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Sample records for jnis vtra mra

  1. JNIS podcasts: the early part of our journey.

    PubMed

    Hirsch, Joshua A; Fargen, Kyle; Ducruet, Andrew F; Tarr, Robert W

    2017-02-01

    Podcasts are an area of innovation in the neurointerventional space that has the potential to convey information in ways that traditional journal articles in peer-reviewed journals do not. BMJ maintains an archive of all of its podcasts on the Journal of NeuroInterventional Surgery (JNIS) website. We sought to analyze this early JNIS podcast experience and assess the impact of content elements and an increased presence in social media.

  2. Whole-Body MRA.

    PubMed

    Kramer, Harald; Quick, Harald H; Tombach, Bernd; Schoenberg, Stefan O; Barkhausen, Joerg

    2008-09-01

    Vascular diseases today constitute a serious health burden, ranking atherosclerosis as number one in the morbidity and mortality statistics of developed countries, with a still-growing incidence. Different treatment options are available for all vascular territories, ranging from conservative pharmacological treatment and catheter-based interventions up to surgical methods with remodelling of the vessels or bypass implantation. For treatment planning, all listed procedures have in common that they rely on initial diagnostic imaging to assess the degree and extent of stenoses. In this respect, imaging of the arterial system from the head down to the feet seems to be reasonable. Up to now no imaging technique allowed the assessment of the complete arterial system in only one exam within a reasonable time and without limiting factors like invasiveness and ionizing radiation. However, recent developments in magnetic resonance (MR) hardware and software, such as dedicated whole-body MR systems with specially designed surface coils, the movement to higher field strength and the implementation of parallel acquisition techniques (PAT), have helped to overcome the long-standing limitations of MR angiography (MRA), like reduced spatial resolution, long acquisition time, the restriction to body parts and only one field of view of a maximum 50 cm.

  3. Your Radiologist Explains Magnetic Resonance Angiography (MRA)

    MedlinePlus

    ... Sponsored by Image/Video Gallery Your Radiologist Explains Magnetic Resonance Angiography (MRA) Transcript Welcome to Radiology Info ... I’d like to talk with you about magnetic resonance angiography, or as it’s commonly known, MRA. ...

  4. 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...

  5. 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...

  6. 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

  7. Nonenhanced magnetic resonance angiography (MRA) of the calf arteries at 3 Tesla: intraindividual comparison of 3D flow-dependent subtractive MRA and 2D flow-independent non-subtractive MRA.

    PubMed

    Knobloch, Gesine; Lauff, Marie-Teres; Hirsch, Sebastian; Schwenke, Carsten; Hamm, Bernd; Wagner, Moritz

    2016-12-01

    To prospectively compare 3D flow-dependent subtractive MRA vs. 2D flow-independent non-subtractive MRA for assessment of the calf arteries at 3 Tesla. Forty-two patients with peripheral arterial occlusive disease underwent nonenhanced MRA of calf arteries at 3 Tesla with 3D flow-dependent subtractive MRA (fast spin echo sequence; 3D-FSE-MRA) and 2D flow-independent non-subtractive MRA (balanced steady-state-free-precession sequence; 2D-bSSFP-MRA). Moreover, all patients underwent contrast-enhanced MRA (CE-MRA) as standard-of-reference. Two readers performed a per-segment evaluation for image quality (4 = excellent to 0 = non-diagnostic) and severity of stenosis. Image quality scores of 2D-bSSFP-MRA were significantly higher compared to 3D-FSE-MRA (medians across readers: 4 vs. 3; p < 0.0001) with lower rates of non-diagnostic vessel segments on 2D-bSSFP-MRA (reader 1: <1 % vs. 15 %; reader 2: 1 % vs. 29 %; p < 0.05). Diagnostic performance of 2D-bSSFP-MRA and 3D-FSE-MRA across readers showed sensitivities of 89 % (214/240) vs. 70 % (168/240), p = 0.0153; specificities: 91 % (840/926) vs. 63 % (585/926), p < 0.0001; and diagnostic accuracies of 90 % (1054/1166) vs. 65 % (753/1166), p < 0.0001. 2D flow-independent non-subtractive MRA (2D-bSSFP-MRA) is a robust nonenhanced MRA technique for assessment of the calf arteries at 3 Tesla with significantly higher image quality and diagnostic accuracy compared to 3D flow-dependent subtractive MRA (3D-FSE-MRA). • 2D flow-independent non-subtractive MRA (2D-bSSFP-MRA) is a robust NE-MRA technique at 3T • 2D-bSSFP-MRA outperforms 3D flow-dependent subtractive MRA (3D-FSE-MRA) as NE-MRA of calf arteries • 2D-bSSFP-MRA is a promising alternative to CE-MRA for calf PAOD evaluation.

  8. The Highly Conserved MraZ Protein Is a Transcriptional Regulator in Escherichia coli

    PubMed Central

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

    2014-01-01

    The mraZ and mraW genes are highly conserved in bacteria, both in sequence and in their position at the head of the division and cell wall (dcw) gene cluster. Located directly upstream of the mraZ gene, the Pmra promoter drives the transcription of mraZ and mraW, as well as many essential cell division and cell wall genes, but no regulator of Pmra has been found to date. Although MraZ has structural similarity to the AbrB transition state regulator and the MazE antitoxin and MraW is known to methylate the 16S rRNA, mraZ and mraW null mutants have no detectable phenotypes. Here we show that overproduction of Escherichia coli MraZ inhibited cell division and was lethal in rich medium at high induction levels and in minimal medium at low induction levels. Co-overproduction of MraW suppressed MraZ toxicity, and loss of MraW enhanced MraZ toxicity, suggesting that MraZ and MraW have antagonistic functions. MraZ-green fluorescent protein localized to the nucleoid, suggesting that it binds DNA. Consistent with this idea, purified MraZ directly bound a region of DNA containing three direct repeats between Pmra and the mraZ gene. Excess MraZ reduced the expression of an mraZ-lacZ reporter, suggesting that MraZ acts as a repressor of Pmra, whereas a DNA-binding mutant form of MraZ failed to repress expression. Transcriptome sequencing (RNA-seq) analysis suggested that MraZ also regulates the expression of genes outside the dcw cluster. In support of this, purified MraZ could directly bind to a putative operator site upstream of mioC, one of the repressed genes identified by RNA-seq. PMID:24659771

  9. Nonenhanced ECG-gated quiescent-interval single shot MRA: image quality and stenosis assessment at 3 tesla compared with contrast-enhanced MRA and digital subtraction angiography.

    PubMed

    Hansmann, Jan; Morelli, John N; Michaely, Henrik J; Riester, Thomas; Budjan, Johannes; Schoenberg, Stefan O; Attenberger, Ulrike I

    2014-06-01

    To evaluate the diagnostic accuracy of a nonenhanced electrocardiograph-gated quiescent-interval single shot MR-angiography (QISS-MRA) at 3 Tesla with contrast-enhanced MRA (CE-MRA) and digital subtraction angiography (DSA) serving as reference standard. Following institutional review board approval, 16 consecutive patients with peripheral arterial disease underwent a combined peripheral MRA protocol consisting of a large field-of-view QISS-MRA, continuous table movement MRA, and an additional time-resolved MRA of the calves. DSA correlation was available in eight patients. Image quality and degree of stenosis was assessed. Sensitivity and specificity of QISS-MRA was evaluated with CE-MRA and DSA serving as the standards of reference and compared using the Fisher exact test. With the exception of the calf station, image quality with QISS-MRA was rated statistically significantly less than that of CE-MRA (P < 0.05, P = 0.17, and P = 0.6, respectively). A greater percentage of segments were not accessible with QISS-MRA (19.5-20.1%) in comparison to CE-MRA (10.9%). Relative to DSA, sensitivity for QISS-MRA was high (100% versus 91.2% for CE-MRA, P = 0.24) in the evaluated segments; however, specificity (76.5%) was substantially less than that of CE-MRA (94.6%, P = 0.003). Overall image quality and specificity of QISS-MRA at 3T are diminished relative to CE-MRA. However, when image quality is adequate, QISS-MRA has high sensitivity and, thus, has potential use in patients with contraindications to gadolinium. Copyright © 2013 Wiley Periodicals, Inc.

  10. mraY is an essential gene for cell growth in Escherichia coli.

    PubMed

    Boyle, D S; Donachie, W D

    1998-12-01

    The synthesis of the murein precursor lipid I is performed by MraY. We have shown that mraY is an essential gene for cell growth. Cells depleted of MraY first swell and then lyse. The expression of mraY DNA in vitro produces a 40-kDa polypeptide detectable by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

  11. Preprocedural MRI and MRA in planning fibroid embolization

    PubMed Central

    Maciel, Cristina; Tang, Yen Zhi; Sahdev, Anju; Madureira, António Miguel; Vilares-Morgado, Paulo

    2017-01-01

    This pictorial review aims to discuss and illustrate the up-to-date use of preprocedural magnetic resonance imaging (MRI) in selecting patients and planning uterine artery embolization (UAE). The merits of magnetic resonance angiography (MRA) in demonstrating the pelvic vasculature to guide UAE are highlighted. MRI features of fibroids and their main differential diagnoses are presented. Fibroid characteristics, such as location, size, and enhancement, which may impact patient selection and outcome, are presented based on recent literature. Pelvic arterial anatomy relevant to UAE, including vascular variants are illustrated, with conventional angiography and MRA imaging correlation. MRA preprocedural determination of the optimal projection angles for uterine artery catheterization is straightforward and constitutes an important strategy to minimize ionizing radiation exposure during UAE. A reporting template for MRI/MRA preassessement of UAE for fibroid treatment is provided. PMID:28163256

  12. 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.

  13. Bacterial transferase MraY inhibitors: synthesis and biological evaluation.

    PubMed

    Lecerclé, Delphine; Clouet, Anthony; Al-Dabbagh, Bayan; Crouvoisier, Muriel; Bouhss, Ahmed; Gravier-Pelletier, Christine; Le Merrer, Yves

    2010-06-15

    New inhibitors of the bacterial transferase MraY are described. Their structure is based on an aminoribosyl-O-uridine like scaffold, readily obtained in two key steps. The amino group can be coupled with proline or guanylated. Alternatively, these amino, prolinyl or guanidinyl groups can be introduced through a triazole linker. Biological evaluation of these compounds on MraY from Bacillus subtilis revealed interesting inhibitory activity for both amino compounds. Copyright 2010. Published by Elsevier Ltd.

  14. Pulmonary MRA: Differentiation of pulmonary embolism from truncation artifact

    PubMed Central

    Bannas, Peter; Schiebler, Mark L; Motosugi, Utaroh; François, Christopher J; Reeder, Scott B; Nagle, Scott K

    2015-01-01

    Purpose Truncation artifact (Gibbs ringing) causes central signal drop within vessels in pulmonary MRA that can be mistaken for emboli, reducing the diagnostic accuracy for pulmonary embolism (PE). We propose a quantitative approach to differentiate truncation artifact from PE. Methods Twenty-eight patients who underwent pulmonary CTA for suspected PE were recruited for pulmonary MRA. Signal intensity drops within pulmonary arteries that persisted on both arterial-phase and delayed-phase MRA were identified. The percent signal loss between the vessel lumen and central drop was measured. CTA served as the reference standard for presence of pulmonary emboli. Results A total of 65 signal intensity drops were identified on MRA. 48 (74%) of these were artifact and 17 (26%) were PE, as confirmed by CTA. Truncation artifacts had a significantly lower median signal drop than PE at both arterial-phase (26% [range 12–58%] vs. 85% [range 53–91%]) and at delayed-phase MRA (26% [range 11–55%] vs. 77% [range 47–89%]), p<0.0001 for both. ROC analyses revealed a threshold value of 51% (arterial-phase) and 47%-signal drop (delayed-phase) to differentiate between truncation artifact and PE with 100% sensitivity and >90% specificity. Conclusion Quantitative signal drop is an objective tool to help differentiate truncation artifact and pulmonary embolism in pulmonary MRA. PMID:24863886

  15. 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

  16. 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.

  17. Structural Investigation of Park's Nucleotide on Bacterial Translocase MraY: Discovery of Unexpected MraY Inhibitors.

    PubMed

    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

    2016-08-17

    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.

  18. 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

  19. Role of MRA in the detection of intracranial aneurysm in the acute phase of subarachnoid hemorrhage.

    PubMed

    Pierot, Laurent; Portefaix, Christophe; Rodriguez-Régent, Christine; Gallas, Sophie; Meder, Jean-François; Oppenheim, Catherine

    2013-07-01

    Magnetic resonance angiography (MRA) has been evaluated for the detection of unruptured intracranial aneurysms with favorable results at 3 Tesla (3T) and with similar diagnostic accuracy as both 3D time-of-flight (3D-TOF) and contrast-enhanced (CE-MRA) MRA. However, the diagnostic value and place of MRA in the detection of ruptured aneurysms has been little evaluated. Thus, the goal of this prospective single-center series was to assess the feasibility and diagnostic value of 3T 3D-TOF MRA and CE-MRA for aneurysm detection in acute non-traumatic subarachnoid hemorrhage (SAH). From March 2006 to December 2007, all consecutive patients admitted to our hospital with acute non-traumatic SAH (≤10 days) were prospectively included in this study evaluating MRA in the diagnostic workup of SAH. Feasibility of MRA and sensitivity/specificity of 3D-TOF and CE-MRA were assessed compared with gold standard DSA. In all, 84 consecutive patients (45 women, 39 men; age 23-86 years) were included. The feasibility of MRA was low (43/84, 51.2%). The reasons given for patients not undergoing magnetic resonance imaging (MRI) examination were clinical status (27 patients), potential delay in aneurysm treatment (11 patients) and contraindications to MRI (three patients). In patients explored by MRA, the sensitivity of CE-MRA (95%) was higher compared with 3D-TOF (86%) with similar specificity (80%). Also, 3D-TOF missed five aneurysms while CE-MRA missed two. The value of MRA in the diagnostic workup of ruptured aneurysms is limited due to its low feasibility during the acute phase of bleeding. Sensitivity for aneurysm detection was good for both MRA techniques, but tended to be better with CE-MRA. Copyright © 2013. Published by Elsevier Masson SAS.

  20. mraY Is an Essential Gene for Cell Growth in Escherichia coli

    PubMed Central

    Boyle, David S.; Donachie, William D.

    1998-01-01

    The synthesis of the murein precursor lipid I is performed by MraY. We have shown that mraY is an essential gene for cell growth. Cells depleted of MraY first swell and then lyse. The expression of mraY DNA in vitro produces a 40-kDa polypeptide detectable by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. PMID:9829961

  1. 5 CFR 870.708 - MRA-plus-10 annuitants.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 5 Administrative Personnel 2 2010-01-01 2010-01-01 false MRA-plus-10 annuitants. 870.708 Section 870.708 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT (CONTINUED) CIVIL SERVICE REGULATIONS (CONTINUED) FEDERAL EMPLOYEES' GROUP LIFE INSURANCE PROGRAM Annuitants and Compensationers § 870.708...

  2. From MIP image to MRA segmentation using fuzzy set theory.

    PubMed

    Vermandel, Maximilien; Betrouni, Nacim; Taschner, Christian; Vasseur, Christian; Rousseau, Jean

    2007-04-01

    The aim of this paper is to describe a semi-automatic method of segmentation in magnetic resonance angiography (MRA). This method, based on fuzzy set theory, uses the information (gray levels) contained in the maximum intensity projection (MIP) image to segment the 3D vascular structure from slices. Tests have been carried out on vascular phantom and on clinical MRA images. This 3D segmentation method has proved to be satisfactory for the detection of vascular structures even for very complex shapes. Finally, this MIP-based approach is semi-automatic and produces a robust segmentation thanks to the contrast-to-noise ratio and to the slice profile which are taken into account to determine the membership of a voxel to the vascular structure.

  3. Noncontrast MR Angiography (MRA) of Infragenual Arteries Using Flow-Sensitive Dephasing (FSD)-Prepared Steady-State Free Precession (SSFP) at 3.0T: Comparison with Contrast-Enhanced MRA

    PubMed Central

    Zhang, Nan; Fan, Zhaoyang; Luo, Nan; Bi, Xiaoming; Zhao, Yike; An, Jing; Liu, Jiayi; Chen, Zhong; Fan, Zhanming; Li, Debiao

    2015-01-01

    Purpose To evaluate the feasibility and diagnostic performance of flow-sensitive dephasing (FSD)-prepared steady-state free precession (SSFP) MR angiography (MRA) for imaging infragenual arteries at 3.0T, with contrast enhanced MR angiography (CE MRA) as reference. Materials And Methods Twenty consecutive patients with suspicion of lower extremity arterial disease undergoing routine CE MRA were recruited. FSD MRA was performed at calf before CE MRA. Image quality and stenosis degree of infragenual arteries from both techniques were independently evaluated and compared. Six patients in this study underwent DSA examination. Results Three undiagnostic segments were excluded with severe venous contamination in CE MRA. A total of 197 calf arterial segments images were analyzed. No significant difference existed in the relative signal intensity (rSI) of arterial segments between FSD MRA and CE MRA techniques (0.92±0.09 vs. 0.93±0.05; P=0.207). However, the subjective image quality score was slightly higher in FSD MRA (3.66±0.81 vs. 3.49±0.87; P=0.050). With CE MRA images as reference standard, slight overestimation existed in FSD MRA (2.19±1.24 vs. 2.09±1.18; P=0.019), with total agreement of 84.3% on the basis of all arterial segments. The sensitivity, specificity, NPV, and PPV of FSD MRA was 96.4%, 93.0%, 98.5%, and 84.1%. No significant difference in the stenosis degree score was detected between MRA (FSD MRA and CE MRA) and DSA (P > 0.05). Conclusion FSD MRA performed on at 3.0Twithout the use of contrast medium provides diagnostic images allowing for arterial stenosis assessment of calf arteries that was highly comparable with CE MRA. Moreover, venous contamination was less problematic with FSD MRA. PMID:26185106

  4. Signal quality of single dose gadobenate dimeglumine pulmonary MRA examinations exceeds quality of MRA performed with double dose gadopentetate dimeglumine

    PubMed Central

    Chenevert, Thomas L.; Sostman, H. Dirk; Jablonski, Kathleen A.; Stein, Paul D.; Goodman, Lawrence R.; Londy, Frank J.; Narra, Vamsidhar; Hales, Charles A.; Hull, Russell D.; Tapson, Victor F.; Weg, John G.

    2011-01-01

    During a recent multi-center trial assessing gadolinium (Gd)-enhanced magnetic resonance angiography (MRA) for diagnosis of acute pulmonary embolism (PE), the Food and Drug Administration announced a risk of nephrogenic sclerosing fibrosis in patients with renal insufficiency who had received intravenous Gd-based MR contrast agents. Although no patients in this trial had renal insufficiency, in cautious response to this announcement, the trial protocol was changed from an intravenous administration of 0.2 mmol/Kg of a conventional Gd-based MR contrast agent to 0.1 mmol/Kg of gadobenate dimeglumine. The study described herein compares the signal quality of pulmonary MRA performed with double dose conventional agent to single dose gadob-enate dimeglumine. This study is a retrospective analysis of data from a prospective, multicenter study in men and women ≥18 years with documented presence or absence of PE. The study was approved by the Institutional Review Board at all participating centers, and all patients provided written indication of informed consent. We performed both objective and subjective analysis of pulmonary artery image quality. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) in the main pulmonary artery were assessed in single and double dose protocols and compared. SNR and CNR of the main PA were correlated with subjective quality assessment of main/lobar, segmental and subsegmental pulmonary arteries. Although there were individual outliers, both SNR (P = 0.01) and CNR (P = 0.008) were higher in all quartiles for examinations using gadobenate dimeglumine than with gadopentetate dimeglumine. Subjective quality of vascular signal intensity at each vessel order was significantly better for gadobenate dimeglumine (P < 0.0001), and correlated well with SNR and CNR at each order (<0.001). Because of agent high relaxivity, a single dose of gadobenate dimeglumine provides better pulmonary MRA signal quality than double dose of a conventional

  5. A new visualization method for 3D head MRA data

    NASA Astrophysics Data System (ADS)

    Ohashi, Satoshi; Hatanaka, Masahiko

    2008-03-01

    In this paper, we propose a new visualization method for head MRA data which supports the user to easily determine the positioning of MPR images and/or MIP images based on the blood vessel network structure (the anatomic location of blood vessels). This visualization method has following features: (a) the blood vessel (cerebral artery) network structure in 3D head MRA data is portrayed the 3D line structure; (b) the MPR or MIP images are combined with the blood vessel network structure and displayed in a 3D visualization space; (c) the positioning of MPR or MIP is decided based on the anatomic location of blood vessels; (d) The image processing and drawing can be operated at real-time without a special hardware accelerator. As a result, we believe that our method is available to position MPR images or MIP images related to the blood vessel network structure. Moreover, we think that the user using this method can obtain the 3D information (position, angle, direction) of both these images and the blood vessel network structure.

  6. Genetic Analysis of MraY Inhibition by the φX174 Protein E

    PubMed Central

    Zheng, Yi; Struck, Douglas K.; Bernhardt, Thomas G.; Young, Ry

    2008-01-01

    Protein E, the lysis protein of bacteriophage φX174, is a specific inhibitor of MraY, the phospho-MurNAc-pentapeptide translocase that catalyzes the synthesis of lipid I in the conserved pathway for peptidoglycan biosynthesis. The original evidence for this inhibition was the isolation of two spontaneous E-resistance mraY mutants. Here we report further genetic studies aimed at dissecting the interaction between E and MraY, using a genetic strategy that is facile, rapid, and does not depend on the availability of purified E, purified MraY, or its substrates. This system relies on the ability of mraY or its enzymatically inactive D267N allele to protect cells from lysis after induction of a chimeric λ∷E prophage. Using this approach, the MraY protein from Bacillus subtilis, which shares 43% sequence identity with the Escherichia coli enzyme, was found to interact weakly, if at all, with E. A potential E binding site defined by transmembrane domains 5 and 9 has been identified by isolating more mraY mutants resistant to E inhibition. Genetic analysis indicates that these E-resistant alleles fall into three classes on the basis of the affinity of the encoded proteins for MraY. PMID:18791230

  7. Genetic analysis of MraY inhibition by the phiX174 protein E.

    PubMed

    Zheng, Yi; Struck, Douglas K; Bernhardt, Thomas G; Young, Ry

    2008-11-01

    Protein E, the lysis protein of bacteriophage phiX174, is a specific inhibitor of MraY, the phospho-MurNAc-pentapeptide translocase that catalyzes the synthesis of lipid I in the conserved pathway for peptidoglycan biosynthesis. The original evidence for this inhibition was the isolation of two spontaneous E-resistance mraY mutants. Here we report further genetic studies aimed at dissecting the interaction between E and MraY, using a genetic strategy that is facile, rapid, and does not depend on the availability of purified E, purified MraY, or its substrates. This system relies on the ability of mraY or its enzymatically inactive D267N allele to protect cells from lysis after induction of a chimeric lambda :: E prophage. Using this approach, the MraY protein from Bacillus subtilis, which shares 43% sequence identity with the Escherichia coli enzyme, was found to interact weakly, if at all, with E. A potential E binding site defined by transmembrane domains 5 and 9 has been identified by isolating more mraY mutants resistant to E inhibition. Genetic analysis indicates that these E-resistant alleles fall into three classes on the basis of the affinity of the encoded proteins for MraY.

  8. Inter- and Intrarater Agreement on the Outcome of Endovascular Treatment of Aneurysms Using MRA.

    PubMed

    Jamali, S; Fahed, R; Gentric, J-C; Letourneau-Guillon, L; Raoult, H; Bing, F; Estrade, L; Nguyen, T N; Tollard, É; Ferre, J-C; Iancu, D; Naggara, O; Chagnon, M; Weill, A; Roy, D; Fox, A J; Kallmes, D F; Raymond, J

    2016-05-01

    Patients treated with coiling are often followed by MR angiography. Our objective was to assess the inter- and intraobserver agreement in diagnosing aneurysm remnants and recurrences by using multimodality imaging, including TOF MRA. A portfolio composed of 120 selected images from 56 patients was sent to 15 neuroradiologists from 10 institutions. For each case, raters were asked to classify angiographic results (3 classes) of 2 studies (32 MRA-MRA and 24 DSA-MRA pairs) and to provide a final judgment regarding the presence of a recurrence (no, minor, major). Six raters were asked to independently review the portfolio twice. A second study, restricted to 4 raters having full access to all images, was designed to validate the results of the electronic survey. The proportion of cases judged to have a major recurrence varied between 16.1% and 71.4% (mean, 35.0% ± 12.7%). There was moderate agreement overall (κ = 0.474 ± 0.009), increasing to nearly substantial (κ = 0.581 ± 0.014) when the judgment was dichotomized (presence or absence of a major recurrence). Agreement on cases followed-up by MRA-MRA was similarly substantial (κ = 0.601 ± 0.018). The intrarater agreement varied between fair (κ = 0.257 ± 0.093) and substantial (κ= 0.699 ± 0.084), improving with a dichotomized judgment concerning MRA-MRA comparisons. Agreement was no better when raters had access to all images. There is an important variability in the assessment of angiographic outcomes of endovascular treatments. Agreement on the presence of a major recurrence when comparing 2 MRA studies or the MRA with the last catheter angiographic study can be substantial. © 2016 by American Journal of Neuroradiology.

  9. MraY Inhibitors as Novel Antibacterial Agents.

    PubMed

    Dini, Christophe

    2005-01-01

    MraY presents all necessary biological requirements to be considered as a target of interest for the discovery of novel antibacterials. Furthermore, several inhibitors aimed at this enzyme have been discovered. Amphomycin, which is currently used as a topical antibacterial in the veterinary industry is one of them, but the major source of future developments resides in the nucleoside based inhibitors group. This group has been subdivided into classes: Tunicamycins, Ribosamino-uridines, Uridylpeptides and Capuramycins. Analysis of pharmacological behaviours observed with several compounds within these classes, shows that broad-spectrum antibacterial activity, including relevant resistant strains and in vivo efficacy without toxicity are achievable. Among them, Caprazamycins, Muraymycins, Riburamycins and Capuramycins present the most promising profiles.

  10. A statistical cerebroarterial atlas derived from 700 MRA datasets.

    PubMed

    Forkert, N D; Fiehler, J; Suniaga, S; Wersching, H; Knecht, S; Kemmling, A

    2013-01-01

    The cerebroarterial system is a complex network of arteries that supply the brain cells with vitally important nutrients and oxygen. The inter-individual differences of the cerebral arteries, especially at a finer level, are still not understood sufficiently. The aim of this work is to present a statistical cerebroarterial atlas that can be used to overcome this problem. Overall, 700 Time-of-Flight (TOF) magnetic resonance angiography (MRA) datasets of healthy subjects were used for atlas generation. Therefore, the cerebral arteries were automatically segmented in each dataset and used for a quantification of the vessel diameters. After this, each TOF MRA dataset as well as the corresponding vessel segmentation and vessel diameter dataset were registered to the MNI brain atlas. Finally, the registered datasets were used to calculate a statistical cerebroarterial atlas that incorporates information about the average TOF intensity, probability for a vessel occurrence and mean vessel diameter for each voxel. Visual analysis revealed that arteries with a diameter as small as 0.5 mm are well represented in the atlas with quantitative values that are within range of anatomical reference values. Moreover, a highly significant strong positive correlation between the vessel diameter and occurrence probability was found. Furthermore, it was shown that an intensity-based automatic segmentation of cerebral vessels can be considerable improved by incorporating the atlas information leading to results within the range of the inter-observer agreement. The presented cerebroarterial atlas seems useful for improving the understanding about normal variations of cerebral arteries, initialization of cerebrovascular segmentation methods and may even lay the foundation for a reliable quantification of subtle morphological vascular changes.

  11. Topological analysis of the MraY protein catalysing the first membrane step of peptidoglycan synthesis.

    PubMed

    Bouhss, A; Mengin-Lecreulx, D; Le Beller, D; Van Heijenoort, J

    1999-11-01

    The two-dimensional membrane topology of the Escherichia coli and Staphylococcus aureus MraY transferases, which catalyse the formation of the first lipid intermediate of peptidoglycan synthesis, was established using the beta-lactamase fusion system. All 28 constructed mraY-blaM fusions produced hybrid proteins. Analysis of the ampicillin resistance of the strains with hybrids led to a common topological model possessing 10 transmembrane segments, five cytoplasmic domains and six periplasmic domains including the N- and C-terminal ends. The agreement between the topologies of E. coli and S. aureus, their agreement to a fair extent with predicted models and a number of features arising from the comparative analysis of 25 orthologue sequences strongly suggested the validity of the model for all eubacterial MraYs. The primary structure of the 10 transmembrane segments diverged among orthologues, but they retained their hydrophobicity, number and size. The similarity of the sequences and distribution of the five cytoplasmic domains in both models, as well as their conservation among the MraY orthologues, clearly suggested their possible involvement in substrate recognition and in the catalytic process. Complementation tests showed that only fusions with untruncated mraY restored growth. It was noteworthy that S. aureus MraY was functional in E. coli. An increased MraY transferase activity was observed only with the untruncated hybrids from both organisms.

  12. Crystal structure of MraY, an essential membrane enzyme for bacterial cell wall synthesis.

    PubMed

    Chung, Ben C; Zhao, Jinshi; Gillespie, Robert A; Kwon, Do-Yeon; Guan, Ziqiang; Hong, Jiyong; Zhou, Pei; Lee, Seok-Yong

    2013-08-30

    MraY (phospho-MurNAc-pentapeptide translocase) is an integral membrane enzyme that catalyzes an essential step of bacterial cell wall biosynthesis: the transfer of the peptidoglycan precursor phospho-MurNAc-pentapeptide to the lipid carrier undecaprenyl phosphate. MraY has long been considered a promising target for the development of antibiotics, but the lack of a structure has hindered mechanistic understanding of this critical enzyme and the enzyme superfamily in general. The superfamily includes enzymes involved in bacterial lipopolysaccharide/teichoic acid formation and eukaryotic N-linked glycosylation, modifications that are central in many biological processes. We present the crystal structure of MraY from Aquifex aeolicus (MraYAA) at 3.3 Å resolution, which allows us to visualize the overall architecture, locate Mg(2+) within the active site, and provide a structural basis of catalysis for this class of enzyme.

  13. Fluorescence detection-based functional assay for high-throughput screening for MraY.

    PubMed

    Stachyra, Thérèse; Dini, Christophe; Ferrari, Paul; Bouhss, Ahmed; van Heijenoort, Jean; Mengin-Lecreulx, Dominique; Blanot, Didier; Biton, Jacques; Le Beller, Dominique

    2004-03-01

    We have developed a novel assay specific to MraY, which catalyzes the first membrane step in the biosynthesis of bacterial cell wall peptidoglycan. This was accomplished by using UDP-MurNAc-N(epsilon)-dansylpentapeptide, a fluorescent derivative of the MraY nucleotide substrate, and a partially purified preparation of MraY solubilized from membranes of an Escherichia coli overproducing strain. Two versions of the assay were developed, one consisting of the high-pressure liquid chromatography separation of the substrate and product (dansylated lipid I) and the other, without separation and adapted to the high-throughput format, taking advantage of the different fluorescence properties of the nucleotide and lipid I in the reaction medium. The latter assay was validated with a set of natural and synthetic MraY inhibitors.

  14. Fluorescence Detection-Based Functional Assay for High-Throughput Screening for MraY

    PubMed Central

    Stachyra, Thérèse; Dini, Christophe; Ferrari, Paul; Bouhss, Ahmed; van Heijenoort, Jean; Mengin-Lecreulx, Dominique; Blanot, Didier; Biton, Jacques; Le Beller, Dominique

    2004-01-01

    We have developed a novel assay specific to MraY, which catalyzes the first membrane step in the biosynthesis of bacterial cell wall peptidoglycan. This was accomplished by using UDP-MurNAc-Nɛ-dansylpentapeptide, a fluorescent derivative of the MraY nucleotide substrate, and a partially purified preparation of MraY solubilized from membranes of an Escherichia coli overproducing strain. Two versions of the assay were developed, one consisting of the high-pressure liquid chromatography separation of the substrate and product (dansylated lipid I) and the other, without separation and adapted to the high-throughput format, taking advantage of the different fluorescence properties of the nucleotide and lipid I in the reaction medium. The latter assay was validated with a set of natural and synthetic MraY inhibitors. PMID:14982781

  15. Crystal Structure of MraY, an Essential Membrane Enzyme for Bacterial Cell Wall Synthesis

    PubMed Central

    Chung, Ben C.; Kwon, Do-Yeon; Guan, Ziqiang; Hong, Jiyong; Zhou, Pei; Lee, Seok-Yong

    2013-01-01

    MraY (phospho-MurNAc-pentapeptide translocase) is an integral membrane enzyme that catalyzes an essential step of bacterial cell wall biosynthesis: the transfer of the peptidoglycan precursor phospho-MurNAc-pentapeptide to the lipid carrier undecaprenyl phosphate. MraY has long been considered a promising target for the development of antibiotics, but the lack of a structure has hindered mechanistic understanding of this critical enzyme and the enzyme superfamily in general. The superfamily includes enzymes involved in bacterial lipopolysaccharide/teichoic acid formation and eukaryotic N-linked glycosylation, modifications that are central in many biological processes. We present the crystal structure of MraY from Aquifex aeolicus (MraYAA) at 3.3 Å resolution, which allows us to visualize the overall architecture, locate Mg2+ within the active site, and provide a structural basis of catalysis for this class of enzyme. PMID:23990562

  16. 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.

  17. Noncontrast MR angiography (MRA) of infragenual arteries using flow-sensitive dephasing (FSD)-prepared steady-state free precession (SSFP) at 3.0 Tesla: Comparison with contrast-enhanced MRA.

    PubMed

    Zhang, Nan; Fan, Zhaoyang; Luo, Nan; Bi, Xiaoming; Zhao, Yike; An, Jing; Liu, Jiayi; Chen, Zhong; Fan, Zhanming; Li, Debiao

    2016-02-01

    To evaluate the feasibility and diagnostic performance of flow-sensitive dephasing (FSD)-prepared steady-state free precession (SSFP) MR angiography (MRA) for imaging infragenual arteries at 3.0T, with contrast enhanced MR angiography (CE MRA) as reference. Twenty consecutive patients with suspicion of lower extremity arterial disease undergoing routine CE MRA were recruited. FSD MRA was performed at calf before CE MRA. Image quality and stenosis degree of infragenual arteries from both techniques were independently evaluated and compared. Six patients in this study underwent DSA examination. Three undiagnostic segments were excluded with severe venous contamination in CE MRA. A total of 197 calf arterial segments images were analyzed. No significant difference existed in the relative signal intensity (rSI) of arterial segments between FSD MRA and CE MRA techniques (0.92 ± 0.09 versus 0.93 ± 0.05; P = 0.207). However, the subjective image quality score was slightly higher in FSD MRA (3.66 ± 0.81 versus 3.49 ± 0.87; P = 0.050). With CE MRA images as reference standard, slight overestimation existed in FSD MRA (2.19 ± 1.24 versus 2.09 ± 1.18; P = 0.019), with total agreement of 84.3% on the basis of all arterial segments. The sensitivity, specificity, negative predictive value, and positive predictive value of FSD MRA was 96.4%, 93.0%, 98.5%, and 84.1%. No significant difference in the stenosis degree score was detected between MRA (FSD MRA and CE MRA) and DSA (P > 0.05). FSD MRA performed on at 3.0T without the use of contrast medium provides diagnostic images allowing for arterial stenosis assessment of calf arteries that was highly comparable with CE MRA. Moreover, venous contamination was less problematic with FSD MRA. © 2015 Wiley Periodicals, Inc.

  18. MraY-antibiotic complex reveals details of tunicamycin mode of action.

    PubMed

    Hakulinen, Jonna K; Hering, Jenny; Brändén, Gisela; Chen, Hongming; Snijder, Arjan; Ek, Margareta; Johansson, Patrik

    2017-03-01

    The rapid increase of antibiotic resistance has created an urgent need to develop novel antimicrobial agents. Here we describe the crystal structure of the promising bacterial target phospho-N-acetylmuramoyl-pentapeptide translocase (MraY) in complex with the nucleoside antibiotic tunicamycin. The structure not only reveals the mode of action of several related natural-product antibiotics but also gives an indication on the binding mode of the MraY UDP-MurNAc-pentapeptide and undecaprenyl-phosphate substrates.

  19. Total Synthesis of Dansylated Park's Nucleotide for High-Throughput MraY Assays.

    PubMed

    Wohnig, Stephanie; Spork, Anatol P; Koppermann, Stefan; Mieskes, Gottfried; Gisch, Nicolas; Jahn, Reinhard; Ducho, Christian

    2016-12-05

    The membrane protein translocase I (MraY) is a key enzyme in bacterial peptidoglycan biosynthesis. It is therefore frequently discussed as a target for the development of novel antibiotics. The screening of compound libraries for the identification of MraY inhibitors is enabled by an established fluorescence-based MraY assay. However, this assay requires a dansylated derivative of the bacterial biosynthetic intermediate Park's nucleotide as the MraY substrate. Isolation of Park's nucleotide from bacteria and subsequent dansylation only furnishes limited amounts of this substrate, thus hampering the high-throughput screening for MraY inhibitors. Accordingly, the efficient provision of dansylated Park's nucleotide is a major bottleneck in the exploration of this promising drug target. In this work, we present the first total synthesis of dansylated Park's nucleotide, affording an unprecedented amount of the target compound for high-throughput MraY assays. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. MraZ from Escherichia coli: cloning, purification, crystallization and preliminary X-ray analysis

    SciTech Connect

    Adams, Melanie A.; Udell, Christian M.; Pal, Gour Pada; Jia, Zongchao

    2005-04-01

    The crystallization and preliminary X-ray diffraction analysis of MraZ, formerly known as hypothetical protein YabB, from Escherichia coli K-12 is presented. The MraZ family of proteins, also referred to as the UPF0040 family, are highly conserved in bacteria and are thought to play a role in cell-wall biosynthesis and cell division. The murein region A (mra) gene cluster encodes MraZ proteins along with a number of other proteins involved in this complex process. To date, there has been no clear functional assignment provided for MraZ proteins and the structure of a homologue from Mycoplasma pneumoniae, MPN314, failed to suggest a molecular function. The b0081 gene from Escherichia coli that encodes the MraZ protein was cloned and the protein was overexpressed, purified and crystallized. This data is presented along with evidence that the E. coli homologue exists in a different oligomeric state to the MPN314 protein.

  1. Noncontrast dynamic MRA in intracranial arteriovenous malformation (AVM), comparison with time of flight (TOF) and digital subtraction angiography (DSA).

    PubMed

    Yu, Songlin; Yan, Lirong; Yao, Yuqiang; Wang, Shuo; Yang, Mingqi; Wang, Bo; Zhuo, Yan; Ai, Lin; Miao, Xinyuan; Zhao, Jizong; Wang, Danny J J

    2012-07-01

    Digital subtraction angiography (DSA) remains the gold standard to diagnose intracranial arteriovenous malformations (AVMs) but is invasive. Existing magnetic resonance angiography (MRA) is suboptimal for assessing the hemodynamics of AVMs. The objective of this study was to evaluate the clinical utility of a novel noncontrast four-dimensional (4D) dynamic MRA (dMRA) in the evaluation of intracranial AVMs through comparison with DSA and time-of-flight (TOF) MRA. Nineteen patients (12 women, mean age 26.2±10.7 years) with intracranial AVMs were examined with 4D dMRA, TOF and DSA. Spetzler-Martin grading scale was evaluated using each of the above three methods independently by two raters. Diagnostic confidence scores for three components of AVMs (feeding artery, nidus and draining vein) were also rated. Kendall's coefficient of concordance was calculated to evaluate the reliability between two raters within each modality (dMRA, TOF, TOF plus dMRA). The Wilcoxon signed-rank test was applied to compare the diagnostic confidence scores between each pair of the three modalities. dMRA was able to detect 16 out of 19 AVMs, and the ratings of AVM size and location matched those of DSA. The diagnostic confidence scores by dMRA were adequate for nidus (3.5/5), moderate for feeding arteries (2.5/5) and poor for draining veins (1.5/5). The hemodynamic information provided by dMRA improved diagnostic confidence scores by TOF MRA. As a completely noninvasive method, 4D dMRA offers hemodynamic information with a temporal resolution of 50-100 ms for the evaluation of AVMs and can complement existing methods such as DSA and TOF MRA. Copyright © 2012 Elsevier Inc. All rights reserved.

  2. Comparison of imaging value for diabetic lower extremity arterial disease between FBI and CE-MRA.

    PubMed

    Yi, C-Y; Zhou, D-X; Li, H-H; Wang, Y; Chen, K; Chen, J; Huang, B-C; Xu, X-L

    2016-07-01

    This study adopted self-control study method to assess the efficacy of fresh blood imaging (FBI) and contrast-enhanced MR angiography (CE-MRA) for patients with diabetic lower extremity arterial disease (DLEAD) (Fontaine stage I to IV), and to evaluate the imaging of lower extremity peripheral arterial disease (PAD) in different stages of diabetes mellitus (DM). 1. This study recruited 44 diabetic patients with suspected lower extremity PAD to take both FBI and CE-MRA. 2. Two experienced cardiovascular radiologists assessed the image quality, the detection of lower extremity arterial branches, and tissue contamination (veins, arteries, and soft tissues) of FBI and CE-MRA, as well as the presence and severity of stenotic lesions. 3. Statistical differences of the quality of FBI and CE-MRA were determined using paired t-test. 4. Correlation analysis was adopted for determining the direction and strength of the relationship between the changes of the indexes of FBI and the different Fontaine stages. 1. The quality evaluation results of the image of lower extremity arteries from the 44 diabetic patients indicated no statistically significant difference between FBI and CE-MRA in the patients with Fontaine stage I-III (p >0.05). However, a statistically significant difference was observed in the patients with Fontaine stage IV (p <0.05), and the quality of FBI was slightly worse. 2. Arterial branches that observed from FBI and CE-MRA were 885 and 904, respectively. There was no statistically significant difference for the arterial branches between FBI and CE-MRA in the patients with Fontaine stage I-III (p >0.05). However, a statistically significant difference was observed in the patients with Fontaine stage IV (p <0.05), and CE-MRA indicated more artery branches than FBI. 3. There was a statistically significant difference for the evaluation of venous contamination between FBI and CE-MRA (p <0.05), and there was less venous contamination using FBI. 4. The study results

  3. Peripheral arterial disease in a symptomatic diabetic population: prospective comparison of rapid unenhanced MR angiography (MRA) with contrast-enhanced MRA.

    PubMed

    Hodnett, Philip A; Ward, Emily V; Davarpanah, Amir H; Scanlon, Timothy G; Collins, Jeremy D; Glielmi, Christopher B; Bi, Xiaoming; Koktzoglou, Ioannis; Gupta, Navyash; Carr, James C; Edelman, Robert R

    2011-12-01

    The joint guidelines of the American College of Cardiology and American Heart Association support the use of contrast-enhanced MR angiography (CEMRA) to diagnose the location and degree of stenosis in patients with known or suspected peripheral arterial disease (PAD). The high prevalence of chronic renal impairment in diabetic patients with PAD and the need for high doses of gadolinium-based contrast agents place them at risk for nephrogenic systemic fibrosis. The purpose of our study was to evaluate the accuracy of the rapid technique of quiescent-interval single-shot (QISS) unenhanced MR angiography (MRA) compared with CEMRA for the diagnosis in diabetic patients referred with symptomatic chronic PAD. This prospective two-center study evaluated 25 consecutive diabetic patients with documented or suspected symptomatic PAD. Both centers used identical imaging protocols. Images were independently analyzed by two radiologists. A subgroup analysis was performed of patients who were also assessed with digital subtraction angiography (DSA) as part of the standard-of-care protocol before revascularization. For this study, 775 segments were analyzed. On a per-segment basis, the mean values of the diagnostic accuracy of unenhanced MRA compared with reference CEMRA for two reviewers, reviewers 1 and 2, were as follows: sensitivity, 87.4% and 92.1%; specificity, 96.8% and 96.0%; positive predictive value, 90.8% and 94.0%; and negative predictive value, 95.5% and 94.6%. Substantial agreement was found when overall DSA results were compared with QISS unenhanced MRA (κ = 0.68) and CEMRA (κ = 0.63) in the subgroup of patients who also underwent DSA. There was almost perfect agreement between the two readers for stenosis scores, with Cohen's kappa values being greater than 0.80 for both MRA techniques. The results of our study indicate that QISS unenhanced MRA is an accurate noncontrast alternative to CEMRA for showing clinically significant arterial disease in patients with

  4. Correlation of preoperative MRI and MRA with arthroscopically proven articular cartilage lesions of the elbow.

    PubMed

    Theodoropoulos, John S; Dwyer, Tim; Wolin, Preston M

    2012-09-01

    The purpose of this study was to evaluate the usefulness of magnetic resonance imaging (MRI) in detecting elbow articular cartilage injuries through comparison of preoperative MRI and magnetic resonance arthrography (MRA) with arthroscopic findings. Retrospective case analysis. Tertiary care orthopedic private practice. Consecutive series of 31 patients presenting with elbow pain and diagnosed at arthroscopy with articular cartilage defects of the elbow. All patients had a preoperative MRI or MRA using a 1.5 T magnet. Each patient had a systematic elbow arthroscopy, with careful inspection and recording of chondral injuries in 4 anatomical regions: capitellum, radius, trochlea, and ulna. Each MRI/MRA was then independently reviewed by 2 radiologists blinded to the arthroscopic findings. The sensitivity, specificity, negative predictive value, positive predictive value, and accuracy were calculated for MRI and MRI compared with arthroscopy as the gold standard, for each of the anatomical regions. The accuracy of MRI was 45% for chondral injuries of the radius, 65% for the capitellum, 20% for the ulna, and 30% for the trochlea. The accuracy of MRA was 45% for chondral injuries of the radius, 64% for the capitellum, 18% for the ulna, and 27% for the trochlea. We conclude that the ability of MRI and MRA using a 1.5 T magnet to detect articular cartilage lesions is limited. Neither MRI nor MRA demonstrates the intraarticular surface as accurately as direct visualization with the arthroscopy. This may be improved with the use of 3 T MRI. This study demonstrates that MRI and MRA with a 1.5 T magnet, as used in community practice, have limited ability to detect cartilage lesions of the elbow.

  5. Diagnosis of rotator cuff tears using 3-Tesla MRI versus 3-Tesla MRA: a systematic review and meta-analysis.

    PubMed

    McGarvey, Ciaran; Harb, Ziad; Smith, Christian; Houghton, Russell; Corbett, Steven; Ajuied, Adil

    2016-02-01

    To compare the diagnostic accuracy of magnetic resonance imaging (MRI), 2-dimensional magnetic resonance arthrogram (MRA) and 3-dimensional isotropic MRA in the diagnosis of rotator cuff tears when performed exclusively at 3-T. A systematic review was undertaken of the Cochrane, MEDLINE and PubMed databases in accordance with the PRISMA guidelines. Studies comparing 3-T MRI or 3-T MRA (index tests) to arthroscopic surgical findings (reference test) were included. Methodological appraisal was performed using QUADAS 2. Pooled sensitivity and specificity were calculated and summary receiver-operating curves generated. Kappa coefficients quantified inter-observer reliability. Fourteen studies comprising 1332 patients were identified for inclusion. Twelve studies were retrospective and there were concerns regarding index test bias and applicability in nine and six studies respectively. Reference test bias was a concern in all studies. Both 3-T MRI and 3-T MRA showed similar excellent diagnostic accuracy for full-thickness supraspinatus tears. Concerning partial-thickness supraspinatus tears, 3-T 2D MRA was significantly more sensitive (86.6 vs. 80.5 %, p = 0.014) but significantly less specific (95.2 vs. 100 %, p < 0.001). There was a trend towards greater accuracy in the diagnosis of subscapularis tears with 3-T MRA. Three-Tesla 3D isotropic MRA showed similar accuracy to 3-T conventional 2D MRA. Three-Tesla MRI appeared equivalent to 3-T MRA in the diagnosis of full- and partial-thickness tears, although there was a trend towards greater accuracy in the diagnosis of subscapularis tears with 3-T MRA. Three-Tesla 3D isotropic MRA appears equivalent to 3-T 2D MRA for all types of tears.

  6. Geometric modeling of hepatic arteries in 3D ultrasound with unsupervised MRA fusion during liver interventions.

    PubMed

    Gérard, Maxime; Michaud, François; Bigot, Alexandre; Tang, An; Soulez, Gilles; Kadoury, Samuel

    2017-06-01

    Modulating the chemotherapy injection rate with regard to blood flow velocities in the tumor-feeding arteries during intra-arterial therapies may help improve liver tumor targeting while decreasing systemic exposure. These velocities can be obtained noninvasively using Doppler ultrasound (US). However, small vessels situated in the liver are difficult to identify and follow in US. We propose a multimodal fusion approach that non-rigidly registers a 3D geometric mesh model of the hepatic arteries obtained from preoperative MR angiography (MRA) acquisitions with intra-operative 3D US imaging. The proposed fusion tool integrates 3 imaging modalities: an arterial MRA, a portal phase MRA and an intra-operative 3D US. Preoperatively, the arterial phase MRA is used to generate a 3D model of the hepatic arteries, which is then non-rigidly co-registered with the portal phase MRA. Once the intra-operative 3D US is acquired, we register it with the portal MRA using a vessel-based rigid initialization followed by a non-rigid registration using an image-based metric based on linear correlation of linear combination. Using the combined non-rigid transformation matrices, the 3D mesh model is fused with the 3D US. 3D US and multi-phase MRA images acquired from 10 porcine models were used to test the performance of the proposed fusion tool. Unimodal registration of the MRA phases yielded a target registration error (TRE) of [Formula: see text] mm. Initial rigid alignment of the portal MRA and 3D US yielded a mean TRE of [Formula: see text] mm, which was significantly reduced to [Formula: see text] mm ([Formula: see text]) after affine image-based registration. The following deformable registration step allowed for further decrease of the mean TRE to [Formula: see text] mm. The proposed tool could facilitate visualization and localization of these vessels when using 3D US intra-operatively for either intravascular or percutaneous interventions to avoid vessel perforation.

  7. Congenital heart disease in adults: Quantitative and qualitative evaluation of IR FLASH and IR SSFP MRA techniques using a blood pool contrast agent in the steady state and comparison to first pass MRA.

    PubMed

    Febbo, Jennifer A; Galizia, Mauricio S; Murphy, Ian G; Popescu, Andrada; Bi, Xiaoming; Turin, Alexander; Collins, Jeremy; Markl, Michael; Edelman, Robert R; Carr, James C

    2015-10-01

    To evaluate magnetic resonance angiography sequences during the contrast steady-state (SS-MRA) using inversion recovery (IR) with fast low-angle shot (IR-FLASH) or steady-state free precession (IR-SSFP) read-outs, following the injection of a blood-pool contrast agent, and compare them to first-pass MR angiography (FP-MRA) in adults with congenital heart disease (CHD). Twenty-three adult patients with CHD who underwent both SS-MRA and FP-MRA using a 1.5-T scanner were retrospectively identified. Signal-to-noise and contrast-to-noise ratios were obtained at eight locations within the aorta and pulmonary vessels.. Image quality and the presence of artifacts were subjectively assessed by two radiologists. The presence of pathology was noted and given a confidence score. There was no difference in vessel dimensions among the sequences. IR-SSFP showed better image quality and fewer artifacts than IR-FLASH and FP-MRA. Confidence scores were significantly higher for SS-MRA compared to FP-MRA. Seven cases (30.4%) had findings detected at SS-MRA that were not detected at FP-MRA, and 2 cases (8.7%) had findings detected by IR-SSFP only. SS-MRA of the thoracic vasculature using a blood pool contrast agent offers superior image quality and reveals more abnormalities compared to standard FP-MRA in adults with CHD, and it is best achieved with an IR-SSFP sequence. These sequences could lead to increased detection rates of abnormalities and provide a simpler protocol image acquisition. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  8. Assay for identification of inhibitors for bacterial MraY translocase or MurG transferase.

    PubMed

    Branstrom, A A; Midha, S; Longley, C B; Han, K; Baizman, E R; Axelrod, H R

    2000-05-01

    Bacterial peptidoglycan synthesis is a well-characterized system for targeting new antimicrobial drugs. Formation of the peptidoglycan precursors Lipid I and Lipid II is catalyzed by the gene products of mraY and murG, which are involved in the first and second steps of the lipid cycle reactions, respectively. Here we describe the development of an assay specific for identifying inhibitors of MraY or MurG, based on the detection of radiolabeled [(14)C]GlcNAc incorporated into Lipid II. Assay specificity is achieved with the biotin tagging of the Lipid I precursor UDP-MurNAc-pentapeptide. This allows for the separation and identification of lipid products produced by the enzymatic activity of the MraY and MurG proteins, and thus identification of specific inhibitors. Copyright 2000 Academic Press.

  9. Lipid production by a CO₂-tolerant green microalga, Chlorella sp. MRA-1.

    PubMed

    Zheng, Yanlin; Yuan, Cheng; Liu, Junhan; Hu, Guangrong; Li, Fuli

    2014-05-01

    Since CO2 concentrations in industrial flue gases are usually 10%-20%, one of the prerequisites for efficient CO2 removal by algae is the level of tolerance of microalgal species to exposure to high concentrations of CO2. A newly isolated microalgal strain, Chlorella sp. MRA-1, could retain growth with high concentrations of CO2 up to 15%. The highest lipid productivity for Chlorella sp. MRA-1 was 0.118 g/l/day with a 5% CO2 concentration. Octadecenoic acid and hexadecanoic acid, the main components of biodiesel, accounted for 70% of the total fatty acids. A lipid content of 52% of dry cell weight was achieved with limited amounts of nitrogen. Chlorella sp. MRA-1 seems to be an ideal candidate for biodiesel production when cultured with high concentrations of CO2.

  10. 3D morphometry using automated aortic segmentation in native MR angiography: an alternative to contrast enhanced MRA?

    PubMed Central

    Müller-Eschner, Matthias; Müller, Tobias; Biesdorf, Andreas; Wörz, Stefan; Rengier, Fabian; Böckler, Dittmar; Kauczor, Hans-Ulrich; Rohr, Karl

    2014-01-01

    Introduction Native-MR angiography (N-MRA) is considered an imaging alternative to contrast enhanced MR angiography (CE-MRA) for patients with renal insufficiency. Lower intraluminal contrast in N-MRA often leads to failure of the segmentation process in commercial algorithms. This study introduces an in-house 3D model-based segmentation approach used to compare both sequences by automatic 3D lumen segmentation, allowing for evaluation of differences of aortic lumen diameters as well as differences in length comparing both acquisition techniques at every possible location. Methods and materials Sixteen healthy volunteers underwent 1.5-T-MR Angiography (MRA). For each volunteer, two different MR sequences were performed, CE-MRA: gradient echo Turbo FLASH sequence and N-MRA: respiratory-and-cardiac-gated, T2-weighted 3D SSFP. Datasets were segmented using a 3D model-based ellipse-fitting approach with a single seed point placed manually above the celiac trunk. The segmented volumes were manually cropped from left subclavian artery to celiac trunk to avoid error due to side branches. Diameters, volumes and centerline length were computed for intraindividual comparison. For statistical analysis the Wilcoxon-Signed-Ranked-Test was used. Results Average centerline length obtained based on N-MRA was 239.0±23.4 mm compared to 238.6±23.5 mm for CE-MRA without significant difference (P=0.877). Average maximum diameter obtained based on N-MRA was 25.7±3.3 mm compared to 24.1±3.2 mm for CE-MRA (P<0.001). In agreement with the difference in diameters, volumes obtained based on N-MRA (100.1±35.4 cm3) were consistently and significantly larger compared to CE-MRA (89.2±30.0 cm3) (P<0.001). Conclusions 3D morphometry shows highly similar centerline lengths for N-MRA and CE-MRA, but systematically higher diameters and volumes for N-MRA. PMID:24834406

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

    PubMed Central

    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.

    2016-01-01

    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. 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. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  13. The MRA-DWI Mismatch Identifies Patients With Stroke Who Are Likely to Benefit From Reperfusion

    PubMed Central

    Lansberg, Maarten G.; Thijs, Vincent N.; Bammer, Roland; Olivot, Jean-Marc; Marks, Michael P.; Wechsler, Lawrence R.; Kemp, Stephanie; Albers, Gregory W.

    2012-01-01

    Background and Purpose The aim of this exploratory analysis was to evaluate if a combination of MR angiography (MRA) and diffusion-weighted imaging (DWI) selection criteria can be used to identify patients with acute stroke who are likely to benefit from early reperfusion. Methods Data from DEFUSE, a study of 74 patients with stroke who received intravenous tissue plasminogen activator in the 3- to 6-hour time window and underwent MRIs before and approximately 4 hours after treatment were analyzed. The MRA–DWI mismatch model was defined as (1) a DWI lesion volume less than 25 mL in patients with a proximal vessel occlusion; or (2) a DWI lesion volume less than 15 mL in patients with proximal vessel stenosis or an abnormal finding of a distal vessel. Favorable clinical response was defined as an improvement on the National Institutes of Health Stroke Scale score of at least 8 points between baseline and 30 days or a National Institutes of Health Stroke Scale score ≤1 at 30 days. Results Twenty-seven of 62 patients (44%) had an MRA-DWI mismatch. There was a differential response to early reperfusion based on MRA-DWI mismatch status. Reperfusion was associated with an increased rate of a favorable clinical response in patients with an MRA-DWI mismatch (OR, 12.5; 95% CI, 1.8 to 83.9) and a lower rate in patients without mismatch (OR, 0.2; 95% CI, 0.0 to 0.8). Conclusions The MRA-DWI mismatch model appears to identify patients with stroke who are likely to benefit from reperfusion therapy administered in the 3- to 6-hour time window after symptom onset. The criteria established for the MRA-DWI mismatch model in this study require validation in an independent cohort. PMID:18635861

  14. Detection and characterization of unruptured intracranial aneurysms: Comparison of 3T MRA and DSA.

    PubMed

    Mine, Benjamin; Pezzullo, Martina; Roque, Gonçalo; David, Philippe; Metens, Thierry; Lubicz, Boris

    2015-06-01

    To compare magnetic resonance angiography (MRA) at 3 Tesla (3T) and digital subtraction angiography (DSA) for the detection and characterization of unruptured intracranial aneurysms (UIA). This study has been approved by our local ethical committee. From February to August 2010, 40 consecutive patients with UIA contemporarily underwent MRA at 3T including time-of-flight (TOF-MRA) and contrast enhanced (CE-MRA) techniques and DSA. MR images were independently reviewed by 3 radiologists and DSA images were reviewed by 2 radiologists together. Interobserver and intertechnique agreements were assessed for aneurysm detection and characterization including maximal diameter, neck width and the presence of a bleb or a branch arising from the sac. DS angiography revealed 56 aneurysms. Mean sensitivity and positive predictive value of MRA were 91.4% and 93.4% respectively. For UIA < 3 mm and those ≥ 3 mm, MRA had a mean sensitivity of 74.1% and 100% respectively. Intertechnique and interobserver agreements were substantial for the measurement of UIA maximal diameter (mean κ, 0.607 and 0.601 respectively) and were moderate and fair for neck width measurement respectively (mean κ, 0.456 and 0.285 respectively). For bleb detection, intertechnique and interobserver agreements were fair and slight respectively (mean κ, 0.312 and 0.116 respectively) whereas both were slight for detection of branches arising from the sac (mean κ, 0.151 and 0.070 respectively). MR angiography at 3T has a high sensitivity for the detection of UIA. However, it remains significantly inferior to DSA for morphological characterization of UIA. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  15. 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. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Development of a microplate-based scintillation proximity assay for MraY using a modified substrate.

    PubMed

    Solapure, S M; Raphael, P; Gayathri, C N; Barde, S P; Chandrakala, B; Das, K S; De Sousa, S M

    2005-03-01

    MraY is an established target for the discovery of antibacterial agents. The conventional assay for MraY uses radioactive substrate and analysis of products after paper chromatography or butanol extraction. Synthesis of radiolabeled substrate has been done in vitro using purified enzymes or by growing cells on radiolabeled precursors. The authors report a simple and rapid method to chemically radiolabel MraY substrate, UDP-MurNAc-pentapeptide. Specific activity obtained by this method was more than 100 times higher than the conventionally labeled substrate, and yields are high enough to support the requirements of high-throughput screening (HTS). The authors have developed a microplate-based homogeneous assay for MraY in which the product is captured on wheat germ agglutinin (WGA) scintillation proximity assay (SPA) beads. The assay was validated by showing inhibition by specific inhibitors of MraY but not by inhibitors of other enzymes of peptidoglycan synthesis. The assay uses wild-type membranes of Escherichia coli, giving it an advantage over recently described assays that need the protein to be overexpressed. In addition, it has an advantage over the high-throughput MraY-MurG coupled assay reported in the literature because it is MraY specific, and therefore hits obtained in this assay do not need further deconvolution. It has potential for use in HTS approaches to find novel inhibitors of MraY.

  17. Follow-up of intracranial aneurysms treated with detachable coils: comparison of 3D inflow MRA at 3T and 1.5T and contrast-enhanced MRA at 3T with DSA.

    PubMed

    Ramgren, Birgitta; Siemund, Roger; Cronqvist, Mats; Undrén, Per; Nilsson, Ola G; Holtås, Stig; Larsson, Elna-Marie

    2008-11-01

    The purpose of this prospective study was to compare 3T and 1.5T magnetic resonance angiography (MRA) with digital subtraction angiography (DSA) for the follow-up of endovascular treated intracranial aneurysms to assess the grade of occlusion. Thirty-seven patients with 41 aneurysms who had undergone endovascular treatment with detachable coils were included. MRA was performed on the same day using an eight-channel sensitivity encoding head-coil with 3D axial inflow technique. At 3T, a contrast-enhanced transverse 3D fast gradient echo acquisition was also performed. Most patients underwent DSA the following day. MRA scans and DSA were classified first independently by two neuroradiologists and an interventional neuroradiologist. Secondly, a consensus was done. Source images, maximum intensity projection, multiplanar reconstruction and volume rendering reconstructions were used for MRA evaluations. A modification of the Raymond classification, previously used for DSA evaluation of recanalization, was used. Statistical comparison of the consensus showed that 3T MRA with 3D axial inflow technique had better agreement with DSA (kappa = 0.43) than 1.5T MRA(kappa = 0.21) and contrast-enhanced MRA (CE-MRA) at 3T (kappa = 0.17). The susceptibility artefacts from the coil mesh were significally smaller at 3T (p = 0.002-0.007) than at 1.5T. 3T MRA, using a sensitivity encoding head-coil, showed better agreement with DSA than 1.5T and CE-MRA at 3T for evaluation of aneurysms treated with endovascular coiling.

  18. Peripheral Arterial Disease in a Symptomatic Diabetic Population: Prospective Comparison of Rapid Unenhanced MR Angiography (MRA) With Contrast-Enhanced MRA

    PubMed Central

    Hodnett, Philip A.; Ward, Emily V.; Davarpanah, Amir H.; Scanlon, Timothy G.; Collins, Jeremy D.; Glielmi, Christopher B.; Bi, Xiaoming; Koktzoglou, Ioannis; Gupta, Navyash; Carr, James C.; Edelman, Robert R.

