Sample records for valodas tulkojusi mra

  1. 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.

  2. High-resolution gadolinium-enhanced 3D MRA of the infrapopliteal arteries. Lessons for improving bolus-chase peripheral MRA.

    PubMed

    Hood, Maureen N; Ho, Vincent B; Foo, Thomas K F; Marcos, Hani B; Hess, Sandra L; Choyke, Peter L

    2002-09-01

    Peripheral magnetic resonance angiography (MRA) is growing in use. However, methods of performing peripheral MRA vary widely and continue to be optimized, especially for improvement in illustration of infrapopliteal arteries. The main purpose of this project was to identify imaging factors that can improve arterial visualization in the lower leg using bolus chase peripheral MRA. Eighteen healthy adults were imaged on a 1.5T MR scanner. The calf was imaged using conventional three-station bolus chase three-dimensional (3D) MRA, two dimensional (2D) time-of-flight (TOF) MRA and single-station Gadolinium (Gd)-enhanced 3D MRA. Observer comparisons of vessel visualization, signal to noise ratios (SNR), contrast to noise ratios (CNR) and spatial resolution comparisons were performed. Arterial SNR and CNR were similar for all three techniques. However, arterial visualization was dramatically improved on dedicated, arterial-phase Gd-enhanced 3D MRA compared with the multi-station bolus chase MRA and 2D TOF MRA. This improvement was related to optimization of Gd-enhanced 3D MRA parameters (fast injection rate of 2 mL/sec, high spatial resolution imaging, the use of dedicated phased array coils, elliptical centric k-space sampling and accurate arterial phase timing for image acquisition). The visualization of the infrapopliteal arteries can be substantially improved in bolus chase peripheral MRA if voxel size, contrast delivery, and central k-space data acquisition for arterial enhancement are optimized. Improvements in peripheral MRA should be directed at these parameters.

  3. Comparison of 3D TOF-MRA and 3D CE-MRA at 3T for imaging of intracranial aneurysms.

    PubMed

    Cirillo, Mario; Scomazzoni, Francesco; Cirillo, Luigi; Cadioli, Marcello; Simionato, Franco; Iadanza, Antonella; Kirchin, Miles; Righi, Claudio; Anzalone, Nicoletta

    2013-12-01

    To compare 3T elliptical-centric CE MRA with 3T TOF MRA for the detection and characterization of unruptured intracranial aneurysms (UIAs), by using digital subtracted angiography (DSA) as reference. Twenty-nine patients (12 male, 17 female; mean age: 62 years) with 41 aneurysms (34 saccular, 7 fusiform; mean diameter: 8.85 mm [range 2.0-26.4mm]) were evaluated with MRA at 3T each underwent 3D TOF-MRA examination without contrast and then a 3D contrast-enhanced (CE-MRA) examination with 0.1mmol/kg bodyweight gadobenate dimeglumine and k-space elliptic mapping (Contrast ENhanced Timing Robust Angiography [CENTRA]). Both TOF and CE-MRA images were used to evaluate morphologic features that impact the risk of rupture and the selection of a treatment. Almost half (20/41) of UIAs were located in the internal carotid artery, 7 in the anterior communicating artery, 9 in the middle cerebral artery and 4 in the vertebro-basilar arterial system. All patients also underwent DSA before or after the MR examination. The CE-MRA results were in all cases consistent with the DSA dataset. No differences were noted between 3D TOF-MRA and CE-MRA concerning the detection and location of the 41 aneurysms or visualization of the parental artery. Differences were apparent concerning the visualization of morphologic features, especially for large aneurysms (>13 mm). An irregular sac shape was demonstrated for 21 aneurysms on CE-MRA but only 13/21 aneurysms on 3D TOF-MRA. Likewise, CE-MRA permitted visualization of an aneurismal neck and calculation of the sac/neck ratio for all 34 aneurysms with a neck demonstrated at DSA. Conversely, a neck was visible for only 24/34 aneurysms at 3D TOF-MRA. 3D CE-MRA detected 15 aneurysms with branches originating from the sac and/or neck, whereas branches were recognized in only 12/15 aneurysms at 3D TOF-MRA. For evaluation of intracranial aneurysms at 3T, 3D CE-MRA is superior to 3D TOF-MRA for assessment of sac shape, detection of aneurysmal neck, and

  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. Comparison of TOF MRA, Contrast-Enhanced MRA and Subtracted CTA from CTP in Residue Evaluation of Treated Intracranial Aneurysms.

    PubMed

    Dündar, Tolga Turan; Aralaşmak, Ayşe; Özdemir, Hüseyin; Seyithanoğlu, Mehmet Hakan; Uysal, Ömer; Toprak, Hüseyin; Kitiş, Serkan; Özek, Erdinç; Alkan, Alpay

    2017-10-18

    To compare effectiveness of contrast-enhanced MRA (CE-MRA), 3D-Time-of-flight MRA (3D-TOF-MRA) and subtracted CTA from CTP (sub-CTA) in residue evaluation of intracranial aneurysms treated either with coiling or clipping. Sixteen treated aneurysms, which were evaluated with three methods within two weeks after the operation, were enrolled. The success of each imaging techniques in demonstration of residue aneurysm and nearby vessels was compared by Fisher\\'s Exact Test. The differences among three was evaluated by Cochran\\'s Q test (p ≤ 0.05). Perfusion abnormality was noted in % 81 of clipped and none of coiled patients. Vessel visualization in the vicinity of aneurysm was better in sub-CTA, followed by CE-MRA. In clipped aneurysms, sub-CTA revealed residue aneurysms in % 16,7 of the patients while 3D-TOF-MRA and CE-MRA revealed none. In coiled aneurysms, CE-MRA revealed residue aneurysms in 100 %, and TOF-MRA in 33,3 % while sub-CTA revealed none. Although dramatic differences were noted in the evaluation of residue aneurysm as well as nearby vessel visualization, no statistical significance noted due to very few patients in subcategories Conclusion: This is first study comparing the effectiveness of CE-MRA, 3D-TOF MRA and sub-CTA in residue aneurysms evaluation. Vessel visualization in the vicinity of aneurysm was better in sub-CTA in all regardless of coiling or clipping. Residue aneurysms were more commonly revealed by CE-MRA in coiled patients and more commonly and better shown by sub-CTA in clipped patients in addition of showing perfusion abnormality that's is more common in clipped patients.

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

    PubMed

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

    2016-08-01

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

  7. 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

  8. 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.

  9. Follow-up of intracranial aneurysms treated with stent-assisted coiling: Comparison of contrast-enhanced MRA, time-of-flight MRA, and digital subtraction angiography.

    PubMed

    Marciano, David; Soize, Sébastien; Metaxas, Georgios; Portefaix, Christophe; Pierot, Laurent

    2017-02-01

    Data about non-invasive follow-up of aneurysm after stent-assisted coiling is scarce. We aimed to compare time-of-flight (TOF) magnetic resonance angiography (MRA) (3D-TOF-MRA) and contrast-enhanced MRA (CE-MRA) at 3-Tesla, with digital subtraction angiography (DSA) for evaluating aneurysm occlusion and parent artery patency after stent-assisted coiling. In this retrospective single-center study, patients were included if they had an intracranial aneurysm treated by stent-assisted coiling between March 2008 and June 2015, followed with both MRA sequences (3D-TOF-MRA and CE-MRA) at 3-Tesla and DSA, performed in an interval<48hours. Thirty-five aneurysms were included. Regarding aneurysm occlusion evaluation, agreement with DSA was better for CE-MRA (K=0.53) than 3D-TOF-MRA (K=0.28). Diagnostic accuracies for aneurysm remnant depiction were similar for 3D-TOF-MRA and CE-MRA (P=1). Both 3D-TOF-MRA (K=0.05) and CE-MRA (K=-0.04) were unable to detect pathological vessel compared to DSA, without difference in accuracy (P=0.68). For parent artery occlusion detection, agreement with DSA was substantial for 3D-TOF-MRA (K=0.64) and moderate for CE-MRA (K=0.45), with similar good diagnostic accuracies (P=1). After stent-assisted coiling treatment, 3D-TOF-MRA and CE-MRA demonstrated good accuracy to detect aneurysm remnant (but tended to overestimation). Although CE-MRA agreement with DSA was better, there was no statistical difference between 3D-TOF-MRA and CE-MRA accuracies. Both MRAs were unable to provide a precise evaluation of in-stent status but could detect parent vessel occlusion. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  10. Combined large field-of-view MRA and time-resolved MRA of the lower extremities: impact of acquisition order on image quality.

    PubMed

    Riffel, Philipp; Haneder, Stefan; Attenberger, Ulrike I; Brade, Joachim; Schoenberg, Stefan O; Michaely, Henrik J

    2012-10-01

    Different approaches exist for hybrid MRA of the calf station. So far, the order of the acquisition of the focused calf MRA and the large field-of-view MRA has not been scientifically evaluated. Therefore the aim of this study was to evaluate if the quality of the combined large field-of-view MRA (CTM MR angiography) and time-resolved MRA with stochastic interleaved trajectories (TWIST MRA) depends on the order of acquisition of the two contrast-enhanced studies. In this retrospective study, 40 consecutive patients (mean age 68.1 ± 8.7 years, 29 male/11 female) who had undergone an MR angiographic protocol that consisted of CTM-MRA (TR/TE, 2.4/1.0 ms; 21° flip angle; isotropic resolution 1.2mm; gadolinium dose, 0.07 mmol/kg) and TWIST-MRA (TR/TE 2.8/1.1; 20° flip angle; isotropic resolution 1.1mm; temporal resolution 5.5s, gadolinium dose, 0.03 mmol/kg), were included. In the first group (group 1) TWIST-MRA of the calf station was performed 1-2 min after CTM-MRA. In the second group (group 2) CTM-MRA was performed 1-2 min after TWIST-MRA of the calf station. The image quality of CTM-MRA and TWIST-MRA were evaluated by 2 two independent radiologists in consensus according to a 4-point Likert-like rating scale assessing overall image quality on a segmental basis. Venous overlay was assessed per examination. In the CTM-MRA, 1360 segments were included in the assessment of image quality. CTM-MRA was diagnostic in 95% (1289/1360) of segments. There was a significant difference (p<0.0001) between both groups with regard to the number of segments rated as excellent and moderate. The image quality was rated as excellent in group 1 in 80% (514/640 segments) and in group 2 in 67% (432/649), respectively (p<0.0001). In contrast, the image quality was rated as moderate in the first group in 5% (33/640) and in the second group in 19% (121/649) respectively (p<0.0001). The venous overlay was disturbing in 10% in group 1 and 20% in group 2 (p=n.s.). If a combined hybrid MRA

  11. 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.

  12. Contrast-enhanced peripheral MRA: technique and contrast agents.

    PubMed

    Nielsen, Yousef W; Thomsen, Henrik S

    2012-09-01

    In the last decade contrast-enhanced magnetic resonance angiography (CE-MRA) has gained wide acceptance as a valuable tool in the diagnostic work-up of patients with peripheral arterial disease. This review presents current concepts in peripheral CE-MRA with emphasis on MRI technique and contrast agents. Peripheral CE-MRA is defined as an MR angiogram of the arteries from the aortic bifurcation to the feet. Advantages of CE-MRA include minimal invasiveness and lack of ionizing radiation. The basic technique employed for peripheral CE-MRA is the bolus-chase method. With this method a paramagnetic MRI contrast agent is injected intravenously and T1-weighted images are acquired in the subsequent arterial first-pass phase. In order to achieve high quality MR angiograms without interfering venous contamination or artifacts, a number of factors need to be taken into account. This includes magnetic field strength of the MRI system, receiver coil configuration, use of parallel imaging, contrast bolus timing technique, and k-space filling strategies. Furthermore, it is possible to optimize peripheral CE-MRA using venous compression techniques, hybrid scan protocols, time-resolved imaging, and steady-state MRA. Gadolinium(Gd)-based contrast agents are used for CE-MRA of the peripheral arteries. Extracellular Gd agents have a pharmacokinetic profile similar to iodinated contrast media. Accordingly, these agents are employed for first-pass MRA. Blood-pool Gd-based agents are characterized by prolonged intravascular stay, due to macromolecular structure or protein binding. These agents can be used for first-pass, as well as steady-state MRA. Some Gd-based contrast agents with low thermodynamic stability have been linked to development of nephrogenic systemic fibrosis in patients with severe renal insufficiency. Using optimized technique and a stable MRI contrast agent, peripheral CE-MRA is a safe procedure with diagnostic accuracy close to that of conventional catheter X

  13. Follow-up assessment of coiled intracranial aneurysms using zTE MRA as compared with TOF MRA: a preliminary image quality study.

    PubMed

    Shang, Song'an; Ye, Jing; Luo, Xianfu; Qu, Jianxun; Zhen, Yong; Wu, Jingtao

    2017-10-01

    To prospectively assess coiled intracranial aneurysms using a novel non-contrast enhanced zero echo time (zTE) MR angiography (MRA) method, and compare its image quality with time-of-flight (TOF) MRA, using digital subtraction angiography (DSA) as reference. Twenty-five patients (10 males and 15 females; age 53.96 ± 12.46 years) were enrolled in this monocentric study. MRA sequences were performed 24 h before DSA. Susceptibility artefact intensity and flow signal within the parent artery were carried out using a 4-point scale. Occlusion status was assessed using the 3-grade Montreal scale. Scores of zTE were higher than TOF for both susceptibility artefact intensity (3.42 ± 0.64, 2.92 ± 0.63, P = 0.01) and flow signal (3.66 ± 0.95, 3.24 ± 1.24, P = 0.01). DSA revealed 17 complete occlusions, five residual neck aneurysms and two residual aneurysms. Inter-observer agreement was excellent (weighted κ: 0.89) for zTE and good (weighted κ: 0.68) for TOF. Intermodality agreement was excellent for zTE (weighted κ: 0.95) and good for TOF (weighted κ: 0.80). Correlations of both MRA sequences with DSA were high (zTE, Spearman's ρ: 0.91; TOF, Spearman's ρ: 0.81). zTE MRA showed promising results for follow-up assessment of coiled intracranial aneurysms and was superior to TOF MRA for visualizing the parent artery and evaluating occlusion status. • Various MRA sequences were applied for follow-up assessment of coiled intracranial aneurysms. • zTE MRA was less sensitive to susceptibility artefacts and haemodynamics. • In this monocentric study, zTE MRA was equivalent to DSA. • zTE MRA maybe an alternative to TOF MRA for follow-up assessment.

  14. Contrast-enhanced time-resolved 4D MRA of congenital heart and vessel anomalies: image quality and diagnostic value compared with 3D MRA.

    PubMed

    Vogt, Florian M; Theysohn, Jens M; Michna, Dariusz; Hunold, Peter; Neudorf, Ulrich; Kinner, Sonja; Barkhausen, Jörg; Quick, Harald H

    2013-09-01

    To evaluate time-resolved interleaved stochastic trajectories (TWIST) contrast-enhanced 4D magnetic resonance angiography (MRA) and compare it with 3D FLASH MRA in patients with congenital heart and vessel anomalies. Twenty-six patients with congenital heart and vessel anomalies underwent contrast-enhanced MRA with both 3D FLASH and 4D TWIST MRA. Images were subjectively evaluated regarding total image quality, artefacts, diagnostic value and added diagnostic value of 4D dynamic imaging. Quantitative comparison included signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and vessel sharpness measurements. Three-dimensional FLASH MRA was judged to be significantly better in terms of image quality (4.0 ± 0.6 vs 3.4 ± 0.6, P < 0.05) and artefacts (3.8 ± 0.4 vs 3.3 ± 0.5, P < 0.05); no difference in diagnostic value was found (4.2 ± 0.4 vs 4.0 ± 0.4); important additional functional information was found in 21/26 patients. SNR and CNR were higher in the pulmonary trunk in 4D TWIST, but slightly higher in the systemic arteries in 3D FLASH. No difference in vessel sharpness delineation was found. Although image quality was inferior compared with 3D FLASH MRA, 4D TWIST MRA yields robust images and added diagnostic value through dynamic acquisition was found. Thus, 4D TWIST MRA is an attractive alternative to 3D FLASH MRA. • New magnetic resonance angiography (MRA) techniques are increasingly introduced for congenital cardiovascular problems. • Time-resolved angiography with interleaved stochastic trajectories (TWIST) is an example. • Four-dimensional TWIST MRA provided inferior image quality compared to 3D FLASH MRA but without significant difference in vessel sharpness. • Four-dimensional TWIST MRA gave added diagnostic value.

  15. 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

  16. 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.

  17. Unenhanced respiratory-gated magnetic resonance angiography (MRA) of renal artery in hypertensive patients using true fast imaging with steady-state precession technique compared with contrast-enhanced MRA.

    PubMed

    Zhang, Weisheng; Lin, Jiang; Wang, Shaowu; Lv, Peng; Wang, Lili; Liu, Hao; Chen, Caizhong; Zeng, Mengsu

    2014-01-01

    This study was aimed to evaluate the accuracy of "True Fast Imaging with Steady-State Precession" (TrueFISP) MR angiography (MRA) for diagnosis of renal arterial stenosis (RAS) in hypertensive patients. Twenty-two patients underwent both TrueFISP MRA and contrast-enhanced MRA (CE-MRA) on a 1.5-T MR imager. Volume of main renal arteries, length of maximal visible renal arteries, number of visualized branches, stenotic grade, and subjective quality were compared. Paired 2-tailed Student t test and Wilcoxon signed rank test were applied to evaluate the significance of these variables. Volume of main renal arteries, length of maximal visible renal arteries, and number of branches indicated no significant difference between the 2 techniques (P > 0.05). Stenotic degree of 10 RAS was greater on CE-MRA than on TrueFISP MRA. Qualitative scores from TrueFISP MRA were higher than those from CE-MRA (P < 0.05). TrueFISP MRA is a reliable and accurate method for evaluating RAS.

  18. Appropriate Minimal Dose of Gadobutrol for 3D Time-Resolved MRA of the Supra-Aortic Arteries: Comparison with Conventional Single-Phase High-Resolution 3D Contrast-Enhanced MRA.

    PubMed

    Bak, S H; Roh, H G; Moon, W-J; Choi, J W; An, H S

    2017-07-01

    The development of nephrogenic systemic fibrosis and neural tissue deposition is gadolinium dose-dependent. The purpose of this study was to determine the appropriate minimal dose of gadobutrol with time-resolved MRA to assess supra-aortic arterial stenosis with contrast-enhanced MRA as a reference standard. Four hundred sixty-two consecutive patients underwent both standard-dose contrast-enhanced MRA and low-dose time-resolved MRA and were classified into 3 groups; group A (a constant dose of 1 mL for time-resolved MRA), group B (2 mL), or group C (3 mL). All studies were independently evaluated by 2 radiologists for image quality by using a 5-point scale (from 0 = failure to 4 = excellent), grading of arterial stenosis (0 = normal, 1 = mild [<30%], 2 = moderate [30%-69%], 3 = severe to occlusion [≥70%]), and signal-to-noise ratio. The image quality of time-resolved MRA was similar to that of contrast-enhanced MRA in groups B and C, but it was inferior to contrast-enhanced MRA in group A. For the grading of arterial stenosis, there was an excellent correlation between contrast-enhanced MRA and time-resolved MRA ( R = 0.957 for group A, R = 0.988 for group B, R = 0.991 for group C). The SNR of time-resolved MRA tended to be lower than that of contrast-enhanced MRA in groups A and B. However, SNR was higher for time-resolved MRA compared with contrast-enhanced MRA in group C. Low-dose time-resolved MRA is feasible in the evaluation of supra-aortic stenosis and could be used as an alternative to contrast-enhanced MRA for a diagnostic technique in high-risk populations. © 2017 by American Journal of Neuroradiology.

  19. MR Angiography (MRA)

    MedlinePlus

    ... resonance angiography (MRA), a powerful magnetic field, radio frequency waves and a computer produce detailed images of ... test. If you have claustrophobia (fear of enclosed spaces) or anxiety, you may want to ask your ...

  20. Visualization of lenticulostriate arteries at 3T: Optimization of slice-selective off-resonance sinc pulse-prepared TOF-MRA and its comparison with flow-sensitive black-blood MRA.

    PubMed

    Okuchi, Sachi; Okada, Tomohisa; Fujimoto, Koji; Fushimi, Yasutaka; Kido, Aki; Yamamoto, Akira; Kanagaki, Mitsunori; Dodo, Toshiki; Mehemed, Taha M; Miyazaki, Mitsue; Zhou, Xiangzhi; Togashi, Kaori

    2014-06-01

    To optimize visualization of lenticulostriate artery (LSA) by time-of-flight (TOF) magnetic resonance angiography (MRA) with slice-selective off-resonance sinc (SORS) saturation transfer contrast pulses and to compare capability of optimal TOF-MRA and flow-sensitive black-blood (FSBB) MRA to visualize the LSA at 3T. This study was approved by the local ethics committee, and written informed consent was obtained from all the subjects. TOF-MRA was optimized in 20 subjects by comparing SORS pulses of different flip angles: 0, 400°, and 750°. Numbers of LSAs were counted. The optimal TOF-MRA was compared to FSBB-MRA in 21 subjects. Images were evaluated by the numbers and length of visualized LSAs. LSAs were significantly more visualized in TOF-MRA with SORS pulses of 400° than others (P < .003). When the optimal TOF-MRA was compared to FSBB-MRA, the visualization of LSA using FSBB (mean branch numbers 11.1, 95% confidence interval (CI) 10.0-12.1; mean total length 236 mm, 95% CI 210-263 mm) was significantly better than using TOF (4.7, 95% CI 4.1-5.3; 78 mm, 95% CI 67-89 mm) for both numbers and length of the LSA (P < .0001). LSA visualization was best with 400° SORS pulses for TOF-MRA but FSBB-MRA was better than TOF-MRA, which indicates its clinical potential to investigate the LSA on a 3T magnetic resonance imaging. Copyright © 2014 AUR. Published by Elsevier Inc. All rights reserved.

  1. Quadruple Inversion-Recovery b-SSFP MRA of the Abdomen: Initial Clinical Validation

    PubMed Central

    Atanasova, Iliyana P.; Lim, Ruth P.; Chandarana, Hersh; Storey, Pippa; Bruno, Mary T; Kim, Daniel; Lee, Vivian S.

    2014-01-01

    The purpose of this study is to assess the image quality and diagnostic accuracy of non-contrast quadruple inversion-recovery balanced-SSFP MRA (QIR MRA) for detection of aortoiliac disease in a clinical population. QIR MRA was performed in 26 patients referred for routine clinical gadolinium-enhanced MRA (Gd-MRA) for known or suspected aortoiliac disease. Non-contrast images were independently evaluated for image qualityand degree of stenosisby two radiologists, usingconsensus Gd-MRA as the reference standard. Hemodynamically significant stenosis (≥ 50%) was found in 10% (22/226) of all evaluable segments on Gd-MRA. The sensitivity and specificity for stenosis evaluation by QIR MRA for the two readers were 86%/86% and 95%/93% respectively. Negative predictive value and positive predictive value were 98%/98% and 63%/53% respectively. For stenosis evaluation of the aortoiliac region QIR MRA showed good agreement with the reference standard with high negative predictive value and a tendency to overestimate mild disease presumably due to the flow-dependence of the technique. QIR MRA could be a reasonable alternative to Gd-MRA for ruling out stenosis when contrast is contraindicated due to impaired kidney function or in patients who undergo abdominal MRA for screening purposes. Further work is necessary to improve performance and justify routine clinical use. PMID:24998363

  2. CE-MRA for follow-up of aneurysms post stent-assisted coiling.

    PubMed

    Agid, R; Schaaf, M; Farb, Ri

    2012-09-01

    This study compared the accuracy of contrast-enhanced MR angiography (CE-MRA) to intra-arterial cerebral angiography (IA-DSA) for assessment of intracranial aneurysms after stent-assisted coiling and to check if the presence of a stent in the parent artery diminishes the accuracy of CE-MRA. Consecutive patients with cerebral aneurysms treated by stent-assisted coiling were evaluated retrospectively. Matching follow-up CE-MRA and IA-DSA were evaluated separately. Evaluation included the presence of aneurysmal remnant, patency and stenosis of parent artery. Twenty-seven patients with 28 aneurysms and 33 matched CE-MRA and IA-DSA studies were evaluated. Nineteen aneurysmal remnants were seen on CE-MRA and 16 on IA-DSA. CE-MRA diagnosed three aneurysmal remnants not appreciated on IA-DSA. Five other remnants were larger on CE-MRA than IA-DSA. None of the remnants were missed on CE-MRA. Parent arteries were patent on both modalities. CE-MRA showed false stenosis of the stented artery in six cases and exaggerated stenosis in two. In 18 cases, CE-MRA showed a short focal "pseudo-stenosis" where the stent's marker bands were located. This was noted whenever the stent's marker bands were located in an artery with luminal diameter ≤2 mm and was called "marker band effect". CE-MRA is an accurate technique for follow-up of aneurysms post stent-assisted coiling with excellent depiction of remnants in spite of the presence of a stent. Apparent stenosis of the stented parent artery on CE-MRA is often false or exaggerated. "Marker band effect" should be recognized as an artifact that appears when stent's marker bands are in a small artery.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Eraso, Jesus M.; Markillie, Lye Meng; Mitchell, Hugh D.

    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,more » 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.« less

  4. Quadruple inversion-recovery b-SSFP MRA of the abdomen: initial clinical validation.

    PubMed

    Atanasova, Iliyana P; Lim, Ruth P; Chandarana, Hersh; Storey, Pippa; Bruno, Mary T; Kim, Daniel; Lee, Vivian S

    2014-09-01

    The purpose of this study is to assess the image quality and diagnostic accuracy of non-contrast quadruple inversion-recovery balanced-SSFP MRA (QIR MRA) for detection of aortoiliac disease in a clinical population. QIR MRA was performed in 26 patients referred for routine clinical gadolinium-enhanced MRA (Gd-MRA) for known or suspected aortoiliac disease. Non-contrast images were independently evaluated for image quality and degree of stenosis by two radiologists, using consensus Gd-MRA as the reference standard. Hemodynamically significant stenosis (≥50%) was found in 10% (22/226) of all evaluable segments on Gd-MRA. The sensitivity and specificity for stenosis evaluation by QIR MRA for the two readers were 86%/86% and 95%/93% respectively. Negative predictive value and positive predictive value were 98%/98% and 63%/53% respectively. For stenosis evaluation of the aortoiliac region QIR MRA showed good agreement with the reference standard with high negative predictive value and a tendency to overestimate mild disease presumably due to the flow-dependence of the technique. QIR MRA could be a reasonable alternative to Gd-MRA for ruling out stenosis when contrast is contraindicated due to impaired kidney function or in patients who undergo abdominal MRA for screening purposes. Further work is necessary to improve performance and justify routine clinical use. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  5. CE-MRA for Follow-up of Aneurysms Post Stent-Assisted Coiling

    PubMed Central

    Agid, R.; Schaaf, M.; Farb, RI.

    2012-01-01

    Summary This study compared the accuracy of contrast-enhanced MR angiography (CE-MRA) to intra-arterial cerebral angiography (IA-DSA) for assessment of intracranial aneurysms after stent-assisted coiling and to check if the presence of a stent in the parent artery diminishes the accuracy of CE-MRA. Consecutive patients with cerebral aneurysms treated by stent-assisted coiling were evaluated retrospectively. Matching follow-up CE-MRA and IA-DSA were evaluated separately. Evaluation included the presence of aneurysmal remnant, patency and stenosis of parent artery. Twenty-seven patients with 28 aneurysms and 33 matched CE-MRA and IA-DSA studies were evaluated. Nineteen aneurysmal remnants were seen on CE-MRA and 16 on IA-DSA. CE-MRA diagnosed three aneurysmal remnants not appreciated on IA-DSA. Five other remnants were larger on CE-MRA than IA-DSA. None of the remnants were missed on CE-MRA. Parent arteries were patent on both modalities. CE-MRA showed false stenosis of the stented artery in six cases and exaggerated stenosis in two. In 18 cases, CE-MRA showed a short focal “pseudo-stenosis” where the stent’s marker bands were located. This was noted whenever the stent’s marker bands were located in an artery with luminal diameter ≤2 mm and was called “marker band effect”. CE-MRA is an accurate technique for follow-up of aneurysms post stent-assisted coiling with excellent depiction of remnants in spite of the presence of a stent. Apparent stenosis of the stented parent artery on CE-MRA is often false or exaggerated. “Marker band effect” should be recognized as an artifact that appears when stent’s marker bands are in a small artery. PMID:22958765

  6. Is MRA an unnecessary expense in the management of a clinically unstable shoulder? A comparison of MRA and arthroscopic findings in 90 patients.

    PubMed

    Jonas, Sam C; Walton, Michael J; Sarangi, Partha P

    2012-06-01

    In detection of glenoid labrum pathology, MR arthrography (MRA) has shown sensitivities of 88-100% and specificities of 89-93%. However, our practice suggested that there may be a higher frequency of falsely negative reports. We assessed the accuracy of this costly modality in practice. We retrospectively reviewed MRA reports of 90 consecutive patients with clinical shoulder instability who had undergone shoulder arthroscopy. All had a history of traumatic anterior shoulder dislocation and had positive anterior apprehension tests. All underwent arthroscopy and stabilization during the same procedure. We compared the findings, using arthroscopic findings as the gold standard in the identification of glenoid labrum pathology. 83 of the 90 patients had glenoid labrum tears at arthroscopy. Only 54 were correctly identified at MRA. All normal glenoid labra were identified at MRA. This gave a sensitivity of 65% and a specificity of 100% in identification of all types of glenoid labrum tear. 74 patients had anterior glenoid labral tears that were detected at an even lower rate of sensitivity (58%). The sensitivity of MRA in this series was substantially lower than previously published, suggesting that MRA may not be as reliable a diagnostic imaging modality in glenohumeral instability as previously thought. Our findings highlight the importance of an accurate history and clinical examination in the management of glenohumeral instability. The need for MRA may not be as high as is currently believed.

  7. Pulmonary MRA: differentiation of pulmonary embolism from truncation artefact.

    PubMed

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

    2014-08-01

    Truncation artefact (Gibbs ringing) causes central signal drop within vessels in pulmonary magnetic resonance angiography (MRA) that can be mistaken for emboli, reducing diagnostic accuracy for pulmonary embolism (PE). We propose a quantitative approach to differentiate truncation artefact from PE. Twenty-eight patients who underwent pulmonary computed tomography angiography (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. A total of 65 signal intensity drops were identified on MRA. Of these, 48 (74%) were artefacts and 17 (26%) were PE, as confirmed by CTA. Truncation artefacts had a significantly lower median signal drop than PE on both arterial-phase (26% [range 12-58%] vs. 85% [range 53-91%]) and delayed-phase MRA (26% [range 11-55%] vs. 77% [range 47-89%]), p < 0.0001 for both. Receiver operating characteristic (ROC) analyses revealed a threshold value of 51% (arterial phase) and 47% signal drop (delayed phase) to differentiate between truncation artefact and PE with 100% sensitivity and greater than 90% specificity. Quantitative signal drop is an objective tool to help differentiate truncation artefact and pulmonary embolism in pulmonary MRA. • Inexperienced readers may mistake truncation artefacts for emboli on pulmonary MRA • Pulmonary emboli have non-uniform signal drop • 51% (arterial phase) and 47% (delayed phase) cut-off differentiates truncation artefact from PE • Quantitative signal drop measurement enables more accurate pulmonary embolism diagnosis with MRA.

  8. Interest of HYPR flow dynamic MRA for characterization of cerebral arteriovenous malformations: comparison with TRICKS MRA and catheter DSA.

    PubMed

    Dautry, Raphaël; Edjlali, Myriam; Roca, Pauline; Rabrait, Cécile; Wu, Yijing; Johnson, Kevin; Wieben, Olivier; Trystram, Denis; Rodriguez-Régent, Christine; Alshareef, Fawaz; Turski, Patrick; Meder, Jean-François; Naggara, Olivier; Oppenheim, Catherine

    2015-11-01

    HYPR flow is a 3D dynamic contrast-enhanced MRA technique providing isotropic sub-millimetre resolution with half-second temporal resolution. We compared HYPR flow and time-resolved imaging of contrast kinetics (TRICKS) MRA for the characterization of cerebral arteriovenous malformations (cAVMs), using catheter DSA as reference. Twenty-two patients underwent HYPR flow and TRICKS MRA within 15 days of DSA. HYPR flow and TRICKS datasets were reviewed separately by two readers for image quality, Spetzler-Martin grade, venous ectasia, and deep venous drainage. Image quality was better for HYPR flow than for TRICKS (narrower full width at half maximum; larger arterial diagnostic window; greater number of arterial frames, P ≤ 0.05). Using HYPR flow, inter-reader agreement was excellent for all cAVM characteristics. The agreement with DSA for the overall Spetzler-Martin grade was excellent for HYPR flow (ICC = 0.96 and 0.98, depending on the reader) and TRICKS (ICC = 0.82 and 0.95). In comparison to TRICKS, HYPR flow showed higher concordance with DSA for the identification of venous ectasia and deep venous drainage. Owing to an excellent agreement with DSA with respect to depiction of the vascular architecture of cAVMs, HYPR flow could be useful for the non-invasive characterization of cAVMs. • Dynamic MRA is used for cerebral AVM depiction and follow-up • HYPR flow is a new, highly-resolved dynamic MRA sequence • HYPR flow provides whole brain coverage • HYPR flow provides excellent agreement with the Spetzler-Martin grade • Compared to TRICKS MRA, HYPR flow improves cerebral AVM characterization.

  9. Highly accelerated single breath-hold noncontrast thoracic MRA: evaluation in a clinical population.

    PubMed

    Lim, Ruth P; Winchester, Priscilla A; Bruno, Mary T; Xu, Jian; Storey, Pippa; McGorty, Kellyanne; Sodickson, Daniel K; Srichai, Monvadi B

    2013-03-01

    The objective of this study was to evaluate the performance of a highly accelerated breath-hold 3-dimensional noncontrast-enhanced steady-state free precession thoracic magnetic resonance angiography (NC-MRA) technique in a clinical population, including assessment of image quality, aortic dimensions, and aortic pathology, compared with electrocardiographically gated gadolinium-enhanced MRA (Gd-MRA). After approval from the institution board and informed consent were obtained, 30 patients (22 men; mean age, 53.4 years) with known or suspected aortic pathology were imaged with NC-MRA followed by Gd-MRA at a single examination at 1.5 T. Images were made anonymous and reviewed by 2 readers for aortic pathology and diagnostic confidence on a 5-point scale (1, worst; 5, best) on a patient basis. Image quality and artifacts were also evaluated in 10 vascular segments: aortic annulus, sinuses of Valsalva, sinotubular junction, ascending aorta, aortic arch, descending aorta, diaphragmatic aorta, great vessel origins, and the left main and right coronary artery origins. Finally, aortic dimensions were measured in each of the 7 aortic segments. The Wilcoxon signed rank test was used to compare diagnostic confidence, image quality, and artifact scores between NC-MRA and Gd-MRA. The paired Student t test and Bland-Altman analysis were used for comparison of aortic dimensions. All patients completed NC-MRA and Gd-MRA successfully. Vascular pathologic findings were concordant with Gd-MRA in 29 of 30 (96.7%) patients and 28 of 30 (93.3%) patients for readers 1 and 2, respectively, with high diagnostic confidence (mean [SD], 4.35 [0.77]) not significantly different from Gd-MRA (4.38 [0.64]; P = 0.74). The image quality and artifact scores were comparable with Gd-MRA in most vascular segments. Notable differences were observed at the ascending aorta, where Gd-MRA had superior image quality (4.13 [0.73]) compared with NC-MRA (3.80 [0.88]; P = 0.028), and at the coronary artery

  10. MRI and MRA of spinal cord arteriovenous shunts.

    PubMed

    Condette-Auliac, Stéphanie; Boulin, Anne; Roccatagliata, Luca; Coskun, Oguzhan; Guieu, Stéphanie; Guedin, Pierre; Rodesch, Georges

    2014-12-01

    The purpose of this review is to describe the diagnostic criteria for spinal cord arteriovenous shunts (SCAVSs) when using magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA), and to discuss the extent to which the different MRI and MRA sequences and technical parameters provide the information that is required to diagnose these lesions properly. SCAVSs are divided into four groups according to location (paraspinal, epidural, dural, or intradural) and type (fistula or nidus); each type of lesion is described. SCAVSs are responsible for neurological symptoms due to spinal cord or nerve root involvement. MRI is usually the first examination performed when a spinal cord lesion is suspected. Recognition of the image characteristics of vascular lesions is mandatory if useful sequences are to be performed-especially MRA sequences. Because the treatment of SCAVSs relies mainly on endovascular therapies, MRI and MRA help with the planning of the angiographic procedure. We explain the choice of MRA sequences and parameters, the advantages and pitfalls to be aware of in order to obtain the best visualization, and the analysis of each lesion. © 2014 Wiley Periodicals, Inc.

  11. Additive value of non-contrast MRA in the preoperative evaluation of potential liver donors.

    PubMed

    Luk, Lyndon; Shenoy-Bhangle, Anuradha S; Jimenez, Guillermo; Ahmed, Firas S; Prince, Martin R; Samstein, Benjamin; Hecht, Elizabeth M

    The purpose of this study is to compare diagnostic quality, inter-observer variability and agreement of non-contrast enhanced MRA (NC-MRA) with contrast-enhanced MRA (CE-MRA) in the evaluation of hepatic arterial anatomy. 20 potential liver donors were included in this retrospective study. NC-MRA, CE-MRA and combined data sets were randomized and reviewed by two readers. Reference standard was consensus by two senior radiologists using all data including CTA. There was no difference in IQ or diagnostic confidence between NC-MRA, CE-MRA or combined data for either reader but the arterial origin of segment IV was successfully identified on NC-MRA when CE-MRA was suboptimal. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. The Role of 3 Tesla MRA in the Detection of Intracranial Aneurysms

    PubMed Central

    Kapsalaki, Eftychia Z.; Rountas, Christos D.; Fountas, Kostas N.

    2012-01-01

    Intracranial aneurysms constitute a common pathological entity, affecting approximately 1–8% of the general population. Their early detection is essential for their prompt treatment. Digital subtraction angiography is considered the imaging method of choice. However, other noninvasive methodologies such as CTA and MRA have been employed in the investigation of patients with suspected aneurysms. MRA is a noninvasive angiographic modality requiring no radiation exposure. However, its sensitivity and diagnostic accuracy were initially inadequate. Several MRA techniques have been developed for overcoming all these drawbacks and for improving its sensitivity. 3D TOF MRA and contrast-enhanced MRA are the most commonly employed techniques. The introduction of 3 T magnetic field further increased MRA's sensitivity, allowing detection of aneurysms smaller than 3 mm. The development of newer MRA techniques may provide valuable information regarding the flow characteristics of an aneurysm. Meticulous knowledge of MRA's limitations and pitfalls is of paramount importance for avoiding any erroneous interpretation of its findings. PMID:22292121

  13. 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 MRA-plus...

  14. 5 CFR 870.708 - MRA-plus-10 annuitants.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 5 Administrative Personnel 2 2013-01-01 2013-01-01 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 MRA-plus...

  15. 5 CFR 870.708 - MRA-plus-10 annuitants.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 5 Administrative Personnel 2 2014-01-01 2014-01-01 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 MRA-plus...

  16. 5 CFR 870.708 - MRA-plus-10 annuitants.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 5 Administrative Personnel 2 2012-01-01 2012-01-01 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 MRA-plus...

  17. 5 CFR 870.708 - MRA-plus-10 annuitants.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 5 Administrative Personnel 2 2011-01-01 2011-01-01 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 MRA-plus...

  18. 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

  19. Baseline MRA predicts the treatment response to vasodilator udenafil in patients with secondary Raynaud's phenomenon.

    PubMed

    Park, J K; Park, E-A; Lee, W; Kim, Y K; Lee, E Y; Song, Y W; Lee, E B

    2014-01-01

    High-resolution MR angiography (HR-MRA) demonstrates blood flow in the digital arteries, which correlates with the severity of Raynaud's phenomenon (RP). This study investigates whether baseline HR-MRA of the hand can predict the treatment response to udenafil, a new PDE5-inhibitor, in patients with secondary RP. Baseline MRA and Doppler ultrasound were obtained in 12 patients with secondary RP. The patients were treated with udenafil 100 mg/day for 4 weeks and changes in blood flow were measured. Blood flow on MRA was scored on a 4-point scale: 0, no visible flow; 1, visible flow to the proximal phalanx; 2, to the middle phalanx; and 3, to the distal phalanx. Peak systolic velocity (PSV) was measured to determine blood flow. Paired t-test and ANOVA were used to determine the treatment response of the different MRA scores. On baseline MRA, 53.3% of digital arteries had an MRA score of 0, 25.8% MRA score of 1, 9.2% MRA score of 2, and 11.6% MRA score of 3. Overall, 4-week udenafil treatment improved digital flow (p<0.05) in all MRA scores. Digital arteries with MRA score 2 showed the best response with improvement in PSV by 14.5 mm/sec (p<0.01), whereas improvement in arteries of MRA scores 1 and 3 were not better than an MRA score of 0 (all, p>0.05). Digital arteries with moderate blood flow observed on MRA respond best to treatment with udenalfil. Therefore, baseline MRA may help predict treatment response in patients with secondary RP.

  20. Steady-state MRA techniques with a blood pool contrast agent improve visualization of pulmonary venous anatomy and left atrial patency compared with time-resolved MRA pre- and postcatheter ablation in atrial fibrillation.

    PubMed

    Rustogi, Rahul; Galizia, Mauricio; Thakrar, Darshit; Merritt, Bryce; Bi, Xiaoming; Collins, Jeremy; Carr, James C

    2015-11-01

    To compare steady-state magnetic resonance angiography (SS-MRA), using a blood pool contrast agent, with the established technique of time-resolved MRA (TR-MRA), in pulmonary vein mapping and left atrial patency. Twenty-one patients (12 males, age 58.3 ± 8.4 years; 9 females; 57 ± 10 years) undergoing pulmonary vein mapping were evaluated with TR-MRA (TWIST) and SS-MRA. Orthogonal measurements and areas for four veins per patient per technique were assessed by Friedman's test. Overall intertechnique mean difference for any pulmonary vein orthogonal measurement and area was 0.02 ± 0.34 cm (P = 0.705), and 0.2 ± 0.08 cm(2) (P < 0.001). Interobserver correlation was strong for diameter and area measurements using the three methods with a range of 0.72-0.94, and 0.87-0.97, respectively. Left atrial appendage image quality score for TR-MRA was significantly lower than the other two methods (P < 0.001). Both observers detected more stenosis on inversion recovery (IR)-True FISP compared to TR-MRA and IR-FLASH. SS-MRA with a blood pool agent compared favorably to the established technique of TR-MRA for quantitative assessment of pulmonary venous anatomy. SS-MRA offers greater spatial resolution than TR-MRA with increased confidence for ruling out left atrial appendage filling defect. © 2015 Wiley Periodicals, Inc.

  1. Non-contrast-enhanced MRA of renal artery stenosis: validation against DSA in a porcine model.

    PubMed

    Bley, T A; François, C J; Schiebler, M L; Wieben, O; Takei, N; Brittain, J H; Del Rio, A Munoz; Grist, T M; Reeder, S B

    2016-02-01

    To compare 3D-inversion-recovery balanced steady-state free precession (IR-bSSFP) non-contrast-enhanced magnetic resonance angiography (MRA) with 3D-contrast-enhanced MRA (CE-MRA) for assessment of renal artery stenosis (RAS) using digital subtraction angiography (DSA) as the reference standard. Bilateral RAS were surgically created in 12 swine. IR-bSSFP and CE-MRA were acquired at 1.5 T and compared to rotational DSA. Three experienced cardiovascular radiologists evaluated the IR-bSSFP and CE-MRA studies independently. Linear regression models were used to calibrate and assess the accuracy of IR-bSSFP and CE-MRA, separately, against DSA. The coefficient of determination and Cohen's kappa coefficient were also generated. Calibration of the three readers' RAS grading revealed R(2) values of 0.52, 0.37 and 0.59 for NCE-MRA and 0.48, 0.53 and 0.71 for CE-MRA. Inter-rater agreement demonstrated Cohen's kappa values ranging from 0.25 to 0.65. Distal renal artery branch vessels were visible to a significantly higher degree with NCE-MRA compared to CE-MRA (p < 0.001). Image quality was rated excellent for both sequences, although image noise was higher with CE-MRA (p < 0.05). In no cases did noise interfere with image interpretation. In a well-controlled animal model of surgically induced RAS, IR-bSSFP based NCE-MRA and CE-MRA accurately graded RAS with a tendency for stenosis overestimation, compared to DSA. • IR-bSSFP and CE-MRA are accurate methods for diagnosis of renal artery stenosis • IR-bSSFP and CE-MRA demonstrate excellent agreement with DSA • Both IR-bSSFP and CE-MRA have a tendency to overestimate renal artery stenosis.

  2. Efficacy and safety of gadobutrol-enhanced MRA of the renal arteries: Results from GRAMS (Gadobutrol-enhanced renal artery MRA study), a prospective, intraindividual multicenter phase 3 blinded study.

    PubMed

    Fabrega-Foster, Kelly E; Agarwal, Sheela; Rastegar, Neda; Haverstock, Daniel; Agris, Jacob M; Kamel, Ihab R

    2018-02-01

    To compare the performance of magnetic resonance angiography (MRA) with 1M gadobutrol, a high relaxivity macrocyclic contrast agent, to 2D time-of-flight MRA (ToF-MRA) using computed tomographic angiography (CTA) as the standard of reference. Primary objectives were evaluation for superiority of structural delineation and noninferiority for detection and exclusion of clinically significant disease. In all, 315 subjects underwent unenhanced and contrast-enhanced MRA with 1M gadobutrol (CE-MRA) and were scanned with 1.5T MRI equipped with an at least 6-element body coil. Evaluations were based on both centralized blinded read (BR) performed by six readers as well as investigator site interpretations for the 292 subjects who completed the study. Quantitative evaluations including percent stenosis and normal vessel measurements were also performed. Secondary endpoints included identification of accessory renal arteries, diagnosis of fibromuscular dysplasia (FMD), diagnostic confidence, and need for additional imaging. A total of 292 patients suspected of renal artery disease completed the study. CE-MRA demonstrated statistically significant improvement in assessability of vascular segments compared to ToF: 95.9% vs. 77.6% (P < 0.0001). In the BR, the sensitivity and specificity of CE-MRA were noninferior to ToF-MRA (53.4% vs. 46.6% and 95.1% vs. 85.7%, respectively). There was less error in the CE-MRA stenosis measurements (0.15 mm gadobutrol vs. 0.41 mm ToF, P < 0.05). FMD was correctly diagnosed more frequently, 10% more accessory renal arteries were identified (P < 0.01), diagnostic confidence increased (P < 0.01), and fewer additional imaging studies were recommended (P < 0.01). Gadobutrol-enhanced MRA of the renal arteries has superior visualization, more accurate vessel measurements, and may serve as a CTA alternative without any ionizing radiation. 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:572-581. © 2017 International Society for Magnetic

  3. A comparison of 4D time-resolved MRA with keyhole and 3D time-of-flight MRA at 3.0 T for the evaluation of cerebral aneurysms

    PubMed Central

    2012-01-01

    Background A subarachnoid hemorrhage (SAH) due to the rupture of a cerebral aneurysm (CA) is a devastating event associated with high rates of mortality. Magnetic resonance angiography (MRA), as a noninvasive technique, is typically used initially. The object of our study is to evaluate the feasibility of 4D time-resolved MRA with keyhole (4D-TRAK) for the diagnostic accuracy and reliability of the detection and characterization of cerebral aneurysms (CAs), with a comparison of 3D time-of-flight MRA (3D-TOF-MRA) by using DSA as a reference. Methods 3D-TOF-MRA, 4D-TRAK and 3D-DSA were performed sequentially in 52 patients with suspected CAs. 4D-TRAK was acquired using a combination of sensitivity encoding (SENSE) and CE timing robust angiography (CENTRA) k-space sampling techniques at a contrast dose of 10 ml at 3 T. Accuracy, sensitivity, specificity of 4D-TRAK and 3D-TOF-MRA were calculated and compared for the detection of CAs on patient-based and aneurysm-based evaluation using 3D-DSA as a reference. Results The overall image quality of 4D-TRAK with a contrast dose of 10 ml was in the diagnostic range but still cannot be compared with that of 3D-TOF-MRA. In 52 patients with suspected CAs, fifty-eight CAs were confirmed on 3D-DSA finally. Fifty-one (with 2 false-positives and 9 false-negatives) and 58 (with 1 false-positive and 1 false-negative) CAs were visualized on 4D-TRAK and 3D-TOF-MRA, respectively. Accuracy, sensitivity and specificity on patient-based evaluation of 4D-TRAK and 3D-TOF-MRA were 92.31%, 93.33%, 85.71% and 98.08%, 100%, 85.71%, respectively, and 74.07%, 75.00%, 66.67% and 96.30%, 95.83%, 100% on aneurysm-based evaluation in patients with multiple CAs, respectively. Subgroup analysis revealed that for 19 very small CAs (maximal diameter <3 mm, measured on 3D-DSA), 9 were missed on 4D-TRAK and 1 on 3D-TOF-MRA (P = 0.008). However, for 39 CAs with maximal diameter ≥ 3 mm, the diagnostic accuracy is equally (39 on 4D-TRAK vs. 39 on 3D-TOF-MRA

  4. A comparison of 4D time-resolved MRA with keyhole and 3D time-of-flight MRA at 3.0 T for the evaluation of cerebral aneurysms.

    PubMed

    Wu, Qian; Li, Ming-Hua

    2012-07-06

    A subarachnoid hemorrhage (SAH) due to the rupture of a cerebral aneurysm (CA) is a devastating event associated with high rates of mortality. Magnetic resonance angiography (MRA), as a noninvasive technique, is typically used initially. The object of our study is to evaluate the feasibility of 4D time-resolved MRA with keyhole (4D-TRAK) for the diagnostic accuracy and reliability of the detection and characterization of cerebral aneurysms (CAs), with a comparison of 3D time-of-flight MRA (3D-TOF-MRA) by using DSA as a reference. 3D-TOF-MRA, 4D-TRAK and 3D-DSA were performed sequentially in 52 patients with suspected CAs. 4D-TRAK was acquired using a combination of sensitivity encoding (SENSE) and CE timing robust angiography (CENTRA) k-space sampling techniques at a contrast dose of 10 ml at 3 T. Accuracy, sensitivity, specificity of 4D-TRAK and 3D-TOF-MRA were calculated and compared for the detection of CAs on patient-based and aneurysm-based evaluation using 3D-DSA as a reference. The overall image quality of 4D-TRAK with a contrast dose of 10 ml was in the diagnostic range but still cannot be compared with that of 3D-TOF-MRA. In 52 patients with suspected CAs, fifty-eight CAs were confirmed on 3D-DSA finally. Fifty-one (with 2 false-positives and 9 false-negatives) and 58 (with 1 false-positive and 1 false-negative) CAs were visualized on 4D-TRAK and 3D-TOF-MRA, respectively. Accuracy, sensitivity and specificity on patient-based evaluation of 4D-TRAK and 3D-TOF-MRA were 92.31%, 93.33%, 85.71% and 98.08%, 100%, 85.71%, respectively, and 74.07%, 75.00%, 66.67% and 96.30%, 95.83%, 100% on aneurysm-based evaluation in patients with multiple CAs, respectively. Subgroup analysis revealed that for 19 very small CAs (maximal diameter <3 mm, measured on 3D-DSA), 9 were missed on 4D-TRAK and 1 on 3D-TOF-MRA (P = 0.008). However, for 39 CAs with maximal diameter ≥ 3 mm, the diagnostic accuracy is equally (39 on 4D-TRAK vs. 39 on 3D-TOF-MRA) (P = 1). In

  5. 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.

  6. 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.

  7. Comparison of remnant size in embolized intracranial aneurysms measured at follow-up with DSA and MRA.

    PubMed

    Serafin, Zbigniew; Strześniewski, Piotr; Lasek, Władysław; Beuth, Wojciech

    2012-12-01

    The possibility of recanalization and the need for retreatment are the most important limitations of intracranial aneurysm embolization. The purpose of the study was to compare the size of aneurysm remnants measured at follow-up with three-dimensional digital subtracted angiography (3D-DSA) and magnetic resonance angiography (MRA). Twenty-six aneurysms were found incompletely occluded in 72 consecutively examined patients at a follow-up after 3 months. The diameters and volume of aneurysm remnants were compared between 3D-DSA, time-of-flight MRA (TOF-MRA), contrast-enhanced TOF-MRA (CE-TOF-MRA), and contrast-enhanced MRA (CE-MRA) at 1.5 T. There was a significant correlation between remnant volumes calculated based on 3D-DSA and all MRA modalities. The intraobserver variability of the measurements ranged from 3.4 to 4.1 % and the interobserver variability from 5.8 to 7.3 %. There were no significant differences in the variability between the techniques. The mean residual filling volume ranged from 16.3 ± 19.0 mm(3) in TOF-MRA to 30.5 ± 44.6 mm(3) in 3D-DSA (P < 0.04). Significant differences were found in the volumes measured with 3D-DSA and CE-MRA as compared to TOF-MRA and CE-TOF-MRA (P < 0.01). There was a moderate significant correlation between the residual filling and the relative error of measurement in the case of TOF-MRA and CE-TOF-MRA. TOF-MRA seems to underestimate the size of aneurysm remnants detected at follow-up and should not be used as a sole imaging method to decide on re-embolization.

  8. MRA versus DSA for follow-up of coiled intracranial aneurysms: a meta-analysis.

    PubMed

    van Amerongen, M J; Boogaarts, H D; de Vries, J; Verbeek, A L M; Meijer, F J A; Prokop, M; Bartels, R H M A

    2014-09-01

    MR angiography is proposed as a safer and less expensive alternative to the reference standard, DSA, in the follow-up of intracranial aneurysms treated with endovascular coil occlusion. We performed a systematic review and meta-analysis to evaluate the accuracy of TOF-MRA and contrast-enhanced MRA in detecting residual flow in the follow-up of coiled intracranial aneurysms. Literature was reviewed through the PubMed, Cochrane, and EMBASE data bases. In comparison with DSA, the sensitivity of TOF-MRA was 86% (95% CI: 82-89%), with a specificity of 84% (95% CI: 81-88%), for the detection of any recurrent flow. For contrast-enhanced MRA, the sensitivity and specificity were 86% (95% CI: 82-89%) and 89% (95% CI: 85-92%), respectively. Both TOF-MRA and contrast-enhanced MRA are shown to be highly accurate for detection of any recanalization in intracranial aneurysms treated with endovascular coil occlusion. © 2014 by American Journal of Neuroradiology.

  9. Comparison of carotid plaque ulcer detection using contrast-enhanced and time-of-flight MRA techniques.

    PubMed

    Etesami, M; Hoi, Y; Steinman, D A; Gujar, S K; Nidecker, A E; Astor, B C; Portanova, A; Qiao, Y; Abdalla, W M A; Wasserman, B A

    2013-01-01

    Ulceration in carotid plaque is a risk indicator for ischemic stroke. Our aim was to compare plaque ulcer detection by standard TOF and CE-MRA techniques and to identify factors that influence its detection. Carotid MR imaging scans were acquired on 2066 participants in the ARIC study. We studied the 600 thickest plaques. TOF-MRA, CE-MRA, and black-blood MR images were analyzed together to define ulcer presence (plaque surface niche ≥2 mm in depth). Sixty ulcerated arteries were detected. These arteries were randomly assigned, along with 40 nonulcerated plaques from the remaining 540, for evaluation of ulcer presence by 2 neuroradiologists. Associations between ulcer detection and ulcer characteristics, including orientation, location, and size, were determined and explored by CFD modeling. One CE-MRA and 3 TOF-MRAs were noninterpretable and excluded. Of 71 ulcers in 56 arteries, readers detected an average of 39 (55%) on both TOF-MRA and CE-MRA, 26.5 (37.5%) only on CE-MRA, and 1 (1.5%) only on TOF-MRA, missing 4.5 (6%) ulcers by both methods. Ulcer detection by TOF-MRA was associated with its orientation (distally pointing versus perpendicular: OR = 5.57 [95% CI, 1.08-28.65]; proximally pointing versus perpendicular: OR = 0.21 [95% CI, 0.14-0.29]); location relative to point of maximum stenosis (distal versus isolevel: OR = 5.17 [95% CI, 2.10-12.70]); and neck-to-depth ratio (OR = 1.96 [95% CI, 1.11-3.45]) after controlling for stenosis and ulcer volume. CE-MRA detects more ulcers than TOF-MRA in carotid plaques. Missed ulcers on TOF-MRA are influenced by ulcer orientation, location relative to point of maximum stenosis, and neck-to-depth ratio.

