Abnormal Gas Diffusing Capacity and Portosystemic Shunt in Patients With Chronic Liver Disease

Science.gov (United States)

Park, Moon-Seung; Lee, Min-Ho; Park, Yoo-Sin; Kim, Shin-Hee; Kwak, Min-Jung; Kang, Ju-Seop

2012-01-01

Background Pulmonary dysfunctions including the hepatopulmonary syndrome and portosystemic shunt are important complications of hepatic cirrhosis. To investigate the severity and nature of abnormal gas diffusing capacity and its correlation to portosystemic shunt in patients with chronic liver disease. Methods Forty-four patients with chronic liver disease (15 chronic active hepatitis (CAH), 16 Child-Pugh class A, and 13 Child-Pugh class B) without other diseases history were enrolled in the study. Evaluation of liver function tests, arterial blood gases analysis, ultrasonography, pulmonary function test including lung diffusing capacity of carbon monoxide (DLco), forced vital capacity(FVC), forced expiratory volume 1 seconds(FEV1), total lung capacity(TLC), DLco/AV(alveolar volume) and thallium-201 per rectum scintigraphy were performed. We were analyzed correlations between pulmonary function abnormalities and heart/liver (H/L) ratio in patients with chronic liver diseases. Results In CAH, percentage of patients with DLco and DLco/VA (Child-Pugh class A and B patients. The means of DLco and DLco/VA were significantly (P Child-Pugh class. The mean H/L ratio in Child-Pugh class B increased markedly (P Child-Pugh class A. The frequency of specific pulmonary function abnormality in patients with Child-Pugh class B was significantly (P Child-Pugh class A and CAH. There was a inverse linear correlation between H/L ratio and DLco (r = -0.339, P < 0.05) and DLco/VA (r = -0.480, P < 0.01). Conclusion A total of 62% of patients with advanced liver disease have abnormal pulmonary diffusion capacity with a reduced DLco or DLco/VA and abnormal portosystemic shunt (increased H/L ratio) is common hemodynamic abnormality. Therefore, inverse linear correlation between DLco or DLco/VA and H/L ratio may be an important factor in predicting pulmonary complication and meaningful diagnostic and prognostic parameters in patients with advanced chronic liver disease. PMID:27785203

Relevance of normative values for functional capacity evaluation

NARCIS (Netherlands)

Soer, R.; Van Der Schans, C.; Geertzen, J.; Groothoff, J.; Brouwer, Sandra; Dijkstra, P.; Reneman, M.

2009-01-01

Background: Functional Capacity Evaluations (FCEs) are evaluations designed to measure capacity to perform activities and are used to make recommendations for participation in work. Normative values of healthy working subjects' performances are unavailable, thus patients' performances cannot be

Effective diffusion coefficients and porosity values for argillaceous rocks and bentonite: measured and estimated values for the provisional safety analyses for SGT-E2

International Nuclear Information System (INIS)

Van Loon, L.R.

2014-11-01

rock is of a house-of-cards type. With increasing density, the randomly oriented clay platelets become more oriented in a specific direction perpendicular to the direction of compaction. As soon as the platelets are more or less horizontally oriented, further decrease of the porosity has no longer an effect on the orientation and consequently on the tortuosity. The rock bulk dry density threshold value is about 2500 kg m"-"3, representing a porosity value of 0.1. Important input parameters are the diffusion coefficient of the radionuclides in free bulk water and the transport relevant porosity. Radionuclides were subdivided into two main groups with a free water diffusion coefficient of (20.0 ± 2.5) x l0"-"1"0 m"2 s"-"1 and (7.5 ± 2.5) x 10"-"1"0 m"2 s"-"1. The porosities were derived mainly from drilling core samples of the host rocks by measurements of the bulk and grain density of the rocks. The values for anion accessible porosities were based on the observation that for most clay rocks about 50 % of the total porosity is accessible to anions. In case of cations undergoing ion exchange, a correction factor CF was calculated using the surface mobility of the cation and the sorption values. The reference values of the effective diffusion coefficients, and their upper and lower bounding values, were multiplied with these correction factors. For most clay rocks investigated, the correction factors used ranged from 1 to at most 30, depending on the sorption value of the cation. The largest values were calculated for Cs"+. In case of Helvetic Marls, the correction factors were between 30 and 400. This is caused by the much larger capacity ratio values, which are directly proportional to the reciprocal transport porosity of the clay rocks. As the depth of the host rocks varies notably in the siting regions, a temperature range was defined for each potential host rock. Effects of temperature on diffusion were evaluated using the Arrhenius equation with an average

Technical and economic aspects of new gaseous diffusion uranium enrichment capacity

International Nuclear Information System (INIS)

Langley, R.A. Jr.; O'Donnell, A.J.

1977-01-01

Work is well advanced on design and construction of the next major increment of U.S. uranium enrichment capacity. The plant will use the gaseous diffusion process to provide the required capacity and reliability at a competitive enrichment services cost. Gaseous diffusion technology is the base against which other processes are compared in order to assess their commercial viability. While it has generally been described as a mature technology with limited future development potential, work on design of the new U.S. plant has resulted in major improvement in plant design with corresponding decreases in plant capacity and operating costs. The paper describes major technological advances incorporated into the new plant design and their impact on enrichment costs. These include the effects of: - advanced barrier technology; - tandem compressor drive systems; - optimization of number of equipment sizes; - single level plant design; - development of rapid power level change capability; - electrical system simplification; - plant arrangement and layout. Resulting capital costs and projected enrichment costs are summarized. Enrichment costs are placed in the context of total nuclear fuel cycle costs. Trade-offs between uranium feed material quantities and enrichment plant tails assays are described, and optimization of this aspect of the nuclear fuel cycle is discussed. The effect on enrichment plant characteristics is described. Flexibility and capability of the new U.S. enrichment plant to meet these changing optimization conditions are described

Value of apparent diffusion coefficient (ADC) in evaluating response ...

African Journals Online (AJOL)

Objective. To determine whether the apparent diffusion coefficient (ADC) value obtained by diffusion-weighted magnetic resonance imaging (DW-MRI) can be used as a reliable detector of response of carcinoma of the cervix treated with chemoradiotherapy, compared with conventional. T2-weighted MRI. Design.

Quantitative cerebral blood flow calculation method using xenon CT. Introduction of a factor reflecting diffusing capacity of the lung for xenon

International Nuclear Information System (INIS)

Sase, Shigeru; Honda, Mitsuru; Noguchi, Yoshitaka

2007-01-01

In calculating cerebral blood flow (CBF) using the Fick principle, time-course information on arterial tracer concentration is indispensable and exerts considerable influence on the accuracy of CBF. In xenon-enhanced CT (Xe-CT), the time-course change rate for end-tidal xenon concentration (Ke), which can be measured, and that for arterial xenon concentration (Ka) have been assumed to be equal. However, it has been pointed out that there are large differences between Ke and Ka in many cases. We have introduced a single factor (γ) which correlates Ke with Ka in the equation Ka=γ x (1-e -Ke/γ ). This factor, γ, reflects the diffusing capacity of the lung for xenon; larger γ values correspond to larger diffusing capacities and Ka is equal to Ke when γ is infinity. Kety's equation contains two parameters: CBF and xenon solubility coefficient We added a third parameter, γ, to Kety's equation, and developed an efficient method to obtain the γ value for each Xe-CT study. Applying this method to ten normal subjects (35.4±16.3 years, mean±standard deviation (SD)), we obtained γ value of 1.01±0.17 and the average CBF value of 38.8±7.5 mL/100 g/min in basal ganglia. The wash-in period could be shortened to two minutes using this method. Xe-CT with this factor (γ) as a parameter enhances its clinical availability as well as the accuracy of CBF. (author)

Intra-session and inter-session variability of nitric oxide pulmonary diffusing capacity in adults with cystic fibrosis.

Science.gov (United States)

Radtke, Thomas; Benden, Christian; Maggi-Beba, Marion; Kriemler, Susi; van der Lee, Ivo; Dressel, Holger

2017-12-01

We evaluated the intra-session and inter-session variability of the diffusing capacity of nitric oxide (DLNO), carbon monoxide (DLCO), alveolar-capillary membrane diffusing capacity for carbon monoxide (DMCO) and pulmonary capillary blood volume (Vc) in patients with cystic fibrosis (CF). Patients performed single-breath diffusing capacity measurements during all of 3 consecutive study visits. Precision of gas diffusing parameters was quantified by within-subject standard deviation (SD ws ) and coefficient of variation (CV). Intra-session and inter-session reproducibility was determined by SD ws *2.77. 15 clinically stable patients were included. The intra-session precision of gas diffusing parameters improved over the study visits. The inter-session SD ws for DLNO, DLCO, DMCO, and Vc was 4.8, 1.3, 2.4, and 4.3, respectively. Reproducibility was 13.3, 3.8, 6.7 and 12.0mLmin -1 mmHg -1 ; CV was 4.4, 4.7, 4.4 and 5.8%, respectively. The intra-session variability of DLNO, DLCO, DMCO and Vc improves with breath-hold maneuver training in test-naïve patients with CF, indicating a learning effect. Inter-session reproducibility data are lower than those previously reported in healthy subjects. Copyright © 2017 Elsevier B.V. All rights reserved.

Role of magnetic resonance diffusion imaging and apparent diffusion coefficient values in the evaluation of spinal tuberculosis in Indian patients

International Nuclear Information System (INIS)

Palle, Lalitha; Reddy, MCH Balaji; Reddy, K Jagannath

2010-01-01

To define a range of apparent diffusion coefficient values in spinal tuberculosis and to evaluate the sensitivity of diffusion-weighted magnetic resonance imaging (DW-MRI) and apparent diffusion coefficient values in patients of spinal tuberculosis. This study was conducted over a period of 20 months and included 110 patients with a total of 230 vertebral bodies. The study was performed in two parts. The first part included all patients of known tuberculosis and patients with classical features of tuberculosis. The second part included patients with spinal pathology of indeterminate etiology. All the patients underwent a routine MRI examination along with diffusion sequences. The apparent diffusion coefficient (ADC) values were calculated from all the involved vertebral bodies. The mean ADC value of affected vertebrae in first part of the study was found to be 1.4 ± 0.20 × 10 −3 mm 2 /s. This ADC value was then applied to patients in the second part of study in order to determine its ability in predicting tuberculosis. This range of ADC values was significantly different from the mean ADC values of normal vertebrae and those with metastatic involvement. However, there was an overlap of ADC values in a few tuberculous vertebrae with the ADC values in metastatic vertebrae. We found that DW-MRI and ADC values may help in the differentiation of spinal tuberculosis from other lesions of similar appearance. However, an overlap of ADC values was noted with those of metastatic vertebrae. Therefore diffusion imaging and ADC values must always be interpreted in association with clinical history and routine MRI findings and not in isolation

Comparison of apparent diffusion coefficients (ADCs) between two-point and multi-point analyses using high-B-value diffusion MR imaging

International Nuclear Information System (INIS)

Kubo, Hitoshi; Maeda, Masayuki; Araki, Akinobu

2001-01-01

We evaluated the accuracy of calculating apparent diffusion coefficients (ADCs) using high-B-value diffusion images. Echo planar diffusion-weighted MR images were obtained at 1.5 tesla in five standard locations in six subjects using gradient strengths corresponding to B values from 0 to 3000 s/mm 2 . Estimation of ADCs was made using two methods: a nonlinear regression model using measurements from a full set of B values (multi-point method) and linear estimation using B values of 0 and max only (two-point method). A high correlation between the two methods was noted (r=0.99), and the mean percentage differences were -0.53% and 0.53% in phantom and human brain, respectively. These results suggest there is little error in estimating ADCs calculated by the two-point technique using high-B-value diffusion MR images. (author)

Determination of Kd-values from diffusion experiments

International Nuclear Information System (INIS)

Meier, H.; Hecker, W.; Zimmerhackl, E.; Zeitler, G.; Menge, P.

1986-01-01

Results of diffusion measurements are reported, obtained with aqueous solutions of U-233, Ra-226, Ni-63, and Se-75 in contact with solid rock samples of the Konrad mine overlying rock. The subsequent derivation of K d -values and the method applied are explained. (orig.) [de

The Capacity Value of Wind in the United States: Methods and Implementation

Energy Technology Data Exchange (ETDEWEB)

Milligan, Michael; Porter, Kevin

2006-03-01

As more wind energy capacity is added in the nation, the question of wind's capacity value is raised. This article shows how the capacity value of wind is determined, both in theory and in practice. (author)

Finite element approximation for time-dependent diffusion with measure-valued source

Czech Academy of Sciences Publication Activity Database

Seidman, T.; Gobbert, M.; Trott, D.; Kružík, Martin

2012-01-01

Roč. 122, č. 4 (2012), s. 709-723 ISSN 0029-599X R&D Projects: GA AV ČR IAA100750802 Institutional support: RVO:67985556 Keywords : measure-valued source * diffusion equation Subject RIV: BA - General Mathematics Impact factor: 1.329, year: 2012 http://library.utia.cas.cz/separaty/2012/MTR/kruzik-finite element approximation for time - dependent diffusion with measure-valued source.pdf

Normative Values for a Functional Capacity Evaluation

NARCIS (Netherlands)

Soer, Remko; van der Schans, Cees P.; Geertzen, Jan H.; Groothoff, Johan W.; Brouwer, Sandra; Dijkstra, Pieter U.; Reneman, Michiel F.

2009-01-01

Objective: To establish normative values for a functional capacity evaluation (FCE) of healthy working subjects. Design: Descriptive. Setting: Rehabilitation center. Participants: Healthy working subjects (N=701; 448 men, 253 women) between 20 and 60 years of age, working in more than 180

What is the real value of diffusion length in GaN?

International Nuclear Information System (INIS)

Yakimov, E.B.

2015-01-01

Highlights: • The applicability of SEM methods for diffusion length measurements in GaN is discussed. • The discussion is based on our own experiments and on the available literature data. • A study of EBIC dependence on beam energy suits well for a small diffusion length. • The most reliable diffusion length values in the state-of-the-art n-GaN are evaluated. - Abstract: The applicability of scanning electron microscopy methods for excess carrier diffusion length measurements in GaN is discussed. The discussion is based on author’s experiments and on the available literature data. It is shown that for semiconductors with submicron diffusion length special attention should be paid to the choice of measuring method and experimental conditions. Some reasons for diffusion length overestimation and underestimation are analyzed. It is shown that a measurement of collected current dependence on electron beam energy is the most suitable method for submicron diffusion length evaluations because it is much easier to meet conditions for a proper application of this method than for other widely used methods. The analysis of data previously reported in literature and author’s results have shown that the diffusion length values in the range from 70 to 400 nm are the most reliable for state-of-the-art n-GaN epilayers

8760-Based Method for Representing Variable Generation Capacity Value in Capacity Expansion Models: Preprint

Energy Technology Data Exchange (ETDEWEB)

Frew, Bethany A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Cole, Wesley J [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Sun, Yinong [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Mai, Trieu T [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Richards, James [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2017-08-01

Capacity expansion models (CEMs) are widely used to evaluate the least-cost portfolio of electricity generators, transmission, and storage needed to reliably serve demand over the evolution of many years or decades. Various CEM formulations are used to evaluate systems ranging in scale from states or utility service territories to national or multi-national systems. CEMs can be computationally complex, and to achieve acceptable solve times, key parameters are often estimated using simplified methods. In this paper, we focus on two of these key parameters associated with the integration of variable generation (VG) resources: capacity value and curtailment. We first discuss common modeling simplifications used in CEMs to estimate capacity value and curtailment, many of which are based on a representative subset of hours that can miss important tail events or which require assumptions about the load and resource distributions that may not match actual distributions. We then present an alternate approach that captures key elements of chronological operation over all hours of the year without the computationally intensive economic dispatch optimization typically employed within more detailed operational models. The updated methodology characterizes the (1) contribution of VG to system capacity during high load and net load hours, (2) the curtailment level of VG, and (3) the potential reductions in curtailments enabled through deployment of storage and more flexible operation of select thermal generators. We apply this alternate methodology to an existing CEM, the Regional Energy Deployment System (ReEDS). Results demonstrate that this alternate approach provides more accurate estimates of capacity value and curtailments by explicitly capturing system interactions across all hours of the year. This approach could be applied more broadly to CEMs at many different scales where hourly resource and load data is available, greatly improving the representation of challenges

Library Support for Covenant University's Core Value of Capacity ...

African Journals Online (AJOL)

... and creation of spiritual and leadership development section among others as some of the roles of the library in supporting the Covenant University core value of capacity building. The paper concluded by noting that it is necessary for individuals and organizations to accord capacity building a pride of place in the scheme ...

The effect of aging and cardiorespiratory fitness on the lung diffusing capacity response to exercise in healthy humans.

Science.gov (United States)

Coffman, Kirsten E; Carlson, Alex R; Miller, Andrew D; Johnson, Bruce D; Taylor, Bryan J

2017-06-01

high-intensity exercise. Interestingly, however, we found that highly fit older individuals demonstrate greater values of lung diffusing capacity during high-intensity exercise than their less fit age-matched counterparts. Copyright © 2017 the American Physiological Society.

Shannon Meets Fick on the Microfluidic Channel: Diffusion Limit to Sum Broadcast Capacity for Molecular Communication.

Science.gov (United States)

Bicen, A Ozan; Lehtomaki, Janne J; Akyildiz, Ian F

2018-03-01

Molecular communication (MC) over a microfluidic channel with flow is investigated based on Shannon's channel capacity theorem and Fick's laws of diffusion. Specifically, the sum capacity for MC between a single transmitter and multiple receivers (broadcast MC) is studied. The transmitter communicates by using different types of signaling molecules with each receiver over the microfluidic channel. The transmitted molecules propagate through microfluidic channel until reaching the corresponding receiver. Although the use of different types of molecules provides orthogonal signaling, the sum broadcast capacity may not scale with the number of the receivers due to physics of the propagation (interplay between convection and diffusion based on distance). In this paper, the performance of broadcast MC on a microfluidic chip is characterized by studying the physical geometry of the microfluidic channel and leveraging the information theory. The convergence of the sum capacity for microfluidic broadcast channel is analytically investigated based on the physical system parameters with respect to the increasing number of molecular receivers. The analysis presented here can be useful to predict the achievable information rate in microfluidic interconnects for the biochemical computation and microfluidic multi-sample assays.

Evaluating the capacity value of wind power considering transmission and operational constraints

International Nuclear Information System (INIS)

Gil, Esteban; Aravena, Ignacio

2014-01-01

Highlights: • Discussion of power system adequacy and the capacity value of wind power. • Method for estimating capacity value of wind power is proposed. • Monte Carlo simulation used to consider transmission and operational constraints. • Application of the method to the Chilean Northern Interconnected System (SING). - Abstract: This paper presents a method for estimating the capacity value of wind considering transmission and operational constraints. The method starts by calculating a metric for system adequacy by repeatedly simulating market operations in a Monte Carlo scheme that accounts for forced generator outages, wind resource variability, and operational conditions. Then, a capacity value calculation that uses the simulation results is proposed, and its application to the Chilean Northern Interconnected System (SING) is discussed. A comparison of the capacity value for two different types of wind farms is performed using the proposed method, and the results are compared with the method currently used in Chile and the method recommended by the IEEE. The method proposed in the paper captures the contribution of the variable generation resources to power system adequacy more accurately than the method currently employed in the SING, and showed capable of taking into account transmission and operational constraints

Optimization of b-value distribution for biexponential diffusion-weighted MR imaging of normal prostate.

Science.gov (United States)

Jambor, Ivan; Merisaari, Harri; Aronen, Hannu J; Järvinen, Jukka; Saunavaara, Jani; Kauko, Tommi; Borra, Ronald; Pesola, Marko

2014-05-01

To determine the optimal b-value distribution for biexponential diffusion-weighted imaging (DWI) of normal prostate using both a computer modeling approach and in vivo measurements. Optimal b-value distributions for the fit of three parameters (fast diffusion Df, slow diffusion Ds, and fraction of fast diffusion f) were determined using Monte-Carlo simulations. The optimal b-value distribution was calculated using four individual optimization methods. Eight healthy volunteers underwent four repeated 3 Tesla prostate DWI scans using both 16 equally distributed b-values and an optimized b-value distribution obtained from the simulations. The b-value distributions were compared in terms of measurement reliability and repeatability using Shrout-Fleiss analysis. Using low noise levels, the optimal b-value distribution formed three separate clusters at low (0-400 s/mm2), mid-range (650-1200 s/mm2), and high b-values (1700-2000 s/mm2). Higher noise levels resulted into less pronounced clustering of b-values. The clustered optimized b-value distribution demonstrated better measurement reliability and repeatability in Shrout-Fleiss analysis compared with 16 equally distributed b-values. The optimal b-value distribution was found to be a clustered distribution with b-values concentrated in the low, mid, and high ranges and was shown to improve the estimation quality of biexponential DWI parameters of in vivo experiments. Copyright © 2013 Wiley Periodicals, Inc.

Pulmonary dysfunction in advanced liver disease: frequent occurrence of an abnormal diffusing capacity

International Nuclear Information System (INIS)

Hourani, J.M.; Bellamy, P.E.; Tashkin, D.P.; Batra, P.; Simmons, M.S.

1991-01-01

Abnormalities in pulmonary function have been reported in association with chronic liver disease of varied etiology. The aim of this study was to better define the frequency and nature of these abnormalities in patients who were being evaluated for liver transplantation. We performed a battery of pulmonary function tests and chest radiographs in 116 consecutive patients (50 men, 66 women; aged 19 to 70 years, mean 44.6 years) with severe advanced liver disease who were hospitalized specifically for evaluation for possible orthotopic liver transplantation and were able to perform technically satisfactory tests. In 17 patients, quantitative whole-body technetium-99m macroaggregated albumin perfusion scanning was also performed for assessment of possible right-to-left shunting through intrapulmonary vascular dilatations. The most commonly affected test of lung function was the single-breath diffusing capacity for carbon monoxide (DLCO), which was abnormal in 48%, 45%, and 71% of patients who never smoked, former smokers, and current smokers, respectively. Ventilatory restriction was noted in 25% of all patients, airflow obstruction (reduced ratio of forced expiratory volume in 1 second to forced vital expiratory volume in 1 second to forced vital capacity) in only 3%, and a widened alveolar-arterial oxygen gradient in 45%. Diffusion impairment was accompanied by a restrictive defect in only 35% of the patients and by an abnormally widened alveolar-arterial oxygen gradient in 60%. When diffusion impairment was accompanied by an oxygenation defect, it was also associated with a significantly increased right-to-left shunt fraction (mean 24.9%) assessed from quantitative whole-body perfusion imaging

Capacity factor of wind power realized values vs. estimates

International Nuclear Information System (INIS)

Boccard, Nicolas

2009-01-01

For two decades now, the capacity factor of wind power measuring the average energy delivered has been assumed in the 30-35% range of the name plate capacity. Yet, the mean realized value for Europe over the last five years is below 21%; accordingly private cost is two-third higher and the reduction of carbon emissions is 40% less than previously expected. We document this discrepancy and offer rationalizations that emphasize the long term variations of wind speeds, the behavior of the wind power industry, political interference and the mode of finance. We conclude with the consequences of the capacity factor miscalculation and some policy recommendations.

The single-breath diffusing capacity of CO and NO in healthy children of European descent

DEFF Research Database (Denmark)

Thomas, Astrid; Hanel, Birgitte; Marott, Jacob L

2014-01-01

a Jaeger Masterscreen PFT. The data were analyzed using the Generalized Additive Models for Location Scale and Shape (GAMLSS) statistical method. MEASUREMENTS AND MAIN RESULTS: A total of 326 children were eligible for diffusing capacity measurements, resulting in 312 measurements of DL,CO,NO and 297 of DL...

Abnormal Gas Diffusing Capacity and Portosystemic Shunt in Patients With Chronic Liver Disease

OpenAIRE

Park, Moon-Seung; Lee, Min-Ho; Park, Yoo-Sin; Kim, Shin-Hee; Kwak, Min-Jung; Kang, Ju-Seop

2012-01-01

Background Pulmonary dysfunctions including the hepatopulmonary syndrome and portosystemic shunt are important complications of hepatic cirrhosis. To investigate the severity and nature of abnormal gas diffusing capacity and its correlation to portosystemic shunt in patients with chronic liver disease. Methods Forty-four patients with chronic liver disease (15 chronic active hepatitis (CAH), 16 Child-Pugh class A, and 13 Child-Pugh class B) without other diseases history were enrolled in the ...

