730 research outputs found
MRA for radiosurgery of AVM
No full textPurpose: To investigate the discrepancy between the arteriovenous malformations
(AVMs) seen on magnetic resonance angiography (MRA), and seen on stereotactic digital subtracted angiography (DSA).
Materials and Methods: The target volume on stereotactic DSA (VDSA) and the target volume on MRA (VMRA) were separately delineated in 28 intracranial AVMs. The coordinates of the center and the outer edges of VDSA and VMRA were calculated and used for the analyses.
Results: The standard deviations (mean value) of the displacement of centers of VMRA from VDSA were 2.67mm (-1.82 mm) in the left-right direction, 3.23 mm (-0.08 mm) in the anterior-posterior direction, and 2.16 mm (0.91 mm) in the cranio-caudal direction.
VMRA covered less than 80% of VDSA 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 VDSA and 12.3 cc for VMRA (p=0.948).
Conclusion: The shift of centers between each modality is not negligible. Considering no significant difference between VDSA and VMRA, but inadequate coverage of the VDSA by VMRA, 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
Gas Injection Optimization to Increase Oil Production at MRA PT. PHE ONWJ
No full textThe MRA platform is one of the offshore platforms located in the north of the Java Sea. The MRA platform has 4 production wells, namely MRA-2ST, MRA-4ST, MRA-5, and MRA-6 wells. The 4 production wells are produced using an artificial lift in the form of a gas lift. The limited gas lift at the MRA Platform at 3.1 MMSCFD makes the production of wells at the MRA Platform not optimal because the wells in the MRA Platform are experiencing insufficient gas lift. Optimization of gas lift injection is obtained by redistribution of gas lift injection for each. The results of the analysis in this study indicate that the optimum gas lift injection for the MRA-2ST well is 0.5552 MMSCFD, the MRA-6 well is 1.0445 MMSCFD, the MRA-5 well is 0.7657 MMSCFD, finally the MRA-4ST well with gas injection. lift is 0.7346 MMSCFD. The manual gas lift in the MRA-4ST is also replaced based on an economic feasibility analysis to ensure that the gas lift injection for each well can be kept constant. The redistribution of gas lift carried out by the author has increased the total production rate of the MRA Platform by 11,160 BO/year or approximately USD 781,200/year. Keywords: Gas lift; Insufficient; Optimizatio
PERANAN MRA NON CONTRAST PADA PEMERIKSAAN MRI BRAIN DENGAN KASUS STROKE ISKEMIK
No full textBackground : As many as 87% of people have an ischemic stroke caused by blockage of blood flow to the brain. MR Angiography (MRA) is used to guide therapeutic decisions. Two methods of MRA without using contrast media, namely Time of Flight MR Angiography (TOF-MRA) and Phase Contrast MR Angiography (PC-MRA). 3-dimensional imaging has a high Signal to Noise Ratio (SNR) and can be seen from various sides compared to 2D. The author found several journals that discussed the use of 3D TOF and 3D PC in patients with clinical ischemic stroke. The purpose of this study was to determine the role of non-contrast MRA in the examination of MRI brain with ischemic stroke cases.Method : This research is a qualitative research study literature review approach using documentation data collection techniques. Searches were carried out using Google Scholar, Pubmed, and Mendeley Web. Limited searches using the keywords "3D TOF MRA", "3D PC MRA", "Stroke Ischemic". The journal is processed in the form of tables and analyzed data descriptively.Result : There were 6 journals, including 3 TOF MRA 3D journals, two PC MRA 3D journals, and 1 journal comparing 3D TOF MRA and 3D PC MRA in clinical ischemic stroke.Conclusion : The 3D role of the TOF MRA is being able to provide a three-dimensional initial diagnosis that can indicate the location of intracranial artery diseases such as occlusion, thrombus, stenosis and plaque. 3D PC MRA is used to predict the incidence of early cerebral ischemia that requires shunt placement by displaying anatomy and hemodynamics of blood vessel flow.Keywords: 3D TOF MRA, 3D PC MRA, Ischemic Stroke
Enkele beschouwingen in verband met de techniek van het afstandmeten met de tellurometer, in het bizonder met de tellurometer MRA 4
No full textZomer 1968 werd de Tellurometer MRA U aangeschaft door de Onderafdeling der Geodesie van de Technische Hogeschool te Delft. Deze radio-afstandmeter, die werkt op een golflengte van 8 mm, zou worden onderzocht op zijn bruikbaarheid voor het meten van primaire netten. Hoewel met dit instrument ook met hoge nauwkeurigheid korte afstanden gemeten kunnen worden, zal dit zelden de reden tot aanschaf zijn. Voor deze afstanden bestaat instrumentarium, dat ekonomisch beter verantwoord is ( de conventionele Geodimeters bij daglicht tot enkele kilometers bijvoorbeeld). Men denke hierbij vooral aan de hoge aanschafprijs van de MRA 4 (ƒ 90.000,—). Deze scriptie wil een verslag zijn van het onderzoek, dat is verricht om indikaties te verkrijgen betreffende de nauwkeurigheid, de betrouwbaarheid, de reproduceerbaarheid en het ekonomisch gebruik van de MRA U.Civil Engineering and Geoscience