    2011-01-01

    OBJECTIVE The joint guidelines of the American College of Cardiology and American Heart Association support the use of contrast-enhanced MR angiography (CEMRA) to diagnose the location and degree of stenosis in patients with known or suspected peripheral arterial disease (PAD). The high prevalence of chronic renal impairment in diabetic patients with PAD and the need for high doses of gadolinium-based contrast agents place them at risk for nephrogenic systemic fibrosis. The purpose of our study was to evaluate the accuracy of the rapid technique of quiescent-interval single-shot (QISS) unenhanced MR angiography (MRA) compared with CEMRA for the diagnosis in diabetic patients referred with symptomatic chronic PAD. SUBJECTS AND METHODS This prospective two-center study evaluated 25 consecutive diabetic patients with documented or suspected symptomatic PAD. Both centers used identical imaging protocols. Images were independently analyzed by two radiologists. A subgroup analysis was performed of patients who were also assessed with digital subtraction angiography (DSA) as part of the standard-of-care protocol before revascularization. RESULTS For this study, 775 segments were analyzed. On a per-segment basis, the mean values of the diagnostic accuracy of unenhanced MRA compared with reference CEMRA for two reviewers, reviewers 1 and 2, were as follows: sensitivity, 87.4% and 92.1%; specificity, 96.8% and 96.0%; positive predictive value, 90.8% and 94.0%; and negative predictive value, 95.5% and 94.6%. Substantial agreement was found when overall DSA results were compared with QISS unenhanced MRA (κ = 0.68) and CEMRA (κ = 0.63) in the subgroup of patients who also underwent DSA. There was almost perfect agreement between the two readers for stenosis scores, with Cohen’s kappa values being greater than 0.80 for both MRA techniques. CONCLUSION The results of our study indicate that QISS unenhanced MRA is an accurate noncontrast alternative to CEMRA for showing

  19. 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.

  20. Scintillation proximity assay for inhibitors of Escherichia coli MurG and, optionally, MraY.

    PubMed

    Ravishankar, Sudha; Kumar, Vidya Prasanna; Chandrakala, B; Jha, Ramesh K; Solapure, Suresh M; de Sousa, Sunita M

    2005-04-01

    MurG and MraY, essential enzymes involved in the synthesis of bacterial peptidoglycan, are difficult to assay because the substrates are lipidic and hard to prepare in large quantities. Based on the use of Escherichia coli membranes lacking PBP1b, we report a high-throughput method to measure the activity of MurG and, optionally, MraY as well. In these membranes, incubation with the two peptidoglycan sugar precursors results in accumulation of lipid II rather than the peptidoglycan produced by wild-type membranes. MurG was assayed by addition of UDP-[3H]N-acetylglucosamine to membranes in which lipid I was preformed by incubation with UDP-N-acetyl-muramylpentapeptide, and the product was captured by wheat germ agglutinin scintillation proximity assay beads. In a modification of the assay, the activity of MraY was coupled to that of MurG by addition of both sugar precursors together in a single step. This allows simultaneous detection of inhibitors of either enzyme. Both assays could be performed using wild-type membranes by addition of the transglycosylase inhibitor moenomycin. Nisin and vancomycin inhibited the MurG reaction; the MraY-MurG assay was inhibited by tunicamycin as well. Inhibitors of other enzymes of peptidoglycan synthesis--penicillin G, moenomycin, and bacitracin--had no effect. Surprisingly, however, the beta-lactam cephalosporin C inhibited both the MurG and MraY-MurG assays, indicating a secondary mechanism by which this drug inhibits bacterial growth. In addition, it inhibited NADH dehydrogenase in membranes, a hitherto-unreported activity. These assays can be used to screen for novel antibacterial agents.

  1. Scintillation Proximity Assay for Inhibitors of Escherichia coli MurG and, Optionally, MraY

    PubMed Central

    Ravishankar, Sudha; Kumar, Vidya Prasanna; Chandrakala, B.; Jha, Ramesh K.; Solapure, Suresh M.; de Sousa, Sunita M.

    2005-01-01

    MurG and MraY, essential enzymes involved in the synthesis of bacterial peptidoglycan, are difficult to assay because the substrates are lipidic and hard to prepare in large quantities. Based on the use of Escherichia coli membranes lacking PBP1b, we report a high-throughput method to measure the activity of MurG and, optionally, MraY as well. In these membranes, incubation with the two peptidoglycan sugar precursors results in accumulation of lipid II rather than the peptidoglycan produced by wild-type membranes. MurG was assayed by addition of UDP-[3H]N-acetylglucosamine to membranes in which lipid I was preformed by incubation with UDP-N-acetyl-muramylpentapeptide, and the product was captured by wheat germ agglutinin scintillation proximity assay beads. In a modification of the assay, the activity of MraY was coupled to that of MurG by addition of both sugar precursors together in a single step. This allows simultaneous detection of inhibitors of either enzyme. Both assays could be performed using wild-type membranes by addition of the transglycosylase inhibitor moenomycin. Nisin and vancomycin inhibited the MurG reaction; the MraY-MurG assay was inhibited by tunicamycin as well. Inhibitors of other enzymes of peptidoglycan synthesis—penicillin G, moenomycin, and bacitracin—had no effect. Surprisingly, however, the β-lactam cephalosporin C inhibited both the MurG and MraY-MurG assays, indicating a secondary mechanism by which this drug inhibits bacterial growth. In addition, it inhibited NADH dehydrogenase in membranes, a hitherto-unreported activity. These assays can be used to screen for novel antibacterial agents. PMID:15793120

  2. mraW, an essential gene at the dcw cluster of Escherichia coli codes for a cytoplasmic protein with methyltransferase activity.

    PubMed

    Carrión, M; Gómez, M J; Merchante-Schubert, R; Dongarrá, S; Ayala, J A

    1999-01-01

    Three new open reading frames, mraZ, mraW and mraR (also called ftsL), were revealed by DNA sequencing immediately upstream of gene pbpB in the dcw cluster of Escherichia coli. We have found that mraW and mraZ are active genes, coding for two proteins with relative molecular masses of 34 800 and 17 300, respectively. MraW is a cytoplasmic protein that under overproduction condition is also loosely bound to the membrane. Soluble MraW was purified up to 90% by a single high performance electrophoresis (HPEC) step from an extract of an overproducing strain. The protein exhibits a S-adenosyl-dependent methyltransferase activity on membrane-located substrates.

  3. Evaluation of meglumine gadoterate-enhanced MR angiography (MRA) compared with time-of-flight MRA in the diagnosis of clinically significant non-coronary arterial disease: a pooled analysis of data from two clinical trials

    PubMed Central

    Shah, D J; Lim, T-H

    2012-01-01

    Objectives We analysed pooled data from two clinical trials to assess the diagnostic accuracy and safety of meglumine gadoterate (Gd-DOTA)-enhanced MR angiography (MRA) relative to those of non-enhanced time-of-flight (TOF) MRA for non-coronary arterial disease. Both techniques were compared with X-ray angiography as the gold standard. Methods Patients were of both sexes, were aged at least 18 years and had suspected non-coronary arterial disease. Each patient was his/her own control and underwent TOF MRA followed by Gd-DOTA-enhanced MRA, and then X-ray angiography. MRA was performed at 1.5 T (USA study) or 3 T (Republic of Korea study). The primary criterion used to evaluate efficacy was the degree to which the MRA examination agreed with X-ray angiography in assessing non-coronary arterial lesions. The performance of Gd-DOTA over TOF was assessed using a one-sided paired t-test. We also evaluated the specificity, sensitivity, image quality, examination duration and clinical safety of both MRA procedures. Results In total, 192 patients were enrolled and received Gd-DOTA. In the intent-to-treat population (n=162), within-patient accuracy was significantly greater for Gd-DOTA than for TOF (85.8±19.8% agreement between Gd-DOTA and X-ray angiography compared with 78.3±24.9% agreement between TOF and X-ray angiography; p=0.0001). The sensitivity, specificity, image quality and examination duration were also better for Gd-DOTA than for TOF. There were no serious drug-related adverse events. Conclusion We conclude that Gd-DOTA-enhanced MRA is a safe and accurate procedure for detecting arterial stenosis at both 1.5 T and 3 T. PMID:22167518

  4. Investigating Uncertainty and Sensitivity in Integrated, Multimedia Environmental Models: Tools for FRAMES-3MRA

    SciTech Connect

    Babendreier, Justin E.; Castleton, Karl J.

    2005-08-01

    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, spanning multiple geographical and ecological regions, will ultimately require a comparative approach using several techniques, coupled with sufficient computational power. The Framework for Risk Analysis in Multimedia Environmental Systems - Multimedia, Multipathway, and Multireceptor Risk Assessment (FRAMES-3MRA) is an important software model being developed by the United States Environmental Protection Agency for use in risk assessment of hazardous waste management facilities. The 3MRA modeling system includes a set of 17 science modules that collectively simulate release, fate and transport, exposure, and risk associated with hazardous contaminants disposed of in land-based waste management units (WMU) .

  5. Phospho-MurNAc-pentapeptide translocase (MraY) as a target for antibacterial agents and antibacterial proteins.

    PubMed

    Bugg, Timothy D H; Lloyd, Adrian J; Roper, David I

    2006-06-01

    Phospho-MurNAc-pentapeptide translocase (MraY, translocase I) catalyses the first step of the lipid-linked cycle of reactions of bacterial peptidoglycan biosynthesis. MraY is the target for five families of nucleoside antibacterial natural products: the tunicamycins, the mureidomycins (also pacidamycins, napsamycins), the liposidomycins, the muraymycins, and the capuramycins. Recent structure-activity studies on these families have led to the identification of active pharmacophores, and insight into their mechanisms of action. This step of peptidoglycan biosynthesis is also the target for the bacteriolytic E protein from bacteriophage phiX174, and for cyclic peptides of the amphomycin family which complex the undecaprenyl phosphate co-substrate. The mechanisms of enzyme inhibition by these agents are discussed, and the state of knowledge regarding the transmembrane structure, active site, and catalytic mechanism of MraY. The availability of high throughput assays and prospects of MraY as an antibacterial target are also discussed.

  6. Synthesis of the nucleoside moiety of liposidomycins: elucidation of the pharmacophore of this family of MraY inhibitors.

    PubMed

    Dini, C; Collette, P; Drochon, N; Guillot, J C; Lemoine, G; Mauvais, P; Aszodi, J

    2000-08-21

    Tunicamycins (TCMs) and liposidomycins (LPMs) are naturally occurring inhibitors of the bacterial translocase (MraY). Based on structure-activity relationship (SAR) studies, a molecular model has been proposed for their inhibitory mechanism. This study points out the importance of the nucleoside moiety of liposidomycins in the inhibition of MraY. A simplified molecule (I) based on the liposidomycin core structure has been synthesised and tested on MraY. The compound displayed a moderate inhibitory activity (IC50 = 50 microM). The validation of the molecular model was then performed by synthesising higher homologues of I, containing an additional stereocentre in the 5' position (XIV and XV). In agreement with the prediction, only the (S) isomer XV showed significant activity against MraY (IC50 = 5 microM).

  7. Matching of projection imaging and tomographic imaging: application to digital subtracted angiography (DSA) and magnetic resonance angiography (MRA)

    NASA Astrophysics Data System (ADS)

    Vermandel, Maximilien; Kulik, Carine; Leclerc, Xavier; Rousseau, Jean; Vasseur, Christian

    2002-05-01

    This study proposes a new method for matching vascular imaging modalities without the use of external frame or external landmarks. We first perform a 3D reconstruction of a piece of the cerebral vascular tree using Magnetic Resonance Angiography (MRA). Then, this structure is projected on the Digital Subtracted Angiography (DSA) images until its best position and orientation are found. As the 3D structure is known in the MRA referential, this method enables us to match information from DSA and MRA. The complete matching of all the DSA images in many incidences and the MRA set have been obtained. For the DSA images, the epipolar constraint has been verified between all the incidences. This new approach in medical imaging brings a very original method, making easier and more efficient visualization and quantification of vascular information.

  8. Non-Contrast SSFP Pulmonary Vein MRA: Impact of Off-Resonance and Flow

    PubMed Central

    Hu, Peng; Stoeck, Christian T.; Smink, Jouke; Peters, Dana C.; Ngo, Long; Goddu, Beth; Kissinger, Kraig V.; Goepfert, Lois A.; Chan, Jonathan; Hauser, Thomas H.; Rofsky, Neil M.; Manning, Warren J.; Nezafat, Reza

    2010-01-01

    Purpose To investigate pulmonary vein (PV) off-resonance and blood flow as causes of signal void artifacts in non-contrast steady-state-free-precession (SSFP) PV MR angiography (MRA). Materials and Methods PV blood off-resonance was measured on 11 healthy adult subjects and 10 atrial fibrillation (AF) patients. Non-contrast PV MRA was performed using a three-dimensional slab-selective SSFP sequence at 1.5T on 7 healthy subjects with signal profile shifts of 0-125Hz. The time-resolved blood flow velocity of the PVs was measured on 5 healthy subjects. The impact of flow was studied on 6 healthy subjects, on whom SSFP PV MRA was acquired twice with the ECG trigger delay corresponding to low and high flow, respectively. Results The PV off-resonance were 97±27Hz, 65±20Hz, 74±25Hz, and 52±17Hz for right inferior, left inferior, right superior and left superior PVs, respectively, on healthy subjects, and were 74±20Hz, 38±9Hz, 51±20Hz, and 28±11Hz on AF patients (P<0.01 for all). The off-resonance caused severe signal voids in the PVs. Signal acquired during mid-diastole with high PV flow caused additional signal voids in the left atrium, which was reduced by setting the ECG trigger delay to late-diastole. Conclusion PV off-resonance and flow causes signal void artifacts in non-contrast three-dimensional slab-selective SSFP PV MRA. PMID:21031533

  9. Peptidoglycan precursor pools associated with MraY and FtsW deficiencies or antibiotic treatments.

    PubMed

    Lara, Beatriz; Mengin-Lecreulx, Dominique; Ayala, Juan A; van Heijenoort, Jean

    2005-09-15

    Blocking peptidoglycan synthesis in Escherichia coli with moenomycin or vancomycin led to the accumulation of UDP-MurNAc-pentapeptide and of its immediate upstream precursors, whereas with cephaloridine or penicillin G the pool of UDP-MurNAc-pentapeptide decreased. With MraY and FtsW deficiencies the decrease of UDP-MurNAc-pentapeptide was accompanied by an increase of the upstream nucleotide precursors and the appearance of UDP-MurNAc-tetrapeptide.

  10. Mechanistic analysis of muraymycin analogues: a guide to the design of MraY inhibitors.

    PubMed

    Tanino, Tetsuya; Al-Dabbagh, Bayan; Mengin-Lecreulx, Dominique; Bouhss, Ahmed; Oyama, Hiroshi; Ichikawa, Satoshi; Matsuda, Akira

    2011-12-22

    The systematic structure-activity relationship (SAR) of the muraymycins (MRYs) using an Ugi four-component reaction (U4CR) was investigated. The impact of the lipophilic substituent on antibacterial activity was significant, and the analogues 8 and 9 having a lipophilic side chain exhibited good activity against a range of Gram-positive bacterial pathogens, including MRSA and VRE. Further investigation of compounds 8 and 9 revealed these analogues to be selective inhibitors of the MraY transferase and nontoxic to HepG2 cells. The SAR of the accessory urea-peptide moiety indicated that it could be simplified. Our SAR study of the MRYs suggests a probable mechanism for inhibition of the MraY, where the inner moiety of the urea-dipeptide motif interacts with the carbohydrate recognition domain in the cytoplasmic loop 5. The predicted binding model would provide further direction toward the design of potent MraY inhibitors. This study has set the stage for the generation of novel antibacterial "lead" compounds based on MRYs.

  11. 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.

  12. 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.

  13. Evaluation of fast highly undersampled contrast-enhanced MR angiography (sparse CE-MRA) in intracranial applications - initial study.

    PubMed

    Gratz, Marcel; Schlamann, Marc; Goericke, Sophia; Maderwald, Stefan; Quick, Harald H

    2017-03-01

    To assess the image quality of sparsely sampled contrast-enhanced MR angiography (sparse CE-MRA) providing high spatial resolution and whole-head coverage. Twenty-three patients scheduled for contrast-enhanced MR imaging of the head, (N = 19 with intracranial pathologies, N = 9 with vascular diseases), were included. Sparse CE-MRA at 3 Tesla was conducted using a single dose of contrast agent. Two neuroradiologists independently evaluated the data regarding vascular visibility and diagnostic value of overall 24 parameters and vascular segments on a 5-point ordinary scale (5 = very good, 1 = insufficient vascular visibility). Contrast bolus timing and the resulting arterio-venous overlap was also evaluated. Where available (N = 9), sparse CE-MRA was compared to intracranial Time-of-Flight MRA. The overall rating across all patients for sparse CE-MRA was 3.50 ± 1.07. Direct influence of the contrast bolus timing on the resulting image quality was observed. Overall mean vascular visibility and image quality across different features was rated good to intermediate (3.56 ± 0.95). The average performance of intracranial Time-of-Flight was rated 3.84 ± 0.87 across all patients and 3.54 ± 0.62 across all features. Sparse CE-MRA provides high-quality 3D MRA with high spatial resolution and whole-head coverage within short acquisition time. Accurate contrast bolus timing is mandatory. • Sparse CE-MRA enables fast vascular imaging with full brain coverage. • Volumes with sub-millimetre resolution can be acquired within 10 seconds. • Reader's ratings are good to intermediate and dependent on contrast bolus timing. • The method provides an excellent overview and allows screening for vascular pathologies.

  14. Correlation between magnetic resonance angiography (MRA) and quantitative coronary angiography (QCA) in ectatic coronary vessels.

    PubMed

    Mavrogeni, Sophie I; Manginas, Athanassios; Papadakis, Emmanouil; Foussas, Stefanos; Douskou, Marouso; Baras, Panagiotis; Seimenis, Ioannis; Cokkinos, Dennis V

    2004-01-01

    Coronary artery ectasia (CAE) is defined as a dilatation of an arterial segment to a diameter at least 1.5 times that of the adjacent normal artery. The correct follow-up of ectatic vessels is hampered by the need for repeat angiograms. In this work we compared quantitative coronary angiography (QCA) measurements of the diameter of the proximal most ectatic part of coronary vessels, with corresponding measurements obtained by magnetic resonance angiography (MRA) using both gradient echo and turbo spin echo imaging sequences. Fifteen patients (14 male), aged 45-65 years, with known CAE were prospectively studied. Two electrocardiogram (ECG)-triggered pulse sequences were implemented for coronary magnetic resonance angiography. The first was a three-dimensional (3D), segmented, k-space gradient-echo sequence, employing a T2-weighted preparation prepulse and a frequency-selective, fat-saturation prepulse to enhance "white blood" (WB) contrast of the coronary arteries. The second sequence was an M2D dual Inversion Recovery (IR) Turbo Spin-Echo with a linear k-space acquisition scheme, providing "black-blood" (BB) contrast of the coronaries. All scans were carried out with the patient free breathing using a 2D, real-time Navigator beam, for respiratory motion tracking and gating. All patients underwent QCA, and the diameter of the proximal most ectatic part of each vessel was measured and compared with "white-blood" and "black-blood" MRA measurements. The average length of continuously visualized LM, LAD, LCx, and RCA by MRA was 2.5 +/- 0.3, 5.8 +/- 0.8, 3.9 +/- 1.0, and 7.2 +/- 1.2 cm, respectively. There were no statistically significant differences between diameter measurements of the proximal most ectatic part of each vessel, obtained with WB and BB sequences. There was a close correlation between MRA and QCA measurements (r = 0.87, p < 0.001). Bland-Altman analysis showed no systematic differences between the examined methods, over the whole range of vessel

  15. Preparative Scale Cell-free Production and Quality Optimization of MraY Homologues in Different Expression Modes*

    PubMed Central

    Ma, Yi; Münch, Daniela; Schneider, Tanja; Sahl, Hans-Georg; Bouhss, Ahmed; Ghoshdastider, Umesh; Wang, Jufang; Dötsch, Volker; Wang, Xiaoning; Bernhard, Frank

    2011-01-01

    MraY translocase catalyzes the first committed membrane-bound step of bacterial peptidoglycan synthesis leading to the formation of lipid I. The essential membrane protein therefore has a high potential as target for drug screening approaches to develop antibiotics against Gram-positive as well as Gram-negative bacteria. However, the production of large integral membrane proteins in conventional cellular expression systems is still very challenging. Cell-free expression technologies have been optimized in recent times for the production of membrane proteins in the presence of detergents (D-CF), lipids (L-CF), or as precipitates (P-CF). We report the development of preparative scale production protocols for the MraY homologues of Escherichia coli and Bacillus subtilis in all three cell-free expression modes followed by their subsequent quality evaluation. Although both proteins can be cell-free produced at comparable high levels, their requirements for optimal expression conditions differ markedly. B. subtilus MraY was stably folded in all three expression modes and showed highest translocase activities after P-CF production followed by defined treatment with detergents. In contrast, the E. coli MraY appears to be unstable after post- or cotranslational solubilization in detergent micelles. Expression kinetics and reducing conditions were identified as optimization parameters for the quality improvement of E. coli MraY. Most remarkably, in contrast to B. subtilis MraY the E. coli MraY has to be stabilized by lipids and only the production in the L-CF mode in the presence of preformed liposomes resulted in stable and translocase active protein samples. PMID:21937437

  16. Preparative scale cell-free production and quality optimization of MraY homologues in different expression modes.

    PubMed

    Ma, Yi; Münch, Daniela; Schneider, Tanja; Sahl, Hans-Georg; Bouhss, Ahmed; Ghoshdastider, Umesh; Wang, Jufang; Dötsch, Volker; Wang, Xiaoning; Bernhard, Frank

    2011-11-11

    MraY translocase catalyzes the first committed membrane-bound step of bacterial peptidoglycan synthesis leading to the formation of lipid I. The essential membrane protein therefore has a high potential as target for drug screening approaches to develop antibiotics against gram-positive as well as gram-negative bacteria. However, the production of large integral membrane proteins in conventional cellular expression systems is still very challenging. Cell-free expression technologies have been optimized in recent times for the production of membrane proteins in the presence of detergents (D-CF), lipids (L-CF), or as precipitates (P-CF). We report the development of preparative scale production protocols for the MraY homologues of Escherichia coli and Bacillus subtilis in all three cell-free expression modes followed by their subsequent quality evaluation. Although both proteins can be cell-free produced at comparable high levels, their requirements for optimal expression conditions differ markedly. B. subtilus MraY was stably folded in all three expression modes and showed highest translocase activities after P-CF production followed by defined treatment with detergents. In contrast, the E. coli MraY appears to be unstable after post- or cotranslational solubilization in detergent micelles. Expression kinetics and reducing conditions were identified as optimization parameters for the quality improvement of E. coli MraY. Most remarkably, in contrast to B. subtilis MraY the E. coli MraY has to be stabilized by lipids and only the production in the L-CF mode in the presence of preformed liposomes resulted in stable and translocase active protein samples.

  17. Comparison of clinical symptoms and magnetic resonance angiographic (MRA) results in patients with trigeminal neuralgia and persistent idiopathic facial pain. Medium-term outcome after microvascular decompression of cases with positive MRA findings.

    PubMed

    Kuncz, A; Vörös, E; Barzó, P; Tajti, J; Milassin, P; Mucsi, Z; Elek, P; Benedek, K; Tarjányi, J; Bodosi, M

    2006-03-01

    Neurovascular compression (NC) seems to have been confirmed as the major cause of classical trigeminal neuralgia (TN). In spite of the large number of surgically positive cases, however, there are still cases where no vascular compression of the trigeminal nerve can be found. To evaluate whether NC could be demonstrated preoperatively, high-resolution magnetic resonance angiography (MRA) was performed in 287 consecutive patients with TN and persistent idiopathic facial pain (PIFP) on a 0.5-T and a 1-T MR unit. Depending on the clinical symptoms, the TN cases were divided into typical TN and trigeminal neuralgia with non-neuralgic interparoxysmal pain (TNWIP) groups. Microvascular decompression (MVD) was performed in 103 of the MRA-positive cases. The patients were followed up postoperatively for from 1 to 10 years. The clinical symptoms were compared with the imaging results. The value of MRA was assessed on the basis of the clinical symptoms and surgical findings. The outcome of MVD was graded as excellent, good or poor. The clinical symptoms were compared with the type of vascular compression and the outcome of MVD. The MRA image was positive in 161 (56%) of the 287 cases. There were significant differences between the clinical groups: 66.5% of the typical TN group, 47.5% of the TNWIP group and 3.4% of the PIFP group were positive. The quality of the MR unit significantly determined the ratio of positive/negative MRA results. The surgical findings corresponded with the MRA images. Six patients from the MRA-negative group were operated on for selective rhizotomy and no NC was found. Venous compression of the trigeminal nerve was observed in a significantly higher proportion in the background of TNWIP than in that of typical TN on MRA imaging (24.1% and 0.8%, respectively) and also during MVD (31.2% and 1.2%, respectively). Four years following the MVD, 69% of the patients gave an excellent, 23% a good and 8% a poor result. The rate of some kind of recurrence of

  18. Evaluation by MRA of aortic dilation late after repair of tetralogy of Fallot.

    PubMed

    Kay, W Aaron; Cook, Stephen C; Daniels, Curt J

    2013-09-10

    This study evaluated predictors for aortic dilation (AD) in patients with repaired tetralogy of Fallot (rTOF) using magnetic resonance angiography (MRA). AD is common in patients with rTOF and may result in increased morbidity and mortality. There are no guidelines for evaluation of AD for rTOF patients. All adults with rTOF who previously underwent MRA had retrospective aortic measurements at the sinuses of Valsalva (SoV) and ascending aorta (AsAo). Rate of change in diameter was determined in patients with multiple MRAs. Chart review identified risk factors for AD. Univariate and multivariate analyses tested predictors of AD. Of the 87 patients who met the inclusion criteria, 12 (14%) had AD. At baseline, mean diameter was 3.6 ± 0.6 cm and 3.1 ± 0.6 cm at the SoV and AsAo, respectively. The AsAo was larger than the SoV in 17%. Predictors of AD included male gender, age, right aortic arch, pregnancy, older age at complete repair, smoking, and systemic hypertension. Serial studies were available in 55 patients; the rate of growth was slow: 0.4 ± 0.9 mm/year (SoV) and 0.1 ± 0.8mm/year (AsAo). AD is common in rTOF at the SoV and AsAo. Transthoracic echocardiography, which does not always image the AsAo as well as MRA, may not image AD in rTOF in cases in which the AsAo is dilated. Although several risk factors correlate with AD in rTOF, the rate of aortic growth is slow, suggesting that rTOF patients may not require frequent aortic imaging. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  19. Hydroxycarbamide treatment and brain MRI/MRA findings in children with sickle cell anaemia.

    PubMed

    Nottage, Kerri A; Ware, Russell E; Aygun, Banu; Smeltzer, Matthew; Kang, Guolian; Moen, Joseph; Wang, Winfred C; Hankins, Jane S; Helton, Kathleen J

    2016-10-01

    Silent cerebral infarction (SCI) is the most common neurological abnormality among children with sickle cell anaemia (SCA). The effect of hydroxycarbamide (also termed hydroxyurea) on the development and progression of SCI is unclear. We evaluated brain magnetic resonance imaging/angiography (MRI/MRA) in children with SCA receiving long-term hydroxycarbamide therapy. Fifty participants (median 9·4 years, range 1·1-17·3) enrolled in the Hydroxyurea Study of Long-Term Effects (HUSTLE; NCT00305175) underwent brain MRI/MRA and laboratory evaluations before hydroxycarbamide initiation and after 3 and 6 years of treatment to maximum tolerated dose. SCI and vascular stenosis were evaluated. At baseline, 3 and 6 years, SCI were present in 19/50 (38%), 20/49 (41%), and 7/17 (41%), respectively. At 3 years, one child developed a SCI lesion, and another progressed (single lesion to multiple). Lower haemoglobin (Hb) (80 g/l vs. 86 g/l, P = 0·049), fetal Hb (5·0% vs. 10·4%, P < 0·001) and oxygen saturation (97% vs. 98%, P = 0·027) before hydroxycarbamide initiation were associated with SCI. No patients had vascular stenosis identified on MRA, transient ischaemic attack or stroke. Our data indicate that children receiving hydroxycarbamide over a 3- to 6-year period have a low rate of new or worsening cerebrovascular disease. Further studies are needed to confirm that hydroxycarbamide can prevent the onset and progression of SCI. © 2016 John Wiley & Sons Ltd.

  20. Synthesis and biological evaluation of a diazepanone-based library of liposidomycins analogs as MraY inhibitors.

    PubMed

    Mravljak, Janez; Monasson, Olivier; Al-Dabbagh, Bayan; Crouvoisier, Muriel; Bouhss, Ahmed; Gravier-Pelletier, Christine; Le Merrer, Yves

    2011-05-01

    New inhibitors of the bacterial tranferase MraY are described. A scaffold strategy based on the diazepanone central core of liposidomycins, natural inhibitors of MraY has been developed. It involves the introduction of key structural fragments required for biological activity on enantiopure diazepanones by reductive amination, esterification and glycosylation. Biological evaluation of these compounds on MraY enzyme revealed interesting inhibitory activity for compounds displaying three fragments on the scaffold: a palmitoyl chain, an aminoribose part and an alkyluracil moiety. The inhibitors were also evaluated on MurG enzyme. The best compounds resulted in inhibition with IC50 values in the 100 μM range for one or the other enzyme. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

  1. Purification and characterization of the bacterial MraY translocase catalyzing the first membrane step of peptidoglycan biosynthesis.

    PubMed

    Bouhss, Ahmed; Crouvoisier, Muriel; Blanot, Didier; Mengin-Lecreulx, Dominique

    2004-07-16

    The MraY translocase catalyzes the first membrane step of bacterial cell wall peptidoglycan synthesis (i.e. the transfer of the phospho-N-acetylmuramoyl-pentapeptide motif onto the undecaprenyl phosphate carrier lipid), a reversible reaction yielding undecaprenylpyrophosphoryl-N-acetylmuramoyl-pentapeptide (lipid intermediate I). This essential integral membrane protein, which is considered as a very promising target for the search of new antibacterial compounds, has thus far been clearly underexploited due to its intrinsic refractory nature to overexpression and purification. We here report conditions for the high level overproduction and for the first time the purification to homogeneity of milligram quantities of MraY protein. The kinetic parameters and effects of pH, salts, cations, and detergents on enzyme activity are described, taking the Bacillus subtilis MraY translocase as a model.

  2. Separation of artery and vein in contrast-enhanced MRA images

    NASA Astrophysics Data System (ADS)

    Lei, Tianhu; Udupa, Jayaram K.; Saha, Punam K.; Odhner, Dewey

    2000-04-01

    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 MR angiographic (CE-MRA) images, and an optimal method for the 3D visualization of vascular structures. The anatomic separation process utilizes fuzzy connected object delineation principles and algorithms. Its first step is the segmentation of the entire vessel structure from the background and other clutter via absolute fuzzy connectedness. Its second step is to separate artery from vein within this entire vessel structure via relative fuzzy connectedness. After 'seed' points are specified inside artery and vein in the vessel-only image, the regions of the bigger aspects of artery and vein are separated in the initial iteration. Further regions are added with subsequent iterations so that the detailed aspects of artery and vein are included in later iterations. This approach has been applied to EPIX Medical Inc's CE-MRA data. 3D images/movies of vessels, arteries, and veins have been created. Shell renditions are colored differently for arteries and veins in a composite display. This approach can produce separated artery and vein images with high quality, reliability, and minimal user interaction, in a clinical setting. All case studies were performed on a Gateway Pentium PC under Linux, and the whole procedure per study was completed in a few minutes.

  3. 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.

  4. Sequence Comparison for Non-Enhanced MRA of the Lower Extremity Arteries at 7 Tesla

    PubMed Central

    Johst, Sören; Orzada, Stephan; Fischer, Anja; Schäfer, Lena C.; Nassenstein, Kai; Umutlu, Lale; Lauenstein, Thomas C.; Ladd, Mark E.; Maderwald, Stefan

    2014-01-01

    In this study three sequences for non-contrast-enhanced MRA of the lower extremity arteries at 7T were compared. Cardiac triggering was used with the aim to reduce signal variations in the arteries. Two fast single-shot 2D sequences, a modified Ultrafast Spoiled Gradient Echo (UGRE) sequence and a variant of the Quiescent-Interval Single-Shot (QISS) sequence were triggered via phonocardiogram and compared in volunteer examinations to a non-triggered 2D gradient echo (GRE) sequence. For image acquisition, a 16-channel transmit/receive coil and a manually positionable AngioSURF table were used. To tackle B1 inhomogeneities at 7T, Time-Interleaved Acquisition of Modes (TIAMO) was integrated in GRE and UGRE. To compare the three sequences quantitatively, a vessel-to-background ratio (VBR) was measured in all volunteers and stations. In conclusion, cardiac triggering was able to suppress flow artifacts satisfactorily. The modified UGRE showed only moderate image artifacts. Averaged over all volunteers and stations, GRE reached a VBR of 4.18±0.05, UGRE 5.20±0.06, and QISS 2.72±0.03. Using cardiac triggering and TIAMO imaging technique was essential to perform non-enhanced MRA of the lower extremities vessels at 7T. The modified UGRE performed best, as observed artifacts were only moderate and the highest average VBR was reached. PMID:24454963

  5. Three-dimensional MRA study of the normal canine thorax: MIP sections and volume rendering.

    PubMed

    Contreras, S; Vázquez, J M; Morales, M; Rivero, M A; Gil, F; Latorre, R; Arencibia, A

    2011-02-01

    The purpose of this study was to investigate the feasibility of three-dimensional contrast-enhanced magnetic resonance angiography (3D-CE-MRA) for the non-invasive anatomical evaluation of the thoracic vasculature in five normal Beagles. After intravenous gadolinium administration and a cardio-respiratory gating protocol, fast 3D gradient echo pulse sequence MRA was performed employing a 1.5 Tesla magnet and a human thorax coil. Three-dimensional vascular software was applied. Sagittal, transverse and dorsal maximum intensity projection (MIP) sections and volume rendering (VR) images were obtained and labelled. Anatomical literature, dissections and gross sections were employed to assist the identification of the vascular structures. With improvements in scanner technology, MIP sections and VR images are a promising, non-invasive and accurate method of evaluating the canine thoracic vasculature. Images provide a reference material for clinical studies of the canine thorax for radiologist-surgeon teamwork assessment and also encourage the development of this technique in veterinary medicine.

  6. 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

  7. Optimal MRI sequence for identifying occlusion location in acute stroke: which value of time-resolved contrast-enhanced MRA?

    PubMed

    Le Bras, A; Raoult, H; Ferré, J-C; Ronzière, T; Gauvrit, J-Y

    2015-06-01

    Identifying occlusion location is crucial for determining the optimal therapeutic strategy during the acute phase of ischemic stroke. The purpose of this study was to assess the diagnostic efficacy of MR imaging, including conventional sequences plus time-resolved contrast-enhanced MRA in comparison with DSA for identifying arterial occlusion location. Thirty-two patients with 34 occlusion levels referred for thrombectomy during acute cerebral stroke events were consecutively included from August 2010 to December 2012. Before thrombectomy, we performed 3T MR imaging, including conventional 3D-TOF and gradient-echo T2 sequences, along with time-resolved contrast-enhanced MRA of the extra- and intracranial arteries. The 3D-TOF, gradient-echo T2, and time-resolved contrast-enhanced MRA results were consensually assessed by 2 neuroradiologists and compared with prethrombectomy DSA results in terms of occlusion location. The Wilcoxon test was used for statistical analysis to compare MR imaging sequences with DSA, and the κ coefficient was used to determine intermodality agreement. The occlusion level on the 3D-TOF and gradient-echo T2 images differed significantly from that of DSA (P < .001 and P = .002, respectively), while no significant difference was observed between DSA and time-resolved contrast-enhanced MRA (P = .125). κ coefficients for intermodality agreement with DSA (95% CI, percentage agreement) were 0.43 (0.3%-0.6; 62%), 0.32 (0.2%-0.5; 56%), and 0.81 (0.6%-1.0; 88%) for 3D-TOF, gradient-echo T2, and time-resolved contrast-enhanced MRA, respectively. The time-resolved contrast-enhanced MRA sequence proved reliable for identifying occlusion location in acute stroke with performance superior to that of 3D-TOF and gradient-echo T2 sequences. © 2015 by American Journal of Neuroradiology.

  8. Identification of novel inhibitors of phospho-MurNAc-pentapeptide translocase MraY from library screening: Isoquinoline alkaloid michellamine B and xanthene dye phloxine B.

    PubMed

    Mihalyi, Agnes; Jamshidi, Shirin; Slikas, Justinas; Bugg, Timothy D H

    2014-09-01

    The National Cancer Institute (NCI) Diversity Set was screened for potential inhibitors of phospho-MurNAc-pentapeptide translocase MraY from Escherichia coli using a primary fluorescence enhancement assay, followed by a secondary radiochemical assay. One new MraY inhibitor was identified from this screen, a naphthylisoquinoline alkaloid michellamine B, which inhibited E. coli MraY (IC50 456μM) and Bacillus subtilis MraY (IC50 386μM), and which showed antimicrobial activity against B. subtilis (MIC 16μg/mL). Following an earlier report of halogenated fluoresceins identified from a combined MraY/MurG screen, three halogenated fluoresceins were tested as inhibitors of E. coli MraY and E. coli MurG, and phloxine B was identified as an inhibitor of E. coli MraY (IC50 32μM). Molecular docking of inhibitor structures against the structure of Aquifex aeolicus MraY indicates that phloxine B appears to bind to the Mg(2+) cofactor in the enzyme active site, while michellamine B binds to a hydrophobic groove formed between transmembrane helices 5 and 9.

  9. Targeting the gram-negative bacteria peptidoglycan synthase MraY as a new approach for monoclonal antibody anti-bacterial activity.

    PubMed

    Cao, Jun; Yi, Fei; Tian, Qiufeng; Dang, Guanghui; Si, Wei; Liu, Siguo; Yu, Shenye

    2017-06-12

    The use of antibiotics to target bacteria is a well-validated approach for controlling infections in animals and humans. Peptidoglycan biosynthesis is a crucial process in bacteria, and the conserved peptidoglycan synthase MraY is an attractive target for drug design. However, due to the lack of detailed MraY structural information, antibiotics targeting MraY have not yet been developed. In the present study, 2 hydrophilic regions of MraY from Escherichia coli were expressed as a fusion protein and used to raise a monoclonal antibody in mice. We confirmed that the MraY amino acid sequence PESHFSKRGTPT forms the core epitope recognized by the monoclonal antibody M-H11. Furthermore, our results show that M-H11 effectively controls Escherichia coli BL21 (DE3) plysS infection, both in vitro and in vivo. Our results may be of great value in the search for novel approaches used to control bacterial infections.

  10. 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...

  11. 5 CFR 875.203 - Am I eligible if I separated under the FERS MRA+10 provision?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 5 Administrative Personnel 2 2011-01-01 2011-01-01 false Am I eligible if I separated under the FERS MRA+10 provision? 875.203 Section 875.203 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT (CONTINUED) CIVIL SERVICE REGULATIONS (CONTINUED) FEDERAL LONG TERM CARE INSURANCE PROGRAM Eligibility §...

  12. 5 CFR 875.203 - Am I eligible if I separated under the FERS MRA+10 provision?

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 5 Administrative Personnel 2 2012-01-01 2012-01-01 false Am I eligible if I separated under the FERS MRA+10 provision? 875.203 Section 875.203 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT (CONTINUED) CIVIL SERVICE REGULATIONS (CONTINUED) FEDERAL LONG TERM CARE INSURANCE PROGRAM Eligibility §...

  13. 5 CFR 875.203 - Am I eligible if I separated under the FERS MRA+10 provision?

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 5 Administrative Personnel 2 2013-01-01 2013-01-01 false Am I eligible if I separated under the FERS MRA+10 provision? 875.203 Section 875.203 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT (CONTINUED) CIVIL SERVICE REGULATIONS (CONTINUED) FEDERAL LONG TERM CARE INSURANCE PROGRAM Eligibility §...

  14. 5 CFR 875.203 - Am I eligible if I separated under the FERS MRA+10 provision?

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 5 Administrative Personnel 2 2014-01-01 2014-01-01 false Am I eligible if I separated under the FERS MRA+10 provision? 875.203 Section 875.203 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT (CONTINUED) CIVIL SERVICE REGULATIONS (CONTINUED) FEDERAL LONG TERM CARE INSURANCE PROGRAM Eligibility §...

  15. 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...

  16. Minimal requirements for inhibition of MraY by lysis protein E from bacteriophage ΦX174.

    PubMed

    Tanaka, Shiho; Clemons, William M

    2012-09-01

    The DNA phage ΦX174 encodes the integral membrane protein E whose expression leads to host cell lysis by inhibition of the peptidoglycan synthesis enzyme MraY. Here we use mutagenesis to characterize the molecular details of the E lysis mechanism. We find that a minimal 18-residue region with the modified wild-type sequences of the conserved transmembrane helix of E is sufficient to lyse host cells and that specific residues within and at the boundaries of this helix are important for activity. This suggests that positioning of the helix in the membrane is critical for interactions with MraY. We further characterize the interaction site of the transmembrane helix with MraY demonstrating E forms a stable complex with MraY. Triggering cell lysis by peptidoglycan synthesis inhibition is a traditional route for antimicrobial strategies. Understanding the mechanism of bacterial cell lysis by E will provide insights into new antimicrobial strategies using re-engineered E peptides. © 2012 Blackwell Publishing Ltd.

  17. Minimal requirements for inhibition of MraY by lysis protein E from bacteriophage ΦX174

    PubMed Central

    Tanaka, Shiho; Clemons, William M.

    2012-01-01

    Summary The DNA phage ΦX174 encodes the integral membrane protein E whose expression leads to host cell lysis by inhibition of the peptidoglycan synthesis enzyme MraY. Here we use mutagenesis to characterize the molecular details of the E lysis mechanism. We find that a minimal 18-residue region with the modified wild-type sequences of the conserved transmembrane helix of E is sufficient to lyse host cells and that specific residues within and at the boundaries of this helix are important for activity. This suggests that positioning of the helix in the membrane is critical for interactions with MraY. We further characterize the interaction site of the transmembrane helix with MraY demonstrating E forms a stable complex with MraY. Triggering cell lysis by peptidoglycan synthesis inhibition is a traditional route for antimicrobial strategies. Understanding the mechanism of bacterial cell lysis by E will provide insights into new antimicrobial strategies using re-engineered E peptides. PMID:22742425

  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

    ... 5 Administrative Personnel 2 2010-01-01 2010-01-01 false Am I eligible if I separated under the FERS MRA+10 provision? 875.203 Section 875.203 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT (CONTINUED) CIVIL SERVICE REGULATIONS (CONTINUED) FEDERAL LONG TERM CARE INSURANCE PROGRAM Eligibility §...

  19. Targeting the MraY and MurG bacterial enzymes for antimicrobial therapeutic intervention.

    PubMed

    Zawadzke, Laura E; Wu, Ping; Cook, Lynda; Fan, Li; Casperson, Margaret; Kishnani, Mona; Calambur, Deepa; Hofstead, Sandra J; Padmanabha, Ramesh

    2003-03-15

    Assays for two enzymes from Escherichia coli were developed and validated as antibacterial inhibitor screens. The MraY and MurG enzymes were overexpressed and purified as the membrane fraction or to homogeneity, respectively. The MurG enzyme was expressed with a six-histidine tag using an optimized minimal-medium protocol for subsequent purification. Although traditional assays were established, the enzymes were also assayed via a 96-well membrane plate assay and a 384-well scintillation proximity-based assay developed herein. These assays afford a more economical and high-throughput evaluation of inhibitors. A mureidomycin inhibitor mix was used as a control for the assay development and screen validation. Several inhibitors resulting from a high-throughput screen were found and evaluated for potential therapeutic use.

  20. Blood pool agent contrast-enhanced MRA: level-set-based artery-vein separation

    NASA Astrophysics Data System (ADS)

    van Bemmel, Cornelis M.; Spreeuwers, Luuk J.; Verdonck, Bert; Viergever, Max A.; Niessen, Wiro J.

    2002-05-01

    Blood pool agents (BPAs) for contrast-enhanced magnetic resonance angiography (CE-MRA) allow prolonged imaging times for higher contrast and resolution by imaging during the steady-state when the contrast agent is distributed through the complete vascular system. However, simultaneous venous and arterial enhancement hampers interpretation. It is shown that arterial and venous segmentation in this equilibrium phase can be achieved if the central arterial axis (CAA) and central venous axis (CVA) are known. Since the CAA can not straightforwardly be obtained from the steady-state data, images acquired during the first-pass of the contrast agent can be utilized to determine the CAA with minimal user initialization. Utilizing the CAA to provide a rough arterial segmentation, the CVA can subsequently be determined from the steady-state dataset. The final segmentations of the arteries and veins are achieved by simultaneously evolving two level-sets in the steady-state dataset starting from the CAA and CVA.

  1. Automated extraction and labelling of the arterial tree from whole-body MRA data.

    PubMed

    Shahzad, Rahil; Dzyubachyk, Oleh; Staring, Marius; Kullberg, Joel; Johansson, Lars; Ahlström, Håkan; Lelieveldt, Boudewijn P F; van der Geest, Rob J

    2015-08-01

    In this work, we present a fully automated algorithm for extraction of the 3D arterial tree and labelling the tree segments from whole-body magnetic resonance angiography (WB-MRA) sequences. The algorithm developed consists of two core parts (i) 3D volume reconstruction from different stations with simultaneous correction of different types of intensity inhomogeneity, and (ii) Extraction of the arterial tree and subsequent labelling of the pruned extracted tree. Extraction of the arterial tree is performed using the probability map of the "contrast" class, which is obtained as one of the results of the inhomogeneity correction scheme. We demonstrate that such approach is more robust than using the difference between the pre- and post-contrast channels traditionally used for this purpose. Labelling the extracted tree is performed by using a combination of graph-based and atlas-based approaches. Validation of our method with respect to the extracted tree was performed on the arterial tree subdivided into 32 segments, 82.4% of which were completely detected, 11.7% partially detected, and 5.9% were missed on a cohort of 35 subjects. With respect to automated labelling accuracy of the 32 segments, various registration strategies were investigated on a training set consisting of 10 scans. Further analysis on the test set consisting of 25 data sets indicates that 69% of the vessel centerline tree in the head and neck region, 80% in the thorax and abdomen region, and 84% in the legs was accurately labelled to the correct vessel segment. These results indicate clinical potential of our approach in enabling fully automated and accurate analysis of the entire arterial tree. This is the first study that not only automatically extracts the WB-MRA arterial tree, but also labels the vessel tree segments.

  2. Evaluation of velocity-sensitized and acceleration-sensitized NCE-MRA for below-knee peripheral arterial disease.

    PubMed

    Shaida, Nadeem; Priest, Andrew N; See, T C; Winterbottom, Andrew P; Graves, Martin J; Lomas, David J

    2017-06-01

    To evaluate the diagnostic performance of velocity- and acceleration-sensitized noncontrast-enhanced magnetic resonance angiography (NCE-MRA) of the infrageniculate arteries using contrast-enhanced MRA (CE-MRA) as a reference standard. Twenty-four patients with symptoms of peripheral arterial disease were recruited. Each patient's infrageniculate arterial tree was examined using a velocity-dependent flow-sensitized dephasing (VEL-FSD) technique, an acceleration-dependent (ACC-FSD) technique, and our conventional CE-MRA technique performed at 1.5T. The images were independently reviewed by two experienced vascular radiologists, who evaluated each vessel segment to assess visibility, diagnostic confidence, venous contamination, and detection of pathology. In all, 432 segments were evaluated by each of the three techniques by each reader in total. Overall diagnostic confidence was rated as moderate or high in 98.5% of segments with CE-MRA, 92.1% with VEL-FSD, and 79.9% with ACC-FSD. No venous contamination was seen in 96% of segments with CE-MRA, 72.2% with VEL-FSD, and 85.8% with ACC-FSD. Per-segment, per-limb, and per-patient sensitivities for detecting significant stenotic disease were 63.4%, 73%, and 92%, respectively, for ACC-FSD, and 65.3%, 87.2%, and 96% for VEL-FSD, and as such no significant statistical change was detected using McNemar's chi-squared test with P-values of 1.00, 0.13, and 0.77 obtained, respectively. Flow-dependent NCE-MRA techniques may have a role to play in evaluation of patients with peripheral vascular disease. Increased sensitivity of a velocity-based technique compared to an acceleration-based technique comes at the expense of greater venous contamination. 2J. Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2017;45:1846-1853. © 2016 International Society for Magnetic Resonance in Medicine.

  3. Follow-up of intracranial aneurysms treated by flow diverter: comparison of three-dimensional time-of-flight MR angiography (3D-TOF-MRA) and contrast-enhanced MR angiography (CE-MRA) sequences with digital subtraction angiography as the gold standard.

    PubMed

    Attali, Jonathan; Benaissa, Azzedine; Soize, Sébastien; Kadziolka, Krzysztof; Portefaix, Christophe; Pierot, Laurent

    2016-01-01

    Follow-up of intracranial aneurysms treated by flow diverter with MRI is complicated by imaging artifacts produced by these devices. This study compares the diagnostic accuracy of three-dimensional time-of-flight MR angiography (3D-TOF-MRA) and contrast-enhanced MRA (CE-MRA) at 3 T for the evaluation of aneurysm occlusion and parent artery patency after flow diversion treatment, with digital subtraction angiography (DSA) as the gold standard. Patients treated with flow diverters between January 2009 and January 2013 followed by MRA at 3 T (3D-TOF-MRA and CE-MRA) and DSA within a 48 h period were included in a prospective single-center study. Aneurysm occlusion was assessed with full and simplified Montreal scales and parent artery patency with three-grade and two-grade scales. Twenty-two patients harboring 23 treated aneurysms were included. Interobserver agreement using simplified scales for occlusion (Montreal) and parent artery patency were higher for DSA (0.88 and 0.61) and CE-MRA (0.74 and 0.55) than for 3D-TOF-MRA (0.51 and 0.02). Intermodality agreement was higher for CE-MRA (0.88 and 0.32) than for 3D-TOF-MRA (0.59 and 0.11). CE-MRA yielded better accuracy than 3D-TOF-MRA for aneurysm remnant detection (sensitivity 83% vs 50%; specificity 100% vs 100%) and for the status of the parent artery (specificity 63% vs 32%; sensitivity 100% vs 100%). At 3 T, CE-MRA is superior to 3D-TOF-MRA for the evaluation of aneurysm occlusion and parent artery patency after flow diversion treatment. However, intraluminal evaluation remains difficult with MRA regardless of the sequence used. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  4. Dynamic contrast-enhanced MRA at 1.5 T for detection of arteriovenous shunting before and after Onyx embolization of cerebral arteriovenous malformations.

    PubMed

    Nogueira, Raul G; Bayrlee, Ahmad; Hirsch, Joshua A; Yoo, Albert J; Copen, William A

    2013-10-01

    Conventional non-invasive angiographic techniques for evaluating cerebral Arteriovenous Malformations (cAVMs) after embolization treatment are limited by their inability to acquire time-resolved images. We describe the use of dynamic contrast-enhanced magnetic resonance angiography (MRA) in the evaluation of residual arteriovenous shunting in cAVMs following Onyx embolization. Six subjects who underwent multimodal MR imaging including dynamic MRA after different stages of endovascular treatment with Onyx were included. Each MRA was assessed for the presence of residual arteriovenous shunting. The results were compared with digital subtraction angiography (DSA). Mean age was 41 years (range, 25-63) and the mean maximum AVM diameter was 5.3 cm (range, 4.7-6.0). Fourteen dynamic MRA were performed using a 1.5 T scanner. Arteriovenous shunting was detected in thirteen of fourteen patients by both dynamic MRA and DSA, with complete agreement between the two techniques. The only MRA without detectable residual arteriovenous shunting was for a subject who had complete treatment with no residual cAVM as confirmed by the DSA images. Dynamic contrast-enhanced MRA is a promising non-invasive modality in identifying residual arteriovenous shunting after different stages of AVM embolization, achieving 100% agreement in this small study. Embolization with Onyx caused no significant image artifact. Copyright © 2013 by the American Society of Neuroimaging.

  5. Selection and Evaluation of Optimal Two-Dimensional CAIPIRINHA Kernels Applied to Time-Resolved Three-Dimensional CE-MRA

    PubMed Central

    Weavers, Paul T.; Borisch, Eric A.; Riederer, Stephen J.

    2015-01-01

    Purpose To develop and validate a method for choosing the optimal two-dimensional CAIPIRINHA kernel for subtraction contrast-enhanced MR angiography (CE-MRA) and estimate the degree of image quality improvement versus that of some reference acceleration parameter set at R≥8. Methods A metric based on patient-specific coil calibration information was defined for evaluating optimality of CAIPIRINHA kernels as applied to subtraction CE-MRA. Evaluation in retrospective studies using archived coil calibration data from abdomen, calf, foot, and hand CE-MRA exams was accomplished with an evaluation metric comparing the geometry factor (g-factor) histograms. Prospective calf, foot, and hand CE-MRA studies were evaluated with vessel signal-to-noise ratio (SNR). Results Retrospective studies show g-factor improvement for the selected CAIPIRINHA kernels was significant in the feet, moderate in the abdomen, and modest in the calves and hands. Prospective CE-MRA studies using optimal CAIPIRINHA show reduced noise amplification with identical acquisition time in studies of the feet, with minor improvements in the hands and calves. Conclusion A method for selection of the optimal CAIPIRINHA kernel for high (R≥8) acceleration CE-MRA exams given a specific patient and receiver array was demonstrated. CAIPIRINHA optimization appears valuable in accelerated CE-MRA of the feet and to a lesser extent in the abdomen. PMID:25046590

  6. Inhibition of phospho-MurNAc-pentapeptide translocase (MraY) by nucleoside natural product antibiotics, bacteriophage ϕX174 lysis protein E, and cationic antibacterial peptides.

    PubMed

    Bugg, Timothy D H; Rodolis, Maria T; Mihalyi, Agnes; Jamshidi, Shirin

    2016-12-15

    This review covers recent developments in the inhibition of translocase MraY and related phospho-GlcNAc transferases WecA and TagO, and insight into the inhibition and catalytic mechanism of this class of integral membrane proteins from the structure of Aquifex aeolicus MraY. Recent studies have also identified a protein-protein interaction site in Escherichia coli MraY, that is targeted by bacteriophage ϕX174 lysis protein E, and also by cationic antimicrobial peptides containing Arg-Trp close to their N- or C-termini. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Ligand Shaping in Induced Fit Docking of MraY Inhibitors. Polynomial Discriminant and Laplacian Operator as Biological Activity Descriptors

    PubMed Central

    Diudea, Mircea V.; Putz, Mihai V.

    2017-01-01

    Docking—i.e., interaction of a small molecule (ligand) with a proteic structure (receptor)—represents the ground of drug action mechanism of the vast majority of bioactive chemicals. Ligand and receptor accommodate their geometry and energy, within this interaction, in the benefit of receptor–ligand complex. In an induced fit docking, the structure of ligand is most susceptible to changes in topology and energy, comparative to the receptor. These changes can be described by manifold hypersurfaces, in terms of polynomial discriminant and Laplacian operator. Such topological surfaces were represented for each MraY (phospho-MurNAc-pentapeptide translocase) inhibitor, studied before and after docking with MraY. Binding affinities of all ligands were calculated by this procedure. For each ligand, Laplacian and polynomial discriminant were correlated with the ligand minimum inhibitory concentration (MIC) retrieved from literature. It was observed that MIC is correlated with Laplacian and polynomial discriminant. PMID:28653980

  8. Ligand Shaping in Induced Fit Docking of MraY Inhibitors. Polynomial Discriminant and Laplacian Operator as Biological Activity Descriptors.

    PubMed

    Lungu, Claudiu N; Diudea, Mircea V; Putz, Mihai V

    2017-06-27

    Docking-i.e., interaction of a small molecule (ligand) with a proteic structure (receptor)-represents the ground of drug action mechanism of the vast majority of bioactive chemicals. Ligand and receptor accommodate their geometry and energy, within this interaction, in the benefit of receptor-ligand complex. In an induced fit docking, the structure of ligand is most susceptible to changes in topology and energy, comparative to the receptor. These changes can be described by manifold hypersurfaces, in terms of polynomial discriminant and Laplacian operator. Such topological surfaces were represented for each MraY (phospho-MurNAc-pentapeptide translocase) inhibitor, studied before and after docking with MraY. Binding affinities of all ligands were calculated by this procedure. For each ligand, Laplacian and polynomial discriminant were correlated with the ligand minimum inhibitory concentration (MIC) retrieved from literature. It was observed that MIC is correlated with Laplacian and polynomial discriminant.

  9. A high-throughput, homogeneous, fluorescence resonance energy transfer-based assay for phospho-N-acetylmuramoyl-pentapeptide translocase (MraY).

    PubMed

    Shapiro, Adam B; Jahić, Haris; Gao, Ning; Hajec, Laurel; Rivin, Olga

    2012-06-01

    Peptidoglycan biosynthesis is an essential process in bacteria and is therefore a suitable target for the discovery of new antibacterial drugs. One of the last cytoplasmic steps of peptidoglycan biosynthesis is catalyzed by the integral membrane protein MraY, which attaches soluble UDP-N-acetylmuramoyl-pentapeptide to the membrane-bound acceptor undecaprenyl phosphate. Although several natural product-derived inhibitors of MraY are known, none have the properties necessary to be of clinical use as antibacterial drugs. Here we describe a novel, homogeneous, fluorescence resonance energy transfer-based MraY assay that is suitable for high-throughput screening for novel MraY inhibitors. The assay allows for continuous measurement, or it can be quenched prior to measurement.

  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. 5'-Methylene-triazole-substituted-aminoribosyl uridines as MraY inhibitors: synthesis, biological evaluation and molecular modeling.

    PubMed

    Fer, Mickaël J; Bouhss, Ahmed; Patrão, Mariana; Le Corre, Laurent; Pietrancosta, Nicolas; Amoroso, Ana; Joris, Bernard; Mengin-Lecreulx, Dominique; Calvet-Vitale, Sandrine; Gravier-Pelletier, Christine

    2015-07-14

    The straightforward synthesis of 5'-methylene-[1,4]-triazole-substituted aminoribosyl uridines is described. Two families of compounds were synthesized from a unique epoxide which was regioselectively opened by acetylide ions (for compounds II) or azide ions (for compounds III). Sequential diastereoselective glycosylation with a ribosyl fluoride derivative, Cu(i)-catalyzed azide-alkyne cycloaddition (CuAAC) with various complementary azide and alkyne partners afforded the targeted compounds after final deprotection. The biological activity of the 16 resulting compounds together with that of 14 previously reported compounds I, lacking the 5' methylene group, was evaluated on the MraY transferase activity. Out of the 30 tested compounds, 18 compounds revealed MraY inhibition with IC50 ranging from 15 to 150 μM. A molecular modeling study was performed to rationalize the observed structure-activity relationships (SAR), which allowed us to correlate the activity of the most potent compounds with an interaction involving Leu191 of MraYAA. The antibacterial activity was also evaluated and seven compounds exhibited a good activity against Gram-positive bacterial pathogens with MIC ranging from 8 to 32 μg mL(-1), including the methicillin resistant Staphylococcus aureus (MRSA).

  12. 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.

  13. CAD scheme for detection of intracranial aneurysms in MRA based on 3D analysis of vessel skeletons and enhanced aneurysms

    NASA Astrophysics Data System (ADS)

    Arimura, Hidetaka; Li, Qiang; Korogi, Yukunori; Hirai, Toshinori; Yamashita, Yasuyuki; Katsuragawa, Shigehiko; Ikeda, Ryuji; Doi, Kunio

    2005-04-01

    We have developed a computer-aided diagnostic (CAD) scheme for detection of unruptured intracranial aneurysms in magnetic resonance angiography (MRA) based on findings of short branches in vessel skeletons, and a three-dimensional (3D) selective enhancement filter for dots (aneurysms). Fifty-three cases with 61 unruptured aneurysms and 62 non-aneurysm cases were tested in this study. The isotropic 3D MRA images with 400 x 400 x 128 voxels (a voxel size of 0.5 mm) were processed by use of the dot enhancement filter. The initial candidates were identified not only on the dot-enhanced images by use of a multiple gray-level thresholding technique, but also on the vessel skeletons by finding short branches on parent skeletons, which can indicate a high likelihood of small aneurysms. All candidates were classified into four categories of candidates according to effective diameter and local structure of the vessel skeleton. In each category, a number of false positives were removed by use of two rule-based schemes and by linear discriminant analysis on localized image features related to gray level and morphology. Our CAD scheme achieved a sensitivity of 97% with 5.0 false positives per patient by use of a leave-one-out-by-patient test method. This CAD system may be useful in assisting radiologists in the detection of small intracranial aneurysms as well as medium-size aneurysms in MRA.

  14. The probability of middle cerebral artery MRA flow signal abnormality with quantified CT ischaemic change: targets for future therapeutic studies.

    PubMed

    Barber, P A; Demchuk, A M; Hill, M D; Pexman, J H Warwick; Hudon, M E; Frayne, R; Buchan, A M

    2004-10-01

    In this study we define the probability of vascular abnormality in the middle cerebral artery (MCA) territory according to the extent of ischaemic change seen using computed tomography (CT). We assessed the sensitivity and specificity of the hyperdense middle cerebral artery (HMCA) and the "dot" sign using magnetic resonance angiography (MRA). Patients presenting with ischaemic stroke had a CT scan (<6 h) prior to MRI (<7 h). A quantitative CT scoring system (ASPECTS) was applied to CT and diffusion weighted images (DWI) at baseline and follow up (24 h) by five independent observers. The presence of HMCA and the MCA "dot" sign was also evaluated. An expert reader assessed the 3D time of flight (TOF) MRA in the anterior circulation for areas of decreased vascular signal in the MCA territory, with an absent signal taken to represent severely reduced or absent flow. A total of 100 consecutive patients had baseline CT and MR scans. The median NIHSS was 9. The median CT ASPECTS was 8 and equalled the median DWI ASPECTS. There were a total of 10 HMCA and 19 MCA "dot" signs, with four patients having both HMCA and "dot" signs. A total of 47 MRA flow signal abnormalities were observed in the anterior circulation. In the absence of accessible neurovascular imaging, the extent of CT ischaemia (ASPECTS) is a strong predictor of vascular occlusion. The CT hyperdense artery signs have a high positive predictive value but low negative predictive value.

  15. Synthesis and biological evaluation of potential new inhibitors of the bacterial transferase MraY with a β-ketophosphonate structure.