Two-dimensional boundary-value problem for ion-ion diffusion

International Nuclear Information System (INIS)

Tuszewski, M.; Lichtenberg, A.J.

1977-01-01

Like-particle diffusion is usually negligible compared with unlike-particle diffusion because it is two orders higher in spatial derivatives. When the ratio of the ion gyroradius to the plasma transverse dimension is of the order of the fourth root of the mass ratio, previous one-dimensional analysis indicated that like-particle diffusion is significant. A two-dimensional boundary-value problem for ion-ion diffusion is investigated. Numerical solutions are found with models for which the nonlinear partial differential equation reduces to an ordinary fourth-order differential equation. These solutions indicate that the ion-ion losses are higher by a factor of six for a slab geometry, and by a factor of four for circular geometry, than estimated from dimensional analysis. The solutions are applied to a multiple mirror experiment stabilized with a quadrupole magnetic field which generates highly elliptical flux surfaces. It is found that the ion-ion losses dominate the electron-ion losses and that these classical radial losses contribute to a significant decrease of plasma lifetime, in qualitiative agreement with the experimental results

Beyond Economy: Impact of National Cultural Values on Nationwide Broadband Internet Diffusion

Science.gov (United States)

Joo, Sung-Hee

2010-01-01

This study examines how the non-conventional factors of national cultural values and government involvement affect the diffusion of broadband Internet technologies in various nations around the world. An innovative element of the study was the examination of the influence patterns at different stages of diffusion, which was measured by the number…

Role of apparent diffusion coefficient values and diffusion weighted magnetic resonance imaging in differentiation between benign and malignant thyroid nodules

International Nuclear Information System (INIS)

Incedayi, M.; Sivrioglu, A.; Mutlu, H.; Sonmez, G.; Velioglu, M.; Sildiroglu, O.; Basekim, C.; Kizilkaya, E.

2012-01-01

Full text: Objective: The purpose of the study was to differentiate between benign and malignant thyroid nodules using nodule-spinal cord signal intensity and nodule apparent diffusion coefficient (ADC) ratios on diffusion weighted magnetic resonance imaging. Materials and methods: Forty-four patients (27 females, 17 males; mean age 49) with nodules who underwent diffusion weighted magnetic resonance imaging (DW-MRI) were included in this study. The images were acquired with 0, 50, 400 and 1000 s/mm 2 b values. ADC maps were calculated afterwards. Fine needle aspiration biopsies (FNAB) were performed at the same day with DW-MRI acquisition. The diagnosis in patients where malignity was detected after FNAB was confirmed by histopathologic analysis of the operation material. The signal intensities of the spinal cord and the nodule were measured additionally, over b-1000 diffusion weighted images. Nodule /cord signal intensity (SI) ratios were obtained and the digital values were calculated by dividing to ADC values estimated for each nodule. Statistical analysis was performed. Results: The (nodule SI-cord SI)/nodule ADC ratio is calculated in the DW images and a statistically significant relationship was found between this ratio and the histopathology of the nodules (p<0.001). The ratio was determined as 0.27 in benign, and 0.86 in malignant lesions. The result of ROC analysis was statistically significant, and the area under Receiver Operating Characteristic (ROC) curve (100%) was considerably high. The threshold value was calculated as 0.56 according to the ROC analysis. According to this threshold value, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy rates for (nodule SI/cord SI)/ADC ratios in differentiating benign from malignant thyroid nodules are calculated as 100%, 97%, 83%, 100%, and 98%, respectively. Conclusion: We have found that (nodule/cord SI)/ nodule ADC ratio has the highest values for

Postural variation of pulmonary diffusing capacity as a marker of lung microangiopathy in Indian patients with type 2 diabetes mellitus

Directory of Open Access Journals (Sweden)

Avinash Kumar

2016-01-01

Full Text Available Introduction: Diabetes mellitus (DM is characterized by the presence of chronic hyperglycemia and formation of advanced glycation end products (AGEs. Interaction between AGE and its receptor leads to endothelial damage and microangiopathy. This study was undertaken to investigate the possibility of using a postural variation of diffusing capacity as an early marker of lung microangiopathy and its correlation with the level of adhesion molecules, HbA1c, duration of diabetes, and insulin resistance in type 2 DM (T2DM patients with and without microangiopathy. Materials and Methods: Forty patients having T2DM without any microangiopathy (n = 20 as well as with microangiopathy (n = 20, and 22 age and sex matched healthy controls were enrolled in this cross-sectional study. Measurement of lung volumes and capacities were done. DLco was measured in sitting and supine position. Levels of vascular cell adhesion molecule-1 (VCAM-1, E-selectin, fasting glucose, and insulin were estimated in plasma of the patients and compared with controls. Results: Restrictive type of ventilatory change was observed in DM patients. Diffusing capacity (% predicted in the supine position (P < 0.0001, postural change in DLco (P < 0.0001, and coefficient of diffusion were significantly less in DM patients as compared to controls. Plasma levels of VCAM-1 were significantly higher in DM patients without microangiopathy and negatively correlated (r = −0.4054, P = 0.0094 with Δ DLco in all diabetic subjects. All patients had significantly higher insulin resistance. Conclusion: Lack of postural increase in diffusing capacity in type 2 diabetic patients along with increased VCAM-1 levels could reflect the presence of an early microangiopathy of the small pulmonary vessels.

Noninvasive measurement of carboxyhemoglobin levels for adjustment of diffusion capacity measured during pulmonary function testing.

Science.gov (United States)

Mahoney, Anne M; Stimpson, Claudia L; Scott, Karen L; Hampson, Neil B

2007-12-01

The diffusing capacity of the lungs for carbon monoxide (D(LCO)) is commonly measured during pulmonary function testing (PFT). Although adjustment of the measured D(LCO) for an elevated baseline carboxyhemoglobin level is recommended, carboxyhemoglobin is not routinely measured, which may reduce the accuracy of D(LCO) measurements. We sought to assess the utility of routine carboxyhemoglobin measurement and subsequent D(LCO) correction in patients referred for PFT. We retrospectively reviewed 100 consecutive PFT results, including D(LCO) assessment. We used a pulse CO-oximeter (recently approved by the Food and Drug Administration) to noninvasively measure baseline carboxyhemoglobin (S(pCO)). We used simple descriptive statistics to compare the S(pCO) values. In subjects with elevated S(pCO) (> 2%) we adjusted the percent-of-predicted D(LCO). Interpretation of D(LCO) was categorized according to the American Thoracic Society classification scheme for respiratory impairment. The self-reported smokers had higher average S(pCO) than did self-reported nonsmokers (1.6% vs 3.5%, p carboxyhemoglobin is easy to perform during PFT. When precise measurement of D(LCO) is important, noninvasive measurement of carboxyhemoglobin may be of value. If routine S(pCO) measurement is considered, the highest yield is among current smokers.

Impact of post-processing methods on apparent diffusion coefficient values

Energy Technology Data Exchange (ETDEWEB)

Zeilinger, Martin Georg; Lell, Michael; Uder, Michael [University of Erlangen-Nuremberg, Institute of Diagnostic Radiology, Erlangen (Germany); Baltzer, Pascal Andreas Thomas [Medical University Vienna, Department of Radiology and Nuclear Medicine, Vienna (Austria); Doerfler, Arnd; Dietzel, Matthias [University of Erlangen-Nuremberg, Department of Neuroradiology, Erlangen (Germany)

2017-03-15

The apparent diffusion coefficient (ADC) is increasingly used as a quantitative biomarker in oncological imaging. ADC calculation is based on raw diffusion-weighted imaging (DWI) data, and multiple post-processing methods (PPMs) have been proposed for this purpose. We investigated whether PPM has an impact on final ADC values. Sixty-five lesions scanned with a standardized whole-body DWI-protocol at 3 T served as input data (EPI-DWI, b-values: 50, 400 and 800 s/mm{sup 2}). Using exactly the same ROI coordinates, four different PPM (ADC{sub 1}-ADC{sub 4}) were executed to calculate corresponding ADC values, given as [10{sup -3} mm{sup 2}/s] of each lesion. Statistical analysis was performed to intra-individually compare ADC values stratified by PPM (Wilcoxon signed-rank tests: α = 1 %; descriptive statistics; relative difference/∇; coefficient of variation/CV). Stratified by PPM, mean ADCs ranged from 1.136-1.206 *10{sup -3} mm{sup 2}/s (∇ = 7.0 %). Variances between PPM were pronounced in the upper range of ADC values (maximum: 2.540-2.763 10{sup -3} mm{sup 2}/s, ∇ = 8 %). Pairwise comparisons identified significant differences between all PPM (P ≤ 0.003; mean CV = 7.2 %) and reached 0.137 *10{sup -3} mm{sup 2}/s within the 25th-75th percentile. Altering the PPM had a significant impact on the ADC value. This should be considered if ADC values from different post-processing methods are compared in patient studies. (orig.)

Effects of body position on the carbon monoxide diffusing capacity in patients with chronic heart failure: relation to hemodynamic changes.

Science.gov (United States)

Faggiano, P; D'Aloia, A; Simoni, P; Gualeni, A; Foglio, K; Ambrosino, N; Giordano, A

1998-01-01

Pulmonary diffusion has been found to be reduced in patients with congestive heart failure. The effects of postural changes on the diffusing capacity had been evaluated in healthy subjects, but not in patients with heart failure. The aim of this study was to evaluate the posture-induced changes in diffusing capacity in patients with chronic heart failure and their relation to the hemodynamic profile. The pulmonary carbon monoxide diffusing capacity (DLCO) was measured in the supine position, with 20 degrees passive head elevation, and in the sitting position, both postures maintained for 10 min, in a group of 32 male patients with mild to moderate chronic heart failure due to left ventricular systolic dysfunction (ejection fraction differ in the two positions (20.3 +/- 5.7 vs. 19.4 +/- 5.6 ml/min/mm Hg, 77 +/- 23 vs. 75 +/- 20% of predicted, respectively). The patients were then subdivided according to changes in DLCO from the supine to the sitting position: DLCO increased (+23%) in 9 patients (28%, group 1), decreased (-17.5%) in 17 patients (53%, group 2), and remained within the coefficient of reproducibility ( +/- 5 %) in 6 patients (group 3). As compared with group 2, group 1 patients showed a significant increase in mean pulmonary artery pressure (+7 vs. -15%, p pressure (+8 vs. -22%, p position, while the cardiac index showed a smaller - but not significant - decrease in group 1 (-5 vs. -12%). The percent changes in DLCO significantly correlated with changes in pulmonary capillary wedge (r = 0.54, p pressures. In chronic heart failure postural changes may induce different responses in diffusing capacity. To a greater extent than in healthy subjects, the most common response is a decrease in DLCO in the sitting as compared with the supine position. The DLCO changes correlate with variations in pulmonary circulation pressure, probably due to changes in pulmonary vascular recruitment and pulmonary capillary blood volume.

CO diffusing capacity in a general population sample: relationships with cigarette smoking and airflow obstruction.

Science.gov (United States)

Viegi, G; Paoletti, P; Carrozzi, L; Baldacci, S; Modena, P; Pedreschi, M; Di Pede, F; Mammini, U; Giuntini, C

1993-01-01

The single-breath carbon monoxide diffusing capacity (DLCOsb) was measured together with ventilatory lung function tests as part of a survey of a general population sample living in Northern Italy (n = 2,481). Based on answers to an interviewer-administered questionnaire, subjects free of respiratory symptoms or diseases were identified. Data from subjects who had never regularly smoked cigarettes were used to derive reference equations for the test indexes, and data from the remaining subjects who had smoked were used to derive regression equations incorporating a term expressing cigarette consumption (cube root of pack-years) and a term indicating current smoking decrement, in order to obtain expected DLCOsb percent predicted. Neither number of cigarettes smoked daily or duration of smoking, in smokers, nor duration of smoking or years since quitting smoking, in ex-smokers, entered significantly the multiple-regression model. The mean values of DLCOsb were only slightly affected by the increasing degree of airway obstruction. When subjects with confirmed asthma were analyzed, after stratifying for different levels of FEV1/FVC ratio, increased mean value of DLCOsb (over 100%) was found in those with an FEV1/FVC ratio between 75 and 65%. This cross-sectional analysis suggests that there is a decrease in DLCOsb with cumulative cigarette consumption even in healthy subjects. Further, it confirms the clinical observations of high DLCOsb values in asthmatic patients, at least in those with an initial degree of chronic airflow obstruction.

Regional apparent diffusion coefficient values in 3rd trimester fetal brain

International Nuclear Information System (INIS)

Hoffmann, Chen; Weisz, Boaz; Lipitz, Shlomo; Katorza, Eldad; Yaniv, Gal; Bergman, Dafi; Biegon, Anat

2014-01-01

Apparent diffusion coefficient (ADC) values in the developing fetus can be used in the diagnosis and prognosis of prenatal brain pathologies. To this end, we measured regional ADC in a relatively large cohort of normal fetal brains in utero. Diffusion-weighted imaging (DWI) was performed in 48 non-sedated 3rd trimester fetuses with normal structural MR imaging results. ADC was measured in white matter (frontal, parietal, temporal, and occipital lobes), basal ganglia, thalamus, pons, and cerebellum. Regional ADC values were compared by one-way ANOVA with gestational age as covariate. Regression analysis was used to examine gestational age-related changes in regional ADC. Four other cases of CMV infection were also examined. Median gestational age was 32 weeks (range, 26-33 weeks). There was a highly significant effect of region on ADC, whereby ADC values were highest in white matter, with significantly lower values in basal ganglia and cerebellum and the lowest values in thalamus and pons. ADC did not significantly change with gestational age in any of the regions tested. In the four cases with fetal CMV infection, ADC value was associated with a global decrease. ADC values in normal fetal brain are relatively stable during the third trimester, show consistent regional variation, and can make an important contribution to the early diagnosis and possibly prognosis of fetal brain pathologies. (orig.)

Regional apparent diffusion coefficient values in 3rd trimester fetal brain

Energy Technology Data Exchange (ETDEWEB)

Hoffmann, Chen [Tel Aviv University, Department of Radiology, Sheba Medical Center, Tel Hashomer (affiliated to the Sackler School of Medicine), Tel Aviv (Israel); Sheba Medical Center, Diagnostic Imaging, 52621, Tel Hashomer (Israel); Weisz, Boaz; Lipitz, Shlomo; Katorza, Eldad [Tel Aviv University, Department of Obstetrics and Gynecology, Sheba Medical Center, Tel Hashomer (affiliated to the Sackler School of Medicine), Tel Aviv (Israel); Yaniv, Gal; Bergman, Dafi [Tel Aviv University, Department of Radiology, Sheba Medical Center, Tel Hashomer (affiliated to the Sackler School of Medicine), Tel Aviv (Israel); Biegon, Anat [Stony Brook University School of Medicine, Department of Neurology, Stony Brook, NY (United States)

2014-07-15

Apparent diffusion coefficient (ADC) values in the developing fetus can be used in the diagnosis and prognosis of prenatal brain pathologies. To this end, we measured regional ADC in a relatively large cohort of normal fetal brains in utero. Diffusion-weighted imaging (DWI) was performed in 48 non-sedated 3rd trimester fetuses with normal structural MR imaging results. ADC was measured in white matter (frontal, parietal, temporal, and occipital lobes), basal ganglia, thalamus, pons, and cerebellum. Regional ADC values were compared by one-way ANOVA with gestational age as covariate. Regression analysis was used to examine gestational age-related changes in regional ADC. Four other cases of CMV infection were also examined. Median gestational age was 32 weeks (range, 26-33 weeks). There was a highly significant effect of region on ADC, whereby ADC values were highest in white matter, with significantly lower values in basal ganglia and cerebellum and the lowest values in thalamus and pons. ADC did not significantly change with gestational age in any of the regions tested. In the four cases with fetal CMV infection, ADC value was associated with a global decrease. ADC values in normal fetal brain are relatively stable during the third trimester, show consistent regional variation, and can make an important contribution to the early diagnosis and possibly prognosis of fetal brain pathologies. (orig.)

Apparent diffusion coefficient values of the normal uterus: Interindividual variations during menstrual cycle

International Nuclear Information System (INIS)

Tsili, A.C.; Argyropoulou, M.I.; Tzarouchi, L.; Dalkalitsis, N.; Koliopoulos, G.; Paraskevaidis, E.; Tsampoulas, K.

2012-01-01

Objectives: To assess the apparent diffusion coefficient (ADC) changes of the normal uterine zones among reproductive women during the menstrual cycle. Methods: The study included 101 women of reproductive age, each with regular cycle and normal endometrium/myometrium, as proved on histopathology or MR imaging examination. Diffusion-weighted (DW) imaging was performed along the axial plane, using a single shot, multi-slice spin-echo planar diffusion pulse sequence and b-values of 0 and 800 s/mm 2 . The mean and standard deviation of the ADC values of normal endometrium/myometrium were calculated for menstrual, proliferative and secretory phase. Analysis of variance followed by the least significant difference test was used for statistical analysis. Results: The ADC values of the endometrium were different in the three phases of the menstrual cycle (menstrual phase: 1.25 ± 0.27; proliferative phase: 1.39 ± 0.20; secretory phase: 1.50 ± 0.18) (F: 9.64, p: 0.00). Statistical significant difference was observed among all groups (p 0.05). Conclusions: A wide variation of ADC values of normal endometrium and myometrium is observed during different phases of the menstrual cycle.

The role of perfusion lung scanning and diffusion capacity for early diagnosis of micro circulatory disturbances in chronic obstructive pulmonary disease

International Nuclear Information System (INIS)

Petrova, D.; Shoshlov, P.; Hadjikostova, H.

2002-01-01

The development of chronic obstructive pulmonary disease (COPD) and the frequent inflammatory exacerbations with development of respiratory failure lead to changes in the micro circulatory and an increased risk of lung thrombotic and thromboembolic complication. The aim of the study was to establish the possibility of the perfusion lung scanning and diffusion capacity for early diagnosis of pulmonary micro circulatory disturbances in COPD with mild and moderate respiratory failure. 59 COPD patients were investigated. The data presented significant segmental disorders. Only in 5 (8.47%) of them the perfusion lung scintigrams were normal. In 23 of the patients, single-breath diffusing capacity (DICO) and its two components: membranous component (Dm) and capillary blood component (Vc) were determined. DICO was lower especially Vc the mean sign of micro circulatory disorders. A relationship between the degree of hypoxaemia and the changes found in the perfusion scintigraphy was found. Changes in the pulmonary lung scanning and in the diffusion capacity in COPD with mild respiratory failure seem to be an early diagnostic test. The early anticoagulant and desaggregant prevention may decrease the risk of thrombotic complications in the development of the disease. (authors)

Utility of Diffusion-Weighted MRI to Detect Changes in Liver Diffusion in Benign and Malignant Distal Bile Duct Obstruction: The Influence of Choice of b-Values.

Science.gov (United States)

Karan, Belgin; Erbay, Gurcan; Koc, Zafer; Pourbagher, Aysin; Yildirim, Sedat; Agildere, Ahmet Muhtesem

2016-11-01

The study sought to evaluate the potential of diffusion-weighted magnetic resonance imaging to detect changes in liver diffusion in benign and malignant distal bile duct obstruction and to investigate the effect of the choice of b-values on apparent diffusion coefficient (ADC). Diffusion-weighted imaging was acquired with b-values of 200, 600, 800, and 1000 s/mm 2 . ADC values were obtained in 4 segments of the liver. The mean ADC values of 16 patients with malignant distal bile duct obstruction, 14 patients with benign distal bile duct obstruction, and a control group of 16 healthy patients were compared. Mean ADC values for 4 liver segments were lower in the malignant obstruction group than in the benign obstruction and control groups using b = 200 s/mm 2 (P liver segments in each group were not significantly different (P > .05). There were no correlations between the ADC values of liver segments and liver function tests. Measurement of ADC shows good potential for detecting changes in liver diffusion in patients with distal bile duct obstruction. Calculated ADC values were affected by the choice of b-values. Copyright © 2016 Canadian Association of Radiologists. Published by Elsevier Inc. All rights reserved.

Value for railway capacity

DEFF Research Database (Denmark)

Sameni, Melody Khadem; Preston, John M.

2012-01-01

to analyze the efficiency of operators in transforming inputs of allocated capacity of infrastructure and franchise payments into valuable passenger service outputs while avoiding delays. By addressing operational and economic aspects of capacity utilization simultaneously, the paper deviates from existing...... DEA work on the economic efficiency of railways by considering a new combination of input-output that also incorporates quality of service. The constant and variable returns to scale models are applied to the case study of franchised passenger operators in Great Britain. The follow-up Tobit regression...

Analysis of Multiple B-Value Diffusion-Weighted Imaging in Pediatric Acute Encephalopathy

Science.gov (United States)

Tachibana, Yasuhiko; Aida, Noriko; Niwa, Tetsu; Nozawa, Kumiko; Kusagiri, Kouki; Mori, Kana; Endo, Kazuo; Obata, Takayuki; Inoue, Tomio

2013-01-01

Acute encephalopathy is a disease group more commonly seen in children. It is often severe and has neurological sequelae. Imaging is important for early diagnosis and prompt treatment to ameliorate an unfavorable outcome, but insufficient sensitivity/specificity is a problem. To overcome this, a new value (fraction of high b-pair (FH)) that could be processed from clinically acceptable MR diffusion-weighted imaging (DWI) with three different b-values was designed on the basis of a two-compartment model of water diffusion signal attenuation. The purpose of this study is to compare FH with the apparent diffusion coefficient (ADC) regarding the detectability of pediatric acute encephalopathy. We retrospectively compared the clinical DWI of 15 children (1–10 years old, mean 2.34, 8 boys, 7 girls) of acute encephalopathy with another 16 children (1–11 years old, mean 4.89, 9 boys, 7 girls) as control. A comparison was first made visually by mapping FH on the brain images, and then a second comparison was made on the basis of 10 regions of interest (ROIs) set on cortical and subcortical areas of each child. FH map visually revealed diffusely elevated FH in cortical and subcortical areas of the patients with acute encephalopathy; the changes seemed more diffuse in FH compared to DWI. The comparison based on ROI revealed elevated mean FH in the cortical and subcortical areas of the acute encephalopathy patients compared to control with significant difference (Pencephalopathy may be superior in FH compared to ADC. PMID:23755112

Measurements of thermal diffusivity, specific heat capacity and thermal conductivity with LFA 447 apparatus

DEFF Research Database (Denmark)

Zajas, Jan Jakub; Heiselberg, Per

The LFA 447 can be successfully used for measurements of thermal diffusivity, specific heat and thermal conductivity of various samples. It is especially useful when determining the properties of materials on a very small scale. The matrix measurement mode allows for determining the local...... that the heat losses from both samples during the measurement are similar. Finally, the leveling of the samples is very important. Very small discrepancies can cause a massive error in the derivation of specific heat capacity and, as a result, thermal conductivity....

The diagnostic value of diffusion-weighted imaging and the apparent diffusion coefficient values in the differentiation of benign and malignant breast lesions.

