction time. PMID:26190869

  12. Advanced imaging of the scapholunate ligamentous complex.

    PubMed

    Shahabpour, Maryam; Staelens, Barbara; Van Overstraeten, Luc; De Maeseneer, Michel; Boulet, Cedric; De Mey, Johan; Scheerlinck, Thierry

    2015-12-01

    The scapholunate joint is one of the most involved in wrist injuries. Its stability depends on primary and secondary stabilisers forming together the scapholunate complex. This ligamentous complex is often evaluated by wrist arthroscopy. To avoid surgery as diagnostic procedure, optimization of MR imaging parameters as use of three-dimensional (3D) sequences with very thin slices and high spatial resolution, is needed to detect lesions of the intrinsic and extrinsic ligaments of the scapholunate complex. The paper reviews the literature on imaging of radial-sided carpal ligaments with advanced computed tomographic arthrography (CTA) and magnetic resonance arthrography (MRA) to evaluate the scapholunate complex. Anatomy and pathology of the ligamentous complex are described and illustrated with CTA, MRA and corresponding arthroscopy. Sprains, mid-substance tears, avulsions and fibrous infiltrations of carpal ligaments could be identified on CTA and MRA images using 3D fat-saturated PD and 3D DESS (dual echo with steady-state precession) sequences with 0.5-mm-thick slices. Imaging signs of scapholunate complex pathology include: discontinuity, nonvisualization, changes in signal intensity, contrast extravasation (MRA), contour irregularity and waviness and periligamentous infiltration by edema, granulation tissue or fibrosis. Based on this preliminary experience, we believe that 3 T MRA using 3D sequences with 0.5-mm-thick slices and multiplanar reconstructions is capable to evaluate the scapholunate complex and could help to reduce the number of diagnostic arthroscopies.

  13. Long term outcome of Aldosteronism after target treatments

    NASA Astrophysics Data System (ADS)

    Wu, Vin-Cent; Wang, Shuo-Meng; Chang, Chia-Hui; Hu, Ya-Hui; Lin, Lian-Yu; Lin, Yen-Hung; Chueh, Shih-Chieh Jeff; Chen, Likwang; Wu, Kwan-Dun

    2016-09-01

    There exists a great knowledge gap in terms of long-term effects of various surgical and pharmacological treatments on outcomes among primary aldosteronism (PA) patients. Using a validated algorithm, we extracted longitudinal data for all PA patients diagnosed in 1997–2010 and treated in the Taiwan National Health Insurance. We identified 3362 PA patients for whom the mean length of follow-up was 5.75 years. PA has higher major cardiovascular events (MACE) than essential hypertension (23.3% vs 19.3%, p = 0.015). Results from the Cox model suggest a strong effect of adrenalectomy on lowering mortality (HR = 0.23 with residual hypertension and 0.21 with resolved hypertension). While need for receptor antagonist (MRA) MRA after diagnosis suggests that a defined daily dose (DDD) of MRA between 12.5 and 50 mg may alleviate risk of death in a U-shape pattern. A specificity test identified patients who has aldosterone producing adenoma (HR = 0.50, p = 0.005) also confirmed adrenalectomy attenuated all-cause mortality. Adrenalectomy decreases long-term all-cause mortality independently from PA cure from hypertension. Prescription corresponding to a DDD between 12.5 and 50 mg may decrease mortality for patients needing MRA. It calls for more attention on early diagnosis, early treatment and prescription of appropriate dosage of MRA for PA patients.

  14. Evaluation of Agreement between HRT III and iVue OCT in Glaucoma and Ocular Hypertension Patients.

    PubMed

    Perdicchi, A; Iester, M; Iacovello, D; Cutini, A; Balestrieri, M; Mutolo, M G; Ferreras, A; Contestabile, M T; Recupero, S M

    2015-01-01

    Purpose. To determine the agreement between Moorfields Regression Analysis (MRA), Glaucoma Probability Score (GPS) of Heidelberg retinal tomograph (HRT III), and peripapillary nerve fibers thickness by iVue Optical Coherence Tomography (OCT). Methods. 72 eyes with ocular hypertension or primary open angle glaucoma (POAG) were included in the study: 54 eyes had normal visual fields (VF) and 18 had VF damage. All subjects performed achromatic 30° VF by Octopus Program G1X dynamic strategy and were imaged with HRT III and iVue OCT. Sectorial and global MRA, GPS, and OCT parameters were used for the analysis. Kappa statistic was used to assess the agreement between methods. Results. A significant agreement between iVue OCT and GPS for the inferotemporal quadrant (κ: 0.555) was found in patients with abnormal VF. A good overall agreement between GPS and MRA was found in all the eyes tested (κ: 0.511). A good agreement between iVue OCT and MRA was shown in the superonasal (κ: 0.656) and nasal (κ: 0.627) quadrants followed by the superotemporal (κ: 0.602) and inferotemporal (κ: 0.586) sectors in all the studied eyes. Conclusion. The highest percentages of agreement were found per quadrant of the MRA and the iVue OCT confirming that in glaucoma damage starts from the temporal hemiretina. PMID:26788363

  15. The Mackenzie River magnetic anomaly, Yukon and Northwest Territories, Canada-Evidence for Early Proterozoic magmatic arc crust at the edge of the North American craton

    USGS Publications Warehouse

    Pilkington, M.; Saltus, R.W.

    2009-01-01

    We characterize the nature of the source of the high-amplitude, long-wavelength, Mackenzie River magnetic anomaly (MRA), Yukon and Northwest Territories, Canada, based on magnetic field data collected at three different altitudes: 300??m, 3.5??km and 400??km. The MRA is the largest amplitude (13??nT) satellite magnetic anomaly over Canada. Within the extent of the MRA, source depth estimates (8-12??km) from Euler deconvolution of low-altitude aeromagnetic data show coincidence with basement depths interpreted from reflection seismic data. Inversion of high-altitude (3.5??km) aeromagnetic data produces an average magnetization of 2.5??A/m within a 15- to 35-km deep layer, a value typical of magmatic arc complexes. Early Proterozoic magmatic arc rocks have been sampled to the southeast of the MRA, within the Fort Simpson magnetic anomaly. The MRA is one of several broad-scale magnetic highs that occur along the inboard margin of the Cordillera in Canada and Alaska, which are coincident with geometric changes in the thrust front transition from the mobile belt to stable cratonic North America. The inferred early Proterozoic magmatic arc complex along the western edge of the North American craton likely influenced later tectonic evolution, by acting as a buttress along the inboard margin of the Cordilleran fold-and-thrust belt. Crown Copyright ?? 2008.

  16. Magnetic resonance angiography: physical principles and applications.

    PubMed

    Kiruluta, Andrew J M; González, R Gilberto

    2016-01-01

    Magnetic resonance angiography (MRA) is the visualization of hemodynamic flow using imaging techniques that discriminate flowing spins in blood from those in stationary tissue. There are two classes of MRA methods based on whether the magnetic resonance imaging signal in flowing blood is derived from the amplitude of the moving spins, the time-of-flight methods, or is based on the phase accumulated by these flowing spins, as in phase contrast methods. Each method has particular advantages and limitations as an angiographic imaging technique, as evidenced in their application space. Here we discuss the physics of MRA for both classes of imaging techniques, including contrast-enhanced approaches and the recent rapid expansion of the techniques to fast acquisition and processing techniques using parallel imaging coils as well as their application in high-field MR systems such as 3T and 7T. PMID:27432663

  17. Visualization of Periventricular Collaterals in Moyamoya Disease with Flow-sensitive Black-blood Magnetic Resonance Angiography: Preliminary Experience

    PubMed Central

    FUNAKI, Takeshi; FUSHIMI, Yasutaka; TAKAHASHI, Jun C.; TAKAGI, Yasushi; ARAKI, Yoshio; YOSHIDA, Kazumichi; KIKUCHI, Takayuki; MIYAMOTO, Susumu

    2015-01-01

    Fragile abnormal collaterals in moyamoya disease, known as “moyamoya vessels,” have rarely been defined. While flow-sensitive black-blood magnetic resonance angiography (FSBB-MRA) is a promising technique for visualizing perforating arteries, as of this writing no other reports exist regarding its application to moyamoya disease. Six adults with moyamoya disease underwent FSBB-MRA. It depicted abnormal collaterals as extended lenticulostriate, thalamic perforating, or choroidal arteries, which were all connected to the medullary or insular artery in the periventricular area and supplied the cortex. This preliminary case series illustrates the potential for FSBB-MRA to reveal abnormal moyamoya vessels, which could be reasonably defined as periventricular collaterals. PMID:25739429

  18. Pulmonary arterial hypertension: an imaging review comparing MR pulmonary angiography and perfusion with multidetector CT angiography

    PubMed Central

    Junqueira, F P; Lima, C M A O; Coutinho, A C; Parente, D B; Bittencourt, L K; Bessa, L G P; Domingues, R C; Marchiori, E

    2012-01-01

    Pulmonary hypertension (PH) is a progressive disease that leads to substantial morbidity and eventual death. Pulmonary multidetector CT angiography (MDCTA), pulmonary MR angiography (MRA) and MR-derived pulmonary perfusion (MRPP) imaging are non-invasive imaging techniques for the differential diagnosis of PH. MDCTA is considered the gold standard for the diagnosis of pulmonary embolism, one of the most common causes of PH. MRA and MRPP are promising techniques that do not require the use of ionising radiation or iodinated contrast material, and can be useful for patients for whom such material cannot be used. This review compares the imaging aspects of pulmonary MRA and 64-row MDCTA in patients with chronic thromboembolic or idiopathic PH. PMID:22932061

  19. Contrast-enhanced MR angiography utilizing parallel acquisition techniques in renal artery stenosis detection.

    PubMed

    Slanina, Martin; Zizka, Jan; Klzo, Ludovít; Lojík, Miroslav

    2010-07-01

    Significant renal artery stenosis (RAS) is a potentially curable cause of renovascular hypertension and/or renal impairment. It is caused by either atherosclerosis or fibromuscular dysplasia. Correct and timely diagnosis remains a diagnostic challenge. MR angiography (MRA) as a minimally invasive method seems to be suitable for RAS detection, however, its diagnostic value widely differs in the literature (sensitivity 62-100% and specificity 75-100%). The aim of our prospective study was to compare the diagnostic value of contrast-enhanced MRA utilizing parallel acquisition techniques in the detection of significant RAS with digital subtraction angiography (DSA). A total of 78 hypertensive subjects with suspected renal artery stenosis were examined on a 1.5 Tesla MR system using a body array coil. Bolus tracking was used to monitor the arrival of contrast agent to the abdominal aorta. The MRA sequence parameters were as follows: TR 3.7 ms; TE 1.2 ms; flip angle 25 degrees; acquisition time 18s; voxel size 1.1 mm x1.0 mm x 1.1 mm; centric k-space sampling; parallel acquisition technique with acceleration factor of 2 (GRAPPA). Renal artery stenosis of 60% and more was considered hemodynamically significant. The results of MRA were compared to digital subtraction angiography serving as a standard of reference. Sensitivity and specificity of MRA in the detection of hemodynamically significant renal artery stenosis were 90% and 96%, respectively. Prevalence of RAS was 39% in our study population. Contrast-enhanced MRA with high spatial resolution offers sufficient sensitivity and specificity for screening of RAS. PMID:19671492

  20. Diagnosing flow residuals in coiled cerebral aneurysms by MR angiography: meta-analysis.

    PubMed

    Menke, Jan; Schramm, Peter; Sohns, Jan Martin; Kallenberg, Kai; Staab, Wieland

    2014-04-01

    This meta-analysis summarizes the accuracy of magnetic resonance angiography (MRA) for diagnosing residuals in coiled cerebral aneurysms by using the threefold Roy classification (residuals: none, neck, or sac). Four databases were searched from 2000 to June 2013 for eligible studies that compared MRA to digital subtraction angiography (DSA) and reported 3 × 3 count data of threefold Roy classification, or a reduced scheme of 2 × 2 count data. Bivariate and trivariate Bayesian random-effects models were used for meta-analysis. Among 27 included studies (2,119 coiled aneurysms in 1,809 patients) the average prevalence of DSA-confirmed sac residuals was 18.2 % (range 0-43 %). The pooled sensitivity was 88.0 % (95 % CI 81.4-94.0) and specificity was 97.2 % (94.6-99.0 %) for assessing sac residuals by MRA. In the trivariate meta-analysis, a "sac residual" finding at MRA had a high positive likelihood ratio of 28.2 (14.0-79.0). A "neck residual" finding had a moderate negative likelihood ratio of 0.246 (0.111-0.426), and the MRA finding of "no residual" had a good negative likelihood ratio of 0.044 (0.013-0.096). Subgroup analyses identified no significant influence of covariates on diagnostic accuracy (P > 0.05). In conclusion, in coiled cerebral aneurysms MRA with application of the threefold Roy classification is well suited for detecting or excluding sac residuals that might require retreatment. PMID:23893001

  1. Use of oral gadobenate dimeglumine to visualise the oesophagus during magnetic resonance angiography in patients with atrial fibrillation prior to catheter ablation

    PubMed Central

    2014-01-01

    Background Atrio-oesophageal fistula was first reported as a fatal complication of surgical endocardial and percutaneous endocardial radiofrequency ablation for atrial fibrillation, with an incidence after catheter ablation between 0.03% and 0.5%. Magnetic resonance angiography (MRA) was usually performed to obtain pre-procedural 3D images, used to merging into an electro-anatomical map, guiding step-by-step ablation strategy of AF. Our aim was to find an easy, safe and cost-effective way to enhance the oesophagus during MRA. Methods In 105 consecutive patients, a right-left phase encoding, free breathing, 3D T1 MRA sequence was performed in the axial plane, >24 hours before catheter ablation, using an intravenous injection of gadobenate dimeglumine contrast medium. The oesophagus was enhanced using an oral gel solution of 0.7 mL gadobenate dimeglumine contrast medium mixed with approximately 40 mg thickened water gel, which was swallowed by the patients on the scanning table, immediately before the MRA sequence acquisition. Results The visualisation of the oesophagus was obtained in 104/105 patients and images were successfully merged, as left atrium and pulmonary veins, into an electro-anatomical map, during percutaneous endocardial radiofrequency ablation. All patients tolerated the study protocol and no immediate or late complication was observed with the oral contrast agent administration. The free-breathing MRA sequence used in our protocol took 7 seconds longer than MRA breath-hold conventional sequence. Conclusion Oesophagus visualization with oral gadobenate dimeglumine is feasible for integration of oesophagus anatomy images into the electro-anatomical map during AF ablation, without undesirable side effects and without significantly increasing cost or examination time. PMID:24927953

  2. Should the scope of human mixture risk assessment span legislative/regulatory silos for chemicals?

    PubMed

    Evans, Richard M; Martin, Olwenn V; Faust, Michael; Kortenkamp, Andreas

    2016-02-01

    Current chemicals regulation operates almost exclusively on a chemical-by-chemical basis, however there is concern that this approach may not be sufficiently protective if two or more chemicals have the same toxic effect. Humans are indisputably exposed to more than one chemical at a time, for example to the multiple chemicals found in food, air and drinking water, and in household and consumer products, and in cosmetics. Assessment of cumulative risk to human health and/or the environment from multiple chemicals and routes can be done in a mixture risk assessment (MRA). Whilst there is a broad consensus on the basic science of mixture toxicology, the path to regulatory implementation of MRA within chemical risk assessment is less clear. In this discussion piece we pose an open question: should the scope of human MRA cross legislative remits or 'silos'? We define silos as, for instance, legislation that defines risk assessment practice for a subset of chemicals, usually on the basis of substance/product, media or process orientation. Currently any form of legal mandate for human MRA in the EU is limited to only a few pieces of legislation. We describe two lines of evidence, illustrated with selected examples, that are particularly pertinent to this question: 1) evidence that mixture effects have been shown for chemicals regulated in different silos and 2) evidence that humans are co-exposed to chemicals from different silos. We substantiate the position that, because there is no reason why chemicals allocated to specific regulatory silos would have non-overlapping risk profiles, then there is also no reason to expect that MRA limited only to chemicals within one silo can fully capture the risk that may be present to human consumers. Finally, we discuss possible options for implementation of MRA and we hope to prompt wider discussion of this issue. PMID:26573369

  3. Cervical vertigo and dizziness after whiplash injury.

    PubMed

    Endo, Kenji; Ichimaru, Katsuji; Komagata, Mashashi; Yamamoto, Kengo

    2006-06-01

    Whiplash injury is not only limited to neck injury but also brainstem injury that does not involve direct damage to the neck or head. The symptoms of whiplash injury are polymorphous, with the most common complaints being cervical pain, headache and scapulodynia. Vertigo and dizziness are also reported in 25-50% of the cases. In otoneurologic studies, magnetic resonance angiography (MRA) is used for the evaluation of vertebrobasilar hemodynamics in patients who complain of dizziness and vertigo. It is reported that vertebrobasilar artery insufficiency (VBI) leads to brainstem and cerebellar ischemia and infarction following cervical manipulation. Here we examined the correlation between vertigo or dizziness and the right and left side difference in vertebral arteries after whiplash injury using MRA. We studied 20 patients who complained of neck pain with vertigo or dizziness after whiplash injury and 13 healthy volunteers as a control. In the control group, abnormal MRA findings in the vertebral arteries such as occlusion, stenosis or slow blood flow were seen in 77% of the cases. In the patient group, abnormal MRA findings were seen in 60%. The side difference in blood flow was 3.5+/-2.5 cm/s in the control group and 6.1+/-3.0 cm/s in the patient group. Our findings suggest that some subjects with persistent vertigo or dizziness after whiplash injury are more likely to have VBI on MRA. VBI might be an important background factor to evoke cervical vertigo or dizziness after whiplash injury. The side difference between the two vertebral arteries could cause a circulation disorder in the vertebrobasilar system after whiplash injury. However, the VBI on MRA itself was also seen in the control group, and thus it is not clear whether it is due to whiplash injury in the patient group.

  4. Structural Measurements for Monitoring Change in Glaucoma: Comparing Retinal Nerve Fiber Layer Thickness With Minimum Rim Width and Area

    PubMed Central

    Gardiner, Stuart K.; Boey, Pui Yi; Yang, Hongli; Fortune, Brad; Burgoyne, Claude F.; Demirel, Shaban

    2015-01-01

    Purpose Minimum rim width (MRW) and area (MRA) have been introduced as anatomically defensible measures of neuroretinal rim tissue observable using spectral-domain optical coherence tomography (SDOCT). They have been reported to change earlier than retinal nerve fiber layer thickness (RNFLT) in glaucoma. This study sought to determine which is better to distinguish subsequent change from variability, using the previously described longitudinal signal-to-noise ratio (LSNR). Methods Data from 157 eyes of 157 participants with high-risk ocular hypertension or non–end-stage glaucoma (mean deviation [MD] from −22 to +3 dB) were used. Participants were tested approximately every 6 months for at least six visits. For each eye, MRW, MRA, and RNFLT were regressed linearly against time. Longitudinal signal-to-noise ratio for each eye was defined as the rate of change over time (signal) divided by the standard deviation of residuals from this trend (noise). These were compared between parameters using a Wilcoxon signed rank test. Results The median LSNRs were −0.58y−1 for RNFLT (bootstrapped 95% confidence interval −0.69 to −0.48y−1); −0.44y−1 (−0.59 to −0.32y−1) for MRW; and −0.23y−1 (−0.32 to −0.08y−1) for MRA. Longitudinal signal-to-noise ratios were significantly more negative for RNFLT than for MRW (P = 0.025) or for MRA (P < 0.001). Conclusions Retinal nerve fiber layer thickness measured by SDOCT had a better LSNR than MRW or MRA. Although MRW and MRA may be more sensitive for early detection of glaucomatous damage, these data suggest that RNFLT may be preferable for monitoring change. PMID:26501416

  5. Effects of hydration levels on the bandwidth of microwave resonant absorption induced by confined acoustic vibrations

    NASA Astrophysics Data System (ADS)

    Liu, Tzu-Ming; Chen, Hung-Pin; Yeh, Shih-Chia; Wu, Chih-Yu; Wang, Chung-Hsiung; Luo, Tang-Nian; Chen, Yi-Jan; Liu, Shen-Iuan; Sun, Chi-Kuang

    2009-10-01

    We found the hydration levels on the capsid surface of viruses can affect the bandwidth of microwave resonant absorption (MRA) induced by the confined acoustic vibrations (CAV). By decreasing the pH value of solution down to 5.2 or inactivating the capsid proteins, we enhanced the surface hydrophilicity and increased the magnitude of surface potentials. Both of these surface manipulations raised the surface affinity to water molecules and narrowed the bandwidths of CAV-induced MRA. Our results validate the viscoelastic transition of hydration shells.

  6. Tumor Therapeutic Response and Vessel Tortuosity: Preliminary Report in Metastatic Breast Cancer

    PubMed Central

    Bullitt, Elizabeth; Lin, Nancy U.; Ewend, Matthew G.; Zeng, Donglin; Winer, Eric P.; Carey, Lisa A.; Smith, J. Keith

    2008-01-01

    No current non-invasive method is capable of assessing the efficacy of brain tumor therapy early during treatment. We outline an approach that evaluates tumor activity via statistical analysis of vessel shape using vessels segmented from MRA. This report is the first to describe the changes in vessel shape that occur during treatment of metastatic brain tumors as assessed by sequential MRA. In this preliminary study of 16 patients undergoing treatment for metastatic breast cancer we conclude that vessel shape may predict tumor response several months in advance of traditional methods. PMID:17354817

  7. Subsecond magnetic resonance angiography and the evaluation of abnormal arteriovasuclar communications

    NASA Astrophysics Data System (ADS)

    Zachariah, Anish B.; Pereles, F. S.; Kaliney, Ryan; Carr, James C.; Collins, Jeremy D.; Wood, Cecil; Finn, John P.

    2003-05-01

    Magnetic resonance (MR) angiography is becoming widely accepted in the diagnosis of vascular diseases. When used for evaluation of arterial stenoses, aneurysm, thrombosis, or occlusion, MR angiography is a robust and accurate technique. Traditional techniques for contrast-enhanced magnetic resonance angiography (MRA) offer the benefit of high spatial resolution in characterizing vascular malformations, but have lacked the temporal resolution to describe dynamic flow events. The purpose of this project is to demonstrate the potential role of a novel technique, sub-second MRA, in the evaluation of abdominal arteriovenous malformation.

  8. Evaluation of Intracranial Vasculatures in Healthy Subjects with Arterial-Spin-Labeling-Based 4D-MR Angiography at 3T.

    PubMed

    Iryo, Yasuhiko; Hirai, Toshinori; Nakamura, Masanobu; Tateishi, Machiko; Hayashida, Eri; Azuma, Minako; Nishimura, Shinichiro; Kitajima, Mika; Yamashita, Yasuyuki

    2016-07-11

    Contrast inherent inflow-enhanced multi-phase angiography combining multiple-phase flow-alternating inversion-recovery (CINEMA-FAIR) is an arterial-spin-labeling-based four-dimensional magnetic resonance angiography (4D-MRA) technique. Two neuroradiologists independently evaluated the depiction of the intracranial vasculatures in healthy subjects with 3T 4D-MRA using CINEMA-FAIR. Our results indicated that this technique can provide good visualization of the cerebral arteries with a high spatial and temporal resolution. It appears to have sufficient resolution for identifying flow difference in the anterior and posterior circulation in healthy subjects. PMID:26701696

  9. MRI of the Coronary vasculature: Imaging the Lumen, Wall and Beyond

    PubMed Central

    Lin, Kai; Carr, James C.

    2015-01-01

    The characteristics of coronary artery disease (CAD) are gradual thickening of the coronary walls and narrowing of the vascular lumen due to the built-up of atherosclerosis plaques. Those morphological changes can be noninvasively detected by coronary MRI/MRA. In addition, functional changes, such as coronary wall distensibility and flow changes may also be evaluated with MRI. However, the application of current MRI/MRA techniques is limited in clinical practice due to several adverse technical and physiological factors, such as cardiac motion and respiratory motion. Many technical innovations have been adopted to address those problems from multiple aspects. PMID:25726999

  10. Assessment of the kidneys: magnetic resonance angiography, perfusion and diffusion

    PubMed Central

    2011-01-01

    Renal magnetic resonance (MR) imaging has undergone major improvements in the past several years. This review focuses on the technical basics and clinical applications of MR angiography (MRA) with the goal of enabling readers to acquire high-resolution, high quality renal artery MRA. The current role of contrast agents and their safe use in patients with renal impairment is discussed. In addition, an overview of promising techniques on the horizon for renal MR is provided. The clinical value and specific applications of renal MR are critically discussed. PMID:22085467

  11. Greenland opens more offshore, land acreage to exploration

    SciTech Connect

    Not Available

    1992-01-13

    Greenland's Mineral Resources Administration (MRA) plans a series of licensing rounds off western Greenland. Meanwhile, the MRA has declared the Jameson Land basin of east central Greenland as open acreage. Greenland Geological Survey (GGU), Copenhagen, has prepared a report on the geographical conditions, logistics, exploration history, and geological development of Jameson Land. The article emphasizes source and reservoir rocks, conceptual play types with six seismic examples, and thermal history with basin modeling. It also includes two interpreted regional seismic lines, a geological and an aeromagnetic map, depth structure, and isopach maps of selected formations.

  12. Aortoiliac thrombus secondary to a mineralized arteriosclerotic lesion.

    PubMed

    Drost, W T; Bahr, R J; Henry, G A; Campbell, G A

    1999-01-01

    A 12-year-old, neutered female, Siberian Husky dog presented with a hind limb weakness of one month duration. To facilitate making a diagnosis multiple imaging modalities were performed. These modalities included radiography, ultrasonography, magnetic resonance imaging (MRI), magnetic resonance angiography (MRA) and selective angiography of the abdominal aorta. In this dog, the MRI/MRA studies provided the first documentation of the external iliac thrombi and the collateral circulation via the lumbar arteries. At necropsy, an aortoiliac thrombus caused by a mineralized arteriosclerotic plaque was noted.

  13. Significance of magnetic resonance angiography-diffusion weighted imaging mismatch in hyperacute cerebral infarction.

    PubMed

    Deguchi, Ichiro; Takeda, Hidetaka; Furuya, Daisuke; Dembo, Tomohisa; Nagoya, Harumitsu; Kato, Yuji; Ito, Yasuo; Fukuoka, Takuya; Maruyama, Hajime; Tanahashi, Norio

    2012-02-01

    Therapeutic results with respect to lesion size were analyzed and compared in patients with hyperacute cerebral infarction with and without major artery lesions on magnetic resonance angiography (MRA) and in those who did and did not receive intravenous (IV) tissue plasminogen activator (t-PA). Of the patients with cerebral infarction who visited the hospital within 3 hours of onset between April 2007 and September 2009, 127 patients with cerebral infarction in the anterior circulation region in whom head magnetic resonance imaging (diffusion-weighted imaging [DWI]) or MRA was performed (81 men and 46 women; mean age, 71 ± 11 years) were enrolled. Major artery lesions (+) were defined as internal carotid artery occlusion and middle cerebral artery (M1/M2 segment) occlusion and ≥50% stenosis. Based on the presence or absence of major artery lesions and the size of DWI lesions, the subjects were divided into 3 groups: MRA-DWI mismatch (+) group [major artery lesion (+) and DWI-ASPECTS ≥6], MRA-DWI mismatch (-) group [major artery lesion (+) and DWI-ASPECTS <6], and major artery lesion (-) group. IV t-PA was given to 21 of the 64 patients in the MRA-DWI mismatch (+) group, to 1 of the 24 patients in the MRA-DWI mismatch (-) group, and to 9 of the 39 patients in the major artery lesion (-) group. In the MRA-DWI mismatch (+) group (n = 64), the median National Institutes of Health Stroke Scale (NIHSS) score on admission was higher in t-PA-treated patients than in t-PA-untreated patients (15 vs 11). The modified Rankin scale (mRS) score at day 90 after onset was more favorable in t-PA-treated patients (0-2 in 10 patients [48%] and 3-6 in 11 patients [52%]) than in t-PA-untreated patients (0-2 in 12 patients [28%] and 3-6 in 31 patients [72%]). After adjusting for admission NIHSS score, there was a significant difference in outcome (mRS score) between t-PA-treated patients (0-2 in 10 patients [48%] and 3-6 in 11 patients [52%]) and t-PA-untreated patients (0-2 in 3

  14. Time-resolved MR angiography with limited projections.

    PubMed

    Huang, Yuexi; Wright, Graham A

    2007-08-01

    A method for reconstruction of time-resolved MRI called highly-constrained backprojection (HYPR) has been developed. To evaluate the HYPR reconstruction in relation to data sparsity and temporal dynamics, computer simulations were performed, investigating signal modulations under different situations that reflect dynamic contrast-enhanced MR angiography (MRA). In vivo studies were also performed with gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) for abdominal MRA in a canine model to demonstrate the application of HYPR for three-dimensional (3D) time-resolved MRA. When contrast dynamics vary over space, large vessels (e.g., veins) tend to introduce signal interference to small vessels (e.g., arteries) in HYPR, particularly when the vessels are in close proximity. The enhancement of background tissue signals may also alter the arterial and venous temporal profiles in HYPR. However, the artifacts are manifest as intensity modulation rather than structural interference, and therefore have little impact on structural diagnosis. Increasing the number of projections per time point increases temporal blur while reducing corruption of temporal behavior from adjacent tissues. Uniformly interleaved acquisition order, such as the bit-reversed order, is important to reduce artifacts. With high signal-to-noise ratio (SNR) and limited artifacts, HYPR reconstruction has potential to greatly improve time-resolved MRA in clinical practice.

  15. 32 CFR 56.5 - Responsibilities.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 1 2013-07-01 2013-07-01 false Responsibilities. 56.5 Section 56.5 National... DEFENSE § 56.5 Responsibilities. (a) The Assistant Secretary of Defense (Manpower, Reserve Affairs, and... responsibility, the ASD(MRA&L), or designee, shall: (1) Coordinate efforts of DoD Components to enforce this...

  16. 32 CFR 56.5 - Responsibilities.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 1 2011-07-01 2011-07-01 false Responsibilities. 56.5 Section 56.5 National... DEFENSE § 56.5 Responsibilities. (a) The Assistant Secretary of Defense (Manpower, Reserve Affairs, and... responsibility, the ASD(MRA&L), or designee, shall: (1) Coordinate efforts of DoD Components to enforce this...

  17. 32 CFR 56.5 - Responsibilities.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 1 2014-07-01 2014-07-01 false Responsibilities. 56.5 Section 56.5 National... DEFENSE § 56.5 Responsibilities. (a) The Assistant Secretary of Defense (Manpower, Reserve Affairs, and... responsibility, the ASD(MRA&L), or designee, shall: (1) Coordinate efforts of DoD Components to enforce this...

  18. 77 FR 45350 - Notice of Availability of Microbial Risk Assessment Guideline: Pathogenic Microorganisms With...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-31

    .... Although the focus of this guideline is microbial contamination of water and food, it will also be useful... Focus on Food and Water AGENCY: Environmental Protection Agency (EPA). ACTION: Notice of availability... Assessment Guideline: Pathogenic Microorganisms with Focus on Food and Water (MRA Guideline). The...

  19. 78 FR 9419 - National Register of Historic Places; Notification of Pending Nominations and Related Actions

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-08

    ... Maricopa County Stephens, C.P., DeSoto Six Motorcars, (Phoenix Commercial MRA), 915 N. Central Ave... GEORGIA Chatham County Savannah Pharmacy and Fonvielle Office Building, 914-918 Martin Luther King, Jr..., 13000025 Kings County Storehouse No. 2, U.S. Navy Fleet Supply Base, 850 3rd Ave., Brooklyn, 13000026...

  20. Estimation of parameters for the elimination of an orally administered test substance with unknown absorption.

    PubMed

    Vogt, Josef A; Denzer, Christian

    2013-04-01

    Assessment of the elimination of an oral test dose based on plasma concentration values requires correction for the effect of gastric release and absorption. Irregular uptake processes should be described 'model independently', which requires estimation of a large number of absorption parameters. To limit the associated computational effort a new approach is developed with a reduced number of unknown parameters. A marginalized and regularized absorption approach (MRA) is defined, which uses for the uptake just one parameter to control rigidity of the uptake curve. For validation, elimination and absorption were reproduced using published IVIVC data and a synthetic data set for comparison with approaches using a 'model-free'--staircase function or mechanistic models to describe absorption. MRA performed almost as accurate as well specified mechanistic models, which gave the best reproduction. MRA demonstrated a 50fold increase in computational efficiency compared to other approaches. The absorption estimated for the IVIVC study demonstrated an in vivo-in vitro correlation comparable to published values. The newly developed MRA approach can be used to efficiently and accurately estimate elimination and absorption with a restricted number of adaptive parameters and with automatic adjustment of the complexity of the uptake.

  1. 32 CFR 56.8 - Guidelines for determining discriminatory practices.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Historic Preservation regulation on “Protection of Historic and Cultural Properties” (36 CFR part 800... Preservation regulation on “Protection of Historic and Cultural Properties” (36 CFR part 800) prior to... problems may be addressed to the ASD (MRA&L), or designee. (ii) When structural changes are necessary...

  2. 32 CFR 56.8 - Guidelines for determining discriminatory practices.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Historic Preservation regulation on “Protection of Historic and Cultural Properties” (36 CFR part 800... Preservation regulation on “Protection of Historic and Cultural Properties” (36 CFR part 800) prior to... problems may be addressed to the ASD (MRA&L), or designee. (ii) When structural changes are necessary...

  3. Magnetic resonance angiography with ultrashort echo times reduces the artefact of aneurysm clips.

    PubMed

    Gönner, F; Lövblad, K O; Heid, O; Remonda, L; Guzman, R; Barth, A; Schroth, G

    2002-09-01

    We evaluated the ability of an ultrashort echo time (TE) three-dimensional (3D) time-of-flight (TOF) magnetic resonance angiography (MRA) sequence to reduce the metal artefact of intracranial aneurysm clips and to display adjacent cerebral arteries. In five patients (aged 8-72 years) treated with Elgiloy or Phynox aneurysm clips we prospectively performed a conventional (TE 6.0 ms) and a new ultrashort TE (TE 2.4 ms) 3D TOF MRA. We compared the diameter of the clip-induced susceptibility artefact and the detectability of flow in adjacent vessels. The mean artefact diameter was 22.3+/-6.4 mm (range 14-38 mm) with the ultrashort TE and 27.7+/-6.4 mm (range 19-45 mm) with the conventional MRA ( P<0.0001). This corresponded to a diameter reduction of 19.5+/-9.2%. More parts of adjacent vessels were detected, but with less intense flow signal. The aneurysm dome and neck remained within the area of signal loss and were therefore not displayed. Ultrashort TE MRA is a noninvasive and fast method for improving detection of vessels adjacent to clipped intracranial aneurysms, by reducing clip-induced susceptibility artefact. The method cannot, however, be used to show remnants of the aneurysm neck or sac as a result of imperfect clipping. PMID:12221447

  4. Direct magnetic resonance arthrography of the canine shoulder.

    PubMed

    Schaefer, Susan L; Baumel, Cheryl A; Gerbig, Jamie R; Forrest, Lisa J

    2010-01-01

    Our goal was to evaluate the ability of three magnetic resonance arthrography (MRA) techniques to improve visualization of soft tissue stabilizing components of the canine shoulder. The optimum concentration of gadolinium (gadodiamide) for MRA was determined by imaging seven individual shoulders with one of seven dilutions of 0.5 mol/l gadodiamide in saline; (1:100, 1:400, 1:800, 1:1000, 1:1200, 1:1400, and 1:1600). For this, sagittal and dorsal T1-weighted fat saturation (T1WFS) images were used. The 1:1200 dilution of gadolinium was determined to be the optimum concentration as it provided adequate contrast to distinguish supporting joint structures without obscuring the edges of those structures. Sagittal, dorsal, and transverse MRA images were then acquired in nine cadaver shoulders using T1WFS with gadolinium, proton density fat saturation (PDFS) with gadolinium, and PDFS with saline. Descriptive comparisons were made among techniques. When gadolinium was compared with saline as a contrast medium, gadolinium provided greater contrast against underlying soft tissues, thereby enhancing tendon and ligament conspicuity. When T1WFS and PDFS gadolinium sequences were compared, minor differences were noted. The interface between tissue and fluid was sharper and more distinct in PDFS images. MRI arthrography has promise as a tool for the diagnosis of canine soft tissue shoulder injury. MRA may be most useful when trauma to the biceps tendon, lateral glenohumeral ligament, or medial glenohumeral ligament is suspected.

  5. The Process of Establishing a New Master of Research Administration Program

    ERIC Educational Resources Information Center

    Smith, Jo Ann; Torres, Laurianne

    2011-01-01

    In 2009, the second largest university in the nation was awarded a grant from NCURA to initiate a new fully-online graduate program in research administration. The Master of Research Administration (MRA) was approved by the institution's Board of Trustees in March 2011 and the first classes will begin August 2011. Currently the research literature…

  6. PARTITION COEFFICIENTS FOR METALS IN SURFACE WATER, SOIL, AND WASTE

    EPA Science Inventory

    This report presents metal partition coefficients for the surface water pathway and for the source model used in the Multimedia, Multi-pathway, Multi-receptor Exposure and Risk Assessment (3MRA) technology under development by the U.S. Environmental Protection Agency. Partition ...

  7. EVALUATION OF VADOSE ZONE AND SORUCE MODULES FOR MULTI-MEDIA, MULTI-PATHWAY, AND MULTI-RECEPTOR RISK ASSESSMENT USING LARGE-SOIL-COLUMN EXPERIMENTAL DATA

    EPA Science Inventory

    The United States Environmental Protection Agency (EPA) is developing a comprehensive environmental exposure and risk analysis software system for agency-wide application using the methodology of a Multi-media, Multi-pathway, Multi-receptor Risk Assessment (3MRA) model. This sof...

  8. Multiresolution analysis over simple graphs for brain computer interfaces

    NASA Astrophysics Data System (ADS)

    Asensio-Cubero, J.; Gan, J. Q.; Palaniappan, R.

    2013-08-01

    Objective. Multiresolution analysis (MRA) offers a useful framework for signal analysis in the temporal and spectral domains, although commonly employed MRA methods may not be the best approach for brain computer interface (BCI) applications. This study aims to develop a new MRA system for extracting tempo-spatial-spectral features for BCI applications based on wavelet lifting over graphs. Approach. This paper proposes a new graph-based transform for wavelet lifting and a tailored simple graph representation for electroencephalography (EEG) data, which results in an MRA system where temporal, spectral and spatial characteristics are used to extract motor imagery features from EEG data. The transformed data is processed within a simple experimental framework to test the classification performance of the new method. Main Results. The proposed method can significantly improve the classification results obtained by various wavelet families using the same methodology. Preliminary results using common spatial patterns as feature extraction method show that we can achieve comparable classification accuracy to more sophisticated methodologies. From the analysis of the results we can obtain insights into the pattern development in the EEG data, which provide useful information for feature basis selection and thus for improving classification performance. Significance. Applying wavelet lifting over graphs is a new approach for handling BCI data. The inherent flexibility of the lifting scheme could lead to new approaches based on the hereby proposed method for further classification performance improvement.

  9. Testing the Waters: Can You Involve Community Action in Your College Curriculum?

    ERIC Educational Resources Information Center

    Knapp, Elizabeth P.; Harbor, David J.; Ginwalla, Zenobia F.

    2003-01-01

    Discusses the Maury River Alliance (MRA), a cooperative program developed at the Washington and Lee University that involved local colleges, high schools, government agencies, and conservation groups. Addresses the connection between land use and water quality with a creative merging of technical, social, and educational aspects of local watershed…

  10. [Assessment of vertebrobasilar insufficiency using magnetic resonance angiography].

    PubMed

    Barona, R; Martínez Sanjuán, V; Campos, A; Roch, S; Brisa, A; Comeche, C

    1994-01-01

    We present the protocol for diagnosis of VBI followed by ENT and Radiology Departments of the Valencia University General Hospital, using the 2D-PC magnetic resonance angiography technique (MRA) with variable VENC (30 and 40 cm/s) with a SIGMA 1.5 T Advantage system version 5 x with the corresponding software review 5.2 (General Electric Medical Systems, Milwaukee, WI, USA). After a coronal angiographic projection is obtained in a neutral position on an axial plane of localization, the patient head is set at the maximum left and right rotation and hyperextension allowed by patient and system. In this way, a coronal angiographic sequence is obtained in order to visualize potential compressions, decreases of the flow, arterial loops, etc. MRA is a non-invasive technique that requires no contrast, does not expose the patient to ionizing radiation, and allows to change the position of the patient's head easily. Since no hospitalization is required and contraindications are minimal (e.g., implanted pacemakers...), we believe that MRA constitutes and ideal screening technique to assess the vertebro basilar system. The results obtained and the advantages provided by MRA over Doppler-ultrasound and X-ray angiography are showed. PMID:7811505

  11. 75 FR 71701 - Science Advisory Board Staff Office; Request for Nominations of Experts for the Review of a Draft...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-24

    ... in common with chemical risk assessment the document addresses issues that are unique to MRA such as... Staff Office will consider nominations received in response to this FR Notice, members of the Science... Staff Office, a review panel includes candidates who possess the necessary domains of knowledge,...

  12. Adaptive Online Self-Gating (ADIOS) for Free-Breathing Noncontrast Renal MR Angiography

    PubMed Central

    Xie, Yibin; Fan, Zhaoyang; Saouaf, Rola; Natsuaki, Yutaka; Laub, Gerhard; Li, Debiao

    2014-01-01

    Purpose To develop a respiratory self-gating method, adaptive online self-gating (ADIOS), for noncontrast MR angiography (NC MRA) of renal arteries to overcome some limitations of current free-breathing methods. Methods A NC MRA pulse sequence for online respiratory self-gating was developed based on three-dimensional balanced steady-state free precession (bSSFP) and slab-selective inversion-recovery. Motion information was derived directly from the slab being imaged for online gating. Scan efficiency was maintained by an automatic adaptive online algorithm. Qualitative and quantitative assessments of image quality were performed and results were compared with conventional diaphragm navigator (NAV). Results NC MRA imaging was successfully completed in all subjects (n=15). Similarly good image quality was observed in the proximal–middle renal arteries with ADIOS compared with NAV. Superior image quality was observed in the middle-distal renal arteries in the right kidneys with no NAV-induced artifacts. Maximal visible artery length was significantly longer with ADIOS versus NAV in the right kidneys. NAV setup was completely eliminated and scan time was significantly shorter with ADIOS on average compared with NAV. Conclusion The proposed ADIOS technique for noncontrast MRA provides high-quality visualization of renal arteries with no diaphragm navigator-induced artifacts, simplified setup, and shorter scan time. PMID:24478221

  13. Questions and Answers about Carotid Endarterectomy

    MedlinePlus

    ... noninvasive test in which sound waves above the range of human hearing are sent into the neck. Echoes bounce off the moving blood and the tissue in the artery and can be formed into an image. Ultrasound is fast, risk-free, relatively inexpensive, and painless compared to MRA and ...

  14. USEPA EXAMPLE EXIT LEVEL ANALYSIS RESULTS

    EPA Science Inventory

    Developed by NERL/ERD for the Office of Solid Waste, the enclosed product provides an example uncertainty analysis (UA) and initial process-based sensitivity analysis (SA) of hazardous waste "exit" concentrations for 7 chemicals and metals using the 3MRA Version 1.0 Modeling Syst...

  15. Vascular disease.

    PubMed

    Amlie-Lefond, Catherine; Shaw, Dennis

    2016-01-01

    The child presenting with possible sentinel transient ischemic event or stroke requires prompt diagnosis so that strategies to limit injury and prevent recurrent stroke can be instituted. Cerebral arteriopathy is a potent risk factor for arterial ischemic stroke in childhood. Though acute imaging study in the setting of possible stroke is often a head computed tomography, when possible magnetic resonance imaging (MRI) is recommended as the first-line study as confirmation and imaging evaluation of ischemic stroke will typically require MRI. The MRI scanning approach should include diffusion-weighted imaging (DWI) early in the sequence order, since normal DWI excludes acute infarct with rare exception. In most cases, arterial imaging with time-of-flight (TOF) magnetic resonance angiography (MRA) is warranted. Dedicated MRA may not be possible in the acute setting, but should be pursued as promptly as possible, particularly in the child with findings and history suggestive of arteriopathy, given the high risk of recurrent stroke in these children. MRA can overestimate the degree of arterial compromise due to complex/turbulent flow, and be insensitive to subtle vessel irregularity due to resolution and complex flow. In cases with high imaging suspicion for dissection despite normal MRA findings, catheter angiogram is indicated. A thoughtful, stepwise approach to arterial neuroimaging is critical to optimize diagnosis, treatment, and primary and secondary prevention of childhood stroke. PMID:27430463

  16. 75 FR 82228 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-30

    ... Center, 6500 South MacArthur Blvd., Oklahoma City, OK 73169 (Mail Address: P.O. Box 25082 Oklahoma City... ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does... Federal Airway V5 Is Amended To Read in Part Shirt, OH FIX *Gloom, OH FIX 3000 *4000--MRA *Gloom, OH...

  17. Role of Waterborne Pathogens in the Food Supply Chain: Implications to Risk Management with Local and Global Perspectives

    EPA Science Inventory

    Microbial risk assessment (MRA) in the food industry is used to support HACCP – which largely focuses on bacterial pathogen control in processing foodstuffs Potential role of microbially-contaminated water used in food production is not as well understood Emergence...

  18. 21 CFR 26.0 - General.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false General. 26.0 Section 26.0 Food and Drugs FOOD AND... modification is done for purposes of clarity only and shall not affect the text of the MRA concluded between... part is relevant only to the Food and Drug Administration's (FDA's) implementation of the...

  19. 21 CFR 26.0 - General.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false General. 26.0 Section 26.0 Food and Drugs FOOD AND... modification is done for purposes of clarity only and shall not affect the text of the MRA concluded between... part is relevant only to the Food and Drug Administration's (FDA's) implementation of the...

  20. 21 CFR 26.0 - General.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false General. 26.0 Section 26.0 Food and Drugs FOOD AND... modification is done for purposes of clarity only and shall not affect the text of the MRA concluded between... part is relevant only to the Food and Drug Administration's (FDA's) implementation of the...

  1. Transient Mesenteric Ischemia Leads to Remodeling of Rat Mesenteric Resistance Arteries

    PubMed Central

    Caracuel, Laura; Jiménez-Altayó, Francesc; Romo, Mónica; Márquez-Martín, Ana; Dantas, Ana P.; Vila, Elisabet

    2012-01-01

    Mesenteric ischemia/reperfusion (I/R) is associated with high rates of morbidity and mortality. We studied the effect of mesenteric I/R on structural and mechanical properties of rat mesenteric resistance artery (MRA) that, once disrupted, might impact the outcome of this devastating clinical condition. Superior mesenteric artery from Wistar–Kyoto rats was occluded (90 min) and reperfused (24 h). The effect of tezosentan, a dual endothelin (ET)-receptor antagonist, was studied in ischemic (IO) and sham-operated (SO) animals. MRA structure and mechanics were assessed by pressure myography. Nuclei distribution, elastin content and organization, collagen I/III and ET-1 expression, ET-1 plasma levels, superoxide anion (O2⋅−) production, and mRNA levels of NAD(P)H-oxidase subunits were measured. To assess ET-1 effects on O2⋅− production, MRA from non-operated rats were incubated in culture medium with ET-1. Mesenteric I/R increased MRA wall thickness (P < 0.05) and cross-sectional area (P < 0.05) but decreased wall stiffness (P < 0.05). Arterial remodeling was paralleled by enhancement of: (i) collagen I/III expression (P < 0.01), ET-1 expression (P < 0.05), and O2⋅− formation (P < 0.01) in the vessel wall; (ii) number of internal elastic lamina (IEL) fenestrae (P < 0.05); and (iii) plasma levels of ET-1 (P < 0.05). Moreover, ET-1 increased O2⋅− (P < 0.05) production in cultured MRA. Tezosentan prevented hypertrophic remodeling and collagen I/III deposition, and enhanced O2⋅− production, but it did not affect the decreased wall stiffness after mesenteric I/R. These results indicate that 90 min occlusion/24 h reperfusion induces hypertrophic remodeling of MRA linked to ET-1-mediated increase of collagen and O2⋅−. Decreased stiffness may be associated with increased number of IEL fenestrae. The resulting MRA remodeling, initially adaptive, might become maladaptive contributing to the pathology and poor

  2. Application of sub-image multiresolution analysis of Ground-penetrating radar data in a study of shallow structures

    NASA Astrophysics Data System (ADS)

    Jeng, Yih; Lin, Chun-Hung; Li, Yi-Wei; Chen, Chih-Sung; Yu, Hung-Ming

    2011-03-01

    Fourier-based algorithms originally developed for the processing of seismic data are applied routinely in the Ground-penetrating radar (GPR) data processing, but these conventional methods of data processing may result in an abundance of spurious harmonics without any geological meaning. We propose a new approach in this study based essentially on multiresolution wavelet analysis (MRA) for GPR noise suppression. The 2D GPR section is similar to an image in all aspects if we consider each data point of the GPR section to be an image pixel in general. This technique is an image analysis with sub-image decomposition. We start from the basic image decomposition procedure using conventional MRA approach and establish the filter bank accordingly. With reasonable knowledge of data and noise and the basic assumption of the target, it is possible to determine the components with high S/N ratio and eliminate noisy components. The MRA procedure is performed further for the components containing both signal and noise. We treated the selected component as an original image and applied the MRA procedure again to that single component with a mother wavelet of higher resolution. This recursive procedure with finer input allows us to extract features or noise events from GPR data more effectively than conventional process. To assess the performance of the MRA filtering method, we first test this method on a simple synthetic model and then on experimental data acquired from a control site using 400 MHz GPR system. A comparison of results from our method and from conventional filtering techniques demonstrates the effectiveness of the sub-image MRA method, particularly in removing ringing noise and scattering events. Field study was carried out in a trenched fault zone where a faulting structure was present at shallow depths ready for understanding the feasibility of improving the data S/N ratio by applying the sub-image multiresolution analysis. In contrast to the conventional

  3. Value of Single-Dose Contrast-Enhanced Magnetic Resonance Angiography Versus Intraarterial Digital Subtraction Angiography in Therapy Indications in Abdominal and Iliac Arteries

    SciTech Connect

    Schaefer, Philipp J. Schaefer, Fritz K. W.; Mueller-Huelsbeck, Stefan; Both, Markus; Heller, Martin; Jahnke, Thomas

    2007-06-15

    The objective of the study was to prove the value of single-dose contrast-enhanced magnetic resonance angiography [three-dimensional (3D) ceMRA] in abdominal and iliac arteries versus the reference standard intra-arterial digital subtraction angiography (i.a.DSA) when indicating a therapy. Patients suspected of having abdominal or iliac artery stenosis were included in this study. A positive vote of the local Ethics Committee was given. After written informed consent was obtained, 37 patients were enrolled, of which 34 were available for image evaluation. Both 3D ceMRA and i.a. DSA were performed for each patient. The dosage for 3D ceMRA was 0.1 mmol/kg body weight in a 1.5-T scanner with a phased-array coil. The parameters of the 3D-FLASH sequence were as follows: TR/TE 4.6/1.8 ms, effective thickness 3.5 mm, matrix 512 x 200, flip angle 30{sup o}, field of view 420 mm, TA 23 s, coronal scan orientation. Totally, 476 vessel segments were evaluated for stenosis degree by two radiologists in a consensus fashion in a blinded read. For each patient, a therapy was proposed, if clinically indicated. Sensitivity, specificity, positive and negative predictive values, and accuracy for stenoses {>=}50% were 68%, 92%, 44%, 97%, and 90%, respectively. In 13/34 patients, a discrepancy was found concerning therapy decisions based on MRA findings versus therapy decisions based on the reference standard DSA. The results showed that the used MRA imaging technique of abdominal and iliac arteries is not competitive to i.a. DSA, with a high rate of misinterpretation of the MRAs resulting in incorrect therapies.

  4. Freestanding membrane composed of micro-ring array with ultrahigh sidewall aspect ratio for application in lightweight cathode arrays

    NASA Astrophysics Data System (ADS)

    Wang, Lanlan; Liu, Hongzhong; Jiang, Weitao; Gao, Wei; Chen, Bangdao; Li, Xin; Ding, Yucheng; An, Ningli

    2014-12-01

    A freestanding multilayer ultrathin nano-membrane (FUN-membrane) with a micro-ring array (MRA) is successfully fabricated through the controllable film deposition. Each micro-ring of FUN-membrane is 3 μm in diameter, 2 μm in height and sub-100 nm in sidewall thickness, demonstrating an ultrahigh sidewall aspect ratio of 20:1. In our strategy, a silica layer (200 nm in thickness), a chromium transition layer (5 nm-thick) and a gold layer (40 nm-thick), were in sequence deposited on patterned photoresist. After removal of the photoresist by lift-off process, a FUN-membrane with MRA was peeled off from the substrate, where the gold layer acted as a protecting layer to prevent the MRA from fracture. The FUN-membrane was then transferred to a flexible polycarbonate (PC) sheet coated with indium tin oxide (ITO) layer, which was then used as a flexible and lightweight cathode. Remarkably, the field emission effect of the fabricated FUN-membrane cathode performs a high field-enhancement factor of 1.2 × 104 and a low turn-on voltage of 2 V/μm, indicating the advantages of the sharp metal edge of MRA. Due to the rational design and material versatility, the FUN-membrane thus could be transferred to either rigid or flexible substrate, even curved surface, such as the skin of bio-robot's arm or leg. Additionally, the FUN-membrane composed of MRA with extremely high aspect ratio of insulator-metal sidewall, also provides potential applications in optical devices, lightweight and flexible display devices, and electronic eye imagers.

