Optimal CT Contrast Enhancement Protocol for the Fontan Pathway: An Analysis Based on a 15-year Single-center Experience

Mapping Intimacies ◽

10.21203/rs.3.rs-621039/v1 ◽

2021 ◽

Author(s):

Hyun Woo Goo

Keyword(s):

Standard Deviation ◽

Contrast Agent ◽

Contrast Enhancement ◽

Quantitative Evaluation ◽

Characteristic Curve ◽

Low Contrast ◽

Group 3 ◽

Heterogeneous Enhancement ◽

Standard Deviations ◽

Noise Ratio

Abstract This retrospective study was performed to systemically compare several candidates for optimal contrast enhancement protocols of cardiothoracic CT dedicated for evaluating the Fontan pathway. Of 115 CT examinations from 89 patients, simultaneous injection of contrast agent via the arm and leg veins with 50% diluted contrast agent (group 1, n = 38), 60-second scan delay after leg vein injection (group 2, n = 41) or 3-minute scan delay (group 3, n = 36) was used to obtain optimal contrast enhancement. The degree and heterogeneity of cardiovascular enhancement, image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were quantitatively evaluated. Histogram-assisted semi-quantitative evaluation was performed for heterogeneous enhancement, and a cut-off value indicating heterogeneous enhancement was determined by comparing the standard deviations between the cases showing homogeneous and heterogeneous enhancement. Contrast enhancement of the Fontan pathway, the standard deviation measured in the Fontan pathway, SNR, and CNR were more frequently lower in group 3 compared to groups 1 and 2 (p < 0.001). Homogeneous enhancement of the Fontan pathway based on the histogram-assisted semi-quantitative evaluation was more frequently seen in group 3 compared to groups 1 and 2 (p < 0.043‒0.001). Receiver operating characteristic curve analysis demonstrated that the standard deviation was an excellent diagnostic test in determining the homogeneity of contrast enhancement (area under the curve = 0.991; 95% confidence interval, 0.988‒0.994; p < 0.001). Standard deviations > 105.1 HU could be considered to indicate heterogeneous enhancement with 73.2% sensitivity and 100.0% specificity. The protocol using a 3-minute scan delay best achieved homogeneous contrast enhancement in the Fontan pathway on cardiothoracic CT among the tested protocols. However, low contrast enhancement, SNR, and, CNR need to be improved.

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Application of low injection rate and low contrast agent dose in three-dimensional rotational digital subtraction angiography of the intracranial aneurysm

Interventional Neuroradiology ◽

10.1177/1591019916631980 ◽

2016 ◽

Vol 22 (3) ◽

pp. 287-292 ◽

Cited By ~ 2

Author(s):

Zhimei Gao ◽

Yongming Zeng ◽

Jingkun Sun ◽

Jingjie Yang ◽

Yang Zhou ◽

...

Keyword(s):

Intracranial Aneurysm ◽

Contrast Agent ◽

Digital Subtraction Angiography ◽

Three Dimensional ◽

Noise Signal ◽

Injection Rate ◽

Digital Subtraction ◽

Low Contrast ◽

Noise Ratio ◽

Rotational Digital Subtraction Angiography

Objective The objective of this article is to explore the feasibility of low injection rate and low contrast agent dose in three-dimensional rotational digital subtraction angiography (3D DSA) of the intracranial aneurysm. Materials and methods Fifty-one patients with suspected intracranial aneurysms were included. The catheter tip was kept within the internal carotid artery at the epistropheus level. Patients were divided into three groups randomly according to injection rate: group A (1.5 ml/s, n = 18), group B (2.0 ml/s, n = 18), and group C (3.0 ml/s, n = 15). The noise, signal-to-noise ratio (SNR), and carrier-to-noise ratio (CNR) of C2, C6, M1, and A1 segments were calculated. The continuous subtraction images and reconstructed images were evaluated by two technicians. Results No significant differences were found in noise between groups A and B, and groups A and C. Significant differences were found in the SNR and CNR of M1 and A1 segments between groups A and B, and groups B and C, but for C2 and C6 segments, they were not significant. Significant differences were found in the SNR and CNR of all segments between groups A and C. Significant differences were found in the contrast agent dose between all three groups. No significant differences were found in scores evaluated by two physicians between the three groups. Conclusion The personalized injection protocol of low injection rate and low contrast agent dose in 3D DSA of the intracranial aneurysm is feasible. The application of this protocol can reduce the dose of iodine and obtain satisfactory images.