    PubMed

    Auberger, Nicolas; Frlan, Rok; Al-Dabbagh, Bayan; Bouhss, Ahmed; Crouvoisier, Muriel; Gravier-Pelletier, Christine; Le Merrer, Yves

    2011-12-21

    Stable analogs of bacterial transferase MraY substrate or product with a pyrophosphate surrogate in their structure are described. β-ketophosphonates were designed as pyrophosphate bioisosteres and were investigated as UDP-GlcNAc mimics. The developed strategy allows introduction of structural diversity at a late stage of the synthesis. The biological activity of the synthesized compounds was evaluated on the MraY enzyme.

  16. The peptidoglycan biosynthesis genes MurA and MraY are related to chloroplast division in the moss Physcomitrella patens.

    PubMed

    Homi, Shoko; Takechi, Katsuaki; Tanidokoro, Koji; Sato, Hiroshi; Takio, Susumu; Takano, Hiroyoshi

    2009-12-01

    In the moss Physcomitrella patens, 10 Mur genes involved in peptidoglycan biosynthesis were found, and the MurE and Pbp genes are related to plastid division. Although the MraY and MurG genes were missing in our previous expressed sequence tag screening, they were discovered in the P. patens genome in this study, indicating that P. patens has a full set of genes capable of synthesizing peptidoglycan. In addition, a second MurA gene (PpMurA2) was found. Whereas Northern analyses indicated that PpMurA1, PpMurG and PpMraY were expressed, transcripts of PpMurA2 were detected only when RT-PCR was employed. Whereas GFP fusion proteins with either PpMurA1 or PpMraY were detected in chloroplasts, the PpMurA2 fusion proteins were located in the cytoplasm. Protonema cells in the wild-type plants had an average of 46 chloroplasts. PpMurA1 gene-disrupted lines had <10 chloroplasts, whereas approximately 30 chloroplasts existed in the PpMurA2 knockout lines. The PpMurA1/A2 double-knockout lines had only a few macrochloroplasts, suggesting a redundant function for these two genes. Disruption of the PpMraY gene in P. patens resulted in the appearance of macrochloroplasts. Anabaena MraY fused to the N-terminal region of PpMraY and A. thaliana MraY could complement the macrochloroplast phenotype in the PpMraY knockout line. Electron microscopic observations showed no obvious differences in the shape or stacking of thylakoid membranes between all knockout transformants and wild-type plants, suggesting that these Mur genes are related only to plastid division in moss.

  17. Pre-ablative high-resolution MRA facilitates electrophysiologic pulmonary vein ablation and reduces fluoroscopy time in patients with paroxysmal atrial fibrillation

    NASA Astrophysics Data System (ADS)

    Collins, Jeremy D.; Pereles, F. S.; Bello, David; Betts, Timothy; Zachariah, Anish; Kaliney, Ryan; Song, Gina K.; Shors, Stephanie M.; Carr, James C.; Finn, John P.

    2003-05-01

    Pulmonary MRA generates high-resolution images of the pulmonary veins (PV) and left atrium (LA), permitting characterization of complex PV anatomy, which is useful in electrophysiologic PV catheter ablation, a proven technique for the treatment of paroxysmal atrial fibrillation (PAF). The purpose of this study was to determine if pre-ablative pulmonary MRA with intra-ablative viewing facilitates ablation by reducing fluoroscopy time. We studied the morphology of the LA and PV at 1.5T (Magnetom Sonata, Siemens Medical Solutions, Erlangen Germany) with breath-held gadolinium-enhanced 3D MRA in 7 patients with PAF undergoing PV ablation. Data was volume rendered (VR) on a stereoscopic workstation. PV ostial diameter and cross-sectional area measurements were obtained on multi-planar reformatted (MPR) images. VR datasets were converted into digital movies and were viewed on a laptop computer adjacent to real-time fluoroscopic images. Fluoroscopy times for patients undergoing pre-ablative MPA mapping were compared with a cohort of 22 consecutive patients diagnosed with PAF who underwent catheter ablation without pre-ablative MRA planning. Mean PV ablation fluoroscopic time with MRA planning versus fluoroscopic imaging alone were 84+/-20 minutes and 114+/-20 minutes respectively. Pre-ablative MRA planning resulted in a significant mean fluoroscopy time savings of 26% (p<0.05). In patients with PAF undergoing PV ablation, analysis of MRA datasets depicting PV anatomy confirms that there is great variability in anatomy between veins. Pre-ablative 3D PV mapping by MRA greatly facilitates fluoroscopic identification of individual veins and significantly reduces fluoroscopic radiation time.

  18. The lysis protein E of phi X174 is a specific inhibitor of the MraY-catalyzed step in peptidoglycan synthesis.

    PubMed

    Bernhardt, T G; Struck, D K; Young, R

    2001-03-02

    Coliphage phi X174 encodes a single lysis protein, E, a 91-amino acid membrane protein. Dominant mutations have been isolated in the host gene mraY that confer E resistance. mraY encodes translocase I, which catalyzes the formation of the first lipid intermediate in bacterial cell wall synthesis, suggesting a model in which E inhibits MraY and promotes cell lysis in a manner analogous to cell wall synthesis inhibitors like penicillin. To test this model biochemically, we monitored the effect of E on cell wall synthesis in vivo and in vitro. We find that expression of Emyc, encoding an epitope-tagged E protein, from a multicopy plasmid inhibits the incorporation of [(3)H]diaminopimelic acid into cell wall and leads to a profile of labeled precursors consistent with MraY inhibition. Moreover, we find that membranes isolated after Emyc expression are drastically reduced in MraY activity, whereas the activity of Rfe, an enzyme in the same superfamily, was unaffected. We therefore conclude that E is indeed a cell wall synthesis inhibitor and that this inhibition results from a specific block at the MraY-catalyzed step in the pathway.

  19. Three-dimensional dynamic time-resolved contrast-enhanced MRA using parallel imaging and a variable rate k-space sampling strategy in intracranial arteriovenous malformations.

    PubMed

    Petkova, Mina; Gauvrit, Jean-Yves; Trystram, Denis; Nataf, François; Godon-Hardy, Sylvie; Munier, Thierry; Oppenheim, Catherine; Meder, Jean-François

    2009-01-01

    To evaluate the effectiveness of three-dimensional (3D) dynamic time-resolved contrast-enhanced MRA (TR-CE-MRA) using a combination of a parallel imaging technique (ASSET: array spatial sensitivity encoding technique) and a time-resolved method (TRICKS: time-resolved imaging of contrast kinetics) and to compare it with 3D dynamic TR-CE-MRA using ASSET alone in the assessment of intracranial arteriovenous malformations (AVMs). Twenty consecutive patients with angiographically confirmed AVMs were investigated using both 3D dynamic TR-CE-MRA techniques. Examinations were compared with respect to image quality, spatial resolution, number and type of feeders and drainers, nidus size, presence of early venous filling and temporal resolution. Digital subtraction angiography was used as standard of reference. The higher temporal and spatial resolution of 3D dynamic TR-CE-MRA TRICKS ASSET allowed a better assessment of intracranial vascular malformations, namely better depiction of feeders, drainers and better detection of early venous drainage. There was no significant difference between them in terms of nidus size. 3D dynamic TR-CE-MRA combining parallel imaging and a time-resolved method with subsecond and submillimeter resolution could become the first-line investigation technique in both diagnosis and follow-up of intracranial AVMs.

  20. 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

  1. Identification of a novel inhibition site in translocase MraY based upon the site of interaction with lysis protein E from bacteriophage ϕX174.

    PubMed

    Rodolis, Maria T; Mihalyi, Agnes; O'Reilly, Amy; Slikas, Justinas; Roper, David I; Hancock, Robert E W; Bugg, Timothy D H

    2014-06-16

    Translocase MraY is the site of action of lysis protein E from bacteriophage ϕX174. Previous genetic studies have shown that mutation F288L in transmembrane helix 9 of E. coli MraY confers resistance to protein E. Construction of a helical wheel model for transmembrane helix 9 of MraY and the transmembrane domain of protein E enabled the identification of an Arg-Trp-x-x-Trp (RWxxW) motif in protein E that might interact with Phe288 of MraY and the neighbouring Glu287. This motif is also found in a number of cationic antimicrobial peptide sequences. Synthetic dipeptides and pentapeptides based on the RWxxW consensus sequence showed inhibition of particulate E. coli MraY activity (IC50 200-600 μM), and demonstrated antimicrobial activity against E. coli (MIC 31-125 μg mL(-1)). Cationic antimicrobial peptides at a concentration of 100 μg mL(-1) containing Arg-Trp sequences also showed 30-60 % inhibition of E. coli MraY activity. Assay of the synthetic peptide inhibitors against recombinant MraY enzymes from Bacillus subtilis, Pseudomonas aeruginosa, and Micrococcus flavus (all of which lack Phe288) showed reduced levels of enzyme inhibition, and assay against recombinant E. coli MraY F288L and an E287A mutant demonstrated either reduced or no detectable enzyme inhibition, thus indicating that these peptides interact at this site. The MIC of Arg-Trp-octyl ester against E. coli was increased eightfold by overexpression of mraY, and was further increased by overexpression of the mraY mutant F288L, also consistent with inhibition at the RWxxW site. As this site is on the exterior face of the cytoplasmic membrane, it constitutes a potential new site for antimicrobial action, and provides a new cellular target for cationic antimicrobial peptides. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Susceptibility-weighted angiography (SWAN) of cerebral veins and arteries compared to TOF-MRA.

    PubMed

    Boeckh-Behrens, T; Lutz, J; Lummel, N; Burke, M; Wesemann, T; Schöpf, V; Brückmann, H; Linn, J

    2012-06-01

    High resolution, non-contrast imaging of both cerebral veins and arteries by use of gradient echo T2 star weighted angiography (SWAN) is a new method for susceptibility-weighted imaging with short acquisition times. We assessed the potential of this sequence for the depiction of both cerebral veins and arteries. 15 healthy volunteers were included in the study. MRI was performed on a 3T MR scanner using the following sequences: (1) a 3D multi-echo gradient echo T2 star weighted angiography (SWAN), (2) an arterial 3D TOF MR angiography and (3) a venous 2D TOF. With regard to the SWAN sequence, both MinIP and MIP images were reconstructed and systematically compared to MIP reconstructions of the artTOF and the venTOF. To suggest possible clinical implications of our findings, we additionally included two illustrative cases. With regard to the visualization of the cerebral veins, the MinIP reconstructions of the SWAN sequence were considerably superior compared to the venTOF. Concerning the depiction of the main segments of the big cerebral arteries the value of the MIP reconstructions of the SWAN was comparable to that of the artTOF with limitations in the homogenity and in the depiction of smaller arteries. SWAN allows for high-resolution visualization of both cerebral veins and arteries in one sequence without application of contrast agent and with significantly shortened scan time compared to the combined scan time of TOF-MRA and TOF-MRV. By use of either MinIP or MIP reconstructions, the arteries can be distinguished from the veins. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  3. 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. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

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

    PubMed Central

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

    2016-01-01

    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

  5. Comparison of vessel enhancement algorithms applied to Time-of-Flight MRA images for cerebrovascular segmentation.

    PubMed

    Phellan, Renzo; Forkert, Nils D

    2017-09-07

    Vessel enhancement algorithms are often used as a preprocessing step for vessel segmentation in medical images to improve the overall segmentation accuracy. Each algorithm uses different characteristics to enhance vessels, such that the most suitable algorithm may vary for different applications. This paper presents a comparative analysis of the accuracy gains in vessel segmentation generated by the use of nine vessel enhancement algorithms: Multiscale vesselness using the formulas described by Erdt (MSE), Frangi (MSF), and Sato (MSS), optimally oriented ux (OOF), ranking orientations responses path operator (RORPO), the regularized Perona-Malik approach (RPM), vessel enhanced diffusion (VED), hybrid diffusion with continuous switch (HDCS), and the white top hat algorithm (WTH). The filters were evaluated and compared based on time-of-flight MRA datasets and corresponding manual segmentations from _ve healthy subjects and ten patients with an arteriovenous malformation. Additionally, five synthetic angiographic datasets with corresponding ground truth segmentation were generated with three different noise levels (low, medium, high) and also used for comparison. The parameters for each algorithm and subsequent segmentation were optimized using leave-one-out cross evaluation. The Dice coefficient, Matthews correlation coefficient, area under the ROC curve, number of connected components, and true positives were used for comparison. The results of this study suggest that vessel enhancement algorithms do not always lead to more accurate segmentation results compared to segmenting non-enhanced images directly. Multiscale vesselness algorithms, such as MSE, MSF, and MSS proved to be robust to noise, while diffusion-based filters, such as RPM, VED, and HDCS ranked in the top of the list in scenarios with medium or no noise. Filters that assume tubular-shapes, such as MSE, MSF, MSS, OOF, RORPO, and VED show a decrease in accuracy when considering patients with an AVM

  6. Preoperative detection of the neurovascular relationship in trigeminal neuralgia using three-dimensional fast imaging employing steady-state acquisition (FIESTA) and magnetic resonance angiography (MRA).

    PubMed

    Zeng, QingShi; Zhou, Qin; Liu, ZhiLing; Li, ChuanFu; Ni, ShiLei; Xue, Feng

    2013-01-01

    Microvascular decompression is an accepted treatment for trigeminal neuralgia (TN). Preoperative identification of neurovascular compression, therefore, could aid determination of the appropriate treatment for TN. To preoperatively visualize the neurovascular relationship, three-dimensional fast imaging employing steady-state acquisition (3D FIESTA) and magnetic resonance angiography (MRA) were performed on 37 patients with TN in our study. 3D FIESTA in combination with MRA identified surgically verified neurovascular contact in 35 of 36 symptomatic nerves. The offending vessel (artery or vein) was correctly identified in 94.4% of patients, and agreement between preoperative MRI visualization and surgical findings was excellent (k=0.92; 95% confidence interval, 0.67-1.00). Thus, 3D FIESTA in combination with MRA is useful in the detection of vascular contact with the trigeminal nerve in patients with TN.

  7. Middle cerebral artery blood flows by combining TCD velocities and MRA diameters: in vitro and in vivo validations.

    PubMed

    Yonan, K A; Greene, E R; Sharrar, J M; Caprihan, A; Qualls, C; Roldan, C A

    2014-11-01

    Non-invasive transcranial Doppler (TCD) is widely used for blood velocity (BV, cm/sec) measurements in the human middle cerebral artery (MCA). MCABV measurements are accepted as linear with MCA blood flow (MCABF). Magnetic resonance angiography (MRA) provides measurements of MCA lumen diameters that can be combined with TCD MCABV to calculate MCABF (mL/min). We tested the precision and accuracy of this method against a flow phantom and in vivo proximal internal carotid artery blood flow (ICABF). In vitro precision (repeated measures) and accuracy (vs. time collection) gave correlations coefficients of 0.97 and 0.98, respectively (both p < 0.05). In vivo precision (repeated measures) and accuracy (vs. ICABF) gave correlation coefficients of 0.90 (left and right), 0.94 (left) and 0.93 (right) (all p < 0.05). Bilateral MCABF in 35 adults were similar (left, 168 ± 72 mL/min; right, 180 ± 69 mL/min; p > 0.05). Results suggest that blood velocity by TCD and lumen diameter by MRA can be combined to estimate absolute values of MCABF. Copyright © 2014 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  8. Middle cerebral artery blood flows by combining TCD velocities and MRA diameters: in vitro and in vivo validations

    PubMed Central

    KA, Yonan; ER, Greene; JM, Sharrar; A, Caprihan; C, Qualls; CA, Roldan

    2014-01-01

    Noninvasive transcranial Doppler (TCD) is widely used for blood velocity (BV, cm/sec) measurements in the human middle cerebral artery (MCA). MCABV measurements are accepted as linear with MCA blood flow (MCABF). Magnetic resonance angiography (MRA) provides measurements of MCA lumen diameters that can be combined with TCD MCABV to calculate MCABF (ml/min). We tested the precision and accuracy of this method against a flow phantom and in vivo proximal internal carotid artery blood flow (ICABF). In vitro precision (repeated measures) and accuracy (versus time collection) gave correlations coefficients of 0.97 and 0.98; respectfully (both p<0.05). In vivo precision (repeated measures) and accuracy (versus ICABF) gave correlation coefficients of 0.90 (left and right), and 0.94 (left) and 0.93 (right) (all p<0.05). Bilateral MCABF in 35 adults were similar (left, 168±72 ml/min; right, 180±69 ml/min; p>0.05). Results suggest that blood velocity by TCD and lumen diameter by MRA can be combined to estimate absolute values of MCABF. PMID:25218448

  9. Synthesis of sub-micromolar inhibitors of MraY by exploring the region originally occupied by the diazepanone ring in the liposidomycin structure.

    PubMed

    Dini, C; Didier-Laurent, S; Drochon, N; Feteanu, S; Guillot, J C; Monti, F; Uridat, E; Zhang, J; Aszodi, J

    2002-04-22

    The synthesis and inhibitory activity against MraY of a series of simplified analogues of liposidomycins are described. These compounds were mainly obtained by performing parallel synthesis in the 6'-position of a scaffold that gathers key features found necessary for the binding to MraY. Thus, inhibitory activity was improved from 5300 to 140 nM. This improvement was correlated with the length and lipophilicity of substituents, but was found to be independent of the nature of the chemical bond generated. In addition, some of these inhibitors presented encouraging antibacterial activities.

  10. Mechanism of action of the uridyl peptide antibiotics: an unexpected link to a protein-protein interaction site in translocase MraY.

    PubMed

    Rodolis, Maria T; Mihalyi, Agnes; Ducho, Christian; Eitel, Kornelia; Gust, Bertolt; Goss, Rebecca J M; Bugg, Timothy D H

    2014-11-07

    The pacidamycin and muraymycin uridyl peptide antibiotics show some structural resemblance to an Arg-Trp-x-x-Trp sequence motif for protein-protein interaction between bacteriophage ϕX174 protein E and E. coli translocase MraY. Members of the UPA class, and a synthetic uridine-peptide analogue, were found to show reduced levels of inhibition to F288L or E287A mutant MraY enzymes, implying that the UPAs interact at this extracellular site as part of the enzyme inhibition mechanism.

  11. 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 ...

  12. 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...

  13. 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...

  14. 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 ...

  15. Synthesis of analogues of the O-beta-D-ribofuranosyl nucleoside moiety of liposidomycins. Part 2: role of the hydroxyl groups upon the inhibition of MraY.

    PubMed

    Dini, C; Drochon, N; Guillot, J C; Mauvais, P; Walter, P; Aszodi, J

    2001-02-26

    O-beta-D-ribofuranosyl nucleoside I is the minimal structural entity of liposidomycins that maintains enzyme inhibitory activity on MraY. A set of compounds with hydroxyl patterns different from I has been synthesized. The presence of a hydroxyl group in the 3" position is essential for the activity. The 3'-deoxy derivative (IV), however, shows a 5-fold improved potency.

  16. Synthesis of gem-difluorinated nucleoside analogues of the liposidomycins and evaluation as MraY inhibitors.

    PubMed

    Xu, Xiu-Hua; Trunkfield, Amy E; Bugg, Timothy D H; Qing, Feng-Ling

    2008-01-07

    Two gem-difluoromethylenated nucleoside moieties of liposidomycins, 3 and 4, were designed and synthesized. Compound 3 was assembled from lactol 5 and gem-difluoromethylenated nucleoside 6. In the synthesis of target molecule 4, the coupling of the trichloroacetimidate derivative of gem-difluoromethylenated furanose 7 with nucleoside 8 in the presence of TMSOTf gave the unexpected compound 16 when CH3CN was used as solvent. This results from acetonitrile acting as a nucleophile and participating in the glycosylation reaction. This unusual process may be correlated with the presence of the electron-withdrawing gem-difluoro substituents at the C-2 position of furanose. Compound 3 demonstrated 29% inhibition of MraY at 11.4 mM.

  17. Time-resolved 3D contrast-enhanced MRA of an extended FOV using continuous table motion.

    PubMed

    Madhuranthakam, Ananth J; Kruger, David G; Riederer, Stephen J; Glockner, James F; Hu, Houchun H

    2004-03-01

    A method is presented for acquiring 3D time-resolved MR images of an extended (>100 cm) longitudinal field of view (FOV), as used for peripheral MR angiographic runoff studies. Previous techniques for long-FOV peripheral MRA have generally provided a single image (i.e., with no time resolution). The technique presented here generates a time series of 3D images of the FOV that lies within the homogeneous volume of the magnet. This is achieved by differential sampling of 3D k-space during continuous motion of the patient table. Each point in the object is interrogated in five consecutive 3D image sets generated at 2.5-s intervals. The method was tested experimentally in eight human subjects, and the leading edge of the bolus was observed in real time and maintained within the imaging FOV. The data revealed differential bolus velocities along the vasculature of the legs.

  18. High-resolution intracranial and cervical MRA at 3.0T: technical considerations and initial experience.

    PubMed

    Bernstein, M A; Huston, J; Lin, C; Gibbs, G F; Felmlee, J P

    2001-11-01

    Initial experience with intracranial and cervical MRA at 3.0T is reported. Phantom measurements (corrected for relaxation effects) show S/N (3.0T) = 2.14 +/- 0.08 x S/N (1.5T) in identical-geometry head coils. A 3.0T 3DTOF intracranial imaging protocol with higher-order autoshimming was developed and compared to 1.5T 3DTOF in 12 patients with aneurysms. A comparison by two radiologists showed the 3.0T to be significantly better (P < 0.001) for visualization of the aneurysms. The feasibility of cervical and intracranial contrast enhanced MR angiography (CEMRA) at 3.0T is also examined. The relaxivity of the gadolinium contrast agent decreases by only about 4-7% when the field strength is increased from 1.5 to 3.0T. Cervical 3.0T CEMRA was obtained in eight patients, two of whom had 1.5T studies available for direct comparison. Image comparison suggests 3.0T to be a favorable field strength for cervical CEMRA. Voxel volumes of 0.62-0.73 mm(3) (not including zero-filling) were readily achieved at 3.0T with the use of a single-channel transmit-receive head or cervical coil, a 25 mL bolus of gadoteridol, and a 3D pulse sequence with a 66% sampling efficiency. This spatial resolution allowed visualization of intracranial aneurysms, carotid dissections, and atherosclerotic disease including ulcerations. Potential drawbacks of 3.0T MRA are increased SAR and T(*)(2) dephasing compared to 1.5T. Image comparison suggests signal loss due to T(*)(2) dephasing will not be substantially more problematic than at 1.5T. The dependence of RF power deposition on TR for CEMRA is calculated and discussed. Copyright 2001 Wiley-Liss, Inc.

  19. High Spatial and Temporal Resolution Dynamic Contrast-Enhanced Magnetic Resonance Angiography (CE-MRA) using Compressed Sensing with Magnitude Image Subtraction

    PubMed Central

    Rapacchi, Stanislas; Han, Fei; Natsuaki, Yutaka; Kroeker, Randall; Plotnik, Adam; Lehman, Evan; Sayre, James; Laub, Gerhard; Finn, J Paul; Hu, Peng

    2014-01-01

    Purpose We propose a compressed-sensing (CS) technique based on magnitude image subtraction for high spatial and temporal resolution dynamic contrast-enhanced MR angiography (CE-MRA). Methods Our technique integrates the magnitude difference image into the CS reconstruction to promote subtraction sparsity. Fully sampled Cartesian 3D CE-MRA datasets from 6 volunteers were retrospectively under-sampled and three reconstruction strategies were evaluated: k-space subtraction CS, independent CS, and magnitude subtraction CS. The techniques were compared in image quality (vessel delineation, image artifacts, and noise) and image reconstruction error. Our CS technique was further tested on 7 volunteers using a prospectively under-sampled CE-MRA sequence. Results Compared with k-space subtraction and independent CS, our magnitude subtraction CS provides significantly better vessel delineation and less noise at 4X acceleration, and significantly less reconstruction error at 4X and 8X (p<0.05 for all). On a 1–4 point image quality scale in vessel delineation, our technique scored 3.8±0.4 at 4X, 2.8±0.4 at 8X and 2.3±0.6 at 12X acceleration. Using our CS sequence at 12X acceleration, we were able to acquire dynamic CE-MRA with higher spatial and temporal resolution than current clinical TWIST protocol while maintaining comparable image quality (2.8±0.5 vs. 3.0±0.4, p=NS). Conclusion Our technique is promising for dynamic CE-MRA. PMID:23801456

  20. 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. Copyright © 2016 Elsevier B.V. and Société Française de

  1. The Escherichia coli mraY gene encoding UDP-N-acetylmuramoyl-pentapeptide: undecaprenyl-phosphate phospho-N-acetylmuramoyl-pentapeptide transferase.

    PubMed Central

    Ikeda, M; Wachi, M; Jung, H K; Ishino, F; Matsuhashi, M

    1991-01-01

    Amplification of the mraY gene, previously called open reading frame Y (ORF-Y, 1,080 bp), at 2 min in the chromosome map of Escherichia coli enhanced the activity of UDP-N-acetylmuramoyl-pentapeptide: undecaprenyl-phosphate phospho-N-acetylmuramoyl-pentapeptide transferase (EC 2.7.8.13). This enzyme catalyzes the formation of undecaprenyl-pyrophosphoryl-N-acetylmuramoyl-pentapeptide from UDP-N-acetylmuramoyl-pentapeptide and undecaprenyl-phosphate, the first step in the lipid cycle reactions in biosynthesis of bacterial cell wall peptidoglycans. The enhanced enzyme activity was sensitive to tunicamycin, and the amino tunicamycin-sensitive N-acetylglucosamine-1-phosphate transferase of Saccharomyces cerevisiae. Very probably mraY is the structural gene for the above enzyme. Images PMID:1846850

  2. The Escherichia coli mraY gene encoding UDP-N-acetylmuramoyl-pentapeptide: undecaprenyl-phosphate phospho-N-acetylmuramoyl-pentapeptide transferase.

    PubMed

    Ikeda, M; Wachi, M; Jung, H K; Ishino, F; Matsuhashi, M

    1991-02-01

    Amplification of the mraY gene, previously called open reading frame Y (ORF-Y, 1,080 bp), at 2 min in the chromosome map of Escherichia coli enhanced the activity of UDP-N-acetylmuramoyl-pentapeptide: undecaprenyl-phosphate phospho-N-acetylmuramoyl-pentapeptide transferase (EC 2.7.8.13). This enzyme catalyzes the formation of undecaprenyl-pyrophosphoryl-N-acetylmuramoyl-pentapeptide from UDP-N-acetylmuramoyl-pentapeptide and undecaprenyl-phosphate, the first step in the lipid cycle reactions in biosynthesis of bacterial cell wall peptidoglycans. The enhanced enzyme activity was sensitive to tunicamycin, and the amino tunicamycin-sensitive N-acetylglucosamine-1-phosphate transferase of Saccharomyces cerevisiae. Very probably mraY is the structural gene for the above enzyme.

  3. Toward analogues of MraY natural inhibitors: synthesis of 5'-triazole-substituted-aminoribosyl uridines through a Cu-catalyzed azide-alkyne cycloaddition.

    PubMed

    Fer, Mickaël J; Olatunji, Samir; Bouhss, Ahmed; Calvet-Vitale, Sandrine; Gravier-Pelletier, Christine

    2013-10-18

    A straightforward strategy for the synthesis of triazole-containing MraY inhibitors has been developed. It involves the sequential introduction of a terminal alkyne at the 5' position of an uridine derivative and O-glycosylation with a protected aminoribose leading to an elaborated alkyne scaffold. An efficient Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) allowed the introduction of chemical diversity toward a small library of inhibitors.

  4. A systematic review and meta-analysis of diagnostic test of MRA versus MRI for detection superior labrum anterior to posterior lesions type II-VII.

    PubMed

    Arirachakaran, Alisara; Boonard, Manusak; Chaijenkij, Kornkit; Pituckanotai, Kwanchai; Prommahachai, Akom; Kongtharvonskul, Jatupon

    2017-02-01

    To determine the diagnostic performance of magnetic resonance arthrography (MRA) and magnetic resonance imaging (MRI) in superior labrum anterior to posterior lesions (type II-VII) of the shoulder. PubMed and Scopus search engines, an electronic search of articles was performed from inception to February 19, 2016. Diagnostic performance of index tests was compared by the summary area under receiver operator characteristic curve (AUROC). In all, 117 of 493 studies were eligible and 32 studies (2,013 shoulders) and 11 studies (1,498 shoulders) were evaluated with MRA and MRI. The summary sensitivity, specificity, likelihood ratio (positive and negative) and AUROC were 0.87 (95 % confidence interval, CI: 0.82, 0.91), 0.92 (95 %CI: 0.85, 0.95), 10.28 (95 %CI: 5.84, 18.08), 0.14 (95 %CI: 0.10, 0.20) and 0.94 (95 %CI: 0.92, 0.96) respectively for MRA, and 0.76 (95 %CI: 0.61, 0.86), 0.87 (95 %CI: 0.71, 0.95), 5.89 (95 %CI: 2.5, 13.86), 0.28 (95 %CI: 0.17, 0.47) and 0.94 (95 %CI: 0.92, 0.96) respectively for MRI. The diagnostic performance of MRA was superior to MRI by both direct and indirect comparisons for the detection of SLAP lesions.

  5. Time-resolved magnetic resonance angiography (MRA) at 3.0 Tesla for evaluation of hemodynamic characteristics of vascular malformations: description of distinct subgroups.

    PubMed

    Hammer, Simone; Uller, Wibke; Manger, Florentine; Fellner, Claudia; Zeman, Florian; Wohlgemuth, Walter A

    2017-01-01

    Quantitative evaluation of hemodynamic characteristics of arteriovenous and venous malformations using time-resolved magnetic resonance angiography (MRA) at 3.0 Tesla. Time-resolved MRA with interleaved stochastic trajectories (TWIST) at 3.0 Tesla was studied in 83 consecutive patients with venous malformations (VM) and arteriovenous malformations (AVM). Enhancement characteristics were calculated as percentage increase of signal intensity above baseline over time. Maximum percentage signal intensity increase (signalmax), time intervals between onset of arterial enhancement and lesion enhancement (tonset), and time intervals between beginning of lesion enhancement and maximum percentage of lesion enhancement (tmax) were analyzed. All AVMs showed a high-flow hemodynamic pattern. Two significantly different (p < 0.001) types of venous malformations emerged: VMs with arteriovenous fistulas (AVF) (median signalmax 737 %, IQR [interquartile range] = 511 - 1182 %; median tonset 5 s, IQR = 5 - 10 s; median tmax 35 s, IQR = 26 - 40 s) and without AVFs (median signalmax 284 %, IQR = 177-432 %; median tonset 23 s, IQR = 15 - 30 s; median tmax 60 s, IQR = 55 - 75 s). Quantitative evaluation of time-resolved MRA at 3.0 Tesla provides hemodynamic characterization of vascular malformations. VMs can be subclassified into two hemodynamic subgroups due to presence or absence of AVFs. • Time-resolved MRA at 3.0 Tesla provides quantitative hemodynamic characterization of vascular malformations. • Malformations significantly differ in time courses of enhancement and signal intensity increase. • AVMs show a distinctive high-flow hemodynamic pattern. • Two significantly different types of VMs emerged: VMs with and without AVFs.

  6. A Proposal of a Mass Appraisal System in Greece with CAMA System: Evaluating GWR and MRA techniques in Thessaloniki Municipality

    NASA Astrophysics Data System (ADS)

    Dimopoulos, Thomas; Moulas, Alexandros

    2016-01-01

    Property tax in Greece is levied since 1985 not on Market Values but on the "objective value" of the properties as it is defined by the Ministry of Economics. It forms a non-flexible system, with market-irrelevant and unrealistic values, inducing land-policy practices and potential political cost to each periodical update. Furthermore, instead of adjusting taxation levels to the current economic reality, the real estate market is experiencing further burdening through approximately 40 different property taxes and levies, leading to further shrinking and depreciation. The authors believe that a fairer taxation system could significantly assist the property sector in Greece. Thus, through this paper and by studying and analyzing best practices from other countries, they propose models that can be applied with the use of existing data in Greece. This work aims to identify the critical parameters that affecting property values in Thessaloniki to create a Market Value forecasting tool for a fairer taxation system, to highlight the importance of a GIS system for this purpose and to compare the results of MRA with the use of SPSS with those of GWR in ArcGIS environment. For the purposes of this study, the Municipality of Thessaloniki was chosen due to its very well organized portal with significant and well organized geographical data and because authors manage to access some data from the Central Bank of Greece, regarding property valuations.

  7. 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

  8. A Proposal of a Mass Appraisal System in Greece with CAMA System: Evaluating GWR and MRA techniques in Thessaloniki Municipality

    NASA Astrophysics Data System (ADS)

    Dimopoulos, Thomas; Moulas, Alexandros

    2017-01-01

    Property tax in Greece is levied since 1985 not on Market Values but on the "objective value" of the properties as it is defined by the Ministry of Economics. It forms a non-flexible system, with market-irrelevant and unrealistic values, inducing land-policy practices and potential political cost to each periodical update. Furthermore, instead of adjusting taxation levels to the current economic reality, the real estate market is experiencing further burdening through approximately 40 different property taxes and levies, leading to further shrinking and depreciation. The authors believe that a fairer taxation system could significantly assist the property sector in Greece. Thus, through this paper and by studying and analyzing best practices from other countries, they propose models that can be applied with the use of existing data in Greece. This work aims to identify the critical parameters that affecting property values in Thessaloniki to create a Market Value forecasting tool for a fairer taxation system, to highlight the importance of a GIS system for this purpose and to compare the results of MRA with the use of SPSS with those of GWR in ArcGIS environment. For the purposes of this study, the Municipality of Thessaloniki was chosen due to its very well organized portal with significant and well organized geographical data and because authors manage to access some data from the Central Bank of Greece, regarding property valuations.

  9. Cross-sectional imaging combined with 3D-MR angiography (3D-MRA): diagnostic tool for preoperative vascular assessment of head and neck tumors.

    PubMed

    Sadick, Maliha; Sadick, Haneen; Hörmann, Karl; Düber, Christoph; Diehl, Steffen J

    2005-10-01

    Head and neck cancer accounts for 5% of all malignancies worldwide. The presence of lymph node metastases and vascular infiltration influence patient outcome. This prospective study describes the preoperative morphologic assessment of the vascular status of patients with head and neck tumors by means of high spatial resolution and extended coverage of the arterial and venous system reaching from the supra-aortic region to the skull base. Cross-sectional imaging combined with contrast-enhanced 3D-maximum intensity projection MR angiography (3D-MRA) was applied using a dedicated head and neck coil with a 4-channel panorama array system interface to assess vascular involvement in patients with suspected head and neck cancer. 32 patients underwent preoperative assessment by magnetic resonance imaging (MRI). The results were then correlated with surgical and histological findings. 3 of the 32 patients (9%) demonstrated involvement of the arterial system. In 2 of these 3 cases, MRA correctly predicted the arterial status, while in 1 case it gave a false negative result. 11 of the 32 patients (34%) presented with involvement of the venous system. 10 cases showed complete concordance between the findings of the MR venography and the intraoperative status, while in 1 case a false negative result was produced. In patients with suspected head and neck tumors, 3D-MRA in combination with cross sectional imaging is a valuable diagnostic tool for the detection of vascular involvement.

  10. Computerized assessment of vessel morphological changes during treatment of glioblastoma multiforme: Report of a case imaged serially by MRA over four years

    PubMed Central

    Bullitt, Elizabeth; Ewend, Matthew; Vredenburgh, James; Friedman, Allan; Lin, Weili; Wilber, Kathy; Zeng, Donglin; Aylward, Stephen R.; Reardon, David

    2009-01-01

    A patient with glioblastoma mutliforme underwent serial computerized analysis of tumor-associated vasculature defined from magnetic resonance angiographic (MRA) scans obtained over almost a four year period. The clinical course included tumor resection with subsequent radiation therapy, a long symptom-free interval, emergence of a new malignant focus, resection of that focus, a stroke, and treatment with chemotherapy and anti-angiogenic therapy. Image analysis methods included segmentation of vessels from each MRA and statistical comparison of vessel morphology over 4 regions of interest (the initial tumor site, the second tumor site, a distant control region, and the entire brain) to the same 4 regions of interest in 50 healthy volunteers (26 females and 24 males; mean age 39 years). Results suggested that following completion of focal radiation therapy (RT) vessel shape abnormalities, if elevated at the time of RT completion, may progressively normalize for months in focal regions, that progressively severe vessel shape abnormalities can precede the emergence of a gadolinium enhancing lesion by months, that lesion resection can produce a dramatic but highly transient drop in abnormal vessel tortuosity both focally and globally, and that treatment with anti-angiogenic agents does not necessarily normalize vessel shape. Quantitative measurements of vessel morphology as defined from MRA may provide useful insights into tumor development and response to therapy. PMID:19103295

  11. 3D radial sampling and 3D affine transform-based respiratory motion correction technique for free-breathing whole-heart coronary MRA with 100% imaging efficiency.

    PubMed

    Bhat, Himanshu; Ge, Lan; Nielles-Vallespin, Sonia; Zuehlsdorff, Sven; Li, Debiao

    2011-05-01

    The navigator gating and slice tracking approach currently used for respiratory motion compensation during free-breathing coronary magnetic resonance angiography (MRA) has low imaging efficiency (typically 30-50%), resulting in long imaging times. In this work, a novel respiratory motion correction technique with 100% scan efficiency was developed for free-breathing whole-heart coronary MRA. The navigator signal was used as a reference respiratory signal to segment the data into six bins. 3D projection reconstruction k-space sampling was used for data acquisition and enabled reconstruction of low resolution images within each respiratory bin. The motion between bins was estimated by image registration with a 3D affine transform. The data from the different respiratory bins was retrospectively combined after motion correction to produce the final image. The proposed method was compared with a traditional navigator gating approach in nine healthy subjects. The proposed technique acquired whole-heart coronary MRA with 1.0 mm(3) isotropic spatial resolution in a scan time of 6.8 ± 0.9 min, compared with 16.2 ± 2.8 min for the navigator gating approach. The image quality scores, and length, diameter and sharpness of the right coronary artery (RCA), left anterior descending coronary artery (LAD), and left circumflex coronary artery (LCX) were similar for both approaches (P > 0.05 for all), but the proposed technique reduced scan time by a factor of 2.5. Copyright © 2011 Wiley-Liss, Inc.

  12. 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

  13. Interaction of the transmembrane domain of lysis protein E from bacteriophage phiX174 with bacterial translocase MraY and peptidyl-prolyl isomerase SlyD.

    PubMed

    Mendel, Sharon; Holbourn, Joanne M; Schouten, James A; Bugg, Timothy D H

    2006-10-01

    The molecular target for the bacteriolytic E protein from bacteriophage X174, responsible for host cell lysis, is known to be the enzyme phospho-MurNAc-pentapeptide translocase (MraY), an integral membrane protein involved in bacterial cell wall peptidoglycan biosynthesis, with an essential role being played by peptidyl-prolyl isomerase SlyD. A synthetic 37 aa peptide E(pep), containing the N-terminal transmembrane alpha-helix of E, was found to be bacteriolytic against Bacillus licheniformis, and inhibited membrane-bound MraY. The solution conformation of E(pep) was found by circular dichroism (CD) spectroscopy to be 100 % alpha-helical. No change in the CD spectrum was observed upon addition of purified Escherichia coli SlyD, implying that SlyD does not catalyse prolyl isomerization upon E. However, E(pep) was found to be a potent inhibitor of SlyD-catalysed peptidyl-prolyl isomerization (IC(50) 0.15 microM), implying a strong interaction between E and SlyD. E(pep) was found to inhibit E. coli MraY activity when assayed in membranes (IC(50) 0.8 microM); however, no inhibition of solubilized MraY was observed, unlike nucleoside natural product inhibitor tunicamycin. These results imply that the interaction of E with MraY is not at the MraY active site, and suggest that a protein-protein interaction is formed between E and MraY at a site within the transmembrane region.

  14. Active site mapping of MraY, a member of the polyprenyl-phosphate N-acetylhexosamine 1-phosphate transferase superfamily, catalyzing the first membrane step of peptidoglycan biosynthesis.

    PubMed

    Al-Dabbagh, Bayan; Henry, Xavier; El Ghachi, Meriem; Auger, Geneviève; Blanot, Didier; Parquet, Claudine; Mengin-Lecreulx, Dominique; Bouhss, Ahmed

    2008-08-26

    The MraY transferase is an integral membrane protein that catalyzes an essential step of peptidoglycan biosynthesis, namely the transfer of the phospho-N-acetylmuramoyl-pentapeptide motif onto the undecaprenyl phosphate carrier lipid. It belongs to a large superfamily of eukaryotic and prokaryotic prenyl sugar transferases. No 3D structure has been reported for any member of this superfamily, and to date MraY is the only protein that has been successfully purified to homogeneity. Nineteen polar residues located in the five cytoplasmic segments of MraY appeared as invariants in the sequences of MraY orthologues. A certain number of these invariant residues were found to be conserved in the whole superfamily. To assess the importance of these residues in the catalytic process, site-directed mutagenesis was performed using the Bacillus subtilis MraY as a model. Fourteen residues were shown to be essential for MraY activity by an in vivo functional complementation assay using a constructed conditional mraY mutant strain. The corresponding mutant proteins were purified and biochemically characterized. None of these mutations did significantly affect the binding of the nucleotidic and lipidic substrates, but the k cat was dramatically reduced in almost all cases. The important residues for activity therefore appeared to be distributed in all the cytoplasmic segments, indicating that these five regions contribute to the structure of the catalytic site. Our data show that the D98 residue that is invariant in the whole superfamily should be involved in the deprotonation of the lipid substrate during the catalytic process.

  15. The diagnostic performance of non-contrast 3-Tesla magnetic resonance imaging (3-T MRI) versus 1.5-Tesla magnetic resonance arthrography (1.5-T MRA) in femoro-acetabular impingement.

    PubMed

    Crespo-Rodríguez, Ana M; De Lucas-Villarrubia, Jose C; Pastrana-Ledesma, Miguel; Hualde-Juvera, Ana; Méndez-Alonso, Santiago; Padron, Mario

    2017-03-01

    The aim of this study was to evaluate the diagnostic accuracy of 3-T non-contrast MRI versus 1.5-T MRA for assessing labrum and articular cartilage lesions in patients with clinical suspicion of femoro-acetabular impingement (FAI). Fifty patients (thirty men and twenty women, mean age 42.5 years) underwent 1.5-T MRA, 3-T MRI and arthroscopy on the same hip. An optimized high-resolution proton density spin echo pulse sequence was included in the 3-T non-contrast MRI protocol. The 3-T non-contrast MRI identified forty-two of the forty-three arthroscopically proven tears at the labral-chondral transitional zone (sensitivity, 97.7%; specificity, 100%; positive predictive value (PPV), 100%; negative predictive value (NPV), 87.5%; accuracy 98%). With 1.5-T MRA, forty-four tears were diagnosed. However, there was one false positive (sensitivity, 100%; specificity, 85.7%; PPV, 97.7%; NPV, 100%; accuracy 98%). Agreement between arthroscopy and MRI, whether 3-T non-contrast MRI or 1.5-T MRA, as to the degree of chondral lesion in the acetabulum was reached in half of the patients and in the femur in 76% of patients. Non-invasive assessment of the hip is possible with 3-T MR magnet. 3-T non-contrast MRI could replace MRA as the workhorse technique for assessing hip internal damage. MRA would then be reserved for young adults with a strong clinical suspicion of FAI but normal findings on 3-T non-contrast MRI. When compared with 1.5-T MRA, optimized sequences with 3-T non-contrast MRI help in detecting normal variants and in diagnosing articular cartilage lesions. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

  16. Characterization of co-translationally formed nanodisc complexes with small multidrug transporters, proteorhodopsin and with the E. coli MraY translocase.

    PubMed

    Roos, Christian; Zocher, Michael; Müller, Daniel; Münch, Daniela; Schneider, Tanja; Sahl, Hans-Georg; Scholz, Frank; Wachtveitl, Josef; Ma, Yi; Proverbio, Davide; Henrich, Erik; Dötsch, Volker; Bernhard, Frank

    2012-12-01

    Nanodiscs (NDs) enable the analysis of membrane proteins (MP) in natural lipid bilayer environments. In combination with cell-free (CF) expression, they could be used for the co-translational insertion of MPs into defined membranes. This new approach allows the characterization of MPs without detergent contact and it could help to identify effects of particular lipids on catalytic activities. Association of MPs with different ND types, quality of the resulting MP/ND complexes as well as optimization parameters are still poorly analyzed. This study describes procedures to systematically improve CF expression protocols for the production of high quality MP/ND complexes. In order to reveal target dependent variations, the co-translational ND complex formation with the bacterial proton pump proteorhodopsin (PR), with the small multidrug resistance transporters SugE and EmrE, as well as with the Escherichia coli MraY translocase was studied. Parameters which modulate the efficiency of MP/ND complex formation have been identified and in particular effects of different lipid compositions of the ND membranes have been analyzed. Recorded force distance pattern as well as characteristic photocycle dynamics indicated the integration of functionally folded PR into NDs. Efficient complex formation of the E. coli MraY translocase was dependent on the ND size and on the lipid composition of the ND membranes. Active MraY protein could only be obtained with ND containing anionic lipids, thus providing new details for the in vitro analysis of this pharmaceutically important protein. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. [Guiding values of facial nerve 3D-TOF-MRA and 3D-FIESTA scan for primary hemifacial spasm operation].

    PubMed

    Wu, Guo-qing; Wang, Lei; Yin, Wei-ning; Liu, Xian-ming; Li, Chuan-feng; Wu, Guo-hong

    2013-12-03

    To explore the operative guiding values of facial nerve three-dimensional time-of-flight magnetic resonance angiography (3D-TOF-MRA) and three-dimensional fast imaging employing steady state acquisition three-dimensional fast imaging employing steady state acquisition (3D-FIESTA) scan. A total of 125 cases of primary hemifacial spasm was treated at our hospital from 2004 to 2012. Among them, 80 cases received preoperative facial nerve MRA scan. The imaging and intraoperative findings were compared to determine the responsible blood vessels. Responsible blood vessels were found in all 80 cases. Sixty patients (75%) had the involvement of single vessel of anterior inferior cerebellar artery (AICA, n = 57), posterior inferior cerebellar artery (PICA, n = 1), superior cerebellar artery (SCA, n = 1) and vertebral artery (VA, n = 1). Two or more vessels were implicated in 9 patients (11.25%). The culprits were AICA+ internal auditory artery (n = 8) and PICA+ internal auditory artery (n = 1). The source of responsible vessels of 11 cases could not be determined before surgery. Through intraoperative anatomy, 59 patients had single vessel lesions, including AICA (n = 53), PICA (n = 4), SCA (n = 1) and VA (n = 1). Among 14 cases of multiple vessels, there were AICA + internal auditory artery (n = 7), internal auditory artery + PICA (n = 2), AICA + brain stem perforating artery (n = 3) and AICA + vein (n = 2). Seven cases were uncertain. No significant statistical difference existed between two groups. Facial nerve 3D-TOF-MRA and 3D-FIESTA scan can identify the status of responsible blood vessels to guide operations.

  18. 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

  19. MR Angiography (MRA)

    MedlinePlus

    ... can be performed with one of three imaging technologies and, in some cases contrast material is administered. ... the extent and severity of the effects of coronary artery disease and plan for a surgical operation, such as ...

  20. MR Angiography (MRA)

    MedlinePlus

    ... in key areas of the body, including the: brain neck heart chest abdomen (such as the kidneys and ... plaque) disease in the carotid artery of the neck, which may limit blood flow to the brain and cause a stroke. identify a small aneurysm ...

  1. Novel method of vulnerability assessment of simple landfills area using the multimedia, multipathway and multireceptor risk assessment (3MRA) model, China.

    PubMed

    Yuan, Ying; He, Xiao-Song; Xi, Bei-Dou; Wei, Zi-Min; Tan, Wen-Bing; Gao, Ru-Tai

    2016-11-01

    Vulnerability assessment of simple landfills was conducted using the multimedia, multipathway and multireceptor risk assessment (3MRA) model for the first time in China. The minimum safe threshold of six contaminants (benzene, arsenic (As), cadmium (Cd), hexavalent chromium [Cr(VI)], divalent mercury [Hg(II)] and divalent nickel [Ni(II)]) in landfill and waste pile models were calculated by the 3MRA model. Furthermore, the vulnerability indexes of the six contaminants were predicted based on the model calculation. The results showed that the order of health risk vulnerability index was As > Hg(II) > Cr(VI) > benzene > Cd > Ni(II) in the landfill model, whereas the ecology risk vulnerability index was in the order of As > Hg(II) > Cr(VI) > Cd > benzene > Ni(II). In the waste pile model, the order of health risk vulnerability index was benzene > Hg(II) > Cr(VI) > As > Cd and Ni(II), whereas the ecology risk vulnerability index was in the order of Hg(II) > Cd > Cr(VI) > As > benzene > Ni(II). These results indicated that As, Hg(II) and Cr(VI) were the high risk contaminants for the case of a simple landfill in China; the concentration of these in soil and groundwater around the simple landfill should be strictly monitored, and proper mediation is also recommended for simple landfills with a high concentration of contaminants. © The Author(s) 2016.

  2. Unique combination of hyperintense vessel sign on initial FLAIR and delayed vasoconstriction on MRA in reversible cerebral vasoconstriction syndrome: a case report.

    PubMed

    Kameda, Tomoaki; Namekawa, Michito; Shimazaki, Haruo; Minakata, Daisuke; Matsuura, Tohru; Nakano, Imaharu

    2014-11-01

    Reversible cerebral vasoconstriction syndrome is characterized by thunderclap headache and reversible cerebral vasoconstriction on angiographic findings. It can be difficult to diagnose when initial angiography is normal. A 30-year-old woman was admitted because of sudden-onset thunderclap headache and seizure on postpartum day 7. Brain MRI on fluid-attenuated inversion recovery (FLAIR) showed hyperintense vessel sign (HVS), which usually means slow flow due to severe proximal arterial stenosis. However, magnetic resonance angiography (MRA) indicated that proximal arteries was normal. After nicardipine treatment, her symptoms improved dramatically. Follow-up FLAIR on day 7 showed complete resolution of HVS, while a series of MRAs revealed reversible multifocal segmental vasoconstriction. HVS on initial FLAIR is useful for an early diagnosis of reversible cerebral vasoconstriction syndrome. As the delayed vasoconstriction on MRA can be observed, reversible cerebral vasoconstriction syndrome may progress from distal small to proximal larger arteries. © International Headache Society 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  3. Synthesis of analogues of the O-beta-D-ribofuranosyl nucleoside moiety of liposidomycins. Part 1: contribution of the amino group and the uracil moiety upon the inhibition of MraY.

    PubMed

    Dini, C; Drochon, N; Feteanu, S; Guillot, J C; Peixoto, C; Aszodi, J

    2001-02-26

    The O-beta-D-ribofuranosyl nucleoside I is the minimal structural entity of liposidomycins maintaining enzyme inhibitory activity. Modifications performed on both the primary amine and the uracil moieties clearly demonstrate their major contribution to the inhibition of the bacterial translocase (MraY).

  4. [Brain 3 D-CT angiography was a useful tool for diagnosis of internal carotid-posterior communicating artery aneurysm: a case of false negative 3 D-MRA].

    PubMed

    Ikeda, K; Iwasaki, Y; Murakami, S; Ichikawa, Y

    1999-09-01

    A 75-year-old woman with hypertension suddenly developed ptosis in the left eyelid. Neurological examination revealed left oculomotor nerve palsy. Brain T 2-weighted imaging showed abnormal flow void sign in the proximal portion of left middle cerebral artery. Other MRIs, including gadolinium enhancement, were normal. However, brain 3 D-MRA, using time-of-flight sequence, did not disclose any intracranial aneurysms. 3 D-CT angiography revealed left internal carotid-posterior communicating artery (IC-PC) aneurysm. Maximum intensity projection display of CT angiography demonstrated the neck and head portions of IC-PC aneurysm (size = 8 mm). Furthermore, 3 D-CT angiography was beneficial for anatomical evaluation of the aneurysm and the surrounding bony structures. The false negative 3 D-MRA of our patient was thought to result from flow-related artifacts, slow blood flow in the aneurysm, the surrounding noise and the localization of aneurysm. False negative findings of cerebral aneurysms occasionally occur on 3 D-MRA or 3 D-CT angiography, in comparison with digital subtraction angiography. Thus, we should pay more attention to assessment of 3 D-MRA and 3 D-CT angiography in patients who have high risks of cerebral aneurysms.

  5. Highly undersampled supraaortic MRA at 3.0 T: initial results with parallel imaging in two directions using a 16-channel neurovascular coil and parallel imaging factors up to 16.

    PubMed

    Kukuk, Guido M; Hadizadeh, Dariusch R; Gieseke, Jürgen; von Falkenhausen, Marcus; Böhm, Ingrid; Semrau, Renate; Urbach, Horst; Koscielny, Arne; Verrel, Frauke; Wilhelm, Kai; Schild, Hans H; Willinek, Winfried A

    2010-11-01

    To present the feasibility of highly undersampled contrast-enhanced MRA (CE-MRA) of the supraaortic arteries with a 16-channel neurovascular coil at 3.0 T using parallel imaging in two directions with parallel imaging factors (PIF) up to 16. Institutional review board approval and informed consent were obtained. In a prospective study, MRA protocols including PIF of 1, 2, 4, 9 and 16 yielding a spatial resolution from 0.81×0.81×1.0 mm(3) to 0.46×.46×0.98 mm(3) were acquired. In 32 examinations, image quality and vascular segments were rated independently by two radiologists. SNR estimations were performed for all MRA protocols. The use of high PIF allowed to shorten acquisition time from 2:09 min down to 1:13 min and to increase the anatomic coverage while maintaining or even increasing spatial resolution down to 0.46×0.46×0.98 mm(3). The larger anatomic coverage that was achieved with the use of high PIF allowed for visualization of vascular structures that were not covered by the standard protocols. Despite the resulting lower SNR using high PIF, image quality was constantly rated to be adequate for diagnosis or better in all cases. The use of high PIF yielded diagnostic image quality and allowed to increase the anatomic coverage while maintaining or even improving spatial resolution and shortening the acquisition time. Copyright © 2010 Elsevier Inc. All rights reserved.

  6. 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

  7. 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

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

    PubMed

    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.

  9. Preliminary experience with MRA in evaluating the degree of carotid stenosis and plaque morphology using high-resolution sequences after gadofosveset trisodium (Vasovist) administration: comparison with CTA and DSA.

    PubMed

    Anzidei, M; Napoli, A; Geiger, D; Cavallo Marincola, B; Zini, C; Zaccagna, F; Di Paolo, P; Catalano, C; Passariello, R

    2010-06-01

    The authors performed a preliminary study with blood-pool contrast-enhanced magnetic resonance angiography (MRA) in evaluating the degree of carotid artery stenosis and plaque morphology, comparing the diagnostic performance of first-pass (FP) and steady-state (SS) acquisitions with 64-slice computed tomography angiography (CTA) and using digital subtraction angiography (DSA) as the reference standard. Twenty patients with >or=50% carotid artery stenosis at Doppler sonography underwent blood-pool contrast-enhanced MRA, CTA and DSA. Two independent radiologists evaluated MRA and CTA examinations to assess the degree of stenosis and characterise plaque morphology. Accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated for FP, SS and CTA. The McNemar and Wilcoxon tests were used to determine significant differences (p<0.05) between the diagnostic performance of the three modalities. Forty carotid bifurcations were studied. For stenosis grading, accuracy, sensitivity, specificity, PPV and NPV were 90%, 89%, 90%, 89% and 90%, respectively, at FP; 95%, 95%, 95%, 95% and 95%, respectively, at SS; and 97.5%, 95%, 100%, 100% and 95%, respectively, at CTA. SS and CTA were superior to FP for evaluating the degree of stenosis (p<0.05). For evaluating plaque morphology, accuracy, sensitivity, specificity, PPV and NPV were 87.5%, 89%, 86%, 85% and 90%, respectively, at FP; 97.5%, 100%, 95%, 95% and 100%, respectively, at SS; and 100%, 100%, 100%, 100% and 100%, respectively, at CTA. There were no significant differences between FP, SS and CTA for plaque assessment (p>0.05). Blood-pool contrast-enhanced MRA with SS sequences allow improved diagnostic evaluation of the degree of carotid stenosis and plaque morphology compared with FP and is substantially equal to CTA and DSA.

  10. Non-Contrast Enhanced MR Angiography (NCE-MRA) of the Calf: A Direct Comparison between Flow-Sensitive Dephasing (FSD) Prepared Steady-State Free Precession (SSFP) and Quiescent-Interval Single-Shot (QISS) in Patients with Diabetes.

    PubMed

    Zhang, Na; Zou, Liqiu; Huang, Yi; Liu, Dexiang; Tang, Yukuan; Fan, Zhaoyang; Chen, Hanwei; Liu, Xin

    2015-01-01

    To compare the image quality and diagnostic performance of two non-contrast enhanced MR angiography (NCE-MRA) techniques using flow-sensitive dephasing (FSD) prepared steady-state free precession (SSFP) and quiescent-interval single-shot (QISS) for the calf arteries in patients with diabetes. Twenty six patients underwent the two NCE-MRA techniques followed by contrast-enhanced MRA (CE-MRA) of lower extremity on a 1.5T MR system. Image quality scores, arterial stenosis scores, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), vessel sharpness, and diagnostic accuracy for detecting more than 50% arterial stenosis were evaluated and statistically compared using CE-MRA as the reference standard. All examinations were performed successfully. Of the total 153 calf arterial segments obtained in the 26 patients, FSD and QISS showed no significant difference in the number of diagnostic arterial segments (151 [98%] vs. 147 [96%], respectively, P>0.05). The image quality of FSD was higher than that of QISS in the peroneal artery and posterior tibial artery (P<0.05), but no significant difference in the anterior tibial artery (P>0.05). SNR and CNR of FSD were higher than those of QISS (P<0.01), while FSD showed comparable vessel sharpness compared with QISS (P>0.05). The time efficiency of SNR and CNR between FSD and QISS showed no significant difference when taking into account the times for FSD-related scout scans. There was no difference in sensitivity (95% vs. 93%, P>0.05) and negative predictive value (98% vs. 97%, P>0.05) between FSD and QISS for detecting stenosis greater than 50%. However, FSD showed higher specificities (99% vs. 92%, P<0.05) and diagnostic accuracy (98% vs. 92%, P<0.05) compared to QISS. Both FSD and QISS had similar high sensitivity and negative predictive value for detecting calf arteries with over 50% stenosis, but FSD showed slightly higher diagnostic specificity and better depiction of arterial lesions due to its isotropic

  11. The applied research of MRI with ASSET-EPI-FLAIR combined with 3D TOF MRA sequences in the assessment of patients with acute cerebral infarction.

    PubMed

    Lin, Zhichao; Guo, Zexiong; Qiu, Lin; Yang, Wanyoug; Lin, Mingxia

    2016-12-01

    Background To extend the time window for thrombolysis, reducing the time for diagnosis and detection of acute cerebral infarction seems to be warranted. Purpose To evaluate the feasibility of implementing an array spatial sensitivity technique (ASSET)-echo-planar imaging (EPI)-fluid attenuated inversion recovery (FLAIR) (AE-FLAIR) sequence into an acute cerebral infarction magnetic resonance (MR) evaluation protocol, and to assess the diagnostic value of AE-FLAIR combined with three-dimensional time-of-flight MR angiography (3D TOF MRA). Material and Methods A total of 100 patients (68 men, 32 women; age range, 44-82 years) with acute cerebral infarction, including 50 consecutive uncooperative and 50 cooperative patients, were evaluated with T1-weighted (T1W) imaging, T2-weighted (T2W) imaging, FLAIR, diffusion-weighted imaging (DWI), 3D TOF, EPI-FLAIR, and AE-FLAIR. Conventional FLAIR, EPI-FLAIR, and AE-FLAIR were assessed by two observers independently for image quality. The optimized group (AE-FLAIR and 3D TOF) and the control group (T1W imaging, T2W imaging, conventional FLAIR, DWI, and 3D TOF) were compared for evaluation time and diagnostic accuracy. Results One hundred and twenty-five lesions were detected and images having adequate diagnostic image quality were in 73% of conventional FLAIR, 62% of EPI-FLAIR, and 89% of AE-FLAIR. The detection time was 12 ± 1 min with 76% accuracy and 4 ± 0.5 min with 100% accuracy in the control and the optimized groups, respectively. Inter-observer agreements of κ = 0.78 and κ = 0.81 were for the optimized group and control group, respectively. Conclusion With reduced acquisition time and better image quality, AE-FLAIR combined with 3D TOF may be used as a rapid diagnosis tool in patients with acute cerebral infarction, especially in uncooperative patients.

  12. A high-throughput solid-phase extraction assay capable of measuring diverse polyprenyl phosphate: sugar-1-phosphate transferases as exemplified by the WecA, MraY, and MurG proteins.

    PubMed

    Hyland, Sheryl A; Anderson, Matt S

    2003-06-15

    The bacterial proteins WecA and MraY are members of the polyprenyl phosphate:N-acetylhexosamine-1-phosphate transferase family, each of which catalyzes the transfer of a specific hexosamine 1-P from a soluble UDP-hexosamine substrate to a bactoprenyl phosphate carrier at the membrane surface. Currently, assays designed to quantitate the activity of these enzymes rely on paper chromatography or liquid-liquid extractions or are specialized to a few members of the family. We describe a generalizable, high-throughput, one-pot assay for these activities that uses a solid-liquid bead-based separation system to selectively adsorb the highly hydrophobic products of reaction. By judicious choice of radiolabeled UDP-hexosamine precursor, the same format can be used to quantitate not only diverse members of this transferase family, but also enzymes that catalyze the further modification of these transferase products. This possibility is exemplified by the MurG protein of bacterial cell wall synthesis, which catalyzes the addition of an N-acetylglucosamine residue to the product of the MraY reaction. Thus, the use of this flexible assay tool will allow a critical biochemical and enzymologic analysis of many such membrane-bound transferases in a similar setting.

  13. The analysis of cell division and cell wall synthesis genes reveals mutationally inactivated ftsQ and mraY in a protoplast-type L-form of Escherichia coli.

    PubMed

    Siddiqui, Roman A; Hoischen, Christian; Holst, Otto; Heinze, Ivonne; Schlott, Bernhard; Gumpert, Johannes; Diekmann, Stephan; Grosse, Frank; Platzer, Matthias

    2006-05-01

    Cell division and cell wall synthesis are tightly linked cellular processes for bacterial growth. A protoplast-type L-form Escherichia coli, strain LW1655F+, indicated that bacteria can divide without assembling a cell wall. However, the molecular basis of its phenotype remained unknown. To establish a first phenotype-genotype correlation, we analyzed its dcw locus, and other genes involved in division of E. coli. The analysis revealed defective ftsQ and mraY genes, truncated by a nonsense and a frame-shift mutation, respectively. Missense mutations were determined in the ftsA and ftsW products yielding amino-acid replacements at conserved positions. FtsQ and MraY, obviously nonfunctional in the L-form, are essential for cell division and cell wall synthesis, respectively, in all bacteria with a peptidoglycan-based cell wall. LW1655F+ is able to survive their loss-of-functions. This points to compensatory mechanisms for cell division in the absence of murein sacculus formation. Hence, this L-form represents an interesting model to investigate the plasticity of cell division in E. coli, and to demonstrate how concepts fundamental for bacterial life can be bypassed.