  5. Time-resolved contrast-enhanced MR angiography: Value of hemodynamic information in the assessment of vascular diseases

    PubMed Central

    Maj, Edyta; Cieszanowski, Andrzej; Rowiński, Olgierd; Wojtaszek, Mikołaj; Szostek, Małgorzata; Tworus, Robert

    2010-01-01

    Summary Background: To assess the quality of images obtained from time-resolved MRA together with the accuracy of this technique in diagnosing vascular diseases and the usefulness of haemodynamic information provided by this method. Material/Methods: The study group included 120 patients with different vascular pathologies excluding of intracranial vessels. All patients underwent time-resolved MRA on 1.5T unit. Results were correlated with other imaging techniques: DSA (n=36), CTA (n=28), Doppler ultrasound (n=71) and intraoperative findings (n=10). Independently, two radiologists evaluated the MRA studies assessing the quality of the images in a 3 point scale (3 – good, 1 – poor), as well as the presence or absence of haemodynamic information (3 – relevant dynamic information, 2 – irrelevant dynamic information, 1 – lack of dynamic information) for different vascular pathologies. Results: Mean quality of MRA examinations was 2.94 (reader A and B) and was similar for different pathologies (kappa value =0.757). The mean grading (reader A and B) for the presence of dynamic information was above 2 for the following pathologies: celiac artery branch pseudoaneurysm (3), vascular malformation (3), subclavian steal syndrome (2.5), Leriche’s syndrome (2.25), aortic dissection (2.06), renal artery stenosis (2.03); and below 2 for: pelvic arterial occlusive disease (1.75), abdominal aortic aneurysm (1.31), carotid artery stenosis (1.1), thoracic aortic aneurysm (1.0). Kappa value was 0.802. The sensitivity was 95%, specificity 96% and positive predictive value 98%. Conclusions: Time-resolved MRA provides good quality images and enables reliable diagnosis of vascular pathologies. PMID:22802762

  6. Low-dose Computed Tomography in a Pregnant Woman with a Ruptured Pseudoaneurysm of the Abdominal Aorta.

    PubMed

    Ramac, Jelena Popić; Vidjak, Vinko; Skegro, Dinko; Duić, Zeljko; Blasković, Darko; Erdelez, Lidija; Skopljanac-Macina, Andrija; Suknaić, Slaven; Slavica, Marko; Leder, Nikola Ivan

    2015-09-01

    Imaging the pregnant patient presents a unique challenge to radiologist due to the risk of radiation to the conceptus (embryo/fetus). A rare case of a successfully recognized and treated pseudoaneurysm (PA) of the abdominal aorta is to be presented. The pseudoaneurysm occurred in the third trimester and had a favorable outcome for the mother and the baby. Emergent abdominal ultrasound (US) is the first modality in diagnostic algorithm for the rupture of aortic aneurysm in a pregnant woman. It provides the most rapid diagnostic information, although intestinal gas and abdominal tenderness may limit its accuracy. To confirm the findings, magnetic resonance angiography (MRA) or CT angiography (CTA) can be used. In our case, the diagnosis was established using a color Doppler ultrasonography of the abdomen and was later confirmed by a low dose CT scan of the abdominal aorta. MRA in such cases have some disadvantages. At many health centers, the monitoring of patients with acute ruptures is more difficult in the MR suite than at the CT scanner. MRA angiographic images are also subject to degradation by multiple artifacts and the visualization of the distal vasculature is suboptimal and inferior to the one done by CTA. Due to fetal movements, a small quantity of fresh blood can be overlooked by MR. MRA is often not available on a 24-hours basis, and the time required for making a diagnosis can preclude the use of MRA in an unstable patient. For this reason, we used a low dose CTA protocol to confirm the diagnosis. Low dose scanning protocols in CT can obtain sufficient diagnostic information while reducing the risk of radiation. A particular focus is put on the outline of new concepts for dose management and optimization. We used new approaches based on tube current modulation. The birth was induced by an urgent Caesarean section followed by a resection of a pseudoaneurysm and a reconstruction of the aorta with an end-to-end vascular prosthesis. PMID:26898082

  7. Application of elements of microbiological risk assessment in the food industry via a tiered approach.

    PubMed

    van Gerwen, Suzanne J C; Gorris, Leon G M

    2004-09-01

    Food safety control is a matter for concern for all parts of the food supply chain, including governments that develop food safety policy, food industries that must control potential hazards, and consumers who need to keep to the intended use of the food. In the future, food safety policy may be set using the framework of risk analysis, part of which is the development of (inter)national microbiological risk assessment (MRA) studies. MRA studies increase our understanding of the impact of risk management interventions and of the relationships among subsequent parts of food supply chains with regard to the safety of the food when it reaches the consumer. Application of aspects of MRA in the development of new food concepts has potential benefits for the food industry. A tiered approach to applying MRA can best realize these benefits. The tiered MRA approach involves calculation of microbial fate for a product and process design on the basis of experimental data (e.g., monitoring data on prevalence) and predictive microbiological models. Calculations on new product formulations and novel processing technologies provide improved understanding of microbial fate beyond currently known boundaries, which enables identification of new opportunities in process design. The outcome of the tiered approach focuses on developing benchmarks of potential consumer exposure to hazards associated with new products by comparison with exposure associated with products that are already on the market and have a safe history of use. The tiered prototype is a tool to be used by experienced microbiologists as a basis for advice to product developers and can help to make safety assurance for new food concepts transparent to food inspection services. PMID:15453599

  8. Application of elements of microbiological risk assessment in the food industry via a tiered approach.

    PubMed

    van Gerwen, Suzanne J C; Gorris, Leon G M

    2004-09-01

    Food safety control is a matter for concern for all parts of the food supply chain, including governments that develop food safety policy, food industries that must control potential hazards, and consumers who need to keep to the intended use of the food. In the future, food safety policy may be set using the framework of risk analysis, part of which is the development of (inter)national microbiological risk assessment (MRA) studies. MRA studies increase our understanding of the impact of risk management interventions and of the relationships among subsequent parts of food supply chains with regard to the safety of the food when it reaches the consumer. Application of aspects of MRA in the development of new food concepts has potential benefits for the food industry. A tiered approach to applying MRA can best realize these benefits. The tiered MRA approach involves calculation of microbial fate for a product and process design on the basis of experimental data (e.g., monitoring data on prevalence) and predictive microbiological models. Calculations on new product formulations and novel processing technologies provide improved understanding of microbial fate beyond currently known boundaries, which enables identification of new opportunities in process design. The outcome of the tiered approach focuses on developing benchmarks of potential consumer exposure to hazards associated with new products by comparison with exposure associated with products that are already on the market and have a safe history of use. The tiered prototype is a tool to be used by experienced microbiologists as a basis for advice to product developers and can help to make safety assurance for new food concepts transparent to food inspection services.

  9. Magnetic Resonance Angiography of Nonferromagnetic Iliac Artery Stents and Stent-Grafts: A Comparative Study in Sheep

    SciTech Connect

    Schuermann, Karl; Vorwerk, Dierk; Buecker, Arno; Neuerburg, Joerg; Grosskortenhaus, Stefanie; Haage, Patrick; Piroth, Werner; Hunter, David W.; Guenther, Rolf W.

    1999-09-15

    Purpose: To compare nonferromagnetic iliac artery prostheses in their suitability for patency monitoring with magnetic resonance angiography (MRA) using conventional angiography as a reference. Methods: In experiment 1, three Memotherm stents were inserted into the iliac arteries of each of six sheep: two 'tandem' stents on one side and a single stent on the other side. In experiment 2, four prostheses (normal and low-porosity Corvita stent-grafts, Memotherm, ZA-stent) were inserted in each of 11 sheep. Patency was monitored before and 1, 3, and 6 months after insertion with 3D phase-contrast and two 2D time-of-flight sequences (TOF-1: TR/TE = 18/6.9, TOF-2: 13/2.5) with and without contrast at 1.5 T. On 206 coronal MIP images (72 pre-, 134 post-stenting), three readers analyzed 824 iliac segments (206 x 4) for patency and artifacts. Results: There was no difference in the number of artifacts between tandem and single iliac Memotherm stents. The ZA-stent induced significantly fewer artifacts than the other prostheses (p < 0.00001). With MRA, patency of the ZA-stent was correctly diagnosed in 88% of cases, which was almost comparable to nonstented iliac segments (95%), patency of the Memotherm stent in 59%, and of the Corvita stent-grafts in 57% and 55%. The TOF-2 sequence with contrast yielded the best images. Conclusion: MRA compatibility of nonferromagnetic prostheses depends strongly on the design of the device. MRA may be used to monitor the patency of iliac ZA-stents, whereas iliac Memotherm stents and Corvita stent-grafts appear to be less suited for follow-up with MRA.

  10. Prognostic value of cardiovascular MR imaging biomarkers on outcome in peripheral arterial disease: a 6-year follow-up pilot study.

    PubMed

    van den Bosch, Harrie; Westenberg, Jos; Setz-Pels, Wikke; Kersten, Erik; Tielbeek, Alexander; Duijm, Lucien; Post, Johannes; Teijink, Joep; de Roos, Albert

    2016-08-01

    The objective of this pilot study was to explore the prognostic value of outcome of cardiovascular magnetic resonance (MR) imaging biomarkers in patients with symptomatic peripheral arterial disease (PAD) in comparison with traditional risk factors. Forty-two consecutive patients (mean age 64 ± 11 years, 22 men) referred for contrast-enhanced MR angiography (CE-MRA) were included. At baseline a comprehensive cardiovascular MRI examination was performed: CE-MRA of the infra-renal aorta and run-off vessels, carotid vessel wall imaging, cardiac cine imaging and aortic pulse wave velocity (PWV) assessment. Patients were categorized for outcome at 72 ± 5 months follow-up. One patient was lost to follow-up. Over 6 years, six patients had died (mortality rate 14.6 %), six patients (14.6 %) had experienced a cardiac event and three patients (7.3 %) a cerebral event. The mean MRA stenosis class (i.e., average stenosis severity visually scored over 27 standardized segments) was a significant independent predictor for all-cause mortality (beta 3.0 ± standard error 1.3, p = 0.02). Descending aorta PWV, age and diabetes mellitus were interrelated with stenosis severity but none of these were significant independent predictors. For cardiac morbidity, left ventricular ejection fraction (LVEF) and mean MRA stenosis class were associated, but only LVEF was a significant independent predictor (beta -0.14 ± 0.05, p = 0.005). Diabetes mellitus was a significant independent predictor for cerebral morbidity (beta 2.8 ± 1.3, p = 0.03). Significant independent predictors for outcome in PAD are mean MRA stenosis class for all-cause mortality, LVEF for cardiac morbidity and diabetes mellitus for cerebral morbidity. PMID:27209283

  11. First step in using molecular data for microbial food safety risk assessment; hazard identification of Escherichia coli O157:H7 by coupling genomic data with in vitro adherence to human epithelial cells

    PubMed Central

    Pielaat, Annemarie; Boer, Martin P.; Wijnands, Lucas M.; van Hoek, Angela H.A.M.; Bouw, El; Barker, Gary C.; Teunis, Peter F.M.; Aarts, Henk J.M.; Franz, Eelco

    2015-01-01

    The potential for using whole genome sequencing (WGS) data in microbiological risk assessment (MRA) has been discussed on several occasions since the beginning of this century. Still, the proposed heuristic approaches have never been applied in a practical framework. This is due to the non-trivial problem of mapping microbial information consisting of thousands of loci onto a probabilistic scale for risks. The paradigm change for MRA involves translation of multidimensional microbial genotypic information to much reduced (integrated) phenotypic information and onwards to a single measure of human risk (i.e. probability of illness). In this paper a first approach in methodology development is described for the application of WGS data in MRA; this is supported by a practical example. That is, combining genetic data (single nucleotide polymorphisms; SNPs) for Shiga toxin-producing Escherichia coli (STEC) O157 with phenotypic data (in vitro adherence to epithelial cells as a proxy for virulence) leads to hazard identification in a Genome Wide Association Study (GWAS). This application revealed practical implications when using SNP data for MRA. These can be summarized by considering the following main issues: optimum sample size for valid inference on population level, correction for population structure, quantification and calibration of results, reproducibility of the analysis, links with epidemiological data, anchoring and integration of results into a systems biology approach for the translation of molecular studies to human health risk. Future developments in genetic data analysis for MRA should aim at resolving the mapping problem of processing genetic sequences to come to a quantitative description of risk. The development of a clustering scheme focusing on biologically relevant information of the microbe involved would be a useful approach in molecular data reduction for risk assessment. PMID:25910947

  12. Imaging blood vessels of the head and neck.

    PubMed Central

    Sellar, R J

    1995-01-01

    ATHEROSCLEROTIC DISEASE: Patients with transient ischaemic attacks or a non-disabling stroke who are surgical candidates should be screened with Doppler ultrasound, or MRA/CT, or both. The choice will depend on local expertise and availability. If DUS is used it is recommended that the equipment is regularly calibrated and a prospective audit of results, particularly of those patients that go on to angiography, is maintained locally. Those patients found to have the DUS equivalent of a 50% stenosis should have angiography only if surgical or balloon angioplasty treatment is contemplated. Angiography should be performed with meticulous technique to minimise risks. ANEURYSM AND ARTERIOVENOUS MALFORMATIONS: Angiography remains the investigation of choice for patients with subarachnoid haemorrhage. Magnetic resonance angiography and CT can demonstrate the larger aneurysm but because even small aneurysms can rupture with devastating effects, these techniques are not the examination of first choice. Angiography is also the only technique that adequately defines the neck of an aneurysm. This information is becoming increasingly important in management decisions-for instance, whether to clip or use a coil. Likewise angiography is the only technique to fully define the vascular anatomy of arteriovenous malformations although the size of the nidus can be monitored by MRA and this is a useful method of follow up after stereotactic radiosurgery, embolisation, or surgery. There are specific uses for MRA such as in patients presenting with a painful 3rd nerve palsy and as a screening test for those patients with a strong family history of aneurysms. VASCULITIS, FIBROMUSCULAR HYPERPLASIA, AND DISSECTION: These rare arterial diseases are best detected by angiography, although there are increasing reports of successful diagnosis by MRA. There are traps for the many unwary and MRA does not give an anatomical depiction of the arteries but a flow map. Slow flow may lead to signal loss

  13. First step in using molecular data for microbial food safety risk assessment; hazard identification of Escherichia coli O157:H7 by coupling genomic data with in vitro adherence to human epithelial cells.

    PubMed

    Pielaat, Annemarie; Boer, Martin P; Wijnands, Lucas M; van Hoek, Angela H A M; Bouw, El; Barker, Gary C; Teunis, Peter F M; Aarts, Henk J M; Franz, Eelco

    2015-11-20

    The potential for using whole genome sequencing (WGS) data in microbiological risk assessment (MRA) has been discussed on several occasions since the beginning of this century. Still, the proposed heuristic approaches have never been applied in a practical framework. This is due to the non-trivial problem of mapping microbial information consisting of thousands of loci onto a probabilistic scale for risks. The paradigm change for MRA involves translation of multidimensional microbial genotypic information to much reduced (integrated) phenotypic information and onwards to a single measure of human risk (i.e. probability of illness). In this paper a first approach in methodology development is described for the application of WGS data in MRA; this is supported by a practical example. That is, combining genetic data (single nucleotide polymorphisms; SNPs) for Shiga toxin-producing Escherichia coli (STEC) O157 with phenotypic data (in vitro adherence to epithelial cells as a proxy for virulence) leads to hazard identification in a Genome Wide Association Study (GWAS). This application revealed practical implications when using SNP data for MRA. These can be summarized by considering the following main issues: optimum sample size for valid inference on population level, correction for population structure, quantification and calibration of results, reproducibility of the analysis, links with epidemiological data, anchoring and integration of results into a systems biology approach for the translation of molecular studies to human health risk. Future developments in genetic data analysis for MRA should aim at resolving the mapping problem of processing genetic sequences to come to a quantitative description of risk. The development of a clustering scheme focusing on biologically relevant information of the microbe involved would be a useful approach in molecular data reduction for risk assessment. PMID:25910947

  14. Recurrent Congenital Diaphragmatic Hernia in Ehlers-Danlos Syndrome

    SciTech Connect

    Lin, I.C.; Ko, S.F.; Shieh, C.S.; Huang, C.F.; Chien, S.J.; Liang, C.D.

    2006-10-15

    Ehlers-Danlos syndrome (EDS) includes a group of connective tissue disorders with abnormal collagen metabolism and a diverse clinical spectrum. We report two siblings with EDS who both presented with congenital diaphragmatic hernia (CDH). The elder sister suffered from recurrent diaphragmatic hernia twice and EDS was overlooked initially. Echocardiography as well as contrast-enhanced magnetic resonance angiography (MRA) showed dilatation of the pulmonary artery, and marked elongation and tortuosity of the aorta and its branches. A diagnosis of EDS was eventually established when these findings were coupled with the clinical features of hyperelastic skin. Her younger brother also had similar features. This report emphasizes that EDS may present as CDH in a small child which could easily be overlooked. Without appropriate surgery, diaphragmatic hernia might occur. Echocardiographic screening is recommended in patients with CDH. Contrast-enhanced MRA can be helpful in delineation of abnormally tortuous aortic great vessels that are an important clue to the early diagnosis of EDS.

  15. Characterization of vascular tree architecture using the Tokunaga taxonomy

    NASA Astrophysics Data System (ADS)

    Galarreta-Valverde, Miguel A.; Zoghbi, Jihan M.; Pereira, Fabricio; Beregi, Jean-Paul; Mekkaoui, Choukri; Jackowski, Marcel P.

    2015-03-01

    The diagnosis of cardiovascular disease is usually assisted by resonance angiography (MRA) or computed tomography angiography (CTA) imaging. The identification of abnormal vascular architecture from angiographic three-dimensional images is therefore crucial to the diagnosis of cardiovascular disease. Automated detection and quantification of vascular structure and architecture thus holds significant clinical value. In this work, we employ a Lindenmayer system to represent vascular trees from angiographic images and describe a quantitative measure based on the Tokunaga taxonomy to differentiate vascular architectures. Synthetic vessel architectures with varying bifurcation patterns were compared and results showed that this architectural measure is proportional to the level of branching. In real MRA images, this measure was able to differentiate between normal and abnormal intracerebral vasculature containing an aneurysm. Hence, this methodology not only allows for compact representation of vascular architectures but also provides a quantitative metric of bifurcation complexity, which has the potential to characterize different types of vascular abnormalities.

  16. [Non-contrast time-resolved magnetic resonance angiography combining high resolution multiple phase echo planar imaging based signal targeting and alternating radiofrequency contrast inherent inflow enhanced multi phase angiography combining spatial resolution echo planar imaging based signal targeting and alternating radiofrequency in intracranial arteries].

    PubMed

    Nakamura, Masanobu; Yoneyama, Masami; Tabuchi, Takashi; Takemura, Atsushi; Obara, Makoto; Sawano, Seishi

    2012-01-01

    Detailed information on anatomy and hemodynamics in cerebrovascular disorders such as AVM and Moyamoya disease is mandatory for defined diagnosis and treatment planning. Arterial spin labeling technique has come to be applied to magnetic resonance angiography (MRA) and perfusion imaging in recent years. However, those non-contrast techniques are mostly limited to single frame images. Recently we have proposed a non-contrast time-resolved MRA technique termed contrast inherent inflow enhanced multi phase angiography combining spatial resolution echo planar imaging based signal targeting and alternating radiofrequency (CINEMA-STAR). CINEMA-STAR can extract the blood flow in the major intracranial arteries at an interval of 70 ms and thus permits us to observe vascular construction in full by preparing MIP images of axial acquisitions with high spatial resolution. This preliminary study demonstrates the usefulness of the CINEMA-STAR technique in evaluating the cerebral vasculature.

  17. Early middle cerebral artery stenosis following stent-assisted thrombectomy

    PubMed Central

    Akpınar, Süha

    2015-01-01

    Stent-assisted thrombectomy (SAT) is an extensively used endovascular treatment method for stroke in which the thrombectomy stents come into direct contact with the vascular intimal surface and entrap the thrombus causing the arterial occlusion. Although there are a few studies that demonstrate that the vessel wall changes in the arteries where stroke intervention is performed, we observed progressive stenosis in early follow-up imaging studies in a case. We present a middle cerebral artery (MCA) stroke patient who had four repetitive stent passes during SAT and developed distal MCA stenosis 2 months after SAT at the control magnetic resonance angiography (MRA). Inclusion of early follow-up MRA studies would be helpful in defining the silent vascular changes in patients who have undergone repetitive SAT. PMID:26015531

  18. [Evaluation of the right internal iliac artery which is anastomosed to transplant renal artery using non-contrast enhanced MR angiography with electrocardiography-gated and 3D True SSFP time-spatial labeling inversion pulse sequence].

    PubMed

    Yoshida, Ayako; Shiratori, Yoko; Suzuki, Makoto; Ozasa, Masaya; Takeyama, Mamoru; Eshima, Mitsuhiro; Shinohara, Maiko; Yamamoto, Takao; Tajima, Tsuyoshi

    2015-05-01

    To evaluate whether electrocardiography-gated is useful in non-contrast-enhanced MRA with time-spatial labeling inversion pulse (Time-SLIP) in renal transplantation patients compared with respiration-triggered free-breathing. Simulation-based analyses of black blood time interval (BBTI) values for spatial selective inversion-recovery pulse and electrocardiography rates were performed, and confirmed on human subjects using a three-dimensional (3D) coherent steady-state free precession (SSFP) sequence on a 1.5 tesla Toshiba MRI scanner. Signal acquisition interval and BBTI values in which signal of a water tissue becomes the null point showed a strong correlation, and successfully suppressed signals from the background and provided better contrast between the arteries and the background. Because electrocardiography-gated non-contrast MRA does not depend on the respiration interval, providing a contrast stable, it was suggested to be an effective screening tool for evaluation of pelvic arteries.

  19. Integrated photonic reservoir computing based on hierarchical time-multiplexing structure.

    PubMed

    Zhang, Hong; Feng, Xue; Li, Boxun; Wang, Yu; Cui, Kaiyu; Liu, Fang; Dou, Weibei; Huang, Yidong

    2014-12-15

    An integrated photonic reservoir computing (RC) based on hierarchical time-multiplexing structure is proposed by numerical simulations. A micro-ring array (MRA) is employed as a typical time delay implementation of RC. At the output port of the MRA, a secondary time-multiplexing is achieved by multi-mode interference (MMI) splitter and delay line array. This hierarchical time-multiplexing structure can ensure a large reservoir size with fast processing speed. Simulation results indicate that the proposed RC system yields better performance than previously reported ones. The achieved normalized mean square error between the system output and target sequence are 0.5% and 2.7% for signal classification and chaotic time series prediction, respectively, while the sample rate is as high as 1.3 Gbps.

  20. Contrast enhanced ultrasonography versus MR angiography in aortocaval fistula: case report.

    PubMed

    Bhatia, Mona; Platon, Alexandra; Khabiri, Ebrahim; Becker, Christoph; Poletti, Pierre-Alexandre

    2010-06-01

    Aortocaval fistula (ACF) is a rare, life threatening complication of abdominal aortic aneurysms. Time to diagnosis is crucial as preoperative diagnosis and early surgical intervention significantly improve the outcome. The clinical spectrum being varied, the challenge of prompt and reliable diagnosis rests on emergency radiology. While the gold standard for detecting ACF today is CT angiography (CTA), frequently complicating renal insufficiency discourages the use of iodinated contrast making MR angiography (MRA) a useful alternative. Contrast enhanced ultrasound (CEUS) provides a promising new diagnostic option allowing rapid, non invasive and bedside diagnosis, especially in hemodynamically unstable patients. We present a case of prompt diagnosis of ACF by CEUS in comparison to modern MRA, thus establishing the new potential role of CEUS.

  1. Vertebral artery dissection in evolution found during chiropractic examination.

    PubMed

    Futch, Dan; Schneider, Michael J; Murphy, Donald; Grayev, Allison

    2015-01-01

    A 30-year-old woman presented to an emergency department with sudden onset of transient loss of left peripheral vision. Owing to a history of migraine headaches, she was released with a diagnosis of ocular migraine. Two days later, she sought chiropractic care for the chief symptom of severe neck pain. The chiropractor suspected the possibility of vertebral artery dissection (VAD). No manipulation was performed; instead, MR angiography (MRA) of the neck was obtained, which revealed an acute left VAD with early thrombus formation. The patient was placed on aspirin therapy. Repeat MRA of the neck 3 months later revealed resolution of the thrombus, without progression to stroke. This case illustrates the importance for all healthcare providers who see patients with neck pain and headache to be attentive to the symptomatic presentation of possible VAD in progress. PMID:26564115

  2. SIM.EM-K3 Key comparison of 10 mH inductance standards at 1 kHz

    NASA Astrophysics Data System (ADS)

    Moreno, J. A.; Côté, M.; Koffman, A.; Castro, B. I.; Vasconcellos, R. de Barros e.; Kyriazis, G.; Cazabat, M.; Izquierdo, D.; Faverio, C.; Slomovitz, D.

    2016-01-01

    A key comparison of 10 mH inductance standards at 1 kHz has been carried out with the participation of seven National Metrology Institutes of the Inter-American Metrology System, within the frame of the International Committee for Weights and Measures Mutual Recognition Arrangement (MRA), which was piloted by CENAM, Mexico. Three previously characterized commercial inductors, contained in individual enclosures with controlled temperature were used as traveling standards. This document presents the results and technical details of the comparison. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  3. Interleaved Variable Density Sampling with a Constrained Parallel Imaging Reconstruction for Dynamic Contrast-Enhanced MR Angiography

    PubMed Central

    Wang, Kang; Busse, Reed F.; Holmes, James H.; Beatty, Philip J.; Brittain, Jean H.; Francois, Christopher J.; Reeder, Scott B.; Du, Jiang; Korosec, Frank R.

    2012-01-01

    For MR applications such as contrast-enhanced MR angiography (CE-MRA), it is desirable to achieve simultaneously high spatial and temporal resolution. The current clinical standard uses view sharing methods combined with parallel imaging; however this approach still provides limited spatial and temporal resolution. To improve on the clinical standard, we present an Interleaved Variable Density (IVD) sampling method that pseudorandomly undersamples each individual frame of a 3D Cartesian ky-kz plane combined with parallel imaging acceleration. From this data set, time-resolved images are reconstructed with a method that combines parallel imaging with a multiplicative constraint. Total acceleration factors on the order of 20 are achieved for CE-MRA of the lower extremities, and improvements in temporal fidelity of the depiction of the contrast bolus passage are demonstrated relative to the clinical standard. PMID:21360740

  4. Real-time blood circulation and bleeding model for surgical training.

    PubMed

    Boisvert, Jonathan; Poirier, Guillaume; Borgeat, Louis; Godin, Guy

    2013-04-01

    Intraoperative management of bleeding is a critical skill all surgeons must possess. It is, however, very challenging to create a safe and realistic learning environment for its acquisition. In this paper, we propose a simple and efficient approach to integrate blood circulation to computerized surgical simulation systems and allow for real-time processing of punctures, ruptures, and cauterization of blood vessels. Blood pressures and flows are calculated using a system of ordinary differential equations, which can be simulated very efficiently. The equation system itself is constructed using a graph of the vessels' connectivity extracted from magnetic resonance angiograms (MRA) and completed with virtual vessels deduced from the principle of minimum work. Real-time performances of the method are assessed and results are demonstrated on ten patients who underwent a MRA before removal of a brain tumor.

  5. A system to detect cerebral aneurysms in multimodality angiographic data sets

    SciTech Connect

    Hentschke, Clemens M. Tönnies, Klaus D.; Beuing, Oliver; Paukisch, Harald; Scherlach, Cordula; Skalej, Martin

    2014-09-15

    Purpose: The early detection of cerebral aneurysms plays a major role in preventing subarachnoid hemorrhage. The authors present a system to automatically detect cerebral aneurysms in multimodal 3D angiographic data sets. The authors’ system is parametrizable for contrast-enhanced magnetic resonance angiography (CE-MRA), time-of-flight magnetic resonance angiography (TOF-MRA), and computed tomography angiography (CTA). Methods: Initial volumes of interest are found by applying a multiscale sphere-enhancing filter. Several features are combined in a linear discriminant function (LDF) to distinguish between true aneurysms and false positives. The features include shape information, spatial information, and probability information. The LDF can either be parametrized by domain experts or automatically by training. Vessel segmentation is avoided as it could heavily influence the detection algorithm. Results: The authors tested their method with 151 clinical angiographic data sets containing 112 aneurysms. The authors reach a sensitivity of 95% with CE-MRA data sets at an average false positive rate per data set (FP{sub DS}) of 8.2. For TOF-MRA, we achieve 95% sensitivity at 11.3 FP{sub DS}. For CTA, we reach a sensitivity of 95% at 22.8 FP{sub DS}. For all modalities, the expert parametrization led to similar or better results than the trained parametrization eliminating the need for training. 93% of aneurysms that were smaller than 5 mm were found. The authors also showed that their algorithm is capable of detecting aneurysms that were previously overlooked by radiologists. Conclusions: The authors present an automatic system to detect cerebral aneurysms in multimodal angiographic data sets. The system proved as a suitable computer-aided detection tool to help radiologists find cerebral aneurysms.

  6. Maximal and submaximal mouth opening with mouth gags in cats: implications for maxillary artery blood flow.

    PubMed

    Martin-Flores, M; Scrivani, P V; Loew, E; Gleed, C A; Ludders, J W

    2014-04-01

    The use of spring-loaded mouth gags in cats can be associated with the development of central neurological deficits, including blindness. In this species, the maxillary arteries are the main source of blood supply to the retinae and brain. Spring-loaded gags generate constant force after placement that could contribute to bulging of the soft tissues between the mandible and the tympanic bulla. Under these circumstances, the maxillary arteries can become compressed as they course between these osseous structures. Smaller gags that might apply less force to the mouth were investigated to determine if they preserved maxillary artery blood flow. Six healthy adult cats were anesthetized. Electroretinography (ERG) and magnetic resonance angiography (MRA) were performed without the use of a mouth gag and during submaximal (plastic mouth gags of 20, 30 and 42 mm in length between canine teeth) and maximal mouth opening. Maximal mouth opening produced alterations in ERG waveforms consistent with circulatory compromise in 1/6 cats and reductions in signal intensity during MRA in 4/6 cats. Placement of a 42 mm plastic gag produced a reduction in MRA signal in 1/6 cats. No changes were observed with smaller gags. The force applied against the mouth was significantly higher with the spring-loaded gag than with any other gags. The use of a smaller mouth gags was associated with fewer alterations of indicators of maxillary artery blood flow. Nevertheless, a 42 mm plastic gag, equivalent to the size of a needle cap, resulted in an abnormal MRA in one cat.

  7. Consultative committee on ionizing radiation: Impact on radionuclide metrology.

    PubMed

    Karam, L R; Ratel, G

    2016-03-01

    In response to the CIPM MRA, and to improve radioactivity measurements in the face of advancing technologies, the CIPM's consultative committee on ionizing radiation developed a strategic approach to the realization and validation of measurement traceability for radionuclide metrology. As a consequence, measurement institutions throughout the world have devoted no small effort to establish radionuclide metrology capabilities, supported by active quality management systems and validated through prioritized participation in international comparisons, providing a varied stakeholder community with measurement confidence. PMID:26688351

  8. Vertebral artery stenting by using coronary intervention techniques and devices.

    PubMed

    Kilic, Harun; Balci, Mustafa; Akdemir, Ramazan

    2009-04-01

    Atherosclerotic disease of the vertebro/basilar vessels is an important cause of posterior circulation infarction. Commonly, the primary atheroma forms at the origin of the vertebral arteries. Although initial treatment is medical, arch and four-vessel studies (CTA, MRA, or DSA) are warranted if symptoms continue. Endovascular management of vertebral artery stenosis might be highlighted as a good option in selected patients. This is a case of endoluminal stenting of vertebral artery with a durable result. PMID:19476126

  9. Multi-reference-based multiple alignment statistics enables accurate protein-particle pickup from noisy images.

    PubMed

    Kawata, Masaaki; Sato, Chikara

    2013-04-01

    Data mining from noisy data/images is one of the most important themes in modern science and technology. Statistical image processing is a promising technique for analysing such data. Automation of particle pickup from noisy electron micrographs is essential, especially when improvement of the resolution of single particle analysis requires a huge number of particle images. For such a purpose, reference-based matching using primary three-dimensional (3D) model projections is mainly adopted. In the matching, however, the highest peaks of the correlation may not accurately indicate particles when the image is very noisy. In contrast, the density and the heights of the peaks should reflect the probability distribution of the particles. To statistically determine the particle positions from the peak distributions, we have developed a density-based peak search followed by a peak selection based on average peak height, using multi-reference alignment (MRA). Its extension, using multi-reference multiple alignment (MRMA), was found to enable particle pickup at higher accuracy even from extremely noisy images with a signal-to-noise ratio of 0.001. We refer to these new methods as stochastic pickup with MRA (MRA-StoPICK) or with MRMA (MRMA-StoPICK). MRMA-StoPICK has a higher pickup accuracy and furthermore, is almost independent of parameter settings. They were successfully applied to cryo-electron micrographs of Rice dwarf virus. Because current computational resources and parallel data processing environments allow somewhat CPU-intensive MRA-StoPICK and MRMA-StoPICK to be performed in a short period, these methods are expected to allow high-resolution analysis of the 3D structure of particles.

  10. Neurovascular study of the trigeminal nerve at 3 t MRI.

    PubMed

    Docampo, Jorge; Gonzalez, Nadia; Muñoz, Alexandra; Bravo, Fernando; Sarroca, Daniel; Morales, Carlos

    2015-02-01

    This study aimed to show a novel visualization method to investigate neurovascular compression of the trigeminal nerve (TN) using a volume-rendering fusion imaging technique of 3D fast imaging employing steady-state acquisition (3D FIESTA) and coregistered 3D time of flight MR angiography (3D TOF MRA) sequences, which we called "neurovascular study of the trigeminal nerve". We prospectively studied 30 patients with unilateral trigeminal neuralgia (TN) and 50 subjects without symptoms of TN (control group), on a 3 Tesla scanner. All patients were assessed using 3D FIESTA and 3D TOF MRA sequences centered on the pons, as well as a standard brain protocol including axial T1, T2, FLAIR and GRE sequences to exclude other pathologies that could cause TN. Post-contrast T1-weighted sequences were also performed. All cases showing arterial imprinting on the trigeminal nerve (n = 11) were identified on the ipsilateral side of the pain. No significant relationship was found between the presence of an artery in contact with the trigeminal nerve and TN. Eight cases were found showing arterial contact on the ipsilateral side of the pain and five cases of arterial contact on the contralateral side. The fusion imaging technique of 3D FIESTA and 3D TOF MRA sequences, combining the high anatomical detail provided by the 3D FIESTA sequence with the 3D TOF MRA sequence and its capacity to depict arterial structures, results in a tool that enables quick and efficient visualization and assessment of the relationship between the trigeminal nerve and the neighboring vascular structures.

  11. Influence of 1.5-Tesla intraoperative MR imaging on surgical decision making.

    PubMed

    Hall, W A; Liu, H; Maxwell, R E; Truwit, C L

    2003-01-01

    To determine the frequency that high-field magnetic resonance (MR) imaging sequences influenced surgical decision making during intraoperative MR-guided surgery. From January 1997 to February 2001, 346 MR-guided procedures were performed using a 1.5-Tesla MR system (NT-ACS, Philips Medical Systems). This system can perform functional MR imaging (fMRI), diffusion weighted imaging (DWI), MR spectroscopy (MRS), MR angiography (MRA), and MR venography (MRV) in addition to T1-weighted, T2-weighted, and turbo FLAIR (fluid-attenuated inversion recovery) imaging. FMRI was used to determine areas of brain activation for language, motor function, and memory. DWI was utilized after tumor resection to exclude cerebral ischemia or infarction. MRS was obtained to identify areas of elevated choline that were suspected to correlate with tumor presence. MRA and MRV localized vascular structures adjacent to tumors prior to resection. The intraoperative procedures performed included 140 brain biopsies of which 82 utilized a trajectory guide and prospective stereotaxy. MRS was used in 42 biopsies (30%), of which 29 had turbo spectroscopic imaging (TSI) and 21 had single voxel spectroscopy (SVS). In all biopsy cases, diagnostic tissue was obtained. There were 103 tumor resections of which 18 (17%) had MRS. Functional MRI was used in 17 cases; 3 biopsies (2%) and 14 planned resections (14%). Speech function was localized in 3 cases, memory function in 3, and motor function in 11. In one case where the motor function of the tongue was intimately involved with a low-grade glioma, resection was not attempted. DWI was used in less than 10% of tumor resections. MRA and MRV were performed in 3 (3%) and 2 (2%) of tumor resections, respectively. The imaging capabilities (i.e., fMRI, DWI, MRA, MRV) associated with high-field intraoperative MR influenced surgical decision making primarily for tumor resections. MRS influenced target selection during brain biopsy.

  12. Different β-adrenoceptor subtypes coupling to cAMP or NO/cGMP pathways: implications in the relaxant response of rat conductance and resistance vessels

    PubMed Central

    Flacco, N; Segura, V; Perez-Aso, M; Estrada, S; Seller, JF; Jiménez-Altayó, F; Noguera, MA; D'Ocon, P; Vila, E; Ivorra, MD

    2013-01-01

    Background and Purpose To analyse the relative contribution of β1-, β2- and β3-adrenoceptors (Adrb) to vasodilatation in conductance and resistance vessels, assessing the role of cAMP and/or NO/cGMP signalling pathways. Experimental Approach Rat mesenteric resistance artery (MRA) and aorta were used to analyse the Adrb expression by real-time-PCR and immunohistochemistry, and for the pharmacological characterization of Adrb-mediated activity by wire myography and tissue nucleotide accumulation. Key Results The mRNAs and protein for all Adrb were identified in endothelium and/or smooth muscle cells (SMCs) in both vessels. In MRA, Adrb1 signalled through cAMP, Adrb3 through both cAMP and cGMP, but Adrb2, did not activate nucleotide formation; isoprenaline relaxation was inhibited by propranolol (β1, β2), CGP20712A (β1), and SQ22536 (adenylyl cyclase inhibitor), but not by ICI118,551 (β2), SR59230A (β3), ODQ (soluble guanylyl cyclase inhibitor), L-NAME or endothelium removal. In aorta, Adrb1 signalled through cAMP, while β2- and β3-subtypes through cGMP; isoprenaline relaxation was inhibited by propranolol, ICI118,551, ODQ, L-NAME, and to a lesser extent, by endothelium removal. CL316243 (β3-agonist) relaxed aorta, but not MRA. Conclusion and Implication Despite all three Adrb subtypes being found in both vessels, Adrb1, located in SMCs and acting through the adenylyl cyclase/cAMP pathway, are primarily responsible for vasodilatation in MRA. However, Adrb-mediated vasodilatation in aorta is driven by endothelial Adrb2 and Adrb3, but also by the Adrb2 present in SMCs, and is coupled to the NO/cGMP pathway. These results could help to understand the different physiological roles played by Adrb signalling in regulating conductance and resistance vessels. PMID:23373597

  13. Tranilast Increases Vasodilator Response to Acetylcholine in Rat Mesenteric Resistance Arteries through Increased EDHF Participation

    PubMed Central

    Sastre, Esther; Caracuel, Laura; Callejo, María; Balfagón, Gloria

    2014-01-01

    Background and Purpose Tranilast, in addition to its capacity to inhibit mast cell degranulation, has other biological effects, including inhibition of reactive oxygen species, cytokines, leukotrienes and prostaglandin release. In the current study, we analyzed whether tranilast could alter endothelial function in rat mesenteric resistance arteries (MRA). Experimental Approach Acetylcholine-induced relaxation was analyzed in MRA (untreated and 1-hour tranilast treatment) from 6 month-old Wistar rats. To assess the possible participation of endothelial nitric oxide or prostanoids, acetylcholine-induced relaxation was analyzed in the presence of L-NAME or indomethacin. The participation of endothelium-derived hyperpolarizing factor (EDHF) in acetylcholine-induced response was analyzed by preincubation with TRAM-34 plus apamin or by precontraction with a high K+ solution. Nitric oxide (NO) and superoxide anion levels were measured, as well as vasomotor responses to NO donor DEA-NO and to large conductance calcium-activated potassium channel opener NS1619. Key Results Acetylcholine-induced relaxation was greater in tranilast-incubated MRA. Acetylcholine-induced vasodilation was decreased by L-NAME in a similar manner in both experimental groups. Indomethacin did not modify vasodilation. Preincubation with a high K+ solution or TRAM-34 plus apamin reduced the vasodilation to ACh more markedly in tranilast-incubated segments. NO and superoxide anion production, and vasodilator responses to DEA-NO or NS1619 remained unmodified in the presence of tranilast. Conclusions and Implications Tranilast increased the endothelium-dependent relaxation to acetylcholine in rat MRA. This effect is independent of the nitric oxide and cyclooxygenase pathways but involves EDHF, and is mediated by an increased role of small conductance calcium-activated K+ channels. PMID:24992476

  14. ACE inhibition can improve orthostatic proteinuria associated with nutcracker syndrome.

    PubMed

    Ha, Tae-Sun; Lee, Eun-Ju

    2006-11-01

    Left renal vein entrapment syndrome (nutcracker syndrome) was documented by magnetic resonance angiography (MRA) as a cause of orthostatic proteinuria in a 14-year-old girl female adolescent. Because of continuous proteinuria we performed a left renal biopsy which showed moderate mesangial hypercellularity. Her overt orthostatic proteinuria disappeared after a treatment of angiotensin-converting enzyme (ACE) inhibition. Nutcracker syndrome remains a rare but important cause of elevated protein excretion, which can induce mesangial changes and be improved by ACE inhibitor treatment.

  15. Haemodynamic analysis of vessel remodelling in STA-MCA bypass for Moyamoya disease and its impact on bypass patency.

    PubMed

    Zhu, Feng-Ping; Zhang, Yu; Higurashi, Masakazu; Xu, Bin; Gu, Yu-Xiang; Mao, Ying; Morgan, Michael Kerin; Qian, Yi

    2014-06-01

    The purpose of this study is to estimate the remodelling characteristics of STA-MCA bypass and its influence on patency via the use of computational fluid dynamic (CFD) technology. The reconstructed three-dimensional geometries from MRA were segmented to create computational domains for CFD simulations. Eleven patients, who underwent regular MRA both immediately following surgery and at the six months follow-up, were studied. The flow velocities at STA were measured via the use of quantitative MRA (QMRA) to validate simulation results. STA-MCA bypass patency was confirmed for each patient immediately following surgery. The simulation indicated that the remodelling of the arterial pedicle in nine patients was associated with a reduction in the resistance to flow through the bypass. For these cases, the modelling of a driving pressure of 10mmHg through the bypass at 6 months post-surgery resulted in a 50% greater blood flow than those found immediately following surgery. However, two patients were found to exhibit contradictory patterns of remodelling, in which a highly curved bending at the bypass immediately post-surgery underwent progression, with increased resistance to flow through the bypass at 6 months follow-up, thereby resulting in a modelled flow rate reduction of 50% and 25%, respectively. This study revealed that STA-MCA bypass has a characteristic remodelling that usually reduces flow resistance. The initial morphology of the bypass may have had a significant effect on the outcome of vessel remodelling.

  16. Role of lactate dehydrogenase in metmyoglobin reduction and color stability of different bovine muscles.

    PubMed

    Kim, Y H; Keeton, J T; Smith, S B; Berghman, L R; Savell, J W

    2009-11-01

    The role of lactate dehydrogenase (LDH) in metmyoglobin reducing activity (MRA) and color stability of different bovine muscles was studied in two consecutive experiments. In experiment 1, three different bovine muscles -M. longissimus lumborum (LL), M. semimembranosus (SM), and M. psoas major (PM) - were obtained (n=7, respectively), cut into steaks, PVC packaged, and then displayed for 7days at 1°C. The LL was the most red over display time and had more (P<0.05) LDH-B activity (catalyzing toward NADH generation), LDH1 isoform expression, NADH, and higher (P<0.05) MRA than the other two muscles studied. The PM had the least color stability and lowest MRA. In experiment 2, LL steaks (n=8) were cut in half, one side syringe-injected with oxamate, and the other injected with distilled water. Inclusion of oxamate decreased (P<0.05) LDH-B activity, NADH, and a* values after 10days display at 1°C. These results suggest that variation in color stability of physiologically different muscles is regulated by different replenishment rates of NADH via different LDH isozymes. PMID:20416707

  17. Treatment of mycoplasma contamination in a large panel of cell cultures.

    PubMed

    Drexler, H G; Gignac, S M; Hu, Z B; Hopert, A; Fleckenstein, E; Voges, M; Uphoff, C C

    1994-05-01

    Mycoplasmal contamination remains a significant impediment to the culture of eukaryotic cells. For certain cultures, attempts to eliminate the infection are feasible alternatives to the normally recommended disposal of the contaminated culture. Here, three antibiotic regimens for mycoplasmal decontamination were compared in a large panel of naturally infected cultures: a 1-wk treatment with the fluoroquinolone mycoplasma removal agent (MRA), a 2-wk treatment with the fluoroquinolone ciprofloxacin, and three rounds of a sequential 1-wk treatment with BM-Cyclin containing tiamulin and minocyclin. These antibiotic treatments had a high efficiency of permanent cure: MRA 69%, ciprofloxacin 75%, BM-Cyclin 87%. Resistance to mycoplasma eradication was observed in some cell cultures: BM-Cyclin 0%, MRA 20%, ciprofloxacin 20%. Nearly all resistant contaminants that could be identified belonged to the species Mycoplasma arginini and M. orale. Detrimental effects of the antibiotics were seen in the form of culture death caused by cytotoxicity (in 5 to 13% of the cultures). Alterations of the cellular phenotypic features or selective clonal outgrowth might represent further untoward side effects of exposure to these antibiotics. Overall, antibiotic decontamination of mycoplasmas is an efficient, inexpensive, reliable, and simple method: 150/200 (75%) chronically and heavily contaminated cultures were cured and 50/200 (25%) cultures could not be cleansed and were either lost or remained infected. It is concluded that eukaryotic cell cultures containing mycoplasmas are amenable to antibiotic treatment and that a cure rate of three-quarters is a reasonable expectation.

  18. Outcomes of drug-based and surgical treatments for primary aldosteronism.

    PubMed

    Steichen, Olivier; Lorthioir, Aurelien; Zinzindohoue, Franck; Plouin, Pierre-François; Amar, Laurence

    2015-05-01

    Treatments for primary aldosteronism (PA) aim to correct or prevent the deleterious consequences of hyperaldosteronism: hypertension, hypokalemia, and direct target organ damage. Patients with unilateral PA considered fit for surgery can undergo laparoscopic adrenalectomy, which significantly decreases blood pressure (BP) and medications in most cases and cures hypertension in about 40%. Mineralocorticoid receptor antagonists (MRA) are used to treat patients with bilateral PA and those with unilateral PA if surgery is not possible or not desired. Spironolactone is more potent than eplerenone, but high doses are poorly tolerated in men. MRA can be replaced or complemented with epithelial sodium channel blockers, such as amiloride. Thiazide diuretics and calcium channel blockers are used when the first-line drugs are insufficient to control BP. Dietary sodium restriction should be implemented in all cases because the deleterious consequences of hyperaldosteronism are dependent on salt loading. Several studies comparing the results of surgery and MRA have reported no differences in terms of BP, serum potassium concentration, or cardiovascular and kidney outcomes, although the benefits of treatment tend to be observed sooner with surgery. Patients with PA display relative glomerular hyperfiltration, which is reversed by specific treatment, revealing CKD in 30% of patients. However, further kidney damage is lessened by the treatment of PA. PMID:25908468

  19. 3D brain MR angiography displayed by a multi-autostereoscopic screen

    NASA Astrophysics Data System (ADS)

    Magalhães, Daniel S. F.; Ribeiro, Fádua H.; Lima, Fabrício O.; Serra, Rolando L.; Moreno, Alfredo B.; Li, Li M.

    2012-02-01

    The magnetic resonance angiography (MRA) can be used to examine blood vessels in key areas of the body, including the brain. In the MRA, a powerful magnetic field, radio waves and a computer produce the detailed images. Physicians use the procedure in brain images mainly to detect atherosclerosis disease in the carotid artery of the neck, which may limit blood flow to the brain and cause a stroke and identify a small aneurysm or arteriovenous malformation inside the brain. Multi-autostereoscopic displays provide multiple views of the same scene, rather than just two, as in autostereoscopic systems. Each view is visible from a different range of positions in front of the display. This allows the viewer to move left-right in front of the display and see the correct view from any position. The use of 3D imaging in the medical field has proven to be a benefit to doctors when diagnosing patients. For different medical domains a stereoscopic display could be advantageous in terms of a better spatial understanding of anatomical structures, better perception of ambiguous anatomical structures, better performance of tasks that require high level of dexterity, increased learning performance, and improved communication with patients or between doctors. In this work we describe a multi-autostereoscopic system and how to produce 3D MRA images to be displayed with it. We show results of brain MR angiography images discussing, how a 3D visualization can help physicians to a better diagnosis.

  20. Modular robotic architecture

    NASA Astrophysics Data System (ADS)

    Smurlo, Richard P.; Laird, Robin T.

    1991-03-01

    The development of control architectures for mobile systems is typically a task undertaken with each new application. These architectures address different operational needs and tend to be difficult to adapt to more than the problem at hand. The development of a flexible and extendible control system with evolutionary growth potential for use on mobile robots will help alleviate these problems and if made widely available will promote standardization and cornpatibility among systems throughout the industry. The Modular Robotic Architecture (MRA) is a generic control systern that meets the above needs by providing developers with a standard set of software hardware tools that can be used to design modular robots (MODBOTs) with nearly unlimited growth potential. The MODBOT itself is a generic creature that must be customized by the developer for a particular application. The MRA facilitates customization of the MODBOT by providing sensor actuator and processing modules that can be configured in almost any manner as demanded by the application. The Mobile Security Robot (MOSER) is an instance of a MODBOT that is being developed using the MRA. Navigational Sonar Module RF Link Control Station Module hR Link Detection Module Near hR Proximi Sensor Module Fluxgate Compass and Rate Gyro Collision Avoidance Sonar Module Figure 1. Remote platform module configuration of the Mobile Security Robot (MOSER). Acoustical Detection Array Stereoscopic Pan and Tilt Module High Level Processing Module Mobile Base 566

  1. Screening for lipid requirements of membrane proteins by combining cell-free expression with nanodiscs.

    PubMed

    Henrich, Erik; Dötsch, Volker; Bernhard, Frank

    2015-01-01

    Cell-free (CF) protein expression has emerged as one of the most efficient production platforms for membrane proteins. Central bottlenecks prevalent in conventional cell-based expression systems such as mistargeting, inclusion body formation, degradation as well as product toxicity can be addressed by taking advantage of the reduced complexity of CF expression systems. However, the open accessibility of CF reactions offers the possibility to design customized artificial expression environments by supplying synthetic hydrophobic compounds such as micelles or membranes of defined composition. The open nature of CF systems therefore generally allows systematic screening approaches for the identification of efficient cotranslational solubilization environments of membrane proteins. Synergies exist in particular with the recently developed nanodisc (ND) technology enabling the synthesis of stable and highly soluble particles containing membrane discs of defined composition. Specific types of lipids frequently modulate folding, stability, and activity of integrated membrane proteins. One recently reported example are phospho-MurNAc-pentapeptide (MraY) translocases that catalyze a crucial step in bacterial peptidoglycan biosynthesis making them interesting as future drug targets. Production of functionally active MraY homologues from most human pathogens in conventional cellular production systems was so far not successful due to their obviously strict lipid dependency for functionally folding. We demonstrate that the combination of CF expression with ND technologies is an efficient strategy for the production of folded MraY translocases, and we present a general protocol for the rapid screening of lipid specificities of membrane proteins. PMID:25857790

  2. Application of Direct Virtual Coil to Dynamic Contrast-Enhanced MRI and MR Angiography with Data-Driven Parallel Imaging

    PubMed Central

    Wang, Kang; Beatty, Philip J.; Nagle, Scott K.; Reeder, Scott B.; Holmes, James H.; Rahimi, Mahdi S.; Bell, Laura C.; Korosec, Frank R.; Brittain, Jean H.

    2013-01-01

    Purpose To demonstrate the feasibility of Direct Virtual Coil (DVC) in the setting of 4D dynamic imaging used in multiple clinical applications. Theory and Methods Three dynamic imaging applications were chosen: pulmonary perfusion, liver perfusion and peripheral MRA, with 18, 11 and 10 subjects respectively. After view-sharing, the k-space data were reconstructed twice: once with channel-by-channel (CBC) followed by sum-of-squares coil combination and once with DVC. Images reconstructed using CBC and DVC were compared and scored based on overall image quality by two experienced radiologists using a 5-point scale. Results The CBC and DVC showed similar image quality in image domain. Time course measurements also showed good agreement in the temporal domain. CBC and DVC images were scored as equivalent for all pulmonary perfusion cases, all liver perfusion cases, and 4 out of the 10 peripheral MRA cases. For the remaining 6 peripheral MRA cases, DVC were scored as slightly better (not clinically significant) than the CBC images by Radiologist A and as equivalent by Radiologist B. Conclusion For dynamic contrast-enhanced MR applications, it is clinically feasible to reduce image reconstruction time while maintaining image quality and time course measurement using the DVC technique. PMID:23441013

  3. Three-Dimensional Time-of-Flight Magnetic Resonance Angiography Detection of Duplication of the Vertebral Artery in a Large Chinese Population

    PubMed Central

    Li, Shuhua; Li, Yunyun; Bai, Min; Zhang, Chuanchen

    2016-01-01

    Background The aim of this study was to investigate duplication of the vertebral artery (VA) using three-dimensional time-of-flight (3D TOF) magnetic resonance angiography (MRA) in a large study population to further our understanding of vascular variations. Material/Methods A retrospective analysis of 3D TOF-MRA data in 12 826 cases was performed. The occurrence rate of VA duplication was calculated and accompanied vascular anomalies were recoded. Results Twenty-one VA duplication patients were found, with an occurrence rate of 0.164%; 12 of them had left VA duplication with 2 branches initially arising from the aortic arch and left subclavian artery; 9 of them were right VA duplication with the branches originating from the right subclavian artery. In the 21 cases, 11 had other vascular abnormalities. Conclusions VA duplication is very rare and often associated with other vascular abnormalities. 3D TOF-MRA can accurately display the duplication variation. Better understanding of the variation is instrumental for disease diagnosis, interventional therapy, and surgical operation. PMID:27749814

  4. Frequency of Intracranial Aneurysms Determined by Magnetic Resonance Angiography in Children (Mean Age 16) Having Operative or Endovascular Treatment of Coarctation of the Aorta (Mean Age 3).

    PubMed

    Donti, Andrea; Spinardi, Luca; Brighenti, Maurizio; Faccioli, Luca; Leoni, Chiara; Fabi, Marianna; Trossello, Marco P; Gargiulo, Gaetano D; Bonvicini, Marco

    2015-08-15

    Coarctation of the aorta (CofA) has been associated with an increased risk of intracranial aneurysm (IA). This magnetic resonance angiography (MRA) study investigates the prevalence of IAs in 80 children treated in early life for CofA. MRA was performed at mean age of 15.7 ± 7.1 years, and surgical or endovascular treatment for CofA occurred at a mean age of 2.6 ± 4.4 years. No IA was found. In contrast with earlier findings in adult patients with late treatment for CofA, this first systematic study of very early treated patients for CofA failed to confirm the association between CofA and IAs. Our results call the abnormal developmental relation between CofA and IAs into question and suggest that modifiable risk factors like hypertension may be responsible for IA development in patients with CofA with adult diagnosis and treatment. In conclusion, our data suggest that early treatment of CofA can reduce the formation of IAs in children so as to make MRA screening less valuable in this young population.

  5. Tissular distributions and kinetics of two renal 99mTc-radiopharmaceuticals in rat.

    PubMed

    Bonnin, F; Petiet, A; Petegnief, Y; Colas-Linhart, N; Bok, B

    2001-05-01

    A digital radioimager (RI), conventional radioautography (RA), and tracks microradioautography (MRA) were used to assess the biodistributions and kinetics of 99mTc-dimercaptosuccinic (99mTc-DMSA) and 99mTc-mercaptoacetyltriglycine (99mTc-MAG3) in rat at both macroscopic and microscopic levels. Three groups of male Wistar rats were studied. Using gamma-counting, kidney, liver, spleen and blood kinetics of both tracers were assessed in the three groups. Using RA and RI, renal slices were analyzed in group 1 the animals being sacrified from 2 to 60 min after injection of 99mTc-MAG3, and in group 2 the animals being sacrificed from 0.5 to 24 hr after injection of 99mTc-DMSA. Using MRA, renal slices were analyzed for 99mTc-DMSA (group 3). RA films and RI images displayed the variation with time of the cortical and medullary uptakes of the tracers. No regional heterogeneity within the different structures could be seen neither with RA films nor with MRA. The remaining activity in the blood 24 hr after injection of 99mTc-DMSA was evaluated. The tissular distributions of both tracer being homogenous, mean values of cortical uptake seems to be acceptable for dosimetric studies. Our results incite to use of 99mTc-MAG3 instead of 99mTc-DMSA when both tracers may be indicated. PMID:11441950

  6. Interactive 3-D graphics workstations in stereotaxy: clinical requirements, algorithms, and solutions

    NASA Astrophysics Data System (ADS)

    Ehricke, Hans-Heino; Daiber, Gerhard; Sonntag, Ralf; Strasser, Wolfgang; Lochner, Mathias; Rudi, Lothar S.; Lorenz, Walter J.