MRA contextual-recovery extension of smooth functions on manifolds
No full textAbstractIn a recent paper, the first author introduced an MRA (multi-resolution or multi-level approximation) approach to extend an earlier work of Chan and Shen on image inpainting, from isotropic diffusion to anisotropic diffusion and from bi-harmonic extension to multi-level lagged anisotropic diffusion extension. The objective of the present paper is to extend and generalize this work to nonstationary smooth function extension to meet the goal of inpainting missing image features, while matching the existing image content without apparent visual artifact. Our result is formulated as an MRA contextual-recovery extension for the completion of smooth functions on manifolds by deriving an error formula, from which sharp error estimates can be derived. A novel estimate for the biharmonic operator derived in this paper is a formulation of the error bound in terms the volume, as opposed to the diameter, of the image hole
Draft genome sequence of Desulfurobacterium sp. Strain AV08, a Thermophilic Chemolithoautotroph isolated from a deep-sea hydrothermal vent
No full text© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Skoog, E. J., Huber, J. A., Serres, M. H., Levesque, A., & Zeigler Allen, L. Draft genome sequence of Desulfurobacterium sp. Strain AV08, a Thermophilic Chemolithoautotroph isolated from a deep-sea hydrothermal vent. Microbiology Resource Announcements, 10(34), (2021): e0061521, https://doi.org/10.1128/MRA.00615-21.A thermophilic chemolithoautotrophic bacterium was isolated from vent fluids at Axial Seamount, an active deep-sea volcano in the northeast Pacific Ocean. We present the draft genome sequence of Desulfurobacterium sp. strain AV08.This research was supported by the National Aeronautics and Space Administration Exobiology Program (grant 80NSSC18K1076 to L.Z.A. and J.A.H.). This study was also partially supported by the NSF Center for Dark Energy Biosphere Investigations (C-DEBI) (grant OCE-0939564 to J.A.H.)
MRA Study on Variation of the Circle of Willis in Healthy Chinese Male Adults
No full textAim. To investigate the morphology and variation of the circle of Willis (COW) in healthy Chinese male adults. Materials and Methods. We analyzed cerebral magnetic resonance angiography (MRA) images of 2,246 healthy subjects using typical magnetic resonance imaging (MRI) and MRA. 3D-time of flight (TOF) MRA method was applied to all subjects and the classification was therefore achieved according to the integrity level of COW and the developmental situation of vessels. Results. The overall incidence of COW integrity was 12.24%, with 7.57% nonvariation integral COW. The incidences of partial integrity and nonintegrity were 70.17% and 17.59%, respectively. The integrity rate of anterior circulation was 78.58%, with a close correlation with A1 segment of the anterior cerebral artery (ACA-A1) developmental condition. The developmental variation rate of ACA-A1 was 28.23% and the variation of the right side was higher than that of the left side. The nonintegrity rate of posterior circulation was 83.93% as the hypoplasia of P1 segment of the posterior cerebral artery (PCA-P1) with an incidence rate of 15.85% for PCA-P1 variation. Conclusions. The COW variation is a common phenomenon among the healthy subjects. MRA could enable reflecting the physiological morphology of COW in a comprehensive manner.Biotechnology & Applied MicrobiologyMedicine, Research & ExperimentalSCI(E)[email protected]
Alphaflexivirus genomes in stony coral tissue loss disease-affected, disease-exposed, and disease-unexposed coral colonies in the U.S. Virgin Islands
No full text© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Veglia, A., Beavers, K., Van Buren, E., Meiling, S., Muller, E., Smith, T., Holstein, D., Apprill, A., Brandt, M., Mydlarz, L., & Correa, A. Alphaflexivirus genomes in stony coral tissue loss disease-affected, disease-exposed, and disease-unexposed coral colonies in the U.S. Virgin Islands. Microbiology Resource Announcements, 11(2), (2022): e01199–e01121, https://doi.org/10.1128/mra.01199-21.Stony coral tissue loss disease (SCTLD) is decimating Caribbean corals. Here, through the metatranscriptomic assembly and annotation of two alphaflexivirus-like strains, we provide genomic evidence of filamentous viruses in SCTLD-affected, -exposed, and -unexposed coral colonies. These data will assist in clarifying the roles of viruses in SCTLD.This work was supported by the National Science Foundation (Biological Oceanography) award numbers 1928753 to M.E.B. and T.B.S., 1928609 to A.M.S.C., 1928817 to E.M.M., 19228771 to L.D.M., 1927277 to D.M.H., and 1928761 to A.A., as well as by VI EPSCoR (NSF numbers 0814417 and 1946412)
Comparement Between MRI and MRA finding in patients with Cerebral Infarction
No full text뇌경색은 고령인구에서 주요한 사망원인 중 하나이며 조기에 정확한진단을 하는 것은 환자의 치료 및 예후에 대단히 중요하다. 뇌경색에 대한 중재적 시술의 발달로 최근의 임상적 동향은 보다 더 조기의 정확한 진단적 접근 방식에 주안점을 두고 있는 실정이다.