  14. 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.

  15. Your Radiologist Explains Magnetic Resonance Angiography (MRA)

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  17. About Neurointerventions

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  18. Aerial target recognition using MRA, GVF snakes, and polygon approximation

    NASA Astrophysics Data System (ADS)

    Lu, Zhen Z.; Zhang, Taiyi; Xu, Jian

    2003-04-01

    The traditional method to extract target contour from aerial target image is changing the aerial image into a gray level image with multiple thresholds or binary image with single threshold. From the edge of target, contour can be extracted according to the changed value. The traditional method is useful only when contrast between target and background is in the proper degree. Snakes are curves defined within an image domain that can move under the influence of internal force coming from within the curve itself and external forces are defined so that the snake will conform to an object boundary or other desired features within an image. Snakes have been proved an effective method and widely used in image processing and computer vision. Snakes synthesize parametric curves within an image domain and allow them to move toward desired edges. Particular advantages of the GVF(Gradient Vector Flow) snakes over a traditional snakes are its insensitivity to initialization and its ability to move into boundary concavities. Its initializations can be inside, outside, or across the object"s boundary. The GVF snake does not need prior knowledge about whether to shrink or expand toward the boundary. This increased capture range is achieved through a diffusion process that does not blur the edges of themselves. Affected by the light from different incident angle, the brightness of aerial target surface changed greatly in a complicate mode. So the GVF snakes is not fast, accurate and effective all the time for this kind of images. A new contour extracting method, GVF Snakes Combined with wavelet multi-resolution Analysis is proposed in this paper. In this algorithm, bubble wavelet is used iteratively to do the multi resolution analysis in the order of degressive scale before GVF Snakes is used every time to extract accurate contour of target. After accurate contour is extracted, polygon approximation is used to extract characteristics to realize the recognition of aerial target. The process is in the following: Step 1: use bubble wavelet filter to cut big part of the noises, weakening false edges. Step 2: initialize active contour and control the contour"s move according to GVF to get a new contour. Step 3: decrease the scale of filter, and use the new contour as the initial contour and control the contour"s move to get new contour again. Step 4: repeat step 3 till the set scale is reached. The last new contour is the final contour. Step 5: find the center determine an axis by calculate distance between every point on the final contour to the center. Step 6: adjust the distance threshold and combine the points until the contour is changed into a polygon with fixed angle number which is best fit the target recognition demand. Step 7: use the polygon to match the target plate to recognize target. Applied the new algorithm to aerial target images of a helicopter and a F22 battleplan, the contour extraction and polygon approximation results show that targets can be matched and recognized successfully. This paper mainly focuses on contour extraction and polygon approximation in the recognition area.

  19. Noncontrast Peripheral MRA with Spiral Echo Train Imaging

    PubMed Central

    Fielden, Samuel W.; Mugler, John P.; Hagspiel, Klaus D.; Norton, Patrick T.; Kramer, Christopher M.; Meyer, Craig H.

    2015-01-01

    Purpose To develop a spin echo train sequence with spiral readout gradients with improved artery–vein contrast for noncontrast angiography. Theory Venous T2 becomes shorter as the echo spacing is increased in echo train sequences, improving contrast. Spiral acquisitions, due to their data collection efficiency, facilitate long echo spacings without increasing scan times. Methods Bloch equation simulations were performed to determine optimal sequence parameters, and the sequence was applied in five volunteers. In two volunteers, the sequence was performed with a range of echo times and echo spacings to compare with the theoretical contrast behavior. A Cartesian version of the sequence was used to compare contrast appearance with the spiral sequence. Additionally, spiral parallel imaging was optionally used to improve image resolution. Results In vivo, artery–vein contrast properties followed the general shape predicted by simulations, and good results were obtained in all stations. Compared with a Cartesian implementation, the spiral sequence had superior artery–vein contrast, better spatial resolution (1.2 mm2 versus 1.5 mm2), and was acquired in less time (1.4 min versus 7.5 min). Conclusion The spiral spin echo train sequence can be used for flow-independent angiography to generate threedimensional angiograms of the periphery quickly and without the use of contrast agents. PMID:24753164

  20. Nonrigid retrospective respiratory motion correction in whole-heart coronary MRA.

    PubMed

    Schmidt, Johannes F M; Buehrer, Martin; Boesiger, Peter; Kozerke, Sebastian

    2011-12-01

    A nonrigid retrospective respiratory motion correction scheme is presented for whole-heart coronary imaging with interleaved acquisition of motion information. The quasi-periodic nature of breathing is exploited to populate a 3D nonrigid motion model from low-resolution 2D imaging slices acquired interleaved with a segmented 3D whole-heart coronary scan without imposing scan time penalty. Reconstruction and motion correction are based on inversion of a generalized encoding equation. Therein, a forward model describes the transformation from the motion free image to the motion distorted k-space data, which includes nonrigid spatial transformations. The effectiveness of the approach is demonstrated on 10 healthy volunteers using free-breathing coronary whole-heart scans. Although conventional respiratory-gated acquisitions with 5-mm gating window resulted in an average gating efficiency of 51% ± 11%, nonrigid motion correction allowed for gate-free acquisitions, and hence scan time reduction by a factor of two without significant penalty in image quality. Image scores and quantitative image quality measures for the left coronary arteries showed no significant differences between 5-mm gated and gate-free acquisitions with motion correction. For the right coronary artery, slightly reduced image quality in the motion corrected gate-free scan was observed as a result of the close vicinity of anatomical structures with different motion characteristics. Magn Reson Med, 2011. © 2011 Wiley Periodicals, Inc.

  1. Detection and Classification of Power Quality Disturbancewaveform Using MRA Based Modified Wavelet Transfrom and Neural Networks

    NASA Astrophysics Data System (ADS)

    Chandrasekar, Perumal; Kamaraj, Vijayarajan

    2010-07-01

    In this paper, the modified wavelet based artificial neural network (ANN) is implemented and tested for power signal disturbances. The power signal is decomposed by using modified wavelet transform and the classification is carried by using ANN. Discrete modified wavelet transforms based signal decomposition technique is integrated with the back propagation artificial neural network model is proposed. Varieties of power quality events including voltage sag, swell, momentary interruption, harmonics, transient oscillation and voltage fluctuation are used to test the performance of the proposed approach. The simulation is carried out by using MATLAB software. The simulation results show that the proposed scheme offers superior detection and classification compared to the conventional approaches.

  2. The real-time interactive 3-D-DVA for robust coronary MRA.

    PubMed

    Sachs, T S; Meyer, C H; Pauly, J M; Hu, B S; Nishimura, D G; Macovski, A

    2000-02-01

    A graphical user interface (GUI) has been developed which enables interactive feedback and control to the real-time diminishing variance algorithm (DVA). This interactivity allows the user to set scan parameters, view scan statistics, and view image updates during the course of the scan. In addition, the DVA has been extended to simultaneously reduce motion artifacts in three dimensions using three orthogonal navigators. Preliminary in vivo studies indicate that these improvements to the standard DVA allow for significantly improved consistency and robustness in eliminating respiratory motion artifacts from MR images, particularly when imaging the coronary arteries.

  3. 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...

  4. 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...

  5. 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

  6. 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...

  7. 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...

  8. 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. ...

  9. 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.

  10. 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. ...

  11. 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.

  12. Interruption of the inferior vena cava with azygos/hemiazygos continuation accompanied by distinct renal vein anomalies: MRA and CT assessment.

    PubMed

    Yilmaz, E; Gulcu, A; Sal, S; Obuz, F

    2003-01-01

    We report a case of interruption of the inferior vena cava with azygos/hemiazygos continuation and additional variations of the renal veins, an uncommon developmental anomaly. Magnetic resonance angiography and computed tomography, in association with clinical awareness, can be used to diagnose this entity.

  13. 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...

  14. 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...

  15. 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

  16. Image Quality and Stenosis Assessment of Non-Contrast-Enhanced 3-T Magnetic Resonance Angiography in Patients with Peripheral Artery Disease Compared with Contrast-Enhanced Magnetic Resonance Angiography and Digital Subtraction Angiography.

    PubMed

    Liu, Jiayi; Zhang, Nan; Fan, Zhaoyang; Luo, Nan; Zhao, Yike; Bi, Xiaoming; An, Jing; Chen, Zhong; Liu, Dongting; Wen, Zhaoying; Fan, Zhanming; Li, Debiao

    2016-01-01

    To evaluate the diagnostic performance of flow-sensitive dephasing (FSD)-prepared steady-state free precession (SSFP) magnetic resonance angiography (MRA) at 3 T for imaging infragenual arteries relative to contrast-enhanced MRA (CE-MRA) and digital subtraction angiography (DSA). A series of 16 consecutive patients with peripheral arterial disease (PAD) underwent a combined peripheral MRA protocol consisting of FSD-MRA for the calves and large field-of-view CE-MRA. DSA was performed on all patients within 1 week of the MR angiographies. Image quality and degree of stenosis was assessed by two readers with rich experience. Inter-observer agreement was determined using kappa statistics. Receiver operating characteristic (ROC) curve analysis determined the diagnostic value of FSD-MRA, CE-MRA, and CE-MRA combined with FSD-MRA (CE+FSD MRA) in predicting vascular stenosis. At the calf station, no significantly difference of subjective image quality scores was found between FSD-MRA and CE-MRA. Inter-reader agreement was excellent for both FSD-MRA and CE-MRA. Both of FSD-MRA and CE-MRA carry a stenosis overestimation risk relative to DSA standard. With DSA as the reference standard, ROC curve analysis showed that the area under the curve was largest for CE+FSD MRA. The greatest sensitivity and specificity were obtained when a cut-off stenosis score of 2 was used. In patients with severe PAD,3 T FSD-MRA provides good-quality diagnostic images without a contrast agent and is a good supplement for CE-MRA. CE+FSD MRA can improve the accuracy of vascular stenosis diagnosis.

  17. 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 ASD(MRA&L...

  18. 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 ASD(MRA&L...

  19. 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 ASD(MRA&L...

  20. 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 ASD(MRA&L...

  1. 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 ASD(MRA&L...

  2. Non-enhanced, ECG-gated MR angiography of the pedal vasculature: comparison with contrast-enhanced MR angiography and digital subtraction angiography in peripheral arterial occlusive disease.

    PubMed

    Schubert, Tilman; Takes, Martin; Aschwanden, Markus; Klarhoefer, Markus; Haas, Tanja; Jacob, Augustinus L; Liu, David; Gutzeit, Andreas; Kos, Sebastian

    2016-08-01

    This study was conducted in order to compare a high resolution, non-contrast-enhanced MRA (NATIVE SPACE, NE-MRA) of the pedal vasculature with contrast-enhanced MRA (CE-MRA) and digital subtraction angiography (DSA) in patients with peripheral arterial occlusive disease (PAOD). The prospective study consists of 20 PAOD patients. All patients underwent percutaneous transluminal angioplasty or stenting and received MR angiographies the following day. With CE-MRA, 75.7 % of vessel segments showed good, 16.4 % suboptimal and 7.9 % not usable image quality. With NE-MRA, 64.6 % showed good, 18.6 % suboptimal and 16.8 % not usable image quality. CE-MRA showed a sensitivity and negative predictive value of 90 %/95 % regarding significant stenosis (greater than 50 %), and specificity and positive predictive value were 88 %/77 %. Accordingly, sensitivity and negative predictive value for the NE-MRA were 96 %/97 % and specificity and positive predictive value were 80 %/69 % for stenoses greater than 50 %. The applied NE-MRA technique achieves high diagnostic accuracy even in very small distal arteries of the foot. However, the rate of non-diagnostic vessel segments is considerably higher for NE-MRA than for CE-MRA. NE-MRA is a valuable alternative to CE-MRA in selected patients. • Comparison of non-enhanced MRA with contrast-enhanced MRA and DSA as gold standard. • High resolution MRA at 3 T for the depiction of small pedal vessels. • Evaluation of high resolution non-enhanced MRA in PAOD patients.

  3. Initial clinical evaluation of a non-contrast-enhanced MR angiography method in the distal lower extremities.

    PubMed

    Priest, Andrew Nicholas; Joubert, Ilse; Winterbottom, Andrew Philip; See, Teik Choon; Graves, Martin John; Lomas, David John

    2013-12-01

    To report the initial experience and diagnostic performance applying a novel flow-dependent non-contrast-enhanced MR angiography (NCE-MRA) method, in patients with suspected peripheral vascular disease, in comparison with established contrast-enhanced MRA (CE-MRA). The lower legs of 34 patients were imaged at 1.5 T with both NCE-MRA and CE-MRA. The NCE-MRA method consisted of a cardiac-gated balanced-SSFP sequence with controllable flow-suppression preparation. Flow-suppressed and unsuppressed datasets were subtracted to obtain angiograms. Two experienced radiologists assessed both NCE-MRA and CE-MRA images, first independently and then in consensus to resolve significant disagreements. Signal loss, vessel conspicuity, vascular disease, venous contamination, artifacts, and diagnostic confidence were assessed. Using the CE-MRA as the "gold standard," the per-segment sensitivity and specificity for detection of significant disease were 81.7% and 90.9%, respectively. Mean diagnostic confidence (scale 0-4) was 3.4 for NCE-MRA and 3.9 for CE-MRA. Most vessel segments were well visualized but the popliteal arteries often suffered some technique-related signal loss. The NCE-MRA method was able to visualize most vessel segments with good or excellent confidence, few artifacts, and excellent background suppression, giving moderate agreement with CE-MRA. However, some segments were poorly visualized, probably due to flow profile distortion in these patients. Copyright © 2012 Wiley Periodicals, Inc.

  4. 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 this...

  5. 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 this...

  6. 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 ASD...

  7. 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 this...

  8. Contrast-Enhanced and Time-of-Flight MR Angiographic Assessment of Endovascular Coiled Intracranial Aneurysms at 1.5 T

    PubMed Central

    Levent, Akin; Yuce, Ihsan; Eren, Suat; Ozyigit, Omer; Kantarci, Mecit

    2014-01-01

    Summary This study evaluated contrast-enhanced magnetic resonance angiography (CE-MRA) and three-dimensional time-of-flight magnetic resonance angiography (3D-TOF-MRA) through comparisons with digital subtraction angiography (DSA) for the follow-up of intracranial aneurysms treated with detachable coils. Sixty-seven patients with 79 aneurysms underwent 3D-TOF-MRA, CE-MRA, and catheter angiography one year after coiling. Two independent observers classified recanalization status on images as neck or body remnant or no recanalization. For 3D-TOF-MRA and CE-MRA, the intermodality agreement, interobserver agreement, and correlation with angiography were assessed. Sixty-seven patients with 79 coiled aneurysms agreed to participate in the study. Three aneurysms could not be detected on 3D-TOF-MRA, so they were excluded from this study. Interobserver agreement was very good for 3D-TOF-MRA and CE-MRA (kappa (κ): 0.87, 0.94, respectively). Correlation of TOF-MRA with angiography was good (κ: 0.76). Correlation of CE-MRA with angiography was excellent (κ: 0.91). The sensitivity and specificity of TOF-MRA were 92% and 98%, respectively. The sensitivity and specificity of CE-MRA were 96% and 98%, respectively. After selective embolization of intracranial aneurysms, CE-MRA is useful and comparable to DSA in the assessment of aneurysmal recanalization. Agreement with the gold standard is stronger with CE-MRA than with 3D-TOF-MRA. PMID:25496678

  9. [Non-contrast-Enhanced MR angiography for selective evaluation of the hepatic portal vein].

    PubMed

    Wu, Bing; Sun, JiayU; Wang, Chenglong; Xia, Chuncao; Li, Changxian

    2011-08-01

    This study was aimed to compare and evaluate the diagnostic performance of non-contrast-enhanced MR angiography (NCE-MRA) with contrast-enhanced MR angiography (CE-MRA) in the anatomic assessment of hepatic portal vein. Thirty people, ten patients with hepatic cirrhosis without ascites and twenty normal physical examination donors as control group were included in the NCE-MRA and CE-MRA with the same 1.5T MR scanner. Anatomic angiographic images were reconstructed and their datasets available for analysis independently performed by two radiologists. Assessment of data quality of hepatic portal vein vessels was rated with a four-point scale. After consensus reading, a total 27 images (90%) scored more than 3 point were observed in NCE-MRA and 28 (93.3%) in CE-MRA, respectively. Segmental branch vessels were visualized on MR angiography in the majority of cases. Both NCE-MRA and CE-MRA correctly characterized the hepatic portal veins with grade 5 and without false positive cases. Only 4 false negatives with grade 6 were missed in NCE-MRA group. There were no statistically significant differences between NCE-MRA and CE-MRA for characterization of hepatic vasculature (P < 0.05). Kappa value was larger than 0.75 for both reviewers. A conclusion could be drawn that NCE-MRA is a non-invasive and effective method that provides a comprehensive assessment of the hepatic portal vein.

  10. Diagnostic accuracy of contrast-enhanced MR angiography and unenhanced proton MR imaging compared with CT pulmonary angiography in chronic thromboembolic pulmonary hypertension.

    PubMed

    Rajaram, Smitha; Swift, Andrew J; Capener, David; Telfer, Adam; Davies, Christine; Hill, Catherine; Condliffe, Robin; Elliot, Charles; Hurdman, Judith; Kiely, David G; Wild, Jim M

    2012-02-01

    To evaluate the diagnostic accuracy of contrast-enhanced MR angiography (CE-MRA) and the added benefit of unenhanced proton MR angiography compared with CT pulmonary angiography (CTPA) in patients with chronic thromboembolic disease (CTE). A 2 year retrospective study of 53 patients with chronic thromboembolic pulmonary hypertension who underwent CTPA and MRI for suspected pulmonary hypertension and a control group of 36 patients with no CT evidence of pulmonary embolism. The MRI was evaluated for CTE and the combined diagnostic accuracy of ce-MRA and unenhanced proton MRA was determined. CE-MRA generated lung perfusion maps were also assessed. The overall sensitivity and specificity of CE-MRA in diagnosing proximal and distal CTE were 98% and 94%, respectively. The sensitivity improved from 50% to 88% for central vessel disease when CE-MRA images were analysed with unenhanced proton MRA. The CE-MRA identified more stenoses (29/18), post-stenosis dilatation (23/7) and occlusions (37/29) compared with CTPA. The CE-MRA perfusion images showed a sensitivity of 92% for diagnosing CTE. CE-MRA has high sensitivity and specificity for diagnosing CTE. The sensitivity of CE-MRA for visualisation of adherent central and lobar thrombus significantly improves with the addition of unenhanced proton MRA which delineates the vessel wall.

  11. Fat-Suppressed Gadolinium-Enhanced Three-Dimensional Magnetic Resonance Angiography Adequately Depicts the Status of Iliac Arteries Following Atherectomy and Stent Placement

    SciTech Connect

    Amano, Yasuo; Gemma, Kazuhito; Kawamata, Hiroshi; Kumazaki, Tatsuo

    1998-07-15

    Fat-suppressed, three-dimensional magnetic resonance angiography (3D MRA) was performed on nine patients with 11 iliac artery stenoses following atherectomy or stent placement. The MRA accurately depicted continued patency, restenosis, or aneurysm formation when compared with immediate posttreatment conventional arteriography. Therefore MRA is accurate and can be used independently for clinical decision making.

  12. 21 CFR 26.0 - General.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... the United States and the European Community (EC), or the rights and obligations of the United States or the EC under that agreement. Whereas the parties to the MRA are the United States and EC, this... implementation of the MRA by the EC, which will implement the MRA in accordance with its internal procedures,...

  13. 21 CFR 26.0 - General.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... the United States and the European Community (EC), or the rights and obligations of the United States or the EC under that agreement. Whereas the parties to the MRA are the United States and EC, this... implementation of the MRA by the EC, which will implement the MRA in accordance with its internal procedures,...

  14. 21 CFR 26.0 - General.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... the United States and the European Community (EC), or the rights and obligations of the United States or the EC under that agreement. Whereas the parties to the MRA are the United States and EC, this... implementation of the MRA by the EC, which will implement the MRA in accordance with its internal procedures,...

  15. 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 DoD...

  16. MR angiography at 3 Tesla to assess proximal internal carotid artery stenoses: contrast-enhanced or 3D time-of-flight MR angiography?

    PubMed

    Weber, J; Veith, P; Jung, B; Ihorst, G; Moske-Eick, O; Meckel, S; Urbach, H; Taschner, C A

    2015-03-01

    The aim of this study was to compare the diagnostic accuracy of 3D time-of-flight (TOF-MRA) and contrast-enhanced (CE-MRA) magnetic resonance angiography at 3 T for detection and quantification of proximal high-grade stenosis using multidetector computed tomography angiography (MDCTA) as reference standard. The institutional ethics committee approved this prospective study. A total of 41 patients suspected of having internal carotid artery (ICA) stenosis underwent both MDCTA and MRA. CE-MRA and TOF-MRA were performed using a 3.0-T imager with a dedicated eight-element cervical coil. ICA stenoses were measured according to the North American Symptomatic Carotid Endarterectomy Trial criteria and categorized as 0-25 % (minimal), 25-50 % (mild), 50-69 % (moderate), 70-99 % (high grade), and 100 % (occlusion). Sensitivity and specificity for the detection of high-grade ICA stenoses (70-99 %) and ICA occlusions were determined. In addition, intermodality agreement was assessed with κ-statistics for detection of high-grade ICA stenoses (70-99 %) and ICA occlusions. A total of 80 carotid arteries of 41 patients were reviewed. Two previously stented ICAs were excluded from analysis. On MDCTA, 7 ICAs were occluded, 12 ICAs presented with and 63 without a high-grade ICA stenosis (70-99 %). For detecting 70-99 % stenosis, both 3D TOF-MRA and CE-MRA were 91.7 % sensitive and 98.5 % specific, respectively. Both MRA techniques were highly sensitive (100 %), and specific (CE-MRA, 100 %; TOF-MRA, 98.7 %) for the detection of ICA occlusion. However, TOF-MRA misclassified one high-grade stenosis as occlusion. Intermodality agreement for detection of 70-99 % ICA stenoses was excellent between TOF-MRA and CE-MRA [κ = 0.902, 95 % confidence interval (CI) = 0.769-1.000], TOF-MRA and MDCTA (κ = 0.902, 95 % CI = 0.769-1.000), and CE-MRA and MDCTA (κ = 0.902, 95 % CI = 0.769-1.000). Both 3D TOF-MRA and CE-MRA at 3 T are

  17. Magnetic Resonance Angiography Using Fresh Blood Imaging in Oral and Maxillofacial Regions

    PubMed Central

    Oda, Masafumi; Tanaka, Tatsurou; Kito, Shinji; Habu, Manabu; Kodama, Masaaki; Kokuryo, Shinya; Miyamoto, Ikuya; Yoshiga, Daigo; Yamauchi, Kensuke; Nogami, Shinnosuke; Wakasugi-Sato, Nao; Matsumoto-Takeda, Shinobu; Ishikawa, Ayataka; Nishida, Ikuko; Saeki, Katsura; Morikawa, Kazumasa; Matsuo, Kou; Seta, Yuji; Yamashita, Yoshihiro; Maki, Kenshi; Tominaga, Kazuhiro; Morimoto, Yasuhiro

    2012-01-01

    The present paper provides general dentists with an introduction to the clinical applications and significance of magnetic resonance angiography (MRA) in the oral and maxillofacial regions. Specifically, the method and characteristics of MRA are first explained using the relevant MR sequences. Next, clinical applications to the oral and maxillofacial regions, such as identification of hemangiomas and surrounding vessels by MRA, are discussed. Moreover, the clinical significance of MRA for other regions is presented to elucidate future clinical applications of MRA in the oral and maxillofacial regions. PMID:23118751

  18. [Non-contrast-enhanced MR angiography for selective visualization of the hepatic vein].

    PubMed

    Wu, Bing; Sun, Jia-Yu; Xia, Chun-Cao; Li, Chang-Xian

    2011-05-01

    To evaluate the diagnostic performance of non-contrast-enhanced MR angiography (NCE-MRA) in the preoperative assessment of hepatic vein. Contrast-enhanced MR angiography (CE-MRA)and NCE-MRA were performed on ten patients with hepatic cirrhosis and twelve potential living liver donors with the same 1. 5T MR scanner. The anatomic angiographic images were reconstructed and reviewed by two radiologists independently. The quality of the images of hepatic vein vessels was rated with a four point scale. After consensus reading, 19 NCE-MRA images (86.4%) and 20 CE-MRA images (90.9%) scored more than 3 point, respectively. The segmental branch vessels were visualized on MR angiography in the majority of cases. Both NCE-MRA and CE-MRA correctly characterized 20 out of 22 hepatic veins without false positive reporting. The NCE-MRA reported two false negative cases. There were no statistically significant differences between NCE-MRA and CE-MRA for the characterization of hepatic vasculature (P > 0.05). High consistency was achieved between the two reviewers, with Kappa values over 0.75. NCE-MRA is a non-invasive and effective method for the comprehensive assessment of hepatic vein.

  19. Usefulness of Non-Contrast-Enhanced MR Angiography Using a Silent Scan for Follow-Up after Y-Configuration Stent-Assisted Coil Embolization for Basilar Tip Aneurysms.

    PubMed

    Takano, N; Suzuki, M; Irie, R; Yamamoto, M; Hamasaki, N; Kamagata, K; Kumamaru, K K; Hori, M; Oishi, H; Aoki, S

    2017-03-01

    Y-configuration stent-assisted coil embolization is used for treating wide-neck aneurysms. Noninvasive alternatives to x-ray DSA for follow-up after Y-configuration stent-assisted coil embolization treatment are required. This study aimed to assess the usefulness of non-contrast-enhanced MRA by using a Silent Scan (silent MRA) for follow-up after Y-configuration stent-assisted coil embolization for basilar tip aneurysms. Seven patients treated with Y-configuration stent-assisted coil embolization for basilar tip aneurysms underwent silent MRA, 3D TOF-MRA, and DSA. Silent MRA and 3D TOF-MRA images were obtained during the same scan session on a 3T MR imaging system. Two neuroradiologists independently reviewed both types of MRA images and subjectively scored the flow in the stents on a scale of 1 (not visible) to 5 (nearly equal to DSA) by referring to the latest DSA image as a criterion standard. Furthermore, we evaluated the visualization of the neck remnant. In all patients, the 2 observers gave a higher score for the flow in the stents on silent MRA than on 3D TOF-MRA. The average score ± standard deviation was 4.07 ± 0.70 for silent MRA and 1.93 ± 0.80 (P < .05) for 3D TOF-MRA. Neck remnants were depicted by DSA in 5 patients. In silent MRA, neck remnants were depicted in 5 patients, and visualization was similar to DSA; however, in 3D TOF-MRA, neck remnants were depicted in only 1 patient. Silent MRA might be useful for follow-up after Y-configuration stent-assisted coil embolization. © 2017 by American Journal of Neuroradiology.

  20. 3D non-contrast-enhanced ECG-gated MR angiography of the lower extremities with dual-source radiofrequency transmission at 3.0 T: Intraindividual comparison with contrast-enhanced MR angiography in PAOD patients.

    PubMed

    Rasper, Michael; Wildgruber, Moritz; Settles, Marcus; Eckstein, Hans-Henning; Zimmermann, Alexander; Reeps, Christian; Rummeny, Ernst J; Huber, Armin M

    2016-09-01

    To compare prospectively image quality and diagnostic confidence of flow-sensitive 3D turbo spin echo (TSE)-based non-contrast-enhanced MR angiography (NE-MRA) at 3.0 T using dual-source radiofrequency (RF) transmission with contrast-enhanced MRA (CE-MRA) in patients with peripheral arterial occlusive disease (PAOD). After consent was obtained, 35 patients (mean age 69.1 ± 10.6 years) with PAOD stage II-IV underwent NE-MRA followed by CE-MRA. Signal-to-noise ratio and contrast-to-noise ratio were calculated. Subjective image quality was independently assessed by two radiologists and stenosis scoring was performed in 875 arterial segments. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for stenosis classification were calculated using CE-MRA as a reference method. Diagnostic agreement with CE-MRA was evaluated with Cohen's kappa statistics. NE-MRA provided high objective and subjective image quality at all levels of the arterial tree. Sensitivity and specificity for the detection of relevant stenosis was 91 % and 89 %, respectively; the NPV was 96 % and the PPV 78 %. There was good concordance between CE-MRA and NE-MRA in stenosis scoring. 3D electrocardiography (ECG)-gated TSE NE-MRA with patient-adaptive dual-source RF transmission at 3.0 T is a promising alternative for PAOD patients with contraindications for gadolinium-based contrast agents. It offers high sensitivity and NPV values in the detection of clinically relevant arterial stenosis. • Flow-sensitive TSE NE-MRA is a promising technique for PAOD evaluation. • Diagnostic accuracy is comparable to contrast-enhanced MRA. • NE-MRA eliminates the risk of NSF in patients with renal insufficiency. • Costs arising from the use of contrast agents can be avoided.

  1. Non-enhanced MR angiography of renal arteries: comparison with contrast-enhanced MR angiography.

    PubMed

    Angeretti, M G; Lumia, D; Canì, A; Barresi, M; Nocchi Cardim, L; Piacentino, F; Maresca, A M; Novario, R; Genovese, E A; Fugazzola, C

    2013-09-01

    The main causes of renal artery stenosis (RAS) are atherosclerosis and fibromuscular dysplasia. Despite contrast-enhanced magnetic resonance angiography (CE-MRA) being a safe and reliable method for diagnosis of RAS especially in young individuals, recently it has been possible to adopt innovative technologies that do not require paramagnetic contrast agents. To assess the accuracy of steady-state free-precession (SSFP) non-contrast-enhanced magnetic resonance angiography (NC-MRA) by using a 1.5 T MR scanner for the detection of renal artery stenosis, in comparison with breath-hold CE-MRA as the reference standard. Sixty-three patients (33 men, 30 women) with suspected renovascular hypertension (RVHT) were examined by a 1.5T MR scanner; NC-MRA with an electrocardiography (ECG)-gated SSFP sequence was performed in 58.7% (37/63) of patients; in 41.3% (26/63) of patients a respiratory trigger was used in addition to cardiac gating. CE-MRA, with a three-dimensional gradient echo (3D-GRE) T1-weighted sequence, was performed in all patients within the same session. Maximum intensity projection (MIP) image quality, number of renal arteries, and the presence of stenosis were assessed by two observers (independently for NC-MRA and together for CE-MRA). The agreement between NC-MRA and CE-MRA as well as the inter-observer reproducibility were calculated with Bland-Altman plots. MIP image quality was considered better for NC-MRA. NC-MRA identified 143 of 144 (99.3%) arteries detected by CE-MRA (an accessory artery was not identified). Fourteen stenoses were detected by CE-MRA (11 atherosclerotic, 3 dysplastic) with four of 14 (28.5%) significant stenosis. Bland-Altman plot demonstrated an excellent concordance between NC-MRA and CE-MRA; particularly, the reader A evaluated correctly all investigated arteries, while over-estimation of two stenoses occurred for reader B. Regarding NC-MRA, inter-observer agreement was excellent. NC-MRA is a valid alternative to CE-MRA for the

  2. Detection of infragenual arterial disease using non-contrast-enhanced MR angiography in patients with diabetes.

    PubMed

    Liu, Xin; Zhang, Na; Fan, Zhaoyang; Feng, Fei; Yang, Qi; Zheng, Hairong; Liu, Pengcheng; Li, Debiao

    2014-12-01

    To evaluate the diagnostic performance of a newly developed non-contrast-enhanced MR angiography (NCE-MRA) technique using flow-sensitive dephasing (FSD) prepared steady-state free precession (SSFP) for detecting calf arterial disease in patients with diabetes. Forty-five patients with diabetes who underwent routine contrast-enhanced MR angiography (CE-MRA) of lower extremities were recruited for NCE-MRA at the calf on a 1.5 Tesla MR system. Image quality evaluated on a 4-point scale and diagnostic performance for detecting more than 50% arterial stenosis were statistically analyzed, using CE-MRA as the standard of reference. A total of 264 calf arterial segments were obtained in the 45 patients with 88 legs. The percentage of diagnostic arterial segments was all 98% for NCE- and CE-MRA. The image quality, SNR, CNR was 3.3, 177, 138, and 3.5, 103, 99, for NCE-MRA and CE-MRA, respectively. The average sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of NCE-MRA were 97%, 96%, 90%, 99%, and 96%, respectively on a per-segment basis and 90%, 84%, 82%, 91%, and 87%, respectively, on a per-patients basis. The NCE-MRA technique demonstrates adequate image quality in the delineation of calf arteries and consistent diagnostic performance for detecting significant stenosis with CE-MRA in patients with diabetes. © 2013 Wiley Periodicals, Inc.

  3. Detection of infragenual arterial disease using noncontrast-enhanced MR angiography in patients with diabetes

    PubMed Central

    Liu, Xin; Zhang, Na; Fan, Zhaoyang; Feng, Fei; Yang, Qi; Zheng, Hairong; Liu, Pengcheng; Li, Debiao

    2013-01-01

    Purpose To evaluate the diagnostic performance of a newly developed noncontrast-enhanced MR angiography (NCE-MRA) technique using flow-sensitive dephasing (FSD) prepared steady-state free precession (SSFP) for detecting calf arterial disease in patients with diabetes. Materials and Methods Forty-five patients with diabetes who underwent routine CE-MRA of lower extremities were recruited for NCE-MRA at the calf on a 1.5T MR system. Image quality evaluated on a four-point scale and diagnostic performance for detecting more than 50% arterial stenosis were statistically analyzed, using CE-MRA as the standard of reference. Results A total of 264 calf arterial segments were obtained in the 45 patients with 88 legs. The percentage of diagnostic arterial segments was all 98% for NCE- and CE-MRA. The image quality, SNR, CNR was 3.3, 177, 138 and 3.5, 103, 99 for NCE-MRA and CE-MRA respectively. The average sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of NCE-MRA were 97%, 96%, 90%, 99%, and 96%, respectively on a per-segment basis and 90%, 84%, 82%, 91%, and 87%, respectively on a per-patients basis. Conclusion The NCE-MRA technique demonstrates adequate image quality in the delineation of calf arteries and consistent diagnostic performance for detecting significant stenosis with CE-MRA in patients with diabetes. PMID:24925770

  4. Comparison of Time-Resolved and First-Pass Contrast-Enhanced MR Angiography in Pretherapeutic Evaluation of Spinal Dural Arteriovenous Fistulas.

    PubMed

    Mathur, S; Bharatha, A; Huynh, T J; Aviv, R I; Symons, S P

    2017-01-01

    Different MRA techniques used to evaluate spinal dural arteriovenous fistulas offer unique advantages and limitations with regards to temporal and spatial resolution. The purpose of this study was to compare the efficacy and interobserver agreement of 2 commonly used contrast-enhanced spinal MRA techniques, multiphase time-resolved MRA and single-phase first-pass MRA, in assessment of spinal dural arteriovenous fistulas. Retrospective review of 15 time-resolved and 31 first-pass MRA studies in patients with clinical suspicion of spinal dural arteriovenous fistula was performed by 2 independent, blinded observers. DSA was used as the reference standard to compare the diagnostic performance of the 2 techniques. There were 10 cases of spinal dural arteriovenous fistula in the time-resolved MRA group and 20 in the first-pass MRA group. Time-resolved MRA detected spinal dural arteriovenous fistulas with sensitivity and specificity of 100% and 80%, respectively, with 100% correct-level localization rate. First-pass MRA detected spinal dural arteriovenous fistulas with sensitivity and specificity of 100% and 82%, respectively, with 87% correct-level localization rate. Interobserver agreement for localization was excellent for both techniques; however, it was higher for time-resolved MRA. In 5 cases, the site of fistula was not included in the FOV, but a prominent intradural radicular vein was observed at the edge of the FOV. Multiphase time-resolved MRA and single-phase first-pass MRA were comparable in diagnosis and localization of spinal dural arteriovenous fistulas and demonstrated excellent interobserver agreement, though there were more instances of ambiguity in fistula localization on first-pass MRA. © 2017 by American Journal of Neuroradiology.

  5. Imaging the whole body atherosclerosis: high resolution magnetic resonance angiography using blood-pool agent. Initial clinical experience.

    PubMed

    Napoli, A; Catalano, C; Anzidei, M; Lanciotti, K; Calabrese, F A; Cavallo Marincola, B; Zini, C; Di Paolo, P L; Kyventidis, T; Passariello, R

    2007-06-01

    Recently whole-body 3D MR angiography (MRA) with blood-pool contrast agent has become available. The purpose of this study was to introduce and evaluate this technique to demonstrate arterial steno-occlusive involvement in systemic atherosclerosis and to compare blood-pool enhanced MRA results with those of CT angiography (CTA) as reference modality. Twenty patients with clinically and US documented carotid occlusive disease underwent whole-body MRA on a 1.5 T scanner and CTA on a 64-MDCT unit. Ten milliliters of a blood-pool agent (MS-235 Gadofosveset Trisodium, VASOVIST, Schering, Berlin, Germany) were administered intravenously and four 3-D MRA stations were acquired successively through automatic table moving. Images were reviewed by two observers. Overall image quality of each arterial segment was assessed and rated for both MRA and CTA examinations; MRA sensitivity, MRA specificity interobserver and intermodality agreement were calculated. Whole-body MRA with blood-pool contrast agent was well tolerated by all patients. It yielded a detailed display of the arterial system with a short examination time. In 14 out of 20 patients there was extensive involvement of the arterial bed by steno-occlusive atherosclerotic disease; for the identification and characterization of vessel damage in the various vascular districts MRA sensitivity was 92-100%, MRA specificity was 95-100%; in 2 cases MRA underestimated the degree of peripheral vessel stenosis. Interobserver agreement calculated with K value was 0.63, intermodality agreement with CTA was 93% (P<0.01). The whole-body MRA technique is a valuable tool for comprehensive evaluation of arterial steno-occlusive involvement in systemic arterial atherosclerosis; there is a good agreement between blood-pool enhanced MRA results and CTA, used as modality of reference.

  6. Femoro-acetabular impingement: can indirect MR arthrography be considered a valid method to detect endoarticular damage? A preliminary study.

    PubMed

    Pozzi, Grazia; Stradiotti, Paola; Parra, Cleber Garcia; Zagra, Luigi; Sironi, Sandro; Zerbi, Alberto

    2009-01-01

    To assess the effectiveness of indirect Magnetic Resonance arthrography (i-MRa) in the detection of chondral and labral lesions related to femoro-acetabular impingement (FAI) a series of 21 hip joints in 17 patients with a clinical diagnosis of FAI were examined either with standard MR imaging, i-MRa and direct-MR arthrography (d-MRa). Sensitivity and accuracy of i-MRa in detecting chondral, labral and tardive lesions were calculated and compared with standard MR. The agreement in detecting endoarticular damage between i-MRa and d-MRa and the interobserver agreement was assessed by K statistic (p<0.05). Finally the presence of trocanteric bursitis was evaluated. I-MRa showed higher values of both sensivity and accuracy than standard MR in detecting chondral damage, with an increase to 92% for the first item and 95% for the second. The same was noticed in labrum evaluation with an increase to 88% and 90% respectively. The level of agreement between i-MRa and d-MRa in detection of chondral lesions was excellent, substantial for the labral damage and absolute for early osteoarthritic changes. An excellent interobserver agreement resulted in detection of both chondral and labral damages with i-MRa. In 6 hips (28,5%) we also found the presence of peri-trochanteric soft tissue inflammation that indicated the possibility of extrarticular involvement in FAI. Indirect-MRa can be considered a valid method of assessing endoarticular damage related to FAI, in comparison to d-MRa. It should be performed instead of standard MR if d-MRa is not available.

  7. Compressed Sensing 3-Dimensional Time-of-Flight Magnetic Resonance Angiography for Cerebral Aneurysms: Optimization and Evaluation.

    PubMed

    Fushimi, Yasutaka; Fujimoto, Koji; Okada, Tomohisa; Yamamoto, Akira; Tanaka, Toshiyuki; Kikuchi, Takayuki; Miyamoto, Susumu; Togashi, Kaori

    2016-04-01

    The aims of this study were to optimize parameters for Nesterov algorithm (NESTA) in reconstruction of 3-dimensional time-of-flight (TOF) magnetic resonance angiography (MRA) at 3 T by performing an exhaustive search and to validate the performance of compressed sensing (CS) by applying it to data from cerebral aneurysms and evaluating diagnostic quality. Three-dimensional TOF-MRA was obtained using a 3 T MR system with a 32-channel head coil for both healthy volunteers and 10 patients (11 aneurysms). No undersampling was applied for imaging parameters, including parallel imaging or other partial Fourier sampling. In the first step, the experimental setup was for healthy subjects to optimize CS parameters of NESTA and the undersampling mask pattern, so 24,696 different reconstruction conditions were surveyed for sampling rates of 8.0X and 5.0X. Mean square error (MSE) was calculated for each image reconstructed with the undersampling pattern and CS parameter sets. Evaluation was by normalized MSE, edge sharpness for MRA reconstructed using fully sampled data (MRA-full), zero-filled MRA (ZF-MRA) with Poisson disk undersampling mask, and CS-MRA (5.0X and 8.0X) with iterations of 5, 10, 15, 20, 25, 30, 35, 40, 45, and 50. CS-MRA (5.0X and 8.0X) with 5, 10, and 50 iterations of the sampling pattern and CS parameter set with the lowest MSE were visually inspected by 2 neuroradiologists to check the diagnostic quality. The sampling pattern and CS parameter set with the lowest MSE were identical for both CS-MRA 5.0X and CS-MRA 8.0X. At the initial 5 to 15 iterations, MSE of both sampling rates greatly decreased from that of ZF-MRA. For subsequent iterations, the decrease in MSE was relatively small. For CS-MRA, sharpness greatly increased from that of ZF-MRA within the initial 5 to 15 iterations, followed by slight increases with further iterations. Two neuroradiologists graded most aneurysms as excellent, with the exception of 1 to 4 aneurysms recognized as good by 1

  8. Non-Contrast-Enhanced Silent Scan MR Angiography of Intracranial Anterior Circulation Aneurysms Treated with a Low-Profile Visualized Intraluminal Support Device.

    PubMed

    Takano, N; Suzuki, M; Irie, R; Yamamoto, M; Teranishi, K; Yatomi, K; Hamasaki, N; Kumamaru, K K; Hori, M; Oishi, H; Aoki, S

    2017-08-01

    The Low-Profile Visualized Intraluminal Support Device comprises a small-cell nitinol structure and a single-wire braided stent that provides greater metal coverage than previously reported intracranial stents, as well as assumed strong susceptibility artifacts. This study aimed to assess the benefits of non-contrast-enhanced MRA by using a Silent Scan (Silent MRA) for intracranial anterior circulation aneurysms treated with Low-Profile Visualized Intraluminal Support Device stents. Thirty-one aneurysms treated with Low-Profile Visualized Intraluminal Support Device stents were assessed by using Silent MRA, 3D TOF-MRA, and x-ray DSA. The quality of MRA visualization of the reconstructed artery was graded on a 4-point scale from 1 (not visible) to 4 (excellent). Aneurysm occlusion status was evaluated by using a 2-grade scale (total occlusion/remnant [neck or aneurysm]). Weighted κ statistics were used to evaluate interobserver and intermodality agreement. The mean scores ± SDs for Silent MRA and 3D TOF-MRA were 3.16 ± 0.79 and 1.48 ± 0.67 (P < .05), respectively, with substantial interobserver agreement (κ = 0.66). The aneurysm occlusion rates of the 2-grade scale (total occlusion/remnant [neck or aneurysm]) were 69%/31% for DSA, 65%/35% for Silent MRA, and 92%/8% for 3D TOF-MRA, respectively. The intermodality agreements were 0.88 and 0.30 for DSA/Silent MRA and DSA/3D TOF-MRA, respectively. Silent MRA seems to be useful for visualizing intracranial anterior circulation aneurysms treated with Low-Profile Visualized Intraluminal Support Device stents. © 2017 by American Journal of Neuroradiology.

  9. State of the science: does the theory of maternal role attainment apply to African American motherhood?

    PubMed

    Fouquier, Katherine Ferrell

    2013-01-01

    This article reviews the current state of knowledge of the theory of maternal role attainment (MRA) and its relevance in describing African American motherhood. EBSCOhost Research Databases that included PubMed, CINAHL plus, MEDLINE, PsycINFO, SCOPUS, and Web of Science were searched for journal articles that examined maternal identity and MRA. Keyword searches included maternal identity, maternal role attainment, becoming a mother, prenatal attachment, maternal-fetal attachment, and maternal-infant attachment. Inclusion criteria for this review were published journal articles of studies conducted in the United States, with a clear delineation of the theoretical framework of MRA. Journal articles that measured MRA among women with depression or medically fragile infants were excluded. Two hundred and twelve studies were reviewed; 25 studies, published between 1975 and 2007, met the inclusion criteria. Nine articles described the theory of MRA, 11 articles measured variables thought to influence MRA, and 6 articles described maternal-fetal attachment, a construct of MRA. Studies were reviewed, categorized, and analyzed to determine current knowledge of how the theory of MRA describes African American motherhood. Categories included studies describing the theoretical framework of maternal identity and MRA, studies measuring key variables thought to impact MRA, and studies measuring maternal-fetal attachment and maternal-infant attachment. The studies were limited by homogenous samples of upper-middle-class white women and low-income, single, African American adolescents. Study results of MRA cannot be generalized to African American women. Further research is essential to identify attributes influencing MRA, specifically among larger samples of African American women with demographics similar to that of the white populations that have been included in studies thus far. © 2013 by the American College of Nurse-Midwives.

  10. 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

    .... Depot St., Springfield, 11000803 LOUISIANA Orleans Parish Lykes Brothers Steamship Company Historic... Wilson Pike, Franklin, 88000299 Russwurm, John S., House, (Williamson County MRA) Spann Town Rd. \\1/ 2...

  11. 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.

  12. 3D time-of-flight MR angiography of the intracranial vessels: optimization of the technique with water excitation, parallel acquisition, eight-channel phased-array head coil and low-dose contrast administration.

    PubMed

    Ozsarlak, O; Van Goethem, J W; Parizel, P M

    2004-11-01

    The aim of this study is three folds: to compare the eight-channel phased-array and standard circularly polarized (CP) head coils in visualisation of the intracranial vessels, to compare the three-dimensional (3D) time-of-flight (TOF) MR angiography (MRA) techniques, and to define the effects of parallel imaging in 3D TOF MRA. Fifteen healthy volunteers underwent 3D TOF MRA of the intracranial vessels using eight-channel phased-array and CP standard head coils. The following MRA techniques were obtained on each volunteer: (1) conventional 3D TOF MRA with magnetization transfer; (2) 3D TOF MRA with water excitation for background suppression; and (3) low-dose (0.5 ml) gadolinium-enhanced 3D TOF MRA with water excitation. Results are demonstrating that water excitation is a valuable background suppression technique, especially when applied with an eight-channel phased-array head coil. For central and proximal portions of the intracranial arteries, unenhanced TOF MRA with water excitation was the best technique. Low-dose contrast enhanced TOF MRA using an eight-channel phased-array head coil is superior in the evaluation of distal branches over the standard CP head coil. Parallel imaging with an acceleration factor of two allows an important time gain without a significant decrease in vessel evaluation. Water excitation allows better background suppression, especially around the orbits and at the periphery, when compared to conventional acquisitions.

  13. 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.

  14. Non-contrast-enhanced MR angiography in critical limb ischemia: performance of quiescent-interval single-shot (QISS) and TSE-based subtraction techniques.

    PubMed

    Altaha, Mustafa A; Jaskolka, Jeffrey D; Tan, Kongteng; Rick, Manuela; Schmitt, Peter; Menezes, Ravi J; Wintersperger, Bernd J

    2017-03-01

    The aim of this study was to evaluate diagnostic performance of non-contrast-enhanced 2D quiescent-interval single-shot (QISS) and 3D turbo spin-echo (TSE)-based subtraction magnetic resonance angiography (MRA) in the assessment of peripheral arteries in patients with critical limb ischemia (CLI). Nineteen consecutive patients (74 % male, 72.8 ± 9.9 years) with CLI underwent 2D QISS and 3D TSE-based subtraction MRA at 1.5 T. Axial-overlapping QISS MRA (3 mm/2 mm; 1 × 1 mm(2)) covered from the toes to the aortic bifurcation while coronal 3D TSE-based subtraction MRA (1.3 × 1.2 × 1.3 mm(3)) was restricted to the calf only. MRA data sets (two readers) were evaluated for stenosis (≥50 %) and image quality. Results were compared with digital subtraction angiography (DSA). Two hundred and sixty-seven (267) segments were available for MRA-DSA comparison, with a prevalence of stenosis ≥50 % of 41.9 %. QISS MRA was rated as good to excellent in 79.5-96.0 % of segments without any nondiagnostic segments; 89.8-96.1 % of segments in 3D TSE-based subtraction MRA were rated as nondiagnostic or poor. QISS MRA sensitivities and specificities (segmental) were 92 % and 95 %, respectively, for reader one and 81-97 % for reader two. Due to poor image quality of 3D TSE-based subtraction MRA, diagnostic performance measures were not calculated. QISS MRA demonstrates excellent diagnostic performance and higher robustness than 3D TSE-based subtraction MRA in the challenging patient population with CLI. • QISS MRA allows reliable diagnosis of peripheral artery stenosis in critical limb ischemia. • Robustness of TSE-based subtraction MRA is limited in critical limb ischemia. • QISS MRA allows robust therapy planning in PAD patients with resting leg pain.

  15. Dynamic Magnetic Resonance Angiography Provides Collateral Circulation and Hemodynamic Information in Acute Ischemic Stroke.

    PubMed

    Hernández-Pérez, María; Puig, Josep; Blasco, Gerard; Pérez de la Ossa, Natalia; Dorado, Laura; Dávalos, Antoni; Munuera, Josep

    2016-02-01

    Contrary to usual static vascular imaging techniques, contrast-enhanced dynamic magnetic resonance angiography (dMRA) enables dynamic study of cerebral vessels. We evaluated dMRA ability to assess arterial occlusion, cerebral hemodynamics, and collateral circulation in acute ischemic stroke. Twenty-five acute ischemic stroke patients with proximal anterior circulation occlusion underwent dMRA on a 3T scanner within 12 hours of symptoms onset. Diffusion weighted imaging, Tmax6 s lesion volumes and hypoperfusion intensity ratio as volume of Tmax>6 s/volume of Tmax>10 s were measured. Site and grade of occlusion (Thrombolysis in Myocardial Infarction criteria) were evaluated on time-of-flight MRA and dMRA. Leptomeningeal collaterality (American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology [ASITN/SIR] Scale) and asymmetries in venous clearance were assessed exclusively on dMRA. Collateral filling was dichotomized into incomplete (ASITN/SIR 0-2) or complete (ASITN/SIR 3-4). On dMRA, site of occlusion was M1 in 21 patients, tandem internal carotid artery/M1 in 2 and tandem internal carotid artery/terminal internal carotid artery in 2 patients. Three tandem occlusions were not detected on time-of-flight-MRA. All patients had Thrombolysis in Myocardial Infarction 0 to 1 on time-of-flight-MRA, but three of them had Thrombolysis in Myocardial Infarction 2 on dMRA. Complete collateral filling (n=12, 48%) was associated with smaller diffusion weighted imaging lesion volume (P=0.039), smaller hypoperfused volume (P=0.018), and lower hypoperfusion intensity ratio (P=0.006). Patients with symmetrical clearance of transverse sinuses (52%) were more likely to have complete collateral filling (P=0.015). As a fast, direct, feasible, noninvasive, and reliable method to assess site of occlusion, collateral circulation and hemodynamic alterations, dMRA provides profound insights in acute stroke. © 2015 American Heart Association, Inc.

  16. 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.

  17. 77 FR 45350 - Notice of Availability of Microbial Risk Assessment Guideline: Pathogenic Microorganisms With...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-31

    ... 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 MRA... document, Microbial Risk Assessment Guideline: Pathogenic Microorganisms with Focus on Food and Water will...

  18. 77 FR 3091 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-23

    ... in Part Grand Junction, CO VOR/DME....... *Paces, CO FIX 11500 *13000--MRA *Paces, CO FIX Slolm, CO... Junction, CO VOR/DME....... *Paces, CO FIX 11500 *13000--MRA *Paces, CO FIX Slolm, CO FIX.. 13000 *13000... VOR Federal Airway V591 Is Amended To Read in Part Grand Junction, CO VOR/DME....... *Paces, CO FIX...

  19. Regression Analysis with Dummy Variables: Use and Interpretation.

    ERIC Educational Resources Information Center

    Hinkle, Dennis E.; Oliver, J. Dale

    1986-01-01

    Multiple regression analysis (MRA) may be used when both continuous and categorical variables are included as independent research variables. The use of MRA with categorical variables involves dummy coding, that is, assigning zeros and ones to levels of categorical variables. Caution is urged in results interpretation. (Author/CH)

  20. MR Angiography of Renal Transplant Vasculature with Ferumoxytol:: Comparison of High-Resolution Steady-State and First-Pass Acquisitions.

    PubMed

    Corwin, Michael T; Fananapazir, Ghaneh; Chaudhari, Abhijit J

    2016-03-01

    This work aimed to quantify the differences in signal-to-noise ratio (SNR) and vessel sharpness between steady-state and first-pass magnetic resonance angiography (MRA) with ferumoxytol in renal transplant recipients. We performed a retrospective study of adult patients who underwent steady-state and first-pass MRA with ferumoxytol to evaluate renal transplant vasculature. SNR was calculated in the external iliac artery, and vessel sharpness was calculated in the external iliac and renal transplant arteries for both acquisitions. Data were compared using Student's t test. Fifteen patients were included (mean age 56.9 years, 10 males). The mean SNR of the external iliac artery was 42.2 (SD, 11.9) for the first-pass MRA and 41.8 (SD, 9.7) for the steady-state MRA (p = 0.92). The mean vessel sharpness was significantly higher for the steady-state MRA compared to first-pass MRA for both external iliac (1.24 vs. 0.80 mm(-1), p < 0.01) and renal transplant arteries (1.26 vs. 0.79 mm(-1), p < 0.01). Steady-state MRA using ferumoxytol improves vessel sharpness while maintaining equivalent SNR compared to conventional first-pass MRA in renal transplant patients. Copyright © 2015 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

  1. 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…

  2. 3D printing of intracranial artery stenosis based on the source images of magnetic resonance angiograph.

    PubMed

    Xu, Wei-Hai; Liu, Jia; Li, Ming-Li; Sun, Zhao-Yong; Chen, Jie; Wu, Jian-Huang

    2014-08-01

    Three dimensional (3D) printing techniques for brain diseases have not been widely studied. We attempted to 'print' the segments of intracranial arteries based on magnetic resonance imaging. Three dimensional magnetic resonance angiography (MRA) was performed on two patients with middle cerebral artery (MCA) stenosis. Using scale-adaptive vascular modeling, 3D vascular models were constructed from the MRA source images. The magnified (ten times) regions of interest (ROI) of the stenotic segments were selected and fabricated by a 3D printer with a resolution of 30 µm. A survey to 8 clinicians was performed to evaluate the accuracy of 3D printing results as compared with MRA findings (4 grades, grade 1: consistent with MRA and provide additional visual information; grade 2: consistent with MRA; grade 3: not consistent with MRA; grade 4: not consistent with MRA and provide probable misleading information). If a 3D printing vessel segment was ideally matched to the MRA findings (grade 2 or 1), a successful 3D printing was defined. Seven responders marked "grade 1" to 3D printing results, while one marked "grade 4". Therefore, 87.5% of the clinicians considered the 3D printing were successful. Our pilot study confirms the feasibility of using 3D printing technique in the research field of intracranial artery diseases. Further investigations are warranted to optimize this technique and translate it into clinical practice.

  3. 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.

  4. 75 FR 10814 - National Register of Historic Places; Weekly Listing of Historic Properties

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-09

    ... Square, Adel, 09000106, LISTED, 12/18/09 Polk County Mattes, Minnie Y. and Frank P., House, 1305 34th St... County Crafts Street City Stable, 90 Crafts St., Newton, 09001095, LISTED, 12/18/09 (Newton MRA) Plymouth... 3rd Ave. NE, 12- 118 5th Ave. NW, 212-258 5th Ave., Hickory, 09001103, LISTED, 12/18/ 09 (Hickory MRA...

  5. 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,...

  6. 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…

  7. Comparison of Heidelberg Retina Tomograph-3 glaucoma probability score and Moorfields regression analysis of optic nerve head in glaucoma patients and healthy individuals.

    PubMed

    Caglar, Çagatay; Gul, Adem; Batur, Muhammed; Yasar, Tekin

    2017-01-01

    To compare the sensitivity and specificity of Moorfields regression analysis (MRA) and glaucoma probability score (GPS) between healthy and glaucomatous eyes with Heidelberg Retinal Tomograph 3 (HRT-3). The study included 120 eyes of 75 glaucoma patients and 138 eyes of 73 normal subjects, for a total of 258 eyes of 148 individuals. All measurements were performed with the HRT-3. Diagnostic test criteria (sensitivity, specificity, etc.) were used to evaluate how efficiently GPS and MRA algorithms in the HRT-3 discriminated between the glaucoma and control groups. The GPS showed 88 % sensitivity and 66 % specificity, whereas MRA had 71.5 % sensitivity and 82.5 % specificity. There was 71 % agreement between the final results of MRA and GPS in the glaucoma group. Excluding borderline patients from both analyses resulted in 91.6 % agreement. In the control group the level of agreement between MRA and GPS was 64 % including borderline patients and 84.1 % after excluding borderline patients. The accuracy rate is 92 % for MRA and 91 % for GPS in the glaucoma group excluding borderline patients. The difference was nor statistically different. In both cases, agreement was higher between MRA and GPS in the glaucoma group. We found that both sensitivity and specificity increased with disc size for MRA, while the sensitivity increased and specificity decreased with larger disc sizes for GPS. HRT is able to quantify and clearly reveal structural changes in the ONH and RNFL in glaucoma.

  8. Regression Analysis with Dummy Variables: Use and Interpretation.

    ERIC Educational Resources Information Center

    Hinkle, Dennis E.; Oliver, J. Dale

    1986-01-01

    Multiple regression analysis (MRA) may be used when both continuous and categorical variables are included as independent research variables. The use of MRA with categorical variables involves dummy coding, that is, assigning zeros and ones to levels of categorical variables. Caution is urged in results interpretation. (Author/CH)

  9. Clinical applications of magnetic resonance angiography.

    PubMed

    Glazer, M; McCormack, J; Dross, P

    1992-08-01

    Recent technical advances in magnetic resonance imaging (MRI) now allow for the noninvasive study of blood flow in vessels, or magnetic resonance angiography (MRA). We describe several case reports involving the use of MRA and discuss its advantages in evaluating patients for carotid artery stenosis, intracerebral aneurysms, and arteriovenous malformations (AVMs).

  10. 75 FR 72944 - Third Party Testing for Certain Children's Products; Mattresses, Mattress Pads, and/or Mattress...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-29

    ... body that was ISO/IEC 17025 accredited by an ILAC-MRA member at the time of the test. For firewalled... ISO/IEC 17025 accredited by an accreditation body that is a signatory to the ILAC- MRA; The third... above provided that: The laboratory will be ISO/IEC 17025 accredited by an accreditation body that is a...

  11. Diagnostic accuracy of colour Doppler ultrasonography, CT angiography and blood-pool-enhanced MR angiography in assessing carotid stenosis: a comparative study with DSA in 170 patients.

    PubMed

    Anzidei, M; Napoli, A; Zaccagna, F; Di Paolo, P; Saba, L; Cavallo Marincola, B; Zini, C; Cartocci, G; Di Mare, L; Catalano, C; Passariello, R

    2012-02-01

    This study was undertaken to prospectively evaluate the diagnostic performance of colour Doppler ultrasonography (CDUS), first-pass (FP) and steady-state (SS) contrast-enhanced magnetic resonance angiography (MRA) and computed tomography angiography (CTA) of the carotid arteries using digital subtraction angiography (DSA) as the reference standard. A total of 170 patients with previous cerebrovascular events and suspected carotid artery stenoses underwent CDUS, blood-pool MRA, CTA and DSA. Accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated for CDUS, FP MRA, SS MRA and CTA. The McNemar and Wilcoxon tests and receiver operating characteristic (ROC) curve analysis were used to determine significant differences (p<0.05) between the diagnostic performances of the four modalities, and the degree of stenosis was compared using linear regression. A total of 336 carotid bifurcations were studied. The area under the curve (AUC) for degree of stenosis was: CDUS 0.85±0.02, FP MRA 0.982±0.005, SS MRA 0.994±0.002 and CTA 0.997±0.001. AUC analysis showed no statistically significant difference between CTA and MRA (p=0.0174) and a statistically significant difference between CDUS and the other techniques (p<0.001). Plaque morphology analysis showed no significant difference between CTA and SS MRA; a significant difference was seen between CTA and SS MRA versus FP MRA (p=0.04) and CDUS (p=0.038). Plaque ulceration analysis showed a statistically significant difference between MRA and CTA (0.04< p<0.046) versus CDUS (p=0.019). CTA is the most accurate technique for evaluating carotid stenoses, with a slightly better performance than MRA (97% vs. 95% for SS MRA and 92% for FP MRA) and a greater accuracy than CDUS (97% vs. 76%). Blood-pool contrast-enhanced SS sequences offer improved evaluation of degree of stenosis and plaque morphology with accuracy substantially identical to CTA.

  12. 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.

  13. Gadolinium-free MR in coarctation-can contrast-enhanced MR angiography be replaced?

    PubMed

    Kalmar, Peter I; Koestenberger, Martin; Marterer, Robert; Tschauner, Sebastian; Sorantin, Erich

    2016-01-01

    To determine the difference in vessel measurements, signal-to-noise ratio (SNR), and voxel size between contrast-enhanced and noncontrast magnetic resonance techniques in patients with coarctation of the aorta (CoA). In 39 patients, vessel size, SNR, and voxel size were compared in cine magnetic resonance imaging (MRI), gadolinium-free magnetic resonance angiography (Gd-free MRA), and contrast-enhanced MRA (ce-MRA). There was no significant difference in measurement and SNR, but there was a significant difference in voxel size (P<.001). Our results show that, in CoA patients, monitoring of vessel size using cine MRI and Gd-free MRA is equivalent to ce-MRA while being less invasive. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Magnetic resonance angiography: current status and future directions

    PubMed Central

    2011-01-01

    With recent improvement in hardware and software techniques, magnetic resonance angiography (MRA) has undergone significant changes in technique and approach. The advent of 3.0 T magnets has allowed reduction in exogenous contrast dose without compromising overall image quality. The use of novel intravascular contrast agents substantially increases the image windows and decreases contrast dose. Additionally, the lower risk and cost in non-contrast enhanced (NCE) MRA has sparked renewed interest in these methods. This article discusses the current state of both contrast-enhanced (CE) and NCE-MRA. New CE-MRA methods take advantage of dose reduction at 3.0 T, novel contrast agents, and parallel imaging methods. The risks of gadolinium-based contrast media, and the NCE-MRA methods of time-of-flight, steady-state free precession, and phase contrast are discussed. PMID:21388544

  15. The accuracy and utility of contrast-enhanced MR angiography for localization of spinal dural arteriovenous fistulas: the Toronto experience.