    1992-09-01

    In stereotactic treatment planning the spatial relationships between a variety of objects has to be taken into account in order to avoid destruction of vital brain structures and rupture of vasculature. The visualization of these highly complex relations may be supported by 3-D computer graphics methods. In this context the three-dimensional display of the intracranial vascular tree and additional objects, such as neuroanatomy, pathology, stereotactic devices, or isodose surfaces, is of high clinical value. We report an advanced rendering method for a depth-enhanced maximum intensity projection from magnetic resonance angiography (MRA) and a walk-through approach to the analysis of MRA volume data. Furthermore, various methods for a multiple-object 3-D rendering in stereotaxy are discussed. The development of advanced applications in medical imaging can hardly be successful if image acquisition problems are disregarded. We put particular emphasis on the use of conventional MRI and MRA for stereotactic guidance. The problem of MR distortion is discussed and a novel three- dimensional approach to the quantification and correction of the distortion patterns is presented. Our results suggest that the sole use of MR for stereotactic guidance is highly practical. The true three-dimensionality of the acquired datasets opens up new perspectives to stereotactic treatment planning. For the first time it is possible now to integrate all the necessary information into 3-D scenes, thus enabling an interactive 3-D planning.

  7. Cognition and the Default Mode Network in Children with Sickle Cell Disease: A Resting State Functional MRI Study

    PubMed Central

    Montanaro, Maria; Rampazzo, Patrizia; Ermani, Mario; Talenti, Giacomo; Baracchini, Claudio; Favero, Angela; Basso, Giuseppe; Manara, Renzo; Sainati, Laura

    2016-01-01

    Cerebrovascular complications are frequent events in children with sickle cell disease, yet routinely used techniques such as Transcranial Doppler (TCD), Magnetic Resonance (MRI) and Angiography (MRA), insufficiently explain the cause of poor cognitive performances. Forty children with SS-Sβ° (mean age 8 years) underwent neurocognitive evaluation and comprehensive brain imaging assessment with TCD, MRI, MRA, Resting State (RS) Functional MRI with evaluation of the Default Mode Network (DMN). Sixteen healthy age-matched controls underwent MRI, MRA and RS functional MRI.Children with SCD display increased brain connectivity in the DMN even in the absence of alterations in standard imaging techniques. Patients with low neurocognitive scores presented higher brain connectivity compared to children without cognitive impairment or controls, suggesting an initial compensatory mechanism to maintain performances. In our cohort steady state haemoglobin level was not related to increased brain connectivity, but SatO2<97% was. Our findings provide novel evidence that SCD is characterized by a selective disruption of connectivity among relevant regions of the brain, potentially leading to reduced cognition and altered functional brain dynamics. RS functional MRI could be used as a useful tool to evaluate cognition and cerebral damage in SCD in longitudinal trials. PMID:27281287

  8. Perceptual enhancement of arteriovenous malformation in MRI angiography displays

    NASA Astrophysics Data System (ADS)

    Abhari, Kamyar; Baxter, John S. H.; Eagleson, Roy; Peters, Terry; de Ribaupierre, Sandrine

    2012-02-01

    The importance of presenting medical images in an intuitive and usable manner during a procedure is essential. However, most medical visualization interfaces, particularly those designed for minimally-invasive surgery, suffer from a number of issues as a consequence of disregarding the human perceptual, cognitive, and motor system's limitations. This matter is even more prominent when human visual system is overlooked during the design cycle. One example is the visualization of the neuro-vascular structures in MR angiography (MRA) images. This study investigates perceptual performance in the usability of a display to visualize blood vessels in MRA volumes using a contour enhancement technique. Our results show that when contours are enhanced, our participants, in general, can perform faster with higher level of accuracy when judging the connectivity of different vessels. One clinical outcome of such perceptual enhancement is improvement of spatial reasoning needed for planning complex neuro-vascular operations such as treating Arteriovenous Malformations (AVMs). The success of an AVM intervention greatly depends on fully understanding the anatomy of vascular structures. However, poor visualization of pre-operative MRA images makes the planning of such a treatment quite challenging.

  9. Three-dimensional contrast-enhanced magnetic resonance angiography for anterolateral thigh flap outlining: A retrospective case series of 68 patients

    PubMed Central

    Jiang, Chunjing; Lin, Ping; Fu, Xiaoyan; Shu, Jiner; Li, Huimin; Hu, Xiaogang; He, Jianrong; Ding, Mingxing

    2016-01-01

    Flap transfer is increasingly used for repairing limb defects secondary to trauma or tumor, and appropriate preoperative planning plays a critical role. The present study aimed to examine the use of three-dimensional (3D) contrast-enhanced magnetic resonance angiography (CE-MRA) in evaluating the blood supply distribution and perforating branch pattern of anterolateral thigh (ALT) flaps. Bilateral donor lower limbs were scanned in 68 patients (136 limbs) using a Siemens Avanto 1.5 T magnetic resonance imaging scanner with a 3D fast low-angle shot sequence, following the thin-slab maximum intensity projection (TS-MIP) technique. The lateral femoral circumflex artery (LFCA) was visualized in all patients: 101 limbs (101/136, 74.3%) were type I; 20 limbs (20/136, 14.7%) were type II; 3 limbs (3/136, 2.2%) were type III; and 12 limbs (12/136, 8.8%) were type IV. Tertiary branches were identified in 94 limbs (94/136, 69.1%). Donor flaps were outlined according to MRA TS-MIP findings in 4 patients. All flaps survived uneventfully following the transfer. In donor flap outlining, 3D CE-MRA with the TS-MIP technique allowed an accurate, direct visualization of the branching pattern and distribution profile of the LFCA supplying the ALT flap. PMID:27446322

  10. Examination of Reticulocytosis among Chronically Transfused Children with Sickle Cell Anemia

    PubMed Central

    Kaushal, Megha; Byrnes, Colleen; Khademian, Zarir; Duncan, Natalie; Luban, Naomi L. C.; Miller, Jeffery L.; Fasano, Ross M.; Meier, Emily Riehm

    2016-01-01

    Sickle cell anemia (SCA) is an inherited hemolytic anemia with compensatory reticulocytosis. Recent studies have shown that increased levels of reticulocytosis during infancy are associated with increased hospitalizations for SCA sequelae as well as cerebrovascular pathologies. In this study, absolute reticulocyte counts (ARC) measured prior to transfusion were analysed among a cohort of 29 pediatric SCA patients receiving chronic transfusion therapy (CTT) for primary and secondary stroke prevention. A cross-sectional flow cytometric analysis of the reticulocyte phenotype was also performed. Mean duration of CTT was 3.1 ± 2.6 years. Fifteen subjects with magnetic resonance angiography (MRA) -vasculopathy had significantly higher mean ARC prior to initiating CTT compared to 14 subjects without MRA-vasculopathy (427.6 ± 109.0 K/μl vs. 324.8 ± 109.2 K/μl, p<0.05). No significant differences in hemoglobin or percentage sickle hemoglobin (HbS) were noted between the two groups at baseline. Reticulocyte phenotyping further demonstrated that the percentages of circulating immature [CD36(+), CD71(+)] reticulocytes positively correlated with ARC in both groups. During the first year of CTT, neither group had significant reductions in ARC. Among this group of children with SCA, cerebrovasculopathy on MRA at initiation of CTT was associated with increased reticulocytosis, which was not reduced after 12 months of transfusions. PMID:27116614

  11. Retro-regression--another important multivariate regression improvement.

    PubMed

    Randić, M

    2001-01-01

    We review the serious problem associated with instabilities of the coefficients of regression equations, referred to as the MRA (multivariate regression analysis) "nightmare of the first kind". This is manifested when in a stepwise regression a descriptor is included or excluded from a regression. The consequence is an unpredictable change of the coefficients of the descriptors that remain in the regression equation. We follow with consideration of an even more serious problem, referred to as the MRA "nightmare of the second kind", arising when optimal descriptors are selected from a large pool of descriptors. This process typically causes at different steps of the stepwise regression a replacement of several previously used descriptors by new ones. We describe a procedure that resolves these difficulties. The approach is illustrated on boiling points of nonanes which are considered (1) by using an ordered connectivity basis; (2) by using an ordering resulting from application of greedy algorithm; and (3) by using an ordering derived from an exhaustive search for optimal descriptors. A novel variant of multiple regression analysis, called retro-regression (RR), is outlined showing how it resolves the ambiguities associated with both "nightmares" of the first and the second kind of MRA. PMID:11410035

  12. Treatment of mycoplasma contamination in a large panel of cell cultures.

    PubMed

    Drexler, H G; Gignac, S M; Hu, Z B; Hopert, A; Fleckenstein, E; Voges, M; Uphoff, C C

    1994-05-01

    Mycoplasmal contamination remains a significant impediment to the culture of eukaryotic cells. For certain cultures, attempts to eliminate the infection are feasible alternatives to the normally recommended disposal of the contaminated culture. Here, three antibiotic regimens for mycoplasmal decontamination were compared in a large panel of naturally infected cultures: a 1-wk treatment with the fluoroquinolone mycoplasma removal agent (MRA), a 2-wk treatment with the fluoroquinolone ciprofloxacin, and three rounds of a sequential 1-wk treatment with BM-Cyclin containing tiamulin and minocyclin. These antibiotic treatments had a high efficiency of permanent cure: MRA 69%, ciprofloxacin 75%, BM-Cyclin 87%. Resistance to mycoplasma eradication was observed in some cell cultures: BM-Cyclin 0%, MRA 20%, ciprofloxacin 20%. Nearly all resistant contaminants that could be identified belonged to the species Mycoplasma arginini and M. orale. Detrimental effects of the antibiotics were seen in the form of culture death caused by cytotoxicity (in 5 to 13% of the cultures). Alterations of the cellular phenotypic features or selective clonal outgrowth might represent further untoward side effects of exposure to these antibiotics. Overall, antibiotic decontamination of mycoplasmas is an efficient, inexpensive, reliable, and simple method: 150/200 (75%) chronically and heavily contaminated cultures were cured and 50/200 (25%) cultures could not be cleansed and were either lost or remained infected. It is concluded that eukaryotic cell cultures containing mycoplasmas are amenable to antibiotic treatment and that a cure rate of three-quarters is a reasonable expectation. PMID:8069460

  13. Automated transformation-invariant shape recognition through wavelet multiresolution

    NASA Astrophysics Data System (ADS)

    Brault, Patrice; Mounier, Hugues

    2001-12-01

    We present here new results in Wavelet Multi-Resolution Analysis (W-MRA) applied to shape recognition in automatic vehicle driving applications. Different types of shapes have to be recognized in this framework. They pertain to most of the objects entering the sensors field of a car. These objects can be road signs, lane separation lines, moving or static obstacles, other automotive vehicles, or visual beacons. The recognition process must be invariant to global, affine or not, transformations which are : rotation, translation and scaling. It also has to be invariant to more local, elastic, deformations like the perspective (in particular with wide angle camera lenses), and also like deformations due to environmental conditions (weather : rain, mist, light reverberation) or optical and electrical signal noises. To demonstrate our method, an initial shape, with a known contour, is compared to the same contour altered by rotation, translation, scaling and perspective. The curvature computed for each contour point is used as a main criterion in the shape matching process. The original part of this work is to use wavelet descriptors, generated with a fast orthonormal W-MRA, rather than Fourier descriptors, in order to provide a multi-resolution description of the contour to be analyzed. In such way, the intrinsic spatial localization property of wavelet descriptors can be used and the recognition process can be speeded up. The most important part of this work is to demonstrate the potential performance of Wavelet-MRA in this application of shape recognition.

  14. Diagnosing RCVS Without the CV: The Evolution of Reversible Cerebral Vasoconstriction Syndrome.

    PubMed

    Jacoby, Nuri; Kaunzner, Ulrike; Dinkin, Marc; Safdieh, Joseph

    2016-07-01

    This is a case of a 52-year-old man with a past medical history of 2 episodes of coital thunderclap headaches as well as recent cocaine, marijuana, and pseudoephedrine use, who presented with sudden, sharp, posterior headache associated with photophobia and phonophobia. His initial magnetic resonance imaging (MRI) of the brain, magnetic resonance angiography (MRA) of the head, and magnetic resonance venography (MRV) of the head were all normal as well as a normal lumbar puncture. Given the multiple risk factors for reversible cerebral vasoconstriction syndrome (RCVS), the patient was treated for suspected RCVS, despite the normal imaging. Repeat MRI brain 3 days after hospital admission demonstrated confluent white matter T2 hyperintensities most prominent in the occipital lobes, typical of posterior reversible encephalopathy syndrome (PRES). Repeat MRA of the head 1 day after discharge and 4 days after the abnormal MRI brain showed multisegment narrowing of multiple arteries. This case demonstrates that RCVS may present with PRES on MRI brain and also exemplifies the need to treat suspected RCVS even if imaging is normal, as abnormalities in both the MRI and the MRA may be delayed. PMID:27366300

  15. Developments in microbiological risk assessment models for drinking water--a short review.

    PubMed

    Gale, P

    1996-10-01

    Microbiological risk assessment (MRA) is emerging method to predict the risks of infection from waterborne pathogens (e.g. rotavirus and Cryptosporidium parvum) in the drinking water supply. The objectives of this paper are to review the appropriateness of current models, with emphasis on pathogen exposures through drinking water, and to consider the information necessary to further their development. Calculating pathogen exposures in MRA is currently limited by the fact that pathogen density data for drinking water supplies are only available for very large volume samples--much larger than imbibed daily by any consumer. To develop MRA, information is needed on how pathogens are dispersed within those volumes at the resolution of volumes typically consumed daily by individuals. Available evidence suggests that micro-organisms, including pathogens, are clustered to some degree, even within small volumes, exposing some drinking water consumers to much higher doses than others. By assuming pathogens are randomly dispersed, current models overestimate the risk from the more infectious agents (e.g. rotaviruses) but underestimate the risk from less infectious pathogens (e.g. C. parvum). Approaches to modelling pathogen densities in drinking water from source water data and treatment removal efficiencies require additional information on the degree to which treatment processes (e.g. filtration and coagulation) increase pathogen clustering. The missing information could be obtained from large-scale pilot plant studies.

  16. Diagnosing RCVS Without the CV

    PubMed Central

    Kaunzner, Ulrike; Dinkin, Marc; Safdieh, Joseph

    2015-01-01

    This is a case of a 52-year-old man with a past medical history of 2 episodes of coital thunderclap headaches as well as recent cocaine, marijuana, and pseudoephedrine use, who presented with sudden, sharp, posterior headache associated with photophobia and phonophobia. His initial magnetic resonance imaging (MRI) of the brain, magnetic resonance angiography (MRA) of the head, and magnetic resonance venography (MRV) of the head were all normal as well as a normal lumbar puncture. Given the multiple risk factors for reversible cerebral vasoconstriction syndrome (RCVS), the patient was treated for suspected RCVS, despite the normal imaging. Repeat MRI brain 3 days after hospital admission demonstrated confluent white matter T2 hyperintensities most prominent in the occipital lobes, typical of posterior reversible encephalopathy syndrome (PRES). Repeat MRA of the head 1 day after discharge and 4 days after the abnormal MRI brain showed multisegment narrowing of multiple arteries. This case demonstrates that RCVS may present with PRES on MRI brain and also exemplifies the need to treat suspected RCVS even if imaging is normal, as abnormalities in both the MRI and the MRA may be delayed. PMID:27366300

  17. Anatomic vs. Acquired Image Frame Discordance in Spectral Domain Optical Coherence Tomography Minimum Rim Measurements

    PubMed Central

    Yang, Hongli; Hardin, Christy; Reyes, Luke; Reynaud, Juan; Gardiner, Stuart K.; Fortune, Brad; Demirel, Shaban; Burgoyne, Claude F.

    2014-01-01

    Purpose To quantify the effects of using the fovea to Bruch's membrane opening (FoBMO) axis as the nasal-temporal midline for 30° sectoral (clock-hour) spectral domain optical coherence tomography (SDOCT) optic nerve head (ONH) minimum rim width (MRW) and area (MRA) calculations. Methods The internal limiting membrane and BMO were delineated within 24 radial ONH B-scans in 222 eyes of 222 participants with ocular hypertension and glaucoma. For each eye the fovea was marked within the infrared reflectance image, the FoBMO angle (θ) relative to the acquired image frame (AIF) horizontal was calculated, the ONH was divided into 30°sectors using a FoBMO or AIF nasal/temporal axis, and SDOCT MRW and MRA were quantified within each FoBMO vs. AIF sector. For each sector, focal rim loss was calculated as the MRW and MRA gradients (i.e. the difference between the value for that sector and the one clockwise to it divided by 30°). Sectoral FoBMO vs. AIF discordance was calculated as the difference between the FoBMO and AIF values for each sector. Generalized estimating equations were used to predict the eyes and sectors of maximum FoBMO vs. AIF discordance. Results The mean FoBMO angle was −6.6±4.2° (range: −17° to +7°). FoBMO vs. AIF discordance in sectoral mean MRW and MRA was significant for 7 of 12 and 6 of 12 sectors, respectively (p<0.05, Wilcoxon test, Bonferroni correction). Eye-specific, FoBMO vs. AIF sectoral discordance was predicted by sectoral rim gradient (p<0.001) and FoBMO angle (p<0.001) and achieved maximum values of 83% for MRW and 101% for MRA. Conclusions Using the FoBMO axis as the nasal-temporal axis to regionalize the ONH rather than a line parallel to the AIF horizontal axis significantly influences clock-hour SDOCT rim values. This effect is greatest in eyes with large FoBMO angles and sectors with focal rim loss. PMID:24643069

  18. Experimental Glaucoma Causes Optic Nerve Head Neural Rim Tissue Compression: A Potentially Important Mechanism of Axon Injury

    PubMed Central

    Fortune, Brad; Reynaud, Juan; Hardin, Christy; Wang, Lin; Sigal, Ian A.; Burgoyne, Claude F.

    2016-01-01

    Purpose We tested the hypothesis that experimental glaucoma (EG) results in greater thinning of the optic nerve head (ONH) neural rim tissue than the peripapillary retinal nerve fiber layer (RNFL) tissue. Methods Longitudinal spectral-domain optical coherence tomography (SDOCT) imaging of the ONH and peripapillary RNFL was performed every other week under manometric IOP control (10 mm Hg) in 51 nonhuman primates (NHP) during baseline and after induction of unilateral EG. The ONH parameter minimum rim area (MRA) was derived from 80 radial B-scans centered on the ONH; RNFL cross-sectional area (RNFLA) from a peripapillary circular B-scan with 12° diameter. Results In control eyes, MRA was 1.00 ± 0.19 mm2 at baseline and 1.00 ± 0.19 mm2 at the final session (P = 0.77), while RNFLA was 0.95 ± 0.09 and 0.95 ± 0.10 mm2, respectively (P = 0.96). In EG eyes, MRA decreased from 1.00 ± 0.19 mm2 at baseline to 0.63 ± 0.21 mm2 at the final session (P < 0.0001), while RNFLA decreased from 0.95 ± 0.09 to 0.74 ± 0.19 mm2, respectively (P < 0.0001). Thus, MRA decreased by 36.4 ± 20.6% in EG eyes, significantly more than the decrease in RNFLA (21.7 ± 19.4%, P < 0.0001). Other significant changes in EG eyes included increased Bruch's membrane opening (BMO) nonplanarity (P < 0.05), decreased BMO aspect ratio (P < 0.0001), and decreased MRA angle (P < 0.001). Bruch's membrane opening area did not change from baseline in either control or EG eyes (P = 0.27, P = 0.15, respectively). Conclusions Optic nerve head neural rim tissue thinning exceeded peripapillary RNFL thinning in NHP EG. These results support the hypothesis that axon bundles are compressed transversely within the ONH rim along with glaucomatous deformation of connective tissues. PMID:27564522

  19. Risk factors for the need of hip arthroscopy following periacetabular osteotomy

    PubMed Central

    Hartig-Andreasen, Charlotte; Troelsen, Anders; Thillemann, Theis M.; Gelineck, John; Søballe, Kjeld

    2015-01-01

    Despite the frequency of labral tears in symptomatic developmental dysplasia of the hip, no consensus exists regarding the treatment of coexisting dysplasia of the hip and tearing of the acetabular labrum. The purpose of this prospective, MR arthrography (MRA) based 2-year follow-up study was to identify risk factors predicting the need for a hip arthroscopy (HA) after periacetabular osteotomy (PAO). Ninety-nine patients (104 hips) scheduled for PAO were evaluated preoperatively and at 2-year follow-up. MRA was performed in all patients prior to PAO. At follow-up, patients were divided into a non-arthroscopy and arthroscopy group. The two groups were compared clinical and radiological, and risk factors for HA after PAO were calculated. Patient reported outcome measures (WOMAC, Oxford Hip and SF36) were filled out before PAO and at follow-up. Ninety-five hips (91.3%) were evaluated. Twenty-six hips (27%) required an arthroscopy within 2 years of the PAO. Risk factors were preoperative borderline dysplasia, acetabular retroversion and complete labral detachment. Labral tearing, degeneration or hypertrophy did not negatively affect the outcome of PAO. Patients not requiring an arthroscopy had a statistically significant better outcome measured by patients reported outcome measures. After PAO, 27% of the hips needed intra-articular assessment. Conventional radiographs and MRA analysis can be used to identify predictors for patients requiring HA after PAO. At 2-year follow-up, the clinical outcome improved in all patients. However, those patients who had no need of a HA after their PAO had superior results. PMID:27011862

  20. Hyperintense Acute Reperfusion Marker on FLAIR in Posterior Circulation Infarction

    PubMed Central

    Wenz, Holger; Böhme, Johannes; Al-Zghloul, Mansour; Groden, Christoph

    2016-01-01

    Purpose In the present study, we aimed to investigate the frequency of blood brain barrier injury in posterior circulation infarction as demonstrated by the hyperintense acute reperfusion marker (HARM) on fluid attenuated inversion recovery images (FLAIR). Methods From a MRI report database we identified patients with posterior circulation infarction who underwent MRI, including perfusion-weighted images (PWI), within 12 hours after onset and follow-up MRI within 24 hours and analyzed diffusion-weighted images (DWI), PWI, FLAIR, and MR angiography (MRA). On FLAIR images, the presence of HARM was noted by using pre-specified criteria (focal enhancement in the subarachnoid space and/or the ventricles). Results Overall 16 patients (median age of patients 68.5 (IQR 55.5–82.75) years) with posterior circulation infarction were included. Of these, 13 (81.3%) demonstrated PCA occlusion, and 3 (18.7%) patients BA occlusion on MRA. Initial DWI demonstrated ischemic lesions in the thalamus (68.8%), splenium (18.8%), hippocampus (75%), occipital lobe (81.3%), mesencephalon (18.8%), pons (18.8%), and cerebellum (50%). On follow-up MRA recanalization was noted in 10 (62.5%) patients. On follow-up FLAIR images, HARM was observed in 8 (50%) patients. In all of these, HARM was detected remote from the acute ischemic lesion. HARM was more frequently observed in patients with vessel recanalization (p = 0.04), minor infarction growth (p = 0.01), and smaller ischemic lesions on follow-up DWI (p = 0.05). Conclusions HARM is a frequent finding in posterior circulation infarction and associated with vessel recanalization, minor infarction growth as well as smaller infarction volumes in the course. Neuroradiologists should be cognizant of the fact that HARM may be present on short interval follow-up FLAIR images in patients with acute ischemic infarction who initially underwent MRI and received intravenous gadolinium-based contrast agents. PMID:27326459

  1. Treatment of unstable osteochondritis dissecans in adults with autogenous osteochondral grafts (Mosaicplasty): long-term results

    PubMed Central

    RONGA, MARIO; STISSI, PLACIDO; LA BARBERA, GIUSEPPE; VALOROSO, MARCO; ANGERETTI, GLORIA; GENOVESE, EUGENIO; CHERUBINO, PAOLO

    2015-01-01

    Purpose the unstable osteochondritis dissecans (OCD-type II and III according to the ICRS classification) of the knee largher than > 2.5 cm2 in adults are uncommon lesions and there is no consensus on how to treat them. Medium-term studies have reported good results using autogenous osteochondral plugs (mosaicplasty). The aim of this study is to analyze the long-term results of this technique for the treatment of unstable OCD in a selected group of adult patients. Methods four patients with OCD at either one of the femoral condyles were included in this prospective study. The average age was 21.2 years (range, 18–24 years). The OCD lesions were classified as type II in three patients and type III in one patient and the average size was 3.8 cm2 (range, 2.55–5.1 cm2). The lesions were treated in situ with a variable number of autogenous osteochondral plugs (Ø 4.5 mm2). The Modified Cincinnati, Lysholm II and Tegner scores were used for clinical and functional evaluation. Magnetic resonance arthrography (MRA) was performed before surgery and at 2, 5 and 10 years after surgery. A modified MOCART score was used to evaluate MRA findings. Results the average follow-up duration was ten years and 6 months (range, 10–11 years). No complications occurred. At the final follow-up, all scores (clinical, functional and MOCART) improved. In all but one of the patients MRA showed complete osteochondral repair. Conclusions the fixation of large and unstable OCD lesions with mosaicplasty may be a good option for treating type II or III OCD lesions in adults. The advantages of this technique include stable fixation, promotion of blood supply to the base of the OCD fragment, and grafting of autologous cancellous bone that stimulates healing with preservation of the articular surface. Level of evidence Level IV, therapeutic case series. PMID:26904522

  2. Misinterpretation of ischaemic infarct location in relationship to the cerebrovascular territories

    PubMed Central

    Hartkamp, Nolan S; Hendrikse, J; De Cocker, Laurens J L; de Borst, Gert Jan; Kappelle, L Jaap; Bokkers, Reinoud P H

    2016-01-01

    Purpose Cerebral perfusion territories are known to vary widely among individuals. This may lead to misinterpretation of the symptomatic artery in patients with ischaemic stroke to a wrong assumption of the underlying aetiology being thromboembolic or hypoperfusion. The aim of the present study was to investigate such potential misinterpretation with territorial arterial spin labelling (T-ASL) by correlating infarct location with imaging of the perfusion territory of the carotid arteries or basilar artery. Materials and methods 223 patients with subacute stroke underwent MRI including structural imaging scans to determine infarct location, time-of-flight MR angiography (MRA) to determine the morphology of the circle of Willis and T-ASL to identify the perfusion territories of the internal carotid arteries, and basilar artery. Infarct location and the perfusion territory of its feeding artery were classified with standard MRI and MRA according to a perfusion atlas, and were compared to the classification made according to T-ASL. Results A total of 149 infarctions were detected in 87 of 223 patients. 15 out of 149 (10%) infarcts were erroneously attributed to a single perfusion territory; these infarcts were partly located in the originally determined perfusion territory but proved to be localised in the border zone with the adjacent perfusion territory instead. 12 out of 149 (8%) infarcts were misclassified with standard assessments and were not located in the original perfusion territory. Conclusions T-ASL with territorial perfusion imaging may provide important additional information for classifying the symptomatic brain-feeding artery when compared to expert evaluation with MRI and MRA. PMID:27466359

  3. Development of an automated processing method to detect still timing of cardiac motion for coronary magnetic resonance angiography

    NASA Astrophysics Data System (ADS)

    Asou, Hiroya; Ichikawa, Katsuhiro; Imada, Naoyuki; Masuda, Takanori; Satou, Tomoyasu

    2011-03-01

    Whole-heart coronary magnetic resonance angiography (WH-MRA) is useful noninvasive examination. Its signal acquisition is performed during very short still timing in each cardiac motion cycle, and therefore the adequate still timing selection is important to obtain the better image quality. However, since the current available selection method is only manual one using visual comparison of cine MRI images with different phases, the selected timings are often incorrect and their reproducibility is not sufficient. We developed an automated selection method to detect the best still timing for the WH-MRA and compared the automated method with conventional manual one. Cine MRI images were used for the analysis. In order to extract the high-speed cardiac cine image, each phase directional pixel set at each pixel position in all cine images were processed by a high-pass filtering using the Fourie transform. After this process, the cine images with low speed timing became dark, and the optimal timing could be determined by a threshold processing. We took ten volunteers' WH-MRA with the manually and automatically selected timings, and visually assessed image quality of each image on a 5-point scale (1=excellent, 2=very good, 3=good, 4=fair, 5=poor). The mean scores of the manual and automatic methods for right coronary arteries (RCA), LDA left anterior descending arteries (LAD) and LCX left circumflex arteries (LCX) were 4.2+/-0.38, 4.1+/-0.44, 3.9+/-0.52 and 4.1+/-0.42, 4.1+/-0.24, 3.2+/-0.35 respectively. The score were increased by our method in the RCA and LCX, and the LCX was significant (p<0.05). As the results, it was indicated that our automated method could determine the optimal cardiac phase more accurately than or equally to the conventional manual method.

  4. Corneal Segmentation Analysis Increases Glaucoma Diagnostic Ability of Optic Nerve Head Examination, Heidelberg Retina Tomograph's Moorfield's Regression Analysis, and Glaucoma Probability Score.

    PubMed

    Saenz-Frances, F; Jañez, L; Berrozpe-Villabona, C; Borrego-Sanz, L; Morales-Fernández, L; Acebal-Montero, A; Mendez-Hernandez, C D; Martinez-de-la-Casa, J M; Santos-Bueso, E; Garcia-Sanchez, J; Garcia-Feijoo, J

    2015-01-01

    Purpose. To study whether a corneal thickness segmentation model, consisting in a central circular zone of 1 mm radius centered at the corneal apex (zone I) and five concentric rings of 1 mm width (moving outwards: zones II to VI), could boost the diagnostic accuracy of Heidelberg Retina Tomograph's (HRT's) MRA and GPS. Material and Methods. Cross-sectional study. 121 healthy volunteers and 125 patients with primary open-angle glaucoma. Six binary multivariate logistic regression models were constructed (MOD-A1, MOD-A2, MOD-B1, MOD-B2, MOD-C1, and MOD-C2). The dependent variable was the presence of glaucoma. In MOD-A1, the predictor was the result (presence of glaucoma) of the analysis of the stereophotography of the optic nerve head (ONH). In MOD-B1 and MOD-C1, the predictor was the result of the MRA and GPS, respectively. In MOD-B2 and MOD-C2, the predictors were the same along with corneal variables: central, overall, and zones I to VI thicknesses. This scheme was reproduced for model MOD-A2 (stereophotography along with corneal variables). Models were compared using the area under the receiver operator characteristic curve (AUC). Results. MOD-A1-AUC: 0.771; MOD-A2-AUC: 0.88; MOD-B1-AUC: 0.736; MOD-B2-AUC: 0.845; MOD-C1-AUC: 0.712; MOD-C2-AUC: 0.838. Conclusion. Corneal thickness variables enhance ONH assessment and HRT's MRA and GPS diagnostic capacity.

  5. Suppression of Rapidly Progressive Mouse Glomerulonephritis with the Non-Steroidal Mineralocorticoid Receptor Antagonist BR-4628

    PubMed Central

    Ma, Frank Y.; Han, Yingjie; Nikolic-Paterson, David J.; Kolkhof, Peter; Tesch, Greg H.

    2015-01-01

    Background/Aim Steroidal mineralocorticoid receptor antagonists (MRAs) are effective in the treatment of kidney disease; however, the side effect of hyperkalaemia, particularly in the context of renal impairment, is a major limitation to their clinical use. Recently developed non-steroidal MRAs have distinct characteristics suggesting that they may be superior to steroidal MRAs. Therefore, we explored the benefits of a non-steroidal MRA in a model of rapidly progressive glomerulonephritis. Methods Accelerated anti-glomerular basement membrane (GBM) glomerulonephritis was induced in groups of C57BL/6J mice which received no treatment, vehicle or a non-steroidal MRA (BR-4628, 5mg/kg/bid) from day 0 until being killed on day 15 of disease. Mice were examined for renal injury. Results Mice with anti-GBM glomerulonephritis which received no treatment or vehicle developed similar disease with severe albuminuria, impaired renal function, glomerular tuft damage and crescents in 40% of glomeruli. In comparison, mice which received BR-4628 displayed similar albuminuria, but had improved renal function, reduced severity of glomerular tuft lesions and a 50% reduction in crescents. The protection seen in BR-4628 treated mice was associated with a marked reduction in glomerular macrophages and T-cells and reduced kidney gene expression of proinflammatory (CCL2, TNF-α, IFN-γ) and profibrotic molecules (collagen I, fibronectin). In addition, treatment with BR-4626 did not cause hyperkalaemia or increase urine Na+/K+ excretion (a marker of tubular dysfunction). Conclusions The non-steroidal MRA (BR-4628) provided substantial suppression of mouse crescentic glomerulonephritis without causing tubular dysfunction. This finding warrants further investigation of non-steroidal MRAs as a therapy for inflammatory kidney diseases. PMID:26700873

  6. Screening for Unruptured Intracranial Aneurysms in Autosomal Dominant Polycystic Kidney Disease: A Survey of 420 Nephrologists

    PubMed Central

    Flahault, Adrien; Trystram, Denis; Fouchard, Marie; Knebelmann, Bertrand; Nataf, François; Joly, Dominique

    2016-01-01

    Background Despite a high prevalence of intracranial aneurysm (ICA) in autosomal dominant polycystic kidney disease (ADPKD), rupture events are rare. The current recommendations for ICA screening are based on expert opinions and studies with low levels of evidence. Objectives The aim of our study was to describe the attitudes of practicing nephrologists in Europe towards screening for ICA using magnetic resonance angiography (MRA). Methods We conducted a web-based survey among 1315 European French-speaking nephrologists and nephrology residents. An anonymous, electronic questionnaire including 24 independent questions related to ICA screening modalities, indications and participant profiles was sent by email between September and December 2014. Four hundred and twenty nephrologists (mostly from France) participated, including 31 nephrology residents; the response rate was 32%. Results Systematic screening for ICA was advocated by 28% of the nephrologists. A family history of ICA rupture, sudden death, stroke and migraine were consensual indications for screening (> 90% of the panel). In other clinical situations largely not covered by the recommendations (pregnancy, nephrectomy, kidney transplantation, cardiac or hepatic surgery, uncontrolled hypertension, lack of familial ADPKD history, at-risk activity, tobacco use), the attitudes towards screening were highly divergent. ICA screening was influenced by nephrologists experience with ADPKD and by their practice setting. The majority of participants (57%) would not repeat a normal ICA screening. Only a few participants (22%) knew that non-contrast MRA was the reference diagnostic tool for ICA screening, whereas most participants thought that contrast enhancement was necessary to screen for ICA. The results from the nephrology residents were analyzed separately and yielded similar results. Conclusion This practice survey revealed that most nephrologists follow the current recommendations for the initial screening of

  7. Review of Source Images is Necessary for the Evaluation of Gadolinium-Enhanced MR Angiography for Renal Artery Stenosis

    SciTech Connect

    Wehrschuetz, M. Aschauer, M.; Portugaller, H.; Stix, A.; Wehrschuetz-Sigl, E.; Hausegger, K.; Ebner, F.

    2004-09-15

    The purpose of this study was to assess interobserver variability and accuracy in the evaluation of renal artery stenosis (RAS) with gadolinium-enhanced MR angiography (MRA) and digital subtraction angiography (DSA) in patients with hypertension. The authors found that source images are more accurate than maximum intensity projection (MIP) for depicting renal artery stenosis. Two independent radiologists reviewed MRA and DSA from 38 patients with hypertension. Studies were postprocessed to display images in MIP and source images. DSA was the standard for comparison in each patient. For each main renal artery, percentage stenosis was estimated for any stenosis detected by the two radiologists. To calculate sensitivity, specificity and accuracy, MRA studies and stenoses were categorized as normal, mild (1-39%), moderate (40-69%) or severe ({>=}70%), or occluded. DSA stenosis estimates of 70% or greater were considered hemodynamically significant. Analysis of variance demonstrated that MIP estimates of stenosis were greater than source image estimates for both readers. Differences in estimates for MIP versus DSA reached significance in one reader. The interobserver variance for MIP, source images and DSA was excellent (0.80< {kappa}{<=} 0.90). The specificity of source images was high (97%) but less for MIP (87%); average accuracy was 92% for MIP and 98% for source images. In this study, source images are significantly more accurate than MIP images in one reader with a similar trend was observed in the second reader. The interobserver variability was excellent. When renal artery stenosis is a consideration, high accuracy can only be obtained when source images are examined.

  8. Improved Cerebral Time-of-Flight Magnetic Resonance Angiography at 7 Tesla – Feasibility Study and Preliminary Results Using Optimized Venous Saturation Pulses

    PubMed Central

    Wrede, Karsten H.; Johst, Sören; Dammann, Philipp; Özkan, Neriman; Mönninghoff, Christoph; Kraemer, Markus; Maderwald, Stefan; Ladd, Mark E.; Sure, Ulrich; Umutlu, Lale; Schlamann, Marc

    2014-01-01

    Purpose Conventional saturation pulses cannot be used for 7 Tesla ultra-high-resolution time-of-flight magnetic resonance angiography (TOF MRA) due to specific absorption rate (SAR) limitations. We overcome these limitations by utilizing low flip angle, variable rate selective excitation (VERSE) algorithm saturation pulses. Material and Methods Twenty-five neurosurgical patients (male n = 8, female n = 17; average age 49.64 years; range 26–70 years) with different intracranial vascular pathologies were enrolled in this trial. All patients were examined with a 7 Tesla (Magnetom 7 T, Siemens) whole body scanner system utilizing a dedicated 32-channel head coil. For venous saturation pulses a 35° flip angle was applied. Two neuroradiologists evaluated the delineation of arterial vessels in the Circle of Willis, delineation of vascular pathologies, presence of artifacts, vessel-tissue contrast and overall image quality of TOF MRA scans in consensus on a five-point scale. Normalized signal intensities in the confluence of venous sinuses, M1 segment of left middle cerebral artery and adjacent gray matter were measured and vessel-tissue contrasts were calculated. Results Ratings for the majority of patients ranged between good and excellent for most of the evaluated features. Venous saturation was sufficient for all cases with minor artifacts in arteriovenous malformations and arteriovenous fistulas. Quantitative signal intensity measurements showed high vessel-tissue contrast for confluence of venous sinuses, M1 segment of left middle cerebral artery and adjacent gray matter. Conclusion The use of novel low flip angle VERSE algorithm pulses for saturation of venous vessels can overcome SAR limitations in 7 Tesla ultra-high-resolution TOF MRA. Our protocol is suitable for clinical application with excellent image quality for delineation of various intracranial vascular pathologies. PMID:25232868

  9. Vascular hand-arm vibration syndrome--magnetic resonance angiography.

    PubMed

    Poole, C J M; Cleveland, T J

    2016-01-01

    The diagnosis of vascular hand-arm vibration syndrome (HAVS) requires consistent symptoms, photographic evidence of digital blanching and sufficient exposure to hand-transmitted vibration (HTV; A(8) > 2.5 m/s2). There is no reliable quantitative investigation for distinguishing HAVS from other causes of Raynaud's phenomenon and from normal individuals. Hypothenar and thenar hammer syndromes produce similar symptoms to HAVS but are difficult to diagnose clinically and may be confused with HAVS. Magnetic resonance angiography (MRA) is a safe and minimally invasive method of visualizing blood vessels. Three cases of vascular HAVS are described in which MRA revealed occlusions of the ulnar, radial and superficial palmar arteries. It is proposed that HTV was the cause of these occlusions, rather than blows to the hand unrelated to vibration, the assumed mechanism for the hammer syndromes. All three cases were advised not to expose their hands to HTV despite one of them being at Stockholm vascular stage 2 (early). MRA should be the investigation of choice for stage 2 vascular HAVS or vascular HAVS with unusual features or for a suspected hammer syndrome. The technique is however technically challenging and best done in specialist centres in collaboration with an occupational physician familiar with the examination of HAVS cases. Staging for HAVS should be developed to include anatomical arterial abnormalities as well as symptoms and signs of blanching. Workers with only one artery supplying a hand, or with only one palmar arch, may be at increased risk of progression and therefore should not be exposed to HTV irrespective of their Stockholm stage.

  10. DIAGNOSTIC IMAGING IN A DIRECT-ACCESS SPORTS PHYSICAL THERAPY CLINIC: A 2-YEAR RETROSPECTIVE PRACTICE ANALYSIS

    PubMed Central

    Dedekam, Erik A.; Johnson, Michael R.; Dembowski, Scott C.; Westrick, Richard B.; Goss, Donald L.

    2016-01-01

    Background While advanced diagnostic imaging is a large contributor to the growth in health care costs, direct-access to physical therapy is associated with decreased rates of diagnostic imaging. No study has systematically evaluated with evidence-based criteria the appropriateness of advanced diagnostic imaging, including magnetic resonance imaging (MRI), when ordered by physical therapists. The primary purpose of this study was to describe the appropriateness of magnetic resonance imaging (MRI) or magnetic resonance arthrogram (MRA) exams ordered by physical therapists in a direct-access sports physical therapy clinic. Study Design Retrospective observational study of practice. Hypothesis Greater than 80% of advanced diagnostic imaging orders would have an American College of Radiology (ACR) Appropriateness Criteria rating of greater than 6, indicating an imaging order that is usually appropriate. Methods A 2-year retrospective analysis identified 108 MRI/MRA examination orders from four physical therapists. A board-certified radiologist determined the appropriateness of each order based on ACR appropriateness criteria. The principal investigator and co-investigator radiologist assessed agreement between the clinical diagnosis and MRI/surgical findings. Results Knee (31%) and shoulder (25%) injuries were the most common. Overall, 55% of injuries were acute. The mean ACR rating was 7.7; scores from six to nine have been considered appropriate orders and higher ratings are better. The percentage of orders complying with ACR appropriateness criteria was 83.2%. Physical therapist's clinical diagnosis was confirmed by MRI/MRA findings in 64.8% of cases and was confirmed by surgical findings in 90% of cases. Conclusions Physical therapists providing musculoskeletal primary care in a direct-access sports physical therapy clinic appropriately ordered advanced diagnostic imaging in over 80% of cases. Future research should prospectively compare physical therapist

  11. Simultaneous Magnetic Resonance Angiography and Perfusion (MRAP) Measurement: Initial Application in Lower Extremity Skeletal Muscle

    PubMed Central

    Wright, Katherine L.; Seiberlich, Nicole; Jesberger, John A.; Nakamoto, Dean A.; Muzic, Raymond F.; Griswold, Mark A.; Gulani, Vikas

    2012-01-01

    Purpose To obtain a simultaneous 3D MR Angiography and Perfusion (MRAP) using a single acquisition, and to demonstrate MRAP in the lower extremities. A time-resolved contrast-enhanced exam is utilized in MRAP to simultaneously acquire a contrast-enhanced MR angiography (MRA) and dynamic contrast-enhanced (DCE) perfusion, which currently requires separate acquisitions and thus two contrast doses. MRAP can be used to assess large and small vessels in vascular pathologies such as peripheral arterial disease. Materials and Methods MRAP was performed on ten volunteers following unilateral plantar flexion exercise (one leg exercised and one rested) on two separate days. Data were acquired after administration of a single dose of contrast agent using an optimized sampling strategy, parallel imaging, and partial-Fourier acquisition to obtain a high spatial resolution, 3D-MRAP frame every four seconds. Two radiologists assessed MRAs for image quality, a signal-to-noise ratio (SNR) analysis was performed, and pharmacokinetic modeling yielded perfusion (Ktrans). Results MRA images had high SNR and radiologist-assessed diagnostic quality. Mean Ktrans±standard error were 0.136±0.009, 0.146±0.012, and 0.191±0.012 min−1 in the resting tibialis anterior, gastrocnemius, and soleus, respectively, which significantly increased with exercise to 0.291±0.018, 0.270±0.019, and 0.338±0.022 min−1. Bland-Altman analysis showed good repeatability. Conclusion MRAP provides simultaneous high-resolution MRA and quantitative DCE exams to assess large and small vessels with a single contrast dose. Application in skeletal muscle shows quantitative, repeatable perfusion measurements, and the ability to measure physiological differences. PMID:23389970

  12. Colonization of UK coastal realignment sites by mosquitoes: implications for design, management, and public health.

    PubMed

    Medlock, J M; Vaux, A G C

    2013-06-01

    Coastal realignment is now widely instituted in the UK as part of local flood risk management plans to compensate for the loss of European protected habitat and to mitigate the effects of sea-level rise and coastal squeeze. Coastal aquatic habitats have long been known to provide suitable habitats for brackish-water mosquitoes and historically, coastal marshes were considered to support anopheline mosquito populations that were responsible for local malaria transmission. This study surveyed the eight largest managed realignment (MRA) sites in England (Essex and the Humber) for mosquito habitats. The apparent absence of anopheline mosquitoes exploiting aquatic habitats at all of these sites suggests that the risk of malaria associated with MRA sites is currently negligible. However, three of the eight sites supported populations of two nuisance and potential arboviral vector species, Aedes detritus and Aedes caspius. The aquatic habitats that supported mosquitoes resulted from a) specific design aspects of the new sea wall (ballast to mitigate wave action and constructed saline borrow ditches) that could be designed out or managed or b) isolated pools created through silt accretion or expansion of flooded zones to neighbouring pasture. The public health risks and recommendations for management are discussed in this report. This report highlights the need for pro-active public health impact assessments prior to MRA development in consultation with the Health Protection Agency, as well as the need for a case-by-case approach to design and management to mitigate mosquito or mosquito-borne disease issues now and in the future.

  13. Endothelial and smooth muscle properties of coronary and mesenteric resistance arteries in spontaneously hypertensive rats compared to WKY rats.

    PubMed

    Pourageaud, F; Freslon, J L

    1995-01-01

    To investigate if the functional alterations observed in resistance arteries of spontaneously hypertensive rats (SHRs) were also present at the coronary level, in vitro experiments were performed in mesenteric resistance arteries (MRA) and in right (RIC) and left interventricular coronary (LIC) arteries taken from 15-25-week-old SHR and age-matched Wistar Kyoto rats WKYs. Using a passive extension protocol, internal diameters corresponding to 100 mmHg intraluminal pressure (D100) were determined and vessels were set up to a normalized internal diameter (0.9 D100). SHR mesenteric resistance arteries had a significantly smaller diameter compared to WKY arteries, whereas both types of SHR coronary arteries had a greater diameter compared to those of WKY rats. In arteries in the absence of contracting agonist, nitro-L-arginine (NOLA, 100 microM) induced a progressive rise in basal tone, which could be reversed by subsequent addition of L-arginine (100 microM) but not D-arginine (100 microM). When expressed as percent of maximal contractions induced by agonists (noradrenaline, NA [10 microM] in MRA; serotonin, 5-HT [10 microM], in RIC and LIC), these contractions were significantly stronger in WKY compared to SHR coronary and mesenteric resistance arteries. In NA-precontracted MRA and 5HT-precontracted coronary arteries in the presence of indomethacin (10 microM), the magnitude of acetylcholine-induced maximal relaxations (expressed as percent of maximal contractions induced by agonists) was greater in WKY compared to SHR arteries. After a 30-min incubation period, NOLA (100 microM) completely inhibited relaxations induced by acetylcholine (0.01-10 microM) in all types of precontracted arteries.(ABSTRACT TRUNCATED AT 250 WORDS)

  14. Comparison of the air kerma standards of the IAEA and the BIPM in mammography x-rays

    NASA Astrophysics Data System (ADS)

    Kessler, C.; Burns, D. T.; Czap, L.; Csete, I.; Gomola, I.

    2013-01-01

    The Dosimetry Laboratory of the International Atomic Energy Agency (IAEA), Seibersdorf, Austria, calibrates reference standards in mammography x-ray beams for IAEA/WHO SSDL Network members (more than 80 laboratories worldwide). As a signatory of the Mutual Recognition Arrangement (CIPM MRA), the IAEA laboratory maintains a Quality Management System (QMS) complying with ISO 17025 and requires updated 'supporting evidence' for its dosimetry calibration and measurement capabilities (CMC), first published in Appendix C of the CIPM MRA key comparison database in 2007. For this purpose, an indirect comparison has been made between the air kerma standards of the IAEA and the Bureau International des Poids et Mesures (BIPM) in the mammography x-ray range from 25 kV to 35 kV, using as transfer instruments two thin-window parallel-plate ionization chambers belonging to the IAEA. The IAEA and BIPM standards for mammography x-rays are shown to be in agreement within the standard uncertainty of the comparison of 5.5 parts in 103. This agreement can be used to support the calibration and measurements capabilities of the IAEA listed in Appendix C of the key comparison database. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  15. A Scale-Adaptive Approach for Spatially-Varying Urban Morphology Characterization in Boundary Layer Parametrization Using Multi-Resolution Analysis

    NASA Astrophysics Data System (ADS)

    Mouzourides, P.; Kyprianou, A.; Neophytou, M. K.-A.

    2013-12-01

    Urban morphology characterization is crucial for the parametrization of boundary-layer development over urban areas. One complexity in such a characterization is the three-dimensional variation of the urban canopies and textures, which are customarily reduced to and represented by one-dimensional varying parametrization such as the aerodynamic roughness length and zero-plane displacement . The scope of the paper is to provide novel means for a scale-adaptive spatially-varying parametrization of the boundary layer by addressing this 3-D variation. Specifically, the 3-D variation of urban geometries often poses questions in the multi-scale modelling of air pollution dispersion and other climate or weather-related modelling applications that have not been addressed yet, such as: (a) how we represent urban attributes (parameters) appropriately for the multi-scale nature and multi-resolution basis of weather numerical models, (b) how we quantify the uniqueness of an urban database in the context of modelling urban effects in large-scale weather numerical models, and (c) how we derive the impact and influence of a particular building in pre-specified sub-domain areas of the urban database. We illustrate how multi-resolution analysis (MRA) addresses and answers the afore-mentioned questions by taking as an example the Central Business District of Oklahoma City. The selection of MRA is motivated by its capacity for multi-scale sampling; in the MRA the "urban" signal depicting a city is decomposed into an approximation, a representation at a higher scale, and a detail, the part removed at lower scales to yield the approximation. Different levels of approximations were deduced for the building height and planar packing density . A spatially-varying characterization with a scale-adaptive capacity is obtained for the boundary-layer parameters (aerodynamic roughness length and zero-plane displacement ) using the MRA-deduced results for the building height and the planar packing

  16. Muraymycin nucleoside-peptide antibiotics: uridine-derived natural products as lead structures for the development of novel antibacterial agents

    PubMed Central

    Wirth, Marius; Niro, Giuliana; Leyerer, Kristin

    2016-01-01

    Summary Muraymycins are a promising class of antimicrobial natural products. These uridine-derived nucleoside-peptide antibiotics inhibit the bacterial membrane protein translocase I (MraY), a key enzyme in the intracellular part of peptidoglycan biosynthesis. This review describes the structures of naturally occurring muraymycins, their mode of action, synthetic access to muraymycins and their analogues, some structure–activity relationship (SAR) studies and first insights into muraymycin biosynthesis. It therefore provides an overview on the current state of research, as well as an outlook on possible future developments in this field. PMID:27340469

  17. [Trigeminalgia caused by neurovascular compression in 12 years old girl].

    PubMed

    Steczkowska, Małgorzata; Herman-Sucharska, Izabela; Gleń, Agnieszka; Gergont, Aleksandra; Skowronek-Bała, Barbara

    2007-01-01

    Trigeminalgia is one of the most frequent clinical problems, common in adults but also found in children. In this paper we described a case of 12 years old girl with symptomatic trigeminalgia caused by neurovascular compression, hospitalized in the Department of Pediatric Neurology Jagiellonian University in Kraków. It creates a very difficult diagnostic problem. The girl was first unsuccessfully treated with carbamazepine and afterwards the surgery of neurovascular decompression was performed. We emphasis the crucial role of MR and MRA in cases refractory to classic pharmacotherapy.

  18. Transboundary study of the Milk River aquifer (Canada, USA): geological, conceptual and numerical models for the sound management of the regional groundwater resources

    NASA Astrophysics Data System (ADS)

    Pétré, Marie-Amélie; Rivera, Alfonso; Lefebvre, René

    2016-04-01

    The Milk River transboundary aquifer straddles southern Alberta (Canada) and northern Montana (United States), a semi-arid and water-short region. The extensive use of this regional sandstone aquifer over the 20th century has led to a major drop in water levels locally, and concerns about the durability of the resources have been raised since the mid-1950. Even though the Milk River Aquifer (MRA) has been studied for decades, most of the previous studies were limited by the international border, preventing a sound understanding of the aquifer dynamics. Yet, a complete portrait of the aquifer is required for proper management of this shared resource. The transboundary study of the MRA aims to overcome transboundary limitations by providing a comprehensive characterization of the groundwater resource at the aquifer scale, following a three-stage approach: 1) The development of a 3D unified geological model of the MRA (50,000 km2). The stratigraphic framework on both sides of the border was harmonized and various sources of geological data were unified to build the transboundary geological model. The delineation of the aquifer and the geometry and thicknesses of the geological units were defined continuously across the border. 2) Elaboration of a conceptual hydrogeological model by linking hydrogeological and geochemical data with the 3D unified geological model. This stage is based on a thorough literature review and focused complementary field work on both sides of the border. The conceptual model includes the determination of the groundwater flow pattern, the spatial distribution of hydraulic properties, a groundwater budget and the definition of the groundwater types. Isotopes (3H, 14C, 36Cl) were used to delineate the recharge area as well as the active and low-flow areas. 3) The building of a 3D numerical groundwater flow model of the MRA (26,000 km2). This model is a transposition of the geological and hydrogeological conceptual models. A pre

  19. A comparison in conventional mass measurements (SIM.M.M-S3)

    NASA Astrophysics Data System (ADS)

    García, Francisco; Bautista, Marco; Müller-Schöll, Christian; Ramírez, Ricardo; Schröter, Georg; Florencio, Arnaldo; Hernández, Raúl; Castillo, Juan Carlos; Leyton, Fernando

    2011-01-01

    A comparison in the calibration of mass standards at nominal values 100 mg, 20 g and 1 kg was carried out between CESMEC (Chile), IBMETRO (Bolivia) and INTN (Paraguay) in the period 2007 to 2008. Results were interpreted in terms of equivalence and a good level of agreement between the participants was demonstrated. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by SIM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  20. Neurodegenerative disease high-field imaging

    PubMed Central

    van der Grond, J.; van Buchem, M.A.; van Zijl, P.; Webb, A.G.

    2012-01-01

    High field magnetic resonance imaging is showing potential for imaging of neurodegenerative diseases. 7 T MRI is beginning to be used in a clinical research setting and the theoretical benefits, i.e. higher signal-to-noise, sensitivity to iron, improved MRA and increased spectral resolution in spectroscopy are being confirmed. Despite the limited number of studies to date, initial results in patients with multiple sclerosis, Alzheimer’s disease and Huntington’s disease show promising additional features in contrast that may assist in better diagnosis of these disorders. PMID:22548926

  1. [Neonatal cerebral venous thrombosis: diagnosis by magnetic resonance angiography].

    PubMed

    Puig, J; Pedraza, S; Méndez, J; Trujillo, A

    2006-01-01

    Neonatal cerebral venous thrombosis (NCVT) is a rare, severe neuropathology of multiple etiology and variable clinical presentation. We describe the case of a 25-day-old infant that presented with a tonic convulsion. Ultrasound examination showed tetraventricular hemorrhage. Magnetic resonance imaging (MRI) showed the presence of acute thrombosis of the deep and superficial venous systems associated to a hemorrhagic infarct of the left thalamus. Coagulation study revealed a deficit of protein C. Thrombosis of deep cerebral veins must be ruled out as a cause of a neonatal convulsive crisis. The presence of a hemorrhagic thalamic lesion supports the diagnosis of NCVT, which must in turn be confirmed by magnetic resonance angiography (MRA).

  2. Acute ischemic stroke in a 19 month old following minor head trauma: case report and review of the literature.

    PubMed

    Garla, Vishnu; Pino, Eduardo; Coulon, Richard; Wolfer, Rebecca

    2014-01-01

    Minor head trauma is a very rare cause of ischemic stroke in the pediatric population. We describe a nineteen month old patient who developed left hemiparesis and subsequently left facial palsy after a fall. MRI of the brain showed hypodensities in the basal ganglia, internal capsule and caudate nucleus consistent with stroke. Echocardiogram and MRA were normal. Hypercoaguable work up showed that the patient was a carrier for a single MTHFR gene. The patient was treated conservatively. On follow up two weeks later his facial palsy had resolved and strength in the extremities improved. Although a rare condition awareness about this is necessary as there can be considerable delay in its recognition.