이전까지 뇌경색의 진단방법으로 이용되어온 전산화단층촬영술(Computed Tomography; CT), 고식적 자기공명영상(Magnetic Resonance Imaging; MRI) 및 고식적 혈관조영술(Conventional Angiography; CA)등의 검사법들의 단점을 보완하면서 환자의 예후 평가에도 도움을 줄 수 있는 의의있는 검사법으로 자기공명혈관조영술 (Magnetic Resonance Angiography; MRA)이 널리 사용되고 있다.
저자는 1993년 10월부터 1995년 1월까지 본원을 방문하여 뇌경색으로 진단 받고 MRI 및 MRA를 시행받은 총 39명의 환자들을 대상으로 MRA상 뇌혈관 병변의 부위및 병변의 정도와, MRI에서의 뇌경색의 위치및 크기를 비교 분석하여 다음과 같은 결론을 얻었다.
1. 뇌간, 시상및 기저핵등의 관통동맥 영역의 2cm이하 크기의 소규모 뇌경색을 제외한다면 MRA에서 관찰되는 혈관 병변은 MRI상 뇌경색의 분포와 높은 일치율을 보였다(86％).
2. MRA상 양성소견을 보인 대다수의 증례(82％)에서 MRA는 다른 부위의 혈관병변이나 측부 순환혈관, 병변 지배영역 혈관의 정상적인 소견등의 MRI에서 관찰할 수 없었던 보다 정화한 정보를 제공하였다.
관통동맥 영역이 아닌 다른 부위의 뇌경색이 의심되는 환자에 있어서 MRI와 함께 MRA를 시행한다면 뇌경색을 조기에 정확히 진단할 수 있을 뿐 아니라, 부가적인 정보들을 얻을 수 있으므로 예후 추정 및 적절한 치료방법을 제시하고 예후를 추정하는데 도움이 될 것으로 사료된다.;MRA which is now becoming more and more popular, reinforces the certain drawbacks in the previous diagnostic methods and is considered to be useful as a screening test for it can also give a prognostic estimate of the brain infacrtions.
The author analyzed the correlation between the MRA and MRI findings of the 39 patients with cerebral infarction in Ewha Womans University medical center Mokdong Hospital in the recent one year. The location and severity of the vascular lesion in MRA was compared with the location and size of the infarct area in MRI. Conclusions are as follows:
1. There was a strong correlation between the vascular lesion observed by the MRA and the distribution of the infarct area in the MRI, except for the microinfarction of less than 2cm in diameter in the perforating arterial territories including brainstem, thalamus and basal ganglia.
2. MRA provided more diagnostic information in that positive findings were found in the parts otherwise not seen in the MRI, such as visualizing the unpredicted vascular lesions, the presence of collateral circulation and discovering normal circulation in the vessels preciously thought to be blocked.
The results of this single institutional study suggest that MRA undewent with the MRI may tend to suggest a less invasive treatment plan and provide us with a more exact diagnosis as well as predicting the prognosis. Moreover MRA can give additional findings which are not provided by MRI.목차 = ⅲ
논문개요 = ⅵ
Ⅰ. 서론 = 1
Ⅱ. 대상 및 방법 = 3
Ⅲ. 연구성적 = 6
Ⅳ. 고찰 = 8
Ⅴ. 결론 = 13
참고문헌 = 14
사진부도 및 설명 = 18
ABSTRACTS = 2
Utility of noncontrast-enhanced time-resolved four-dimensional MR angiography with a vessel-selective technique for intracranial arteriovenous malformations
No full textPurpose: To evaluate the utility of a vessel-selective four-dimensional (4D) magnetic resonance angiography (MRA) technique for the evaluation of intracranial arteriovenous malformations (AVMs). Materials and Methods: Twelve AVM patients were evaluated retrospectively. Time-of-flight (TOF) MRA, non-vessel-selective 4D-MRA (NS-4D-MRA) and vessel-selective 4D-MRA (VS-4D-MRA) were performed using a 3-tesla MR unit in all patients, and used to identify feeding arteries and draining veins and measure nidus size. The diagnostic accuracy of the three techniques was compared using digital subtraction angiography (DSA). If a multi-feeder was observed, the percentage of blood flow of each feeding artery to the entire nidus was evaluated, and compared to the DSA findings using the 'error value', defined as the degree of overestimation of the blood flow. All imaging findings were assessed by two neuroradiologists. Results: In both raters, the detectability of feeding arteries by VS-4D-MRA (12 and 11 patients) was significantly higher than those of TOF-MRA (7 and 6 patients) and NS-4D-MRA (8 and 7 patients) (p<0.016, respectively). The detectability of drainer veins by TOF-MRA (10 and 10 patients) was significantly higher than that of VS-4D-MRA (7 and 6 patients). In the percentage of the blood flow of each feed artery to the entire nidus, the DSA findings (error value; 27.1 ± 5.7) indicated overestimations of the blood flow compared to the VS-4D-MRA (error value; 7.1 ± 3.9) (p<0.001). Conclusions: VS-4D-MRA was shown to be a useful technique for the evaluation of intracranial AVMs, especially for detecting feed arteries and estimating details of the nidus structure
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