Science.gov (United States)

Çabuk, Gonca; Nass Duce, Meltem; Özgür, Anıl; Apaydın, Feramuz Demir; Polat, Ayşe; Orekici, Gülhan

2015-04-01

The goal of our study was to evaluate the diagnostic efficacy of diffusion-weighted imaging (DWI) in the differentiation of benign and malignant breast lesions. Between June 2012 and March 2013, 60 patients with 63 lesions (age range 29-70 years, mean age 48.6 years) were included in our study. All lesions, except complicated cysts and intra-mammary lymph nodes, were confirmed histopathologically. The patients were evaluated with a 1.5 Tesla MR scanner using dedicated bilateral breast coil. DWI images were obtained by echo planar imaging sequence and 'b' values were selected as 200, 600 and 1000 s/mm(2). Apparent diffusion coefficient (ADC) values of both breast lesions and the normal fibroglandular tissue of the contralateral breast were calculated and statistically compared using Shapiro-Wilk test, Student's t-test, Mann-Whitney U test, chi-square test and the receiver operating curve. Of 63 lesions, 22 were malignant and 41 were benign. In malignant lesions, the mean ADC values were 1.40 ± 0.41 × 10(-3) mm(2)/s for b = 200, 1.05 ± 0.28 × 10(-3) mm(2)/s for b = 600 and 0.91 ± 0.20 × 10(-3) mm(2)/s for b = 1000 and in benign lesions, the mean ADC values were 2.13 ± 0.85 × 10(-3) mm(2)/s for b = 200, 1.64 ± 0.47 × 10(-3) mm(2)/s for b = 600 and 1.40 ± 0.43 × 10(-3) mm(2)/s for b = 1000. The success of ADC values in differentiation of benign and malignant lesions was statistically significant (P = 0.0001). The threshold values were determined to be 1.50 × 10(-3) mm(2)/s for b = 200, 1.22 × 10(-3) mm(2)/s for b = 600 and 0.98 × 10(-3) mm(2)/s for b = 1000 (P benign and malignant breast lesions. © 2015 The Royal Australian and New Zealand College of Radiologists.

Value of apparent diffusion coefficients in patients with brain tumors

International Nuclear Information System (INIS)

De Luca, Silvina; Stoisa, Daniela; Mondello, Eduardo; Vietti, Julio; Casas, Gabriel; Florenzano, Nestor; Eyheremendy, Eduardo; Martinez Boero, Macarena

2004-01-01

Purpose: To determine the utility of ADC values for the diagnosis of encephalic tumors. Material and method: Forty patients with encephalic tumors histopathologically confirmed, have been studied by conventional MR, diffusion and ADC maps. The intensities were measured in the solid tumor portion and the normal white matter, ratios were obtained and correlated in 13 patients with their respective cellularity indexes. Results: Seventeen were glial tumors, with lower ADC values in cases of greater malignancy. In 12 patients the diagnosis was secondary lesions in which the lowest ADC values were obtained. This feature was shared by the epidermoid cyst. The hamartomas, neurinomas, oligodendrogliomas and ependymomas have shown intermediate ADC values. Conclusion: The ADC map is a complement of conventional MR which provides additional information for the diagnosis of encephalic tumors. Low ADC values correlated with high grade malignant tumors. (author)

Effect of EDTA and gypsum on self diffusion coefficient of zinc in alkali soil

International Nuclear Information System (INIS)

Gupta, G.N.; Deb, D.L.

1981-01-01

The effect of EDTA and gypsum application on the rate of zinc diffusion was studied in an alkali soil. Gypsum application at the rate of half gypsum requirement (GR) increased the apparent self diffusion coefficient of zinc (DaZn) and decreased the capacity factor (B) of soil. The higher rates (full GR and double GR) depressed the rate of zinc diffusion and increased the B value. Application of EDTA at the rate of 0.77 μeg -1 of soil produced 1600 and 24 fold increase in DaZn and DpZn values respectively and 100 times drop in B value. Addition of 55 ppm Zn to the soil significantly increased the DaZn and DpZn values. (author)

Differences in spirometry and diffusing capacity after a 3-h wet or dry oxygen dive with a PO(2) of 150 kPa

NARCIS (Netherlands)

van Ooij, P. J. A. M.; van Hulst, R. A.; Houtkooper, A.; Sterk, P. J.

2011-01-01

Breathing oxygen with a partial pressure of >50 kPa causes pulmonary oxygen toxicity (POT), resulting in a decrease in vital capacity (VC) and in diffusing capacity for carbon monoxide (DLco). As submersion is thought to potentiate POT, we hypothesized that submerged oxygen divers are at increased

Diffusion

International Nuclear Information System (INIS)

Kubaschewski, O.

1983-01-01

The diffusion rate values of titanium, its compounds and alloys are summarized and tabulated. The individual chemical diffusion coefficients and self-diffusion coefficients of certain isotopes are given. Experimental methods are listed which were used for the determination of diffusion coefficients. Some values have been taken over from other studies. Also given are graphs showing the temperature dependences of diffusion and changes in the diffusion coefficient with concentration changes

Quantitative analysis of diffusion-weighted magnetic resonance imaging in malignant breast lesions using different b value combinations

Energy Technology Data Exchange (ETDEWEB)

Nilsen, Line B. [Oslo University Hospital, Department of Radiation Biology, Norwegian Radium Hospital, P.O. Box 4959, Oslo (Norway); University of Oslo, Faculty of Medicine, P.O. Box 1078, Oslo (Norway); Fangberget, Anne [Oslo University Hospital, Department of Radiology and Nuclear Medicine, Division of Diagnostics and Intervention, Norwegian Radium Hospital, P.O. Box 4959, Oslo (Norway); Geier, Oliver [Oslo University Hospital, Department of Diagnostic Physics, The Interventional Centre, Division of Diagnostics and Intervention, P.O. Box 4950, Oslo (Norway); Seierstad, Therese [Oslo University Hospital, Department of Radiology and Nuclear Medicine, Division of Diagnostics and Intervention, Norwegian Radium Hospital, P.O. Box 4959, Oslo (Norway); Buskerud University College, Department of Health Sciences, P.O. Box 7053, Drammen (Norway)

2013-04-15

To explore how apparent diffusion coefficients (ADCs) in malignant breast lesions are affected by selection of b values in the monoexponential model and to compare ADCs with diffusion coefficients (Ds) obtained from the biexponential model. Twenty-four women (mean age 51.3 years) with locally advanced breast cancer were included in this study. Pre-treatment diffusion-weighted magnetic resonance imaging was performed using a 1.5-T system with b values of 0, 50, 100, 250 and 800 s/mm{sup 2}. Thirteen different b value combinations were used to derive individual monoexponential ADC maps. All b values were used in the biexponential model. Median ADC (including all b values) and D were 1.04 x 10{sup -3} mm{sup 2}/s (range 0.82-1.61 x 10{sup -3} mm{sup 2}/s) and 0.84 x 10{sup -3} mm{sup 2}/s (range 0.17-1.56 x 10{sup -3} mm{sup 2}/s), respectively. There was a strong positive correlation between ADCs and Ds. For clinically relevant b value combinations, maximum deviation between ADCs including and excluding low b values (<100 s/mm{sup 2}) was 11.8 %. Selection of b values strongly affects ADCs of malignant breast lesions. However, by excluding low b values, ADCs approach biexponential Ds, demonstrating that microperfusion influences the diffusion signal. Thus, care should be taken when ADC calculation includes low b values. (orig.)

Postural variation of pulmonary diffusing capacity as a marker of lung microangiopathy in Indian patients with type 2 diabetes mellitus.

Science.gov (United States)

Kumar, Avinash; Bade, Geetanjali; Trivedi, Anjali; Jyotsna, Viveka P; Talwar, Anjana

2016-01-01

Diabetes mellitus (DM) is characterized by the presence of chronic hyperglycemia and formation of advanced glycation end products (AGEs). Interaction between AGE and its receptor leads to endothelial damage and microangiopathy. This study was undertaken to investigate the possibility of using a postural variation of diffusing capacity as an early marker of lung microangiopathy and its correlation with the level of adhesion molecules, HbA1c, duration of diabetes, and insulin resistance in type 2 DM (T2DM) patients with and without microangiopathy. Forty patients having T2DM without any microangiopathy (n = 20) as well as with microangiopathy (n = 20), and 22 age and sex matched healthy controls were enrolled in this cross-sectional study. Measurement of lung volumes and capacities were done. DLco was measured in sitting and supine position. Levels of vascular cell adhesion molecule-1 (VCAM-1), E-selectin, fasting glucose, and insulin were estimated in plasma of the patients and compared with controls. Restrictive type of ventilatory change was observed in DM patients. Diffusing capacity (% predicted) in the supine position (P capacity in type 2 diabetic patients along with increased VCAM-1 levels could reflect the presence of an early microangiopathy of the small pulmonary vessels.

Value of diffusion-Weighted imaging in evaluating the cellularity density of prostate cancer

International Nuclear Information System (INIS)

Liu Jingang; Wang Xizhen; Wang Bin; Niu Qingliang; Liu Qiang

2008-01-01

Objective: To study the cellularity density of prostate cancer (PCa) with diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC). Methods: 38 patients with histologically proven prostate cancer (PCa) underwent DWI with a 1.5 T MR scanner using a pelvic phased array multi-coil. The ADC values of PCa, benign prostatic hyperplasia (BPH), and peripheral zone (PZ) were calculated. The cellularity density of PCa was recorded according to hematoxylin and eosin (HE) staining. The relationship between ADC value and cellularity density of PCa was analyzed with Pearson correlation coefficient. Results: The ADC values of PCa, BPH, and PZ were (49.32±12.68)×10 -5 mm 2 /s, (86.73±26.75)×10 -5 mm 2 /s and (126.25±27.21)×10 -5 mm 2 /s, respectively. The ADC value of PCa was significantly lower than that of BPH and PZ (P<005). The cellularity density of PCa was 12.9%. The ADC value reversely related to the cellularity density of prostate cancer (r=-0.646, P<005). Conclusion: The ADC value can reflect the cellularity density of PCa. (authors)

Apparent diffusion coefficient values of the normal uterus: Interindividual variations during menstrual cycle

Energy Technology Data Exchange (ETDEWEB)

Tsili, A.C., E-mail: a_tsili@yahoo.gr [Department of Clinical Radiology, University Hospital of Ioannina (Greece); Argyropoulou, M.I., E-mail: margyrop@cc.uoi.gr [Department of Clinical Radiology, University Hospital of Ioannina (Greece); Tzarouchi, L., E-mail: ltzar@cc.uoi.gr [Department of Clinical Radiology, University Hospital of Ioannina (Greece); Dalkalitsis, N., E-mail: ndalkal@cc.uoi.gr [Department of Obstetrics and Gynaecology, University Hospital of Ioannina (Greece); Koliopoulos, G., E-mail: georgekoliopoulos@yahoo.com [Department of Obstetrics and Gynaecology, University Hospital of Ioannina (Greece); Paraskevaidis, E., E-mail: eparaske@cc.uoi.gr [Department of Obstetrics and Gynaecology, University Hospital of Ioannina (Greece); Tsampoulas, K., E-mail: ctsampou@uoi.gr [Department of Clinical Radiology, University Hospital of Ioannina (Greece)

2012-08-15

Objectives: To assess the apparent diffusion coefficient (ADC) changes of the normal uterine zones among reproductive women during the menstrual cycle. Methods: The study included 101 women of reproductive age, each with regular cycle and normal endometrium/myometrium, as proved on histopathology or MR imaging examination. Diffusion-weighted (DW) imaging was performed along the axial plane, using a single shot, multi-slice spin-echo planar diffusion pulse sequence and b-values of 0 and 800 s/mm{sup 2}. The mean and standard deviation of the ADC values of normal endometrium/myometrium were calculated for menstrual, proliferative and secretory phase. Analysis of variance followed by the least significant difference test was used for statistical analysis. Results: The ADC values of the endometrium were different in the three phases of the menstrual cycle (menstrual phase: 1.25 {+-} 0.27; proliferative phase: 1.39 {+-} 0.20; secretory phase: 1.50 {+-} 0.18) (F: 9.64, p: 0.00). Statistical significant difference was observed among all groups (p < 0.05). The ADC values of the normal myometrium were different in the three phases of the menstrual cycle (menstrual phase: 1.91 {+-} 0.35; proliferative phase: 1.72 {+-} 0.27; secretory phase: 1.87 {+-} 0.28) (F: 3.60, p: 0.03). Statistical significant difference was observed between menstrual and proliferative phase and between proliferative and secretory phase (p < 0.05). No significant difference was noted between menstrual and secretory phase (p > 0.05). Conclusions: A wide variation of ADC values of normal endometrium and myometrium is observed during different phases of the menstrual cycle.

The diagnostic value of diffusion-weighted magnetic resonance imaging in soft tissue abscesses

Energy Technology Data Exchange (ETDEWEB)

Unal, Ozkan; Koparan, Halil Ibrahim [Yuezuencue Yil University, Department of Radiology, Van (Turkey); Avcu, Serhat, E-mail: serhatavcu@hotmail.com [Yuezuencue Yil University, Department of Radiology, Van (Turkey); Kalender, Ali Murat [Yuezuencue Yil University, Department of Orthopaedics, General Surgery, Van (Turkey); Kisli, Erol [Yuezuencue Yil University, Department of General Surgery, Van (Turkey)

2011-03-15

Purpose: To study the diagnostic value of diffusion-weighted imaging (DWI) in soft tissue abscesses. Materials and methods: Fifty patients were included in this study who were thought to have soft tissue abscess or cystic lesion as a result of clinical and radiological examinations. Localisations of the lesions were: 1 periorbital, 3 breast, 14 intraabdominal, and 32 intramuscular lesions. After other radiological examinations, DWI was performed. The signal intensity values of the lesions were evaluated qualitatively according to the hyperintensity on b-1000 DWI, using 1.5 T MR system. All of the lesions were aspirated after DWI, and detection of pus in the aspiration material was accepted as gold standard for the diagnosis of abscess. Results: In 38 of the 50 patients, hyperintensity was obtained on diffusion-weighted images. False-positive results were maintained in 2 of these patients, and true-positive results were maintained in 36 of them. In 11 of the 50 patients, hypointensity was visualised on diffusion-weighted images. False-negative results were maintained in 3 of these patients, and true-negative results were maintained in 8 of them. An abscess which was seen on post-contrast conventional MRI could not be seen on DWI, and this was regarded as false-negative. Conclusion: The sensitivity and specificity of diffusion-weighted images for detecting soft tissue abscesses were found to be 92% and 80%, respectively. DWI has a high diagnostic value in soft tissue abscesses, and is an important imaging modality that may be used for the differentiation of cysts and abscesses.

The diagnostic value of diffusion-weighted magnetic resonance imaging in soft tissue abscesses

International Nuclear Information System (INIS)

Unal, Ozkan; Koparan, Halil Ibrahim; Avcu, Serhat; Kalender, Ali Murat; Kisli, Erol

2011-01-01

Purpose: To study the diagnostic value of diffusion-weighted imaging (DWI) in soft tissue abscesses. Materials and methods: Fifty patients were included in this study who were thought to have soft tissue abscess or cystic lesion as a result of clinical and radiological examinations. Localisations of the lesions were: 1 periorbital, 3 breast, 14 intraabdominal, and 32 intramuscular lesions. After other radiological examinations, DWI was performed. The signal intensity values of the lesions were evaluated qualitatively according to the hyperintensity on b-1000 DWI, using 1.5 T MR system. All of the lesions were aspirated after DWI, and detection of pus in the aspiration material was accepted as gold standard for the diagnosis of abscess. Results: In 38 of the 50 patients, hyperintensity was obtained on diffusion-weighted images. False-positive results were maintained in 2 of these patients, and true-positive results were maintained in 36 of them. In 11 of the 50 patients, hypointensity was visualised on diffusion-weighted images. False-negative results were maintained in 3 of these patients, and true-negative results were maintained in 8 of them. An abscess which was seen on post-contrast conventional MRI could not be seen on DWI, and this was regarded as false-negative. Conclusion: The sensitivity and specificity of diffusion-weighted images for detecting soft tissue abscesses were found to be 92% and 80%, respectively. DWI has a high diagnostic value in soft tissue abscesses, and is an important imaging modality that may be used for the differentiation of cysts and abscesses.

Intravoxel incoherent motion diffusion imaging of the liver: Optimal b-value subsampling and impact on parameter precision and reproducibility

International Nuclear Information System (INIS)

Dyvorne, Hadrien; Jajamovich, Guido; Kakite, Suguru; Kuehn, Bernd; Taouli, Bachir

2014-01-01

Highlights: • We assess the precision and reproducibility of liver IVIM diffusion parameters. • Liver IVIM DWI can be performed with 4 b-values with good parameter precision. • Liver IVIM DWI can be performed with 4 b-values with good parameter reproducibility. - Abstract: Purpose: To increase diffusion sampling efficiency in intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) of the liver by reducing the number of diffusion weightings (b-values). Materials and methods: In this IRB approved HIPAA compliant prospective study, 53 subjects (M/F 38/15, mean age 52 ± 13 y) underwent IVIM DWI at 1.5 T using 16 b-values (0–800 s/mm 2 ), with 14 subjects having repeat exams to assess IVIM parameter reproducibility. A biexponential diffusion model was used to quantify IVIM hepatic parameters (PF: perfusion fraction, D: true diffusion and D*: pseudo diffusion). All possible subsets of the 16 b-values were probed, with number of b values ranging from 4 to 15, and corresponding parameters were quantified for each subset. For each b-value subset, global parameter estimation error was computed against the parameters obtained with all 16 b-values and the subsets providing the lowest error were selected. Interscan estimation error was also evaluated between repeat exams to assess reproducibility of the IVIM technique in the liver. The optimal b-values distribution was selected such that the number of b-values was minimal while keeping parameter estimation error below interscan reproducibility error. Results: As the number of b-values decreased, the estimation error increased for all parameters, reflecting decreased precision of IVIM metrics. Using an optimal set of 4 b-values (0, 15, 150 and 800 s/mm 2 ), the errors were 6.5, 22.8 and 66.1% for D, PF and D* respectively. These values lie within the range of test–retest reproducibility for the corresponding parameters, with errors of 12.0, 32.3 and 193.8% for D, PF and D* respectively. Conclusion: A set

The diagnostic value of diffusion-weighted imaging and the apparent diffusion coefficient values in the differentiation of benign and malignant breast lesions

International Nuclear Information System (INIS)

Çabuk, Gonca; Duce, Meltem Nass; Özgür, Anil; Apaydin, Feramuz Demir; Polat, Ayşe; Orekici, Gülhan

2015-01-01

The goal of our study was to evaluate the diagnostic efficacy of diffusion-weighted imaging (DWI) in the differentiation of benign and malignant breast lesions. Between June 2012 and March 2013, 60 patients with 63 lesions (age range 29-70 years, mean age 48.6 years) were included in our study. All lesions, except complicated cysts and intra-mammary lymph nodes, were confirmed histopathologically. The patients were evaluated with a 1.5 Tesla MR scanner using dedicated bilateral breast coil. DWI images were obtained by echo planar imaging sequence and 'b' values were selected as 200, 600 and 1000 s/mm2. Apparent diffusion coefficient (ADC) values of both breast lesions and the normal fibroglandular tissue of the contralateral breast were calculated and statistically compared using Shapiro-Wilk test, Student's t-test, Mann-Whitney U test, chi-square test and the receiver operating curve. Of 63 lesions, 22 were malignant and 41 were benign. In malignant lesions, the mean ADC values were 1.40 ± 0.41 × 10 −3 mm 2 /s for b = 200, 1.05 ± 0.28 × 10 −3 mm 2 /s for b = 600 and 0.91 ± 0.20 × 10 −3 mm 2 /s for b = 1000 and in benign lesions, the mean ADC values were 2.13 ± 0.85 × 10 −3 mm 2 /s for b = 200, 1.64 ± 0.47 × 10 −3 mm 2 /s for b = 600 and 1.40 ± 0.43 × 10 −3 mm 2 /s for b = 1000. The success of ADC values in differentiation of benign and malignant lesions was statistically significant (P = 0.0001). The threshold values were determined to be 1.50 × 10 −3 mm 2 /s for b = 200, 1.22 × 10 −3 mm 2 /s for b = 600 and 0.98 × 10 −3 mm 2 /s for b = 1000 (P < 0.05). DWI can be an effective radiological method in the differentiation of benign and malignant breast lesions.

Apparent diffusion coefficient value of gastric cancer by diffusion-weighted imaging: Correlations with the histological differentiation and Lauren classification

International Nuclear Information System (INIS)

Liu, Song; Guan, Wenxian; Wang, Hao; Pan, Liang; Zhou, Zhuping; Yu, Haiping; Liu, Tian; Yang, Xiaofeng; He, Jian; Zhou, Zhengyang

2014-01-01

Highlights: • Gastric cancers’ ADC values were significantly lower than normal gastric wall. • Gastric adenocarcinomas with different differentiation had different ADC values. • Gastric adenocarcinomas’ ADC values correlated with histologic differentiations. • Gastric cancers’ ADC values correlated with Lauren classifications. • Mean ADC value was better than min ADC value in characterizing gastric cancers. - Abstract: Objective: The purpose of this study was to evaluate the correlations between histological differentiation and Lauren classification of gastric cancer and the apparent diffusion coefficient (ADC) value of diffusion weighted imaging (DWI). Materials and methods: Sixty-nine patients with gastric cancer lesions underwent preoperative magnetic resonance imaging (MRI) (3.0T) and surgical resection. DWI was obtained with a single-shot, echo-planar imaging sequence in the axial plane (b values: 0 and 1000 s/mm 2 ). Mean and minimum ADC values were obtained for each gastric cancer and normal gastric walls by two radiologists, who were blinded to the histological findings. Histological type, degree of differentiation and Lauren classification of each resected specimen were determined by one pathologist. Mean and minimum ADC values of gastric cancers with different histological types, degrees of differentiation and Lauren classifications were compared. Correlations between ADC values and histological differentiation and Lauren classification were analyzed. Results: The mean and minimum ADC values of gastric cancers, as a whole and separately, were significantly lower than those of normal gastric walls (all p values <0.001). There were significant differences in the mean and minimum ADC values among gastric cancers with different histological types, degrees of differentiation and Lauren classifications (p < 0.05). Mean and minimum ADC values correlated significantly (all p < 0.001) with histological differentiation (r = 0.564, 0.578) and Lauren

High and ultra-high b-value diffusion-weighted imaging in prostate cancer: a quantitative analysis.

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Wetter, Axel; Nensa, Felix; Lipponer, Christine; Guberina, Nika; Olbricht, Tobias; Schenck, Marcus; Schlosser, Thomas W; Gratz, Marcel; Lauenstein, Thomas C

2015-08-01

Diffusion-weighted imaging (DWI) is routinely used in magnetic resonance imaging (MRI) of prostate cancer. However, the routine use of b values higher than 1000 s/mm(2) is not clear up to present. Moreover, the complex diffusion behavior of malignant and benign prostate tissues hampers precise predictions of contrast in DWI images and apparent diffusion coefficient (ADC) maps. To quantitatively analyze DWI with different b values in prostate cancer and to identify b values best suitable for cancer detection. Forty-one patients with histologically proven prostate cancer were examined with high resolution T2-weighted imaging and DWI at 3 Tesla. Five different b values (0, 800, 1000, 1500, 2000 s/mm(2)) were applied. ADC values of tumors and reference areas were measured on ADC maps derived from different pairs of b values. Furthermore, signal intensities of DW images of tumors and reference areas were measured. For analysis, contrast ratios of ADC values and signal intensities of DW images were calculated and compared. No significant differences were found between contrast ratios measured on ADC maps of all analyzed b value pairs (P = 0.43). Contrast ratios calculated from signal intensities of DW images were highest at b values of 1500 and 2000 s/mm(2) and differed significantly from contrast ratios at b values of 800 and 1000 s/mm(2) (P values, contrast ratios of DW images are significantly higher at b-values of 1500 and 2000 s/mm(2) in comparison to b values of 800 and 1000 s/mm(2). Therefore, diagnostic performance of DWI in prostate cancer might be increased by application of b values higher than 1000 s/mm(2). © The Foundation Acta Radiologica 2014.

Toward quantitative fast diffusion kurtosis imaging with b-values chosen in consideration of signal-to-noise ratio and model fidelity.