    PubMed

    Lindenholz, Arjen; TerBrugge, Karel G; van Dijk, J Marc C; Farb, Richard I

    2014-11-01

    The purpose of this study was to determine the accuracy and utility of contrast-enhanced MR angiography (CE-MRA) in spinal dural arteriovenous fistulas (SDAVF). A retrospective analysis from 1999-2012 identified 70 patients clinically suspected of harboring a SDAVF. Each patient underwent consecutive conventional MR-imaging, CE-MRA, and digital subtraction angiography (DSA). The presence or absence of serpentine flow voids, T2-weighted hyperintensity, and cord enhancement were evaluated, as well as location of the fistula as predicted by CE-MRA. DSA was used as the reference standard. Of the 70 cases, 53 were determined to be a SDAVF, 10 cases were shown to be other forms of vascular malformation, and 7 were DSA-negative. On MRI, all reported cases of SDAVF showed serpentine flow voids (100 %). T2-weighted hyperintensity was seen in 48 of 50 cases (96 %), extending to the conus in 41 of 48 cases (85 %). Cord enhancement was seen in 38 of 41 cases (93 %). CE-MRA correctly localized the SDAVF in 43 of the 53 cases (81 %). CE-MRA is a useful non-invasive examination for the detection and localization of SDAVF. CE-MRA facilitates but does not replace DSA as confirmation of location, fistula type, and arterial detail, which are required before treatment. • CE-MRA correctly localized the site of the SDAVF in over 80 % of cases. • CE-MRA facilitates diagnostic DSA and expedites the diagnostic process. • CE-MRA does not replace diagnostic DSA in SDAVF cases as confirmative test. • CE-MRA provides better understanding of missed or mislocalized SDAVF cases.

  16. Non-contrast-enhanced MR angiography for detecting arteriovenous fistula dysfunction in haemodialysis patients.

    PubMed

    Jin, W T; Zhang, G F; Liu, H C; Zhang, H; Li, B; Zhu, X Q

    2015-08-01

    To assess the diagnostic value of non-contrast-enhanced magnetic resonance angiography (NCE-MRA), using time-of-flight and black-blood MRA, in the evaluation of arteriovenous fistulas in haemodialysis patients in comparison to multidetector computed tomography angiography (MDCTA). NCE-MRA and MDCTA were performed on the same day in 21 patients on maintenance haemodialysis with dysfunctional arteriovenous fistulas. The fistulas included three segments: arterial inflow, anastomosis, and venous outflow. Two experienced observers, who were blinded to the results of the NCE-MRA, recorded in consensus the significant stenoses (≥50%) seen on CTA. Two other experienced observers, unaware of the results of CTA, independently recorded significant stenoses (≥50%) in the NCE-MRA. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of NCE-MRA were calculated, with MDCTA as the standard reference. Sixty-three vascular segments in the 21 patients were clearly displayed. For the two observers of NCE-MRA, the accuracy was 98% and 95.4%; sensitivity 96.4% and 96.4%; specificity 97.1% and 94.3%; positive predictive value 96.4% and 93.1%; and, negative predictive value 97.1% and 97.1%. Inter-/intra-observer agreement for detecting stenosis was excellent for NCE-MRA, with a weighted kappa of 0.968 (95% confidence interval [CI], 0.874-1) and 0.936 (95% CI, 0.848-1). Non-contrast-enhanced MRA, using time-of-flight and black-blood MRA, is a reproducible and reliable imaging technique for detecting ≥50% stenosis in dysfunctional haemodialysis arteriovenous fistulas. Copyright © 2015 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

  17. 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.

  18. Whole body magnetic resonance angiography and computed tomography angiography in the vascular mapping of head and neck: an intraindividual comparison

    PubMed Central

    2014-01-01

    Introduction The aim of the study was to compare the detectability of neck vessels with contrast enhanced magnetic resonance angiography (MRA) in the setting of a whole-body MRA and multislice computed tomography angiography (CTA) for preoperative vascular mapping of head and neck. Methods In 20 patients MRA was performed prior to microvascular reconstruction of the mandible with osteomyocutaneous flaps. CTA of the neck served as the method of reference. 1.5 T contrast enhanced magnetic resonance angiograms were acquired to visualize the vascular structures of the neck in the setting of a whole-body MRA examination. 64-slice spiral computed tomography was performed with a dual-phase protocol, using the arterial phase images for 3D CTA reconstruction. Maximum intensity projection was employed to visualize MRA and CTA data. To retrieve differences in the detectability of vessel branches between MRA and CTA, a McNemar test was performed. Results All angiograms were of diagnostic quality. There were no statistically significant differences between MRA and CTA for the detection of branches of the external carotid artery that are relevant host vessels for microsurgery (p = 0.118). CTA was superior to MRA if all the external carotid artery branches were included (p < 0.001). Conclusions MRA is a reliable alternative to CTA in vascular mapping of the cervical vasculature for planning of microvascular reconstruction of the mandible. In the setting of whole-body MRA it could serve as a radiation free one-stop-shop tool for preoperative assessment of the arterial system, potentially covering both, the donor and host site in one single examination. PMID:24884580

  19. 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

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

    SciTech Connect

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

    2016-07-05

    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 thatVibrio parahaemolyticusVtrC, 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.

  1. 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

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

    DOE PAGES

    Li, Peng; Rivera-Cancel, Giomar; Kinch, Lisa N.; ...

    2016-07-05

    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 structuremore » 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.« less

  3. Dynamic contrast-enhanced magnetic resonance angiography for the localization of spinal dural arteriovenous fistulas at 3T.

    PubMed

    Zhou, G; Li, M H; Lu, C; Yin, Y L; Zhu, Y Q; Wei, X E; Lu, H T; Zheng, Q Q; Gao, W W

    2017-02-01

    This study was undertaken to evaluate the accuracy of dynamic contrast-enhanced magnetic resonance angiography (DCE-MRA) in the precise location and demonstration of fistulous points in spinal dural arteriovenous fistulas (SDAVFs). Fifteen patients (14 men, 1 woman; age range: 40-78 years; mean: 55.5 years) harboring SDAVF who underwent preoperative DCE-MRA and spinal digital subtraction angiography (DSA) between January 2012 and January 2015 were evaluated retrospectively. Two reviewers independently evaluated the level and side of the arteriovenous fistula and feeding artery on 3T DCE-MRA and DSA images. The accuracy of DCE-MRA was assessed by comparing its findings with those from DSA and surgery in each case. All 15 patients underwent DCE-MRA and DSA. DSA was unsuccessful in two patients due to technical difficulties. All cases were explored surgically, guided by the DCE-MRA. Surgery confirmed that 14 AVF sites were located in the thoracic spine, 5 in the lumbar spine, and 1 in the cervical spine. The origin of the fistulas and feeding arteries was accurately shown by DCE-MRA in 11 of the 15 patients. DCE-MRA also detected dilated perimedullary veins in all 15 patients. Overall, DCE-MRA facilitated DSA catheterization in 10 cases. In six patients, the artery of Adamkiewicz could be observed. In 15 out of 20 fistulas (75%), both readers agreed on the location on DCE-MRA images, and the κ coefficient of the interobserver agreement was 0.67 (95% confidence interval [CI], 0.16-0.87). In 13 of 16 shunts (75%), the DCE-MRA consensus findings and DSA findings coincided. The intermodality agreement was 0.77 (95% CI: 0.35-0.92). Our DCE-MRA studies benefited from the use of a high-field 3T MR imaging unit and reliably detected and localized the SDAVF and feeding arteries. As experience with this technique grows, it may be possible to replace DSA with DCE-MRA if surgery is the planned treatment. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  4. Combined low-dose contrast-enhanced MR angiography and perfusion for acute ischemic stroke at 3T: A more efficient stroke protocol.

    PubMed

    Nael, K; Meshksar, A; Ellingson, B; Pirastehfar, M; Salamon, N; Finn, P; Liebeskind, D S; Villablanca, J P

    2014-06-01

    There is need to improve image acquisition speed for MR imaging in evaluation of patients with acute ischemic stroke. The purpose of this study was to evaluate the feasibility of a 3T MR stroke protocol that combines low-dose contrast-enhanced MRA and dynamic susceptibility contrast perfusion, without additional contrast. Thirty patients with acute stroke who underwent 3T MR imaging followed by DSA were retrospectively enrolled. TOF-MRA of the neck and brain and 3D contrast-enhanced MRA of the craniocervical arteries were obtained. A total of 0.1 mmol/kg of gadolinium was used for both contrast-enhanced MRA (0.05 mmol/kg) and dynamic susceptibility contrast perfusion (0.05 mmol/kg) (referred to as half-dose). An age-matched control stroke population underwent TOF-MRA and full-dose (0.1 mmol/kg) dynamic susceptibility contrast perfusion. The cervicocranial arteries were divided into 25 segments. Degree of arterial stenosis on contrast-enhanced MRA and TOF-MRA was compared with DSA. Time-to-maximum maps (>6 seconds) were evaluated for image quality and hypoperfusion. Quantitative analysis of arterial input function curves, SNR, and maximum T2* effects were compared between half- and full-dose groups. The intermodality agreements (k) for arterial stenosis were 0.89 for DSA/contrast-enhanced MRA and 0.63 for DSA/TOF-MRA. Detection specificity of >50% arterial stenosis was lower for TOF-MRA (89%) versus contrast-enhanced MRA (97%) as the result of overestimation of 10% (39/410) of segments by TOF-MRA. The DWI-perfusion mismatch was identified in both groups with high interobserver agreement (r = 1). There was no significant difference between full width at half maximum of the arterial input function curves (P = .14) or the SNR values (0.6) between the half-dose and full-dose groups. In patients with acute stroke, combined low-dose contrast-enhanced MRA and dynamic susceptibility contrast perfusion at 3T is feasible and results in significant scan time and contrast dose

  5. Magnetic resonance angiography manifestations and prognostic significance in HIV-negative tuberculosis meningitis.

    PubMed

    Lu, T-T; Lin, X-Q; Zhang, L; Cai, W; Dai, Y-Q; Lu, Z-Z; Wu, A-M; Bao, J; Yang, Y; Hu, X-Q; Lu, Z-Q

    2015-12-01

    To evaluate the patterns, related factors and prognostic value of abnormal magnetic resonance angiography (MRA) in human immunodeficiency virus negative tuberculous meningitis. We performed a prospective study in patients aged >14 years. Abnormality on MRA was correlated with clinical, laboratory and magnetic resonance imaging findings. Modified Barthel index was used to assess outcome at 6 months after inclusion. Of 101 patients included, MRA was abnormal in 45 (44.6%). The distribution of MRA abnormality was classified as disseminated irregular calibres of intracranial arteries with or without reduction in distant branches (29.7%, pattern 1) and localised stenosis at the base of the brain (26.7%, pattern 2). In logistic regression analysis, pattern 2 was related to stage of the disease (P = 0.002), basal exudates (P = 0.03) and infarction (P = 0.000), while pattern 1 was related to duration of disease (P = 0.050), hydrocephalus (P = 0.032) and age (P = 0.002). Pattern 1 was also correlated with infarction (P = 0.000), particularly infarction in the tubercular zone (P = 0.035) in univariate analysis. MRA abnormality was associated with paradoxical worsening (P = 0.022) and poor prognosis in univariate analysis (P = 0.035). MRA abnormality is associated with stroke and poor outcomes. Although it indicates mild vascular injury, pattern 1 MRA abnormality is nevertheless associated with infarction and needs proper intervention.

  6. Clinical and laboratory findings in primary generalized and multiple-myeloma-related amyloidosis.

    PubMed Central

    Pruzanski, W.; Katz, A.

    1976-01-01

    Thirty-four patients with primary generalized amyloidosis (PGA) and 14 with multiple-myeloma-related amyloidosis (MRA) were studied. The commonest clinical manifestations in PGA were nephrotic syndrome, hepatomegaly and congestive heart failure, and in MRA, low back pain, plasmacytoma and rheumatoid-arthritis-like syndrome. Eight patients with PGA had limited clinical expression of the disease, such as involvement of only kidneys, joints, parotid glands or gastrointestinal tract; in one patient amyloidosis was limited to lymph nodes. Low serum concentrations of total protein and albumin were common. M components were detected in the serum of 91% of patients with PGA and 92% of patients with MRA: 70% of the M components in PGA and 25% of those in MRA had lambda light chains. Bence Jones proteinemia was detected in 56% of the patients with PGA and in 77% of those with MRA. The serum concentration of immunoglobulins was decreased substantially in more than two thirds of the patients with PGA. Proteinuria (greater than 250 mg/24 h) was observed in 78% of patients with PGA and in 93% of patients with MRA. Bence Jones proteinuria was noted in 75 and 77% of patients, respectively. Plasmacytic infiltration of the bone marrow was found in 90% of the patients with PGA. The mean survival time of the patients with PGA was 28 months and of those with MRA, 29 months from the time of diagnosis. PMID:1268776

  7. Upscaling the Use of Mixed Recycled Aggregates in Non-Structural Low Cement Concrete

    PubMed Central

    López-Uceda, Antonio; Ayuso, Jesús; Jiménez, José Ramón; Agrela, Francisco; Barbudo, Auxiliadora; De Brito, Jorge

    2016-01-01

    This research aims to produce non-structural concrete with mixed recycled aggregates (MRA) in upscaled applications with low-cement content. Four slabs were executed with concrete made with different ratios of coarse MRA (0%, 20%, 40% and 100%), using the mix design, the mixing procedures and the facilities from a nearby concrete production plant. The analysis of the long-term compressive and splitting tensile strengths in concrete cores, extracted from the slabs, allowed the highlighting of the long-term high strength development potential of MRA incorporation. The study of cast specimens produced in situ under the same conditions as the slabs showed, firstly, that the use of MRA has a great influence on the properties related to durability, secondly, that the loss of compressive strength for total MRA incorporation relative to control concrete increases proportionally with the class strength, and, thirdly, that the mechanical properties (including Schmidt hammer results) from the concrete slabs showed no significant differences relative to the control concrete for coarse aggregates replacements up to 40%. Therefore, this upscaled experimental study supports the application of concrete with 100% coarse MRA incorporation and low cement content in non-structural civil works such as bike lanes, gutters, ground slabs, leveling surfaces, and subgrades for foundations. To the best of the authors’ knowledge, there have not been any upscaled applications of concrete with MRA and low cement content. PMID:28787892

  8. Follow-up of intracranial aneurysms treated by a WEB flow disrupter: a comparative study of DSA and contrast-enhanced MR angiography.

    PubMed

    Mine, Benjamin; Tancredi, Illario; Aljishi, Ali; Alghamdi, Faisal; Beltran, Margarita; Herchuelz, Maxime; Lubicz, Boris

    2016-06-01

    To compare contrast-enhanced MR angiography (CE-MRA) and DSA for the follow-up of intracranial aneurysms (IAs) treated with the Woven EndoBridge embolization system DL (WEB DL; Sequent Medical, Aliso Viejo, California, USA). We retrospectively identified all patients treated with a WEB DL between November 2010 and February 2013 in 2 hospitals. The IA occlusion was graded on follow-up CE-MRA and DSA by 4 independent readers and by 2 readers reaching a consensus, respectively. Interobserver agreement for MRA and intertechnique agreement was evaluated by calculating linear weighted κ. Fifteen patients with 16 IAs were included. Mean delay between MRA and DSA was 2 months (range 0-16 months). Interobserver agreement for MRA was substantial to almost perfect (κ=0.686-0.921; mean κ=0.809). Intertechnique agreement was moderate to substantial (κ=0.579-0.724; mean κ=0.669). Only three out of five inadequately occluded IAs were detected by MRA. CE-MRA is a useful tool for the follow-up of IAs treated with a WEB DL. However, early follow-up with DSA remains mandatory to detect inadequately occluded IAs. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  9. An exploration of the relationship between postnatal distress and maternal role attainment, breast feeding problems and breast feeding cessation in Australia.

    PubMed

    Cooke, Margaret; Schmied, Virginia; Sheehan, Athena

    2007-03-01

    To explore the relationships between maternal distress, breast feeding cessation, breast feeding problems and breast feeding maternal role attainment. Longitudinal cohort study. Three urban hospitals within Sydney, Australia. 449 women were invited to participate in the study, with an 81% response rate. Self-report questionnaires were used to collect the data in pregnancy (28-36 weeks) and 2 weeks and 3 months after birth. The Edinburgh Postnatal Depression Scale (EPDS) was used to measure postnatal distress, and the Maternal Role Attainment subscale (MRA) of the Maternal Breast Feeding Evaluation Scale (MBFES) was used to measure breast feeding maternal role attainment. Women with high MRA were less likely to stop breast feeding (even when they had breast feeding problems) than women with low MRA. Antenatal EPDS and anxiety scores were not related to breast feeding cessation or breast feeding problems when analysed alone. As hypothesised, the relationship between breast feeding cessation and postnatal distress (EPDS scores) varied according to MRA level. Women who were categorised as high MRA and no longer breast feeding had higher EPDS scores and were more likely to be categorised as distressed (36%) than women who had low MRA (<12%) or women who had high MRA and continued to breast feed (7%). There is a complex relationship between maternal identity, stopping breast feeding earlier than desired, and psychological distress. Women with strong beliefs about the importance of breast feeding to their maternal role may benefit from psychological assessment and support should they decide to stop breast feeding earlier.

  10. 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.

  11. 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.

  12. Noninvasive evaluation of collateral blood flow through circle of Willis in cervical carotid stenosis using selective magnetic resonance angiography.

    PubMed

    Ito, Kenji; Sasaki, Makoto; Kobayashi, Masakazu; Ogasawara, Kuniaki; Nishihara, Takashi; Takahashi, Tetsuhiko; Natori, Tatsunori; Uwano, Ikuko; Yamashita, Fumio; Kudo, Kohsuke

    2014-01-01

    Preoperative assessment of intracranial collateral circulation is helpful in predicting cerebral ischemia during surgical procedures for cervical internal carotid artery (ICA) stenosis. However, magnetic resonance angiography (MRA) and other less-invasive techniques cannot evaluate collateral blood flow because these techniques are nonselective. Hence, by using a newly developed selective MRA technique, we attempted to visualize collaterals via the circle of Willis in patients with ICA stenosis. Twelve patients who underwent carotid endarterectomy were prospectively examined with a 1.5-T MR scanner. Both selective and nonselective MRA were obtained using a 3-dimensional time-of-flight technique, with or without a cylindrical saturation pulse that suppresses the flow signal from the region of the target ICA. Maximum intensity projection MRA images were generated and compared with digital subtraction angiography (DSA) images. In all patients, the distal flow signal of the ipsilateral ICA was completely suppressed on selective MRA compared with nonselective MRA. In addition, collateral blood flow through the anterior and posterior communicating arteries was visualized in 5 and 2 patients, respectively. These findings corresponded well with the DSA imaging. Selective MRA techniques can readily suppress signals from the distal blood flow of the target artery and visualize the presence of collateral flows through the circle of Willis in patients with cervical ICA stenosis. Copyright © 2014 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  13. Upscaling the Use of Mixed Recycled Aggregates in Non-Structural Low Cement Concrete.

    PubMed

    López-Uceda, Antonio; Ayuso, Jesús; Jiménez, José Ramón; Agrela, Francisco; Barbudo, Auxiliadora; De Brito, Jorge

    2016-02-02

    This research aims to produce non-structural concrete with mixed recycled aggregates (MRA) in upscaled applications with low-cement content. Four slabs were executed with concrete made with different ratios of coarse MRA (0%, 20%, 40% and 100%), using the mix design, the mixing procedures and the facilities from a nearby concrete production plant. The analysis of the long-term compressive and splitting tensile strengths in concrete cores, extracted from the slabs, allowed the highlighting of the long-term high strength development potential of MRA incorporation. The study of cast specimens produced in situ under the same conditions as the slabs showed, firstly, that the use of MRA has a great influence on the properties related to durability, secondly, that the loss of compressive strength for total MRA incorporation relative to control concrete increases proportionally with the class strength, and, thirdly, that the mechanical properties (including Schmidt hammer results) from the concrete slabs showed no significant differences relative to the control concrete for coarse aggregates replacements up to 40%. Therefore, this upscaled experimental study supports the application of concrete with 100% coarse MRA incorporation and low cement content in non-structural civil works such as bike lanes, gutters, ground slabs, leveling surfaces, and subgrades for foundations. To the best of the authors' knowledge, there have not been any upscaled applications of concrete with MRA and low cement content.

  14. Centripetal Propagation of Vasoconstriction at the Time of Headache Resolution in Patients with Reversible Cerebral Vasoconstriction Syndrome.

    PubMed

    Shimoda, M; Oda, S; Hirayama, A; Imai, M; Komatsu, F; Hoshikawa, K; Shigematsu, H; Nishiyama, J; Osada, T

    2016-09-01

    Reversible cerebral vasoconstriction syndrome is characterized by thunderclap headache and diffuse segmental vasoconstriction that resolves spontaneously within 3 months. Previous reports have proposed that vasoconstriction first involves small distal arteries and then progresses toward major vessels at the time of thunderclap headache remission. The purpose of this study was to confirm centripetal propagation of vasoconstriction on MRA at the time of thunderclap headache remission compared with MRA at the time of reversible cerebral vasoconstriction syndrome onset. Of the 39 patients diagnosed with reversible cerebral vasoconstriction syndrome at our hospital during the study period, participants comprised the 16 patients who underwent MR imaging, including MRA, within 72 hours of reversible cerebral vasoconstriction syndrome onset (initial MRA) and within 48 hours of thunderclap headache remission. In 14 of the 16 patients (87.5%), centripetal propagation of vasoconstriction occurred from the initial MRA to remission of thunderclap headache, with typical segmental vasoconstriction of major vessels. These mainly involved the M1 portion of the MCA (10 cases), P1 portion of the posterior cerebral artery (10 cases), and A1 portion of the anterior cerebral artery (5 cases). This study found evidence of centripetal propagation of vasoconstriction on MRA obtained at the time of thunderclap headache remission, compared with MRA obtained at the time of reversible cerebral vasoconstriction syndrome onset. If clinicians remain unsure of the diagnosis during early-stage reversible cerebral vasoconstriction syndrome, this time point represents the best opportunity to diagnose reversible cerebral vasoconstriction syndrome with confidence. © 2016 by American Journal of Neuroradiology.

  15. Advances in MR angiography with 7T MRI: From microvascular imaging to functional angiography.

    PubMed

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

    2017-01-13

    Over the past few decades, vascular flow-dependent imaging techniques have proven to be effective for the visualization of large vessel diseases. However, these approaches are unlikely to be efficacious for small vessels because the affected small vessels cannot always be visualized directly, owing to a lack of detection sensitivity. Recently, many researchers have introduced state-of-the-art imaging techniques to visualize cerebral microvessels using ultra-high-field (UHF) magnetic resonance angiography (MRA). They have demonstrated the superiority of UHF MRA, especially for visualization of the microvasculature compared with clinical MRA images using 1.5T or 3T magnetic resonance imaging (MRI). Thus, UHF MRA may become an important investigative tool for research, facilitating examinations of vascular mechanisms for small vessel diseases and contributing to the early detection of cerebrovascular diseases in clinics. Furthermore, new imaging methods for visualizing vascular dynamics or flow effects may help investigate brain functions, especially in conjunction with blood oxygenation level-dependent contrast functional MRI modalities, as well as situations in which small vessel abnormalities are clinically important. The present article reviews recent technological advances in UHF MRA, especially 7T MRA, and discusses the potential benefits and future directions of UHF MRA. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Effectiveness of MR Angiography for the Primary Diagnosis of Acute Pulmonary Embolism: Clinical Outcomes at 3 Months and 1 Year

    PubMed Central

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

    2014-01-01

    Purpose To determine the effectiveness of MR angiography for pulmonary embolism (MRA-PE) in symptomatic patients. Materials and Methods We retrospectively reviewed all patients whom were evaluated for possible pulmonary embolism (PE) using MRA-PE. A 3-month and 1-year from MRA-PE electronic medical record (EMR) review was performed. Evidence for venous thromboembolism (VTE) (or death from PE) within the year of follow-up was the outcome surrogate for this study. Results There were 190 MRA-PE exams performed with 97.4% (185/190) of diagnostic quality. There were 148 patients (120 F: 28 M) that had both a diagnostic MRA-PE exam and 1 complete year of EMR follow-up. There were 167 patients (137 F: 30 M) with 3 months or greater follow-up. We found 83% (139/167) and 81% (120/148) MRA-PE exams negative for PE at 3 months and 1 year, respectively. Positive exams for PE were seen in 14% (23/167). During the 1-year follow-up period, five patients (false negative) were diagnosed with DVT (5/148 = 3.4 %), and one of these patients also experienced a non–life-threatening PE. The negative predictive value (NPV) for MRA-PE was 97% (92–99; 95% CI) at 3 months and 96% (90–98; 95% CI) with 1 year of follow-up. Conclusion The NPV of MRA-PE, when used for the primary diagnosis of pulmonary embolism in symptomatic patients, were found to be similar to the published values for CTA-PE. In addition, the technical success rate and safety of MRA-PE were excellent. PMID:23553735

  17. Digital Subtraction Angiography is Superior to Magnetic Resonance Angiography in Diagnosis of Cerebral Arteriovenous Malformation.

    PubMed

    Chowdhury, A H; Ghose, S K; Mohammad, Q D; Habib, M; Khan, S U; Rahman, K M

    2015-04-01

    This study was carried out to compare MRA and DSA in diagnosis of cerebral AVM. It was a retrospective observational study conducted in the Department of Neurology Dhaka Medical College Hospital (DMCH), Dhaka during the period of January 2010 to December 2010. Thirty patients with haemorrhagic stroke age ranging from 13 to 65 years were selected on the basis of inclusion and exclusion criteria as the study sample. MRA and DSA were done in all the selected patients. The mean age of the patients of haemorrhagic stroke was 30.3 ± 14.3 years and male female ratio was 2.7:1. Regarding the venous drainage of AVM 13 and 12 were superficial and deep respectively, and evaluated 100% by MRA. In the diagnosis of cerebral AVM nidus size S1: <3 and S2: 3-6 cm sensitivity was 100% but accuracy was 100% and 73.3% respectively. DSA was 100% sensitive in the diagnosis of superficial and deep venous drainage AVM. Regarding the eloquence of brain area 15 had no eloquence by both MRA and DSA and identification of eloquence of brain area sensitivity was 73.3% and accuracy was 86.7%. The main feeding vessels was found (22, 73.3%) in both DSA and MRA findings. Distal vessels was seen (8, 26.7%) in DSA but not seen in MRA findings. Intranidal aneurysm and Angiopathic AVM were seen in 3(10.0%) and 4(13.3%) respectively in DSA. This study was carried out to diagnose the patients presented with cerebral AVM by MRA and DSA. MRA could not be evaluated flow status of AVM, distal feeding arteries, intranidal aneurysm and angiopathic AVM which could be detected by DSA. So, DSA is superior to MRA in diagnosis of cerebral AVM.

  18. Cerebral arteriovenous malformations: improved nidus demarcation by means of dynamic tagging MR-angiography.

    PubMed

    Essig, M; Engenhart, R; Knopp, M V; Bock, M; Scharf, J; Debus, J; Wenz, F; Hawighorst, H; Schad, L R; van Kaick, G

    1996-01-01

    Our purpose was to further improve the target volume definition for radiosurgical treatment of cerebral arteriovenous malformations (AVMs) by means of dynamic MRA (dMRA) using a blood bolus tagging sequence. We therefore compare this technique with 3D-TOF-MRA and transfemoral high resolution angiography in plain film technique. Twenty patients with angiographically proven cerebral AVMs were investigated by dMRA, TOF-MRA, and conventional angiography during the MR-assisted radiosurgical planning protocol. The patient's head was fixed in an MR-compatible stereotactic device. The different angiography techniques were evaluated by consensus of two radiologists. AVMs were characterized by the number and origin of feeding arteries, the maximum diameter of the AVM nidus, and the venous drainage pattern. Dynamic MRA was able to demonstrate the complete AVM characteristics and hemodynamics in 12 out of 20 patients. In three patients with an AVM nidus smaller than 1 cm in diameter the technique could not reliably depict the malformation. Technical problems due to steel screws and pins in the initially used stereotactic frame occurred in five patients. Due to reduced vessel overlap and the lack of disturbances caused by formations with short T1 time, dMRA was superior to TOF-MRA in the detection and the exact localization of the AVM nidus in four patients. We conclude that dMRA is able to demonstrate reliably AVM characteristics and hemodynamics in AVMs with a nidus larger than 1 cm in diameter. Because of the improved demarcation of the AVM nidus, this technique may be a valuable adjunct to radiosurgery planning of cerebral AVMs.

  19. Planning deep inferior epigastric perforator flaps for breast reconstruction: a comparison between multidetector computed tomography and magnetic resonance angiography.

    PubMed

    Cina, A; Barone-Adesi, L; Rinaldi, P; Cipriani, A; Salgarello, M; Masetti, R; Bonomo, L

    2013-08-01

    Deep inferior epigastric perforator (DIEP) flaps have become the state of the art in breast reconstruction. We compared the diagnostic performance of multidetector computed tomography (CTA) and magnetic resonance angiography (MRA) in DIEP flap planning. Twenty-three women (mean age 48.0 years, range 26-72 years) underwent preoperative blinded evaluation using 64-slice CTA and 1.5-T MRA. Perforator identification, measurement of their calibre, intramuscular course (IMC), assessment of direct venous connections (DVC) with main superficial veins, superficial venous communications (SVC) between the right and left hemi-abdomen and deep inferior epigastric artery (DIEA) branching type were performed. Surgery was carried out by the same team. Intraoperative findings were the standard of reference. Accuracy in identifying dominant perforators was 91.3 % for both techniques and mean error in calibre measurement 1.18 ± 0.35 mm for CTA and 1.63 ± 0.39 mm for MRA. Accuracy in assessing perforator IMCs was 97.1 % for CTA and 88.4 % for MRA, DVC 94.4 % for both techniques, SVC 91.3 % as well, and DIEA branching type 100 % for CTA and 91.3 % for MRA. Image acquisition and interpretation time was 21 ± 3 min for CTA (35 ± 5 min for MRA). In a strategy to optimise DIEP flap planning avoiding radiation exposure, MRA can be proposed alternatively to CTA. • Identification of deep inferior epigastric perforators (DIEP) is important before breast reconstruction. • Both CT and MR angiography are accurate in identifying DIEA perforator branches. • CTA and MRA are equivalent in demonstrating perforator-venous connections. • MRA can be proposed as an alternative to CTA in DIEP planning.

  20. A Comparison of Magnetic Resonance Angiography Techniques for the Evaluation of Intracranial Aneurysms Treated With Stent-assisted Coil Embolization

    PubMed Central

    Cockroft, Kevin; Agarwal, Amit K; Sabat, Shyam; Kalapos, Paul

    2016-01-01

    Aim To identify the effective magnetic resonance angiography (MRA) technique to monitor intracranial aneurysms treated with stent-assisted coiling. Materials and Methods Retrospective analysis of various MRA techniques was performed in 42 patients. Three neuroradiologists independently compared non-contrast time of flight (ncTOF) MRA of the head, contrast-enhanced time of flight (cTOF) MRA of the head and dynamic contrast-enhanced MRA (CEMRA) of the head and neck or of the head. Digital subtraction angiography (DSA) was available for comparison in 32 cases. Inter-rater agreement (kappa statistic) was assessed. Results Artifactual in-stent severe stenosis or flow gap was identified by ncTOF MRA in 23 of 42 cases (55%) and by cTOF MRA in 23 of 38 cases (60%). DSA excluded in-stent stenosis or occlusion in all 32 cases. No difference was noted between ncTOF and cTOF in the demonstration of neck remnants or residual aneurysms in three cases each. CEMRA of the head and neck or of the head was rated superior to ncTOF and cTOF MRA by all three investigators in seven out of eight cases. In one case, all three techniques demonstrated signifcant artifacts due to double stent placement during coiling. The kappa statistic revealed 0.8 agreement between investigators. Conclusions In the assessment of stent-assisted coiling of intracranial aneurysm, both ncTOF and cTOF MRA show similar results. CEMRA tends to show better flow signals in stent and residual aneurysm. PMID:28083453

  1. 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

  2. Reversible Cerebral Vasoconstriction Syndrome Promptly Diagnosed with Magnetic Resonance Imaging Including Magnetic Resonance Angiography During Immunosuppressive Therapy in a 16-Year-Old Girl with Refractory Cytopenia of Childhood.

    PubMed

    Ueki, Hideaki; Sanayama, Yasushi; Miyajima, Akiyo; Tsuchimochi, Taichiro; Igarashi, Shunji; Sunami, Shosuke

    2016-11-02

    Reversible cerebral vasoconstriction syndrome (RCVS) is a syndrome characterized by severe headache with segmental vasoconstriction of the cerebral arteries that resolves within 12 weeks. A 16-year-old girl with refractory cytopenia of childhood, who was receiving the immunosuppressant cyclosporine, developed severe headache and was diagnosed with RCVS using magnetic resonance imaging, including magnetic resonance angiography (MRA). MRA is a non-invasive and very effective technique for diagnosing RCVS. MRA should be performed at the onset of severe headache during immunosuppressant administration for children with hematological disorders and may prevent sequelae such as posterior reversible encephalopathy syndrome or ischemic attack.

  3. The Harvard Catalyst Common Reciprocal IRB Reliance Agreement: An Innovative Approach to Multisite IRB Review and Oversight

    PubMed Central

    Winkler, Sabune J.; Witte, Elizabeth

    2014-01-01

    Abstract 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. PMID:25196592

  4. Comparison of native high-resolution 3D and contrast-enhanced MR angiography for assessing the thoracic aorta.

    PubMed

    von Knobelsdorff-Brenkenhoff, Florian; Gruettner, Henriette; Trauzeddel, Ralf F; Greiser, Andreas; Schulz-Menger, Jeanette

    2014-06-01

    To omit risks of contrast agent administration, native magnetic resonance angiography (MRA) is desired for assessing the thoracic aorta. The aim was to evaluate a native steady-state free precession (SSFP) three-dimensional (3D) MRA in comparison with contrast-enhanced MRA as the gold standard. Seventy-six prospective patients with known or suspicion of thoracic aortic disease underwent MRA at 1.5 T using (i) native 3D SSFP MRA with ECG and navigator gating and high isotropic spatial resolution (1.3 × 1.3 × 1.3 mm(3)) and (ii) conventional contrast-enhanced ECG-gated gradient-echo 3D MRA (1.3 × 0.8 × 1.8 mm(3)). Datasets were compared at nine aortic levels regarding image quality (score 0-3: 0 = poor, 3 = excellent) and aortic diameters, as well as observer dependency and final diagnosis. Statistical tests included paired t-test, correlation analysis, and Bland-Altman analysis. Native 3D MRA was acquired successfully in 70 of 76 subjects (mean acquisition time 8.6 ± 2.7 min), while irregular breathing excluded 6 of 76 subjects. Aortic diameters agreed close between both methods at all aortic levels (r = 0.99; bias ± SD -0.12 ± 1.2 mm) with low intra- and inter-observer dependency (intraclass correlation coefficient 0.99). Native MRA studies resulted in the same final diagnosis as the contrast-enhanced MRA. The mean image quality score was superior with native compared with contrast-enhanced MRA (2.4 ± 0.6 vs. 1.6 ± 0.5; P < 0.001). Accuracy of aortic size measurements, certainty in defining the diagnosis and benefits in image quality at the aortic root, underscore the use of the tested high-resolution native 3D SSFP MRA as an appropriate alternative to contrast-enhanced MRA to assess the thoracic aorta. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

  5. Reversible Cerebral Vasoconstriction Syndrome Promptly Diagnosed with Magnetic Resonance Imaging Including Magnetic Resonance Angiography During Immunosuppressive Therapy in a 16-Year-Old Girl with Refractory Cytopenia of Childhood

    PubMed Central

    Ueki, Hideaki; Sanayama, Yasushi; Miyajima, Akiyo; Tsuchimochi, Taichiro; Igarashi, Shunji; Sunami, Shosuke

    2016-01-01

    Reversible cerebral vasoconstriction syndrome (RCVS) is a syndrome characterized by severe headache with segmental vasoconstriction of the cerebral arteries that resolves within 12 weeks. A 16-year-old girl with refractory cytopenia of childhood, who was receiving the immunosuppressant cyclosporine, developed severe headache and was diagnosed with RCVS using magnetic resonance imaging, including magnetic resonance angiography (MRA). MRA is a non-invasive and very effective technique for diagnosing RCVS. MRA should be performed at the onset of severe headache during immunosuppressant administration for children with hematological disorders and may prevent sequelae such as posterior reversible encephalopathy syndrome or ischemic attack. PMID:27994838

  6. 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.

  7. Neuroradiologic applications of dynamic MR angiography at 3 T.

    PubMed

    Parmar, Hemant; Ivancevic, Marko K; Dudek, Nancy; Gandhi, Dheeraj; Geerts, Liesbeth; Hoogeveen, R; Mukherji, S K; Chenevert, Thomas L

    2009-02-01

    Four-dimensional time-resolved MR angiography (4D-MRA) using keyhole imaging techniques is a new method of performing contrastenhanced vascular imaging. Combining parallel imaging and keyhole imaging techniques, it is possible to obtain dynamic MRA scans up to 60 times faster, thereby achieving subsecond sampling of the contrast hemodynamics. Furthermore, imaging at 3 T gives higher signal, thus affording higher spatial resolution and allowing dynamic 3D MRA to approach the diagnostic performance of conventional digital subtraction angiography. This article presents the authors' clinical experience using 4D-MRA to evaluate various vascular abnormalities in the brain, spine, orbits, and neck at 3 T, demonstrates the imaging findings of this novel technique, and discusses its advantages and use in current neuroradiology practice.

  8. 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...

  9. 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.

  10. Negative MRI versus real disease.

    PubMed

    Weinberg, D A

    1996-01-01

    A 76-year-old diabetic woman presented with progressive binocular vertical diplopia and right eye pain. Examination revealed a pupil-involving partial right third cranial nerve palsy, with development of anisocoria over the course of several hours. MRI of the brain showed no mass lesion. MRA, even with retrospective review of the images, failed to clearly identify a 1 cm right posterior communicating artery aneurysm detected by subsequent conventional cerebral angiography. While MRA has been reported to be highly sensitive in cerebral aneurysm detection at some centers, other investigators have indicated less favorable data. Standardized protocols for data acquisition and meticulous attention to proper post-processing and image interpretation are essential if MRA is to supplant invasive arteriography. Currently, conventional (x-ray) angiography remains the gold standard for aneurysm detection, while MRA possesses excellent potential in this regard.

  11. Afghanistan: Key Oversight Issues

    DTIC Science & Technology

    2013-02-01

    of Defense Drug Interdiction and Counter-Drug Activities DOJ Department of Justice ERMA Emergency Refugee and Migration Assistance ESF...cHumanitarian assistance includes Migration and Refugee Assistance (MRA); Emergency Refugee and Migration Assistance ( ERMA ); International Disaster

  12. Unenhanced and Contrast-Enhanced MR Angiography and Perfusion Imaging for Suspected Pulmonary Thromboembolism.

    PubMed

    Ohno, Yoshiharu; Yoshikawa, Takeshi; Kishida, Yuji; Seki, Shinichiro; Karabulut, Nevzat

    2017-03-01

    This article discusses the basics of unenhanced MR angiography (MRA) and MR venography (MRV), time-resolved contrast-enhanced (CE) MRA and dynamic first-pass CE perfusion MRI, and unenhanced and CE MRV, in addition to assessing the clinical relevance of these techniques for evaluating patients with suspected pulmonary thromboembolism and deep venous thrombosis. Since the 1990s, the efficacy of MRA or MRV and dynamic perfusion MRI for patients with suspected pulmonary thromboembolism and deep venous thrombosis has been evaluated. On the basis of the results of single-center trials, comprehensive MRI protocols, including pulmonary unenhanced and CE MRA, perfusion MRI, and MRV, promise to be safe and time effective for assessing patients with suspected pulmonary thromboembolism, although future multicenter trials are required to assess the real clinical value of MRI.

  13. 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...

  14. Reply to comment by R. Philipona on “A new absolute reference for atmospheric longwave irradiance measurements with traceability to SI units”: Reply to Comment of Dr. Philipona

    SciTech Connect

    Gröbner, Julian; Wacker, Stefan; Gorman, J.

    2015-07-21

    Atmospheric longwave irradiance is currently not metrologically traceable. Traceability requires formal comparisons in the framwork of the CIPM MRA. A task team on Radiation has been created by the WMO to address these issues.

  15. Whole-body MR angiography in patients with peripheral arterial disease.

    PubMed

    Nielsen, Yousef Jesper Wirenfeldt

    2010-12-01

    Ph.D. project performed at Copenhagen University Hospital Herlev in the period 2007-2010. To investigate whole-body magnetic resonance angiography (WB-MRA) as diagnostic method in patients with peripheral arterial disease (PAD). Due to the systemic nature of atherosclerosis patients with PAD often have concomitant arterial stenoses outside the peripheral arteries. In this respect, it seems desirable to perform whole-body angiography. Currently, WB-MRA is the only imaging modality allowing assessment of the total arterial system (excluding the coronary arteries) in one examination without limiting factors like invasiveness or ionizing radiation. Four studies were performed (I-IV). Study I investigated the feasibility of performing WB-MRA in a 3T MRI system using body coil acquisition and a blood-pool contrast agent. Study II investigated the impact of a hybrid scan technique on the performance of 3T WB-MRA using body coil acquisition and an extracellular contrast agent. The aim of study III was to investigate if addition of infra-genicular steady-state MRA (SS-MRA) to first-pass imaging alone improves diagnostic performance in 3T WB-MRA. The last study (IV) was a questionnaire-based investigation of patient acceptance of WB-MRA compared to digital subtraction angiography (DSA). In all studies the inclusion criterium was referral to DSA due to PAD. Exclusion criteria were overweight exceeding the MRI system's limitations, inability to lie still due to rest pain, allergy to gadolinium-based contrast media, chronic renal insufficiency with an estimated glomerular filtration rate (eGFR) < 30 ml/min/1.73 m², dialysis, inability to obtain informed consent, and contraindications for MRI (pacemaker, claustrophobia etc.). In total, 57 patients were investigated in the technical oriented studies (I: n = 11, II: n = 26, and III: n = 20). Seventy-nine patients were included in study IV. DSA served as method of reference for calculation of WB-MRA sensitivity and specificity for

  16. Three-dimensional contrast-enhanced magnetic resonance angiography of the thoracic vasculature.

    PubMed

    Leung, D A; Debatin, J F

    1997-01-01

    Magnetic resonance angiography (MRA) has become a useful non-invasive imaging technique for the assessment of vascular disease. Due to limitations such as respiratory motion artefacts, saturations problems, and long acquisition times, applications of MRA in the thorax have largely been restricted to imaging of the aorta. The recent introduction of breath-hold three-dimensional (3D) contrast-enhanced MRA promises not only to enhance conventional MR protocols for aortic imaging, but to extend the clinical indications of MRI to diseases affecting other vascular structures of the thorax, most notably the pulmonary arteries. This article describes the technical aspects of contrast-enhanced 3D MRA and reviews existing and potential future clinical applications.

  17. 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

  18. 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.

  19. Diagnostic Tests and Procedures

    MedlinePlus

    ... Blood Tests Cardiac Catheterization Cardiac Magnetic Resonance Imaging (MRI and MRA) Computed Tomography (CT) Scan Echocardiography Electrocardiogram Electrophysiology Studies Exercise Stress Test Holter Monitoring Intravascular Ultrasound Nuclear Stress Test ...

  20. Optical Coherence Tomography

    MedlinePlus

    ... Blood Tests Cardiac Catheterization Cardiac Magnetic Resonance Imaging (MRI and MRA) Computed Tomography (CT) Scan Diagnostic Tests and Procedures Echocardiography Electrocardiogram Electrophysiology Studies Exercise Stress Test Holter Monitoring Intravascular Ultrasound Nuclear Stress Test ...

  1. Whole-body MR angiography: initial experience in imaging pediatric vasculopathy.

    PubMed

    Hong, Terence S; Greer, Mary-Louise C; Grosse-Wortmann, Lars; Yoo, Shi-Joon; Babyn, Paul S

    2011-06-01

    Radiological assessment of vasculopathy in children is typically undertaken with ultrasonography, echocardiography, conventional angiography, computed tomography and, more recently, positron emission tomography. Drawbacks of these modalities include radiation exposure or, in the case of ultrasonography, the dependence on operator skills and sufficient acoustic windows. With advancements in MR technology, which have improved sensitivity and shortened scan times, whole-body magnetic resonance angiography (WB-MRA) lends itself as a potential "one-stop shop" for vascular imaging. Currently, WB-MRA is primarily used in adult patients with atherosclerosis or multifocal regional vasculopathy. WB-MRA has not been employed in the routine assessment of pediatric vascular disease. The purpose of this article is to describe and illustrate our WB-MRA imaging technique for evaluation of pediatric vasculopathy.

  2. 32 CFR 56.6 - Information requirements.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... investigation or resolution. Each DoD Component shall submit a narrative summary report on complaints by... narrative report by memorandum to the ASD(MRA&L), or designee, whenever, pursuant to enclosure 4 of...

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

    MedlinePlus

    ... Children Early Detection, Diagnosis, and Staging 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 ...

  4. 76 FR 22608 - Third Party Testing for Certain Children's Products; Clothing Textiles: Revisions to Terms of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-22

    ... tested by a third party conformity assessment body that was ISO/IEC 17025 accredited by an ILAC-MRA..., the product was tested by a third party conformity assessment body that was ISO/IEC 17025 accredited...

  5. Time-Resolved and Bolus-Chase MR Angiography of the Leg: Branching Pattern Analysis and Identification of Septocutaneous Perforators

    PubMed Central

    Sandhu, Gurpreet S.; Rezaee, Rod P.; Wright, Katherine; Jesberger, John A.; Griswold, Mark A.; Gulani, Vikas

    2014-01-01

    OBJECTIVE The goal of this study was to compare time-resolved MR angiography (MRA) and bolus-chase MRA in the identification of peroneal artery septocutaneous perforators and for classification of the branching pattern of the arterial tree in the leg in a cohort of candidates for fibular free flap transfer operations. MATERIALS AND METHODS Retrospective analysis was performed on imaging data from 53 legs of 27 patients (age range, 27–88 years) who underwent time-resolved MRA (FLASH; TR/TE, 2.5/1.0; flip angle, 22°; voxel dimensions, 1.54 × 1.25 × 1.5 mm; acquisition time, 2.27 s/frame) and bolus-chase MRA (FLASH; 3.2/1.2; flip angle, 25°; voxel dimensions, 0.94 × 0.89 × 1 mm) at 3 T with gadobenate dimeglumine administered at 0.05 and 0.10 mmol/kg, respectively. The branching pattern was analyzed; the total number of septocutaneous perforators for each leg was calculated from the time-resolved and bolus-chase MRA data; and the results were combined. The total and average number of septocutaneous perforators per leg and the frequency of various branching patterns were calculated. The techniques were compared in terms of branching pattern and number of visible septocutaneous perforators. RESULTS A total of 84 septocutaneous perforators (1.58 ± 1.05 [SD] per leg) were identified. Pattern 1A was found in 42 legs; 1B, two legs; 2A, one leg; 2B, one; 3A, four; 3B, one; and 3D, two legs. Classification with time-resolved MRA was successful for 53 legs and with bolus-chase MRA for 51 legs (Z = 0.713, p = 0.24, one-tailed, not significant). Twenty-two septocutaneous perforators were identified with time-resolved MRA and 82 with bolus-chase MRA. CONCLUSION MRA of the leg can be used to investigate the branching pattern and identify septocutaneous perforators in a single step. With the imaging parameters and contrast dose used in this study, septocutaneous perforators can be better identified with bolus-chase MRA, although this result may be partially related to the

  6. Dynamic and static MR angiography of the supraaortic vessels at 3.0 T: intraindividual comparison of different contrast agents at equimolar dose

    PubMed Central

    Kramer, J. Harald; Arnoldi, Elisabeth; Francois, Christopher J; Wentland, Andrew L.; Nikolaou, Konstantin; Wintersperger, Bernd J.; Grist, Thomas

    2013-01-01

    Purpose Intraindividual comparison of a 1.0 molar and two 0.5 molar Gadolinium (Gd) based contrast agents (GBCA) with weak/no protein binding using equimolar dosing in dynamic and static Magnetic Resonance Angiography (MRA) of the supraaortic vessels. Material & Methods In this IRB approved study a total of 20 healthy volunteers (29±6y) underwent three consecutive supraaortic MRA exams on a 3T MR system. Order of GBCA (Gadobutrol, Gadobenate dimeglumine, Gadoterate meglumine) was randomized with a minimum interval of 48h between exams. Prior to and 45 minutes after each exam circulatory parameters were recorded. Total GBCA dose per MRA exam was 0.1mmol/kg with a 0.03/0.07 mmol/kg split for dynamic and static MRA respectively, injected at a rate of 2ml/s. Two blinded readers qualitatively assessed static MRA data sets independently using pairwise rankings (superior, inferior, equal). In addition quantitative analysis was performed with SNR and CNR evaluation as well as vessel sharpness analysis of static MRA employing an in house developed semi-automated tool. Dynamic MRA was evaluated in terms of maximal SNR. Statistical analysis was performed using Cohen’s kappa, Wilcoxon rank tests as well as mixed effects models. Results No significant differences of hemodynamic parameters were observed. In static MRA Gadobutrol was rated superior to Gadoterate meglumine(p0.0002) and equal to Gadobenate dimeglumine(p0.057) with good to excellent reader agreement (kappa 0.663 – 0.83). In static MRA SNR was significantly higher using1M Gadobutrol as compared to either 0.5M agent (p0.0458/0.0325) and CNR significantly higher as compared to Gadoterate meglumine (p 0.033) while CNR values of Gadobutrol datasets were not significantly different as compared to Gadobenate dimeglumine(p 0.134). Differences in CNR between Gadobenate dimeglumine and Gadoterate meglumine were not significant (p 0.779). Differences in vessel sharpness between the different GBCAs were also not

  7. Image fusion for radiosurgery treatments of arteriovenous malformations

    NASA Astrophysics Data System (ADS)

    Bercier, Yanic

    An interactive 3D target localisation and delineation tool has been developed for radiosurgery planning of arteriovenous malformations (AVMs). With this system, magnetic resonance (MR), MR angiography (MRA) and computed tomography (CT) volumes can be fused in stereotactic space. Stereotactic angiography (SA) images can be linked to the MRA volume by recovering the SA acquisition geometry. The MRA and SA images can be correlated (1) by ray-tracing through the MRA volume with the recovered SA acquisition geometry and overlaying the images onto the SA images and (2) by localising the AVM onto a volume rendered representation of the MRA with a 3D cursor and projecting its position onto the SA images. Target contours can then be drawn on the MRA/MR/CT images and simultaneously projected onto the SA images. The plans of patients who had previously undergone radiosurgery at our institution employing SA images for localisation and MR images for delineation were investigated. MRA datasets were also acquired at the time of MR scanning employing the 3D TOF technique. Some ray-traced MRA images correlated well visually with the SA images, others presented inconsistencies which suggest that MRA should be used only as complement to SA images. The role of the different modalities (M-RA, MR and SA) in the definition of target volumes is investigated by defining the target contours with different combinations of modalities within the interactive system. The target volumes drawn with different modalities were compared to a reference volume, drawn using MRA, MR and SA images, and presented underestimation and overestimation of target volumes ranging from 20% to 92% and from 3% to 40%. The dosimetric implications of image fusion for target delineation are investigated by retrospective evaluation of the dose coverage of the reference target volume by the original treatment plan. Target coverage inferior to 60% of the reference target volumes by the original treatment plans was obtained

  8. 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

  9. 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

  10. Comparison of Ethnic-specific Databases in Heidelberg Retina Tomography-3 to Discriminate Between Early Glaucoma and Normal Chinese Eyes

    PubMed Central

    Tan, Xiu Ling; Yap, Sae Cheong; Li, Xiang; Yip, Leonard W.

    2017-01-01

    Purpose: To compare the diagnostic accuracy of the 3 race-specific normative databases in Heidelberg Retina Tomography (HRT)-3, in differentiating between early glaucomatous and healthy normal Chinese eyes. Method: 52 healthy volunteers and 25 glaucoma patients were recruited for this prospective cross-sectional study. All underwent standardized interviews, ophthalmic examination, perimetry and HRT optic disc imaging. Area under the curve (AUC) receiver operating characteristics, sensitivity and specificity were derived to assess the discriminating abilities of the 3 normative databases, for both Moorfields Regression Analysis (MRA) and Glaucoma Probability Score (GPS). Results: A significantly higher percentage (65%) of patients were classified as “within normal limits” using the MRA-Indian database, as compared to the MRA-Caucasian and MRA-African-American databases. However, for GPS, this was observed using the African-American database. For MRA, the highest sensitivity was obtained with both Caucasian and African-American databases (68%), while the highest specificity was from the Indian database (94%). The AUC for discrimination between glaucomatous and normal eyes by MRA-Caucasian, MRA-African-American and MRA-Indian databases were 0.77 (95% CI, 0.67-0.88), 0.79 (0.69-0.89) and 0.73 (0.63-0.84) respectively. For GPS, the highest sensitivity was obtained using either Caucasian or Indian databases (68%). The highest specificity was seen with the African-American database (98%). The AUC for GPS-Caucasian, GPS-African-American and GPS-Indian databases were 0.76 (95% CI, 0.66-0.87), 0.77 (0.67-0.87) and 0.76 (0.66-0.87) respectively. Conclusion: Comparison of the 3 ethnic databases did not reveal significant differences to differentiate early glaucomatous from normal Chinese eyes. PMID:28400890

  11. Comparing Optic Nerve Head Rim Width, Rim Area, and Peripapillary Retinal Nerve Fiber Layer Thickness to Axon Count in Experimental Glaucoma

    PubMed Central

    Fortune, Brad; Hardin, Christy; Reynaud, Juan; Cull, Grant; Yang, Hongli; Wang, Lin; Burgoyne, Claude F.

    2016-01-01

    Purpose We compare spectral-domain optical coherence tomography (SDOCT) measurements of minimum rim width (MRW), minimum rim area (MRA), and peripapillary retinal nerve fiber layer thickness (RNFLT) to complete orbital optic nerve axon counts in nonhuman primates (NHP) with unilateral experimental glaucoma (EG). Methods Biweekly SDOCT measurements of MRW, MRA, and RNFLT were acquired under manometric IOP control (10 mm Hg) in 51 NHP during baseline (mean ± SD, 5.0 ± 1.6 sessions) and after laser photocoagulation was applied to the trabecular meshwork of one eye to induce chronic IOP elevation. At the study endpoint (predefined for each NHP), 100% axon counts were obtained from each optic nerve. Results For SDOCT parameters at baseline, the correlation between the two eyes of each animal was strongest for RNFLT (R = 0.97) and MRW (R = 0.97), but lower for MRA (R = 0.85). At the final time point, average values in EG eyes relative to control eyes were: −22% for RNFLT, −38% for MRW, −36% for MRA, and −36% for optic nerve axons. The correlation with axon counts was strongest for RNFLT (R = 0.81), compared to MRW (R = 0.72, P = 0.001) or MRA (R = 0.70, P = 0.001). Diagnostic sensitivity was 75% for RNFLT, 90% for MRW, and 88% for MRA; all had 100% specificity. Conclusions Peripapillary RNFLT was correlated more closely with total orbital optic nerve axon count than were the ONH parameters MRW or MRA. This is likely because glaucomatous deformation (beyond axon loss alone) has a greater influence on the ONH parameters MRW and MRA than on RNFLT. PMID:27409499

  12. Detection of residual brain arteriovenous malformations after radiosurgery: diagnostic accuracy of contrast-enhanced four-dimensional MR angiography at 3.0 T

    PubMed Central

    Lim, H K; Choi, C G; Kim, S M; Kim, J L; Lee, D H; Kim, S J; Suh, D C

    2012-01-01

    Objective To evaluate the diagnostic accuracy of four-dimensional MR angiography (4D-MRA) at 3.0 T for detecting residual arteriovenous malformations (AVMs) after Gamma Knife® (Elekta Instrument AB, Stockholm, Sweden) radiosurgery (GKRS). Methods We assessed 36 angiographically confirmed AVMs in 36 patients who had been treated with GKRS. 4D-MRA was performed after GKRS and the time intervals were 39.4±26.0 months [mean±standard deviation (SD)]. 4D-MRA was obtained at 3.0 T after contrast injection, with a measured voxel size of 1×1×1 mm and a temporal resolution of 1.1 s (13 patients) or a voxel size of 1×1×2 mm and a temporal resolution of 0.98 s (23 patients). X-ray angiography was performed as the standard reference within 53±47 days (mean±SD) after MRA. To determine a residual AVM, the 4D-MRA results were independently reviewed by two readers blinded to the X-ray angiography results. We evaluated diagnostic sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of 4D-MRA for detection of a residual AVM. Results A residual AVM was identified in 13 patients (13/36, 36%) on X-ray angiography. According to Readers 1 and 2, 4D-MRA had a sensitivity of 79.6% and 64.3%, a specificity of 90.9% and 100%, a PPV of 84.6% and 100% and an NPV of 90% and 81.5%, respectively, and a diagnostic accuracy of 86.1% for Readers 1 and 2, for detecting residual AVMs after GKRS. Conclusion The diagnostic accuracy of 4D-MRA at 3.0 T seems high, but there is still the possibility of further improving the spatiotemporal resolution of this technique. PMID:22294705

  13. Comparison of contrast-enhanced multi-station MR angiography and digital subtraction angiography of the lower extremity arterial disease.

    PubMed

    Burbelko, Mykhaylo; Augsten, Michael; Kalinowski, Marc O; Heverhagen, Johannes T

    2013-06-01

    To compare diagnostic accuracy of multi-station, high-spatial resolution contrast-enhanced MR angiography (CE-MRA) of the lower extremities with digital subtraction angiography (DSA) as the reference standard in patients with symptomatic peripheral arterial occlusive disease. Of 485 consecutive patients undergoing a run-off CE-MRA, 152 patients (86 male, 66 female; mean age, 71.6 years) with suspected peripheral arterial occlusive disease were included into our Institutional Review Board approved study. All patients underwent MRA and DSA of the lower extremities within 30 days. MRA was performed at 1.5 Tesla with a single bolus of 0.1 mmol/kg body weight of gadobutrol administered at a rate of 2.0 mL/s at three stations. Two readers evaluated the MRA images independently for stenosis grade and image quality. Sensitivity and specificity were derived. Sensitivity and specificity ranged from 73% to 93% and 64% to 89% and were highest in the thigh area. Both readers showed comparable results. Evaluation of good and better quality MRAs resulted in a considerable improvement in diagnostic accuracy. Contrast-enhanced MRA demonstrates good sensitivity and specificity in the investigation of the vasculature of the lower extremities. While a minor investigator experience dependence remains, it is standardizable and shows good inter-observer agreement. Our results confirm that the administration of Gadobutrol at a standard dose of 0.1 mmol/kg for contrast-enhanced runoff MRA is able to detect hemodynamically relevant stenoses. Use of contrast-enhanced MRA as an alternative to intra-arterial DSA in the evaluation and therapeutic planning of patients with suspected peripheral arterial occlusive disease is well justified. Copyright © 2012 Wiley Periodicals, Inc.

  14. Non-contrast-enhanced MR angiography using time-spin labelling inversion pulse technique for detecting crossing renal vessels in children with symptomatic ureteropelvic junction obstruction: comparison with surgical findings.

    PubMed

    Brucher, Nicolas; Vial, Julie; Baunin, Christiane; Labarre, David; Meyrignac, Olivier; Juricic, Michel; Bouali, Ourdia; Abbo, Olivier; Galinier, Philippe; Sans, Nicolas

    2016-08-01

    Investigate the feasibility and evaluate the accuracy of non-contrast-enhanced MR angiography (NC-MRA) using time-spin labelling inversion pulse (time-SLIP)to identify crossing renal vessels (CRVs) in children requiring surgical treatment of ureteropelvic junction (UPJ) obstructionand compare to laparoscopic findings. Nineteen children ranging from 6 to 16 years of age underwent NC-MRA using the time-SLIP technique before surgery. Two independent readers analysed the MRA images. Number of renal arteries and presence or absence of CRVs were identified and compared with surgicalfindings. Image quality was assessed, as well as the presence of CRVs and measurement of renal pelvis diameter. Intra and inter-reader agreement was calculated using Cohen's kappa coefficient and Bland-Altman plots. The overall image quality was fair or good in 88% of cases. NC-MRA demonstrated CRVs at the level of the obstruction in 10 children and no CRV in 9 children. All were confirmed intra-operatively except in one of the nine children. Sensitivity, specificity, NPV, PPV for predicting CRVs were 92%, 100%, 100% and 87.5%, respectively, for both readers. NC-MRA is a good alternative to contrast-enhanced MRA and CT scanning for identifying CRVs in children with symptomatic UPJ. • Time-SLIP technique offers acceptable imaging quality for identifying crossing renal vessel. • Time-SLIP technique is easy to apply to the renal MRA examination. • Time-SLIP technique is an alternative to contrast-enhanced MRA and CT scanning.

  15. Comparison of Ethnic-specific Databases in Heidelberg Retina Tomography-3 to Discriminate Between Early Glaucoma and Normal Chinese Eyes.

    PubMed

    Tan, Xiu Ling; Yap, Sae Cheong; Li, Xiang; Yip, Leonard W

    2017-01-01

    To compare the diagnostic accuracy of the 3 race-specific normative databases in Heidelberg Retina Tomography (HRT)-3, in differentiating between early glaucomatous and healthy normal Chinese eyes. 52 healthy volunteers and 25 glaucoma patients were recruited for this prospective cross-sectional study. All underwent standardized interviews, ophthalmic examination, perimetry and HRT optic disc imaging. Area under the curve (AUC) receiver operating characteristics, sensitivity and specificity were derived to assess the discriminating abilities of the 3 normative databases, for both Moorfields Regression Analysis (MRA) and Glaucoma Probability Score (GPS). A significantly higher percentage (65%) of patients were classified as "within normal limits" using the MRA-Indian database, as compared to the MRA-Caucasian and MRA-African-American databases. However, for GPS, this was observed using the African-American database. For MRA, the highest sensitivity was obtained with both Caucasian and African-American databases (68%), while the highest specificity was from the Indian database (94%). The AUC for discrimination between glaucomatous and normal eyes by MRA-Caucasian, MRA-African-American and MRA-Indian databases were 0.77 (95% CI, 0.67-0.88), 0.79 (0.69-0.89) and 0.73 (0.63-0.84) respectively. For GPS, the highest sensitivity was obtained using either Caucasian or Indian databases (68%). The highest specificity was seen with the African-American database (98%). The AUC for GPS-Caucasian, GPS-African-American and GPS-Indian databases were 0.76 (95% CI, 0.66-0.87), 0.77 (0.67-0.87) and 0.76 (0.66-0.87) respectively. Comparison of the 3 ethnic databases did not reveal significant differences to differentiate early glaucomatous from normal Chinese eyes.