  10. Ultra high field TOF-MRA: A method to visualize small cerebral vessels. 7T TOF-MRA sequence parameters on different MRI scanners - Literature review.

    PubMed

    Grochowski, Cezary; Staśkiewicz, Grzegorz

    Time-of-flight (TOF) angiography is a technique allowing to visualize the blood flow in vessels. 7T ToF-MRA is able to visualize the whole Circle of Willis including small perforating branches without any known side effects as opposed to usually used DSA and CTA with high exposition to the radiation and high doses of contrast as far as CTA is concerned. The aim of this review is to describe ultra-high field ToF-MRA and present different protocol data depending on the scanner used in the study. PubMed, Embase, Ovid, Google Scholar databases were searched. Selection of studies for this systematic review included 7T magnetic resonance angiography studies. We searched for type of head coil used in various studies, flip angle, echo time, repetition time, field-of-view (FOV), number of slices per slab, matrix, voxel size and acquisition time. Visualization for the small perforating vessels of the Circle of Willis, that are not fully visualized using low-field-strength MRA is improving with increasing magnetic field strength, which has been proved by several studies. Ultra-high filed ToF-MRA has found to be a superior method in depicting cerebral microvasculature. 7T ToF-MRA seems to be a reliable method for visualization of arteries up to the second order cerebral arteries and has a potential to replace DSA. Copyright © 2017. Published by Elsevier Urban & Partner Sp. z o.o.

  11. 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.

  12. 3D morphometry using automated aortic segmentation in native MR angiography: an alternative to contrast enhanced MRA?

    PubMed

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

    2014-04-01

    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. 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. 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 cm(3)) were consistently and significantly larger compared to CE-MRA (89.2±30.0 cm(3)) (P<0.001). 3D morphometry shows highly similar centerline lengths for N-MRA and CE-MRA, but systematically higher diameters and volumes for N-MRA.

  13. 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/

  14. High-resolution motion compensated MRA in patients with congenital heart disease using extracellular contrast agent at 3 Tesla.

    PubMed

    Dabir, Darius; Naehle, Claas Philip; Clauberg, Ralf; Gieseke, Juergen; Schild, Hans H; Thomas, Daniel

    2012-10-29

    Using first-pass MRA (FP-MRA) spatial resolution is limited by breath-hold duration. In addition, image quality may be hampered by respiratory and cardiac motion artefacts. In order to overcome these limitations an ECG- and navigator-gated high-resolution-MRA sequence (HR-MRA) with slow infusion of extracellular contrast agent was implemented at 3 Tesla for the assessment of congenital heart disease and compared to standard first-pass-MRA (FP-MRA). 34 patients (median age: 13 years) with congenital heart disease (CHD) were prospectively examined on a 3 Tesla system. The CMR-protocol comprised functional imaging, FP- and HR-MRA, and viability imaging. After the acquisition of the FP-MRA sequence using a single dose of extracellular contrast agent the motion compensated HR-MRA sequence with isotropic resolution was acquired while injecting the second single dose, utilizing the timeframe before viability imaging. Qualitative scores for image quality (two independent reviewers) as well as quantitative measurements of vessel sharpness and relative contrast were compared using the Wilcoxon signed-rank test. Quantitative measurements of vessel diameters were compared using the Bland-Altman test. The mean image quality score revealed significantly better image quality of the HR-MRA sequence compared to the FP-MRA sequence in all vessels of interest (ascending aorta (AA), left pulmonary artery (LPA), left superior pulmonary vein (LSPV), coronary sinus (CS), and coronary ostia (CO); all p < 0.0001). In comparison to FP-MRA, HR-MRA revealed significantly better vessel sharpness for all considered vessels (AA, LSPV and LPA; all p < 0.0001). The relative contrast of the HR-MRA sequence was less compared to the FP-MRA sequence (AA: p <0.028, main pulmonary artery: p <0.004, LSPV: p <0.005). Both, the results of the intra- and interobserver measurements of the vessel diameters revealed closer correlation and closer 95 % limits of agreement for the HR-MRA. HR-MRA revealed

  15. High-resolution motion compensated MRA in patients with congenital heart disease using extracellular contrast agent at 3 Tesla

    PubMed Central

    2012-01-01

    Background Using first-pass MRA (FP-MRA) spatial resolution is limited by breath-hold duration. In addition, image quality may be hampered by respiratory and cardiac motion artefacts. In order to overcome these limitations an ECG- and navigator-gated high-resolution-MRA sequence (HR-MRA) with slow infusion of extracellular contrast agent was implemented at 3 Tesla for the assessment of congenital heart disease and compared to standard first-pass-MRA (FP-MRA). Methods 34 patients (median age: 13 years) with congenital heart disease (CHD) were prospectively examined on a 3 Tesla system. The CMR-protocol comprised functional imaging, FP- and HR-MRA, and viability imaging. After the acquisition of the FP-MRA sequence using a single dose of extracellular contrast agent the motion compensated HR-MRA sequence with isotropic resolution was acquired while injecting the second single dose, utilizing the timeframe before viability imaging. Qualitative scores for image quality (two independent reviewers) as well as quantitative measurements of vessel sharpness and relative contrast were compared using the Wilcoxon signed-rank test. Quantitative measurements of vessel diameters were compared using the Bland-Altman test. Results The mean image quality score revealed significantly better image quality of the HR-MRA sequence compared to the FP-MRA sequence in all vessels of interest (ascending aorta (AA), left pulmonary artery (LPA), left superior pulmonary vein (LSPV), coronary sinus (CS), and coronary ostia (CO); all p < 0.0001). In comparison to FP-MRA, HR-MRA revealed significantly better vessel sharpness for all considered vessels (AA, LSPV and LPA; all p < 0.0001). The relative contrast of the HR-MRA sequence was less compared to the FP-MRA sequence (AA: p <0.028, main pulmonary artery: p <0.004, LSPV: p <0.005). Both, the results of the intra- and interobserver measurements of the vessel diameters revealed closer correlation and closer 95 % limits of agreement for

  16. 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

  17. Single Breath-Hold Non-Contrast Thoracic MRA Using Highly-Accelerated Parallel Imaging With a 32-element Coil Array

    PubMed Central

    Xu, Jian; Mcgorty, Kelly Anne; Lim, Ruth. P.; Bruno, Mary; Babb, James S.; Srichai, Monvadi B.; Kim, Daniel; Sodickson, Daniel K.

    2011-01-01

    OBJECTIVE To evaluate the feasibility of performing single breath-hold 3D thoracic non-contrast magnetic resonance angiography (NC-MRA) using highly-accelerated parallel imaging. MATERIALS AND METHODS We developed a single breath-hold NC MRA pulse sequence using balanced steady state free precession (SSFP) readout and highly-accelerated parallel imaging. In 17 subjects, highly-accelerated non-contrast MRA was compared against electrocardiogram (ECG)-triggered contrast-enhanced MRA. Anonymized images were randomized for blinded review by two independent readers for image quality, artifact severity in 8 defined vessel segments and aortic dimensions in 6 standard sites. NC-MRA and CE-MRA were compared in terms of these measures using paired sample t and Wilcoxon tests. RESULTS The overall image quality (3.21±0.68 for NC-MRA vs. 3.12±0.71 for CE-MRA) and artifact (2.87±1.01 for NC-MRA vs. 2.92±0.87 for CE-MRA) scores were not significantly different, but there were significant differences for the great vessel and coronary artery origins. NC-MRA demonstrated significantly lower aortic diameter measurements compared to CE-MRA; however, this difference was not considered clinically relevant (>3 mm difference) for less than 12% of segments, most commonly at the sinotubular junction. Mean total scan time was significantly lower for NC-MRA compared to CE-MRA (18.2 ± 6.0s vs. 28.1 ± 5.4s, respectively; p < 0.05). CONCLUSION Single breath-hold NC-MRA is feasible and can be a useful alternative for evaluation and follow-up of thoracic aortic diseases. PMID:22147589

  18. 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.

  19. Time-of-flight magnetic resonance angiography (TOF-MRA) of the normal equine head.

    PubMed

    Manso-Díaz, G; García-Real, M I; Casteleyn, C; San-Román, F; Taeymans, O

    2013-03-01

    Noncontrast magnetic resonance angiography (MRA) is widely used in human and small animal medicine. However, this technique has not yet been described in the horse, and compared to other angiographic techniques MRA could be more cost efficient and potentially safer. The aim of this study was to provide a comprehensive anatomical reference of the normal equine head vasculature using a noncontrast MRA technique, on both low- and high-field MRI. Five healthy adult horses were examined, 4 with a low-field magnet (0.23T) and the remaining one with a high-field magnet (1.5T). The magnetic resonance angiography sequence used was TOF (time-of-flight) 2D-MRA and CT images of a vascular corrosion cast were subsequently used as anatomical references. The MRA imaging protocol provided good visualisation of all major intra- and extracranial vessels down to a size of approximately 2 mm in diameter on both low- and high-field systems. This resulted in identification of vessels to the order of 3rd-4th branches of ramification. The visibility of the arteries was higher than of the veins, which showed lower signal intensity. Overall, MRA obtained with the high-field protocol provided better visualisation of the arteries, showing all the small arterial branches with a superior resolution. The use of a specific vascular sequence such as TOF 2D-MRA allows good visualisation of the equine head vasculature and eliminates the need for contrast media for MRA. Magnetic resonance angiography allows for visualisation of the vasculature of the equine head. Vessel morphology, symmetry and size can be evaluated and this may possibly play a role in preoperative planning or characterisation of diseases of the head, such as neoplasia or guttural pouch mycosis. © 2012 EVJ Ltd.

  20. 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

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

    PubMed

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

    2014-09-01

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

  2. Limited utility of MRA for acute bowel ischemia after portal venous phase CT.

    PubMed

    Shetty, Anup S; Mellnick, Vincent M; Raptis, Constantine; Loch, Ronald; Owen, Joseph; Bhalla, Sanjeev

    2015-10-01

    Mesenteric ischemia and ischemic colitis are uncommon but potentially life-threatening causes of acute abdominal pain. Portal venous phase computed tomography (CT) is routinely ordered in the emergency room setting for abdominal pain, but subsequent MR angiography may be requested for additional evaluation of the mesenteric vasculature. We compare the concordance of CT and magnetic resonance angiography (MRA) for acute bowel ischemia. Thirty-two patients who underwent contrast-enhanced MRA for bowel ischemia after having undergone CT evaluation within the preceding 2 weeks were identified. A retrospective review of imaging, treatment history, surgical, and pathology reports was conducted. Two radiologists each reviewed the imaging studies in a blinded fashion. Ten cases of bowel ischemia were confirmed by endoscopy and/or surgical pathology. CT correctly identified bowel findings in all cases. Intraobserver agreement between CT and MRA for all vessels was 0.68 and 0.63, highest for the superior mesenteric artery. Interobserver agreement was 0.74 for MRA and 0.78 for CT. Vascular findings were only directly mentioned in 10 of 32 CT reports (and 7 of 10 cases with confirmed bowel ischemia). MRA only detected two additional or alternative diagnoses. Portal venous phase CT and MRA demonstrate a high degree of concordance for vascular evaluation. Reviewed CT examinations were sufficient to assess the patency of the mesenteric vasculature, but vascular findings were not reported in most cases. A direct description within the report may have obviated the request for further MR imaging. MRA adds little value after portal venous CT in assessing bowel ischemia.

  3. Impact of time-resolved MRA on diagnostic accuracy in patients with symptomatic peripheral artery disease of the calf station.

    PubMed

    Hansmann, Jan; Michaely, Henrik J; Morelli, John N; Diehl, Steffen J; Meyer, Mathias; Schoenberg, Stefan O; Attenberger, Ulrike I

    2013-12-01

    The purpose of this article is to evaluate the added diagnostic accuracy of time-resolved MR angiography (MRA) of the calves compared with continuous-table-movement MRA in patients with symptomatic lower extremity peripheral artery disease (PAD) using digital subtraction angiography (DSA) correlation. Eighty-four consecutive patients with symptomatic PAD underwent a low-dose 3-T MRA protocol, consisting of continuous-table-movement MRA, acquired from the diaphragm to the calves, and an additional time-resolved MRA of the calves; 0.1 mmol/kg body weight (bw) of contrast material was used (0.07 mmol/kg bw for continuous-table-movement MRA and 0.03 mmol/kg bw for time-resolved MRA). Two radiologists rated image quality on a 4-point scale and stenosis degree on a 3-point scale. An additional assessment determined the degree of venous contamination and whether time-resolved MRA improved diagnostic confidence. The accuracy of stenosis gradation with continuous-table-movement and time-resolved MRA was compared with that of DSA as a correlation. Overall diagnostic accuracy was calculated for continuous-table-movement and time-resolved MRA. Median image quality was rated as good for 578 vessel segments with continuous-table-movement MRA and as excellent for 565 vessel segments with time-resolved MRA. Interreader agreement was excellent (κ = 0.80-0.84). Venous contamination interfered with diagnosis in more than 60% of continuous-table-movement MRA examinations. The degree of stenosis was assessed for 340 vessel segments. The diagnostic accuracies (continuous-table-movement MRA/time-resolved MRA) combined for the readers were obtained for the tibioperoneal trunk (84%/93%), anterior tibial (69%/87%), posterior tibial (85%/91%), and peroneal (67%/81%) arteries. The addition of time-resolved MRA improved diagnostic confidence in 69% of examinations. The addition of time-resolved MRA at the calf station improves diagnostic accuracy over continuous-table-movement MRA alone in

  4. Ferumoxytol MRA for transcatheter aortic valve replacement planning with renal insufficiency.

    PubMed

    Kallianos, Kimberly; Henry, Travis S; Yeghiazarians, Yerem; Zimmet, Jeffrey; Shunk, Kendrick A; Tseng, Elaine E; Mahadevan, Vaikom; Hope, Michael D

    2017-03-15

    Computed tomography angiography (CTA) is the test of choice for pre-procedure imaging of transcatheter aortic valve replacement (TAVR) candidates. The iodinated contrast required, however, increases the risk of renal dysfunction in patients with pre-existing renal failure. Ferumoxytol is a magnetic resonance imaging (MRI) contrast agent that can be used with renal failure. Its long vascular resonance time allows gated MRA sequences that approach CTA in image quality. We present respiratory and cardiac gated MRA enabled by ferumoxytol that can be post-processed in an analogous fashion to CTA. Seven patients with renal failure presenting for TAVR were imaged with respiratory and cardiac gated MRA at 3T using ferumoxtyol for contrast. Aortic annulus, root and peripheral access dimensions were calculated in a fashion identical to that used for CTA. Of these, 6 patients underwent a TAVR procedure and 5 had intraoperative valve assessment with transesophageal echocardiograph (TEE) using standard clinical protocols that employed both two- and three-dimensional techniques. Good correlation between MRA aortic annulus measurements and those from TEE were shown in 5 patients with mean annulus area of 392.4mm 2 (290-470 range) versus 374.1mm 2 (285-440 range), with a pairwise correlation coefficient of 0.92, p=0.029. All patients received Sapien valve implants (one 20mm, three 23mm, and two 26mm valves). Access decisions were guided by MRA with no complications. Annulus sizing resulted in no greater than trace/mild aortic regurgitation in all patients. Ferumoxytol MRA is a safe alternative to CTA in patients with renal failure for pre-TAVR analysis of the aortic root and peripheral access. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  5. ECG-gated imaging of the left atrium and pulmonary veins: Intra-individual comparison of CTA and MRA.

    PubMed

    Fahlenkamp, U L; Lembcke, A; Roesler, R; Schwenke, C; Huppertz, A; Streitparth, F; Taupitz, M; Hamm, B; Wagner, M

    2013-10-01

    To compare electrocardiography (ECG)-gated computed tomography angiography (CTA) with ECG-gated magnetic resonance angiography (MRA) for assessment of the left atrium (LA) and pulmonary veins (PVs). Twenty-nine consecutive patients who underwent both cardiac CTA and MRA were evaluated. Contrast-enhanced CTA was performed with prospective ECG-gating using a 320 detector row CT system. Contrast-enhanced MRA was performed with prospective ECG-gating using a 1.5 T MRI system equipped with a 32 channel cardiac coil. MRA was acquired during free-breathing with a navigator-gated inversion-recovery prepared steady-state free precession sequence. Two readers independently assessed the CTA and MRA images for vascular definition of the PVs (from 0, not visualized, to 4, excellent definition) and ostial PV diameters. Variants of LA anatomy were assessed in consensus. CTA was successfully performed in all patients with a mean radiation exposure of 5.1 ± 2.2 mSv. MRA was successfully performed in 27 of 29 patients (93 %). Visual definition of PVs was rated significantly higher on CTA compared to MRA (p < 0.0001; reader 1: excellent/good ratings of CTA versus MRA: 100% versus 86%; reader 2: excellent/good ratings of CTA versus MRA: 99% versus 89%). Assessment of ostial PV diameters showed good correlation between CTA and MRA (reader 1: Pearson r = 0.91; reader 2: Pearson r = 0.82). Moreover, agreement between both imaging methods for evaluation of variants of LA anatomy was high (agreement rate of 95% (95% CI: 92-99%). ECG-gated CTA provides higher image quality compared to ECG-gated MRA. Nevertheless, both CTA and MRA provided similar information of LA anatomy and ostial PV diameters. Copyright © 2013 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

  6. Contrast-enhanced time-resolved MRA for follow-up of intracranial aneurysms treated with the pipeline embolization device.

    PubMed

    Boddu, S R; Tong, F C; Dehkharghani, S; Dion, J E; Saindane, A M

    2014-01-01

    Endovascular reconstruction and flow diversion by using the Pipeline Embolization Device is an effective treatment for complex cerebral aneurysms. Accurate noninvasive alternatives to DSA for follow-up after Pipeline Embolization Device treatment are desirable. This study evaluated the accuracy of contrast-enhanced time-resolved MRA for this purpose, hypothesizing that contrast-enhanced time-resolved MRA will be comparable with DSA and superior to 3D-TOF MRA. During a 24-month period, 37 Pipeline Embolization Device-treated intracranial aneurysms in 26 patients underwent initial follow-up by using 3D-TOF MRA, contrast-enhanced time-resolved MRA, and DSA. MRA was performed on a 1.5T unit by using 3D-TOF and time-resolved imaging of contrast kinetics. All patients underwent DSA a median of 0 days (range, 0-68) after MRA. Studies were evaluated for aneurysm occlusion, quality of visualization of the reconstructed artery, and measurable luminal diameter of the Pipeline Embolization Device, with DSA used as the reference standard. The sensitivity, specificity, and positive and negative predictive values of contrast-enhanced time-resolved MRA relative to DSA for posttreatment aneurysm occlusion were 96%, 85%, 92%, and 92%. Contrast-enhanced time-resolved MRA demonstrated superior quality of visualization (P = .0001) and a higher measurable luminal diameter (P = .0001) of the reconstructed artery compared with 3D-TOF MRA but no significant difference compared with DSA. Contrast-enhanced time-resolved MRA underestimated the luminal diameter of the reconstructed artery by 0.965 ± 0.497 mm (27% ± 13%) relative to DSA. Contrast-enhanced time-resolved MRA is a reliable noninvasive method for monitoring intracranial aneurysms following flow diversion and vessel reconstruction by using the Pipeline Embolization Device. © 2014 by American Journal of Neuroradiology.

  7. Comparison of 7.0- and 3.0-T MRI and MRA in ischemic-type moyamoya disease: preliminary experience.

    PubMed

    Deng, Xiaofeng; Zhang, Zihao; Zhang, Yan; Zhang, Dong; Wang, Rong; Ye, Xun; Xu, Long; Wang, Bo; Wang, Kai; Zhao, Jizong

    2016-06-01

    OBJECT The authors compared the image quality and diagnostic sensitivity and specificity of 7.0-T and 3.0-T MRI and time-of-flight (TOF) MR angiography (MRA) in patients with moyamoya disease (MMD). METHODS MR images of 15 patients with ischemic-type MMD (8 males, 7 females; age 13-48 years) and 13 healthy controls (7 males, 6 females; age 19-28 years) who underwent both 7.0-T and 3.0-T MRI and MRA were studied retrospectively. The main intracranial arteries were assessed by using the modified Houkin's grading system (MRA score). Moyamoya vessels (MMVs) were evaluated by 2 grading systems: the MMV quality score and the MMV area score. Two diagnostic criteria for MMD were used: the T2 criteria, which used flow voids in the basal ganglion on T2-weighted images, and the TOF criteria, which used the high-intensity areas in the basal ganglion on source images from TOF MRA. All data were evaluated by 2 independent readers who were blinded to the strength field and presence or absence of MMD. Using conventional angiography as the gold standard, the sensitivity and specificity of 7.0-T and 3.0-T MRI/MRA in the diagnosis of MMD were calculated. The differences between 7.0-T and 3.0-T MRI and MRA were statistically compared. RESULTS No significant differences were observed between 7.0-T and 3.0-T MRA in MRA score (p = 0.317) or MRA grade (p = 0.317). There was a strong correlation between the Suzuki's stage and MRA grade in both 3.0-T (rs = 0.930; p < 0.001) and 7.0-T (rs = 0.966; p < 0.001) MRA. However, MMVs were visualized significantly better on 7.0-T than on 3.0-T MRA, suggested by both the MMV quality score (p = 0.001) and the MMV area score (p = 0.001). The correlation between the Suzuki's stage and the MMV area score was moderate in 3.0-T MRA (rs = 0.738; p = 0.002) and strong in 7.0-T MRA (rs = 0.908; p < 0.001). Moreover, 7.0-T MR images showed a greater capacity for detecting flow voids in the basal ganglion on both T2-weighted MR images (p < 0.001) and TOF source

  8. Contrast-enhanced time-resolved MRA for pre-angiographic evaluation of suspected spinal dural arterial venous fistulas.

    PubMed

    Saindane, Amit M; Boddu, Srikanth R; Tong, Frank C; Dehkharghani, Seena; Dion, Jacques E

    2015-02-01

    Spinal digital subtraction angiography (DSA) is the gold standard for diagnosis of spinal dural arterial venous fistulas (SDAVFs), but can require extensive time, radiation exposure and contrast dose. We hypothesize that contrast-enhanced time-resolved MR angiography (CE-TR MRA) will have utility for the non-invasive diagnosis and pre-angiographic localization of SDAVFs. Eighteen patients underwent both CE-TR MRA and DSA for suspected SDAVFs, with DSA performed a median of 11 days (range 0-41) after MRA. CE-TR MRA was performed on a 1.5 T GE unit using Time Resolved Imaging of Contrast Kinetics (TRICKS). CE-TR MRA and DSA images were evaluated for the presence of SDAVFs and location of the feeding arterial supply, with DSA as the reference standard. DSA was also evaluated for the number of vessels catheterized, contrast volume and fluoroscopic and procedure times. Eight of the 18 patients were positive for SDAVF on DSA. Sensitivity, specificity, positive predictive value and negative predictive value for the 18 CE-TR MRAs were 88%, 90%, 88% and 90%, respectively. Localization of the SDAVF arterial supply on CE-TR MRA was within one vertebral level from DSA for 6/7 SDAVFs. Compared with patients with a SDAVF and feeding artery identified on CE-TR MRA, patients with negative or suboptimal CE-TR MRA had a significantly increased number of vessels catheterized (p=0.027) and larger contrast volumes (p=0.022). CE-TR MRA is a useful initial examination for the diagnosis and localization of SDAVFs, with a high concordance rate with DSA. When CE-TR MRA demonstrates a SDAVF, the number of catheterized vessels and contrast dose can be decreased during DSA. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  9. Your Radiologist Explains Magnetic Resonance Angiography (MRA)

    MedlinePlus Videos and Cool Tools

    ... mild sedative prior to the examination. For more information about Magnetic Resonance Angiography of MRA or any ... Inc. (RSNA). To help ensure current and accurate information, we do not permit copying but encourage linking ...

  10. 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

  11. Non-ECG-gated unenhanced MRA of the carotids: optimization and clinical feasibility.

    PubMed

    Raoult, H; Gauvrit, J Y; Schmitt, P; Le Couls, V; Bannier, E

    2013-11-01

    To optimise and assess the clinical feasibility of a carotid non-ECG-gated unenhanced MRA sequence. Sixteen healthy volunteers and 11 patients presenting with internal carotid artery (ICA) disease underwent large field-of-view balanced steady-state free precession (bSSFP) unenhanced MRA at 3T. Sampling schemes acquiring the k-space centre either early (kCE) or late (kCL) in the acquisition window were evaluated. Signal and image quality was scored in comparison to ECG-gated kCE unenhanced MRA and TOF. For patients, computed tomography angiography was used as the reference. In volunteers, kCE sampling yielded higher image quality than kCL and TOF, with fewer flow artefacts and improved signal homogeneity. kCE unenhanced MRA image quality was higher without ECG-gating. Arterial signal and artery/vein contrast were higher with both bSSFP sampling schemes than with TOF. The kCE sequence allowed correct quantification of ten significant stenoses, and it facilitated the identification of an infrapetrous dysplasia, which was outside of the TOF imaging coverage. Non-ECG-gated bSSFP carotid imaging offers high-quality images and is a promising sequence for carotid disease diagnosis in a short acquisition time with high spatial resolution and a large field of view. • Non-ECG-gated unenhanced bSSFP MRA offers high-quality imaging of the carotid arteries. • Sequences using early acquisition of the k-space centre achieve higher image quality. • Non-ECG-gated unenhanced bSSFP MRA allows quantification of significant carotid stenosis. • Short MR acquisition times and ungated sequences are helpful in clinical practice. • High 3D spatial resolution and a large field of view improve diagnostic performance.

  12. Concordance of Time-of-Flight MRA and Digital Subtraction Angiography in Adult Primary Central Nervous System Vasculitis.

    PubMed

    de Boysson, H; Boulouis, G; Parienti, J-J; Touzé, E; Zuber, M; Arquizan, C; Dequatre, N; Detante, O; Bienvenu, B; Aouba, A; Guillevin, L; Pagnoux, C; Naggara, O

    2017-10-01

    3D-TOF-MRA and DSA are 2 available tools to demonstrate neurovascular involvement in primary central nervous system vasculitis. We aimed to compare the diagnostic concordance of vessel imaging using 3D-TOF-MRA and DSA in patients with primary central nervous system vasculitis. We retrospectively identified all patients included in the French primary central nervous system vasculitis cohort of 85 patients who underwent, at baseline, both intracranial 3D-TOF-MRA and DSA in an interval of no more than 2 weeks and before treatment initiation. Two neuroradiologists independently reviewed all 3D-TOF-MRA and DSA imaging. Brain vasculature was divided into 25 arterial segments. Concordance between 3D-TOF-MRA and DSA for the identification of arterial stenosis was assessed by the Cohen κ Index. Thirty-one patients met the inclusion criteria, including 20 imaged with a 1.5T MR unit and 11 with a 3T MR unit. Among the 25 patients (81%) with abnormal DSA findings, 24 demonstrated abnormal 3D-TOF-MRA findings, whereas all 6 remaining patients with normal DSA findings had normal 3D-TOF-MRA findings. In the per-segment analysis, concordance between 1.5T 3D-TOF-MRA and DSA was 0.82 (95% CI, 0.75-0.93), and between 3T 3D-TOF-MRA and DSA, it was 0.87 (95% CI, 0.78-0.91). 3D-TOF-MRA shows a high concordance with DSA in diagnostic performance when analyzing brain vasculature in patients with primary central nervous system vasculitis. In patients with negative 3T 3D-TOF-MRA findings, the added diagnostic value of DSA is limited. © 2017 by American Journal of Neuroradiology.

  13. Diagnosis of glenoid labral tears using 3-tesla MRI vs. 3-tesla MRA: a systematic review and meta-analysis.

    PubMed

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

    2018-05-01

    Various protocols exist for magnetic resonance arthrogram (MRA) of the shoulder, including 3D isotropic scanning and positioning in neutral (2D neutral MRA), or abduction-external-rotation (ABER). MRA does not improve diagnostic accuracy for labral tears when compared to magnetic resonance imaging (MRI) performed using 3-Tesla (3T) magnets. Systematic review of the Cochrane, MEDLINE, and PubMed databases according to PRISMA guidelines. Included studies compared 3T MRI or 3T MRA (index tests) to arthroscopic findings (reference test). Methodological appraisal performed using QUADAS-2. Pooled sensitivity and specificity were calculated. Ten studies including 929 patients were included. Index test bias and applicability were a concern in the majority of studies. The use of arthroscopy as the reference test raised concern of verification bias in all studies. For anterior labral lesions, 3T MRI was less sensitive (0.83 vs. 0.87 p = 0.083) than 3T 2D neutral MRA. Compared to 3T 2D neutral MRA, both 3T 3D Isotropic MRA and 3T ABER MRA significantly improved sensitivity (0.87 vs. 0.95 vs. 0.94). For SLAP lesions, 3T 2D neutral MRA was of similar sensitivity to 3T MRI (0.84 vs. 0.83, p = 0.575), but less specific (0.99 vs. 0.92 p < 0.0001). For posterior labral lesions, 3T 2D neutral MRA had greater sensitivity than 3T 3D Isotropic MRA and 3T MRI (0.90 vs. 0.83 vs. 0.83). At 3-T, MRA improved sensitivity for diagnosis of anterior and posterior labral lesions, but reduced specificity in diagnosis of SLAP tears. 3T MRA with ABER positioning further improved sensitivity in diagnosis of anterior labral tears. IV.

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

    PubMed

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

    2015-08-01

    The aim of this meta-analysis was to evaluate the diagnostic value of 3D time-of-flight magnetic resonance angiography (3D-TOF-MRA) in trigeminal neuralgia (TN). Relevant studies were identified by computerized database searches supplemented by manual search strategies. The studies were included in accordance with stringent inclusion and exclusion criteria. Following a multistep screening process, high quality studies related to the diagnostic value of 3D-TOF-MRA in TN were selected for meta-analysis. Statistical analyses were conducted using Statistical Analysis Software (version 8.2; SAS Institute, Cary, NC, USA) and Meta Disc (version 1.4; Unit of Clinical Biostatistics, Ramon y Cajal Hospital, Madrid, Spain). For the present meta-analysis, we initially retrieved 95 studies from database searches. A total of 13 studies were eventually enrolled containing a combined total of 1084 TN patients. The meta-analysis results demonstrated that the sensitivity and specificity of the diagnostic value of 3D-TOF-MRA in TN were 95% (95% confidence interval [CI] 0.93-0.96) and 77% (95% CI 0.66-0.86), respectively. The pooled positive likelihood ratio and negative likelihood ratio were 2.72 (95% CI 1.81-4.09) and 0.08 (95% CI 0.06-0.12), respectively. The pooled diagnostic odds ratio of 3D-TOF-MRA in TN was 52.92 (95% CI 26.39-106.11), and the corresponding area under the curve in the summary receiver operating characteristic curve based on the 3D-TOF-MRA diagnostic image of observers was 0.9695 (standard error 0.0165). Our results suggest that 3D-TOF-MRA has excellent sensitivity and specificity as a diagnostic tool for TN, and that it can accurately identify neurovascular compression in TN patients. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Validation of a standardized mapping system of the hip joint for radial MRA sequencing.

    PubMed

    Klenke, Frank M; Hoffmann, Daniel B; Cross, Brian J; Siebenrock, Klaus A

    2015-03-01

    Intraarticular gadolinium-enhanced magnetic resonance arthrography (MRA) is commonly applied to characterize morphological disorders of the hip. However, the reproducibility of retrieving anatomic landmarks on MRA scans and their correlation with intraarticular pathologies is unknown. A precise mapping system for the exact localization of hip pathomorphologies with radial MRA sequences is lacking. Therefore, the purpose of the study was the establishment and validation of a reproducible mapping system for radial sequences of hip MRA. Sixty-nine consecutive intraarticular gadolinium-enhanced hip MRAs were evaluated. Radial sequencing consisted of 14 cuts orientated along the axis of the femoral neck. Three orthopedic surgeons read the radial sequences independently. Each MRI was read twice with a minimum interval of 7 days from the first reading. The intra- and inter-observer reliability of the mapping procedure was determined. A clockwise system for hip MRA was established. The teardrop figure served to determine the 6 o'clock position of the acetabulum; the center of the greater trochanter served to determine the 12 o'clock position of the femoral head-neck junction. The intra- and inter-observer ICCs to retrieve the correct 6/12 o'clock positions were 0.906-0.996 and 0.978-0.988, respectively. The established mapping system for radial sequences of hip joint MRA is reproducible and easy to perform.

  16. 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.

  17. 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.

  18. 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

    ... FERS MRA+10 provision? 875.203 Section 875.203 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT....203 Am I eligible if I separated under the FERS MRA+10 provision? If you have separated from service under the FERS Minimum Retirement Age and 10 years of service (MRA+10) provision of 5 U.S.C. 8412(g...

  19. 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

    ... FERS MRA+10 provision? 875.203 Section 875.203 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT....203 Am I eligible if I separated under the FERS MRA+10 provision? If you have separated from service under the FERS Minimum Retirement Age and 10 years of service (MRA+10) provision of 5 U.S.C. 8412(g...

  20. 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

    ... FERS MRA+10 provision? 875.203 Section 875.203 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT....203 Am I eligible if I separated under the FERS MRA+10 provision? If you have separated from service under the FERS Minimum Retirement Age and 10 years of service (MRA+10) provision of 5 U.S.C. 8412(g...

  1. 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

    ... FERS MRA+10 provision? 875.203 Section 875.203 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT....203 Am I eligible if I separated under the FERS MRA+10 provision? If you have separated from service under the FERS Minimum Retirement Age and 10 years of service (MRA+10) provision of 5 U.S.C. 8412(g...

  2. 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

    ... FERS MRA+10 provision? 875.203 Section 875.203 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT....203 Am I eligible if I separated under the FERS MRA+10 provision? If you have separated from service under the FERS Minimum Retirement Age and 10 years of service (MRA+10) provision of 5 U.S.C. 8412(g...

  3. Improvement of the diagnostic accuracy of MRA with subtraction technique in cerebral vasospasm.

    PubMed

    Hamaguchi, Akiyoshi; Fujima, Noriyuki; Yoshida, Daisuke; Hamaguchi, Naoko; Kodera, Shuichi

    2014-01-01

    Vasospasm has been considered the most severe acute complication after subarachnoid hemorrhage (SAH). MRA is not considered ideal for detecting cerebral vasospasm because of background including the hemorrhage. The aim of this study is to evaluate the efficacy of Subtraction MRA (SMRA) by comparing it to that of conventional MRA (CMRA) for diagnosis of cerebral vasospasm. Arteries were assigned to one of three categories based on the degree of MRA diagnostic quality of vasospasm (quality score): 0, bad … 2, good. Furthermore each artery was assigned to one of four categories based on the degree of vasospasm severity (SV score): 0, no vasospasm … 3, severe. The value of the difference between DSA-SV score and MRA-SV score was defined as the DIF score. CMRA and SMRA were compared for each arterial region with regard to quality score and DIF score. The average CMRA and SMRA quality score were 1.46 and 1.79; the difference was statistically significant. The average CMRA and SMRA DIF score were 1.08 and .60; the difference was statistically significant. Diagnosis of cerebral vasospasm is more accurate by SMRA than by CMRA. The advantages are its noninvasive nature and its ability to detect cerebral vasospasm. Copyright © 2014 by the American Society of Neuroimaging.

  4. 7Tesla MRA for the differentiation between intracranial aneurysms and infundibula.

    PubMed

    Wermer, Marieke J H; van Walderveen, Marianne A A; Garpebring, Anders; van Osch, Matthias J P; Versluis, Maarten J

    2017-04-01

    The differentiation between an aneurysm and an infundibulum with time-of-flight MRA is often difficult. However, this distinction is important because it affects further patient follow-up. The purpose of this study was to assess the added value of high resolution 7Tesla MRA for investigating small vascular lesions suspect for an aneurysm or an infundibulum. We included patients in whom an intracranial vascular lesion was detected in our University Hospital and in whom the discrimination between a true aneurysms or an infundibulum could not be made on conventional 1.5 or 3T MRI were included in the study. All patients underwent an additional 7T time-of-flight MRA at higher spatial resolution. We included 6 patients. The age range of the patients was 35-65years and 5 of them were women. 1 out of 6 had a 1.5T MRI, the other 5 patients had a 3T MRI previous to the 7T MRI. The lesion size varied between 0.9mm and 2.0mm. In 5 of the 6 patients the presence of an infundibulum could be proven using the high resolution of the 7T MRA. All patients tolerated the 7T MRI well. Our results suggest that high resolution and contrast of 7T MRA provides added diagnostic value in discriminating between intracranial aneurysms and infundibula. This finding may have important consequences for patient follow-up and comfort because it might reduce unnecessary follow-up exams and decrease uncertainty about the diagnosis. Larger studies, however, are needed to confirm our findings. Copyright © 2016. Published by Elsevier Inc.

  5. Contrast-enhanced pulmonary MRA for the primary diagnosis of pulmonary embolism: current state of the art and future directions.

    PubMed

    Benson, Donald G; Schiebler, Mark L; Repplinger, Michael D; François, Christopher J; Grist, Thomas M; Reeder, Scott B; Nagle, Scott K

    2017-06-01

    CT pulmonary angiography (CTPA) is currently considered the imaging standard of care for the diagnosis of pulmonary embolism (PE). Recent advances in contrast-enhanced pulmonary MR angiography (MRA) techniques have led to increased use of this modality for the detection of PE in the proper clinical setting. This review is intended to provide an introduction to the state-of-the-art techniques used in pulmonary MRA for the detection of PE and to discuss possible future directions for this modality. This review discusses the following issues pertinent to MRA for the diagnosis of PE: (1) the diagnostic efficacy and clinical effectiveness for pulmonary MRA relative to CTPA, (2) the different pulmonary MRA techniques used for the detection of PE, (3) guidance for building a clinical service at their institution using MRA and (4) future directions of PE MRA. Our principal aim was to show how pulmonary MRA can be used as a safe, effective modality for the diagnosis of clinically significant PE, particularly for those patients where there are concerns about ionizing radiation or contraindications/allergies to the iodinated contrast material.

  6. Contrast-enhanced pulmonary MRA for the primary diagnosis of pulmonary embolism: current state of the art and future directions

    PubMed Central

    Schiebler, Mark L; Repplinger, Michael D; François, Christopher J; Grist, Thomas M; Reeder, Scott B

    2017-01-01

    CT pulmonary angiography (CTPA) is currently considered the imaging standard of care for the diagnosis of pulmonary embolism (PE). Recent advances in contrast-enhanced pulmonary MR angiography (MRA) techniques have led to increased use of this modality for the detection of PE in the proper clinical setting. This review is intended to provide an introduction to the state-of-the-art techniques used in pulmonary MRA for the detection of PE and to discuss possible future directions for this modality. This review discusses the following issues pertinent to MRA for the diagnosis of PE: (1) the diagnostic efficacy and clinical effectiveness for pulmonary MRA relative to CTPA, (2) the different pulmonary MRA techniques used for the detection of PE, (3) guidance for building a clinical service at their institution using MRA and (4) future directions of PE MRA. Our principal aim was to show how pulmonary MRA can be used as a safe, effective modality for the diagnosis of clinically significant PE, particularly for those patients where there are concerns about ionizing radiation or contraindications/allergies to the iodinated contrast material. PMID:28306332

  7. The impact of injector-based contrast agent administration in time-resolved MRA.

    PubMed

    Budjan, Johannes; Attenberger, Ulrike I; Schoenberg, Stefan O; Pietsch, Hubertus; Jost, Gregor

    2018-05-01

    Time-resolved contrast-enhanced MR angiography (4D-MRA), which allows the simultaneous visualization of the vasculature and blood-flow dynamics, is widely used in clinical routine. In this study, the impact of two different contrast agent injection methods on 4D-MRA was examined in a controlled, standardized setting in an animal model. Six anesthetized Goettingen minipigs underwent two identical 4D-MRA examinations at 1.5 T in a single session. The contrast agent (0.1 mmol/kg body weight gadobutrol, followed by 20 ml saline) was injected using either manual injection or an automated injection system. A quantitative comparison of vascular signal enhancement and quantitative renal perfusion analyses were performed. Analysis of signal enhancement revealed higher peak enhancements and shorter time to peak intervals for the automated injection. Significantly different bolus shapes were found: automated injection resulted in a compact first-pass bolus shape clearly separated from the recirculation while manual injection resulted in a disrupted first-pass bolus with two peaks. In the quantitative perfusion analyses, statistically significant differences in plasma flow values were found between the injection methods. The results of both qualitative and quantitative 4D-MRA depend on the contrast agent injection method, with automated injection providing more defined bolus shapes and more standardized examination protocols. • Automated and manual contrast agent injection result in different bolus shapes in 4D-MRA. • Manual injection results in an undefined and interrupted bolus with two peaks. • Automated injection provides more defined bolus shapes. • Automated injection can lead to more standardized examination protocols.

  8. 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.

  9. 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

  10. Selection and evaluation of optimal two-dimensional CAIPIRINHA kernels applied to time-resolved three-dimensional CE-MRA.

    PubMed

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

    2015-06-01

    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. 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). 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. 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. © 2014 Wiley Periodicals, Inc.

  11. Noncontrast MRA of pedal arteries in type II diabetes: effect of disease load on vessel visibility.

    PubMed

    Zhang, Lijuan; Liu, Xin; Fan, Zhaoyang; Zhang, Na; Chung, Yiu-Cho; Liao, Weiqi; Zheng, Hairong; Li, Debiao

    2015-04-01

    Noncontrast magnetic resonance angiography (NC-MRA) of pedal artery remains challenging because of the global and regional disease load, tissue integrity, and altered microcirculation. This study aims to investigate the feasibility of the NC-MRA of pedal arteries with flow-sensitive dephasing-prepared steady-state free precession (FSD-SSFP) and to explore the effect of disease load of type II diabetes on the vessel depiction. FSD-SSFP was performed on a 1.5-T magnetic resonance system before the contrast-enhanced MRA (CE-MRA) as a reference standard in 39 consecutive diabetic subjects (29 men and 16 women, aged 57.9 ± 11.4 years). Two experienced radiologists evaluated the overall artery visibility (VA) and the contamination from soft tissue (SC) and veins (VC) with a four-point scale. Chronic complications and measures including random blood glucose (RBG), lipid panel, body mass index, risk of diabetic foot ulcers (RDF), and glycated hemoglobin (HbA1c) by the imaging were recorded as disease load indicators. Spearman rank correlation and ordinal regression were performed to investigate the effect of disease load on the depiction of pedal arteries. The measurement of RBG and RDF were significantly correlated with the VC in CE-MRA and with the overall visibility of pedal arteries in NC-MRA (P < .025 and P < .001, respectively). Blood pressure was the only parameter that was significantly associated with SC in NC-MRA with FSD-SSFP (P < .025). For CE-MRA the effect of RDF on the overall VA manifested a significant linear trend (P < .001), and the level of RBG was substantially associated with the VC (P < .025) without significantly impacting VA and SC. Hypertension only correlated with SC in NC-MRA. VA was found independent of the presence of diabetic nephropathy, coronary artery disease, abnormal lipid panel, HbA1c (75.0%), or optimized m1 value that ranged from 70 to 160 mT⋅ms(2)/m (mean, 125 ± 18 mT⋅ms(2)/m) in this study. FSD-SSFP proved to be a useful

  12. 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.

  13. Time-resolved imaging of contrast kinetics does not improve performance of follow-up MRA of embolized intracranial aneurysms.

    PubMed

    Serafin, Zbigniew; Strześniewski, Piotr; Lasek, Władysław; Beuth, Wojciech

    2012-07-01

    The use of contrast media and the time-resolved imaging of contrast kinetics (TRICKS) technique have some theoretical advantages over time-of-flight magnetic resonance angiography (TOF-MRA) in the follow-up of intracranial aneurysms after endovascular treatment. We prospectively compared the diagnostic performance of TRICKS and TOF-MRA with digital subtracted angiography (DSA) in the assessment of occlusion of embolized aneurysms. Seventy-two consecutive patients with 72 aneurysms were examined 3 months after embolization. Test characteristics of TOF-MRA and TRICKS were calculated for the detection of residual flow. The results of quantification of flow were compared with weighted kappa. Intraobserver and interobserver reproducibility was determined. The sensitivity of TOF-MRA was 85% (95% CI, 65-96%) and of TRICKS, 89% (95% CI, 70-97%). The specificity of both methods was 91% (95% CI, 79-98%). The accuracy of the flow quantification ranged from 0.76 (TOF-MRA) to 0.83 (TRICKS). There was no significant difference between the methods in the area under the ROC curve regarding both the detection and the quantification of flow. Intraobserver reproducibility was very good with both techniques (kappa, 0.86-0.89). The interobserver reproducibility was moderate for TOF-MRA and very good for TRICKS (kappa, 0.74-0.80). In this study, TOF-MRA and TRICKS presented similar diagnostic performance; therefore, the use of time-resolved contrast-enhanced MRA is not justified in the follow-up of embolized aneurysms.

  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. Clinical outcomes after magnetic resonance angiography (MRA) versus computed tomographic angiography (CTA) for pulmonary embolism evaluation.

    PubMed

    Repplinger, Michael D; Nagle, Scott K; Harringa, John B; Broman, Aimee T; Lindholm, Christopher R; François, Christopher J; Grist, Thomas M; Reeder, Scott B; Schiebler, Mark L

    2018-05-10

    To compare patient outcomes following magnetic resonance angiography (MRA) versus computed tomographic angiography (CTA) ordered for suspected pulmonary embolism (PE). In this IRB-approved, single-center, retrospective, case-control study, we reviewed the medical records of all patients evaluated for PE with MRA during a 5-year period along with age- and sex-matched controls evaluated with CTA. Only the first instance of PE evaluation during the study period was included. After application of our exclusion criteria to both study arms, the analysis included 1173 subjects. The primary endpoint was major adverse PE-related event (MAPE), which we defined as major bleeding, venous thromboembolism, or death during the 6 months following the index imaging test (MRA or CTA), obtained through medical record review. Logistic regression, chi-square test for independence, and Fisher's exact test were used with a p < 0.05 threshold. The overall 6-month MAPE rate following MRA (5.4%) was lower than following CTA (13.6%, p < 0.01). Amongst outpatients, the MAPE rate was lower for MRA (3.7%) than for CTA (8.0%, p = 0.01). Accounting for age, sex, referral source, BMI, and Wells' score, patients were less likely to suffer MAPE than those who underwent CTA, with an odds ratio of 0.44 [0.24, 0.80]. Technical success rate did not differ significantly between MRA (92.6%) and CTA (90.5%) groups (p = 0.41). Within the inherent limitations of a retrospective case-controlled analysis, we observed that the rate of MAPE was lower (more favorable) for patients following pulmonary MRA for the primary evaluation of suspected PE than following CTA.

  16. 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.

  17. Single-Breath-Hold Whole-heart Unenhanced Coronary MRA Using Multi-shot Gradient Echo EPI at 3T: Comparison with Free-breathing Turbo-field-echo Coronary MRA on Healthy Volunteers.

    PubMed

    Iyama, Yuji; Nakaura, Takeshi; Nagayama, Yasunori; Oda, Seitaro; Utsunomiya, Daisuke; Kidoh, Masafumi; Yuki, Hideaki; Hirata, Kenichiro; Namimoto, Tomohiro; Kitajima, Mika; Morita, Kosuke; Funama, Yoshinori; Takemura, Atsushi; Okuaki, Tomoyuki; Yamashita, Yasuyuki

    2018-04-10

    We investigated the feasibility of single breath hold unenhanced coronary MRA using multi-shot gradient echo planar imaging (MSG-EPI) on a 3T-scanner. Fourteen volunteers underwent single breath hold coronary MRA with a MSG-EPI and free-breathing turbo field echo (TFE) coronary MRA at 3T. The acquisition time, signal to noise ratio (SNR), and the contrast of the sequences were compared with the paired t-test. Readers evaluated the image contrast, noise, sharpness, artifacts, and the overall image quality. The acquisition time was 88.1% shorter for MSG-EPI than TFE (24.7 ± 2.5 vs 206.4 ± 23.1 sec, P < 0.01). The SNR was significantly higher on MSG-EPI than TFE scans (P < 0.01). There was no significant difference in the contrast on MSG-EPI and TFE scans (1.8 ± 0.3 vs 1.9 ± 0.3, P = 0.24). There was no significant difference in image contrast, image sharpness, and overall image quality between two scan techniques. The score of image noise and artifact were significantly higher on MSG-EPI than TFE scans (P < 0.05). The single breath hold MSG-EPI sequence is a promising technique for shortening the scan time and for preserving the image quality of unenhanced whole heart coronary MRA on a 3T scanner.

  18. Performance of unenhanced respiratory-gated 3D SSFP MRA to depict hepatic and visceral artery anatomy and variants.

    PubMed

    Puippe, Gilbert D; Alkadhi, Hatem; Hunziker, Roger; Nanz, Daniel; Pfammatter, Thomas; Baumueller, Stephan

    2012-08-01

    To prospectively evaluate the performance of unenhanced respiratory-gated magnetization-prepared 3D-SSFP inversion recovery MRA (unenhanced-MRA) to depict hepatic and visceral artery anatomy and variants in comparison to contrast-enhanced dynamic gradient-echo MRI (CE-MRI) and to digital subtraction angiography (DSA). Eighty-four patients (55.6±12.4 years) were imaged with CE-MRI (TR/TE 3.5/1.7ms, TI 1.7ms, flip-angle 15°) and unenhanced-MRA (TR/TE 4.4/2.2ms, TI 200ms, flip-angle 90°). Two independent readers assessed image quality of hepatic and visceral arteries on a 4-point-scale. Vessel contrast was measured by a third reader. In 28 patients arterial anatomy was compared to DSA. Interobserver agreement regarding image quality was good for CE-MRI (κ=0.77) and excellent for unenhanced-MRA (κ=0.83). Unenhanced-MRA yielded diagnostic image quality in 71.6% of all vessels, whereas CE-MRI provided diagnostic image quality in 90.6% (p<0.001). Vessel-based image quality was significantly superior for all vessels at CE-MRI compared to unenhanced-MRA (p<0.01). Vessel contrast was similar among both sequences (p=0.15). Compared to DSA, CE-MRI and unenhanced-MRA yielded equal accuracy of 92.9-96.4% for depiction of hepatic and visceral artery variants (p=0.93). Unenhanced-MRA provides diagnostic image quality in 72% of hepatic and visceral arteries with no significant difference in vessel contrast and similar accuracy to CE-MRI for depiction of hepatic and visceral anatomy. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  19. Is there a role for free breathing non-contrast steady-state free precession renal MRA imaging for assessing live donors? A preliminary study.

    PubMed

    Laurence, I; Ariff, B; Quest, R A; Moser, S; Glover, A; Taube, D; Gishen, P; Papalois, V; Juli, C

    2012-08-01

    Accurate pre-operative evaluation of renal vascular anatomy is essential for successful renal harvest in live donor transplantation. Non-contrast renal MR angiographic (MRA) techniques are potentially well suited to the screening of donors; however, their restricted imaging field of view (FOV) has previously been an important limitation. We sought to assess whether the addition of a large FOV balanced fast field echo (BFFE) steady-state free precession (SSFP) sequence to non-contrast SSFP MRA could overcome this problem. Comparison with contrast-enhanced MRA (CE MRA) and findings at surgery were performed. 22 potential renal donors each underwent SSFP and CE MRA. 11 out of 22 potential donors subsequently underwent a donor nephrectomy. All images were diagnostic. Both SSFP MRA and CE MRA identified an equal number of arteries. Surgery confirmed two accessory renal arteries, both demonstrated with both imaging techniques. A third accessory vessel was identified with both techniques on a kidney contralateral to the donated organ. 6 out of 11 procured kidneys demonstrated early branch arteries at surgery, 5 out of 6 of which had been depicted on both SSFP and CE MRA. The median grading of image quality for main renal arteries was slightly better for CE MRA (p=0.048), but for accessory vessels it was better for SSFP MRA. This pilot study indicates that by combining free-breathing SSFP MRA with large-FOV bFFE images, an accurate depiction of renal vascular anatomy without the need for intravenous contrast administration can be obtained, as compared with surgical findings and CE MRA.

  20. Is there a role for free breathing non-contrast steady-state free precession renal MRA imaging for assessing live donors? A preliminary study

    PubMed Central

    Laurence, I; Ariff, B; Quest, R A; Moser, S; Glover, A; Taube, D; Gishen, P; Papalois, V; Juli, C

    2012-01-01

    Objective Accurate pre-operative evaluation of renal vascular anatomy is essential for successful renal harvest in live donor transplantation. Non-contrast renal MR angiographic (MRA) techniques are potentially well suited to the screening of donors; however, their restricted imaging field of view (FOV) has previously been an important limitation. We sought to assess whether the addition of a large FOV balanced fast field echo (BFFE) steady-state free precession (SSFP) sequence to non-contrast SSFP MRA could overcome this problem. Comparison with contrast-enhanced MRA (CE MRA) and findings at surgery were performed. Methods 22 potential renal donors each underwent SSFP and CE MRA. 11 out of 22 potential donors subsequently underwent a donor nephrectomy. Results All images were diagnostic. Both SSFP MRA and CE MRA identified an equal number of arteries. Surgery confirmed two accessory renal arteries, both demonstrated with both imaging techniques. A third accessory vessel was identified with both techniques on a kidney contralateral to the donated organ. 6 out of 11 procured kidneys demonstrated early branch arteries at surgery, 5 out of 6 of which had been depicted on both SSFP and CE MRA. The median grading of image quality for main renal arteries was slightly better for CE MRA (p=0.048), but for accessory vessels it was better for SSFP MRA. Conclusion This pilot study indicates that by combining free-breathing SSFP MRA with large-FOV bFFE images, an accurate depiction of renal vascular anatomy without the need for intravenous contrast administration can be obtained, as compared with surgical findings and CE MRA. PMID:22253354

  1. Non-contrast-enhanced imaging of haemodialysis fistulas using quiescent-interval single-shot (QISS) MRA: a feasibility study.

    PubMed

    Okur, A; Kantarci, M; Karaca, L; Yildiz, S; Sade, R; Pirimoglu, B; Keles, M; Avci, A; Çankaya, E; Schmitt, P

    2016-03-01

    To assess the efficiency of a novel quiescent-interval single-shot (QISS) technique for non-contrast-enhanced magnetic resonance angiography (MRA) of haemodialysis fistulas. QISS MRA and colour Doppler ultrasound (CDU) images were obtained from 22 haemodialysis patients with end-stage renal disease (ESRD). A radiologist with extensive experience in vascular imaging initially assessed the fistulas using CDU. Two observers analysed each QISS MRA data set in terms of image quality, using a five-point scale ranging from 0 (non-diagnostic) to 4 (excellent), and lumen diameters of all segments were measured. One hundred vascular segments were analysed for QISS MRA. Two anastomosis segments were considered non-diagnostic. None of the arterial or venous segments were evaluated as non-diagnostic. The image quality was poorer for the anastomosis level compared to the other segments (p<0.001 for arterial segments, and p<0.05 for venous segments), while no significant difference was determined for other vascular segments. QISS MRA has the potential to provide valuable complementary information to CDU regarding the imaging of haemodialysis fistulas. In addition, QISS non-enhanced MRA represents an alternative for assessment of haemodialysis fistulas, in which the administration of iodinated or gadolinium-based contrast agents is contraindicated. Copyright © 2015 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

  2. Normal flow signal of the pterygoid plexus on 3T MRA in patients without DAVF of the cavernous sinus.

    PubMed

    Watanabe, K; Kakeda, S; Watanabe, R; Ohnari, N; Korogi, Y

    2013-01-01

    Cavernous sinuses and draining dural sinuses or veins are often visualized on 3D TOF MRA images in patients with dural arteriovenous fistulas involving the CS. Flow signals may be seen in the jugular vein and dural sinuses at the skull base on MRA images in healthy participants, however, because of reverse flow. Our purpose was to investigate the prevalence of flow signals in the pterygoid plexus and CS on 3T MRA images in a cohort of participants without DAVFs. Two radiologists evaluated the flow signals of the PP and CS on 3T MRA images obtained from 406 consecutive participants by using a 5-point scale. In addition, the findings on 3T MRA images were compared with those on digital subtraction angiography images in an additional 171 participants who underwent both examinations. The radiologists identified 110 participants (27.1%; 108 left, 10 right, 8 bilateral) with evidence of flow signals in the PP alone (n = 67) or in both the PP and CS (n = 43). Flow signals were significantly more common in the left PP than in the right PP. In 171 patients who underwent both MRA and DSA, the MRA images showed flow signals in the PP with or without CS in 60 patients; no DAVFs were identified on DSA in any of these patients. Flow signals are frequently seen in the left PP on 3T MRA images in healthy participants. This finding may be the result of flow reversal and should not be considered to indicate occult DAVF.