Science.gov (United States)

Kuo, Yen-Shu; Yang, Shun-Chung; Chung, Hsiao-Wen; Wu, Wen-Chau

2018-02-01

Diffusion kurtosis (DK) imaging is a variant of conventional diffusion magnetic resonance (MR) imaging that allows assessment of non-Gaussian diffusion. Fast DK imaging expedites the procedure by decreasing both scan time (acquiring the minimally required number of b-values) and computation time (obviating least-square curve fitting). This study aimed to investigate the applicability of fast DK imaging for both cerebral gray matter and white matter as a quantitative method. Seventeen healthy volunteers were recruited and each provided written informed consent before participation. On a 3-Tesla clinical MR system, diffusion imaging was performed with 12 b-values ranging from 0 to 4000 s/mm 2 . Diffusion encoding was along three orthogonal directions (slice selection, phase encoding, and frequency encoding) in separate series. Candidate b-values were chosen by first determining the maximum b-value (b max ) in the context of signal-to-noise ratio and then assessing the model fidelity for all b-value combinations within b max . Diffusion coefficient (D) and diffusion kurtosis coefficient (K) were derived from these candidates and assessed for their dependence on b-value combination. Our data suggested b max to be 2200 s/mm 2 as a trade-off between the percentage (~80%) of voxels statistically detectable against background and the sensitivity to non-Gaussian diffusion in both gray matter and white matter. The measurement dependence on b-value was observed predominantly in areas with a considerable amount of cerebrospinal fluid. In most gray matter and white matter, b-value combinations do not cause statistical difference in the calculated D and K. For fast DK imaging to be quantitatively applicable in both gray matter and white matter, b max should be chosen to ensure adequate signal-to-noise ratio in the majority of gray/white matter and the two nonzero b-values should be chosen in consideration of model fidelity to mitigate the dependence of derived indices on b-values

Value of Diffusion Tensor Imaging of Prostate Cancer: Comparison with Systemic Prostate Biopsy

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Yoon, Seong Kuk; Kim, Dong Won; Ha, Dong Ho; Kwon, Hee Jin; Kang, Myong Jin; Choi, Sun Seob; Nam, Kyung Jin; Kim, Jung Il [Dong-A University, Medical Center, Busan (Korea, Republic of)

2011-02-15

This study was performed to evaluate the usefulness of diffusion tensor imaging (DTI) and to correlate systemic twelve biopsy in prostate cancer. Thirty-one patients with suspected prostate cancer underwent MR imaging. DTI was performed prior to a prostate biopsy. We prospectively calculated the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) value in each corresponding biopsy site. Twenty-three of 31 patients had histopathologically proven adenocarcinoma. Among the 276 biopsy cores of 23 patients with prostate cancer, 109 cores showed positive results (39%). The ADC and FA value of positive cores were 1.31 {+-} 0.34x10-3 mm2/s and 0.68 {+-} 0.07, and those of the negative cores were 1.74 {+-} 0.45x10-3 mm2/s and 0.54 {+-} 0.09, respectively. Eight patients without carcinoma showed an ADC value of 1.83 {+-} 0.26x10-3 mm2/s and an FA value of 0.47 {+-} 0.07. The ADC and FA value of positive cores were significantly lower and higher than those of negative cores and cancer-free patients, respectively (p < 0.05). The ADC and FA values using DTI may provide useful diagnostic information in the differentiation of cancerous tissues, although there is overlap in some cases

Study of the effect of yoga training on diffusion capacity in chronic obstructive pulmonary disease patients: A controlled trial

Directory of Open Access Journals (Sweden)

Ritu Soni

2012-01-01

Full Text Available Background: Patients of chronic obstructive pulmonary disease (COPD are at high risk for depression and anxiety. Yoga techniques are suited for promoting relaxation, psycho-emotional stability and exercise tolerance. Studies showing the effect of yoga in diffusion capacity are not available; hence this study was planned. Materials and Methods: The study was conducted on 60 diagnosed stable mild-to-moderate COPD patients in the age group of 30-60 years, of either sex, in the department of physiology. Patients were taken from Guru Teg Bahadur Hospital, Delhi and divided into two groups: Control and the yoga group. Both the groups were on conventional drug therapy. Subjects from the Yoga group was called to cardiopulmonary laboratory daily for 21 days and then weekly for the compliance. Yoga instructor taught them the technique of pranayama and various postures every day. They practiced yoga at home for 2 months for 45 min in the mornings. Diffusion capacity was recorded by using computerized Medisoft instrument (HYPAIR compact, in both the groups before and after 2 months. Results: Statistical analysis showed significant improvement in TLCO of the yoga group. Transfer factor of lung for carbon monoxide i.e. TLCO in mild COPD increased from 17.61 ± 4.55 to 19.08 ± 5.09 ml/mmHg/min, and in moderate COPD it increased from 14.99 ± 4.02 to17.35 ± 3.97 ml/mmHg/min. Conclusion: It was concluded that yogic breathing exercises improve diffusion capacity. They are beneficial to COPD patients and they can be used as an adjunct therapy with the conventional medical therapy.

Hidden wholesale: The drug diffusing capacity of online drug cryptomarkets.

Science.gov (United States)

Aldridge, Judith; Décary-Hétu, David

2016-09-01

In spite of globalizing processes 'offline' retail drug markets remain localized and - in recent decades - typically 'closed', in which dealers sell primarily to known customers. We characterize drug cryptomarkets as 'anonymous open' marketplaces that allow the diffusion of drugs across locales. Where cryptomarket customers make stock-sourcing purchases for offline distribution, the cryptomarket may indirectly serve drug users who are not themselves cryptomarket customers, thereby increasing the drug diffusing capacity of these marketplaces. Our research aimed to identify wholesale activity on the first major cryptomarket, Silk Road 1. Data were collected 13-15 September 2013. A bespoke web crawler downloaded content from the first major drug cryptomarket, Silk Road 1. This generated data on 1031 vendors and 10,927 drug listings. We estimated monthly revenues to ascertain the relative importance of wholesale priced listings. Wholesale-level revenue generation (sales for listings priced over USD $1000.00) accounted for about a quarter of the revenue generation on SR1 overall. Ecstasy-type drugs dominated wholesale activity on this marketplace, but we also identified substantial wholesale transactions for benzodiazepines and prescription stimulants. Less important, but still generating wholesale revenue, were cocaine, methamphetamine and heroin. Although vendors on the marketplace were located in 41 countries, wholesale activity was confined to only a quarter of these, with China, the Netherlands, Canada and Belgium prominent. The cryptomarket may function in part as a virtual broker, linking wholesalers with offline retail-level distributors. For drugs like ecstasy, these marketplaces may link vendors in producer countries directly with retail level suppliers. Wholesale activity on cryptomarkets may serve to increase the diffusion of new drugs - and wider range of drugs - in offline drug markets, thereby indirectly serving drug users who are not cryptomarket

High b-value diffusion-weighted MR imaging of normal brain at 3 T

International Nuclear Information System (INIS)

Cihangiroglu, Mutlu; Ulug, Aziz Muefit; Firat, Zeynep; Bayram, Ali; Kovanlikaya, Arzu; Kovanlikaya, Ilhami

2009-01-01

Introduction: The purpose of this study was to determine the normative apparent diffusion coefficient (ADC) values at 3 T using high b-value (3000 s/mm 2 ) diffusion-weighted images (DWI) and compare the signal characteristics of the high b value with standard b-value (1000 s/mm 2 ) DWI. Methods: Institutional review board approval was obtained for this prospective study which included 20 volunteers (10 M, 10 F, mean age: 38.7 ± 14.9) without any known clinical disease or radiological findings. All brain examinations were performed with 3 T MR by using similar parameters of b1000 and b3000 DWI sequences. DWI and ADC maps were obtained. Signal intensity, noise, signal to noise ratio (SNR), contrast to noise (CNR), contrast ratio (CR), and ADC values of bilateral posterior limb of internal capsule, frontal white matter, parietal gray matter, pons, thalamus, splenium of corpus callosum were measured on b1000 and b3000 DW images. Results: In all anatomic locations, MR signal intensity, SNR and ADC values of b3000 images were significantly lower than MR signal intensity, SNR and ADC values of b1000 images (p < 0.001). The CNR and CR values at the posterior limb of internal capsule and pons were significantly increased on b3000 images (p < 0.001) and decreased in the other regions measured. Conclusion: The ADC values calculated from standard b-value DWI were significantly higher than those calculated from high b-value DWI. These results agree with the previous studies. In the regions where CNR values increase with high b value, b3000 DWI images may provide additional clinical information.

Correlation between 3 T apparent diffusion coefficient values and grading of invasive breast carcinoma

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Cipolla, Valentina, E-mail: valentina.cipolla@yahoo.it [Department of Radiological Sciences, University of Rome “Sapienza”, Viale del Policlinico 155, 00161 Rome (Italy); Santucci, Domiziana; Guerrieri, Daniele; Drudi, Francesco Maria [Department of Radiological Sciences, University of Rome “Sapienza”, Viale del Policlinico 155, 00161 Rome (Italy); Meggiorini, Maria Letizia [Department of Gynaecological Sciences, University of Rome “Sapienza”, Viale del Policlinico 155, 00161 Rome (Italy); Felice, Carlo de [Department of Radiological Sciences, University of Rome “Sapienza”, Viale del Policlinico 155, 00161 Rome (Italy)

2014-12-15

Highlights: • Apparent diffusion coefficient is a quantitative parameter which reflects molecular water movement. • Grading is an independent prognostic factor which correlates with other histopathological features. • Apparent diffusion coefficient values were significantly different between G1 and G3 classes. - Abstract: Purpose: The aim of this study was to evaluate whether the apparent diffusion coefficient (ADC) provided by 3.0 T (3 T) magnetic resonance diffusion-weighted imaging (DWI) varied according to the grading of invasive breast carcinoma. Materials and methods: A total of 92 patients with 96 invasive breast cancer lesions were enrolled; all had undergone 3 T magnetic resonance imaging (MRI) for local staging. All lesions were confirmed by histological analysis, and tumor grade was established according to the Nottingham Grading System (NGS). MRI included both dynamic contrast-enhanced and DWI sequences, and ADC value was calculated for each lesion. ADC values were compared with NGS classification using the Mann–Whitney U and the Kruskal–Wallis H tests. Grading was considered as a comprehensive prognostic factor, and Rho Spearman test was performed to determine correlation between grading and tumor size, hormonal receptor status, HER2 expression and Ki67 index. Pearson's Chi square test was carried out to compare grading with the other prognostic factors. Results: ADC values were significantly higher in G1 than in G3 tumors. No significant difference was observed when G1 and G3 were compared with G2. Tumor size, hormonal receptor status, HER2 expression and Ki67 index correlated significantly with grading but there was a significant difference only between G1 and G3 related to the ER and PR status, HER2 expression and Ki67 index. There was no statistically significant difference in lesion size between the two groups. Conclusion: ADC values obtained on 3 T DWI correlated with low-grade (G1) and high-grade (G3) invasive breast carcinoma. 3

Effect of organic matter on 125I diffusion in bentonite

International Nuclear Information System (INIS)

Tao Wu; Qing Zheng

2015-01-01

Through-diffusion method was conducted to investigate the diffusion behavior of 125 I in bentonite in present of organic matter, such as polyaminopolycarboxylate EDTA, oxalic acid, hydrazine and humic acid HA. The effective diffusion coefficient D e value and rock capacity factor α were (2.32.6) × 10 -11 m 2 /s and 0.040-0.052, respectively. The small difference showed that iodine was preferentially associated with silicoaluminate mineral as an inorganic form. In present of HA, the D a value of 125 I was almost two orders of magnitude higher than that of HA and humic substances HS. The D e and α derived from the experiments were used to simulate its diffusion in the designed bentonite obstacle of high-level radioactive waste repository and the results showed that 125 I can be transported from 30 to 50 cm thickness of bentonite to the far-field of repository in several years. (author)

Lung diffusing capacity for nitric oxide and carbon monoxide in relation to morphological changes as assessed by computed tomography in patients with cystic fibrosis

Directory of Open Access Journals (Sweden)

Nowak Dennis

2009-06-01

Full Text Available Abstract Background Due to large-scale destruction, changes in membrane diffusion (Dm may occur in cystic fibrosis (CF, in correspondence to alterations observed by computed tomography (CT. Dm can be easily quantified via the diffusing capacity for nitric oxide (DLNO, as opposed to the conventional diffusing capacity for carbon monoxide (DLCO. We thus studied the relationship between DLNO as well as DLCO and a CF-specific CT score in patients with stable CF. Methods Simultaneous single-breath determinations of DLNO and DLCO were performed in 21 CF patients (mean ± SD age 35 ± 9 y, FEV1 66 ± 28%pred. Patients also underwent spirometry and bodyplethysmography. CT scans were evaluated via the Brody score and rank correlations (rS with z-scores of functional measures were computed. Results CT scores correlated best with DLNO (rS = -0.83; p S = -0.63; p CO (rS = -0.79; p NO were significantly lower than for DLCO (p 1, IVC or bodyplethysmographic (e.g., SRaw, RV/TLC indices were weaker than for DLNO or DLCO but most of them were also significant (p Conclusion In this cross sectional study in patients with CF, DLNO and DLCO reflected CT-morphological alterations of the lung better than other measures. Thus the combined diffusing capacity for NO and CO may play a future role for the non-invasive, functional assessment of structural alterations of the lung in CF.

pKa value and buffering capacity of acidic monomers commonly used in self-etching primers.

Science.gov (United States)

Salz, Ulrich; Mücke, Angela; Zimmermann, Jörg; Tay, Franklin R; Pashley, David H

2006-06-01

The aim of this investigation was to characterize acidic monomers used in self-etching primers/adhesives by determination of their pKa values and by calculation of their calcium dissolving capacity in comparison with phosphoric and hydrochloric acid. The following acidic monomers were included in this study: 4-methacryloyloxyethyl trimellitate anhydride (4-META), 10-methacryloyloxydecyl dihydrogen phosphate (MDP), dimethacryloyloxyethyl hydrogen phosphate (di-HEMA-phosphate), ethyl 2-[4-(dihydroxyphosphoryl)-2-oxabutyl]acrylate (EAEPA), 2-[4-(dihydroxyphosphoryl)-2-ox-abutyl]acrylic acid (HAEPA), and 2,4,6 trimethylphenyl 2-[4-(dihydroxyphosphoryl)-2-oxabutyl]acrylate (MAEPA). The pKa values were obtained by titration with 0.1 mol/l NaOH in aqueous solution. The inflection points of the resulting potentiometric titration curve were determined as pKa values. In the case of the sparingly water-soluble acidic monomers MAEPA and 4-META, the co-solvent method using different water/ethanol ratios for MAEPA or water/acetone ratios for 4-META was used. The dissolving capacity of each acidic monomer is defined as the amount of hydroxyapatite (HA) dissolved by 1 g of acid. For each monomer, the HA dissolving capacity was calculated bythe corresponding pKa value and the molecular weight. To confirm the calculated dissolving capacities, increasing amounts of HA powder (100 mg portions) were slowly added to 15 mmol/l aqueous solutions of the monomers to determine how much HA could be dissolved in the acidic solutions. For all the investigated acidic monomers, pKal values between 1.7 to 2.5 were observed. The pKa2 values for the phosphate/phosphonate derivatives are between 7.0 and 7.3, and are comparable to phosphoric acid. For dicarboxylic acid derivatives, the pKa2 values are in the range of 4.2 to 4.5. Due to their comparable molecular weights and pKal values, the three tested acids di-HEMA phosphate, MDP and 4-META all possess comparable dissolving capacities for HA (ie, 0

Required storage capacity to increase the value of renewable energy

International Nuclear Information System (INIS)

Nacht, T.

2014-01-01

The effort to achieve a more eco - friendly production of energy leads to larger shares of renewables in the electricity sector, resulting in more supply - dependency and volatility. This results in a time shift between production and consumption. In order to gain an upper hand, possibilities for transferring renewable energies from the time of production to the time when the demand occurs are researched. Energy storage systems will play a big role in this process, with pumped storage plants being the most developed and most common technology nowadays. As a first part of this thesis, the renewables in Germany are studied through the use of models on the basis of hourly measured values of the primary energy carriers for the corresponding technology. For these data series many years’ worth of measurements were considered, resulting in data for the hourly production values of the renewable energy sources. The results show a strong dependency between production and the seasons of the year. Furthermore a very small secured contribution of renewable production during times of peak load is registered, leading to the conclusion that energy storages are indeed necessary. Different strategies for the dispatch of the storage technologies pumped hydro storage, compressed air storage and hydrogen storage are developed for the region of Germany, which will be dispatched outside the energy - only market. The different strategies for the storage dispatch have the reduction of the resulting load in common, by preferably transferring renewable energy from times when it is not needed to those times with high loads. This resulting load needs to be covered by thermal power plants. The required capacities of the different storage technologies are evaluated and compared. By using pumped storage plants the increase in the value of renewables, as measured by the secure contribution during peak load hours, is determined. An analysis of different compositions of renewable production allows

Apparent diffusion coefficient value as a biomarker reflecting morphological and biological features of prostate cancer.

Science.gov (United States)

Bae, Hyeyeol; Yoshida, Soichiro; Matsuoka, Yoh; Nakajima, Hiroshi; Ito, Eisaku; Tanaka, Hiroshi; Oya, Miyako; Nakayama, Takayuki; Takeshita, Hideki; Kijima, Toshiki; Ishioka, Junichiro; Numao, Noboru; Koga, Fumitaka; Saito, Kazutaka; Akashi, Takumi; Fujii, Yasuhisa; Kihara, Kazunori

2014-03-01

To assess whether there is an association between the apparent diffusion coefficient (ADC) value and the pathological characteristics of prostate cancer. The study cohort consisted of 29 consecutive patients with prostate cancer treated with radical prostatectomy. All patients underwent diffusion-weighted MRI before the prostate biopsy. In 42 tumor foci, the associations of the ADC values with the clinicopathological characteristics and Ki-67 labeling index (LI) were analyzed. High-grade cancers (Gleason score [GS] ≥ 4 + 3), larger cancers (maximum diameter (MD) ≥ 16 mm), and highly proliferating cancers (Ki-67 LI ≥ 4.43 %) had significantly lower ADC values, respectively (P value according to age, prostate-specific antigen, presence of extra-prostatic extension, and intra-tumoral stroma proportion. Multivariate analysis showed that GS, Ki-67 LI, and MD had independent and significant correlations with ADC value (P value to predict high-grade cancer foci are 81.8 and 93.5 %, respectively. A low ADC value reflects the morphological and biological features of prostate cancer. Analyzing the ADC value may make it possible to more precisely predict the cancer aggressiveness of each focus before treatment.

Diffusion-weighted MRI of epithelial ovarian cancers: Correlation of apparent diffusion coefficient values with histologic grade and surgical stage

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Oh, Ji-Won, E-mail: fromentin@naver.com [Department of Radiology, Seoul St. Mary' s Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 137-701 (Korea, Republic of); Rha, Sung Eun, E-mail: serha@catholic.ac.kr [Department of Radiology, Seoul St. Mary' s Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 137-701 (Korea, Republic of); Oh, Soon Nam, E-mail: hiohsn@catholic.ac.kr [Department of Radiology, Seoul St. Mary' s Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 137-701 (Korea, Republic of); Park, Michael Yong, E-mail: digirave@kmle.com [Department of Radiology, Seoul St. Mary' s Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 137-701 (Korea, Republic of); Byun, Jae Young, E-mail: jybyun@catholic.ac.kr [Department of Radiology, Seoul St. Mary' s Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 137-701 (Korea, Republic of); Lee, Ahwon, E-mail: klee@catholic.ac.kr [Department of Hospital Pathology, Seoul St. Mary' s Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 137-701 (Korea, Republic of)

2015-04-15

Highlights: •The solid component of all invasive epithelial cancers showed high b{sub 1000} signal intensity. •ADCs can predict the histologic grade of epithelial ovarian cancer. •ADCs correlate negatively to the surgical stage of epithelial ovarian cancer. •ADCs may be useful imaging biomarkers to assess epithelial ovarian cancer. -- Abstract: Objective: The purpose of this article is to correlate the apparent diffusion coefficient (ADC) values of epithelial ovarian cancers with histologic grade and surgical stage. Materials and methods: We enrolled 43 patients with pathologically proven epithelial ovarian cancers for this retrospective study. All patients underwent preoperative pelvic magnetic resonance imaging (MRI) including diffusion-weighted images with b value of 0 and 1000 s/mm{sup 2} at 3.0-T unit. The mean ADC values of the solid portion of the tumor were measured and compared among different histologic grades and surgical stages. Results: The mean ADC values of epithelial ovarian cancers differed significantly between grade 1 (well-differentiated) and grade 2 (moderately-differentiated) (P = 0.013) as well as between grade 1 and grade 3 (poorly-differentiated) (P = 0.01); however, no statistically significant difference existed between grade 2 and grade 3 (P = 0.737). The receiver-operating characteristic analysis indicated that a cutoff ADC value of less than or equal to 1.09 × 10{sup −3} mm{sup 2}/s was associated with 94.4% sensitivity and 85.7% specificity in distinguishing grade 1 and grade 2/3 cancer. The difference in mean ADC values was statistically significant for early stage (FIGO stage I) and advanced stage (FIGO stage II-IV) cancer (P = 0.011). The interobserver agreement for the mean ADC values of epithelial ovarian cancers was excellent. Conclusion: The mean ADC values of the solid portion of epithelial ovarian cancers negatively correlated to histologic grade and surgical stage. The mean ADC values may be useful imaging

Diffusion in crushed rock and in bentonite clay

International Nuclear Information System (INIS)

Olin, M.

1994-04-01

Diffusion theories for porous media with sorption are reviewed to serve as a basis for considering diffusion in simple systems like sand of crushed rock. A Fickian diffusion and linear sorption model is solved both by analytical Laplance transform and Green's function methods and by numerical methods, and then applied to small-scale experiments for Finnish low- and medium-level operating waste repositories. The main properties of bentonite are reviewed. The hydraulic conductivity of compacted bentonite is so low that the major transport mechanism is diffusion. A Fickian diffusion and linear sorption model is applied to bentonite. The main component of bentonite, montmorillonite, has a high ion-exchange capacity and thus, transport in bentonite consists of interactive chemical and diffusion phenomena. A chemical equilibrium model, CHEQ, is developed for ion-exchange reactions in bentonite water systems. CHEQ is applied to some bentonite experiments with success, especially for monovalent ions. The fitted log-binding constants for sodium exchange with potassium, magnesium, and calcium were 0.27, 1.50, and 2.10, respectively. A coupled chemical and diffusion model, CHEQDIFF, is developed to take account of diffusion in pore water, surface diffusion and ion-exchange reactions. The model is applied to the same experiments as CHEQ, and validation is partly successful. In the diffusion case, the above-mentioned values for binding constants are used. The apparent diffusion (both anions and cations) and surface diffusion (only for cations) constants used are 3.0*10 -11 m 2 /s and 6.0*10 -12 m 2 /s, respectively, but these values are questionable, as experimental results good enough for fitting are not available. (orig.). (74 refs., 27 figs., 12 tabs.)

Physicians' personal values in determining medical decision-making capacity: a survey study.

Science.gov (United States)

Hermann, Helena; Trachsel, Manuel; Biller-Andorno, Nikola

2015-09-01

Decision-making capacity (DMC) evaluations are complex clinical judgements with important ethical implications for patients' self-determination. They are achieved not only on descriptive grounds but are inherently normative and, therefore, dependent on the values held by those involved in the DMC evaluation. To date, the issue of whether and how physicians' personal values relate to DMC evaluation has never been empirically investigated. The present survey study aimed to investigate this question by exploring the relationship between physicians' value profiles and the use of risk-relative standards in capacity evaluations. The findings indicate that physicians' personal values are of some significance in this regard. Those physicians with relatively high scores on the value types of achievement, power-resource, face and conformity to interpersonal standards were more likely to apply risk-relative criteria in a range of situations, using more stringent assessment standards when interventions were riskier. By contrast, those physicians who strongly emphasise hedonism, conformity to rules and universalism concern were more likely to apply equal standards regardless of the consequences of a decision. Furthermore, it has been shown that around a quarter of all respondents do not appreciate that their values impact on their DMC evaluations, highlighting a need to better sensitise physicians in this regard. The implications of these findings are discussed, especially in terms of the moral status of the potential and almost unavoidable influence of physicians' values. 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.

The correlation between biological activity and diffusion-weighted MR imaging and ADC value in cases with prostate cancer.