  3. International Comparisions Database

    National Institute of Standards and Technology Data Gateway

    International Comparisions Database (Web, free access)   The International Comparisons Database (ICDB) serves the U.S. and the Inter-American System of Metrology (SIM) with information based on Appendices B (International Comparisons), C (Calibration and Measurement Capabilities) and D (List of Participating Countries) of the Comit� International des Poids et Mesures (CIPM) Mutual Recognition Arrangement (MRA). The official source of the data is The BIPM key comparison database. The ICDB provides access to results of comparisons of measurements and standards organized by the consultative committees of the CIPM and the Regional Metrology Organizations.

  4. Severe amnesia following a unilateral temporal lobe stroke.

    PubMed

    Grewal, Raji P

    2003-01-01

    A 60 year old right-handed man developed severe amnesia following a left medial temporal stroke as documented by cerebral MRI, MRA and SPECT scans. Neuropsychological evaluation 13 weeks after the stroke showed a profound retrograde amnesia characterised by memory loss for public facts and events over the previous four decades. In addition, autobiographical memory showed selective loss of personal episodic memory with relative preservation of personal semantic memory. The development of this degree of amnesia with these features following a unilateral temporal lobe lesion is unusual. The possible neuroanatomical mechanisms underlying the amnesia and how they relate to current theories of memory loss are discussed. PMID:12464535

  5. [Trombosis of the middle cerebral artery as the cause of cerebrovascular insult (CVI) and recognition of the etiologic factors for CVI].

    PubMed

    Hajro, Tarik; Ramić, Ibrahim; Alajbegović, Azra

    2004-01-01

    In the paper is shown the case of the patient of the CVI life, age of 40 years. It was about the vascular lesion left of the temperoparienal MRA shew the amputation of amputation of the temporal branches art. cerebri medii from the left side. The patient 6 years before she suffered of CVI infract myocard after which she recovered well. After the performed neurologic and physiatric treatment it came to the strength of the rude motor strength with the normalization of the speech.

  6. Noninvasive assessment of portomesenteric venous thrombosis: current concepts and imaging strategies.

    PubMed

    Bradbury, Michelle S; Kavanagh, Peter V; Chen, Michael Y; Weber, Therese M; Bechtold, Robert E

    2002-01-01

    Rapid, noninvasive imaging strategies, especially multidetector spiral CT and CT angiography (CTA) as well as gadolinium-enhanced MR angiography (MRA), have facilitated early diagnosis of splanchnic venous thrombosis, a potentially lethal cause of intestinal ischemia. Single breath-hold volumetric acquisitions permit superior temporal and contrast resolution while eliminating motion artifact and suppressing respiratory misregistration. Increased spatial resolution is aided by thinner slice collimation. These cross-sectional imaging techniques are becoming a preferred noninvasive alternative to conventional selective mesenteric angiography with delayed imaging for venous evaluation and should be considered the primary diagnostic modalities for evaluating patients with high clinical suspicion of nonsurgical mesenteric ischemia.

  7. Clinical and Radiological Evaluation after Arthroscopic Rotator Cuff Repair Using Suture Bridge Technique

    PubMed Central

    Lee, Kwang Won; Bae, Kyoung Wan; Choy, Won Sik

    2013-01-01

    Background We retrospectively assessed the clinical outcomes and investigated risk factors influencing retear after arthroscopic suture bridge repair technique for rotator cuff tear through clinical assessment and magnetic resonance arthrography (MRA). Methods Between January 2008 and April 2011, sixty-two cases of full-thickness rotator cuff tear were treated with arthroscopic suture bridge repair technique and follow-up MRA were performed. The mean age was 56.1 years, and mean follow-up period was 27.4 months. Clinical and functional outcomes were assessed using range of motion, Korean shoulder score, Constant score, and UCLA score. Radiological outcome was evaluated with preoperative and follow-up MRA. Potential predictive factors that influenced cuff retear, such as age, gender, geometric patterns of tear, size of cuff tear, acromioplasty, fatty degeneration, atrophy of cuff muscle, retraction of supraspinatus, involved muscles of cuff and osteolysis around the suture anchor were evaluated. Results Thirty cases (48.4%) revealed retear on MRA. In univariable analysis, retear was significantly more frequent in over 60 years age group (62.5%) than under 60 years age group (39.5%; p = 0.043), and also in medium to large-sized tear than small-sized tear (p = 0.003). There was significant difference in geometric pattern of tear (p = 0.015). In multivariable analysis, only age (p = 0.036) and size of tear (p = 0.030) revealed a significant difference. The mean active range of motion for forward flexion, abduction, external rotation at the side and internal rotation at the side were significantly improved at follow-up (p < 0.05). The mean Korean shoulder score, Constant score, and UCLA score increased significantly at follow-up (p < 0.01). The range of motion, Korean shoulder score, Constant score, and UCLA score did not differ significantly between the groups with retear and intact repairs (p > 0.05). The locations of retear were insertion site in 10 cases (33.3%) and

  8. Comparison APMP.QM-S2.1: oxygen in nitrogen at atmospheric level

    NASA Astrophysics Data System (ADS)

    Kim, B. M.; Kim, K.; Jung, J.; Oh, S.; Hui, L.; Li, H.; Keat, T. B.; Ann, C. H.

    2016-01-01

    This document describes results of the bilateral comparison of an oxygen in nitrogen gas mixture. The nominal amount-of-substance fraction was 0.2 mol/mol oxygen in nitrogen Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  9. Key comparison on pH of an unknown phosphate buffer

    NASA Astrophysics Data System (ADS)

    Bastkowski, F.; Spitzer, P.; Sander, B.; Máriássy, M.; Dimitrova, L.; Reyes, A.; Rodríguez, A.; Manzano, V. Lara; Vospelova, A.; Jakobsen, P. T.; Pawlina, M.; Korol, M.; Kozlowski, W.; Delgado, M.; Ticona Canaza, G.; Dias, J. C.; Gonzaga, F. B.; Nagyné Szilágyi, Z.; Jakusovszky, B.; Nongluck, T.; Waters, J.; Pratt, K. W.; Asakai, T.; Maksimov, I.; Hankova, Z.; Uysal, E.; Gavrilkin, V.; Prokunin, S. V.; Ferreira, E.; Fajardo, S.

    2016-01-01

    Results of CCQM-K99 key comparison on unknown phosphate buffer pH ~ 7.5 at 5 °C, 15 °C, 25 °C, 37 °C and 50 °C are reported. Good agreement is found between the majority of participants. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  10. EURAMET.M.M-S8: comparison of 500 kg and 1000 kg weights

    NASA Astrophysics Data System (ADS)

    Gutfelt, B.; Koponen, P.; Riski, K.; Vabson, V.

    2016-01-01

    Mass comparison of conventional masses of 500 kg and 1000 kg weights between three laboratories (AS Metrosert, MIKES, and SP) was carried out in 2012. MIKES was the pilot laboratory. For both 500 kg and 1000 kg, the results show an agreement between the laboratories. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  11. Final report. SIM comparison in mass standards SIM.M.M-K4

    NASA Astrophysics Data System (ADS)

    Becerra, L. O.; Peña, L. M.; Luján, L.; Díaz, J. C.; Centeno, L. M.; Loayza, V.; Cacais, F.; Olman, Ramos; Rodriguez, S.; Garcia, Fe; Garcia, Fr; Leyton, F.; Santo, C.; Caceres, J.; Kornblit, F.; Leiblich, J.; Jacques, C.

    2016-01-01

    This report summarizes the results of a SIM comparison of a 1 kg mass standard carried out by 7 NMIs. The results reported by the participants are consistent with each other and they can be linked to the comparison CCM.M-K4 with satisfactory degrees of equivalence. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  12. Force Euramet supplementary comparison EURAMET.M.F-S4 (Euramet Project 1311)10 kN and 20 kN

    NASA Astrophysics Data System (ADS)

    Averlant, P.; Duflon, C.

    2016-01-01

    This report details the results of a bilateral force comparison carried out between the KIM-LIPI (Indonesia) and the LNE (France), for force values of 10 kN and 20 kN. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  13. Remotely Controlled Mandibular Protrusion during Sleep Predicts Therapeutic Success with Oral Appliances in Patients with Obstructive Sleep Apnea

    PubMed Central

    Remmers, John; Charkhandeh, Shouresh; Grosse, Joshua; Topor, Zbigniew; Brant, Rollin; Santosham, Peter; Bruehlmann, Sabina

    2013-01-01

    Study Objectives: The present study addresses the need for a validated tool that prospectively identifies favorable candidates for oral appliance therapy in treatment of obstructive sleep apnea. The objective of the study was to evaluate the ability of a mandibular titration study, performed with a remotely controlled mandibular positioner (RCMP), to predict treatment outcome with a mandibular repositioning appliance (MRA) and to predict an effective target protrusive position (ETPP). Design: A prospective, blinded, outcome study. Setting: Standard clinical care with tests performed in the polysomnographic laboratory. Participants: Consecutive patients (n = 67) recruited from a sleep center or a dental practice using broad inclusion criteria (age 21-80 years; AHI > 10/h; BMI < 40 kg/m2). Interventions: Therapeutic outcome with a mandibular protruding oral appliance was predicted following a mandibular protrusive titration study in the polysomnographic laboratory using a remotely controlled positioner and prospectively established predictive rules. An ETPP was also prospectively determined for participants predicted to be therapeutically successful with MRA therapy. All participants were blindly treated with a MRA, at either the predicted ETPP or a sham position, and therapeutic outcome was compared against prediction. Measurements and Results: At the final protrusive position, standard predictive parameters (sensitivity, specificity, positive and negative predictive values) showed statistically significant predictive accuracy (P < 0.05) in the range of 83% to 94%. The predicted ETPP provided an efficacious protrusive position in 87% of participants predicted to be therapeutically successful with MRA therapy (P < 0.05). Conclusions: Using prospectively established rules for interpreting the polysomnographic data, the mandibular titration study predicted mandibular repositioning appliance therapeutic outcome with significant accuracy, particularly with regard to

  14. Muraymycin nucleoside-peptide antibiotics: uridine-derived natural products as lead structures for the development of novel antibacterial agents.

    PubMed

    Wiegmann, Daniel; Koppermann, Stefan; Wirth, Marius; Niro, Giuliana; Leyerer, Kristin; Ducho, Christian

    2016-01-01

    Muraymycins are a promising class of antimicrobial natural products. These uridine-derived nucleoside-peptide antibiotics inhibit the bacterial membrane protein translocase I (MraY), a key enzyme in the intracellular part of peptidoglycan biosynthesis. This review describes the structures of naturally occurring muraymycins, their mode of action, synthetic access to muraymycins and their analogues, some structure-activity relationship (SAR) studies and first insights into muraymycin biosynthesis. It therefore provides an overview on the current state of research, as well as an outlook on possible future developments in this field. PMID:27340469

  15. Skeletal muscle metastasis from uterine leiomyosarcoma.

    PubMed

    O'Brien, J M; Brennan, D D; Taylor, D H; Holloway, D P; Hurson, B; O'Keane, J C; Eustace, S J

    2004-11-01

    A case of a 68-year-old woman who presented with a rapidly enlarging painful right thigh mass is presented. She had a known diagnosis of uterine leiomyosarcoma following a hysterectomy for dysfunctional uterine bleeding. She subsequently developed a single hepatic metastatic deposit that responded well to radiofrequency ablation. Whole-body MRI and MRA revealed a vascular mass in the sartorius muscle and a smaller adjacent mass in the gracilis muscle, proven to represent metastatic leiomyosarcoma of uterine origin. To our knowledge, metastatic uterine leiomyosarcoma to the skeletal muscle has not been described previously in the English medical literature.

  16. Chemical Logic and Enzymatic Machinery for Biological Assembly of Peptidyl Nucleoside Antibiotics

    PubMed Central

    Walsh, Christopher T.; Zhang, Wenjun

    2011-01-01

    Peptidyl nucleoside antibiotics are a group of natural products targeting MraY, a bacterial translocase involved in the lipid-linked cycle in peptidoglycan biosynthesis. In this Perspective, we explore how Nature builds complex peptidyl nucleoside antibiotics scaffolds from simple nucleoside and amino acid building blocks. We discuss the current stage of research on biosynthetic pathways for peptidyl nucleoside antibiotics, primarily focusing on chemical logic and enzymatic machinery for uridine transformation and coupling to peptides. We further survey the nonribosomal biosynthetic paradigm for a subgroup of uridyl peptide antibiotics represented by pacidamycins, concluded by diversification opportunities for antibiotic optimization. PMID:21851099

  17. Optimization of Regularization Parameters in Compressed Sensing of Magnetic Resonance Angiography: Can Statistical Image Metrics Mimic Radiologists' Perception?

    PubMed

    Akasaka, Thai; Fujimoto, Koji; Yamamoto, Takayuki; Okada, Tomohisa; Fushumi, Yasutaka; Yamamoto, Akira; Tanaka, Toshiyuki; Togashi, Kaori

    2016-01-01

    In Compressed Sensing (CS) of MRI, optimization of the regularization parameters is not a trivial task. We aimed to establish a method that could determine the optimal weights for regularization parameters in CS of time-of-flight MR angiography (TOF-MRA) by comparing various image metrics with radiologists' visual evaluation. TOF-MRA of a healthy volunteer was scanned using a 3T-MR system. Images were reconstructed by CS from retrospectively under-sampled data by varying the weights for the L1 norm of wavelet coefficients and that of total variation. The reconstructed images were evaluated both quantitatively by statistical image metrics including structural similarity (SSIM), scale invariant feature transform (SIFT) and contrast-to-noise ratio (CNR), and qualitatively by radiologists' scoring. The results of quantitative metrics and qualitative scorings were compared. SSIM and SIFT in conjunction with brain masks and CNR of artery-to-parenchyma correlated very well with radiologists' visual evaluation. By carefully selecting a region to measure, we have shown that statistical image metrics can reflect radiologists' visual evaluation, thus enabling an appropriate optimization of regularization parameters for CS. PMID:26744843

  18. Dynamic and static contributions of the cerebrovasculature to the resting-state BOLD signal.

    PubMed

    Tak, Sungho; Wang, Danny J J; Polimeni, Jonathan R; Yan, Lirong; Chen, J Jean

    2014-01-01

    Functional magnetic resonance imaging (fMRI) in the resting state, particularly fMRI based on the blood-oxygenation level-dependent (BOLD) signal, has been extensively used to measure functional connectivity in the brain. However, the mechanisms of vascular regulation that underlie the BOLD fluctuations during rest are still poorly understood. In this work, using dual-echo pseudo-continuous arterial spin labeling and MR angiography (MRA), we assess the spatio-temporal contribution of cerebral blood flow (CBF) to the resting-state BOLD signals and explore how the coupling of these signals is associated with regional vasculature. Using a general linear model analysis, we found that statistically significant coupling between resting-state BOLD and CBF fluctuations is highly variable across the brain, but the coupling is strongest within the major nodes of established resting-state networks, including the default-mode, visual, and task-positive networks. Moreover, by exploiting MRA-derived large vessel (macrovascular) volume fraction, we found that the degree of BOLD-CBF coupling significantly decreased as the ratio of large vessels to tissue volume increased. These findings suggest that the portion of resting-state BOLD fluctuations at the sites of medium-to-small vessels (more proximal to local neuronal activity) is more closely regulated by dynamic regulations in CBF, and that this CBF regulation decreases closer to large veins, which are more distal to neuronal activity.

  19. Tolosa-Hunt syndrome masquerading as a carotid artery dissection

    PubMed Central

    Taylor, Elise J; Anders, Ursula M; Martel, Joseph R; Martel, James B

    2014-01-01

    Purpose To demonstrate the difficulties of diagnosing a patient with Tolosa-Hunt syndrome (THS) due to its complicated presentation and extensive diagnostic testing, and how to manage the treatment of a patient in an emergent setting. Patients and methods A female patient with THS affecting the left eye was examined using two magnetic resonance imaging (MRI) scans. The patient was treated with high-dose methylprednisolone (Solu-Medrol®) and prednisone. A follow-up MRI and magnetic resonance angiogram (MRA) was also performed 4 months later. Results The second MRI scan disclosed a 5×9×10 mm lesion in the left superior orbital fissure/cavernous sinus. After administration of methylprednisolone and prednisone, the patient’s pain completely resolved, and the left eye regained full duction and eyelid mobility. The MRI and MRA obtained after the treatment showed no abnormalities. Conclusion The rarity of THS makes it difficult to diagnose, especially when there is a question of accuracy and reproducibility of the testing performed. An ophthalmologic consultation in such cases is crucial. PMID:24741291

  20. Evaluation of maxillary arterial blood flow in anesthetized cats with the mouth closed and open.

    PubMed

    Barton-Lamb, A L; Martin-Flores, M; Scrivani, P V; Bezuidenhout, A J; Loew, E; Erb, H N; Ludders, J W

    2013-06-01

    The mouth-gag is a common tool used in veterinary medicine during oral and transoral procedures in cats but its use has recently been associated with the development of blindness. The goal of this study was to investigate whether maximal opening of the mouth affects maxillary artery blood flow in six anesthetized cats. To assess blood flow, the electroretinogram (ERG), brainstem auditory evoked response (BAER) and magnetic resonance angiography (MRA) were evaluated qualitatively with the mouth closed and open. During dynamic computer tomography (CT) examinations, detection of contrast medium in the maxillary artery was quantified by measuring the Hounsfield units (HUs). The peak HU, time to peak and mean HU were determined. Changes ⩾10% of these parameters were considered indicative of altered blood flow. ERG and BAER were normal with the mouth closed in all cats, but was abnormal with the mouth opened maximally in two cats and one cat, respectively. During MRA, blood flow was undetected in either maxillary artery in one cat and reduced in the right maxillary artery in two cats, when the mouth was open. During CT, the peak HU decreased ⩾10% in three cats, the time to peak was ⩾10% longer in two cats, and the mean HU was ⩾10% lower in one cat when the mouth was open. No cat developed apparent blindness or deafness. Maximal opening of the mouth caused alterations in several indicators of blood flow in some individual cats.

  1. Final report on EURAMET.T-K7.2: Bilateral comparison of water triple point cells

    NASA Astrophysics Data System (ADS)

    Peruzzi, A.; Szmyrka Grzebyk, A.

    2012-01-01

    This is the final report of EURAMET.T-K7.2 bilateral comparison of water triple point cells. This comparison was requested by the Institute of Low Temperature and Structure Research, INTiBS, in its role as designated institute of Poland for participation in the CIPM MRA in the low temperature range of the thermometry field. The measurement protocol adopted was compatible with EURAMET.T-K7 with the only exception that INTiBS used capsule-type SPRTs (CSPRTs) instead of long-stem SPRTs (LSPRTs). The results showed a satisfactory degree of equivalence between VSL and INTiBS and allowed linkage to the parent key comparison EURAMET.T-K7. As a consequence, INTiBS is able to support CMCs for CSPRTs at the triple point of water and publish them in the KCDB. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  2. A comparison between willingness to pay and willingness to give up time.

    PubMed

    van Helvoort-Postulart, Debby; Dirksen, Carmen D; Kessels, Alfons G H; van Engelshoven, Jos M A; Myriam Hunink, M G

    2009-02-01

    We compared the willingness-to-pay and willingness to give up time methods to assess preferences for digital subtraction angiography (DSA), computed tomography angiography (CTA) and magnetic resonance angiography (MRA). Respondents were hypertensive patients suspected of having renal artery stenosis. Data were gathered using telephone interviews. Both the willingness-to-pay and willingness to give up time methods revealed that patients preferred CTA to MRA in order to avoid DSA. The agreement between willingness-to-pay and willingness to give up time responses was high (kappa 0.65-0.85). The willingness-to-pay method yielded relatively more protest answers (12%) as compared to willingness to give up time (2%). So, our results provided evidence for the comparability of willingness to pay and willingness to give up time. The high percentage of protest answers on the willingness-to-pay questions raises questions with respect to the application of the willingness-to-pay method in a broad decision-making context. On the other hand, the strength of willingness-to-pay is that the method directly arrives at a monetary measure well founded in economic theory, whereas the willingness to give up time method requires conversion to monetary units. PMID:18437436

  3. Vasodilatation of multiple cerebral arteries in early stage of stroke-like episode with MELAS.

    PubMed

    Minobe, Shoko; Matsuda, Akiko; Mitsuhashi, Tetsuya; Ishikawa, Motonao; Nishimura, Yoshiko; Shibata, Koichi; Ito, Eiichi; Goto, Yu-ichi; Nakaoka, Takashi; Sakura, Hiroshi

    2015-02-01

    We describe a patient with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS), with multiple cerebral vasodilatations in a stroke-like episode visualised by using magnetic resonance angiography (MRA) and CT angiography (CTA). In the acute stroke-like episode stage, T2-weighted and fluid-attenuated inversion recovery MRI showed high-intensity areas in the left occipital area. In addition, MRA and CTA revealed prominent dilatation of the left posterior cerebral artery and temporal branches of the middle cerebral artery with focal hyperperfusions using CT perfusion (CTP) that corresponded to the MRI. After 10 days, with the development of aphasia, MRI indicated the lesions had spread to the temporal and parietal regions, and this distribution was not confined to major vascular territories. The patient's symptoms gradually improved, accompanied by the attenuation of MRI, CTA, and CTP findings. These characteristic features along with the MRI changes that spread beyond vascular boundaries and the multiple cerebral vasodilatations prior to the development of clinical symptoms are not fully explained by the mitochondrial angiopathy or cytopathy theories. These findings provide further evidence supporting neuronal hyperexcitability in stroke-like episodes of MELAS.

  4. A Practical Algorithm for Improving Localization and Quantification of Left Ventricular Scar

    PubMed Central

    Zenger, Brian; Cates, Joshua; Morris, Alan; Kholmovski, Eugene; Au, Alexander; Ranjan, Ravi; Akoum, Nazem; McGann, Chris; Wilson, Brent; Marrouche, Nassir; Han, Frederick T.; MacLeod, Rob S.

    2015-01-01

    Current approaches to classification of left ventricular scar rely on manual segmentation of myocardial borders and manual classification of scar tissue. In this paper, we propose an novel, semi-automatic approach to segment the left ventricular wall and classify scar tissue using a combination of modern image processing techniques. We obtained high-resolution magnetic resonance angiograms (MRA) and late-gadolinium enhanced magnetic resonance imaging (LGE-MRI) in 14 patients who had ventricular scar from a prior myocardial infarction. We applied (1) a level set-based segmentation approach using a combination of the MRA and LGE-MRI to segment the myocardium and then (2) an automated signal intensity algorithm (Otsu thresholding) to identify ventricular scar tissue. We compared results from both steps to those of expert observers. The LVgeometry using the semi-automated segmentation method had a mean overlap of 94% with the manual segmentations. The scar volumes obtained with the Otsu method correlated with the expert observer scar volumes (Dice comparison coefficient of 0.85± 0.11). This proof of concept segmentation pipeline provides a more objective method for identifying scar in the left ventricle than manual approaches. PMID:26448961

  5. Effective use of flow-spoiled FBI and time-SLIP methods in the diagnostic study of an aberrant vessel of the head and neck: "left jugular venous steal by the right jugular vein".

    PubMed

    Kogure, Taroh; Kogure, Kyuya; Iizuka, Mitsumasa; Ino, Azusa; Ishii, Masako

    2010-08-01

    Three-dimensional (3D) time-of-flight (TOF) is now commonly used in routine magnetic resonance angiography (MRA) studies of the head and neck. However, there are limits to its diagnostic abilities in the clinical field and, in some instances, a more invasive supplementary examination may be required. We incidentally discovered a patient with an aberrant vessel of the head and neck that ran alongside the left carotid artery and contained a constant, slowly pulsating efferent blood flow. 3D-TOF and carotid ultrasonography could not determine the nature and origin of this vessel. Additional studies using flow-spoiled fresh blood imaging (flow-spoiled FBI) and time spatial labeling inversion pulse (time-SLIP) methods were effective in determining that the vessel was the left jugular vein, and that the continuous venous reflux was a result of a venous steal by the right jugular vein. We show that by combining different MRA techniques we can effectively achieve diagnosis without resorting to more invasive examinations.

  6. Region based feature extraction from non-cooperative iris images using triplet half-band filter bank

    NASA Astrophysics Data System (ADS)

    Barpanda, Soubhagya Sankar; Majhi, Banshidhar; Sa, Pankaj Kumar

    2015-09-01

    In this paper, we have proposed energy based features using a multi-resolution analysis (MRA) on iris template. The MRA is based on our suggested triplet half-band filter bank (THFB). The THFB derivation process is discussed in detail. The iris template is divided into six equispaced sub-templates and two level decomposition has been made to each sub-template using THFB except second one. The reason for discarding the second template is due to the fact that it mostly contains the noise due to eyelids, eyelashes, and occlusion due to segmentation failure. Subsequently, energy features are derived from the decomposed coefficients of each sub-template. The proposed feature has been experimented on standard databases like CASIAv3, UBIRISv1, and IITD and mostly on iris images which encounter a segmentation failure. Comparative analysis has been done with existing features based on Gabor transform, Fourier transform, and CDF 9/7 filter bank. The proposed scheme shows superior performance with respect to FAR, GAR and AUC.

  7. Statistical methods for analysis of coordination of chest wall motion using optical reflectance imaging of multiple markers

    NASA Astrophysics Data System (ADS)

    Kenyon, C. M.; Ghezzo, R. H.; Cala, S. J.; Ferrigno, Giancarlo; Pedotti, Antonio; Macklem, P. T.; Rochester, D. F.

    1994-07-01

    To analyze coordination of chest wall motion we have used principle component analysis (PCA) and multiple regression analysis (MRA) with respect to spirometry on the displacements of 93 optical reflective markers placed upon the chest wall (CW). Each marker is tracked at 10 Hz with an accuracy of 0.2 mm in each spatial dimension using the ELITE system (IEEE Trans. Biomed. Eng. 11:943-949, 1985). PCA enables the degree of linear coordination between all of the markers to be assessed using the eigenvectors and eigenvalues of the covariance of the matrix of marker displacements in each dimension against time. Thus the number of linear degrees of freedom (DOF) which contribute more than a particular amount to the total variance can be determined and analyzed. MRA with respect to spirometrically measured lung volume changes enables identification of the CW points whose movement correlates best with lung volume. We have used this analysis to compare a quiet breathing sequence with one where tidal volume was increased fourfold involuntarily and show that the number of DOF with eigenvalues accounting for >5% of the covariance increased from 2 to 3. Also the point whose movement correlated best with lung volume changed from halfway down the lower costal margin to a more lateral point at the level of the bottom of the sternum. This quantification of CW coordination may be useful in analysis and staging of many respiratory disorders and is applicable to any nonrigid body motion where points can be tracked.

  8. Eplerenone: a review of its use in patients with chronic systolic heart failure and mild symptoms.

    PubMed

    Dhillon, Sohita

    2013-09-01

    Eplerenone (Inspra®) is a selective mineralocorticoid receptor antagonist (MRA). In the EU, it is approved for use (in addition to standard optimal therapy) to reduce the risk of cardiovascular (CV) mortality and morbidity in adult patients with chronic systolic heart failure (HF) and mild symptoms. This article reviews the efficacy and tolerability of eplerenone in this indication and briefly summarizes its pharmacology. In the EMPHASIS-HF study, relative to placebo, the addition of eplerenone to optimal background therapy significantly reduced the risk of death from CV causes or hospitalization for HF in patients with chronic systolic HF and mild symptoms. Benefits of eplerenone therapy over placebo were also observed in several secondary outcomes, including: death from any cause or hospitalization for HF; death from any cause; hospitalization for any reason; or hospitalization for HF. Eplerenone was generally well tolerated in this study, with the most frequent adverse event being hyperkalaemia, which is a known adverse event of the drug class. Sexual adverse events (e.g. gynecomastia) occurred in <1 % of eplerenone recipients, reflecting the selectivity of eplerenone for mineralocorticoid receptors. Based on these results, European guidelines have been updated and recommend the use of an MRA to reduce the risk of HF hospitalization and premature death in all patients with persisting symptoms (New York Heart Association class II-IV) and a left-ventricular ejection fraction of ≤35 %, despite treatment with ACE inhibitor (or an angiotensin receptor blocker if an ACE inhibitor is not tolerated) and a β-blocker.

  9. 2010 Manufacturing Readiness Assessment Update to the 2008 Report for Fuel Cell Stacks and Systems for the Backup Power and Materials Handling Equipment Markets

    SciTech Connect

    Wheeler, D.; Ulsh, M.

    2012-08-01

    In 2008, the National Renewable Energy Laboratory (NREL), under contract to the US Department of Energy (DOE), conducted a manufacturing readiness assessment (MRA) of fuel cell systems and fuel cell stacks for back-up power and material handling applications (MHE). To facilitate the MRA, manufacturing readiness levels (MRL) were defined that were based on the Technology Readiness Levels previously established by the US Department of Energy (DOE). NREL assessed the extensive existing hierarchy of MRLs developed by Department of Defense (DoD) and other Federal entities, and developed a MRL scale adapted to the needs of the Fuel Cell Technologies Program (FCTP) and to the status of the fuel cell industry. The MRL ranking of a fuel cell manufacturing facility increases as the manufacturing capability transitions from laboratory prototype development through Low Rate Initial Production to Full Rate Production. DOE can use MRLs to address the economic and institutional risks associated with a ramp-up in polymer electrolyte membrane (PEM) fuel cell production. In 2010, NREL updated this assessment, including additional manufacturers, an assessment of market developments since the original report, and a comparison of MRLs between 2008 and 2010.

  10. Advanced level set segmentation of the right atrium in MR

    NASA Astrophysics Data System (ADS)

    Chen, Siqi; Kohlberger, Timo; Kirchberg, Klaus J.

    2011-03-01

    Atrial fibrillation is a common heart arrhythmia, and can be effectively treated with ablation. Ablation planning requires 3D models of the patient's left atrium (LA) and/or right atrium (RA), therefore an automatic segmentation procedure to retrieve these models is desirable. In this study, we investigate the use of advanced level set segmentation approaches to automatically segment RA in magnetic resonance angiographic (MRA) volume images. Low contrast to noise ratio makes the boundary between the RA and the nearby structures nearly indistinguishable. Therefore, pure data driven segmentation approaches such as watershed and ChanVese methods are bound to fail. Incorporating training shapes through PCA modeling to constrain the segmentation is one popular solution, and is also used in our segmentation framework. The shape parameters from PCA are optimized with a global histogram based energy model. However, since the shape parameters span a much smaller space, it can not capture fine details of the shape. Therefore, we employ a second refinement step after the shape based segmentation stage, which follows closely the recent work of localized appearance model based techniques. The local appearance model is established through a robust point tracking mechanism and is learned through landmarks embedded on the surface of training shapes. The key contribution of our work is the combination of a statistical shape prior and a localized appearance prior for level set segmentation of the right atrium from MRA. We test this two step segmentation framework on porcine RA to verify the algorithm.

  11. Image-based modeling of the hemodynamics in cerebral arterial trees

    NASA Astrophysics Data System (ADS)

    Mut, Fernando; Wright, Susan; Putman, Christopher; Ascoli, Giorgio; Cebral, Juan

    2009-02-01

    Knowledge of the hemodynamics in normal arterial trees of the brain is important to better understand the mechanisms responsible for the initiation and progression of cerebrovascular diseases. Information about the baseline values of hemodynamic variables such as velocity magnitudes, swirling flows, wall shear stress, pressure drops, vascular resistances, etc. is important for characterization of the normal hemodynamics and comparison with pathological states such as aneurysms and stenoses. This paper presents image-based computational hemodynamics models of cerebral arterial trees constructed from magnetic resonance angiography (MRA) images. The construction of large models of cerebral arterial trees is challenging because of the following main reasons: a) it is necessary to acquire high resolution angiographic images covering the entire brain, b) it is necessary to construct topologically correct and geometrically accurate watertight models of the vasculature, and c) the models typically result in large computational grids which make the calculations computationally demanding. This paper presents a methodology to model the hemodynamics in the brain arterial network that combines high resolution MRA at 3T, a vector representation of the vascular structures based on semi-manual segmentation, and a novel algorithm to solve the incompressible flow equations efficiently in tubular geometries. These techniques make the study of the hemodynamics in the cerebral arterial network practical.

  12. Internal jugular vein valve incompetence and intracranial venous anatomy in transient global amnesia

    PubMed Central

    Schreiber, S; Doepp, F; Klingebiel, R; Valdueza, J

    2005-01-01

    Background: Recently a causal relation between internal jugular vein valve incompetence (IJVVI) and transient global amnesia (TGA) has been suggested. IJVVI is postulated to provoke a transient mesiotemporal ischaemia by venous congestion. This mechanism requires a patent venous pathway from the affected IJV through the transverse sinus, confluens, straight sinus (SS), vein of Galen into the basal vein of Rosenthal and the internal cerebral veins. Objective: To study IJVVI in TGA patients in relation to the intracranial venous anatomy. Methods: IJVVI was defined if a repeated Valsalva manoeuvre (VM) led to a retrograde jugular flow detected by extracranial duplex ultrasound. Non-contrast venous MR angiography (MRA) was performed to analyse intracranial drainage patterns of the SS in relation to the side of the IJVVI. SS drainage was differentiated into three groups: predominantly right, left, and bilateral drainage. Ultrasound studies were performed in 25 TGA patients and 85 age matched controls. Twenty patients underwent venous MRA. Results: Sixty eight per cent of patients and 33% of controls showed unilateral or bilateral IJVVI (p = 0.0025). In 36% of patients a TGA preceding VM was reported. Drainage pattern of SS and side of IJVVI corresponded in five of eight patients (63%) with VM and four of 12 patients without VM (33%, p = 0.0994). Conclusion: Our study confirms the significantly higher prevalence of IJVVI in TGA patients. However, no specific IJVVI related intracranial venous drainage patterns could be found to further support the hypothesis of a direct causal relation between IJVVI and TGA. PMID:15774436

  13. Morphological Characteristics of the Vertebrobasilar Arterial System Are Associated with Vertebrobasilar Dolichoectasia

    PubMed Central

    Wu, Xi; Li, Yanjun; Huang, Qinghai; Liu, Jianmin

    2016-01-01

    Background Vertebrobasilar dolichoectasia (VBD) is characterized by abnormal dilation, distortion, and extension of the vertebral artery (VA) and basilar artery (BA). This study investigated whether BA and VA morphological characteristics were factors predicting VBD. Material/Methods Individuals aged ≥18 years undergoing contrast-enhanced magnetic resonance angiography (CE-MRA) of the head/neck were enrolled in 2012 at Changhai Hospital, Shanghai. Data concerning cardiovascular risk factors were recorded. Bilateral VA diameter and lateral displacement, BA diameter and lateral displacement, VA confluence displacement, and dominant VA (DVA) presence/absence were determined from CE-MRA. VBD was diagnosed using established criteria. DVA and no-DVA groups were compared. Logistic regression analysis was used to identify variables independently associated with VBD. Results Our study included 1153 individuals, of which 614 (53.3%) had DVA. The DVA group had higher mean age, hypertension prevalence (44.6% vs. 37.5%), and VBD prevalence (8.1% vs. 4.5%), and lower smoking prevalence (24.3% vs. 30.6%), than no-DVA patients. Univariate analysis revealed that age, female sex, hypertension, hyperlipidemia, smoking, alcohol consumption, and DVA presence were associated with VBD occurrence. Multivariate analysis showed that age and presence of a DVA were independently associated with VBD. Conclusions Age and presence of DVA are independently associated with VBD. PMID:27206494

  14. Determination of boiling point of petrochemicals by gas chromatography-mass spectrometry and multivariate regression analysis of structural activity relationship.

    PubMed

    Fakayode, Sayo O; Mitchell, Breanna S; Pollard, David A

    2014-08-01

    Accurate understanding of analyte boiling points (BP) is of critical importance in gas chromatographic (GC) separation and crude oil refinery operation in petrochemical industries. This study reported the first combined use of GC separation and partial-least-square (PLS1) multivariate regression analysis of petrochemical structural activity relationship (SAR) for accurate BP determination of two commercially available (D3710 and MA VHP) calibration gas mix samples. The results of the BP determination using PLS1 multivariate regression were further compared with the results of traditional simulated distillation method of BP determination. The developed PLS1 regression was able to correctly predict analytes BP in D3710 and MA VHP calibration gas mix samples, with a root-mean-square-%-relative-error (RMS%RE) of 6.4%, and 10.8% respectively. In contrast, the overall RMS%RE of 32.9% and 40.4%, respectively obtained for BP determination in D3710 and MA VHP using a traditional simulated distillation method were approximately four times larger than the corresponding RMS%RE of BP prediction using MRA, demonstrating the better predictive ability of MRA. The reported method is rapid, robust, and promising, and can be potentially used routinely for fast analysis, pattern recognition, and analyte BP determination in petrochemical industries.

  15. Cationic gadolinium chelate for magnetic resonance imaging of cartilaginous defects.

    PubMed

    Nwe, Kido; Huang, Ching-Hui; Qu, Feini; Warden-Rothman, Robert; Zhang, Clare Y; Mauck, Robert L; Tsourkas, Andrew

    2016-05-01

    The ability to detect meniscus defects by magnetic resonance arthrography (MRA) can be highly variable. To improve the delineation of fine tears, we synthesized a cationic gadolinium complex, (Gd-DOTA-AM4 )(2+) , that can electrostatically interact with Glycosaminoglycans (GAGs). The complex has a longitudinal relaxivity (r1) of 4.2 mM(-1) s(-1) and is highly stable in serum. Its efficacy in highlighting soft tissue tears was evaluated in comparison to a clinically employed contrast agent (Magnevist) using explants obtained from adult bovine menisci. In all cases, Gd-DOTA-AM4 appeared to improve the ability to detect the soft tissue defect by providing increased signal intensity along the length of the tear. Magnevist shows a strong signal near the liquid-meniscus interface, but much less contrast is observed within the defect at greater depths. This provides initial evidence that cationic contrast agents can be used to improve the diagnostic accuracy of MRA. Copyright © 2016 John Wiley & Sons, Ltd.

  16. Final report on APMP.T-K7 key comparison of water triple point cells

    NASA Astrophysics Data System (ADS)

    Tsai, S. F.; White, R.; Tamba, J.; Yamazawa, K.; Ho, M. K.; Tsui, C. M.; Zaid, G.; Achmadi, A.; Gam, K. S.; Othman, H.; Ali, N. M.; Yuan, K. H.; Shaochun, Y.; Liedberg, H.; Yaokulbodee, C.

    2016-01-01

    APMP.T-K7, was held from February 2008 to September 2009 to compare the national realizations of the water triple point among eleven NMIs. To reach the objective, each participating laboratory sent a transfer cell to CMS and stated a value for the temperature difference of the transfer cell, relative to the corresponding national standard, representing 273.16 K. CMS (Taiwan) organized the comparison, with the support from co-pilot institutes MSL (New Zealand) and NMIJ (Japan). The other eight participating laboratories included NMIA, SCL, KIM-LIPI, KRISS, NMIM/SIRIM, NMC, NMISA, and NIMT. This report presents the results of the TPW comparison, gives detailed information about the measurements made at the CMS and at the participating laboratories, and aims to link the results of APMP.T-K7 to CCT-K7. The results of this key comparison are also represented in the form of degrees of equivalence for the purposes of the MRA. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  17. Long-term Follow-up Study of Endovascularly Treated Intracranial Aneurysms

    PubMed Central

    Pyysalo, L.M.; Keski-Nisula, L.H.; Niskakangas, T.T.; Kähärä, V.J.; Öhman, J.E.

    2010-01-01

    Summary Long-term follow-up studies after endovascular treatment for intracranial aneurysm are still rare and inconclusive. The aim of this study was to assess long-term clinical and angiographic outcome of patients with endovascularly treated aneurysms. The Clinical outcome of all 185 patients with endovascularly treated aneurysms were analyzed and 77 out of 122 surviving patients were examined with MRI and MRA nine to 16 years (mean 11 years) after the initial endovascular treatment. Sixty-three patients were deceased at the time of follow-up. The cause of death was aneurysm- related in 34 (54%) patients. The annual re- bleeding rate from the treated aneurysms was 1.3% in the ruptured group and 0.1% in the unruptured group. In long-term follow-up MRA 18 aneurysms (53%) were graded as complete, 11 aneurysms (32%) had neck remnants and five aneurysms (15%) were incompletely occluded in the ruptured group. Occlusion grade was lower in the unruptured group with 20 an- eurysms (41%) graded as complete, 11 (22%) had neck remnants and 18 (37%) were incomplete. However, only three aneurysms were unstable during the follow-up period and needed retreatment. Endovascular treatment of unruptured aneu- rysms showed incomplete angiographic outcome in 37% of cases. However, annual bleeding rate was as low as 0.1%. Endovascular treatment of ruptured aneurysms showed incomplete angiographic outcome in 15% of cases and the annual rebleeding rate was 1.3%. PMID:21162766

  18. Long-Term Follow-Up Study of Endovascularly Treated Intracranial Aneurysms

    PubMed Central

    Pyysalo, L.M.; Keski-Nisula, L.H.; Niskakangas, T.T.; Kähärä, V.J.; Öhman, J.E.

    2010-01-01

    Summary Long-term follow-up studies after endovascular treatment for intracranial aneurysm are still rare and inconclusive. The aim of this study was to assess the long-term clinical and angiographic outcome of patients with endovascularly treated aneurysms. The clinical outcome of all 185 patients with endovascularly treated aneurysms were analyzed and 77 out of 122 surviving patients were examined with MRI and MRA nine to 16 years (mean 11 years) after the initial endovascular treatment. Sixty-three patients were deceased at the time of follow-up. The cause of death was aneurysm-related in 34 (54ċ) patients. The annual rebleeding rate from the treated aneurysms was 1.3% in the ruptured group and 0.1% in the unruptured group. In long-term follow-up MRA 18 aneurysms (53%) were graded as complete, 11 aneurysms (32%) had neck remnants and five aneurysms (15%) were incompletely occluded in the ruptured group. The occlusion grade was lower in the unruptured group with 20 aneurysms (41%) graded as complete, 11 (22%) had neck remnants and 18 (37%) were incomplete. However, only three aneurysms were unstable during the follow-up period and needed retreatment. Endovascular treatment of unruptured aneurysms showed incomplete angiographic outcome in 37% of cases. However, the annual bleeding rate was as low as 0.1%. Endovascular treatment of ruptured aneurysms showed incomplete angiographic outcome in 15% of cases and the annual rebleeding rate was 1,3%. PMID:20977853

  19. Quantifying errors in flow measurement using phase contrast magnetic resonance imaging: comparison of several boundary detection methods.

    PubMed

    Jiang, Jing; Kokeny, Paul; Ying, Wang; Magnano, Chris; Zivadinov, Robert; Mark Haacke, E

    2015-02-01

    Quantifying flow from phase-contrast MRI (PC-MRI) data requires that the vessels of interest be segmented. The estimate of the vessel area will dictate the type and magnitude of the error sources that affect the flow measurement. These sources of errors are well understood, and mathematical expressions have been derived for them in previous work. However, these expressions contain many parameters that render them difficult to use for making practical error estimates. In this work, some realistic assumptions were made that allow for the simplification of such expressions in order to make them more useful. These simplified expressions were then used to numerically simulate the effect of segmentation accuracy and provide some criteria that if met, would keep errors in flow quantification below 10% or 5%. Four different segmentation methods were used on simulated and phantom MRA data to verify the theoretical results. Numerical simulations showed that including partial volumed edge pixels in vessel segmentation provides less error than missing them. This was verified with MRA simulations, as the best performing segmentation method generally included such pixels. Further, it was found that to obtain a flow error of less than 10% (5%), the vessel should be at least 4 (5) pixels in diameter, have an SNR of at least 10:1 and have a peak velocity to saturation cut-off velocity ratio of at least 5:3.

  20. Long-term forecasting of internet backbone traffic.

    PubMed

    Papagiannaki, Konstantina; Taft, Nina; Zhang, Zhi-Li; Diot, Christophe

    2005-09-01

    We introduce a methodology to predict when and where link additions/upgrades have to take place in an Internet protocol (IP) backbone network. Using simple network management protocol (SNMP) statistics, collected continuously since 1999, we compute aggregate demand between any two adjacent points of presence (PoPs) and look at its evolution at time scales larger than 1 h. We show that IP backbone traffic exhibits visible long term trends, strong periodicities, and variability at multiple time scales. Our methodology relies on the wavelet multiresolution analysis (MRA) and linear time series models. Using wavelet MRA, we smooth the collected measurements until we identify the overall long-term trend. The fluctuations around the obtained trend are further analyzed at multiple time scales. We show that the largest amount of variability in the original signal is due to its fluctuations at the 12-h time scale. We model inter-PoP aggregate demand as a multiple linear regression model, consisting of the two identified components. We show that this model accounts for 98% of the total energy in the original signal, while explaining 90% of its variance. Weekly approximations of those components can be accurately modeled with low-order autoregressive integrated moving average (ARIMA) models. We show that forecasting the long term trend and the fluctuations of the traffic at the 12-h time scale yields accurate estimates for at least 6 months in the future.

  1. Successful serial imaging of the mouse cerebral arteries using conventional 3-T magnetic resonance imaging

    PubMed Central

    Makino, Hiroshi; Hokamura, Kazuya; Natsume, Takahiro; Kimura, Tetsuro; Kamio, Yoshinobu; Magata, Yasuhiro; Namba, Hiroki; Katoh, Takasumi; Sato, Shigehito; Hashimoto, Tomoki; Umemura, Kazuo

    2015-01-01

    Serial imaging studies can be useful in characterizing the pathologic and physiologic remodeling of cerebral arteries in various mouse models. We tested the feasibility of using a readily available, conventional 3-T magnetic resonance imaging (MRI) to serially image cerebrovascular remodeling in mice. We utilized a mouse model of intracranial aneurysm as a mouse model of the dynamic, pathologic remodeling of cerebral arteries. Aneurysms were induced by hypertension and a single elastase injection into the cerebrospinal fluid. For the mouse cerebrovascular imaging, we used a conventional 3-T MRI system and a 40-mm saddle coil. We used non-enhanced magnetic resonance angiography (MRA) to detect intracranial aneurysm formation and T2-weighted imaging to detect aneurysmal subarachnoid hemorrhage. A serial MRI was conducted every 2 to 3 days. MRI detection of aneurysm formation and subarachnoid hemorrhage was compared against the postmortem inspection of the brain that was perfused with dye. The imaging times for the MRA and T2-weighted imaging were 3.7±0.5 minutes and 4.8±0.0 minutes, respectively. All aneurysms and subarachnoid hemorrhages were correctly identified by two masked observers on MRI. This MRI-based serial imaging technique was useful in detecting intracranial aneurysm formation and subarachnoid hemorrhage in mice. PMID:25920958

  2. Evaluation of the physicochemical properties of fine globular granules prepared by a multi-functional rotor processor.

    PubMed

    Kimura, Shin-ichiro; Iwao, Yasunori; Ishida, Masayuki; Noguchi, Shuji; Itai, Shigeru; Uchida, Shinya; Yamada, Masaki; Namiki, Noriyuki

    2014-01-01

    Multiple regression analysis (MRA) and principal component analysis (PCA) have been used in the present study to examine the relationships between the operational conditions of a unique multi-functional rotor processor, material attributes such as water content during granulation, and a series of associated micromeritics, including the flowability, granule mean size and granule density values. A variety of different operational conditions were tested, including the binder flow rate, atomization pressure, slit air flow rate, rotating speed and temperature of the inlet air. The results of MRA revealed several trends, including (1) the granule mean size was negatively affected by the atomization pressure, and positively affected by the binder flow rate; (2) the granule flow property, Carr's index was positively affected by the atomization pressure, and negatively affected by the slit air flow rate; and (3) the granule density was positively affected by the rotating speed. Taken together, these results suggested that the binder flow rate, atomization pressure and slit airflow rate were critical process parameters for the preparation of fine globular granules. Using PCA, it was possible to examine each relationship of all 19 batches and 10 variables, as well as determine which process parameters or material attributes impacted on the quality of the final product. The PCA results revealed that the roundness was positively correlated with the water content. Therefore, we believe this fundamental information will be important for the development of processes for the facile manufacture of fine globular granules.

  3. Color attributes and oxidative stability of longissimus lumborum and psoas major muscles from Nellore bulls.

    PubMed

    Canto, Anna C V C S; Costa-Lima, Bruno R C; Suman, Surendranath P; Monteiro, Maria Lucia G; Viana, Fernanda M; Salim, Ana Paula A A; Nair, Mahesh N; Silva, Teofilo J P; Conte-Junior, Carlos A

    2016-11-01

    The influence of muscle source on color stability of fresh beef from purebred Bos indicus cattle was investigated. Longissimus lumborum (LL) and psoas major (PM) muscles obtained from twelve (n=12) Nellore bull carcasses (24h post-mortem) were fabricated into 2.54-cm steaks, aerobically packaged, and stored at 4°C for nine days. Steaks were analyzed on day 0 for proximate composition and myoglobin concentration, whereas pH, instrumental color, metmyoglobin reducing activity (MRA), lipid oxidation, and protein oxidation were evaluated on days 0, 3, 6, and 9. LL steaks exhibited greater (P<0.05) redness, color stability, and MRA than PM counterparts. On the other hand, PM steaks demonstrated greater (P<0.05) myoglobin content, lipid oxidation, and protein oxidation than LL steaks. These results indicated the critical influence of muscle source on discoloration of fresh beef from Bos indicus animals and suggested the necessity to engineer muscle-specific strategies to improve color stability and marketability of beef from Bos indicus cattle.

  4. Automatic algorithm for correcting motion artifacts in time-resolved two-dimensional magnetic resonance angiography using convex projections.

    PubMed

    Raj, Ashish; Zhang, Honglei; Prince, Martin R; Wang, Yi; Zabih, Ramin

    2006-03-01

    Time-resolved contrast enhanced magnetic resonance angiography (MRA) may suffer from involuntary patient motion. It is noted that while MR signal change associated with motion is large in magnitude and has smooth phase variation in k-phase, signal change associated with vascular enhancement is small in magnitude and has rapid phase variation in k-space. Based upon this observation, a novel projection onto convex sets (POCS) algorithm is developed as an automatic iterative method to remove motion artifacts. The presented POCS algorithm consists of high-pass phase filtering and convex projections in both k-space and image space. Without input of detailed motion knowledge, motion effects are filtered out, while vasculature information is preserved. The proposed method can be effective for a large class of nonrigid motions, including through-plane motion. The algorithm is stable and converges quickly, usually within five iterations. A double-blind evaluation on a set of clinical MRA cases shows that a completely unsupervised version of the algorithm produces significantly better rank scores (P=0.038) when compared to angiograms produced manually by an experienced radiologist.

  5. Multiresolution analysis over graphs for a motor imagery based online BCI game.

    PubMed

    Asensio-Cubero, Javier; Gan, John Q; Palaniappan, Ramaswamy

    2016-01-01

    Multiresolution analysis (MRA) over graph representation of EEG data has proved to be a promising method for offline brain-computer interfacing (BCI) data analysis. For the first time we aim to prove the feasibility of the graph lifting transform in an online BCI system. Instead of developing a pointer device or a wheel-chair controller as test bed for human-machine interaction, we have designed and developed an engaging game which can be controlled by means of imaginary limb movements. Some modifications to the existing MRA analysis over graphs for BCI have also been proposed, such as the use of common spatial patterns for feature extraction at the different levels of decomposition, and sequential floating forward search as a best basis selection technique. In the online game experiment we obtained for three classes an average classification rate of 63.0% for fourteen naive subjects. The application of a best basis selection method helps significantly decrease the computing resources needed. The present study allows us to further understand and assess the benefits of the use of tailored wavelet analysis for processing motor imagery data and contributes to the further development of BCI for gaming purposes.

  6. Determination of boiling point of petrochemicals by gas chromatography-mass spectrometry and multivariate regression analysis of structural activity relationship.

    PubMed

    Fakayode, Sayo O; Mitchell, Breanna S; Pollard, David A

    2014-08-01

    Accurate understanding of analyte boiling points (BP) is of critical importance in gas chromatographic (GC) separation and crude oil refinery operation in petrochemical industries. This study reported the first combined use of GC separation and partial-least-square (PLS1) multivariate regression analysis of petrochemical structural activity relationship (SAR) for accurate BP determination of two commercially available (D3710 and MA VHP) calibration gas mix samples. The results of the BP determination using PLS1 multivariate regression were further compared with the results of traditional simulated distillation method of BP determination. The developed PLS1 regression was able to correctly predict analytes BP in D3710 and MA VHP calibration gas mix samples, with a root-mean-square-%-relative-error (RMS%RE) of 6.4%, and 10.8% respectively. In contrast, the overall RMS%RE of 32.9% and 40.4%, respectively obtained for BP determination in D3710 and MA VHP using a traditional simulated distillation method were approximately four times larger than the corresponding RMS%RE of BP prediction using MRA, demonstrating the better predictive ability of MRA. The reported method is rapid, robust, and promising, and can be potentially used routinely for fast analysis, pattern recognition, and analyte BP determination in petrochemical industries. PMID:24881546

  7. Multivariate and multiscale monitoring of wastewater treatment operation.

    PubMed

    Rosen, C; Lennox, J A

    2001-10-01

    In this work extensions to principal component analysis (PCA) for wastewater treatment (WWT) process monitoring are discussed. Conventional PCA has some limitations when used for WWT monitoring. Firstly, PCA assumes that data are stationary, which is normally not the case in WWT monitoring. Secondly, PCA is most suitable for monitoring data that display events in one time-scale. However, in WWT operation. disturbances and events occur in different time-scales. These two limitations make conventional PCA unsuitable for WWT monitoring. The first limitation can be overcome by use of adaptive PCA. In adaptive PCA. the PCA model is continuously updated using an exponential memory function. Variable mean, variance and co-variance are thus adapted to the changing conditions. The second problem can be solved by time-scale decomposition of data prior to analysis. The time-scale decomposition methodology involves wavelets and multiresolution analysis (MRA) in combination with PCA. MRA provides a tool for investigation and monitoring of process measurement at different time-scales by decomposing measurement data into separate frequency bands. Time-scale decomposition increases the sensitivity of the monitoring, which makes it possible to detect small but significant events in data displaying large variations. Moreover, time-scale information is sometimes important in the interpretation of a disturbance to determine its physical cause. Also, by decomposing data, the problem of changing process conditions is partly solved. All the presented methods are illustrated with examples using real WWT process data.

  8. Cationic gadolinium chelate for magnetic resonance imaging of cartilaginous defects.

    PubMed

    Nwe, Kido; Huang, Ching-Hui; Qu, Feini; Warden-Rothman, Robert; Zhang, Clare Y; Mauck, Robert L; Tsourkas, Andrew

    2016-05-01

    The ability to detect meniscus defects by magnetic resonance arthrography (MRA) can be highly variable. To improve the delineation of fine tears, we synthesized a cationic gadolinium complex, (Gd-DOTA-AM4 )(2+) , that can electrostatically interact with Glycosaminoglycans (GAGs). The complex has a longitudinal relaxivity (r1) of 4.2 mM(-1) s(-1) and is highly stable in serum. Its efficacy in highlighting soft tissue tears was evaluated in comparison to a clinically employed contrast agent (Magnevist) using explants obtained from adult bovine menisci. In all cases, Gd-DOTA-AM4 appeared to improve the ability to detect the soft tissue defect by providing increased signal intensity along the length of the tear. Magnevist shows a strong signal near the liquid-meniscus interface, but much less contrast is observed within the defect at greater depths. This provides initial evidence that cationic contrast agents can be used to improve the diagnostic accuracy of MRA. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26853708

  9. [Coil embolization for incidental aneurysms in patients with chronic renal failure: midterm clinical results of two cases].