  3. The clinical value of MRA at 3.0 T for the diagnosis and therapeutic planning of patients with subarachnoid haemorrhage.

    PubMed

    Chen, Yuan-Chang; Sun, Zhen-Kui; Li, Ming-Hua; Li, Yong-Dong; Wang, Wu; Tan, Hua-Qiao; Gu, Bin-Xian; Chen, Shi-Wen

    2012-07-01

    To evaluate the clinical value of unenhanced magnetic resonance angiography (MRA) at 3.0 T for the diagnosis and therapeutic planning of patients with subarachnoid haemorrhage (SAH). A total of 165 patients with SAH were referred for three-dimensional time-of-flight MRA (3D-TOF-MRA) before digital subtraction angiography (DSA). For each aneurysm, 3D-TOF-MRA was used to determine whether the aneurysm was suitable for coil placement with or without balloon/stent-assisted coiling, surgical clipping or conservative treatment. Treatment planning with 3D-TOF-MRA was compared with actual treatment decisions or treatment that had been carried out in each aneurysm decided using DSA. The aneurysm-based evaluation yielded accuracy of 96.9%, sensitivity of 97.6%, specificity of 93.1%, positive predictive value (PPV) of 98.8% and negative predictive value (NPV) of 87.1%, in the detection of intracranial aneurysms. Treatment planning could be correctly made on the basis of aneurysm anatomy and working view by volume rendering (VR) 3D-TOF-MRA with accuracy, sensitivity, specificity, PPV and NPV of 94.9%, 94.0%, 100%, 100% and 74.4%, respectively, on a per aneurysm-based evaluation. VR 3D-TOF-MRA offers high diagnostic accuracy in the detection of ruptured intracranial aneurysms, and appears to be an effective treatment planning tool for most patients with SAH. VR 3D-TOF-MRA offers high diagnostic accuracy for detecting ruptured intracranial aneurysms. • VR 3D-TOF-MRA helps treatment planning for patients with subarachnoid haemorrhage. • 3D-TOF-MRA is non-invasive and avoids using ionising radiation or contrast agents.

  4. Highly undersampled contrast-enhanced MRA with iterative reconstruction: Integration in a clinical setting.

    PubMed

    Stalder, Aurelien F; Schmidt, Michaela; Quick, Harald H; Schlamann, Marc; Maderwald, Stefan; Schmitt, Peter; Wang, Qiu; Nadar, Mariappan S; Zenge, Michael O

    2015-12-01

    To integrate, optimize, and evaluate a three-dimensional (3D) contrast-enhanced sparse MRA technique with iterative reconstruction on a standard clinical MR system. Data were acquired using a highly undersampled Cartesian spiral phyllotaxis sampling pattern and reconstructed directly on the MR system with an iterative SENSE technique. Undersampling, regularization, and number of iterations of the reconstruction were optimized and validated based on phantom experiments and patient data. Sparse MRA of the whole head (field of view: 265 × 232 × 179 mm(3) ) was investigated in 10 patient examinations. High-quality images with 30-fold undersampling, resulting in 0.7 mm isotropic resolution within 10 s acquisition, were obtained. After optimization of the regularization factor and of the number of iterations of the reconstruction, it was possible to reconstruct images with excellent quality within six minutes per 3D volume. Initial results of sparse contrast-enhanced MRA (CEMRA) in 10 patients demonstrated high-quality whole-head first-pass MRA for both the arterial and venous contrast phases. While sparse MRI techniques have not yet reached clinical routine, this study demonstrates the technical feasibility of high-quality sparse CEMRA of the whole head in a clinical setting. Sparse CEMRA has the potential to become a viable alternative where conventional CEMRA is too slow or does not provide sufficient spatial resolution. © 2014 Wiley Periodicals, Inc.

  5. First-Pass Contrast-Enhanced MRA for Pretherapeutic Diagnosis of Spinal Epidural Arteriovenous Fistulas with Intradural Venous Reflux.

    PubMed

    Mathur, S; Symons, S P; Huynh, T J; Muthusami, P; Montanera, W; Bharatha, A

    2017-01-01

    Spinal epidural AVFs are rare spinal vascular malformations. When there is associated intradural venous reflux, they may mimic the more common spinal dural AVFs. Correct diagnosis and localization before conventional angiography is beneficial to facilitate treatment. We hypothesize that first-pass contrast-enhanced MRA can diagnose and localize spinal epidural AVFs with intradural venous reflux and distinguish them from other spinal AVFs. Forty-two consecutive patients with a clinical and/or radiologic suspicion of spinal AVF underwent MR imaging, first-pass contrast-enhanced MRA, and DSA at a single institute (2000-2015). MR imaging/MRA and DSA studies were reviewed by 2 independent blinded observers. DSA was used as the reference standard. On MRA, all 7 spinal epidural AVFs with intradural venous reflux were correctly diagnosed and localized with no interobserver disagreement. The key diagnostic feature was arterialized filling of an epidural venous pouch with a refluxing radicular vein arising from the arterialized epidural venous system. First-pass contrast-enhanced MRA is a reliable and useful technique for the initial diagnosis and localization of spinal epidural AVFs with intradural venous reflux and can distinguish these lesions from other spinal AVFs. © 2017 by American Journal of Neuroradiology.

  6. A meta-analysis of the diagnostic test accuracy of MRA and MRI for the detection of glenoid labral injury.

    PubMed

    Smith, Toby O; Drew, Benjamin T; Toms, Andoni P

    2012-07-01

    Magnetic resonance imaging (MRI) and magnetic resonance arthrography (MRA) have gained increasing favour in the assessment of patients with suspected glenoid labral injuries. The purpose of this study was to determine the diagnostic accuracy of MRI or MRA in the detection of gleniod labral lesions. A systematic review was undertaken of the electronic databases Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, AMED and CINAHL, in addition to a search of unpublished literature databases. All studies which compared the ability of MRI or MRA (index test) to assess gleniod labral tears or lesions, when verified with a surgical procedure (arthroscopy or open surgery-reference test) were included. Data extraction and methodological appraisal using the QUADAS tool were both conducted by two reviewers independently. Data were analysed through a summary receiver operator characteristic curve and pooled sensitivity and specificity analysis were calculated with 95% confidence intervals. Sixty studies including 4,667 shoulders from 4,574 patients were reviewed. There appeared slightly greater diagnostic test accuracy for MRA over MRI for the detection of overall gleniod labral lesions (MRA-sensitivity 88%, specificity 93% vs. MRI sensitivity 76% vs. specificity 87%). Methodologically, studies recruited and identified their samples appropriately and clearly defined the radiological procedures. In general, it was not clearly defined why patients were lost during the study, and studies were poor at recording whether the same clinical data were available to the radiologist interpreting the MRI or MRA as would be available in clinical practice. Most studies did not state whether the surgeon interpreting the arthroscopic procedure was blinded to the results of the MR or MRA imaging. Based on the available literature, overall MRA appeared marginally superior to MRI for the detection of glenohumeral labral lesions. Level 2a.

  7. Time-resolved 3D contrast-enhanced MRA on 3.0T: a non-invasive follow-up technique after stent-assisted coil embolization of the intracranial aneurysm.

    PubMed

    Choi, Jin Woo; Roh, Hong Gee; Moon, Won-Jin; Kim, Na Ra; Moon, Sung Gyu; Kang, Chung Hwan; Chun, Young Il; Kang, Hyun-Seung

    2011-01-01

    To evaluate the usefulness of time-resolved contrast enhanced magnetic resonance angiography (4D MRA) after stent-assisted coil embolization by comparing it with time of flight (TOF)-MRA. TOF-MRA and 4D MRA were obtained by 3T MRI in 26 patients treated with stent-assisted coil embolization (Enterprise:Neuroform = 7:19). The qualities of the MRA were rated on a graded scale of 0 to 4. We classified completeness of endovascular treatment into three categories. The degree of quality of visualization of the stented artery was compared between TOF and 4D MRA by the Wilcoxon signed rank test. We used the Mann-Whitney U test for comparing the quality of the visualization of the stented artery according to the stent type in each MRA method. The quality in terms of the visualization of the stented arteries in 4D MRA was significantly superior to that in 3D TOF-MRA, regardless of type of the stent (p < 0.001). The quality of the arteries which were stented with Neuroform was superior to that of the arteries stented with Enterprise in 3D TOF (p < 0.001) and 4D MRA (p = 0.008), respectively. 4D MRA provides a higher quality view of the stented parent arteries when compared with TOF.

  8. Diagnostic accuracy of CTA and MRI/MRA in the evaluation of the cortical venous reflux in the intracranial dural arteriovenous fistula DAVF.

    PubMed

    Lin, Yen-Heng; Wang, Yu-Fen; Liu, Hon-Man; Lee, Chung-Wei; Chen, Ya-Fang; Hsieh, Hong-Jen

    2018-01-01

    Computed tomography angiography (CTA) and magnetic resonance imaging/angiography (MRI/MRA) are used for the diagnosis of intracranial dural arteriovenous fistulas (DAVFs). The purpose of this study was to compare the diagnostic accuracy of CTA and magnetic resonance imaging/angiography (MRI/MRA) for detection of cortical venous reflux (CVR) in intracranial DAVFs. The records of patients with angiography-confirmed intracranial DAVFs who also received CTA and MRI/MRA from January 2008 to July 2016 were reviewed. CTA and MRI/MRA were reviewed for signs of CVR, and the diagnostic accuracy of individual signs was evaluated by receiver operating curve (ROC) analysis. A total 108 patients were included in this study. CTA signs of CVR included abnormal dilatation, early enhancement, and the presence of a medullary or pial vein. MRI/MRA signs of CVR included abnormal dilatation, early enhancement, flow-related enhancement, flow void, and medullary or pial venous collaterals. The sensitivity of individual CTA signs ranged from 62 to 96%, and specificities from 79 to 94%. The sensitivities of individual MRI/MRA signs ranged from 58 to 83%, and specificities from 77 to 93%. The area under ROC curve (AUC) of CTA and MRI/MRA were 0.91 and 0.87, respectively (P = 0.04 in direct comparison). In subgroup analysis, CTA had better diagnostic accuracy for higher grade disease (P = 0.05) and non-aggressive manifestation (P = 0.04). Both CTA and MRI/MRA have good diagnostic accuracy for detection of CVR in patients with intracranial DAVFs. There is modest evidence that CTA is better than MRI/MRA.

  9. Contrast-Enhanced and Time-of-Flight MRA at 3T Compared with DSA for the Follow-Up of Intracranial Aneurysms Treated with the WEB Device.

    PubMed

    Timsit, C; Soize, S; Benaissa, A; Portefaix, C; Gauvrit, J-Y; Pierot, L

    2016-09-01

    Imaging follow-up at 3T of intracranial aneurysms treated with the WEB Device has not been evaluated yet. Our aim was to assess the diagnostic accuracy of 3D-time-of-flight MRA and contrast-enhanced MRA at 3T against DSA, as the criterion standard, for the follow-up of aneurysms treated with the Woven EndoBridge (WEB) system. From June 2011 to December 2014, patients treated with the WEB in our institution, then followed for ≥6 months after treatment by MRA at 3T (3D-TOF-MRA and contrast-enhanced MRA) and DSA within 48 hours were included. Aneurysm occlusion was assessed with a simplified 2-grade scale (adequate occlusion [total occlusion + neck remnant] versus aneurysm remnant). Interobserver and intermodality agreement was evaluated by calculating the linear weighted κ. MRA test characteristics and predictive values were calculated from a 2 × 2 contingency table, by using DSA data as the standard of reference. Twenty-six patients with 26 WEB-treated aneurysms were included. The interobserver reproducibility was good with DSA (κ = 0.71) and contrast-enhanced-MRA (κ = 0.65) compared with moderate with 3D-TOF-MRA (κ = 0.47). Intermodality agreement with DSA was fair with both contrast-enhanced MRA (κ = 0.36) and 3D-TOF-MRA (κ = 0.36) for the evaluation of total occlusion. For aneurysm remnant detection, the prevalence was low (15%), on the basis of DSA, and both MRA techniques showed low sensitivity (25%), high specificity (100%), very good positive predictive value (100%), and very good negative predictive value (88%). Despite acceptable interobserver reproducibility and predictive values, the low sensitivity of contrast-enhanced MRA and 3D-TOF-MRA for aneurysm remnant detection suggests that MRA is a useful screening procedure for WEB-treated aneurysms, but similar to stents and flow diverters, DSA remains the criterion standard for follow-up. © 2016 by American Journal of Neuroradiology.

  10. Retrospective multi-phase non-contrast-enhanced magnetic resonance angiography (ROMANCE MRA) for robust angiogram separation in the presence of cardiac arrhythmia.

    PubMed

    Kim, Hahnsung; Park, Suhyung; Kim, Eung Yeop; Park, Jaeseok

    2018-09-01

    To develop a novel, retrospective multi-phase non-contrast-enhanced MRA (ROMANCE MRA) in a single acquisition for robust angiogram separation even in the presence of cardiac arrhythmia. In the proposed ROMANCE MRA, data were continuously acquired over all cardiac phases using retrospective, multi-phase flow-sensitive single-slab 3D fast spin echo (FSE) with variable refocusing flip angles, while an external pulse oximeter was in sync with pulse repetitions in FSE to record real-time information on cardiac cycles. Data were then sorted into k-bin space using the real-time cardiac information. Angiograms were reconstructed directly from k-bin space by solving a constrained optimization problem with both subtraction-induced sparsity and low rank priors. Peripheral MRA was performed in normal volunteers with/without caffeine consumption and a volunteer with cardiac arrhythmia using conventional fresh blood imaging (FBI) and the proposed ROMANCE MRA for comparison. The proposed ROMANCE MRA shows superior performance in accurately delineating both major and small vessel branches with robust background suppression if compared with conventional FBI. Even in the presence of irregular heartbeats, the proposed method exhibits clear depiction of angiograms over conventional methods within clinically reasonable imaging time. We successfully demonstrated the feasibility of the proposed ROMANCE MRA in generating robust angiograms with background suppression. © 2018 International Society for Magnetic Resonance in Medicine.

  11. Identification of the inflow zone of unruptured cerebral aneurysms: comparison of 4D flow MRI and 3D TOF MRA data.

    PubMed

    Futami, K; Sano, H; Misaki, K; Nakada, M; Ueda, F; Hamada, J

    2014-07-01

    The hemodynamics of the inflow zone of cerebral aneurysms may be a key factor in coil compaction and recanalization after endovascular coil embolization. We performed 4D flow MR imaging in conjunction with 3D TOF MRA and compared their ability to identify the inflow zone of unruptured cerebral aneurysms. This series comprised 50 unruptured saccular cerebral aneurysms in 44 patients. Transluminal color-coded 3D MRA images were created by selecting the signal-intensity ranges on 3D TOF MRA images that corresponded with both the luminal margin and the putative inflow. 4D flow MR imaging demonstrated the inflow zone and yielded inflow velocity profiles for all 50 aneurysms. In 18 of 24 lateral-projection aneurysms (75%), the inflow zone was located distally on the aneurysmal neck. The maximum inflow velocity ranged from 285 to 922 mm/s. On 4D flow MR imaging and transluminal color-coded 3D MRA studies, the inflow zone of 32 aneurysms (64%) was at a similar location. In 91% of aneurysms whose neck section plane angle was <30° with respect to the imaging section direction on 3D TOF MRA, depiction of the inflow zone was similar on transluminal color-coded 3D MRA and 4D flow MR images. 4D flow MR imaging can demonstrate the inflow zone and provide inflow velocity profiles. In aneurysms whose angle of the neck-section plane is obtuse vis-a-vis the imaging section on 3D TOF MRA scans, transluminal color-coded 3D MRA may depict the inflow zone reliably. © 2014 by American Journal of Neuroradiology.

  12. A novel non-contrast-enhanced MRA using silent scan for evaluation of brain arteriovenous malformation: A case report and review of literature.

    PubMed

    Moon, Jin Il; Baek, Hye Jin; Ryu, Kyeong Hwa; Park, Hyun

    2017-11-01

    Brain arteriovenous malformations (AVMs) are congenital vascular abnormalities involving abnormal connections between arteries and veins. In clinical practice, imaging studies help evaluate feeding arteries, niduses, draining venous systems, and coexisting complications in patients with brain AVM. They also have an impact on decision-making regarding clinical management. We applied a novel non-contrast-enhanced MR angiography (MRA) technique, termed "silent MRA," for evaluating an incidental brain AVM. Here, we describe the clinical case with radiological review and highlight the technical background and clinical usefulness of silent MRA. A 60-year-old woman underwent neuroimaging study including MRA to evaluate intracranial cause of headache. The brain AVM, including its nidus and draining veins, was conspicuously delineated on silent MRA images; these findings correlated well with conventional angiographic findings. The patient did not receive interventional or surgical treatment. The patient is being followed up regularly at the outpatient department. The silent MRA can be a suitable imaging modality for repeated follow-up evaluation for not only brain AVMs but also various intracranial vascular diseases without the use of contrast materials.

  13. Comparison of ferumoxytol-enhanced MRA with conventional angiography for assessment of severity of transplant renal artery stenosis.

    PubMed

    Fananapazir, Ghaneh; Bashir, Mustafa R; Corwin, Michael T; Lamba, Ramit; Vu, Catherine T; Troppmann, Christoph

    2017-03-01

    To determine the accuracy of ferumoxytol-enhanced magnetic resonance angiography (MRA) in assessing the severity of transplant renal artery stenosis (TRAS), using digital subtraction angiography (DSA) as the reference standard. Our Institutional Review Board approved this retrospective, Health Insurance Portability and Accountability Act-compliant study. Thirty-three patients with documented clinical suspicion for TRAS (elevated serum creatinine, refractory hypertension, edema, and/or audible bruit) and/or concerning sonographic findings (elevated renal artery velocity and/or intraparenchymal parvus tardus waveforms) underwent a 1.5T MRA with ferumoxytol prior to DSA. All DSAs were independently reviewed by an interventional radiologist and served as the reference standard. The MRAs were reviewed by three readers who were blinded to the ultrasound and DSA findings for the presence and severity of TRAS. Sensitivity, specificity, and accuracy for identifying substantial stenoses (>50%) were determined. Intraclass correlation coefficients (ICCs) were calculated among readers. Mean differences between the percent stenosis from each MRA reader and DSA were calculated. On DSA, a total of 42 stenoses were identified in the 33 patients. The sensitivity, specificity, and accuracy of MRA in detecting substantial stenoses were 100%, 75-87.5%, and 95.2-97.6%, respectively, among the readers. There was excellent agreement among readers as to the percent stenosis (ICC = 0.82). MRA overestimated the degree of stenosis by 3.9-9.6% compared to DSA. Ferumoxytol-enhanced MRA provides high sensitivity, specificity, and accuracy for determining the severity of TRAS. Our results suggest that it can potentially be used as a noninvasive examination following ultrasound to reduce the number of unnecessary conventional angiograms. 3 J. Magn. Reson. Imaging 2017;45:779-785. © 2016 International Society for Magnetic Resonance in Medicine.

  14. Implant-specific follow-up imaging of treated intracranial aneurysms: TOF-MRA vs. metal artifact reduced intravenous flat panel computed tomography angiography (FPCTA).

    PubMed

    Hänsel, N H; Schubert, G A; Scholz, B; Nikoubashman, O; Othman, A E; Wiesmann, M; Pjontek, R; Brockmann, M A

    2018-02-01

    To compare the diagnostic quality of time-of-flight magnetic resonance angiography (TOF-MRA) and metal-artefact-reduction (MAR) flat-panel-detector computed tomography angiography (FPCTA) and to determine the imaging technique best suited for evaluation endovascular and surgically treated aneurysms. The image quality of TOF-MRA and MAR-FPCTA of 44 intracranial implants (coiling: n=20; clipping: n=15; coiling + stenting: n=9) in a patient cohort of 25 was evaluated by two independent readers. Images obtained using MAR-FPCTA (20 second scan time, 496 projections, intravenous contrast medium administration; Artis Zee, Siemens Healthcare, Forchheim) were compared with TOF-MRA-images (1.5 or 3 T). Nominal data were analysed using McNemar's chi-square test and ordinal variables using the Wilcoxon rank test. Compared to TOF-MRA, MAR-FPCTA was significantly better suited to detect aneurysm remnants and to evaluate parent vessels after clipping (p<0.01). For coil packages >160 mm 3 , TOF-MRA provided significantly better assessment than MAR-FPCTA (p<0.01). For small coil packages (<160 mm 3 ), no significant difference between TOF-MRA and MAR-FPCTA (p=0.232) was observed. For different clip sizes (cut-off 492 mm 3 ) likewise no significant differences were found. The interobserver comparison showed high interrater agreement. MAR-FPCTA is significantly better suited for follow-up examinations of clipped aneurysms, whereas for larger coil packages TOF-MRA is preferable. Smaller coil packages can be analysed using MAR-FPCTA or TOF-MRA. Copyright © 2017 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

  15. 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.

  16. 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

  17. 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.

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

    PubMed

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Mankovich, Nicholas J.; Lambert, Timothy; Zrimec, Tatjana; Hiller, John B.

    1995-05-01

    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. We have developed a vascular phantom suitable for testing segmentation and fusion algorithms with either derived images (psuedo-MRA/psuedo-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.

  20. [Can TOF MRA replace duplex and Doppler sonography in preoperative assessment of the carotid arteries? A prospective comparison and review of the literature].

    PubMed

    Krappel, F A; Bauer, E; Harland, U

    2002-01-01

    To examine the quality and usefulness of time-of-flight MR-angiography and duplex-doppler sonography, respectively, in assessment of the extracranial arteries before cervical spine operations. Patients scheduled for operations of the cervical spine had an MRI plus TOF as well as a duplex and Doppler scan. At the time of the examination the radiologist and the neurologist in charge were blinded for the study. Endpoints were not only the accuracy of the procedures but more so which method improved the preoperative process most. Twenty patients were examined so far. Only in one case did the result differ when a complete occlusion diagnosed sonographically was judged as a severe stenosis on MRA. One patient did not tolerate the MRA for the extra 5 minutes necessary, therefore a contrast-enhanced MRA was performed. MRA eased the preoperative process as imaging of the pathology and the carotids were realised in one step. The costs were slightly higher for MRA than for duplex-doppler sonography. TOF-MRA can replace the duplex-doppler examination in the preoperative assessment of the carotids and has the potential to streamline the preoperative time schedule. Similar to duplex and doppler, in order to be accurate enough the method requires a high degree of expertise from the radiologist.

  1. Supra-aortic arteries: three-dimensional time-resolved k-t BLAST contrast-enhanced MRA using a nondedicated body coil at 3 tesla in acute ischemic stroke.

    PubMed

    Ferré, Jean-Christophe; Raoult, Hélène; Breil, Stéphane; Carsin-Nicol, Béatrice; Ronzière, Thomas; Gauvrit, Jean-Yves

    2014-11-01

    To assess the image quality and diagnostic performance achieved by using supra-aortic 3D-TR-CE-k-t BLAST MRA and a nondedicated body coil as compared with conventional CE-MRA in patients with acute ischemic stroke. In this prospective study, 36 consecutive patients with a suspected acute ischemic stroke underwent both k-t BLAST MRA and conventional CE-MRA. Image quality was assessed using visual and quantitative criteria and the techniques were compared. Both techniques were compared for degree of visual and quantitative measurement of carotid stenosis. Delineation of vessel lumen and overall diagnostic confidence were significantly better with CE-MRA, respectively 3.4 ± 0.5 and 3.3 ± 0.6 (mean score ± SD), than with k-t BLAST MRA, respectively 2.8 ± 0.4 and 2.9 ± 0.5 (P < 0.02). SNR and CNR were significantly higher for k-t BLAST MRA, respectively 33.5 ± 19.3 and 27.9 ± 19.3, than for CE-MRA, respectively 25.7 ± 10 and 20.4 ± 8.4 (P < 0.03). Intertechnique agreement was good for carotid stenosis characterization (κ = .763). For the 14 relevant stenosis, stenosis measurements were highly correlated between techniques (0.96; P < 0.0001). The Bland-Altman plot showed a low bias in assessment of the degree of stenosis (mean bias 2.1% ± 7.7). k-t BLAST MRA using a nondedicated coil offering and dynamic information was a effective diagnostic tool for detection and characterization of carotid stenosis. © 2013 Wiley Periodicals, Inc.

  2. Clinical Presentation, Predictors, and Outcomes Among Mineralocorticoid Receptor Antagonist (MRA)-Eligible Acute Heart Failure Patients in the Heart Function Assessment Registry Trial in Saudi Arabia (HEARTS).

    PubMed

    AlShamiri, Mostafa Q; AlHabib, Khalid F; AlHabeeb, Waleed; Raslan, Ismail R; Ullah, Anhar; Elasfar, Abdelfatah A; Alshaer, Fayez; Albackr, Hanan; Mimish, Layth; Almasood, Ali; AlGhamdi, Saleh; Ghabashi, Abdullah

    2018-04-01

    Mineralocorticoid receptor antagonist (MRA) therapy is indicated after myocardial infarction in patients with acute heart failure (AHF) with an ejection fraction ≤40% and lacking contraindications. We analyzed clinical presentations, predictors, and outcomes of MRA-eligible patients within a prospective registry of patients with AHF from 18 hospitals in Saudi Arabia, from 2009 to 2010. For this subgroup, mortality rates were followed until 2013, and the clinical characteristics, management, predictors, and outcomes were compared between MRA-treated and non-MRA-treated patients. Of 2609 patients with AHF, 387 (14.8%) were MRA eligible, of which 146 (37.7%) were prescribed MRAs. Compared with non-MRA-treated patients, those prescribed MRAs more commonly exhibited non-ST-segment elevation myocardial infarction, acute on chronic heart failure, past history of ischemic heart disease, and severe left ventricular systolic dysfunction; were more commonly administered oral furosemide and digoxin; and had higher in-hospital recurrent congestive HF rates. Mortality did not significantly differ ( P > .05) between groups. In Saudi Arabia, 37.7% of eligible patients received MRA treatment, which is higher than that in developed countries. The lack of long-term survival benefit raises concerns about systematic problems, for example, proper follow-up and management after hospital discharge, warranting further investigation.

  3. A pitfall of the volume rendering method with 3D time-of-flight MRA: a case of a branching vessel at the aneurysm neck.

    PubMed

    Goto, Masami; Kunimatsu, Akira; Shojima, Masaaki; Abe, Osamu; Aoki, Shigeki; Hayashi, Naoto; Mori, Harushi; Ino, Kenji; Yano, Keiichi; Saito, Nobuhito; Ohtomo, Kuni

    2013-03-25

    We present a case in which the origin of the branching vessel at the aneurysm neck was observed at the wrong place on the volume rendering method (VR) with 3D time-of-flight MRA (3D-TOF-MRA) with 3-Tesla MR system. In 3D-TOF-MRA, it is often difficult to observe the origin of the branching vessel, but it is unusual for it to be observed in the wrong place. In the planning of interventional treatment and surgical procedures, false recognition, as in the unique case in the present report, is a serious problem. Decisions based only on VR with 3D-TOF-MRA can be a cause of suboptimal selection in clinical treatment.

  4. 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

  5. 3.0Tesla magnetic resonance angiography (MRA) for comprehensive renal evaluation of living renal donors: pilot study with computerized tomography angiography (CTA) comparison.

    PubMed

    Gulati, Mittul; Dermendjian, Harout; Gómez, Ana M; Tan, Nelly; Margolis, Daniel J; Lu, David S; Gritsch, H Albin; Raman, Steven S

    2016-01-01

    Most living related donor (LRD) kidneys are harvested laparoscopically. Renal vascular anatomy helps determine donor suitability for laparoscopic nephrectomy. Computed tomography angiography (CTA) is the current gold standard for preoperative imaging; magnetic resonance angiography (MRA) offers advantages including lack of ionizing radiation and lower incidence of contrast reactions. We evaluated 3.0T MRA for assessing renal anatomy of LRDs. Thirty consecutive LRDs underwent CTA followed by 3.0T MRA. Data points included number and branching of vessels, incidental findings, and urothelial opacification. Studies were individually evaluated by three readers blinded to patient data. Studies were reevaluated in consensus with discrepancies revealed, and final consensus results were labeled "truth". Compared with consensus "truth", both computed tomography (CT) and magnetic resonance imaging were highly accurate for assessment of arterial and venous anatomy, although CT was superior for detection of late venous confluence as well as detection of renal stones. Both modalities were comparable in opacification of lower ureters and bladder; MRA underperformed CTA for opacification of upper urinary tracts. 3.0T MRA enabled excellent detection of comprehensive renal anatomy compared to CTA in LRDs. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. 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

  7. 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.

  8. Aneurysm outflow angle at MRA as discriminant for accurate diagnosis and differentiation between small sidewall cerebral aneurysms and infundibula.

    PubMed

    Sun, Ling-Jun; Li, Yong-Dong; Li, Ming-Hua; Wang, Wu; Gu, Bin-Xian

    2017-06-01

    To evaluate whether the aneurysm outflow angle (OA) at MR angiography (MRA) might serve as discriminant for accurate diagnosis of, and differentiation between, small sidewall cerebral aneurysms (SCAs) and infundibula. Between June 2007 and July 2015, 426 consecutive patients with SCAs completed both an MRA and DSA examination. Of these, 156 patients with small SCAs and 52 patients with infundibula were included in this study. A patient with an OA ≥90° was defined as having a SCA, while those with OA <90° were defined as having an infundibulum. DSA identified 172 SCAs in 156 patients and 55 infundibula in 52 patients. The average OA on MRA was 102.96°±13.36° (range 60°-151°) in 172 SCAs of 156 patients. An OA of ≥90° was seen for 159 (92.4%) small SCAs in 147 patients, while an OA of <90° was observed for 13 SCAs. The average OA on MRA was 69.05°±14.26° (range 35-107°) in 55 infundibula of 52 patients. An OA of ≥90° was seen in one patient with one infundibulum; while an OA of <90° was observed for 54 infundibula (98.2%) in 51 patients. The average OA in SCAs (n=172) was greater than the average OA in infundibula (n=55; 102.96° vs 69.05°, p<0.001). The OA at MRA could serve as discriminant for accurate diagnosis of, and differentiation between, small SCAs and infundibula. 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. High-resolution structural and functional assessments of cerebral microvasculature using 3D Gas ΔR2*-mMRA.

    PubMed

    Huang, Chien-Hsiang; Chen, Chiao-Chi V; Siow, Tiing-Yee; Hsu, Sheng-Hsiou S; Hsu, Yi-Hua; Jaw, Fu-Shan; Chang, Chen

    2013-01-01

    The ability to evaluate the cerebral microvascular structure and function is crucial for investigating pathological processes in brain disorders. Previous angiographic methods based on blood oxygen level-dependent (BOLD) contrast offer appropriate visualization of the cerebral vasculature, but these methods remain to be optimized in order to extract more comprehensive information. This study aimed to integrate the advantages of BOLD MRI in both structural and functional vascular assessments. The BOLD contrast was manipulated by a carbogen challenge, and signal changes in gradient-echo images were computed to generate ΔR2* maps. Simultaneously, a functional index representing the regional cerebral blood volume was derived by normalizing the ΔR2* values of a given region to those of vein-filled voxels of the sinus. This method is named 3D gas ΔR2*-mMRA (microscopic MRA). The advantages of using 3D gas ΔR2*-mMRA to observe the microvasculature include the ability to distinguish air-tissue interfaces, a high vessel-to-tissue contrast, and not being affected by damage to the blood-brain barrier. A stroke model was used to demonstrate the ability of 3D gas ΔR2*-mMRA to provide information about poststroke revascularization at 3 days after reperfusion. However, this technique has some limitations that cannot be overcome and hence should be considered when it is applied, such as magnifying vessel sizes and predominantly revealing venous vessels.

  10. Contribution of the Pmra Promoter to Expression of Genes in the Escherichia coli mra Cluster of Cell Envelope Biosynthesis and Cell Division Genes

    PubMed Central

    Mengin-Lecreulx, Dominique; Ayala, Juan; Bouhss, Ahmed; van Heijenoort, Jean; Parquet, Claudine; Hara, Hiroshi

    1998-01-01

    Recently, a promoter for the essential gene ftsI, which encodes penicillin-binding protein 3 of Escherichia coli, was precisely localized 1.9 kb upstream from this gene, at the beginning of the mra cluster of cell division and cell envelope biosynthesis genes (H. Hara, S. Yasuda, K. Horiuchi, and J. T. Park, J. Bacteriol. 179:5802–5811, 1997). Disruption of this promoter (Pmra) on the chromosome and its replacement by the lac promoter (Pmra::Plac) led to isopropyl-β-d-thiogalactopyranoside (IPTG)-dependent cells that lysed in the absence of inducer, a defect which was complemented only when the whole region from Pmra to ftsW, the fifth gene downstream from ftsI, was provided in trans on a plasmid. In the present work, the levels of various proteins involved in peptidoglycan synthesis and cell division were precisely determined in cells in which Pmra::Plac promoter expression was repressed or fully induced. It was confirmed that the Pmra promoter is required for expression of the first nine genes of the mra cluster: mraZ (orfC), mraW (orfB), ftsL (mraR), ftsI, murE, murF, mraY, murD, and ftsW. Interestingly, three- to sixfold-decreased levels of MurG and MurC enzymes were observed in uninduced Pmra::Plac cells. This was correlated with an accumulation of the nucleotide precursors UDP–N-acetylglucosamine and UDP–N-acetylmuramic acid, substrates of these enzymes, and with a depletion of the pool of UDP–N-acetylmuramyl pentapeptide, resulting in decreased cell wall peptidoglycan synthesis. Moreover, the expression of ftsZ, the penultimate gene from this cluster, was significantly reduced when Pmra expression was repressed. It was concluded that the transcription of the genes located downstream from ftsW in the mra cluster, from murG to ftsZ, is also mainly (but not exclusively) dependent on the Pmra promoter. PMID:9721276

  11. An interleaved sequence for simultaneous magnetic resonance angiography (MRA), susceptibility weighted imaging (SWI) and quantitative susceptibility mapping (QSM).

    PubMed

    Chen, Yongsheng; Liu, Saifeng; Buch, Sagar; Hu, Jiani; Kang, Yan; Haacke, E Mark

    2018-04-01

    To image the entire vasculature of the brain with complete suppression of signal from background tissue using a single 3D excitation interleaved rephased/dephased multi-echo gradient echo sequence. This ensures no loss of signal from fast flow and provides co-registered susceptibility weighted images (SWI) and quantitative susceptibility maps (QSM) from the same scan. The suppression of background tissue was accomplished by subtracting the flow-dephased images from the flow-rephased images with the same echo time of 12.5ms to generate a magnetic resonance angiogram and venogram (MRAV). Further, a 2.5ms flow-compensated echo was added in the rephased portion to provide sufficient signal for major arteries with fast flow. The QSM data from the rephased 12.5ms echo was used to suppress veins on the MRAV to generate an artery-only MRA. The proposed approach was tested on five healthy volunteers at 3T. This three-echo interleaved GRE sequence provided complete background suppression of stationary tissues, while the short echo data gave high signal in the internal carotid and middle cerebral arteries (MCA). The contrast-to-noise ratio (CNR) of the arteries was significantly improved in the M3 territory of the MCA compared to the non-linear subtraction MRA and TOF-MRA. Veins were suppressed successfully utilizing the QSM data. The background tissue can be properly suppressed using the proposed interleaved MRAV sequence. One can obtain whole brain MRAV, MRA, SWI, true-SWI (or tSWI) and QSM data simultaneously from a single scan. Published by Elsevier Inc.

  12. 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.

  13. A Comparison of Various MRA Methods Applied to Longitudinal Evaluation Studies in Vocational Education.

    ERIC Educational Resources Information Center

    Kapes, Jerome T.; And Others

    Three models of multiple regression analysis (MRA): single equation, commonality analysis, and path analysis, were applied to longitudinal data from the Pennsylvania Vocational Development Study. Variables influencing weekly income of vocational education students one year after high school graduation were examined: grade point averages (grades…

  14. A comparison between gadofosveset trisodium and gadobenate dimeglumine for steady state MRA of the thoracic vasculature.

    PubMed

    Camren, G Paul; Wilson, Gregory J; Bamra, Vikram R; Nguyen, Khahn Q; Hippe, Daniel S; Maki, Jeffrey H

    2014-01-01

    Retrospective comparison between gadofosveset trisodium and gadobenate dimeglumine steady state magnetic resonance angiography (SS-MRA) of the thoracic vasculature at 1.5T using signal-to-noise ratio (SNR) and vessel edge sharpness (ES) as markers of image quality. IRB approval was obtained. Twenty separate patients each underwent SS-MRA using high-resolution 3D ECG-triggered coronal IR-TFE at 1.5T approximately 3-4 minutes following 10 or 15 mL gadofosveset or 20 mL gadobenate. ROIs were placed in the right atrium, left ventricle, left atrium, ascending aorta, descending aorta, and right pulmonary artery to estimate SNR. Vessel ES was estimated as 20-80% rise distances from line intensity profiles in the left pulmonary vein, ascending aorta, and descending aorta. Data were analyzed using nonpaired Student's t-test (threshold for significance set at P < 0.05). There was no significant difference in mean SNR for the gadofosveset or gadobenate groups (P values: 0.14 to 0.85). There was no significant difference in mean vessel ES for gadofosveset and gadobenate groups (P values: 0.17 to 0.78). High quality thoracic SS-MRA can be achieved with gadobenate dimeglumine, similar to that achieved with the blood pool agent gadofosveset trisodium provided that imaging is initiated quickly (3-4 min) after contrast injection.

  15. A Comparison between Gadofosveset Trisodium and Gadobenate Dimeglumine for Steady State MRA of the Thoracic Vasculature

    PubMed Central

    Camren, G. Paul; Wilson, Gregory J.; Bamra, Vikram R.; Nguyen, Khahn Q.; Hippe, Daniel S.; Maki, Jeffrey H.

    2014-01-01

    Purpose. Retrospective comparison between gadofosveset trisodium and gadobenate dimeglumine steady state magnetic resonance angiography (SS-MRA) of the thoracic vasculature at 1.5T using signal-to-noise ratio (SNR) and vessel edge sharpness (ES) as markers of image quality. Materials and Methods. IRB approval was obtained. Twenty separate patients each underwent SS-MRA using high-resolution 3D ECG-triggered coronal IR-TFE at 1.5T approximately 3-4 minutes following 10 or 15 mL gadofosveset or 20 mL gadobenate. ROIs were placed in the right atrium, left ventricle, left atrium, ascending aorta, descending aorta, and right pulmonary artery to estimate SNR. Vessel ES was estimated as 20–80% rise distances from line intensity profiles in the left pulmonary vein, ascending aorta, and descending aorta. Data were analyzed using nonpaired Student's t-test (threshold for significance set at P < 0.05). Results. There was no significant difference in mean SNR for the gadofosveset or gadobenate groups (P values: 0.14 to 0.85). There was no significant difference in mean vessel ES for gadofosveset and gadobenate groups (P values: 0.17 to 0.78). Conclusion. High quality thoracic SS-MRA can be achieved with gadobenate dimeglumine, similar to that achieved with the blood pool agent gadofosveset trisodium provided that imaging is initiated quickly (3-4 min) after contrast injection. PMID:25061611

  16. Exact monitoring of aortic diameters in Marfan patients without gadolinium contrast: intraindividual comparison of 2D SSFP imaging with 3D CE-MRA and echocardiography.

    PubMed

    Veldhoen, Simon; Behzadi, Cyrus; Derlin, Thorsten; Rybczinsky, Meike; von Kodolitsch, Yskert; Sheikhzadeh, Sara; Henes, Frank Oliver; Bley, Thorsten Alexander; Adam, Gerhard; Bannas, Peter

    2015-03-01

    To assess whether ECG-gated non-contrast 2D steady-state free precession (SSFP) imaging allows for exact monitoring of aortic diameters in Marfan syndrome (MFS) patients using non-ECG-gated contrast-enhanced 3D magnetic resonance angiography (CE-MRA) and echocardiography for intraindividual comparison. Non-ECG-gated CE-MRA and ECG-gated non-contrast SSFP at 1.5 T were prospectively performed in 50 patients. Two readers measured aortic diameters on para-sagittal images identically aligned with the aortic arch at the sinuses of Valsalva, sinotubular junction, ascending/descending aorta and aortic arch. Image quality was assessed on a three-point scale. Aortic root diameters acquired by echocardiography were used as reference. Intra- and interobserver variances were smaller for SSFP at the sinuses of Valsalva (p = 0.002; p = 0.002) and sinotubular junction (p = 0.014; p = 0.043). Image quality was better in SSFP than in CE-MRA at the sinuses of Valsalva (p < 0.0001), sinotubular junction (p < 0.0001) and ascending aorta (p = 0.02). CE-MRA yielded higher diameters than SSFP at the sinuses of Valsalva (mean bias, 2.5 mm; p < 0.0001), and comparison with echocardiography confirmed a higher bias for CE-MRA (7.2 ± 3.4 mm vs. SSFP, 4.7 ± 2.6 mm). ECG-gated non-contrast 2D SSFP imaging provides superior image quality with higher validity compared to non-ECG-gated contrast-enhanced 3D imaging. Since CE-MRA requires contrast agents with potential adverse effects, non-contrast SSFP imaging is an appropriate alternative for exact and riskless aortic monitoring of MFS patients.

  17. 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.

  18. Collateral circulation via the circle of Willis in patients with carotid artery steno-occlusive disease: evaluation on 3-T 4D MRA using arterial spin labelling.

    PubMed

    Iryo, Yasuhiko; Hirai, Toshinori; Nakamura, Masanobu; Inoue, Yasuteru; Watanabe, Masaki; Ando, Yukio; Azuma, Minako; Nishimura, Shinichiro; Shigematsu, Yoshinori; Kitajima, Mika; Yamashita, Yasuyuki

    2015-09-01

    To evaluate whether 3-T four-dimensional (4D) arterial spin-labelling (ASL) -based magnetic resonance angiography (MRA) is useful for assessing the collateral circulation via the circle of Willis in patients with carotid artery steno-occlusive disease. Institutional review board approval and prior written informed consent from all patients were obtained. The inclusion criteria were fulfilled by 13 patients with carotid artery steno-occlusive disease. All underwent 4D-ASL MRA at 3 T and digital subtraction angiography (DSA). The flow-sensitive alternating inversion recovery (FAIR) preparation scheme with look-locker sampling was used for spin labeling. At 300-ms intervals seven dynamic scans were obtained with a spatial resolution of 0.5×0.5×0.6 mm(3). The collateral flow via the circle of Willis was read on 4D-ASL MRA and DSA images by two sets of two independent readers each. κ statistics were used to assess interobserver and intermodality agreement. On DSA, collateral flow via the anterior communicating artery (AcomA) was observed in six patients, via the posterior communicating artery (PcomA) in four patients, and via both the AcomA and PcomA in three patients. With respect to the qualitative evaluation of 4D-ASL MRA images, interobserver agreement was excellent for all items (κ=1). 4D-ASL MRA and DSA consensus readings agreed on the type of collateral flow pattern in 10 of the 13 patients (77%). Intermodality agreement was good (κ=0.606; 95% confidence interval (CI): 0.215-0.997). 3 T 4D-ASL MRA may be a useful tool for the evaluation of the collateral circulation in patients with carotid artery steno-occlusive disease. Copyright © 2015 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

  19. 3D Geometric Analysis of the Pediatric Aorta in 3D MRA Follow-Up Images with Application to Aortic Coarctation.

    PubMed

    Wörz, Stefan; Schenk, Jens-Peter; Alrajab, Abdulsattar; von Tengg-Kobligk, Hendrik; Rohr, Karl; Arnold, Raoul

    2016-10-17

    Coarctation of the aorta is one of the most common congenital heart diseases. Despite different treatment opportunities, long-term outcome after surgical or interventional therapy is diverse. Serial morphologic follow-up of vessel growth is necessary, because vessel growth cannot be predicted by primer morphology or a therapeutic option. For the analysis of the long-term outcome after therapy of congenital diseases such as aortic coarctation, accurate 3D geometric analysis of the aorta from follow-up 3D medical image data such as magnetic resonance angiography (MRA) is important. However, for an objective, fast, and accurate 3D geometric analysis, an automatic approach for 3D segmentation and quantification of the aorta from pediatric images is required. We introduce a new model-based approach for the segmentation of the thoracic aorta and its main branches from follow-up pediatric 3D MRA image data. For robust segmentation of vessels even in difficult cases (e.g., neighboring structures), we propose a new extended parametric cylinder model that requires only relatively few model parameters. Moreover, we include a novel adaptive background-masking scheme used for least-squares model fitting, we use a spatial normalization scheme to align the segmentation results from follow-up examinations, and we determine relevant 3D geometric parameters of the aortic arch. We have evaluated our proposed approach using different 3D synthetic images. Moreover, we have successfully applied the approach to follow-up pediatric 3D MRA image data, we have normalized the 3D segmentation results of follow-up images of individual patients, and we have combined the results of all patients. We also present a quantitative evaluation of our approach for four follow-up 3D MRA images of a patient, which confirms that our approach yields accurate 3D segmentation results. An experimental comparison with two previous approaches demonstrates that our approach yields superior results. From the

  20. 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

  1. Pre-procedural assessment of aortic annulus dimensions for transcatheter aortic valve replacement: comparison of a non-contrast 3D MRA protocol with contrast-enhanced cardiac dual-source CT angiography.

    PubMed

    Ruile, Philipp; Blanke, Philipp; Krauss, Tobias; Dorfs, Stephan; Jung, Bernd; Jander, Nikolaus; Leipsic, Jonathon; Langer, Mathias; Neumann, Franz-Josef; Pache, Gregor

    2016-04-01

    To evaluate the feasibility of a non-contrast three-dimensional (3D)-FLASH magnetic resonance angiography (MRA) protocol for pre-procedural aortic annulus assessment for transcatheter aortic valve replacement (TAVR) in comparison with cardiac dual-source computed tomography angiography (CTA). In this prospective study, 69 of 104 consecutive patients (mean age 81.8 ± 5.4 years, 37.7% arrhythmic) with severe aortic stenosis who had undergone pre-TAVR cardiac CTA received a respiratory and ECG-triggered, non-contrast 3D-FLASH MRA at 3 T. Annular area measurements were obtained at mid-diastole for both modalities whereas maximum systolic area was assessed by CTA only. Systolic MRA dimensions were modelled, by adding the relative difference of systolic and diastolic CTA area dimensions as a corrective factor. Hypothetical prosthesis sizing was performed based on systolic CTA, diastolic, and modelled systolic MRA area measurements. MR image quality and degree of annular calcifications were evaluated using 4-point-grading scales. The mean acquisition time was 14 ± 4.2 min. The mean image quality was 3.1 ± 0.9 with only two examinations rated non-diagnostic. The mean degree of calcifications was equal. As assessed by Bland-Altman analysis, there was no relevant systematic difference between area measurements for modelled systolic MRA and systolic CTA [the mean difference -3.1 mm(2) (limits of agreement -44.4 mm(2); 38.2 mm(2))]. Agreement for hypothetical prosthesis sizing was found in 63 of 67 (94%) patients for systolic CTA and modelled systolic MRA. The employed non-contrast 3D-FLASH MRA protocol allows for reliable assessment of aortic annulus dimensions and calcifications even in the presence of arrhythmias in an all-comers pre-TAVR population. Implementation of this technique appears legitimate in patients at an increased risk for contrast-induced nephropathy. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For

  2. Reproducibility of cerebrospinal venous blood flow and vessel anatomy with the use of phase contrast-vastly undersampled isotropic projection reconstruction and contrast-enhanced MRA.

    PubMed

    Schrauben, E M; Johnson, K M; Huston, J; Del Rio, A M; Reeder, S B; Field, A; Wieben, O

    2014-05-01

    The chronic cerebrospinal venous insufficiency hypothesis raises interest in cerebrospinal venous blood flow imaging, which is more complex and less established than in arteries. For accurate assessment of venous flow in chronic cerebrospinal venous insufficiency diagnosis and research, we must account for physiologic changes in flow patterns. This study examines day-to-day flow variability in cerebrospinal veins by use of 4D MR flow and contrast-enhanced MRA under typical, uncontrolled conditions in healthy individuals. Ten healthy volunteers were scanned in a test-retest fashion by use of a 4D flow MR imaging technique and contrast-enhanced MRA. Flow parameters obtained from phase contrast-vastly undersampled isotropic projection reconstruction and contrast-enhanced MRA scoring measurements in the head, neck, and chest veins were analyzed for internal consistency and interscan reproducibility. Internal consistency was satisfied at the torcular herophili, with an input-output difference of 2.2%. Percentages of variations in flow were 20.3%, internal jugular vein; 20.4%, azygos vein; 6.8%, transverse sinus; and 5.1%, common carotid artery. Retrograde flow was found in the lower internal jugular vein (4.8%) and azygos vein (7.2%). Contrast-enhanced MRA interscan κ values for the internal jugular vein (left: 0.474, right: 0.366) and azygos vein (-0.053) showed poor interscan agreement. Phase contrast-vastly undersampled isotropic projection reconstruction blood flow measurements are reliable and highly reproducible in intracranial veins and in the common carotid artery but not in veins of the neck (internal jugular vein) and chest (azygos vein) because of normal physiologic variation. Retrograde flow normally may be observed in the lower internal jugular vein and azygos vein. Low interrater agreement in contrast-enhanced MRA scans was observed. These findings have important implications for imaging diagnosis and experimental research of chronic cerebrospinal venous

  3. The cell wall and cell division gene cluster in the Mra operon of Pseudomonas aeruginosa: cloning, production, and purification of active enzymes.

    PubMed

    Azzolina, B A; Yuan, X; Anderson, M S; El-Sherbeini, M

    2001-04-01

    We have cloned the Pseudomonas aeruginosa cell wall biosynthesis and cell division gene cluster that corresponds to the mra operon in the 2-min region of the Escherichia coli chromosome. The organization of the two chromosomal regions in P. aeruginosa and E. coli is remarkably similar with the following gene order: pbp3/pbpB, murE, murF, mraY, murD, ftsW, murG, murC, ddlB, ftsQ, ftsA, ftsZ, and envA/LpxC. All of the above P. aeruginosa genes are transcribed from the same strand of DNA with very small, if any, intragenic regions, indicating that these genes may constitute a single operon. All five amino acid ligases, MurC, MurD, MurE, MurF, and DdlB, in addition to MurG and MraY were cloned in expression vectors. The four recombinant P. aeruginosa Mur ligases, MurC, MurD, MurE, and MurF were overproduced in E. coli and purified as active enzymes. Copyright 2001 Academic Press.

  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. Development of a quantitative intracranial vascular features extraction tool on 3D MRA using semiautomated open-curve active contour vessel tracing.

    PubMed

    Chen, Li; Mossa-Basha, Mahmud; Balu, Niranjan; Canton, Gador; Sun, Jie; Pimentel, Kristi; Hatsukami, Thomas S; Hwang, Jenq-Neng; Yuan, Chun

    2018-06-01

    To develop a quantitative intracranial artery measurement technique to extract comprehensive artery features from time-of-flight MR angiography (MRA). By semiautomatically tracing arteries based on an open-curve active contour model in a graphical user interface, 12 basic morphometric features and 16 basic intensity features for each artery were identified. Arteries were then classified as one of 24 types using prediction from a probability model. Based on the anatomical structures, features were integrated within 34 vascular groups for regional features of vascular trees. Eight 3D MRA acquisitions with intracranial atherosclerosis were assessed to validate this technique. Arterial tracings were validated by an experienced neuroradiologist who checked agreement at bifurcation and stenosis locations. This technique achieved 94% sensitivity and 85% positive predictive values (PPV) for bifurcations, and 85% sensitivity and PPV for stenosis. Up to 1,456 features, such as length, volume, and averaged signal intensity for each artery, as well as vascular group in each of the MRA images, could be extracted to comprehensively reflect characteristics, distribution, and connectivity of arteries. Length for the M1 segment of the middle cerebral artery extracted by this technique was compared with reviewer-measured results, and the intraclass correlation coefficient was 0.97. A semiautomated quantitative method to trace, label, and measure intracranial arteries from 3D-MRA was developed and validated. This technique can be used to facilitate quantitative intracranial vascular research, such as studying cerebrovascular adaptation to aging and disease conditions. Magn Reson Med 79:3229-3238, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  6. 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.

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

    EPA Science Inventory

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

  8. Comparison between multi-shot gradient echo EPI and balanced SSFP in unenhanced 3T MRA of thoracic aorta in healthy volunteers.

    PubMed

    Iyama, Yuji; Nakaura, Takeshi; Nagayama, Yasunori; Oda, Seitaro; Utsunomiya, Daisuke; Kidoh, Masafumi; Yuki, Hideaki; Hirata, Kenichiro; Namimoto, Tomohiro; Kitajima, Mika; Morita, Kosuke; Funama, Yoshinori; Takemura, Atsushi; Tokuyasu, Shinichi; Okuaki, Tomoyuki; Yamashita, Yasuyuki

    2017-11-01

    The purpose of this study was to compare scan time and image quality between magnetic resonance angiography (MRA) of the thoracic aorta using a multi-shot gradient echo planar imaging (MSG-EPI) and MRA using balanced steady-state free precession (b-SSFP). Healthy volunteers (n=17) underwent unenhanced thoracic aorta MRA using balanced steady-state free precession (b-SSFP) and MSG-EPI sequences on a 3T MRI. The acquisition time, total scan time, signal-to-noise ratio (SNR) of the thoracic aorta, and the coefficient of variation (CV) of thoracic aorta were compared with paired t-tests. Two radiologists independently recorded the images' contrast, noise, sharpness, artifacts, and overall quality on a 4-point scale. The acquisition time was 36.2% shorter for MSG-EPI than b-SSFP (115.5±14.4 vs 181.0±14.9s, p<0.01). The total scan time was 40.4% shorter for MSG-EPI than b-SSFP (272±78 vs 456±144s, p<0.01). There was no significant difference in mean SNR between MSG-EPI and b-SSFP scans (17.3±3.6 vs 15.2±4.3, p=0.08). The CV was significantly lower for MSG-EPI than b-SSFP (0.2±0.1 vs. 0.5±0.2, p<0.01). All qualitative scores except for image noise were significantly higher in MSG-EPI than b-SSFP scans (p<0.05). The MSG-EPI sequence is a promising technique for shortening scan time and yielding more homogenous image quality in MRA of thoracic aorta on 3T scanners compared with the b-SSFP. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. 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 (signal max ), time intervals between onset of arterial enhancement and lesion enhancement (t onset ), and time intervals between beginning of lesion enhancement and maximum percentage of lesion enhancement (t max ) 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 signal max 737 %, IQR [interquartile range] = 511 - 1182 %; median t onset 5 s, IQR = 5 - 10 s; median t max 35 s, IQR = 26 - 40 s) and without AVFs (median signal max 284 %, IQR = 177-432 %; median t onset 23 s, IQR = 15 - 30 s; median t max 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.

  10. 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.

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

    PubMed

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

    2016-01-01

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

  12. 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.

  13. 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

  14. 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

  15. 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...

  16. Improved receiver arrays and optimized parallel imaging accelerations applied to time-resolved 3D fluoroscopically tracked peripheral runoff CE-MRA.