Science.gov (United States)

Sokmen, Bedriye Koyuncu; Sokmen, Dogukan; Ucar, Nese; Ozkurt, Huseyin; Simsek, Abdulmuttalip

2017-12-31

Firstly, we aimed to investigate the correlation among dynamic contrasted magnetic resonance (MR) images, diffusion-weighted MR images, and apparent diffusion coefficent (ADC) values in patients with prostate cancer. Secondly, we aimed to investigate the roles of these variables on clinical risk classification and the biological behavior of the prostate cancer. A total of sixty with prostatic adenocarcinoma patients diagnosed between January 2011 and May 2013 were retrospectively included in the study. Risk classification of patients were evaluated as low-risk (Group 1) (n = 20) (Stage T1c-T2a, PSA T3a, PSA > 20 ng/ml, Gleason Score > 7). Diffusion-weighted MR images, dynamic contrasted MR images, and ADC values of the prostates were correlated. ADC values of the cases in Group 3 were lower than those of the other groups (p values of the areas without malignancy did not differ significantly between groups (p > 0.05). Biological activity of the tumor tissue was determined by GS, while a negative correlation was observed between GSs and ADC values of the patients, (p values were obtained. These measured values can play a role in the noninvasive determination of the cellularity of the tumoral mass.

Value of diffusion-weighted MR imaging using various parameters for assessment and characterization of solitary pulmonary nodules

International Nuclear Information System (INIS)

Koyama, Hisanobu; Ohno, Yoshiharu; Seki, Shinichiro; Nishio, Mizuho; Yoshikawa, Takeshi; Matsumoto, Sumiaki; Maniwa, Yoshimasa; Itoh, Tomoo; Nishimura, Yoshihiro; Sugimura, Kazuro

2015-01-01

Highlights: •Signal–intensity ratio evaluation between lesion and spinal cord is practical method. •Apparent diffusion coefficients may not contribute to the diagnosis of malignant. •True diffusion coefficients may have low potential for the differentiation. •Perfusion fractions may be less specific parameter of diagnosis of pulmonary nodule. •Choice of b values shows little impact for differentiation of pulmonary nodules. -- Abstract: Objectives: To determine the appropriate parameters and evaluation method for characterizing solitary pulmonary nodules (SPNs) using quantitative parameters of diffusion-weighted imaging (DWI). Methods: Thirty-two subjects with 36 SPNs underwent DWI with seven different b values (0, 50, 100, 150, 300, 500, and 1000 s/mm 2 ). Five quantitative parameters were obtained from the region of interest drawn over each SPN: apparent diffusion coefficients (ADCs), true diffusion coefficients (DCs), and perfusion fractions (PFs), and signal–intensity ratios between lesion and spinal cord from DWI (b values: 1000 [LSR 1000 ] and 500 [LSR 500 )]). All quantitative parameters and the diagnostic capabilities were statistically compared. Results: SPNs were diagnosed as follow: malignant (n = 27) and benign (n = 9). Parameter comparisons for malignant and benign showed both LSRs differed significantly (p < 0.05). Applying feasible threshold values showed LSR 500 specificity (88.9% [8/9]) and accuracy (77.8% [28/36]) were significantly higher than ADC, DC, and PF specificity and accuracy (p < 0.05). LSR 1000 accuracy (72.2% [26/36]) was significantly higher than DC accuracy, and its specificity (88.9% [8/9]) was significantly higher than ADC, DC, and PF specificities (p < 0.05). Conclusions: For quantitative differentiation of SPNs, LSR evaluation was more useful and practical than ADC, DC, and PF, and choice of b values showed little impact for the differentiation

FDG-PET/CT and diffusion-weighted imaging for resected lung cancer: correlation of maximum standardized uptake value and apparent diffusion coefficient value with prognostic factors.

Science.gov (United States)

Usuda, Katsuo; Funasaki, Aika; Sekimura, Atsushi; Motono, Nozomu; Matoba, Munetaka; Doai, Mariko; Yamada, Sohsuke; Ueda, Yoshimichi; Uramoto, Hidetaka

2018-04-09

Diffusion-weighted magnetic resonance imaging (DWI) is useful for detecting malignant tumors and the assessment of lymph nodes, as FDG-PET/CT is. But it is not clear how DWI influences the prognosis of lung cancer patients. The focus of this study is to evaluate the correlations between maximum standardized uptake value (SUVmax) of FDG-PET/CT and apparent diffusion coefficient (ADC) value of DWI with known prognostic factors in resected lung cancer. A total of 227 patients with resected lung cancers were enrolled in this study. FEG-PET/CT and DWI were performed in each patient before surgery. There were 168 patients with adenocarcinoma, 44 patients with squamous cell carcinoma, and 15 patients with other cell types. SUVmax was a factor that was correlated to T factor, N factor, or cell differentiation. ADC of lung cancer was a factor that was not correlated to T factor, or N factor. There was a significantly weak inverse relationship between SUVmax and ADC (Correlation coefficient r = - 0.227). In analysis of survival, there were significant differences between the categories of sex, age, pT factor, pN factor, cell differentiation, cell type, and SUVmax. Univariate analysis revealed that SUVmax, pN factor, age, cell differentiation, cell type, sex, and pT factor were significant factors. Multivariate analysis revealed that SUVmax and pN factor were independent significant prognostic factors. SUVmax was a significant prognostic factor that is correlated to T factor, N factor, or cell differentiation, but ADC was not. SUVmax may be more useful for predicting the prognosis of lung cancer than ADC values.

Cortical hypoxic-ischemic brain damage in shaken-baby (shaken impact) syndrome: value of diffusion-weighted MRI

International Nuclear Information System (INIS)

Parizel, Paul M.; Oezsarlak, Oezkan; Goethem, Johan W. van; Ceulemans, Berten; Laridon, Annick; Jorens, Philippe G.

2003-01-01

Shaken-baby syndrome (SBS) is a type of child abuse caused by violent shaking of an infant, with or without impact, and characterized by subdural hematomas, retinal hemorrhages, and occult bone fractures. Parenchymal brain lesions in SBS may be missed or underestimated on CT scans, but can be detected at an earlier stage with diffusion-weighted MRI (DW-MRI) as areas of restricted diffusion. We demonstrate the value of DW-MRI in a 2-month-old baby boy with suspected SBS. The pattern of diffusion abnormalities indicates that the neuropathology of parenchymal lesions in SBS is due to hypoxic-ischemic brain injuries, and not to diffuse axonal injury. (orig.)

Cortical hypoxic-ischemic brain damage in shaken-baby (shaken impact) syndrome: value of diffusion-weighted MRI

Energy Technology Data Exchange (ETDEWEB)

Parizel, Paul M.; Oezsarlak, Oezkan; Goethem, Johan W. van [Department of Radiology, University of Antwerp, Wilrijkstraat 10, 2650, Edegem (Belgium); Ceulemans, Berten; Laridon, Annick [Department of Pediatric Neurology, University of Antwerp, Wilrijkstraat 10, 2650, Edegem (Belgium); Jorens, Philippe G. [Department of Pediatric Intensive Care Medicine, University of Antwerp, Wilrijkstraat 10, 2650, Edegem (Belgium)

2003-12-01

Shaken-baby syndrome (SBS) is a type of child abuse caused by violent shaking of an infant, with or without impact, and characterized by subdural hematomas, retinal hemorrhages, and occult bone fractures. Parenchymal brain lesions in SBS may be missed or underestimated on CT scans, but can be detected at an earlier stage with diffusion-weighted MRI (DW-MRI) as areas of restricted diffusion. We demonstrate the value of DW-MRI in a 2-month-old baby boy with suspected SBS. The pattern of diffusion abnormalities indicates that the neuropathology of parenchymal lesions in SBS is due to hypoxic-ischemic brain injuries, and not to diffuse axonal injury. (orig.)

Consistency in thermophysical properties: enthalpy, heat capacity, thermal conductivity and thermal diffusivity of solid UO2

International Nuclear Information System (INIS)

Fink, J.K.; Chasanov, M.G.; Leibowitz, L.

Equations have been derived for the enthalpy, heat capacity, thermal conductivity, and thermal diffusivity of UO 2 . In selection of these equations, we considered the traditional criterion of lowest relative standard deviation between experimental data and the function chosen to fit these data as well as consistency between the thermophysical properties. In the latter case, we considered consistency in (1) thermodynamic relations among properties, (2) the choice of physical phenomena on which to base the theoretical formulation of the equations, and (3) the existence and temperature of phase transitions

Diffusion-weighted MR imaging of non-complicated hepatic cysts: Value of 3T computed diffusion-weighted imaging

International Nuclear Information System (INIS)

Nakamura, Yuko; Higaki, Toru; Akiyama, Yuji; Fukumoto, Wataru; Kajiwara, Kenji; Kaichi, Yoko; Honda, Yukiko; Komoto, Daisuke; Tatsugami, Fuminari; Iida, Makoto; Ohmoto, Toshifumi; Date, Shuji; Awai, Kazuo

2016-01-01

To investigate the utility of computed 3T diffusion-weighted imaging (c-DWI) for the diagnosis of non-complicated hepatic cysts with a focus on the T2 shine-through effect. In 50 patients with non-complicated hepatic cysts we acquired one set of DWIs (b-value 0 and 1000 s/mm 2 ) at 1.5T, and two sets at 3T (b-value 0 and 1000 s/mm 2 , TE 70 ms; b-value 0 and 600 s/mm 2 , TE 60 ms). We defined the original DWIs acquired with b = 1000 s/mm 2 at 1.5T and 3T as “o-1.5T-1000” and “o-3T-1000”. c-DWIs were calculated with 3T DWI at b-values of 0 and 600 s/mm 2 . c-DWI with b = 1000 and 1500 s/mm 2 were defined as “c-1000” and “c-1500”. Radiologists evaluated the signal intensity (SI) of the cysts using a 3-point score where 1 = not visible, 2 = discernible, and 3 = clearly visible. They calculated the contrast ratio (CR) between the cysts and the surrounding liver parenchyma on each DWIs and recorded the apparent diffusion coefficient (ADC) with a b-value = 0 and 1000 s/mm 2 on 1.5T- and 3T DWIs. Compared with o-1.5T-1000 DWI, the visual scores of all but the c-1500 DWIs were higher (p = 0.07 for c-1500- and p < 0.01 for the other DWIs). The CR at b = 1000 s/mm 2 was higher on o-3T-1000- than on o-1.5T-1000- (p < 0.01) but not higher than on c-1500 DWIs (p = 0.96). The CR at b = 0 s/mm 2 on 3T images with TE 70 ms was higher than on 1.5T images (p < 0.01). The ADC value was higher for 3T- than 1.5T images (p < 0.01). Non-complicated hepatic cysts showed higher SI on o-3T-1000- than o-1.5T-1000 DWIs due to the T2-shine through effect. This high SI was suppressed on c-1500 DWIs

Correlation between apparent diffusion coefficient value on diffusion-weighted MR imaging and Gleason score in prostate cancer.

Science.gov (United States)

Wu, X; Reinikainen, P; Vanhanen, A; Kapanen, M; Vierikko, T; Ryymin, P; Hyödynmaa, S; Kellokumpu-Lehtinen, P-L

2017-01-01

To investigate whether diffusion-weighted imaging (DWI) apparent diffusion coefficient (ADC) correlates with prostate cancer aggressiveness and further to compare the diagnostic performance of ADC and normalized ADC (nADC: normalized to non-tumor tissue). Thirty pre-treatment patients (mean age, 69years; range: 59-78years) with prostate cancer underwent magnetic resonance imaging (MRI) examination, including DWI with three b values: 50, 400, and 800s/mm 2 . Both ADC and nADC were correlated with the Gleason score obtained through transrectal ultrasound-guided biopsy. The tumor minimum ADC (ADC min : the lowest ADC value within tumor) had an inverse correlation with the Gleason score (r=-0.43, Pcorrelated with the Gleason score (r=-0.52 and r=-0.55, P<0.01; respectively), and they were lower in patients with Gleason score 3+4 than those with Gleason score 3+3 (P<0.01; respectively). Receiver operating characteristic (ROC) analysis showed that the area under the ROC curve was 0.765, 0.818, or 0.833 for the ADC min , nADC min , or nADC mean ; respectively, in differentiating between Gleason score 3+4 and 3+3 tumors. Tumor ADC min , nADC min , and nADC mean are useful markers to predict the aggressiveness of prostate cancer. Copyright © 2016 Éditions françaises de radiologie. Published by Elsevier Masson SAS. All rights reserved.

8760-Based Method for Representing Variable Generation Capacity Value in Capacity Expansion Models

Energy Technology Data Exchange (ETDEWEB)

Frew, Bethany A [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2017-08-03

Capacity expansion models (CEMs) are widely used to evaluate the least-cost portfolio of electricity generators, transmission, and storage needed to reliably serve load over many years or decades. CEMs can be computationally complex and are often forced to estimate key parameters using simplified methods to achieve acceptable solve times or for other reasons. In this paper, we discuss one of these parameters -- capacity value (CV). We first provide a high-level motivation for and overview of CV. We next describe existing modeling simplifications and an alternate approach for estimating CV that utilizes hourly '8760' data of load and VG resources. We then apply this 8760 method to an established CEM, the National Renewable Energy Laboratory's (NREL's) Regional Energy Deployment System (ReEDS) model (Eurek et al. 2016). While this alternative approach for CV is not itself novel, it contributes to the broader CEM community by (1) demonstrating how a simplified 8760 hourly method, which can be easily implemented in other power sector models when data is available, more accurately captures CV trends than a statistical method within the ReEDS CEM, and (2) providing a flexible modeling framework from which other 8760-based system elements (e.g., demand response, storage, and transmission) can be added to further capture important dynamic interactions, such as curtailment.

Value of 3 Tesla diffusion-weighted magnetic resonance imaging for assessing liver fibrosis.

Science.gov (United States)

Papalavrentios, Lavrentios; Sinakos, Emmanouil; Chourmouzi, Danai; Hytiroglou, Prodromos; Drevelegas, Konstantinos; Constantinides, Manos; Drevelegas, Antonios; Talwalkar, Jayant; Akriviadis, Evangelos

2015-01-01

Limited data are available regarding the role of magnetic resonance imaging (MRI), particularly the new generation 3 Tesla technology, and especially diffusion-weighted imaging (DWI) in predicting liver fibrosis. The aim of our pilot study was to assess the clinical performance of the apparent diffusion coefficient (ADC) of liver parenchyma for the assessment of liver fibrosis in patients with non-alcoholic fatty liver disease (NAFLD). 18 patients with biopsy-proven NAFLD underwent DWI with 3 Tesla MRI. DWI was performed with single-shot echo-planar technique at b values of 0-500 and 0-1000 s/mm 2 . ADC was measured in four locations in the liver and the mean ADC value was used for analysis. Staging of fibrosis was performed according to the METAVIR system. The median age of patients was 52 years (range 23-73). The distribution of patients in different fibrosis stages was: 0 (n=1), 1 (n=7), 2 (n=1), 3 (n=5), 4 (n=4). Fibrosis stage was poorly associated with ADC at b value of 0-500 s/mm 2 (r= -0.30, P=0.27). However it was significantly associated with ADC at b value of 0-1000 s/mm 2 (r= -0.57, P=0.01). For this b value (0-1000 s/mm 2 ) the area under receiver-operating characteristic curve was 0.93 for fibrosis stage ≥3 and the optimal ADC cut-off value was 1.16 ×10 -3 mm 2 /s. 3 Tesla DWI can possibly predict the presence of advanced fibrosis in patients with NAFLD.

The relationship between alveolar oxygen tension and the single-breath carbon monoxide diffusing capacity.

Science.gov (United States)

Kanner, R E; Crapo, R O

1986-04-01

The effects of alveolar oxygen tension (PAO2) on the single-breath carbon monoxide diffusing capacity (DLCO) were quantified and a factor was derived to accommodate for differences in PAO2 over commonly encountered altitudes and/or varying concentrations of oxygen in the test gas mixture (FIO2) We performed duplicate measurements of DLCO in 7 normal subjects with 6 different oxygen fractions (0.176, 0.196, 0.211, 0.22, 0.25, and 0.27). The PAO2 for each test was measured as the PO2 in the alveolar gas sample bag. DLCO varied inversely with PAO2 and changed by 0.35% for each mmHg change in PAO2 (r = -0.62, p less than 0.001). At an FIO2 of 0.25, PAO2 varied between subjects and was highly correlated with each subject's residual volume to total lung capacity ratio (r = -0.84, p less than 0.001). We suggest that laboratories can adjust the measured DLCO when PAO2 is not congruent to 120 mmHg by the following formula: DLCO (corrected = DLCO (measured) x [1.0 + 0.0035 (PAO2 - 120)].

Additional Value of Diffusion-Weighted Imaging to Evaluate Prognostic Factors of Breast Cancer: Correlation with the Apparent Diffusion Coefficient

International Nuclear Information System (INIS)

Park, Eun Kyung; Cho, Kyu Ran; Seo, Bo Kyoung; Woo, Ok Hee; Cho, Sung Bum; Bae, Jeoung Won

2016-01-01

Breast cancer is a heterogeneous disease with diverse prognoses. The main prognostic determinants are lymph node status, tumor size, histological grade, and biological factors, such as hormone receptors, human epidermal growth factor receptor 2 (HER2), Ki-67 protein levels, and p53 expression. Diffusion-weighted imaging (DWI) can be used to measure the apparent diffusion coefficient (ADC) that provides information related to tumor cellularity and the integrity of the cell membranes. The goal of this study was to evaluate whether ADC measurements could provide information on the prognostic factors of breast cancer. A total of 71 women with invasive breast cancer, treated consecutively, who underwent preoperative breast MRIs with DWI at 3.0 Tesla and subsequent surgery, were prospectively included in this study. Each DWI was acquired with b values of 0 and 1000 s/mm 2 . The mean ADC values of the lesions were measured, including the entire lesion on the three largest sections. We performed histopathological analyses for the tumor size, lymph node status, histological grade, hormone receptors, human epidermal growth factor receptor 2 (HER2), Ki-67, p53, and molecular subtypes. The associations with the ADC values and prognostic factors of breast cancer were evaluated using the independent-samples t test and the one-way analysis of variance (ANOVA). A low ADC value was associated with lymph node metastasis (P < 0.01) and with high Ki-67 protein levels (P = 0.03). There were no significant differences in the ADC values among the histological grade (P = 0.48), molecular subtype (P = 0.51), tumor size (P = 0.46), and p53 protein level (P = 0.62). The pre-operative use of the 3.0 Tesla DWI could provide information about the lymph node status and tumor proliferation for breast cancer patients, and could help determine the optimal treatment plan

Morphometric partitioning of the respiratory surface area and diffusion capacity of the gills and swim bladder in juvenile Amazonian air-breathing fish, Arapaima gigas.

Science.gov (United States)

Fernandes, Marisa Narciso; da Cruz, André Luis; da Costa, Oscar Tadeu Ferreira; Perry, Steven Franklin

2012-09-01

The gills and the respiratory swim bladders of juvenile specimens (mean body mass 100g) of the basal teleost Arapaima gigas (Cuvier 1829) were evaluated using stereological methods in vertical sections. The surface areas, harmonic mean barrier thicknesses and morphometric diffusing capacities for oxygen and carbon dioxide were estimated. The average respiratory surface area of the swim bladder (2173 cm² kg⁻¹) exceeded that of the gills (780 cm² kg⁻¹) by a factor of 2.79. Due to the extremely thin air-blood barrier in the swim bladder (harmonic mean 0.22 μm) and the much thicker water-blood barrier of the gills (9.61 μm), the morphometric diffusing capacity for oxygen and carbon dioxide was 88 times greater in the swim bladder than in the gills. These data clearly indicate the importance of the swim bladder, even in juvenile A. gigas that still engage in aquatic respiration. Because of the much greater diffusion constant of CO₂ than O₂ in water, the gills also remain important for CO₂ release. Copyright © 2012 Elsevier Ltd. All rights reserved.

The value of holding scarce wind resource—A cause of overinvestment in wind power capacity in China

International Nuclear Information System (INIS)

Liu, Xuemei

2013-01-01

China's wind power capacity has increased dramatically in recent years, but about 30% of the installed capacity sits idle, so overinvestment in wind power capacity seems to be a serious problem. This paper explores reasons for the overinvestment. The economic analysis shows that, given uncertain future policy on wind power, it is optimal for power companies to invest more than the amount in a certain world. A part of the “overinvestment” has a real value, which can be interpreted as the value of holding scarce wind resource. This value exists because the wind-rich sites with convenient locations to connect to the grids are scarce resource, and also because the specific government policies that are essential for promoting wind power are uncertain in the future. This value should be taken into account in the investment decision, but it results in the phenomenon of “overinvestment”. The concept of the value of holding scarce resource can be generally applied to the resources that are scarce and for which the future policy is uncertain

The correlation between biological activity and diffusion-weighted MR imaging and ADC value in cases with prostate cancer

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Bedriye Koyuncu Sokmen

2017-12-01

Full Text Available Purpose: Firstly, we aimed to investigate the correlation among dynamic contrasted magnetic resonance (MR images, diffusion-weighted MR images, and apparent diffusion coefficent (ADC values in patients with prostate cancer. Secondly, we aimed to investigate the roles of these variables on clinical risk classification and the biological behavior of the prostate cancer. Methods: A total of sixty with prostatic adenocarcinoma patients diagnosed between January 2011 and May 2013 were retrospectively included in the study. Risk classification of patients were evaluated as low-risk (Group 1 (n = 20 (Stage T1c-T2a, PSA T3a, PSA > 20 ng/ml, Gleason Score > 7. Diffusion-weighted MR images, dynamic contrasted MR images, and ADC values of the prostates were correlated. Results: ADC values of the cases in Group 3 were lower than those of the other groups (p 0.05. Biological activity of the tumor tissue was determined by GS, while a negative correlation was observed between GSs and ADC values of the patients, (p < 0.001. Conclusion: In tumors with higher Gleason scores, lower ADC values were obtained. These measured values can play a role in the noninvasive determination of the cellularity of the tumoral mass.

MGH-USC Human Connectome Project datasets with ultra-high b-value diffusion MRI.

Science.gov (United States)

Fan, Qiuyun; Witzel, Thomas; Nummenmaa, Aapo; Van Dijk, Koene R A; Van Horn, John D; Drews, Michelle K; Somerville, Leah H; Sheridan, Margaret A; Santillana, Rosario M; Snyder, Jenna; Hedden, Trey; Shaw, Emily E; Hollinshead, Marisa O; Renvall, Ville; Zanzonico, Roberta; Keil, Boris; Cauley, Stephen; Polimeni, Jonathan R; Tisdall, Dylan; Buckner, Randy L; Wedeen, Van J; Wald, Lawrence L; Toga, Arthur W; Rosen, Bruce R

2016-01-01

The MGH-USC CONNECTOM MRI scanner housed at the Massachusetts General Hospital (MGH) is a major hardware innovation of the Human Connectome Project (HCP). The 3T CONNECTOM scanner is capable of producing a magnetic field gradient of up to 300 mT/m strength for in vivo human brain imaging, which greatly shortens the time spent on diffusion encoding, and decreases the signal loss due to T2 decay. To demonstrate the capability of the novel gradient system, data of healthy adult participants were acquired for this MGH-USC Adult Diffusion Dataset (N=35), minimally preprocessed, and shared through the Laboratory of Neuro Imaging Image Data Archive (LONI IDA) and the WU-Minn Connectome Database (ConnectomeDB). Another purpose of sharing the data is to facilitate methodological studies of diffusion MRI (dMRI) analyses utilizing high diffusion contrast, which perhaps is not easily feasible with standard MR gradient system. In addition, acquisition of the MGH-Harvard-USC Lifespan Dataset is currently underway to include 120 healthy participants ranging from 8 to 90 years old, which will also be shared through LONI IDA and ConnectomeDB. Here we describe the efforts of the MGH-USC HCP consortium in acquiring and sharing the ultra-high b-value diffusion MRI data and provide a report on data preprocessing and access. We conclude with a demonstration of the example data, along with results of standard diffusion analyses, including q-ball Orientation Distribution Function (ODF) reconstruction and tractography. Copyright © 2015 Elsevier Inc. All rights reserved.