    PubMed

    Nakashima, T; Katou, T; Murakawa, T; Yamakawa, H; Yoshimura, S; Kaku, Y; Sakai, N

    2000-06-01

    In spite of recent advances in perioperative management, the risk of neurosurgical intervention for patients with chronic renal failure is still considered too high. In this study, coil embolization for incidental aneurysms in such patients is demonstrated in reference to midterm results. A 42-year-old woman with a history of hemodialisis for 7 years presented with subcortical hemorrhage in her right frontal lobe. The magnetic resonance angiography (MRA) demonstrated a distal anterior cerebral artery aneurysm, but it was considered to be unrelated to the hemorrhage. Two and a half months after the hemorrhage the aneurysm was embolized with interlocking detachable coils. Thirty months after embolization, the angiogram revealed the coil compaction and the recanalization of the aneurysm neck. However, 54 months after embolization, the figure of the embolized aneurysm and neck remnant was the same as the previous findings. A 69-year-old woman with a history of hemodialisis for 5 years suddenly experienced left hemiparesis. Computed tomography revealed cerebral infarction in the right frontoparietal white matter. In addition, a left middle cerebral artery aneurysm was unexpectedly found on the MRA. Five months after the onset of the attack, the aneurysm was embolized with a Guglielmi detachable coli. An angiogram obtained 24 months after the embolization showed the aneurysm to be almost completely obliterated. In considering the therapeutic risks and benefits for incidental aneurysms of patients with chronic renal failure, intra-vascular surgery could be recommended as a less invasive treatment. PMID:10875114

  10. Computing molecular correlation energies with guaranteed precision

    NASA Astrophysics Data System (ADS)

    Bischoff, Florian A.; Valeev, Edward F.

    2013-09-01

    We present an approach to compute accurate correlation energies for atoms and molecules in the framework of multiresolution analysis (MRA), using an adaptive discontinuous multiresolution spectral-element representation for the six-dimensional (two-electron) pair function. The key features of our approach that make it feasible, namely (1) low-rank tensor approximations of functions and operators and (2) analytic elimination of operator singularities via explicit correlation, were retained from the previous work [F. A. Bischoff, R. J. Harrison, and E. F. Valeev, J. Chem. Phys. 137, 104103 (2012)]. Here we generalized the working equations to handle general (non-symmetric) many-electron systems at the MP2 level. The numerical performance is shown for the beryllium atom and the water molecule where literature data for the basis set limits could be reproduced to a few tens of μEh. The key advantages of molecular MRA-MP2 are the absence of bias and arbitrariness in the choice of the basis set, high accuracy, and low scaling with respect to the system size.

  11. Quantifying errors in flow measurement using phase contrast magnetic resonance imaging: comparison of several boundary detection methods.

    PubMed

    Jiang, Jing; Kokeny, Paul; Ying, Wang; Magnano, Chris; Zivadinov, Robert; Mark Haacke, E

    2015-02-01

    Quantifying flow from phase-contrast MRI (PC-MRI) data requires that the vessels of interest be segmented. The estimate of the vessel area will dictate the type and magnitude of the error sources that affect the flow measurement. These sources of errors are well understood, and mathematical expressions have been derived for them in previous work. However, these expressions contain many parameters that render them difficult to use for making practical error estimates. In this work, some realistic assumptions were made that allow for the simplification of such expressions in order to make them more useful. These simplified expressions were then used to numerically simulate the effect of segmentation accuracy and provide some criteria that if met, would keep errors in flow quantification below 10% or 5%. Four different segmentation methods were used on simulated and phantom MRA data to verify the theoretical results. Numerical simulations showed that including partial volumed edge pixels in vessel segmentation provides less error than missing them. This was verified with MRA simulations, as the best performing segmentation method generally included such pixels. Further, it was found that to obtain a flow error of less than 10% (5%), the vessel should be at least 4 (5) pixels in diameter, have an SNR of at least 10:1 and have a peak velocity to saturation cut-off velocity ratio of at least 5:3. PMID:25460329

  12. Vascular Tree Segmentation in Medical Images Using Hessian-Based Multiscale Filtering and Level Set Method

    PubMed Central

    Jin, Jiaoying; Yang, Linjun; Zhang, Xuming

    2013-01-01

    Vascular segmentation plays an important role in medical image analysis. A novel technique for the automatic extraction of vascular trees from 2D medical images is presented, which combines Hessian-based multiscale filtering and a modified level set method. In the proposed algorithm, the morphological top-hat transformation is firstly adopted to attenuate background. Then Hessian-based multiscale filtering is used to enhance vascular structures by combining Hessian matrix with Gaussian convolution to tune the filtering response to the specific scales. Because Gaussian convolution tends to blur vessel boundaries, which makes scale selection inaccurate, an improved level set method is finally proposed to extract vascular structures by introducing an external constrained term related to the standard deviation of Gaussian function into the traditional level set. Our approach was tested on synthetic images with vascular-like structures and 2D slices extracted from real 3D abdomen magnetic resonance angiography (MRA) images along the coronal plane. The segmentation rates for synthetic images are above 95%. The results for MRA images demonstrate that the proposed method can extract most of the vascular structures successfully and accurately in visualization. Therefore, the proposed method is effective for the vascular tree extraction in medical images. PMID:24348738

  13. Pulmonary Hemorrhage: Imaging with a New Magnetic Resonance Blood Pool Agent in Conjunction with Breathheld Three-Dimensional Magnetic Resonance Angiography

    SciTech Connect

    Weishaupt, Dominik; Hilfiker, Paul R.; Schmidt, Michaela; Debatin, Joerg F.

    1999-07-15

    Purpose: To describe the three-dimensional magnetic resonance angiography (3D MRA) imaging appearance of the pulmonary arteries following administration of a superparamagnetic iron oxide blood pool agent to human volunteers, and to demonstrate in an animal model (pigs) how this technique can be used to detect pulmonary parenchymal hemorrhage. Methods: Two volunteers were examined following the intravenous administration of a superparamagnetic iron oxide blood pool agent (NC100150 Injection, Nycomed Amersham Imaging, Wayne, PA, USA). T1-weighted 3D gradient recalled echo (GRE) image sets (TR/TE 5.1/1.4 msec, flip angle 30 deg.) were acquired breathheld over 24 sec. To assess the detectability of pulmonary bleeding with intravascular MR contrast, pulmonary parenchymal injuries were created in two animals under general anesthesia, and fast T1-weighted 3D GRE image sets collected before and after the injury. Results: Administration of the intravascular contrast in the two volunteers resulted in selective enhancement of the pulmonary vasculature permitting complete visualization and excellent delineation of central, segmental, and subsegmental arteries. Following iatrogenic injury in the two animals, pulmonary hemorrhage was readily detected on the 3D image sets. Conclusion: The data presented illustrate that ultrafast 3D GRE MR imaging in conjunction with an intravenously administered intravascular blood pool agent can be used to perform high-quality pulmonary MRA as well as to detect pulmonary hemorrhage.

  14. Morphological Characteristics of the Vertebrobasilar Arterial System Are Associated with Vertebrobasilar Dolichoectasia.

    PubMed

    Wu, Xi; Li, Yanjun; Huang, Qinghai; Liu, Jianmin

    2016-05-21

    BACKGROUND Vertebrobasilar dolichoectasia (VBD) is characterized by abnormal dilation, distortion, and extension of the vertebral artery (VA) and basilar artery (BA). This study investigated whether BA and VA morphological characteristics were factors predicting VBD. MATERIAL AND METHODS Individuals aged ≥18 years undergoing contrast-enhanced magnetic resonance angiography (CE-MRA) of the head/neck were enrolled in 2012 at Changhai Hospital, Shanghai. Data concerning cardiovascular risk factors were recorded. Bilateral VA diameter and lateral displacement, BA diameter and lateral displacement, VA confluence displacement, and dominant VA (DVA) presence/absence were determined from CE-MRA. VBD was diagnosed using established criteria. DVA and no-DVA groups were compared. Logistic regression analysis was used to identify variables independently associated with VBD. RESULTS Our study included 1153 individuals, of which 614 (53.3%) had DVA. The DVA group had higher mean age, hypertension prevalence (44.6% vs. 37.5%), and VBD prevalence (8.1% vs. 4.5%), and lower smoking prevalence (24.3% vs. 30.6%), than no-DVA patients. Univariate analysis revealed that age, female sex, hypertension, hyperlipidemia, smoking, alcohol consumption, and DVA presence were associated with VBD occurrence. Multivariate analysis showed that age and presence of a DVA were independently associated with VBD. CONCLUSIONS Age and presence of DVA are independently associated with VBD.

  15. HSCT Sector Combustor Evaluations for Demonstration Engine

    NASA Technical Reports Server (NTRS)

    Greenfield, Stuart; Heberling, Paul; Kastl, John; Matulaitis, John; Huff, Cynthia

    2004-01-01

    In LET Task 10, critical development issues of the HSCT lean-burn low emissions combustor were addressed with a range of engineering tools. Laser diagnostics and CFD analysis were applied to develop a clearer understanding of the fuel-air premixing process and premixed combustion. Subcomponent tests evaluated the emissions and operability performance of the fuel-air premixers. Sector combustor tests evaluated the performance of the integrated combustor system. A 3-cup sector was designed and procured for laser diagnostics studies at NASA Glenn. The results of these efforts supported the earlier selection of the Cyclone Swirler as the pilot stage premixer and the IMFH (Integrated Mixer Flame Holder) tube as the main stage premixer of the LPP combustor. In the combustor system preliminary design subtask, initial efforts to transform the sector combustor design into a practical subscale engine combustor met with significant challenges. Concerns about the durability of a stepped combustor dome and the need for a removable fuel injection system resulted in the invention and refinement of the MRA (Multistage Radial Axial) combustor system in 1994. The MRA combustor was selected for the HSR Phase II LPP subscale combustor testing in the CPC Program.

  16. Final report on RMO comparison SIM.EM-S10: High value resistance comparison with two-terminal cryogenic current comparators

    NASA Astrophysics Data System (ADS)

    Bierzychudek, Marcos E.; Elmquist, Randolph; Hernández, Felipe

    2014-01-01

    This work presents a supplementary comparison of high value resistance standards performed during 2012 and January 2013, following the guidelines presented in a document about measurement comparisons in the CIPM MRA. The purpose of this task was to compare the high resistance cryogenic current comparator scaling of the participating institutes: National Institute of Standards and Technology, USA (NIST), Centro Nacional de Metrología, Mexico (CENAM) and Instituto Nacional de Tecnología Industrial, Argentina (INTI), all of which are members of the Sistema Interamericano de Metrología (SIM) Regional Metrology Organization. All the measurements of this comparison were performed with two-terminal cryogenic current comparators (CCC). Degrees of equivalence of the participating institutes relative to the comparison reference values are given in the report for the measured resistance values. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by SIM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  17. Calibration of surface roughness standards

    NASA Astrophysics Data System (ADS)

    Thalmann, R.; Nicolet, A.; Meli, F.; Picotto, G. B.; Matus, M.; Carcedo, L.; Hemming, B.; Ganioglu, O.; De Chiffre, L.; Saraiva, F.; Bergstrand, S.; Zelenika, S.; Tonmueanwai, A.; Tsai, C.-L.; Shihua, W.; Kruger, O.; de Souza, M. M.; Salgado, J. A.; Ramotowski, Z.

    2016-01-01

    The key comparison EURAMET.L-K8.2013 on roughness was carried out in the framework of a EURAMET project starting in 2013 and ending in 2015. It involved the participation of 17 National Metrology Institutes from Europe, Asia, South America and Africa representing four regional metrology organisations. Five surface texture standards of different type were circulated and on each of the standards several roughness parameters according to the standard ISO 4287 had to be determined. 32 out of 395 individual results were not consistent with the reference value. After some corrective actions the number of inconsistent results could be reduced to 20, which correspond to about 5% of the total and can statistically be expected. In addition to the material standards, two softgauges were circulated, which allow to test the software of the instruments used in the comparison. The comparison results help to support the calibraton and measurement capabilities (CMCs) of the laboratories involved in the CIPM MRA. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCL, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  18. Quantifying Errors in Flow Measurement Using Phase Contrast Magnetic Resonance Imaging: Comparison of Several Boundary Detection Methods

    PubMed Central

    Jiang, Jing; Kokeny, Paul; Ying, Wang; Magnano, Chris; Zivadinov, Robert; Haacke, E. Mark

    2014-01-01

    Quantifying flow from phase-contrast MRI (PC-MRI) data requires that the vessels of interest be segmented. This estimate of the vessel area will dictate the type and magnitude of the error sources that affect the flow measurement. These sources of errors are well understood and mathematical expressions have been derived for them in previous work. However, these expressions contain many parameters that render them difficult to use for making practical error estimates. In this work, some realistic assumptions were made that allow for the simplification of such expressions in order to make them more useful. These simplified expressions were then used to numerically simulate the effect of segmentation accuracy and provide some criteria that if met, would keep errors in flow quantification below 10% or 5%. Four different segmentation methods were used on simulated and phantom MRA data to verify the theoretical results. Numerical simulations showed that including partial volumed edge pixels in vessel segmentation provides less error than missing them. This was verified with MRA simulations, as the best performing segmentation method generally included such pixels. Further, it was found that to obtain a flow error of less than 10% (5%), the vessel should be at least 4 (5) pixels in diameter, have an SNR of at least 10:1 and a peak velocity to saturation cut-off velocity ratio of at least 5:3. PMID:25460329

  19. Substantial Reduction of Parenchymal Cerebral Blood Flow in Mice with Bilateral Common Carotid Artery Stenosis

    PubMed Central

    Hattori, Yorito; Enmi, Jun-ichiro; Iguchi, Satoshi; Saito, Satoshi; Yamamoto, Yumi; Nagatsuka, Kazuyuki; Iida, Hidehiro; Ihara, Masafumi

    2016-01-01

    The bilateral common carotid artery stenosis (BCAS) mouse model, which replicates chronic cerebral hypoperfusion and white matter ischemic lesions, is considered to model some aspects of vascular cognitive impairment. Cerebral blood flow (CBF) changes in the brain surface post-BCAS have been demonstrated by laser speckle flowmetry, but CBF levels in the brain parenchyma remain unknown. Adult C57BL/6J male mice were subjected to BCAS using external microcoils. Brain magnetic resonance angiography (MRA) was conducted to visualize the intracranial main arteries while arterial spin labeling (ASL) was used to measure cortical and subcortical parenchymal CBF levels before and after BCAS. Brain MRA showed anterior circulation flow was substantially decreased until 14 days post-BCAS, which gradually but incompletely recovered over the following 14 days, with probable growth of collaterals from the posterior cerebral artery. ASL showed that cortical and subcortical parenchymal CBF remained decreased at approximately 50% of the baseline level during 1 and 14 days post-BCAS, recovering to approximately 70% at day 28. CBF levels in the parenchyma were lower than the cortical superficial region in the BCAS model and remained decreased without recovery during the first 2 weeks post-BCAS. These results suggest that the BCAS model reliably replicates chronic cerebral hypoperfusion. PMID:27535801

  20. Three-dimensional stereotactic atlas of the extracranial vasculature correlated with the intracranial vasculature, cranial nerves, skull and muscles.

    PubMed

    Nowinski, Wieslaw L; Shoon Let Thaung, Thant; Choon Chua, Beng; Hnin Wut Yi, Su; Yang, Yili; Urbanik, Andrzej

    2015-04-01

    Our objective was to construct a 3D, interactive, and reference atlas of the extracranial vasculature spatially correlated with the intracranial blood vessels, cranial nerves, skull, glands, and head muscles.The atlas has been constructed from multiple 3T and 7T magnetic resonance angiogram (MRA) brain scans, and 3T phase contrast and inflow MRA neck scans of the same specimen in the following steps: vessel extraction from the scans, building 3D tubular models of the vessels, spatial registration of the extra- and intracranial vessels, vessel editing, vessel naming and color-coding, vessel simplification, and atlas validation.This new atlas contains 48 names of the extracranial vessels (25 arterial and 23 venous) and it has been integrated with the existing brain atlas.The atlas is valuable for medical students and residents to easily get familiarized with the extracranial vasculature with a few clicks; is useful for educators to prepare teaching materials; and potentially can serve as a reference in the diagnosis of vascular disease and treatment, including craniomaxillofacial surgeries and radiologic interventions of the face and neck. PMID:25923683

  1. An innovative approach for characteristic analysis and state-of-health diagnosis for a Li-ion cell based on the discrete wavelet transform

    NASA Astrophysics Data System (ADS)

    Kim, Jonghoon; Cho, B. H.

    2014-08-01

    This paper introduces an innovative approach to analyze electrochemical characteristics and state-of-health (SOH) diagnosis of a Li-ion cell based on the discrete wavelet transform (DWT). In this approach, the DWT has been applied as a powerful tool in the analysis of the discharging/charging voltage signal (DCVS) with non-stationary and transient phenomena for a Li-ion cell. Specifically, DWT-based multi-resolution analysis (MRA) is used for extracting information on the electrochemical characteristics in both time and frequency domain simultaneously. Through using the MRA with implementation of the wavelet decomposition, the information on the electrochemical characteristics of a Li-ion cell can be extracted from the DCVS over a wide frequency range. Wavelet decomposition based on the selection of the order 3 Daubechies wavelet (dB3) and scale 5 as the best wavelet function and the optimal decomposition scale is implemented. In particular, this present approach develops these investigations one step further by showing low and high frequency components (approximation component An and detail component Dn, respectively) extracted from variable Li-ion cells with different electrochemical characteristics caused by aging effect. Experimental results show the clearness of the DWT-based approach for the reliable diagnosis of the SOH for a Li-ion cell.

  2. Three-dimensional stereotactic atlas of the extracranial vasculature correlated with the intracranial vasculature, cranial nerves, skull and muscles.

    PubMed

    Nowinski, Wieslaw L; Shoon Let Thaung, Thant; Choon Chua, Beng; Hnin Wut Yi, Su; Yang, Yili; Urbanik, Andrzej

    2015-04-01

    Our objective was to construct a 3D, interactive, and reference atlas of the extracranial vasculature spatially correlated with the intracranial blood vessels, cranial nerves, skull, glands, and head muscles.The atlas has been constructed from multiple 3T and 7T magnetic resonance angiogram (MRA) brain scans, and 3T phase contrast and inflow MRA neck scans of the same specimen in the following steps: vessel extraction from the scans, building 3D tubular models of the vessels, spatial registration of the extra- and intracranial vessels, vessel editing, vessel naming and color-coding, vessel simplification, and atlas validation.This new atlas contains 48 names of the extracranial vessels (25 arterial and 23 venous) and it has been integrated with the existing brain atlas.The atlas is valuable for medical students and residents to easily get familiarized with the extracranial vasculature with a few clicks; is useful for educators to prepare teaching materials; and potentially can serve as a reference in the diagnosis of vascular disease and treatment, including craniomaxillofacial surgeries and radiologic interventions of the face and neck.

  3. The MurE synthetase from Thermotoga maritima is endowed with an unusual D-lysine adding activity.

    PubMed

    Boniface, Audrey; Bouhss, Ahmed; Mengin-Lecreulx, Dominique; Blanot, Didier

    2006-06-01

    The peptidoglycan of Thermotoga maritima, an extremely thermophilic eubacterium, was shown to contain no diaminopimelic acid and approximate amounts of both enantiomers of lysine (Huber, R., Langworthy, T. A., König, H., Thomm, M., Woese, C. R., Sleytr, U. B., and Stetter, K. O. (1986) Arch. Microbiol. 144, 324-333). To assess the possible involvement of the MurE activity in the incorporation of D-lysine, the murE gene from this organism was cloned in Escherichia coli, and the corresponding protein was purified as the C-terminal His6-tagged form. In vitro assays showed that D-lysine and meso-diaminopimelic acid were added to UDP-N-acetylmuramoyl-dipeptide with 25 and 10% efficiencies, respectively, relative to L-lysine. The purified enzyme was used to synthesize the L- and D-lysine-containing UDP-N-acetylmuramoyl-tripeptides; chemical analysis revealed an unusual structure for the D-lysine-containing nucleotide, namely acylation of the epsilon-amino function of D-lysine by the D-glutamyl residue. In vitro assays with MurF and MraY enzymes from T. maritima showed that this novel nucleotide was not a substrate for MurF but that it could be directly processed into tripeptide lipid I by MraY, thereby substantiating the role of MurE in the incorporation of D-lysine into peptidoglycan.

  4. Final report on bilateral comparison SIM.EM-S9.b: Comparison of resistance standards at 1 Ω and 10 kΩ between INIMET (Cuba) and INTI (Argentina), March to October 2012

    NASA Astrophysics Data System (ADS)

    Tonina, A.; Currás, M.; Navarro, M.

    2014-01-01

    The CIPM MRA states that its technical basis is a set of results obtained in a course of time through key comparisons carried out by the Consultative Committees of the CIPM, the BIPM and the Regional Metrology Organizations (RMOs). As part of this process, INTI (Argentina) has participated in several key and supplementary comparisons. By means of procedures for linking key comparison data, a bilateral comparison would help to provide assurance of equality in measurements between the participating laboratories. With this end, the comparison SIM.EM-S9.b of 1 ohm and 10 kiloohm standard resistors of INIMET (Cuba) and INTI was carried out from March to October 2012. The obtained results were very good. They show that the resistance standards maintained by INTI and INIMET were equivalent, within their combined uncertainties, on the mean date of the comparison. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by SIM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  5. Clinical presentation and imaging results of patients with symptomatic gluteus medius tears

    PubMed Central

    Lindner, Dror; Shohat, Noam; Botser, Itamar; Agar, Gabriel; Domb, Benjamin G.

    2015-01-01

    Greater trochanteric pain syndrome (GTPS) is a common complaint. Recently, it has become well recognized that tendinopathy and tears of the gluteus medius (GM) are a cause of recalcitrant GTPS. Nevertheless, the clinical syndrome associated with GM tears is not fully characterized. We characterize the clinical history, findings on physical examination, imaging and intraoperative findings associated with symptomatic GM tears. Forty-five patients (47 hips) who underwent GM repair for the diagnosis of tear were evaluated. Pain was estimated on the visual analog scale (VAS) and hip-specific scores were administered to assess functional status. The imaging modalities were reviewed and intra operative findings were recorded. The average patient age was 54 years (17–76), 93% were females. Symptom onset was commonly insidious (75%) and the average time to diagnosis was 28 months (2–240). The most common pain location was the lateral hip (75%). The average pre-surgery VAS and modified Harris Hip Score were 6.65 (0–10) and 55.5 (12–90), respectively. All patients had pathological findings on magnetic resonance angiogram (MRA) ranging from tendinosis to complete tears of the GM tendon. There was a discrepancy between MRA interpretation by a radiologist and findings during surgery. Hip abductor tears are an under-recognized cause of hip pain and hip symptomatology. In this study, we further characterize the clinical presentation of this entity. The data we present here may facilitate early diagnosis, early orthopedic care and avoid unnecessary prolonged patient sufferings. PMID:27011854

  6. Visualization of hepatic arteries with 3D ultrasound during intra-arterial therapies

    NASA Astrophysics Data System (ADS)

    Gérard, Maxime; Tang, An; Badoual, Anaïs.; Michaud, François; Bigot, Alexandre; Soulez, Gilles; Kadoury, Samuel

    2016-03-01

    Liver cancer represents the second most common cause of cancer-related mortality worldwide. The prognosis is poor with an overall mortality of 95%. Moreover, most hepatic tumors are unresectable due to their advanced stage at discovery or poor underlying liver function. Tumor embolization by intra-arterial approaches is the current standard of care for advanced cases of hepatocellular carcinoma. These therapies rely on the fact that the blood supply of primary hepatic tumors is predominantly arterial. Feedback on blood flow velocities in the hepatic arteries is crucial to ensure maximal treatment efficacy on the targeted masses. Based on these velocities, the intra-arterial injection rate is modulated for optimal infusion of the chemotherapeutic drugs into the tumorous tissue. While Doppler ultrasound is a well-documented technique for the assessment of blood flow, 3D visualization of vascular anatomy with ultrasound remains challenging. In this paper we present an image-guidance pipeline that enables the localization of the hepatic arterial branches within a 3D ultrasound image of the liver. A diagnostic Magnetic resonance angiography (MRA) is first processed to automatically segment the hepatic arteries. A non-rigid registration method is then applied on the portal phase of the MRA volume with a 3D ultrasound to enable the visualization of the 3D mesh of the hepatic arteries in the Doppler images. To evaluate the performance of the proposed workflow, we present initial results from porcine models and patient images.

  7. [A Case of Fibromuscular Dysplasia in a Patient with Various Main Trunk Dissections in the Head and Neck over a Short Period].

    PubMed

    Ando, Kazuhiro; Sasaki, Osamu; Watanabe, Masatoshi; Nashimoto, Takeo; Kikuchi, Bumpei

    2016-07-01

    We report a case of subarachnoid hemorrhage(SAH)from an intracranial vertebral artery(VA)dissection in a patient with fibromuscular dysplasia(FMD)who presented with headache. A 54-year-old woman complained of spontaneous occipital headache. The dilatation of the left VA was detected on magnetic resonance angiography(MRA). She was diagnosed with left VA dissection(headache onset type). After sudden onset of headache on the second day of hospitalization, her consciousness level, as defined by the Japan Coma Scale, was 300. Computed tomography(CT)revealed SAH. Cerebral angiography showed the dilatation of the left intracranial VA and contrast material pooling, which was suspected to be a sign of dissection. We performed VA intravascular ligation by coil embolization. The postoperative course was good but postoperative MRA revealed arterial wall irregularities in both the extra cranial internal carotid artery and the right VA. Cerebral angiography showed the presence of the string-of-beads sign at these arteries. She was diagnosed with FMD. SAH might develop during the follow-up period in patients with VA dissection, even those in whom the initial symptom is headache. In addition, cases of FMD might also be complicated by various lesions of the main trunk of the cerebral artery. PMID:27384119

  8. [Successful Treatment of Repeated Bilateral Middle Cerebral Artery Occlusion by Performing Mechanical Thrombectomy in a Patient with Trousseau Syndrome].

    PubMed

    Inoue, Satoshi; Fujita, Atsushi; Mizowaki, Takashi; Uchihashi, Yoshito; Kuroda, Ryuichi; Urui, Seishirou; Kurihara, Eiji; Kohmura, Eiji

    2016-06-01

    We report a patient with Trousseau syndrome who presented with repeated acute middle cerebral artery (MCA) occlusion, which was successfully treated by performing mechanical thrombectomy. A 66-year-old man with a lung lesion and abdominal lymph node swelling experienced a sudden onset of left hemiparesis. Magnetic resonance angiography (MRA) revealed a right MCA occlusion. Perfusion-weighted imaging revealed reduced cerebral blood flow in the right MCA territory. Complete recanalization of the occluded vessel was achieved by performing mechanical thrombectomy, and his symptoms remarkably disappeared. Twenty days after the procedure, he experienced right hemiparesis and total aphasia. MRA revealed a left MCA occlusion, which was located on the contralateral side of the first occlusion. The second mechanical thrombectomy was successfully performed, and complete recanalization was successfully achieved. Right hemiparesis improved after the procedure. Histological examination of the retrieved clots revealed coagulated fibrin and platelets. Cytodiagnosis of pleural effusion revealed adenocarcinoma, and he was diagnosed with lung adenocarcinoma and cancerous pleurisy. Trousseau syndrome was the presumed primary cause of the patient's tendency for thrombogenesis. To the best of our knowledge, there were no reports regarding the repeated use of mechanical thrombectomy for patients with bilateral MCA occlusion caused by Trousseau syndrome. Neuroendovascular therapy can offer good neurological outcomes even in patients with malignant lesions. PMID:27270149

  9. Optimization of Regularization Parameters in Compressed Sensing of Magnetic Resonance Angiography: Can Statistical Image Metrics Mimic Radiologists' Perception?

    PubMed Central

    Akasaka, Thai; Fujimoto, Koji; Yamamoto, Takayuki; Okada, Tomohisa; Fushumi, Yasutaka; Yamamoto, Akira; Tanaka, Toshiyuki; Togashi, Kaori

    2016-01-01

    In Compressed Sensing (CS) of MRI, optimization of the regularization parameters is not a trivial task. We aimed to establish a method that could determine the optimal weights for regularization parameters in CS of time-of-flight MR angiography (TOF-MRA) by comparing various image metrics with radiologists’ visual evaluation. TOF-MRA of a healthy volunteer was scanned using a 3T-MR system. Images were reconstructed by CS from retrospectively under-sampled data by varying the weights for the L1 norm of wavelet coefficients and that of total variation. The reconstructed images were evaluated both quantitatively by statistical image metrics including structural similarity (SSIM), scale invariant feature transform (SIFT) and contrast-to-noise ratio (CNR), and qualitatively by radiologists’ scoring. The results of quantitative metrics and qualitative scorings were compared. SSIM and SIFT in conjunction with brain masks and CNR of artery-to-parenchyma correlated very well with radiologists’ visual evaluation. By carefully selecting a region to measure, we have shown that statistical image metrics can reflect radiologists’ visual evaluation, thus enabling an appropriate optimization of regularization parameters for CS. PMID:26744843

  10. [Evaluation of Vessel Depictability in Compressed Sensing MR Angiography Using Numerical Phantom Model].

    PubMed

    Saito, Toshiki; Machida, Yoshio; Miyamoto, Kota; Ichinoseki, Yuki

    2015-11-01

    As an acceleration technique for use with magnetic resonance imaging (MRI), compressed sensing MRI (CSMRI) was introduced recently to obtain MR images from under sampled k-space data. Images generated using a nonlinear iterative procedure based on sophisticated theory in informatics using data sparsity have complicated characteristics. Therefore, the factors affecting image quality (IQ) in CS-MRI must be elucidated. This article specifically describes the examination of the IQ of clinically important MR angiography (MRA). For MRA, the depictability of thin blood vessels is extremely important, but quantitative evaluation of thin blood vessel depictability is difficult. Therefore, we conducted numerical experiments using a simple numerical phantom model mimicking the cerebral arteries so that the experimental conditions, including the thin vessel positions, can be given. Results show that vessel depictability changed depending on the noise intensity when the wavelet transform was used as the sparsifying transform. Decreased vessel depictability might present difficulties at the clinical signal-to-noise ratio (SNR) level. Therefore, selecting data acquisition and reconstruction conditions carefully in terms of the SNR is crucially important for CS-MRI study. PMID:26596199

  11. The evaluation of vertebrobasilar artery system in neuro-Behçet and Behçet disease using magnetic resonance angiography.

    PubMed

    Kose, Evren; Kamisli, Suat; Dogan, Metin; Tasolar, Sevgi; Kahraman, Ayşegül; Oztanir, Mustafa Namik; Sener, Serpil

    2014-07-01

    The aim of this study is the evaluation of the vertebrobasilar artery system in patients with Behçet's and Neuro-Behçet's disease. For this aim; 20 adults with clinically diagnosed Behcet's disease, 20 adults with Neuro-Behçet's disease, and 19 age- and gender-matched controls were examined by magnetic resonance angiography (MRA). During MRA, diameters of left vertebral artery (LVA), right vertebral artery (RVA), basilar artery (BA), and proximal segment (P1) of posterior cerebral artery between origin and junction with the posterior communicating artery were measured. In all groups, LVA was dominant than RVA (P < 0.05). The diameters of BA and right P1 of Neuro-Behçet's disease were larger than the other groups (P < 0.05). In addition, the diameters of left P1 of Neuro-Behçet's disease were larger but not statistically significant. There is no difference between the groups in terms of gender. Behçet's disease can affect vascular structures; therefore vertebrobasilar artery system should be examined in patients with Behçet's and Neuro-Behçet's disease.

  12. Effects of extended aging and modified atmospheric packaging on beef top loin steak color.

    PubMed

    English, A R; Mafi, G G; VanOverbeke, D L; Ramanathan, R

    2016-04-01

    The objective of this study was to evaluate the effects of extended aging and modified atmospheric packaging on beef LM color. Using a randomized complete block design, each beef longissimus lumborum muscle ( = 10; USDA Choice, 3 d postmortem) was equally divided into 3 sections and randomly assigned to 1 of 3 aging periods (21, 42, or 62 d at 2°C). After respective aging, each loin section was cut into four 2.5-cm-thick steaks and randomly assigned to 1 of 3 packaging types (PVC, HiOx-MAP [80% oxygen and 20% carbon dioxide], or CO-MAP [0.4% carbon monoxide, 69.6% nitrogen, and 30% carbon dioxide]). The steaks were displayed under continuous fluorescent lighting for 6 d, and surface color was determined daily using a HunterLab Miniscan XE Plus spectrophotometer and a visual panel. The fourth steak was used to characterize oxygen consumption (OC), lipid oxidation, and metmyoglobin reducing activity (MRA) on 21, 42, and 62 d (before display). On d 6 display, MRA, OC, and lipid oxidation also were measured. An increase in aging time decreased ( < 0.0001) muscle pH. Loin sections aged for 42 and 62 d had a lower ( < 0.0002) pH compared with loin sections aged for 21 d. An aging period × packaging × display time interaction ( < 0.0001) resulted for a* values (redness), chroma, and visual color (muscle color and surface discoloration). As aging time increased, HiOx-MAP had the most discoloration ( < 0.0001) compared with other packaging types on d 6. At all aging periods, steaks packaged in CO-MAP had greater ( < 0.0001) MRA on d 6 than PVC and HiOx-MAP, whereas steaks packaged in HiOx-MAP had the least MRA ( < 0.0001). There were no differences ( = 0.34) in thiobarbituric acid reactive substances values between steaks aged for 21 and 42 d when steaks were packaged in CO-MAP and displayed for 6 d. However, steaks packaged in HiOx-MAP and displayed 6 d had greater ( < 0.0001) lipid oxidation than CO-MAP. Steaks packaged in HiOx-MAP had a lower ( < 0.0001) OC compared

  13. Gadofosveset: MS 325, MS 32520, Vasovist, ZK 236018.

    PubMed

    2004-01-01

    100 sales representatives. In January 2001, EPIX Medical reacquired the Japanese rights for gadofosveset from Daiichi Radioisotope Laboratories and exclusively licensed them to Schering AG. With this agreement, Schering AG has worldwide rights for gadofosveset. The financial terms of the Japanese rights agreement included a US$3 million upfront fee, and additional milestone payments from Schering AG to EPIX Medical. On 16 December 2003, EPIX announced that it submitted an NDA to the US FDA for gadofosveset for vascular imaging using magnetic resonance angio-graphy (MRA). This is the first NDA filed for approval with the FDA for a MR contrast agent for the primary indication of MRA. The NDA is based on the results of 18 clinical trials in 1438 patients who received gadofosveset. In February 2004, EPIX Medical announced that the NDA for gadofosveset was accepted for filing by the FDA and would proceed through a standard review cycle. The approval for gadofosveset is expected at the end of 2004. In January 2004, Schering reported at the JP Morgan Healthcare Conference that it plans a product launch in the US sometime in 2005.EPIX and Schering have completed four phase III studies in patients with suspected atherosclerotic disease in the aortoilliac, pedal and renal arteries for inclusion in the NDA submission. These trials were conducted at 86 clinical sites and involved 782 patients. The blinded reading of almost 4000 vessels showed that gadofosveset improved diagnostic accuracy of MRA compared with non-contrast MRA. The diagnostic efficacy of gadofosveset-enhanced MRA was comparable to that of x-ray angiography. These trials were initiated in accordance with the recommendations of the FDA to expand gadofosveset's target indication of aortoiliac occlusive disease to a broader peripheral vascular disease indication. In July 2004, EPIX Medical initiated a multicentre, post-NDA trial with gadofosveset for use in high-resolution vessel imaging for the characterisation of

  14. Application of 3.0T magnetic resonance arterial spin labeling (ASL) technology in mild and moderate intracranial atherosclerotic stenosis

    PubMed Central

    LI, ZHONGWEI; LI, NAIKUN; QU, YANYAN; GAI, FENG; ZHANG, GUOWEI; ZHANG, GUANGHUI

    2016-01-01

    The application value of 3.0T magnetic resonance arterial spin labeling (ASL) technology in mild and moderate intracranial atherosclerotic stenosis was evaluated. A total of 58 cases of transient ischemic attack (TIA) and 60 cases of ischemic cerebral apoplexy cases were selected. The cases were analysed using a GE Healthcare Signa HDx 3.0T superconducting whole-body magnetic resonance scan within 24 h of attack. Eight-channel head phased array coils and conventional sequence were used to create T1-weighted images (T1WI), T2WI, diffusion-weighted imaging, magnetic resonance angiography (MRA) and ASL imaging, which were generated into ASL pseudo-color images (blue was hypoperfusion area) through post-processing in order to compare and analyze the correlation and differences between ASL and conventional imaging in terms of lesion location, size, blood perfusion situation and signal range of relative cerebral blood flow (rCBF). The results showed that, 13 TIA cases of abnormal signal in conventional magnetic resonance imaging (MRI) can also be found through ASL technology. Diameter stenosis beyond 30% in MRA can also be tested in ASL. A positive rate in ASL was significantly higher than that of conventional MRI (χ2=29.078, P<0.001) and hypoperfusion area was greatly increased (t=32.526, P<0.001). The rCBF value was positively correlated with the degree of diameter stenosis shown in MRA (r=0.524, P=0.012). Additionally, the positive rate of ASL was positively correlated with the attack times of TIA (r=0.352, P=0.027). A total of 39 cerebral apoplexy cases of abnormal signal in conventional MRI were also found through ASL technology. A positive rate in ASL was significantly higher than that of conventional MRI (χ2=7.685, P=0.006) and hypoperfusion area was greatly increased (t=9.425, P<0.001). The rCBF value was positively correlated with the degree of diameter stenosis (r=0.635, P=0.009). In conclusion, 3.0T ASL correlated with early diagnosis of TIA and mild and

  15. A finite element solution to conjugated heat transfer in tissue using magnetic resonance angiography to measure the in vitro velocity field

    NASA Astrophysics Data System (ADS)

    Dutton, Andrew William

    1993-12-01

    A combined numerical and experimental system for tissue heat transfer analysis was developed. The goal was to develop an integrated set of tools for studying the problem of providing accurate temperature estimation for use in hyperthermia treatment planning in a clinical environment. The completed system combines (1) Magnetic Resonance Angiography (MRA) to non-destructively measure the velocity field in situ, (2) the Streamwise Upwind Petrov-Galerkin finite element solution to the 3D steady state convective energy equation (CEE), (3) a medical image based automatic 3D mesh generator, and (4) a Gaussian type estimator to determine unknown thermal model parameters such as thermal conductivity, blood perfusion, and blood velocities from measured temperature data. The system was capable of using any combination of three thermal models (1) the Convective Energy Equation (CEE), (2) the Bioheat Transfer Equation (BHTE), and (3) the Effective Thermal Conductivity Equation (ETCE) Incorporation of the theoretically correct CEE was a significant theoretical advance over approximate models made possible by the use of MRA to directly measure the 3D velocity field in situ. Experiments were carried out in a perfused alcohol fixed canine liver with hyperthermia induced through scanned focused ultrasound Velocity fields were measured using Phase Contrast Angiography. The complete system was then used to (1) develop a 3D finite element model based upon user traced outlines over a series of MR images of the liver and (2) simulate temperatures at steady state using the CEE, BHTE, and ETCE thermal models in conjunction with the gauss estimator. Results of using the system on an in vitro liver preparation indicate the need for improved accuracy in the MRA scans and accurate spatial registration between the thermocouple junctions, the measured velocity field, and the scanned ultrasound power No individual thermal model was able to meet the desired accuracy of 0.5 deg C, the resolution

  16. Cardiovascular magnetic resonance physics for clinicians: Part II.

    PubMed

    Biglands, John D; Radjenovic, Aleksandra; Ridgway, John P

    2012-09-20

    This is the second of two reviews that is intended to cover the essential aspects of cardiovascular magnetic resonance (CMR) physics in a way that is understandable and relevant to clinicians using CMR in their daily practice. Starting with the basic pulse sequences and contrast mechanisms described in part I, it briefly discusses further approaches to accelerate image acquisition. It then continues by showing in detail how the contrast behaviour of black blood fast spin echo and bright blood cine gradient echo techniques can be modified by adding rf preparation pulses to derive a number of more specialised pulse sequences. The simplest examples described include T2-weighted oedema imaging, fat suppression and myocardial tagging cine pulse sequences. Two further important derivatives of the gradient echo pulse sequence, obtained by adding preparation pulses, are used in combination with the administration of a gadolinium-based contrast agent for myocardial perfusion imaging and the assessment of myocardial tissue viability using a late gadolinium enhancement (LGE) technique. These two imaging techniques are discussed in more detail, outlining the basic principles of each pulse sequence, the practical steps required to achieve the best results in a clinical setting and, in the case of perfusion, explaining some of the factors that influence current approaches to perfusion image analysis. The key principles of contrast-enhanced magnetic resonance angiography (CE-MRA) are also explained in detail, especially focusing on timing of the acquisition following contrast agent bolus administration, and current approaches to achieving time resolved MRA. Alternative MRA techniques that do not require the use of an endogenous contrast agent are summarised, and the specialised pulse sequence used to image the coronary arteries, using respiratory navigator gating, is described in detail. The article concludes by explaining the principle behind phase contrast imaging techniques

  17. Vertebrobasilar dolichoectasia diagnosed by magnetic resonance angiography and risk of stroke and death: a cohort study

    PubMed Central

    Ubogu, E; Zaidat, O

    2004-01-01

    Objective: There are only limited epidemiological studies evaluating the association between vertebrobasilar dolichoectasia (VBD) and outcomes. This study was designed to elucidate the outcome and prognosis of adults diagnosed with VBD by magnetic resonance angiography (MRA) and to ascertain if these outcomes were independent of known vascular risk factors. Methods: A cohort study was designed to compare VBD cases identified retrospectively from a computerised database of MRA reports with age and sex matched controls evaluated after a 4–7 year period, and 1440 MRA reports were reviewed. The inclusion criteria were age ⩾18 years and a radiological diagnosis of VBD. Patients were excluded if there was haemodynamically significant stenosis or occlusion of the posterior circulation. Data were obtained by medical record review and telephone questionnaires. The primary outcome measure was transient or fixed posterior circulation dysfunction (PCD), with a secondary outcome measure of all cause mortality. Results: Sixty four VBD cases were obtained, and 19 cases (30%) were excluded due to refusal and/or insufficient follow up data. From the same computerised database, 45 controls were selected by consecutive sampling. The mean age at follow up was 73.4 years for VBD cases and 73.1 years for controls, with a median follow up period of 64 months. VBD was associated with fixed/transient PCD (p = 0.0001; estimated adjusted odds ratio (OR) of 20.6 and confidence interval (CI) of 4.4 to 95.3), and with all cause mortality (OR = 3.6 CI 1.3 to10.3); (p = 0.018). VBD cases had 36% mortality, with 50% occurring within 34 months of the initial diagnosis. The VBD cumulative survival curve was statistically different from the controls (p = 0.012 by Mantel-Cox log rank test). Conclusions: This study suggests that VBD may be an independent risk factor for stroke. VBD cases had an increased likelihood for PCD, all cause mortality, and reduced cumulative survival independent of other

  18. A prospective study of shoulder pain in primary care: Prevalence of imaged pathology and response to guided diagnostic blocks

    PubMed Central

    2011-01-01

    Background The prevalence of imaged pathology in primary care has received little attention and the relevance of identified pathology to symptoms remains unclear. This paper reports the prevalence of imaged pathology and the association between pathology and response to diagnostic blocks into the subacromial bursa (SAB), acromioclavicular joint (ACJ) and glenohumeral joint (GHJ). Methods Consecutive patients with shoulder pain recruited from primary care underwent standardised x-ray, diagnostic ultrasound scan and diagnostic injections of local anaesthetic into the SAB and ACJ. Subjects who reported less than 80% reduction in pain following either of these injections were referred for a magnetic resonance arthrogram (MRA) and GHJ diagnostic block. Differences in proportions of positive and negative imaging findings in the anaesthetic response groups were assessed using Fishers test and odds ratios were calculated a for positive anaesthetic response (PAR) to diagnostic blocks. Results In the 208 subjects recruited, the rotator cuff and SAB displayed the highest prevalence of pathology on both ultrasound (50% and 31% respectively) and MRA (65% and 76% respectively). The prevalence of PAR following SAB injection was 34% and ACJ injection 14%. Of the 59% reporting a negative anaesthetic response (NAR) for both of these injections, 16% demonstrated a PAR to GHJ injection. A full thickness tear of supraspinatus on ultrasound was associated with PAR to SAB injection (OR 5.02; p < 0.05). Ultrasound evidence of a biceps tendon sheath effusion (OR 8.0; p < 0.01) and an intact rotator cuff (OR 1.3; p < 0.05) were associated with PAR to GHJ injection. No imaging findings were strongly associated with PAR to ACJ injection (p ≤ 0.05). Conclusions Rotator cuff and SAB pathology were the most common findings on ultrasound and MRA. Evidence of a full thickness supraspinatus tear was associated with symptoms arising from the subacromial region, and a biceps tendon sheath effusion

  19. Automated 3D Volumetry of the Pulmonary Arteries based on Magnetic Resonance Angiography Has Potential for Predicting Pulmonary Hypertension

    PubMed Central

    Rengier, Fabian; Wörz, Stefan; Melzig, Claudius; Ley, Sebastian; Fink, Christian; Benjamin, Nicola; Partovi, Sasan; von Tengg-Kobligk, Hendrik; Rohr, Karl; Kauczor, Hans-Ulrich; Grünig, Ekkehard

    2016-01-01

    Purpose To demonstrate feasibility of automated 3D volumetry of central pulmonary arteries based on magnetic resonance angiography (MRA), to assess pulmonary artery volumes in patients with pulmonary hypertension compared to healthy controls, and to investigate the potential of the technique for predicting pulmonary hypertension. Methods MRA of pulmonary arteries was acquired at 1.5T in 20 patients with pulmonary arterial hypertension and 21 healthy normotensive controls. 3D model-based image analysis software was used for automated segmentation of main, right and left pulmonary arteries (MPA, RPA and LPA). Volumes indexed to vessel length and mean, minimum and maximum diameters along the entire vessel course were assessed and corrected for body surface area (BSA). For comparison, diameters were also manually measured on axial reconstructions and double oblique multiplanar reformations. Analyses were performed by two cardiovascular radiologists, and by one radiologist again after 6 months. Results Mean volumes of MPA, RPA and LPA for patients/controls were 5508 ± 1236/3438 ± 749, 3522 ± 934/1664 ± 468 and 3093 ± 692/1812 ± 474 μl/(cm length x m2 BSA) (all p<0.001). Mean, minimum and maximum diameters along the entire vessel course were also significantly increased in patients compared to controls (all p<0.001). Intra- and interobserver agreement were excellent for both volume and diameter measurements using 3D segmentation (intraclass correlation coefficients 0.971–0.999, p<0.001). Area under the curve for predicting pulmonary hypertension using volume was 0.998 (95% confidence interval 0.990–1.0, p<0.001), compared to 0.967 using manually measured MPA diameter (95% confidence interval 0.910–1.0, p<0.001). Conclusions Automated MRA-based 3D volumetry of central pulmonary arteries is feasible and demonstrated significantly increased volumes and diameters in patients with pulmonary arterial hypertension compared to healthy controls. Pulmonary artery

  20. Pediatric cardiovascular interventional devices: effect on CMR images at 1.5 and 3 Tesla

    PubMed Central

    2013-01-01

    Background To predict the type and extent of CMR artifacts caused by commonly used pediatric trans-catheter devices at 1.5 T and 3 T as an aid to clinical planning and patient screening. Methods Eleven commonly used interventional, catheter-based devices including stents, septal occluders, vascular plugs and embolization coils made from either stainless steel or nitinol were evaluated ex-vivo at both 1.5T and 3T. Pulse sequences and protocols commonly used for cardiovascular magnetic resonance (CMR) were evaluated, including 3D high-resolution MR angiography (MRA), time-resolved MRA, 2D balanced-SSFP cine and 2D phase-contrast gradient echo imaging (GRE). We defined the signal void amplification factor (F) as the ratio of signal void dimension to true device dimension. F1 and F2 were measured in the long axis and short axes respectively of the device. We defined F3 as the maximum extent of the off-resonance dark band artifact on SSFP measured in the B0direction. The effects of field strength, sequence type, orientation, flip angle and phase encode direction were tested. Clinical CMR images in 3 patients with various indwelling devices were reviewed for correlation with the in-vitro findings. Results F1 and F2 were higher (p<0.05) at 3T than at 1.5T for all sequences except 3D-MRA. Stainless steel devices produced greater off-resonance artifact on SSFP compared to nitinol devices (p<0.05). Artifacts were most severe with the stainless steel Flipper detachable embolization coil (Cook Medical, Bloomington, IN), with F1 and F2 10 times greater than with stainless steel stents. The orientation of stents changed the size of off-resonance artifacts by up to two fold. Sequence type did influence the size of signal void or off-resonance artifact (p<0.05). Varying the flip angle and phase encode direction did not affect image artifact. Conclusion Stainless steel embolization coils render large zones of anatomy uninterpretable, consistent with predictions based on ex

  1. Common Carotid Intima Media Thickness and Ankle-Brachial Pressure Index Correlate with Local but Not Global Atheroma Burden: A Cross Sectional Study Using Whole Body Magnetic Resonance Angiography

    PubMed Central

    Weir-McCall, Jonathan R.; Khan, Faisel; Lambert, Matthew A.; Adamson, Carly L.; Gardner, Michael; Gandy, Stephen J.; Ramkumar, Prasad Guntur; Belch, Jill J. F.; Struthers, Allan D.; Rauchhaus, Petra; Morris, Andrew D.; Houston, J. Graeme

    2014-01-01

    Background Common carotid intima media thickness (CIMT) and ankle brachial pressure index (ABPI) are used as surrogate marker of atherosclerosis, and have been shown to correlate with arterial stiffness, however their correlation with global atherosclerotic burden has not been previously assessed. We compare CIMT and ABPI with atheroma burden as measured by whole body magnetic resonance angiography (WB-MRA). Methods 50 patients with symptomatic peripheral arterial disease were recruited. CIMT was measured using ultrasound while rest and exercise ABPI were performed. WB-MRA was performed in a 1.5T MRI scanner using 4 volume acquisitions with a divided dose of intravenous gadolinium gadoterate meglumine (Dotarem, Guerbet, FR). The WB-MRA data was divided into 31 anatomical arterial segments with each scored according to degree of luminal narrowing: 0 = normal, 1 = <50%, 2 = 50–70%, 3 = 70–99%, 4 = vessel occlusion. The segment scores were summed and from this a standardized atheroma score was calculated. Results The atherosclerotic burden was high with a standardised atheroma score of 39.5±11. Common CIMT showed a positive correlation with the whole body atheroma score (β 0.32, p = 0.045), however this was due to its strong correlation with the neck and thoracic segments (β 0.42 p = 0.01) with no correlation with the rest of the body. ABPI correlated with the whole body atheroma score (β −0.39, p = 0.012), which was due to a strong correlation with the ilio-femoral vessels with no correlation with the thoracic or neck vessels. On multiple linear regression, no correlation between CIMT and global atheroma burden was present (β 0.13 p = 0.45), while the correlation between ABPI and atheroma burden persisted (β −0.45 p = 0.005). Conclusion ABPI but not CIMT correlates with global atheroma burden as measured by whole body contrast enhanced magnetic resonance angiography in a population with symptomatic peripheral

  2. Markers of acute neuropsychiatric systemic lupus erythematosus: a multidisciplinary evaluation.

    PubMed

    Abda, Essam A; Selim, Zahraa I; Radwan, Moustafa E M; Mahmoud, Nagham M; Herdan, Omar M; Mohamad, Khalid A; Hamed, Sherifa A

    2013-05-01

    This study was aimed to assess: (1) the additive diagnostic utility of diffusion-weighted imaging (DWI) and magnetic resonance angiography (MRA) over conventional MRI in detecting brain lesions in patients with acute primary neuropsychiatric systemic lupus erythematosus (NPSLE), and (2) the relevance of their findings to the associated NP manifestations. Included were 34 patients with acute NPSLE with mean age of 33.26 ± 10.14 years and duration of illness of 3.33 ± 1.71 years. Clinical interviewing and psychiatric and cognitive evaluations were performed by applying the criteria of the diagnostic and statistical manual of mental health disorders criteria (DSM-IV), Stanford Binet Subset Testing, Mini-Mental State Examination and Wechsler Memory Scale-Revised. Serologic tests included looking for antinuclear antibodies, anti-double strand DNA, anti-phospholipid antibodies. Radiologic evaluation included conventional MRI, DWI and MRA. One or more NP manifestations were diagnosed in 28 patients, in which cognitive deficits were reported with headache, psychosis and CVS. Anti-phospholipid antibodies were reported in patients with CVS. Twenty patients (71.43 %) with primary NPSLE (n = 28) had MRI abnormalities in which hyperintense signals at subcortical and periventricular white matter and at the junction between the gray and white matter represented 75 % (n = 15) and with headache (n = 6), psychosis (n = 6) and acute confusional state (n = 3) with and without cognitive deficits, respectively. Moderate-sized infarctions with restricted diffusion in the distribution of middle cerebral arteries were represented in 35 % (n = 7) and with CVS, of them, 71.43 % (n = 5) had beading and focal narrowing of carotid arteries were consistent with vasculitis. Brain atrophy represented 20 % (n = 4) and with psychosis. Compared to those with normal MRI, patients with MRI abnormalities were older (P < 0.050) and had longer duration of illness (P < 0.050). To conclude, although DWI

  3. Can Automated Imaging for Optic Disc and Retinal Nerve Fiber Layer Analysis Aid Glaucoma Detection?

    PubMed Central

    Banister, Katie; Boachie, Charles; Bourne, Rupert; Cook, Jonathan; Burr, Jennifer M.; Ramsay, Craig; Garway-Heath, David; Gray, Joanne; McMeekin, Peter; Hernández, Rodolfo; Azuara-Blanco, Augusto

    2016-01-01

    Purpose To compare the diagnostic performance of automated imaging for glaucoma. Design Prospective, direct comparison study. Participants Adults with suspected glaucoma or ocular hypertension referred to hospital eye services in the United Kingdom. Methods We evaluated 4 automated imaging test algorithms: the Heidelberg Retinal Tomography (HRT; Heidelberg Engineering, Heidelberg, Germany) glaucoma probability score (GPS), the HRT Moorfields regression analysis (MRA), scanning laser polarimetry (GDx enhanced corneal compensation; Glaucoma Diagnostics (GDx), Carl Zeiss Meditec, Dublin, CA) nerve fiber indicator (NFI), and Spectralis optical coherence tomography (OCT; Heidelberg Engineering) retinal nerve fiber layer (RNFL) classification. We defined abnormal tests as an automated classification of outside normal limits for HRT and OCT or NFI ≥ 56 (GDx). We conducted a sensitivity analysis, using borderline abnormal image classifications. The reference standard was clinical diagnosis by a masked glaucoma expert including standardized clinical assessment and automated perimetry. We analyzed 1 eye per patient (the one with more advanced disease). We also evaluated the performance according to severity and using a combination of 2 technologies. Main Outcome Measures Sensitivity and specificity, likelihood ratios, diagnostic, odds ratio, and proportion of indeterminate tests. Results We recruited 955 participants, and 943 were included in the analysis. The average age was 60.5 years (standard deviation, 13.8 years); 51.1% were women. Glaucoma was diagnosed in at least 1 eye in 16.8%; 32% of participants had no glaucoma-related findings. The HRT MRA had the highest sensitivity (87.0%; 95% confidence interval [CI], 80.2%–92.1%), but lowest specificity (63.9%; 95% CI, 60.2%–67.4%); GDx had the lowest sensitivity (35.1%; 95% CI, 27.0%–43.8%), but the highest specificity (97.2%; 95% CI, 95.6%–98.3%). The HRT GPS sensitivity was 81.5% (95% CI, 73.9%–87.6%), and

  4. Horner's Syndrome due to a Spontaneous Internal Carotid Artery Dissection after Deep Sea Scuba Diving

    PubMed Central

    Fernández Reyes, Jose Luis; Envid Lázaro, Blanca Mar; Fernández Letamendi, Teresa; Yeste Martín, Ryth; Jódar Morente, Francisco José

    2016-01-01

    Internal carotid artery dissection (ICAD) is a rare entity that either results from traumatic injury or can be spontaneously preceded or not by a minor trauma such as sporting activities. It represents a major cause of stroke in young patients. The diagnosis should be suspected with the combination of Horner's syndrome, headache or neck pain, and retinal or cerebral ischaemia. The confirmation is frequently made with a magnetic resonance angiography (MRA). Although anticoagulation with heparin followed by vitamin-K-antagonists is the most common treatment, there is no difference in efficacy of antiplatelet and anticoagulant drugs at preventing stroke and death in patients with symptomatic carotid dissection. We describe a patient with ICAD following deep sea scuba diving, who presented with Horner's syndrome and neck pain and was successfully treated with anticoagulants. PMID:27525139

  5. Multidetector spiral CT arthrography of the shoulder. Clinical applications and limits, with MR arthrography and arthroscopic correlations.