    PubMed

    Weavers, Paul T; Borisch, Eric A; Hulshizer, Tom C; Rossman, Phillip J; Young, Phillip M; Johnson, Casey P; McKay, Jessica; Cline, Christopher C; Riederer, Stephen J

    2016-04-01

    Three-station stepping-table time-resolved 3D contrast-enhanced magnetic resonance angiography has conflicting demands in the need to limit acquisition time in proximal stations to match the speed of the advancing contrast bolus and in the distal-most station to avoid venous contamination while still providing clinically useful spatial resolution. This work describes improved receiver coil arrays which address this issue by allowing increased acceleration factors, providing increased spatial resolution per unit time. Receiver coil arrays were constructed for each station (pelvis, thigh, calf) and then integrated into a 48-element array for three-station peripheral CE-MRA. Coil element sizes and array configurations for these three stations were designed to improve SENSE-type parallel imaging taking advantage of an increase in coil count for all stations versus the previous 32 channel capability. At each station either acceleration apportionment or optimal CAIPIRINHA selection was used to choose the optimum acceleration parameters for each subject. Results were evaluated in both single- and multi-station studies. Single-station studies showed that SENSE acceleration in the thigh station could be readily increased from R=8 to R=10, allowing reduction of the frame time from 2.5 to 2.1 s to better image the typically rapidly advancing bolus at this station. Similarly, the improved coil array for the calf station permitted acceleration increase from R=8 to R=12, providing a 4.0 vs. 5.2 s frame time. Results in three-station studies suggest an improved ability to track the contrast bolus in peripheral CE-MRA. Modified receiver coil arrays and individualized parameter optimization have been used to provide improved acceleration at all stations in multi-station peripheral CE-MRA and provide high spatial resolution with frame times as short as 2.1 s. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. High-resolution, time-resolved MRA provides superior definition of lower-extremity arterial segments compared to 2D time-of-flight imaging.

    PubMed

    Thornton, F J; Du, J; Suleiman, S A; Dieter, R; Tefera, G; Pillai, K R; Korosec, F R; Mistretta, C A; Grist, T M

    2006-08-01

    To evaluate a novel time-resolved contrast-enhanced (CE) projection reconstruction (PR) magnetic resonance angiography (MRA) method for identifying potential bypass graft target vessels in patients with Class II-IV peripheral vascular disease. Twenty patients (M:F = 15:5, mean age = 58 years, range = 48-83 years), were recruited from routine MRA referrals. All imaging was performed on a 1.5 T MRI system with fast gradients (Signa LX; GE Healthcare, Waukesha, WI). Images were acquired with a novel technique that combined undersampled PR with a time-resolved acquisition to yield an MRA method with high temporal and spatial resolution. The method is called PR hyper time-resolved imaging of contrast kinetics (PR-hyperTRICKS). Quantitative and qualitative analyses were used to compare two-dimensional (2D) time-of-flight (TOF) and PR-hyperTRICKS in 13 arterial segments per lower extremity. Statistical analysis was performed with the Wilcoxon signed-rank test. Fifteen percent (77/517) of the vessels were scored as missing or nondiagnostic with 2D TOF, but were scored as diagnostic with PR-hyperTRICKS. Image quality was superior with PR-hyperTRICKS vs. 2D TOF (on a four-point scale, mean rank = 3.3 +/- 1.2 vs. 2.9 +/- 1.2, P < 0.0001). PR-hyperTRICKS produced images with high contrast-to-noise ratios (CNR) and high spatial and temporal resolution. 2D TOF images were of inferior quality due to moderate spatial resolution, inferior CNR, greater flow-related artifacts, and absence of temporal resolution. PR-hyperTRICKS provides superior preoperative assessment of lower limb ischemia compared to 2D TOF.

  18. Time-resolved contrast-enhanced MRA (TWIST) with gadofosveset trisodium in the classification of soft-tissue vascular anomalies in the head and neck in children following updated 2014 ISSVA classification: first report on systematic evaluation of MRI and TWIST in a cohort of 47 children.

    PubMed

    Higgins, L J; Koshy, J; Mitchell, S E; Weiss, C R; Carson, K A; Huisman, T A G M; Tekes, A

    2016-01-01

    To evaluate the relative accuracy of contrast-enhanced time-resolved angiography with interleaved stochastic trajectories versus conventional contrast-enhanced magnetic resonance imaging (MRI) following International Society for the Study of Vascular Anomalies updated 2014-based classification of soft-tissue vascular anomalies in the head and neck in children. Time-resolved angiography with interleaved stochastic trajectories versus conventional contrast-enhanced MRI of children with diagnosis of soft-tissue vascular anomalies in the head and neck referred for MRI between 2008 and 2014 were retrospectively reviewed. Forty-seven children (0-18 years) were evaluated. Two paediatric neuroradiologists evaluated time-resolved MRA and conventional MRI in two different sessions (30 days apart). Blood-pool endovascular MRI contrast agent gadofosveset trisodium was used. The present cohort had the following diagnoses: infantile haemangioma (n=6), venous malformation (VM; n=23), lymphatic malformation (LM; n=16), arteriovenous malformation (AVM; n=2). Time-resolved MRA alone accurately classified 38/47 (81%) and conventional MRI 42/47 (89%), respectively. Although time-resolved MRA alone is slightly superior to conventional MRI alone for diagnosis of infantile haemangioma, conventional MRI is slightly better for diagnosis of venous and LMs. Neither time-resolved MRA nor conventional MRI was sufficient for accurate diagnosis of AVM in this cohort. Conventional MRI combined with time-resolved MRA accurately classified 44/47 cases (94%). Time-resolved MRA using gadofosveset trisodium can accurately classify soft-tissue vascular anomalies in the head and neck in children. The addition of time-resolved MRA to existing conventional MRI protocols provides haemodynamic information, assisting the diagnosis of vascular anomalies in the paediatric population at one-third of the dose of other MRI contrast agents. Copyright © 2015 The Royal College of Radiologists. Published by Elsevier

  19. 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 ...

  20. 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.

  1. 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 Central

    Huang, Yi; Liu, Dexiang; Tang, Yukuan; Fan, Zhaoyang; Chen, Hanwei; Liu, Xin

    2015-01-01

    Objectives 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. Materials and Methods 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. Results 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. Conclusion 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

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    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 3MRAmore » 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) .« less

  3. Sum of top-hat transform based algorithm for vessel enhancement in MRA images

    NASA Astrophysics Data System (ADS)

    Ouazaa, Hibet-Allah; Jlassi, Hajer; Hamrouni, Kamel

    2018-04-01

    The Magnetic Resonance Angiography (MRA) is rich with information's. But, they suffer from poor contrast, illumination and noise. Thus, it is required to enhance the images. But, these significant information can be lost if improper techniques are applied. Therefore, in this paper, we propose a new method of enhancement. We applied firstly the CLAHE method to increase the contrast of the image. Then, we applied the sum of Top-Hat Transform to increase the brightness of vessels. It is performed with the structuring element oriented in different angles. The methodology is tested and evaluated on the publicly available database BRAINIX. And, we used the measurement methods MSE (Mean Square Error), PSNR (Peak Signal to Noise Ratio) and SNR (Signal to Noise Ratio) for the evaluation. The results demonstrate that the proposed method could efficiently enhance the image details and is comparable with state of the art algorithms. Hence, the proposed method could be broadly used in various applications.

  4. 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.

  5. Quantitative evaluation of high intensity signal on MIP images of carotid atherosclerotic plaques from routine TOF-MRA reveals elevated volumes of intraplaque hemorrhage and lipid rich necrotic core.

    PubMed

    Yamada, Kiyofumi; Song, Yan; Hippe, Daniel S; Sun, Jie; Dong, Li; Xu, Dongxiang; Ferguson, Marina S; Chu, Baocheng; Hatsukami, Thomas S; Chen, Min; Zhou, Cheng; Yuan, Chun

    2012-11-29

    Carotid intraplaque hemorrhage (IPH) and lipid rich necrotic core (LRNC) have been associated with accelerated plaque growth, luminal narrowing, future surface disruption and development of symptomatic events. The aim of this study was to evaluate the quantitative relationships between high intensity signals (HIS) in the plaque on TOF-MRA and IPH or LRNC volumes as measured by multicontrast weighted CMR. Seventy six patients with a suspected carotid artery stenosis or carotid plaque by ultrasonography underwent multicontrast carotid CMR. HIS presence and volume were measured from TOF-MRA MIP images while IPH and LRNC volumes were separately measured from multicontrast CMR. For detecting IPH, HIS on MIP images overall had high specificity (100.0%, 95% CI: 93.0 - 100.0%) but relatively low sensitivity (32%, 95% CI: 20.8 - 47.9%). However, the sensitivity had a significant increasing relationship with underlying IPH volume (p = 0.033) and degree of stenosis (p = 0.022). Mean IPH volume was 2.7 times larger in those with presence of HIS than in those without (142.8 ± 97.7 mm(3) vs. 53.4 ± 56.3 mm(3), p = 0.014). Similarly, mean LRNC volume was 3.4 times larger in those with HIS present (379.8 ± 203.4 mm(3) vs. 111.3 ± 122.7 mm(3), p = 0.001). There was a strong correlation between the volume of the HIS region and the IPH volume measured from multicontrast CMR (r = 0.96, p < 0.001). MIP images are easily reformatted from three minute, routine, clinical TOF sequences. High intensity signals in carotid plaque on TOF-MRA MIP images are associated with increased intraplaque hemorrhage and lipid-rich necrotic core volumes. The technique is most sensitive in patients with moderate to severe stenosis.

  6. 3.0 Tesla high spatial resolution contrast-enhanced magnetic resonance angiography (CE-MRA) of the pulmonary circulation: initial experience with a 32-channel phased array coil using a high relaxivity contrast agent.

    PubMed

    Nael, Kambiz; Fenchel, Michael; Krishnam, Mayil; Finn, J Paul; Laub, Gerhard; Ruehm, Stefan G

    2007-06-01

    To evaluate the technical feasibility of high spatial resolution contrast-enhanced magnetic resonance angiography (CE-MRA) with highly accelerated parallel acquisition at 3.0 T using a 32-channel phased array coil, and a high relaxivity contrast agent. Ten adult healthy volunteers (5 men, 5 women, aged 21-66 years) underwent high spatial resolution CE-MRA of the pulmonary circulation. Imaging was performed at 3 T using a 32-channel phase array coil. After intravenous injection of 1 mL of gadobenate dimeglumine (Gd-BOPTA) at 1.5 mL/s, a timing bolus was used to measure the transit time from the arm vein to the main pulmonary artery. Subsequently following intravenous injection of 0.1 mmol/kg of Gd-BOPTA at the same rate, isotropic high spatial resolution data sets (1 x 1 x 1 mm3) CE-MRA of the entire pulmonary circulation were acquired using a fast gradient-recalled echo sequence (TR/TE 3/1.2 milliseconds, FA 18 degrees) and highly accelerated parallel acquisition (GRAPPA x 6) during a 20-second breath hold. The presence of artifact, noise, and image quality of the pulmonary arterial segments were evaluated independently by 2 radiologists. Phantom measurements were performed to assess the signal-to-noise ratio (SNR). Statistical analysis of data was performed by using Wilcoxon rank sum test and 2-sample Student t test. The interobserver variability was tested by kappa coefficient. All studies were of diagnostic quality as determined by both observers. The pulmonary arteries were routinely identified up to fifth-order branches, with definition in the diagnostic range and excellent interobserver agreement (kappa = 0.84, 95% confidence interval 0.77-0.90). Phantom measurements showed significantly lower SNR (P < 0.01) using GRAPPA (17.3 +/- 18.8) compared with measurements without parallel acquisition (58 +/- 49.4). The described 3 T CE-MRA protocol in addition to high T1 relaxivity of Gd-BOPTA provides sufficient SNR to support highly accelerated parallel acquisition

  7. Three-dimensional contrast-enhanced magnetic resonance angiography (3-D CE-MRA) in the evaluation of hemodialysis access complications, and the condition of central veins in patients who are candidates for hemodialysis access.

    PubMed

    Paksoy, Yahya; Gormus, Niyazi; Tercan, Mehmet Akif

    2004-01-01

    Arteriovenous (AV) fistulas are crucial in patients requiring long-term hemodialysis (HD). Dysfunctions of these fistulas are the most common causes of recurrent hospitalizations. This study aimed to evaluate the feasibility, safety and usefulness of contrast-enhanced magnetic resonance angiography (CE-MRA) in the evaluation of HD fistulas complications, and the condition of the central veins before HD access. This study comprised 30 consecutive patients (15 females, 15 males; age range 25-66 yrs, mean +/- SD 51.2 +/- 9.9 yrs). Of 30 patients, 26 had native AV fistulas and the remaining four patients, who had a history of previous subclavian vein catheterization, were candidates for HD fistulas. Nine patients had a radiocephalic fistula, 15 had a brachiobasilic fistula, one had a saphenous vein graft, and one had brachiobasilic vein transposition. To observe the fistula complications in these cases, three-dimensional (3-D) CE-MRA using gadolinium was performed. The results were considered normal in three patients (10%), who were candidates for AV fistula construction; one patient had central vein occlusion due to previous catheterization. Thirteen patients (43.3%) had venous stenosis or occlusion; three of them (10%) had low CE arteries distal to fistula region, leading to ischemic complications, and six (20%) had stenosis at the fistula region. Seven patients (23.3%) had venous pseudoaneurysms, whereas two of them had both pseudoaneurysms and fistula region stenosis, and one had both venous stenosis and pseudoaneurysm. There were no adverse or allergic-like reactions or heat and taste sensations observed in our series. 3-D CE-MRA is a useful, safe and a practical imaging modality in complicated fistula diagnosis with fewer complications and side-effects in comparison to fistulography.

  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. 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

  10. 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

  11. Who Loves Prescriptivism and Why? Some Aspects of Language Correctness in Latvia

    ERIC Educational Resources Information Center

    Strelevica-Ošina, Dace

    2016-01-01

    Taking into account the crosscultural differences in prescriptive attitudes in various linguistic communities, a theory of three types of prescriptivism--human-oriented, language-oriented, and error-oriented prescriptivism--has been offered [Strelevica-Ošina, Dace. [2011] 2012. "Kapec mes gribam, lai valoda ir pareiza? Ieskats preskriptivisma…

  12. Biochemical and functional characterization of MRA-1571 of Mycobacterium tuberculosis H37Ra and effect of its down-regulation on survival in macrophages

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sharma, Rishabh; Keshari, Deepa; Singh, Kumar Sachin

    Amino acid biosynthesis has emerged as a source of new drug targets as many bacterial strains auxotrophic for amino acids fail to proliferate under in vivo conditions. Branch chain amino acids (BCAAs) are important for Mycobacterium tuberculosis (Mtb) survival and strains deficient in their biosynthesis were attenuated for growth in mice. Threonine dehydratase (IlvA) is a pyridoxal-5-phosphate (PLP) dependent enzyme that catalyzes the first step in isoleucine biosynthesis. The MRA-1571 of Mycobacterium tuberculosis H37Ra (Mtb-Ra), annotated to be coding for IlvA, was cloned, expressed and purified. Purified protein was subsequently used for developing enzyme assay and to study its biochemical properties.more » Also, E. coli BL21 (DE3) IlvA knockout (E. coli-ΔilvA) was developed and genetically complemented with Mtb-Ra ilvA expression construct (pET32a-ilvA) to make complemented E. coli strain (E. coli-ΔilvA + pET32a-ilvA). The E. coli-ΔilvA showed growth failure in minimal medium but growth restoration was observed in E. coli-ΔilvA + pET32a-ilvA. E. coli-ΔilvA growth was also restored in the presence of isoleucine. The IlvA localization studies detected its distribution in cell wall and membrane fractions with relatively minor presence in cytosolic fraction. Maximum IlvA expression was observed at 72 h in wild-type (WT) Mtb-Ra infecting macrophages. Also, Mtb-Ra IlvA knockdown (KD) showed reduced survival in macrophages compared to WT and complemented strain (KDC). - Highlights: • Mtb-Ra gene MRA-1571 codes for a functional threonine dehydratase (IlvA). • IlvA is pyridoxal 5’-phosphate dependent and is inhibited by isoleucine. • E. coli IlvA knockout growth can be supplemented by isoleucine or by Mtb-Ra IlvA. • The enzyme is primarily localized in cell wall and membrane fractions. • IlvA knockdown Mtb-Ra shows reduced growth in macrophages.« less

  13. 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

  14. 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 Central

    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

    Purpose 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). Materials and Methods 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. Results 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. Conclusion 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. PMID:27861626

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

    PubMed Central

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

    2016-01-01

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

  16. 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.

  17. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nielsen, Yousef W., E-mail: yujwni01@heh.regionh.d; Eiberg, Jonas P.; Logager, Vibeke B.

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

  18. 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.

  19. 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.

  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. True rate of mineralocorticoid receptor antagonists-related hyperkalemia in placebo-controlled trials: A meta-analysis.

    PubMed

    Vukadinović, Davor; Lavall, Daniel; Vukadinović, Aleksandra Nikolovska; Pitt, Bertram; Wagenpfeil, Stefan; Böhm, Michael

    2017-06-01

    Mineralocorticoid receptor antagonists (MRA) improve survival in heart failure with reduced ejection fraction but are often underused, mostly due to concerns of hyperkalemia. Because hyperkalemia occurs also on placebo, we aimed to determine the truly MRA-related rate of hyperkalemia. We performed a meta-analysis including randomized, placebo-controlled trials reporting hyperkalemia on MRAs in patients after myocardial infarction or with chronic heart failure. We evaluated the truly MRA-related rate of hyperkalemia that represents hyperkalemia on MRA, corrected for hyperkalemia on placebo (Pla), according to the equation: True MRA (%)=(MRA (%) - Pla (%))/MRA (%). A total number of 16,065 patients from 7 trials were analyzed. Hyperkalemia was more frequently observed on MRA (9.3%) vs placebo (4.3%) (risk ratio 2.17, 95% CI 1.92-2.45, P<.0001). Truly MRA-related hyperkalemia was 54%, whereas 46% were non-MRA related. In trials using eplerenone, hyperkalemia was documented in 5.0% on eplerenone and in 2.6% on placebo (P<.0001). In spironolactone trials, hyperkalemia was documented in 17.5% and in 7.5% of patients on placebo (P=.0001). Hypokalemia occurred less frequently in patients on MRA (9.3%) compared with placebo (14.8%) (risk ratio 0.58, CI 0.47-0.72, P<.0001). This meta-analysis shows that in clinical trials, 54% of hyperkalemia cases were specifically related to the MRA treatment and 46% to other reasons. Therefore, non-MRA-related rises in potassium levels might be underestimated and should be rigorously explored before cessation of the evidence-based therapy with MRAs. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Noncontrast-enhanced magnetic resonance renal angiography using a repetitive artery and venous labelling technique at 3 T: comparison with contrast-enhanced magnetic resonance angiography in subjects with normal renal function.

    PubMed

    Park, Sung Yoon; Kim, Chan Kyo; Kim, EunJu; Park, Byung Kwan

    2015-02-01

    To investigate the feasibility of noncontrast-enhanced MR angiography (NC-MRA) using the repetitive artery and venous labelling (RAVEL) technique to evaluate renal arteries compared to contrast-enhanced MR angiography (CE-MRA). Twenty-five subjects with normal renal function underwent NC-MRA using a RAVEL technique and CE-MRA at 3 T. Two independent readers analysed the MRA images. Image quality, number of renal arteries, presence or absence of an early branching vessel, and diameter of the main renal arteries were evaluated. The overall image quality of NC-MRA was fair or greater in 88% of right and 92% of left renal arteries, while it was 96% in both sides with CE-MRA. On NC-MRA, the number of renal arteries in all subjects was perfectly predicted by both readers. Sensitivity and specificity for predicting early branching vessels were 82% and 100% for reader 1 and 82% and 95% for reader 2. Inter-modality agreement for comparing the diameters of main renal arteries was good or excellent at all segments for both readers. Inter-reader agreement was moderate or good at all segments except at the right distal segment on NC-MRA. NC-MRA with the RAVEL technique at 3 T may have comparable diagnostic feasibility for evaluating renal arteries compared to CE-MRA. • Accurate pre-treatment evaluation of renal artery anatomy helps clinical decision-making. • NC-MRA using RAVEL offers acceptable imaging quality for renal artery evaluation. • The 3 T RAVEL technique provides excellent diagnostic performance for renal artery evaluation. • The 3 T RAVEL technique may be an alternative to contrast-enhanced MRA.

  3. Mineralocorticoid Receptor Antagonism in Patients With Atrial Fibrillation: Findings From the ORBIT-AF (Outcomes Registry for Better Informed Treatment of Atrial Fibrillation) Registry.

    PubMed

    Fudim, Marat; Liu, Peter R; Shrader, Peter; Blanco, Rosalia G; Allen, Larry A; Fonarow, Gregg C; Gersh, Bernard J; Kowey, Peter R; Mahaffey, Kenneth W; Hylek, Elaine; Go, Alan S; Thomas, Laine; Peterson, Eric D; Piccini, Jonathan P

    2018-04-13

    Mineralocorticoid receptor antagonist (MRA) therapy may be beneficial to patients with atrial fibrillation (AF), but little is known about their use in patients with AF and subsequent outcomes. In order to better understand MRA use and subsequent outcomes, we performed a retrospective cohort study of the contemporary ORBIT-AF (Outcomes Registry for Better Informed Treatment of Atrial Fibrillation) registry. AF progression and cardiovascular outcomes were compared using propensity-matched Cox proportional hazards modeling according to MRA use at baseline and new MRA use at follow-up versus patients with no MRA use. Among 7012 patients with nonpermanent AF, 320 patients were taking MRA at enrollment, and 416 patients initiated MRA use during follow-up. The mean patient age was 72.5 years, 56.3% were men, and 70.4% had paroxysmal AF. Among all patients taking MRAs, 434 (59.0%) had heart failure, 655 (89.0%) had hypertension, and 380 (51.6%) had both. After adjustment, new MRA use was not associated with reduced AF progression (hazard ratio, 1.18; 95% confidence interval, 0.88-1.58; P =0.27) but showed a trend towards lower risk of stroke, transient ischemic attack, or systemic embolism (hazard ratio, 0.17; 95% confidence interval, 0.02-1.23; P =0.08). Results were similar for a comparison of new MRA users and baseline MRA users compared with nonusers. In community-based outpatients with AF, the majority of MRA use was for heart failure and hypertension. MRA use also trended towards lower adjusted stroke risk. Future studies should test the hypothesis that MRA use may decrease the risk of stroke in patients with AF. © 2018 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

  4. 50 CFR 679.81 - Rockfish Program annual harvester and processor privileges.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... amount (MRA) limits—(1) Rockfish cooperative. A vessel assigned to a rockfish cooperative and fishing... this part. (6) Maximum retainable amounts (MRA). (i) The MRA for an incidental catch species for..., shortraker and rougheye rockfish are incidental catch species and are limited to an aggregate MRA of 2.0...

  5. 77 FR 23751 - National Register of Historic Places; Notification of Pending Nominations and Related Actions

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-20

    ..., Clarissa C., Library--Blue Ribbon News Building, (Davenport MRA) 528 Brady St., Davenport, 83002415 Lend-A-Hand Club, (Davenport MRA) 105 S. Main St., Davenport, 84001459 Petersen's, J. H. C., Sons Wholesale Building, (Davenport MRA) 122- 124 W. River Dr., Davenport, 83002484 Schauder Hotel, (Davenport MRA) 126 W...

  6. DOE Office of Scientific and Technical Information (OSTI.GOV)

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

    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 themore » 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.« less

  7. CERT Resilience Management Model - Mail-Specific Process Areas: Mail Revenue Assurance (Version 1.0)

    DTIC Science & Technology

    2014-08-01

    Revenue Assurance ( MRA ), Mail Transportation (MT), and Mail Delivery (MD)—were accepted by the USPIS, as well as an initial draft of the MRA PA...versions of two complete PAs, MI [Allen 2014b] and MRA , were accepted by the USPIS. Following this initial effort, the USPIS asked CERT to extend the...Revenue Assurance ( MRA ) is to ensure that the USPS is compensated for all mail that is accepted, transported, and delivered. Outline MRA:SG1

  8. Combining stereotactic angiography and 3D time-of-flight magnetic resonance angiography in treatment planning for arteriovenous malformation radiosurgery.

    PubMed

    Bednarz, G; Downes, B; Werner-Wasik, M; Rosenwasser, R H

    2000-03-15

    This study was initiated to evaluate the advantages of using three-dimensional time-of-flight magnetic resonance angiography (3D TOF MRA), as an adjuvant to conventional stereotactic angiography, in obtaining three-dimensional information about an arteriovenous malformation (AVM) nidus and in optimizing radiosurgical treatment plans. Following angiography, contrast-enhanced MRI and MRA studies were obtained in 22 consecutive patients undergoing Gamma Knife radiosurgery for AVM. A treatment plan was designed, based on the angiograms and modified as necessary, using the information provided by MRA. The quantitative analysis involved calculation of the ratio of the treated volume to the MRA nidus volume (the tissue volume ratio [TVR]) for the initial and final treatment plans. In 12 cases (55%), the initial treatment plans were modified after including the MRA information in the treatment planning process. The mean TVR for the angiogram-based plans was 1.63 (range 1.17-2.17). The mean coverage of the MRA nidus by the angiogram-based plans was 93% (range 73-99%). The mean MRA nidus volume was 2.4 cc (range 0. 6-5.3 cc). The MRA-based modifications resulted in increased conformity with the mean TVR of 1.46 (range 1.20-1.74). These modifications were caused by MRA revealing irregular nidi and/or vascular components superimposed on the angiographic projections of the nidi. In a number of cases, the information from MRA was essential in defining the nidus when the projections of the angiographic outlines showed different superior and/or inferior extent of the nidus. In two cases, MRA revealed irregular nidi, correlating well with the angiograms and showed that the angiographically acceptable plans undertreated 27% of the MRA nidus in one case and 18% of the nidus in the other case. In the remaining 10 cases (45%), both MRI and MRA failed to detect the nidus due to surgical clip artifacts and the presence of embolizing glue. The 3D TOF MRA provided information on irregular

  9. 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

  10. 76 FR 46202 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-02

    ... * 4500-MRA ** 6400-MOCA ** 7000-GNSS MEA * Wigan, NY FIX Barnes, MA ** 10000 VORTAC. * 4500-MRA ** 4900... Airway V20 Is Amended To Read in Part Jorda, HI FIX * Fires, HI FIX......... * 13000-MRA NW BND ** 10000 ** 1300-MOCA SE BND ** 13000 * Fires, HI FIX * Hokla, HI FIX......... ** 13000 * 13000-MRA ** 1300-MOCA...

  11. 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.

  12. 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.

  13. Comparison of vessel enhancement algorithms applied to time-of-flight MRA images for cerebrovascular segmentation.

    PubMed

    Phellan, Renzo; Forkert, Nils D

    2017-11-01

    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 flux (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 5 healthy subjects and 10 patients with an arteriovenous malformation. Additionally, five synthetic angiographic datasets with corresponding ground truth segmentation were generated with three different noise levels (low, medium, and 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 nonenhanced 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

  14. 75 FR 24790 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-06

    ... Read in Part *Italy, WV FIX REACH, WV FIX 4000 *4000-MRA Reach, WV FIX ELKINS, WV VORTAC....... 4400...-MOCA Cleep, TX FIX *Legge, TX FIX 3100 *3000-MRA Napoleon, MO VORTAC LAMONI, IA VORTAC....... 2900 Sec... in Part Sacky, WV FIX *Julea, WV FIX 3000 *5000-MRA *Julea, WV FIX Benzo, WV FIX 3300 *5000-MRA Benzo...

  15. 78 FR 44874 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-25

    ... FIX 2300 *4000--MRA *ROMAR, MS FIX MAGNOLIA, MS VORTAC..... 2300 *4000--MRA MAGNOLIA, MS VORTAC SIDON... Amended To Read in Part *FLATT, TX FIX SHALO, TX FIX 5200 *8000--MRA Sec. 95.6018 VOR Federal Airway V18... Part *WRACK, LA FIX NATCHEZ, MS VOR/DME..... **3500 *4000--MRA **2200--MOCA **2200--GNSS MEA Sec. 95...

  16. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Klein, W.M.; Schlejen, P.M.; Eikelboom, B.C.

    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 Amore » 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.« less

  17. Comparison of Power Versus Manual Injection in Bolus Shape and Image Quality on Contrast-Enhanced Magnetic Resonance Angiography: An Experimental Study in a Swine Model.

    PubMed

    Tsuboyama, Takahiro; Jost, Gregor; Pietsch, Hubertus; Tomiyama, Noriyuki

    2017-09-01

    The aim of this study was to compare power versus manual injection in bolus shape and image quality on contrast-enhanced magnetic resonance angiography (CE-MRA). Three types of CE-MRA (head-neck 3-dimensional [3D] MRA with a test-bolus technique, thoracic-abdominal 3D MRA with a bolus-tracking technique, and thoracic-abdominal time-resolved 4-dimensional [4D] MRA) were performed after power and manual injection of gadobutrol (0.1 mmol/kg) at 2 mL/s in 12 pigs (6 sets of power and manual injections for each type of CE-MRA). For the quantitative analysis, the signal-to-noise ratio was measured on ascending aorta, descending aorta, brachiocephalic trunk, common carotid artery, and external carotid artery on the 6 sets of head-neck 3D MRA, and on ascending aorta, descending aorta, brachiocephalic trunk, abdominal aorta, celiac trunk, and renal artery on the 6 sets of thoracic-abdominal 3D MRA. Bolus shapes were evaluated on the 6 sets each of test-bolus scans and 4D MRA. For the qualitative analysis, arterial enhancement, superimposition of nontargeted enhancement, and overall image quality were evaluated on 3D MRA. Visibility of bolus transition was assessed on 4D MRA. Intraindividual comparison between power and manual injection was made by paired t test, Wilcoxon rank sum test, and analysis of variance by ranks. Signal-to-noise ratio on 3D MRA was statistically higher with power injection than with manual injection (P < 0.001). Bolus shapes (test-bolus, 4D MRA) were represented by a characteristic standard bolus curve (sharp first-pass peak followed by a gentle recirculation peak) in all the 12 scans with power injection, but only in 1 of the 12 scans with manual injection. Standard deviations of time-to-peak enhancement were smaller in power injection than in manual injection. Qualitatively, although both injection methods achieved diagnostic quality on 3D MRA, power injection exhibited significantly higher image quality than manual injection (P = 0.001) due to

  18. 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

  19. 78 FR 20783 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-08

    ... FIX BANDR, WA FIX E BND *8400 W BND *7700 *7700--GNSS MEA BANDR, WA FIX *BEEZR, WA FIX 8400 *9000--MRA... *3700--MRA *6200--MCA WACCO, MO FIX, SW BND **3100--MOCA **4000--GNSS MEA *WACCO, MO FIX *QUALM, MO FIX **3700 *3700--MRA **3000--MOCA QUALM, MO FIX *MIRTH, MO FIX 3000 *3700--MRA *MIRTH, MO FIX SPRINGFIELD...

  20. Identification of peripheral vessels in oral and maxillofacial regions on magnetic resonance angiography obtained using a balanced steady-state free-precession sequence with a time-spatial labeling inversion pulse and using fresh blood imaging.

    PubMed

    Oda, Masafumi; Tanaka, Tatsurou; Yamashita, Yoshihiro; Kito, Shinji; Wakasugi-Sato, Nao; Matsumoto-Takeda, Shinobu; Nishimura, Shun; Habu, Manabu; Kodama, Masaaki; Uehara, Masataka; Kaneuji, Tsuyoshi; Kokuryo, Shinya; Miyamoto, Ikuya; Yoshiga, Daigo; Seta, Yuji; Tominaga, Kazuhiro; Yoshioka, Izumi; Morimoto, Yasuhiro

    2013-12-01

    To elucidate the characteristics of visualizing thin main peripheral vessels in oral and maxillofacial regions of 3-dimensional magnetic resonance angiography (MRA) using a balanced steady-state free-precession (SSFP) sequence with a time-spatial labeling inversion pulse (time-SLIP) and using fresh blood imaging (FBI). The conspicuity of blood vessels and the characteristics on MRA using SSFP with a time-SLIP was compared with those on MRA using FBI in 20 healthy participants. The conspicuity of the main peripheral arteries was significantly higher on MRA using SSFP with a time-SLIP than on MRA using FBI. MRA scans using SSFP were obtained in all participants, and scans using FBI were obtained in 16 of 20 participants. An electrocardiogram was unnecessary when using SSFP but was necessary when using FBI. MRA obtained using SSFP with a time-SLIP is a useful technique to visualize thin main peripheral arteries in the oral and maxillofacial regions without contrast medium. Copyright © 2013 Elsevier Inc. All rights reserved.

  1. The costs and effects of contrast-enhanced magnetic resonance angiography and digital substraction angiography on quality of life in patients with peripheral arterial disease.

    PubMed

    Bosma, Jan; Dijksman, Lea M; Lam, Kayan; Wisselink, Willem; van Swijndregt, Alexander D Montauban; Vahl, Anco

    2014-04-01

    Contrast-enhanced magnetic resonance angiography (MRA) and intra-arterial digital subtraction angiography (DSA) both have a high diagnostic performance in the imaging of peripheral arterial occlusive disease (PAOD). However, little is known about the effects of initial, preoperative imaging using MRA or DSA on quality of life (QoL) in relation to costs (cost-utility). To compare cost-utility of treatment strategies using either MRA or DSA as the principal imaging tool, related to QoL, in patients with PAOD. In a prospective subgroup analysis of patients randomized between MRA and DSA (n = 79) for preoperative imaging, QoL questionnaires (SF-36) were obtained at randomization and at 4-month follow-up. Cost-effectiveness from hospital perspective was subsequently compared between groups and the difference in gained or lost QoL per € spent assessed using bootstrap analysis. No difference in quality of life was found. A treatment trajectory employing MRA as the principal imaging modality was almost 20% cheaper, leading to a better cost-utility ratio in favor of MRA. A treatment plan for peripheral arterial occlusive disease employing MRA versus DSA as the principal imaging modality yields a better cost/QoL ratio for MRA.

  2. Prospective study comparing three-dimensional computed tomography and magnetic resonance imaging for evaluating the renal vascular anatomy in potential living renal donors.

    PubMed

    Bhatti, Aftab A; Chugtai, Aamir; Haslam, Philip; Talbot, David; Rix, David A; Soomro, Naeem A

    2005-11-01

    To prospectively compare the accuracy of multislice spiral computed tomographic angiography (CTA) and magnetic resonance angiography (MRA) in evaluating the renal vascular anatomy in potential living renal donors. Thirty-one donors underwent multislice spiral CTA and gadolinium-enhanced MRA. In addition to axial images, multiplanar reconstruction and maximum intensity projections were used to display the renal vascular anatomy. Twenty-four donors had a left laparoscopic donor nephrectomy (LDN), whereas seven had right open donor nephrectomy (ODN); LDN was only considered if the renal vascular anatomy was favourable on the left. CTA and MRA images were analysed by two radiologists independently. The radiological and surgical findings were correlated after the surgery. CTA showed 33 arteries and 32 veins (100% sensitivity) whereas MRA showed 32 arteries and 31 veins (97% sensitivity). CTA detected all five accessory renal arteries whereas MRA only detected one. CTA also identified all three accessory renal veins whereas MRA identified two. CTA had a sensitivity of 97% and 47% for left lumbar and left gonadal veins, whereas MRA had a sensitivity of 74% and 46%, respectively. Multislice spiral CTA with three-dimensional reconstruction was more accurate than MRA for both renal arterial and venous anatomy.

  3. Comparison of 7T and 3T MRI in patients with moyamoya disease.

    PubMed

    Oh, Byeong Ho; Moon, Hyeong Cheol; Baek, Hyeon Man; Lee, Youn Joo; Kim, Sang Woo; Jeon, Young Jai; Lee, Gun Seok; Kim, Hong Rae; Choi, Jai Ho; Min, Kyung Soo; Lee, Mou Seop; Kim, Young Gyu; Kim, Dong Ho; Kim, Won Seop; Park, Young Seok

    2017-04-01

    Magnetic resonance imaging and magnetic resonance angiography (MRI/MRA) are widely used for evaluating the moyamoya disease (MMD). This study compared the diagnostic accuracy of 7Tesla (T) and 3T MRI/MRA in MMD. In this case control study, 12 patients [median age: 34years; range (10-66years)] with MMD and 12 healthy controls [median age: 25years; range (22-59years)] underwent both 7T and 3T MRI/MRA. To evaluate the accuracy of MRI/MRA in MMD, five criteria were compared between imaging systems of 7T and 3T: Suzuki grading system, internal carotid artery (ICA) diameter, ivy sign, flow void of the basal ganglia on T2-weighted images, and high signal intensity areas of the basal ganglia on time-of-flight (TOF) source images. No difference was observed between 7T and 3T MRI/MRA in Suzuki stage, ICA diameter, and ivy sign score; while, 7T MRI/MRA showed a higher detection rate in the flow void on T2-weighted images and TOF source images (p<0.001). Receiver operating characteristic curves of both T2 and TOF criteria showed that 7T MRI/MRA had higher sensitivity and specificity than 3T MRI/MRA. Our findings indicate that 7T MRI/MRA is superior to 3T MRI/MRA for the diagnosis of MMD in point of detecting the flow void in basal ganglia by T2-weighted and TOF images. Copyright © 2016. Published by Elsevier Inc.

  4. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Aoyama, Hidefumi; Shirato, Hiroki; Katoh, Norio

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

  5. 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.

  6. 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.

  7. Evaluation of the vascular anatomy in potential living kidney donors with gadolinium-enhanced magnetic resonance angiography: comparison with digital subtraction angiography and intraoperative findings.

    PubMed

    Asgari, Majid A; Dadkhah, Farid; Ghadian, Ali R; Razzaghi, Mohammad R; Noorbala, Mohammad H; Amini, Erfan

    2011-01-01

    X-ray contrast arteriography has traditionally been used for pre-operative evaluation in living kidney donors. However, magnetic resonance angiography (MRA) offers a non-invasive alternative, which has been considered to be less accurate. This study was performed to determine whether MRA in the pre-operative investigation of living kidney donors provides sufficient information. From December 2005 to December 2007, 173 potential live donors were evaluated in this study. Donors performed digital subtraction angiography (DSA) and those with one or more accessory arteries at least on one side recruited for further evaluation with three-dimensional gadolinium-enhanced MRA. A total of 30 donors constituted the study population. When compared with DSA as the reference method, MRA detected 20 of 36 renal accessory arteries which indicates a sensitivity of 55.6%. The difference between MRA and DSA in identifying accessory renal arteries was significant (p-value <0.001). Considering intraoperative findings as the standard of reference, MRA depicted correctly four of six (66.7%) accessory arteries on the transplanted kidneys. MRA has the advantage of avoiding exposure to ionizing radiation and is non-invasive. These are important considerations in pre-operative evaluation of a generally healthy donor population. However, MRA provides suboptimal accuracy in detecting small accessory arteries. © 2010 John Wiley & Sons A/S.

  8. Clinical utility of time-resolved imaging of contrast kinetics (TRICKS) magnetic resonance angiography for infrageniculate arterial occlusive disease.

    PubMed

    Mell, Matthew; Tefera, Girma; Thornton, Frank; Siepman, David; Turnipseed, William

    2007-03-01

    The diagnostic accuracy of magnetic resonance angiography (MRA) in the infrapopliteal arterial segment is not well defined. This study evaluated the clinical utility and diagnostic accuracy of time-resolved imaging of contrast kinetics (TRICKS) MRA compared with digital subtraction contrast angiography (DSA) in planning for percutaneous interventions of popliteal and infrapopliteal arterial occlusive disease. Patients who underwent percutaneous lower extremity interventions for popliteal or tibial occlusive disease were identified for this study. Preprocedural TRICKS MRA was performed with 1.5 Tesla (GE Healthcare, Waukesha, Wis) magnetic resonance imaging scanners with a flexible peripheral vascular coil, using the TRICKS technique with gadodiamide injection. DSA was performed using standard techniques in angiography suite with a 15-inch image intensifier. DSA was considered the gold standard. The MRA and DSA were then evaluated in a blinded fashion by a radiologist and a vascular surgeon. The popliteal artery and tibioperoneal trunk were evaluated separately, and the tibial arteries were divided into proximal, mid, and distal segments. Each segment was interpreted as normal (0% to 49% stenosis), stenotic (50% to 99% stenosis), or occluded (100%). Lesion morphology was classified according to the TransAtlantic Inter-Society Consensus (TASC). We calculated concordance between the imaging studies and the sensitivity and specificity of MRA. The clinical utility of MRA was also assessed in terms of identifying arterial access site as well as predicting technical success of the percutaneous treatment. Comparisons were done on 150 arterial segments in 30 limbs of 27 patients. When evaluated by TASC classification, TRICKS MRA correlated with DSA in 83% of the popliteal and in 88% of the infrapopliteal segments. MRA correctly identified significant disease of the popliteal artery with a sensitivity of 94% and a specificity of 92%, and of the tibial arteries with a

  9. Assessment of craniospinal arteriovenous malformations at 3T with highly temporally and highly spatially resolved contrast-enhanced MR angiography.

    PubMed

    Saleh, R S; Lohan, D G; Villablanca, J P; Duckwiler, G; Kee, S T; Finn, J P

    2008-05-01

    Patients with arteriovenous malformation (AVM) are known to have an elevated risk of complications with conventional catheter angiography (CCA) but nonetheless require monitoring of hemodynamics. Thus, we aimed to evaluate both anatomy and hemodynamics in patients with AVM noninvasively by using contrast-enhanced MR angiography (CE-MRA) at 3T and to compare the results with CCA. Institutional review board approval and informed consent were obtained for this Health Insurance Portability and Accountability Act-compliant study. Twenty control subjects without vascular malformation (6 men, 18-70 years of age) and 10 patients with AVMs (6 men, 20-74 years of age) underwent supra-aortic time-resolved and high-spatial-resolution CE-MRA at 3T. Large-field-of-view coronal acquisitions extending from the root of the aorta to the cranial vertex were obtained for both MRA techniques. Image quality was assessed by 2 specialized radiologists by using a 4-point scale. AVM characteristics and nidus size were evaluated by using both CE-MRA and CCA in all patients. In patients, 96.6% (319/330) of arterial segments on high-spatial-resolution MRA and 87.7% (272/310) of arterial segments on time-resolved MRA were graded excellent/good. MRA showed 100% specificity for detecting feeding arteries and venous drainage (n = 8) and complete obliteration of the AVM in 2 cases (concordance with CCA). Nidus diameters measured by both MRA and CCA resulted in a very strong correlation (r = 0.99) with a mild overestimation by MRA (0.10 cm by using the Bland-Altman plot). By combining highly temporally resolved and highly spatially resolved MRA at 3T as complementary studies, one can assess vascular anatomy and hemodynamics noninvasively in patients with AVM.

  10. 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.

  11. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

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

  13. 47 CFR 68.162 - Requirements for Telecommunication Certification Bodies.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... effective bilateral or multilateral mutual recognition agreement or arrangement (MRA) to which the United States is a party, the Commission may limit or withdraw its recognition of a TCB designated by an MRA... necessary, concerning any disputes arising under an MRA for compliance with under the Telecommunications...

  14. 50 CFR 679.81 - Rockfish Program annual harvester privileges.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...) Maximum retainable amount (MRA) limits—(1) Rockfish cooperative. A vessel assigned to a rockfish... those species as established in Table 10 to this part. (4) Maximum retainable amount (MRA) calculation and limits—catcher vessels. (i) The MRA for an incidental catch species for vessels fishing under the...

  15. 47 CFR 68.162 - Requirements for Telecommunication Certification Bodies.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... effective bilateral or multilateral mutual recognition agreement or arrangement (MRA) to which the United States is a party, the Commission may limit or withdraw its recognition of a TCB designated by an MRA... necessary, concerning any disputes arising under an MRA for compliance with under the Telecommunications...

  16. 76 FR 22030 - Third Party Testing for Certain Children's Products; Toddler Beds: Requirements for Accreditation...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-20

    ... Laboratory Accreditation Cooperation--Mutual Recognition Arrangement (ILAC-MRA), and the scope of the... and content of the ILAC-MRA approach and of the requirements of the ISO/IEC 17025:2005 laboratory... this document, it must be accredited by an ILAC-MRA signatory accrediting body, and the accreditation...

  17. 50 CFR 679.81 - Rockfish Program annual harvester privileges.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...) Maximum retainable amount (MRA) limits—(1) Rockfish cooperative. A vessel assigned to a rockfish... those species as established in Table 10 to this part. (4) Maximum retainable amount (MRA) calculation and limits—catcher vessels. (i) The MRA for an incidental catch species for vessels fishing under the...

  18. 47 CFR 68.162 - Requirements for Telecommunication Certification Bodies.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... effective bilateral or multilateral mutual recognition agreement or arrangement (MRA) to which the United States is a party, the Commission may limit or withdraw its recognition of a TCB designated by an MRA... necessary, concerning any disputes arising under an MRA for compliance with under the Telecommunications...

  19. 50 CFR 679.81 - Rockfish Program annual harvester privileges.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...) Maximum retainable amount (MRA) limits—(1) Rockfish cooperative. A vessel assigned to a rockfish... those species as established in Table 10 to this part. (4) Maximum retainable amount (MRA) calculation and limits—catcher vessels. (i) The MRA for an incidental catch species for vessels fishing under the...

  20. 75 FR 76708 - Extension of the Date by Which Youth All-Terrain Vehicles Must Be Tested and Certified

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-09

    ... Cooperation-Mutual Recognition Arrangement (``ILAC/MRA'') signatory. For firewalled conformity assessment... is a signatory to the ILAC/MRA, a prerequisite for such conformity assessment bodies to be accepted... assessment bodies that have the requisite accreditation by an ILAC-MRA signatory to test for conformity to 16...

  1. DOE Office of Scientific and Technical Information (OSTI.GOV)

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

    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 amore » 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.« less

  2. 47 CFR 2.962 - Requirements for Telecommunication Certification Bodies.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... effective bilateral or multilateral mutual recognition agreement or arrangement (MRA) to which the United States is a party, the Commission may limit or withdraw its recognition of a TCB designated by an MRA... necessary, concerning any disputes arising under an MRA for compliance with the Telecommunications Trade Act...

  3. 47 CFR 2.962 - Requirements for Telecommunication Certification Bodies.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... effective bilateral or multilateral mutual recognition agreement or arrangement (MRA) to which the United States is a party, the Commission may limit or withdraw its recognition of a TCB designated by an MRA... necessary, concerning any disputes arising under an MRA for compliance with the Telecommunications Trade Act...

  4. 47 CFR 2.962 - Requirements for Telecommunication Certification Bodies.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... effective bilateral or multilateral mutual recognition agreement or arrangement (MRA) to which the United States is a party, the Commission may limit or withdraw its recognition of a TCB designated by an MRA... necessary, concerning any disputes arising under an MRA for compliance with the Telecommunications Trade Act...

  5. 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

  6. CT versus MR Techniques in the Detection of Cervical Artery Dissection.

    PubMed

    Hanning, Uta; Sporns, Peter B; Schmiedel, Meilin; Ringelstein, Erich B; Heindel, Walter; Wiendl, Heinz; Niederstadt, Thomas; Dittrich, Ralf

    2017-11-01

    Spontaneous cervical artery dissection (sCAD) is an important etiology of juvenile stroke. The gold standard for the diagnosis of sCAD is convential angiography. However, magnetic resonance imaging (MRI)/MR angiography (MRA) and computed tomography (CT)/CT angiography (CTA) are frequently used alternatives. New developments such as multislice CT/CTA have enabled routine acquisition of thinner sections with rapid imaging times. The goal of this study was to compare the capability of recent developed 128-slice CT/CTA to MRI/MRA to detect radiologic features of sCAD. Retrospective review of patients with suspected sCAD (n = 188) in a database of our Stroke center (2008-2014), who underwent CT/CTA and MRI/MRA on initial clinical work-up. A control group of 26 patients was added. All Images were evaluated concerning specific and sensitive radiological features for dissection by two experienced neuroradiologists. Imaging features were compared between the two modalities. Forty patients with 43 dissected arteries received both modalities (29 internal carotid arteries [ICAs] and 14 vertebral arteries [VAs]). All CADs were identified in CT/CTA and MRI/MRA. The features intimal flap, stenosis, and lumen irregularity appeared in both modalities. One high-grade stenosis was identified by CT/CTA that was expected occluded on MRI/MRA. Two MRI/MRA-confirmed pseudoaneurysms were missed by CT/CTA. None of the controls evidenced specific imaging signs for dissection. CT/CTA is a reliable and better available alternative to MRI/MRA for diagnosis of sCAD. CT/CTA should be used to complement MRI/MRA in cases where MRI/MRA suggests occlusion. Copyright © 2017 by the American Society of Neuroimaging.

  7. Gadolinium-enhanced versus time-of-flight magnetic resonance angiography: what is the benefit of contrast enhancement in evaluating carotid stenosis?

    PubMed

    Muhs, Bart E; Gagne, Paul; Wagener, Jael; Baker, Jessica; Ortega, Marta Ramirez; Adelman, Mark A; Cayne, Neal S; Rockman, Caron B; Maldonado, Thomas

    2005-11-01

    Accurate patient selection based on preoperative imaging is imperative to good risk reduction in patients undergoing carotid endarterectomy (CEA). The goal of this study was to assess the accuracy of gadolinium-enhanced magnetic resonance angiography (GE MRA) versus time-of-flight (TOF) MRA in the work-up of patients undergoing CEA. Patients undergoing CEA between 1999 and 2001 were identified from a prospectively maintained institutional database. GE or TOF MRA was obtained on extracranial carotid arteries (n = 319) in patients undergoing CEA. Stenosis on MRA images was graded as moderate (n = 76) or severe (n = 243) by an attending radiologist who was blind to duplex results. Duplex imaging was performed in an Intersocietal Commission for the Accreditation of Vascular Labs (ICAVL) accredited lab, and stenosis was stratified as moderate (50-79%, n = 76) or high (80-99%, n = 243) grade using University of Washington criteria. For each patient, the degree of stenosis as determined by MRA (GE versus TOF) was compared to percent stenosis on duplex. For moderate-grade lesions, GE MRA concurred with duplex in 11.1% (4/36), underestimated in 2.8% (1/36), and overestimated in 86.1% (31/36) of carotid arteries imaged. TOF MRA concurred with duplex in 35% (14/40), underestimated in 0% (0/40), and overestimated in 65% (26/40) of carotid arteries. High-grade lesions demonstrated improved concordance between MRA and duplex. For these lesions, GE MRA concurred with duplex in 95.6% (130/136) of carotid arteries imaged, never overestimated stenosis (0/136), and underestimated in 4.4% (6/136). TOF MRA concurred with duplex 96.3% (103/107), overestimated stenosis as an occlusion in 0.9% (1/107), and underestimated in 2.8% (3/107). In addition to neck visualization, the GE technique allowed simultaneous aortic arch imaging. This was accomplished in 79.1% (136/172) of all GE MRAs. Simultaneous aortic arch imaging was not technically feasible with TOF MRA. For moderate-grade lesions

  8. 32 CFR 56.9 - Ensuring compliance with this part in Federal financial assistance programs and activities.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... approval of these supplementary guidelines from the ASD(MRA&L), or designee, before issuing them. Prior to their issuance, the ASD(MRA&L), or designee, shall submit supplementary guidelines prepared pursuant to... Components deal with the employment of civilians in programs and activities subject to this part the ASD(MRA...

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

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... approval of these supplementary guidelines from the ASD(MRA&L), or designee, before issuing them. Prior to their issuance, the ASD(MRA&L), or designee, shall submit supplementary guidelines prepared pursuant to... Components deal with the employment of civilians in programs and activities subject to this part the ASD(MRA...

  10. 32 CFR 70.4 - Responsibilities.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... (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(MRA&L) and the OSD Federal Register liaison officer to effect publication in the Federal Register. (3...

  11. 32 CFR 70.4 - Responsibilities.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... (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(MRA&L) and the OSD Federal Register liaison officer to effect publication in the Federal Register. (3...

  12. 32 CFR 70.4 - Responsibilities.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... (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(MRA&L) and the OSD Federal Register liaison officer to effect publication in the Federal Register. (3...

  13. 75 FR 52616 - Third Party Testing for Certain Children's Products; Youth All-Terrain Vehicles: Requirements for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-27

    ... Cooperation-Mutual Recognition Arrangement (ILAC-MRA), and the scope of the accreditation must include testing... content of the ILAC-MRA approach and of the requirements of the ISO/IEC 17025:2005 laboratory... part I of this document, it must be accredited by an ILAC-MRA signatory accrediting body, and the...

  14. 32 CFR 179.3 - Definitions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... remedial action is required. Munitions response area (MRA) means any area on a defense site that is known... MRA comprises one or more munitions response sites. Munitions response site (MRS) means a discrete location within an MRA that is known to require a munitions response. Operational range means a range that...

  15. 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 FIX.. 13000 *13000--MRA MTA V134 NE TO V220 NW 12900 Slolm, CO FIX *Gleno, CO FIX 14000 *16000--MRA *Gleno, CO FIX Red Table, CO VOR/DME... 14000 [[Page 3094

  16. 32 CFR 56.9 - Ensuring compliance with this part in Federal financial assistance programs and activities.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... approval of these supplementary guidelines from the ASD(MRA&L), or designee, before issuing them. Prior to their issuance, the ASD(MRA&L), or designee, shall submit supplementary guidelines prepared pursuant to... Components deal with the employment of civilians in programs and activities subject to this part the ASD(MRA...

  17. 75 FR 40720 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-14

    ... FIX GROUP, NY FIX **8000 *4500--MRA **3000--GNSS MEA GROUP, NY FIX ALBANY, NY VORTAC....... *6000..., NY FIX **8000 *4500--MRA **3000--GNSS MEA GROUP, NY FIX ALBANY, NY VORTAC....... *6000 *2300--MOCA... ALBANY, NY VORTAC....... **10000 *6000--MRA **6100--MOCA **8000--GNSS MEA Sec. 95.6214 VOR FEDERAL AIRWAY...

  18. 32 CFR 179.3 - Definitions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... remedial action is required. Munitions response area (MRA) means any area on a defense site that is known... MRA comprises one or more munitions response sites. Munitions response site (MRS) means a discrete location within an MRA that is known to require a munitions response. Operational range means a range that...

  19. 77 FR 50909 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-23

    ... *3000--MRA **1400--MOCA Treasure, FL VORTAC Ovido, FL FIX *4000 *2800--MOCA Sec. 95.6053 VOR Federal... Amended To Read in Part Blythe, CA VORTAC *Vicko, AZ FIX......... 6000 *9000--MRA Sec. 95.6114 VOR Federal... FIX......... 3000 *2500--MRA Walnut Ridge, AR VORTAC........ Dogwood, MO VORTAC..... *3400 *3000--MOCA...

  20. 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(MRA&L) and the OSD Federal Register liaison officer to effect publication in the Federal Register. (3...

  1. 32 CFR 70.4 - Responsibilities.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... (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(MRA&L) and the OSD Federal Register liaison officer to effect publication in the Federal Register. (3...

  2. 32 CFR 179.3 - Definitions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... remedial action is required. Munitions response area (MRA) means any area on a defense site that is known... MRA comprises one or more munitions response sites. Munitions response site (MRS) means a discrete location within an MRA that is known to require a munitions response. Operational range means a range that...

  3. 75 FR 35282 - Third Party Testing for Certain Children's Products; Infant Walkers: Requirements for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-21

    ... (ILAC-MRA), and the scope of the accreditation must include testing for any of the test methods... be accredited. (A description of the history and content of the ILAC-MRA approach and of the... this document, it must be accredited by an ILAC-MRA signatory accrediting body, and the accreditation...

  4. 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

  5. Contrast-enhanced magnetic resonance angiography findings prior to hemodialysis vascular access creation: a prospective analysis.

    PubMed

    Planken, R N; Leiner, T; Nijenhuis, R J; Duijm, L E; Cuypers, P W; Douwes-Draaijer, P; Van Der Sande, F M; Kessels, A G; Tordoir, J H M

    2008-01-01

    To determine prospectively the clinical value of contrast-enhanced magnetic resonance angiography (CE-MRA) for assessment of the arterial inflow and venous outflow prior to vascular access (VA) creation. Seventy-three patients underwent duplex ultrasonography (DUS) and CE-MRA prior to VA creation for detection of stenoses and occlusions. Two observers read the CE-MRA images for determination of inter-observer agreement. A VA was considered functional if it could be used for successful two-needle hemodialysis therapy within 2 months after creation. CE-MRA detected 6 stenosed, 8 occluded arterial vessel segments and 12 stenosed and 41 occluded venous vessel segments in 70 patients. Inter-observer agreement for detection of upper extremity arterial and venous stenoses and occlusions with CE-MRA was substantial to almost perfect (kappa values 0.76-0.96). CE-MRA detected lesions, not detected by DUS, that were associated with VA early failure and non-maturation in 33% of patients (7/21). Accessory veins detected preoperatively were the cause of VA non-maturation in a substantial group of patients (47%: 7/15). CE-MRA enables accurate detection of upper extremity arterial and venous stenosis and occlusions prior to VA creation. Preoperative CE-MRA identified arterial and venous stenoses, not detected by DUS that were associated with VA early failure and non-maturation. However, the use of gadolinium containing contrast media is currently contraindicated due the reported incidence of nephrogenic systemic fibrosis.