Clinical value of diffusion-weighted MR imaging in acute contusion of spinal cord

International Nuclear Information System (INIS)

Zhang Jinsong; Huan Yi; Sun Lijun; Zhao Haitao; Ge Yali; Chang Yingjuan; Yang Chunmin

2005-01-01

Objective: To study the clinical value of diffusion-weighted MR imaging (DWI) in acute contusion of spinal cord. Methods: Eighteen cases with acute contusion of spinal cord were examined with routine MRI and DWI, including single-shot DWI (ssh-DWI) in 2 cases and multi-shot DWI (msh-DWI) in 16 cases, on a 1.5-tesla MR system within 72 h post-trauma. Results: Two cases examined by ssh-DWI showed local lesions with significant high signals, but ssh-DWI images could not be used to measure apparent diffusion coefficient (ADC) value due to its weak resolution. Other 16 cases examined by msh-DWI showed better images and were classified into three categories depending on different degrees of tissue injury and characteristics of DWI: (1) Edema-type: ten cases presented DWI high signals with different degree in local lesions. There were significant difference of ADC values between lesions and normal parts (t=7.515, P 2 WI heterogeneous high signals and T 1 WI low signals due to prominent hemorrhage. Conclusion: DWI of the spinal cord provided satisfactory images and was a useful method for visualizing the injury cord in the super-early stage, helping determine integrity and compression degree of spinal cord and detecting hemorrhage. (authors)

Diffusion-Tensor Imaging of Thigh Muscles in Duchenne Muscular Dystrophy: Correlation of Apparent Diffusion Coefficient and Fractional Anisotropy Values With Fatty Infiltration.

Science.gov (United States)

Li, Gui Dian; Liang, Ying Yin; Xu, Ping; Ling, Jian; Chen, Ying Ming

2016-04-01

The purpose of this study is to investigate the correlation of apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values with fatty infiltration in the thigh muscles of patients with Duchenne muscular dystrophy (DMD) using diffusion-tensor imaging (DTI). Twenty-one boys with DMD were recruited. The grade of fatty infiltration and the ADC and FA values of four thigh muscles (rectus femoris, semitendinosus, sartorius, and gracilis) were measured, and the FA and ADC values were compared with the grade of fatty infiltration. Twenty age-matched healthy boys were enrolled as the control group. The differences in the ADC and FA values of the thigh muscles between patients with DMD and the control group were compared. The patients with DMD showed lower FA values and higher ADC values in all measured muscles when compared with the control group. The FA and ADC values were correlated with the grade of fatty infiltration. For the rectus femoris muscle, r = -0.753 and p = 0.007 for FA, and r = 0.685 and p = 0.001 for ADC. For the semitendinosus muscle, r = -0.621 and p = 0.041 for FA, and r = 0.705 and p = 0.021 for ADC. For the sartorius muscle, r = -0.662 and p = 0.027 for FA, and r = 0.701 and p = 0.017 for ADC. For the gracilis muscle, r = -0.618 and p = 0.043 for FA, and r = 0.695 and p = 0.022 for ADC. Damage to the thigh muscles in patients with DMD can be detected by ADC and FA values using DTI. DTI can be used to assess the severity of the disease.

Evaluation of malignant and benign renal lesions using diffusion-weighted MRI with multiple b values

International Nuclear Information System (INIS)

Erbay, Gurcan; Koc, Zafer; Karadeli, Elif; Kuzgunbay, Baris; Goren, M. Resit; Bal, Nebil

2012-01-01

Background: Limited data are available regarding the use of diffusion-weighted (DW) magnetic resonance imaging (MRI) with multiple b values for characterization of renal lesions. Purpose: To demonstrate and compare the diagnostic performance of DW-MRI with multiple b values for renal lesion characterization. Material and Methods: Sixty-three lesions (36 malignant, 27 benign) in 60 consecutive patients (48 men, 12 women; age 60 ± 12.5 years) with solid/cystic renal lesion diagnosed after MRI were included prospectively. Single-shot echo-planar DW abdominal MRI (1.5T) was obtained using seven b values with eight apparent diffusion coefficient (ADC) maps. Contrast-to-noise ratios (CNRs), signal intensities, lesion ADCs, and lesion/normal parenchyma ADC ratios were analyzed. Receiver-operating characteristic analysis was performed. Results: The mean signal intensities of malignant lesions (at b0, 50, and 200 s/mm 2 ) were significantly lower than those of benign lesions (P 2 . ADC with all b values could better distinguish between benign and malignant lesions. A 1.35 x 10 -3 mm 2 /s threshold ADC value permitted this distinction with 85.2% sensitivity and 65.6% specificity. The lesion/normal parenchyma ADC ratio was more effective than the lesion ADC. Conclusion: In addition to the ADC value, the signal intensity curve on DW images using multiple b values could be helpful for differentiation of malignant and benign renal lesions

The value of diffusion weighted imaging in differentiating intracranial tuberculomas from high-grade astrocytomas and metastases

International Nuclear Information System (INIS)

Peng Juan; Luo Tianyou; Lv Fajin; Fang Weidong; Wu Jingquan; Ouyang Yu; Li Yongmei

2007-01-01

Objective: To explore the value of diffusion weighted imaging (DWI) in differentiating intracranial tuberculomas from high-grade astrocytomas and metastases. Methods: The conventional MR imaging and DWI were performed in 50 eases (14 cases with intracranial tuberculomas, 15 cases with high- grade astrocytomas, and 21 cases with metastases) before treatment or operation. The mean apparent diffusion coefficient (ADC) values and relative apparent diffusion coefficient (rADC) values were calculated from the mass as well as from the peripheral edema regions of intracranial lesions. Results: The mean ADC values and rADC values were (1.2±0.2) x 10 -3 mm 2 ·s -1 and 1.6±0.3 in the mass of intracranial tuberculomas respectively; (0.8±0.1) x 10 -3 mm 2 ·s -1 and 1.1±0.1 in the parenehyma of high-grade astrocytomas; (0.8±0.1) x 10 -3 mm 2 ·s -1 and 1.0±0.2 in the parenchyma of metastases. There was significant difference of the mean ADC values (F=33.57, P -3 mm 2 ·s -1 and 2.5±0.2 in the peripheral edema regions of intracranial tuberculomas respectively; (1.4±0.2) x 10 -3 mm 2 ·s -1 and 1.8±0.3 in the peripheral edema regions of high-grade astrocytomas; and (1.9±0.2) x 10 -3 mm 2 ·s -1 and 2.3±0.5 in the peripheral edema regions of metastases. There was also significant difference in the mean ADC values (F23.17, P<0.01) or rADC values (F=5.94, P<0.01) among the peripheral edema regions of the three groups. Conclusion: The ADC values and rADC values are quite effective in differentiating intracranial tuberculoma from high-grade astrocytoma and metastasis. (authors)

Organohalogen diffuse contamination in Firenze and Prato groundwater bodies. investigative monitoring and definition of background values

Directory of Open Access Journals (Sweden)

Stefano Menichetti

2017-03-01

Full Text Available The experience of the Environmental Protection Agency of Tuscany in the determination of background values start from 2009 with various substances such as metals, non-metals and inorganic, dioxins and various matrices such as soil, groundwater, inland surface waters and coastal marine sediments. The methodologies supplied in literature have been interpreted and integrated to meet the requirements of current legislation and needs for remediation, diffuse pollution and excavated earth in specific areas. The method for diffuse pollution described here focuses on the use of statistical and geostatistical tools and what we present in this paper are some early results of interest obtained from two case studies in the Florence and in the Prato area. The study has been carried out on concentrations of tetrachlorethylene in the two groundwater bodies by identifying a number of frequency classes in the distribution. Each class has been hypothesized as corresponding to a distinct process. The occurrence both in space and time of the classes has been analysed and discussed critically concluding for a background value that has been found similar between the two zones. The investigation conducted on two monitoring stations representing hot-spots, with values in excess on background value has enabled to map spatial distribution of concentrations and to separate plumes from diffuse pollution area. The two areas show some peculiarities: Florence area shows advanced dehalogenation and a clear spatial continuity, whereas in Prato area it is limited with poor spatial continuity suggesting a spreading with vertical motions from still active primary or secondary sources. Observing how the methodological structure would require, to be fully predictive, a greater number of samples, however, the present work want to constitute a first contribution for management of areas subject to diffuse pollution.

The diagnostic value of high-frequency power-based diffusion-weighted imaging in prediction of neuroepithelial tumour grading

Energy Technology Data Exchange (ETDEWEB)

Chen, Zhiye; Liu, Mengqi [Chinese PLA General Hospital, Department of Radiology, Beijing (China); Hainan Branch of Chinese PLA General Hospital, Department of Radiology, Sanya (China); Zhou, Peng [Chinese Academy of Sciences, Research Center for Brain-inspired Intelligence, Institute of Automation, Beijing (China); University of Chinese Academy of Sciences, Beijing (China); Lv, Bin [Academy of Telecommunication Research of MIIT, Beijing (China); Wang, Yan; Wang, Yulin; Lou, Xin; Ma, Lin [Chinese PLA General Hospital, Department of Radiology, Beijing (China); Gui, Qiuping [Chinese PLA General Hospital, Department of Pathology, Beijing (China); He, Huiguang [Chinese Academy of Sciences, Research Center for Brain-inspired Intelligence, Institute of Automation, Beijing (China); University of Chinese Academy of Sciences, Beijing (China); Chinese Academy of Sciences, Center for Excellence in Brain Science and Intelligence Technology, Beijing (China)

2017-12-15

To retrospectively evaluate the diagnostic value of high-frequency power (HFP) compared with the minimum apparent diffusion coefficient (MinADC) in the prediction of neuroepithelial tumour grading. Diffusion-weighted imaging (DWI) data were acquired on 115 patients by a 3.0-T MRI system, which included b0 images and b1000 images over the whole brain in each patient. The HFP values and MinADC values were calculated by an in-house script written on the MATLAB platform. There was a significant difference among each group excluding grade I (G1) vs. grade II (G2) (P = 0.309) for HFP and among each group for MinADC. ROC analysis showed a higher discriminative accuracy between low-grade glioma (LGG) and high-grade glioma (HGG) for HFP with area under the curve (AUC) value 1 compared with that for MinADC with AUC 0.83 ± 0.04 and also demonstrated a higher discriminative ability among the G1-grade IV (G4) group for HFP compared with that for MinADC except G1 vs. G2. HFP could provide a simple and effective optimal tool for the prediction of neuroepithelial tumour grading based on diffusion-weighted images in routine clinical practice. (orig.)

[Diagnostic efficiency of decline rate of signal intensity and apparent diffusion coefficient with different b values for differentiating benign and malignant breast lesions on diffusion-weighted 3.0T magnetic resonance imaging].

Science.gov (United States)

Jiang, Jing; Liu, Wanhua; Ye, Yuanyuan; Wang, Rui; Li, Fengfang; Peng, Chengyu

2014-06-17

To investigate the diagnostic efficiency of decline rate of signal intensity and apparent diffusion coefficient with different b values for differentiating benign and malignant breast lesions on diffusion-weighted 3.0 T magnetic resonance imaging. A total of 152 patients with 162 confirmed histopathologically breast lesions (85 malignant and 77 benign) underwent 3.0 T diffusion-weighted magnetic resonance imaging. Four b values (0, 400, 800 and 1 000 s/mm²) were used. The signal intensity and ADC values of breast lesions were measured respectively. The signal intensity decline rate (SIDR) and apparent diffusion coefficient decline rate (ADCDR) were calculated respectively. SIDR = (signal intensity of lesions with low b value-signal intensity of lesions with high b value)/signal intensity of lesions with low b value, ADCDR = (ADC value of lesions with low b value-ADC value of lesions with high b value) /ADC value of lesions with low b value. The independent sample t-test was employed for statistical analyses and the receiver operating characteristic (ROC) curve for evaluating the diagnosis efficiency of SIDR and ADCDR values. Significant differences were observed in SIDR between benign and malignant breast lesions with b values of 0-400, 400-800 and 800-1 000 s/mm². The sensitivities of SIDR for differentiating benign and malignant breast lesions were 61.2%, 68.2% and 67.1%, the specificities 74.0%, 85.7% and 67.5%, the diagnosis accordance rates 67.3%, 76.5% and 67.3%, the positive predictive values 72.2%, 84.1% and 69.5% and the negative predictive values 63.3%, 71.0% and 65.0% respectively. Significant differences were observed in ADCDR between benign and malignant breast lesions with b values of 400-800 s/mm² and 800-1 000 s/mm². The sensitivities of SDR for differentiating benign and malignant breast lesions were 80.0% and 65.9%, the specificities 72.7% and 65.0%, the diagnostic accordance rates 76.5% and 65.4%, the positive predictive values 76.4% and 67

Exercise capacity in Dutch children : New reference values for the Bruce treadmill protocol

NARCIS (Netherlands)

M.H.M. van der Cammen-van Zijp (Monique); H.J.G. van den Berg-Emons (Rita); S.P. Willemsen (Sten); H.J. Stam (Henk); D. Tibboel (Dick); H. IJsselstijn (Hanneke)

2010-01-01

textabstractThe Bruce treadmill protocol is suitable for children 4 years of age and older. Dutch reference values were established in 1987. We considered that children's exercise capacity has deteriorated due to changes in physical activity patterns and eating habits. We determined new reference

Advantages of high b-value diffusion-weighted imaging to diagnose pseudo-responses in patients with recurrent glioma after bevacizumab treatment

International Nuclear Information System (INIS)

Yamasaki, Fumiyuki; Kurisu, Kaoru; Aoki, Tomokazu; Yamanaka, Masami; Kajiwara, Yoshinori; Watanabe, Yosuke; Takayasu, Takeshi; Akiyama, Yuji; Sugiyama, Kazuhiko

2012-01-01

Background: The diagnosis of pseudo-responses after bevacizumab treatment is difficult. Because diffusion-weighted imaging (DWI) is associated with cell density, it may facilitate the differentiation between true- and pseudo-responses. Furthermore, as high b-value DWI is even more sensitive to diffusion, it has been reported to be diagnostically useful in various clinical settings. Materials and methods: Between September 2008 and May 2011, 10 patients (5 males, 5 females; age range 6–65 years) with recurrent glioma were treated with bevacizumab. All underwent pre- and post-treatment MRI including T2- or FLAIR imaging, post-gadolinium contrast T1-weighted imaging, and DWI with b-1000 and b-4000. Response rates were evaluated by MacDonald- and by response assessment in neuro-oncology working group (RANO) criteria. We also assessed the response rate by calculating the size of high intensity areas using high b-value diffusion-weighted criteria. Prognostic factors were evaluated using Kaplan–Meier survival curves (log-rank test). Results: It was easier to identify pseudo-responses with RANO- than MacDonald criteria, however the reduction of edema by bevacizumab rendered the early diagnosis of tumor progression difficult by RANO criteria. In some patients with recurrent glioma treated with bevacizumab, high b-value diffusion-weighted criteria did, while MacDonald- and RANO criteria did not identify pseudo-responses at an early point after the start of therapy. Discussion and conclusion: High b-value DWI reflects cell density more accurately than regular b-value DWI. Our findings suggest that in patients with recurrent glioma, high b-value diffusion-weighted criteria are useful for the differentiation between pseudo- and true responses to treatment with bevacizumab

Advantages of high b-value diffusion-weighted imaging to diagnose pseudo-responses in patients with recurrent glioma after bevacizumab treatment.

Science.gov (United States)

Yamasaki, Fumiyuki; Kurisu, Kaoru; Aoki, Tomokazu; Yamanaka, Masami; Kajiwara, Yoshinori; Watanabe, Yosuke; Takayasu, Takeshi; Akiyama, Yuji; Sugiyama, Kazuhiko

2012-10-01

The diagnosis of pseudo-responses after bevacizumab treatment is difficult. Because diffusion-weighted imaging (DWI) is associated with cell density, it may facilitate the differentiation between true- and pseudo-responses. Furthermore, as high b-value DWI is even more sensitive to diffusion, it has been reported to be diagnostically useful in various clinical settings. Between September 2008 and May 2011, 10 patients (5 males, 5 females; age range 6-65 years) with recurrent glioma were treated with bevacizumab. All underwent pre- and post-treatment MRI including T2- or FLAIR imaging, post-gadolinium contrast T1-weighted imaging, and DWI with b-1000 and b-4000. Response rates were evaluated by MacDonald- and by response assessment in neuro-oncology working group (RANO) criteria. We also assessed the response rate by calculating the size of high intensity areas using high b-value diffusion-weighted criteria. Prognostic factors were evaluated using Kaplan-Meier survival curves (log-rank test). It was easier to identify pseudo-responses with RANO- than MacDonald criteria, however the reduction of edema by bevacizumab rendered the early diagnosis of tumor progression difficult by RANO criteria. In some patients with recurrent glioma treated with bevacizumab, high b-value diffusion-weighted criteria did, while MacDonald- and RANO criteria did not identify pseudo-responses at an early point after the start of therapy. High b-value DWI reflects cell density more accurately than regular b-value DWI. Our findings suggest that in patients with recurrent glioma, high b-value diffusion-weighted criteria are useful for the differentiation between pseudo- and true responses to treatment with bevacizumab. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Analysis of the utility of diffusion-weighted MRI and apparent diffusion coefficient values in distinguishing central nervous system toxoplasmosis from lymphoma

International Nuclear Information System (INIS)

Schroeder, Paul C.; Donovan Post, M. Judith; Bruce-Gregorios, Jocelyn; Oschatz, Elizabeth; Stadler, Alfred; Thurnher, Majda M.

2006-01-01

Toxoplasmosis and lymphoma are common lesions of the central nervous system in patients with AIDS. It is often difficult to distinguish between these lesions both clinically and radiographically. Previous research has demonstrated restricted diffusion within cerebral lymphomas and bacterial abscesses. However, little work has been done to evaluate the diffusion characteristics of toxoplasmosis lesions. This study was designed to explore further the utility of diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps and values in making the distinction between toxoplasmosis and lymphoma. The magnetic resonance imaging (MRI) studies of 36 patients, including 22 with toxoplasmosis (all of whom had AIDS) and 14 with lymphoma (8 of whom had AIDS), at two institutions were reviewed retrospectively. The characteristics of the lesions on DWI were evaluated, and the ADC ratios of the lesions were calculated and compared. There was significant overlap of the ADC ratios of toxoplasma and lymphoma, most notably in the intermediate (1.0-1.6) range. There was variability in ADC ratios even among different lesions in the same patient. In only a minority of the lymphoma patients were the ADC ratios low enough to suggest the correct diagnosis. Our study showed that toxoplasmosis exhibits a wide spectrum of diffusion characteristics with ADC ratios which have significant overlap with those of lymphoma. Therefore, in the majority of patients, ADC ratios are not definitive in making the distinction between toxoplasmosis and lymphoma. (orig.)

Analysis of the utility of diffusion-weighted MRI and apparent diffusion coefficient values in distinguishing central nervous system toxoplasmosis from lymphoma

Energy Technology Data Exchange (ETDEWEB)

Schroeder, Paul C.; Donovan Post, M. Judith; Bruce-Gregorios, Jocelyn [University of Miami, Jackson Memorial Hospital, Miami, FL (United States); Oschatz, Elizabeth; Stadler, Alfred; Thurnher, Majda M. [Medical University of Vienna, Department of Radiology Neuroradiology Section, Vienna (Austria)

2006-10-15

Toxoplasmosis and lymphoma are common lesions of the central nervous system in patients with AIDS. It is often difficult to distinguish between these lesions both clinically and radiographically. Previous research has demonstrated restricted diffusion within cerebral lymphomas and bacterial abscesses. However, little work has been done to evaluate the diffusion characteristics of toxoplasmosis lesions. This study was designed to explore further the utility of diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps and values in making the distinction between toxoplasmosis and lymphoma. The magnetic resonance imaging (MRI) studies of 36 patients, including 22 with toxoplasmosis (all of whom had AIDS) and 14 with lymphoma (8 of whom had AIDS), at two institutions were reviewed retrospectively. The characteristics of the lesions on DWI were evaluated, and the ADC ratios of the lesions were calculated and compared. There was significant overlap of the ADC ratios of toxoplasma and lymphoma, most notably in the intermediate (1.0-1.6) range. There was variability in ADC ratios even among different lesions in the same patient. In only a minority of the lymphoma patients were the ADC ratios low enough to suggest the correct diagnosis. Our study showed that toxoplasmosis exhibits a wide spectrum of diffusion characteristics with ADC ratios which have significant overlap with those of lymphoma. Therefore, in the majority of patients, ADC ratios are not definitive in making the distinction between toxoplasmosis and lymphoma. (orig.)

Apparent diffusion coefficient values of diffusion-weighted imaging for distinguishing focal pulmonary lesions and characterizing the subtype of lung cancer: a meta-analysis

Energy Technology Data Exchange (ETDEWEB)

Shen, Guohua; Jia, Zhiyun; Deng, Houfu [Sichuan University, Department of Nuclear Medicine, West China Hospital, Chengdu, Sichuan (China)

2016-02-15

The potential performance of apparent diffusion coefficient (ADC) values for distinguishing malignant and benign pulmonary lesions, further characterizing the subtype of lung cancer was assessed. PubMed, EMBASE, Cochrane Library, EBSCO, and three Chinese databases were searched to identify eligible studies on diffusion-weighted imaging (DWI) of focal pulmonary lesions. ADC values of malignant and benign lesions were extracted by lesion type and statistically pooled based on a linear mixed model. Further analysis for subtype of lung cancer was also performed. The methodological quality was assessed using the quality assessment of diagnostic accuracy studies tool. Thirty-four articles involving 2086 patients were included. Malignant pulmonary lesions have significantly lower ADC values than benign lesions [1.21 (95 % CI, 1.19-1.22) mm{sup 2}/s vs. 1.76 (95 % CI, 1.72-1.80) mm{sup 2}/s; P < 0.05]. There is a significant difference between ADC values of small cell lung cancer and non-small cell lung cancer (P < 0.05), while the differences were not significant among histological subtypes of lung cancer. The methodological quality was relatively high, and the data points from Begg's test indicated that there was probably no obvious publication bias. The ADC value is helpful for distinguishing malignant and benign pulmonary lesions and provides a promising method for differentiation of SCLC from NSCLC. (orig.)

Prognostic value of diffusion-weighted imaging summation scores or apparent diffusion coefficient maps in newborns with hypoxic-ischemic encephalopathy

International Nuclear Information System (INIS)

Cavalleri, Francesca; Todeschini, Alessandra; Lugli, Licia; Pugliese, Marisa; Della Casa, Elisa; Gallo, Claudio; Frassoldati, Rossella; Ferrari, Fabrizio; D'Amico, Roberto

2014-01-01

The diagnostic and prognostic assessment of newborn infants with hypoxic-ischemic encephalopathy (HIE) comprises, among other tools, diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps. To compare the ability of DWI and ADC maps in newborns with HIE to predict the neurodevelopmental outcome at 2 years of age. Thirty-four term newborns with HIE admitted to the Neonatal Intensive Care Unit of Modena University Hospital from 2004 to 2008 were consecutively enrolled in the study. All newborns received EEG, conventional MRI and DWI within the first week of life. DWI was analyzed by means of summation (S) score and regional ADC measurements. Neurodevelopmental outcome was assessed with a standard 1-4 scale and the Griffiths Mental Developmental Scales - Revised (GMDS-R). When the outcome was evaluated with a standard 1-4 scale, the DWI S scores showed very high area under the curve (AUC) (0.89) whereas regional ADC measurements in specific subregions had relatively modest predictive value. The lentiform nucleus was the region with the highest AUC (0.78). When GMDS-R were considered, DWI S scores were good to excellent predictors for some GMDS-R subscales. The predictive value of ADC measurements was both region- and subscale-specific. In particular, ADC measurements in some regions (basal ganglia, white matter or rolandic cortex) were excellent predictors for specific GMDS-R with AUCs up to 0.93. DWI S scores showed the highest prognostic value for the neurological outcome at 2 years of age. Regional ADC measurements in specific subregions proved to be highly prognostic for specific neurodevelopmental outcomes. (orig.)