    PubMed

    Lecouvet, Frédéric E; Simoni, Paolo; Koutaïssoff, Sophie; Vande Berg, Bruno C; Malghem, Jacques; Dubuc, Jean-Emile

    2008-10-01

    Although MR imaging and MR arthrography are the first choice modalities for shoulder imaging, CT arthrography (CTA) may be used successfully to address many clinical questions. The advent of submillimeter multiple detector CT technology and subsequent excellent three-plane resolution has considerably increased the quality of CTA examinations and has propelled this technique to the forefront in a growing number of indications. The combined use of iodinated contrast material for fluoroscopic confirmation of the articular position of the needle before injection of gadolinium chelates for MR arthrography offers the unique opportunity to compare CTA and MRA findings in carefully selected cases. This paper illustrates capabilities and limits of CTA for the study of rotator cuff tears, shoulder instability, cartilage lesions, anatomical variants and abnormalities of the glenoid labrum, with correlations to MR arthrography and surgical findings.

  6. Carotid and vertebral artery dissection syndromes

    PubMed Central

    Thanvi, B; Munshi, S; Dawson, S; Robinson, T

    2005-01-01

    Cervicocerebral arterial dissections (CAD) are an important cause of strokes in younger patients accounting for nearly 20% of strokes in patients under the age of 45 years. Extracranial internal carotid artery dissections comprise 70%–80% and extracranial vertebral dissections account for about 15% of all CAD. Aetiopathogenesis of CAD is incompletely understood, though trauma, respiratory infections, and underlying arteriopathy are considered important. A typical picture of local pain, headache, and ipsilateral Horner's syndrome followed after several hours by cerebral or retinal ischaemia is rare. Doppler ultrasound, MRI/MRA, and CT angiography are useful non-invasive diagnostic tests. The treatment of extracranial CAD is mainly medical using anticoagulants or antiplatelet agents although controlled studies to show their effectiveness are lacking. The prognosis of extracranial CAD is generally much better than that of the intracranial CAD. Recurrences are rare in CAD. PMID:15937204

  7. Bias correction of satellite precipitation products for flood forecasting application at the Upper Mahanadi River Basin in Eastern India

    NASA Astrophysics Data System (ADS)

    Beria, H.; Nanda, T., Sr.; Chatterjee, C.

    2015-12-01

    High resolution satellite precipitation products such as Tropical Rainfall Measuring Mission (TRMM), Climate Forecast System Reanalysis (CFSR), European Centre for Medium-Range Weather Forecasts (ECMWF), etc., offer a promising alternative to flood forecasting in data scarce regions. At the current state-of-art, these products cannot be used in the raw form for flood forecasting, even at smaller lead times. In the current study, these precipitation products are bias corrected using statistical techniques, such as additive and multiplicative bias corrections, and wavelet multi-resolution analysis (MRA) with India Meteorological Department (IMD) gridded precipitation product,obtained from gauge-based rainfall estimates. Neural network based rainfall-runoff modeling using these bias corrected products provide encouraging results for flood forecasting upto 48 hours lead time. We will present various statistical and graphical interpretations of catchment response to high rainfall events using both the raw and bias corrected precipitation products at different lead times.

  8. A Case of Subacute Ataxia in the Summertime: Tick Paralysis.

    PubMed

    Laufer, Christin B; Chiota-McCollum, Nicole

    2015-08-01

    Tick paralysis is caused by a neurotoxin secreted in the saliva of a gravid female tick, and manifests with ataxia, areflexia, ascending paralysis, bulbar palsy, and ophthalmoparesis. An 84-year-old man presented in June in coastal Mississippi with several days of subacute ataxia, bulbar palsy, unilateral weakness, and absent deep tendon reflexes. MRI/MRA and extensive serum and cerebrospinal fluid investigations were unrevealing. His symptoms progressed over several days, until his nurse discovered and removed an engorged tick from his gluteal fold. Within hours of tick removal, his subacute symptoms completely resolved. While tick paralysis is rare in adults, it is a condition that internists should be familiar with, particularly in seasons and areas with high prevalence of disease. This case also highlights the importance of performing a thorough skin exam on patients with the aforementioned neurologic abnormalities. PMID:25794538

  9. Reversible cerebral vasoconstriction in Guillain-Barré syndrome.

    PubMed

    Wei, Diana Y; Kao, Justin; Wu, Teddy Y; Pereira, Jennifer A; Anderson, Neil E; Alan Barber, P

    2015-07-01

    We present a 51-year-old woman with clinical and neurophysiological evidence of Guillain-Barré syndrome (GBS) who developed a generalised headache and autonomic dysfunction with sinus tachycardia, hypertension, gastrointestinal motility symptoms and urinary retention. MRI/MRA demonstrated cerebral vasoconstriction and a small convexity subarachnoid haemorrhage which resolved after 3 months. Reversible cerebral vasoconstriction syndrome (RCVS) is characterised by headache, focal neurological deficits or seizures, and reversible cerebral vasoconstriction. To our knowledge, this is the first reported case of RCVS complicating autonomic dysfunction in GBS. This case depicts a rare complication of a common condition and also sheds light on the potential mechanism of RCVS. Neurologists should be aware that autonomic dysfunction can lead to RCVS in GBS.

  10. HYPR: constrained reconstruction for enhanced SNR in dynamic medical imaging

    NASA Astrophysics Data System (ADS)

    Mistretta, C.; Wieben, O.; Velikina, J.; Wu, Y.; Johnson, K.; Korosec, F.; Unal, O.; Chen, G.; Fain, S.; Christian, B.; Nalcioglu, O.; Kruger, R. A.; Block, W.; Samsonov, A.; Speidel, M.; Van Lysel, M.; Rowley, H.; Supanich, M.; Turski, P.; Wu, Yan; Holmes, J.; Kecskemeti, S.; Moran, C.; O'Halloran, R.; Keith, L.; Alexander, A.; Brodsky, E.; Lee, J. E.; Hall, T.; Zagzebski, J.

    2008-03-01

    During the last eight years our group has developed radial acquisitions with angular undersampling factors of several hundred that accelerate MRI in selected applications. As with all previous acceleration techniques, SNR typically falls as least as fast as the inverse square root of the undersampling factor. This limits the SNR available to support the small voxels that these methods can image over short time intervals in applications like time-resolved contrast-enhanced MR angiography (CE-MRA). Instead of processing each time interval independently, we have developed constrained reconstruction methods that exploit the significant correlation between temporal sampling points. A broad class of methods, termed HighlY Constrained Back PRojection (HYPR), generalizes this concept to other modalities and sampling dimensions.

  11. KEY COMPARISON: Final report on CCEM key comparison CCEM.RF-K10.CL (GT-RF/99-2) 'Power in 50 Ω coaxial lines, frequency: 50 MHz to 26 GHz' measurement techniques and results

    NASA Astrophysics Data System (ADS)

    Janik, Dieter; Inoue, T.; Michaud, A.

    2006-01-01

    This report summarizes the results and the measuring methods of an international key comparison between twelve national metrology institutes (NMIs) and is concerning the calibration factor of RF power sensors in the coaxial 3.5 mm line for frequencies up to 26 GHz. Two RF power travelling standards fitted with male PC 3.5 mm connectors were measured at seven frequencies. The following NMIs participated: NMIJ (Japan), NRC (Canada), NIST (USA), METAS (Switzerland), CSIR-NML (South Africa), NMIA (Australia), NPL (UK), SiQ (Slovenia), IEN (Italy), VNIIFTRI (Russian Federation), SPRING (Singapore) and PTB (Germany), as the pilot laboratory. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  12. Greenland to gather more exploration data

    SciTech Connect

    Not Available

    1991-01-28

    Danish authorities are taking steps to make more exploration data available on Greenland in advance of a possible West Greenland shelf licensing round in 1993. Seismic data acquisition and other studies continue toward more fully evaluating Greenland's oil and gas potential. Geological Survey of Greenland (GGU), Copenhagen, Denmark, is processing 2,041 line miles of reflection seismic data shot on the West Greenland shelf in August and September of 1990. Sixty-fold stacks and migrations will be obtained. Total field magnetic data were also recorded during the survey, known as project Syd Vest Seis. Early work is under way to kick off the multicompany Kanumas seismic acquisition project, proposed in 1986, during 1991. Meanwhile, the Mineral Resources Administration for Greenland (MRA), Copenhagen, the Danish and Greenland governments aim to sweeten Greenland's exploration regulations prior to making areas available.

  13. Greenland unveils terms for offshore licenses

    SciTech Connect

    Not Available

    1992-04-20

    This paper reports that Greenland has spelled out terms for its first round of offshore licensing. The action off western Greenland could lead to the first oil and gas exploration there since an unsuccessful campaign in the 1970s. The Mineral Resources Administration (MRA) for Greenland pegged exploration license terms on 133 blocks, all south of the 66th parallel, at 10 years with options for 2 year extensions to a maximum of 6 more years. The license can cover as many as six blocks. In the first 3 year period companies will have only a seismic obligation of 1,588 km per six blocks. For the second 3 year period there will be a one well obligation and one well in each subsequent 2 year periods.

  14. The dimensions of mobilities: the spatial relationships between corporeal and digital mobilities.

    PubMed

    Taipale, Sakari

    2014-01-01

    The aim of this article is to study how the corporeal and digital mobilities are spatially organised in relation to each other in everyday life. The dimensions of mobilities are modelled by using survey data (N=612) collected from Finland in 2011, Multiple Correspondence Analysis (MCA) and Multiple Regression Analysis (MRA). The results show that the combined use of corporeal and digital means of mobility affect the spatial organisation of mobilities only little. The results indicate that young people and students are more likely to benefit from their mobility in networking activities as they are equipped with a larger variety of mobility means than older people and pensioners. Lastly, women and people living in essentially urban areas are more likely to augment their physical travelling practices by using small-sized digital mobilities than men and people living in rural locations.

  15. Reconstructing cerebrovascular networks under local physiological constraints by integer programming

    DOE PAGES

    Rempfler, Markus; Schneider, Matthias; Ielacqua, Giovanna D.; Xiao, Xianghui; Stock, Stuart R.; Klohs, Jan; Szekely, Gabor; Andres, Bjoern; Menze, Bjoern H.

    2015-04-23

    We introduce a probabilistic approach to vessel network extraction that enforces physiological constraints on the vessel structure. The method accounts for both image evidence and geometric relationships between vessels by solving an integer program, which is shown to yield the maximum a posteriori (MAP) estimate to the probabilistic model. Starting from an over-connected network, it is pruning vessel stumps and spurious connections by evaluating the local geometry and the global connectivity of the graph. We utilize a high-resolution micro computed tomography (µCT) dataset of a cerebrovascular corrosion cast to obtain a reference network and learn the prior distributions of ourmore » probabilistic model. As a result, we perform experiments on micro magnetic resonance angiography (µMRA) images of mouse brains and discuss properties of the networks obtained under different tracking and pruning approaches.« less

  16. Reconstructing cerebrovascular networks under local physiological constraints by integer programming

    SciTech Connect

    Rempfler, Markus; Schneider, Matthias; Ielacqua, Giovanna D.; Xiao, Xianghui; Stock, Stuart R.; Klohs, Jan; Szekely, Gabor; Andres, Bjoern; Menze, Bjoern H.

    2015-04-23

    We introduce a probabilistic approach to vessel network extraction that enforces physiological constraints on the vessel structure. The method accounts for both image evidence and geometric relationships between vessels by solving an integer program, which is shown to yield the maximum a posteriori (MAP) estimate to the probabilistic model. Starting from an over-connected network, it is pruning vessel stumps and spurious connections by evaluating the local geometry and the global connectivity of the graph. We utilize a high-resolution micro computed tomography (µCT) dataset of a cerebrovascular corrosion cast to obtain a reference network and learn the prior distributions of our probabilistic model. As a result, we perform experiments on micro magnetic resonance angiography (µMRA) images of mouse brains and discuss properties of the networks obtained under different tracking and pruning approaches.

  17. [Study of elliptical centric view ordering technique with spectrally selected inversion recovery pulse (spec-IR pulse)].

    PubMed

    Okuaki, Tomoyuki; Yamashita, Midori; Wakamatsu, Osamu; Shirouzu, Ichiro; Machida, Toru; Matsuda, Tsuyoshi

    2003-03-01

    Among several techniques for contrast-enhanced MRA, the elliptical centric view ordering method, originally developed at the Mayo Clinic, is a promising one. It has been difficult to apply a fat-suppression prepulse, mainly because the conventional fat suppression method requires a longer acquisition time during sampling of the low-frequency domain in k-space, and it causes severe image distortion due to the great change in longitudinal magnetization derived from fat tissue. We developed a novel method to append fat saturation to the elliptical centric view ordering technique, and assessed the feasibility of its use. Our method is to apply fat-saturation pulses only at selected sampling points when any gradient is applied in the slice-encoding direction. In this way, we achieved efficient suppression of fat-derived signal within a relatively short time, comparable to that of the conventional fat-saturation method, and succeeded in minimizing artifacts. PMID:12740563

  18. KEY COMPARISON: Final report, on-going key comparison BIPM.QM-K1: Ozone at ambient level, comparison with ISCIII, 2007

    NASA Astrophysics Data System (ADS)

    Viallon, Joële; Moussay, Philippe; Wielgosz, Robert; Morillo Gomez, Pilar; Sánchez Blaya, Carmen

    2009-01-01

    As part of the on-going key comparison BIPM.QM-K1, a comparison has been performed between the ozone national standard of the Instituto de Salud Carlos III (ISCIII) and the common reference standard of the key comparison, maintained by the Bureau International des Poids et Mesures (BIPM). The instruments have been compared over a nominal ozone mole fraction range of 0 nmol/mol to 500 nmol/mol. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  19. Final report, ongoing key comparison BIPM.QM-K1, ozone at ambient level, comparison with ISCIII (December 2014)

    NASA Astrophysics Data System (ADS)

    Viallon, Joële; Moussay, Philippe; Idrees, Faraz; Wielgosz, Robert; Sanchez, Carmen; Morillo Gomez, Pilar

    2015-01-01

    As part of the ongoing key comparison BIPM.QM-K1, a comparison has been performed between the ozone national standard of the Instituto de Salud Carlos III (ISCIII) and the common reference standard of the key comparison, maintained by the Bureau International des Poids et Mesures (BIPM). The instruments have been compared over a nominal ozone amount-of-substance fraction range of 0 nmol/mol to 500 nmol/mol. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  20. Final report on the ongoing key comparison BIPM.QM-K1: Ozone at ambient level, comparison with ISCIII (December 2012)

    NASA Astrophysics Data System (ADS)

    Viallon, Joële; Moussay, Philippe; Idrees, Faraz; Wielgosz, Robert; Morillo Gomez, Pilar; Sánchez, Carmen

    2013-01-01

    As part of the ongoing key comparison BIPM.QM-K1, a comparison has been performed between the ozone national standard of the Instituto de Salud Carlos III (ISCIII) and the common reference standard of the key comparison, maintained by the Bureau International des Poids et Mesures (BIPM). The instruments have been compared over a nominal ozone amount-of-substance fraction range of 0 nmol/mol to 500 nmol/mol. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  1. Final report on the ongoing key comparison BIPM.QM-K1: Ozone at ambient level, comparison with ISCIII (December 2010)

    NASA Astrophysics Data System (ADS)

    Viallon, Joële; Moussay, Philippe; Idrees, Faraz; Wielgosz, Robert; Morillo Gomez, Pilar; Sánchez, Carmen

    2011-01-01

    As part of the ongoing key comparison BIPM.QM-K1, a comparison has been performed between the ozone national standard of the Instituto de Salud Carlos III (ISCIII) and the common reference standard of the key comparison, maintained by the Bureau International des Poids et Mesures (BIPM). The instruments have been compared over a nominal ozone amount-of-substance fraction range of 0 nmol/mol to 500 nmol/mol. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  2. Detection of Orthoimage Mosaicking Seamlines by Means of Wavelet Transform

    NASA Astrophysics Data System (ADS)

    Pyka, K.

    2016-06-01

    The detection of orthoimage mosaicking seamlines by means of wavelet transform was examined. Radiometric alignment was omitted, giving priority to the issue of seamlines which bypass locations where there is a parallax between orthoimages. The importance of this issue is particularly relevant for images with very high resolution. In order to create a barrier image between orthoimages, the redundant wavelet transform variant known as MODWT-MRA was used. While more computationally complex than the frequently used DWT, it enables very good multiresolution edge detection. An IT prototype was developed on the basis of the described concept, and several cases of seamline detection were tested on the basis of data with a resolution of 10 cm to 1 m. The correct seamline location was obtained for each test case. This result opens the door to future expansion of the radiometric alignment method, which is also based on wavelets.

  3. [Effect of MRSA on treatment and care in Finland - applications for compensation and complaints in 1993 to 2012].

    PubMed

    Lumio, Jukka

    2015-01-01

    Events involving applications for compensation or filing a complaint in a MRSA case in Finland by patients or family members were studied for over a twenty-year period. The number of cases found was 305. Of the applications, only 7% resulted in compensation, and none of the complaints led to a change in decision. The discontentment was more commonly associated with the possible MRSA-induced impairment of the given treatment or limitations in freedom than with the fear of the direct health effects of the infection. In order to avoid problems, essential aspects include an intimate knowledge of guidelines among those working in the treatment and care sector, and proper informing of the patients about the effects of MRA on life. PMID:26536722

  4. SUPPLEMENTARY COMPARISON: Bilateral direct comparison of Josephson array voltage standards of the PTB (Germany) and PEL (Croatia): Draft B report for EUROMET.EM-S28

    NASA Astrophysics Data System (ADS)

    Behr, Ralf; Ilić, Damir; Šala, Alan

    2008-01-01

    A comparison of the 10 V Josephson array voltage standard of the Physikalisch-Technische Bundesanstalt (PTB), Germany, was made with that of the Primarni Elektromagnetski Laboratorij (PEL), Croatia, in April 2007. The results are in very good agreement and the measured overall relative combined standard uncertainty is better than 1 part in 1010. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by EURAMET, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  5. Unusual case of persistent Horner's syndrome following epidural anaesthesia and caesarean section.

    PubMed

    Goel, Shubhra; Burkat, Cat Nguyen

    2011-01-01

    This is a rare case of persistent Horner's syndrome following epidural anesthesia and Caesarean section. A 33-year-old female presented with persistent ptosis and miosis following epidural anesthesia and Caesarian section several months prior. Magnetic resonance imaging (MRI)/magnetic resonance angiography (MRA) of head, neck, and chest were unremarkable. Medline search using terms Horner's, epidural, spinal anesthesia, delivery, childbirth, Caesarian, and pregnancy identified 31 articles describing Horner's syndrome in obstetric epidural anesthesia, of which 11 were following Caesarean section. The increased incidence of Horner's syndrome in the setting of epidural anesthesia in pregnancy may be related to epidural venous engorgement and cephalic spread of the local anaesthetic, with disruption in the oculosympathetic pathway. It is important to include recent epidural anesthesia within the differential diagnosis of acute Horner's syndrome in a postpartum female. Rarely, the ptosis may be permanent and require surgical intervention.

  6. Horner's Syndrome due to a Spontaneous Internal Carotid Artery Dissection after Deep Sea Scuba Diving.

    PubMed

    Alonso Formento, Jose Enrique; Fernández Reyes, Jose Luis; Envid Lázaro, Blanca Mar; Fernández Letamendi, Teresa; Yeste Martín, Ryth; Jódar Morente, Francisco José

    2016-01-01

    Internal carotid artery dissection (ICAD) is a rare entity that either results from traumatic injury or can be spontaneously preceded or not by a minor trauma such as sporting activities. It represents a major cause of stroke in young patients. The diagnosis should be suspected with the combination of Horner's syndrome, headache or neck pain, and retinal or cerebral ischaemia. The confirmation is frequently made with a magnetic resonance angiography (MRA). Although anticoagulation with heparin followed by vitamin-K-antagonists is the most common treatment, there is no difference in efficacy of antiplatelet and anticoagulant drugs at preventing stroke and death in patients with symptomatic carotid dissection. We describe a patient with ICAD following deep sea scuba diving, who presented with Horner's syndrome and neck pain and was successfully treated with anticoagulants. PMID:27525139

  7. [Middle and anterior cerebral arteries dissection as a cause of ischemic stroke in a 7-year-old boy].

    PubMed

    Kalashnikova, L A; Dreval', M V; Dobrynina, L A; Krotenkova, M V

    2016-01-01

    Authors describe a 7-year-old boy, who developed a severe right-sided hemiparesis, aphasia, seizure, and confusion state during sport games. There was no headache. Allergic dermatitis in the past medical history and influenza vaccination 2 weeks before stroke were recorded. On the 12th day of disease, MRI of the brain revealed an acute infarction in the territory of left anterior and middle cerebral arteries with hemorrhagic transformation. MPA (15 day) showed occlusion of the left ACA and MCA. HR-MRI T1_db_fs weighted imaging (36 day) found intramural hematoma (IMH) in ACA and MCA with marked stenosis of the lumen. After 3 months, HR-MRI/MRA showed the complete regression of IMH, recanalization of the arterial lumen, prolonged irregular MCA stenosis. Neurological deficit regressed significantly.

  8. Carotid body paraganglioma.

    PubMed

    Manzoor, Tahir; Ahmed, Bashir; Najam, Atif; Ayub, Zeeshan

    2009-08-01

    Carotid body tumours are benign neoplasms. This case report describes two patients with this rare tumour with diagnostic workup and treatment options. The first case was a 36-year-old gentleman who presented with 6 months history of painless swelling on the left side of neck. The second patient was 60-years-old man who presented with slowly growing swelling on the right side of neck for the last 20 years. Both patients had transmitted pulsations over the swelling. On suspicion of a vascular lesion, a contrast enhanced CT scan and Doppler's ultrasound of neck was advised which suggested the diagnosis of a carotid body tumour. Magnetic Resonance Angiography (MRA) confirmed the diagnosis. Excision in collaboration with vascular surgeon was planned for the first case. The second case was subjected to radiation therapy due to the large size of tumour and the patient's age.

  9. KEY COMPARISON: Final report of comparison of the calibrations of hydrometers for liquid density determination between SIM laboratories: SIM.M.D-K4

    NASA Astrophysics Data System (ADS)

    Becerra, Luis Omar

    2009-01-01

    This SIM comparison on the calibration of high accuracy hydrometers was carried out within fourteen laboratories in the density range from 600 kg/m3 to 1300 kg/m3 in order to evaluate the degree of equivalence among participant laboratories. This key comparison anticipates the planned key comparison CCM.D-K4, and is intended to be linked with CCM.D-K4 when results are available. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  10. SUPPLEMENTARY COMPARISON: Report of the bilateral comparison of the calibrations of hydrometers for liquid density determination between CENAM-Mexico and INRIM-Italy: SIM.M.D-S1

    NASA Astrophysics Data System (ADS)

    Becerra, Luis Omar; Lorefice, Salvatore

    2009-01-01

    Hydrometers are instruments usually made of glass which are widely used for different levels of precision to measure liquid density and related quantities to control different products and processes. This bilateral comparison on the calibration of hydrometers shows that results reported by CENAM-Mexico and INRIM-Italy are consistent within the claimed uncertainty in the range of 800 kg/m3 to 1200 kg/m3. This bilateral comparison is intended to link the two regional comparisons SIM.M.D-K4 and EURAMET.D-K4. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by SIM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  11. SUPPLEMENTARY COMPARISON Bilateral comparison on the calibrations of hydrometers for liquid density between INRIM-Italy and INMETRO-Brazil: SIM.M.D-S2

    NASA Astrophysics Data System (ADS)

    Lorefice, Salvatore; Malta, Dalni; Julio Pinheiro, José; Marteleto, Paulo Roberto

    2010-01-01

    The results of the SIM.M.D-S2 bilateral comparison between INRIM-Italy and INMETRO-Brazil are summarized in this report. The aims of this comparison were to check the stated uncertainty levels and the degrees of equivalence between the two institutes on the calibration of hydrometers for liquid density in the range of 800 kg m-3 to 1000 kg m-3 at 20 ºC, by means of two transfer standards of excellent metrological characteristics. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by SIM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  12. Final report of the ongoing key comparison BIPM.QM-K1: Ozone at ambient level, comparison with NMC, A*STAR, May 2013

    NASA Astrophysics Data System (ADS)

    Viallon, Joële; Moussay, Philippe; Wielgosz, Robert; Li, Hou; Hui, Wendy Liu; Norris, James E.; Guenther, Frank

    2014-01-01

    As part of the on-going key comparison BIPM.QM-K1, a comparison has been performed between the ozone national standard of Singapore maintained by the National Metrology Centre, A*STAR (NMC, A*STAR) and the common reference standard of the key comparison, maintained by the Bureau International des Poids et Mesures (BIPM), via a transfer standard maintained by the National Institute of Standards and Technology (NIST). The instruments have been compared over a nominal ozone amount-of-substance fraction range of 0 nmol/mol to 500 nmol/mol Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  13. Blood Pool Segmentation Results in Superior Virtual Cardiac Models than Myocardial Segmentation for 3D Printing.

    PubMed

    Farooqi, Kanwal M; Lengua, Carlos Gonzalez; Weinberg, Alan D; Nielsen, James C; Sanz, Javier

    2016-08-01

    The method of cardiac magnetic resonance (CMR) three-dimensional (3D) image acquisition and post-processing which should be used to create optimal virtual models for 3D printing has not been studied systematically. Patients (n = 19) who had undergone CMR including both 3D balanced steady-state free precession (bSSFP) imaging and contrast-enhanced magnetic resonance angiography (MRA) were retrospectively identified. Post-processing for the creation of virtual 3D models involved using both myocardial (MS) and blood pool (BP) segmentation, resulting in four groups: Group 1-bSSFP/MS, Group 2-bSSFP/BP, Group 3-MRA/MS and Group 4-MRA/BP. The models created were assessed by two raters for overall quality (1-poor; 2-good; 3-excellent) and ability to identify predefined vessels (1-5: superior vena cava, inferior vena cava, main pulmonary artery, ascending aorta and at least one pulmonary vein). A total of 76 virtual models were created from 19 patient CMR datasets. The mean overall quality scores for Raters 1/2 were 1.63 ± 0.50/1.26 ± 0.45 for Group 1, 2.12 ± 0.50/2.26 ± 0.73 for Group 2, 1.74 ± 0.56/1.53 ± 0.61 for Group 3 and 2.26 ± 0.65/2.68 ± 0.48 for Group 4. The numbers of identified vessels for Raters 1/2 were 4.11 ± 1.32/4.05 ± 1.31 for Group 1, 4.90 ± 0.46/4.95 ± 0.23 for Group 2, 4.32 ± 1.00/4.47 ± 0.84 for Group 3 and 4.74 ± 0.56/4.63 ± 0.49 for Group 4. Models created using BP segmentation (Groups 2 and 4) received significantly higher ratings than those created using MS for both overall quality and number of vessels visualized (p < 0.05), regardless of the acquisition technique. There were no significant differences between Groups 1 and 3. The ratings for Raters 1 and 2 had good correlation for overall quality (ICC = 0.63) and excellent correlation for the total number of vessels visualized (ICC = 0.77). The intra-rater reliability was good for Rater A (ICC = 0.65). Three models were successfully printed

  14. Simultaneous segmentation and anatomical labeling of the cerebral vasculature.

    PubMed

    Robben, David; Türetken, Engin; Sunaert, Stefan; Thijs, Vincent; Wilms, Guy; Fua, Pascal; Maes, Frederik; Suetens, Paul

    2016-08-01

    We present a novel algorithm for the simultaneous segmentation and anatomical labeling of the cerebral vasculature. Unlike existing approaches that first attempt to obtain a good segmentation and then perform labeling, we optimize for both by simultaneously taking into account the image evidence and the prior knowledge about the geometry and connectivity of the vasculature. This is achieved by first constructing an overcomplete graph capturing the vasculature, and then selecting and labeling the subset of edges that most likely represents the true vasculature. We formulate the latter problem as an Integer Program (IP), which can be solved efficiently to provable optimality. We evaluate our approach on a publicly available dataset of 50 cerebral MRA images, and demonstrate that it compares favorably against state-of-the-art methods. PMID:27131026

  15. [Effect of MRSA on treatment and care in Finland - applications for compensation and complaints in 1993 to 2012].

    PubMed

    Lumio, Jukka

    2015-01-01

    Events involving applications for compensation or filing a complaint in a MRSA case in Finland by patients or family members were studied for over a twenty-year period. The number of cases found was 305. Of the applications, only 7% resulted in compensation, and none of the complaints led to a change in decision. The discontentment was more commonly associated with the possible MRSA-induced impairment of the given treatment or limitations in freedom than with the fear of the direct health effects of the infection. In order to avoid problems, essential aspects include an intimate knowledge of guidelines among those working in the treatment and care sector, and proper informing of the patients about the effects of MRA on life.

  16. Precursory Subsurface 222Rn and 220Rn Degassing Signatures of the 2004 Seismic Crisis at Tenerife, Canary Islands

    NASA Astrophysics Data System (ADS)

    Pérez, Nemesio M.; Hernández, Pedro A.; Padrón, Eleazar; Melián, Gladys; Marrero, Rayco; Padilla, Germán; Barrancos, José; Nolasco, Dácil

    2007-12-01

    Precursory geochemical signatures of radon degassing in the subsurface of the Tenerife Island were observed several months prior to the recent 2004 seismic-volcanic crisis. These premonitory signatures were detected by means of a continuous monitoring of 222Rn and 220Rn activity from a bubbling CO2-rich gas spot located at 2.850 m depth inside a horizontal gallery for groundwater exploitation at Tenerife. Multivariate Regression Analysis (MRA) on time series of the radon activity was applied to eliminate the radon activity fluctuation due to external variables such as barometric pressure, temperature and relative humidity as well as power supply. Material Failure Forecast Method (FFM) was successfully applied to forecast the anomalous seismicity registered in Tenerife Island in 2004. The changes in the 222Rn/220Rn ratio observed after the period of anomalous seismicity might suggest a higher gas flow rate and/or changes in the vertical permeability induced by seismic activity.

  17. Final report of supplementary comparison AFRIMETS.AUV.A-S1: primary pressure calibration of LS2aP microphones according to IEC 61094-2, over the frequency range 1 Hz to 31.5 kHz.

    NASA Astrophysics Data System (ADS)

    Nel, R.; Barrera-Figueroa, S.; Dobrowolska, D.; Defilippo Soares, Z. M.; Maina, A. K.; Hof, C.

    2016-01-01

    This is the final report of the AFRIMETS.AUV-S1 comparison of the pressure sensitivity, modulus and phase, of LS2aP microphones in the frequency range 1 Hz to 31.5 kHz in accordance with IEC 61094-2. Six national metrology institutes from three different regional metrology organisations participated in the comparison for which two LS2aP microphones were circulated simultaneously to all the participants in a hybrid-star configuration. The comparison reference values were calculated as the weighted mean for modulus and phase for each individual microphone. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCAUV, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  18. Determination of the magnetic susceptibility and the magentic polarization of weights by means of the susceptometer method

    NASA Astrophysics Data System (ADS)

    Quiroga, A.; Bermudez, A.; Kornblit, F.; Garcia, F.; Fang, H.; Caceres, J.; Peña, L. M.; Ramos, O.; Viaggio, A.; Santo, C.

    2016-01-01

    This report summarizes the results of a SIM comparison of magentic properties by means of the susceptometer method. It was carried out by seven SIM laboraories and BIPM. Five standards have been circulated: two OIML weights class E2, two of them with nominal value 1 kg and two of them with nominal value 2 g, and a steel disk. Most of the results were consistent with each other. This final report shows the degree of equivalence achieved by the participants Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  19. Chromosome Conformation Capture on Chip (4C): Data Processing.

    PubMed

    Leblanc, Benjamin; Comet, Itys; Bantignies, Frédéric; Cavalli, Giacomo

    2016-01-01

    4C methods are useful to investigate dependencies between regulatory mechanisms and chromatin structures by revealing the frequency of chromatin contacts between a locus of interest and remote sequences on the chromosome. In this chapter we describe a protocol for the data analysis of microarray-based 4C experiments, presenting updated versions of the methods we used in a previous study of the large-scale chromatin interaction profile of a Polycomb response element in Drosophila. The protocol covers data preparation, normalization, microarray probe selection, and the multi-resolution detection of regions with enriched chromatin contacts. A reanalysis of two independent mouse datasets illustrates the versatility of this protocol and the importance of data processing in 4C. Methods were implemented in the R package MRA.TA (Multi-Resolution Analyses on Tiling Array data), and they can be used to analyze ChIP-on-chip data on broadly distributed chromatin components such as histone marks. PMID:27659990

  20. Final report on key comparison CCQM-K96: Determination of amount content of dichromate

    NASA Astrophysics Data System (ADS)

    Máriássy, Michal; Hanková, Zuzana; Hwang, Euijin; Lim, Youngran; Pratt, Kenneth W.; Hioki, Akiharu; Asakai, Toshiaki; Bing, Wu; Liandi, Ma; Chao, Wei; Sobina, Alena; Shimolin, Alexandr; Junior, Wiler B. S.; Borges, Paulo P.; Matehuala, Francisco Javier; Segoviano, Francisco; Rivera, Griselda; Ramírez, Pedro; del Rocio Arvizu, María; Ortiz-Aparicio, José Luis

    2013-01-01

    The key comparison CCQM-K96 was organized jointly by the inorganic and electrochemistry working groups of CCQM to test the abilities of the metrology institutes to measure the amount content of dichromate. Slovak Institute of Metrology with help of KRISS acted as the coordinating laboratories. Eight NMIs took part in the comparison. All participants used high accuracy constant current coulometry. Good agreement of the results was observed. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  1. Coronary artery anomalies.

    PubMed

    Earls, James P

    2006-12-01

    Coronary artery anomalies are uncommon findings but can be of significant clinical importance in a small number of individuals. Clinical presentation depends on the specific anomaly. Most coronary artery anomalies are benign and clinically insignificant, however, some anomalies are potentially significant and can lead to heart failure and even death. Noninvasive imaging has emerged as the preferred way to image coronary anomalies. Both electron beam computed tomography (EBCT) and magnetic resonance angiography (MRA) are useful for the diagnosis of anomalous coronary arteries. Recently, MDCT has also proven to be very useful in the detection and characterization of anomalous coronary arteries. This chapter will review the appearance of the most commonly encountered coronary anomalies on MDCT. PMID:17709086

  2. Recovery of phase inconsistencies in continuously moving table extended field of view magnetic resonance imaging acquisitions.

    PubMed

    Kruger, David G; Riederer, Stephen J; Rossman, Phillip J; Mostardi, Petrice M; Madhuranthakam, Ananth J; Hu, Houchun H

    2005-09-01

    MR images formed using extended FOV continuously moving table data acquisition can have signal falloff and loss of lateral spatial resolution at localized, periodic positions along the direction of table motion. In this work we identify the origin of these artifacts and provide a means for correction. The artifacts are due to a mismatch of the phase of signals acquired from contiguous sampling fields of view and are most pronounced when the central k-space views are being sampled. Correction can be performed using the phase information from a periodically sampled central view to adjust the phase of all other views of that view cycle, making the net phase uniform across each axial plane. Results from experimental phantom and contrast-enhanced peripheral MRA studies show that the correction technique substantially eliminates the artifact for a variety of phase encode orders.

  3. Magnetic resonance imaging of thoracic aortic aneurysm and dissection.

    PubMed

    Roberts, D A

    2001-10-01

    MRI is an extremely useful technique for the evaluation of the thoracic aorta. It provides a comprehensive evaluation of all the important structures within the chest and allows for high-resolution imaging of both the aortic lumen and the wall itself. As such, it is a sensitive method for delineating the extent of disease, branch-vessel involvement, and superimposed complications. Technical advances, such as stepped-table MRA and bolus-timing strategies, continue to improve overall image quality. In addition, the recent development of blood-pool contrast agents may further impact the diagnostic yield. Given these facts, MRI is likely to remain a mainstay in this patient population for years to come. PMID:11715325

  4. Non-contact measurement of pulse wave velocity using RGB cameras

    NASA Astrophysics Data System (ADS)

    Nakano, Kazuya; Aoki, Yuta; Satoh, Ryota; Hoshi, Akira; Suzuki, Hiroyuki; Nishidate, Izumi

    2016-03-01

    Non-contact measurement of pulse wave velocity (PWV) using red, green, and blue (RGB) digital color images is proposed. Generally, PWV is used as the index of arteriosclerosis. In our method, changes in blood volume are calculated based on changes in the color information, and is estimated by combining multiple regression analysis (MRA) with a Monte Carlo simulation (MCS) model of the transit of light in human skin. After two pulse waves of human skins were measured using RGB cameras, and the PWV was calculated from the difference of the pulse transit time and the distance between two measurement points. The measured forehead-finger PWV (ffPWV) was on the order of m/s and became faster as the values of vital signs raised. These results demonstrated the feasibility of this method.

  5. International key comparison CCQM-K94: 10 μmol/mol dimethyl sulfide in nitrogen

    NASA Astrophysics Data System (ADS)

    Lee, S.; Heo, G. S.; Kim, Y.; Oh, S.; Han, Q.; Wu, H.; Konopelko, L. A.; Kustikov, Y. A.; Kolobova, A. V.; Efremova, O. V.; Pankratov, V. V.; Pavlov, M. V.; Culleton, L. P.; Brown, A. S.; Brookes, C.; Li, J.; Ziel, P. R.; van der Veen, A. M. H.

    2016-01-01

    Dimethyl sulfide (DMS) is an important compound in monitoring climate change and is monitored by the World Meteorological Organization Global Atmospheric Watch Volatile Organic Compounds (WMO-GAW VOC) program at several monitoring sites. It is essential that measurement results are accurate and consistent among the assigned values for primary gas mixtures to meet the WMO requirement. The purpose of this comparison is to compare the measurement capability of DMS at approximately 10 μ­mol/mol and expectation to contribute the establishment of traceability to single measurement scale for DMS between NMIs. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  6. Final report: COOMET 344/UA/05 supplementary comparison of 50/60 Hz power (COOMET.EM-S2)

    NASA Astrophysics Data System (ADS)

    Velychko, O.; Karpenko, S.; Gachok, V.; Akhmadov, O.

    2015-01-01

    This report describes the results of supplementary comparison COOMET.EM-S2 (also known as regional comparison COOMET 344/UA/05) of AC power measurements at low frequency (50/53 Hz). Three participants were involved in the measurements carried out from 2008 to 2011, with the aim of supporting their Calibration and Measurement Capabilities (CMCs). The results of this comparison are described in the report. They show that the differences between almost all laboratory's values and the reference values are within the expanded measurement uncertainties at a coverage factor k = 2. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  7. SUPPLEMENTARY COMPARISON: NORAMET intercomparison of volume standards at 50 mL and 100 mL (SIM.M.FF-S1)

    NASA Astrophysics Data System (ADS)

    Jacques, C.; Trujillo Juarez, S.; Maldonado, J. M.; Bean, V.

    2003-01-01

    An intercomparison of volume standards, 50 mL and 100 mL pycnometers, was decided on at the NORAMET Technical Contacts Meeting of 8-9 June 1998. The participating laboratories were CENAM, NIST, and NRC. NRC acted as the pilot laboratory. The comparison was done between April 1999 and October 1999. The pycnometers were not protected against evaporation by a supplementary cap. Even with this handicap, the three laboratories agreed with one another very well. The difference between maximum and minimum reported volumes never exceeded 0.014%. This comparison was assigned the number SIM.M.FF-S1. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the SIM, according to the provisions of the Mutual Recognition Arrangement (MRA).

  8. Bilateral comparison of cryogenic radiometers between NPL and UME, linked to the CCPR-S3 supplementary comparison

    NASA Astrophysics Data System (ADS)

    Goodman, T.

    2016-01-01

    This report presents the results of a bilateral comparison between NPL and UME, which was carried out to establish the unilateral degrees of equivalence for UME with respect to the defined reference value of the CCPR S3 supplementary comparison of cryogenic radiometers using silicon trap detectors as transfer devices. In accordance with the protocol for the CCPR S3 comparison, UME was asked to calibrate a set of NPL supplied silicon trap transfer detectors at a series of laser wavelengths; UME chose to measure at 514.5 nm and 632.8 nm. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCPR, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  9. Gadolinium-enhanced magnetic resonance angiography in brain death

    NASA Astrophysics Data System (ADS)

    Luchtmann, M.; Beuing, O.; Skalej, M.; Kohl, J.; Serowy, S.; Bernarding, J.; Firsching, R.

    2014-01-01

    Confirmatory tests for the diagnosis of brain death in addition to clinical findings may shorten observation time required in some countries and may add certainty to the diagnosis under specific circumstances. The practicability of Gadolinium-enhanced magnetic resonance angiography to confirm cerebral circulatory arrest was assessed after the diagnosis of brain death in 15 patients using a 1.5 Tesla MRI scanner. In all 15 patients extracranial blood flow distal to the external carotid arteries was undisturbed. In 14 patients no contrast medium was noted within intracerebral vessels above the proximal level of the intracerebral arteries. In one patient more distal segments of the anterior and middle cerebral arteries (A3 and M3) were filled with contrast medium. Gadolinium-enhanced MRA may be considered conclusive evidence of cerebral circulatory arrest, when major intracranial vessels fail to fill with contrast medium while extracranial vessels show normal blood flow.

  10. Comparison BIPM.RI(I)-K8 of high dose-rate Ir-192 brachytherapy standards for reference air kerma rate of the NRC and the BIPM

    NASA Astrophysics Data System (ADS)

    Kessler, C.; Downton, B.; Mainegra-Hing, E.

    2015-01-01

    An indirect comparison of the standards for reference air kerma rate for 192Ir high dose rate (HDR) brachytherapy sources of the National Research Council (NRC), Canada, and of the Bureau International des Poids et Mesures (BIPM) was carried out at the NRC in August 2014. The comparison result, based on the calibration coefficients for a transfer standard and expressed as a ratio of the NRC and the BIPM standards for reference air kerma rate, is 0.9966 with a combined standard uncertainty of 0.0050. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  11. Comparison BIPM.RI(I)-K8 of high dose-rate Ir-192 brachytherapy standards for reference air kerma rate of the NMIJ and the BIPM

    NASA Astrophysics Data System (ADS)

    Kessler, C.; Kurosawa, T.; Mikamoto, T.

    2016-01-01

    An indirect comparison of the standards for reference air kerma rate for 192Ir high dose rate (HDR) brachytherapy sources of the National Metrology Institute of Japan (AIST-NMIJ), Japan, and of the Bureau International des Poids et Mesures (BIPM) was carried out at the Japan Radioisotope Association (JRIA) in April 2015. The comparison result, based on the calibration coefficients for a transfer standard and expressed as a ratio of the NMIJ and the BIPM standards for reference air kerma rate, is 1.0036 with a combined standard uncertainty of 0.0054. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  12. Comparison BIPM.RI(I)-K8 of high dose-rate Ir-192 brachytherapy standards for reference air kerma rate of the PTB and the BIPM

    NASA Astrophysics Data System (ADS)

    Kessler, C.; Allisy-Roberts, P. J.; Selbach, H. J.

    2015-01-01

    An indirect comparison of the standards for reference air kerma rate (RAKR) for 192Ir high dose rate (HDR) brachytherapy sources of the Physikalisch-Technische Bundesanstalt (PTB), Germany, and of the Bureau International des Poids et Mesures (BIPM) was carried out at the PTB in September 2011. The comparison result, based on the calibration coefficients for a transfer standard and expressed as a ratio of the PTB and the BIPM standards for reference air kerma rate, is 1.0003 with a combined standard uncertainty of 0.0099. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  13. [Spinal cord infarction].

    PubMed

    Naumann, N; Shariat, K; Ulmer, S; Stippich, C; Ahlhelm, F J

    2012-05-01

    Infarction of the spinal cord can cause a variety of symptoms and neurological deficits because of the complex vascular supply of the myelon. The most common leading symptom is distal paresis ranging from paraparesis to tetraplegia caused by arterial ischemia or infarction of the myelon. Venous infarction, however, cannot always be distinguished from arterial infarction based on the symptoms alone.Modern imaging techniques, such as computed tomography angiography (CTA) and magnetic resonance angiography (MRA) assist in preoperative planning of aortic operations to reliably identify not only the most important vascular structure supplying the spinal cord, the artery of Adamkiewicz, but also other pathologies such as tumors or infectious disorders. In contrast to CT, MRI can reliably depict infarction of the spinal cord.

  14. Imaging of superior labral anterior to posterior (SLAP) tears of the shoulder.

    PubMed

    Simoni, P; Scarciolla, L; Kreutz, J; Meunier, B; Beomonte Zobel, B

    2012-12-01

    Superior labral anterior to posterior (SLAP) tears include a number of abnormal changes of the superior glenoid labrum. SLAP tears have been first reported in elite young atlete and are caused by repetitive overhead motion or by a fall on an outstretched arm. SLAP can lead to chronic pain and instability of shoulder. A diagnosis of SLAP may be difficult on the basis of clinical tests. Hence, modern imaging, including computed tomography arthrography (CTA), magnetic resonance imaging (MRI) and magnetic resonance arthrography (MRA) play a key role in the diagnosis of SLAP. The large number of normal anatomic variants of the superior labrum and the surrounding structures make the interpretation of SLAP challenging on imaging and at arthroscopy. In this article the imaging of SLAP are discussed in detail along with relevant anatomy, anatomic variants and biomechanics.

  15. Blood Pool Segmentation Results in Superior Virtual Cardiac Models than Myocardial Segmentation for 3D Printing.

    PubMed

    Farooqi, Kanwal M; Lengua, Carlos Gonzalez; Weinberg, Alan D; Nielsen, James C; Sanz, Javier

    2016-08-01

    The method of cardiac magnetic resonance (CMR) three-dimensional (3D) image acquisition and post-processing which should be used to create optimal virtual models for 3D printing has not been studied systematically. Patients (n = 19) who had undergone CMR including both 3D balanced steady-state free precession (bSSFP) imaging and contrast-enhanced magnetic resonance angiography (MRA) were retrospectively identified. Post-processing for the creation of virtual 3D models involved using both myocardial (MS) and blood pool (BP) segmentation, resulting in four groups: Group 1-bSSFP/MS, Group 2-bSSFP/BP, Group 3-MRA/MS and Group 4-MRA/BP. The models created were assessed by two raters for overall quality (1-poor; 2-good; 3-excellent) and ability to identify predefined vessels (1-5: superior vena cava, inferior vena cava, main pulmonary artery, ascending aorta and at least one pulmonary vein). A total of 76 virtual models were created from 19 patient CMR datasets. The mean overall quality scores for Raters 1/2 were 1.63 ± 0.50/1.26 ± 0.45 for Group 1, 2.12 ± 0.50/2.26 ± 0.73 for Group 2, 1.74 ± 0.56/1.53 ± 0.61 for Group 3 and 2.26 ± 0.65/2.68 ± 0.48 for Group 4. The numbers of identified vessels for Raters 1/2 were 4.11 ± 1.32/4.05 ± 1.31 for Group 1, 4.90 ± 0.46/4.95 ± 0.23 for Group 2, 4.32 ± 1.00/4.47 ± 0.84 for Group 3 and 4.74 ± 0.56/4.63 ± 0.49 for Group 4. Models created using BP segmentation (Groups 2 and 4) received significantly higher ratings than those created using MS for both overall quality and number of vessels visualized (p < 0.05), regardless of the acquisition technique. There were no significant differences between Groups 1 and 3. The ratings for Raters 1 and 2 had good correlation for overall quality (ICC = 0.63) and excellent correlation for the total number of vessels visualized (ICC = 0.77). The intra-rater reliability was good for Rater A (ICC = 0.65). Three models were successfully printed

  16. Final report on supplementary comparison of the calibration of a 5 kg stainless steel standard weight between INDECOPI-PERÚ and CEM-ESPAÑA (SIM.M.M-S10)

    NASA Astrophysics Data System (ADS)

    Quiroga Rojas, Aldo; Nieves Medina, María

    2012-01-01

    This report summarizes the results of the supplementary comparison SIM.M.M-S10 of a 5 kg stainless steel mass standard between INDECOPI (Peru) and CEM (Spain).The objective of the comparison was to demonstrate the metrological equivalence between the two laboratories. The results of the comparison will be used to support the Calibration and Measurement Capabilities (CMCs) declared by the institutes at 5 kg. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the SIM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  17. SUPPLEMENTARY COMPARISON Final report on EUROMET.L-S19 (EUROMET Project 910): Comparison of squareness measurements

    NASA Astrophysics Data System (ADS)

    Mokros, Jiri

    2010-01-01

    A bilateral comparison has been undertaken between two European national metrology institutes (NMIs) in the subject field of squareness measurement. Specifically, both NMIs made measurements of a cylindrical squareness standard, made of steel. Both participants made measurements of the internal angles at several positions around the circumference, as well as measurement of the corresponding straightness profiles. The report lists the results obtained by both participants, as well as an analysis of the results and their uncertainties. The results are in good agreement with one another. This bilateral comparison followed the same technical protocol as a previous supplementary comparison (EUROMET.L-S10). Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by EURAMET, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  18. SUPPLEMENTARY COMPARISON: Final report on COOMET.RI(II)-S2.Cs-137 (319/RU/04): Comparison measurements of radionuclide volume sources (Cs-137)

    NASA Astrophysics Data System (ADS)

    Korostin, S.; Hernandez, T.; Oropesa, P.; Arnold, D.; Evseev, V.; Ivanukovich, A.; Milevskiy, V.; Svec, A.; Lapenas, A.; Andonova, V.; Steiner, V.

    2010-01-01

    Measurements of the Cs-137 specific activity in artificial volume material of water density were performed in nine laboratories with the HPGe spectrometry technique. Analysis of the gamma radiation absorption in the measured material and in the most important substances for environmental monitoring (food, water, biological materials, soils) confirmed Compton scattering as the main mechanism of interaction. The list of CMCs supported by the comparison is suggested in the report of this comparison. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by COOMET, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  19. KEY COMPARISON: Measurement of activity concentration of radionuclide Cs-137 in a solution (COOMET Project no 386/RU/06)

    NASA Astrophysics Data System (ADS)

    Kharitonov, I. A.; Zanevsky, A. V.; Milevski, V.; Ivaniukovich, A.; Oropesa Verdecia, P.; Moreno León, Y.; Svec, A.

    2008-01-01

    A COOMET.RI(II)-K2.Cs-137 comparison of the measurement of a standardized solution of Cs-137 has enabled three national metrology institutes in the COOMET to demonstrate their traceability to the SI. The results of the comparison will be used to evaluate degrees of equivalence for these institutes through the measurements of the linking laboratory in the key comparison BIPM.RI(II)-K1.Cs-137. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI Section II, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  20. SUPPLEMENTARY COMPARISON: Final report on COOMET.RI(II)-S2.Eu-152 (319/RU/04): Comparison measurements of radionuclide volume sources (Eu-152)

    NASA Astrophysics Data System (ADS)

    Korostin, S.; Hernandez, T.; Oropesa, P.; Arnold, D.; Evseev, V.; Ivanukovich, A.; Milevskiy, V.; Svec, A.; Lapenas, A.; Andonova, V.; Steiner, V.

    2010-01-01

    Measurements of the Eu-152 specific activity in an artificial volume sample of water density were performed in nine laboratories with the HPGe spectrometry technique. Analysis of the gamma radiation absorption in the sample material confirmed Compton scattering as the main mechanism of interaction of photons with energy between 300-600 keV and 779-1408 keV in the most important substances for environmental monitoring (food, water, biological materials, soils). A list of CMCs supported by the comparison is suggested in the report. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by COOMET, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  1. Final report on COOMET.RI(II)-K2.Eu-152: Measurement of activity concentration of radionuclide Eu-152 in a solution (COOMET project no 423/RU/08)

    NASA Astrophysics Data System (ADS)

    Kharitonov, I. A.; Zanevsky, A. V.; Milevski, V.; Ivaniukovich, A.; Oropesa Verdecia, P.; Moreno León, Y.; Švec, A.

    2013-01-01

    The COOMET.RI(II)-K2.Eu-152 comparison of measurements of a standardized solution of Eu-152 has enabled the demonstration of the traceability to the SI of the national measurement standards of three national metrology institutes of the COOMET countries: BelGIM, CENTIS-DMR and SMU. The pilot laboratory is the D I Mendeleyev Institute for Metrology (VNIIM), which participated in the BIPM.RI(II)-K1.Eu-152 key comparison and will provide the link to evaluate the degrees of equivalence for these institutes. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  2. KEY COMPARISON: BIPM comparison BIPM.RI(II)-K1.Cu-64 of the activity measurements of the radionuclide 64Cu

    NASA Astrophysics Data System (ADS)

    Michotte, C.; Courte, S.; Ratel, G.; Kossert, K.; Nähle, O. J.

    2009-01-01

    In 2009, the Physikalisch-Technische Bundesanstalt (PTB), Germany, submitted a sample of known activity of 64Cu to the International Reference System (SIR) for activity comparison at the Bureau International des Poids et Mesures (BIPM). The value of the activity submitted was about 9.3 MBq. The result of this new comparison has been approved for publication by Section II of the Consultative Committee for Ionizing Radiation (CCRI(II)), comparison identifier BIPM.RI(II)-K1.Cu-64. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI Section II, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  3. A rat model for the treatment of melanoma metastatic to the brain by means of neutron capture therapy

    SciTech Connect

    Matalka, K.Z.; Bailey, M.Q.; Barth, R.F.; Staubus, A.E.; Adams, D.M.; Soloway, A.H.; James, S.M.; Goodman, J.H. ); Coderre, J.A.; Fairchild, R.G. ); Rofstad, E.K. )

    1991-01-01

    Melanoma metastatic to the brain is a serious clinical problem for which there currently is no satisfactory treatment. Boron neutron capture therapy (BNCT) has been shown by Mishima et al. to be clinically effective in the treatment of cutaneous melanoma using {sup 10}B-enriched boronophenylalaine (BPA) as the capture agent. In the present pilot study we have observed a significant prolongation in survival time of nude rats bearing intracerebral implants of the human melanoma cell line MRA 27 following administration of BPA and neutron irradiation. These findings suggest therapeutic efficacy, but unequivocal proof depends upon confirmation in a more definitive experiment using large numbers of animals with both solitary and multiple implants of melanoma. If our preliminary results are confirmed, then this will lay the groundwork for a clinical study of BNCT for the treatment of melanoma metastatic to the brain. 7 refs., 2 figs., 2 tabs.