  6. 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.

  7. 75 FR 51016 - Third Party Testing for Certain Children's Products; Clothing Textiles: Requirements for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-18

    ... Recognition Arrangement (ILAC-MRA), and the scope of the accreditation must include testing in accordance with... assessment body seeks to be accredited. (A description of the history and content of the ILAC-MRA approach... part I of this document, it must be accredited by an ILAC-MRA signatory accrediting body, and the...

  8. 75 FR 31688 - Third Party Testing for Certain Children's Products; Infant Bath Seats: Requirements for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-04

    ... (ILAC-MRA), and the scope of the accreditation must include testing for any of the test methods... be accredited. (A description of the history and content of the ILAC-MRA approach and of the... identified earlier in part I of this document, it must be accredited by an ILAC-MRA signatory accrediting...

  9. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nielsen, Yousef W., E-mail: yujwni01@heh.regionh.d; Eiberg, Jonas P., E-mail: Eiberg@dadlnet.d; Logager, Vibeke B., E-mail: viloe@heh.regionh.d

    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 wellmore » 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.« less

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kang, Jun; Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland; Huang, Judy

    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.more » 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.« less

  11. 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

  12. 21 CFR 26.0 - General.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Between the United States of America and the European Community” (the MRA), signed at London May 18, 1998. For codification purposes, certain provisions of the MRA have been modified for use in this part. This modification is done for purposes of clarity only and shall not affect the text of the MRA concluded between...

  13. 75 FR 52437 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-26

    ... Part GORDONSVILLE, VA VORTAC LURAY, VA FIX 6100 LURAY, VA FIX *KERRE, VA FIX **6000 *7000--MRA **5000--MOCA *KERRE, VA FIX MARTINSBURG, WV VORTAC.. **6000 *7000--MRA **5000--MOCA Sec. 95.6005 VOR Federal... GORDONSVILLE, VA VORTAC LURAY, VA FIX 6100 LURAY, VA FIX *KERRE, VA FIX **6000 *7000--MRA **5000--MOCA *KERRE...

  14. 75 FR 22746 - Third Party Testing for Certain Children's Products; Notice of Requirements for Accreditation of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-30

    ... Recognition Arrangement (ILAC-MRA), and the scope of the accreditation must include testing for any of the... assessment body seeks to be accredited. (A description of the history and content of the ILAC-MRA approach... the test methods identified earlier in part I of this document, it must be accredited by an ILAC-MRA...

  15. 32 CFR 56.5 - Responsibilities.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 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. 75 FR 82228 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-30

    ... Is Amended To Read in Part Shirt, OH FIX *Gloom, OH FIX 3000 *4000--MRA *Gloom, OH FIX Appleton, OH VORTAC..... 3000 *4000--MRA Appleton, OH VORTAC Mansfield, OH VORTAC.... 3000 Mansfield, OH VORTAC Dryer... in Part Lee County, FL VORTAC Jocks, FL FIX 2600 Jocks, FL FIX *Crowd, FL FIX **2300 *5000--MRA...

  17. 21 CFR 26.0 - General.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... Between the United States of America and the European Community” (the MRA), signed at London May 18, 1998. For codification purposes, certain provisions of the MRA have been modified for use in this part. This modification is done for purposes of clarity only and shall not affect the text of the MRA concluded between...

  18. 21 CFR 26.0 - General.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... Between the United States of America and the European Community” (the MRA), signed at London May 18, 1998. For codification purposes, certain provisions of the MRA have been modified for use in this part. This modification is done for purposes of clarity only and shall not affect the text of the MRA concluded between...

  19. 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...

  20. 32 CFR 56.5 - Responsibilities.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

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

  1. 32 CFR 56.5 - Responsibilities.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 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...

  2. 21 CFR 26.0 - General.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Between the United States of America and the European Community” (the MRA), signed at London May 18, 1998. For codification purposes, certain provisions of the MRA have been modified for use in this part. This modification is done for purposes of clarity only and shall not affect the text of the MRA concluded between...

  3. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Amano, Yasuo; Gemma, Kazuhito; Kawamata, Hiroshi

    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.

  4. 32 CFR 56.5 - Responsibilities.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 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...

  5. 77 FR 27357 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-10

    ... Hygen, CO FIX *Allan, CO FIX **13500 *16000--MRA *15400--MCA ALLAN, CO FIX, NW BND **12900--MOCA *CHART... *Allan, CO FIX Laramie, WY VOR/DME..... 16000 *16000--MRA Sec. 95.6106 VOR Federal Airway V106 Is Amended... in Part Olympia, WA VORTAC *Carro, WA FIX **4000 *4000--MRA **2000--MOCA *CARRO, WA FIX Diggn, WA FIX...

  6. 50 CFR 679.27 - Improved Retention/Improved Utilization Program.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... prohibited all fish of that species brought on board the vessel up to the MRA for that species. (C) Retention... on board equals the MRA for that species. (C) Retention of an IR/IU species is prohibited no fish or... the point that the round-weight equivalent of primary products on board equals the MRA for that...

  7. 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 reapply the rule to all MRSs within the MRA. In such cases where data are not sufficient to populate one... modules. (b) Ensure that the total acreage of each MRA is evaluated using this rule (i.e., ensure the all...

  8. 78 FR 9583 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-11

    ... is Amended to Read in Part LAWRENCEVILLE, VA VORTAC..... *MANGE, VA FIX....... **4000 *5000--MRA.... **5000 *5000--MRA **1800--MOCA **2000--GNSS MEA Sec. 95.6157 VOR Federal Airway V157 is Amended to Read... BND 8600 S BND 10000 *12000--MRA Sec. 95.6301 VOR Federal Airway V301 is Amended to Read in Part SANTA...

  9. 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 reapply the rule to all MRSs within the MRA. In such cases where data are not sufficient to populate one... modules. (b) Ensure that the total acreage of each MRA is evaluated using this rule (i.e., ensure the all...

  10. 76 FR 21622 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-18

    ...--MRA **1700--MOCA Sec. 95.6044 VOR Federal Airway V44 Is Amended To Read in Part BENDS, WV FIX... VORTAC *PRATZ, GA FIX 2500 *3000--MRA PRATZ, GA FIX MACON, GA *2500 VORTAC. *GNSS MEA MACON R-265... *RAGGS, CA FIX **BESSA, CA FIX......... **8500 *8500--MRA **8500--MCA BESSA, CA FIX, S BND **4800--MOCA...

  11. 50 CFR 679.27 - Improved Retention/Improved Utilization Program.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... prohibited all fish of that species brought on board the vessel up to the MRA for that species. (C) Retention... on board equals the MRA for that species. (C) Retention of an IR/IU species is prohibited no fish or... the point that the round-weight equivalent of primary products on board equals the MRA for that...

  12. 76 FR 59890 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-28

    ... in Part *AWSON, GA FIX NELLO, GA FIX **7000 *5000--MRA **5500--MOCA Sec. 95.6006 VOR Federal Airway..., IN FIX *3500 *2400--MOCA BRYTO, IN FIX *PIONS, OH FIX **4000 *4000--MRA **2500--MOCA *PIONS, OH FIX WATERVILLE, OH VOR/DME.. **3300 *4000--MRA **2300--MOCA Sec. 95.6016 VOR Federal Airway V16 Is Amended to...

  13. 50 CFR 679.27 - Improved Retention/Improved Utilization Program.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... IR/IU species is prohibited all fish of that species brought on board the vessel up to the MRA for... equivalent of primary products on board equals the MRA for that species. (C) Retention of an IR/IU species is... MRA for that species. (C) Retention of an IR/IU species is prohibited no fish or product of that...

  14. 50 CFR 679.27 - Improved Retention/Improved Utilization Program.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... IR/IU species is prohibited all fish of that species brought on board the vessel up to the MRA for... equivalent of primary products on board equals the MRA for that species. (C) Retention of an IR/IU species is... MRA for that species. (C) Retention of an IR/IU species is prohibited no fish or product of that...

  15. 76 FR 72094 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-22

    ....6017 VOR Federal Airway V17 is Amended to Read in Part Fator, TX FIX *Nelee, TX FIX **4000 *5500-MRA... Read in Part Sandhills, NC VORTAC *RAEFO, NC FIX **6000 *6000-MRA **2000-MOCA **3000-GNSS MEA *Raefo, NC FIX Fayetteville, NC VOR/DME **2800 *6000-MRA **1900-MOCA &95.6104 VOR Federal Airway V104 Is...

  16. 50 CFR 679.27 - Improved Retention/Improved Utilization Program.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... IR/IU species is prohibited all fish of that species brought on board the vessel up to the MRA for... equivalent of primary products on board equals the MRA for that species. (C) Retention of an IR/IU species is... MRA for that species. (C) Retention of an IR/IU species is prohibited no fish or product of that...

  17. 32 CFR 179.5 - Responsibilities.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... rule. Upon further delineation and characterization of an MRA into more than one MRS, Components shall reapply the rule to all MRSs within the MRA. In such cases where data are not sufficient to populate one... modules. (b) Ensure that the total acreage of each MRA is evaluated using this rule (i.e., ensure the all...

  18. 76 FR 33136 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-08

    .......... Chicago Heights, IL VORTAC....... *Niles, IL FIX 2500 *3500--MRA *3000--MCA Niles, IL FIX, N BND *Niles, IL FIX **Laird, IL FIX......... 3400 *3500--MRA **2600--MCA Laird, IL FIX, S BND Laird, IL FIX Thorr... IN PART....... Bebee, IL FIX *Niles, IL FIX 3400 *3500--MRA *3000--MCA Niles, IL FIX, N BND *Niles...

  19. 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.

  20. Comparison of the diagnostic ability of Moorfield’s regression analysis and glaucoma probability score using Heidelberg retinal tomograph III in eyes with primary open angle glaucoma

    PubMed Central

    Jindal, Shveta; Dada, Tanuj; Sreenivas, V; Gupta, Viney; Sihota, Ramanjit; Panda, Anita

    2010-01-01

    Purpose: To compare the diagnostic performance of the Heidelberg retinal tomograph (HRT) glaucoma probability score (GPS) with that of Moorfield’s regression analysis (MRA). Materials and Methods: The study included 50 eyes of normal subjects and 50 eyes of subjects with early-to-moderate primary open angle glaucoma. Images were obtained by using HRT version 3.0. Results: The agreement coefficient (weighted k) for the overall MRA and GPS classification was 0.216 (95% CI: 0.119 – 0.315). The sensitivity and specificity were evaluated using the most specific (borderline results included as test negatives) and least specific criteria (borderline results included as test positives). The MRA sensitivity and specificity were 30.61 and 98% (most specific) and 57.14 and 98% (least specific). The GPS sensitivity and specificity were 81.63 and 73.47% (most specific) and 95.92 and 34.69% (least specific). The MRA gave a higher positive likelihood ratio (28.57 vs. 3.08) and the GPS gave a higher negative likelihood ratio (0.25 vs. 0.44).The sensitivity increased with increasing disc size for both MRA and GPS. Conclusions: There was a poor agreement between the overall MRA and GPS classifications. GPS tended to have higher sensitivities, lower specificities, and lower likelihood ratios than the MRA. The disc size should be taken into consideration when interpreting the results of HRT, as both the GPS and MRA showed decreased sensitivity for smaller discs and the GPS showed decreased specificity for larger discs. PMID:20952832

  1. 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.

  2. 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

  3. 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.

  4. 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/

  5. 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.

  6. 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.

  7. 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.

  8. Magnetic resonance angiography in infrapopliteal arterial disease: prospective comparison of 1.5 and 3 Tesla magnetic resonance imaging.

    PubMed

    Diehm, Nicolas; Kickuth, Ralph; Baumgartner, Iris; Srivastav, Sudesh K; Gretener, Silvia; Husmann, Marc J; Jaccard, Yves; Do, Do Dai; Triller, Juergen; Bonel, Harald M

    2007-06-01

    To prospectively determine the accuracy of 1.5 Tesla (T) and 3 T magnetic resonance angiography (MRA) versus digital subtraction angiography (DSA) in the depiction of infrageniculate arteries in patients with symptomatic peripheral arterial disease. A prospective 1.5 T, 3 T MRA, and DSA comparison was used to evaluate 360 vessel segments in 10 patients (15 limbs) with chronic symptomatic peripheral arterial disease. Selective DSA was performed within 30 days before both MRAs. The accuracy of 1.5 T and 3 T MRA was compared with DSA as the standard of reference by consensus agreement of 2 experienced readers. Signal-to-noise ratios (SNR) and signal-difference-to-noise ratios (SDNRs) were quantified. No significant difference in overall image quality, sufficiency for diagnosis, depiction of arterial anatomy, motion artifacts, and venous overlap was found comparing 1.5 T with 3 T MRA (P > 0.05 by Wilcoxon signed rank and as by Cohen k test). Overall sensitivity of 1.5 and 3 T MRA for detection of significant arterial stenosis was 79% and 82%, and specificity was 87% and 87% for both modalities, respectively. Interobserver agreement was excellent k > 0.8, P < 0.05) for 1.5 T as well as for 3 T MRA. SNR and SDNR were significantly increased using the 3 T system (average increase: 36.5%, P < 0.032 by t test, and 38.5%, P < 0.037 respectively). Despite marked improvement of SDNR, 3 T MRA does not yet provide a significantly higher accuracy in diagnostic imaging of atherosclerotic lesions below the knee joint as compared with 1.5 T MRA.

  9. Optimization Strategies for Bruch's Membrane Opening Minimum Rim Area Calculation: Sequential versus Simultaneous Minimization.

    PubMed

    Enders, Philip; Adler, Werner; Schaub, Friederike; Hermann, Manuel M; Diestelhorst, Michael; Dietlein, Thomas; Cursiefen, Claus; Heindl, Ludwig M

    2017-10-24

    To compare a simultaneously optimized continuous minimum rim surface parameter between Bruch's membrane opening (BMO) and the internal limiting membrane to the standard sequential minimization used for calculating the BMO minimum rim area in spectral domain optical coherence tomography (SD-OCT). In this case-control, cross-sectional study, 704 eyes of 445 participants underwent SD-OCT of the optic nerve head (ONH), visual field testing, and clinical examination. Globally and clock-hour sector-wise optimized BMO-based minimum rim area was calculated independently. Outcome parameters included BMO-globally optimized minimum rim area (BMO-gMRA) and sector-wise optimized BMO-minimum rim area (BMO-MRA). BMO area was 1.89 ± 0.05 mm 2 . Mean global BMO-MRA was 0.97 ± 0.34 mm 2 , mean global BMO-gMRA was 1.01 ± 0.36 mm 2 . Both parameters correlated with r = 0.995 (P < 0.001); mean difference was 0.04 mm 2 (P < 0.001). In all sectors, parameters differed by 3.0-4.2%. In receiver operating characteristics, the calculated area under the curve (AUC) to differentiate glaucoma was 0.873 for BMO-MRA, compared to 0.866 for BMO-gMRA (P = 0.004). Among ONH sectors, the temporal inferior location showed the highest AUC. Optimization strategies to calculate BMO-based minimum rim area led to significantly different results. Imposing an additional adjacency constraint within calculation of BMO-MRA does not improve diagnostic power. Global and temporal inferior BMO-MRA performed best in differentiating glaucoma patients.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhang Pengpeng; Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY; Wu, Leester

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

  11. Spinal arteriovenous shunts: accuracy of shunt detection, localization, and subtype discrimination using spinal magnetic resonance angiography and manual contrast injection using a syringe.

    PubMed

    Unsrisong, Kittisak; Taphey, Siriporn; Oranratanachai, Kanokporn

    2016-04-01

    The object of this study was to evaluate the accuracy of fast 3D contrast-enhanced spinal MR angiography (MRA) using a manual syringe contrast injection technique for detecting and evaluating spinal arteriovenous shunts (AVSs). This was a retrospective study of 15 patients and 20 spinal MRA and catheter angiography studies. The accuracy of using spinal MRA to detect spinal AVS, localize shunts, and discriminate the subtype and dominant arterial feeder of the AVS were studied. There were 14 pretherapeutic and 6 posttherapeutic follow-up spinal MRA and catheter spinal angiography studies. The spinal AVS was demonstrated in 17 of 20 studies. Spinal MRA demonstrated 100% sensitivity for detecting spinal AVS with no false-negative results. A 97% accuracy rate for AVS subtype discrimination and shunt level localization was achieved using this study's diagnostic criteria. The detection of the dominant arterial feeder was limited to 9 of these 17 cases (53%). The fast 3D contrast-enhanced MRA technique performed using manual syringe contrast injection can detect the presence of a spinal AVS, locate the shunt level, and discriminate AVS subtype in most cases, but is limited when detecting small arterial feeders.

  12. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Buis, Dennis R.; Lagerwaard, Frank J.; Dirven, Clemens M.F.

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

  13. 23 CFR 637.209 - Laboratory and sampling and testing personnel qualifications.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... Laboratory Accreditation Cooperation (APLAC) Mutual Recognition Arrangement (MRA), is a signatory to the International Laboratory Accreditation Cooperation (ILAC) Mutual Recognition Arrangement (MRA), or another...

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

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Laboratory Accreditation Cooperation (APLAC) Mutual Recognition Arrangement (MRA), is a signatory to the International Laboratory Accreditation Cooperation (ILAC) Mutual Recognition Arrangement (MRA), or another...

  15. 23 CFR 637.209 - Laboratory and sampling and testing personnel qualifications.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... Laboratory Accreditation Cooperation (APLAC) Mutual Recognition Arrangement (MRA), is a signatory to the International Laboratory Accreditation Cooperation (ILAC) Mutual Recognition Arrangement (MRA), or another...

  16. 23 CFR 637.209 - Laboratory and sampling and testing personnel qualifications.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Laboratory Accreditation Cooperation (APLAC) Mutual Recognition Arrangement (MRA), is a signatory to the International Laboratory Accreditation Cooperation (ILAC) Mutual Recognition Arrangement (MRA), or another...

  17. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wieners, Gero, E-mail: gero.wieners@med.ovgu.d; Meyer, Frank; Halloul, Zuhir

    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 IImore » 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.« less

  18. [Combined use of ECK-triggered 2D-phase contrast MR angiography and 2D-time-of-flight MR angiography for planning and follow up before and after vascular intervention of pelvic and leg arteries].

    PubMed

    Reimer, P; Wilhelm, M; Lentschig, M; Wörtler, K; Marx, C; Allkemper, T; Boettger, U; Heinecke, A; Rummeny, E J; Peters, P E

    1998-03-01

    To develop a strategy for the complete work-up of vessel lumen and vessel wall for planning and follow-up of radiological interventions of lower extremity arteries. A total of 36 patients (21 pre-, 8 post- and 7 pre- and postinterventional) were studied. MRA studies were performed using an ECG-triggered phase contrast technique for the demonstration of intraluminal flow and an axial high resolution time-of-flight technique to assess the vascular wall. All MRA studies were analysed by intraindividual DSA comparison for the assessment of flow and wall structures. Combined MRA techniques provided a good correlation with DSA for the assessment of vascular flow. The kappa test revealed a value of greater than 0.61 for most on the vessel segments proving a good correlation of both methods. Orthogonal high-resolution TOF-MRA provided additional information for the assessment postinterventional wall haematomas and hard plaques. Combination of PCA to study flow and axial TOF to study wall pathology improves the usefulness of peripheral MRA.

  19. Atherosclerosis of the carotid artery: evaluation by magnetic resonance angiography.

    PubMed

    Wildy, K S; Yuan, C; Tsuruda, J S; Ferguson, M S; Wen, N; Subramaniam, D S; Strandness, D E

    1996-01-01

    Carotid artery atherosclerotic plaques (APs) can lead to brain ischemia, an event shown to correlate with both the degree of stenosis and the composition of the AP. Currently, accurate estimates of stenosis can be obtained by either x-ray angiography or three-dimensional time-of-flight (TOF) magnetic resonance angiography (MRA). Our purpose was to determine whether three-dimensional TOF MRA images could also provide information on plaque location, morphology, and composition. Seven pre-endarterectomy patients underwent three-dimensional TOF MRA. After endarterectomy, plaque histology was evaluated. Three-dimensional TOF MRA images contained sufficient soft tissue contrast to differentiate the plaques from the surrounding tissues in all cases. Estimation of plaque morphology had 80% correlation with histology. Finally, intraplaque hemorrhage and calcification were deplicted as regions of moderately high and very low intensity, respectively. These preliminary results suggest that three-dimensional TOF MRA may be useful in studying the development and progression of carotid atherosclerosis.

  20. High spatial resolution time-resolved magnetic resonance angiography of lower extremity tumors at 3T

    PubMed Central

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

    2016-01-01

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

  1. Lower limb vascular disease in diabetic patients: a study with calf compression contrast-enhanced magnetic resonance angiography at 3.0 Tesla.

    PubMed

    Li, Jie; Zhao, Jun-Gong; Li, Ming-Hua

    2011-06-01

    To retrospectively analyze the significance of 3.0-T contrast-enhanced (CE) magnetic resonance angiography (MRA) with calf compression in the lower limbs of diabetic patients with peripheral vascular disease. Sixty-one type 2 diabetes patients underwent both MRA and digital subtraction angiography (DSA) within 1 week. The patients were divided into two groups: one with (pressure) and one without (conventional) calf compression during MRA. Two radiologists evaluated the quality of MRA images and compared the two groups. Cohen's kappa statistic was used to determine the concordance between MRA and DSA. Image quality in the calf and foot was better in the group with calf pressure than the conventional group without applied pressure (P = .001 [calf], 0.008 [foot]). Significantly more runoff vessels in the calf were detected with MRA than with DSA (P = .0043 [conventional], 0.0031 [pressure]). The kappa values were 0.928 in the conventional group and 0.979 in the pressure group, but in the conventional group, the diagnostic accuracy of CE-MRA was lower than that of DSA (P = .002). Diagnostic accuracy in the pressure group was significantly higher than that in the conventional group (P = .009). The overall sensitivity and specificity for >50% stenosis or occlusion was 93.8% and 98.5%, respectively, in the conventional group and 98.7% and 99.6%, respectively, in the pressure group. With calf compression, venous overlap (P = .0396, .0425) and deep vein overlap (P = .022, .022) were significantly reduced in the leg and foot. Calf compression with 3.0-T CE-MRA was convenient and practical and could improve image quality and diagnostic accuracy in diabetic patients with peripheral vascular disease by reducing venous overlap. Copyright © 2011 AUR. Published by Elsevier Inc. All rights reserved.

  2. 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

  3. DOE Office of Scientific and Technical Information (OSTI.GOV)

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

    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,more » 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.« less

  4. Time of flight MR angiography assessment casts doubt on the association between transient global amnesia and intracranial jugular venous reflux.

    PubMed

    Kang, Yeonah; Kim, Eunhee; Kim, Jae Hyoung; Choi, Byung Se; Jung, Cheolkyu; Bae, Yun Jung; Lee, Kyung Mi; Lee, Dong Hoon

    2015-03-01

    Evidence of intracranial venous reflux flow due to jugular venous reflux (JVR) on time of flight (TOF) MR angiography (MRA) is thought to be highly associated with transient global amnesia (TGA)-evidence that supports the venous congestion theory of TGA pathophysiology. However, recent studies indicate that intracranial JVR on TOF MRA is occasionally observed in normal elderly. Therefore, the purpose of this study was to compare the prevalence of intracranial JVR on TOF MRA in patients with TGA and two control groups. Three age- and sex-matched groups of subjects that received MRI and MRA were enrolled. The groups comprised 167 patients with TGA, 167 visitors to the emergency room (ER) and 167 visitors to a health promotion centre (HPC). Intracranial JVR was defined as abnormal venous signals in the inferior petrosal, sigmoid and/or transverse sinuses on TOF MRA. The prevalence of intracranial JVR was assessed across the three groups. Intracranial JVR was seen in seven (4.2 %) TGA patients, eight (4.8 %) ER visitors and three (1.8 %) HPC visitors, respectively. No statistically significant differences were observed among the three groups. TGA patients showed a low prevalence of intracranial JVR on TOF MRA, and no statistical differences were found in comparison with control groups.

  5. 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.

  6. 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.

  7. 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.

  8. Dynamic alteration of regional cerebral blood flow during carotid compression and proof of reversibility.

    PubMed

    Asahi, Kouichi; Hori, M; Hamasaki, N; Sato, S; Nakanishi, H; Kuwatsuru, R; Sasai, K; Aoki, S

    2012-01-01

    It is difficult to non-invasively visualize changes in regional cerebral blood flow caused by manual compression of the carotid artery. To visualize dynamic changes in regional cerebral blood flow during and after manual compression of the carotid artery. Two healthy volunteers were recruited. Anatomic features and flow directions in the circle of Willis were evaluated with time-of-flight magnetic resonance angiography (MRA) and two-dimensional phase-contrast (2DPC) MRA, respectively. Regional cerebral blood flow was visualized with territorial arterial spin-labeling magnetic resonance imaging (TASL-MRI). TASL-MRI and 2DPC-MRA were performed in three states: at rest, during manual compression of the right carotid artery, and after decompression. In one volunteer, time-space labeling inversion pulse (Time-SLIP) MRA was performed to confirm collateral flow. During manual carotid compression, in one volunteer, the right thalamus changed to be fed only by the vertebrobasilar system, and the right basal ganglia changed to be fed by the left internal carotid artery. In the other volunteer, the right basal ganglia changed to be fed by the vertebrobasilar system. 2DPC-MRA showed that the flow direction changed in the right A1 segment of the anterior cerebral artery and the right posterior communicating artery. Perfusion patterns and flow directions recovered after decompression. Time-SLIP MRA showed pial vessels and dural collateral circulation when the right carotid artery was manually compressed. Use of TASL-MRI and 2DPC-MRA was successful for non-invasive visualization of the dynamic changes in regional cerebral blood flow during and after manual carotid compression.

  9. 78 FR 21353 - Combined Notice of Filings #1

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-10

    ... Company. Description: Mississippi Power Company submits 2011 MRA Rate Case Compliance Filing to be...: Mississippi Power Company. Description: Mississippi Power Company submits MRA 24 Rate Case Filing to be...

  10. Clinical and surgical correlation of hip MR arthrographic findings in adolescents.

    PubMed

    Jawahar, Anugayathri; Vade, Aruna; Lomasney, Laurie; Okur, Gokcan; Evans, Douglas; Subbaiah, Perla

    2016-06-01

    The purpose of this study was to analyze the utility of MRA-H in adolescents by comparing the results of imaging with surgical findings and/or clinical outcome. After obtaining appropriate IRB approval, the Radiologic Information System database was queried for all patients 13-18 years of age who underwent MRA-H from 2004 through 2013. The electronic medical record was reviewed for clinical history, clinical examination findings, and operative notes. MRA-H images were reviewed for soft tissue abnormalities (labral tear, paralabral ganglion, articular cartilage loss, synovitis, ligament tears) and bony abnormalities (cam-type femoroacetabular impingement (FAI), pincer-type FAI, hip dysplasia). MRA-H findings were correlated with surgical findings and with clinical outcomes. Twenty-six patients with labral tears by MRA-H were included in study and grouped as follows: Group I) patients who underwent surgical management (n=10); group II) patients managed non-surgically (medication, intra-articular injection, physical therapy) (n=9); group III) patients lost to follow up after being advised to have surgery (n=7). With regard to presenting symptomatology, 87.5% of patients with labral tear had groin pain. Of those patients who were diagnosed with a labral tear, 52% were categorized as idiopathic labral tears, 26% as secondary tears (secondary to abnormal bony morphology), and 22% as traumatic labral tears. The labral tears were found to be anterior in 61% and posterior in 22%. Associated articular cartilage lesions were found in 29% of patients. In group I (surgical patients), MRA-H labral findings were confirmed at surgery in 9/10. Seventy percent of labral tears in our study had some form of abnormal bony morphology. Nine of the 12 patients with bone abnormalities were derived from group I patients. Six out of 7 patients with cam-type FAI had a labral tear. Labral tears diagnosed by MRA-H in the adolescent population correlated well with clinical examination and

  11. 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.

  12. Four cases of vertebrobasilar insufficiency.

    PubMed

    Inui, H; Yoneyama, K; Kitaoku, Y; Nakane, M; Ohue, S; Yamanaka, T; Ueda, T; Fujita, N; Miyahara, H; Matsunaga, T

    1998-01-01

    Four cases of vertebrobasilar insufficiency are reported. Case 1 was a 38-year-old man who felt a sudden onset of dizziness when he turned his head to the back. An abnormal positional nystagmus was observed when he rotated his head to the left. A magnetic resonance angiogram (MRA) demonstrated total occlusion of the left vertebral artery (VA). Case 2 was a 31-year-old woman who had a total occlusion of her left VA as observed in the MRA. Case 3 was a 68-year-old man who noted dizziness. The systolic blood pressure change on his Schellong test was 28 mmHg. On his MRA, severe displacement of the basilar and the vertebral arteries was visible. Case 4 was a 76-year-old woman who noted a blackout-like sensation. Optokinetic nystagmus was noted with a hyponystagmus pattern, and an eye tracking test showed a saccadic pattern. On her MRA, the vertebrobasilar system was narrowed. The arterial architecture and any stenosis of the blood vessels could be detected non-invasively by MRA.

  13. 76 FR 5565 - Notice of Stay of Enforcement of Testing and Certification Pertaining to Youth All-Terrain Vehicles

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-01

    ... Cooperation-Mutual Recognition Arrangement (ILAC-MRA), a prerequisite for such conformity assessment bodies to... the requisite accreditation by an ILAC-MRA signatory to test for conformity to 16 CFR part 1420'' and...

  14. 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. Copyright © 2016 John Wiley & Sons, Ltd.

  15. Magnetic resonance angiography for the nonpalpable testis: a cost and cancer risk analysis.

    PubMed

    Eggener, S E; Lotan, Y; Cheng, E Y

    2005-05-01

    For the unilateral nonpalpable testis standard management is open surgical or laparoscopic exploration. An ideal imaging technique would reliably identify testicular nubbins and safely allow children to forgo surgical exploration without compromising future health or fertility. Our goal was to perform a cost and risk analysis of magnetic resonance angiography (MRA) for unilateral nonpalpable cryptorchid testes. A search of the English medical literature revealed 3 studies addressing the usefulness of MRA for the nonpalpable testicle. We performed a meta-analysis and applied the results to a hypothetical set of patients using historical testicular localization data. Analysis was then performed using 3 different management protocols-MRA with removal of testicular nubbin tissue, MRA with observation of testicular nubbin tissue and diagnostic laparoscopy. A cancer risk and cost analysis was then performed. MRA with observation of testicular nubbin tissue results in 29% of patients avoiding surgery without any increased cost of care. Among the 29% of boys with testicular nubbins left in situ and observed the highest estimated risk was 1 in 300 of cancer developing, and 1 in 5,300 of dying of cancer. A protocol using MRA with observation of inguinal nubbins results in nearly a third of boys avoiding surgical intervention at a similar cost to standard care without any significant increased risk of development of testis cancer.

  16. [Value of MR imaging and MR angiography in the differential diagnosis of carotid space tumour].

    PubMed

    Liu, Pei-fang; Li, Xin; Bao, Run-xian; Liu, Jing-zu; Ge, Zheng-jin

    2004-04-01

    To determine the imaging features of magnetic resonance imaging (MRI) and 2D time of flight (TOF) MR angiography (MRA) and study the value in the differential diagnosis and surgical planning for carotid space tumors. Twenty-six patients with suspected pulsatile carotid space mass were imaged by MRI and 2D TOF MRA from 1996 to 2003. Its characteristic findings were analyzed for lesion shape, margin, signal intensity, angle of common carotid bifurcation, and the relationship between the great vessels and carotid space mass. Of the 26 patients, 22 were verified histopathologically, including 15 carotid body tumors (1 patient had bilateral carotid body tumors), 4 carotid artery aneurysms, 3 schwannomas, and 1 metastatic carcinoma. The rest four patients had clinical pseudomasses proved by MRI and MRA as considerable dilated or tortuous carotid artery as compared with the contralateral one. Combined MRI and MRA assessment of carotid body tumors and carotid artery aneurysm yielded an accuracy of 100%. It was also revealed that the anatomy shown on the MRI and axial MRA source images was consistent with that found by surgery. MRI in combination with MRA is considered as non-invasive imaging technique for the evaluation of carotid space tumor showing superiority to other modalities in the differential diagnosis between vascular versus non-vascular tumours. This method may take the place of traumatic carotid angiography.

  17. 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

  18. Characterization of Mineralocorticoid Receptor Antagonist Therapy Initiation in High-Risk Patients With Heart Failure.

    PubMed

    Cooper, Lauren B; Hammill, Bradley G; Peterson, Eric D; Pitt, Bertram; Maciejewski, Matthew L; Curtis, Lesley H; Hernandez, Adrian F

    2017-01-01

    Heart failure guidelines recommend routine monitoring of serum potassium, and renal function in patients treated with a mineralocorticoid receptor antagonist (MRA). How these recommendations are implemented in high-risk patients or according to setting of drug initiation is poorly characterized. We conducted a retrospective cohort study of Medicare beneficiaries linked to laboratory data in 10 states with prevalent heart failure as of July 1, 2011, and incident MRA use between May 1 and September 30, 2011. Outcomes included laboratory testing before MRA initiation and in the early (days 1-10) and extended (days 11-90) post-initiation periods, based on setting of drug initiation and the presence of renal insufficiency. Additional outcomes included abnormal laboratory results and adverse events proximate to MRA initiation. Of 10 443 Medicare beneficiaries with heart failure started on an MRA, 19.7% were initiated during a hospitalization. Appropriate follow-up laboratory testing across all time periods occurred in 25.2% of patients with inpatient initiation compared with 2.8% of patients begun as an outpatient. Patients with chronic kidney disease had higher rates of both hyperkalemia and acute kidney failure in the early (1.3% and 2.7%, respectively) and extended (5.6% and 9.8%, respectively) post-initiation periods compared with those without chronic kidney disease. Patients initiated on MRA therapy as an outpatient had extremely poor rates of guideline indicated follow-up laboratory monitoring after drug initiation. In particular, patients with chronic kidney disease are at high risk for adverse events after MRA initiation. Quality improvement initiatives focused on systems to improve appropriate laboratory monitoring are needed. © 2017 American Heart Association, Inc.

  19. Assessing bioequivalence of generic modified-release antiepileptic drugs

    PubMed Central

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

    2016-01-01

    Objectives: 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. Methods: 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. Results: 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. Conclusions: 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. PMID:27016518

  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. 47 CFR 68.160 - Designation of Telecommunication Certification Bodies (TCBs).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... recognition agreement or arrangement (MRA) to which the United States is a party, bodies outside the United States shall be permitted to authorize equipment in lieu of the Commission. A body in an MRA partner...

  2. 76 FR 77249 - National Register of Historic Places; Notification of Pending Nominations and Related Actions

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-12

    ...), (Asheville Historic and Architectural MRA) 76- 129 Biltmore Ave., 64 Carter St., 11-23 Grove St., 14-44 N..., (Chatham County MRA) 2488 Wade Paschal Rd., Siler City, 11000973 Henderson County Rice, Clough H., House...

  3. 47 CFR 2.960 - Designation of Telecommunication Certification Bodies (TCBs).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... recognition agreement or arrangement (MRA) to which the United States is a party, bodies outside the United States shall be permitted to authorize equipment in lieu of the Commission. A body in an MRA partner...

  4. 47 CFR 68.160 - Designation of Telecommunication Certification Bodies (TCBs).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... recognition agreement or arrangement (MRA) to which the United States is a party, bodies outside the United States shall be permitted to authorize equipment in lieu of the Commission. A body in an MRA partner...

  5. 47 CFR 2.960 - Designation of Telecommunication Certification Bodies (TCBs).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... recognition agreement or arrangement (MRA) to which the United States is a party, bodies outside the United States shall be permitted to authorize equipment in lieu of the Commission. A body in an MRA partner...

  6. 47 CFR 2.960 - Designation of Telecommunication Certification Bodies (TCBs).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... recognition agreement or arrangement (MRA) to which the United States is a party, bodies outside the United States shall be permitted to authorize equipment in lieu of the Commission. A body in an MRA partner...

  7. 47 CFR 68.160 - Designation of Telecommunication Certification Bodies (TCBs).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... recognition agreement or arrangement (MRA) to which the United States is a party, bodies outside the United States shall be permitted to authorize equipment in lieu of the Commission. A body in an MRA partner...

  8. Magnetic resonance angiography of the pediatric abdomen and pelvis: techniques and imaging findings.

    PubMed

    Sada, David M; Vellody, Ranjith; Liu, Peter S

    2013-11-01

    Although traditional catheter-based angiography has been the gold standard for pediatric abdominal and pelvic vascular imaging for the past several decades, advances in magnetic resonance angiography (MRA) have made it a viable alternative. MRA offers several advantages in that it is noninvasive, can be performed without ionizing radiation, and does not necessarily rely on contrast administration. The ability of modern MRA techniques to define variant vascular anatomy and detect vascular disease may obviate traditional angiography in some patients. Copyright © 2013 Elsevier Inc. All rights reserved.

  9. 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...

  10. 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...

  11. 14 CFR 95.1 - Applicability.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... of a VOR station used to define the route. (f) The MRA applies to the operation of an aircraft over an intersection defined by ground-based navigation aids. The MRA is the lowest altitude at which the...

  12. 14 CFR 95.1 - Applicability.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... of a VOR station used to define the route. (f) The MRA applies to the operation of an aircraft over an intersection defined by ground-based navigation aids. The MRA is the lowest altitude at which the...

  13. 14 CFR 95.1 - Applicability.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... of a VOR station used to define the route. (f) The MRA applies to the operation of an aircraft over an intersection defined by ground-based navigation aids. The MRA is the lowest altitude at which the...

  14. 14 CFR 95.1 - Applicability.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... of a VOR station used to define the route. (f) The MRA applies to the operation of an aircraft over an intersection defined by ground-based navigation aids. The MRA is the lowest altitude at which the...

  15. 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...

  16. 14 CFR 95.1 - Applicability.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... of a VOR station used to define the route. (f) The MRA applies to the operation of an aircraft over an intersection defined by ground-based navigation aids. The MRA is the lowest altitude at which the...

  17. 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

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

    PubMed Central

    HAMAMOTO, Kohei; MATSUURA, Katsuhiko; CHIBA, Emiko; OKOCHI, Tomohisa; TANNO, Keisuke; TANAKA, Osamu

    2016-01-01

    Purpose: 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). Methods: 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. Results: 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. Conclusion: Time-SLIP MRA is technically and clinically feasible and represents a promising technique for noninvasive pre- and post

  19. Non-Contrast-Enhanced MR Angiography at 3 Tesla in Patients with Advanced Peripheral Arterial Occlusive Disease

    PubMed Central

    Nikolaou, Konstantin; Sommer, Wieland H.; Schmitt, Peter; Kazmierczak, Philipp M.; Reiser, Maximilian F.; Theisen, Daniel

    2014-01-01

    Purpose 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). Method and Materials 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. Results 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). Conclusion 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. PMID:24608937

  20. Effects of time of day and monensin on the size distribution of particles in digestive tract sites of heifers fed corn silage.

    PubMed

    Deswysen, A G; Pond, K R; Rivera-Villarreal, E; Ellis, W C

    1989-07-01

    Effects of time of day and dietary monensin in the distribution of size of digesta particles in different digestive tract sites and their intersite relationships were examined in six heifers (290 kg BW) with ruminal, duodenal and ileal cannulas given ad libitum access to corn silage, with or without 100 mg monensin.head-1.d-1, in a two-period crossover design. Ingestive masticate and digesta of corn silage were collected via esophageal, ruminal or intestinal cannulas. The distribution of particulate matter retained on sieves with apertures larger than 20 microm was determined by wet-sieving. The cumulative distribution of particulate matter on a series of sieves was regressed on retaining sieve aperture to estimate the sieve aperture that would retain 50% weight of the particulate matter (median retaining aperture, MRA). The MRA of masticate was 6,494 microm. The MRA of digesta particles decreased (P less than .05) from ventral rumen (1,847 microm) to dorsal rumen (1,797 microm) to duodenum (346 microm), but increased to the rectum (359 microm). The MRA was lower (P = .044) for the monensin treatment only in feces. The MRA of particulate matter in the dorsal and ventral rumen, duodenum and rectum all changed (P less than .05) over 24 h. An inverse pattern between the MRA of ruminal and duodenal digesta occurred, presumably the result of a nycterohemeral pattern of eating and ruminating activity. Across sampling times, an inverse relationship existed between MRA of ventral rumen and duodenal digesta. This relationship suggests that a ruminal digesta raft composed of larger particles (immediately following major meals) is more effective than a raft of smaller particles (prior to such meals) in preventing flux of large particles to the duodenum.

  1. Estimation of lung tumor position from multiple anatomical features on 4D-CT using multiple regression analysis.

    PubMed

    Ono, Tomohiro; Nakamura, Mitsuhiro; Hirose, Yoshinori; Kitsuda, Kenji; Ono, Yuka; Ishigaki, Takashi; Hiraoka, Masahiro

    2017-09-01

    To estimate the lung tumor position from multiple anatomical features on four-dimensional computed tomography (4D-CT) data sets using single regression analysis (SRA) and multiple regression analysis (MRA) approach and evaluate an impact of the approach on internal target volume (ITV) for stereotactic body radiotherapy (SBRT) of the lung. Eleven consecutive lung cancer patients (12 cases) underwent 4D-CT scanning. The three-dimensional (3D) lung tumor motion exceeded 5 mm. The 3D tumor position and anatomical features, including lung volume, diaphragm, abdominal wall, and chest wall positions, were measured on 4D-CT images. The tumor position was estimated by SRA using each anatomical feature and MRA using all anatomical features. The difference between the actual and estimated tumor positions was defined as the root-mean-square error (RMSE). A standard partial regression coefficient for the MRA was evaluated. The 3D lung tumor position showed a high correlation with the lung volume (R = 0.92 ± 0.10). Additionally, ITVs derived from SRA and MRA approaches were compared with ITV derived from contouring gross tumor volumes on all 10 phases of the 4D-CT (conventional ITV). The RMSE of the SRA was within 3.7 mm in all directions. Also, the RMSE of the MRA was within 1.6 mm in all directions. The standard partial regression coefficient for the lung volume was the largest and had the most influence on the estimated tumor position. Compared with conventional ITV, average percentage decrease of ITV were 31.9% and 38.3% using SRA and MRA approaches, respectively. The estimation accuracy of lung tumor position was improved by the MRA approach, which provided smaller ITV than conventional ITV. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

  2. 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.

  3. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sailer, Anna M., E-mail: anni.sailer@mumc.nl; Haan, Michiel W. de, E-mail: m.de.haan@mumc.nl; Graaf, Rick de, E-mail: r.de.graaf@mumc.nl

    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 fusionmore » 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.« less

  4. Journal Club: Comparison of assessment of preoperative pulmonary vasculature in patients with non-small cell lung cancer by non-contrast- and 4D contrast-enhanced 3-T MR angiography and contrast-enhanced 64-MDCT.

    PubMed

    Ohno, Yoshiharu; Nishio, Mizuho; Koyama, Hisanobu; Yoshikawa, Takeshi; Matsumoto, Sumiaki; Seki, Shinichiro; Sugimura, Kazuro

    2014-03-01

    The purpose of this article is to prospectively and directly compare the capabilities of non-contrast-enhanced MR angiography (MRA), 4D contrast-enhanced MRA, and contrast-enhanced MDCT for assessing pulmonary vasculature in patients with non-small cell lung cancer (NSCLC) before surgical treatment. A total of 77 consecutive patients (41 men and 36 women; mean age, 71 years) with pathologically proven and clinically assessed stage I NSCLC underwent thin-section contrast-enhanced MDCT, non-contrast-enhanced and contrast-enhanced MRA, and surgical treatment. The capability for anomaly assessment of the three methods was independently evaluated by two reviewers using a 5-point visual scoring system, and final assessment for each patient was made by consensus of the two readers. Interobserver agreement for pulmonary arterial and venous assessment was evaluated with the kappa statistic. Then, sensitivity, specificity, and accuracy for the detection of anomalies were directly compared among the three methods by use of the McNemar test. Interobserver agreement for pulmonary artery and vein assessment was substantial or almost perfect (κ=0.72-0.86). For pulmonary arterial and venous variation assessment, there were no significant differences in sensitivity, specificity, and accuracy among non-contrast-enhanced MRA (pulmonary arteries: sensitivity, 77.1%; specificity, 97.4%; accuracy, 87.7%; pulmonary veins: sensitivity, 50%; specificity, 98.5%; accuracy, 93.2%), 4D contrast-enhanced MRA (pulmonary arteries: sensitivity, 77.1%; specificity, 97.4%; accuracy, 87.7%; pulmonary veins: sensitivity, 62.5%; specificity, 100.0%; accuracy, 95.9%), and thin-section contrast-enhanced MDCT (pulmonary arteries: sensitivity, 91.4%; specificity, 89.5%; accuracy, 90.4%; pulmonary veins: sensitivity, 50%; specificity, 100.0%; accuracy, 95.9%) (p>0.05). Pulmonary vascular assessment of patients with NSCLC before surgical resection by non-contrast-enhanced MRA can be considered equivalent to

  5. Accuracy of the Medication Adherence Report Scale (MARS-5) as a quantitative measure of adherence to inhalation medication in patients with COPD.

    PubMed

    Tommelein, Eline; Mehuys, Els; Van Tongelen, Inge; Brusselle, Guy; Boussery, Koen

    2014-05-01

    Self-report is considered most suitable to measure medication adherence in routine clinical practice. However, accuracy of self-report as a quantitative measure of adherence is not well documented. To assess the accuracy of a self-report measure of adherence (Medication Adherence Report Scale [MARS-5]) for identifying nonadherent users of inhalation medication among patients with chronic obstructive pulmonary disease (COPD), compared with medication refill adherence (MRA) as reference. We used baseline data from the Pharmaceutical Care for Patients with COPD (PHARMACOP)-trial (n = 734). Patients with incomplete MARS-5 and/or incomplete pharmacy refill records were excluded (n = 121). Internal consistency of MARS-5 (Crohnbach α) and Spearman rank correlation (ρ) with MRA were calculated. Different thresholds for nonadherence were used to calculate sensitivity, specificity, and positive predictive value (PPV), compared with dichotomized MRA (MRA ≥80% = adherent). A receiver operating characteristic (ROC) curve was plotted to determine the goodness of test. 613 patients were included in the analysis. The mean adherence score by MARS-5 (range = 5-25) was 23.5 (SD = 2.6); mean adherence by MRA was 83.4% (SD = 23.8%). Internal consistency of MARS-5 was high (α = 0.77). Continuous MARS-5 scores correlated poorly with continuous MRA scores (ρ = 0.10; P = 0.011). When lowering the nonadherence threshold stepwise from 25 to 20, MARS-5 did not reach sufficient sensitivity (53% to 13%), specificity (57% to 94%), and PPV (42% to 57%) to detect nonadherers compared with dichotomized MRA. ROC curve plotting resulted in an area under the curve value of 0.56 (95% CI = 0.521-0.616; P = 0.005). Self-reported adherence measured by MARS-5 is inaccurate in identifying nonadherence to inhalation medication in patients with COPD.

  6. A follow-up study of autosomal dominant polycystic kidney disease with intracranial aneurysms using 3.0 T three-dimensional time-of-flight magnetic resonance angiography.

    PubMed

    Jiang, Tao; Wang, Peng; Qian, Yi; Zheng, Xuan; Xiao, Liaoyuan; Yu, Shengqiang; Liu, Shiyuan

    2013-11-01

    Autosomal dominant polycystic kidney disease (ADPKD) patients have an increased risk for intracranial aneurysms (IAs). Our aim was to screen and follow up the unruptured intracranial aneurysms (UIAs) detected by 3.0 T three-dimensional time-of-flight magnetic resonance angiography (3D-TOF MRA) in patients with ADPKD in order to evaluate the growth of UIAs and the value of 3D-TOF MRA. From 2011 to 2012, we followed up UIAs detected in 40 ADPKD patients who had MRA examinations with an interval of at least 36 months. All MRA examinations were performed on a 3T system (Achieva X-Series, Philips Medical Systems) with a Sense-Head-8 receiver head coil. The acquired data sets were transferred to a workstation (EWS, Philips Medical) to perform maximum intensity projection (MIP) and volume rendering (VR) with a specialized software package (Philips Medical). The size of UIAs was determined as the longest diameter in transverse or vertical measurement. UIAs that grew more than 20% were considered as enlarged. Fifty UIAs were found in 40 previously examined ADPKD patients who underwent 3.0 T 3D-TOF MRA follow-ups. No patients ever had treatment before the second examination. The longest diameter of all follow-up UIAs was less than 10mm and mean diameter was 3.64 ± 2.25 mm. UIAs in only 4 patients (10%) were considered as enlarged. None of the 50 IAs in the 40 ADPKD patients ruptured during the MRA follow-up period. 3.0 T 3D-TOF MRA was feasible for UIAs follow-up in ADPKD patients. The chance of enlargement and rupture of UIAs in ADPKD patients was not higher than in the general population. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  7. Time-of-Flight MR Angiography for Detection of Cerebral Hyperperfusion Syndrome after Superficial Temporal Artery-Middle Cerebral Artery Anastomosis in Moyamoya Disease.

    PubMed

    Sato, K; Yamada, M; Kuroda, H; Yamamoto, D; Asano, Y; Inoue, Y; Fujii, K; Kumabe, T

    2016-07-01

    Cerebral hyperperfusion syndrome is a potential complication of superficial temporal artery-MCA anastomosis for Moyamoya disease. In this study, we evaluated whether TOF-MRA could assess cerebral hyperperfusion syndrome after superficial temporal artery-MCA anastomosis for this disease. This retrospective study included patients with Moyamoya disease who underwent superficial temporal artery-MCA single anastomosis. TOF-MRA and SPECT were performed before and 1-6 days after anastomosis. Bilateral ROIs on the source image of TOF-MRA were manually placed directly on the parietal branch of the superficial temporal artery just after branching the frontal branch of the superficial temporal artery and on the contralateral superficial temporal artery on the same axial image, respectively. The change ratio of the maximum signal intensity of the superficial temporal artery on TOF-MRA was calculated by using the following formula: (Postoperative Ipsilateral/Postoperative Contralateral)/(Preoperative Ipsilateral/Preoperative Contralateral). Of 23 patients (26 sides) who underwent the operation, 5 sides showed cerebral hyperperfusion syndrome postoperatively. There was a significant difference in the change ratio of signal intensity on TOF-MRA observed between the cerebral hyperperfusion syndrome and non-cerebral hyperperfusion syndrome groups (cerebral hyperperfusion syndrome group: 1.88 ± 0.32; non-cerebral hyperperfusion syndrome group: 1.03 ± 0.20; P = .0009). The minimum ratio value for the cerebral hyperperfusion syndrome group was 1.63, and the maximum ratio value for the non-cerebral hyperperfusion syndrome group was 1.30. Thus, no overlap was observed between the 2 groups for the change ratio of signal intensity on TOF-MRA. Diagnosis of cerebral hyperperfusion syndrome is indicated by an increase in the change ratio of signal intensity on TOF-MRA by more than approximately 1.5 times the preoperative levels. © 2016 by American Journal of Neuroradiology.

  8. Diagnostic Accuracy of Computer Tomography Angiography and Magnetic Resonance Angiography in the Stenosis Detection of Autologuous Hemodialysis Access: A Meta-Analysis

    PubMed Central

    Liu, Shiyuan

    2013-01-01

    Purpose To compare the diagnostic performances of computer tomography angiography (CTA) and magnetic resonance angiography (MRA) for detection and assessment of stenosis in patients with autologuous hemodialysis access. Materials and Methods Search of PubMed, MEDLINE, EMBASE and Cochrane Library database from January 1984 to May 2013 for studies comparing CTA or MRA with DSA or surgery for autologuous hemodialysis access. Eligible studies were in English language, aimed to detect more than 50% stenosis or occlusion of autologuous vascular access in hemodialysis patients with CTA and MRA technology and provided sufficient data about diagnosis performance. Methodological quality was assessed by the Quality Assessment of Diagnostic Studies (QUADAS) instrument. Sensitivities (SEN), specificities (SPE), positive likelihood ratio (PLR), negative likelihood values (NLR), diagnostic odds ratio (DOR) and areas under the receiver operator characteristic curve (AUC) were pooled statistically. Potential threshold effect, heterogeneity and publication bias was evaluated. The clinical utility of CTA and MRA in detection of stenosis was also investigated. Result Sixteen eligible studies were included, with a total of 500 patients. Both CTA and MRA were accurate modality (sensitivity, 96.2% and 95.4%, respectively; specificity, 97.1 and 96.1%, respectively; DOR [diagnostic odds ratio], 393.69 and 211.47, respectively) for hemodialysis vascular access. No significant difference was detected between the diagnostic performance of CTA (AUC, 0.988) and MRA (AUC, 0.982). Meta-regression analyses and subgroup analyses revealed no statistical difference. The Deek’s funnel plots suggested a publication bias. Conclusion Diagnostic performance of CTA and MRA for detecting stenosis of hemodialysis vascular access had no statistical difference. Both techniques may function as an alternative or an important complement to conventional digital subtraction angiography (DSA) and may be able to

  9. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Katsumori, Tetsuya, E-mail: katsumo@eurus.dti.ne.jp; Kasahara, Toshiyuki; Kin, Yoko

    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.more » 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.« less

  10. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Janka, R., E-mail: rolf.janka@idr.imed.uni-erlangen.de; Wenkel, E.; Fellner, C.

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

  11. 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.

  12. Prospective Heart Tracking for Whole-heart Magnetic Resonance Angiography

    PubMed Central

    Moghari, Mehdi H.; Geva, Tal; Powell, Andrew J.

    2015-01-01

    Purpose To develop a prospective respiratory-gating technique (Heart-NAV) for use with contrast-enhanced 3D inversion recovery (IR) whole-heart magnetic resonance angiography (MRA) acquisitions that directly tracks heart motion without creating image inflow artifact. Methods With Heart-NAV, 1 of the startup pulses for the whole-heart steady-state free precession MRA sequence is used to collect the centerline of k-space, and its 1-dimensional reconstruction is fed into the standard diaphragm-navigator (NAV) signal analysis process to prospectively gate and track respiratory-induced heart displacement. Ten healthy volunteers underwent non-contrast whole-heart MRA acquisitions using the conventional diaphragm-NAV and Heart-NAV with 5 and 10 mm acceptance windows in a 1.5T scanner. Five patients underwent contrast-enhanced IR whole-heart MRA using a diaphragm-NAV and Heart-NAV with a 5 mm acceptance window. Results For non-contrast whole-heart MRA with both the 5 and 10 mm acceptance windows, Heart-NAV yielded coronary artery vessel sharpness and subjective visual scores that were not significantly different than those using a conventional diaphragm-NAV. Scan time for Heart-NAV was 10% shorter (p<0.05). In patients undergoing contrast-enhanced IR whole-heart MRA, inflow artifact was seen with the diaphragm-NAV but not with Heart-NAV. Conclusion Compared to a conventional diaphragm-NAV, Heart-NAV achieves similar image quality in a slightly shorter scan time and eliminates inflow artifact. PMID:26843458

  13. Visualization and Classification of Deeply Seated Collateral Networks in Moyamoya Angiopathy with 7T MRI.

    PubMed

    Matsushige, T; Kraemer, M; Sato, T; Berlit, P; Forsting, M; Ladd, M E; Jabbarli, R; Sure, U; Khan, N; Schlamann, M; Wrede, K H

    2018-06-07

    Collateral networks in Moyamoya angiopathy have a complex angioarchitecture difficult to comprehend on conventional examinations. This study aimed to evaluate morphologic patterns and the delineation of deeply seated collateral networks using ultra-high-field MRA in comparison with conventional DSA. Fifteen white patients with Moyamoya angiopathy were investigated in this prospective trial. Sequences acquired at 7T were TOF-MRA with 0.22 × 0.22 × 0.41 mm 3 resolution and MPRAGE with 0.7 × 0.7 × 0.7 mm 3 resolution. Four raters evaluated the presence of deeply seated collateral networks and image quality in a consensus reading of DSA, TOF-MRA, and MPRAGE using a 5-point scale in axial source images and maximum intensity projections. Delineation of deeply seated collateral networks by different imaging modalities was compared by means of the McNemar test, whereas image quality was compared using the Wilcoxon signed-rank test. The relevant deeply seated collateral networks were classified into 2 categories and 6 pathways. A total of 100 collateral networks were detected on DSA; 106, on TOF-MRA; and 73, on MPRAGE. Delineation of deeply seated collateral networks was comparable between TOF-MRA and DSA ( P = .25); however, both were better than MPRAGE ( P < .001). This study demonstrates excellent delineation of 6 distinct deeply seated collateral network pathways in Moyamoya angiopathy in white adults using 7T TOF-MRA, comparable to DSA. © 2018 by American Journal of Neuroradiology.