Prognostic value of diffusion-weighted imaging summation scores or apparent diffusion coefficient maps in newborns with hypoxic-ischemic encephalopathy

Energy Technology Data Exchange (ETDEWEB)

Cavalleri, Francesca; Todeschini, Alessandra [Azienda Unita Sanitaria Locale di Modena, Neuroradiology Unit, Department of Neuroscience, Nuovo Ospedale Civile S. Agostino Estense di Modena, Modena (Italy); Lugli, Licia; Pugliese, Marisa; Della Casa, Elisa; Gallo, Claudio; Frassoldati, Rossella; Ferrari, Fabrizio [Modena University Hospital, Institute of Pediatrics and Neonatal Medicine and NICU, Modena (Italy); D' Amico, Roberto [University of Modena and Reggio Emilia, Department of Clinical and Diagnostic Medicine and Public Health, Modena (Italy)

2014-09-15

The diagnostic and prognostic assessment of newborn infants with hypoxic-ischemic encephalopathy (HIE) comprises, among other tools, diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps. To compare the ability of DWI and ADC maps in newborns with HIE to predict the neurodevelopmental outcome at 2 years of age. Thirty-four term newborns with HIE admitted to the Neonatal Intensive Care Unit of Modena University Hospital from 2004 to 2008 were consecutively enrolled in the study. All newborns received EEG, conventional MRI and DWI within the first week of life. DWI was analyzed by means of summation (S) score and regional ADC measurements. Neurodevelopmental outcome was assessed with a standard 1-4 scale and the Griffiths Mental Developmental Scales - Revised (GMDS-R). When the outcome was evaluated with a standard 1-4 scale, the DWI S scores showed very high area under the curve (AUC) (0.89) whereas regional ADC measurements in specific subregions had relatively modest predictive value. The lentiform nucleus was the region with the highest AUC (0.78). When GMDS-R were considered, DWI S scores were good to excellent predictors for some GMDS-R subscales. The predictive value of ADC measurements was both region- and subscale-specific. In particular, ADC measurements in some regions (basal ganglia, white matter or rolandic cortex) were excellent predictors for specific GMDS-R with AUCs up to 0.93. DWI S scores showed the highest prognostic value for the neurological outcome at 2 years of age. Regional ADC measurements in specific subregions proved to be highly prognostic for specific neurodevelopmental outcomes. (orig.)

Prognostic value of diffusion-weighted imaging summation scores or apparent diffusion coefficient maps in newborns with hypoxic-ischemic encephalopathy.

Science.gov (United States)

Cavalleri, Francesca; Lugli, Licia; Pugliese, Marisa; D'Amico, Roberto; Todeschini, Alessandra; Della Casa, Elisa; Gallo, Claudio; Frassoldati, Rossella; Ferrari, Fabrizio

2014-09-01

The diagnostic and prognostic assessment of newborn infants with hypoxic-ischemic encephalopathy (HIE) comprises, among other tools, diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps. To compare the ability of DWI and ADC maps in newborns with HIE to predict the neurodevelopmental outcome at 2 years of age. Thirty-four term newborns with HIE admitted to the Neonatal Intensive Care Unit of Modena University Hospital from 2004 to 2008 were consecutively enrolled in the study. All newborns received EEG, conventional MRI and DWI within the first week of life. DWI was analyzed by means of summation (S) score and regional ADC measurements. Neurodevelopmental outcome was assessed with a standard 1-4 scale and the Griffiths Mental Developmental Scales - Revised (GMDS-R). When the outcome was evaluated with a standard 1-4 scale, the DWI S scores showed very high area under the curve (AUC) (0.89) whereas regional ADC measurements in specific subregions had relatively modest predictive value. The lentiform nucleus was the region with the highest AUC (0.78). When GMDS-R were considered, DWI S scores were good to excellent predictors for some GMDS-R subscales. The predictive value of ADC measurements was both region- and subscale-specific. In particular, ADC measurements in some regions (basal ganglia, white matter or rolandic cortex) were excellent predictors for specific GMDS-R with AUCs up to 0.93. DWI S scores showed the highest prognostic value for the neurological outcome at 2 years of age. Regional ADC measurements in specific subregions proved to be highly prognostic for specific neurodevelopmental outcomes.

Risk of COPD with obstruction in active smokers with normal spirometry and reduced diffusion capacity.

Science.gov (United States)

Harvey, Ben-Gary; Strulovici-Barel, Yael; Kaner, Robert J; Sanders, Abraham; Vincent, Thomas L; Mezey, Jason G; Crystal, Ronald G

2015-12-01

Smokers are assessed for chronic obstructive pulmonary disease (COPD) using spirometry, with COPD defined by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) as airflow limitation that is not fully reversible with bronchodilators. There is a subset of smokers with normal spirometry (by GOLD criteria), who have a low diffusing capacity of the lung for carbon monoxide (DLCO), a parameter linked to emphysema and small airway disease. The natural history of these "normal spirometry/low DLCO" smokers is unknown.From a cohort of 1570 smokers in the New York City metropolitian area, all of whom had normal spirometry, two groups were randomly selected for lung function follow-up: smokers with normal spirometry/normal DLCO (n=59) and smokers with normal spirometry/low DLCO (n=46). All had normal history, physical examination, complete blood count, urinalysis, HIV status, α1-antitrypsin level, chest radiography, forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), FEV1/FVC ratio and total lung capacity. Throughout the study, all continued to be active smokers.In the normal spirometry/normal DLCO group assessed over 45±20 months, 3% developed GOLD-defined COPD. In contrast, in the normal spirometry/low DLCO group, followed over 41±31 months, 22% developed GOLD-defined COPD.Despite appearing "normal" according to GOLD, smokers with normal spirometry but low DLCO are at significant risk of developing COPD with obstruction to airflow. Copyright ©ERS 2015.

Increased P diffusion as an explanation of increased P availability in flooded rice soils

International Nuclear Information System (INIS)

Turner, F.T.; Gilliam, J.W.

1976-01-01

Phosphorus supply factors (capacity, kinetic, intensity, and diffusivity) and plant growth were the approaches used to assess P supply of flooded rice soils. Increases in the capacity, intensity and kinetic factors, as measured by E-value, solution P concentration, and soil P release rate to a distilled water 'sink' respectively, were unpronounced and infrequent upon water-saturation of ten soils. However, increases in the diffusivity factor, as measured by 32 P diffusion coefficients, were at least ten-fold as soil moisture increased. The greatest increases in P diffusion occurred as soil moisture increased beyond one-third bar. Using a P-fertilized soil or P treated powdered cellulose as the P source and a minus P nutrient solution to nourish a split root system with water and nutrients, data were obtained which suggested that P uptake and rice shoot growth (indicators of P availability) increased with increasing moisture level. Phosphorus uptake and rice-shoot growth were greatest when the soil or P treated cellulose were water-saturated. These data indicate that increased soil P availability upon flooding can be attributed to an increase in the diffusivity factor

Electrochemical Effect of Different Modified Glassy Carbon Electrodes on the Values of Diffusion Coefficient for Some Heavy Metal Ions

International Nuclear Information System (INIS)

Radhi, M M; Alwan, S H; Amir, Y K A; Tee, T W

2013-01-01

Glassy carbon electrode (GCE) was modified with carbon nanotubes (CNT), C 60 and activated carbon (AC) by mechanical attachment method and solution evaporation technique to preparation CNT/GCE, C 60 /GCE and AC/GCE, these electrodes were modified in Li + solution via cyclic voltammetry (CV) potential cycling to preparing CNT/Li + /GCE, C 60 /Li + /GCE and AC/Li + /GCE. The sensing characteristics of the modified film electrodes, demonstrated in the application study for different heavy metal ions such as Hg 2+ , Cd 2+ , and Mn 2+ . Cyclic voltammetric effect by chronoamperometry (CA) technique was investigated to determination the diffusion coefficient (D f ) values from Cottrell equation at these ions. Based on Cottrell equation (diffusion coefficient) of the redox current peaks of different heavy metal ions at different modified electrodes were studied to evaluate the sensing of these electrodes by the diffusion coefficient values. The modification of GCE with nano materials and Li + act an enhancement for the redox current peaks to observe that the diffusion process are high at CNT/Li + /GCE, C 60 /Li + /GCE and AC/Li+/GCE, but it has low values at unmodified GCE.

Study of apparent diffusion coefficient value in the normal breastq

International Nuclear Information System (INIS)

Cai Shifeng

2007-01-01

Objective: To investigate the differences of apparent diffusion coefficient (ADC) value in normal breasts and to evaluate the correlation between ADC value and corresponding histology. Methods: Sixty-two normal breasts including 42 normal breasts of 42 patients with unilateral lesions and 20 normal breasts of 10 volunteers were studied. The ADC value of all 62 normal breasts were calculated when b value was given from 1000 to 0 s/mm 2 , 1000 to 500 s/mm 2 and 500 to 0 s/mm 2 . The MRI features of 60 normal breasts were classified into 3 types (dense, lobular-speckled, degenerative types) according to Wolf's classification and histology. Results: DWI and ADC images were different in 3 types of normal breasts because of different histologic structures. The mean ADC value of the dense type breasts was (1.70 ± 0.37) x 10 -3 mm 2 /s, the lobular-speckled type was (1.93 ± 0.46) x 10 -3 mm 2 /s and the degenerative type was (1.18 ± 0.65) x 10 -3 mm 2 /s (F=12.998, P=0.000). There were no significant differences between the dense type and the lobular-speckled type (F=2.167, P=0.147), but significant differences between the dense type and the degenerative type, the lobular-speckled type and the degenerate type (F=5.593 and 19.128; P=0.029 and 0.000). When b value decreased, the ADC value of the dense type and the lobular-speckled type increased correspondingly, but the degenerative type didn't increase apparently. Conclusion: ADC value was influenced by histologic structures in normal breasts and also was influenced by b value in the dense type and lobular-speckled type breasts. (authors)

[Value of intravoxel incoherent motion diffusion-weighted imaging in differential diagnosis of benign and malignant hepatic lesions and blood perfusion evaluation].

Science.gov (United States)

Ying, M L; Xiao, W W; Xu, S L; Shu, J E; Pan, J F; Fu, J F; Lu, J H; Pan, Y H; Jiang, Y

2016-11-20

Objective: To investigate the value of intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) in the differential diagnosis and blood perfusion evaluation of benign and malignant hepatic lesions. Methods: A retrospective analysis was performed for 86 patients (96 lesions) with pathologically or clinically confirmed hepatic lesions or hepatic lesions diagnosed based on follow-up results, among whom 48 had malignant lesions (53 lesions) and 38 had benign lesions (43 lesions). The patients underwent conventional magnetic resonance (MR) plain scan, contrast-enhanced scan, and diffusion-weighted imaging (DWI) with different b values (b = 0, 50, 100, 150, 200, 400, 600, 800, 1 000, and 1 200 s/mm 2 ) to determine the parameters of the double exponential model for intravoxel incoherent motion (IVIM): fast diffusion coefficient Dfast, slow diffusion coefficient Dslow, and percentage of fast-diffusion constituent F value. The patients were divided into groups according to the blood supply to lesions on conventional MR plain scan and contrast-enhanced scan, and there were 47 lesions in abundant blood supply group and 49 in poor blood supply group. The data for analysis were Dfast, Dslow, and F values of benign/malignant lesion groups and abundant/poor blood supply groups. The independent samples t-test was used for statistical analysis; the independent samples non-parametric test Mann-Whitney U test was used for the comparison of F value; the receiver operating characteristic (ROC) curve was used to evaluate the value of above parameters in the differentiation of benign and malignant lesions and blood supply evaluation. Results: Compared with the malignant lesion group, the benign lesion group had significantly higher Dslow, and F values ( P benign and malignant hepatic lesions, and F value can show blood perfusion in benign and malignant hepatic lesions without the need for contrast-enhanced scan, which provides a reference for the qualitative diagnosis of liver

Initial Experience of 3-Tesla Apparent Diffusion Coefficient Values in Characterizing Squamous Cell Carcinomas of the Head and Neck

International Nuclear Information System (INIS)

Srinivasan, A.; Dvorak, R.; Rohrer, S.; Mukherji, S.K.

2008-01-01

Background: With the increased clinical use of 3-Tesla (3T) magnets, it becomes important to identify the potential applications of advanced magnetic resonance (MR) imaging techniques such as diffusion-weighted imaging in head and neck pathologies. Purpose: To establish the 3T apparent diffusion coefficient (ADC) values for normal neck structures, and to examine the utility of ADC values in distinguishing head and neck squamous cell carcinomas (HNSCC) from normal neck anatomy. Material and Methods: 3T diffusion-weighted imaging was performed on 10 normal volunteers and 10 patients with known HNSCC. In the volunteers, mean ADC was calculated in the parotid gland, submandibular gland, base of the tongue, pterygoid muscle, masseter muscle, paraspinal muscles, true vocal cord, thyroid gland, thyroid cartilage, cricoid cartilage, and lymph nodes. The mean tumor ADC value was calculated from the 10 patients with HNSCC and compared with the normal ADC values from various neck structures. Results: The mean ADC value measured in the HNSCC was 1.101 (±0.214)x10 -3 mm 2 /s. This was significantly lower than ADC values of paraspinal muscles, pterygoid muscle, masseter muscle, thyroid gland, and base of the tongue (P=0.0006, 0.0002, 0.0001, 0.001, and 0.002, respectively). The tumor ADC values were not significantly different from ADC values of parotid and submandibular glands (P=0.057 and 0.14, respectively). Conclusion: 3T ADC values show potential for distinguishing HNSCC from normal extracranial head and neck structures

Initial Experience of 3-Tesla Apparent Diffusion Coefficient Values in Characterizing Squamous Cell Carcinomas of the Head and Neck

Energy Technology Data Exchange (ETDEWEB)

Srinivasan, A.; Dvorak, R.; Rohrer, S.; Mukherji, S.K. (Dept. of Radiology, Division of Neuroradiology, Univ. of Michigan Health System, Ann Arbor, MI (United States))

2008-11-15

Background: With the increased clinical use of 3-Tesla (3T) magnets, it becomes important to identify the potential applications of advanced magnetic resonance (MR) imaging techniques such as diffusion-weighted imaging in head and neck pathologies. Purpose: To establish the 3T apparent diffusion coefficient (ADC) values for normal neck structures, and to examine the utility of ADC values in distinguishing head and neck squamous cell carcinomas (HNSCC) from normal neck anatomy. Material and Methods: 3T diffusion-weighted imaging was performed on 10 normal volunteers and 10 patients with known HNSCC. In the volunteers, mean ADC was calculated in the parotid gland, submandibular gland, base of the tongue, pterygoid muscle, masseter muscle, paraspinal muscles, true vocal cord, thyroid gland, thyroid cartilage, cricoid cartilage, and lymph nodes. The mean tumor ADC value was calculated from the 10 patients with HNSCC and compared with the normal ADC values from various neck structures. Results: The mean ADC value measured in the HNSCC was 1.101 (+-0.214)x10-3mm2/s. This was significantly lower than ADC values of paraspinal muscles, pterygoid muscle, masseter muscle, thyroid gland, and base of the tongue (P=0.0006, 0.0002, 0.0001, 0.001, and 0.002, respectively). The tumor ADC values were not significantly different from ADC values of parotid and submandibular glands (P=0.057 and 0.14, respectively). Conclusion: 3T ADC values show potential for distinguishing HNSCC from normal extracranial head and neck structures

Utility of Diffusion Weighted Magnetic Resonance Imaging with Multiple B Values in Evaluation of Pancreatic Malignant and Benign Lesions and Pancreatitis.

Science.gov (United States)

Karadeli, Elif; Erbay, Gurcan; Parlakgumus, Alper; Koc, Zafer

2018-02-01

To determine the feasibility of diffusion-weighted imaging in evaluation of pancreatic lesions and in differentiation of benign from malignant lesions. Descriptive study. Baskent University Adana Teaching and Research Center, Adana, Turkey, between September 2013 and May 2015. Forty-three lesions [pancreas adenocarcinoma (n=25)], pancreatitis (n=10), benign lesion (n=8)] were utilized with diffusion-weighted magnetic resonance imaging with multiple b-values. Different ADC maps of diffusion weighted images by using b-values were acquired. The median ADC at all b values for malignant lesions was significantly different from that for benign lesions (pvalues were compared between benign lesions/normal parenchyma and malignant lesions/normal parenchyma, there was a significant statistical difference in all b values between benign and malignant lesions except at b 50 and b 200 (pvalue (AUC=0.804) was more effective than the lesion ADC for b 600 value (AUC=0.766) in differentiation of benign and malignant lesions. The specificity and sensitivity of the lesion/normal parenchyma ADC ratio were higher than those of ADC values of lesions. When the ADC was compared between benign lesions and pancreatitis, a significant difference was found at all b values (pvalue combinations (p>0.05). Diffusion-weighted magnetic resonance images can be helpful in differentiation of pancreatic carcinoma and benign lesions. Lesion ADC / normal parenchyma ADC ratios are more important than lesion ADC values in assessment of pancreatic lesions.

Diffusion Profiles of Health Beneficial Components from Goji Berry (Lyceum barbarum Marinated in Alcohol and Their Antioxidant Capacities as Affected by Alcohol Concentration and Steeping Time

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Yang Song

2013-01-01

Full Text Available The fruit (goji berry of Lycium barbarum, a traditional Chinese medicine, has been widely used in health diets due to its potential role in the prevention of chronic diseases. One of the most popular applications of goji berry is to make goji wine in China by steeping goji berry in grain liquor. However, how the steeping process affects antioxidant capacities and phytochemicals of goji berry is not yet fully understood. Therefore, to provide scientific data for the utilization of goji berry in the nutraceutical industry, the diffusion rate of betaine, β-carotene, phenolic compounds in goji berry and their antioxidant capacities affected by alcohol concentration and steeping time were determined by UV-Visible spectrophotometer. The results showed that low alcohol concentration (15% or 25% would promote the diffusion of betaine and increase antioxidant activity, while high concentration (55% or 65% would generally increase the diffusion of flavonoids and reduce antioxidant activity. The steeping time had no significant effect on the diffusion of phenolic compounds and antioxidant activities. However, all goji berry wine steeped for 14 days with different alcohol concentrations exhibited the highest betaine concentration. Current findings provide useful information for the nutraceutical industries to choose proper steeping time and alcohol concentration to yield desired health promotion components from goji.

Diffusion Profiles of Health Beneficial Components from Goji Berry (Lyceum barbarum) Marinated in Alcohol and Their Antioxidant Capacities as Affected by Alcohol Concentration and Steeping Time

Science.gov (United States)

Song, Yang; Xu, Baojun

2013-01-01

The fruit (goji berry) of Lycium barbarum, a traditional Chinese medicine, has been widely used in health diets due to its potential role in the prevention of chronic diseases. One of the most popular applications of goji berry is to make goji wine in China by steeping goji berry in grain liquor. However, how the steeping process affects antioxidant capacities and phytochemicals of goji berry is not yet fully understood. Therefore, to provide scientific data for the utilization of goji berry in the nutraceutical industry, the diffusion rate of betaine, β-carotene, phenolic compounds in goji berry and their antioxidant capacities affected by alcohol concentration and steeping time were determined by UV-Visible spectrophotometer. The results showed that low alcohol concentration (15% or 25%) would promote the diffusion of betaine and increase antioxidant activity, while high concentration (55% or 65%) would generally increase the diffusion of flavonoids and reduce antioxidant activity. The steeping time had no significant effect on the diffusion of phenolic compounds and antioxidant activities. However, all goji berry wine steeped for 14 days with different alcohol concentrations exhibited the highest betaine concentration. Current findings provide useful information for the nutraceutical industries to choose proper steeping time and alcohol concentration to yield desired health promotion components from goji. PMID:28239094

Usefulness of Diffusion-Weighted MR Imaging for Breast Lesions: Comparing the Apparent Diffusion Coefficient (ADC) Values and the Pathologic Results

International Nuclear Information System (INIS)

Ahn, Hye Shin; Chang, Yun Woo; Choi, Kyung Hee; Kim, Hyun Joo; Hong, Seong Suk; Hwang, Jung Hwa; Kwon, Kui Hyang; Kim, Yong Bae

2011-01-01

We wanted to evaluate the ability of the apparent diffusion coefficient (ADC) values to differentiate between benign and malignant breast lesions and the normal breast parenchyma. We used breast MRI, including DWI, to obtain images of 167 breast lesions (18 benign lesions and 149 malignant lesions) of 152 women (mean age: 48.6 years, range: 24-80 years). The mean ADC values of the malignant lesions were compared to those of the benign lesions and the normal parenchyma. We compared the ADC values of IDC, DCIS and other types of breast cancer and we also compared the ADC values with the nuclear grade of IDC. The mean ADC values of the malignant lesions were lower than those of the benign lesions and the normal parenchyma (p -3 mm 2 /s for discriminating between malignant and benign lesion showed a specificity of 53% and a sensitivity of 100%, and the ADC threshold value of 1.33 X 10 -3 mm 2 /s showed a specificity of 93% and a sensitivity of 94% for discriminating between malignant and benign lesion.

Transport and calorimetric properties of AISI 321 by pulse thermal diffusivity and calorimetric techniques

International Nuclear Information System (INIS)

Perovic, N.L.; Maglic, K.D.; Stanimirovic, A.M.; Vukovic, G.S.

1995-01-01

The study of the thermophysical properties of AISI 321 stainless steel was the last part of work within the IAEA-coordinated Research Programme for the Establishment of a Database of Thermophysical Properties of LW and HW Reactor Materials (IAEA CRP) effected at the Institute of Nuclear Sciences Vinca (NIV). The AISI 321 stainless steel belongs to the group of construction materials whose thermophysical and calorimetric properties have significance for the IAEA CRP. Because there have been few investigations of the thermal properties of this material, the CRP foresaw the need for new measurements, which are reported in this paper. Experimental research performed at NIV consisted of the investigation of thermal diffusivity, electric resistivity, and specific heat capacity of this austenitic stainless steel. The thermal diffusivity was measured by the laser pulse technique, and the elastic resistivity and specific heat capacity were determined by use of millisecond-resolution pulse calorimetry. All measurements were performed from ambient temperature to above 1000 o C, within which temperature range the material maintains its structure and stable thermophysical properties. Values for the thermal conductivity were computed from data on the thermal diffusivity, specific heat capacity, and the room-temperature density. (author)

Improved Correction of IR Loss in Diffuse Shortwave Measurements: An ARM Value-Added Product

Energy Technology Data Exchange (ETDEWEB)

Younkin, K; Long, CN

2003-11-01

Simple single black detector pyranometers, such as the Eppley Precision Spectral Pyranometer (PSP) used by the Atmospheric Radiation Measurement (ARM) Program, are known to lose energy via infrared (IR) emission to the sky. This is especially a problem when making clear-sky diffuse shortwave (SW) measurements, which are inherently of low magnitude and suffer the greatest IR loss. Dutton et al. (2001) proposed a technique using information from collocated pyrgeometers to help compensate for this IR loss. The technique uses an empirically derived relationship between the pyrgeometer detector data (and alternatively the detector data plus the difference between the pyrgeometer case and dome temperatures) and the nighttime pyranometer IR loss data. This relationship is then used to apply a correction to the diffuse SW data during daylight hours. We developed an ARM value-added product (VAP) called the SW DIFF CORR 1DUTT VAP to apply the Dutton et al. correction technique to ARM PSP diffuse SW measurements.

The effect of thickness in the through-diffusion experiment. Final report

International Nuclear Information System (INIS)

Valkiainen, M.; Aalto, H.; Lehikoinen, J.; Uusheimo, K.