  16. 2009 H1N1 and Seasonal Influenza Immunization Among Pregnant Women: A Comparison of Different Sources of Immunization Information

    PubMed Central

    Specker, Bonny; Wey, Betty; Fuller, Jill; Sandoval, Marie-Noel; Durkin, Maureen; Dole, Nancy; Walter, Emmanuel B.

    2013-01-01

    Validity of prenatal immunization data from different sources has not been assessed. We evaluated prenatal 2009 H1N1 and seasonal influenza (FLU) data obtained from state immunization information systems (IIS), medical record abstraction (MRA), and participant recall using medical care logs (NCS–MCL). 2009 H1N1 and FLU data were obtained from IIS and MRA for 325 pregnant women participating in the National Children’s Study at three locations (SD/MN, NC, WI). Women recalled immunizations at first pregnancy visit and at 16–17 and 36 weeks’ gestation (NCS–MCL). The proportion of women with vaccine information obtainable from each data source was determined, and proportions immunized as determined using different data sources were compared. IIS data were available for 82 %, MRA for 97 %, and NCS–MCL for 93 % of women. No mention of either vaccine occurred in 29 % (range 4–48 %) of IIS, 40 % of MRA (25–59 %), and 59 % (43–82 %) in NCS–MCL. Best agreement between sources was 2009 H1N1 vaccine in MRA versus IIS [kappa (95 % CI) of 0.44 (0.32–0.55)], with poorest agreement for FLU in IIS versus NCS–MCL [0.11 (−0.03 to 0.25)]. IIS was the most sensitive method for identifying women receiving 2009 H1N1 vaccine (92 %); MRA was most sensitive for FLU vaccine (81 %). IIS provided the most complete and sensitive data for 2009 H1N1 immunizations and MRA the most complete and sensitive data for FLU; IIS data were available for a smaller percent of population than MRA. NCS–MCL was the least sensitive method for identifying vaccinated women. PMID:23793534

  17. Assessment of extracranial-intracranial bypass in Moyamoya disease using 3T time-of-flight MR angiography: comparison with CT angiography.

    PubMed

    Chen, Qian; Qi, Rongfeng; Cheng, Xiaoqing; Zhou, Changsheng; Luo, Song; Ni, Ling; Huang, Wei

    2014-07-01

    To evaluate the value of time-of-flight MR angiography (TOF MRA) for the assessment of extracranial-intracranial (EC-IC) bypass in Moyamoya disease in comparison with computed tomography angiography (CTA). A consecutive series of 23 patients with Moyamoya disease were analyzed retrospectively. Twenty three patients underwent 25 procedures of extracranial-intracranial bypass. Cranial CTA was performed within one week after the surgery to assess bypass patency. Then TOF MRA was scanned within 24 h after CTA on a 3T MRI system. Using 5-point scales (0 = poor to 4 = excellent), two radiologists rated the image quality and vessel integrity of bypass for three segments (extracranial, trepanation, intracranial). Image quality was high in both CTA and TOF MRA (mean quality score 3.84 ± 0.37 and 3.8 ± 0.41), without statistical difference (p = 0.66). Mean scores of TOF MRA with respect to bypass visualization were higher than CTA in the intracranial segment (p = 0.026). No significant difference of bypass visualization regarding the extracranial and trepanation segments was found between TOF MRA and CTA (p = 0.66 and p = 0.34, respectively). For the trepanation segment, TOF MRA showed pseudo lesions in 2 of all 25 cases. 3T TOF MRA, a non-contrast technique not exposing the patients to radiation, proved to be at least equal to CTA for the assessment of EC-IC bypass, and even superior to CTA with respect to the intracranial segment. In addition, readers should be aware of a potential overestimation showing focal pseudo lesions of the bypass at the trepanation segment in TOF MRA.

  18. Magnetic resonance angiography in children with sickle cell disease and abnormal transcranial Doppler ultrasonography findings enrolled in the STOP study.

    PubMed

    Abboud, Miguel R; Cure, Joel; Granger, Suzanne; Gallagher, Dianne; Hsu, Lewis; Wang, Winfred; Woods, Gerald; Berman, Brian; Brambilla, Don; Pegelow, Charles; Lewin, Jonathan; Zimmermann, Robert A; Adams, Robert J

    2004-04-01

    The stroke prevention study in sickle cell disease (STOP) demonstrated a 90% reduction in stroke risk with transfusion among patients with time-averaged mean cerebral blood velocity (TAMV) of 200 cm/s or more as measured by transcranial Doppler (TCD). In STOP, 232 brain magnetic resonance angiograms (MRAs) were performed on 100 patients, 47 in the transfusion arm and 53 in the standard care arm. Baseline MRA findings were interpreted as normal in 75 patients and as indicating mild stenosis in 4 patients and severe stenosis in 21 patients. Among 35 patients who underwent magnetic resonance angiography within 30 days of random assignment, the TAMV was significantly higher in 7 patients with severe stenosis compared with 28 patients with normal MRA findings or mild stenosis (276.7 +/- 34 vs 215 +/- 15.6 cm/s; P<.001). In the standard care arm, 4 of 13 patients with abnormal MRA findings had strokes compared with 5 of 40 patients with normal MRA findings (P=.03). In this arm, TAMV became normal (less than 170 cm/s) or conditional (170-199 cm/s) in 26 of 38 patients with normal or mildly abnormal baseline MRA but remained abnormal in 8 of 10 patients with severely abnormal baseline MRA. These results suggest that TCD often detects flow abnormalities indicative of stroke risk before MRA lesions become evident. Furthermore, patients with abnormal MRA findings and higher TCD velocities are at higher risk for stroke, and their cerebral TAMVs are unlikely to decrease without transfusion.

  19. Final Environmental Assessment For Proposed Family Campground Expansion Maxwell Air Force Base, Montgomery County, Alabama

    DTIC Science & Technology

    2013-03-27

    surface soil , subsurface soil , surface water, sediment , and groundwater were identified as potential exposure media in the CSE Phase I ICSMs. No... soil , subsurface soil , surface water, and sediment were sampled to evaluate the potential impacts of lead and PAHs at the MRA. The MRA was divided...Lighting Auxiliary Generator UST-Bidg. 668 (Old BX Service Station) 1100 Area Base Fuel Farm AVGAS Distribution System Legend (IDIRPSites

  20. Vessel segmentation in 4D arterial spin labeling magnetic resonance angiography images of the brain

    NASA Astrophysics Data System (ADS)

    Phellan, Renzo; Lindner, Thomas; Falcão, Alexandre X.; Forkert, Nils D.

    2017-03-01

    4D arterial spin labeling magnetic resonance angiography (4D ASL MRA) is a non-invasive and safe modality for cerebrovascular imaging procedures. It uses the patient's magnetically labeled blood as intrinsic contrast agent, so that no external contrast media is required. It provides important 3D structure and blood flow information but a sufficient cerebrovascular segmentation is important since it can help clinicians to analyze and diagnose vascular diseases faster, and with higher confidence as compared to simple visual rating of raw ASL MRA images. This work presents a new method for automatic cerebrovascular segmentation in 4D ASL MRA images of the brain. In this process images are denoised, corresponding image label/control image pairs of the 4D ASL MRA sequences are subtracted, and temporal intensity averaging is used to generate a static representation of the vascular system. After that, sets of vessel and background seeds are extracted and provided as input for the image foresting transform algorithm to segment the vascular system. Four 4D ASL MRA datasets of the brain arteries of healthy subjects and corresponding time-of-flight (TOF) MRA images were available for this preliminary study. For evaluation of the segmentation results of the proposed method, the cerebrovascular system was automatically segmented in the high-resolution TOF MRA images using a validated algorithm and the segmentation results were registered to the 4D ASL datasets. Corresponding segmentation pairs were compared using the Dice similarity coefficient (DSC). On average, a DSC of 0.9025 was achieved, indicating that vessels can be extracted successfully from 4D ASL MRA datasets by the proposed segmentation method.

  1. Direct Assessment of Wall Shear Stress by Signal Intensity Gradient from Time-of-Flight Magnetic Resonance Angiography

    PubMed Central

    Lee, Sang Hyuk; Ryu, Han Uk; Park, Se-Hyoung; Chung, Gyung-Ho; Cho, Young I.

    2017-01-01

    The aim of the study was to calculate the arterial wall signal intensity gradient (SIG) from time-of-flight MR angiography (TOF-MRA) and represent arterial wall shear stress. We developed a new algorithm that uses signal intensity (SI) of a TOF-MRA to directly calculate the signal intensity gradient (SIG). The results from our phantom study showed that the TOF-MRA SIG could be used to distinguish the magnitude of blood flow rate as high (mean SIG ± SD, 2.2 ± 0.4 SI/mm for 12.5 ± 2.3 L/min) and low (0.9 ± 0.3 SI/mm for 8.5 ± 2.6 L/min) in vessels (p < 0.001). Additionally, we found that the TOF-MRA SIG values were highly correlated with various flow rates (β = 0.96, p < 0.001). Remarkably, the correlation coefficient between the WSS obtained from the computational fluid dynamics (CFD) analysis and the TOF-MRA SIG was greater than 0.8 in each section at the carotid artery (p < 0.001 for all β values). This new technique using TOF-MRA could enable the rapid calculation of the TOF-MRA SIG and thereby the WSS. Thus, the TOF-MRA SIG can provide clinicians with an accurate and efficient screening method for making rapid decisions on the risk of vascular disease for a patient in clinical practice. PMID:28900625

  2. Direct Assessment of Wall Shear Stress by Signal Intensity Gradient from Time-of-Flight Magnetic Resonance Angiography.

    PubMed

    Han, Kap-Soo; Lee, Sang Hyuk; Ryu, Han Uk; Park, Se-Hyoung; Chung, Gyung-Ho; Cho, Young I; Jeong, Seul-Ki

    2017-01-01

    The aim of the study was to calculate the arterial wall signal intensity gradient (SIG) from time-of-flight MR angiography (TOF-MRA) and represent arterial wall shear stress. We developed a new algorithm that uses signal intensity (SI) of a TOF-MRA to directly calculate the signal intensity gradient (SIG). The results from our phantom study showed that the TOF-MRA SIG could be used to distinguish the magnitude of blood flow rate as high (mean SIG ± SD, 2.2 ± 0.4 SI/mm for 12.5 ± 2.3 L/min) and low (0.9 ± 0.3 SI/mm for 8.5 ± 2.6 L/min) in vessels (p < 0.001). Additionally, we found that the TOF-MRA SIG values were highly correlated with various flow rates (β = 0.96, p < 0.001). Remarkably, the correlation coefficient between the WSS obtained from the computational fluid dynamics (CFD) analysis and the TOF-MRA SIG was greater than 0.8 in each section at the carotid artery (p < 0.001 for all β values). This new technique using TOF-MRA could enable the rapid calculation of the TOF-MRA SIG and thereby the WSS. Thus, the TOF-MRA SIG can provide clinicians with an accurate and efficient screening method for making rapid decisions on the risk of vascular disease for a patient in clinical practice.

  3. Non-Enhanced MR Imaging of Cerebral Arteriovenous Malformations at 7 Tesla.

    PubMed

    Wrede, Karsten H; Dammann, Philipp; Johst, Sören; Mönninghoff, Christoph; Schlamann, Marc; Maderwald, Stefan; Sandalcioglu, I Erol; Ladd, Mark E; Forsting, Michael; Sure, Ulrich; Umutlu, Lale

    2016-03-01

    To evaluate prospectively 7 Tesla time-of-flight (TOF) magnetic resonance angiography (MRA) and 7 Tesla non-contrast-enhanced magnetization-prepared rapid acquisition gradient-echo (MPRAGE) for delineation of intracerebral arteriovenous malformations (AVMs) in comparison to 1.5 Tesla TOF MRA and digital subtraction angiography (DSA). Twenty patients with single or multifocal AVMs were enrolled in this trial. The study protocol comprised 1.5 and 7 Tesla TOF MRA and 7 Tesla non-contrast-enhanced MPRAGE sequences. All patients underwent an additional four-vessel 3D DSA. Image analysis of the following five AVM features was performed individually by two radiologists on a five-point scale: nidus, feeder(s), draining vein(s), relationship to adjacent vessels, and overall image quality and presence of artefacts. A total of 21 intracerebral AVMs were detected. Both sequences at 7 Tesla were rated superior over 1.5 Tesla TOF MRA in the assessment of all considered AVM features. Image quality at 7 Tesla was comparable with DSA considering both sequences. Inter-observer accordance was good to excellent for the majority of ratings. This study demonstrates excellent image quality for depiction of intracerebral AVMs using non-contrast-enhanced 7 Tesla MRA, comparable with DSA. Assessment of untreated AVMs is a promising clinical application of ultra-high-field MRA. • Non-contrast-enhanced 7 Tesla MRA demonstrates excellent image quality for intracerebral AVM depiction. • Image quality at 7 Tesla was comparable with DSA considering both sequences. • Assessment of intracerebral AVMs is a promising clinical application of ultra-high-field MRA.

  4. Endothelin-1 and endothelin-2 initiate and maintain contractile responses by different mechanisms in rat mesenteric and cerebral arteries

    PubMed Central

    Compeer, M G; Janssen, G M J; De Mey, J G R

    2013-01-01

    BACKGROUND AND PURPOSE Endothelin (ET)-1 and ET-2 cause potent long-lasting vasoconstrictions by tight binding to smooth muscle ETA receptors. We tested the hypotheses that different mechanisms mediate initiation and maintenance of arterial contractile responses to ET-1 and ET-2 and that this differs among vascular beds. EXPERIMENTAL APPROACH Segments of rat mesenteric resistance artery (MRA) and basilar artery (BA) were studied in wire myographs with and without functional antagonists. KEY RESULTS Sensitivity and maximum of MRA contractile responses to ET-1 were not, or only moderately, reduced by stimulation of soluble GC, AC or K+-channels and by an inhibitor of receptor-operated ion channels. However, each of these reduced maintenance of ET-1 effects and relaxed ET-1-induced contractions in MRA. A calcium channel antagonist did not alter sensitivity, maximum and maintenance of ET-1 effects, but relaxed ET-1-induced contractions in MRA. A PLC inhibitor prevented contractile responses to ET-1 and ET-2 in MRA and BA, and relaxed ET-1- and ET-2-induced responses in MRA and ET-1 effects in BA. A Rho-kinase inhibitor did not modify sensitivity, maximum and maintenance of responses to both peptides in both arteries but relaxed ET-2, but not ET-1, effects in MRA and ET-1 effects in BA. CONCLUSIONS AND IMPLICATIONS PLC played a key role in arterial contractile responses to ETs, but ET-1 and ET-2 initiated and maintained vasoconstriction through different mechanisms, and these differed between MRA and BA. Selective functional antagonism may be considered for agonist- and vascular bed selective pharmacotherapy of ET-related diseases. PMID:23941276

  5. Non-contrast-enhanced 4D MR angiography with STAR spin labeling and variable flip angle sampling: a feasibility study for the assessment of Dural Arteriovenous Fistula.

    PubMed

    Jang, Jinhee; Schmitt, Peter; Kim, Bom-yi; Choi, Hyun Seok; Jung, So-Lyung; Ahn, Kook-Jin; Kim, Inseong; Paek, Munyoung; Kim, Bum-soo

    2014-04-01

    This study aimed to evaluate the feasibility of non-contrast-enhanced 4D magnetic resonance angiography (NCE 4D MRA) with signal targeting with alternative radiofrequency (STAR) spin labeling and variable flip angle (VFA) sampling in the assessment of dural arteriovenous fistula (DAVF) in the transverse sinus. Nine patients underwent NCE 4D MRA for the evaluation of DAVF in the transverse sinus at 3 T. One patient was examined twice, once before and once after the interventional treatment. All patients also underwent digital subtraction angiography (DSA) and/or contrast-enhanced magnetic resonance angiography (CEMRA). For the acquisition of NCE 4D MRA, a STAR spin tagging method was used, and a VFA sampling was applied in the data readout module instead of a constant flip angle. Two readers evaluated the NCE 4D MRA data for the diagnosis of DAVF and its type with consensus. The results were compared with those from DSA and/or CEMRA. All patients underwent NCE 4D MRA without any difficulty. Among seven patients with patent DAVFs, all cases showed an early visualization of the transverse sinus on NCE 4D MRA. Except for one case, the type of DAVF of NCE 4D MRA was agreed with that of reference standard study. Cortical venous reflux (CVR) was demonstrated in two cases out of three patients with CVR. NCE 4D MRA with STAR tagging and VFA sampling is technically and clinically feasible and represents a promising technique for assessment of DAVF in the transverse sinus. Further technical developments should aim at improvements of spatial and temporal coverage.

  6. Accelerated noncontrast-enhanced 4-dimensional intracranial MR angiography using golden-angle stack-of-stars trajectory and compressed sensing with magnitude subtraction.

    PubMed

    Zhou, Ziwu; Han, Fei; Yu, Songlin; Yu, Dandan; Rapacchi, Stanislas; Song, Hee Kwon; Wang, Danny J J; Hu, Peng; Yan, Lirong

    2017-05-07

    To evaluate the feasibility and performance of compressed sensing (CS) with magnitude subtraction regularization in accelerating non-contrast-enhanced dynamic intracranial MR angiography (NCE-dMRA). A CS algorithm was introduced in NCE-dMRA by exploiting the sparsity of the magnitude difference of the control and label images. The NCE-dMRA data were acquired using golden-angle stack-of-stars trajectory on six healthy volunteers and one patient with arteriovenous fistula. Images were reconstructed using (i) the proposed magnitude-subtraction CS (MS-CS); (ii) complex-subtraction CS; (iii) independent CS; and (iv) view-sharing with k-space weighted image contrast (KWIC). The dMRA image quality was compared across the four reconstruction strategies. The proposed MS-CS method was further compared with KWIC for temporal fidelity of depicting dynamic flow. The proposed MS-CS method was able to reconstruct NCE-dMRA images with detailed vascular structures and clean background. It provided better subjective image quality than the other two CS strategies (P < 0.05). Compared with KWIC, MS-CS showed similar image quality, but reduced temporal blurring in delineating the fine distal arteries. The MS-CS method is a promising CS technique for accelerating NCE-dMRA acquisition without compromising image quality and temporal fidelity. Magn Reson Med, 2017. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  7. Pulmonary vein imaging: comparison of 3D magnetic resonance angiography with 2D cine MRI for characterizing anatomy and size.

    PubMed

    Syed, Mushabbar A; Peters, Dana C; Rashid, Haroon; Arai, Andrew E

    2005-01-01

    Pulmonary vein imaging is integral for planning atrial fibrillation ablation procedures. We tested the feasibility of quantifying pulmonary vein ostial diameter using two-dimensional cine cardiac magnetic resonance (2D cine CMR) and three-dimensional magnetic resonance angiography (3D MRA). Nine patients with a history of atrial fibrillation and 20 normal volunteers underwent 2D cine CMR and contrast-enhanced 3D MRA of pulmonary veins on a 1.5 T scanner. Pulmonary vein ostial diameters were measured and pulmonary vein vessel border sharpness was graded qualitatively. Both techniques provided excellent pulmonary vein imaging; however, 3D MRA was faster to perform. The average difference between the systolic and diastolic pulmonary vein diameter was 2.5 mm (23.2%, p < 0.0001) in normal volunteers and 2.2 mm (16.9%, p < 0.0001) in atrial fibrillation patients. The ostial diameter measurements by 3D MRA were significantly larger than on 2D cine CMR. Additionally, the pulmonary vein borders appeared sharper with 2D cine CMR compared to 3D MRA. In conclusion, the 2D images can resolve differences in diameter across the cardiac cycle, while the 3D images provide high quality anatomical depiction but blur borders due to pulsatile motion. We suggest a protocol combining 2D cine CMR and 3D MRA for comprehensive evaluation of pulmonary veins.

  8. Carotid Artery Stenosis: Comparison of 3D Time-of-Flight MR Angiography and Contrast-Enhanced MR Angiography at 3T.

    PubMed

    Platzek, Ivan; Sieron, Dominik; Wiggermann, Philipp; Laniado, Michael

    2014-01-01

    Purpose. The aim of this study was to assess the correlation of 3D time-of-flight MR angiography (TOF MRA) and contrast-enhanced MR angiography (CEMRA) for carotid artery stenosis evaluation at 3T. Material and Methods. Twenty-three patients (5 f, 18 m; mean age 61 y, age range 45-78 y) with internal carotid artery stenosis detected with ultrasonography were examined on a 3.0T MR system. The MR examination included both 3D TOF MRA and CEMRA of the carotid arteries. MR images were evaluated independently by two board-certified radiologists. Stenosis evaluation was based on a five-point scale. Stenosis grades determined by TOF and CEMRA were compared using Spearman's rank correlation coefficient and the Wilcoxon test. Cohen's Kappa was used to evaluate interrater reliability. Results. CEMRA detected stenosis in 24 (52%) of 46 carotids evaluated, while TOF detected stenosis in 27 (59%) of 46 carotids. TOF MRA yielded significantly higher results for stenosis grade in comparison to CEMRA (P = 0.014). Interrater agreement was very good for both TOF MRA (κ = 0.93) and CEMRA (κ = 0.93). Conclusion. At 3T, 3D TOF MRA should not be used as replacement for contrast-enhanced MRA of the carotid arteries, as it results in significantly higher stenosis grades.

  9. Carotid Artery Stenosis: Comparison of 3D Time-of-Flight MR Angiography and Contrast-Enhanced MR Angiography at 3T

    PubMed Central

    Sieron, Dominik; Wiggermann, Philipp; Laniado, Michael

    2014-01-01

    Purpose. The aim of this study was to assess the correlation of 3D time-of-flight MR angiography (TOF MRA) and contrast-enhanced MR angiography (CEMRA) for carotid artery stenosis evaluation at 3T. Material and Methods. Twenty-three patients (5 f, 18 m; mean age 61 y, age range 45–78 y) with internal carotid artery stenosis detected with ultrasonography were examined on a 3.0T MR system. The MR examination included both 3D TOF MRA and CEMRA of the carotid arteries. MR images were evaluated independently by two board-certified radiologists. Stenosis evaluation was based on a five-point scale. Stenosis grades determined by TOF and CEMRA were compared using Spearman's rank correlation coefficient and the Wilcoxon test. Cohen's Kappa was used to evaluate interrater reliability. Results. CEMRA detected stenosis in 24 (52%) of 46 carotids evaluated, while TOF detected stenosis in 27 (59%) of 46 carotids. TOF MRA yielded significantly higher results for stenosis grade in comparison to CEMRA (P = 0.014). Interrater agreement was very good for both TOF MRA (κ = 0.93) and CEMRA (κ = 0.93). Conclusion. At 3T, 3D TOF MRA should not be used as replacement for contrast-enhanced MRA of the carotid arteries, as it results in significantly higher stenosis grades. PMID:24778875

  10. Technical Aspects of Contrast-enhanced MR Angiography: Current Status and New Applications.

    PubMed

    Riederer, Stephen J; Stinson, Eric G; Weavers, Paul T

    2017-08-31

    This article is based on a presentation at the meeting of the Japanese Society of Magnetic Resonance in Medicine in September 2016. The purpose is to review the technical developments which have contributed to the current status of contrast-enhanced magnetic resonance angiography (CE-MRA) and to indicate related emerging areas of study. Technical developments include magnetic resonance imaging (MRI) physics-based innovations as well as improvements in MRI engineering. These have collectively addressed not only early issues of timing and venous suppression but more importantly have led to an improvement in spatiotemporal resolution of CE-MRA of more than two orders of magnitude compared to early results. This has allowed CE-MRA to be successfully performed in virtually all vascular territories of the body. Contemporary technical areas of study include improvements in implementation of high rate acceleration, extension of high performance first-pass CE-MRA across multiple imaging stations, expanded use of compressive sensing techniques, integration of Dixon-based fat suppression into CE-MRA sequences, and application of CE-MRA sequences to dynamic-contrast-enhanced perfusion imaging.

  11. Carotid ultrasound for pulmonary arteriovenous malformation screening

    PubMed Central

    Schneider, Günther; Maßmann, Alexander; Gräber, Stefan; Geisthoff, Urban W.

    2015-01-01

    Objective In patients with hereditary hemorrhagic telangiectasia (HHT), pulmonary arteriovenous malformations (PAVMs) can cause serious neurological complications. Our aim was to evaluate the potential of contrast-enhanced Doppler ultrasound (CE-US) of the common carotid artery as a screening test for detection of PAVMs. Methods A total of 124 consecutive patients with HHT or a positive family history underwent screening for PAVMs with CE-US and thoracic contrast-enhanced magnetic resonance angiography (CE-MRA). CE-US was performed after receiving (D)-galactose microparticulate, and CE-MRA with gadobenate dimeglumine. Twenty-five patients with confirmed PAVMs were referred to conventional pulmonary catheter angiography (PA). Findings on CE-US and CE-MRA were evaluated using contingency tables and McNemar’s test. Results Using CE-MRA as the reference test, CE-US had a sensitivity of 100%, a specificity of 87%, and a negative predictive value of 100%. In 25 patients who underwent PA, PAVMs that had been diagnosed on CE-US and CE-MRA were confirmed. Of the PAVMs detected by CE-MRA, 24% were not identified on PA. Conclusion CE-US is a simple, minimally invasive screening method that can easily be performed in different settings. CE-US can predict PAVMs with high probability of success. CE-US may be a simple alternative to transthoracic echocardiography in the assessment of PAVMs in certain HHT-patients. PMID:28352707

  12. Arterial-phase three-dimensional gadolinium magnetic resonance angiography of the renal arteries. Strategies for timing and contrast media injection: original investigation.

    PubMed

    Schoenberg, S O; Knopp, M V; Prince, M R; Londy, F; Knopp, M A

    1998-09-01

    The authors review different imaging and contrast-media infusion strategies for arterial-phase three-dimensional (3D) gadolinium-enhanced magnetic resonance angiography (Gd-MRA). The influence of physicochemical factors on the infusion of contrast media, including viscosity, flow rate, inline pressure, and cannula size, is assessed. The combination of manual or automated contrast-media administration with timing-dependent or -independent 3D Gd-MRA techniques is reviewed regarding the aspects of effectiveness, robustness, image quality, and costs. For effective bolus delivery with high flow rates, the type and temperature of the contrast media, the size of the cannula, and an immediate saline flush must be considered. Timing-dependent techniques based on a test bolus and using automated contrast-media infusion as well as timing independent techniques such as MR SmartPrep or multiphase 3D Gd-MRA by using a manual injection with a SmartSet tubing set, are all effective procedures for arterial phase 3D Gd-MRA. Manual contrast-media injection with a tubing set can be used for timing-independent MRA techniques. The multiphase 3D Gd-MRA approach seems to be favorable for different MR systems, robustness, and speed.

  13. 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.

  14. Computed tomography and magnetic resonance angiography in the evaluation of aberrant origin of the external carotid artery branches.

    PubMed

    Cappabianca, Salvatore; Scuotto, Assunta; Iaselli, Francesco; Pignatelli di Spinazzola, Nicoletta; Urraro, Fabrizio; Sarti, Giuseppe; Montemarano, Marcella; Grassi, Roberto; Rotondo, Antonio

    2012-07-01

    Aim of our study was to evaluate the prevalence of aberrant origin of the branches of the external carotid artery (ECA) in 97 patients by computed tomography (CTA) and magnetic resonance angiography (MRA) and to compare the accuracy of these two techniques in the visualization of the ECA system. All patients underwent CTA and MRA examination of the head and neck. Multiplanar and volumetric reformations were obtained in all cases. For each set of images, the presence of aberrant origin of the branches of the external carotid artery was investigated. MRA and CTA images of each patient were compared to define their information content. Anatomical anomalies were found in 88 heminecks, with a prevalence of 53.3%. In the 61 patients in whom the CTA was performed before the MRA, the latter method showed only 92% of abnormalities detected at the first examination; in the 36 patients in whom MRA was performed first, CTA identified all of the anomalies highlighted by the former, adding 12 new. Knowledge of the anomalies of origin of the ECA branches is essential for the head and neck surgeon; the high prevalence of anomalies found in our series as in the previous studies indicates the opportunity to perform a CTA or a MRA of the head and neck before any surgical or interventional procedure. CTA is the method of choice in the evaluation of anomalies of origin of the branches of the ECA and in the definition of their course.

  15. Magnetic resonance angiography with midsagittal saturation for the assessment of blood flow from superficial temporal artery-to-middle cerebral artery bypass.

    PubMed

    Akashi, Toshiaki; Taoka, Toshiaki; Miyasaka, Toshiteru; Myochin, Kaoru; Sakamoto, Masahiko; Takayama, Katsutoshi; Nakagawa, Hiroyuki; Kichikawa, Kimihiko

    2010-01-01

    The purpose of this study was to evaluate the feasibility of magnetic resonance angiography (MRA) with midsagittal saturation for depiction of superficial temporal artery-to-middle cerebral artery bypass flow. Eleven patients undergoing bypass surgery in 13 regions were examined by external carotid artery angiography (ECAG) and 3-dimensional time-of-flight MRA with saturation pulse applied to the midsagittal plane covering the internal carotid arteries. We classified the extent of visualization of bypass flow into 4 types and examined the agreement of findings between them. The MRA revealed types of bypass flow in agreement with those observed on ECAG in 10 of the 13 regions. The MRA underestimated bypass flow in 2 regions and overestimated it in 1 region. The MRA with midsagittal saturation demonstrated bypass flow in agreement with ECAG in most cases. Application of MRA with midsagittal saturation permits noninvasive assessment of physiological flow from superficial temporal artery-to-middle cerebral artery bypass for a postoperative follow-up.

  16. Magnetic resonance imaging in children presenting migraine with aura: Association of hypoperfusion detected by arterial spin labelling and vasospasm on MR angiography findings.

    PubMed

    Cadiot, Domitille; Longuet, Romain; Bruneau, Bertrand; Treguier, Catherine; Carsin-Vu, Aline; Corouge, Isabelle; Gomes, Constantin; Proisy, Maïa

    2017-01-01

    Objective A child presenting with a first attack of migraine with aura usually undergoes magnetic resonance imaging (MRI) to rule out stroke. The purpose of this study was to report vascular and brain perfusion findings in children suffering from migraine with aura on time-of-flight MR angiography (TOF-MRA) and MR perfusion imaging using arterial spin labelling (ASL). Methods We retrospectively included all children who had undergone an emergency MRI examination with ASL and TOF-MRA sequences for acute neurological deficit and were given a final diagnosis of migraine with aura. The ASL perfusion maps and TOF-MRA images were independently assessed by reviewers blinded to clinical data. A mean cerebral blood flow (CBF) value was obtained for each cerebral lobe after automatic data post-processing. Results Seventeen children were finally included. Hypoperfusion was identified in one or more cerebral lobes on ASL perfusion maps by visual assessment in 16/17 (94%) children. Vasospasm was noted within the intracranial vasculature on the TOF-MRA images in 12/17 (71%) children. All (100%) of the abnormal TOF-MRA images were associated with homolateral hypoperfusion. Mean CBF values were significantly lower ( P < 0.05) in visually hypoperfused lobes than in normally perfused lobes. Conclusion ASL and TOF-MRA are two totally non-invasive, easy-to-use MRI sequences for children in emergency settings. Hypoperfusion associated with homolateral vasospasm may suggest a diagnosis of migraine with aura.

  17. Effect of Spironolactone on Plasma Apelin-12 Levels in Patients with Chronic Systolic Heart Failure.

    PubMed

    Topuz, Mustafa; Cosgun, Mehmet; Akkuş, Oğuz; Bulut, Atilla; Sen, Omer; Topuz, Ayşe Nur; Caylı, Murat

    2016-11-01

    The aim of this study was to determine whether spironolactone therapy has an effect on serum apelin-12 levels in heart failure with reduced ejection fraction (HFrEF) patients. Eighty outpatients previously diagnosed with HFrEF were enrolled in the current study. Included patients were taking only standard heart failure therapy (ST) (angiotensin converting enzyme or angiotensin receptor blocker, beta-blockers, loop diuretics and anticoagulant or antiagregan agents) without a mineralocorticoid receptor antagonists (MRA) because of its side effects, and were designated the non-MRA group; those patients taking 25 mg/daily spironolactone in addition to the ST were deemed the MRA group. Patient blood samples were collected to measure serum apelin-12 levels. After adjustment for all clinical and demographic factors, plasma apelin-12 levels were significantly higher and NT pro-BNP levels were significantly lower in the MRA group compared to the non-MRA group (p < 0.001, p < 0.001; respectively). In multiple linear regression analyses, there was no association between baseline apelin-12 level and clinical parameters. MRA using initial apelin-12 levels were lower and NT pro-BNP levels were higher in patients with stricken event than in event-free patients (p = 0.042, p < 0.001, and p < 0.001; respectively). Blocking the aldosterone receptors by spironolactone, in addition to maximal standard therapy, may increase serum apelin-12 levels among patients with HFrEF.

  18. 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. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. 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.

  20. Use of microbial risk assessment to inform the national estimate of acute gastrointestinal illness attributable to microbes in drinking water.

    PubMed

    Soller, Jeffrey A

    2006-01-01

    Microbial risk assessment (MRA) evaluates the likelihood of adverse human health effects that occur following exposure to pathogenic microorganisms. This paper focuses on the potential use of MRA to provide insight to the national estimate of acute gastrointestinal illness (AGI) in the United States among persons served by public water systems. This article defines MRA, describes how MRA is implemented, provides an overview of the field of MRA and discusses how MRA may be useful for characterizing the national estimate. Communities served by drinking water systems with relatively contaminated source waters, sub-standard treatment facilities, and/or contamination problems in their distribution systems are subject to higher risks than communities where such issues are less of a concern. Further, the risk of illness attributable to pathogens in drinking water in each community can be thought of as the sum of the risk from the treated drinking water and the risk from the distribution system. Pathogen-specific MRAS could be developed to characterize the risk associated with each of these components; however, these assessments are likely to under-estimate the total risk from all pathogens attributable to drinking water. Potential methods for developing such MRAs are discussed along with their associated limitations.

  1. Neither fixed nor random: weighted least squares meta-regression.

    PubMed

    Stanley, T D; Doucouliagos, Hristos

    2017-03-01

    Our study revisits and challenges two core conventional meta-regression estimators: the prevalent use of 'mixed-effects' or random-effects meta-regression analysis and the correction of standard errors that defines fixed-effects meta-regression analysis (FE-MRA). We show how and explain why an unrestricted weighted least squares MRA (WLS-MRA) estimator is superior to conventional random-effects (or mixed-effects) meta-regression when there is publication (or small-sample) bias that is as good as FE-MRA in all cases and better than fixed effects in most practical applications. Simulations and statistical theory show that WLS-MRA provides satisfactory estimates of meta-regression coefficients that are practically equivalent to mixed effects or random effects when there is no publication bias. When there is publication selection bias, WLS-MRA always has smaller bias than mixed effects or random effects. In practical applications, an unrestricted WLS meta-regression is likely to give practically equivalent or superior estimates to fixed-effects, random-effects, and mixed-effects meta-regression approaches. However, random-effects meta-regression remains viable and perhaps somewhat preferable if selection for statistical significance (publication bias) can be ruled out and when random, additive normal heterogeneity is known to directly affect the 'true' regression coefficient. Copyright © 2016 John Wiley & Sons, Ltd.

  2. 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.

  3. Improved artery-vein separation with acceleration-dependent preparation for non-contrast-enhanced magnetic resonance angiography.

    PubMed

    Priest, Andrew Nicholas; Taviani, Valentina; Graves, Martin John; Lomas, David John

    2014-09-01

    To compare the use of acceleration-dependent and velocity-dependent flow-preparation for non-contrast-enhanced magnetic resonance angiography (NCE-MRA), investigating both image quality and the ability to discriminate between arteries and veins. We develop an acceleration-dependent NCE-MRA method known as acceleration dependent vascular anatomy for non-contrast-enhanced MRA (ADVANCE-MRA). Acceleration-dependent and velocity-dependent images were acquired using a constant and pulsatile flow-phantom and from the lower legs of six healthy volunteers and one patient with peripheral vascular disease. The volunteer images were assessed both by quantitative signal measurements and qualitative scoring by a radiologist. In the phantom, acceleration-dependent preparation depicted pulsatile but not constant flow, while velocity-dependent preparation depicted both. In the volunteers and the patient, the velocity-dependent preparation was unable to separate the arterial and venous signals completely, with some overlap of arterial and venous signals for all acquired flow sensitizations whereas the acceleration-dependent preparation gave complete artery-vein separation over a wide range of flow sensitizations. Acceleration-dependent preparation received the best overall qualitative scores for arterial image quality and venous contamination. Acceleration-dependent NCE-MRA improves arterial image quality and reduces venous contamination, compared with velocity-dependent NCE-MRA, and warrants further investigation in patients. Copyright © 2013 Wiley Periodicals, Inc.

  4. 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

  5. [Evaluation of cerebro-vascular diseases with persistent carotid-basilar anastomosis].

    PubMed

    Harada, K; Uozumi, T; Kurisu, K; Sumida, M; Nakahara, A; Migita, K

    1994-12-01

    Five cases of cerebro-vascular diseases with carotid-basilar anastomosis were evaluated. Case 1: a 73-year-old female was diagnosed as having subarachnoid hemorrhage due to a ruptured aneurysm of the right internal carotid artery-posterior communicating artery bifurcation and demonstrated that a left proatlantal intersegmental artery. Case 2: a 38-year-old female showed intraventricle hemorrhage due to arteriovenous malformation and showed left primitive hypoglossal artery. Case 3: 73-year-old female was diagnosed as having subarachnoid hemorrhage due to a ruptured basilar top aneurysm and demonstrated that a right primitive hypoglossal artery. Case 4: a 29-year-old male with unruptured aneurysm of the left internal carotid artery-posterior communicating artery bifurcation, and right trigeminal artery was detected incidentally by magnetic resonance angiography (MRA). Furthermore, right proatlantal intersegmental artery was detected by conventional angiography. Case 5: a 76-year-old male was diagnosed as having subarachnoid hemorrhage due to a ruptured aneurysm of the anterior communicating artery. MRA showed the aneurysm and a primitive trigeminal artery. No clinical symptom related with carotid-basilar anastomosis was detected. Magnetic resonance angiography (MRA) was useful for diagnosis of asymptomatic carotid-basilar anastomosis. Especially, axial view of MRA by time of flight method detected two cases of a primitive trigeminal artery. And coronal view of MRA by phase contrast method is useful for diagnosis of primitive proatlantal intersegmental artery. More asymptomatic persistent carotid-basilar anastomosis may be detected by MRA.

  6. The Diuretic Torasemide Does Not Prevent Aldosterone-Mediated Mineralocorticoid Receptor Activation in Cardiomyocytes

    PubMed Central

    Gravez, Basile; Tarjus, Antoine; Jimenez-Canino, Ruben; El Moghrabi, Soumaya; Messaoudi, Smail; de la Rosa, Diego Alvarez; Jaisser, Frederic

    2013-01-01

    Aldosterone binds to the mineralocorticoid receptor (MR) and exerts pleiotropic effects beyond enhancing renal sodium reabsorption. Excessive mineralocorticoid signaling is deleterious during the evolution of cardiac failure, as evidenced by the benefits provided by adding MR antagonists (MRA) to standard care in humans. In animal models of cardiovascular diseases, MRA reduce cardiac fibrosis. Interestingly diuretics such as torasemide also appear efficient to improve cardiovascular morbidity and mortality, through several mechanisms. Among them, it has been suggested that torasemide could block aldosterone binding to the MR. To evaluate whether torasemide acts as a MRA in cardiomyocytes, we compared its effects with a classic MRA such as spironolactone. We monitored ligand-induced nuclear translocation of MR-GFP and MR transactivation activity in the cardiac-like cell line H9C2 using a reporter gene assay and known endogenous aldosterone-regulated cardiac genes. Torasemide did not modify MR nuclear translocation. Aldosterone-induced MR transactivation activity was reduced by the MRA spironolactone, not by torasemide. Spironolactone blocked the induction by aldosterone of endogenous MR-responsive genes (Sgk-1, PAI-1, Orosomucoid-1, Rgs-2, Serpina-3, Tenascin-X), while torasemide was ineffective. These results show that torasemide is not an MR antagonist; its association with MRA in heart failure may however be beneficial, through actions on complementary pathways. PMID:24040049

  7. Predictors of success for mandibular repositioning appliance in obstructive sleep apnea syndrome.

    PubMed

    Cunha, Thays Crosara Abrahão; Guimarães, Thais de Moura; Schultz, Teresa Cristina Barros; Almeida, Fernanda Ribeiro de; Cunha, Thulio Marquez; Simamoto, Paulo Cezar; Bittencourt, Lia Rita Azeredo

    2017-06-05

    The characteristics of non-obese patients with mild to moderate Obstructive Sleep Apnea Syndrome (OSAS) who will present with a good response to Mandibular Repositioning Appliance (MRA) treatment have not yet been well established in the literature. The aim of this study is to assess whether polysomnographic (PSG), demographic, anthropometric, cephalometric, and otorhinolaryngological parameters predict MRA success in the treatment of OSAS. Forty (40) males with mild and moderate OSAS were assessed pretreatment and 2-months post-treatment after wearing an MRA. Demographic, anthropometric, otorhinolaryngological (ENT), cephalometric, and polysomnographic parameters, including continuous positive airway pressure (CPAP) titrated pressure, dental models, Epworth Sleepiness Scale, quality of life (Short Form SF-36), and mood state (Profile of Mood States - POMS), were assessed. The responders exhibited fewer oropharyngeal alterations, increased upper pharyngeal space, reduced lower airway space, and increased mandibular intercanine width, and they had milder disease. Nevertheless, no predictive factors of MRA success could be found. MRA was more successful among men with a more pervious airway, a larger interdental width and milder OSAS. However, a combined [1] functional and structural assessment is needed to successfully predict the [2] effectiveness of MRA treatment of OSA.

  8. Effect of Spironolactone on Plasma Apelin-12 Levels in Patients with Chronic Systolic Heart Failure

    PubMed Central

    Topuz, Mustafa; Cosgun, Mehmet; Akkuş, Oğuz; Bulut, Atilla; Sen, Omer; Topuz, Ayşe Nur; Caylı, Murat

    2016-01-01

    Background The aim of this study was to determine whether spironolactone therapy has an effect on serum apelin-12 levels in heart failure with reduced ejection fraction (HFrEF) patients. Methods Eighty outpatients previously diagnosed with HFrEF were enrolled in the current study. Included patients were taking only standard heart failure therapy (ST) (angiotensin converting enzyme or angiotensin receptor blocker, beta-blockers, loop diuretics and anticoagulant or antiagregan agents) without a mineralocorticoid receptor antagonists (MRA) because of its side effects, and were designated the non-MRA group; those patients taking 25 mg/daily spironolactone in addition to the ST were deemed the MRA group. Patient blood samples were collected to measure serum apelin-12 levels. Results After adjustment for all clinical and demographic factors, plasma apelin-12 levels were significantly higher and NT pro-BNP levels were significantly lower in the MRA group compared to the non-MRA group (p < 0.001, p < 0.001; respectively). In multiple linear regression analyses, there was no association between baseline apelin-12 level and clinical parameters. MRA using initial apelin-12 levels were lower and NT pro-BNP levels were higher in patients with stricken event than in event-free patients (p = 0.042, p < 0.001, and p < 0.001; respectively). Conclusions Blocking the aldosterone receptors by spironolactone, in addition to maximal standard therapy, may increase serum apelin-12 levels among patients with HFrEF. PMID:27899856

  9. Stringent mating-type-regulated auxotrophy increases the accuracy of systematic genetic interaction screens with Saccharomyces cerevisiae mutant arrays.

    PubMed

    Singh, Indira; Pass, Rebecca; Togay, Sine Ozmen; Rodgers, John W; Hartman, John L

    2009-01-01

    A genomic collection of haploid Saccharomyces cerevisiae deletion strains provides a unique resource for systematic analysis of gene interactions. Double-mutant haploid strains can be constructed by the synthetic genetic array (SGA) method, wherein a query mutation is introduced by mating to mutant arrays, selection of diploid double mutants, induction of meiosis, and selection of recombinant haploid double-mutant progeny. The mechanism of haploid selection is mating-type-regulated auxotrophy (MRA), by which prototrophy is restricted to a particular haploid genotype generated only as a result of meiosis. MRA escape leads to false-negative genetic interaction results because postmeiotic haploids that are supposed to be under negative selection instead proliferate and mate, forming diploids that are heterozygous at interacting loci, masking phenotypes that would be observed in a pure haploid double-mutant culture. This work identified factors that reduce MRA escape, including insertion of terminator and repressor sequences upstream of the MRA cassette, deletion of silent mating-type loci, and utilization of alpha-type instead of a-type MRA. Modifications engineered to reduce haploid MRA escape reduced false negative results in SGA-type analysis, resulting in >95% sensitivity for detecting gene-gene interactions.

  10. Contrast Enhanced Pulmonary Magnetic Resonance Angiography for Pulmonary Embolism: Building a Successful Program

    PubMed Central

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

    2016-01-01

    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. First-pass contrast-enhanced magnetic resonance angiography in humans using ferumoxytol, a novel ultrasmall superparamagnetic iron oxide (USPIO)-based blood pool agent.

    PubMed

    Li, Wei; Tutton, Sean; Vu, Anthony T; Pierchala, Linda; Li, Belinda S Y; Lewis, Jerome M; Prasad, Pottumarthi V; Edelman, Robert R

    2005-01-01

    To evaluate the feasibility of first-pass contrast-enhanced magnetic resonance angiography (MRA) using ferumoxytol in humans. First-pass and equilibrium phase MRA were performed using ferumoxytol in one healthy volunteer and 11 patients with a fast three-dimensional spoiled gradient recalled (SPGR) pulse sequence. The examined vessels included carotid arteries, thoracic aorta, abdominal aorta, and peripheral arteries. A dose of either 71.6 micromol Fe/kg (n = 9), or 35.8 micromol Fe/kg (n = 3) was used. Based on a phantom study, the agent with initial concentration of 537.2 micromol Fe/mL was diluted by either four-fold (134.3 micromol Fe/mL) or eight-fold (67.1 micromol Fe/mL) for first-pass MRA. All subjects completed their studies without adverse events. First-pass MRA showed selective arterial enhancement, with both arterial and venous enhancement on delayed acquisitions. Selective venous enhancement could be obtained by subtraction of arterial phase images from equilibrium phase images. The findings in ferumoxytol MRA were consistent with the results of original vascular tests. Our preliminary experience supports the feasibility of first-pass MRA with ferumoxytol. Satisfactory arterial enhancement during first-pass imaging is obtained with injection of diluted contrast agent. With ferumoxytol, arteries and veins can be selectively depicted in a single exam.

  12. Pharmacist-patient communication about medication regimen adjustment during Ramadan.

    PubMed

    Amin, Mohamed E K; Chewning, Betty

    2016-12-01

    During Ramadan, Muslims fast from dawn to sunset while abstaining from food and drink. Although Muslim patients may be aware of their religious exemption from fasting, many patients still choose not to take that exemption and fast. This study examines pharmacists' initiation and timing of communication about medication regimen adjustment (MRA) with patients related to Ramadan. Predictors for initiating this communication with patients were also explored. A probability sample of community pharmacists in Alexandria, Egypt was surveyed. The self-administered instrument covered timing and likelihood of initiating discussion about MRA. Using ordered logistic regression, a model was estimated to predict pharmacists' initiation of the conversation on MRA during Ramadan. Ninety-three percent of the 298 approached pharmacists completed surveys. Only 16% of the pharmacists reported that they themselves usually initiated the conversation on MRA. Pharmacists' initiation of these conversations was associated with pharmacists' perceived importance of MRA on pharmacy revenue odds ratio ((OR) = 1.24, CI = 1.03-1.48). Eighty percent of the responding pharmacists reported the MRA conversation for chronic conditions started either 1-3 days before, or during the first week of Ramadan. These results suggest considerable pharmacist patient communication gaps regarding medication use during Ramadan. It is especially important for pharmacists and other health professionals to initiate communication with Muslim patients early enough to identify how best to help patients transition safely into and out of Ramadan as they fast. © 2016 Royal Pharmaceutical Society.

  13. Contrast-enhanced MR angiography of cavopulmonary connections in adult patients with congenital heart disease.

    PubMed

    Wagner, Moritz; Nguyen, Kim-Lien; Khan, Sarah; Mirsadraee, Saeed; Satou, Gary M; Aboulhosn, Jamil; Finn, J Paul

    2012-11-01

    The purpose of this study is to evaluate combined time-resolved and high-spatial resolution contrast-enhanced MR angiography (MRA) for assessment of cavopulmonary connections in adult patients with congenital heart disease. Twenty-eight adults with various surgical cavopulmonary connections (Glenn shunt and Fontan connection) underwent high-spatial-resolution contrast-enhanced MRA (voxel size, 1.95 mm(3); temporal resolution, 22 seconds) and time-resolved contrast-enhanced MRA (voxel size, 6.5-9.3 mm(3); temporal resolution, < 1.2 seconds). Ten patients had 2D phase contrast flow quantification measurements performed at the same setting. Two readers independently assessed anatomic dimensions of cavopulmonary connections (using high-spatial-resolution contrast-enhanced MRA) and pulmonary artery (PA) perfusion patterns (using time-resolved contrast-enhanced MRA). High-spatial-resolution contrast-enhanced MRA yielded diagnostic-quality images for morphologic assessment of cavopulmonary connections in 27 of 28 (96%) patients. The anatomic dimensions (cross-sectional area) of the PA and cavopulmonary connections showed a wide variation (right PA, 0.99-5.67 cm(2); left PA, 0.80-5.69 cm(2); Glenn shunt, 0.93-6.94 cm(2); and Fontan connection, 1.25-6.67 cm(2)). The anatomic dimensions could be assessed with excellent interobserver agreement on high-spatial-resolution contrast-enhanced MRA (r = 0.895). Time-resolved contrast-enhanced MRA yielded diagnostic-quality images in all patients and enabled characterization of PA perfusion via the superior vena cava as follows: preferential inflow to the right PA (n = 12), preferential inflow to the left PA (n = 5), and balanced inflow to the right and left PA (n = 11). In those patients who had technically successful flow quantification measurements, phase contrast data confirmed patency of the cavopulmonary connections. Combined time-resolved contrast-enhanced MRA and high-spatial-resolution contrast-enhanced MRA allowed detailed

  14. Supra-aortic low-dose contrast-enhanced time-resolved magnetic resonance (MR) angiography at 3 T: comparison with time-of-flight MR angiography and high-resolution contrast-enhanced MR angiography.

    PubMed

    Lee, Youn-Joo; Kim, Bum-soo; Koo, Ja-Sung; Kim, Bom-Yi; Jang, Jinhee; Choi, Hyun Seok; Jung, So-Lyung; Ahn, Kook-Jin

    2015-06-01

    Low-dose, time-resolved, contrast-enhanced, magnetic resonance angiography (TR-CEMRA) has been described previously; however, a comparative study between low dose TR-CEMRA and time-of-flight MRA (TOF-MRA) in the diagnosis of supra-aortic arterial stenosis has not yet been published. To demonstrate the feasibility and effectiveness of low-dose TR-CEMRA compared with TOF-MRA, using high-resolution contrast-enhanced MRA (HR-CEMRA) as the reference standard. This prospective study consisted of 30 consecutive patients. All patients underwent TOF-MRA of the neck and circle of Willis and supra-aortic HR-CEMRA, followed by supra-aortic low-dose TR-CEMRA. Gadoterate meglumine (Gd-DOTA, Dotarem(®), Guerbet, Roissy CdG Cedex, France) was injected at a dose of 0.1 mmol/kg for HR-CEMRA, followed by a 0.03 mmol/kg bolus for low-dose TR-CEMRA. Three readers evaluated the assessibility and image quality, and then two readers classified each stenosis into the following categories: normal (0-30%), mild stenosis (31-50%), moderate (51-70%), severe (71-99%), and occlusion. TR-CEMRA and HR-CEMRA showed a greater number of assessable arterial segments than TOF-MRA (P < 0.01). For TR-CEMRA, 29 cases showed within or better than the diagnostic range, whereas all 30 cases were in the diagnostic range for TOF-MRA and HR-CEMRA. For evaluation of stenosis in a total of 743 arterial segments, both TR-CEMRA and TOF-MRA results agreed with those of HR-CEMRA in 729 segments (98.1%), with excellent inter-observer agreement of TR-CEMRA; stenosis was overestimated in nine segments (1.2%) and underestimated in five segments (0.7%). For diagnosis of stenosis using 30% as the cut-off value on HR-CEMRA, the sensitivity and specificity were 88.2% and 99.3%, respectively, for the TR-CEMRA procedure, versus 94.1% and 99.6%, respectively, for TOF-MRA. Low-dose TR-CEMRA is feasible and effective in the diagnosis of supra-aortic arterial stenosis, and could be more useful option than TOF-MRA. © The

  15. An international multicenter comparison of time-SLIP unenhanced MR angiography and contrast-enhanced CT angiography for assessing renal artery stenosis: the renal artery contrast-free trial.

    PubMed

    Albert, Timothy S E; Akahane, Masaaki; Parienty, Isabelle; Yellin, Nancy; Catalá, Violeta; Alomar, Xavier; Prot, Antoine; Tomizawa, Nobuo; Xue, Huadan; Katabathina, Venkata S; Lopera, Jorge E; Jin, Zhengyu

    2015-01-01

    The unenhanced MR angiography (MRA) technique time-spatial labeling inversion pulse (time-SLIP) may provide a safe alternative for evaluating the renal arteries for stenosis. This international multicenter trial tested the hypothesis that time-SLIP unenhanced MRA is accurate and robust for assessing the renal arteries for stenosis in comparison with contrast-enhanced CT angiography (CTA). Four centers (United States, Europe, Asia) enrolled 75 patients (average age ± SD, 58 ± 13 years; 41 [55%] men and 34 [45%] women). Each patient underwent abdominal contrast-enhanced CTA and abdominal unenhanced MRA using time-SLIP with balanced steady-state free precession. All images were visually assessed for quality (arterial signal intensity) and for the absence or presence of renal artery stenosis (≤ 50% or > 50% stenosis, respectively). In addition, for arteries with any visible disease, the severity of the stenosis was quantified. Two blinded readers evaluated each study. No arteries were excluded from analysis. Unenhanced MRA image quality was excellent for 56 of 75 patients (75%) and good for 16 of 75 patients (21%). CTA was used as the reference standard and showed that 23 of 161 renal arteries (14.3%) had stenosis > 50%. Unenhanced MRA correctly classified 17 of the 23 renal arteries with > 50% stenosis and correctly classified 128 of the 138 renal arteries as not having disease (≤ 50% stenosis) to yield a sensitivity of 74%, specificity of 93%, and accuracy of 90% (χ(2) = 0.56; p = 0.45, no statistically significant difference). Of the 16 misclassified arteries, only three had a clinically relevant misclassification (CTA ≥ 70% stenosis and unenhanced MRA ≤ 50% stenosis or unenhanced MRA ≥ 70% stenosis and CTA ≤ 50% stenosis). On average, measured stenotic severity (n = 28 arteries) was similar for unenhanced MRA (64% ± 17%) and CTA (62% ± 16%) (p = 0.51). Compared with contrast-enhanced CTA, the unenhanced MRA technique time-SLIP shows promise for

  16. 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.

  17. Diagnosis of systemic arterial diseases with whole-body 3D contrast-enhanced magnetic resonance angiography.

    PubMed

    Lin, Jiang; Chen, Bin; Wang, Jian-hua

    2006-11-05

    With the development of magnetic resonance (MR) technologies, whole-body 3D contrast-enhanced MR angiography (3D CE MRA) has become possible. The purpose of this study was to introduce and evaluate this technique in demonstration of various systemic arterial diseases. Thirty-seven patients underwent whole-body 3D CE MRA using a 1.5T MR imager. The patients included were with clinically documented or suspected peripheral arterial occlusive disease (PAOD, n = 19), Takayasu arteritis (n = 8), polyarteritis nodosa (n = 1), Type B dissection (n = 4) and thoracic and/or abdominal aneurysm (n = 5). Sixty-eight surface coil elements were employed to encompass the whole body. Four 3D CE MRA stations were acquired successively through automatic table moving. A total scan range of 188 cm, covering the arterial tree from carotid artery to trifurcation vessels, was acquired. Overall image quality of each arterial segment and venous overlay were assessed and rated. The depiction of various systemic arterial diseases was evaluated and compared with other imaging modalities if available, including digital subtraction angiography (DSA), CT angiography, dedicated mono-station MRA. Whole-body 3D CE MRA was well tolerated by all patients. It yielded a detailed display of the arterial system with a short examination time. The image quality was considered diagnostic in 99.3% of the arterial segments. The remaining 0.7% of the arterial segments were considered non-diagnostic. In 7 of 19 patients with PAOD, whole-body MRA showed additional vascular narrowing apart from peripheral arterial disease. In 9 patients with vasculitis, whole-body MRA depicted luminal irregularity, narrowing or occlusion, aneurysm and collateral circulation involving multiple vascular segments. Whole-body MRA also clearly revealed the severity and extent of dissection and aortic aneurysm. In 20 cases the vascular pathologies demonstrated on whole body MRA were confirmed by other imaging investigations. The whole

  18. 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.

  19. Off-resonance magnetic resonance angiography improves visualization of in-stent lumen in peripheral nitinol stents compared to conventional T1-weighted acquisitions: an in vitro comparison study.

    PubMed

    Gitsioudis, Gitsios; Fortner, Philipp; Stuber, Matthias; Missiou, Anna; Andre, Florian; Müller, Oliver J; Katus, Hugo A; Korosoglou, Grigorios

    2016-11-01

    To compare the value of inversion recovery with on-resonant water suppression (IRON) to conventional T1-weighted (T1w) MRA and computed tomography angiography (CTA) for visualization of peripheral nitinol stents. We visualized 14 different peripheral nitinol stents in vitro both using Gadolinium (Gd) and ultrasmall superparamagnetic iron nanoparticles (USPIOs) for conventional T1w and IRON-MRA using clinical grade 1.5T MR scanner and iodinated contrast material for CTA using a 256-slice CT scanner. Parameter assessment included signal- and contrast-to-noise ratio (S/CNR), relative in-stent signal and artificial lumen narrowing. X-ray angiography served as gold standard for diameter assessment. Gd-enhanced IRON-MRA exhibited highest in-stent SNR and CNR values compared to conventional T1w MRA (IRON (Gd/USPIO): SNR = 30 ± 3/21 ± 2, CNR = 23 ± 2/14 ± 1; T1w: SNR = 16 ± 1/14 ± 2, CNR = 12 ± 1/10 ± 1, all p < 0.05). Furthermore, IRON-MRA achieved highest relative in-stent signal both using Gd and USPIO (IRON (Gd/USPIO): 121 ± 8 %/103 ± 6 %; T1w: 73 ± 2 %/66 ± 4 %; CTA: 84 ± 6 %, all p < 0.05). However, artificial lumen narrowing appeared similar in all imaging protocols (IRON (Gd/USPIO): 21 ± 3 %/21 ± 2 %; T1w: 16 ± 4 %/17 ± 3 %; CTA: 19 ± 2 %, all p = NS). Finally, IRON-MRA provided improvement of the in-stent lumen visualization with an 'open-close-open' design, which revealed a complete in-stent signal loss in T1w MRA. IRON-MRA improves in-stent visualization in vitro compared to conventional T1w MRA and CTA. In light of the in vitro results with Gd-enhanced IRON-MRA, the clinical implementation of such an approach appears promising.

  20. Detection of Symptomatic Carotid Plaque Using Source Data from MR and CT Angiography: A Correlative Study

    PubMed Central

    Gupta, Ajay; Baradaran, Hediyeh; Mtui, Edward E.; Kamel, Hooman; Pandya, Ankur; Giambrone, Ashley; Iadecola, Costantino; Sanelli, Pina C.