  14. 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

    2018-04-01

    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.

  15. 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.

  16. Contrast-enhanced magnetic resonance angiography for the detection of crossing renal vessels in children with symptomatic ureteropelvic junction obstruction: comparison with operative findings.

    PubMed

    Calder, Alistair D; Hiorns, Melanie P; Abhyankar, Aruna; Mushtaq, Imran; Olsen, Oystein E

    2007-04-01

    Crossing renal vessels (CRV) are associated with ureteropelvic junction (UPJ) obstruction, particularly when presentation is beyond the neonatal period. Their presence may influence surgical management. To evaluate the accuracy of contrast-enhanced magnetic resonance angiography (CE-MRA) in the identification of CRV in children requiring surgical treatment of symptomatic UPJ obstruction, against a gold standard of laparoscopic or open surgical findings. We reviewed CE-MRA studies (3-D T2-weighted turbo spin-echo and multiphase 3-D spoiled gradient echo following intravenous gadolinium administration) of 14 children, age range 6-15 years, performed prior to surgery for suspected CRV-related UPJ obstruction. Consensus reviews of the CE-MRA studies were compared with surgical findings. CE-MRA demonstrated CRV at the level of the obstruction in nine and no crossing vessels in five children. These were all verified intraoperatively (chi2=14.0; P<0.001). In eight of the nine patients with CRV there was no evidence of intrinsic obstruction at surgery. In the remaining patient there was fibrosis of the upper ureter. CE-MRA is an accurate means of identifying CRV in children older than 6 years with symptomatic UPJ obstruction.

  17. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Joja, Ikuo; Asakawa, Mari; Motoyama, Kazumi

    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 obtainmore » 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« less

  18. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lakshminarayan, Raghuram, E-mail: raghuram.lakshminarayan@hey.nhs.u; Simpson, James O.; Ettles, Duncan F., E-mail: Duncan.Ettles@hey.nhs.u

    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 remainsmore » 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.« less

  19. Armed Conflict in Syria: Overview and U.S. Response

    DTIC Science & Technology

    2014-09-10

    MRA -OCO) and International Disaster Assistance (IDA-OCO) accounts. A further $155 million from the Economic Support Fund-Overseas Contingency...table does not show, $1.1 billion within Migration and Refugee Assistance ( MRA -OCO) and International Disaster Assistance (IDA-OCO) accounts

  20. Armed Conflict in Syria: Overview and U.S. Response

    DTIC Science & Technology

    2014-09-17

    support humanitarian response needs from the Migration and Refugee Assistance ( MRA -OCO) and International Disaster Assistance (IDA-OCO) accounts. A...and Refugee Assistance ( MRA -OCO) and International Disaster Assistance (IDA-OCO) accounts expected to be used for humanitarian assistance related to

  1. 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,...

  2. Automated analysis of heidelberg retina tomograph optic disc images by glaucoma probability score.

    PubMed

    Coops, Annemiek; Henson, David Barry; Kwartz, Anna J; Artes, Paul Habib

    2006-12-01

    To compare the diagnostic performance of the Heidelberg Retinal Tomograph's (HRT; Heidelberg Engineering GmbH, Dossenheim, Germany) glaucoma probability score (GPS), an automated, contour line-independent method of optic disc analysis with that of the Moorfields regression analysis (MRA). HRT images were obtained from one eye of 121 patients with glaucoma (median age, 70.2 years; median mean deviation [MD], -3.6 dB, range, +2.0 to -9.9 dB) and 95 healthy control subjects (median age, 59.7 years; median MD -0.1 dB, range +2.5 to -3.7). The diagnostic performances of GPS and MRA were evaluated by including borderline classifications, either as test negatives (most specific criteria) or as test positives (least specific criteria). Agreement between global and sectoral data of both analyses was established. Logistic regression analyses were performed to evaluate the effect of covariates such as optic disc size and age on the classification outcomes of both the GPS and the MRA. In 8 (7%) patients with glaucoma and 10 (11%) control subjects, the GPS failed to provide a complete global and sectoral optic disc classification. Although we could not identify a single distinct cause of this failure in the glaucoma group, failures in the control subjects occurred most often (7/10) with small and crowded optic discs. In subjects who were successfully classified at least globally by the GPS (117 patients with glaucoma, 88 control subjects), the diagnostic performances of GPS and MRA were similar (areas under the receiver operating characteristic [ROC] curve of 0.78 and 0.77, respectively; P > 0.1). With the GPS, sensitivity and specificity were 59% and 91% (most specific criteria) and 78% and 63% (least specific criteria), respectively. Combining GPS and MRA did not increase diagnostic performance significantly (ROC area of combined classifiers, 0.81). Both GPS and MRA were affected by disc size. In patients with glaucoma as well as healthy control subjects, the odds of a

  3. 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

  4. Optimisation of the microplate resazurin assay for screening and bioassay-guided fractionation of phytochemical extracts against Mycobacterium tuberculosis.

    PubMed

    O'Neill, Taryn E; Li, Haoxin; Colquhoun, Caitlyn D; Johnson, John A; Webster, Duncan; Gray, Christopher A

    2014-01-01

    Because of increased resistance to current drugs, there is an urgent need to discover new anti-mycobacterial compounds for the development of novel anti-tuberculosis drugs. The microplate resazurin assay (MRA) is commonly used to evaluate natural products and synthetic compounds for anti-mycobacterial activity. However, the assay can be problematic and unreliable when screening methanolic phytochemical extracts. To optimise the MRA for the screening and bioassay-guided fractionation of phytochemical extracts using Mycobacterium tuberculosis H37Ra. The effects of varying assay duration, resazurin solution composition, solvent (dimethyl sulphoxide - DMSO) concentration and type of microtitre plate used on the results and reliability of the MRA were investigated. The optimal bioassay protocol was applied to methanolic extracts of medicinal plants that have been reported to possess anti-mycobacterial activity. The variables investigated were found to have significant effects on the results obtained with the MRA. A standardised procedure that can reliably quantify anti-mycobacterial activity of phytochemical extracts in as little as 48 h was identified. The optimised MRA uses 2% aqueous DMSO, with an indicator solution of 62.5 µg/mL resazurin in 5% aqueous Tween 80 over 96 h incubation. The study has identified an optimal procedure for the MRA when used with M. tuberculosis H37Ra that gives rapid, reliable and consistent results. The assay procedure has been used successfully for the screening and bioassay-guided fractionation of anti-mycobacterial compounds from methanol extracts of Canadian medicinal plants. Copyright © 2014 John Wiley & Sons, Ltd.

  5. 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

  6. Prospective heart tracking for whole-heart magnetic resonance angiography.

    PubMed

    Moghari, Mehdi H; Geva, Tal; Powell, Andrew J

    2017-02-01

    To develop a prospective respiratory-gating technique (Heart-NAV) for use with contrast-enhanced three-dimensional (3D) inversion recovery (IR) whole-heart magnetic resonance angiography (MRA) acquisitions that directly tracks heart motion without creating image inflow artifact. With Heart-NAV, one of the startup pulses for the whole-heart steady-state free precession MRA sequence is used to collect the centerline of k-space, and its one-dimensional reconstruction is fed into the standard diaphragm-navigator (NAV) signal analysis process to prospectively gate and track respiratory-induced heart displacement. Ten healthy volunteers underwent non-contrast whole-heart MRA acquisitions using the conventional diaphragm-NAV and Heart-NAV with 5 and 10-mm acceptance windows in a 1.5T scanner. Five patients underwent contrast-enhanced IR whole-heart MRA using a diaphragm-NAV and Heart-NAV with a 5-mm acceptance window. For non-contrast whole-heart MRA with both the 5 and 10-mm acceptance windows, Heart-NAV yielded coronary artery vessel sharpness and subjective visual scores that were not significantly different than those using a conventional diaphragm-NAV. Scan time for Heart-NAV was 10% shorter (p < 0.05). In patients undergoing contrast-enhanced IR whole-heart MRA, inflow artifact was seen with the diaphragm-NAV but not with Heart-NAV. Compared with a conventional diaphragm-NAV, Heart-NAV achieves similar image quality in a slightly shorter scan time and eliminates inflow artifact. Magn Reson Med 77:759-765, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  7. 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.

  8. 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 R 1 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, R 1 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.

  9. 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.

  10. Magnetic resonance imaging with gadolinium arthrography to assess acetabular cartilage delamination.

    PubMed

    Zaragoza, Edward; Lattanzio, Pierre-Jean; Beaule, Paul E

    2009-01-01

    Recent reports have demonstrated magnetic resonance imaging (MRI) as a promising technique in detecting articular cartilage lesions of the hip joint. The purpose of our study was to evaluate the diagnostic performance of MRI with gadolinium arthrography in detecting acetabular cartilage delamination in patients with pre-arthritic hip pain. 46 patients (48 hips) underwent surgical dislocation of the hip. Mean age was 38.8 (range 17-56). There were 26 males and 20 females. All patients had Magnetic Resonance Imaging with gadolinium arthrography (MRA) before undergoing open hip surgery where the acetabular cartilage was inspected. Acetabular cartilage delamination on MRA was seen on sagittal images as a linear intra-articular filling defect of low signal intensity >1mm in thickness on T1 weighted images and surrounded by contrast. On MRA all hips had a labral tear confirmed at surgery. At surgery 30 hips had evidence of acetabular cartilage delamination, 4 hips had ulceration and 14 had no articular cartilage damage. The majority of labral tears and cartilage damage were located in the antero-superior quadrant. The sensitivity and specificity of MRA detection of cartilage delamination confirmed at surgery were 97% and 84%, respectively. The positive and negative predictive values of the MRA finding were 90% and 94%, respectively. The presence of the acetabular cartilage delamination represents an early stage of articular cartilage degeneration. When evaluating a young adult with hip pain, labral tears in association with cartilage delamination should be considered. MRA represents an effective diagnostic tool.

  11. Utility of 3-dimensional ultrasound imaging to evaluate carotid artery stenosis: comparison with magnetic resonance angiography.

    PubMed

    Igase, Keiji; Kumon, Yoshiaki; Matsubara, Ichiro; Arai, Masamori; Goishi, Junji; Watanabe, Hideaki; Ohnishi, Takanori; Sadamoto, Kazuhiko

    2015-01-01

    We evaluated the utility of 3-dimensional (3-D) ultrasound imaging for assessment of carotid artery stenosis, as compared with similar assessment via magnetic resonance angiography (MRA). Subjects comprised 58 patients with carotid stenosis who underwent both 3-D ultrasound imaging and MRA. We studied whether abnormal findings detected by ultrasound imaging could be diagnosed using MRA. Ultrasound images were generated using Voluson 730 Expert and Voluson E8. The degree of stenosis was mild in 17, moderate in 16, and severe in 25 patients, according to ultrasound imaging. Stenosis could not be recognized using MRA in 4 of 17 patients diagnosed with mild stenosis using ultrasound imaging. Ultrasound imaging showed ulceration in 13 patients and mobile plaque in 6 patients. When assessing these patients, MRA showed ulceration in only 2 of 13 patients and did not detect mobile plaque in any of these 6 patients. Static 3-D B mode images demonstrated distributions of plaque, ulceration, and mobile plaque, and static 3-D flow images showed flow configuration as a total structure. Real-time 3-D B mode images demonstrated plaque and vessel movement. Carotid artery stenting was not selected for patients diagnosed with ulceration or mobile plaque. Ultrasound imaging was necessary to detect mild stenosis, ulcerated plaque, or mobile plaque in comparison with MRA, and 3-D ultrasound imaging was useful to recognize carotid stenosis and flow pattern as a total structure by static and real-time 3-D demonstration. This information may contribute to surgical planning. Copyright © 2015 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  12. State-Level Immunization Information Systems: Potential for Childhood Immunization Data Linkages.

    PubMed

    Fuller, Jill E; Walter, Emmanuel B; Dole, Nancy; O'Hara, Richard; Herring, Amy H; Durkin, Maureen S; Specker, Bonny; Wey, Betty

    2017-01-01

    Objectives Sources of immunization data include state registries or immunization information systems (IIS), medical records, and surveys. Little is known about the quality of these data sources or the feasibility of using IIS data for research. We assessed the feasibility of collecting immunization information for a national children's health study by accessing existing IIS data and comparing the completeness of these data against medical record abstractions (MRA) and parent report. Staff time needed to obtain IIS and MRA data was assessed. Methods We administered a questionnaire to state-level IIS representatives to ascertain availability and completeness of their data for research and gather information about data formats. We evaluated quality of data from IIS, medical records, and reports from parents of 119 National Children's Study participants at three locations. Results IIS data were comparable to MRA data and both were more complete than parental report. Agreement between IIS and MRA data was greater than between parental report and MRA, suggesting IIS and MRA are better sources than parental report. Obtaining IIS data took less staff time than chart review, making IIS data linkage for research a preferred choice. Conclusions IIS survey results indicate data can be obtained by researchers using data linkages. IIS are an accessible and feasible child immunization information source and these registries reduce reliance on parental report or medical record abstraction. Researchers seeking to link IIS data with large multi-site studies should consider acquiring IIS data, but may need strategies to overcome barriers to data completeness and linkage.

  13. The Predictive Validity of the Minnesota Reading Assessment for Students in Postsecondary Vocational Education Programs.

    ERIC Educational Resources Information Center

    Brown, James M.; Chang, Gerald

    1982-01-01

    The predictive validity of the Minnesota Reading Assessment (MRA) when used to project potential performance of postsecondary vocational-technical education students was examined. Findings confirmed the MRA to be a valid predictor, although the error in prediction varied between the criterion variables. (Author/GK)

  14. Research Area 3: Mathematical Sciences: 3.4, Discrete Mathematics and Computer Science

    DTIC Science & Technology

    2015-06-10

    013-0043-1 Charles Chui, Hrushikesh Mhaskar. MRA contextual-recovery extension of smooth functions on manifolds, Applied and Computational Harmonic...753507. International Society for Optics and Photonics, 2010. [5] C. K. Chui and H. N. Mhaskar. MRA contextual-recovery extension of smooth functions on

  15. Classification of motor imagery tasks for BCI with multiresolution analysis and multiobjective feature selection.

    PubMed

    Ortega, Julio; Asensio-Cubero, Javier; Gan, John Q; Ortiz, Andrés

    2016-07-15

    Brain-computer interfacing (BCI) applications based on the classification of electroencephalographic (EEG) signals require solving high-dimensional pattern classification problems with such a relatively small number of training patterns that curse of dimensionality problems usually arise. Multiresolution analysis (MRA) has useful properties for signal analysis in both temporal and spectral analysis, and has been broadly used in the BCI field. However, MRA usually increases the dimensionality of the input data. Therefore, some approaches to feature selection or feature dimensionality reduction should be considered for improving the performance of the MRA based BCI. This paper investigates feature selection in the MRA-based frameworks for BCI. Several wrapper approaches to evolutionary multiobjective feature selection are proposed with different structures of classifiers. They are evaluated by comparing with baseline methods using sparse representation of features or without feature selection. The statistical analysis, by applying the Kolmogorov-Smirnoff and Kruskal-Wallis tests to the means of the Kappa values evaluated by using the test patterns in each approach, has demonstrated some advantages of the proposed approaches. In comparison with the baseline MRA approach used in previous studies, the proposed evolutionary multiobjective feature selection approaches provide similar or even better classification performances, with significant reduction in the number of features that need to be computed.

  16. [Preoperative assessment of renal vascular anatomy for donor nephrectomy: Is CT superior to MRI?].

    PubMed

    Arvin-Berod, A; Bricault, I; Terrier, N; Skowron, O; Cadi, P; Boillot, B; Thuillier, C; Cluze, C; Descotes, J-L; Rambeaud, J-J; Long, J-A

    2011-01-01

    computed tomography angiography (CTA) and magnetic resonance angiography (MRA) are both used in the preoperative assessment of vascular anatomy before donor nephrectomy. Our objective was to determine retrospectively and to compare the sensitivity of CTA and MRA imaging in preoperative renal vascularisation in living kidney donors. between 1999 and 2007, 42 kidney donors were assessed in our center: 27 by MRA, 10 by CTA, and five by both techniques. Images were interpreted using multiplanar reconstructions. Results were compared retrospectively with peroperative findings; discordant cases were re-examined by an experienced radiologist. Numbers of vessels detected with imaging methods was compared with numbers actually found at the operating time. MRA showed 35/43 arteries (Se 81.4 %) and 33/34 veins (Se 97.1 %), and CTA showed 18/18 arteries (Se 100 %) and 15/16 veins (Se 93.8 %). The presence of multiple arteries was detected in only one third of cases (3/9) on MRI scans; this difference was statistically significant. The missed arteries were not detected on second examination of the MRI scans with the knowledge of peroperative findings. MRA is less sensitive than CTA for preoperative vascularisation imaging in living renal donors, especially in the detection of multiple renal arteries. 2010 Elsevier Masson SAS. All rights reserved.

  17. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Meijne, E.I.; van der Winden-van Groenewegen, R.J.; Ploemacher, R.E.

    The sensitivity for x-irradiation of a series of hematopoietic stem cell populations has been determined. The most primitive cells identified, cells with marrow-repopulating ability (MRA), showed the highest degree of radioresistance. These MRA cells which generate many secondary day-twelve spleen colony-forming units (MRA(CFU-S-12)) or colony-forming units in culture (MRA(CFU-C)) in the marrow of primary recipients had Do values equal to 1.18 and 1.13 Gy, respectively. The more mature CFU-S-12 had intermediate radiosensitivity (Do = 0.94 Gy), whereas the less primitive CFU-S-7 were the most radiosensitive (Do = 0.71 Gy). The in vitro colony-forming precursor cells (CFU-C) showed low radiosensitivity. Thesemore » data clearly show that the most primitive hematopoietic stem cell measured is less sensitive to ionizing radiation than generally has been assumed on the basis of measurements on CFU-S-7 or CFU-S-12.« less

  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. [Autodermal plastics and transposition of musculus rectus abdominus for giant postoperative hernias].

    PubMed

    Ianov, V N

    2000-01-01

    For reduction of postoperative hernia relapses rate the technique of the autodermal plastics and transposition of musculus rectus abdominalis (MRA) was developed. This technique consists of two-sided transection of the lateral abdominal muscles (oblique and transverse) on the pararectal line, transposition of MRA together with their sheaths medially by autodermal continuous lacing to complete adaptation of the edges. Closing of the lateral muscle-aponeurotic defects was carried out with use of the double autodermal grafts which were prepared by Yanov's technique. This technique is indicated for giant postoperative hernias and pronounced diastase of the MRA in people with well developed abdominal muscles. This technique was used in 11 patients without complications after surgery. Long-term results are available for all the patients. The relapses were absent. The technique, developed by us, provides first of all restoration of physiological function of the MRA, and also closing of the abdominal wall muscle-aponeurotic defect.

  20. Non-enhanced MR imaging of cerebral aneurysms: 7 Tesla versus 1.5 Tesla.

    PubMed

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

    2014-01-01

    To prospectively evaluate 7 Tesla time-of-flight (TOF) magnetic resonance angiography (MRA) in comparison to 1.5 Tesla TOF MRA and 7 Tesla non-contrast enhanced magnetization-prepared rapid acquisition gradient-echo (MPRAGE) for delineation of unruptured intracranial aneurysms (UIA). Sixteen neurosurgical patients (male n = 5, female n = 11) with single or multiple UIA were enrolled in this trial. All patients were accordingly examined at 7 Tesla and 1.5 Tesla MRI utilizing dedicated head coils. The following sequences were obtained: 7 Tesla TOF MRA, 1.5 Tesla TOF MRA and 7 Tesla non-contrast enhanced MPRAGE. Image analysis was performed by two radiologists with regard to delineation of aneurysm features (dome, neck, parent vessel), presence of artifacts, vessel-tissue-contrast and overall image quality. Interobserver accordance and intermethod comparisons were calculated by kappa coefficient and Lin's concordance correlation coefficient. A total of 20 intracranial aneurysms were detected in 16 patients, with two patients showing multiple aneurysms (n = 2, n = 4). Out of 20 intracranial aneurysms, 14 aneurysms were located in the anterior circulation and 6 aneurysms in the posterior circulation. 7 Tesla MPRAGE imaging was superior over 1.5 and 7 Tesla TOF MRA in the assessment of all considered aneurysm and image quality features (e.g. image quality: mean MPRAGE7T: 5.0; mean TOF7T: 4.3; mean TOF1.5T: 4.3). Ratings for 7 Tesla TOF MRA were equal or higher over 1.5 Tesla TOF MRA for all assessed features except for artifact delineation (mean TOF7T: 4.3; mean TOF1.5T 4.4). Interobserver accordance was good to excellent for most ratings. 7 Tesla MPRAGE imaging demonstrated its superiority in the detection and assessment of UIA as well as overall imaging features, offering excellent interobserver accordance and highest scores for all ratings. Hence, it may bear the potential to serve as a high-quality diagnostic tool for pretherapeutic assessment and

  1. Non-Enhanced MR Imaging of Cerebral Aneurysms: 7 Tesla versus 1.5 Tesla

    PubMed Central

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

    2014-01-01

    Purpose To prospectively evaluate 7 Tesla time-of-flight (TOF) magnetic resonance angiography (MRA) in comparison to 1.5 Tesla TOF MRA and 7 Tesla non-contrast enhanced magnetization-prepared rapid acquisition gradient-echo (MPRAGE) for delineation of unruptured intracranial aneurysms (UIA). Material and Methods Sixteen neurosurgical patients (male n = 5, female n = 11) with single or multiple UIA were enrolled in this trial. All patients were accordingly examined at 7 Tesla and 1.5 Tesla MRI utilizing dedicated head coils. The following sequences were obtained: 7 Tesla TOF MRA, 1.5 Tesla TOF MRA and 7 Tesla non-contrast enhanced MPRAGE. Image analysis was performed by two radiologists with regard to delineation of aneurysm features (dome, neck, parent vessel), presence of artifacts, vessel-tissue-contrast and overall image quality. Interobserver accordance and intermethod comparisons were calculated by kappa coefficient and Lin's concordance correlation coefficient. Results A total of 20 intracranial aneurysms were detected in 16 patients, with two patients showing multiple aneurysms (n = 2, n = 4). Out of 20 intracranial aneurysms, 14 aneurysms were located in the anterior circulation and 6 aneurysms in the posterior circulation. 7 Tesla MPRAGE imaging was superior over 1.5 and 7 Tesla TOF MRA in the assessment of all considered aneurysm and image quality features (e.g. image quality: mean MPRAGE7T: 5.0; mean TOF7T: 4.3; mean TOF1.5T: 4.3). Ratings for 7 Tesla TOF MRA were equal or higher over 1.5 Tesla TOF MRA for all assessed features except for artifact delineation (mean TOF7T: 4.3; mean TOF1.5T 4.4). Interobserver accordance was good to excellent for most ratings. Conclusion 7 Tesla MPRAGE imaging demonstrated its superiority in the detection and assessment of UIA as well as overall imaging features, offering excellent interobserver accordance and highest scores for all ratings. Hence, it may bear the potential to serve as a high

  2. 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)

  3. Mineralocorticoid receptor antagonist pretreatment to MINIMISE reperfusion injury after ST-elevation myocardial infarction (the MINIMISE STEMI Trial): rationale and study design.

    PubMed

    Bulluck, Heerajnarain; Fröhlich, Georg M; Mohdnazri, Shah; Gamma, Reto A; Davies, John R; Clesham, Gerald J; Sayer, Jeremy W; Aggarwal, Rajesh K; Tang, Kare H; Kelly, Paul A; Jagathesan, Rohan; Kabir, Alamgir; Robinson, Nicholas M; Sirker, Alex; Mathur, Anthony; Blackman, Daniel J; Ariti, Cono; Krishnamurthy, Arvindra; White, Steven K; Meier, Pascal; Moon, James C; Greenwood, John P; Hausenloy, Derek J

    2015-05-01

    Novel therapies capable of reducing myocardial infarct (MI) size when administered prior to reperfusion are required to prevent the onset of heart failure in ST-segment elevation myocardial infarction (STEMI) patients treated by primary percutaneous coronary intervention (PPCI). Experimental animal studies have demonstrated that mineralocorticoid receptor antagonist (MRA) therapy administered prior to reperfusion can reduce MI size, and MRA therapy prevents adverse left ventricular (LV) remodeling in post-MI patients with LV impairment. With these 2 benefits in mind, we hypothesize that initiating MRA therapy prior to PPCI, followed by 3 months of oral MRA therapy, will reduce MI size and prevent adverse LV remodeling in STEMI patients. The MINIMISE-STEMI trial is a prospective, randomized, double-blind, placebo-controlled trial that will recruit 150 STEMI patients from four centers in the United Kingdom. Patients will be randomized to receive either an intravenous bolus of MRA therapy (potassium canrenoate 200 mg) or matching placebo prior to PPCI, followed by oral spironolactone 50 mg once daily or matching placebo for 3 months. A cardiac magnetic resonance imaging scan will be performed within 1 week of PPCI and repeated at 3 months to assess MI size and LV remodeling. Enzymatic MI size will be estimated by the 48-hour area-under-the-curve serum cardiac enzymes. The primary endpoint of the study will be MI size on the 3-month cardiac magnetic resonance imaging scan. The MINIMISE STEMI trial will investigate whether early MRA therapy, initiated prior to reperfusion, can reduce MI size and prevent adverse post-MI LV remodeling. © 2015 The Authors. Clinical Cardiology published by Wiley Periodicals, Inc.

  4. 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

  5. Estimating normative limits of Heidelberg Retina Tomograph optic disc rim area with quantile regression.

    PubMed

    Artes, Paul H; Crabb, David P

    2010-01-01

    To investigate why the specificity of the Moorfields Regression Analysis (MRA) of the Heidelberg Retina Tomograph (HRT) varies with disc size, and to derive accurate normative limits for neuroretinal rim area to address this problem. Two datasets from healthy subjects (Manchester, UK, n = 88; Halifax, Nova Scotia, Canada, n = 75) were used to investigate the physiological relationship between the optic disc and neuroretinal rim area. Normative limits for rim area were derived by quantile regression (QR) and compared with those of the MRA (derived by linear regression). Logistic regression analyses were performed to quantify the association between disc size and positive classifications with the MRA, as well as with the QR-derived normative limits. In both datasets, the specificity of the MRA depended on optic disc size. The odds of observing a borderline or outside-normal-limits classification increased by approximately 10% for each 0.1 mm(2) increase in disc area (P < 0.1). The lower specificity of the MRA with large optic discs could be explained by the failure of linear regression to model the extremes of the rim area distribution (observations far from the mean). In comparison, the normative limits predicted by QR were larger for smaller discs (less specific, more sensitive), and smaller for larger discs, such that false-positive rates became independent of optic disc size. Normative limits derived by quantile regression appear to remove the size-dependence of specificity with the MRA. Because quantile regression does not rely on the restrictive assumptions of standard linear regression, it may be a more appropriate method for establishing normative limits in other clinical applications where the underlying distributions are nonnormal or have nonconstant variance.

  6. Contrast material-enhanced, moving-table MR angiography versus digital subtraction angiography for surveillance of peripheral arterial bypass grafts.

    PubMed

    Loewe, Christian; Cejna, Manfred; Schoder, Maria; Loewe-Grgurin, Maria; Wolf, Florian; Lammer, Johannes; Thurnher, Siegfried A

    2003-09-01

    To assess the accuracy of moving-table MR angiography (MRA) in the evaluation of peripheral bypass grafts. There were 39 patients who had had peripheral bypass graft surgery and then subsequently underwent digital subtraction angiography (DSA) and contrast material-enhanced MRA, which was performed with moving-table software on a 1.0-T system before and during administration of 40 mL gadolinium. For evaluation, every bypass graft was divided into three parts and every leg into 14 segments. Disease severity was scored in four categories (0%-29%, 30%-69%, 70%-99%, 100%). Results were compared with those of the DSA. A total of 147 bypass graft segments and 938 vessel segments were classified. In 132 of the assessable 147 bypass segments, disease gradings with both methods were congruent; however, 13 stenoses were misinterpreted by MRA for one grade and two additional lesions by two grades, leading to an accuracy in precise stenoses detection of 89.9%. The sensitivity and specificity values in the detection of bypass graft stenoses >69% (grade 3 + 4 lesions) reached 90.0% and 98.3%, respectively. In 821 of 938 vessel segments the accuracy of MRA in stenoses detection reached 87.5%. The sensitivity and specificity values in the detection of grade 3 + 4 lesions were 95.6% and 94.0% for the native vessels, respectively. Moving-table MRA was as accurate in assessing bypass grafts as it was for the native arteries and showed a great accuracy in stenosis detection compared with DSA. Therefore, MRA is a promising modality for bypass graft surveillance and might be a noninvasive alternative to DSA in this regard.

  7. 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

  8. 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. © 2014 Wiley Periodicals, Inc.

  9. Varieties of Comprehension Measures: A Comparison of Intercorrelations among Several Reading Tests.

    ERIC Educational Resources Information Center

    Raygor, Alton L.; Flippo, Rona F.

    The procedures used to establish the validity of the Minnesota Reading Assessment (MRA) are described in this paper. The MRA is described as a measure designed for use with students in community colleges, business schools, technical schools, and other secondary and postsecondary training institutions in order to measure student competence in…

  10. 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.

  11. 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.

  12. Which cardiovascular magnetic resonance planes and sequences provide accurate measurements of branch pulmonary artery size in children with right ventricular outflow tract obstruction?

    PubMed

    Vijarnsorn, Chodchanok; Rutledge, Jennifer M; Tham, Edythe B; Coe, James Y; Quinonez, Luis; Patton, David J; Noga, Michelle

    2014-02-01

    Children with right ventricular outflow tract obstructive (RVOTO) lesions require precise quantification of pulmonary artery (PA) size for proper management of branch PA stenosis. We aimed to determine which cardiovascular magnetic resonance (CMR) sequences and planes correlated best with cardiac catheterization and surgical measurements of branch PA size. Fifty-five children with RVOTO lesions and biventricular circulation underwent CMR prior to; either cardiac catheterization (n = 30) or surgery (n = 25) within a 6 month time frame. CMR sequences included axial black blood, axial, coronal oblique and sagittal oblique cine balanced steady-state free precession (bSSFP), and contrast-enhanced magnetic resonance angiography (MRA) with multiplanar reformatting in axial, coronal oblique, sagittal oblique, and cross-sectional planes. Maximal branch PA and stenosis (if present) diameter were measured. Comparisons of PA size on CMR were made to reference methods: (1) catheterization measurements performed in the anteroposterior plane at maximal expansion, and (2) surgical measurement obtained from a maximal diameter sound which could pass through the lumen. The mean differences (Δ) and intra class correlation (ICC) were used to determine agreement between different modalities. CMR branch PA measurements were compared to the corresponding cardiac catheterization measurements in 30 children (7.6 ± 5.6 years). Reformatted MRA showed better agreement for branch PA measurement (ICC > 0.8) than black blood (ICC 0.4-0.6) and cine sequences (ICC 0.6-0.8). Coronal oblique MRA and maximal cross sectional MRA provided the best correlation of right PA (RPA) size with ICC of 0.9 (Δ -0.1 ± 2.1 mm and Δ 0.5 ± 2.1 mm). Maximal cross sectional MRA and sagittal oblique MRA provided the best correlate of left PA (LPA) size (Δ 0.1 ± 2.4 and Δ -0.7 ± 2.4 mm). For stenoses, the best correlations were from coronal oblique MRA of right pulmonary artery (RPA) (Δ -0.2 ± 0.8 mm, ICC 0

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

    ERIC Educational Resources Information Center

    Herington, Carmel; Weaven, Scott

    2007-01-01

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

  14. Cervical vertigo and dizziness after whiplash injury.

    PubMed

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

    2006-06-01

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

  15. The Islamic State Crisis and U.S. Policy

    DTIC Science & Technology

    2015-06-11

    Funding—The Administration is requesting $1.629 billion in Migration and Refugee Assistance-OCO ( MRA - OCO) and International Disaster Assistance-OCO...Programs (DoD) 715 600 1315 INCLE-OCO 11 10 21 PKO-OCO 65 65 FMF-OCO 250 50 300 ESF-OCO 50 160 277.4 487.4 MRA -OCO 819 819 IDA-OCO

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

    ERIC Educational Resources Information Center

    Pascucci, Stefano; De Magistris, Tiziana

    2011-01-01

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

  17. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bertoncello, I.; Hodgson, G.S.; Bradley, T.R.

    A multiparameter cell separative procedure is described that enables normal transplantable hemopoietic stem cells that preferentially home to the marrow of lethally irradiated mice to be enriched and separated from the majority of spleen colony-forming cells that are assayed 13 days after transplantation (CFU-S13). First, bone marrow cells are centrifuged in a discontinuous bovine serum albumin gradient. Low-density cells are harvested and labeled with the supravital cationic fluorochrome rhodamine 123 (Rh123). Labeled cells are analyzed using a fluorescence-activated cell sorter, and cells are sorted on the basis of relative Rh123 fluorescence within a predetermined forward versus 90 degrees red lightmore » scatter window that has been optimized for the recovery and enrichment of cells with marrow repopulating ability (MRA). Cells with MRA were characterized by relatively low Rh123 fluorescence and could be separated from a fraction that fluoresced more intensely and contained the majority of CFU-S13 but low MRA. Cells with platelet repopulating ability cofractionate with MRA whereas cells with erythroid repopulating ability remain associated with CFU-S13.« less

  18. GlcNAc-1-P-transferase–tunicamycin complex structure reveals basis for inhibition of N-glycosylation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yoo, Jiho; Mashalidis, Ellene H.; Kuk, Alvin C. Y.

    N-linked glycosylation is a predominant post-translational modification of protein in eukaryotes, and its dysregulation is the etiology of several human disorders. The enzyme UDP-N-acetylglucosamine:dolichyl-phosphate N-acetylglucosaminephosphotransferase (GlcNAc-1-P-transferase or GPT) catalyzes the first and committed step of N-linked glycosylation in the endoplasmic reticulum membrane, and it is the target of the natural product tunicamycin. Tunicamycin has potent antibacterial activity, inhibiting the bacterial cell wall synthesis enzyme MraY, but its usefulness as an antibiotic is limited by off-target inhibition of human GPT. Our understanding of how tunicamycin inhibits N-linked glycosylation and efforts to selectively target MraY are hampered by a lack of structuralmore » information. Here we present crystal structures of human GPT in complex with tunicamycin. In conclusion, structural and functional analyses reveal the difference between GPT and MraY in their mechanisms of inhibition by tunicamycin. We demonstrate that this difference could be exploited to design MraY-specific inhibitors as potential antibiotics.« less

  19. 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. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. 77 FR 65256 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-26

    ... FEDERAL AIRWAY V263 Is Amended To Read in Part HUGO, CO VOR/DME *LIMEX, CO FIX **10000 *10000--MRA **8500--MOCA **9000--GNSS MEA *LIMEX, CO FIX AKRON, CO VOR/DME....... **8500 *10000--MRA **7200--MOCA Sec. 95... V611 Is Amended To Read in Part JEFEL, CO FIX *LIMEX, CO FIX 85 00 [[Page 65260

  1. 12 CFR Appendix C to Subpart A of... - Appendix C to Subpart A of Part 327

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... (included in the Matters Requiring Attention, or MRA) of the bank's controls or administration of its asset... herein, provided the bank's PFR has not cited a criticism (included in the MRA) of the bank's controls or... reporting bank. (c) For all other C&I loans (whether term or non-revolver loans), the total amount of the...

  2. Advanced Noncontrast Magnetic Resonance Angiography of the Thoracic and Peripheral Arteries

    NASA Astrophysics Data System (ADS)

    Lindley, Marc Daniel

    The gold standard for evaluation of arterial disease using MR continues to be contrast-enhanced MR angiography (MRA) with gadolinium-based contrast agents (Gd-MRA). There has been a recent resurgence in interest in methods that do not rely on gadolinium for enhancement of blood vessels due to associations Gd-MRA has with nephrogenic systemic fibrosis (NSF) in patients with impaired renal function. The risk due to NSF has been shown to be minimized when selecting the appropriate contrast type and dose. Even though the risk of NSF has been shown to be minimized, demand for noncontrast MRA has continued to rise to reduce examination cost, and improve patient comfort and ability to repeat scans. Several methods have been proposed and used to perform angiography of the aorta and peripheral arteries without the use of gadolinium. These techniques have had limitations in transmit radiofrequency field (B1+) inhomogeneities, acquisition time, and specific hardware requirements, which have stunted the utility of noncontrast enhanced MRA. In this work feasibility of noncontrast (NC) MRA at 3T of the femoral arteries using dielectric padding, and using 3D radial stack of stars and compressed sensing to accelerate acquisitions in the abdomen and thorax were tested. Imaging was performed on 13 subjects in the pelvis and thighs using high permittivity padding, and 11 in the abdomen and 19 in the thorax using 3D radial stack of stars with tiny golden angle using gold standards or previously published techniques. Qualitative scores for each study were determined by radiologists who were blinded to acquisition type. Vessel conspicuity in the thigh and pelvis showed significant increase when high permittivity padding was used in the acquisition. No significant difference in image quality was observed in the abdomen and thorax when using undersampling, except for the descending aorta in thoracic imaging. All image quality scores were determined to be of diagnostic quality. In this

  3. Artefacts induced by coiled intracranial aneurysms on 3.0-Tesla versus 1.5-Tesla MR angiography--An in vivo and in vitro study.

    PubMed

    Schaafsma, Joanna D; Velthuis, Birgitta K; Vincken, Koen L; de Kort, Gerard A P; Rinkel, Gabriel J E; Bartels, Lambertus W

    2014-05-01

    To compare metal-induced artefacts from coiled intracranial aneurysms on 3.0-Tesla and 1.5-Tesla magnetic resonance angiography (MRA), since concerns persist on artefact enlargement at 3.0Tesla. We scanned 19 patients (mean age 53; 16 women) with 20 saccular aneurysms treated with coils only, at 1.5 and 3.0Tesla according to standard clinical 3D TOF-MRA protocols containing a shorter echo-time but weaker read-out gradient at 3.0Tesla in addition to intra-arterial digital subtraction angiography (IA-DSA). Per modality two neuro-radiologists assessed the occlusion status, measured residual flow, and indicated whether coil artefacts disturbed this assessment on MRA. We assessed relative risks for disturbance by coil artefacts, weighted kappa's for agreement on occlusion levels, and we compared remnant sizes. For artefact measurements, a coil model was created and scanned with the same protocols followed by 2D MR scans with variation of echo-time and read-out gradient strength. Coil artefacts disturbed assessments less frequently at 3.0Tesla than at 1.5Tesla (RR: 0.3; 95%CI: 0.1-0.8). On 3.0-Tesla MRA, remnants were larger than on 1.5-Tesla MRA (difference: 0.7mm; 95%CI: 0.3-1.1) and larger than on IA-DSA (difference: 1.0mm; 95%CI: 0.6-1.5) with similar agreement on occlusion levels with IA-DSA for both field strengths (κ 0.53; 95%CI: 0.23-0.84 for 1.5-Tesla MRA and IA-DSA; κ 0.47; 95%CI: 0.19-0.76 for 3.0-Tesla MRA and IA-DSA). Coil model artefacts were smaller at 3.0Tesla than at 1.5Tesla. The echo-time influenced artefact size more than the read-out gradient. Artefacts were not larger, but smaller at 3.0Tesla because a shorter echo-time at 3.0Tesla negated artefact enlargement. Despite smaller artefacts and larger remnants at 3.0Tesla, occlusion levels were similar for both field strengths. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  4. Role of non-contrast balanced steady-state free precession megnetic resonance angiography compared to contrast-enhanced megnetic resonance angiography in diagnosing renal artery stenosis: a meta-analysis.

    PubMed

    Tao, Weijing; Shen, Yang; Guo, Lili; Bo, Genji

    2014-01-01

    Balanced steady-state free precession MR angiography (b-SSFP MRA) has shown great promise in diagnosing renal artery stenosis (RAS) as a non-contrast MR angiography (NC-MRA) method. However, results from related studies are inconsistent. The purpose of this meta-analysis was to assess the accuracy of b-SSFP MRA compared to contrast-enhanced MR angiography (CE-MRA) in diagnosing RAS. English and Chinese studies that were published prior to September 4, 2013 and that assessed b-SSFP MRA diagnostic performance in RAS patients were reviewed. Quality of the literature was assessed independently by two observers. The statistical analysis was adopted by the software of Meta-Disc version 1.4. Using the heterogeneity test, a statistical effect model was chosen to calculate different pooled weighted values. The receiver operator characteristic (ROC) space and Spearman correlation coefficient were to explore threshold effect. Sensitivity analysis and the publication bias were performed to demonstrate if the pooled estimates were stable and reliable. We produced forest plots to calculate the pooled values and corresponding 95% confidence interval (CI) of sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and constructed a summary receiver operating characteristic curve (SROC) to calculate the area under the curve (AUC). A total of 10 high quality articles were used in this meta-analysis. The studies showed a high degree of heterogeneity. The "shoulder-arm" shape in the ROC plot and the Spearman correlation coefficient between the log(SEN) and log(1-SPE) suggested that there was a threshold effect. Sensitivity analysis demonstrated that the actual combined effect size was equal to the theoretical combined effect size. The publication bias was low after quality evaluation of the literature and the construction of a funnel plot. The pooled sensitivity was 0.88 (95% CI, 0.83-0.91) and pooled specificity was 0

  5. 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.

  6. Comparison of 3D computer-aided with manual cerebral aneurysm measurements in different imaging modalities.

    PubMed

    Groth, M; Forkert, N D; Buhk, J H; Schoenfeld, M; Goebell, E; Fiehler, J

    2013-02-01

    To compare intra- and inter-observer reliability of aneurysm measurements obtained by a 3D computer-aided technique with standard manual aneurysm measurements in different imaging modalities. A total of 21 patients with 29 cerebral aneurysms were studied. All patients underwent digital subtraction angiography (DSA), contrast-enhanced (CE-MRA) and time-of-flight magnetic resonance angiography (TOF-MRA). Aneurysm neck and depth diameters were manually measured by two observers in each modality. Additionally, semi-automatic computer-aided diameter measurements were performed using 3D vessel surface models derived from CE- (CE-com) and TOF-MRA (TOF-com) datasets. Bland-Altman analysis (BA) and intra-class correlation coefficient (ICC) were used to evaluate intra- and inter-observer agreement. BA revealed the narrowest relative limits of intra- and inter-observer agreement for aneurysm neck and depth diameters obtained by TOF-com (ranging between ±5.3 % and ±28.3 %) and CE-com (ranging between ±23.3 % and ±38.1 %). Direct measurements in DSA, TOF-MRA and CE-MRA showed considerably wider limits of agreement. The highest ICCs were observed for TOF-com and CE-com (ICC values, 0.92 or higher for intra- as well as inter-observer reliability). Computer-aided aneurysm measurement in 3D offers improved intra- and inter-observer reliability and a reproducible parameter extraction, which may be used in clinical routine and as objective surrogate end-points in clinical trials.

  7. Effects of mineralocorticoid receptor antagonists on the progression of diabetic nephropathy.

    PubMed

    Sun, Li-Jing; Sun, Yan-Ni; Shan, Jian-Ping; Jiang, Geng-Ru

    2017-07-01

    We aimed to evaluate the potential benefits and adverse effects of adding a mineralocorticoid receptor antagonist (MRA) to angiotensin-converting enzyme inhibitors (ACEI) and/or angiotensin receptor blockers (ARB), as standard treatment in patients with diabetic nephropathy. We scanned the Embase, PubMed and Cochrane Central Register of Controlled Trials databases for human clinical trials published in English until June 2016, evaluating renal outcomes in patients with diabetic nephropathy. A total of 18 randomized controlled trials involving 1,786 patients were included. Compared with ACEI/ARB alone, co-administration of MRA and ACEI/ARB significantly reduced urinary albumin excretion and the urinary albumin-creatinine ratio (mean difference -69.38, 95% confidence intervals -103.53 to -35.22, P < 0.0001; mean difference -215.74, 95% confidence intervals -409.22 to -22.26, P = 0.03, respectively). A decrease of blood pressure was also found in the co-administration of MRA and ACEI/ARB groups. However, we did not observe any improvement in the glomerular filtration rate. There was a significant increase in the risk of hyperkalemia on the addition of MRA to ACEI/ARB treatment (relative risk 3.74, 95% confidence intervals 2.30-6.09, P < 0.00001). These findings suggest that co-administration of MRA and ACEI/ARB has beneficial effects on renal outcomes with increasing the incidence of hyperkalemia. © 2017 The Authors. Journal of Diabetes Investigation published by Asian Association for the Study of Diabetes (AASD) and John Wiley & Sons Australia, Ltd.

  8. Assessment of carotid stenosis using three-dimensional T2-weighted dark blood imaging: Initial experience.

    PubMed

    Mihai, Georgeta; Winner, Marshall W; Raman, Subha V; Rajagopalan, Sanjay; Simonetti, Orlando P; Chung, Yiu-Cho

    2012-02-01

    To evaluate the use of a T2-weighted SPACE sequence (T2w-SPACE) to assess carotid stenosis via several methods and compare its performance with contrast-enhanced magnetic resonance angiography (ceMRA). Fifteen patients with carotid atherosclerosis underwent dark blood (DB)-MRI using a 3D turbo spin echo with variable flip angles sequence (T2w-SPACE) and ceMRA. Images were coregistered and evaluated by two observers. Comparisons were made for luminal diameter, luminal area, degree of luminal stenosis (NASCET: North American Symptomatic Endarterectomy Trial; ECST: European Carotid Surgery Trial, and area stenosis), and vessel wall area. Degree of NASCET stenosis was clinically classified as mild (<50%), moderate (50%-69%), or severe (>69%). Excellent agreement was seen between ceMRA and T2w-SPACE and between observers for assessment of lumen diameter, lumen area, vessel wall area, and degree of NASCET stenosis (r > 0.80, P < 0.001). ECST stenosis was consistently higher than NASCET stenosis (48 ± 14% vs. 24 ± 22%, P < 0.001). Area stenosis (72 ± 2%) was significantly higher (P < 0.001) than both ESCT and NASCET stenosis. DB-MRI of carotid arteries using T2w-SPACE is clinically feasible. It provides accurate measurements of lumen size and degree of stenosis in comparison with ceMRA and offers a more reproducible measure of ECST stenosis than ceMRA. Copyright © 2011 Wiley Periodicals, Inc.

  9. 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

  10. Evolutionary Capability Delivery of Coast Guard Manpower System

    DTIC Science & Technology

    2014-06-01

    Office IID iterative incremental development model IT information technology MA major accomplishment MRA manpower requirements analysis MRD manpower...CG will need to ensure that development is low risk. The CG uses Manpower Requirements Analysis ( MRAs ) to collect the necessary manpower data to...of users. The CG uses two business processes to manage human capital: Manpower Requirements Analysis ( MRA ) and Manpower Requirements

  11. What MRI Findings Predict Failure 10 Years After Surgery for Femoroacetabular Impingement?

    PubMed

    Hanke, Markus S; Steppacher, Simon D; Anwander, Helen; Werlen, Stefan; Siebenrock, Klaus A; Tannast, Moritz

    2017-04-01

    Magnetic resonance arthrogram (MRA) with radial cuts is presently the best available preoperative imaging study to evaluate chondrolabral lesions in the setting of femoroacetabular impingement (FAI). Existing followup studies for surgical treatment of FAI have evaluated predictors of treatment failure based on preoperative clinical examination, intraoperative findings, and conventional radiography. However, to our knowledge, no study has examined whether any preoperative findings on MRA images might be associated with failure of surgical treatment of FAI in the long term. The purposes of this study were (1) to identify the preoperative MRA findings that are associated with conversion to THA, any progression of osteoarthritis, and/or a Harris hip score of < 80 points after acetabuloplasty and/or osteochondroplasty of the femoral head-neck junction through a surgical hip dislocation (SHD) for FAI at a minimum 10-year followup; and (2) identify the age of patients with symptomatic FAI when these secondary degenerative findings were detected on preoperative radial MRAs. We retrospectively studied 121 patients (146 hips) who underwent acetabuloplasty and/or osteochondroplasty of the femoral head-neck junction through SHD for symptomatic anterior FAI between July 2001 and March 2003. We excluded 35 patients (37 hips) with secondary FAI after previous surgery and 11 patients (12 hips) with Legg-Calvé-Perthes disease. All patients underwent preoperative MRA to further specify chondrolabral lesions except in 19 patients (32 hips) including 17 patients (20 hips) who presented with an MRI from an external institution taken with a different protocol, 10 patients with no preoperative MRA because the patients had already been operated on the contralateral side with a similar appearance, and two patients (two hips) refused MRA because of claustrophobia. This resulted in 56 patients (65 hips) with idiopathic FAI and a preoperative MRA. Of those, three patients (three hips) did

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  13. Endothelial dysfunction in rat mesenteric resistance artery after transient middle cerebral artery occlusion.

    PubMed

    Martinez-Revelles, Sonia; Jiménez-Altayó, Francesc; Caracuel, Laura; Pérez-Asensio, Fernando J; Planas, Anna M; Vila, Elisabet

    2008-05-01

    Stroke triggers a local and systemic inflammatory response leading to the production of cytokines that can influence blood vessel reactivity. In this study, we aimed to assess whether cerebral ischemia/reperfusion could affect vasoconstriction and vasodilatation on mesenteric resistance arteries (MRA) from Wistar Kyoto rats. The right middle cerebral artery was occluded (90 min) and reperfused (24 h). Sham-operated animals were used as controls. Plasma levels of interleukin (IL)-6 and IL-1beta were measured at 24 h. Vasoconstrictor and vasodilator responses were recorded in a wire myograph. Protein expression was determined by Western blot and immunofluorescence, and superoxide anion (O(2)(.)) production was evaluated by ethidium fluorescence. In MRA, ischemia/reperfusion increased plasma levels of IL-6, O2. production, protein expression of cyclooxygenase-2, and protein tyrosine nitrosylation, but it impaired acetylcholine (ACh) vasodilatation without modifying the vasodilatations to sodium nitroprusside or the contractions to phenylephrine and KCl. Superoxide dismutase (SOD) and indomethacin reversed the impairment of ACh relaxation induced by ischemia/reperfusion. However, N(omega)-nitro-l-arginine methyl ester affected similarly ACh-induced vasodilatations in MRA of ischemic and sham-operated rats. Protein expression of endothelial and inducible nitric-oxide synthase, copper/zinc SOD, manganese SOD, and extracellular SOD was similar in both groups of rats. Our results show MRA endothelial dysfunction 24 h after brain ischemia/reperfusion. Excessive production of O2. in MRA mediates endothelial dysfunction, and the increase in plasma cytokine levels after brain ischemia/reperfusion might be involved in this effect.

  14. Evaluation of takayasu arteritis with delayed contrast-enhanced MR imaging by a free-breathing 3D IR turbo FLASH.

    PubMed

    Liu, Min; Liu, Weifang; Li, Haoyuan; Shu, Xiaoming; Tao, Xincao; Zhai, Zhenguo

    2017-12-01

    The primary aim of our case-control study was to observe delayed contrast-enhanced magnetic resonance imaging (DCE-MRI) in patients with Takayasu arteritis (TA) in comparison with magnetic resonance angiography (MRA). Twenty-seven patients including 15 with active TA and 12 with stable TA who underwent both aortic MRA and DCE-MRI were included. A total of 27 sex- and age-matched healthy volunteers were enrolled as the control group. MRA were obtained with T1WI-volume-interpolated breath-hold examination sequence or fast low-angle shot (FLASH) sequence. DCE-MRI was acquired with a free-breathing three-dimensional inversion recovery Turbo fast low-angle shot (3D IR Turbo FLASH). Neither stenosis nor delayed enhancement of arterial wall was shown in the control group. In patients with stable TA, arterial stenosis was observed on MRA. On DCE-MR, delayed enhancement of arterial walls could be observed in the active TA group but not in the stable TA group or the control group. Stenotic arteries on MRA were comparable in the active TA and stable TA (χ = 2.70, P = .259); however, delayed enhancement of arterial walls in the active-TA group were more than those in the stable group (χ = 27.00, P < .001). Our results suggest that DCE-MRI with the free-breathing 3D IR Turbo FLASH sequence could assess TA and delayed enhancement on DCE-MRI is one characteristics of the active TA. Copyright © 2017 The Authors. Published by Wolters Kluwer Health, Inc. All rights reserved.

  15. The diagnostic test accuracy of magnetic resonance imaging, magnetic resonance arthrography and computer tomography in the detection of chondral lesions of the hip.

    PubMed

    Smith, Toby O; Simpson, Michael; Ejindu, Vivian; Hing, Caroline B

    2013-04-01

    The purpose of this study was to assess the diagnostic test accuracy of magnetic resonance imaging (MRI), magnetic resonance arthrography (MRA) and multidetector arrays in CT arthrography (MDCT) for assessing chondral lesions in the hip joint. A review of the published and unpublished literature databases was performed to identify all studies reporting the diagnostic test accuracy (sensitivity/specificity) of MRI, MRA or MDCT for the assessment of adults with chondral (cartilage) lesions of the hip with surgical comparison (arthroscopic or open) as the reference test. All included studies were reviewed using the quality assessment of diagnostic accuracy studies appraisal tool. Pooled sensitivity, specificity, likelihood ratios and diagnostic odds ratios were calculated with 95 % confidence intervals using a random-effects meta-analysis for MRI, MRA and MDCT imaging. Eighteen studies satisfied the eligibility criteria. These included 648 hips from 637 patients. MRI indicated a pooled sensitivity of 0.59 (95 % CI: 0.49-0.70) and specificity of 0.94 (95 % CI: 0.90-0.97), and MRA sensitivity and specificity values were 0.62 (95 % CI: 0.57-0.66) and 0.86 (95 % CI: 0.83-0.89), respectively. The diagnostic test accuracy for the detection of hip joint cartilage lesions is currently superior for MRI compared with MRA. There were insufficient data to perform meta-analysis for MDCT or CTA protocols. Based on the current limited diagnostic test accuracy of the use of magnetic resonance or CT, arthroscopy remains the most accurate method of assessing chondral lesions in the hip joint.

  16. Accuracy of magnetic resonance imaging, magnetic resonance arthrography and computed tomography for the detection of chondral lesions of the knee.

    PubMed

    Smith, Toby O; Drew, Benjamin T; Toms, Andoni P; Donell, Simon T; Hing, Caroline B

    2012-12-01

    To assess the diagnostic test accuracy of magnetic resonance imaging (MRI), magnetic resonance arthrography (MRA) and computed tomography arthrography (CTA) for the detection of chondral lesions of the patellofemoral and tibiofemoral joints. A review of published and unpublished literature sources was conducted on 22nd September 2011. All studies assessing the diagnostic test accuracy (sensitivity/specificity) of MRI or MRA or CTA for the assessment of adults with chondral (cartilage) lesions of the knee (tibiofemoral/patellofemoral joints) with surgical comparison (arthroscopic or open) as the reference test were included. Data were analysed through meta-analysis. Twenty-seven studies assessing 2,592 knees from 2,509 patients were included. The findings indicated that whilst presenting a high specificity (0.95-0.99), the sensitivity of MRA, MRI and CTA ranged from 0.70 to 0.80. MRA was superior to MRI and CTA for the detection of patellofemoral joint chondral lesions and that higher field-strength MRI scanner and grade four lesions were more accurately detected compared with lower field-strength and grade one lesions. There appeared no substantial difference in diagnostic accuracy between the interpretation from musculoskeletal and general radiologists when undertaking an MRI review of tibiofemoral and patellofemoral chondral lesions. Specialist radiological imaging is specific for cartilage disease in the knee but has poorer sensitivity to determine the therapeutic options in this population. Due to this limitation, there remains little indication to replace the 'gold-standard' arthroscopic investigation with MRI, MRA or CTA for the assessment of adults with chondral lesions of the knee. II.

  17. 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. Copyright © 2017 by the Congress of Neurological Surgeons

  18. 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. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  19. High-resolution magnetic resonance angiography of the lower extremities with a dedicated 36-element matrix coil at 3 Tesla.