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On the sensibility of the Pairs Trading strategy: the case of the FTS stock market index

Studies of Applied Economics ◽

10.25115/eea.v38i3.3145 ◽

2020 ◽

Vol 38 (3) ◽

Author(s):

Ainhoa Fernández-Pérez ◽

María de las Nieves López-García ◽

José Pedro Ramos Requena

Keyword(s):

Standard Deviation ◽

Stock Market ◽

Trading Strategy ◽

Stock Market Index ◽

Pairs Trading ◽

Empirical Application ◽

Statistical Arbitrage ◽

Market Index ◽

Standard Deviations ◽

Using Data

In this paper we present a non-conventional statistical arbitrage technique based in varying the number of standard deviations used to carry the trading strategy. We will show how values of 1 and 1,2 in the standard deviation provide better results that the classic strategy of Gatev et al (2006). An empirical application is performance using data of the FST100 index during the period 2010 to June 2019.

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Image Quality Enhancing by Efficient Histogram Equalization

Wasit Journal of Engineering Sciences ◽

10.31185/ejuow.vol2.iss2.29 ◽

2014 ◽

Vol 2 (2) ◽

pp. 47-58

Author(s):

Ismail Sh. Baqer

Keyword(s):

Image Quality ◽

Contrast Enhancement ◽

Mean Squared Error ◽

Signal To Noise Ratio ◽

Histogram Equalization ◽

Gray Level ◽

Signal To Noise ◽

Squared Error ◽

Noise Ratio

A two Level Image Quality enhancement is proposed in this paper. In the first level, Dualistic Sub-Image Histogram Equalization DSIHE method decomposes the original image into two sub-images based on median of original images. The second level deals with spikes shaped noise that may appear in the image after processing. We presents three methods of image enhancement GHE, LHE and proposed DSIHE that improve the visual quality of images. A comparative calculations is being carried out on above mentioned techniques to examine objective and subjective image quality parameters e.g. Peak Signal-to-Noise Ratio PSNR values, entropy H and mean squared error MSE to measure the quality of gray scale enhanced images. For handling gray-level images, convenient Histogram Equalization methods e.g. GHE and LHE tend to change the mean brightness of an image to middle level of the gray-level range limiting their appropriateness for contrast enhancement in consumer electronics such as TV monitors. The DSIHE methods seem to overcome this disadvantage as they tend to preserve both, the brightness and contrast enhancement. Experimental results show that the proposed technique gives better results in terms of Discrete Entropy, Signal to Noise ratio and Mean Squared Error values than the Global and Local histogram-based equalization methods

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Risk stratification of cardiac metastases using late gadolinium enhancement cardiovascular magnetic resonance: prognostic impact of hypo-enhancement evidenced tumor avascularity

Journal of Cardiovascular Magnetic Resonance ◽

10.1186/s12968-021-00727-2 ◽

2021 ◽

Vol 23 (1) ◽

Author(s):

Angel T. Chan ◽

William Dinsfriend ◽

Jiwon Kim ◽

Brian Yum ◽

Razia Sultana ◽

...

Keyword(s):