    2016-01-01

    Background Carotid plaque MRI has been a useful method to characterize vulnerable atherosclerotic plaque elements. Recent investigations have suggested that source images from CT angiography (CTA) and MR angiography (MRA) can identify the simple high-risk features of symptom-producing carotid artery plaque. We studied the correlation and relative diagnostic accuracies of CTA and MRA source images in detecting symptomatic carotid artery plaque. Methods Subjects were eligible if they had carotid stenosis between 50 and 99% and had MRA and CTA exams performed within 10 days of one another. We measured the soft (non-calcified) plaque and hard (calcified) plaque thickness on CTA axial source images and intraplaque high-intensity signal (IHIS) on 3D-time-of-flight MRA source images in subjects. We assessed whether a correlation existed between increasing CTA soft plaque thicknesses and the presence of MRA IHIS using the Student's t-test. We calculated the differences in sensitivity and specificity measures of CTA and MRA source-imaging data with the occurrence of recent ipsilateral stroke or transient ischemic attack (TIA) as the reference standard. We also performed logistic regression analyses to evaluate the predictive strength of plaque showing both IHIS and increased CTA soft plaque thickness in predicting symptomatic disease status. Results Of 1994 screened patients, 48 arteries met the final inclusion criteria with MRA and CTA performed within 10 days of one another. The mean and median time between CTA and MRA exams were 2.0 days and 1 day, respectively. A total of 34 of 48 stenotic vessels (70.8%) were responsible for giving rise to ipsilateral stroke or TIA. CTA mean soft plaque thickness was significantly greater (4.47 vs. 2.30 mm, p < 0.0001) in patients with MRA-defined IHIS, while CTA hard plaque thickness was significantly greater (2.09 vs. 1.16 mm, p = 0.0134) in patients without MRA evidence of IHIS. CTA soft plaque thickness measurements were more

  1. Preventive and chronic mineralocorticoid receptor antagonism is highly beneficial in obese SHHF rats

    PubMed Central

    Youcef, G; Olivier, A; Nicot, N; Muller, A; Deng, C; Labat, C; Fay, R; Rodriguez‐Guéant, R‐M; Leroy, C; Jaisser, F; Zannad, F; Lacolley, P; Vallar, L

    2016-01-01

    Background and Purpose Mineralocorticoid receptor (MR) activation contributes to heart failure (HF) progression. Its overactivity in obesity is thought to accelerate cardiac remodelling and HF development. Given that MR antagonists (MRA) are beneficial in chronic HF patients, we hypothesized that early MRA treatment may target obesity‐related disorders and consequently delay the development of HF. Experimental Approach Twenty spontaneously hypertensive HF dyslipidaemic obese SHHFcp/cp rats and 18 non‐dyslipidaemic lean SHHF+/+ controls underwent regular monitoring for their metabolic and cardiovascular phenotypes with or without MRA treatment [eplerenone (eple), 100 mg∙kg−1∙day−1] from 1.5 to 12.5 months of age. Key Results Eleven months of eple treatment in obese rats (SHHFcp/cpeple) reduced the obesity‐related metabolic disorders observed in untreated SHHFcp/cp rats by reducing weight gain, triglycerides and total cholesterol levels and by preserving adiponectinaemia. The MRA treatment predominantly preserved diastolic and systolic functions in obese rats by alleviating the eccentric cardiac hypertrophy observed in untreated SHHFcp/cp animals and preserving ejection fraction (70 ± 1 vs. 59 ± 1%). The MRA also improved survival independently of these pressure effects. Conclusion and Implications Early chronic eple treatment resulted in a delay in cardiac remodelling and HF onset in both SHHF+/+ and SHHFcp/cp rats, whereas SHHFcp/cp rats further benefited from the MRA treatment through a reduction in their obesity and dyslipidaemia. These findings suggest that preventive MRA therapy may provide greater benefits in obese patients with additional risk factors of developing cardiovascular complications. PMID:26990406

  2. Flow characteristics in a canine aneurysm model: A comparison of 4D accelerated phase-contrast MR measurements and computational fluid dynamics simulations

    PubMed Central

    Jiang, Jingfeng; Johnson, Kevin; Valen-Sendstad, Kristian; Mardal, Kent-Andre; Wieben, Oliver; Strother, Charles

    2011-01-01

    Purpose: Our purpose was to compare quantitatively velocity fields in and around experimental canine aneurysms as measured using an accelerated 4D PC-MR angiography (MRA) method and calculated based on animal-specific CFD simulations. Methods: Two animals with a surgically created bifurcation aneurysm were imaged using an accelerated 4D PC-MRA method. Meshes were created based on the geometries obtained from the PC-MRA and simulations using “subject-specific” pulsatile velocity waveforms and geometries were then solved using a commercial CFD solver. Qualitative visual assessments and quantitative comparisons of the time-resolved velocity fields obtained from the PC-MRA measurements and the CFD simulations were performed using a defined similarity metric combining both angular and magnitude differences of vector fields. Results: PC-MRA and image-based CFD not only yielded visually consistent representations of 3D streamlines in and around both aneurysms, but also showed good agreement with regard to the spatial velocity distributions. The estimated similarity between time-resolved velocity fields from both techniques was reasonably high (mean value >0.60; one being the highest and zero being the lowest). Relative differences in inflow and outflow zones among selected planes were also reasonable (on the order of 10%–20%). The correlation between CFD-calculated and PC-MRA-measured time-averaged wall shear stresses was low (0.22 and 0.31, p < 0.001). Conclusions: In two experimental canine aneurysms, PC-MRA and image-based CFD showed favorable agreement in intra-aneurismal velocity fields. Combining these two complementary techniques likely will further improve the ability to characterize and interpret the complex flow that occurs in human intracranial aneurysms. PMID:22047395

  3. Quantitative magnetic resonance arthrography in patients with femoroacetabular impingement.

    PubMed

    Samaan, Michael A; Zhang, Alan L; Gallo, Matthew C; Schwaiger, Benedikt J; Link, Thomas M; Souza, Richard B; Majumdar, Sharmila

    2016-12-01

    Quantitative MRI (QMRI) of the hip with sequences such as T1ρ and T2 mapping has been utilized to detect early changes in cartilage matrix composition. However, QMRI has not been performed in the presence of intra-articular contrast. Thus the purpose of this study was to evaluate the feasibility and use of QMRI during MR-arthrography (MRA) in femoracetabular impingement (FAI) patients. Using a 3 Tesla MR-scanner, 10 FAI patients underwent a unilateral MRA and standard MRI of the hip joint. Global and sub-regional T1ρ and T2 relaxation times of the acetabular and femoral articular cartilage were computed in the MRA and MRI assessments and agreement of these values were assessed using the Krippendorff's alpha (α) coefficient and linear regression (μ). T1ρ and T2 relaxation times between the MRA and MRI were compared using a repeated measures analysis of variance. Both global and sub-regional T1ρ and T2 relaxation times demonstrated strong agreement (α > 0.83; μ > 0.85) independent of intra-articular contrast. Also, global and sub-regional acetabular T1ρ (P = 0.72) and T2 (P = 0.94), as well as femoral T1ρ , relaxation times were similar between MRA and MRI (P = 0.73) yet femoral T2 relaxation times decreased when using intra-articular contrast (P = 0.04). This study demonstrated the feasibility of T1ρ and T2 mapping for use in hip MRA with FAI patients. The inclusion of QMRI in MRA provides a quantitative assessment of the effects of FAI on hip joint articular cartilage while allowing for detailed assessment of labral pathology with the use of intra-articular contrast. J. Magn. Reson. Imaging 2016;44:1539-1545. © 2016 International Society for Magnetic Resonance in Medicine.

  4. 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

    2016-07-08

    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.

  5. Feasibility of Non-contrast-enhanced MR Angiography Using the Time-SLIP Technique for the Assessment of Pulmonary Arteriovenous Malformation.

    PubMed

    Hamamoto, Kohei; Matsuura, Katsuhiko; Chiba, Emiko; Okochi, Tomohisa; Tanno, Keisuke; Tanaka, Osamu

    2016-07-11

    The purpose of this study was to evaluate the diagnostic performance of non-contrast-enhanced magnetic resonance angiography with time-spatial labeling inversion pulse (time-SLIP MRA) in the assessment of pulmonary arteriovenous malformation (PAVM). Eleven consecutive patients with 38 documented PAVMs underwent time-SLIP MRA with a 3-tesla unit. Eight patients with 25 lesions were examined twice, once before and once after embolotherapy. The lesions were divided into two groups-initial diagnosis (n = 35) and follow-up (n = 28)-corresponding to untreated and treated lesions, respectively, and were evaluated separately. To evaluate the initial diagnosis group, two reviewers assessed image quality for visualization of PAVMs by using a qualitative 4-point scale (1 = not assessable to 4 = excellent). The location and classification of PAVMs were also evaluated. The results were compared with those from digital subtraction angiography. For evaluation of the follow-up group, the reviewers assessed the status of treated PAVMs. Reperfusion and occlusion were defined respectively as visualization or disappearance of the aneurysmal sac. The diagnostic accuracy of time-SLIP MRA was assessed and compared with standard reference images. Interobserver agreement was evaluated with the κ statistic. In the initial diagnosis group, time-SLIP MRA correctly determined the PAVMs in all but one patient with one lesion who had image degradation due to irregular breath. Image quality was considered excellent (median = 4) and the κ coefficient was 0.85. Additionally, both readers could correctly localize and classify the PAVMs on time-SLIP MRA images with both κ coefficient of 1.00. In the follow-up group, the sensitivity and specificity of time-SLIP MRA for reperfusion of PAVMs were both 100%, and the κ coefficient was 1.00. Time-SLIP MRA is technically and clinically feasible and represents a promising technique for noninvasive pre- and post-treatment assessment of PAVMs.

  6. First-Pass Contrast-Enhanced MR Angiography in Evaluation of Treated Spinal Arteriovenous Fistulas: Is Catheter Angiography Necessary?

    PubMed

    Mathur, S; Symons, S P; Huynh, T J; Marotta, T R; Aviv, R I; Bharatha, A

    2017-01-01

    Catheter angiography is typically used for follow-up of treated spinal AVFs. The purpose of this study was to determine the diagnostic performance and utility of first-pass contrast-enhanced MRA in the posttreatment evaluation of spinal AVFs compared with DSA. A retrospective review was performed of all patients at our tertiary referral hospital (from January 2000 to April 2015) who underwent spine MR imaging, first-pass contrast-enhanced MRA, and DSA after surgical and/or endovascular treatment of a spinal AVF. Presence of recurrent or residual fistula on MRA, including vertebral level of the recurrent/residual fistula, was evaluated by 2 experienced neuroradiologists blinded to DSA findings. Posttreatment conventional MR imaging findings were also evaluated, including presence of intramedullary T2 hyperintensity, perimedullary serpentine flow voids, and cord enhancement. The performance of MRA and MR imaging findings for diagnosis of recurrent/residual fistula was determined by using DSA as the criterion standard. In total, 28 posttreatment paired MR imaging/MRA and DSA studies were evaluated in 22 patients with prior spinal AVF and 1 patient with intracranial AVF with prior cervical perimedullary venous drainage. Six image sets of 5 patients demonstrated recurrent/residual disease at DSA. MRA correctly identified all cases with recurrent/residual disease with 1 false-positive (sensitivity, 100%; specificity 95%; P < .001), with correct localization in all cases without interobserver disagreement. Conventional MR imaging parameters were not significantly associated with recurrent/residual spinal AVF. First-pass MRA demonstrates high sensitivity and specificity for identifying recurrent/residual spinal AVFs and may potentially substitute for DSA in the posttreatment follow-up of patients with spinal AVFs. © 2017 by American Journal of Neuroradiology.

  7. Evaluation of contrast-enhanced MR angiography in the follow-up of visceral arterial aneurysms after coil embolization.

    PubMed

    Iryo, Yasuhiko; Ikushima, Ichiro; Hirai, Toshinori; Yonenaga, Kazuchika; Yamashita, Yasuyuki

    2013-06-01

    The placement of detachable coil has become the alternative method of treating visceral arterial aneurysms (VAAs). Imaging follow-up is necessary after coil embolization because of frequent incomplete occlusion. To compare contrast-enhanced magnetic resonance angiography (CE-MRA) at 3T with a reference standard of digital subtraction angiography (DSA) for the evaluation of VAAs after coil embolization. We treated 15 patients with VAA with coil embolization; eight had splenic artery aneurysms and seven had renal artery aneurysms. We packed the aneurysmal sac preserving native arterial circulation. For follow-up, all patients underwent CE-MRA at 3T and DSA. The results were classified according to coil occlusion: Class 1, complete occlusion; Class 2, residual neck; Class 3, aneurysmal filling. CE-MRA revealed 11 complete occlusions and four residual necks. DSA follow-up showed 12 complete occlusions and three residual necks. No aneurysmal filling occurred after treatment. Comparison of CE-MRA and DSA findings showed 93% agreement (14/15). CE-MRA allowed the detection of a residual neck in one misclassified case in which DSA showed occlusion. Coil-related artifacts were minimal and did not interfere with evaluation of the occlusion status of the VAAs. CE-MRA at 3T provides high-quality images equivalent to DSA for the evaluation of VAAs after coil embolization. We suggest that CE-MRA at 3T might be used as the primary method for follow-up of VAAs after coil embolization. © 2013 The Foundation Acta Radiologica.

  8. Non-contrast-enhanced MR angiography at 3 Tesla in patients with advanced peripheral arterial occlusive disease.

    PubMed

    Thierfelder, Kolja M; Meimarakis, Georgios; Nikolaou, Konstantin; Sommer, Wieland H; Schmitt, Peter; Kazmierczak, Philipp M; Reiser, Maximilian F; Theisen, Daniel

    2014-01-01

    The aim of this study was to assess the diagnostic performance of ECG-gated non-contrast-enhanced quiescent interval single-shot (QISS) magnetic resonance angiography at a magnetic field strength of 3 Tesla in patients with advanced peripheral arterial occlusive disease (PAOD). A total of 21 consecutive patients with advanced PAOD (Fontaine stage IIb and higher) referred for peripheral magnetic resonance angiography (MRA) were included. Imaging was performed on a 3 T whole body MR. Image quality and stenosis diameter were evaluated in comparison to contrast-enhanced continuous table and TWIST MRA (CE-MRA) as standard of reference. QISS images were acquired with a thickness of 1.5 mm each (high-resolution QISS, HR-QISS). Two blinded readers rated the image quality and the degree of stenosis for both HR-QISS and CE-MRA in 26 predefined arterial vessel segments on 5-point Likert scales. With CE-MRA as the reference standard, HR-QISS showed high sensitivity (94.1%), specificity (97.8%), positive (95.1%), and negative predictive value (97.2%) for the detection of significant (≥ 50%) stenosis. Interreader agreement for stenosis assessment of both HR-QISS and CE-MRA was excellent (κ-values of 0.951 and 0.962, respectively). As compared to CR-MRA, image quality of HR-QISS was significantly lower for the distal aorta, the femoral and iliac arteries (each with p<0.01), while no significant difference was found in the popliteal (p = 0.09) and lower leg arteries (p = 0.78). Non-enhanced ECG-gated HR-QISS performs very well in subjects with severe PAOD and is a good alternative for patients with a high risk of nephrogenic systemic fibrosis.

  9. Comparison of dynamic contrast-enhanced 3T MR and 64-row multidetector CT angiography for the localization of spinal dural arteriovenous fistulas.

    PubMed

    Oda, S; Utsunomiya, D; Hirai, T; Kai, Y; Ohmori, Y; Shigematsu, Y; Iryo, Y; Uetani, H; Azuma, M; Yamashita, Y

    2014-02-01

    For the localization of spinal dural arteriovenous fistulas, it is not determined whether dynamic contrast-enhanced MRA is more reliable than multidetector CTA. The aim of this study was to compare the agreement between intra-arterial DSA, dynamic contrast-enhanced MRA at 3T, and 64-row multidetector CTA for the localization of spinal dural arteriovenous fistulas. We enrolled 12 consecutive patients (11 men, 1 woman; age range, 46-83 years; mean, 65 years) who underwent preoperative dynamic contrast-enhanced MRA at 3T and 64-row multidetector CTA. The spinal dural arteriovenous fistula location was confirmed by intra-arterial DSA as the reference standard. Two reviewers independently evaluated the level of the artery feeding the spinal dural arteriovenous fistula on the basis of continuity between the feeder and abnormal spinal vessels on 3T dynamic contrast-enhanced MRA and 64-row multidetector CTA images. Interobserver and intermodality agreement was determined by calculation of the κ coefficient. On DSA, the vessel feeding the spinal dural arteriovenous fistula was the intercostal artery (7 cases), the lumbar artery (3 cases), and the internal iliac artery or the ascending pharyngeal artery (1 case each). For the fistula level, interobserver agreement was excellent for 3T dynamic contrast-enhanced MRA (κ = 0.97; 95% CI, 0.92-1.00) and very good for 64-row multidetector CTA (κ = 0.84; 95% CI, 0.72-0.96). Intermodality agreement with DSA was good for 3T dynamic contrast-enhanced MRA (κ = 0.78; 95% CI, 0.49-1.00) and moderate for 64-row multidetector CTA (κ = 0.41; 95% CI, 0.020-0.84). For the localization of spinal dural arteriovenous fistulas, 3T dynamic contrast-enhanced MRA may be more reliable than 64-row multidetector CTA.

  10. Accelerated free breathing ECG triggered contrast enhanced pulmonary vein magnetic resonance angiography using compressed sensing.

    PubMed

    Roujol, Sébastien; Foppa, Murilo; Basha, Tamer A; Akçakaya, Mehmet; Kissinger, Kraig V; Goddu, Beth; Berg, Sophie; Nezafat, Reza

    2014-11-22

    To investigate the feasibility of accelerated electrocardiogram (ECG)-triggered contrast enhanced pulmonary vein magnetic resonance angiography (CE-PV MRA) with isotropic spatial resolution using compressed sensing (CS). Nineteen patients (59±13 y, 11 M) referred for MR were scanned using the proposed accelerated free breathing ECG-triggered 3D CE-PV MRA sequence (FOV=340×340×110 mm3, spatial resolution=1.5×1.5×1.5 mm3, acquisition window=140 ms at mid diastole and CS acceleration factor=5) and a conventional first-pass breath-hold non ECG-triggered 3D CE-PV MRA sequence. CS data were reconstructed offline using low-dimensional-structure self-learning and thresholding reconstruction (LOST) CS reconstruction. Quantitative analysis of PV sharpness and subjective qualitative analysis of overall image quality were performed using a 4-point scale (1: poor; 4: excellent). Quantitative PV sharpness was increased using the proposed approach (0.73±0.09 vs. 0.51±0.07 for the conventional CE-PV MRA protocol, p<0.001). There were no significant differences in the subjective image quality scores between the techniques (3.32±0.94 vs. 3.53±0.77 using the proposed technique). CS-accelerated free-breathing ECG-triggered CE-PV MRA allows evaluation of PV anatomy with improved sharpness compared to conventional non-ECG gated first-pass CE-PV MRA. This technique may be a valuable alternative for patients in which the first pass CE-PV MRA fails due to inaccurate first pass timing or inability of the patient to perform a 20-25 seconds breath-hold.

  11. Purification and Functional Characterization of the ϕX174 Lysis Protein E†

    PubMed Central

    Zheng, Yi; Struck, Douglas K.; Young, Ry

    2011-01-01

    Two classes of bacteriophages, the single-stranded DNA Microviridae, and the single-stranded RNA Alloleviviridae, accomplish lysis by expressing “protein antibiotics”, or polypeptides that inhibit cell wall biosynthesis. Previously, we have provided genetic and physiological evidence that E, a 91 aa membrane protein encoded by the prototype microvirus, ϕX174, is a specific inhibitor of the translocase MraY, an essential membrane-embedded enzyme that catalyzes the formation of the murein precursor, Lipid I, from UDP-N-acetylmuramic acid-pentapeptide and the lipid carrier, undecaprenol phosphate. Here we report the first purification of E, which has been refractory to over-expression because of its lethality to E. coli. Moreover, using a fluorescently-labeled analog of the sugar-nucleotide substrate, we demonstrate that E acts as a non-competitive inhibitor of detergent-solubilized MraY, with respect to both soluble and lipid substrates. In addition, we show that the E-sensitivity of five MraY mutant proteins, produced from alleles selected for resistance to E, can be correlated to the apparent affinities determined by in vivo multicopy suppression experiments. These results are inconsistent with previous reports that E inhibited membrane-embedded MraY but not the detergent-solubilized enzyme, which led to a model in which E functions by binding MraY and blocking the formation of an essential hetero-multimeric complex involving MraY and other murein biosynthesis enzymes. We discuss a new model in which E binds to MraY at a site composed of the two transmembrane domains within which the E-resistance mutations map and that the result of this binding is a conformational change that inactivates the enzyme. PMID:19379010

  12. Purification and functional characterization of phiX174 lysis protein E.

    PubMed

    Zheng, Yi; Struck, Douglas K; Young, Ry

    2009-06-09

    Two classes of bacteriophages, the single-stranded DNA Microviridae and the single-stranded RNA Alloleviviridae, accomplish lysis by expressing "protein antibiotics", or polypeptides that inhibit cell wall biosynthesis. Previously, we have provided genetic and physiological evidence that E, a 91-amino acid membrane protein encoded by the prototype microvirus, varphiX174, is a specific inhibitor of the translocase MraY, an essential membrane-embedded enzyme that catalyzes the formation of the murein precursor, Lipid I, from UDP-N-acetylmuramic acid-pentapeptide and the lipid carrier, undecaprenol phosphate. Here we report the first purification of E, which has been refractory to overexpression because of its lethality to Escherichia coli. Moreover, using a fluorescently labeled analogue of the sugar-nucleotide substrate, we demonstrate that E acts as a noncompetitive inhibitor of detergent-solubilized MraY, with respect to both soluble and lipid substrates. In addition, we show that the E sensitivity of five MraY mutant proteins, produced from alleles selected for resistance to E, can be correlated to the apparent affinities determined by in vivo multicopy suppression experiments. These results are inconsistent with previous reports that E inhibited membrane-embedded MraY but not the detergent-solubilized enzyme, which led to a model in which E functions by binding MraY and blocking the formation of an essential heteromultimeric complex involving MraY and other murein biosynthesis enzymes. We discuss a new model in which E binds to MraY at a site composed of the two transmembrane domains within which the E resistance mutations map and the fact that the result of this binding is a conformational change that inactivates the enzyme.

  13. 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.

  14. Assessing bioequivalence of generic modified-release antiepileptic drugs.

    PubMed

    Johnson, Emily L; Chang, Yi-Ting; Davit, Barbara; Gidal, Barry E; Krauss, Gregory L

    2016-04-26

    The purpose of this study was to determine how closely generic modified-release antiepileptic drugs (MR-AEDs) resemble reference (brand) formulations by comparing peak concentrations (Cmax), total absorption (area under the curve [AUC]), time to Cmax (Tmax), intersubject variability, and food effects between generic and reference products. We tabulated Cmax and AUC data from the bioequivalence (BE) studies used to support the approvals of generic Food and Drug Administration-approved MR-AEDs. We compared differences in 90% confidence intervals of the generic/reference AUC and Cmax geometric mean ratios, and intersubject variability, Tmax and delivery profiles and food effects. Forty-two MR-AED formulations were studied in 3,175 healthy participants without epilepsy in 97 BE studies. BE ratios for AUC and Cmax were similar between most generic and reference products: AUC ratios varied by >15% in 11.4% of BE studies; Cmax varied by >15% in 25.8% of studies. Tmax was more variable, with >30% difference in 13 studies (usually delayed in the fed compared to fasting BE studies). Generic and reference MR products had similar intersubject variability. Immediate-release AEDs showed less intersubject variability in AUC than did MR-AEDs. Most generic and reference MR-AEDs have similar AUC and Cmax values. Ratios for some products, however, are near acceptance limits and Tmax values may vary. Food effects are common with MR-AED products. High variability in pharmacokinetic values for once-a-day MR-AEDs suggests their major advantage compared to immediate-release AED formulations may be the convenience of less frequent dosing to improve adherence. © 2016 American Academy of Neurology.

  15. Performance of magnetic resonance angiography in suspected acute pulmonary embolism.

    PubMed

    Blum, Alain; Bellou, Abdelouahab; Guillemin, Francis; Douek, Philippe; Laprévote-Heully, Marie-Claude; Wahl, Denis

    2005-03-01

    Pulmonary embolism (PE) is a common and potentially fatal disorder. Non-specific findings make the clinical diagnosis of PE difficult. To assess the diagnostic value and inter-observer agreement of magnetic resonance angiography (MRA) in a cohort of patients with suspected PE, we conducted a prospective clinical study. MRA was compared for sensitivity and specificity to a diagnostic strategy including clinical probability, D-dimer testing, spiral CT, ultrasound leg compression and pulmonary angiography. A total of 89 patients with clinically suspected PE were included: the clinical probability of PE was intermediate or high in 78, and low in the remaining 11. All patients underwent monoor multi-slice spiral CT and MRA with gadolinium injection (both within 24 hours of entry to the study). Anticoagulation was withheld in patients concerned about the strategy. All subjects were followed up for 3 months. MRA was read independently by two experienced teams of radiologists: one local and one from another university centre. Spiral CT was positive in 62 of 63 cases of confirmed PE. No patient with negative CT findings was positive ultrasonographically. Only one patient with a negative CT (and negative ultrasound) had a recurrent thromboembolic event. The first team diagnosed PE with MRA in 47 cases, with a sensitivity of 71% and a specificity of 92%; the second team obtained the diagnosis in 23 cases, with a sensitivity of 31% and a specificity of 85%. Inter-observer agreement between MRA reading was low: Kappa = 0.16 (-0.01 to 0.33); p = 0.07. In conclusion, compared with a non-invasive strategy based on spiral CT, the diagnostic value of MRA is limited by poor inter-observer agreement.

  16. Autologous breast reconstruction: preoperative magnetic resonance angiography for perforator flap vessel mapping.

    PubMed

    Agrawal, Mukta D; Thimmappa, Nanda Deepa; Vasile, Julie V; Levine, Joshua L; Allen, Robert J; Greenspun, David T; Ahn, Christina Y; Chen, Constance M; Hedgire, Sandeep S; Prince, Martin R

    2015-01-01

    Selection of a vascular pedicle for autologous breast reconstruction is time consuming and depends on visual evaluation during the surgery. Preoperative imaging of donor site for mapping the perforator artery anatomy greatly improves the efficiency of perforator selection and significantly reduces the operative time. In this article, we present our experience with magnetic resonance angiography (MRA) for perforator vessel mapping including MRA technique and interpretation. We have performed over 400 MRA examinations from August 2008 to August 2013 at our institution for preoperative imaging of donor site for mapping the perforator vessel anatomy. Using our optimized imaging protocol with blood pool magnetic resonance imaging contrast agents, multiple donor sites can be imaged in a single MRA examination. Following imaging using the postprocessing and reporting tool, we estimated incidence of commonly used perforators for autologous breast reconstruction. In our practice, anterior abdominal wall tissue is the most commonly used donor site for perforator flap breast reconstruction and deep inferior epigastric artery perforators are the most commonly used vascular pedicle. A thigh flap, based on the profunda femoral artery perforator has become the second most used flap at our institution. In addition, MRA imaging also showed evidence of metastatic disease in 4% of our patient subset. Our MRA technique allows the surgeons to confidently assess multiple donor sites for the best perforator and flap design. In conclusion, a well-performed MRA with specific postprocessing provides an accurate method for mapping perforator vessel, at the same time avoiding ionizing radiation. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  17. 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.

    2016-11-01

    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.

  18. Reporting rotator cuff tears on magnetic resonance arthrography using the Snyder’s arthroscopic classification

    PubMed Central

    Aliprandi, Alberto; Messina, Carmelo; Arrigoni, Paolo; Bandirali, Michele; Di Leo, Giovanni; Longo, Stefano; Magnani, Sandro; Mattiuz, Chiara; Randelli, Filippo; Sdao, Silvana; Sardanelli, Francesco; Sconfienza, Luca Maria; Randelli, Pietro

    2017-01-01

    AIM To determine diagnostic performance of magnetic resonance arthrography (MRA) in evaluating rotator cuff tears (RCTs) using Snyder’s classification for reporting. METHODS One hundred and twenty-six patients (64 males, 62 females; median age 55 years) underwent shoulder MRA and arthroscopy, which represented our reference standard. Surgical arthroscopic reports were reviewed and the reported Snyder’s classification was recorded. MRA examinations were evaluated by two independent radiologists (14 and 5 years’ experience) using Snyder’s classification system, blinded to arthroscopy. Agreement between arthroscopy and MRA on partial- and full-thickness tears was calculated, first regardless of their extent. Then, analysis took into account also the extent of the tear. Interobserver agreement was also calculated the quadratically-weighted Cohen kappa statistics. RESULTS On arthroscopy, 71/126 patients (56%) had a full-thickness RCT. The remaining 55/126 patients (44%) had a partial-thickness RCT. Regardless of tear extent, out of 71 patients with arthroscopically-confirmed full-thickness RCTs, 66 (93%) were correctly scored by both readers. All 55 patients with arthroscopic diagnosis of partial-thickness RCT were correctly assigned as having a partial-thickness RCT at MRA by both readers. Interobserver reproducibility analysis showed total agreement between the two readers in distinguishing partial-thickness from full-thickness RCTs, regardless of tear extent (k = 1.000). With regard to tear extent, in patients in whom a complete tear was correctly diagnosed, correct tear extent was detected in 61/66 cases (92%); in the remaining 5/66 cases (8%), tear extent was underestimated. Agreement was k = 0.955. Interobserver agreement was total (k = 1.000). CONCLUSION MRA shows high diagnostic accuracy and reproducibility in evaluating RCTs using the Snyder’s classification for reporting. Snyder’s classification may be adopted for routine reporting of MRA. PMID

  19. Brain arteriovenous malformation diagnosis: value of time-resolved contrast-enhanced MR angiography at 3.0T compared to DSA.

    PubMed

    Machet, A; Portefaix, C; Kadziolka, K; Robin, G; Lanoix, O; Pierot, L

    2012-10-01

    This study was conducted in order to evaluate the value of time-resolved contrast-enhanced magnetic resonance angiography (TR-CE-MRA) with a 3.0-T magnetic field compared to digital subtraction angiography (DSA) as the reference standard for the diagnosis of brain arteriovenous malformation (bAVM). Nineteen patients with 19 angiographically confirmed untreated bAVM were investigated with both DSA and TR-CE-MRA for the initial diagnosis. Examinations were compared by two independent readers. Interobserver agreement and intermodality agreement with respect to nidus size, arterial feeders, and venous drainage were determined using the K statistic test. Also, the quality of the TR-CE-MRA images was evaluated. Seventeen of the 19 bAVM (89.5%) detected with DSA were diagnosed with TR-CE-MRA. Interobserver agreement for TR-CE-MRA was good for nidus size, venous drainage, and arterial feeders (K = 0.75, 95% CI 0.50-1.00; K = 0.77, 95% CI 0.54-1.00; and K = 0.80, 95% CI 0.59-1.00 respectively). Intermodality agreement was good for nidus size and venous drainage (K = 0.75, 95% CI 0.49-1.00 and K = 0.77, 95% CI 0.54-1.00, respectively) and moderate for arterial feeders (K = 0.44, 95% CI 0.17-0.70). TR-CE-MRA at 3.0 T has a good sensitivity for bAVM detection and good agreement with DSA for determining nidus size and the type of venous drainage, suggesting that TR-CE-MRA is potentially a reliable tool for the diagnosis and assessment of bAVMs. However, it still suffers from low spatial resolution and vessel superposition, making differentiation of the arterial feeders of the nidus difficult at times.

  20. Comparison of three-dimensional volume-targeted thin-slab FIESTA magnetic resonance angiography and 64-multidetector computed tomographic angiography for the identification of proximal coronary stenosis.

    PubMed

    Cheng, Liuquan; Ma, Lin; Schoenhagen, Paul; Ye, Huiyi; Lou, Xin; Gao, Yuangui; Zhao, Xihai; Wang, Xinjiang; Dong, Wei

    2013-09-10

    Based on recent clinical data, an imaging strategy of identifying proximal coronary disease allows further management decisions in patients with stable angina pectoris. We aimed to compare diagnostic accuracy of non-contrast fast steady-state (FIESTA) magnetic resonance angiography (MRA) with 64-multidetector computed tomographic angiography (CTA), using conventional coronary angiography (CA) as the reference standard. Thirty patients with suspected coronary artery disease consented to participate in an institutional review board-approved protocol. Coronary MRA was performed at 1.5 T using a respiratory navigator and electrocardiogram-gated three-dimensional FIESTA pulse sequence. CTA images were acquired using a 64-multidetector computed tomographic scanner, using beta blockade to reduce the heart rate to less than 70 bpm. Coronary luminal stenosis >50% was identified. Plaques were classified as non-calcified, mixed, or calcified on CTA, and as high-, intermediate-, or low-signal on FIESTA MRA. Compared to CA, the sensitivity, specificity, and overall accuracy for detection of >50% proximal coronary stenoses were 83.0%, 86.9%, and 86.1% for MRA and 85.1%, 87.2%, and 86.8% for CTA, respectively. For the 24 calcified stenoses, MRA corrected 16 segments that overestimated on CTA and MRA had an accuracy of 75% in evaluating calcified plaques. High-resolution three-dimensional FIESTA MRA and CTA have a similar accuracy in detecting proximal coronary stenosis. The clinical impact of identification of proximal disease in patients with stable CAD needs to be examined in future studies. Copyright © 2012. Published by Elsevier Ireland Ltd.

  1. Learning curve of office-based ultrasonography for rotator cuff tendons tears.

    PubMed

    Ok, Ji-Hoon; Kim, Yang-Soo; Kim, Jung-Man; Yoo, Tae-Wook

    2013-07-01

    To compare the accuracy of ultrasonography and MR arthrography (MRA) imaging in detecting of rotator cuff tears with arthroscopic finding used as the reference standard. The ultrasonography and MRA findings of 51 shoulders that underwent the arthroscopic surgery were prospectively analysed. Two orthopaedic doctors independently performed ultrasonography and interpreted the findings at the office. The tear size measured at ultrasonography and MRA was compared with the size measured at surgery using Pearson correlation coefficients (r). The sensitivity, specificity, accuracy, positive predictive value, negative predictive value and false-positive rate were calculated for a diagnosis of partial-and full-thickness rotator cuff tears. The kappa coefficient was calculated to verify the inter-observer agreement. The sensitivity of ultrasonography and MRA for detecting partial-thickness tears was 45.5 and 72.7 %, and that for full-thickness tears was 80.0 and 100 %, respectively. The accuracy of ultrasonograpy and MRA for detecting partial-thickness tears was 45.1 and 88.2 %, and that for full-thickness tears was 82.4 and 98 %, respectively. Tear size measured based on ultrasonography examination showed a poor correlation with the size measured at arthroscopic surgery (r = 0.21; p < 0.05). However, tear size estimated by MRA showed a strong correlation (r = 0.75; p < 0.05). The kappa coefficient was 0.47 between the two independent examiners. The accuracy of office-based ultrasonography for beginner orthopaedic surgeons to detect full-thickness rotator cuff tears was comparable to that of MRA but was less accurate for detecting partial-thickness tears and torn size measurement. Inter-observer agreement on the interpretation was fair. These results highlight the importance of the correct technique and experience in operation of ultrasonography in shoulder joint. Diagnostic study, Level II.

  2. ECG-triggered non-enhanced MR angiography of peripheral arteries in comparison to DSA in patients with peripheral artery occlusive disease.

    PubMed

    Partovi, Sasan; Rasmus, Matthias; Schulte, Anja-Carina; Rengier, Fabian; Jacob, Augustinus Ludwig; Aschwanden, Markus; Karmonik, Christof; Bongartz, Geog; Bilecen, Deniz

    2013-06-01

    The purpose of this study was to evaluate peripheral non-enhanced-MRA (NE-MRA) acquired with a 3D Turbo Spin Echo sequence with electrocardiographt (ECG) triggering in comparison to Digital Subtraction Angiography (DSA) as the gold standard in symptomatic peripheral artery occlusive disease (PAOD) patients. This IRB approved prospective study included 23 PAOD patients from whom three patients had to be excluded. The remaining 20 subjects were included in the analysis (15 male; mean age 62.4 ± 15.3 years). The patients first underwent DSA followed by NE-MRA on a 1.5-T whole body scanner within 24 h after the DSA study. A NATIVE (Non-contrast Angiography of the Arteries and Veins) SPACE (Sampling Perfection with Application Optimized Contrast by using different flip angle Evolution) sequence at four levels (pelvis, upper leg, knee region and lower leg) was acquired. For evaluation purposes, subtracted standardized MIP (maximum intensity projection) images were generated from the NE-MRA data sets. Qualitative assessment of NE-MRA images in reference to the corresponding DSA images, as well as blinded stenosis grading of preselected segments in NE-MRA images were performed by two experienced readers. Image quality in 95 corresponding arterial segments was rated from 1 (good) to 4 (inadequate) directly comparing the NE-MRA with the corresponding DSA segment as the gold standard. Blinded stenosis grading consisted of 66 preselected stenoses rated from 1 (<10 %) to 4 (>90 %) in NE-MRA which were compared to the grade in the corresponding DSA. The mean image quality of NE-MRA in comparison to DSA was 2.7 ± 1.1 (reader 1) and 3.0 ± 1.0 (reader 2). The kappa value indicating interobserver agreement was 0.34; readers 1 and 2 rated the image quality as good in 21 % and 3 %, sufficient in 19 % and 41 %, limited in 29 % and 14 % and inadequate in 31 % and 42 %, respectively. Stenosis graduation revealed significantly higher grades in NE-MRA (reader 1: 3.0

  3. The increased use of computed tomography angiography and magnetic resonance angiography as the sole imaging modalities prior to infrainguinal bypass has had no effect on outcomes.

    PubMed

    Shue, Bing; Damle, Rachelle N; Flahive, Julie; Kalish, Jeffrey A; Stone, David H; Patel, Virendra I; Schanzer, Andres; Baril, Donald T

    2015-08-01

    Angiography remains the gold standard imaging modality before infrainguinal bypass. Computed tomography angiography (CTA) and magnetic resonance angiography (MRA) have emerged as noninvasive alternatives for preoperative imaging. We sought to examine contemporary trends in the utilization of CTA and MRA as isolated imaging modalities before infrainguinal bypass and to compare outcomes following infrainguinal bypass in patients who underwent CTA or MRA versus those who underwent conventional arteriography. Patients undergoing infrainguinal bypass within the Vascular Study Group of New England were identified (2003-2012). Patients were stratified by preoperative imaging modality: CTA/MRA alone or conventional angiography. Trends in utilization of these modalities were examined and demographics of these groups were compared. Primary end points included primary patency, secondary patency, and major adverse limb events (MALE) at 1 year as determined by Kaplan-Meier analysis. Multivariable Cox proportional hazards models were constructed to evaluate the effect of imaging modality on primary patency, secondary patency, and MALE after adjusting for confounders. In 3123 infrainguinal bypasses, CTA/MRA alone was used in 462 cases (15%) and angiography was used in 2661 cases (85%). Use of CTA/MRA alone increased over time, with 52 (11%) bypasses performed between 2003 and 2005, 189 (41%) bypasses performed between 2006 and 2009, and 221 (48%) bypasses performed between 2010 and 2012 (P < 0.001). Patients with CTA/MRA alone, compared with patients with angiography, more frequently underwent bypass for claudication (33% vs. 26%, P = 0.001) or acute limb ischemia (13% vs. 5%, P < 0.0001), more frequently had prosthetic conduits (39% vs. 30%, P = 0.001), and less frequently had tibial/pedal targets (32% vs. 40%, P = 0.002). After adjusting for these and other confounders, multivariable analysis demonstrated that the use of CTA/MRA alone was not associated with a significant

  4. 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

  5. Foods contributing to absolute intake and variance in intake of selected vitamins, minerals and dietary fiber in middle-aged Japanese.

    PubMed

    Imaeda, N; Tokudome, Y; Ikeda, M; Kitagawa, I; Fujiwara, N; Tokudome, S

    1999-10-01

    Using 351 one-day weighted diet records, we selected foods providing vitamins, minerals and dietary fiber according to contribution analysis (CA) and multiple regression analysis (MRA). Vitamin C was supplied by various vegetables and fruits, and carotene was specifically derived from green-yellow vegetables based on MRA as well as CA. Vitamin A was provided by green-yellow vegetables, fruits, chicken egg and milk (whole) according to CA; whereas chicken liver and pork liver were major sources according to MRA. Vitamin E was mainly of vegetable origin as determined by CA, and largely of spinach, safflower oil and pumpkin as determined by MRA. Vitamin D was mainly derived from chicken egg, fish and mushroom based on CA, and particularly from fish based on MRA. Calcium was supplied by milk (whole), soy products and chicken egg as determined by CA; while milk, tofu and various small fishes were the main contributors to variance. Magnesium was provided by soy products, well-milled rice and spinach according to both analyses, and iron by chicken egg, spinach and soy products. Zinc was largely derived from well-milled rice, followed by chicken egg and milk (whole) as determined by CA, and copper was provided by well-milled rice, soy and wheat products. Dietary fiber was supplied by vegetable sources, whether water soluble or insoluble, based on both analytic methods.

  6. Off-resonance-robust velocity-selective magnetization preparation for non-contrast-enhanced peripheral MR angiography.

    PubMed

    Shin, Taehoon; Hu, Bob S; Nishimura, Dwight G

    2013-11-01

    To develop a new velocity-selective (VS) excitation pulse sequence which is robust to field inhomogeneity, and demonstrate its application to non-contrast-enhanced peripheral MR angiography (MRA). The off-resonance-robust VS saturation pulse is designed by incorporating 180° refocusing pulses into the k-space-based reference design and tailoring sequence parameters in a velocity region of interest. The VS saturation pulse is used as magnetization preparation for non-contrast-enhanced peripheral MRA to suppress background tissues but not arterial blood based on their velocities. Non-contrast-enhanced peripheral MRA using the proposed VS preparation was tested in healthy volunteers and a patient with arterial stenosis. Calf angiograms obtained using the new VS preparation show more uniform background suppression than the reference VS preparation, as demonstrated by larger mean values and smaller standard deviations of artery-to-vein and artery-to-muscle contrast-to-noise ratios (71.0 ± 11.4 and 75.3 ± 12.1 versus 61.7 ± 22.7 and 58.5 ± 27.8). Two-station peripheral MRA using the new VS preparation identifies stenosis of the femoral and popliteal arteries in the patient, as validated by digital subtraction angiography. Non-contrast-enhanced MRA using the new VS magnetization preparation can reliably provide high angiographic contrast in the lower extremities with significantly improved immunity to field inhomogeneity. Copyright © 2012 Wiley Periodicals, Inc.

  7. 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.

  8. 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

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

    PubMed

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

    2015-06-03

    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.

  10. Shuttle vectors derived from pN315 for study of essential genes in Staphylococcus aureus.

    PubMed

    Matsuo, Miki; Kurokawa, Kenji; Lee, Bok-Luel; Sekimizu, Kazuhisa

    2010-01-01

    Using the par to rep region of the 24653 bp plasmid pN315, which is present in Staphylococcus aureus strain N315, we constructed three vectors that can be shuttled between Escherichia coli and S. aureus and maintained stably in S. aureus. Due to plasmid incompatibility, the resident plasmid in S. aureus cells can be replaced via transformation with an entering plasmid, which carries a different drug resistance gene. To evaluate the applicability of this plasmid-based approach for identifying genes essential for S. aureus cell growth, the chromosomal mraY gene, which is involved in peptidoglycan biosynthesis, was deleted in cells harboring a resident plasmid with an intact mraY gene. The resultant disruptant was then transformed with an empty vector. Cells with a chromosomal mraY deletion but lacking the plasmid supplying mraY could not be recovered, suggesting that mraY is indispensable for staphylococcal cell growth or viability. In contrast, other two genes were shown to be dispensable by this system. Thus, the pN315-based plasmids appear to be useful for studying genes essential for S. aureus cell growth.

  11. 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

  12. Multiresolution analysis of characteristic length scales with high-resolution topographic data

    NASA Astrophysics Data System (ADS)

    Sangireddy, Harish; Stark, Colin P.; Passalacqua, Paola

    2017-07-01

    Characteristic length scales (CLS) define landscape structure and delimit geomorphic processes. Here we use multiresolution analysis (MRA) to estimate such scales from high-resolution topographic data. MRA employs progressive terrain defocusing, via convolution of the terrain data with Gaussian kernels of increasing standard deviation, and calculation at each smoothing resolution of (i) the probability distributions of curvature and topographic index (defined as the ratio of slope to area in log scale) and (ii) characteristic spatial patterns of divergent and convergent topography identified by analyzing the curvature of the terrain. The MRA is first explored using synthetic 1-D and 2-D signals whose CLS are known. It is then validated against a set of MARSSIM (a landscape evolution model) steady state landscapes whose CLS were tuned by varying hillslope diffusivity and simulated noise amplitude. The known CLS match the scales at which the distributions of topographic index and curvature show scaling breaks, indicating that the MRA can identify CLS in landscapes based on the scaling behavior of topographic attributes. Finally, the MRA is deployed to measure the CLS of five natural landscapes using meter resolution digital terrain model data. CLS are inferred from the scaling breaks of the topographic index and curvature distributions and equated with (i) small-scale roughness features and (ii) the hillslope length scale.

  13. Stereoelectroencephalography Using Magnetic Resonance Angiography for Avascular Trajectory Planning: Technical Report.

    PubMed

    Minkin, Krasimir; Gabrovski, Kaloyan; Penkov, Marin; Todorov, Yuri; Tanova, Rositsa; Milenova, Yoana; Romansky, Kiril; Dimova, Petia

    2017-10-01

    Stereoelectroencephalography (SEEG) requires high-quality angiographic studies because avascular trajectory planning is a prerequisite for the safety of this procedure. Some epilepsy surgery groups have begun to use computed tomography angiography and magnetic resonance T1-weighted sequence with contrast enhancement for this purpose. To present the first series of patients with avascular trajectory planning of SEEG based on magnetic resonance angiography (MRA). Thirty-six SEEG explorations for drug-resistant focal epilepsy were performed from January 2013 to December 2015. A retrospective analysis of this consecutive surgical series was then performed. Magnetic resonance imaging included MRA with a modified contrast-enhanced magnetic resonance venography (MRV) protocol with a short acquisition delay, which allowed simultaneous arterial and venous visualization. Our criteria for satisfactory MRA were the visualization of at least first-order branches of the angular artery, paracentral and calcarine artery, and third-order tributaries of the superficial Sylvian vein, vein of Labbe, and vein of Trolard. Thirty-four patients underwent 36 SEEG explorations with 369 electrodes carrying 4321 contacts. Contrast-enhanced MRA using the MRV protocol was judged satisfactory for SEEG planning in all explorations. Postoperative complications were not observed in our series of 36 SEEG explorations, which included 50 transopercular insular trajectories. MRA using an MRV protocol may be applied for avascular trajectory planning during SEEG procedures. This technique provides a simultaneous visualization of cortical arteries and veins without the need for additional radiation exposure or intra-arterial catheter placement.

  14. Quiescent-Inflow Single-Shot (QISS) Magnetic Resonance Angiography using a Highly Undersampled Radial K-Space Trajectory

    PubMed Central

    Edelman, RR; Giri, S; Dunkle, E; Galizia, M; Amin, P; Koktzoglou, I

    2012-01-01

    Purpose We hypothesized that high undersampling factors could be used in conjunction with radial Quiescent-Inflow Single-Shot (QISS) MRA in order to accelerate the data acquisition and enable multi-slice acquisitions. Methods Seven subjects were imaged on a 1.5T MRI system. For multi-slice QISS MRA, the venous saturation RF pulse, in-plane saturation RF pulse, and QI were applied only once prior to the first slice. Results The mean (standard deviation) measurements for the intra-arterial signal-to-noise ratio were: Cartesian 1 slice - 29.3(5.5); Radial 1 slice, 92 views - 22.3(3.6); Radial 1 slice, 46 views - 18.5(2.0); Radial 2 slices, 46 views - 18.3(3.2); Radial 3 slices, 32 views - 21.7(3.9), normalized for pixel size to 15.8. Horizontal striping was present with multi-slice radial QISS MRA (especially with the 3-slice acquisition) due to variable T1 relaxation between the concurrently acquired slices, but the image quality remained diagnostic. Vascular pathology in patients with peripheral arterial disease was well shown by all techniques. Conclusion Very high undersampling factors in excess of 18 have been demonstrated for nonenhanced MRA using a radial QISS technique, enabling the acquisition of 2 to 3 slices per cardiac cycle. Scan time for a complete peripheral MRA could be shortened to 2 minutes or less. PMID:23348595

  15. Comparison Between 3D TOF Magnetic Resonance Angiography and Intraarterial Digital Subtraction Angiography in Imaging the Circle of Willis

    PubMed Central

    Ghazali, Rozita Mohd; Shuaib., Ibrahim Lutfi

    2003-01-01

    This study was done compare the accuracy of non-contrast enhanced 3D time of flight magnetic resonance angiography (3D TOF MRA) with intraarterial digital subtraction angiography (IADSA) in depicting the arterial segments of the circle of Willis. 398 arterial segments were analysed from 38 patients who underwent both non-contrast enhanced 3D TOF MRA and IADSA examinations in Hospital Universiti Sains Malaysia from November 1998 to December 2000. Two observers performed blinded retrospective analysis of the IADSA images and Maximum Intensity Projection display of the 3D TOF MRA of the circle of Willis on separate sessions. Non-contrast enhanced 3D TOF MRA was sensitive and specific in depicting the A1, A2, M1, P1 and Anterior Communicating segments of the circle of Willis with a sensitivity ranging from 94.5% to 100% and specificity ranging from 90.5% to 100%. However it was poor in depicting the Posterior Communicating segments with a sensitivity of 21.4%. MIP display of the non-contrast enhanced 3D TOF MRA is sensitive in depicting the anatomy of the circle of Willis except for the PCOM segment. It is thus a reliable method for screening of this arterial circle. PMID:23365498

  16. Comparison of conventional magnetic resonance imaging and nonenhanced three dimensional time-of-flight magnetic resonance angiography findings between dogs with meningioma and dogs with intracranial histiocytic sarcoma: 19 cases (2010-2014).

    PubMed

    Ishikawa, Chieko; Ito, Daisuke; Kitagawa, Masato; Watari, Toshihiro

    2016-05-15

    OBJECTIVE To compare conventional MRI and nonenhanced 3-D time-of-flight (TOF) magnetic resonance angiography (MRA) findings between dogs with meningioma and dogs with intracranial histiocytic sarcoma (IHS). DESIGN Retrospective case series. ANIMALS 14 dogs with meningioma and 5 dogs with IHS. PROCEDURES Medical records of dogs with meningioma or IHS that were examined at a tertiary veterinary hospital from 2010 through 2014 and underwent 3-D TOF MRA in conjunction with conventional MRI were reviewed. Findings for conventional MRI and 3-D TOF MRA were compared between the 2 groups of dogs to evaluate whether there were any characteristics that could be used to differentiate meningioma from IHS. RESULTS Tumor type was significantly associated with signal intensity on conventional T2-weighted and fluid-attenuated inversion recovery MRI images; most meningiomas were hyperintense, and most IHSs were isointense or hypointense on those images. Tumor type was not associated with signal uniformity, tumor location, tumor origin, or the presence of edema, midline shift, or brain herniation. On MRA, blood vessels adjacent to the tumor were identified and characterized for 9 of 14 dogs with meningioma and all 5 dogs with IHS. Vessels adjacent to meningiomas were displaced in 8 of 9 dogs, whereas vessels adjacent to IHSs were not displaced. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated nonenhanced 3-D TOF MRA findings provided additional information that can be assessed in conjunction with conventional MRI findings to help differentiate meningiomas from IHSs in dogs.

  17. A Comparison of Conventional Ultrasonography and Arthrosonography in the Assessment of Cuff Integrity after Rotator Cuff Repair

    PubMed Central

    Lee, Kwang Won; Chun, Tong Jin; Bae, Kyoung Wan; Choy, Won Sik; Park, Hyeon Jong

    2014-01-01

    Background This study was designed to perform conventional ultrasonography, magnetic resonance arthrography (MRA) and arthrosonography exams after rotator cuff repair to compare the results of conventional ultrasonography and arthrosonography with those of MRA as the gold standard. Methods We prospectively studied 42 consecutive patients (14 males, 28 females; average age, 59.4 years) who received arthroscopic rotator cuff repair due to full-thickness tears of the supraspinatus tendon from 2008 to 2010. The integrity assessment of the repaired rotator cuff was performed 6 months postoperatively using conventional ultrasonography, MRA, and arthrosonography. Results The diagnostic accuracy of the conventional ultrasonography compared to MRA was 78.6% and the McNemar test results were 0.016 in full-thickness tear and 0.077 in partial-thickness tear. The diagnostic accuracy of arthrosonography compared to MRA was 92.9% and the McNemar test results were 0.998 in full-thickness tear and 0.875 in partial-thickness tear. Conclusions It was found that the integrity assessment of the repaired rotator cuff by ultrasonography must be guarded against and that arthrosonography is an effective alternative method in the postoperative integrity assessment. Also, an arthrosonography seems to be a suitable modality to replace the conventional ultrasonography. PMID:25177461

  18. 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.

  19. Jugular venous reflux on magnetic resonance angiography and radionuclide venography

    PubMed Central

    Okada, Tomohisa; Okuchi, Sachi; Yamamoto, Akira; Kanagaki, Mitsunori; Fujimoto, Koji; Togashi, Kaori

    2016-01-01

    Background The relationship between the signal from retrograde venous flow on magnetic resonance angiography (MRA) and retrograde upward flow from the left brachiocephalic vein has not been explored. Purpose To reveal the frequency of jugular venous reflux using MRA and nuclear venography in patients being evaluated for cerebral volume and blood flow. Material and Methods A total of 229 patients with cognitive disturbance who had undergone brain magnetic resonance imaging (MRI) and single-photon emission computed tomography (SPECT) on the same day to evaluate cerebral blood flow were evaluated. Jugular venous reflux was measured on MRA and nuclear venography, which was conducted just after injection of N-isopropyl-123I-p-iodoamphetamine for the SPECT study. Results MRA showed jugular reflux in seven patients on the right side, and in 22 on the left. Nuclear venography showed jugular reflux in six patients on the right side, and in 20 on the left. Conclusion Jugular venous reflux was observed mostly on the left side. Retrograde flow was observed on both MRA and nuclear venography in half of the cases, with the rest only on one of the modalities. PMID:27994882

  20. Comparison of computed tomographic angiography and noncontrast magnetic resonance angiography in preoperative evaluation of living renal donors

    PubMed Central

    Patil, Abhijit Dnyandeo; Shailage, K.; Nadarajah, Jeyaseelan; Harigovind, P.; Mohan, R. Krishna

    2017-01-01

    Introduction: The computed tomographic angiography (CTA) renal donor protocol is an established method of preoperative renal vascular pedicle evaluation in prospective renal donors. However, CTA is associated with significant radiation exposure and intravenous contrast administration. The newer noncontrast-enhanced magnetic resonance angiography (NCE-MRA) techniques, especially arterial spin labeling (ASL) with steady-state free precession (SSFP) hold promise as an effective alternative. We prospectively compared CTA with NCE MRA for accuracy in the evaluation of renal arterial anatomy in prospective renal donors. Methods: A total of 43 subjects underwent CTA followed by NCE MRA in a prospective comparative study. The number of renal arteries and early branching of renal arteries were noted in both kidneys in all subjects. Intermodality agreement was calculated using “K” (Kappa) statistics and 95% confidence interval for both modalities. Results: A total of 63 single, 21 double, and 2 triple arteries were detected in 43 subjects on CTA. CTA showed an early branch in 17 kidneys. NCE MRAshowed 64 single arteries, 20 double arteries, and 2 triple arteries. A total of 14 kidneys showed an early branch. Unweighted Kappa statistic of agreement between CTA and NCE MRA for number of renal arteries and for frequency of early branching was 0.9707 and 0.8822, respectively. Conclusions: The newer NCE MRA techniques such as ASL with SSFP among others are potential alternatives for CTA, in the evaluation of prospective renal donors. PMID:28197027

  1. Contrast-enhanced magnetic resonance angiography in carotid artery disease: does automated image registration improve image quality?

    PubMed

    Menke, Jan; Larsen, Jörg

    2009-05-01

    Contrast-enhanced magnetic resonance angiography (MRA) is a noninvasive imaging alternative to digital subtraction angiography (DSA) for patients with carotid artery disease. In DSA, image quality can be improved by shifting the mask image if the patient has moved during angiography. This study investigated whether such image registration may also help to improve the image quality of carotid MRA. Data from 370 carotid MRA examinations of patients likely to have carotid artery disease were prospectively collected. The standard nonregistered MRAs were compared to automatically linear, affine and warp registered MRA by using three image quality parameters: the vessel detection probability (VDP) in maximum intensity projection (MIP) images, contrast-to-noise ratio (CNR) in MIP images, and contrast-to-noise ratio in three-dimensional image volumes. A body shift of less than 1 mm occurred in 96.2% of cases. Analysis of variance revealed no significant influence of image registration and body shift on image quality (p > 0.05). In conclusion, standard contrast-enhanced carotid MRA usually requires no image registration to improve image quality and is generally robust against any naturally occurring body shift.

  2. 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.

  3. [Feasibility of non-contrast enhanced magnetic resonance angiography for diagnosis of renal artery stenosis in elderly patients].

    PubMed

    Xu, Xian; An, Ningyu; Chen, Suihui; Li, Xue; Jiang, Bo; Han, Shaojun; Liu, Xinqiu

    2014-01-01

    To evaluate the diagnostic efficacy of IFIR-FIESTA technique in detecting renal artery stenosis in elderly patients. Twenty-seven aged patients underwent both IFIR-FIESTA and 3D CE-MRA examinations. The imaging quality and renal artery stenosis grades were evaluated. Kappa test was used to assess the consistency between the two methods. With CE-MRA as the reference, the diagnostic sensitivity, specificity, accuracy, PPV and NPV for IFIR-FIESTA were calculated in detecting renal artery stenosis. The images by the two methods were 100% qualified for diagnosis, although the image quality of CE-MRA was significantly better. IFIR-FIESTA and CE-MRA showed excellent consistency in detecting renal artery stenosis. With CE-MRA as the reference, the diagnostic sensitivity, specificity, accuracy, PPV and NPV for IFIR-FIESTA were 97.1%, 100%, 98.1%, 100%, and 95% in detecting renal artery stenosis, respectively. IFIR-FIESTA is feasible as a routine examination for detecting renal artery stenosis in elderly patients.

  4. Effects of Metmyoglobin Reducing Activity and Thermal Stability of NADH-Dependent Reductase and Lactate Dehydrogenase on Premature Browning in Ground Beef.

    PubMed

    Djimsa, Blanchefort A; Abraham, Anupam; Mafi, Gretchen G; VanOverbeke, Deborah L; Ramanathan, Ranjith

    2017-02-01

    Premature browning is a condition wherein ground beef exhibits a well-done appearance before reaching the USDA recommended internal cooked meat temperature of 71.1 °C; however, the mechanism is unclear. The objectives of this study were: (1) to determine the effects of packaging and temperature on metmyoglobin reducing activity (MRA) of cooked ground beef patties and (2) to assess the effects of temperature and pH on thermal stability of NADH-dependent reductase, lactate dehydrogenase (LDH), and oxymyoglobin (OxyMb) in-vitro. Beef patties (lean: fat = 85:15) were packaged in high-oxygen modified atmosphere (HiOX-MAP) or vacuum (VP) and cooked to either 65 or 71 °C. Internal meat color and MRA of both raw and cooked patties were determined. Purified NADH-dependent reductase and LDH were used to determine the effects of pH and temperature on enzyme activity. MRA of cooked patties was temperature and packaging dependent (P < 0.05). Vacuum packaged patties cooked to 71 °C had greater (P < 0.05) MRA than HiOX-MAP counterparts. Thermal stability of OxyMb, NADH-dependent reductase, and LDH were different and pH-dependent. LDH was able to generate NADH at 84 °C; whereas NADH-dependent reductase was least stable to heat. The results suggest that patties have MRA at cooking temperatures, which can influence cooked meat color.

  5. 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.

  6. Re-Epithelialization of Pathological Cutaneous Wounds Is Improved by Local Mineralocorticoid Receptor Antagonism.

    PubMed

    Nguyen, Van Tuan; Farman, Nicolette; Maubec, Eve; Nassar, Dany; Desposito, Dorinne; Waeckel, Ludovic; Aractingi, Sélim; Jaisser, Frederic

    2016-10-01

    Impaired cutaneous wound healing is a social burden. It occurs as a consequence of glucocorticoid treatment in several pathologies. Glucocorticoids (GC) bind not only to the glucocorticoid receptor but also to the mineralocorticoid receptor (MR), both expressed by keratinocytes. In addition to its beneficial effects through the glucocorticoid receptor, GC exposure may lead to inappropriate MR occupancy. We hypothesized that dermatological use of MR antagonists (MRA) might be beneficial by overcoming the negative impact of GC treatment on pathological wounds. The potent GC clobetasol, applied as an ointment to mouse skin, or added to cultured human skin explants, induced delayed wound closure and outgrowth of epidermis with reduced proliferation of keratinocytes. Delayed wound re-epithelialization was rescued by local MRA application. Normal skin was unaffected by MRA. The benefit of MR blockade is explained by the increased expression of MR in clobetasol-treated mouse skin. Blockade of the epithelial sodium channel by phenamil also rescued cultured human skin explants from GC-impaired growth of the epidermis. MRA application over post-biopsy wounds of clobetasol-treated skin zones of healthy volunteers (from the Interest of Topical Spironolactone's Administration to Prevent Corticoid-induced Epidermal Atrophy clinical trial) also accelerated wound closure. In conclusion, we propose repositioning MRA for cutaneous application to improve delayed wound closure occurring in pathology.

  7. 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

  8. Posttraumatic innominate artery aneurysm with occlusion of the common carotid artery at its origin by an intimal flap.

    PubMed

    Edwards, J D; Sapienza, P; Lefkowitz, D M; Thorpe, P E; McGregor, P E; Agrawal, D K; Samocha, M S

    1993-07-01

    Blunt trauma involving the innominate and carotid arteries is a rare occurrence that can be lethal or have serious neurologic sequelae. To our knowledge this is the first reported case in the international literature describing the association of posttraumatic innominate artery aneurysm with total occlusion and thrombosis of the common carotid artery at its origin by an intimal flap. The diagnostic problems created by this unusual injury are discussed. In this case the patency of the distal portion of the common and internal carotid arteries was demonstrated by magnetic resonance angiography (MRA), whereas color duplex and digital arteriographic studies were unsuccessful. This demonstration was crucial to patient management. Since no studies are available comparing color duplex imaging, conventional arteriography, and MRA in the evaluation of blunt carotid trauma, this case study is presented to demonstrate the utility of MRA in emergency situations. In addition, we analyze the possible pathogenesis and discuss the surgical treatment.

  9. Gadofosveset-enhanced magnetic resonance angiography

    PubMed Central

    Goyen, Mathias

    2008-01-01

    Gadofosveset (Vasovist®, Bayer Schering Pharma AG, Berlin/Germany) is the first intravascular contrast agent approved for use with magnetic resonance angiography in the European Union, Switzerland, Turkey, Canada, and Australia. Gadofosveset reversibly binds to albumin providing extended intravascular enhancement compared wth existing extracellular magnetic resonance contrast agents. Prior to approval, gadofosveset underwent extensive testing to evaluate the safety and efficacy of the drug; the clinical trials show that gadofosveset-enhanced magnetic resonance angiography (MRA) is safe and well tolerated in patients with vascular disease and effective for the detection of vascular stenosis and aneurysms gadofosveset has the potential to open new horizons in diagnostic MRA by increasing the spatial resolution and the robustness of MRA examinations and facilitating the examination of multiple vascular beds. PMID:18629367

  10. MR-angiography: the role of contrast agents.

    PubMed

    Goyen, M; Ruehm, S G; Debatin, J F

    2000-06-01

    Contrast-enhanced 3D MR angiography (MRA) permits comprehensive assessment of the supraaortic arteries as well as the arterial system in the chest, abdomen and lower extremities. 3D MRA combines intravenous injection of a non-nephrotoxic, paramagnetic, extracellular contrast agent that increases the signal intensity of blood by shortening its T1 value with the acquisition of a fast 3D data set. High contrast between the vascular lumen and surrounding tissues, inherent three-dimensionality and the ability to collect image data in the chest and abdomen under apnea conditions all contribute to excellent image quality. This review provides clinical applications of 3D MRA in the chest, abdomen and lower extremities based upon the available literature and several clinical examples.

  11. Long-term observation of lateral medullary infarction due to vertebral artery dissection assessed with multimodal neuroimaging.

    PubMed

    Nomura, Koichi; Mishina, Masahiro; Okubo, Seiji; Suda, Satoshi; Katsura, Ken-ichiro; Katayama, Yasuo

    2015-01-01

    A 33-year-old man presented with a lateral medullary infarction, vertigo, and nausea. At the time of hospital admission, he had Wallenberg syndrome. Although initial magnetic resonance imaging showed no abnormalities, subsequent diffusion-weighted magnetic resonance imaging showed a high-intensity area in the right lateral medulla oblongata. The right vertebral artery was shown to be dilated on basi-parallel anatomical scanning but to be stenosed on magnetic resonance angiography (MRA). Cerebral angiography 7 days after onset showed the "pearl and string sign" in the right vertebral artery. Follow-up MRA showed gradual improvement of the stenosis in the right vertebral artery. Multiple neuroimaging studies, such as MRA, basi-parallel anatomical scanning, 3-dimensional computed tomographic angiography, and cerebral angiography, should be performed soon after onset in suspected cases of cerebral artery dissection. In addition, serial imaging examinations increase diagnostic accuracy, and the medical history and neurological examination are important.

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

    PubMed

    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

    2012-11-01

    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.