    PubMed

    Kramer, Harald; Michaely, Henrik J; Matschl, Volker; Schmitt, Peter; Reiser, Maximilian F; Schoenberg, Stefan O

    2007-06-01

    Recent developments in hard- and software help to significantly increase image quality of magnetic resonance angiography (MRA). Parallel acquisition techniques (PAT) help to increase spatial resolution and to decrease acquisition time but also suffer from a decrease in signal-to-noise ratio (SNR). The movement to higher field strength and the use of dedicated angiography coils can further increase spatial resolution while decreasing acquisition times at the same SNR as it is known from contemporary exams. The goal of our study was to compare the image quality of MRA datasets acquired with a standard matrix coil in comparison to MRA datasets acquired with a dedicated peripheral angio matrix coil and higher factors of parallel imaging. Before the first volunteer examination, unaccelerated phantom measurements were performed with the different coils. After institutional review board approval, 15 healthy volunteers underwent MRA of the lower extremity on a 32 channel 3.0 Tesla MR System. In 5 of them MRA of the calves was performed with a PAT acceleration factor of 2 and a standard body-matrix surface coil placed at the legs. Ten volunteers underwent MRA of the calves with a dedicated 36-element angiography matrix coil: 5 with a PAT acceleration of 3 and 5 with a PAT acceleration factor of 4, respectively. The acquired volume and acquisition time was approximately the same in all examinations, only the spatial resolution was increased with the acceleration factor. The acquisition time per voxel was calculated. Image quality was rated independently by 2 readers in terms of vessel conspicuity, venous overlay, and occurrence of artifacts. The inter-reader agreement was calculated by the kappa-statistics. SNR and contrast-to-noise ratios from the different examinations were evaluated. All 15 volunteers completed the examination, no adverse events occurred. None of the examinations showed venous overlay; 70% of the examinations showed an excellent vessel conspicuity

  20. Simultaneous acquisition of perfusion image and dynamic MR angiography using time‐encoded pseudo‐continuous ASL

    PubMed Central

    Helle, Michael; Koken, Peter; Van Cauteren, Marc; van Osch, Matthias J. P.

    2017-01-01

    Purpose Both dynamic magnetic resonance angiography (4D‐MRA) and perfusion imaging can be acquired by using arterial spin labeling (ASL). While 4D‐MRA highlights large vessel pathology, such as stenosis or collateral blood flow patterns, perfusion imaging provides information on the microvascular status. Therefore, a complete picture of the cerebral hemodynamic condition could be obtained by combining the two techniques. Here, we propose a novel technique for simultaneous acquisition of 4D‐MRA and perfusion imaging using time‐encoded pseudo‐continuous arterial spin labeling. Methods The time‐encoded pseudo‐continuous arterial spin labeling module consisted of a first subbolus that was optimized for perfusion imaging by using a labeling duration of 1800 ms, whereas the other six subboli of 130 ms were used for encoding the passage of the labeled spins through the arterial system for 4D‐MRA acquisition. After the entire labeling module, a multishot 3D turbo‐field echo‐planar‐imaging readout was executed for the 4D‐MRA acquisition, immediately followed by a single‐shot, multislice echo‐planar‐imaging readout for perfusion imaging. The optimal excitation flip angle for the 3D turbo‐field echo‐planar‐imaging readout was investigated by evaluating the image quality of the 4D‐MRA and perfusion images as well as the accuracy of the estimated cerebral blood flow values. Results When using 36 excitation radiofrequency pulses with flip angles of 5 or 7.5°, the saturation effects of the 3D turbo‐field echo‐planar‐imaging readout on the perfusion images were relatively moderate and after correction, there were no statistically significant differences between the obtained cerebral blood flow values and those from traditional time‐encoded pseudo‐continuous arterial spin labeling. Conclusions This study demonstrated that simultaneous acquisition of 4D‐MRA and perfusion images can be achieved by using time‐encoded pseudo

  1. Hydronephrosis by an Aberrant Renal Artery: A Case Report

    PubMed Central

    Park, Byoung Seok; Jeong, Taek Kyun; Ma, Seong Kwon; Kim, Soo Wan; Kim, Nam Ho; Choi, Ki Chul; Jeong, Yong Yeon

    2003-01-01

    Ureteropelvic junction obstruction is usually intrinsic and is most common in children. Aberrant renal arteries are present in about 30% of individuals. Aberrant renal arteries to the inferior pole cross anteriorly to the ureter and may cause hydronephrosis. To the best of our knowledge, although there are some papers about aberrant renal arteries producing ureteropelvic junction obstruction, there is no report of a case which is diagnosed by the new modalities, such as computed tomography angiogram (CTA) or magnetic resonance angiogram (MRA). We describe a 36-year-old woman with right hydronephrosis. Kidney ultrasonogram and excretory urogram revealed right hydronephrosis. CTA and MRA clearly displayed an aberrant renal artery and hydronephrosis. The patient underwent surgical exploration. For the evaluation of hydronephrosis by an aberrant renal artery, use of CTA and MRA is advocated. PMID:12760271

  2. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schuermann, Karl; Vorwerk, Dierk; Buecker, Arno

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

  3. Greater Rupture Risk for Familial as Compared to Sporadic Unruptured Intracranial Aneurysms

    PubMed Central

    Broderick, Joseph P.; Brown, Robert D.; Sauerbeck, Laura; Hornung, Richard; Huston, John; Woo, Daniel; Anderson, Craig; Rouleau, Guy; Kleindorfer, Dawn; Flaherty, Matthew L.; Meissner, Irene; Foroud, Tatiana; Moomaw, E. Charles J.; Connolly, E. Sander

    2009-01-01

    Background The risk of intracranial aneurysm (IA) rupture in asymptomatic members of families who have multiple affected individuals is not known. Methods First-degree unaffected relatives of those with a familial history of IA who had a history of smoking or hypertension but no known IA were offered cerebral magnetic resonance angiography (MRA) and followed yearly as part of an NINDS-funded study of familial IA (FIA Study). Results 2874 subjects from 542 FIA families were enrolled. After study enrollment, MRAs were performed in 548 FIA family members with no known history of IA. Of these 548 subjects, 113 subjects (20.6%) had 148 IAs by MRA of whom 5 subjects had IA >= 7 mm. Two subjects with an unruptured IA by MRA/CTA (3 mm and 4mm ACOM) subsequently had rupture of their IA. This represents an annual rate of 1.2 ruptures per 100 subjects (1.2% per year, 95% CI of 0.14% to 4.3% per year). None of the 435 subjects with a negative MRA have had a ruptured IA. Survival curves between the MRA positive and negative cohorts were significantly different (p = 0.004). This rupture rate of unruptured IA in the FIA cohort of 1.2% per year is approximately 17 times higher than the rupture rate for subjects with an unruptured IA in the International Study of Unruptured Aneurysm Study with a matched distribution of IA size and location - 0.069% per year. Conclusions Small unruptured IAs in patients from FIA families may have a higher risk of rupture than sporadic unruptured IAs of similar size, which should be considered in the management of these patients. PMID:19228834

  4. Non-contrast 3D time-of-flight magnetic resonance angiography for visualization of intracranial aneurysms in patients with absolute contraindications to CT or MRI contrast.

    PubMed

    Yanamadala, Vijay; Sheth, Sameer A; Walcott, Brian P; Buchbinder, Bradley R; Buckley, Deidre; Ogilvy, Christopher S

    2013-08-01

    The preoperative evaluation of patients with intracranial aneurysms typically includes a contrast-enhanced vascular study, such as computed tomography angiography (CTA), magnetic resonance angiography (MRA), or digital subtraction angiography. However, there are numerous absolute and relative contraindications to the administration of imaging contrast agents, including pregnancy, severe contrast allergy, and renal insufficiency. Evaluation of patients with contrast contraindications thus presents a unique challenge. We identified three patients with absolute contrast contraindications who presented with intracranial aneurysms. One patient was pregnant, while the other two had previous severe anaphylactic reactions to iodinated contrast. Because of these contraindications to intravenous contrast, we performed non-contrast time-of-flight MRA with 3D reconstruction (TOF MRA with 3DR) with maximum intensity projections and volume renderings as part of the preoperative evaluation prior to successful open surgical clipping of the aneurysms. In the case of one paraclinoid aneurysm, a high-resolution non-contrast CT scan was also performed to assess the relationship of the aneurysm to the anterior clinoid process. TOF MRA with 3DR successfully identified the intracranial aneurysms and adequately depicted the surrounding microanatomy. Intraoperative findings were as predicted by the preoperative imaging studies. The aneurysms were successfully clip-obliterated, and the patients had uneventful post-operative courses. These cases demonstrate that non-contrast imaging is a viable modality to assess intracranial aneurysms as part of the surgical planning process in patients with contrast contraindications. TOF MRA with 3DR, in conjunction with high-resolution non-contrast CT when indicated, provides adequate visualization of the microanatomy of the aneurysm and surrounding structures. Copyright © 2013 Elsevier Ltd. All rights reserved.

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

    PubMed

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

    2004-09-01

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

  6. A real-world cohort study on the quality of potassium and creatinine monitoring during initiation of mineralocorticoid receptor antagonists in patients with heart failure.

    PubMed

    Nilsson, Erik; De Deco, Pietro; Trevisan, Marco; Bellocco, Rino; Lindholm, Bengt; Lund, Lars H; Coresh, Josef; Carrero, Juan J

    2018-05-02

    Clinical heart failure (HF) guidelines recommend monitoring of creatinine and potassium throughout the initial weeks of mineralocorticoid receptor antagonists (MRAs) therapy. We here assessed the extent to which this occurs in our healthcare. Observational study in 2007-2010 HF patients starting MRA therapy in Stockholm, Sweden. Outcomes included potassium and creatinine laboratory testing before MRA initiation and in the early (days 1-10) and extended (days 11-90) post-initiation periods. Exclusion criteria considered death/hospitalization within 90 days, and lack of a second MRA dispense. Of 4,036 HF patients starting on MRA, 45% were initiated from a hospital, 24% from a primary care center and 30% from other private centers. Overall, 89% underwent pre-initiation testing, being more common among hospital (97%) than for primary care (74%) initiations. Only 24% were adequately monitored in all three recommended intervals, being again more frequent following hospital (33%) than private (21%) or primary care (17%) initiations. In multivariable analyses, adequate monitoring was more likely for hospital [odds ratio (OR), 95% confidence interval; 2.85, 2.34-3.56] initiations, and for patients with chronic kidney disease (OR 1.79, 1.30-2.43) and concomitant use of ACE (OR 1.27, 1.05-1.52), ARBs (OR 1.19, 1.01-1.40) or beta blockers (OR 1.65, 1.22-2.26). Age, sex and prescribing center explained a small portion of adequate monitoring (c-statistic, 0.63). Addition of comorbidities and medications improved prediction marginally (c-statistic, 0.65). Although serum potassium and creatinine monitoring before MRA initiation for HF is frequent, rates of post-initiation monitoring remain suboptimal, especially among primary care centers.

  7. In vitro stent lumen visualisation of various common and newly developed femoral artery stents using MR angiography at 1.5 and 3 tesla.

    PubMed

    Syha, R; Ketelsen, D; Kaempf, M; Mangold, S; Sixt, S; Zeller, T; Springer, F; Schick, F; Claussen, C D; Brechtel, K

    2013-02-01

    To evaluate stent lumen assessment of various commonly used and newly developed stents for the superficial femoral artery (SFA) using MR angiography (MRA) at 1.5 and 3 T. Eleven nitinol stents and one cobalt-chromium stent were compared regarding stent lumen visualisation using a common three-dimensional MRA sequence. Maximum visible stent lumen width and contrast ratio were analysed in three representative slices for each stent type. A scoring system for lumen visualisation was applied. Nitinol stents showed significantly better performance than the cobalt chromium stent (P < 0.05) at 1.5 and 3 T. Maximum visible stent lumen ranged between 43.4 and 95.5 %, contrast ratio between 7.2 and 110.6 %. Regarding both field strengths, seven of the nitinol stents were classified as "suitable". Three nitinol stents were "limited", and one nitinol stent and the cobalt chromium stent were "not suitable". Intraluminal loss of signal and artefacts of most of the SFA stents do not markedly limit assessment of stent lumen by MRA at 1.5 and 3 T. MRA can thus be considered a valid technique for detection of relevant in-stent restenosis. Applied field strength does not strongly influence stent lumen assessment in general, but proper choice of field strength might be helpful.

  8. Adaptive online self-gating (ADIOS) for free-breathing noncontrast renal MR angiography.

    PubMed

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

    2015-01-01

    To develop a respiratory self-gating method, adaptive online self-gating (ADIOS), for noncontrast MR angiography (NC MRA) of renal arteries to overcome some limitations of current free-breathing methods. A NC MRA pulse sequence for online respiratory self-gating was developed based on three-dimensional balanced steady-state free precession (bSSFP) and slab-selective inversion-recovery. Motion information was derived directly from the slab being imaged for online gating. Scan efficiency was maintained by an automatic adaptive online algorithm. Qualitative and quantitative assessments of image quality were performed and results were compared with conventional diaphragm navigator (NAV). NC MRA imaging was successfully completed in all subjects (n = 15). Similarly good image quality was observed in the proximal-middle renal arteries with ADIOS compared with NAV. Superior image quality was observed in the middle-distal renal arteries in the right kidneys with no NAV-induced artifacts. Maximal visible artery length was significantly longer with ADIOS versus NAV in the right kidneys. NAV setup was completely eliminated and scan time was significantly shorter with ADIOS on average compared with NAV. The proposed ADIOS technique for noncontrast MRA provides high-quality visualization of renal arteries with no diaphragm navigator-induced artifacts, simplified setup, and shorter scan time. © 2014 Wiley Periodicals, Inc.

  9. Preoperative evaluation of hepatic arterial and portal venous anatomy using the time resolved echo-shared MR angiographic technique in living liver donors.

    PubMed

    Lee, Min Woo; Lee, Jeong Min; Lee, Jae Young; Kim, Se Hyung; Park, Eun-Ah; Han, Joon Koo; Choi, Jin-Young; Kim, Young Jun; Suh, Kyung-Suk; Choi, Byung Ihn

    2007-04-01

    The purpose of this study was to determine whether MR angiography utilizing the time resolved echo-shared angiographic technique (TREAT) can provide an effective assessment of the hepatic artery (HA) and portal vein (PV) in living donor candidates. MR angiography (MRA)was performed in 27 patients (23 men and 4 women; mean age, 31 years) by using TREAT. Two blinded radiologists evaluated HA anatomy, origin of segment IV feeding artery and PV anatomy in consensus. Qualitative evaluations of MRA images were performed using the following criteria: (a) overall image quality, (b) presence of artifacts, and (c) degree of venous contamination of the arterial phase. Using intraoperative findings as a standard of reference, the accuracy for the HA anatomy, origin of segment IV feeding artery and PV anatomy on TREAT-MRA were 93% (25/27), 85% (23/27), and 96% (26/27), respectively. Overall image qualities were as follows: excellent (n=22, 81%), good (n=4, 15%), and fair (n=1, 4%). Significant artifacts or venous contamination of the arterial phase images was not noted in any patient. TREAT-MRA can provide a complete evaluation of HA and PV anatomy during preoperative evaluation of living liver donors. Furthermore, it provides a more detailed anatomy of the HA without venous contamination.

  10. Effects of inaccuracies in arterial path length measurement on differences in MRI and tonometry measured pulse wave velocity.

    PubMed

    Weir-McCall, Jonathan R; Khan, Faisel; Cassidy, Deirdre B; Thakur, Arsh; Summersgill, Jennifer; Matthew, Shona Z; Adams, Fiona; Dove, Fiona; Gandy, Stephen J; Colhoun, Helen M; Belch, Jill Jf; Houston, J Graeme

    2017-05-10

    Carotid-femoral pulse wave velocity (cf-PWV) and aortic PWV measured using MRI (MRI-PWV) show good correlation, but with a significant and consistent bias across studies. The aim of the current study was to evaluate whether the differences between cf.-PWV and MRI-PWV can be accounted for by inaccuracies of currently used distance measurements. One hundred fourteen study participants were recruited into one of 4 groups: Type 2 diabetes melltus (T2DM) with cardiovascular disease (CVD) (n = 23), T2DM without CVD (n = 41), CVD without T2DM (n = 25) and a control group (n = 25). All participants underwent cf.-PWV, cardiac MRI and whole body MR angiography(WB-MRA). 90 study participants also underwent aortic PWV using MRI. cf.-PWV EXT was performed using a SphygmoCor device (Atcor Medical, West Ryde, Australia). The true intra-arterial pathlength was measured using the WB-MRA and then used to recalculate the cf.-PWV EXT to give a cf.-PWV MRA . Distance measurements were significantly lower on WB-MRA than on external tape measure (mean diff = -85.4 ± 54.0 mm,p < 0.001). MRI-PWV was significantly lower than cf.-PWV EXT (MRI-PWV = 8.1 ± 2.9 vs. cf.-PWV EXT  = 10.9 ± 2.7 ms -1 ,p < 0.001). When cf.-PWV was recalculated using the inter-arterial distance from WB-MRA, this difference was significantly reduced but not lost (MRI-PWV = 8.1 ± 2.9 ms -1 vs. cf.-PWV MRA 9.1 ± 2.1 ms -1 , mean diff = -0.96 ± 2.52 ms -1 ,p = 0.001). Recalculation of the PWV increased correlation with age and pulse pressure. Differences in cf.-PWV and MRI PWV can be predominantly but not entirely explained by inaccuracies introduced by the use of simple surface measurements to represent the convoluted arterial path between the carotid and femoral arteries.

  11. Evaluation of two-dimensional Bruch's membrane opening minimum rim area for glaucoma diagnostics in a large patient cohort.

    PubMed

    Enders, Philip; Adler, Werner; Kiessling, David; Weber, Vincent; Schaub, Friederike; Hermann, Manuel M; Dietlein, Thomas; Cursiefen, Claus; Heindl, Ludwig M

    2018-03-24

    To characterize the two-dimensional parameter Bruch's membrane opening minimum rim area (BMO-MRA) in spectral domain optical coherence tomography (SD-OCT) of the optic nerve head (ONH) compared to minimum rim width (BMO-MRW) and retinal nerve fibre layer (RNFL) thickness in a large patient cohort. Case-control, cross-sectional study of 705 eyes of 445 participants. A total of 449 eyes with glaucoma, 67 eyes with ocular hypertension and 189 healthy controls, underwent SD-OCT and confocal laser scanning tomography (CSLT), visual field testing and clinical examination. Morphometric ONH parameters, visual field function and diagnostic power were compared. Main outcome measures were SD-OCT-derived BMO-MRA, BMO-MRW, RNFL thickness and CSLT-derived rim area (DM-RA). Mean ONH area was 2.11 ± 0.57 mm 2 ; mean BMO area was 1.89 ± 0.45 mm 2 . Correlation of mean deviation in visual field to morphometric parameters was ρ = 0.70, (p < 0.001) for RNFL thickness, ρ = 0.68 (p < 0.001) for BMO-MRA, ρ = 0.66 (p < 0.001) for BMO-MRW. These correlations were not significantly different (p > 0.05), while DM-RA correlated significantly worse (ρ = 0.55; p < 0.001). In receiver operating characteristics, the calculated area under the curve (AUC) and sensitivity at 90% specificity to differentiate glaucoma were 0.87% and 70.1% for BMO-MRA, 0.86% and 68.1% for RNFL thickness, 0.84% and 66.0% for BMO-MRW, 0.82% and 51.3% for DM-RA. In a heterogenous clinical cohort of glaucoma patients, all analysed SD-OCT parameters excel DM-RA of CSLT. The two-dimensional parameter BMO-MRA shows comparable levels of diagnostic power to detect glaucoma compared to established parameters BMO-MRW and RNFL thickness. Given higher comparability between ONH sizes, BMO-MRA might become an additional standard tool in SD-OCT imaging for glaucoma. © 2018 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  12. NATO and the Challenges of Austerity

    DTIC Science & Technology

    2012-01-01

    Navy’s participation in operations in Libya in 2011. The The Impact of Defense Cuts on Key NATO Allies 7 elimination of the Nimrod MRA.4 maritime... Nimrod MRA. Mk2. The CSR cuts included the entire fleet of Harrier GR.9 combat aircraft. The Harrier cut has joint implications because the RAF Har- riers...overlap of its replacement. The Boeing RC-135 “Rivet Joint” signals intelligence (SIGINT) aircraft will replace the two remaining Nimrod R.1 platforms

  13. On wavelet analysis of auditory evoked potentials.

    PubMed

    Bradley, A P; Wilson, W J

    2004-05-01

    To determine a preferred wavelet transform (WT) procedure for multi-resolution analysis (MRA) of auditory evoked potentials (AEP). A number of WT algorithms, mother wavelets, and pre-processing techniques were examined by way of critical theoretical discussion followed by experimental testing of key points using real and simulated auditory brain-stem response (ABR) waveforms. Conclusions from these examinations were then tested on a normative ABR dataset. The results of the various experiments are reported in detail. Optimal AEP WT MRA is most likely to occur when an over-sampled discrete wavelet transformation (DWT) is used, utilising a smooth (regularity >or=3) and symmetrical (linear phase) mother wavelet, and a reflection boundary extension policy. This study demonstrates the practical importance of, and explains how to minimize potential artefacts due to, 4 inter-related issues relevant to AEP WT MRA, namely shift variance, phase distortion, reconstruction smoothness, and boundary artefacts.

  14. Magnetic Resonance Imaging (MRI) and Digital Subtraction Angiography Investigation of Childhood Moyamoya Disease.

    PubMed

    Song, Peiji; Qin, Jing; Lun, Han; Qiao, Penggang; Xie, Anming; Li, Gongjie

    2017-11-01

    Because digital subtraction angiography (DSA) is not an ideal angiographic examination for moyamoya disease in the pediatric population, magnetic resonance angiography (MRA) provides a noninvasive contrast-free angiographic examination; whereas magnetic resonance imaging (MRI) provides superior spatial resolution and soft-tissue contrast for lesion assessment. Ninety patients with moyamoya disease were examined by MRI and DSA to assess the distribution of lesions and their diagnostic agreement between modalities. MRI examination revealed 439 lesions. Punctate lesions were the most abundant, followed by patchy lesions. These lesions generally covered a smaller area than the abnormal-vascular corresponding brain parenchyma. Steno-occlusive changes at bilateral anterior, medial, and posterior cerebral arteries were identified by MRA and DSA. MRI showed moderate agreement in identifying lesions after steno-occlusive changes in anterior and medial cerebral arteries, and good agreement in posterior cerebral arteries; 6% to 11% of cases were misdiagnosed by MRA.

  15. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Davis, A.B.; Clothiaux, E.

    Because of Earth`s gravitational field, its atmosphere is strongly anisotropic with respect to the vertical; the effect of the Earth`s rotation on synoptic wind patterns also causes a more subtle form of anisotropy in the horizontal plane. The authors survey various approaches to statistically robust anisotropy from a wavelet perspective and present a new one adapted to strongly non-isotropic fields that are sampled on a rectangular grid with a large aspect ratio. This novel technique uses an anisotropic version of Multi-Resolution Analysis (MRA) in image analysis; the authors form a tensor product of the standard dyadic Haar basis, where themore » dividing ratio is {lambda}{sub z} = 2, and a nonstandard triadic counterpart, where the dividing ratio is {lambda}{sub x} = 3. The natural support of the field is therefore 2{sup n} pixels (vertically) by 3{sup n} pixels (horizontally) where n is the number of levels in the MRA. The natural triadic basis includes the French top-hat wavelet which resonates with bumps in the field whereas the Haar wavelet responds to ramps or steps. The complete 2D basis has one scaling function and five wavelets. The resulting anisotropic MRA is designed for application to the liquid water content (LWC) field in boundary-layer clouds, as the prevailing wind advects them by a vertically pointing mm-radar system. Spatial correlations are notoriously long-range in cloud structure and the authors use the wavelet coefficients from the new MRA to characterize these correlations in a multifractal analysis scheme. In the present study, the MRA is used (in synthesis mode) to generate fields that mimic cloud structure quite realistically although only a few parameters are used to control the randomness of the LWC`s wavelet coefficients.« less

  16. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schaefer, Philipp J., E-mail: jp.schaefer@rad.uni-kiel.de; Schaefer, Fritz K. W.; Mueller-Huelsbeck, Stefan

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

  17. Thirty Years of Evidence on the Efficacy of Drug Treatments for Chronic Heart Failure With Reduced Ejection Fraction

    PubMed Central

    Earley, Amy; Voors, Adriaan A.; Senni, Michele; McMurray, John J.V.; Deschaseaux, Celine; Cope, Shannon

    2017-01-01

    Background— Treatments that reduce mortality and morbidity in patients with heart failure with reduced ejection fraction, including angiotensin-converting enzyme inhibitors (ACEI), angiotensin receptor blockers (ARB), β-blockers (BB), mineralocorticoid receptor antagonists (MRA), and angiotensin receptor–neprilysin inhibitors (ARNI), have not been studied in a head-to-head fashion. This network meta-analysis aimed to compare the efficacy of these drugs and their combinations regarding all-cause mortality in patients with heart failure with reduced ejection fraction. Methods and Results— A systematic literature review identified 57 randomized controlled trials published between 1987 and 2015, which were compared in terms of study and patient characteristics, baseline risk, outcome definitions, and the observed treatment effects. Despite differences identified in terms of study duration, New York Heart Association class, ejection fraction, and use of background digoxin, a network meta-analysis was considered feasible and all trials were analyzed simultaneously. The random-effects network meta-analysis suggested that the combination of ACEI+BB+MRA was associated with a 56% reduction in mortality versus placebo (hazard ratio 0.44, 95% credible interval 0.26–0.66); ARNI+BB+MRA was associated with the greatest reduction in all-cause mortality versus placebo (hazard ratio 0.37, 95% credible interval 0.19–0.65). A sensitivity analysis that did not account for background therapy suggested that ARNI monotherapy is more efficacious than ACEI or ARB monotherapy. Conclusions— The network meta-analysis showed that treatment with ACEI, ARB, BB, MRA, and ARNI and their combinations were better than the treatment with placebo in reducing all-cause mortality, with the exception of ARB monotherapy and ARB plus ACEI. The combination of ARNI+BB+MRA resulted in the greatest mortality reduction. PMID:28087688

  18. Evaluation of the applicability of territorial arterial spin labeling in meningiomas for presurgical assessments compared with 3-dimensional time-of-flight magnetic resonance angiography.

    PubMed

    Lu, Yiping; Luan, Shihai; Liu, Li; Xiong, Ji; Wen, Jianbo; Qu, Jianxun; Geng, Daoying; Yin, Bo

    2017-10-01

    To prospectively evaluate the application of territorial arterial spin labelling (t-ASL) in comparison with unenhanced three-dimensional time-of-flight magnetic resonance angiography (3D-TOF-MRA) in the identification of the feeding vasculature of meningiomas. Thirty consecutive patients with suspected meningiomas underwent conventional MR imaging, unenhanced 3D-TOF-MRA and t-ASL scanning. Four experienced neuro-radiologists assessed the feeding vessels with different techniques separately. For the identification of the origin of the feeding arteries on t-ASL, the inter-observer agreement was excellent (к = 0.913), while the inter-observer agreement of 3D-TOF-MRA was good (к = 0.653). The inter-modality agreement between t-ASL and 3D-TOF-MRA for the feeding arteries was moderate (к = 0.514). All 8 patients with motor or sensory disorders proved to have meningiomas supplied completely or partially by the internal carotid arteries, while all 14 patients with meningiomas supplied by the external carotid arteries or basilar arteries didn't show any symptoms concerning motor or sensory disorders (p = 0.003). T-ASL could complement unenhanced 3D-TOF-MRA and increase accuracy in the identification of the supplying arteries of meningiomas in a safe, intuitive, non-radioactive manner. The information about feeding arteries was potentially related to patients' symptoms and pathology, making it more crucial for neurosurgeons in planning surgery as well as evaluating prognosis. • A comprehensive understanding of feeding vasculature is helpful for optimized treatment decisions. • T-ASL could identify main supplying arteries of meningiomas with excellent inter-observer agreement. • The inter-modality agreement for identification of the main feeding arteries was moderate. • Blood supply from ICAs was related to motor or sensory disorders. • High-level meningiomas were found to have double main supplying arteries.

  19. Greater refill adherence to adalimumab therapy for patients using specialty versus retail pharmacies.

    PubMed

    Liu, Yifei; Yang, Mei; Chao, Jingdong; Mulani, Parvez M

    2010-08-01

    Retail pharmacies provide regular prescription drugs and some specialty prescription drugs, whereas specialty pharmacies focus on distributing specialty prescription drugs, including tumor necrosis factor (TNF) antagonists. It is unknown whether pharmacy type impacts patients' adherence to anti-TNF therapy. The relationship between pharmacy type (specialty vs. retail) and refill adherence to therapy with the TNF antagonist adalimumab was examined. This was a retrospective analysis of dispensing records of patients in the United States who were prescribed a TNF antagonist (adalimumab 40 mg per 0.8-mL injection) during a dispensation period from January 2003 to August 2009. Patients treated with adalimumab were included in the analysis regardless of diagnosis. For each patient, medication refill adherence (MRA) was calculated as total days of supply divided by total number of days evaluated, multiplied by 100. A regression analysis was conducted in which the dependent variable was MRA and the independent variables included pharmacy type (specialty vs. retail pharmacy), reimbursement/payment type, copayment/payment amount per prescription, age, sex, ethnicity, and annual income. Of the 86,079 patients included, 70% obtained the medication from a specialty pharmacy, 92% were members of Blue Cross and Blue Shield plans, 67% were women, and 81% were white. The average MRA was 84, and the average age was 52 years. Significant predictors (P<0.05) of MRA included pharmacy type, reimbursement/payment type, copayment/payment amount per prescription, age, sex, and ethnicity; and pharmacy type was the strongest predictor. When other independent variables were controlled for, MRA was 16% less for patients who used a retail pharmacy vs. patients who used a specialty pharmacy. Patients who used a specialty pharmacy to fulfill prescriptions for a TNF antagonist had a greater refill adherence than did patients who used a retail pharmacy.

  20. Dose optimization of contrast-enhanced carotid MR angiography.

    PubMed

    Unterweger, M; Froehlich, J M; Kubik-Huch, R A; Seifert, B; Birrer, M; Huber, T; Otto, R

    2005-09-01

    The purpose of this work was to compare the diagnostic performance of a single-contrast or a double-contrast dose of carotid contrast-enhanced MR angiography (MRA). One-hundred nineteen patients (mean age 65+/-14.4 years) underwent carotid contrast-enhanced MRA with a standardized protocol (repetition time/echo 3.73 ms/1.38 ms, flip-angle 25 degrees, acquisition-time 19 s, voxel size 1.2 x 1.2 x 0.9 mm3) on a 1.5-T scanner (Sonata, Siemens-Medical-Systems) using a neck phased-array coil. Contrast agent was administered intravenously at a rate of 3.0 ml/s, either as a single dose (n=57; 0.1 mmol/kg body weight) or as a double dose (n=62; 0.2 mmol/kg body weight) of meglumine gadoterate (0.5 M/l), followed by 30 ml saline. Qualitative image analysis was performed on maximum intensity projections using a five-point scale. Signal intensities were measured at three different vascular levels on both sides to assess the contrast-to-noise ratios (CNRs). Image quality was rated as good or excellent in all cases. A double dose did not influence the efficacy of carotid enhancement (CNR single dose 69.12+/-19.8; CNR double dose 70.01+/-20.7; p = 0.81) compared with a single dose. In both dose groups the mean CNRs were inversely related to bodyweight, despite adjusted contrast volumes (p=0.0005). Double-dose contrast-enhanced carotid MRA is not superior to single-dose MRA, as overall diagnostic performance and quantitative contrast enhancement are equal. Being more cost-efficient, a single-dose administration of contrast agent is recommended for MRA of the carotid arteries.

  1. Greater rupture risk for familial as compared to sporadic unruptured intracranial aneurysms.

    PubMed

    Broderick, Joseph P; Brown, Robert D; Sauerbeck, Laura; Hornung, Richard; Huston, John; Woo, Daniel; Anderson, Craig; Rouleau, Guy; Kleindorfer, Dawn; Flaherty, Matthew L; Meissner, Irene; Foroud, Tatiana; Moomaw, E Charles J; Connolly, E Sander

    2009-06-01

    The risk of intracranial aneurysm (IA) rupture in asymptomatic members of families who have multiple affected individuals is not known. First-degree unaffected relatives of those with a familial history of IA who had a history of smoking or hypertension but no known IA were offered cerebral MR angiography (MRA) and followed yearly as part of a National Institute of Neurological Diseases and Stroke-funded study of familial IA (Familial Intracranial Aneurysm [FIA] Study). A total of 2874 subjects from 542 FIA Study families were enrolled. After study enrollment, MRAs were performed in 548 FIA Study family members with no known history of IA. Of these 548 subjects, 113 subjects (20.6%) had 148 IAs by MRA of whom 5 subjects had IA >or=7 mm. Two subjects with an unruptured IA by MRA/CT angiography (3-mm and 4-mm anterior communicating artery) subsequently had rupture of their IA. This represents an annual rate of 1.2 ruptures per 100 subjects (1.2% per year; 95% CI, 0.14% to 4.3% per year). None of the 435 subjects with a negative MRA have had a ruptured IA. Survival curves between the MRA-positive and -negative cohorts were significantly different (P=0.004). This rupture rate of unruptured IA in the FIA Study cohort of 1.2% per year is approximately 17 times higher than the rupture rate for subjects with an unruptured IA in the International Study of Unruptured Aneurysm Study with a matched distribution of IA size and location 0.069% per year. Small unruptured IAs in patients from FIA Study families may have a higher risk of rupture than sporadic unruptured IAs of similar size, which should be considered in the management of these patients.

  2. The cryopreservation protocol optimal for progenitor recovery is not optimal for preservation of marrow repopulating ability.

    PubMed

    Balint, B; Ivanović, Z; Petakov, M; Taseski, J; Jovcić, G; Stojanović, N; Milenković, P

    1999-03-01

    The efficiency of five different cryopreservation protocols (our original controlled-rate and noncontrolled-rate protocols) was evaluated on the basis of the recovery after thawing of very primitive pluripotent hemopoietic stem cells (MRA(CFU-GM), pluripotent progenitors (CFU-Sd12) and committed granulocyte-monocyte progenitors (CFU-GM) in mouse bone marrow. Although the nucleated cell recovery and viability determined immediately after the thawing and washing of the cells were found to be similar, whether controlled-rate or noncontrolled-rate cryopreservation protocols were used, the recovery of MRA(CFU-GM), CFU-Sd12 and CFU-GM varied depending on the type of protocol and the cryoprotector (DMSO) concentrations used. It was shown that the controlled-rate protocol was more efficient, enabling better MRA(CFU-GM), CFU-Sd12 and CFU-GM recovery from frozen samples. The most efficient was the controlled-rate protocol of cryopreservation designed to compensate for the release of fusion heat, which enabled a better survival of CFU-Sd12 and CFU-GM when combined with a lower (5%) DMSO concentration. On the contrary, a satisfactory survival rate of very primitive stem cells (MRA(CFU-GM)) was achieved only when 10% DMSO was included with a five-step protocol of cryopreservation. These results point to adequately used controlled-rate freezing as essential for a highly efficient cryopreservation of some of the categories of hematopoietic stem and progenitor cells. At the same time, it was obvious that a higher DMSO concentration was necessary for the cryopreservation of very primitive stem cells, but not, however, for more mature progenitor cells (CFU-S, CFU-GM). These results imply the existence of a mechanism that decreases the intracellular concentration of DMSO in primitive MRA cells, which is not the case for less primitive progenitors.

  3. Carotid MR angiography with traditional bolus timing: clinical observations and Fourier-based modelling of contrast kinetics.

    PubMed

    Menke, Jan

    2009-11-01

    This study analyses the relation between image quality and contrast kinetics in bolus-timed carotid magnetic resonance angiography (MRA) and interprets the findings by Fourier-based numerical modelling. One hundred patients prone to carotid stenosis were studied using contrast-enhanced carotid MRA with bolus timing. The carotid MRAs were timed to start relatively early without accounting for the injection time of the contrast medium. For interpretation different starting times were modelled, utilising the spectral information of the test bolus series. In the test bolus series the arterial time-to-peak showed a large 95% confidence interval of 12-27 s, indicating the need for individual MRA timing. All bolus-timed MRAs were of good diagnostic quality. The mean (+/-SD) arterial contrast-to-noise ratio was 53.0 (+/-12.8) and thus high, and 95% of the MRAs showed a slight venous contamination of 11.8% or less (median 5.6%). According to the Fourier-based modelling the central k-space may be acquired about 2 s before the arterial contrast peak. This results in carotid MRAs with sufficiently high arterial enhancement and little venous contamination. In conclusion, in bolus-timed carotid MRA a relatively short timing provides good arterial contrast with little venous contamination, which can be explained by Fourier-based numerical modelling of the contrast kinetics.

  4. Contrast-enhanced magnetic resonance angiography for preoperative imaging of deep inferior epigastric artery perforator flaps: advantages and disadvantages compared with computed tomography angiography: a United Kingdom perspective.

    PubMed

    Schaverien, Mark V; Ludman, Catherine N; Neil-Dwyer, Jason; McCulley, Stephen J

    2011-12-01

    The anatomy of the anterior abdominal wall is highly variable and leads to uncertainty when harvesting a deep inferior epigastric artery perforator flap. Presurgical imaging has been shown to reduce the operating time, as well as reduce the rates of flap and donor site complications. The importance of imaging of the venous system has also been recognized for reducing the risk of venous congestion. The modalities currently available for presurgical imaging include handheld Doppler ultrasound, duplex ultrasound, computed tomographic angiography (CTA), and contrast-enhanced magnetic resonance angiography (CE-MRA). Of these, the most promising are CTA and CE-MRA, and advantages and disadvantages exist for both modalities. In this article, we review the use of CE-MRA for preoperative flap imaging and report our experience with its use in deep inferior epigastric artery perforator flap harvest, as well as compare it with CTA. We also explore the future directions for presurgical flap imaging.

  5. The Impact of Injector-Based Contrast Agent Administration on Bolus Shape and Magnetic Resonance Angiography Image Quality.

    PubMed

    Jost, Gregor; Endrikat, Jan; Pietsch, Hubertus

    2017-01-01

    To compare injector-based contrast agent (CA) administration with hand injection in magnetic resonance angiography (MRA). Gadobutrol was administered in 6 minipigs with 3 protocols: (a) hand injection (one senior technician), (b) hand injection (6 less-experienced technicians), and (c) power injector administration. The arterial bolus shape was quantified by test bolus measurements. A head and neck MRA was performed for quantitative and qualitative comparison of signal enhancement. A significantly shorter time to peak was observed for protocol C, whereas no significant differences between protocols were found for peak height and bolus width. However, for protocol C, these parameters showed a much lower variation. The MRA revealed a significantly higher signal-to-noise ratio for injector-based administration. A superimposed strong contrast of the jugular vein was found in 50% of the hand injections. Injector-based CA administration results in a more standardized bolus shape, a higher vascular contrast, and a more robust visualization of target vessels.

  6. [Reconstructive surgery of the mitral and tricuspid valves with a Cosgrove-Edwards flexible ring].

    PubMed

    Pugliese, P; Pantani, P; Lusa, A M; Nuti, R; Bongiovanni, M; Conti, F; Biasi, C; Pigini, F; Palmisano, D

    2000-04-01

    Mitral and tricuspid valve asymmetric annular dilation represents the most important mechanism which produces insufficiency. Recent computerized in vitro and in vivo three-dimensional models have been developed in order to better understand the competing factors (annular dilation, displacement of papillary muscles, left and right ventricular geometry). The leading cause of mitral and tricuspid competence is a sphincteric action of both annuli, during systole and diastole, the loss of which produces asymmetric dilation and therefore the absence of cusp coaptation. The Cosgrove-Edwards dynamic ring corrects, alone or in combination with other procedures on the valves, this patho-anatomic feature in a physiological way by restoring the normal annular dimensions and the sphincteric movements during the cardiac cycle. Between June 1998 and May 1999, 30 adult patients underwent mitral (n = 20, Group I) or tricuspid valve repair (n = 10, Group II). Regurgitation was due to a degenerative disease in 13 Group I patients and to ischemic (n = 3), congenital (n = 2) or dilated cardiomyopathy (n = 2) in the others. In Group II the leading cause of insufficiency was functional regurgitation in 7 patients and organic in 3. Associated procedures were carried out in 4 Group I patients and in all Group II patients. Regurgitation was evaluated by transesophageal echocardiography before, during and 3 months after operation. The maximal regurgitant area (MRA) and the grade of insufficiency were evaluated using the equation: MRA < 2 cm2 = grade 0, MRA > 2 < 4 cm2 = 1+, MRA > 4 < 7 cm2 = grade 2+, MRA > 7 < 10 cm2 = 3+, MRA > 10 cm2 = 4+. The operative mortality was 0%. One Group I patient died 3 months after operation due to bronchopneumonia. No patient was reoperated on for plasty failure in both groups during the follow-up. Mitral insufficiency was absent (grade 0) in 17 Group I patients and mild (grade 1+) in 3 at the end of operation. At 3-month postoperative transesophageal

  7. High spatial resolution contrast-enhanced MR angiography of the supraaortic arteries using the quadrature body coil at 3.0T: a feasibility study.

    PubMed

    Willinek, Winfried A; Bayer, Thomas; Gieseke, Jürgen; von Falkenhausen, Marcus; Sommer, Torsten; Hoogeveen, Romhild; Wilhelm, Kai; Urbach, Horst; Schild, Hans H

    2007-03-01

    To examine whether the the increased signal-to-noise (S/N) available at 3.0T would permit the use of the quadrature body coil for high spatial resolution contrast-enhanced (CE) MR angiography (MRA), and whether the large FOV that was used in our routine 1.5T protocol would also be feasible at 3.0T. In a prospective study, 43 patients and five volunteers were examined on a clinical whole-body 3.0T MR unit (Intera, Philips Medical Systems, Best, The Netherlands) after institutional review board approval and informed consent. Three-dimensional CE MRA (T1 gradient echo-sequence with TR/TE = 5.7/1.93 msec.; acquisition time, 1:54 min.) using randomly segmented central k-space ordering (CENTRA) was acquired with the quadrature body coil, using over a FOV of 350 mm. A high-image matrix of 432x432 yielded a non-zero filled voxel size of 0.81 mm x 0.81 mm x 1.0 mm (0.66 mm(3)). For quantitative analysis, contrast ratios (CR) between vessels (S) and signal in surrounding tissue (ST) were calculated [(S-ST)/(S+ST)]. For qualitative analysis, image quality and presence of artifacts were rated by two radiologists in consensus on a five-point scale (1=excellent to 5=nondiagnostic). Digital subtraction angiography (DSA) served as the standard of reference in patients with vascular disease. In the five volunteers, 1.5T CE MRA using a phased array neurovascular coil was available for intraindividual comparison. 3.0T CE MRA was successfully performed in 48/48 subjects (100%). Mean CR+/- SD were 0.76 (139.30/182.42) and 0.87 (235.18/270.14) at 3.0T and 1.5T respectively . Mean image quality was 3.82+/-0.86. Intraindividual comparison between 1.5T and 3.0T CE MRA in the volunteers revealed no significant difference in image quality (4.2+/-0.74 vs 4.6+/-0.80; p>0.05). Vascular disease was correctly identified in 13/13 patients with DSA correlation. CE MRA of the supraaortic arteries is feasible at 3.0T using a large FOV of 350 mm. The signal gain at 3.0T enables high spatial resolution

  8. MR arthrography in chondromalacia patellae diagnosis on a low-field open magnet system.

    PubMed

    Harman, Mustafa; Ipeksoy, Umit; Dogan, Ali; Arslan, Halil; Etlik, Omer

    2003-01-01

    The purpose of this study was to compare the diagnostic efficacy conventional MRI and MR arthrography (MRA) in the diagnosis of chondromalacia patella (CP) on a low-field open magnet system (LFOMS), correlated with arthroscopy. Forty-two patients (50 knees) with pain in the anterior part of the knee were prospectively examined with LFOMS, including T1-weighted, proton density-weighted and T2-weighted sequences. All were also examined T1-weighted MRI after intraarticular injection of dilue gadopentetate dimeglumine. Two observers, who reached a consensus interpretation, evaluated each imaging technique independently. Thirty-six of the 50 facets examined had chondromalacia shown by arthroscopy, which was used as the standard of reference. The sensitivity, specificity and accuracy of each imaging technique in the diagnosis of each stage of CP were determined and compared by using the McNemar two-tailed analysis. Arthroscopy showed that 16 facets were normal. Four (30%) of 13 grade 1 lesions were detected with T1. Four lesions (30%) with T2 and three lesions (23%) with proton-weighted images were detected. Seven (53%) of 13 grade 1 lesions were detected with MRA. Grade 2 abnormalities were diagnosed in two (33%) of six facets with proton density-weighted pulse sequences, two (33%) of six facets with T1-weighted pulse sequences, in three (50%) of six facets with T2-weighted pulse sequences, in five (83%) of six facets with MRA sequences. Grade 3 abnormalities were diagnosed in three (71%) of seven facets with proton density- and T1-weighted images, five (71%) of seven facets with T2-weighted pulse sequences, six (85%) of seven facets with MRA sequences. Grade 4 CP was detected with equal sensitivity with T1-, proton density- and T2-weighted pulse sequences, all showing seven (87%) of the eight lesions. MRA again showed these findings in all eight patients. All imaging techniques were insensitive to grade 1 lesions and highly sensitive to grade 4 lesion, so that no

  9. Time resolved imaging of contrast kinetics (TRICKS) MR angiography of arteriovenous malformations of head and neck.

    PubMed

    Razek, Ahmed Abdel Khalek Abdel; Gaballa, Gada; Megahed, Abdel Salam; Elmogy, Ebrahiem

    2013-11-01

    To evaluate vasculature of arteriovenous malformations (AVMs) of head and neck with time resolved imaging of contrast kinetics (TRICKS) MR angiography (MRA). Prospective study was conducted upon 19 patients (age range, 12-29 years; mean age 18 years; 10 males and 9 females) with AVM of head and neck. TRICKS-MRA of head and neck was performed during injection of contrast medium. Post processing with reconstruction of the images was done. Two independent readers assessed the overall TRICKS-MRA image quality score using a 5-point scale and depiction of the main arterial feeders, nidus, and venous drainage using 3 points scale. The Kappa test for interobserver agreement was done. The AVMs were evaluated morphologically in terms of number and origin of the main arterial feeders, the location and size of nidus either small (>2 cm) or large (>2 cm) and the draining veins into the superficial or deep venous drainage. The average TRICKS-MRA image quality score as judged by reader 1 was 3.89 ± 1.15 and that as judged by reader 2 was 3.89 ± 0.10, which yielded excellent interobserver agreement (k=0.77, 95% CI=0.53-0.98, r=0.78, P=0.001). The interobserver agreement of both readers was excellent for the arterial feeders (k=0.81, 95% CI=0.57-1.00, r=0.83, P=0.001), excellent for the nidus (k=0.91, 95% CI=0.75-1.00, r=0.92, P=0.001), and good for the venous drainage (k=0.77, 95% CI=0.53-0.98, r=0.78, P=0.001). The arterial feeders were single (n=14) or multiple (n=5), the nidus was large (n=16) or small (n=3) and the venous drainage was into the internal jugular (n=17) or the external jugular (n=2) veins. Three patients with small nidus and single arterial feeder were treated with sclerotherapy. Eleven patients with large nidus and single arterial feeder were referred for embolization. Combined embolization and surgery were done for five patients with large nidus and multiple arterial feeders. We concluded that TRICKS-MRA is a reliable non invasive tool for evaluation of the

  10. A predictive software tool for optimal timing in contrast enhanced carotid MR angiography

    NASA Astrophysics Data System (ADS)

    Moghaddam, Abbas N.; Balawi, Tariq; Habibi, Reza; Panknin, Christoph; Laub, Gerhard; Ruehm, Stefan; Finn, J. Paul

    2008-03-01

    A clear understanding of the first pass dynamics of contrast agents in the vascular system is crucial in synchronizing data acquisition of 3D MR angiography (MRA) with arrival of the contrast bolus in the vessels of interest. We implemented a computational model to simulate contrast dynamics in the vessels using the theory of linear time-invariant systems. The algorithm calculates a patient-specific impulse response for the contrast concentration from time-resolved images following a small test bolus injection. This is performed for a specific region of interest and through deconvolution of the intensity curve using the long division method. Since high spatial resolution 3D MRA is not time-resolved, the method was validated on time-resolved arterial contrast enhancement in Multi Slice CT angiography. For 20 patients, the timing of the contrast enhancement of the main bolus was predicted by our algorithm from the response to the test bolus, and then for each case the predicted time of maximum intensity was compared to the corresponding time in the actual scan which resulted in an acceptable agreement. Furthermore, as a qualitative validation, the algorithm's predictions of the timing of the carotid MRA in 20 patients with high quality MRA were correlated with the actual timing of those studies. We conclude that the above algorithm can be used as a practical clinical tool to eliminate guesswork and to replace empiric formulae by a priori computation of patient-specific timing of data acquisition for MR angiography.

  11. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Not Available

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

  12. Gadofosveset-enhanced magnetic resonance angiography as a means of evaluating pulmonary arteriovenous malformation: a case report.

    PubMed

    Pressacco, Josephine; Papas, Konstantin

    2012-07-01

    This case report is a unique presentation of a new potential indication for Gadofosvest (Ablavar), a blood pool contrast agent for magnetic resonance angiography (MRA). Ablavar is an excellent MRA contrast agent because it provides optimal contrast opacification of both the arterial and venous system, unlike the conventional extracellular agents that are used for arterial imaging only. The present case report demonstrates the ability of Ablavar to demonstrate pulmonary arteriovenous malformation (AVM), showing both its arterial feeders as well as its venous drainage tract. Crown Copyright © 2012. Published by Elsevier Inc. All rights reserved.

  13. Hip arthroscopy: prevalence of intra-articular pathologic findings after traumatic injury of the hip.

    PubMed

    Khanna, Vickas; Harris, Adam; Farrokhyar, Forough; Choudur, Hema N; Wong, Ivan H

    2014-03-01

    The purpose of this study was to document and compare the incidence of intra-articular hip pathologic findings identified using arthroscopy versus conventional imaging in patients with acute trauma to the hip. This was a blinded prospective case series study designed to review the incidence of intra-articular pathologic disorders in patients with post-traumatic injury between the ages of 18 and 65 years who were referred to a single surgeon. Injuries included hip dislocation, proximal femur fracture, pelvic ring fracture, acetabular fracture, penetrating injury (gunshot wound), and soft tissue injury. Preoperative radiographs, computed tomographic (CT) scans, or magnetic resonance imaging/magnetic resonance angiography (MRI/MRA) scans (or a combination of these) were obtained. Findings were documented and compared with intraoperative findings. A total of 29 post-traumatic hips were enrolled in this study. Hip arthroscopy identified 17 of 29 hips (59%) as having loose bodies, 11 of 29 (38%) hips as having an intra-articular step deformity, 14 of 29 (49%) hips as having an osteochondral lesion, and 27 of 29 (93%) hips as having a labral tear. Plain radiographs and CT scans yielded low sensitivity when compared with arthroscopy for the identification of loose bodies and step deformities. MRI/MRA comparison with arthroscopic findings suggest that MRI/MRA is an accurate tool for identification of labral tears, because 91% of tears seen on arthroscopy were also identified by MRI/MRA. In 4 hips, however, MRI/MRA failed to identify osteochondral lesions that were subsequently identified by arthroscopy. Traumatic injuries of the hip result in substantial intra-articular pathologic findings, including loose bodies, labral tears, step deformities, and osteochondral lesions. The arthroscope is a powerful tool in identifying these injuries. Plain radiographs and CT scans appear to underestimate the true incidence of loose bodies and step deformities within the joint when

  14. Application and assessment of a robust elastic motion correction algorithm to dynamic MRI.

    PubMed

    Herrmann, K-H; Wurdinger, S; Fischer, D R; Krumbein, I; Schmitt, M; Hermosillo, G; Chaudhuri, K; Krishnan, A; Salganicoff, M; Kaiser, W A; Reichenbach, J R

    2007-01-01

    The purpose of this study was to assess the performance of a new motion correction algorithm. Twenty-five dynamic MR mammography (MRM) data sets and 25 contrast-enhanced three-dimensional peripheral MR angiographic (MRA) data sets which were affected by patient motion of varying severeness were selected retrospectively from routine examinations. Anonymized data were registered by a new experimental elastic motion correction algorithm. The algorithm works by computing a similarity measure for the two volumes that takes into account expected signal changes due to the presence of a contrast agent while penalizing other signal changes caused by patient motion. A conjugate gradient method is used to find the best possible set of motion parameters that maximizes the similarity measures across the entire volume. Images before and after correction were visually evaluated and scored by experienced radiologists with respect to reduction of motion, improvement of image quality, disappearance of existing lesions or creation of artifactual lesions. It was found that the correction improves image quality (76% for MRM and 96% for MRA) and diagnosability (60% for MRM and 96% for MRA).

  15. Standardized volume-rendering of contrast-enhanced renal magnetic resonance angiography.

    PubMed

    Smedby, O; Oberg, R; Asberg, B; Stenström, H; Eriksson, P

    2005-08-01

    To propose a technique for standardizing volume-rendering technique (VRT) protocols and to compare this with maximum intensity projection (MIP) in regard to image quality and diagnostic confidence in stenosis diagnosis with magnetic resonance angiography (MRA). Twenty patients were examined with MRA under suspicion of renal artery stenosis. Using the histogram function in the volume-rendering software, the 95th and 99th percentiles of the 3D data set were identified and used to define the VRT transfer function. Two radiologists assessed the stenosis pathology and image quality from rotational sequences of MIP and VRT images. Good overall agreement (mean kappa=0.72) was found between MIP and VRT diagnoses. The agreement between MIP and VRT was considerably better than that between observers (mean kappa=0.43). One of the observers judged VRT images as having higher image quality than MIP images. Presenting renal MRA images with VRT gave results in good agreement with MIP. With VRT protocols defined from the histogram of the image, the lack of an absolute gray scale in MRI need not be a major problem.

  16. Privatization of Army Lodging

    DTIC Science & Technology

    2008-03-25

    primary point person for this initiative is ASA for Installations and Environment (ASA- I& E ). 9 * There are 11 major commands, only 1 shown on...FM&C) DCS G-8 DCS G-8 ASA (I& E ) ASA (I& E ) ASA (M&RA) ASA (M&RA) DCS G-1 DCS G-1 CIO/ G-6 CIO/ G-6 DCS G-2 DCS G-2 DCS G-3 DCS G-3 DASDAS ACSIM/ IMCOM...Army Ch of Staff Army Figure 1 – Army Stakeholders in Policy Process18 The Office of the ASA-I& E has responsibility for policy development

  17. State-of-the-art Magnetic Resonance Imaging in Vascular Thoracic Outlet Syndrome.

    PubMed

    Aghayev, Ayaz; Rybicki, Frank J

    2015-05-01

    Vascular thoracic outlet syndrome is caused by compression of subclavian/axillary vessels during their passage from the thoracic cavity to the axilla. Early diagnosis and treatment is important to prevent debilitating outcomes of vascular thoracic outlet syndrome. Contrast-enhanced three-dimensional (3D) magnetic resonance angiography (MRA) with equilibrium phase using provocative arm positioning is the optimal examination to determine presence, degree of vascular compression, and complications of vascular thoracic outlet syndrome. This article reviews thoracic outlet anatomy, disorders of the vascular component, and typical imaging findings by contrast-enhanced 3D MRA. Published by Elsevier Inc.

  18. Breath-hold imaging of the coronary arteries using Quiescent-Interval Slice-Selective (QISS) magnetic resonance angiography: pilot study at 1.5 Tesla and 3 Tesla.