Cardiovascular Magnetic Resonance ◽

Late Gadolinium Enhancement ◽

Magnetic Resonance ◽

Contrast Enhancement ◽

Cancer Etiology ◽

Enhancement Pattern ◽

Gadolinium Enhancement ◽

Lesion Location ◽

Heterogeneous Enhancement ◽

Lge Cmr

Abstract Background Late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) is widely used to identify cardiac neoplasms, for which diagnosis is predicated on enhancement stemming from lesion vascularity: Impact of contrast-enhancement pattern on clinical outcomes is unknown. The objective of this study was to determine whether cardiac metastasis (CMET) enhancement pattern on LGE-CMR impacts prognosis, with focus on heterogeneous lesion enhancement as a marker of tumor avascularity. Methods Advanced (stage IV) systemic cancer patients with and without CMET matched (1:1) by cancer etiology underwent a standardized CMR protocol. CMET was identified via established LGE-CMR criteria based on lesion enhancement; enhancement pattern was further classified as heterogeneous (enhancing and non-enhancing components) or diffuse and assessed via quantitative (contrast-to-noise ratio (CNR); signal-to-noise ratio (SNR)) analyses. Embolic events and mortality were tested in relation to lesion location and contrast-enhancement pattern. Results 224 patients were studied, including 112 patients with CMET and unaffected (CMET -) controls matched for systemic cancer etiology/stage. CMET enhancement pattern varied (53% heterogeneous, 47% diffuse). Quantitative analyses were consistent with lesion classification; CNR was higher and SNR lower in heterogeneously enhancing CMET (p < 0.001)—paralleled by larger size based on linear dimensions (p < 0.05). Contrast-enhancement pattern did not vary based on lesion location (p = NS). Embolic events were similar between patients with diffuse and heterogeneous lesions (p = NS) but varied by location: Patients with right-sided lesions had threefold more pulmonary emboli (20% vs. 6%, p = 0.02); those with left-sided lesions had lower rates equivalent to controls (4% vs. 5%, p = 1.00). Mortality was higher among patients with CMET (hazard ratio [HR] = 1.64 [CI 1.17–2.29], p = 0.004) compared to controls, but varied by contrast-enhancement pattern: Diffusely enhancing CMET had equivalent mortality to controls (p = 0.21) whereas prognosis was worse with heterogeneous CMET (p = 0.005) and more strongly predicted by heterogeneous enhancement (HR = 1.97 [CI 1.23–3.15], p = 0.005) than lesion size (HR = 1.11 per 10 cm [CI 0.53–2.33], p = 0.79). Conclusions Contrast-enhancement pattern and location of CMET on CMR impacts prognosis. Embolic events vary by CMET location, with likelihood of PE greatest with right-sided lesions. Heterogeneous enhancement—a marker of tumor avascularity on LGE-CMR—is a novel marker of increased mortality risk.

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Dynamic Quantitative Iodine Myocardial Perfusion Imaging with Dual-Layer CT using a Porcine Model

Scientific Reports ◽

10.1038/s41598-019-52458-1 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 2

Author(s):

Kai Scherer ◽

Johannes Hammel ◽

Thorsten Sellerer ◽

Korbinian Mechlem ◽

Bernhard Renger ◽

...

Keyword(s):

Contrast Agent ◽

Perfusion Imaging ◽

Porcine Model ◽

Ct Perfusion ◽

Dual Energy Ct ◽

Beam Hardening ◽

Low Contrast ◽

Time To Peak ◽

Coronary Ct

Abstract Ischemic heart disease is the globally leading cause of death. When using coronary CT angiography, the functional hemodynamics within the myocardium remain uncertain. In this study myocardial CT perfusion imaging using iodine contrast agent demonstrated to strongly improve the assessment of myocardial disorders. However, a retrieval of such dynamics using Hounsfield units from conventional CT poses concerns with respect to beam-hardening effects and low contrast-to-noise ratio (CNR). Dual-energy CT offers novel approaches to overcome aforementioned limitations. Quantitative peak enhancement, perfusion, time to peak and iodine volume measurements inside the myocardium were determined resulting in 0.92 mg/ml, 0.085 mg/ml/s 17.12 s and 29.89 mg/ml*s, respectively. We report on the first extensive quantitative and iodine-based analysis of myocardial dynamics in a healthy porcine model using a dual-layer spectral CT. We further elucidate on the potential of reducing the radiation dose from 135 to 18 mGy and the contrast agent volume from 60 to 30 mL by presenting a two-shot acquisition approach and measuring iodine concentrations in the myocardium in-vivo down to 1 mg/ml, respectively. We believe that dynamic quantitative iodine perfusion imaging may be a highly sensitive tool for the precise functional assessment and monitoring of early myocardial ischemia.