  13. Properties of Non-Structural Concrete Made with Mixed Recycled Aggregates and Low Cement Content

    PubMed Central

    López-Uceda, Antonio; Ayuso, Jesús; López, Martin; Jimenez, José Ramón; Agrela, Francisco; Sierra, María José

    2016-01-01

    In spite of not being legally accepted in most countries, mixed recycled aggregates (MRA) could be a suitable raw material for concrete manufacturing. The aims of this research were as follows: (i) to analyze the effect of the replacement ratio of natural coarse aggregates with MRA, the amount of ceramic particles in MRA, and the amount of cement, on the mechanical and physical properties of a non-structural concrete made with a low cement content; and (ii) to verify if it is possible to achieve a low-strength concrete that replaces a greater amount of natural aggregate with MRA and that has a low cement content. Two series of concrete mixes were manufactured using 180 and 200 kg/m3 of CEM II/A-V 42.5 R type Portland cement. Each series included seven concrete mixes: one with natural aggregates; two MRA with different ceramic particle contents; and one for each coarse aggregate replacement ratio (20%, 40%, and 100%). To study their properties, compressive and splitting tensile strength, modulus of elasticity, density, porosity, water penetration, and sorptivity, tests were performed. The results confirmed that the main factors affecting the properties analyzed in this research are the amount of cement and the replacement ratio; the two MRAs used in this work presented a similar influence on the properties. A non-structural, low-strength concrete (15 MPa) with an MRA replacement ratio of up to 100% for 200 kg/m3 of cement was obtained. This type of concrete could be applied in the construction of ditches, sidewalks, and other similar civil works. PMID:28787874

  14. Effect of a new remineralizing biomaterial on the color of dental enamel.

    PubMed

    Vargas-Sánchez, Paula K; Delgado-Mejía, Edgar; Torres-Rodríguez, Carolina

    2014-01-01

    The aim of this research was to describe the effects of altering the composition of a modified remineralizing agent (MRA) and the osmotic pressure on tooth color by using spectrophotometric analysis. One hundred and four (104) human premolars and molars were randomly divided into 2 groups of 52 specimens each. Group 1 was treated with the remineralizing agent MRA 55, (remineralizing agent 1), a 50% - 50% by weight mixture of coarse-grain and fine-grain generating minerals, and group 2 was treated with the remineralizing agent MRA 91 (remineralizing agent 2), containing the same minerals in a 90% - 10% proportion. Each group was divided into 2 subgroups with 26 specimens each, which were stored as follows: subgroups A were stored in synthetic saliva with isotonic osmotic pressure (IP), and subgroups B in hypotonic osmotic pressure saliva (HP). The initial and final readings were taken with a Vita Easy Shade spectrophotometer. Color parameters (L*, a*, b*) and whiteness indices (WIC, WIO, W) were calculated from the readings. The color changes (deltaL, deltaA, deltaB, and deltaE) and whiteness indices were compared and analyzed with descriptive analyses. The variables deltaL, deltaA, deltaB, deltaE, and the whiteness index W were analyzed with an analysis of variance (ANOVA), and the indices WIC and WIO were analyzed with a nonparametric Kruskal-Wallis ANOVA. The results indicate that combination A2 (MRA 91 and IP) affected variables deltaB and deltaE, while combination B1 (MRA 55 and HP) affected variables deltaA, deltaB and the whiteness index WIO. Only MRA 91 affected the variable deltaL. The osmotic pressure of saliva and the remineralizing agent used affect the color of dental enamel.

  15. Diagnostic ability of 3-dimensional contrast-enhanced MR angiography in identifying vertebral basilar artery stenosis.

    PubMed

    Yi, Ting-yu; Chen, Wen-huo; Zhang, Mei-fang; Chen, Yue-hong; Cai, Ruo-wei; Wu, Zong-zhong; Wu, Yan-min; Shi, Yan-chuan; Chen, Bai-ling; Guo, Ting-hui; Wu, Chao-xin; Yang, Miao-xiong; Chen, Xue-jiao

    2016-04-15

    Vertebral-basilar artery stenosis is associated with posterior circulation infarction. So correct detection of vertebral basilar artery stenosis is very important. Studies concerning the sensitivity and specificity of 3-dimensional contrast enhanced MR angiography (3D-CE-MRA) in detecting vertebral basilar artery stenosis is generally lacking. Retrospectively reviewed the imagines of consecutive one hundred and forty-nine Chinese patients with ischemic stroke or vertigo/dizziness who underwent 3D-CE-MRA and DSA. DSA and CE-MRA images were studied separately and to determine the presence of mild, moderate, or severe stenosis of the vertebral-basilar arteries. Analysis combined with vascular origin image was applied when evaluating the vertebral artery origin stenosis. Sensitivity, specificity, positive and negative predictive values, and the accuracy of 3D-CE-MRA in detecting and grading of vertebral-basilar artery stenosis were calculated. Compared with DSA, sensitivity, specificity and accuracy of 3D-CE-MRA in detecting of vertebral artery origin ≥70% stenosis or occlusion was 97.1%, 77.4% and 81.9%, but diagnostic consistency was poor (K=0.59); Analysis combined with vascular origin images, the specificity (97.8%), accuracy (92.9%) and consistency (K=0.826) was significantly improved. 3D-CE-MRA is a sensitive and noninvasive technique for the detection of vertebral artery origin stenosis. Furthermore, analysis combined with vascular origin image would improve the diagnostic accuracy. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Simultaneous noncontrast angiography and intraplaque hemorrhage (SNAP) imaging: Comparison with contrast-enhanced MR angiography for measuring carotid stenosis.

    PubMed

    Shu, Hongge; Sun, Jie; Hatsukami, Thomas S; Balu, Niranjan; Hippe, Daniel S; Liu, Haining; Kohler, Ted R; Zhu, Wenzhen; Yuan, Chun

    2017-02-06

    To evaluate in a proof-of-concept study the feasibility of Simultaneous Noncontrast Angiography and intraPlaque hemorrhage (SNAP) imaging as a clinical magnetic resonance angiography (MRA) technique for measuring carotid stenosis. There is a growing interest in detecting intraplaque hemorrhage (IPH) during the clinical management of carotid disease, yet luminal stenosis has remained indispensable during clinical decision-making. SNAP imaging has been proposed as a novel IPH imaging technique that provides carotid MRA with no added scan time. Flowing blood shows negative signal on SNAP because of phase-sensitive inversion recovery. In all, 58 asymptomatic subjects with 16-79% stenosis on ultrasound were scanned at 3T by SNAP with 0.8 mm isotropic resolution and 16 cm longitudinal coverage. Two readers measured luminal stenosis of bilateral carotid arteries (n = 116) on minimum intensity projections of SNAP using the NASCET criteria. In the subset (48 arteries) with contrast-enhanced (CE) MRA available for comparison, luminal stenosis was also measured on maximum intensity projections of CE-MRA. Intraclass correlation coefficients (ICCs) with 95% confidence intervals were 0.94 (0.90-0.96) and 0.93 (0.88-0.96) for intra- and interreader agreement on stenosis measurements, respectively. Corresponding kappas for grading stenosis (0-29%, 30-69%, 70-99%, and 100%) were 0.79 (0.67-0.89) and 0.80 (0.68-0.90). Agreement between SNAP and CE-MRA was high (ICC: 0.95 [0.90-0.98]; kappa: 0.82 [0.71-0.93]). As a dedicated IPH-imaging sequence, SNAP also provided carotid stenosis measurement that showed high intra- and interreader consistency and excellent agreement with CE-MRA. Further comparisons with digital subtraction angiography and other noninvasive techniques are warranted. 4 J. Magn. Reson. Imaging 2016. © 2017 International Society for Magnetic Resonance in Medicine.

  17. Effect of injection rate on contrast-enhanced MR angiography image quality: Modulation transfer function analysis.

    PubMed

    Clark, Toshimasa J; Wilson, Gregory J; Maki, Jeffrey H

    2017-07-01

    Contrast-enhanced (CE)-MRA optimization involves interactions of sequence duration, bolus timing, contrast recirculation, and both R1 relaxivity and R2*-related reduction of signal. Prior data suggest superior image quality with slower gadolinium injection rates than typically used. A computer-based model of CE-MRA was developed, with contrast injection, physiologic, and image acquisition parameters varied over a wide gamut. Gadolinium concentration was derived using Verhoeven's model with recirculation, R1 and R2* calculated at each time point, and modulation transfer curves used to determine injection rates, resulting in optimal resolution and image contrast for renal and carotid artery CE-MRA. Validation was via a vessel stenosis phantom and example patients who underwent carotid CE-MRA with low effective injection rates. Optimal resolution for renal and carotid CE-MRA is achieved with injection rates between 0.5 to 0.9 mL/s and 0.2 to 0.3 mL/s, respectively, dependent on contrast volume. Optimal image contrast requires slightly faster injection rates. Expected signal-to-noise ratio varies with both contrast volume and cardiac output. Simulated vessel phantom and clinical carotid CE-MRA exams at an effective contrast injection rate of 0.4 to 0.5 mL/s demonstrate increased resolution. Optimal image resolution is achieved at intuitively low, effective injection rates (0.2-0.9 mL/s, dependent on imaging parameters and contrast injection volume). Magn Reson Med 78:357-369, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  18. Grading of carotid artery stenosis in the presence of extensive calcifications: dual-energy CT angiography in comparison with contrast-enhanced MR angiography.

    PubMed

    Korn, A; Bender, B; Brodoefel, H; Hauser, T-K; Danz, S; Ernemann, U; Thomas, C

    2015-03-01

    We investigated the agreement of dual-energy computed tomography angiography (DE-CTA) and contrast-enhanced magnetic resonance angiography (CE-MRA)in the quantitative measurement of stenoses of the internal carotid artery in comparison with digital subtraction angiography (DSA). A total of 21 patients with stenoses of the external carotid artery were investigated with a DE-CTA and CE-MRA before undergoing carotid angioplasty. The grade of the stenoses was assessed in axial multiplanar reformations (MPR) before and multi-intensity projections (MIP) after plaque subtraction (PS) and compared with results from CE-MRA and DSA according to the North American Symptomatic Carotid Endarterectomy Trial. Average grades of stenoses were 80.7 ± 16.1 % (DSA), 81.4 ± 15.3 % (MRA), 80.0 ± 16.7 % (DE-CTA-MPR), and 85.2 ± 14.7 % (DE-CTA-PS-MIP). Of 21 stenoses, 6 were filiform (stenosis grade, 99 %) in the DSA examination. Five of these cases were identified as pseudo-occlusions in MRA, while four were considered as occlusions in DE-CTA-PS-MIP. Another four cases were identified as pseudo-occlusion in DE-CTA-PS-MIP, which were identified as 90 % stenosis in the DSA examination. In comparison with the gold standard DSA, DE-CTA-MPR had a slightly better agreement in measuring the degree of stenosis of the internal carotid arteries than CE-MRA. In DE-CTA-PS-MIP images, a systematic overestimation has to be taken into account due to partial extinction of the lumen by the PS algorithm. Nevertheless, DE-CTA should be preferred in imaging patients with carotid artery stenosis in the presence of extensive calcifications.

  19. 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.

  20. Anti-interleukin-6 receptor antibody therapy favors adrenal androgen secretion in patients with rheumatoid arthritis: a randomized, double-blind, placebo-controlled study.

    PubMed

    Straub, Rainer H; Härle, Peter; Yamana, Seizo; Matsuda, Takemasa; Takasugi, Kiyoshi; Kishimoto, Tadamitsu; Nishimoto, Norihiro

    2006-06-01

    Proinflammatory cytokines such as tumor necrosis factor (TNF) were demonstrated to inhibit adrenal steroidogenesis in patients with rheumatoid arthritis (RA), and this was particularly evident in the increase in adrenal androgen levels during anti-TNF therapy. This study investigated the influence on steroidogenesis of an interleukin-6 (IL-6)-neutralizing strategy using IL-6 receptor monoclonal antibodies (referred to as MRA). In a placebo-controlled, double-blind, randomized study over 12 weeks in 29 patients with RA being treated with prednisolone, 13 of whom received placebo and 16 of whom received 8 mg MRA/kg body weight, the effects of MRA on serum levels of adrenocorticotropic hormone (ACTH), cortisol, 17-hydroxyprogesterone (17OHP), dehydroepiandrosterone (DHEA), DHEA sulfate (DHEAS), androstenedione (ASD), estrone, and 17beta-estradiol, as well as their respective molar ratios, were determined. MRA therapy markedly improved clinical signs of inflammation (the erythrocyte sedimentation rate, swollen joint score, and Disease Activity Score in 28 joints). Serum levels of ACTH and cortisol and the molar ratio of cortisol to ACTH did not change. Although serum levels of DHEA and DHEAS remained stable during therapy, the DHEAS:DHEA molar ratio significantly decreased in treated patients (P = 0.048). Serum levels of ASD as well as the ASD:cortisol and ASD:17OHP molar ratios increased in MRA-treated patients (minimum P < 0.004). Serum levels of estrone and 17beta-estradiol did not change. but the estrone:ASD molar ratio (an indicator of aromatization) decreased during 12 weeks of MRA treatment (P = 0.001). Neutralization of IL-6 increases secretion of biologically active adrenal androgens in relation to that of precursor hormones and estrogens. This is another important indication that proinflammatory cytokines interfere with adrenal androgen steroidogenesis in patients with RA.

  1. Whole-body MR angiography: first experiences with the new TimCT technology with single contrast injection.

    PubMed

    Naguib, Nagy N N; Bohrt, Kevin; Nour-Eldin, Nour-Eldin A; Schulz, Boris; Tawfik, Ahmed M; Siebenhandel, Petra; Bodelle, Boris; Eichler, Katrin; Moritz, Anton; Vogl, Thomas J; Zangos, Stephan

    2014-02-01

    To assess image quality, presence of artifacts, arterial stenosis, and interobserver agreement of Tim-CT in assessment of the arterial system using contrast-enhanced whole-body-MRA (CE-Wb-MRA) with a single contrast-medium injection in patients with arteriosclerosis. The retrospective study included 18 patients (mean age, 68 years). A total of 468 arteries were evaluated. CE-Wb-MRA was performed using Tim-CT technology on a 1.5 Tesla (T) MRI after injecting a single dose of Vasovist. Evaluations were independently performed by two radiologists. The arterial system was divided into seven anatomic locations. Each radiologist assessed the image quality, degree of artifacts, and arterial stenosis in different locations. All Wb-MRA examinations were technically successful. Image quality: 28.42% arteries were excellent, 29.17% were good, 22.54% were satisfactory, 9.40% were poor, and 5.13% of insufficient quality. Occurrence of artifacts: 37.25% were free of artifacts, 49.44% minimal artifacts not affecting diagnosis, and 13.31% strong artifacts not permitting a diagnosis. A total of 60.00% arteries showed no stenosis, 8.76% were ≤50% stenotic, 5.17% were 51-75% stenotic, 4.38% were 76-99%, and 8.54% total occlusion. The interobserver agreement was good for supra-aortic, pelvic, and upper and lower leg regions. CE-Wb-MRA using the TimCT technology and with a single contrast injection is a feasible tool for whole-body MRA. Copyright © 2013 Wiley Periodicals, Inc.

  2. 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

  3. Comparison of 1.5 and 3.0 T for Contrast-Enhanced Pulmonary Magnetic Resonance Angiography

    PubMed Central

    Londy, Frank Joseph; Lowe, Suzan; Stein, Paul D.; Weg, John G.; Eisner, Robert L.; Leeper, Kenneth V.; Woodard, Pamela K.; Sostman, H. Dirk; Jablonski, Kathleen A.; Fowler, Sarah E.; Hales, Charles A.; Hull, Russell D.; Gottschalk, Alexander; Naidich, David P.; Chenevert, Thomas L.

    2013-01-01

    Objective In a recent multi-center trial of gadolinium contrast-enhanced magnetic resonance angiography (Gd-MRA) for diagnosis of acute pulmonary embolism (PE), two centers utilized a common MRI platform though at different field strengths (1.5T and 3T) and realized a signal-to-noise gain with the 3T platform. This retrospective analysis investigates this gain in signal-to-noise of pulmonary vascular targets. Methods Thirty consecutive pulmonary MRA examinations acquired on a 1.5T system at one institution were compared to 30 consecutive pulmonary MRA examinations acquired on a 3T system at a different institution. Both systems were from the same MRI manufacturer and both used the same Gd-MRA pulse sequence, although there were some protocol adjustments made due to field strength differences. Region-of-interests were manually defined on the main pulmonary artery, 4 pulmonary veins, thoracic aorta, and background lung for objective measurement of signal-to-noise, contrast-to-noise, and bolus timing bias between centers. Results The 3T pulmonary MRA protocol achieved higher spatial resolution yet maintained significantly higher signal-to-noise ratio (≥ 13%, p = 0.03) in the main pulmonary vessels relative to 1.5T. There was no evidence of operator bias in bolus timing or patient hemodynamic differences between groups. Conclusion Relative to 1.5T, higher spatial resolution Gd-MRA can be achieved at 3T with a sustained or greater signal-to-noise ratio of enhanced vasculature. PMID:21993980

  4. Carotid artery stenosis with a high-intensity signal plaque on time-of-flight magnetic resonance angiography and association with evidence of intraplaque hypoxia.

    PubMed

    Ogata, Atsushi; Kawashima, Masatou; Wakamiya, Tomihiro; Nishihara, Masashi; Masuoka, Jun; Nakahara, Yukiko; Ebashi, Ryo; Inoue, Kohei; Takase, Yukinori; Irie, Hiroyuki; Abe, Tatsuya

    2017-06-01

    OBJECTIVE Hypoxia induces angiogenesis and plays a major role in the progression of carotid plaques. During carotid intervention, plaques with high-intensity signals on time-of-flight (TOF) magnetic resonance angiography (MRA) often cause ischemic stroke and embolic complications. However, the role of intraplaque hypoxia before carotid endarterectomy (CEA) and carotid artery stenting is not presently understood. In this study the authors aimed to investigate the relationship between intraplaque hypoxia and MRA findings. METHODS Nineteen consecutive patients with 20 carotid artery stenoses who underwent CEA at Saga University Hospital between August 2008 and December 2014 were enrolled in the study. The expressions of hypoxia-inducible transcription factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) were analyzed by immunohistochemical analysis. In addition, the relationship between the findings on TOF MRA and pathology for the carotid plaques was analyzed. RESULTS High-intensity plaques on TOF MRA showed higher expression levels of HIF-1α (p = 0.015) and VEGF (p = 0.007) compared with isointensity plaques. The rate of intraplaque hemorrhage (IPH) on TOF MRA was also significantly higher in the high-intensity plaques than in the isointensity plaques (p = 0.024). Finally, the mean number of neovessels was significantly higher in those without plaque hemorrhage than in those with plaque hemorrhage (p = 0.010). CONCLUSIONS Plaques with high-intensity signals on TOF MRA were associated with IPH and evidence of intraplaque hypoxia. This fact may represent an opportunity to establish novel therapeutic agents targeting intraplaque hypoxia.

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

    PubMed

    Faletti, Riccardo; Rapellino, Alessandro; Barisone, Francesca; Anselmino, Matteo; Ferraris, Federico; Fonio, Paolo; Gaita, Fiorenzo; Gandini, Giovanni

    2014-06-13

    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. 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. 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. 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.

  6. 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

  7. Properties of Non-Structural Concrete Made with Mixed Recycled Aggregates and Low Cement Content.

    PubMed

    López-Uceda, Antonio; Ayuso, Jesús; López, Martin; Jimenez, José Ramón; Agrela, Francisco; Sierra, María José

    2016-01-26

    In spite of not being legally accepted in most countries, mixed recycled aggregates (MRA) could be a suitable raw material for concrete manufacturing. The aims of this research were as follows: (i) to analyze the effect of the replacement ratio of natural coarse aggregates with MRA, the amount of ceramic particles in MRA, and the amount of cement, on the mechanical and physical properties of a non-structural concrete made with a low cement content; and (ii) to verify if it is possible to achieve a low-strength concrete that replaces a greater amount of natural aggregate with MRA and that has a low cement content. Two series of concrete mixes were manufactured using 180 and 200 kg/m³ of CEM II/A-V 42.5 R type Portland cement. Each series included seven concrete mixes: one with natural aggregates; two MRA with different ceramic particle contents; and one for each coarse aggregate replacement ratio (20%, 40%, and 100%). To study their properties, compressive and splitting tensile strength, modulus of elasticity, density, porosity, water penetration, and sorptivity, tests were performed. The results confirmed that the main factors affecting the properties analyzed in this research are the amount of cement and the replacement ratio; the two MRAs used in this work presented a similar influence on the properties. A non-structural, low-strength concrete (15 MPa) with an MRA replacement ratio of up to 100% for 200 kg/m³ of cement was obtained. This type of concrete could be applied in the construction of ditches, sidewalks, and other similar civil works.

  8. 3.0T whole-heart coronary magnetic resonance angiography performed with 32-channel cardiac coils: a single-center experience.

    PubMed

    Yang, Qi; Li, Kuncheng; Liu, Xin; Du, Xiangying; Bi, Xiaoming; Huang, Feng; Jerecic, Renate; Liu, Zhi; An, Jing; Xu, Dong; Zheng, Hairong; Fan, Zhaoyang; Li, Debiao

    2012-09-01

    Whole-heart coronary magnetic resonance angiography (MRA) is a promising method for noninvasive, radiation-free detection and exclusion of obstructive coronary artery disease; however, the required imaging time and robustness of the technique are not yet satisfactory. We evaluated the value of whole-heart coronary MRA at 3.0T using a 32-channel cardiac coil, which reduces image-acquisition times and hence allows to increase the clinical throughput. A total of 110 consecutive patients with suspected coronary artery disease referred for clinically indicated conventional coronary angiography were included in this prospective study. Acquisition of 3.0T coronary MRA data was done by using 32-channel receiver coils. An ECG-triggered, navigator-gated, inversion-recovery prepared, segmented gradient-echo sequence was used for image acquisition with an acceleration factor of 3 in the phase-encoding direction using generalized auto calibrating partially parallel acquisitions reconstruction. Acquisition of coronary MRA was successfully completed in 101 of 110 (92%) patients with average imaging time of 7.0±1.8 minutes. The sensitivity, specificity, positive and negative predictive value of coronary MRA on a patient-based analysis were 95.9% (47/49, 95% CI, 86.0%-99.4%), 86.5% (45/52, 95% CI, 74.2%-94.4%), 87.0% (47/54, 95% CI, 75.1%-94.6%) and 95.7% (45/47, 95% CI, 85.4%-99.4%), respectively. Whole-heart coronary MRA at 3.0T using a 32-channel cardiac coil allows high overall accuracy for detecting significant coronary artery disease with reduced imaging time. It has potential to be a robust and alternative technique for ruling out significant coronary artery disease. URL: http://www.chictr.org. Unique identifier: ChiCTR-DDT-07000121.

  9. Comparison of magnetic resonance imaging mismatch criteria to select patients for endovascular stroke therapy.

    PubMed

    Mishra, Nishant K; Albers, Gregory W; Christensen, Søren; Marks, Michael; Hamilton, Scott; Straka, Matus; Liggins, John T P; Kemp, Stephanie; Mlynash, Michael; Bammer, Roland; Lansberg, Maarten G

    2014-05-01

    The Diffusion and Perfusion Imaging Evaluation for Understanding Stroke Evolution 2 (DEFUSE 2) study has shown that clinical response to endovascular reperfusion differs between patients with and without perfusion-diffusion (perfusion-weighted imaging-diffusion-weighted imaging, PWI-DWI) mismatch: patients with mismatch have a favorable clinical response to reperfusion, whereas patients without mismatch do not. This study examined whether alternative mismatch criteria can also differentiate patients according to their response to reperfusion. Patients from the DEFUSE 2 study were categorized according to vessel occlusion on magnetic resonance angiography (MRA) and DWI lesion volume criteria (MRA-DWI mismatch) and symptom severity and DWI criteria (clinical-DWI mismatch). Favorable clinical response was defined as an improvement of ≥8 points on the National Institutes of Health Stroke Scale (NIHSS) by day 30 or an NIHSS score of ≤1 at day 30. We assessed, for each set of criteria, whether the association between reperfusion and favorable clinical response differed according to mismatch status. A differential response to reperfusion was observed between patients with and without MRA-DWI mismatch defined as an internal carotid artery or M1 occlusion and a DWI lesion<50 mL. Reperfusion was associated with good functional outcome in patients who met these MRA-DWI mismatch criteria (odds ratio [OR], 8.5; 95% confidence interval [CI], 2.3-31.3), whereas no association was observed in patients who did not meet these criteria (OR, 0.5; 95% CI, 0.08-3.1; P for difference between the odds, 0.01). No differential response to reperfusion was observed with other variations of the MRA-DWI or clinical-DWI mismatch criteria. The MRA-DWI mismatch is a promising alternative to DEFUSE 2's PWI-DWI mismatch for patient selection in endovascular stroke trials.

  10. Assessing HTS Performance Using BioAssay Ontology: Screening and Analysis of a Bacterial Phospho-N-Acetylmuramoyl-Pentapeptide Translocase Campaign

    PubMed Central

    Moberg, Andreas; Hansson, Eva; Boyd, Helen

    2014-01-01

    Abstract With the public availability of biochemical assays and screening data constantly increasing, new applications for data mining and method analysis are evolving in parallel. One example is BioAssay Ontology (BAO) for systematic classification of assays based on screening setup and metadata annotations. In this article we report a high-throughput screening (HTS) against phospho-N-acetylmuramoyl-pentapeptide translocase (MraY), an attractive antibacterial drug target involved in peptidoglycan synthesis. The screen resulted in novel chemistry identification using a fluorescence resonance energy transfer assay. To address a subset of the false positive hits, a frequent hitter analysis was performed using an approach in which MraY hits were compared with hits from similar assays, previously used for HTS. The MraY assay was annotated according to BAO and three internal reference assays, using a similar assay design and detection technology, were identified. Analyzing the assays retrospectively, it was clear that both MraY and the three reference assays all showed a high false positive rate in the primary HTS assays. In the case of MraY, false positives were efficiently identified by applying a method to correct for compound interference at the hit-confirmation stage. Frequent hitter analysis based on the three reference assays with similar assay method identified additional false actives in the primary MraY assay as frequent hitters. This article demonstrates how assays annotated using BAO terms can be used to identify closely related reference assays, and that analysis based on these assays clearly can provide useful data to influence assay design, technology, and screening strategy. PMID:25415593

  11. Assessing HTS performance using BioAssay Ontology: screening and analysis of a bacterial phospho-N-acetylmuramoyl-pentapeptide translocase campaign.

    PubMed

    Moberg, Andreas; Zander Balderud, Linda; Hansson, Eva; Boyd, Helen

    2014-01-01

    With the public availability of biochemical assays and screening data constantly increasing, new applications for data mining and method analysis are evolving in parallel. One example is BioAssay Ontology (BAO) for systematic classification of assays based on screening setup and metadata annotations. In this article we report a high-throughput screening (HTS) against phospho-N-acetylmuramoyl-pentapeptide translocase (MraY), an attractive antibacterial drug target involved in peptidoglycan synthesis. The screen resulted in novel chemistry identification using a fluorescence resonance energy transfer assay. To address a subset of the false positive hits, a frequent hitter analysis was performed using an approach in which MraY hits were compared with hits from similar assays, previously used for HTS. The MraY assay was annotated according to BAO and three internal reference assays, using a similar assay design and detection technology, were identified. Analyzing the assays retrospectively, it was clear that both MraY and the three reference assays all showed a high false positive rate in the primary HTS assays. In the case of MraY, false positives were efficiently identified by applying a method to correct for compound interference at the hit-confirmation stage. Frequent hitter analysis based on the three reference assays with similar assay method identified additional false actives in the primary MraY assay as frequent hitters. This article demonstrates how assays annotated using BAO terms can be used to identify closely related reference assays, and that analysis based on these assays clearly can provide useful data to influence assay design, technology, and screening strategy.

  12. High-resolution STIR for 3-T MRI of the posterior fossa: visualization of the lower cranial nerves and arteriovenous structures related to neurovascular compression.

    PubMed

    Hiwatashi, Akio; Yoshiura, Takashi; Yamashita, Koji; Kamano, Hironori; Honda, Hiroshi

    2012-09-01

    Preoperative evaluation of small vessels without contrast material is sometimes difficult in patients with neurovascular compression disease. The purpose of this retrospective study was to evaluate whether 3D STIR MRI could simultaneously depict the lower cranial nerves--fifth through twelfth--and the blood vessels in the posterior fossa. The posterior fossae of 47 adults (26 women, 21 men) without gross pathologic changes were imaged with 3D STIR and turbo spin-echo heavily T2-weighted MRI sequences and with contrast-enhanced turbo field-echo MR angiography (MRA). Visualization of the cranial nerves on STIR images was graded on a 4-point scale and compared with visualization on T2-weighted images. Visualization of the arteries on STIR images was evaluated according to the segments in each artery and compared with that on MRA images. Visualization of the veins on STIR images was also compared with that on MRA images. Statistical analysis was performed with the Mann-Whitney U test. There were no significant differences between STIR and T2-weighted images with respect to visualization of the cranial nerves (p > 0.05). Identified on STIR and MRA images were 94 superior cerebellar arteries, 81 anteroinferior cerebellar arteries, and 79 posteroinferior cerebellar arteries. All veins evaluated were seen on STIR and MRA images. There were no significant differences between STIR and MRA images with respect to visualization of arteries and veins (p > 0.05). High-resolution STIR is a feasible method for simultaneous evaluation of the lower cranial nerves and the vessels in the posterior fossa without the use of contrast material.

  13. 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.

  14. Feasibility of three-dimensional magnetic resonance angiography-fluoroscopy image fusion technique in guiding complex endovascular aortic procedures in patients with renal insufficiency.

    PubMed

    Schwein, Adeline; Chinnadurai, Ponraj; Shah, Dipan J; Lumsden, Alan B; Bechara, Carlos F; Bismuth, Jean

    2017-05-01

    Three-dimensional image fusion of preoperative computed tomography (CT) angiography with fluoroscopy using intraoperative noncontrast cone-beam CT (CBCT) has been shown to improve endovascular procedures by reducing procedure length, radiation dose, and contrast media volume. However, patients with a contraindication to CT angiography (renal insufficiency, iodinated contrast allergy) may not benefit from this image fusion technique. The primary objective of this study was to evaluate the feasibility of magnetic resonance angiography (MRA) and fluoroscopy image fusion using noncontrast CBCT as a guidance tool during complex endovascular aortic procedures, especially in patients with renal insufficiency. All endovascular aortic procedures done under MRA image fusion guidance at a single-center were retrospectively reviewed. The patients had moderate to severe renal insufficiency and underwent diagnostic contrast-enhanced magnetic resonance imaging after gadolinium or ferumoxytol injection. Relevant vascular landmarks electronically marked in MRA images were overlaid on real-time two-dimensional fluoroscopy for image guidance, after image fusion with noncontrast intraoperative CBCT. Technical success, time for image registration, procedure time, fluoroscopy time, number of digital subtraction angiography (DSA) acquisitions before stent deployment or vessel catheterization, and renal function before and after the procedure were recorded. The image fusion accuracy was qualitatively evaluated on a binary scale by three physicians after review of image data showing virtual landmarks from MRA on fluoroscopy. Between November 2012 and March 2016, 10 patients underwent endovascular procedures for aortoiliac aneurysmal disease or aortic dissection using MRA image fusion guidance. All procedures were technically successful. A paired t-test analysis showed no difference between preimaging and postoperative renal function (P = .6). The mean time required for MRA-CBCT image

  15. Novel Bruch's Membrane Opening Minimum Rim Area Equalizes Disc Size Dependency and Offers High Diagnostic Power for Glaucoma.

    PubMed

    Enders, Philip; Adler, Werner; Schaub, Friederike; Hermann, Manuel M; Dietlein, Thomas; Cursiefen, Claus; Heindl, Ludwig M

    2016-12-01

    The purpose of this study was to assess the diagnostic power of the novel two-dimensional parameter Bruch's membrane opening minimal rim area (BMO-MRA) in spectral-domain optical coherence tomography (SD-OCT) for detection of glaucoma compared to minimal rim width (BMO-MRW) and retinal nerve fiber layer (RNFL) thickness in large and small optic discs. In this case-control, cross-sectional study, 207 eyes of 207 participants, including 89 controls and 97 patients with glaucoma and 21 with ocular hypertension (OHT), with a disc size <1.63 mm2 or >2.43 mm2 underwent SD-OCT, confocal laser scanning tomography (CSLT), visual field testing, and clinical examination. Bruch's membrane opening-MRA BMO-MRW, RNFL thickness of SD-OCT and disc margin rim area (DM-RA) of CSLT were evaluated and analyzed for diagnostic power to detect glaucoma. In healthy eyes with macrodiscs, mean BMO-MRW of 243.14 ± 43.12 μm was significantly smaller than BMO-MRW in microdiscs (338.97 ± 69.39; P < 0.001). Bruch's membrane opening-MRA was comparable between disc size groups with 1.22 ± 0.25 mm2 for macrodiscs and 1.26 ± 0.27 mm2 for microdiscs (P = 0.51), as was RNFL thickness (82.69 ± 15.76 μm versus 78.53 ± 11.01 μm, respectively; P = 0.28). Perimetric mean deviation was -8.7 ± 6.3 dB in glaucoma and -0.6 ± 1.60 dB in OHT patients. Correlation of BMO-MRA and visual field function was rho (ρ) = 0.70 (P < 0.001). Diagnostic power to differentiate glaucoma patients was highest for BMO-MRA. Partial area under the curve (pAUC) for BMO-MRA was 0.14 for specificity between 0.8 and 1.0, exceeding pAUCs of BMO-MRW (P < 0.001), RNFL thickness (P = 0.03), and DM-RA (P = 0.01). Bruch's membrane opening-based minimum rim area measurements offer advantages compared to one-dimensional parameters assessing neuroretinal rim by SD-OCT. In nonglaucomatous eyes, BMO-MRA values seem comparable for the full range of disc sizes. Bruch's membrane opening-MRA surpasses other parameters in diagnostic power

  16. High resolution 3 Tesla contrast-enhanced MR angiography of the hands in Raynaud's disease.

    PubMed

    Walcher, J; Strecker, R; Goldacker, S; Winterer, J; Langer, M; Bley, T A

    2007-04-01

    Raynaud's disease is associated with disorders in blood circulation of the hands. The gold standard to visualise pathology of digital arteries is catheter angiography. Contrast-enhanced MR angiography (CE MRA) has developed even more as an alternative non-invasive method to digital subtraction angiography, mostly for pelvic or lower limb vessels. We report a case of primary Raynaud's disease with high-grade stenosis and an occlusion of the digital arteries. This case illustrates the benefit and efficiency of CE MRA at high fields in depicting location and extension of peripheral arterial alterations.

  17. Emerging Techniques for Evaluation of the Hemodynamics of Intracranial Vascular Pathology

    PubMed Central

    Huang, Melissa; Chien, Aichi

    2015-01-01

    Advances in imaging modalities have improved the assessment of intracranial hemodynamics using non-invasive techniques. This review examines new imaging modalities and clinical applications of currently available techniques, describes pathophysiology and future directions in hemodynamic analysis of intracranial stenoses, aneurysms and arteriovenous malformations and explores how hemodynamic analysis may have prognostic value in predicting clinical outcomes and assist in risk stratification. The advent of new technologies such as pseudo-continuous arterial spin labeling, accelerated magnetic resonance angiography (MRA) techniques, 4D digital subtraction angiography, and improvements in clinically available techniques such as phase-contrast MRA may change the landscape of vascular imaging and modify current clinical practice guidelines. PMID:25924168

  18. 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.

  19. Head-to-head comparison between (18)F-FDOPA PET/CT and MR/CT angiography in clinically recurrent head and neck paragangliomas.

    PubMed

    Heimburger, Céline; Veillon, Francis; Taïeb, David; Goichot, Bernard; Riehm, Sophie; Petit-Thomas, Julie; Averous, Gerlinde; Cavalcanti, Marcela; Hubelé, Fabrice; Chabrier, Gerard; Namer, Izzie Jacques; Charpiot, Anne; Imperiale, Alessio

    2017-06-01

    Head and neck paragangliomas (HNPGLs) can relapse after primary treatment. Optimal imaging protocols have not yet been established for posttreatment evaluation. The aim of the present study was to assess the diagnostic value of (18)F-FDOPA PET/CT and MR/CT angiography (MRA/CTA) in HNPGL patients with clinical relapse during their follow-up. Sixteen consecutive patients presenting with local pain, tinnitus, dysphagia, hoarse voice, cranial nerve involvement, deafness, or retrotympanic mass appearing during follow-up after the initial treatment of HNPGLs were retrospectively evaluated. Patients underwent both (18)F-FDOPA PET/CT and MRA (15 patents) or CTA (1 patent). Both methods were first assessed under blinded conditions and afterwards correlated. Head and neck imaging abnormalities without histological confirmation were considered true-positive results based on a consensus between radiologists and nuclear physicians and on further (18)F-FDOPA PET/CT and/or MRA. (18)F-FDOPA PET/CT and MRA/CTA were concordant in 14 patients and in disagreement in 2 patients. (18)F-FDOPA PET/CT and MRA/CTA identified, respectively, 12 and 10 presumed recurrent HNPGLs in 12 patients. The two lesions diagnosed by PET/CT only were confirmed during follow-up by otoscopic examination and MRA performed 29 and 17 months later. (18)F-FDOPA PET/CT images were only slightly influenced by the posttreatment sequelae, showing a better interobserver reproducibility than MRA/CTA. Finally, in 2 of the 16 studied patients, (18)F-FDOPA PET/CT detected two additional synchronous primary HNPGLs. (18)F-FDOPA PET/CT is highly sensitive in posttreatment evaluation of patients with HNPGLs, and also offers better interobserver reproducibility than MRA/CTA and whole-body examination. We therefore suggest that (18)F-FDOPA PET/CT is performed as the first diagnostic imaging modality in symptomatic patients with suspicion of HNPGL relapse after primary treatment when (68)Ga-labeled somatostatin analogues are

  20. Predicting pharmacists' adjustment of medication regimens in Ramadan using the Theory of Planned Behavior.

    PubMed

    Amin, Mohamed E K; Chewning, Betty

    2015-01-01

    During Ramadan, many Muslim patients may choose to abstain from food, drink and oral medications from dawn to sunset. This study explored the utility of the Theory of Planned Behavior (TPB) model in predicting community pharmacists' Medication Regimen Adjustment (MRA) behavior for patients during Ramadan. A sample of pharmacists was drawn from a recent list of community pharmacies in the Alexandria governorate. A cross-sectional, self-administered survey was completed by community pharmacists to determine their attitudes and behaviors regarding adjustment of medication regimens around Ramadan. Multiple linear regression was used to predict MRA as a function of the TPB constructs and four other factors - "pharmacist initiation of the conversation on MRA," "number of hours worked," "age," and "religion" of pharmacist. Two hundred seventy-seven (92.9%) of the 298 approached pharmacists participated. While 94.2% reported performing one or more kinds of MRA around Ramadan for at least one patient, the majority of these were for a small percentage of patients. The most common MRA was changing the frequency of taking the medication followed by the dose of the medication, the dosage form of the medication and the medication itself. Statistically significant predictors of MRA in the final model included patient social pressure (PSP) (β = 0.274, P < 0.001), pharmacist perceived behavioral capability (PBC) (β = 0.217, P < 0.001), pharmacist perceived patient benefit (PPB) (β = 0.207, P = 0.001), initiating communication (β = 0.167, P = 0.001) and the number of working hours (β = 0.145, P = 0.005). The TPB appears to have utility in predicting pharmacists' MRA behavior. Pharmacists may be open to a larger MRA role than they are currently performing. There is a need to prepare pharmacists who are frequently requested to adjust patients' medication regimens to make sure they provide a safe transition for fasting patients into and out of Ramadan

  1. [Cerebral vasospasm after coil embolization for unruptured internal carotid artery aneurysm: case report].

    PubMed

    Ogata, Atsushi; Suzuyama, Kenji; Koga, Hisao; Takase, Yukinori; Matsushima, Toshio

    2010-01-01

    A 38-year-old woman was admitted to our hospital with a 3-day history of severe headache associated with some nausea and vomiting. MRI did not show any evidence of subarachnoid hemorrhage, but MRA and CTA showed an aneurysm on the paraclinoid region of the right internal carotid artery. She was successfully treated by coil embolization. MRA taken 7 days after the treatment showed marked vasospam. Fortunately, her therapeutic course was uneventful and she was discharged without any neurological deficits. Vasospasm without subarachnoid hemorrhage is a rare event. Here, we review the literature and discuss potential mechanisms for vasospasm in the absence of subarachnoid hemorrhage.

  2. Carotid Artery Stenting in a Patient with Spontaneous Recanalization of a Proximal Internal Carotid Artery Occlusion: a Case Report

    PubMed Central

    Koh, Jun Seok; Choi, Woo Suk

    2006-01-01

    We report here on a rare case of carotid artery angioplasty and stenting in a patient with spontaneous recanalization after complete occlusion of the proximal internal carotid artery (ICA). The patient initially showed severe stenosis at the left proximal ICA on MR angiography (MRA). Digital subtraction angiography (DSA) performed three days after MRA showed complete occlusion of the proximal ICA. The follow-up DSA after four weeks showed recanalization of the ICA, and then carotid artery stenting was successfully performed. There has been no neurologic complication during more than one year follow-up. PMID:17143034

  3. [Aberrant internal carotid artery as a cause of pulsatile tinnitus: a difficult diagnosis in MRI?].

    PubMed

    Soyka, M B; Schuknecht, B; Huber, A M

    2010-02-01

    We present the case of a 43-year-old patient with sensorineural hearing loss and the finding of an aberrant internal carotid artery in the left tympanic cavity that was causing pulsatile tinnitus. The aberrant vessel was initially invisible on magnetic resonance imaging (MRI) and was confirmed by high-resolution computed tomography and MR angiography (MRA). Recognition of an aberrant course of an internal carotid artery often requires a combination of MRI and MRA to establish the diagnosis and rule out other differential diagnoses.

  4. Comparison of 3D free-breathing coronary MR angiography and 64-MDCT angiography for detection of coronary stenosis in patients with high calcium scores.

    PubMed

    Liu, Xin; Zhao, Xihai; Huang, Jie; Francois, Christopher J; Tuite, David; Bi, Xiaoming; Li, Debiao; Carr, James C

    2007-12-01

    The objective of our study was to compare the diagnostic performance of coronary MR angiography (MRA) and 64-MDCT angiography (MDCTA) for the detection of significant stenosis (> or = 50%) in patients with high calcium scores. Eighteen patients (12 men, six women; mean age, 56 y; age range, 38-77 y) who had at least one calcified plaque with a calcium score of > 100 underwent coronary MRA and conventional coronary angiography (CAG) within 2 weeks of MDCTA. Coronary MRA image quality of the calcified segments was assessed by two observers in consensus on a 4-point scale (1 = not visible, 2 = poor, 3 = good, 4 = excellent) using a 10-segment model from the modified American Heart Association classification. Three experienced radiologists, unaware of the results of conventional CAG, independently assessed for the presence of significant stenosis on MDCTA images and the corresponding MRA images. Receiver operating characteristic (ROC) curves were calculated for each reader using conventional CAG as the gold standard. Thirty-three calcified plaques with a calcium score of > 100 were detected on MDCTA in the 18 patients. The coronary segments with nodal calcification (n = 17) showed a higher mean image quality score than the segments with diffuse calcification (n = 16) (3.47 +/- 0.62 vs 2.94 +/- 0.77, respectively; p < 0.05). Of the 33 coronary segments with calcification, 12 significant stenoses were identified on conventional CAG. The sensitivity, specificity, and area under the ROC curve (AUC) for MRA and MDCTA, respectively, were as follows: reader 1, 75%, 81%, 0.82 versus 75%, 48%, 0.68; reader 2, 83%, 71%, 0.82 versus 67%, 52%, 0.63; and reader 3, 83%, 71%, 0.85 versus 83%, 43%, 0.65, respectively. The average AUC of MRA for the three readers was significantly higher than that of MDCTA (p = 0.030). Coronary MRA has higher image quality for coronary segments with nodal calcification than for coronary segments with diffuse calcification. Coronary MRA has better

  5. Comparison of 3D Free-Breathing Coronary MR Angiography and 64-MDCT Angiography for Detection of Coronary Stenosis in Patients with High Calcium Scores

    PubMed Central

    Liu, Xin; Zhao, Xihai; Huang, Jie; Francois, Christopher J.; Tuite, David; Bi, Xiaoming; Li, Debiao; Carr, James C.

    2014-01-01

    OBJECTIVE The objective of our study was to compare the diagnostic performance of coronary MR angiography (MRA) and 64-MDCT angiography (MDCTA) for the detection of significant stenosis (≥ 50%) in patients with high calcium scores. MATERIALS AND METHODS Eighteen patients (12 men, six women; mean age, 56 y; age range, 38–77 y) who had at least one calcified plaque with a calcium score of > 100 underwent coronary MRA and conventional coronary angiography (CAG) within 2 weeks of MDCTA. Coronary MRA image quality of the calcified segments was assessed by two observers in consensus on a 4-point scale (1 = not visible, 2 = poor, 3 = good, 4 = excellent) using a 10-segment model from the modified American Heart Association classification. Three experienced radiologists, unaware of the results of conventional CAG, independently assessed for the presence of significant stenosis on MDCTA images and the corresponding MRA images. Receiver operating characteristic (ROC) curves were calculated for each reader using conventional CAG as the gold standard. RESULTS Thirty-three calcified plaques with a calcium score of > 100 were detected on MDCTA in the 18 patients. The coronary segments with nodal calcification (n = 17) showed a higher mean image quality score than the segments with diffuse calcification (n = 16) (3.47 ± 0.62 vs 2.94 ± 0.77, respectively; p < 0.05). Of the 33 coronary segments with calcification, 12 significant stenoses were identified on conventional CAG. The sensitivity, specificity, and area under the ROC curve (AUC) for MRA and MDCTA, respectively, were as follows: reader 1, 75%, 81%, 0.82 versus 75%, 48%, 0.68; reader 2, 83%, 71%, 0.82 versus 67%, 52%, 0.63; and reader 3, 83%, 71%, 0.85 versus 83%, 43%, 0.65, respectively. The average AUC of MRA for the three readers was significantly higher than that of MDCTA (p = 0.030). CONCLUSION Coronary MRA has higher image quality for coronary segments with nodal calcification than for coronary segments with

  6. Dynamic and static magnetic resonance angiography of the supra-aortic vessels at 3.0 T: intraindividual comparison of gadobutrol, gadobenate dimeglumine, and gadoterate meglumine at equimolar dose.

    PubMed

    Kramer, Jens Harald; Arnoldi, Elisabeth; François, Christopher J; Wentland, Andrew L; Nikolaou, Konstantin; Wintersperger, Bernd J; Grist, Thomas M

    2013-03-01

    The purpose of this study was the intraindividual comparison of a 1.0 M and two 0.5 M gadolinium-based contrast agents (GBCA) using equimolar dosing in dynamic and static magnetic resonance angiography (MRA) of the supra-aortic vessels. In this institutional review board-approved study, a total of 20 healthy volunteers (mean ± SD age, 29 ± 6 years) underwent 3 consecutive supra-aortic MRA examinations on a 3.0 T magnetic resonance system. The order of GBCA (Gadobutrol, Gadobenate dimeglumine, and Gadoterate meglumine) was randomized with a minimum interval of 48 hours between the examinations. Before each examination and 45 minutes after each examination, circulatory parameters were recorded. Total GBCA dose per MRA examination was 0.1 mmol/kg with a 0.03 mmol/kg and 0.07 mmol/kg split for dynamic and static MRA, respectively, injected at a rate of 2 mL/s. Two blinded readers qualitatively assessed static MRA data sets independently using pairwise rankings (superior, inferior, and equal). In addition, quantitative analysis was performed with signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) evaluation as well as vessel sharpness analysis of static MRA using an in-house-developed semiautomated tool. Dynamic MRA was evaluated for maximal SNR. Statistical analysis was performed using the Cohen κ, the Wilcoxon rank sum tests, and mixed effects models. No significant differences of hemodynamic parameters were observed. In static MRA, Gadobutrol was rated superior to Gadoterate meglumine (P < 0.05) and equal to Gadobenate dimeglumine (P = 0.06) with good to excellent reader agreement (κ, 0.66-0.83). In static MRA, SNR was significantly higher using 1.0 M Gadobutrol as compared with either 0.5 M agent (P < 0.05 and P < 0.05) and CNR was significantly higher as compared with Gadoterate meglumine (P < 0.05), whereas CNR values of Gadobutrol data sets were not significantly different as compared with Gadobenate dimeglumine (P = 0.13). Differences in CNR

  7. 32 CFR 179.5 - Responsibilities.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... rule. Upon further delineation and characterization of an MRA into more than one MRS, Components shall... federal agency, state regulatory agencies, tribal governments, and local government officials are aware of... sequencing decisions result in action at an MRS with a lower MRS priority ahead of an MRS with a higher MRS...

  8. 32 CFR 179.5 - Responsibilities.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... rule. Upon further delineation and characterization of an MRA into more than one MRS, Components shall... federal agency, state regulatory agencies, tribal governments, and local government officials are aware of... sequencing decisions result in action at an MRS with a lower MRS priority ahead of an MRS with a higher MRS...

  9. Growth and health of Holstein calves fed milk replacers supplemented with antibiotics or Enteroguard.

    PubMed

    Donovan, D C; Franklin, S T; Chase, C C L; Hippen, A R

    2002-04-01

    Forty-five Holstein calves were fed milk replacers containing either antibiotics [MRA (oxytetracycline at 138 mg/kg and neomycin at 276 mg/kg), n = 22)] or Enteroguard [MRE, a blend of fructooligosaccharides, allicin, and gut-active microbes at (129 mg/kg, n = 23)] from birth to 5 wk of age to compare effects on average daily gain and on incidence of scours. Performance was evaluated by measuring weight gain, feed efficiency, and fecal scores. The overall body weight gains and severity of scours were not different between treatments, nor were there differences in starter intake or mean body weight gain. During wk 2, the average gain of calves fed MRA was less than that of calves fed MRE (0.07 vs. 0.09 kg/d, P = 0.09), and greater during wk 5 (0.62 vs. 0.51 kg/d, P < 0.01); however, total gain for calves fed MRE was not different from calves fed MRA. Likewise, average feed efficiencies (gain/dry matter intake) were not different. Severity of scours, as measured by fecal scores, and concentrations of serum proteins, an indirect measure of immunoglobulins, were similar for calves fed MRA and MRE. The results suggest that antibiotics in milk replacers can be replaced with compounds such as fructooligosaccharides, probiotics, and allicin to obtain similar calf performance.

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

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... such determination shall be stated in writing and submitted to the ASD(MRA&L), or designee, for review... designee, in writing. (b) Required assurances. (1) DoD Components shall require all recipients to file written assurances that their programs or activities will be conducted in accordance with this part and...

  11. 75 FR 3246 - National Register of Historic Places; Notification of Pending Nominations and Related Actions

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-20

    ... Multnomah County Arnold-Park Log Home, 12000 SW. Boones Ferry Rd., Portland, 10000016 In the interest of... Program. ARKANSAS Pulaski County Main Street Commercial Historic District, (Pulaski County MRA) 300 block...., Building, (Ottumwa MPS) 222-224 E. 2nd St., Ottumwa, 10000003 MASSACHUSETTS Norfolk County Pond Street...

  12. 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.

  13. 32 CFR 56.7 - Programs and activities subject to this part.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 1 2014-07-01 2014-07-01 false Programs and activities subject to this part. 56.7 Section 56.7 National Defense Department of Defense OFFICE OF THE SECRETARY OF DEFENSE PERSONNEL... this part to the ASD (MRA&L), or designee, within 15 calendar days of their creation or funding....

  14. The value of resting-state functional MRI in subacute ischemic stroke: comparison with dynamic susceptibility contrast-enhanced perfusion MRI.

    PubMed

    Ni, Ling; Li, Jingwei; Li, Weiping; Zhou, Fei; Wang, Fangfang; Schwarz, Christopher G; Liu, Renyuan; Zhao, Hui; Wu, Wenbo; Zhang, Xin; Li, Ming; Yu, Haiping; Zhu, Bin; Villringer, Arno; Zang, Yufeng; Zhang, Bing; Lv, Yating; Xu, Yun

    2017-01-31

    To evaluate the potential clinical value of the time-shift analysis (TSA) approach for resting-state fMRI (rs-fMRI) blood oxygenation level-dependent (BOLD) data in detecting hypoperfusion of subacute stroke patients through comparison with dynamic susceptibility contrast perfusion weighted imaging (DSC-PWI). Forty patients with subacute stroke (3-14 days after neurological symptom onset) underwent MRI examination. Cohort A: 31 patients had MRA, DSC-PWI and BOLD data. Cohort B: 9 patients had BOLD and MRA data. The time delay between the BOLD time course in each voxel and the mean signal of global and contralateral hemisphere was calculated using TSA. Time to peak (TTP) was employed to detect hypoperfusion. Among cohort A, 14 patients who had intracranial large-vessel occlusion/stenosis with sparse collaterals showed hypoperfusion by both of the two approaches, one with abundant collaterals showed neither TTP nor TSA time delay. The remaining 16 patients without obvious MRA lesions showed neither TTP nor TSA time delay. Among cohort B, eight patients showed time delay areas. The TSA approach was a promising alternative to DSC-PWI for detecting hypoperfusion in subacute stroke patients who had obvious MRA lesions with sparse collaterals, those with abundant collaterals would keep intact local perfusion.

  15. 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…

  16. EVALUATION OF VADOSE ZONE AND SOURCE MODELS FOR MULTI-MEDIA, MULTI-PATHWAY, MULTI-RECEPTOR RISK ASSESSMENT USING LARGE SOIL COLUMN EXPERIMENT DATA

    EPA Science Inventory

    The U.S. 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 software sys...

  17. 32 CFR 56.7 - Programs and activities subject to this part.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 1 2013-07-01 2013-07-01 false Programs and activities subject to this part. 56.7 Section 56.7 National Defense Department of Defense OFFICE OF THE SECRETARY OF DEFENSE PERSONNEL... this part to the ASD (MRA&L), or designee, within 15 calendar days of their creation or funding....

  18. Vascular thoracic outlet syndrome: protocol design and diagnostic value of contrast-enhanced 3D MR angiography and equilibrium phase imaging on 1.5- and 3-T MRI scanners.

    PubMed

    Ersoy, Hale; Steigner, Michael L; Coyner, Karl B; Gerhard-Herman, Marie D; Rybicki, Frank J; Bueno, Raphael; Nguyen, Louis L

    2012-05-01

    The purpose of this article is to evaluate the efficiency and reproducibility of a contrast-enhanced 3D MR angiography (MRA) protocol, using the provocative arm position on 1.5- and 3-T MRI scanners, and to determine the frequency and distribution of vascular compression and vascular complications in the thoracic outlet. Seventy-eight consecutive patients with clinically suspected thoracic outlet syndrome (TOS) were included in the study. Two radiologists independently analyzed all eligible vessel segments, and interobserver agreement was determined using kappa statistics. The distribution of vascular compression with regard to the clinical presentation at referral was also analyzed. A venous component, which presented with mainly venous symptoms and findings, was confirmed in 85% of the subjects. An arterial component, which presented with clinical symptoms and findings of vascular TOS syndrome, was seen in 82% of the subjects. The vascular component of TOS, which presented with mainly neurogenic or indeterminate symptoms or findings, was excluded in 61% of the subjects. Contrast-enhanced 3D MRA using provocative arm positioning allows excellent imaging of the arteries and veins on both sides and thus provides a noninvasive imaging alternative to digital subtraction angiography in patients with suspected vascular TOS. Contrast-enhanced 3D MRA is also an ideal imaging modality for postsurgical follow-up for identifying restenosis or residual vascular compression. However, all imaging studies, including the contrast-enhanced 3D MRA protocol described here, should be treated as complementary tests for the diagnosis of TOS.

  19. Velocity-selective magnetization-prepared non-contrast-enhanced cerebral MR angiography at 3 Tesla: Improved immunity to B0/B1 inhomogeneity.

    PubMed

    Qin, Qin; Shin, Taehoon; Schär, Michael; Guo, Hua; Chen, Hanwei; Qiao, Ye

    2016-03-01

    To develop a Fourier-transform based velocity-selective (VS) pulse train that offers improved robustness to B0/B1 inhomogeneity for non-contrast-enhanced cerebral MR angiography (MRA) at 3 Tesla (T). VS pulse train I and II with different saturation bands are proposed to incorporate paired and phase cycled refocusing pulses. Their sensitivity to B0/B1 inhomogeneity was estimated through simulation and compared with a single refocused VS pulse train. The implementation was compared to standard time of flight (TOF) among eight healthy subjects. In contrast to single refocused VS pulse train, the simulated VS profiles from proposed pulse trains indicate much improved immunity to field inhomogeneity in the brain at 3T. Successive application of two identical VS pulse trains yields a better suppression of static tissue at the cost of 20 ∼ 30% signal loss within large vessels. Average relative contrast ratios of major cerebral arterial segments applying both pulse train I and II with two preparations are 0.81 ± 0.06 and 0.81 ± 0.05, respectively, significantly higher than 0.67 ± 0.07 of TOF-MRA. VS MRA, in particular, the pulse train II with the narrower saturation band, depicts more small vessels with slower flow. VS magnetization-prepared cerebral MRA was demonstrated among normal subjects on a 3T scanner. © 2015 Wiley Periodicals, Inc.

  20. 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...

  1. Retention Behavior of Enlisted TARs (Training and Administration of the Reserves) in Surface-Expansion Ratings

    DTIC Science & Technology

    1987-12-01

    program matures. ROBERT F. LOCKMAN Director Navy Manpower Program Distribution List: ASSTSECNAV MRA USNA NAVPGSCOL * NAVWARCOL NAVFITWEPSCOL...paper are contained in table A-I. 1. See Pindyck and iubi..eld (A-11, pages 301-312. 2. FORTRAN IV Program [A-2]. A-1 %II TABLE A-I ESTIMATES OF EQUATIONS

  2. A comparative 2D QSAR study on a series of hydroxamic acid-based histone deacetylase inhibitors vis-à-vis comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA).

    PubMed

    Bajpai, Anubha; Agarwal, Neeraj; Gupta, Satya P

    2014-06-01

    A quantitative structure-activity relationship (QSAR) study was performed on a series of indole amide analogues reported by Dai et al. [Bioorg Med Chem Lett (2003), 13, 1897-1901] to act as histone deacetylase (HDAC) inhibitors. The multiple regression analysis (MRA) revealed a model showing the significant dependence of the activity on molar refractivity (MR) and global topological charge index (GTCI) of the compounds, suggesting that inhibition of the HDAC by this series of compounds might involve the dispersion interaction with the receptor, where charge transfer between pairs of atoms might greatly help to polarize the molecule. The MRA results were then compared with those obtained by Guo et al. [Bioorg Med Chem (2005), 13, 5424-5434] by comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA). It was found that MRA gave as good results and had as good predictive ability as CoMFA and CoMSIA. Besides, MRA was also able to throw the light on the physicochemical properties of the molecules that were involved in drug-receptor interactions, while CoMFA and CoMSIA could not. The dispersion interaction between the molecule and the active site of the receptor is suggested to be the main interaction.

  3. 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...

  4. 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...

  5. 32 CFR 56.5 - Responsibilities.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 1 2010-07-01 2010-07-01 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...

  6. Biosynthesis of a water-soluble lipid I analogue and a convenient assay for translocase I.

    PubMed

    Siricilla, Shajila; Mitachi, Katsuhiko; Skorupinska-Tudek, Karolina; Swiezewska, Ewa; Kurosu, Michio

    2014-09-15

    Translocase I (MraY/MurX) is an essential enzyme in growth of the vast majority of bacteria that catalyzes the transformation from UDP-MurNAc-pentapeptide (Park's nucleotide) to prenyl-MurNAc-pentapeptide (lipid I), the first membrane-anchored peptidoglycan precursor. MurX has received considerable attention in the development of new tuberculosis (TB) drugs due to the fact that the MurX inhibitors kill exponentially growing Mycobacterium tuberculosis (Mtb) much faster than clinically used TB drugs. Lipid I isolated from Mtb contains the C50-prenyl unit that shows very poor water solubility; thus, this chemical characteristic of lipid I renders MurX enzyme assays impractical for screening and lacks reproducibility of the enzyme assays. We have established a scalable chemical synthesis of Park's nucleotide-N(ε)-dansylthiourea 2 that can be used as a MurX enzymatic substrate to form lipid I analogues. In our investigation of the minimum structure requirement of the prenyl phosphate in the MraY/MurX-catalyzed lipid I analogue synthesis with 2, we found that neryl phosphate (C10 phosphate) can be recognized by MraY/MurX to generate the water-soluble lipid I analogue in quantitative yield under the optimized conditions. Here, we report a rapid and robust analytical method for quantifying MraY/MurX inhibitory activity of library molecules. Copyright © 2014 Elsevier Inc. All rights reserved.

  7. Biosynthesis of A Water-Soluble Lipid I Analogue and A Convenient Assay for Translocase I

    PubMed Central

    Skorupinska-Tudek, Karolina; Swiezewska, Ewa; Kurosu, Michio

    2014-01-01

    Translocase I (MraY/MurX) is an essential enzyme in growth of the vast majority of bacteria that catalyzes the transformation from UDP-MurNAc-pentapeptide (Park’s nucleotide) to prenyl-MurNAc-pentapeptide (lipid I), the first membrane-anchored peptidoglycan precursor. MurX has been received considerable attentions to the development of new TB drugs due to the fact that the MurX inhibitors kill exponentially growing Mycobacterium tuberculosis (Mtb) much faster than clinically used TB drugs. Lipid I isolated from Mtb contains the C50-prenyl unit that shows very poor water-solubility, and thus, this chemical characteristic of lipid I renders MurX enzyme assays impractical for screening and lacks reproducibility of the enzyme assays. We have established a scalable chemical synthesis of Park’s nucleotide-Nε-dansylthiourea 2 that can be used as a MurX enzymatic substrate to form lipid I analogues. In our investigation of minimum structure requirement of the prenyl phosphate in the MraY/MurX-catalyzed lipid I analogue synthesis with 2, we found that neryl phosphate (C10-phosphate) can be recognized by MraY/MurX to generate the water-soluble lipid I analogue in quantitative yield under the optimized conditions. Herein, we report a rapid and robust analytical method for quantifying MraY/MurX inhibitory activity of library molecules. PMID:24939461

  8. 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...

  9. 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...

  10. The Supply of Women Enlistees and Their Utilization in the Navy

    DTIC Science & Technology

    1976-06-01

    Chief of Naval Res Bur Applied Social Research Dir of Res Prof. Paul F. Lazarsfeld Asst Chief for Res Sp Asst for Res, OASN (M&RA) Naval Res Branch...Research Organization. -44- TR-1283 [10] HODGE, ROBERT W., SIEGEL, PAUL M., and ROSSI, PETER H. "Occupa- tional Prestige in the United States, 1925-63