  4. Key comparison BIPM.RI(I)-K3 of the air-kerma standards of the NRC, Canada and the BIPM in medium-energy x-rays

    NASA Astrophysics Data System (ADS)

    Burns, D. T.; Kessler, C.; Mainegra-Hing, E.; Shen, H.; McEwen, M. R.

    2016-01-01

    A key comparison has been made between the air-kerma standards of the NRC, Canada and the BIPM in the medium-energy x-ray range. The results show the standards to be in agreement at the level of the standard uncertainty of the comparison of 3.3 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  5. Noise in waveguide between 18 GHz and 26.5 GHz

    NASA Astrophysics Data System (ADS)

    Allal, D.

    2016-01-01

    This report summarises the results of the Key Comparison CCEM.RF-K22.W on noise temperature, performed between October 2007 and February 2011. In this comparison, the available noise temperature of three noise sources was determined by six National Metrology Institutes (NMIs) in the frequency range from 18 GHz to 26.5 GHz. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  6. Report on APMP key comparison: calibration of angle standards

    NASA Astrophysics Data System (ADS)

    Kang, C.-S.; Kruger, O. A.; Cox, P.; Xue, Z.; Liou, P.; Wong, S. Y.; Chaudhary, K. P.; Alfiyati, N.; Watanabe, T.; Eom, T.; Halim, R. M.; Tan, S. L.; Tonmueanwai, A.; Dibo, M.

    2016-01-01

    A regional key comparison, APMP.L-K3 (calibration of angle standards) was held in 2005. Thirteen National Metrology Institutes (NMISA, NMIA, KRISS, NMIJ/ AIST, NMC/ A*STAR, NIMT, SCL, CMS/ ITRI, NPLI, RCM- LIPI, NIM, and NSCL) have participated in this comparison and the measurements were carried out during the period from April 2005 to December 2007. This report describes the measurement results of a 12-sided optical polygon with nominal angles of 30°, and four angle blocks with nominal angles of 5 arc seconds, 5 minutes, 30 minutes and 5 degrees, respectively. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCL, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  7. Key comparison BIPM.RI(I)-K3 of the air-kerma standards of the NMIJ, Japan and the BIPM in medium-energy x-rays

    NASA Astrophysics Data System (ADS)

    Burns, D. T.; Kessler, C.; Tanaka, T.; Kurosawa, T.; Saito, N.

    2016-01-01

    A key comparison has been made between the air-kerma standards of the NMIJ, Japan and the BIPM in the medium-energy x-ray range. The results show the standards to be in agreement at the level of the standard uncertainty of the comparison of 3.1 parts in 103. A trend is evident in the results for the different radiation qualities. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  8. Final report. SIM comparison in mass standards SIM.M.M-K5

    NASA Astrophysics Data System (ADS)

    Becerra, L. O.; Peña, L. M.; Luján, L.; Díaz, J. C.; Centeno, L. M.; Loayza, V.; Cacais, F.; Ramos, O.; Rodriguez, S.; Garcia, Fr; Garcia, Fe; Leyton, F.; Santo, C.; Caceres, J.; Kornblit, F.; Leiblich, J.; Jacques, C.

    2016-01-01

    This report summarizes the results of a SIM comparison in masss carried out between 7 NMIs. Five mass standards with nominal values 2 kg, 200 g, 50 g, 1 g and 200 mg have been circulated by the NMIs. The results reported by the participants are consistent with each other and with the key comparison reference valu of the comparison CCM.M-K5 to which the present comparison has been linked. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  9. Key comparison BIPM.RI(I)-K2 of the air-kerma standards of the CMI, Czech Republic and the BIPM in low-energy x-rays

    NASA Astrophysics Data System (ADS)

    Burns, D. T.; Kessler, C.; Sochor, V.

    2016-01-01

    A key comparison has been made between the air-kerma standards of the CMI, Czech Republic and the BIPM in the low-energy x-ray range. The results show the standards to be in agreement at around the level of the standard uncertainty of the comparison of 3.5 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  10. Key comparison BIPM.RI(I)-K7 of the air-kerma standards of the CMI, Czech Republic and the BIPM in mammography x-rays

    NASA Astrophysics Data System (ADS)

    Kessler, C.; Burns, D.; Roger, P.; Sochor, V.

    2016-01-01

    A first key comparison has been made between the air-kerma standards of the CMI, Czech Republic and the BIPM in mammography x-ray beams. The results show the standards to be in agreement at the level of the standard uncertainty for the comparison of 3.5 parts in 103. The results for an indirect comparison made at the same time are consistent with the direct results at the level of 1 part in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  11. Key comparison BIPM.RI(I)-K1 of the air-kerma standards of the NIM, China and the BIPM in 60Co gamma radiation

    NASA Astrophysics Data System (ADS)

    Kessler, C.; Burns, D.; Wang, K.; Fan, Y.; Jin, S.; Yang, X.

    2016-01-01

    An indirect comparison of the standards for air kerma of the National Institute of Metrology (NIM), China and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in November 2015. The comparison result, evaluated as a ratio of the NIM and the BIPM standards for air kerma, is 0.9997 with a combined standard uncertainty of 2.7 × 10-3. The results are analysed and presented in terms of degrees of equivalence for entry in the BIPM key comparison database. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  12. Final report, on-going key comparison BIPM.QM-K1: ozone at ambient level, comparison with DMDM, July 2015

    NASA Astrophysics Data System (ADS)

    Viallon, J.; Moussay, P.; Wielgosz, R.; Bebic, J.; Norris, J. E.; Guenther, F.

    2016-01-01

    As part of the on-going key comparison BIPM.QM-K1, a comparison has been performed between the ozone national standard of the Directorate of Measures and Precious Metals (DMDM) and the common reference standard of the key comparison, maintained by the Bureau International des Poids et Mesures (BIPM), via a transfer standard maintained by the National Institute of Standards and Technology (NIST). The instruments have been compared over a nominal ozone amount-of-substance fraction range of 0 nmol/mol to 500 nmol/mol Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  13. Final Report. Supplementary comparison of 50/60 Hz energy SIM.EM-S7

    NASA Astrophysics Data System (ADS)

    Carranza, R.; Campos, S.; Castruita, A.; Nelson, T.; Ribeiro, A. M.; So, E.; Spaggiari, A.; Slomovitz, D.; Izquierdo, D.; Postigo, H.; Díaz, H.; Sanchez, H.; Gonzalez, J.; Ramos, R.; Zipaquira, A.

    2016-01-01

    From 2010 to 2012, a key comparison of energy standards at 50/60 Hz was conducted in the SIM region. The comparison included measurements of active and reactive energy at three frequencies, aiming at providing support to high accuracy measurement needs of reactive energy. This work presents the results of the SIM.EM-S7 supplementary comparison. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  14. Fibrolamellar Hepatocellular Carcinoma: a Case Report with Distinct Radiological Features

    PubMed Central

    Haritanti, Afrodite; Economou, Ipoliti

    2010-01-01

    Introduction We report a rare case of a 23-year-old male who presented with abdominal discomfort for 15 days. An ultrasound was performed which showed a hypoechoic, heterogenous mass in the left lobe of the liver and distended portal vein, followed by further investigation with computed tomography (CT), MRI, and MRA. Serum alpha-fetoprotein was not elevated and hepatitis B antigen was negative. Methods CT scan depicted a nodular mass in left liver lobe with occlusion of both the central part and the two main branches of intrahepatic portal vein. Result Biopsy of the liver mass led to a diagnosis of fibrolamellar hepatocellular carcinoma. Conclusion Fibrolamellar carcinoma is an uncommon variant of hepatocellular carcinoma. The diagnosis is suggested by radiographic studies and is confirmed by histological examination. PMID:19960280

  15. Bilateral comparison report (APMP.L-K11.1) carried out between KRISS and VMI in November 2007

    NASA Astrophysics Data System (ADS)

    Suh, Hosuhng; Lee, Won-Kyu; Thu, Bui Quoc; Thang, Le Huu

    2012-01-01

    The laser from the Vietnam metrological institute (VMI) was brought to the Korea Research Institute of Standards and Science (KRISS) in November 2007 in the framework of the APMP.L-K11.1 bilateral key comparison. The absolute frequency of the f component of the R(127) 11-5 transition was measured for this laser and KRISS's laser following the protocol for key comparison BIPM.L-K11. The results of these measurements are compiled in the present report. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCL, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  16. Results of the EURAMET.RI(II)-S6.I-129 supplementary comparison

    NASA Astrophysics Data System (ADS)

    García-Toraño, Eduardo; Altzitzoglou, Timotheos; Auerbach, Pavel; Bé, Marie-Martine; Lourenço, Valérie; Bobin, Christophe; Cassette, Philippe; Dersch, Rainer; Kossert, Karsten; Nähle, Ole; Peyrés, Virginia; Pommé, Stefaan; Rozkov, Andrej; Sanchez-Cabezudo, Anabel; Sochoro&vacute; , Jana

    2015-01-01

    An international comparison of the long-lived gamma-ray emitter 129I has been recently completed. A total of 5 laboratories measured a solution prepared by Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT). Aliquots of the master solution were standardized in terms of activity per mass unit by participant laboratories using 4 different techniques. The results of the comparison can be used as the basis for establishing the equivalence among the laboratories. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  17. KEY COMPARISON Comparison of the standards of air kerma of the ENEA-INMRI and the BIPM for 137Cs gamma rays

    NASA Astrophysics Data System (ADS)

    Allisy-Roberts, P. J.; Kessler, C.; Toni, M.; Bovi, M.

    2010-01-01

    A comparison of the standards of air kerma of the Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti of the Ente per le Nuove Tecnologie, l'Energia e l'Ambiente, Italy (ENEA-INMRI) and of the Bureau International des Poids et Mesures (BIPM) was carried out in 137Cs radiation in 1998. The comparison result, updated for changes in the standards in 2003 and 2009, is 0.9927 (0.0067) and demonstrates that the ENEA-INMRI and BIPM standards are in agreement within the uncertainties. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI Section I, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  18. Reconstructing cerebrovascular networks under local physiological constraints by integer programming.

    PubMed

    Rempfler, Markus; Schneider, Matthias; Ielacqua, Giovanna D; Xiao, Xianghui; Stock, Stuart R; Klohs, Jan; Székely, Gábor; Andres, Bjoern; Menze, Bjoern H

    2015-10-01

    We introduce a probabilistic approach to vessel network extraction that enforces physiological constraints on the vessel structure. The method accounts for both image evidence and geometric relationships between vessels by solving an integer program, which is shown to yield the maximum a posteriori (MAP) estimate to a probabilistic model. Starting from an overconnected network, it is pruning vessel stumps and spurious connections by evaluating the local geometry and the global connectivity of the graph. We utilize a high-resolution micro computed tomography (μCT) dataset of a cerebrovascular corrosion cast to obtain a reference network and learn the prior distributions of our probabilistic model and we perform experiments on in-vivo magnetic resonance microangiography (μMRA) images of mouse brains. We finally discuss properties of the networks obtained under different tracking and pruning approaches.

  19. Key comparison BIPM.RI(I)-K5 of the air kerma standards of the NIM, China, and the BIPM in 137Cs gamma radiation

    NASA Astrophysics Data System (ADS)

    Kessler, C.; Burns, D. T.; Li, D.; Wang, P.

    2015-01-01

    A direct comparison of the standards for air kerma of the National Institute of Metrology (NIM), Beijing, China, and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 137Cs radiation beam of the BIPM in September 2014. The comparison result, evaluated as a ratio of the NIM and the BIPM standards for air kerma, is 0.9967 with a combined standard uncertainty of 2.1 × 10-3. The results are analysed and presented in terms of degrees of equivalence for entry in the BIPM key comparison database. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  20. Carotid body tumors: advantages of contrast ultrasound investigation.

    PubMed

    Giannoni, Maria F; Irace, Luigi; Vicenzini, Edoardo; Massa, Rita; Gossetti, Bruno; Benedetti-Valentini, Fabrizio

    2009-10-01

    Carotid body tumors are rare neoplasms that have to be considered in the evaluation of all lateral neck mass. Early surgical removal has been recommended to avoid possible cranial nerve injury, the most common perioperative complication. Computed tomography (CT) and magnetic resonance imaging (MRA) angiographies are the preferred pre-operative diagnostic imaging investigations, as well as the 111 In-pentetreotide scintigraphic scan, whereas the standard ultrasound investigations have poor sensitivity in characterizing of the blood flows of the parenchimal structure of the carotid body tumors. We describe a case of a patient with a carotid body tumor assessed with contrast ultrasonography that clearly improved the quality of the standard color Duplex. This technique may represent a non-invasive method, easy to use and to repeat, and able to achieve high diagnostic accuracy.

  1. Horner's Syndrome due to a Spontaneous Internal Carotid Artery Dissection after Deep Sea Scuba Diving.

    PubMed

    Alonso Formento, Jose Enrique; Fernández Reyes, Jose Luis; Envid Lázaro, Blanca Mar; Fernández Letamendi, Teresa; Yeste Martín, Ryth; Jódar Morente, Francisco José

    2016-01-01

    Internal carotid artery dissection (ICAD) is a rare entity that either results from traumatic injury or can be spontaneously preceded or not by a minor trauma such as sporting activities. It represents a major cause of stroke in young patients. The diagnosis should be suspected with the combination of Horner's syndrome, headache or neck pain, and retinal or cerebral ischaemia. The confirmation is frequently made with a magnetic resonance angiography (MRA). Although anticoagulation with heparin followed by vitamin-K-antagonists is the most common treatment, there is no difference in efficacy of antiplatelet and anticoagulant drugs at preventing stroke and death in patients with symptomatic carotid dissection. We describe a patient with ICAD following deep sea scuba diving, who presented with Horner's syndrome and neck pain and was successfully treated with anticoagulants.

  2. Using fMR-Adaptation to Track Complex Object Representations in Perirhinal Cortex

    PubMed Central

    Rubin, Rachael D.; Chesney, Samantha; Cohen, Neal J.; Gonsalves, Brian D.

    2013-01-01

    Brain regions in medial temporal lobe have seen a shift in emphasis in their role in long-term declarative memory to an appreciation of their role in cognitive domains beyond declarative memory, such as implicit memory, working memory, and perception. Recent theoretical accounts emphasize the function of perirhinal cortex in terms of its role in the ventral visual stream. Here, we used functional magnetic resonance adaptation (fMRa) to show that brain structures in the visual processing stream can bind item features prior to the involvement of hippocampal binding mechanisms. Evidence for perceptual binding was assessed by comparing BOLD responses between fused objects and variants of the same object as different, non-fused forms (e.g. physically separate objects). Adaptation of the neural response to fused, but not non-fused, objects was in left fusiform cortex and left perirhinal cortex, indicating the involvement of these regions in the perceptual binding of item representations. PMID:23997832

  3. Reversible Cerebral Vasoconstriction Syndrome Presenting With Visual Field Defects.

    PubMed

    Raven, Meisha L; Ringeisen, Alexander L; McAllister, Angela R; Knoch, Daniel W

    2016-06-01

    A 45-year-old woman with a history of depression and anxiety, treated with selective serotonin reuptake inhibitors (SSRIs), experienced acute, recurrent, and severe bifrontal headaches. Over time, she developed a left homonymous hemianopia and mental status changes. MRA revealed segmental vasoconstriction of cerebral arteries in multiple vascular distributions. She was treated with a calcium-channel blocker and magnesium, and there was resolution of her symptoms and cerebrovascular changes. Her clinical course and neuroimaging findings were consistent with reversible cerebral vasoconstriction syndrome. Although rare, this disorder frequently manifests with visual complaints. Although the prognosis is generally favorable, patients with this syndrome require prompt diagnosis and care directed to avoid complications including stroke, seizure, and subarachnoid hemorrhage. PMID:26807800

  4. In search of a corrected prescription drug elasticity estimate: a meta-regression approach.

    PubMed

    Gemmill, Marin C; Costa-Font, Joan; McGuire, Alistair

    2007-06-01

    An understanding of the relationship between cost sharing and drug consumption depends on consistent and unbiased price elasticity estimates. However, there is wide heterogeneity among studies, which constrains the applicability of elasticity estimates for empirical purposes and policy simulation. This paper attempts to provide a corrected measure of the drug price elasticity by employing meta-regression analysis (MRA). The results indicate that the elasticity estimates are significantly different from zero, and the corrected elasticity is -0.209 when the results are made robust to heteroskedasticity and clustering of observations. Elasticity values are higher when the study was published in an economic journal, when the study employed a greater number of observations, and when the study used aggregate data. Elasticity estimates are lower when the institutional setting was a tax-based health insurance system.

  5. KEY COMPARISON: EUROMET Project 666, EUROMET-PR.S1 Final Report: Intercomparison of chromatic dispersion reference fibres

    NASA Astrophysics Data System (ADS)

    Morel, Jacques

    2006-01-01

    The calibration of the chromatic dispersion properties of single-mode fibres is of critical importance for a proper optimization of optical fibre communication systems. Although extensive analyses of the commonly used calibration techniques were already performed by some NMIs, no large scale interlaboratory comparisons that could be used as a basis for the MRA existed at this time. The aim of this project was to perform a comparison of chromatic dispersion measurements that were carried out on four of the most commonly used fibre types, namely G652, G653, G655-TeraLight and G655-Leaf. This intercomparison was also registered as a supplementary comparison (Euromet-PR-S1) and will serve as a basis for the review of the CMC entries on chromatic dispersion. This intercomparison addressed the calibration of the three relevant quantities, namely the chromatic dispersion, the zero dispersion wavelength and the dispersion slope. All laboratories used quite similar equipment, but applied very different measurement strategies and data processing techniques. Very good agreement was found between the results provided by most of the participants. One laboratory obtained results with more significant deviations, probably due to a problem in its measurement setup. The results of this laboratory have been analyzed in this report, but have not been used for the determination of the mean value of the reported quantities. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by EUROMET, according to the provisions of the Mutual Recognition Arrangement (MRA).

  6. Advances in imaging technologies for planning breast reconstruction

    PubMed Central

    Mohan, Anita T.

    2016-01-01

    The role and choice of preoperative imaging for planning in breast reconstruction is still a disputed topic in the reconstructive community, with varying opinion on the necessity, the ideal imaging modality, costs and impact on patient outcomes. Since the advent of perforator flaps their use in microsurgical breast reconstruction has grown. Perforator based flaps afford lower donor morbidity by sparing the underlying muscle provide durable results, superior cosmesis to create a natural looking new breast, and are preferred in the context of radiation therapy. However these surgeries are complex; more technically challenging that implant based reconstruction, and leaves little room for error. The role of imaging in breast reconstruction can assist the surgeon in exploring or confirming flap choices based on donor site characteristics and presence of suitable perforators. Vascular anatomical studies in the lab have provided the surgeon a foundation of knowledge on location and vascular territories of individual perforators to improve our understanding for flap design and safe flap harvest. The creation of a presurgical map in patients can highlight any abnormal or individual anatomical variance to optimize flap design, intraoperative decision-making and execution of flap harvest with greater predictability and efficiency. This article highlights the role and techniques for preoperative planning using the newer technologies that have been adopted in reconstructive clinical practice: computed tomographic angiography (CTA), magnetic resonance angiography (MRA), laser-assisted indocyanine green fluorescence angiography (LA-ICGFA) and dynamic infrared thermography (DIRT). The primary focus of this paper is on the application of CTA and MRA imaging modalities. PMID:27047790

  7. Role of Transcranial Doppler in the Evaluation of Vasculopathy in Tuberculous Meningitis

    PubMed Central

    Tai, Mei-Ling Sharon; Sharma, Vijay K.

    2016-01-01

    Background Vascular complications are important causes of cerebral infarction in tuberculous meningitis (TBM).Transcranial Doppler ultrasonography (TCD) is a non-invasive tool that can provide real-time information about cerebral hemodynamics. However, the literature on the role of TCD in the diagnosis or monitoring of vasculopathy associated with TBM is scarce. We explored the role of TCD in the diagnosis and monitoring of TBM-related vasculopathy of the major intracranial arteries. Methods Consecutive patients with TBM admitted to our tertiary center between 2011 and 2015 were included. All patients underwent TCD evaluation within 2 weeks of hospitalisation and it was repeated 2 weeks later. Mean flow velocity (Vmean) and pulsatility index (PI) were recorded. Flow velocities obtained from the submandibular internal carotid artery were also measured to calculate the Lindegaard ratio. A correlation was made between the patients who demonstrated vasculopathy on TCD, and patients with confirmed focal narrowing on computed tomography angiography (CTA) or magnetic resonance angiography (MRA). The modified Rankin scale (mRS) was used to assess the clinical outcome at three and six months. Results A total of 36 patients were recruited. Focally elevated flow velocities in the middle cerebral artery (MCA) were observed in 11 (30.6%) patients, bilaterally in 6 of them. The Lindegaard ratio was elevated (>3) in 10 (90.9%) of them, which occurred as early as the fourth day of hospitalization and persisted as long as four months. Eighty percent of patients with TBM vasculopathy by TCD criteria, also had narrowing on CTA or MRA. Ten patients (27.8%) achieved good outcome (mRS 0–2) at 3 months, which increased to 13 (36.1%) at 6 months. Conclusion A considerable proportion of patients with TBM develops intracranial vasculopathy, which can be reliably diagnosed and monitored using TCD. PMID:27723828

  8. Measurement of gauge blocks by interferometry

    NASA Astrophysics Data System (ADS)

    Matus, M.; Haas, S.; Piree, H.; Gavalyugov, V.; Tamakyarska, D.; Thalmann, R.; Balling, P.; Garnaes, J.; Hald, J.; Farid, N.; Prieto, E.; Lassila, A.; Salgado, J. A.; Lewis, A.; Bandis, C.; Mudronja, V.; Banreti, E.; Balsamo, A.; Pedone, P.; Bergmans, R. H.; Karlsson, H.; Ramotowski, Z.; Eusebio, L.; Saraiva, F.; Duta, A.; Zelenika, S.; Bergstrand, S.; Fira, R.; Yandayan, T.; Sendogdu, D.; Ganioglu, O.; Asli Akgoz, S.; Franke, P.

    2016-01-01

    The key comparison EURAMET.L-K1.2011 on gauge blocks was carried out in the framework of a EURAMET project starting in 2012 and ending in 2015. It involved the participation of 24 National Metrology Institutes from Europe and Egypt, respectively. 38 gauge blocks of steel and ceramic with nominal central lengths between 0.5 mm and 500 mm were circulated. The comparison was conducted in two loops with two sets of artifacts. A statistical technique for linking the reference values was applied. As a consequence the reference value of one loop is influenced by the measurements of the other loop although they did not even see the artifacts of the others. This influence comes solely from three "linking laboratories" which measure both sets of artifacts. In total there were 44 results were not fully consistent with the reference values. This represents 10% of the full set of 420 results which is a considerable high number. At least 12 of them are clearly outliers where the participants have been informed by the pilot as soon as possible. The comparison results help to support the calibration and measurement capabilities (CMCs) of the laboratories involved in the CIPM MRA. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCL, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  9. 'NC100150', a preparation of iron oxide nanoparticles ideal for positive-contrast MR angiography.

    PubMed

    Kellar, K E; Fujii, D K; Gunther, W H; Briley-Saebø, K; Spiller, M; Koenig, S H

    1999-08-01

    A laboratory-scale synthesis of NC100150 (iron oxide particles with an oxidized starch coating) was characterized by magnetization measurements (vibrating sample magnetometry, VSM), relaxometry (1/T1 NMRD profiles and 1/T2 at 10 and 20 MHz), and dynamic light scattering (photon correlation spectroscopy, PCS). The results were related to give a self-consistent physical description of the particles: a water-impenetrable part making up 12% of the total particle volume, 82% of this volume consisting of an iron oxide core and the remaining 18% consisting of an oxidized starch rind; and, a water-penetrable part making up 88% of the total particle volume, consisting of oxidized starch polymers and entrained water molecules. Relating the magnetization to the relaxometry results required that the oxidized starch coating slows the diffusivity of solvent water molecules in the vicinity of the iron oxide cores. The effect of the organic coating on water diffusivity, not previously considered in the application of relaxation theory to iron oxide nanoparticles, is supported by the much greater (factor of about 2) diameter obtained from the dynamic light scattering measurements in comparison to that obtained from the magnetization measurements. The present work shows that three physical techniques--VSM, relaxometry, and PCS--are needed for properly assessing iron oxide nanoparticles for use as contrast agents for magnetic resonance angiography (MRA). It is also shown that NC100150 has a narrow range of diameters and the smallest value of r2/r1 reported to date, an asset for MRA. PMID:10504049

  10. Multiresolution quantum chemistry in multiwavelet bases: excited states from time-dependent Hartree–Fock and density functional theory via linear response

    DOE PAGES

    Yanai, Takeshi; Fann, George I.; Beylkin, Gregory; Harrison, Robert J.

    2015-02-25

    Using the fully numerical method for time-dependent Hartree–Fock and density functional theory (TD-HF/DFT) with the Tamm–Dancoff (TD) approximation we use a multiresolution analysis (MRA) approach to present our findings. From a reformulation with effective use of the density matrix operator, we obtain a general form of the HF/DFT linear response equation in the first quantization formalism. It can be readily rewritten as an integral equation with the bound-state Helmholtz (BSH) kernel for the Green's function. The MRA implementation of the resultant equation permits excited state calculations without virtual orbitals. Moreover, the integral equation is efficiently and adaptively solved using amore » numerical multiresolution solver with multiwavelet bases. Our implementation of the TD-HF/DFT methods is applied for calculating the excitation energies of H2, Be, N2, H2O, and C2H4 molecules. The numerical errors of the calculated excitation energies converge in proportion to the residuals of the equation in the molecular orbitals and response functions. The energies of the excited states at a variety of length scales ranging from short-range valence excitations to long-range Rydberg-type ones are consistently accurate. It is shown that the multiresolution calculations yield the correct exponential asymptotic tails for the response functions, whereas those computed with Gaussian basis functions are too diffuse or decay too rapidly. Finally, we introduce a simple asymptotic correction to the local spin-density approximation (LSDA) so that in the TDDFT calculations, the excited states are correctly bound.« less

  11. Contrast-enhanced CT- and MRI-based perfusion assessment for pulmonary diseases: basics and clinical applications

    PubMed Central

    Ohno, Yoshiharu; Koyama, Hisanobu; Lee, Ho Yun; Miura, Sachiko; Yoshikawa, Takeshi; Sugimura, Kazuro

    2016-01-01

    Assessment of regional pulmonary perfusion as well as nodule and tumor perfusions in various pulmonary diseases are currently performed by means of nuclear medicine studies requiring radioactive macroaggregates, dual-energy computed tomography (CT), and dynamic first-pass contrast-enhanced perfusion CT techniques and unenhanced and dynamic first-pass contrast enhanced perfusion magnetic resonance imaging (MRI), as well as time-resolved three-dimensional or four-dimensional contrast-enhanced magnetic resonance angiography (MRA). Perfusion scintigraphy, single-photon emission tomography (SPECT) and SPECT fused with CT have been established as clinically available scintigraphic methods; however, they are limited by perfusion information with poor spatial resolution and other shortcomings. Although positron emission tomography with 15O water can measure absolute pulmonary perfusion, it requires a cyclotron for generation of a tracer with an extremely short half-life (2 min), and can only be performed for academic purposes. Therefore, clinicians are concentrating their efforts on the application of CT-based and MRI-based quantitative and qualitative perfusion assessment to various pulmonary diseases. This review article covers 1) the basics of dual-energy CT and dynamic first-pass contrast-enhanced perfusion CT techniques, 2) the basics of time-resolved contrast-enhanced MRA and dynamic first-pass contrast-enhanced perfusion MRI, and 3) clinical applications of contrast-enhanced CT- and MRI-based perfusion assessment for patients with pulmonary nodule, lung cancer, and pulmonary vascular diseases. We believe that these new techniques can be useful in routine clinical practice for not only thoracic oncology patients, but also patients with different pulmonary vascular diseases. PMID:27523813

  12. Compensatory intracranial arterial dilatation in extracranial carotid atherosclerosis: the Northern Manhattan Study

    PubMed Central

    Gutierrez, Jose; Elkind, Mitchell S. V.; Gomez-Schneider, Maia; DeRosa, Janet T.; Cheung, Ken; Bagci, Ahmet; Alperin, Noam; Sacco, Ralph L.; Wright, Clinton B.; Rundek, Tatjana

    2015-01-01

    Background There is a scarcity of data supporting the association between atherosclerosis and dolichoectasia (DE) in unbiased samples. Aims To test the hypothesis that the association between DE and extracranial carotid atherosclerosis depends on the degree of collateral circulation. Methods The Northern Manhattan Study MRI substudy consists of 1290 participants who remained stroke-free at the time of MRI. Arterial diameters were collected in all participants with available MRA. Dolichoectasia was defined as a head-size adjusted diameter > 2 SD for each artery. Carotid Doppler was used to evaluate for carotid atherosclerosis (carotid plaque, maximum plaque thickness [MCPT] and intima media thickness [cIMT]). Results We included 994 participants with available Doppler and MRA data (mean age 63 years, 60% female). Any DE was reported in 16% of participants, 54% had at least one carotid plaque and the mean cIMT was 0.92 ± 0.09 mm. After adjusting for demographic and clinical characteristics, there was no association between markers of carotid atherosclerosis and DE. However, stratifying by collaterals, it was observed that DE was more likely in the anterior and posterior circulations when collaterals were available among participants with carotid atherosclerosis. These associations were confirmed by noting an increment in arterial diameters in the corresponding arteries ipsilateral and contralateral to each carotid as well as in the posterior circulation. Conclusions We did not find an association of extracranial carotid atherosclerosis with DE. However, we found that DE is more frequent when intracranial collaterals are available suggesting a compensatory process that needs further investigation. PMID:25753026

  13. Influence of Diet and Postmortem Ageing on Oxidative Stability of Lipids, Myoglobin and Myofibrillar Proteins and Quality Attributes of Gluteus Medius Muscle in Goats.

    PubMed

    Adeyemi, Kazeem Dauda; Shittu, Rafiat Morolayo; Sabow, Azad Behnan; Ebrahimi, Mahdi; Sazili, Awis Qurni

    2016-01-01

    This study appraised the effects of dietary blend of 80% canola oil and 20% palm oil and postmortem ageing on oxidative stability, fatty acids and quality attributes of gluteus medius (GM) muscle in goats. Twenty-four Boer bucks were randomly allotted to diet supplemented with 0, 4 and 8% oil blend, fed for 100 days and slaughtered, and the GM muscle was subjected to a 7 d chill storage (4±1°C). Diet had no effect (P> 0.05) on the colour, drip loss, thiobarbituric acid-reactive substances (TBARS) value, free thiol, carbonyl, myoglobin and metmyoglobin contents, metmyoglobin reducing activity (MRA), antioxidant enzyme activities and abundance of myosin heavy chain (MHC) and actin in the GM muscle in goats. The meat from goats fed 4 and 8% oil blend had higher (P< 0.05) concentration of α and γ-tocopherol and abundance of troponin T compared with that from the control goats. The GM muscle from the oil-supplemented goats had lower (P< 0.05) concentration of C16:0 and greater (P< 0.05) concentration of C18:1n-9, C18:3n-3 and C20:5n-3 compared with that from the control goats. Nonetheless, diet did not affect (P< 0.05) the total fatty acid in the GM muscle in goats. Regardless of the diet, the free thiol and myoglobin contents, concentration of tocopherol and total carotenoids, MHC and MRA in the GM muscle decreased (P< 0.05) while carbonyl content, TBARS, drip loss and metmyoglobin content increased over storage. Dietary blend of 80% canola oil and 20% palm oil beneficially altered tissue lipids without hampering the oxidative stability of chevon. PMID:27138001

  14. Machine Learning in Ionospheric Phenomena Detection Using Passive Radar

    NASA Astrophysics Data System (ADS)

    Pankratius, V.; Barari, S.; Lind, F. D.

    2015-12-01

    This work describes an approach to automate ionospheric feature detection in passive radar data using a tunable pipeline of Python-implemented algorithms for detection and classification. In particular, our detector is tuned to capture E-region irregularities and various other events such as meteors, aircraft, and ambiguities that result from poor transmission of signals or noise interference. The detection stage applies to passive radar images with pixels normalized to a defined value range. To separate the background, we apply a thresholding value and an area cuttoff to keep regions with connected pixels of a minimum size; for each particular image, these parameters can be determined algorithmically in two ways through our ExplainedEntropy (EE) and MaximumRegionArea (MRA) techniques. EE identifies the smallest set of regions that explain the most entropy of the image. MRA sets the area threshold to be a function of the largest region size. The classification stage picks up on these detected areas and applies neural networks and random forests to the image feature space. This way we are able categorize images based on their scientific content and make them searchable for scientists. A training set of real radar images was available to evaluate our approach and its adaptivity. Based on these labeled real images, we also evaluated the robustness of the detection with enhanced set of perturbed images that were generated through a model-based simulator. The simulator also allowed for controlled experiments in the amount of perturbation and noise added, to precisely characterize the operation ranges of our machine learning algorithms. We will discuss the performance of the algorithms and potential scientific applications. Acknowledgements. We would like to acknowledge support from the NSF ACI-1442997 (PI V. Pankratius).

  15. Intracranial stenosis, cerebrovascular diseases, and cognitive impairment in chinese.

    PubMed

    Hilal, Saima; Saini, Monica; Tan, Chuen Seng; Catindig, Joseree A; Dong, Yan Hong; Holandez, Rachelle L; Niessen, Wiro J; Vrooman, Henri A; Ting, Eric; Wong, Tien Yin; Chen, Christopher; Venketasubramanian, Narayanaswamy; Ikram, Mohammad K

    2015-01-01

    Extracranial carotid artery disease has been shown to be related to cognitive deficits. However, limited data are available on intracranial stenosis (ICS) and cognitive impairment. We investigate the association between ICS and cognitive impairment in Chinese. Subjects (n=278), recruited from the Epidemiology of Dementia in Singapore Study, underwent comprehensive clinical evaluation, neuropsychological testing, and brain magnetic resonance imaging (MRI), including 3-dimensional-time-of-flight magnetic resonance angiography (MRA). Cognitive function was expressed as composite and domain-specific Z-scores. Cognitive impairment no dementia and dementia were diagnosed according to internationally accepted diagnostic criteria. Linear and logistic regression models were adjusted for age, sex, education, vascular risk factors, and other MRI markers. A total of 29 (10.4%) persons had ICS on MRA, which was significantly associated with both composite cognitive Z-scores [mean difference in Z-score, presence vs. absence of ICS: -0.37 (95% confidence interval: -0.63, -0.12)] and specific domains including executive function, language, visuomotor speed, verbal memory, and visual memory. ICS was also related to significant cognitive impairment (odds ratio: 5.10 [1.24 to 21.02]). With respect to other MRI markers, adjusted for the presence of lacunar infarcts, the associations of ICS with both composite and domain-specific Z-scores, and significant cognitive impairment became nonsignificant; however, adjustment for other MRI markers did not alter these associations. In this Chinese population, presence of ICS was associated with cognitive impairment independent of vascular risk factors. These associations may be mediated through the presence of infarcts.

  16. Graft Patency in Long-term Survivors after Renovisceral Debranching with VORTEC

    SciTech Connect

    Winklehner, Anna Nguyen-Kim, Thi Dan Linh Pfammatter, Thomas; Rancic, Zoran Mayer, Dieter Lachat, Mario; Frauenfelder, Thomas

    2015-06-15

    PurposeThis study was designed to evaluate retrospectively the long-term stent-graft patency after renovisceral revascularization with Viabahn Open Revascularization Technique (VORTEC) using computed tomography angiography (CTA) and magnetic resonance angiography (MRA).MethodsIn 34 patients (seven women; mean age 72 ± 8 years) with aortic aneurysm, 63 renovisceral vessels (i.e., 54 renal, nine visceral arteries) were revascularized with VORTEC between 2004 and 2009. All patients obtained a pre- and postinterventional CTA and at least one follow-up CTA or MRA after 6 or more months following intervention (median follow up: 43 months). Detection of bypass occlusion, bypass stenosis, infolding, stent-graft fractures and dislocations, and kidney shrinkage were noted by two readers in consensus. Furthermore, mortality during follow-up was assessed using the medical report.ResultsDuring follow-up, 12.6 % of stent-grafts occluded. Cumulative patency rate was 95.2 ± 2.7 % at 12 months, 87.7 ± 4.4 % at 24 and 36 months, and 84.7 ± 5.2 % at 48, 60, 72, 84, and 89 months, respectively. Overall, 19 % of stent-grafts (12/63) developed bypass stenosis (<50 %, 10 stent-grafts; > 50 %, 2 stent-grafts), in one case stenosis (>70 %) was suspected to be hemodynamically significant. No secondary dislocation, no infolding of renovisceral stent-grafts, and no stent-graft fracture occurred. Kidney shrinkage occurred in nine patients, primarily in patients with an occluded Viabahn (n = 7). Eleven patients (32.3 %) died within the follow-up time period.ConclusionsIn long-term survivors after VORTEC cumulative patency rate remained high, and no stent-graft fractures or secondary dislocations occurred.

  17. Stretch-dependent changes in surface profiles of the human crystalline lens during accommodation: A finite element study

    PubMed Central

    Pour, Hooman Mohammad; Kanapathipillai, Sangarapillai; Zarrabi, Khosrow; Manns, Fabrice; Ho, Arthur

    2015-01-01

    Background A nonlinear isotropic finite element (FE) model of a 29 year old human crystalline lens was constructed to study the effects of various geometrical parameters on lens accommodation. Methods The model simulates dis-accommodation by stretching of the lens and predicts the change in the lens capsule, cortex and nucleus surface profiles at select states of stretching/accommodation. Multiple regression analysis (MRA) is used to develop a stretch-dependent mathematical model relating the lens sagittal height to the radial position of the lens surface as a function of dis-accommodative stretch. A load analysis is performed to compare the FE results to empirical results from lens stretcher studies. Using the predicted geometrical changes, the optical response of the whole eye during accommodation was analysed by ray-tracing. Results Aspects of lens shape change relative to stretch were evaluated including change in diameter (d), central thickness (T) and accommodation (A). Maximum accommodation achieved was 10.29 D. From the MRA, the stretch-dependent mathematical model of the lens shape related lens curvatures as a function of lens ciliary stretch well (maximum mean-square residual error 2.5×10−3 µm, p<0.001). The results are compared with those from in vitro studies. Conclusions The FE and ray-tracing predictions are consistent with EVAS studies in terms of load and power change versus change in thickness. The mathematical stretch-dependent model of accommodation presented may have utility in investigating lens behaviour at states other than the relaxed or fully-accommodated states. PMID:25727940

  18. Atherosclerotic ischemic renal disease. Diagnosis and prevalence in an hypertensive and/or uremic elderly population

    PubMed Central

    Coen, Giorgio; Calabria, Santo; Lai, Silvia; Moscaritolo, Eleonora; Nofroni, Italo; Ronga, Giuseppe; Rossi, Michele; Ventroni, Guido; Sardella, Daniela; Ferrannini, Michele; Zaccaria, Alvaro; Cianci, Rosario

    2003-01-01

    Background Atherosclerotic ischemic renal disease is a frequent cause of end-stage renal failure leading to dialysis among the elderly; Its prevalence is inferred from autopsy or retrospective arteriographic studies. This study has been conducted on 269 subjects over 50 with hypertension and/or CRF, unrelated to other known causes of renal disease. Methods All 269 patients were studied either by color-flow duplex sonography (n = 238) or by renal scintigraphy (n = 224), and 199 of the 269 patients were evaluated using both of these techniques. 40 patients, found to have renal artery stenosis (RAS), were subjected to 3D-contrast enhancement Magnetic Resonance Angiography (MRA) and/or Selective Angiography (SA). An additional 23 cases, negative both to scintigraphy and to ultrasound study, underwent renal angiography (MRA and/or SA). Results Color-duplex sonography, carried out in 238 patients, revealed 49 cases of RAS. MR or SA was carried out in 35 of these 49 patients, and confirmed the diagnosis in 33. Color-duplex sonography showed a PPV value of 94.3% and NPV of 87.0% while renal scintigraphy, carried out in 224 patients, had a PPV of 72.2% and a NPV of 29.4%. Patients with RAS showed a higher degree of renal insufficiency compared to non stenotic patients while there were no differences in proteinuria. RAS, based on color-duplex sonography studies, was present in 11% of patients in the age group 50–59, 18% in the 60–69 and 23% at age 70 and above. Conclusions A relatively large percentage of the elderly population with renal insufficiency and/or hypertension is affected by RAS and is at risk of developing end-stage renal failure. Color-duplex ultrasonography is a valid routine method of investigation of population at risk for renal artery stenosis. PMID:12622875

  19. G-protein βγ subunits in vasorelaxing and anti-endothelinergic effects of calcitonin gene-related peptide

    PubMed Central

    Meens, MJPMT; Mattheij, NJA; van Loenen, PB; Spijkers, LJA; Lemkens, P; Nelissen, J; Compeer, MG; Alewijnse, AE; De Mey, JGR

    2012-01-01

    BACKGROUND AND PURPOSE Calcitonin gene-related peptide (CGRP) has been proposed to relax vascular smooth muscle cells (VSMC) via cAMP and can promote dissociation of endothelin-1 (ET-1) from ETA receptors. The latter is not mimicked by other stimuli of adenylate cyclases. Therefore, we evaluated the involvement of G-protein βγ subunits (Gβγ) in the arterial effects of CGRP receptor stimulation. EXPERIMENTAL APPROACH To test the hypothesis that instead of α subunits of G-proteins (Gαs), Gβγ mediates the effects of CGRP receptor activation, we used (i) rat isolated mesenteric resistance arteries (MRA), (ii) pharmacological modulators of cyclic nucleotides; and (iii) low molecular weight inhibitors of the functions of Gβγ, gallein and M119. To validate these tools with respect to CGRP receptor function, we performed organ bath studies with rat isolated MRA, radioligand binding on membranes from CHO cells expressing human CGRP receptors and cAMP production assays in rat cultured VSMC. KEY RESULTS In isolated arteries contracted with K+ or ET-1, IBMX (PDE inhibitor) increased sodium nitroprusside (SNP)- and isoprenaline (ISO)- but not CGRP-induced relaxations. While fluorescein (negative control) was without effects, gallein increased binding of [125I]-CGRP in the absence and presence of GTPγS. Gallein also increased CGRP-induced cAMP production in VSMC. Despite these stimulating effects, gallein and M119 selectively inhibited the relaxing and anti-endothelinergic effects of CGRP in isolated arteries while not altering contractile responses to K+ or ET-1 or relaxing responses to ISO or SNP. CONCLUSION AND IMPLICATIONS Activated CGRP receptors induce cyclic nucleotide-independent relaxation of VSMC and terminate arterial effects of ET-1 via Gβγ. PMID:22074193

  20. Oral Mineralocorticoid-Receptor Antagonists: Real-Life Experience in Clinical Subtypes of Nonresolving Central Serous Chorioretinopathy With Chronic Epitheliopathy

    PubMed Central

    Daruich, Alejandra; Matet, Alexandre; Dirani, Ali; Gallice, Mathilde; Nicholson, Luke; Sivaprasad, Sobha; Behar-Cohen, Francine

    2016-01-01

    Purpose To evaluate the efficacy and safety of oral mineralocorticoid-receptor antagonist (MRa) therapy in three clinical presentations of nonresolving central serous chorioretinopathy (CSCR) with chronic epitheliopathy. Methods Retrospective case series of consecutive patients with nonresolving CSCR treated with oral eplerenone or spironolactone. Treatment criteria were: persistent CSCR with subretinal fluid (SRF) lasting longer than 4 months; recurrent CSCR with SRF lasting longer than 2 months; persistent CSCR (SRF ≥ 4 months) with fundus autofluorescence gravitational tracks. Outcomes at 1, 3, and 6 months were: foveal SRF height, central macular thickness (CMT), subfoveal choroidal thickness (SFCT), best-corrected visual acuity (BCVA), and occurrence of side effects. Results Among 54 eyes from 42 patients (mean age: 53 years), mean foveal SRF, CMT, and SFCT decreased significantly at 1, 3, and 6 months after treatment initiation. Mean BCVA improved significantly at 6 months. In the subgroup analysis, mean foveal SRF, CMT, and SFCT decreased significantly at 3 and 6 months in the persistent and recurrent groups. In persistent cases with tracks, a significant diminution of mean CMT and SFCT was achieved at 6 months. Treatment-related side effects were observed in 6 patients, prompting treatment discontinuation in one case. Conclusion Response to treatment was observed in the three subgroups. In persistent CSCR with tracks the response was delayed compared with persistent and recurrent cases, suggesting that longer treatment durations would be beneficial in patients with gravitational tracks of RPE alteration. Translational Relevance The clinical response to oral MRa is consistent with the involvement of the mineralocorticoid pathway in CSCR pathogenesis. PMID:26966638

  1. Intraoperative magnetic resonance imaging.

    PubMed

    Hall, Walter A; Truwit, Charles L

    2011-01-01

    Neurosurgeons have become reliant on image-guidance to perform safe and successful surgery both time-efficiently and cost-effectively. Neuronavigation typically involves either rigid (frame-based) or skull-mounted (frameless) stereotactic guidance derived from computed tomography (CT) or magnetic resonance imaging (MRI) that is obtained days or immediately before the planned surgical procedure. These systems do not accommodate for brain shift that is unavoidable once the cranium is opened and cerebrospinal fluid is lost. Intraoperative MRI (ioMRI) systems ranging in strength from 0.12 to 3 Tesla (T) have been developed in part because they afford neurosurgeons the opportunity to accommodate for brain shift during surgery. Other distinct advantages of ioMRI include the excellent soft tissue discrimination, the ability to view the surgical site in three dimensions, and the ability to "see" tumor beyond the surface visualization of the surgeon's eye, either with or without a surgical microscope. The enhanced ability to view the tumor being biopsied or resected allows the surgeon to choose a safe surgical corridor that avoids critical structures, maximizes the extent of the tumor resection, and confirms that an intraoperative hemorrhage has not resulted from surgery. Although all ioMRI systems allow for basic T1- and T2-weighted imaging, only high-field (>1.5 T) MRI systems are capable of MR spectroscopy (MRS), MR angiography (MRA), MR venography (MRV), diffusion-weighted imaging (DWI), and brain activation studies. By identifying vascular structures with MRA and MRV, it may be possible to prevent their inadvertent injury during surgery. Biopsying those areas of elevated phosphocholine on MRS may improve the diagnostic yield for brain biopsy. Mapping out eloquent brain function may influence the surgical path to a tumor being resected or biopsied. The optimal field strength for an ioMRI-guided surgical system and the best configuration for that system are as yet

  2. Influence of Diet and Postmortem Ageing on Oxidative Stability of Lipids, Myoglobin and Myofibrillar Proteins and Quality Attributes of Gluteus Medius Muscle in Goats

    PubMed Central

    Adeyemi, Kazeem Dauda; Shittu, Rafiat Morolayo; Sabow, Azad Behnan; Ebrahimi, Mahdi; Sazili, Awis Qurni

    2016-01-01

    This study appraised the effects of dietary blend of 80% canola oil and 20% palm oil and postmortem ageing on oxidative stability, fatty acids and quality attributes of gluteus medius (GM) muscle in goats. Twenty-four Boer bucks were randomly allotted to diet supplemented with 0, 4 and 8% oil blend, fed for 100 days and slaughtered, and the GM muscle was subjected to a 7 d chill storage (4±1°C). Diet had no effect (P> 0.05) on the colour, drip loss, thiobarbituric acid-reactive substances (TBARS) value, free thiol, carbonyl, myoglobin and metmyoglobin contents, metmyoglobin reducing activity (MRA), antioxidant enzyme activities and abundance of myosin heavy chain (MHC) and actin in the GM muscle in goats. The meat from goats fed 4 and 8% oil blend had higher (P< 0.05) concentration of α and γ-tocopherol and abundance of troponin T compared with that from the control goats. The GM muscle from the oil-supplemented goats had lower (P< 0.05) concentration of C16:0 and greater (P< 0.05) concentration of C18:1n-9, C18:3n-3 and C20:5n-3 compared with that from the control goats. Nonetheless, diet did not affect (P< 0.05) the total fatty acid in the GM muscle in goats. Regardless of the diet, the free thiol and myoglobin contents, concentration of tocopherol and total carotenoids, MHC and MRA in the GM muscle decreased (P< 0.05) while carbonyl content, TBARS, drip loss and metmyoglobin content increased over storage. Dietary blend of 80% canola oil and 20% palm oil beneficially altered tissue lipids without hampering the oxidative stability of chevon. PMID:27138001

  3. Development of in vivo tissue-engineered microvascular grafts with an ultra small diameter of 0.6 mm (MicroBiotubes): acute phase evaluation by optical coherence tomography and magnetic resonance angiography.

    PubMed

    Ishii, Daizo; Enmi, Jun-Ichiro; Moriwaki, Takeshi; Ishibashi-Ueda, Hastue; Kobayashi, Mari; Iwana, Shinichi; Iida, Hidehiro; Satow, Tetsu; Takahashi, Jun C; Kurisu, Kaoru; Nakayama, Yasuhide

    2016-09-01

    Biotubes, i.e., in vivo tissue-engineered connective tubular tissues, are known to be effective as vascular replacement grafts with a diameter greater than several millimeters. However, the performance of biotubes with smaller diameters is less clear. In this study, MicroBiotubes with diameters <1 mm were prepared, and their patency was evaluated noninvasively by optical coherence tomography (OCT) and magnetic resonance angiography (MRA). MicroBiotube molds, containing seven stainless wires (diameter 0.5 mm) covered with silicone tubes (outer diameter 0.6 mm) per mold, were embedded into the dorsal subcutaneous pouches of rats. After 2 months, the molds were harvested with the surrounding capsular tissues to obtain seven MicroBiotubes (internal diameter 0.59 ± 0.015 mm, burst pressure 4190 ± 1117 mmHg). Ten-mm-long MicroBiotubes were allogenically implanted into the femoral arteries of rats by end-to-end anastomosis. Cross-sectional OCT imaging demonstrated the patency of the MicroBiotubes immediately after implantation. In a 1-month follow-up MRA, high patency (83.3 %, n = 6) was observed without stenosis, aneurysmal dilation, or elongation. Native-like vascular structure was reconstructed with completely endothelialized luminal surfaces, mesh-like elastin fiber networks, regular circumferential orientation of collagen fibers, and α-SMA-positive cells. Although the long-term patency of MicroBiotubes still needs to be confirmed, they may be useful as an alternative ultra-small-caliber vascular substitute. PMID:27003431

  4. Advances in imaging technologies for planning breast reconstruction.

    PubMed

    Mohan, Anita T; Saint-Cyr, Michel

    2016-04-01

    The role and choice of preoperative imaging for planning in breast reconstruction is still a disputed topic in the reconstructive community, with varying opinion on the necessity, the ideal imaging modality, costs and impact on patient outcomes. Since the advent of perforator flaps their use in microsurgical breast reconstruction has grown. Perforator based flaps afford lower donor morbidity by sparing the underlying muscle provide durable results, superior cosmesis to create a natural looking new breast, and are preferred in the context of radiation therapy. However these surgeries are complex; more technically challenging that implant based reconstruction, and leaves little room for error. The role of imaging in breast reconstruction can assist the surgeon in exploring or confirming flap choices based on donor site characteristics and presence of suitable perforators. Vascular anatomical studies in the lab have provided the surgeon a foundation of knowledge on location and vascular territories of individual perforators to improve our understanding for flap design and safe flap harvest. The creation of a presurgical map in patients can highlight any abnormal or individual anatomical variance to optimize flap design, intraoperative decision-making and execution of flap harvest with greater predictability and efficiency. This article highlights the role and techniques for preoperative planning using the newer technologies that have been adopted in reconstructive clinical practice: computed tomographic angiography (CTA), magnetic resonance angiography (MRA), laser-assisted indocyanine green fluorescence angiography (LA-ICGFA) and dynamic infrared thermography (DIRT). The primary focus of this paper is on the application of CTA and MRA imaging modalities. PMID:27047790

  5. SP 01-3 ALDOSTERONE ANTAGONISTS IN HEART FAILURE.

    PubMed

    Johnston, Colin

    2016-09-01

    Aldosterone's deleterious pathophysiological effects on the cardiovascular system if blocked by mineralcorticord antagonists (MRAs) logically should lead to improvement in heart function and outcomes in heart failure (HF). The first trial to test this hypothesis was tthe RALES trial in 1999 which treated patients with class III-IV HF with spironolactone. It showed significant reduction in mortality and cardiovascular hospitalzation rates. This was confirmed & extended in EMHASIS-HF RCT with classs II-III being treated with ACEIs & BB who received placebo or elperinone (a MRA) with again a statistically significant fall in mortality & hospitalization.The possible cardioprotective effects of MRA post acute myocardial infarct (MI) is less clear. The EPHESUS RCT in 2003 demostrated that elperinone given 3-14 days AMI in patients with early signs of HF reduced mortality & morbidity. However in the ALBTROSS trial using spironolactone 2 days after AMI showed no benfit in patients without HF but in a subgroup with ST elevation there was a 80% reduction in mortality after 6 months. However a recent meta-analysis from 25 RCT with data invovling 19,333 patients with either HF or post MI assigned aldosterone antagonists (AA)or placebo showed a 18% reduction in mortality including a 20% fall in CV mortality and a 19% reduction in SCD.The role of AA in HFPEF is even even more contraversial. The TOPCAT RCT of 3445 patients with symptomatc HFPEF randomised to spironolactone failed to meet the primary composite end point of death, aborted cardiac arrest or hospitalization although there was a reduction in hospitalization for HF (HR 0.83 P = 0.04).The differences between selective or non-selective MRAs, their ADRs & off target effects will also be discussed. PMID:27643096

  6. Endovascular Repair of Complex Aortic Aneurysms: Intravascular Ultrasound Guidance with an Intracardiac Probe

    SciTech Connect

    Zanchetta, Mario Rigatelli, Gianluca; Pedon, Luigi; Zennaro, Marco; Ronsivalle, Salvatore; Maiolino, Pietro

    2003-09-15

    To assess the accuracy and efficacy of intravascular ultrasound guidance obtained by an intracardiac ultrasound probe during complex aortic endografting. Between November 1999 and July 2002, 19 patients (5 female, 14 male; mean age 73.5 {+-} 2.1 years) underwent endovascular repair of thoracic (n = 10), complex abdominal (n = 6) and concomitant thoraco-abdominal (n = 3) aortic aneurysm. The most suitable size and configuration of the stent-graft were chosen on the basis of preoperative computed tomographic angiography (CTA) or magnetic resonance angiography (MRA). Intraoperative intravascular ultrasound imaging was obtained using a 9 Fr, 9 MHz intracardiac echocardiography (ICE) probe, 110 cm in length, inserted through a 10 Fr precurved long sheath. The endografts were deployed as planned by CTA or MRA. Before stent-graft deployment, the ICE probe allowed us to view the posterior aortic arch and descending thoraco-abdominal aorta without position-related artifacts, and to identify both sites of stent-graft positioning. After stent-graft deployment, the ICE probe allowed us to detect the need for additional modular components to internally reline the aorta in 11 patients, and to discover 2 incomplete graft expansions subsequently treated with adjunctive balloon angioplasty. In 1 patient, the ICE probe supported the decision that the patient was ineligible for the endovascular exclusion procedure. The ICE probe provides accurate information on the anatomy of the posterior aortic arch and thoracic and abdominal aortic aneurysms and a rapid identification of attachment sites and stent-graft pathology, allowing refinement and improvement of the endovascular strategy.

  7. [Intracerebral and subarachnoid hemorrhages after administration of recombinant tissue plasminogen activator in a patient with acute ischemicstroke due to anterior cerebral artery dissection: a case report].