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The Effects of Ethyl Alcohol on a Driver's Driving Skill, Visual Perception, Risk Acceptance, Choice Reaction Times and Information Processing Rates

Proceedings of the Human Factors Society Annual Meeting ◽

10.1177/154193127401800202 ◽

1974 ◽

Vol 18 (2) ◽

pp. 116-116

Author(s):

Helmut T. Zwahlen

Keyword(s):

Information Processing ◽

Standard Deviation ◽

Visual Perception ◽

Reaction Times ◽

Driving Skill ◽

Alcohol Condition ◽

The Mean ◽

Risk Acceptance ◽

Standard Deviations ◽

Choice Reaction Times

Twelve subjects (20–37 years old) were tested in the laboratory and eleven out of these were also tested in a car in the field, first under a no alcohol condition and then under an alcohol condition (approximately 0.10% BAC). In the laboratory the subjects simple and choice reaction times for two uncertainty modes were measured and their information processing rates (3 bits unsertainty) were determined. In the field the subjects driving skill for driving through a gap with 20 inches total clearance at 20 MPH was measured, as well as their static visual perceptual capabilities and risk acceptance decisions for a 46 feet viewing distance using psychophysical experimental methods. Based upon the driving skill measure (standard deviation of centerline deviations in the gap), the mean of the psychometric visual gap perception function and the mean of the psychometric gap risk acceptance function, the “Safety Distance” and the “Driver Safety Index” (DSI) were obtained. Based upon a statistical analysis of the data we may conclude first that the effects of alcohol (approximately 0.10% BAC) vary widely from one subject to another (slighthly improved performance to highly impaired performance) and that the changes in the group averages of the means and standard deviations of the psychometric visual perception and risk acceptance functions, the driving skill distributions, the “Safety Distances” and the DSI's for the subjects (although all changes in the group averages are in the expected direction) are statistically not significant (α = .05). Second, the group average of the means of the choice reaction times for the subjects increased by 5% under the alcohol condition (statistically significant, α = .05), but more important the group average of the standard deviations of the choice reaction times for the subjects increased by 23% (statistically significant, α = .05). The group average of the information processing rates for the subjects decreased by 3% (statistically not significant, α = .05) under the alcohol condition. A system model in which the system demands on the driver are represented in terms of choice reaction times is used to demonstrate that the increase in performance variability (expressed by the standard deviation of choice reaction times) under the influence of alcohol provides a much better explanation for the higher accident involvement than the historically most frequently used rather small increase in average performance (expressed by the mean of choice reaction times).

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Operation of a PDA convergence gauge Characteristic curve The operating characteristic curve of a PDA convergence gauge is a curve demarcated with a value of reference displacement as the horizontal abscissa and a value of test displacement as the vertical ordinate. It should be linear and its equation could be obtained with the least square method. According to the testing in an indoor baseline field (see the next section), Figure 5 gives the instrument’s characteristic curve and its constants. The standard deviation fitted between the test displacement and the reference displacement is 0.05 mm (see also Fig. 8). Instrument constants Addition constant [mm] -0.007

Structural Health Monitoring and Integrity Management ◽

10.1201/b18510-124 ◽

2015 ◽

pp. 391-393

Keyword(s):

Standard Deviation ◽

Operating Characteristic ◽

Characteristic Curve ◽

Least Square Method ◽

Least Square ◽

A Value ◽

Operating Characteristic Curve

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Synthesis of Plans to Increase the Results of Ordinary National Education Test by All-Round Tutoring Process for Primary School Grade 6

International Education Studies ◽

10.5539/ies.v14n2p63 ◽

2021 ◽

Vol 14 (2) ◽

pp. 63

Author(s):

Nuttakan Pakprod ◽

Kanokrat Jirasatjanukul ◽

Damrong Tumthong ◽

Prapa Amklad ◽

Wipa Lekchom

Keyword(s):

Standard Deviation ◽

Primary School ◽

Target Group ◽

Educational Testing ◽

School Grade ◽

National Education ◽

Standard Deviations ◽

The Difference ◽

High Level ◽

Basic Level

The objective of this research is to study the results of activities to increase the scores of Ordinary National Education Test. Cluster; teachers of Phetchaburi Rajabhat University comparing the results of Ordinary National Education Test in 2017-2018 and studying the satisfaction of the activities. The target group is 49 schools in Phetchaburi and Prachuap Khiri Khan Provinces, data were analyzed using mean and standard deviation. The study found that the difference of the scores of the Ordinary National Education Test was higher in 32 schools and there is a difference in scores of Ordinary National Education Test tests lower by 2 schools, representing 94.12, with the satisfaction of the participation in the activity of increasing the basic educational testing at the basic level is at a high level with an average of 4.22, standard deviations 0.73, which the participants are satisfied with the process. The process of organizing activities was at the highest with an average of 4.28, standard deviations 0.76 and continues organizing activities to increase the scores of Ordinary National Education Test.

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