    PubMed

    Edelman, Robert R; Giri, S; Pursnani, A; Botelho, M P F; Li, W; Koktzoglou, I

    2015-11-23

    Coronary magnetic resonance angiography (MRA) is usually obtained with a free-breathing navigator-gated 3D acquisition. Our aim was to develop an alternative breath-hold approach that would allow the coronary arteries to be evaluated in a much shorter time and without risk of degradation by respiratory motion artifacts. For this purpose, we implemented a breath-hold, non-contrast-enhanced, quiescent-interval slice-selective (QISS) 2D technique. Sequence performance was compared at 1.5 and 3 Tesla using both radial and Cartesian k-space trajectories. The left coronary circulation was imaged in six healthy subjects and two patients with coronary artery disease. Breath-hold QISS was compared with T2-prepared 2D balanced steady-state free-precession (bSSFP) and free-breathing, navigator-gated 3D bSSFP. Approximately 10 2.1-mm thick slices were acquired in a single ~20-s breath-hold using two-shot QISS. QISS contrast-to-noise ratio (CNR) was 1.5-fold higher at 3 Tesla than at 1.5 Tesla. Cartesian QISS provided the best coronary-to-myocardium CNR, whereas radial QISS provided the sharpest coronary images. QISS image quality exceeded that of free-breathing 3D coronary MRA with few artifacts at either field strength. Compared with T2-prepared 2D bSSFP, multi-slice capability was not restricted by the specific absorption rate at 3 Tesla and pericardial fluid signal was better suppressed. In addition to depicting the coronary arteries, QISS could image intra-cardiac structures, pericardium, and the aortic root in arbitrary slice orientations. Breath-hold QISS is a simple, versatile, and time-efficient method for coronary MRA that provides excellent image quality at both 1.5 and 3 Tesla. Image quality exceeded that of free-breathing, navigator-gated 3D MRA in a much shorter scan time. QISS also allowed rapid multi-slice bright-blood, diastolic phase imaging of the heart, which may have complementary value to multi-phase cine imaging. We conclude that, with further clinical

  19. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Stillman, A.E.; Wilke, N.; Li, D.

    Our goal was to determine the feasibility of using an intravascular MR contrast agent to improve 3D MRA. Three-dimensional TOF MRA was performed in nine patients both prior to and following the administration of an ultrasmall particle superparamagnetic iron oxide contrast agent (AMI 227). The lengths of both renal arteries were measured from the maximum intensity projection (MIP) images as well as the individual partitions. Seven of these patients also were studied by a 3D coronary artery MRA sequence. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) measurements of the right coronary artery were determined both prior to and following themore » administration of AMI 227. Statistical analysis of both renal artery lengths and right coronary SNR and CNR was performed using a one tailed paired t test comparing pre- and postcontrast images. The renal artery lengths significantly increased (right renal artery: 30%, p = 0.001; left renal artery: 25%, p < 0.008) when measured from the individual axial slice partitions. No significant increase in length was observed on the MIP images following contrast. In the right coronary artery, the SNR increased by an average of 80% (p = 0.008) and CNR increased by an average of 109% (p = 0.007). Increased background signal and superimposed venous structures reduced the measurable lengths of the renal arteries from the MIP images. These studies support the hypothesis that 3D MRA in the body will benefit from the use of intravascular contrast agents. Nevertheless, conventional MIP processing is unable to reveal the full advantage of the contrast improvement. 14 refs., 6 figs., 2 tabs.« less

  20. An online psychological intervention can improve the sexual satisfaction of men following treatment for localized prostate cancer: outcomes of a Randomised Controlled Trial evaluating My Road Ahead.

    PubMed

    Wootten, Addie C; Meyer, Denny; Abbott, Jo-Anne M; Chisholm, Katherine; Austin, David W; Klein, Britt; McCabe, Marita; Murphy, Declan G; Costello, Anthony J

    2017-07-01

    Prostate cancer treatment often results in significant psycho-sexual challenges for men following treatment; however, many men report difficulty in accessing appropriate care. A randomized controlled trial was undertaken to assess the efficacy of a 10-week self-guided online psychological intervention called My Road Ahead (MRA) for men with localized prostate cancer in improving sexual satisfaction. Participants were randomized to 1 of 3 conditions MRA alone or MRA plus online forum, or forum access alone. Pre, post, and follow-up assessments of overall sexual satisfaction were conducted. Mixed models and structural equation modeling were used to analyze the data. One hundred forty-two men (mean age 61 y; SD = 7) participated. The majority of participants had undergone radical prostatectomy (88%) and all men had received treatment for localized prostate cancer. Significant differences were obtained for the 3 groups (P = .026) and a significant improvement in total sexual satisfaction was observed only for participants who were allocated to MRA + forum with a large effect size (P = .004, partial η 2  = 0.256). Structural equation modeling indicated that increases in sexual function, masculine self-esteem, and sexual confidence contributed significantly to overall sexual satisfaction for the MRA + forum plus forum condition. This study is the first, to our knowledge, that has evaluated a self-guided online psychological intervention tailored to the specific needs of men with prostate cancer. The findings indicate the potential for MRA to deliver support that men may not otherwise receive and also highlight the importance of psychological intervention to facilitate improved sexual outcomes. Copyright © 2016 John Wiley & Sons, Ltd.

  1. Neurovascular Study of the Trigeminal Nerve at 3 T MRI

    PubMed Central

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

    2015-01-01

    This study aimed to show a novel visualization method to investigate neurovascular compression of the trigeminal nerve (TN) using a volume-rendering fusion imaging technique of 3D fast imaging employing steady-state acquisition (3D FIESTA) and coregistered 3D time of flight MR angiography (3D TOF MRA) sequences, which we called “neurovascular study of the trigeminal nerve”. We prospectively studied 30 patients with unilateral trigeminal neuralgia (TN) and 50 subjects without symptoms of TN (control group), on a 3 Tesla scanner. All patients were assessed using 3D FIESTA and 3D TOF MRA sequences centered on the pons, as well as a standard brain protocol including axial T1, T2, FLAIR and GRE sequences to exclude other pathologies that could cause TN. Post-contrast T1-weighted sequences were also performed. All cases showing arterial imprinting on the trigeminal nerve (n = 11) were identified on the ipsilateral side of the pain. No significant relationship was found between the presence of an artery in contact with the trigeminal nerve and TN. Eight cases were found showing arterial contact on the ipsilateral side of the pain and five cases of arterial contact on the contralateral side. The fusion imaging technique of 3D FIESTA and 3D TOF MRA sequences, combining the high anatomical detail provided by the 3D FIESTA sequence with the 3D TOF MRA sequence and its capacity to depict arterial structures, results in a tool that enables quick and efficient visualization and assessment of the relationship between the trigeminal nerve and the neighboring vascular structures. PMID:25924169

  2. Computational biomechanics to simulate the femoropopliteal intersection during knee flexion: a preliminary study.

    PubMed

    Diehm, Nicolas; Sin, Sangmun; Hoppe, Hanno; Baumgartner, Iris; Büchler, Philippe

    2011-06-01

    To assess if finite element (FE) models can be used to predict deformation of the femoropopliteal segment during knee flexion. Magnetic resonance angiography (MRA) images were acquired on the lower limbs of 8 healthy volunteers (5 men; mean age 28 ± 4 years). Images were taken in 2 natural positions, with the lower limb fully extended and with the knee bent at ~ 40°. Patient-specific FE models were developed and used to simulate the experimental situation. The displacements of the artery during knee bending as predicted by the numerical model were compared to the corresponding positions measured on the MRA images. The numerical predictions showed a good overall agreement between the calculated displacements of the motion measures from MRA images. The average position error comparing the calculated vs. actual displacements of the femoropopliteal intersection measured on the MRA was 8 ± 4 mm. Two of the 8 subjects showed large prediction errors (average 13 ± 5 mm); these 2 volunteers were the tallest subjects involved in the study and had a low body mass index (20.5 kg/m²). The present computational model is able to capture the gross mechanical environment of the femoropopliteal intersection during knee bending and provide a better understanding of the complex biomechanical behavior. However, results suggest that patient-specific mechanical properties and detailed muscle modeling are required to provide accurate patient-specific numerical predictions of arterial displacement. Further adaptation of this model is expected to provide an improved ability to predict the multiaxial deformation of this arterial segment during leg movements and to optimize future stent designs.

  3. Effects of mineralocorticoid receptor antagonists in patients with hypertension and diabetes mellitus: a systematic review and meta-analysis.

    PubMed

    Takahashi, S; Katada, J; Daida, H; Kitamura, F; Yokoyama, K

    2016-09-01

    Blood pressure (BP) control is important to ameliorate cardiovascular events in patients with diabetes mellitus (DM). However, achieving the target BP with a single drug is often difficult. The objective of this study was to evaluate the antihypertensive effects of mineralocorticoid receptor antagonists (MRAs) as add-on therapy to renin-angiotensin system (RAS) inhibitor(s) in patients with hypertension and DM. Studies were searched through October 2014 in MEDLINE, Embase and the Cochrane Central Register of Controlled Trials. Randomized, controlled trials or prospective, observational studies regarding concomitant administration of MRA and RAS inhibitor(s) in patients with DM were included. Articles were excluded if the mean systolic BP (SBP) was <130 mm Hg before randomization for interventional studies or at baseline for prospective cohort studies. We identified nine eligible studies (486 patients): five randomized placebo-controlled trials; three randomized active drug-controlled trials; and one single-arm observational study. The mean differences in office SBP and diastolic BP (DBP) between the MRA and placebo groups were -9.4 (95% confidence interval (CI) -12.9 to -5.9) and -3.8 (95% CI, -5.5 to -2.2) mm Hg, respectively. Subgroup analysis results for study type, age, baseline office SBP and follow-up duration were similar to those of the main analysis. MRA mildly increased serum potassium (0.4 mEq l(-1); 95% CI, 0.3-0.5 mEq l(-1)). A consistent reduction of albuminuria across these studies was also demonstrated. MRA further reduced SBP and DBP in patients with hypertension and DM already taking RAS inhibitors. Serum potassium levels should be monitored to prevent hyperkalemia.

  4. Differential Diagnosis of Benign and Malignant Intraductal Papillary Mucinous Tumors of the Pancreas: MR Cholangiopancreatography and MR Angiography

    PubMed Central

    Choi, Byung Se; Kim, Ah Young; Kim, Kyoung Won; Park, Sung Won; Kim, Pyo Nyun; Ha, Hyun Kwon; Lee, Moon-Gyu; Kim, Song Cheol

    2003-01-01

    Objective To compare the usefulness of magnetic resonance cholangiopancreatography (MRCP) and MR angiography (MRA) in differentiating malignant from benign intraductal papillary mucinous tumors of the pancreas (IPMTs), and to determine the findings which suggest malignancy. Materials and Methods During a 6-year period, 46 patients with IPMT underwent MRCP. Morphologically, tumor type was classified as main duct, branch duct, or combined. The diameter of the main pancreatic duct (MPD), the extent of the dilated MPD, and the location and size of the cystic lesion, septum, and communicating channel were assessed. For all types of IPMTs, enhanced mural nodules and portal vein narrowing were evaluated at MRA. Results Combined-type IPMTs were more frequently malignant (78%) than benign (42%) (p < 0.05). Compared with benign lesions, malignant lesions were larger, and the caliber of the communicating channel was also larger (p < 0.05). Their dilated MPD was more extensive and of greater diameter (p < 0.05), and the presence of mural nodules was more frequent (p < 0.001). Conclusion Combined MRCP and MRA might be useful for the differential diagnosis of malignant and benign IPMTs of the pancreas. PMID:14530644

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

    PubMed

    Randić, M

    2001-01-01

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

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

    PubMed

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

    2015-08-15

    Coarctation of the aorta (CofA) has been associated with an increased risk of intracranial aneurysm (IA). This magnetic resonance angiography (MRA) study investigates the prevalence of IAs in 80 children treated in early life for CofA. MRA was performed at mean age of 15.7 ± 7.1 years, and surgical or endovascular treatment for CofA occurred at a mean age of 2.6 ± 4.4 years. No IA was found. In contrast with earlier findings in adult patients with late treatment for CofA, this first systematic study of very early treated patients for CofA failed to confirm the association between CofA and IAs. Our results call the abnormal developmental relation between CofA and IAs into question and suggest that modifiable risk factors like hypertension may be responsible for IA development in patients with CofA with adult diagnosis and treatment. In conclusion, our data suggest that early treatment of CofA can reduce the formation of IAs in children so as to make MRA screening less valuable in this young population. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. Marine ecological risk assessment methods for radiation accidents.

    PubMed

    Ye, Sufen; Zhang, Luoping; Feng, Huan

    2017-12-01

    Ecological risk assessment (ERA) is a powerful technical tool that can be used to analyze potential and extreme adverse environmental impacts. With the rapid development of nuclear power plants in coastal areas around the world, the establishment of approaches and methodologies for marine ERA with a focus on radiation accidents is an urgent requirement for marine environmental management. In this study, the approaches and methodologies for ERA pertaining to marine radiation accidents (MRA) are discussed and summarized with applications in case studies, such as the nuclear accident in Fukushima, Japan, and a hypothetical accident in Daya Bay, China. The concepts of ERA and Risk Degree of ERA on MRA are defined for the first time to optimize the ERA system. The results of case studies show that the ERA approach and methodology for MRA are scientifically sound and effective in both the early and late stage of MRAs along with classic ERA Approach and the ERICA Integrated Approach. The results can be useful in the decision-making processes and the risk management at the beginning of accident as well as the ecological restoration after the accident. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Posterior reversible encephalopathy with late postpartum eclampsia and short-term memory loss: a case report.

    PubMed

    Gimovsky, Martin L; Guzman, Guillermo M; Koscica, Karen L; Nazir, Munir A; Ross, Diane E

    2010-01-01

    Late postpartum eclampsia is more frequently recognized than past reports indicate. This report describes the association of a reversible encephalopathy in a woman with late postpartum eclampsia. A woman with lupus nephritis presented 7 days postpartum with eclampsia. Postseizure findings included dramatic short-term memory loss. Although a computed tomography scan was negative, subsequent magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) demonstrated vascular changes associated with a reversible encephalopathy. Conservative treatment with analeptic and antihypertensive therapy allowed a rapid resolution of all symptomatology. In women with eclampsia and unusual neurologic findings, an MRI/MRA may be useful even in the presence of a negative computed tomography scan.

  9. Arterial imaging in patients with lower extremity ischemia and diabetes mellitus.

    PubMed

    Pomposelli, Frank

    2010-09-01

    Precise, comprehensive imaging of the arterial circulation is the cornerstone of successful revascularization of the ischemic extremity in patients with diabetes mellitus. Arterial imaging is challenging in these patients because the disease is often multisegmental with a predilection for the distal tibial and peroneal arteries. Occlusive lesions and the arterial wall itself are often calcified and patients presenting with ischemic complications frequently have underlying renal insufficiency. Intra-arterial digital subtraction angiography (DSA), contrast enhanced magnetic resonance angiography (MRA), and more recently, computerized tomographic angiography (CTA) have been used as imaging modalities in lower extremity ischemia. Each has specific advantages and shortcomings in this patient population, which will be summarized and contrasted in this review. DSA is an invasive technique most often performed from a femoral arterial puncture and requires the injection of arterial contrast, which can occasionally cause allergic reactions. In patients with pre-existing renal insufficiency, contrast infusion can result in worsening renal failure; although usually self-limited, it may occasionally require hemodialysis, especially in patients with diabetes. However, DSA provides the highest degree of spatial resolution and image quality. It is also the only modality in which the diagnosis and treatment of arterial disease can be performed simultaneously. MRA is noninvasive, and when enhanced with gadolinium contrast injection provides arterial images of comparable quality to DSA and in some circumstances may uncover distal arterial targets not visualized on DSA. However, spatial resolution is inferior to DSA and erroneous interpretations due to acquisition artifacts are common. Specialized equipment and imaging techniques are necessary to minimize their occurrence in the distal lower extremity. In addition, due to the risk of inducing nephrogenic systemic fibrosis, gadolinium

  10. 4D flow MRI assessment of extracranial-intracranial bypass: qualitative and quantitative evaluation of the hemodynamics.

    PubMed

    Sekine, Tetsuro; Takagi, Ryo; Amano, Yasuo; Murai, Yasuo; Orita, Erika; Matsumura, Yoshio; Kumita, Shin-Ichiro

    2016-03-01

    Our aim was to assess the feasibility of using time-resolved 3D phase-contrast (4D flow) MRI to characterize extracranial-intracranial (EC-IC) bypass. We enrolled 32 patients who underwent EC-IC bypass (15 men, 17 women; mean age 66.4 years). In all, 16 underwent radial artery graft (RAG) bypass and 16 underwent superficial temporal artery (STA) bypass. 4D flow MRI, time-of-flight (TOF) magnetic resonance angiography (MRA), and computed tomography angiography (CTA) were performed. Bypass patency, flow direction, and blood flow volume (BFV) of each artery were determined by 4D flow MRI. Arterial diameters were measured by TOF-MRA and CTA. We compared RAG and STA bypasses by evaluating the flow direction and BFV of each artery. We evaluated the correlation between arterial diameters (measured by CTA or MRA) and the BFV and the detectability of flow direction (measured by 4D flow MRI) of each artery. 4D flow MRI confirmed the patency of each bypass artery. Flow direction of the M1 segment of the middle cerebral artery and BFV in the bypass artery differed between RAG and STA groups (p < 0.01). BFV in the bypass slightly correlated with the diameters on CTA (p < 0.05, R (2) = 0.287). Of the 29 arteries in the circle of Willis, nine were not depicted on 4D flow MRI. Cutoff values for arterial diameters on CTA and TOF-MRA for detecting the artery on 4D flow MRI were 2.4 and 1.8 mm, respectively. 4D flow MRI provided unique information for characterizing EC-IC bypasses, although this detectability is limited when addressing small arteries with slow flow.

  11. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hentschke, Clemens M., E-mail: clemens.hentschke@gmail.com; Tönnies, Klaus D.; Beuing, Oliver

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

  12. Validation of an arterial tortuosity measure with application to hypertension collection of clinical hypertensive patients.

    PubMed

    Diedrich, Karl T; Roberts, John A; Schmidt, Richard H; Kang, Chang-Ki; Cho, Zang-Hee; Parker, Dennis L

    2011-10-18

    Hypertension may increase tortuosity or twistedness of arteries. We applied a centerline extraction algorithm and tortuosity metric to magnetic resonance angiography (MRA) brain images to quantitatively measure the tortuosity of arterial vessel centerlines. The most commonly used arterial tortuosity measure is the distance factor metric (DFM). This study tested a DFM based measurement's ability to detect increases in arterial tortuosity of hypertensives using existing images. Existing images presented challenges such as different resolutions which may affect the tortuosity measurement, different depths of the area imaged, and different artifacts of imaging that require filtering. The stability and accuracy of alternative centerline algorithms was validated in numerically generated models and test brain MRA data. Existing images were gathered from previous studies and clinical medical systems by manually reading electronic medical records to identify hypertensives and negatives. Images of different resolutions were interpolated to similar resolutions. Arterial tortuosity in MRA images was measured from a DFM curve and tested on numerically generated models as well as MRA images from two hypertensive and three negative control populations. Comparisons were made between different resolutions, different filters, hypertensives versus negatives, and different negative controls. In tests using numerical models of a simple helix, the measured tortuosity increased as expected with more tightly coiled helices. Interpolation reduced resolution-dependent differences in measured tortuosity. The Korean hypertensive population had significantly higher arterial tortuosity than its corresponding negative control population across multiple arteries. In addition one negative control population of different ethnicity had significantly less arterial tortuosity than the other two. Tortuosity can be compared between images of different resolutions by interpolating from lower to higher

  13. Comparative analysis of fluorescent angiography, computed tomographic angiography and magnetic resonance angiography for planning autologous breast reconstruction

    PubMed Central

    Chae, Michael P.; Hunter-Smith, David J.

    2015-01-01

    Background The high incidence of breast cancer and growing number of breast cancer patients undergoing mastectomy has led to breast reconstruction becoming an important part of holistic treatment for these patients. In planning autologous reconstructions, preoperative assessment of donor site microvascular anatomy with advanced imaging modalities has assisted in the appropriate selection of flap donor site, individual perforators, and lead to an overall improvement in flap outcomes. In this review, we compare the accuracy of fluorescent angiography, computed tomographic angiography (CTA), and magnetic resonance angiography (MRA) and their impact on clinical outcomes. Methods A review of the published English literature dating from 1950 to 2015 using databases, such as PubMed, Medline, Web of Science, and EMBASE was undertaken. Results Fluorescent angiography is technically limited by its inability to evaluate deep-lying perforators and hence, it has a minimal role in the preoperative setting. However, it may be useful intraoperatively in evaluating microvascular anastomotic patency and the mastectomy skin perfusion. CTA is currently widely considered the standard, due to its high accuracy and reliability. Multiple studies have demonstrated its ability to improve clinical outcomes, such as operative length and flap complications. However, concerns surrounding exposure to radiation and nephrotoxic contrast agents exist. MRA has been explored, however despite recent advances, the image quality of MRA is considered inferior to CTA. Conclusions Preoperative imaging is an essential component in planning autologous breast reconstruction. Fluorescent angiography presents minimal role as a preoperative imaging modality, but may be a useful intraoperative adjunct to assess the anastomosis and the mastectomy skin perfusion. Currently, CTA is the gold standard preoperatively. MRA has a role, particularly for women of younger age, iodine allergy, and renal impairment. PMID

  14. Noncontrast magnetic resonance angiography of the hand: improved arterial conspicuity by multidirectional flow-sensitive dephasing magnetization preparation in 3D balanced steady-state free precession imaging.

    PubMed

    Fan, Zhaoyang; Hodnett, Philip A; Davarpanah, Amir H; Scanlon, Timothy G; Sheehan, John J; Varga, John; Carr, James C; Li, Debiao

    2011-08-01

    : To develop a flow-sensitive dephasing (FSD) preparative scheme to facilitate multidirectional flow-signal suppression in 3-dimensional balanced steady-state free precession imaging and to validate the feasibility of the refined sequence for noncontrast magnetic resonance angiography (NC-MRA) of the hand. : A new FSD preparative scheme was developed that combines 2 conventional FSD modules. Studies using a flow phantom (gadolinium-doped water 15 cm/s) and the hands of 11 healthy volunteers (6 males and 5 females) were performed to compare the proposed FSD scheme with its conventional counterpart with respect to the signal suppression of multidirectional flow. In 9 of the 11 healthy subjects and 2 patients with suspected vasculitis and documented Raynaud phenomenon, respectively, 3-dimensional balanced steady-state free precession imaging coupled with the new FSD scheme was compared with spatial-resolution-matched (0.94 × 0.94 × 0.94 mm) contrast-enhanced magnetic resonance angiography (0.15 mmol/kg gadopentetate dimeglumine) in terms of overall image quality, venous contamination, motion degradation, and arterial conspicuity. : The proposed FSD scheme was able to suppress 2-dimensional flow signal in the flow phantom and hands and yielded significantly higher arterial conspicuity scores than the conventional scheme did on NC-MRA at the regions of common digitals and proper digitals. Compared with contrast-enhanced magnetic resonance angiography, the refined NC-MRA technique yielded comparable overall image quality and motion degradation, significantly less venous contamination, and significantly higher arterial conspicuity score at digital arteries. : The FSD-based NC-MRA technique is improved in the depiction of multidirectional flow by applying a 2-module FSD preparation, which enhances its potential to serve as an alternative magnetic resonance angiography technique for the assessment of hand vascular abnormalities.

  15. Losartan reverses COX-2-dependent vascular dysfunction in offspring of hyperglycaemic rats.

    PubMed

    de Queiroz, Diego Barbosa; Ramos-Alves, Fernanda Elizabethe; Santos-Rocha, Juliana; Duarte, Gloria Pinto; Xavier, Fabiano Elias

    2017-09-01

    This study examined whether chronic treatment with losartan, an angiotensin II type 1 receptor (AT 1 R) antagonist, might reverse COX-2-mediated vascular dysfunction in mesenteric resistance arteries (MRA) from offspring of hyperglycaemic rats. Male 12-month-old offspring of hyperglycaemic (O-DR) and normoglycaemic (O-CR) rats were treated with losartan (15mg·kg·day -1 ) during 2months. Third order MRA of untreated and losartan-treated O-DR and O-CR were mounted in wire myograph for isometric tension measurements. COX-2 expression was analyzed by Western blot; TxA 2 , PGE 2 and PGF 2α release was measured using commercial kits. O-DR showed increased blood pressure, impaired acetylcholine-induced vasodilation and increased noradrenaline-induced vasoconstriction than O-CR. All these parameters were normalized by losartan in O-DR. Pre-incubation of MRA with indomethacin (COX-1/2 inhibitor), NS-398 (COX-2 inhibitor) or tempol (superoxide dismutase mimetic) increased relaxation to acetylcholine and reduced contraction to noradrenaline only in O-DR. COX-2 expression, TxA 2 , PGE 2 and PGF 2α release were increased in O-DR. In losartan-treated O-DR, NS-398, indomethacin or tempol failed to produce any effect on acetylcholine or noradrenaline responses. Losartan treatment reduced COX-2 expression, TxA 2 , PGE 2 and PGF 2α release in O-DR. The present results reveal that chronic losartan administration in O-DR normalizes endothelial function in MRA by correcting the existing COX-2 overexpression and the imbalance between endothelium-derived relaxing and contracting factors. These findings not only support the beneficial effects of AT 1 receptor antagonist in O-DR, but also suggest the implication of angiotensin II as a putative mediator of hyperglycemia-programmed vascular dysfunction in rats. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Multivariate analysis for the estimation of target localization errors in fiducial marker-based radiotherapy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Takamiya, Masanori; Nakamura, Mitsuhiro, E-mail: m-nkmr@kuhp.kyoto-u.ac.jp; Akimoto, Mami

    Purpose: To assess the target localization error (TLE) in terms of the distance between the target and the localization point estimated from the surrogates (|TMD|), the average of respiratory motion for the surrogates and the target (|aRM|), and the number of fiducial markers used for estimating the target (n). Methods: This study enrolled 17 lung cancer patients who subsequently underwent four fractions of real-time tumor tracking irradiation. Four or five fiducial markers were implanted around the lung tumor. The three-dimensional (3D) distance between the tumor and markers was at maximum 58.7 mm. One of the markers was used as themore » target (P{sub t}), and those markers with a 3D |TMD{sub n}| ≤ 58.7 mm at end-exhalation were then selected. The estimated target position (P{sub e}) was calculated from a localization point consisting of one to three markers except P{sub t}. Respiratory motion for P{sub t} and P{sub e} was defined as the root mean square of each displacement, and |aRM| was calculated from the mean value. TLE was defined as the root mean square of each difference between P{sub t} and P{sub e} during the monitoring of each fraction. These procedures were performed repeatedly using the remaining markers. To provide the best guidance on the answer with n and |TMD|, fiducial markers with a 3D |aRM ≥ 10 mm were selected. Finally, a total of 205, 282, and 76 TLEs that fulfilled the 3D |TMD| and 3D |aRM| criteria were obtained for n = 1, 2, and 3, respectively. Multiple regression analysis (MRA) was used to evaluate TLE as a function of |TMD| and |aRM| in each n. Results: |TMD| for n = 1 was larger than that for n = 3. Moreover, |aRM| was almost constant for all n, indicating a similar scale for the marker’s motion near the lung tumor. MRA showed that |aRM| in the left–right direction was the major cause of TLE; however, the contribution made little difference to the 3D TLE because of the small amount of motion in the left–right direction

  17. Comparison between digital subtraction angiography and magnetic resonance angiography in investigation of nonlacunar ischemic stroke in young patients: preliminary results.

    PubMed

    Conforto, Adriana Bastos; Fregni, Felipe; Puglia, Paulo; Leite, Claudia da Costa; Yamamoto, Fabio Iuji; Coracini, Karen F; Scaff, Milberto

    2006-06-01

    We preliminarily investigated the relevance of performing digital subtraction angiography (DSA) in addition to magnetic resonance angiography (MRA) in definition of ischemic stroke etiology in young patients. DSAs and MRAs from 17 young patients with nonlacunar ischemic stroke were blindly analyzed and their impact on stroke management was evaluated. Etiologies were the same considering results of either DSA or MRA in 12/17 cases. In 15/17 patients no changes would have been made in treatment, regardless of the modality of angiography considered. These preliminary results suggest that DSA may be redundant in two thirds of ischemic strokes in young patients. Further larger prospective studies are necessary to determine indications of DSA in this age group.

  18. DOE Office of Scientific and Technical Information (OSTI.GOV)

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

    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 andmore » 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.« less

  19. A geographical information system (GIS) as a tool for microbial risk assessment in catchment areas of drinking water reservoirs.

    PubMed

    Kistemann, T; Dangendorf, F; Exner, M

    2001-03-01

    The main tributaries of three drinking water reservoirs of Northrhine-Westfalia (Germany) were monitored within a 14-month period mainly for bacterial and parasitic contamination. In this context a detailed geo-ecological characterisation within the differing catchment areas was carried out to reveal a reliable informational basis for tracing back the origin of microbial loads present in the watercourses. To realise a microbial risk assessing geo-ecological information system (MRA-GIS), a Geographical Information System (GIS) has been implemented for the study areas. The results of the microbiological investigations of the watercourses showed an input of pathogens into all three of the tributaries. It could be demonstrated that the use of MRA-GIS database and some GIS-techniques substantially support the spatial analysis of the microbial contamination patterns. From the hygienic point of view, it is of the utmost importance to protect catchment areas of surface water reservoirs from microbial contamination stemming from human activities and animal sources. This constitutes essential part of the multi-barrier concept which stresses the importance of reducing diffuse and point pollution in catchment areas of water resources intended for human consumption. MRA-GIS proves to be helpful to manage multi-barrier water protection in catchment areas and ideally assists the application of the HACCP concept on drinking water production.

  20. VizieR Online Data Catalog: VLT Survey Telescope ATLAS (Shanks+, 2015)

    NASA Astrophysics Data System (ADS)

    Shanks, T.; Metcalfe, N.; Chehade, B.; Findlay, J. R.; Irwin, M. J.; Gonzalez-Solares, E.; Lewis, J. R.; Yoldas, A. K.; Mann, R. G.; Read, M. A.; Sutorius, E. T. W.; Voutsinas, S.

    2017-11-01

    The ATLAS sky coverage consists of two contiguous blocks in the North and South galactic caps. The ATLAS South Galactic Cap (SGC) area lies between 21h30m<04h00m and -40°m<15h30m and -20°m<15h00m and -30°

  1. LETTER TO THE EDITOR: Free-response operator characteristic models for visual search

    NASA Astrophysics Data System (ADS)

    Hutchinson, T. P.

    2007-05-01

    Computed tomography of diffraction enhanced imaging (DEI-CT) is a novel x-ray phase-contrast computed tomography which is applied to inspect weakly absorbing low-Z samples. Refraction-angle images which are extracted from a series of raw DEI images measured in different positions of the rocking curve of the analyser can be regarded as projections of DEI-CT. Based on them, the distribution of refractive index decrement in the sample can be reconstructed according to the principles of CT. How to combine extraction methods and reconstruction algorithms to obtain the most accurate reconstructed results is investigated in detail in this paper. Two kinds of comparison, the comparison of different extraction methods and the comparison between 'two-step' algorithms and the Hilbert filtered backprojection (HFBP) algorithm, draw the conclusion that the HFBP algorithm based on the maximum refraction-angle (MRA) method may be the best combination at present. Though all current extraction methods including the MRA method are approximate methods and cannot calculate very large refraction-angle values, the HFBP algorithm based on the MRA method is able to provide quite acceptable estimations of the distribution of refractive index decrement of the sample. The conclusion is proved by the experimental results at the Beijing Synchrotron Radiation Facility.

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

    PubMed

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

    2016-08-01

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

  3. Effects of size of ingestively masticated fragments of plant tissues on kinetics of digestion of NDF.

    PubMed

    Ellis, W C; Mahlooji, M; Lascano, C E; Matis, J H

    2005-07-01

    Ingestively masticated fragments were collected and sized via sieving. Different sizes of esophageal masticate and ruminal digesta fragments, and ground fragments of larger masticated pieces were incubated in vitro, and undigested NDF remaining at intervals of up to 168 h of incubation was determined. The ruminal age-dependent time delay (tau) for onset of digestion of NDF was positively correlated (P < 0.004) with the mean sieve aperture estimated to retain 50% of the fragments between successive sieve apertures (MRA). Degradation rate of potentially degradable NDF (PDF) and level of indigestible NDF were not related (P > 0.10) to MRA of masticated and ground fragments. Estimates of tau were positively related to MRA, with slopes of bermudagrass < corn silage < ruminal fragments of corn silage. It was concluded that fragment size-, and consequently, ruminal age-dependent onset of PDF degradation of a mixture of different fragment sizes results in an age-dependent rate of degradation of the more rapidly degrading of two subentities of PDF. Models are proposed that assume a tau before onset of simultaneous degradation of PDF from two pools characterized as having gamma-modeled age-dependency and age-constant rates. The ruminal age-dependent pool seems to be associated with the faster-degrading pool, and its rate parameter increases with range in MRA in the population of fragments. Conceptually, the ruminal age-dependent rate parameter for PDF degradation seems to represent a composite of several effects: 1) effects of the size-dependent tau; 2) range in MRA of the population of ingestively masticated fragments; and 3) subentities of PDF that degrade via more rapid age-dependent rates compared with subentities of PDF that degrade via age-constant rates. The estimated fractional rates of ruminative comminution of ingestively masticated fragments (0.060 to 0.075/h) were of a magnitude similar to the mean fractional rates of PDF digestion (0.030 to 0.085/h), which

  4. Feasibility of ferumoxytol-enhanced neonatal and young infant cardiac MRI without general anesthesia.

    PubMed

    Lai, Lillian M; Cheng, Joseph Y; Alley, Marcus T; Zhang, Tao; Lustig, Michael; Vasanawala, Shreyas S

    2017-05-01

    To assess the feasibility of ferumoxytol-enhanced anesthesia-free cardiac MRI in neonates and young infants for complex congenital heart disease (CHD). With Institutional Review Board approval, 21 consecutive neonates and young infants (1 day to 11 weeks old; median age of 3 days) who underwent a rapid two-sequence (MR angiography [MRA] and four-dimensional [4D] flow) MRI protocol with intravenous ferumoxytol without sedation (n = 17) or light sedation (n = 4) at 3 Tesla (T) (except one case at 1.5T) between June 2014 and February 2016 were retrospectively identified. Medical records were reviewed for indication, any complications, if further diagnostic imaging was performed after MRI, and surgical findings. Two radiologists scored the images in two sessions on a 5-point scale for overall image quality and delineation of various anatomical structures. Confidence interval of proportions for likelihood of requiring additional diagnostic imaging after MRI was determined. For the possibility of reducing the protocol to a single rapid sequence, Wilcoxon-rank sum test was used to assess whether 4D flow and MRA significantly differed in anatomical delineation. One of 21 patients (4.8%, 80% confidence interval 0-11%) required additional imaging, a computed tomography angiography to assess lung parenchyma and peripheral pulmonary arteries. Only 1 of 13 patients (7.7%) with operative confirmation had a minor discrepancy between radiology and operative reports (80% confidence interval 0-17%). 4D flow was significantly superior to MRA (P < 0.05) for the evaluation of systemic arteries, valves, ventricular trabeculae, and overall quality. Using Cohen's kappa coefficient, there was good interobserver agreement for the evaluation of systemic arteries by 4D flow (κ = 0.782), and systemic veins and pulmonary arteries by MRA (κ > 0.6). Overall 4D flow measurements (mean κ = 0.64-0.74) had better internal agreement compared with MRA (mean κ = 0

  5. [Accreditation of clinical laboratories based on ISO standards].

    PubMed

    Kawai, Tadashi

    2004-11-01

    International Organization for Standardization (ISO) have published two international standards (IS) to be used for accreditation of clinical laboratories; ISO/IEC 17025:1999 and ISO 15189:2003. Any laboratory accreditation body must satisfy the requirements stated in ISO/IEC Guide 58. In order to maintain the quality of the laboratory accreditation bodies worldwide, the International Laboratory Accreditation Cooperation (ILAC) has established the mutual recognition arrangement (MRA). In Japan, the International Accreditation Japan (IAJapan) and the Japan Accreditation Board for Conformity Assessment (JAB) are the members of the ILAC/MRA group. In 2003, the Japanese Committee for Clinical Laboratory Standards (JCCLS) and the JAB have established the Development Committee of Clinical Laboratory Accreditation Program (CLAP), in order to establish the CLAP, probably starting in 2005.

  6. DOE Office of Scientific and Technical Information (OSTI.GOV)

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

    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.more » 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.« less

  7. Quantitative contrast enhanced magnetic resonance imaging for the evaluation of peripheral arterial disease: a comparative study versus standard digital angiography.

    PubMed

    Pavlovic, Chris; Futamatsu, Hideki; Angiolillo, Dominick J; Guzman, Luis A; Wilke, Norbert; Siragusa, Daniel; Wludyka, Peter; Percy, Robert; Northrup, Martin; Bass, Theodore A; Costa, Marco A

    2007-04-01

    The purpose of this study is to evaluate the accuracy of semiautomated analysis of contrast enhanced magnetic resonance angiography (MRA) in patients who have undergone standard angiographic evaluation for peripheral vascular disease (PVD). Magnetic resonance angiography is an important tool for evaluating PVD. Although this technique is both safe and noninvasive, the accuracy and reproducibility of quantitative measurements of disease severity using MRA in the clinical setting have not been fully investigated. 43 lesions in 13 patients who underwent both MRA and digital subtraction angiography (DSA) of iliac and common femoral arteries within 6 months were analyzed using quantitative magnetic resonance angiography (QMRA) and quantitative vascular analysis (QVA). Analysis was repeated by a second operator and by the same operator in approximately 1 month time. QMRA underestimated percent diameter stenosis (%DS) compared to measurements made with QVA by 2.47%. Limits of agreement between the two methods were +/- 9.14%. Interobserver variability in measurements of %DS were +/- 12.58% for QMRA and +/- 10.04% for QVA. Intraobserver variability of %DS for QMRA was +/- 4.6% and for QVA was +/- 8.46%. QMRA displays a high level of agreement to QVA when used to determine stenosis severity in iliac and common femoral arteries. Similar levels of interobserver and intraobserver variability are present with each method. Overall, QMRA represents a useful method to quantify severity of PVD.

  8. The melanoma research alliance: the power of patient advocacy to accelerate research and novel therapies.

    PubMed

    Black, Debra; Brockway-Lunardi, Laura

    2013-12-01

    Patient advocacy organizations play a major role in accelerating research and are particularly important in a disease like melanoma, for which there is an urgent need for new tools and treatments. Melanoma is a growing public health burden. In the United States alone, the incidence of melanoma has tripled over the past 30 years, and one American dies every hour from the disease. To accelerate the field, the Melanoma Research Alliance (MRA) was founded in 2007 and is now the largest private funder of melanoma research, having invested more than $48 million in innovative and translational research projects worldwide to date. This investment is bearing fruit in the recent transformation of the melanoma clinical landscape, which has brought new hope to patients and their families. Yet, even with new drugs on the market, much more needs to be done until melanoma is effectively addressed. MRA is part of a growing group of nonprofit disease research foundations collectively called "venture philanthropies" that are playing a powerful role in transforming the outlook for their disease by overcoming barriers that bog down progress, targeting key areas, and enhancing collaboration. MRA is leading an innovative agenda to accelerate efforts on behalf of patients. Our goal, while significant, is straightforward: to end suffering and death due to melanoma. ©2013 AACR.

  9. Uncommon incidental pseudoaneurysm. Diagnostic and management challenges.

    PubMed

    Hadidy, Azmy M; Samara, Osama A; Takrouri, Heba S; Al-Ryalat, Nosaiba T; Al-Smady, Moaath M; Ryalat, Soukaina T; Abu-Khalaf, Mahmoad M

    2009-08-01

    To analyze patients with uncommon incidental pseudoaneurysms, secondary to non-catheterization causes, and to discuss the peculiar clinical spectrum, and focus on some aspects of difference from post-catheterization pseudoaneurysms. Eleven patients, 8 males and 3 females, were studied retrospectively in Jordan University Hospital, Amman, Jordan, between 2002-2008. Radiological studies performed included duplex sonography (DS), computed tomography (CT), conventional angiography, magnetic resonance imaging (MRI), and magnetic resonance angiography (MRA). Pseudoaneurysms were most commonly encountered in young males (63.6%), especially in the lower limb vessels (36%). Clinical findings were suggestive of pseudoaneurysms in 27% of our cases. Four out of the 8 DS scans showed the neck of pseudoaneurysms, and the to and fro waveform, the strongest indicators for pseudoaneurysms. Both CT with intravenous contrast and angiography failed to establish the diagnosis in one out of 5 cases. The MRI with MRA showed the pseudoaneurysms in 2 patients that underwent the scan. Incidental pseudoaneurysms are considered following iatrogenic procedures, penetrating, or blunt traumas with variable delay time. Young healthy males are at increased risks, as opposed to elderly females with calcified vessels in post-catheterization cases. Duplex sonography is less sensitive in incidental than post-catheterization pseudoaneurysms. The CT scan with intravenous contrast has high accuracy in establishing the diagnosis in small, or medium sized pseudoaneurysms. The MRI and MRA are accurate valuable studies and comparable to conventional angiography.

  10. MR angiography fusion technique for treatment planning of intracranial arteriovenous malformations.

    PubMed

    McGee, Kiaran P; Ivanovic, Vladimir; Felmlee, Joel P; Meyer, Fredrick B; Pollock, Bruce E; Huston, John

    2006-03-01

    To develop an image fusion technique using elliptical centric contrast-enhanced (CE) MR angiography (MRA) and three-dimensional (3D) time-of-flight (TOF) acquisitions for radiosurgery treatment planning of arteriovenous malformations (AVMs). CE and 3D-TOF MR angiograms with disparate in-plane fields of view (FOVs) were acquired, followed by k-space reformatting to provide equal voxel dimensions. Spatial domain addition was performed to provide a third, fused data volume. Spatial distortion was evaluated on an MRA phantom and provided slice-dependent and global distortion along the three physical dimensions of the MR scanner. In vivo validation was performed on 10 patients with intracranial AVMs prior to their conventional angiogram on the day of gamma knife radiosurgery. Spatial distortion in the phantom within a volume of 14 x 14 x 3.2 cm(3) was less than +/-1 mm (+/-1 standard deviation (SD)) for CE and 3D-TOF data sets. Fused data volumes were successfully generated for all 10 patients. Image fusion can be used to obtain high-resolution CE-MRA images of intracranial AVMs while keeping the fiducial markers needed for gamma knife radiosurgery planning. The spatial fidelity of these data is within the tolerance acceptable for daily quality control (QC) purposes and gamma knife treatment planning. (c) 2006 Wiley-Liss, Inc.

  11. Contribution of intracranial vertebral artery asymmetry to vestibular neuropathy.

    PubMed

    Chuang, Y M; Chern, C M; Liao, W H; Hsu, L C; Lien, C F; Lirng, J F; Shiao, A S; Ko, J S C

    2011-07-01

    To test the hypothesis that vertebral artery hypoplasia (VAH) may affect the lateralisation of vestibular neuropathy (VN), probably through haemodynamic effect on the vestibular labyrinth. 69 patients with unilateral VN were examined with a magnetic resonance angiographic (MRA) and caloric test. 50 healthy subjects served as controls. The diagnosis of intracranial VAH was based on MRA if <0.22 cm in VA diameter and a diameter asymmetry index >40%. The authors then correlated the canal paretic side with the VAH side. MRA study revealed 29 VAH (right/left: 23/6) in VN subjects and six VAH in controls (right/left: 5/1). The RR of VAH in VN subjects compared with controls was elevated (RR=2.2; 95% CI 1.8 to 2.8). There was a high accordance rate between the side of VAH and VN. Among 29 patients with unilateral VAH, 65.5% (N=19) had an ipsilateral VN, in which left VAH showed a higher accordance rate (83.3%) than the right side (60.9%). VN subjects with vascular risk factors also had a higher VAH accordance rate (81%) than those without (25%). VAH may serve as a regional haemodynamic negative contributor and impede blood supply to the ipsilateral vestibular labyrinth, contributing to the development of VN, which could be enhanced by atherosclerotic risk factors and the left-sided location.

  12. Phosphodiesterase-3 inhibitor cilostazol reverses endothelial dysfunction with ageing in rat mesenteric resistance arteries.

    PubMed

    Moreira, Hicla S; Lima-Leal, Geórgia A; Santos-Rocha, Juliana; Gomes-Pereira, Leonardo; Duarte, Gloria P; Xavier, Fabiano E

    2018-03-05

    Ageing impairs endothelial function, which is considered a hallmark of the development of cardiovascular diseases in elderly. Cilostazol, a phosphodiesterase-3 inhibitor, has antiplatelet, antithrombotic and protective effects on endothelial cells. Here, we hypothesized that cilostazol could improve endothelial function in mesenteric resistance arteries (MRA) from old rats. Using eight-week cilostazol-treated (100mg/kg/day) or untreated 72-week-old Wistar rats, we evaluate the relaxation to acetylcholine, sodium nitroprusside (SNP), forskolin and isoproterenol and the noradrenaline-induced contraction in MRA. Superoxide anion and nitric oxide (NO) was measured by dihydroethidium- and diaminofluorescein-2-emitted fluorescence, respectively. Normotensive old rats had impaired acetylcholine-induced NO- and EDHF-mediated relaxation and increased noradrenaline vasoconstriction than young rats. This age-associated endothelial dysfunction was restored by cilostazol treatment. Relaxation to SNP, forskolin or isoproterenol remained unmodified by cilostazol. Diaminofluorescein-2-emitted fluorescence was increased while dihydroethidium-emitted was decreased by cilostazol, indicating increased NO and reduced superoxide generation, respectively. Cilostazol improves endothelial function in old MRA without affecting blood pressure. This protective effect of cilostazol could be attributed to reduced oxidative stress, increased NO bioavailability and EDHF-type relaxation. Although these results are preliminary, we believe that should stimulate further interest in cilostazol as an alternative for the treatment of age-related vascular disorders. Copyright © 2018 Elsevier B.V. All rights reserved.

  13. Identification and reduction of image artifacts in non-contrast-enhanced velocity-selective peripheral angiography at 3T.

    PubMed

    Shin, Taehoon; Qin, Qin; Park, Jang-Yeon; Crawford, Robert S; Rajagopalan, Sanjay

    2016-08-01

    To identify and reduce image artifacts in non-contrast-enhanced velocity-selective (VS) magnetization-prepared peripheral MR angiography (MRA) at 3T. To avoid signal loss in the arteries, double and quadruple refocused VS excitation pulse sequences were designed that were robust to a wide range of B0 and B1 offset. To suppress stripe artifact and background signal variation, we successively applied two VS preparations with excitation profiles shifted by half the period of the stripes. VS-MRA using single, double, and quadruple refocused VS preparations was tested in healthy subjects and a patient. In the regions of large B0 and B1 offsets, arterial signal loss was yielded by single refocused VS preparation, but was avoided with double or quadruple refocused preparations. Compared with single VS preparation, the two consecutive preparations with shifted excitation profiles substantially reduced the stripe artifact and background signal variation, as demonstrated by increased mean and decreased standard deviation of relative contrast-to-noise ratio. The proposed VS-MRA identified multilevel disease in the femoral arteries of the patient, as validated by digital subtraction angiography. Two multiple refocused VS magnetization preparations with shifted excitation profiles yield artifact-free peripheral angiograms at 3T. Magn Reson Med 76:466-477, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  14. Rosmarinic acid improves function and in vitro fertilising ability of boar sperm after cryopreservation.

    PubMed

    Luño, Victoria; Gil, Lydia; Olaciregui, Maite; González, Noelia; Jerez, Rodrigo Alberto; de Blas, Ignacio

    2014-08-01

    During cryopreservation, oxidative stress exerts physical and chemical changes on sperm functionality. In the present study we investigated the antioxidant effect of rosmarinic acid (RA) on quality and fertilising ability of frozen-thawed boar spermatozoa. Ejaculates collected from mature boar were cryopreserved in lactose-egg yolk buffer supplemented with different concentrations of RA (0 μM, 26.25 μM, 52.5 μM and 105 μM). Motion parameters, acrosome and plasma membrane integrity, lipoperoxidation levels, DNA oxidative damage (8-hydroxy-2-deoxyguanosine base lesion) and in vitro fertilisation ability were evaluated. Total and progressive motility were significantly higher in experimental extenders with RA than in the control (P<0.05) at 0 and 120 min post-thawing. The plasma and acrosomal membrane integrity were improved by supplementation with 105 μMRA (P<0.05). Negative correlation between RA and malondialdehyde (MDA) concentration were determined (P<0.05). After thawing, the percentage of spermatozoa with oxidised DNA did not differ between extenders, however, at 120 and 240 min post-thawing, the samples supplemented with 105 μMRA showed the lowest DNA oxidation rate (P<0.05). The penetration rate was significantly higher on spermatozoa cryopreserved with 105 μMRA (P<0.05). The results suggest that RA provides a protection for boar spermatozoa against oxidative stress during cryopreservation by their antioxidant properties. Copyright © 2014 Elsevier Inc. All rights reserved.

  15. Reconstruction of dynamic image series from undersampled MRI data using data-driven model consistency condition (MOCCO).

    PubMed

    Velikina, Julia V; Samsonov, Alexey A

    2015-11-01

    To accelerate dynamic MR imaging through development of a novel image reconstruction technique using low-rank temporal signal models preestimated from training data. We introduce the model consistency condition (MOCCO) technique, which utilizes temporal models to regularize reconstruction without constraining the solution to be low-rank, as is performed in related techniques. This is achieved by using a data-driven model to design a transform for compressed sensing-type regularization. The enforcement of general compliance with the model without excessively penalizing deviating signal allows recovery of a full-rank solution. Our method was compared with a standard low-rank approach utilizing model-based dimensionality reduction in phantoms and patient examinations for time-resolved contrast-enhanced angiography (CE-MRA) and cardiac CINE imaging. We studied the sensitivity of all methods to rank reduction and temporal subspace modeling errors. MOCCO demonstrated reduced sensitivity to modeling errors compared with the standard approach. Full-rank MOCCO solutions showed significantly improved preservation of temporal fidelity and aliasing/noise suppression in highly accelerated CE-MRA (acceleration up to 27) and cardiac CINE (acceleration up to 15) data. MOCCO overcomes several important deficiencies of previously proposed methods based on pre-estimated temporal models and allows high quality image restoration from highly undersampled CE-MRA and cardiac CINE data. © 2014 Wiley Periodicals, Inc.

  16. Time-Resolved Three-Dimensional Contrast-Enhanced Magnetic Resonance Angiography in Patients with Chronic Expanding and Stable Aortic Dissections.

    PubMed

    Trojan, Michael; Rengier, Fabian; Kotelis, Drosos; Müller-Eschner, Matthias; Partovi, Sasan; Fink, Christian; Karmonik, Christof; Böckler, Dittmar; Kauczor, Hans-Ulrich; von Tengg-Kobligk, Hendrik

    2017-01-01

    To prospectively evaluate our hypothesis that three-dimensional time-resolved contrast-enhanced magnetic resonance angiography (TR-MRA) is able to detect hemodynamic alterations in patients with chronic expanding aortic dissection compared to stable aortic dissections. 20 patients with chronic or residual aortic dissection in the descending aorta and patent false lumen underwent TR-MRA of the aorta at 1.5 T and repeated follow-up imaging (mean follow-up 5.4 years). 7 patients showed chronic aortic expansion and 13 patients had stable aortic diameters. Regions of interest were placed in the nondissected ascending aorta and the false lumen of the descending aorta at the level of the diaphragm (FL-diaphragm level) resulting in respective time-intensity curves. For the FL-diaphragm level, time-to-peak intensity and full width at half maximum were significantly shorter in the expansion group compared to the stable group ( p = 0.027 and p = 0.003), and upward and downward slopes of time-intensity curves were significantly steeper ( p = 0.015 and p = 0.005). The delay of peak intensity in the FL-diaphragm level compared to the nondissected ascending aorta was significantly shorter in the expansion group compared to the stable group ( p = 0.01). 3D TR-MRA detects significant alterations of hemodynamics within the patent false lumen of chronic expanding aortic dissections compared to stable aortic dissections.

  17. RECONSTRUCTION OF DYNAMIC IMAGE SERIES FROM UNDERSAMPLED MRI DATA USING DATA-DRIVEN MODEL CONSISTENCY CONDITION (MOCCO)

    PubMed Central

    Velikina, Julia V.; Samsonov, Alexey A.

    2014-01-01

    Purpose To accelerate dynamic MR imaging through development of a novel image reconstruction technique using low-rank temporal signal models pre-estimated from training data. Theory We introduce the MOdel Consistency COndition (MOCCO) technique that utilizes temporal models to regularize the reconstruction without constraining the solution to be low-rank as performed in related techniques. This is achieved by using a data-driven model to design a transform for compressed sensing-type regularization. The enforcement of general compliance with the model without excessively penalizing deviating signal allows recovery of a full-rank solution. Methods Our method was compared to standard low-rank approach utilizing model-based dimensionality reduction in phantoms and patient examinations for time-resolved contrast-enhanced angiography (CE MRA) and cardiac CINE imaging. We studied sensitivity of all methods to rank-reduction and temporal subspace modeling errors. Results MOCCO demonstrated reduced sensitivity to modeling errors compared to the standard approach. Full-rank MOCCO solutions showed significantly improved preservation of temporal fidelity and aliasing/noise suppression in highly accelerated CE MRA (acceleration up to 27) and cardiac CINE (acceleration up to 15) data. Conclusions MOCCO overcomes several important deficiencies of previously proposed methods based on pre-estimated temporal models and allows high quality image restoration from highly undersampled CE-MRA and cardiac CINE data. PMID:25399724

  18. DOE Office of Scientific and Technical Information (OSTI.GOV)

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

    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 andmore » 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. Arthroscopic repair of massive contracted rotator cuff tears: aggressive release with anterior and posterior interval slides do not improve cuff healing and integrity.

    PubMed

    Kim, Sung-Jae; Kim, Sung-Hwan; Lee, Su-Keon; Seo, Jae-Wan; Chun, Yong-Min

    2013-08-21

    Few studies of large-to-massive contracted rotator cuff tears have examined the arthroscopic complete repair obtained by a posterior interval slide and whether the clinical outcomes or structural integrity achieved are better than those after partial repair without the posterior interval slide. The study included forty-one patients with large-to-massive contracted rotator cuff tears, not amenable to complete repair with margin convergence alone. The patients underwent either arthroscopic complete repair with a posterior interval slide and side-to-side repair of the interval slide edge (twenty-two patients; Group P) or partial repair with margin convergence (nineteen patients; Group M). The patient assignment was not randomized. The Simple Shoulder Test (SST), American Shoulder and Elbow Surgeons (ASES) score, University of California at Los Angeles (UCLA) shoulder score, and range of motion were used to compare the functional outcomes. Preoperative and six-month postoperative magnetic resonance arthrography (MRA) images were compared within or between groups. At the two-year follow-up evaluation, the SST, ASES score, UCLA score, and range of motion had significantly improved (p < 0.001 for all) in both groups. However, no significant differences were detected between groups. Even though the difference in preoperative tear size on MRA images was not significant, follow-up MRA images identified a retear in twenty patients (91%) in Group P and a significant difference in tear size between groups (p = 0.007). The complete repair group with an aggressive release had no better clinical or structural outcomes compared with the partial repair group with margin convergence alone for large-to-massive contracted rotator cuff tears. In addition, the complete repair group had a 91% retear rate and a greater defect on follow-up MRA images. Even though this study had a relatively short-term follow-up, a complete repair of large-to-massive contracted rotator cuff tears, with an

  20. Validation of an arterial tortuosity measure with application to hypertension collection of clinical hypertensive patients

    PubMed Central

    2011-01-01

    Background Hypertension may increase tortuosity or twistedness of arteries. We applied a centerline extraction algorithm and tortuosity metric to magnetic resonance angiography (MRA) brain images to quantitatively measure the tortuosity of arterial vessel centerlines. The most commonly used arterial tortuosity measure is the distance factor metric (DFM). This study tested a DFM based measurement’s ability to detect increases in arterial tortuosity of hypertensives using existing images. Existing images presented challenges such as different resolutions which may affect the tortuosity measurement, different depths of the area imaged, and different artifacts of imaging that require filtering. Methods The stability and accuracy of alternative centerline algorithms was validated in numerically generated models and test brain MRA data. Existing images were gathered from previous studies and clinical medical systems by manually reading electronic medical records to identify hypertensives and negatives. Images of different resolutions were interpolated to similar resolutions. Arterial tortuosity in MRA images was measured from a DFM curve and tested on numerically generated models as well as MRA images from two hypertensive and three negative control populations. Comparisons were made between different resolutions, different filters, hypertensives versus negatives, and different negative controls. Results In tests using numerical models of a simple helix, the measured tortuosity increased as expected with more tightly coiled helices. Interpolation reduced resolution-dependent differences in measured tortuosity. The Korean hypertensive population had significantly higher arterial tortuosity than its corresponding negative control population across multiple arteries. In addition one negative control population of different ethnicity had significantly less arterial tortuosity than the other two. Conclusions Tortuosity can be compared between images of different resolutions