    PubMed

    Ueyama, Ken; Koyama, Seigo; Nakamura, Ryoichi

    2011-06-01

    A 45-year-old man was admitted to our hospital for treatment of right hemiparesis. At admission, he was alert and well oriented. His verbal comprehension seemed good, but his speech was not fluent. He could not stand or walk owing to the right hemiparesis, which was severe in the lower extremity. Computed tomographic (CT) scans on admission showed no abnormality. Diffusion weighted magnetic resonance imaging performed after the CT showed a high-intensity lesion in the left cingulate gyrus. Magnetic resonance angiography (MRA) revealed occlusion and irregularity of the left A2 portion of the anterior cerebral artery (ACA). At 1 h 50 min after the onset of the hemiparesis, recombinant tissue plasminogen activator (rt-PA; 0.6 mg/kg) was administered intravenously. At 1 h after the administration of rt-PA, he became drowsy and his right hemiparesis deteriorated. CT scans performed again showed a hematoma in the left frontal lobe and subarachnoid hemorrhage in the anterior interhemispheric fissure. He was treated conservatively. MRA performed on the 18th day after admission showed recanalization of the left ACA and abnormal dilatation of the left A2 segment. The abnormal dilatation was also depicted by 3D-CT angiography (3D-CTA) performed on the 26th day after admission and even on the 33rd and 77th days. As seen in our case, the definite diagnosis of dissection confined to the ACA frequently needs serial angiographies; therefore, its diagnosis immediately after the onset is often difficult. Thrombolytic therapy by intravenous administration of rt-PA for cerebral infarction caused by dissection of the ACA may recanalize the occluded site and facilitate the progression of the dissection, resulting in intracerebral and/or subarachnoid hemorrhages. In patients with cerebral infarction due to ACA dissection, strict control of blood pressure and careful observation are necessary after thrombolytic therapy by rt-PA.

  8. Multiresolution quantum chemistry in multiwavelet bases: excited states from time-dependent Hartree–Fock and density functional theory via linear response

    SciTech Connect

    Yanai, Takeshi; Fann, George I.; Beylkin, Gregory; Harrison, Robert J.

    2015-02-25

    Using the fully numerical method for time-dependent Hartree–Fock and density functional theory (TD-HF/DFT) with the Tamm–Dancoff (TD) approximation we use a multiresolution analysis (MRA) approach to present our findings. From a reformulation with effective use of the density matrix operator, we obtain a general form of the HF/DFT linear response equation in the first quantization formalism. It can be readily rewritten as an integral equation with the bound-state Helmholtz (BSH) kernel for the Green's function. The MRA implementation of the resultant equation permits excited state calculations without virtual orbitals. Moreover, the integral equation is efficiently and adaptively solved using a numerical multiresolution solver with multiwavelet bases. Our implementation of the TD-HF/DFT methods is applied for calculating the excitation energies of H2, Be, N2, H2O, and C2H4 molecules. The numerical errors of the calculated excitation energies converge in proportion to the residuals of the equation in the molecular orbitals and response functions. The energies of the excited states at a variety of length scales ranging from short-range valence excitations to long-range Rydberg-type ones are consistently accurate. It is shown that the multiresolution calculations yield the correct exponential asymptotic tails for the response functions, whereas those computed with Gaussian basis functions are too diffuse or decay too rapidly. Finally, we introduce a simple asymptotic correction to the local spin-density approximation (LSDA) so that in the TDDFT calculations, the excited states are correctly bound.

  9. Morphometric analysis and taxonomic revision of Anisopteromalus Ruschka (Hymenoptera: Chalcidoidea: Pteromalidae) – an integrative approach

    PubMed Central

    Baur, Hannes; Kranz-Baltensperger, Yvonne; Cruaud, Astrid; Rasplus, Jean-Yves; Timokhov, Alexander V; Gokhman, Vladimir E

    2014-01-01

    We use an integrative taxonomic approach to revise the genus Anisopteromalus. In particular, we apply multivariate ratio analysis (MRA), a rather new statistical method based on principal component analysis (PCA) and linear discriminant analysis (LDA), to numerous body measurements and combine the data with those from our molecular analysis of Cytb and ITS2 genetic markers (on a subset of species) and all available published data on morphology, karyology, behaviour, host associations and geographic distribution. We demonstrate that the analysis of quantitative characters using MRA plays a major role for the integration of name-bearing types and thus for the association of taxa with names. Six species are recognized, of which two are new: A. cornis Baur sp.n. and A. quinarius Gokhman & Baur sp.n. For Anisopteromalus calandrae (Howard), a well-known, cosmopolitan parasitoid of stored-product pests, we have selected a neotype to foster continuity and stability in the application of this important name. The species was sometimes confused with the related A. quinarius sp.n., another cosmopolitan species that is frequently encountered in similar environments. We also show that several species originally described or later put under Anisopteromalus actually belong to different genera: Cyrtoptyx camerunus (Risbec) comb.n.; Meraporus glaber (Szelényi) comb.n.; Dinarmus schwenkei (Roomi, Khan & Khan) comb.n. Neocatolaccus indicus Ayyar & Mani is confirmed as a junior synonym of Oxysychus sphenopterae (Ferrière) syn.n. and Anisopteromalus calandrae brasiliensis (Domenichini) stat.rev. must be considered as a valid but doubtful taxon. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:BDFE96D3-D0F4-4012-90F5-9A087F7F5864. PMID:26074661

  10. Administered activity and metastatic cure probability during radioimmunotherapy of ovarian cancer in nude mice with {sup 211}At-MX35 F(ab'){sub 2}

    SciTech Connect

    Elgqvist, Joergen . E-mail: jorgen.elgqvist@radfys.gu.se; Andersson, Hakan; Bernhardt, Peter; Baeck, Tom; Claesson, Ingela; Hultborn, Ragnar; Jensen, Holger; Johansson, Bengt R.; Lindegren, Sture; Olsson, Marita; Palm, Stig; Warnhammar, Elisabet; Jacobsson, Lars

    2006-11-15

    Purpose: To elucidate the therapeutic efficacy of {alpha}-radioimmunotherapy of ovarian cancer in mice. This study: (i) estimated the minimum required activity (MRA), giving a reasonable high therapeutic efficacy; and (ii) calculated the specific energy to tumor cell nuclei and the metastatic cure probability (MCP) using various assumptions regarding monoclonal-antibody (mAb) distribution in measured tumors. The study was performed using the {alpha}-particle emitter Astatine-211 ({sup 211}At) labeled to the mAb MX35 F(ab'){sub 2}. Methods and Materials: Animals were inoculated intraperitoneally with {approx}1 x 10{sup 7} cells of the cell line NIH:OVCAR-3. Four weeks later animals were treated with 25, 50, 100, or 200 kBq {sup 211}At-MX35 F(ab'){sub 2} (n = 74). Another group of animals was treated with a nonspecific mAb: 100 kBq {sup 211}At-Rituximab F(ab'){sub 2} (n = 18). Eight weeks after treatment the animals were sacrificed and presence of macro- and microscopic tumors and ascites was determined. An MCP model was developed and compared with the experimentally determined tumor-free fraction (TFF). Results: When treatment was given 4 weeks after cell inoculation, the TFFs were 25%, 22%, 50%, and 61% after treatment with 25, 50, 100, or 200 kBq {sup 211}At-MX35 F(ab'){sub 2}, respectively, the specific energy to irradiated cell nuclei varying between {approx}2 and {approx}400 Gy. Conclusion: As a significant increase in the therapeutic efficacy was observed between the activity levels of 50 and 100 kBq (TFF increase from 22% to 50%), the conclusion was that the MRA is {approx}100 kBq {sup 211}At-MX35 F(ab'){sub 2}. MCP was most consistent with the TFF when assuming a diffusion depth of 30 {mu}m of the mAbs in the tumors.

  11. Contrast-enhanced CT- and MRI-based perfusion assessment for pulmonary diseases: basics and clinical applications.

    PubMed

    Ohno, Yoshiharu; Koyama, Hisanobu; Lee, Ho Yun; Miura, Sachiko; Yoshikawa, Takeshi; Sugimura, Kazuro

    2016-01-01

    Assessment of regional pulmonary perfusion as well as nodule and tumor perfusions in various pulmonary diseases are currently performed by means of nuclear medicine studies requiring radioactive macroaggregates, dual-energy computed tomography (CT), and dynamic first-pass contrast-enhanced perfusion CT techniques and unenhanced and dynamic first-pass contrast enhanced perfusion magnetic resonance imaging (MRI), as well as time-resolved three-dimensional or four-dimensional contrast-enhanced magnetic resonance angiography (MRA). Perfusion scintigraphy, single-photon emission tomography (SPECT) and SPECT fused with CT have been established as clinically available scintigraphic methods; however, they are limited by perfusion information with poor spatial resolution and other shortcomings. Although positron emission tomography with 15O water can measure absolute pulmonary perfusion, it requires a cyclotron for generation of a tracer with an extremely short half-life (2 min), and can only be performed for academic purposes. Therefore, clinicians are concentrating their efforts on the application of CT-based and MRI-based quantitative and qualitative perfusion assessment to various pulmonary diseases. This review article covers 1) the basics of dual-energy CT and dynamic first-pass contrast-enhanced perfusion CT techniques, 2) the basics of time-resolved contrast-enhanced MRA and dynamic first-pass contrast-enhanced perfusion MRI, and 3) clinical applications of contrast-enhanced CT- and MRI-based perfusion assessment for patients with pulmonary nodule, lung cancer, and pulmonary vascular diseases. We believe that these new techniques can be useful in routine clinical practice for not only thoracic oncology patients, but also patients with different pulmonary vascular diseases.

  12. Contrast-enhanced CT- and MRI-based perfusion assessment for pulmonary diseases: basics and clinical applications.

    PubMed

    Ohno, Yoshiharu; Koyama, Hisanobu; Lee, Ho Yun; Miura, Sachiko; Yoshikawa, Takeshi; Sugimura, Kazuro

    2016-01-01

    Assessment of regional pulmonary perfusion as well as nodule and tumor perfusions in various pulmonary diseases are currently performed by means of nuclear medicine studies requiring radioactive macroaggregates, dual-energy computed tomography (CT), and dynamic first-pass contrast-enhanced perfusion CT techniques and unenhanced and dynamic first-pass contrast enhanced perfusion magnetic resonance imaging (MRI), as well as time-resolved three-dimensional or four-dimensional contrast-enhanced magnetic resonance angiography (MRA). Perfusion scintigraphy, single-photon emission tomography (SPECT) and SPECT fused with CT have been established as clinically available scintigraphic methods; however, they are limited by perfusion information with poor spatial resolution and other shortcomings. Although positron emission tomography with 15O water can measure absolute pulmonary perfusion, it requires a cyclotron for generation of a tracer with an extremely short half-life (2 min), and can only be performed for academic purposes. Therefore, clinicians are concentrating their efforts on the application of CT-based and MRI-based quantitative and qualitative perfusion assessment to various pulmonary diseases. This review article covers 1) the basics of dual-energy CT and dynamic first-pass contrast-enhanced perfusion CT techniques, 2) the basics of time-resolved contrast-enhanced MRA and dynamic first-pass contrast-enhanced perfusion MRI, and 3) clinical applications of contrast-enhanced CT- and MRI-based perfusion assessment for patients with pulmonary nodule, lung cancer, and pulmonary vascular diseases. We believe that these new techniques can be useful in routine clinical practice for not only thoracic oncology patients, but also patients with different pulmonary vascular diseases. PMID:27523813

  13. Recent advances in Takayasu’s arteritis

    PubMed Central

    Alibaz-Öner, Fatma; Aydın, Sibel Zehra; Direskeneli, Haner

    2015-01-01

    Takayasu’s arteritis (TAK) is a rare, chronic large-vessel vasculitis (LVV) that predominantly affects the aorta, its major branches, and the pulmonary arteries. Recent advances in the diagnosis, clinical course, disease assessment with biomarkers/imaging and new clinical tools, patient-reported outcomes, and new treatment options of TAK are discussed in this review. Conventional angiography, the gold standard method for initial diagnosis, appears to have been replaced with new imaging modalities such as magnetic resonance angiography (MRA) and 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) in recent years. MRA and FDG-PET are also promising for the assessment of disease activity. New tools for disease assessment such as Indian Takayasu’s Arteritis Score 2010 (ITAS2010) and color Doppler ultrasound (CDUS) aim to better characterize and quantify disease activity; however, different imaging modalities in routine follow-up are not incorporated sufficiently in these approaches. Prognosis is possibly getting better, with lower mortality in recent years; however, it is difficult to assess the widely different vascular intervention rates among the clinical series. Leflunomide, tumor necrosis factor (TNF)-α antagonists, and tocilizumab are new options for patients resistant to conventional therapies. There is a clear need to develop a validated set of outcome measures for use in clinical trials of TAK. The Outcome Measures in Rheumatology (OMERACT) Vasculitis Working Group has taken on this task, finished a Delphi exercise with experts, and aims to develop a core set of outcomes for LVV in accordance with OMERACT Filter 2.0.

  14. Automated imaging technologies for the diagnosis of glaucoma: a comparative diagnostic study for the evaluation of the diagnostic accuracy, performance as triage tests and cost-effectiveness (GATE study).

    PubMed Central

    Azuara-Blanco, Augusto; Banister, Katie; Boachie, Charles; McMeekin, Peter; Gray, Joanne; Burr, Jennifer; Bourne, Rupert; Garway-Heath, David; Batterbury, Mark; Hernández, Rodolfo; McPherson, Gladys; Ramsay, Craig; Cook, Jonathan

    2016-01-01

    BACKGROUND Many glaucoma referrals from the community to hospital eye services are unnecessary. Imaging technologies can potentially be useful to triage this population. OBJECTIVES To assess the diagnostic performance and cost-effectiveness of imaging technologies as triage tests for identifying people with glaucoma. DESIGN Within-patient comparative diagnostic accuracy study. Markov economic model comparing the cost-effectiveness of a triage test with usual care. SETTING Secondary care. PARTICIPANTS Adults referred from the community to hospital eye services for possible glaucoma. INTERVENTIONS Heidelberg Retinal Tomography (HRT), including two diagnostic algorithms, glaucoma probability score (HRT-GPS) and Moorfields regression analysis (HRT-MRA); scanning laser polarimetry [glaucoma diagnostics (GDx)]; and optical coherence tomography (OCT). The reference standard was clinical examination by a consultant ophthalmologist with glaucoma expertise including visual field testing and intraocular pressure (IOP) measurement. MAIN OUTCOME MEASURES (1) Diagnostic performance of imaging, using data from the eye with most severe disease. (2) Composite triage test performance (imaging test, IOP measurement and visual acuity measurement), using data from both eyes, in correctly identifying clinical management decisions, that is 'discharge' or 'do not discharge'. Outcome measures were sensitivity, specificity and incremental cost per quality-adjusted life-year (QALY). RESULTS Data from 943 of 955 participants were included in the analysis. The average age was 60.5 years (standard deviation 13.8 years) and 51.1% were females. Glaucoma was diagnosed by the clinician in at least one eye in 16.8% of participants; 37.9% of participants were discharged after the first visit. Regarding diagnosing glaucoma, HRT-MRA had the highest sensitivity [87.0%, 95% confidence interval (CI) 80.2% to 92.1%] but the lowest specificity (63.9%, 95% CI 60.2% to 67.4%) and GDx had the lowest

  15. KEY COMPARISON: Final report on CCQM-K38: Determination of PAHs in solution

    NASA Astrophysics Data System (ADS)

    Duewer, D. L.; May, W. E.; Parris, R. M.; Schantz, M. M.; Wise, S. A.; Piechotta, C.; Philipp, R.; Win, T.; Avila, M.; Pérez Urquiza, M.; Ulberth, F.; Kim, B.; Ishikawa, K.; Chen, D.; Krylov, A. I.; Kustidov, Y. A.; Lopushanskaya, E. M.

    2009-01-01

    Solutions of known mass fraction of organic analytes of interest are typically used to calibrate the measurement processes used in the determination of these analytes. Appropriate value assignments and uncertainty calculations for these calibration solutions are critical. For the Mutual Recognition Arrangement (MRA) developed by the CIPM, there are numerous Calibration and Measurement Capability Claims (CMCs) published in Category 3 Organic Solutions in the CIPM MRA Appendix C. Additional CMCs in this category are being proposed and reviewed. Evidence of successful participation in formal, relevant international comparisons is needed to support these claims. A CCQM pilot study conducted in 2004 was comprised of three parts: CCQM-P31a Organic Solution—Polycyclic Aromatic Hydrocarbons (PAHs), CCQM-P31b Organic Solution—Polychlorinated Biphenyl (PCB) Congeners, and CCQM-P31c Organic Solution—Chlorinated Pesticides. The results from the CCQM-P31a study are summarized below for the PAHs. After review of the P31a results at the April 2004 Organic Analytical Working Group (OAWG) meeting (Sèvres 2004) and the October 2004 OAWG meeting (Beijing 2004), it was decided to proceed with a key comparison study for PAHs in solution (CCQM-K38) with a concurrent second pilot study for the PAHs in solution (CCQM-P31a.1). CCQM-K38 was conducted during the same time period as a PAHs in soil pilot study (CCQM-P69) coordinated by CENAM and BAM. This Key Comparison study demonstrated a high level of equivalence in capabilities of the participating NMIs to successfully identify and measure five PAHs (phenanthrene, fluoranthene, benz[a]anthracene, benzo[a]pyrene, and benzo[ghi]perylene) in a solution using GC/MS-based methods. The PAHs measured in CCQM-K38 were selected to be representative of PAHs typically used as calibrants in the determination of the PAHs found in environmental samples and to provide the typical analytical measurement challenges encountered in the value

  16. A nude rat model for neutron capture therapy of human intracerebral melanoma

    SciTech Connect

    Barth, R.F.; Matalka, K.Z.; Bailey, M.Q.; Staubus, A.E.; Soloway, A.H.; Moeschberger, M.L. ); Coderre, J.A. ); Rofstad, E.K. )

    1994-03-30

    The present study was carried out to determine the efficacy of Boron Neutron Capture Therapy (BNCT) for intracerebral melanoma using nude rats, the human melanoma cell line MRA 27, and boronophenylalanine as the capture agent. MRA 27 cells (2 [times] 10[sup 5]) were implanted intracerebrally, and 30 days later, 120 mg of [sup 10]B-L-BPA were injected intraperitoneally into nude rats. Thirty days following implantation, tumor bearing rats were irradiated at the Brookhaven Medical Research Reactor. Six hours following administration of BPA, tumor, blood, and normal brain boron-10 levels were 23.7, 9.4, and 8.4 [mu]g/g respectively. Median survival time of untreated rats was 44 days compared to 76 days and 93 days for those receiving physical doses of 2.73 Gy and 3.64 Gy, respectively. Rats that have received both [sup 10]B-BPA and physical doses of 1.82, 2.73, or 3.64 Gy had median survival times of 170, 182, and 262 days, respectively. Forty percent of rats that had received the highest tumor dose (10.1 Gy) survived for > 300 days and in a replicate experiment 21% of the rats were longterm survivors (>220 days). Animals that received 12 Gy in a single dose or 18 Gy fractionated (2 Gy [times] 9) of gamma photons from a [sup 137]Cs source had median survival times of 86 and 79 days, respectively, compared to 47 days for untreated animals. Histopathologic examination of the brains of longterm surviving rats, euthanized at 8 or 16 months following BNCT, showed no residual tumor, but dense accumulations of melanin laden macrophages and minimal gliosis were observed. Significant prolongations in median survival time were noted in nude rats with intracerebral human melanoma that had received BNCT, thereby suggesting therapeutic efficacy. Large animal studies should be carried out to further assess BNCT of intracerebral melanoma before any human trials are contemplated. 49 refs., 7 figs., 2 tabs.

  17. High-Permittivity Thin Dielectric Padding Improves Fresh Blood Imaging of Femoral Arteries at 3T

    PubMed Central

    Lindley, Marc D; Kim, Daniel; Morrell, Glen; Heilbrun, Marta E; Storey, Pippa; Hanrahan, Christopher J; Lee, Vivian S

    2014-01-01

    Objectives Fresh blood imaging (FBI) is a useful non-contrast magnetic resonance angiography (NC-MRA) method for assessment of peripheral arterial disease (PAD), particularly in patients with poor renal function. Compared with 1.5T, 3T enables higher signal to noise ratio (SNR) and/or spatio-temporal resolution in FBI, as demonstrated successfully for the calf station. However, FBI of the thigh station at 3T has been reported to suffer from signal void in the common femoral artery of one thigh only due to the radial symmetry in transmit radio-frequency field (B1+) variation. We sought to increase the femoral arterial signal attenuated by B1+ variation in FBI at 3T using high permittivity dielectric padding. Materials and Methods We performed FBI of the thigh station in 13 human subjects at 3T to compare the following 3 settings: no padding, commercially available thick (~ 5 cm) dielectric padding, and high-permittivity thin (~2 cm) dielectric padding. B1+ mapping was also performed in the common femoral arteries to characterize the radial symmetry in B1+ variation and quantify the improvement in B1+ excitation. We characterized the impact of radial symmetry in B1+ variation on the FBI signal and FBI MRA of the right common femoral artery using quantitative (i.e., contrast-to-noise ratio (CNR)) and qualitative (i.e., conspicuity) analyses. Results The radial symmetry in B1+ variation attenuates signal in the right common femoral artery, which can be partially improved with commercial padding and improved further with high permittivity padding. Averaging the results over 13 subjects, the B1+, CNR and conspicuity scores in the right common femoral artery were significantly better with high-permittivity padding than with commercial padding and baseline (p<0.001). Conclusions Our study shows that high-permittivity dielectric padding can be used to increase the femoral arterial signal attenuated by B1+ variation in FBI at 3T. PMID:25329606

  18. Characterizing land condition variability in Ferlo, Senegal (2001-2009) using multi-temporal 1-km Apparent Green Cover (AGC) SPOT Vegetation data

    NASA Astrophysics Data System (ADS)

    Martínez, B.; Gilabert, M. A.; García-Haro, F. J.; Faye, A.; Meliá, J.

    2011-04-01

    The ecosystem state or 'land condition' can be characterized by a set of attributes, which show variations at different temporal scales. A multi-resolution analysis (MRA) based on the wavelet transform (WT) has been implemented to examine the land condition of a dryland region in Ferlo (Senegal) over the period 2001-2009. This methodology has proven to be useful for smoothing time series while considering those temporal resolutions that incorporate information about the vegetation dynamics. For this purpose, time series of the 1-km Apparent Green Cover (AGC) from the 10-day composites SPOT Vegetation (VGT) data are analyzed. Two relevant outputs from the MRA, A1 (de-noised) and the A6 (inter-annual) components have served us for characterizing the annual vegetation production and assess the long-term variation, respectively. In a first stage, the vegetation seasonality (or intra-annual variation) over the area is described by using several metrics related to vegetation phenology derived from the de-noised time series ( A1). In a second phase, the temporal variability of the inter-annual component series ( A6) is accomplished to detect potential vegetation changes over the considered period. A Mann-Kendall test has been applied to confirm the significance of the observed inter-annual changes. A higher number of significant pixels (86%) are obtained when considering the inter-annual component in the trend analysis instead of the original time-series (47%). The results confirm a general greening up over the period 2001-2009, not fully explained by precipitation, as well as rather local negative trends. The Rain-Use Efficiency (RUE) ratio computed using the AGC as a proxy of vegetation production has been considered to further analyze the detected changes. Inter-annual changes in RUE provide a potential method of separating vegetation declines due to lack of rainfall from declines associated with degradation. Some spots of negative values in inter-annual RUE changes

  19. Required buried alpha-helical structure in the bilirubin UDP-glucuronosyltransferase, UGT1A1, contains a nonreplaceable phenylalanine.

    PubMed

    Ciotti, M; Cho, J W; George, J; Owens, I S

    1998-08-01

    A conserved hydrophobic region in the bilirubin-type UDP-glucuronosyltransferase isozyme was first uncovered as a consequence of a deleterious mutation in the UGT1A1 (HUG-Br1) isozyme of a Crigler-Najjar (CN) Type I patient. According to analysis by the RAOARGOS computer program, this hydrophobic region in UGT1A1 is located between residues 159-177 and defines a buried helix centered over position 169-172 with a positive factor of 1.22. Further analysis showed that the planar phenol-type UGT1A6 (HLUG P1) isoform, unlike the steroid-type UGT2B7 (UDPGTh2) isozyme, has a similar conserved hydrophobic region and that the positive factor for its buried helix is 1.14 compared to the threshold of 1.13 for such a structure. The analysis detected the typical membrane-insertion-signal sequence and a membrane-anchoring domain in each isoform. The different amino acid sequence patterns between positions 168-172 for the three types of isoforms and the deleterious mutations in this microregion (MRA) of UGT1A1 in CN-I patients are evidence of a critical and descriminating role for MRA. With the recombinant UGT1A1 enzyme and its mutants, P167G, F170del, F170L, F170I, F170V, F170A, F170Y, F170E, F171L, F171I, F171V, F171A, F171Y, or L175Q, expressed in COS-1 cells, bilirubin glucuronidating activity at both pH 6.4 and 7.6 demonstrated that Phe-170 is not replaceable, whereas Phe-171 can be replaced by Leu without any loss of activity. The less hydrophobic buried helix in the phenolic-type UGT1A6 has a Tyr/Leu at position 170/171; this isoform glucuronidated bilirubin at 1/10 the level of that by UGT1A1 with a Km (bilirubin) of 25 microM compared to that for UGT1A1 of 5. 0 microM.

  20. Final report on CCQM-K89: Trace and essential elements in Herba Ecliptae

    NASA Astrophysics Data System (ADS)

    Valiente, Liliana; Saxby, David; Merrick, Jeffrey; Kotzeva, Boriana; Mester, Zoltan; Yang, Lu; Willie, Scott; Feng, Liuxing; Wang, Jun; Labarraque, Guillaume; Rienitz, Olaf; Wai-mei Sin, Della; Mok, Chuen-sing; Wong, Siu-kay; Ng, Chi-shing; Fung, Wai-hong; Yau, Ho-pan; Zhu, Yanbei; Yim, Yong-Hyeon; Lee, Kyoung Seok; Kim, In Jung; Lim, Young Ran; Ramirez Cruz, Pedro; Mercader Trejo, Flora E.; Valle Moya, Edith; Santiago Castellanos, Itzel; del Rocio Arvizu Torres, Maria; Manzano, Judith Velina Lara; Konopelko, L. A.; Kustikov, Yu A.; Shin, Richard; Horvat, Milena; Jacimovic, Radojko; Milacic, Radmila; Yafa, Charun; Taebunpakul, Sutthinun; Kaewkhomdee, Nattikarn; Phukphatthanachai, Pranee; Cankur, Oktay; Gonca Coskun, F.; Turk, Gregory C.; Davis, W. Clay; Wood, Laura J.; Murphy, Karen E.; Entwisle, John

    2013-01-01

    The key comparison CCQM-K89 was undertaken to demonstrate the capability of participating NMIs and DIs in measuring the contents of incurred trace elements (total arsenic, cadmium and lead) and essential elements (calcium and zinc) at µg/g (for arsenic, cadmium, lead and zinc) and mg/g (for calcium) levels in a herb matrix sample by various analytical techniques. This key comparison was organized by the Government Laboratory of the Hong Kong Special Administrative Region (GLHK) and agreed at the Inorganic Analysis Working Group Meeting in Hindås, Sweden in October 2010 as a benchmarking exercise with arsenic (a trace element) and calcium (an essential element) chosen as the 'exemplary' elements. It was also agreed that a pilot study CCQM-P126 would be run in parallel with this key comparison. The key comparison serves to facilitate claims by participants on the Calibration and Measurement Capabilities (CMCs) as listed in Appendix C of the Key Comparison Database (KCDB) under the Mutual Recognition Arrangement of the International Committee for Weights and Measures (CIPM MRA). A total of 20 NMIs/DIs registered for this programme and 18 of them submitted their results. Most of the participants used microwave acid digestion methods for sample dissolution. For the instrumental determination, a variety of techniques like ICP-MS, AAS, INAA, ICP-AES were employed by the participants. For this key comparison, inorganic core capabilities have been demonstrated by concerned participants with respect to methods including ICP-MS (without isotope dilution), ID-ICP-MS, ICP-AES, INAA, AAS and ion chromatography with iteratively matrix-matched calibration on the determination of total arsenic, calcium, cadmium, lead and zinc in a matrix of herb. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for

  1. Final report on APMP.QM-S5: Essential and toxic elements in seafood

    NASA Astrophysics Data System (ADS)

    Valiente, Liliana; Bennett, John W.; Caciano de Sena, Rodrigo; Kotzeva, Boriana; Massiff, Gabriela; Chao, Jingbo; Wang, Jun; Nasr, Randa; Labarraque, Guillaume; Kakoulidis, Elias; Lampi, Eugenia; Wai-mei Sin, Della; Mok, Chuen-shing; Wong, Siu-kay; Yip, Yiu-chung; Gopala Aggarwal, Shankar; Gupta, Prabhat K.; Zhu, Yanbei; Miyashita, Shin-ichi; Yim, Yong-Hyeon; Zakaria, Osman; Manzano, Judith Velina Lara; Shin, Richard; Horvat, Milena; Yafa, Charun

    2013-01-01

    The supplementary comparison APMP.QM-S5 was undertaken to demonstrate the capability of participating national metrology institutes (NMIs) and designated institutes (DIs) in measuring the contents of the incurred essential elements (iron and zinc) and toxic elements (total arsenic and cadmium) at µg/g levels in a test sample of dried shrimp by various analytical techniques. At the APMP TCQM Meeting held in Pattaya, Thailand in November 2010, Government Laboratory of the Government of the Hong Kong Special Administrative Region (GLHK) proposed this APMP supplementary comparison. The proposal was further discussed and agreed upon at the CCQM Inorganic Analysis Working Group Meeting held in Paris in April 2011. GLHK was the coordinating laboratory for the supplementary comparison. For enhancing the collaboration amongst specialized regional bodies in Asia-Pacific and to help build the laboratory capacity of NMIs/DIs from developing economies, the reference values of the supplementary comparison are used for evaluation of performance of participants of an APMP proficiency testing programme (APMP PT 11-01), an Asia-Pacific Laboratory Accreditation Cooperation proficiency testing programme (APLAC T082) and an Asia-Pacific Economic Co-operation proficiency testing programme (APEC PT), which were concurrently run using the same testing material as in APMP.QM-S5. The supplementary comparison serves to facilitate claims by participants on the Calibration and Measurement Capabilities (CMCs) as listed in Appendix C of the Key Comparison Database (KCDB) under the Mutual Recognition Arrangement of the International Committee for Weights and Measures (CIPM MRA). A total of 18 institutes registered for the supplementary comparison and all of them submitted their results. Most of the participants used microwave acid digestion methods for sample dissolution. For the instrumental determination, a variety of techniques like ICP-MS, ICP-OES, INAA and AAS were employed by the

  2. Use of a semi-automated cardiac segmentation tool improves reproducibility and speed of segmentation of contaminated right heart magnetic resonance angiography.

    PubMed

    Tandon, Animesh; Byrne, Nicholas; Nieves Velasco Forte, Maria de Las; Zhang, Song; Dyer, Adrian K; Dillenbeck, Jeanne M; Greil, Gerald F; Hussain, Tarique

    2016-08-01

    Three-dimensional printing has an increasing number of clinical applications in pediatric cardiology. Time required for dataset segmentation and conversion to stereolithography (STL) format remains a significant limitation. We investigated the impact of semi-automated cardiovascular-specific segmentation software on time and reproducibility of segmentation. Magnetic resonance angiograms (MRAs) of 19 patients undergoing intervention for right ventricular outflow lesions were segmented to demonstrate the right heart. STLs were created by two independent clinicians using semi-automated cardiovascular segmentation (SAS) and traditional manual segmentation (MS). Time was recorded and geometric STL disagreement was determined (0 % = no disagreement, 100 % = complete disagreement). MRA datasets were categorized as clean when only right heart structures were present in the MRA, or contaminated when left heart structures were also present and required removal. Eighteen (seven clean and 11 contaminated) cases were successfully segmented with both methods. Time to STL for clean datasets was faster with MS than SAS [median 209 s (IQR 192-252) vs. 296 s (272-317), p = 0.018] while contaminated datasets were faster with SAS [455 s (384-561) vs. 866 s (310-1429), p = 0.033]. Interobserver STL geometric disagreement was significantly lower using SAS than MS overall (0.70 ± 1.15 % vs. 1.31 ± 1.52 %, p = 0.030), and for the contaminated subset (0.81 ± 1.08 % vs. 1.75 ± 1.57 %, p = 0.036). Most geometric disagreement occurred at areas where left heart contamination was removed. Semi-automated segmentation was faster and more reproducible for contaminated datasets, while MS was faster but equally reproducible for clean datasets. Semi-automated segmentation methods are preferable for contaminated datasets and continued refinement of these tools should be supported. PMID:27173489

  3. Use of a semi-automated cardiac segmentation tool improves reproducibility and speed of segmentation of contaminated right heart magnetic resonance angiography.

    PubMed

    Tandon, Animesh; Byrne, Nicholas; Nieves Velasco Forte, Maria de Las; Zhang, Song; Dyer, Adrian K; Dillenbeck, Jeanne M; Greil, Gerald F; Hussain, Tarique

    2016-08-01

    Three-dimensional printing has an increasing number of clinical applications in pediatric cardiology. Time required for dataset segmentation and conversion to stereolithography (STL) format remains a significant limitation. We investigated the impact of semi-automated cardiovascular-specific segmentation software on time and reproducibility of segmentation. Magnetic resonance angiograms (MRAs) of 19 patients undergoing intervention for right ventricular outflow lesions were segmented to demonstrate the right heart. STLs were created by two independent clinicians using semi-automated cardiovascular segmentation (SAS) and traditional manual segmentation (MS). Time was recorded and geometric STL disagreement was determined (0 % = no disagreement, 100 % = complete disagreement). MRA datasets were categorized as clean when only right heart structures were present in the MRA, or contaminated when left heart structures were also present and required removal. Eighteen (seven clean and 11 contaminated) cases were successfully segmented with both methods. Time to STL for clean datasets was faster with MS than SAS [median 209 s (IQR 192-252) vs. 296 s (272-317), p = 0.018] while contaminated datasets were faster with SAS [455 s (384-561) vs. 866 s (310-1429), p = 0.033]. Interobserver STL geometric disagreement was significantly lower using SAS than MS overall (0.70 ± 1.15 % vs. 1.31 ± 1.52 %, p = 0.030), and for the contaminated subset (0.81 ± 1.08 % vs. 1.75 ± 1.57 %, p = 0.036). Most geometric disagreement occurred at areas where left heart contamination was removed. Semi-automated segmentation was faster and more reproducible for contaminated datasets, while MS was faster but equally reproducible for clean datasets. Semi-automated segmentation methods are preferable for contaminated datasets and continued refinement of these tools should be supported.

  4. 5-Androstene-3{beta},17{beta}-diol Promotes Recovery of Immature Hematopoietic Cells Following Myelosuppressive Radiation and Synergizes With Thrombopoietin

    SciTech Connect

    Aerts-Kaya, Fatima S.F.; Visser, Trudi P.; Arshad, Shazia; Frincke, James; Stickney, Dwight R.; Reading, Chris L.; Wagemaker, Gerard

    2012-11-01

    Purpose: 5-Androstene-3{beta},17{beta}-diol (5-AED) stimulates recovery of hematopoiesis after exposure to radiation. To elucidate its cellular targets, the effects of 5-AED alone and in combination with (pegylated) granulocyte colony-stimulating factor and thrombopoietin (TPO) on immature hematopoietic progenitor cells were evaluated following total body irradiation. Methods and Materials: BALB/c mice were exposed to radiation delivered as a single or as a fractionated dose, and recovery of bone marrow progenitors and peripheral blood parameters was assessed. Results: BALB/c mice treated with 5-AED displayed accelerated multilineage blood cell recovery and elevated bone marrow (BM) cellularity and numbers of progenitor cells. The spleen colony-forming unit (CFU-S) assay, representing the life-saving short-term repopulating cells in BM of irradiated donor mice revealed that combined treatment with 5-AED plus TPO resulted in a 20.1-fold increase in CFU-S relative to that of placebo controls, and a 3.7 and 3.1-fold increase in comparison to 5-AED and TPO, whereas no effect was seen of Peg-G-CSF with or without 5-AED. Contrary to TPO, 5-AED also stimulated reconstitution of the more immature marrow repopulating (MRA) cells. Conclusions: 5-AED potently counteracts the hematopoietic effects of radiation-induced myelosuppression and promotes multilineage reconstitution by stimulating immature bone marrow cells in a pattern distinct from, but synergistic with TPO.

  5. Identification of a hemodynamic parameter for assessing treatment outcome of EDAS in Moyamoya disease.

    PubMed

    Karunanithi, Kaavya; Han, Cong; Lee, Chang-Joon; Shi, Wanchao; Duan, Lian; Qian, Yi

    2015-01-21

    This work is a novel attempt to incorporate computational fluid dynamics (CFD) techniques in the analysis of hemodynamic parameters of Moyamoya disease (MMD). Highly prevalent in Asian countries, MMD is characterised by progressive occlusion of the intracranial Internal Carotid Arteries (ICA). We intend to identify a reliable hemodynamic parameter that can be used to gauge treatment outcome. This will aid surgeons in the perioperative management of MMD patients. We carried out CFD analysis on eight patients (5 female, 3 male) with MMD treated by EDAS (encephalo-duro-arterio-synangiosis) between 2011 and 2012. All the eight patients presented with haemorrhage, with subsequent 4-12 month follow-up done using Magnetic Resonance Angiography (MRA) to capture auto-remodelling. We calculated percentage change in flow rate and pressure drop indicator (ΡDI) across the Left and Right ICA. Pressure drop indicator (PDI) is defined as the difference of pressure reduction within the carotid arteries, measured at post-op and follow up, using patient specific inflow rates. The measured percentage flow change and pressure reduction showed an increase at follow up for improved patients (characterised by angiography according to the method of Matsushima), who did not develop any complications after surgery. The inverse was observed in patients who were clinically classified as no change and retrogressed (according to the method of Matsushima) cases post-operation. This elucidates that our findings have instituted a new parameter that may well play a critical role as an assistive clinical decision making tool in MMD.

  6. Bilateral key comparison SIM.T-K6.5 on humidity standards in the dew/frost-point temperature range from -30 °C to +20 °C

    NASA Astrophysics Data System (ADS)

    Meyer, C.; Solano, A.

    2016-01-01

    A Regional Metrology Organization (RMO) Key Comparison of dew/frost point temperatures was carried out by the National Institute of Standards and Technology (NIST, USA) and the Laboratorio Costarricense de Metrología (LACOMET, Costa Rica) between February 2015 and August 2015. The results of this comparison are reported here, along with descriptions of the humidity laboratory standards for NIST and LACOMET and the uncertainty budget for these standards. This report also describes the protocol for the comparison and presents the data acquired. The results are analyzed, determining degree of equivalence between the dew/frost-point standards of NIST and LACOMET. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  7. SUPPLEMENTARY COMPARISON Technically enhanced naturally occurring radionuclides (TENORM) in phosphogypsum: Comparison CCRI(II)-S5

    NASA Astrophysics Data System (ADS)

    Shakhashiro, A.; Sansone, U.; Wershofen, H.; Bollhöfer, A.; Kim, C. K.; Kim, C. S.; Korun, M.; Moune, M.; Lee, S. H.; Tarjan, S.

    2010-01-01

    Within the frame of mutual cooperation between the IAEA and the BIPM, the Consultative Committee for Ionizing Radiation Section II—Measurement of Radionuclides accepted an IAEA-organized interlaboratory comparison in 2008 on the determination of technically enhanced naturally occurring radionuclides in phosphogypsum. The study was piloted by the Chemistry Unit at the IAEA's Laboratories in Seibersdorf (Austria). This report presents the methodology applied in conducting this comparison and the results. Activity results for Pb-210, Ra-226, Th-230, U-234, U-235 and U-238 were reported by three national metrology institutes (NMI) and five other expert laboratories or designated institutes. Four different approaches were used to calculate the nominal value of the reported results and associated uncertainties, and the results from each individual participant were evaluated and compared with this nominal reference value. The reported evaluation of the measurement results demonstrated agreement amongst the participating laboratories. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI Section II, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  8. Performance of the Wavelet Decomposition on Massively Parallel Architectures

    NASA Technical Reports Server (NTRS)

    El-Ghazawi, Tarek A.; LeMoigne, Jacqueline; Zukor, Dorothy (Technical Monitor)

    2001-01-01

    Traditionally, Fourier Transforms have been utilized for performing signal analysis and representation. But although it is straightforward to reconstruct a signal from its Fourier transform, no local description of the signal is included in its Fourier representation. To alleviate this problem, Windowed Fourier transforms and then wavelet transforms have been introduced, and it has been proven that wavelets give a better localization than traditional Fourier transforms, as well as a better division of the time- or space-frequency plane than Windowed Fourier transforms. Because of these properties and after the development of several fast algorithms for computing the wavelet representation of any signal, in particular the Multi-Resolution Analysis (MRA) developed by Mallat, wavelet transforms have increasingly been applied to signal analysis problems, especially real-life problems, in which speed is critical. In this paper we present and compare efficient wavelet decomposition algorithms on different parallel architectures. We report and analyze experimental measurements, using NASA remotely sensed images. Results show that our algorithms achieve significant performance gains on current high performance parallel systems, and meet scientific applications and multimedia requirements. The extensive performance measurements collected over a number of high-performance computer systems have revealed important architectural characteristics of these systems, in relation to the processing demands of the wavelet decomposition of digital images.

  9. Bilateral comparison of 100 pF capacitance standards (ongoing BIPM key comparison BIPM.EM-K14.b) between the NSAI-NML, Ireland, and the BIPM, March-August 2011

    NASA Astrophysics Data System (ADS)

    Power, O.; Moran, A.; Fletcher, N.; Goebel, R.; Stock, M.

    2015-01-01

    This report gives the result of a bilateral comparison of capacitance between the NSAI-NML (Ireland) and the BIPM carried out in 2011. Two 100 pF travelling standards belonging to the BIPM were used. The comparison was carried out with an 'A-B-A' pattern of measurements; the standards were measured first at the BIPM for a period of about one month, then for a similar period at the NSAI-NML, and finally again at the BIPM. The measurand was the two terminal-pair capacitance at a frequency of 1000 Hz, for a measuring voltage of 15 V. The BIPM was the pilot laboratory, and the comparison forms part of the ongoing BIPM key comparison BIPM.EM-K14.b. The results from the NSAI-NML and the BIPM were found to be in good agreement, with a difference smaller than the relative expanded uncertainty (95 % confidence, k = 2) of 0.66 × 10-6. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  10. Bilateral comparison of 10 pF capacitance standards (ongoing BIPM key comparison BIPM.EM-K14.a) between the NSAI-NML, Ireland, and the BIPM, March-August 2011

    NASA Astrophysics Data System (ADS)

    Power, O.; Moran, A.; Fletcher, N.; Goebel, R.; Stock, M.

    2015-01-01

    This report gives the result of a bilateral comparison of capacitance between the NSAI-NML (Ireland) and the BIPM carried out in 2011. Two 10 pF travelling standards belonging to the BIPM were used. The comparison was carried out with an 'A—B—A' pattern of measurements; the standards were measured first at the BIPM for a period of about one month, then for a similar period at the NSAI-NML, and finally again at the BIPM. The measurand was the two terminal-pair capacitance at a frequency of 1000 Hz for a measuring voltage of 15 V. The BIPM was the pilot laboratory, and the comparison forms part of the ongoing BIPM key comparison BIPM.EM-K14.a. The results from the NSAI-NML and the BIPM were found to be in good agreement, with a difference smaller than the relative expanded uncertainty (95 % confidence, k = 2) of 2.5 × 10-6. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  11. [Evaluation of carotid stenosis by using carotid ultrasonography].

    PubMed

    Seike, Nahoko; Ito, Michiko; Yasaka, Masahiro

    2010-12-01

    Carotid stenosis is observed in several diseases such as atherosclerosis, moyamoya disease, and aortitis. Carotid stenosis can be assessed using computed tomography (CT), magnetic resonance angiography (MRA), ultrasonography, or cerebral angiography. Carotid ultrasonography is superior to other modalities because it is a noninvasive, repeatable, and easy method that does not involve much cost. The intima-media complex thickness (IMT) can be easily measured using carotid ultrasonography. The incidence of cerebral and cardiovascular events increases with increase in the thickness of the IMT. The percentage of stenosis was expressed using the NASCET, ECST, or area methods. The NASCET criterion of 70% stenosis for performing carotid endarterectomy for symptomatic carotid stenosis corresponded to 85% ECST stenosis, 90% area stenosis, and 200 cm/sec of peak systolic velocity. Carotid ultrasonography provides information on not only carotid stenosis but also unstable plaques such as ulcer, hypoechoic plaque, thin fibrous cap, and mobile plaque. In patients with moyamoya disease, carotid ultrasonography often reveals that the diameter of the internal carotid artery (ICA) is greatly reduced at the proximal portion above the bulbus (resembling a champagne bottle neck) and is less than 50% that of the common carotid artery (champagne bottle neck sign); the diameter of the ICA is smaller than that of the external carotid artery (diameter reversal sign). In patients with aortitis, IMT thickness is frequently observed at the common carotid artery (Macaroni sign) but not at the ICA. PMID:21139180

  12. An Active Contour Model Based on Adaptive Threshold for Extraction of Cerebral Vascular Structures.

    PubMed

    Wang, Jiaxin; Zhao, Shifeng; Liu, Zifeng; Tian, Yun; Duan, Fuqing; Pan, Yutong

    2016-01-01

    Cerebral vessel segmentation is essential and helpful for the clinical diagnosis and the related research. However, automatic segmentation of brain vessels remains challenging because of the variable vessel shape and high complex of vessel geometry. This study proposes a new active contour model (ACM) implemented by the level-set method for segmenting vessels from TOF-MRA data. The energy function of the new model, combining both region intensity and boundary information, is composed of two region terms, one boundary term and one penalty term. The global threshold representing the lower gray boundary of the target object by maximum intensity projection (MIP) is defined in the first-region term, and it is used to guide the segmentation of the thick vessels. In the second term, a dynamic intensity threshold is employed to extract the tiny vessels. The boundary term is used to drive the contours to evolve towards the boundaries with high gradients. The penalty term is used to avoid reinitialization of the level-set function. Experimental results on 10 clinical brain data sets demonstrate that our method is not only able to achieve better Dice Similarity Coefficient than the global threshold based method and localized hybrid level-set method but also able to extract whole cerebral vessel trees, including the thin vessels. PMID:27597878

  13. New fuzzy wavelet network for modeling and control: The modeling approach

    NASA Astrophysics Data System (ADS)

    Ebadat, Afrooz; Noroozi, Navid; Safavi, Ali Akbar; Mousavi, Seyyed Hossein

    2011-08-01

    In this paper, a fuzzy wavelet network is proposed to approximate arbitrary nonlinear functions based on the theory of multiresolution analysis (MRA) of wavelet transform and fuzzy concepts. The presented network combines TSK fuzzy models with wavelet transform and ROLS learning algorithm while still preserve the property of linearity in parameters. In order to reduce the number of fuzzy rules, fuzzy clustering is invoked. In the clustering algorithm, those wavelets that are closer to each other in the sense of the Euclidean norm are placed in a group and are used in the consequent part of a fuzzy rule. Antecedent parts of the rules are Gaussian membership functions. Determination of the deviation parameter is performed with the help of gold partition method. Here, mean of each function is derived by averaging center of all wavelets that are related to that particular rule. The overall developed fuzzy wavelet network is called fuzzy wave-net and simulation results show superior performance over previous networks. The present work is complemented by a second part which focuses on the control aspects and to be published in this journal( [17]). This paper proposes an observer based self-structuring robust adaptive fuzzy wave-net (FWN) controller for a class of nonlinear uncertain multi-input multi-output systems.

  14. Comparison of density determination of liquid samples by density meters

    NASA Astrophysics Data System (ADS)

    Buchner, C.; Wolf, H.; Vámossy, C.; Lorefice, S.; Lenard, E.; Spohr, I.; Mares, G.; Perkin, M.; Parlic-Risovic, T.; Grue, L.-L.; Tammik, K.; van Andel, I.; Zelenka, Z.

    2016-01-01

    Hydrostatic density determinations of liquids as reference material are mainly performed by National Metrology Institutes to provide means for calibrating or checking liquid density measuring instruments such as oscillation-type density meters. These density meters are used by most of the metrology institutes for their calibration and scientific work. The aim of this project was to compare the results of the liquid density determination by oscillating density meters of the participating laboratories. The results were linked to CCM.D.K-2 partly via Project EURAMET.M.D.K-2 (1019) "Comparison of liquid density standards" by hydrostatic weighing piloted by BEV in 2008. In this comparison pentadecane, water and of oil with a high viscosity were measured at atmospheric pressure using oscillation type density meter. The temperature range was from 15 °C to 40 °C. The measurement results were in some cases discrepant. Further studies, comparisons are essential to explore the capability and uncertainty of the density meters Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  15. Population genetic structure and trait associations in forest savory using molecular, morphological and phytochemical markers.

    PubMed

    Khadivi-Khub, Abdollah; Karimi, Ehsan; Hadian, Javad

    2014-08-10

    In this investigation, morphological, phytochemical and ISSR markers were used to estimate the relationships among and within seven populations of white savory (Satureja mutica), belonging to four provinces in Iran. The individuals were phenotypically diverse, which stamen length, corolla length, corolla diameter, calyx length, bract length, inflorescence length, calyx length and bracteole width were characteristics with the highest variation. Leaf dimensions were in significant correlation with flower and inflorescence characteristics. Chemical compounds of essential oils were found variable in various individuals and all samples were principally composed of phenolic constituents (carvacrol and/or thymol). As a consequence, the plants were classified into two major chemotypes including carvacrol and thymol. A total of 197 band positions were produced by 14 ISSR primers, of which 176 were found polymorphic with 88.91% polymorphism. ISSR genetic similarity values among individuals ranged between 0.45 and 0.94 which was indicative of a high level of genetic variation. Multiple regression analysis (MRA) revealed that phytochemical compositions as dependent variable, showed statistically significant correlation and in association with leaf and flower traits as independent variable, indicating a main role of leaf and flower on production of these compounds. Also, several ISSR fragments were found associated with some morphological traits and phytochemical compositions. The high diversity within and among populations of S. mutica according to different data systems could provide useful information for conservation and selection of cross-parents in breeding programs. PMID:24878369

  16. Chinese Consensus Statement on the Evaluation and Intervention of Collateral Circulation for Ischemic Stroke

    PubMed Central

    Liu, Li-Ping; Xu, An-Ding; Wong, Lawrence KS; Wang, David Z; Wang, Yong-Jun

    2014-01-01

    Background Collateral circulation is becoming more significant in the individual management strategy of ischemic stroke, there are more data updated recently. Aim To make the further acknowledgment of the evaluation and how to improving collateral flow, for better treatment selection. Method A panel of experts on stroke providing related statement based on review the results from most up-to-date clinical research. Results DSA is the gold standard in evaluating all levels of collaterals. CTA can be used for evaluating leptomeningeal collaterals, MRA for CoW, TCD or TCCS can be used as screening tool for primary evaluation. The treatment modalities include direct interventions, such as Extracranial–Intracranial bypass, and indirect interventions, as External counterpulsation and pressor therapy. The consideration of methodology to augment and improve can be considered on an individual basis. Discussion In this consensus, we interpret the definition, neuroimaging evaluation, intervention and potential strategy on collaterals in the future. Conclusion Assessment of collateral circulation is crucial for selecting therapeutic options, predicting infarction volume and making prognosis after ischemic stroke. Data is still needed to provide therapeutic evidence for many new developed technologies. Until more evidence is available, the clinical significance of applying the new technologies is unclear and perhaps limited. PMID:24495505

  17. The Membrane Steps of Bacterial Cell Wall Synthesis as Antibiotic Targets.

    PubMed

    Liu, Yao; Breukink, Eefjan

    2016-01-01

    Peptidoglycan is the major component of the cell envelope of virtually all bacteria. It has structural roles and acts as a selective sieve for molecules from the outer environment. Peptidoglycan synthesis is therefore one of the most important biogenesis pathways in bacteria and has been studied extensively over the last twenty years. The pathway starts in the cytoplasm, continues in the cytoplasmic membrane and finishes in the periplasmic space, where the precursor is polymerized into the peptidoglycan layer. A number of proteins involved in this pathway, such as the Mur enzymes and the penicillin binding proteins (PBPs), have been studied and regarded as good targets for antibiotics. The present review focuses on the membrane steps of peptidoglycan synthesis that involve two enzymes, MraY and MurG, the inhibitors of these enzymes and the inhibition mechanisms. We also discuss the challenges of targeting these two cytoplasmic membrane (associated) proteins in bacterial cells and the perspectives on how to overcome the issues. PMID:27571111

  18. Scale-adaptive tensor algebra for local many-body methods of electronic structure theory

    SciTech Connect

    Liakh, Dmitry I

    2014-01-01

    While the formalism of multiresolution analysis (MRA), based on wavelets and adaptive integral representations of operators, is actively progressing in electronic structure theory (mostly on the independent-particle level and, recently, second-order perturbation theory), the concepts of multiresolution and adaptivity can also be utilized within the traditional formulation of correlated (many-particle) theory which is based on second quantization and the corresponding (generally nonorthogonal) tensor algebra. In this paper, we present a formalism called scale-adaptive tensor algebra (SATA) which exploits an adaptive representation of tensors of many-body operators via the local adjustment of the basis set quality. Given a series of locally supported fragment bases of a progressively lower quality, we formulate the explicit rules for tensor algebra operations dealing with adaptively resolved tensor operands. The formalism suggested is expected to enhance the applicability and reliability of local correlated many-body methods of electronic structure theory, especially those directly based on atomic orbitals (or any other localized basis functions).

  19. Final report of EURAMET 1197: Supplementary bilateral comparison of hydraulic gauge pressure standards up to 50 MPa

    NASA Astrophysics Data System (ADS)

    Durgut, Yasin; Petrovski, Nenad; Kacarski, Vanco

    2012-01-01

    Interlaboratory comparisons are important for the laboratories to assess their own measurement capability. It is equally important for the accreditation bodies and assessors during the audit process of a laboratory to judge whether the laboratory is doing well. As per accreditation rules, it is mandatory for the testing and calibration laboratories to participate in such comparisons from time to time. In this report, results of the bilateral interlaboratory comparison in pressure area in hydraulic media up to 50 MPa gauge between UME (Turkey) and BOM (The FYR of Macedonia) are presented. The artefact used for the comparison was a digital pressure calibrator and its drift was taken into account in the calculation. Results show that all En values lie in acceptable limits. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by EURAMET, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  20. Intraosseous ganglion cyst of the humeral head in a competitive flat water paddler: case report

    PubMed Central

    Muir, Brad; Kissel, Jaclyn A.; Yedon, Dominique Forand

    2011-01-01

    Objective To present the diagnostic and clinical features of an intraosseous ganglion cyst of the humeral head of a female flat water canoe athlete. Clinical Features An 18-year old female flat water canoeist complaining of right shoulder pain following a strenuous paddling training camp. Intervention and outcome A trial of passive care was conducted, including soft tissue therapy, spinal manipulative therapy, acupuncture, and rehabilitation. The patient seemed to be responding with treatment, but pain would always resume with paddling. A diagnostic ultrasound displayed mild thickening and effusion in the subacromial/subdeltoid bursae. Continued passive care was not able to resolve the symptoms and she underwent an MRI which revealed an intraosseus ganglion cyst subjacent to the lesser tuberosity and floor of the intertubercular groove. A subsequent MRA was ordered to assess the labrum, which was intact, but the cyst had progressed in size. She was referred to an orthopedic surgeon who performed surgery. Conclusion An IOG cyst within the humeral head is a rare, potentially painful condition that can mimic other pathologies including impingement and labral tear. It is important to be aware of the clinical features to obtain a prompt diagnosis and appropriate treatment of this condition. PMID:22131566