1996-01-01

The report contains an experimental study of diffusion in the water-filled pores of rock samples. The samples studied are rapakivi granite from Loviisa, southern Finland. The drill-core sample was sectioned perpendicularly with a diamond saw and three cylindrical samples were obtained. The nominal thicknesses (heights of the cylinders) are 2, 4 and 6 cm. For the diffusion measurement the sample holders were pressed between two chambers. One of the chambers was filled with 0.0044 molar sodium chloride solution spiked with tracers. Another chamber was filled with inactive solution. Tritium (HTO) considered to be a water equivalent tracer and anionic 36 Cl - were used as tracers. The through diffusion was monitored about 1000 days after which time the diffusion cells were emptied and the sample holders dismantled. The samples were sectioned into 1 cm slices and the tracers were leached from the slices. The porosities of the slices were determined by the weighing method. The rock-capacity factors could be determined from the leaching results obtained. It was seen that the porosity values were in accordance with the rock capacity factors obtained with HTO. An anion exclusion can be seen comparing the results obtained with HTO and 36 Cl - . The concentration profile through even the thickest sample had reached a constant slope and the rate of diffusion was practically at a steady state. An anion exclusion effect was also seen in the effective diffusion coefficients. The effect of thickness on diffusion shows that the connectivity of the pores decreases in the thickness range 2-4 cm studied. The decrease as reflected in the diffusion coefficient was not dramatic and it can be said that especially for studying chemical interactions during diffusion, the thickness of 2 cm is adequate. (orig.) (12 refs.)

Prognostic value of brain proton MR spectroscopy and diffusion tensor imaging in newborns with hypoxic-ischemic encephalopathy treated by brain cooling

International Nuclear Information System (INIS)

Ancora, G.; Testa, C.; Tonon, C.; Manners, D.N.; Gramegna, L.L.; Lodi, R.; Grandi, S.; Sbravati, F.; Savini, S.; Corvaglia, L.T.; Faldella, G.; Tani, G.; Malucelli, E.

2013-01-01

MRI, proton magnetic resonance spectroscopy ( 1 H-MRS), and diffusion tensor imaging (DTI) have been shown to be of great prognostic value in term newborns with moderate-severe hypoxic-ischemic encephalopathy (HIE). Currently, no data are available on 1 H-MRS and DTI performed in the subacute phase after hypothermic treatment. The aim of the present study was to assess their prognostic value in newborns affected by moderate-severe HIE and treated with selective brain cooling (BC). Twenty infants treated with BC underwent conventional MRI and 1 H-MRS at a mean (SD) age of 8.3 (2.8) days; 15 also underwent DTI. Peak area ratios of metabolites and DTI variables, namely mean diffusivity (MD), axial and radial diffusivity, and fractional anisotropy (FA), were calculated. Clinical outcome was monitored until 2 years of age. Adverse outcome was observed in 6/20 newborns. Both 1 H-MRS and DTI variables showed higher prognostic accuracy than conventional MRI. N-acetylaspartate/creatine at a basal ganglia localisation showed 100 % PPV and 93 % NPV for outcome. MD showed significantly decreased values in many regions of white and gray matter, axial diffusivity showed the best predictive value (PPV and NPV) in the genu of corpus callosum (100 and 91 %, respectively), and radial diffusivity was significantly decreased in fronto white matter (FWM) and fronto parietal (FP) WM. The decrement of FA showed the best AUC (0.94) in the FPWM. Selective BC in HIE neonates does not affect the early and accurate prognostic value of 1 H-MRS and DTI, which outperform conventional MRI. (orig.)

Signal intensity changes of normal brain at varying high b-value diffusion-weighted images using 3.0T MR scanner

International Nuclear Information System (INIS)

Lee, Jin Hee; Sohn, Chul Ho; Choi, Jin Soo

2003-01-01

Using diffusion-weighted MR imaging (DWI), to evaluate the signal intensity characteristics of normal adult brain as diffusion gradient strength (b value) increases from 1,000 to 3,000 s/mm 2 . Twenty-one healthy volunteers with neither neurologic symptoms nor pathologic findings at axial and sagittal T2-weighted MR imaging were involved in this study. All images were obtained with a 3.0T MR scanner. Six sets of spin-echo echo-planar images were acquired in the axial plane using progressively increasing strengths of diffusion-sensitizing gradients (corresponding to b values of 0, 1,000, 1,500, 2,000, 2,500, and 3,000 s/mm 2 ). All imaging parameters other than TE remained constant. Changes in normal white-gray matter signal intensity observed at variable b-value DWI were qualitatively analysed, and the signal-to-noise ratios (SNRs) in six anatomic regions (frontal and parietal white matter, genu and splenium corporis callosi, the posterior limb of the internal capsule, and the thalamus) quantitatively, and the ratios were averaged and compared with the average SNR of 1,000 s/mm DWI. As gradient strength increased from 1,000 to 3,000 s/mm 2 , both gray-and white-matter structures diminished in signal intensity, and images obtained at a b value of 3,000 s/mm 2 appeared very noisy. White matter became progressively hyperintense to gray matter as the diffusion sensitizing gradient increased, especially at the centrum semiovale, the posterior limb of the internal capsule, and the splenium corporis callosi, but the genu corporis callosi; showed exceptional intermediate low signal intensity. At quantitative assessment, the signal-to-noise ratio decreased as the diffusion sensitizing gradient increased. Relative to the images obtained at a b value of 1,000 s/mm 2 , average SNRs were 0.71 (b=1,500 s/mm 2 ), 0.52 (b=2,000 s/mm 2 ), 0.41 (b=2,500 s/mm 2 ), 0.33 (b=3,000 s/mm 2 ). As the diffusion sensitizing gradient increased, the signal-to-noise ratio of brain structures

Emphysema Distribution and Diffusion Capacity Predict Emphysema Progression in Human Immunodeficiency Virus Infection

Science.gov (United States)

Leung, Janice M; Malagoli, Andrea; Santoro, Antonella; Besutti, Giulia; Ligabue, Guido; Scaglioni, Riccardo; Dai, Darlene; Hague, Cameron; Leipsic, Jonathon; Sin, Don D.; Man, SF Paul; Guaraldi, Giovanni

2016-01-01

Background Chronic obstructive pulmonary disease (COPD) and emphysema are common amongst patients with human immunodeficiency virus (HIV). We sought to determine the clinical factors that are associated with emphysema progression in HIV. Methods 345 HIV-infected patients enrolled in an outpatient HIV metabolic clinic with ≥2 chest computed tomography scans made up the study cohort. Images were qualitatively scored for emphysema based on percentage involvement of the lung. Emphysema progression was defined as any increase in emphysema score over the study period. Univariate analyses of clinical, respiratory, and laboratory data, as well as multivariable logistic regression models, were performed to determine clinical features significantly associated with emphysema progression. Results 17.4% of the cohort were emphysema progressors. Emphysema progression was most strongly associated with having a low baseline diffusion capacity of carbon monoxide (DLCO) and having combination centrilobular and paraseptal emphysema distribution. In adjusted models, the odds ratio (OR) for emphysema progression for every 10% increase in DLCO percent predicted was 0.58 (95% confidence interval [CI] 0.41–0.81). The equivalent OR (95% CI) for centrilobular and paraseptal emphysema distribution was 10.60 (2.93–48.98). Together, these variables had an area under the curve (AUC) statistic of 0.85 for predicting emphysema progression. This was an improvement over the performance of spirometry (forced expiratory volume in 1 second to forced vital capacity ratio), which predicted emphysema progression with an AUC of only 0.65. Conclusion Combined paraseptal and centrilobular emphysema distribution and low DLCO could identify HIV patients who may experience emphysema progression. PMID:27902753

High-Temperature Thermal Diffusivity Measurements of Silicate Glasses

Science.gov (United States)

Pertermann, M.; Hofmeister, A. M.; Whittington, A. G.; Spera, F. J.; Zayac, J.

2005-12-01

Transport of heat in geologically relevant materials is of great interest because of its key role in heat transport, magmatism and volcanic activity on Earth. To better understand the thermal properties of magmatic materials at high temperatures, we measured the thermal diffusivity of four synthetic end-member silicate glasses with the following compositions: albite (NaAlSi3O8), orthoclase (KAlSi3O8), anorthite (CaAl2Si2O8), and diopside (CaMgSi2O6). Thermal diffusivity measurements were conducted with the laser-flash technique and data were acquired from room temperature to a maximum temperature near 1100°C, depending on the glass transition temperature. The presence of sub-mm sized bubbles in one of the orthoclase samples had no discernable effect on measured diffusivities. At room temperature, the three feldspar-type glasses have thermal diffusivity (D) values of 0.58-0.61 mm2/s, whereas the diopside glass has 0.52 mm2/s. With increasing temperature, D decreases by 5-10% (relative) for all samples and becomes virtually constant at intermediate temperatures. At higher temperatures, the anorthite and diopside glasses exhibit significant drops in thermal diffusivity over a 50-100°C interval, correlating with previously published heat capacity changes near the glass transition for these compositions. For anorthite, D (in mm2/s) decreases from 0.48 at 750-860°C to 0.36 at 975-1075°C; for diopside, D changes from 0.42 at 630-750°C to 0.30 at 850-910°C, corresponding to relative drops of 24 and 29%, respectively. Albite and orthoclase glasses do not exhibit this change and also lack significant changes in heat capacity near the glass transition. Instead, D is constant at 400-800°C for albite, and for orthoclase values go through a minimum at 500-600°C before increasing slightly towards 1100°C but it never exceeds the room temperature D. Our data on thermal diffusivity correlate closely with other thermophysical properties. Thus, at least in case of simple

Interaction and diffusion transport of americium in soils

Energy Technology Data Exchange (ETDEWEB)

Ramirez-Guinart, Oriol; Rigol, Anna; Vidal, Miquel [Analytical Chemistry department, Faculty of Chemistry, University of Barcelona, Marti i Franques 1-11, 08028, Barcelona (Spain)

2014-07-01

The final disposal of High Level Radioactive Wastes (HLRW) is based on its long-term storage in underground facilities located in geological stable sites with a multi-barrier system, the so called Deep Geological Repositories (DGR), that will keep HLRW confined for >10.000 years. After this period of time, leachates rich in long-live radioisotopes might escape from DGR and start to transport towards the biosphere. There is still a lack of information concerning the interaction and transport in soils of some radionuclides present in HLRW, especially for radionuclides that present a high sorption, such as americium (Am). Having reliable information about the mobility of radionuclides in soils is crucial in order to develop risk assessment models and to take proper decisions in case of soil contamination. The aim of the present work was, by means of laboratory scale experiments, to study the interaction and, for first time, to evaluate the diffusion transport of {sup 241}Am in soils. The {sup 241}Am interaction in soils was assessed by applying sorption batch assays to 20 soil samples with contrasted edaphic properties which allowed us to quantify the solid-liquid distribution coefficient (K{sub d}) and desorption percentage. K{sub d} (Am) values ranged from 10{sup 3} to 10{sup 5} L kg{sup -1} and desorption percentages were always less than 2% which denoted a high capacity of the soil to incorporate the Am and a low reversibility of the sorption process. The influence of soil properties in {sup 241}Am interaction was studied by means of multiple linear and multivariate regressions. Although a single correlation between K{sub d} (Am) values and a soil property was not found, the main properties affecting {sup 241}Am interaction in soils were soil pH, carbonate and organic matter contents in the soil. Finally, additional batch assays at different controlled pH were done to study Am sorption as a function of the contact solution pH. A variation of the Am sorption

Carrying capacity an approaching procedure to the economic value of natural patrimony

International Nuclear Information System (INIS)

Blandon M, Luis; Ochoa S, German; Ospina N, Efren

2001-01-01

This study demonstrates a new alternative method for valorizing the natural heritage of various economically and environmentally important ecosystems. It was conducted in the Piedras Blancas, Antioquia watershed and considered the degree of conservation of the area and its capacity for supporting humans, by means of extractive economic activities. In this way the ecosystem itself provides a natural offer of goods and services and therefore a good approximation of its economic value

Prognostic value of brain proton MR spectroscopy and diffusion tensor imaging in newborns with hypoxic-ischemic encephalopathy treated by brain cooling

Energy Technology Data Exchange (ETDEWEB)

Ancora, G. [Neonatal Intensive Care Unit, Department of Mother and Infant Infermi Hospital of Rimini, Rimini (Italy); Testa, C.; Tonon, C.; Manners, D.N.; Gramegna, L.L.; Lodi, R. [Department of Biomedical and Neuromotor Sciences University of Bologna, MR Functional Unit, Bologna (Italy); Grandi, S.; Sbravati, F.; Savini, S.; Corvaglia, L.T.; Faldella, G. [University of Bologna, Neonatology Unit, Department of Woman, Child and Adolescent Health, Bologna (Italy); Tani, G. [University of Bologna, Radiology Unit, Department of Woman, Child and Adolescent Health, Bologna (Italy); Malucelli, E. [University of Bologna, Department of Pharmacy and Biotechnologies, Bologna (Italy)

2013-08-15

MRI, proton magnetic resonance spectroscopy ({sup 1}H-MRS), and diffusion tensor imaging (DTI) have been shown to be of great prognostic value in term newborns with moderate-severe hypoxic-ischemic encephalopathy (HIE). Currently, no data are available on {sup 1}H-MRS and DTI performed in the subacute phase after hypothermic treatment. The aim of the present study was to assess their prognostic value in newborns affected by moderate-severe HIE and treated with selective brain cooling (BC). Twenty infants treated with BC underwent conventional MRI and {sup 1}H-MRS at a mean (SD) age of 8.3 (2.8) days; 15 also underwent DTI. Peak area ratios of metabolites and DTI variables, namely mean diffusivity (MD), axial and radial diffusivity, and fractional anisotropy (FA), were calculated. Clinical outcome was monitored until 2 years of age. Adverse outcome was observed in 6/20 newborns. Both {sup 1}H-MRS and DTI variables showed higher prognostic accuracy than conventional MRI. N-acetylaspartate/creatine at a basal ganglia localisation showed 100 % PPV and 93 % NPV for outcome. MD showed significantly decreased values in many regions of white and gray matter, axial diffusivity showed the best predictive value (PPV and NPV) in the genu of corpus callosum (100 and 91 %, respectively), and radial diffusivity was significantly decreased in fronto white matter (FWM) and fronto parietal (FP) WM. The decrement of FA showed the best AUC (0.94) in the FPWM. Selective BC in HIE neonates does not affect the early and accurate prognostic value of {sup 1}H-MRS and DTI, which outperform conventional MRI. (orig.)

Increased signal intensity of prostate lesions on high b-value diffusion-weighted images as a predictive sign of malignancy

International Nuclear Information System (INIS)

Quentin, Michael; Schimmoeller, Lars; Antoch, Gerald; Blondin, Dirk; Arsov, Christian; Rabenalt, Robert; Albers, Peter

2014-01-01

The evaluation of lesions detected in prostate magnetic resonance imaging (MRI) with increased signal intensity (SI) on high b-value diffusion-weighted images as a sign of malignancy. One hundred and three consecutive patients with prostate MRI examination and MRI-guided in-bore biopsy were retrospectively included in the study. MRI-guided in-bore biopsy histologically confirmed prostate cancer in 50 patients (n = 92 lesions). The other 53 patients (n = 122 lesions) had negative bioptical results. In patients with histologically confirmed prostate cancer, 46 of the 92 lesions had visually increased SI on the high b-value images compared with the peripheral zone (SI = +27 ± 16%) or the central gland (SI = +37 ± 19%, P < 0.001 respectively). In patients with a negative biopsy, ten of the 122 lesions had visually increased SI (compared with the peripheral zone, SI = +29 ± 18%, and with the central gland, SI = +41 ± 15%, P < 0.001 respectively). Neither the apparent diffusion coefficient (ADC) values nor the Gleason Score of lesions with increased SI were significantly different from lesions without increased SI. Visually increased SI on the high b-value images of diffusion-weighted imaging using standard b-values is a sign of malignancy but can occasionally also be a feature of benign lesions. However, it does not indicate more aggressive tumours. (orig.)

Estimating values for the moisture source load and buffering capacities from indoor climate measurements

NARCIS (Netherlands)

Schijndel, van A.W.M.

2008-01-01

The objective of this study is to investigate the potential for estimating values for the total size of human induced moisture source load and the total buffering (moisture storage) capacity of the interior objects with the use of relatively simple measurements and the use of heat, air, and moisture

The alveolar to arterial oxygen partial pressure difference is associated with pulmonary diffusing capacity in heart failure patients.

Science.gov (United States)

Morosin, Marco; Vignati, Carlo; Novi, Angela; Salvioni, Elisabetta; Veglia, Fabrizio; Alimento, Marina; Merli, Guido; Sciomer, Susanna; Sinagra, Gianfranco; Agostoni, Piergiuseppe

2016-11-01

In chronic heart failure (HF), the alveolar-capillary membrane undergoes a remodeling process that negatively affects gas exchange. In case of alveolar-capillary gas diffusion impairment, arterial desaturation (SaO 2 ) is rarely observed in HF patients. At play are 3 factors: overall pulmonary diffusing capacity (assessed as lung diffusion for CO, DLCO), global O 2 consumption (VO 2 ) and alveolar (A) to arterial (a) pO 2 gradient (AaDO 2 ). In 100 consecutive stable HF patients, DLCO, resting respiratory gases and arterial blood gases were measured to determine VO 2, paO 2 , pAO 2 and AaDO 2 . DLCO was poorly but significantly related to AaDO 2 . The correlation improved after correcting AaDO 2 for VO 2 (p<0.001, r=0.49). Both VO 2 and AaDO 2 were independently associated with DLCO (p<0.001). Patients with reduced DLCO showed no differences as regards paO 2 and pAO 2 . AaDO 2 /VO 2 showed a higher gradient in patients with lower DLCO. AaDO 2 increase and VO 2 reduction allow preventing low SaO 2 in HF patients with reduced DLCO. Accordingly, we suggest considering AaDO 2 and VO 2 combined and reporting AaDO 2 /VO 2 . Copyright © 2016 Elsevier B.V. All rights reserved.

Investigating the capability to resolve complex white matter structures with high b-value diffusion magnetic resonance imaging on the MGH-USC Connectom scanner.

Science.gov (United States)

Fan, Qiuyun; Nummenmaa, Aapo; Witzel, Thomas; Zanzonico, Roberta; Keil, Boris; Cauley, Stephen; Polimeni, Jonathan R; Tisdall, Dylan; Van Dijk, Koene R A; Buckner, Randy L; Wedeen, Van J; Rosen, Bruce R; Wald, Lawrence L

2014-11-01

One of the major goals of the NIH Blueprint Human Connectome Project was to map and quantify the white matter connections in the brain using diffusion tractography. Given the prevalence of complex white matter structures, the capability of resolving local white matter geometries with multiple crossings in the diffusion magnetic resonance imaging (dMRI) data is critical. Increasing b-value has been suggested for delineation of the finer details of the orientation distribution function (ODF). Although increased gradient strength and duration increase sensitivity to highly restricted intra-axonal water, gradient strength limitations require longer echo times (TE) to accommodate the increased diffusion encoding times needed to achieve a higher b-value, exponentially lowering the signal-to-noise ratio of the acquisition. To mitigate this effect, the MGH-USC Connectom scanner was built with 300 mT/m gradients, which can significantly reduce the TE of high b-value diffusion imaging. Here we report comparisons performed across b-values based on q-ball ODF metrics to investigate whether high b-value diffusion imaging on the Connectom scanner can improve resolving complex white matter structures. The q-ball ODF features became sharper as the b-value increased, with increased power fraction in higher order spherical harmonic series of the ODF and increased peak heights relative to the overall size of the ODF. Crossing structures were detected in an increasingly larger fraction of white matter voxels and the spatial distribution of two-way and three-way crossing structures was largely consistent with known anatomy. Results indicate that dMRI with high diffusion encoding on the Connectom system is a promising tool to better characterize, and ultimately understand, the underlying structural organization and motifs in the human brain.

A practical guide for implementing and maintaining value-added clinical systems learning roles for medical students using a diffusion of innovations framework.

Science.gov (United States)

Gonzalo, Jed D; Graaf, Deanna; Ahluwalia, Amarpreet; Wolpaw, Dan R; Thompson, Britta M

2018-03-21

After emphasizing biomedical and clinical sciences for over a century, US medical schools are expanding experiential roles that allow students to learn about health care delivery while also adding value to patient care. After developing a program where all 1st-year medical students are integrated into interprofessional care teams to contribute to patient care, authors use a diffusion of innovations framework to explore and identify barriers, facilitators, and best practices for implementing value-added clinical systems learning roles. In 2016, authors conducted 32 clinical-site observations, 29 1:1 interviews with mentors, and four student focus-group interviews. Data were transcribed verbatim, and a thematic analysis was used to identify themes. Authors discussed drafts of the categorization scheme, and agreed upon results and quotations. Of 36 sites implementing the program, 17 (47%) remained, 8 (22%) significantly modified, and 11 (31%) withdrew from the program. Identified strategies for implementing value-added roles included: student education, patient characteristics, patient selection methods, activities performed, and resources. Six themes influencing program implementation and maintenance included: (1) educational benefit, (2) value added to patient care from student work, (3) mentor time and site capacity, (4) student engagement, (5) working relationship between school, site, and students, and, (6) students' continuity at the site. Health systems science is an emerging focus for medical schools, and educators are challenged to design practice-based roles that enhance education and add value to patient care. Health professions' schools implementing value-added roles will need to invest resources and strategize about best-practice strategies to guide efforts.

Diffusion-weighted imaging in relation to morphology on dynamic contrast enhancement MRI: the diagnostic value of characterizing non-puerperal mastitis.

Science.gov (United States)

Zhang, Lina; Hu, Jiani; Guys, Nicholas; Meng, Jinli; Chu, Jianguo; Zhang, Weisheng; Liu, Ailian; Wang, Shaowu; Song, Qingwei

2018-03-01

To demonstrate the value of diffusion-weighted imaging (DWI) in the characterisation of mastitis lesions. Sixty-one non-puerperal patients with pathologically confirmed single benign mastitis lesions underwent preoperative examinations with conventional MRI and axial DWI. Patients were categorised into three groups: (1) periductal mastitis (PDM), (2) granulomatous lobular mastitis (GLM), and (3) infectious abscess (IAB). Apparent diffusion coefficient (ADC) values of each lesion were recorded. A one-way ANOVA with logistic analysis was performed to compare ADC values and other parameters. Discriminative abilities of DWI modalities were compared using the area under the receiver operating characteristic curve (AUC). P mastitis subtypes. • Mastitis subtypes exhibit different characteristics on DWI and DCE MRI. • ADC values are helpful in isolating PDM from other mastitis lesions. • Distribution of non-mass enhancement also has value in comparing mastitis subtypes.

Peak capacity and peak capacity per unit time in capillary and microchip zone electrophoresis.

Science.gov (United States)

Foley, Joe P; Blackney, Donna M; Ennis, Erin J

2017-11-10

The origins of the peak capacity concept are described and the important contributions to the development of that concept in chromatography and electrophoresis are reviewed. Whereas numerous quantitative expressions have been reported for one- and two-dimensional separations, most are focused on chromatographic separations and few, if any, quantitative unbiased expressions have been developed for capillary or microchip zone electrophoresis. Making the common assumption that longitudinal diffusion is the predominant source of zone broadening in capillary electrophoresis, analytical expressions for the peak capacity are derived, first in terms of migration time, diffusion coefficient, migration distance, and desired resolution, and then in terms of the remaining underlying fundamental parameters (electric field, electroosmotic and electrophoretic mobilities) that determine the migration time. The latter expressions clearly illustrate the direct square root dependence of peak capacity on electric field and migration distance and the inverse square root dependence on solute diffusion coefficient. Conditions that result in a high peak capacity will result in a low peak capacity per unit time and vice-versa. For a given symmetrical range of relative electrophoretic mobilities for co- and counter-electroosmotic species (cations and anions), the peak capacity increases with the square root of the electric field even as the temporal window narrows considerably, resulting in a significant reduction in analysis time. Over a broad relative electrophoretic mobility interval [-0.9, 0.9], an approximately two-fold greater amount of peak capacity can be generated for counter-electroosmotic species although it takes about five-fold longer to do so, consistent with the well-known bias in migration time and resolving power for co- and counter-electroosmotic species. The optimum lower bound of the relative electrophoretic mobility interval [μ r,Z , μ r,A ] that provides the maximum

Computerized tomography and pulmonary diffusing capacity in highly trained athletes after performing a triathlon.

Science.gov (United States)

Caillaud, C; Serre-Cousiné, O; Anselme, F; Capdevilla, X; Préfaut, C

1995-10-01

We investigated the computerized tomographies (CTs) of the thorax and the pulmonary diffusing capacity for CO (DLCO) in eight male athletes before and after a triathlon. DLCO and alveolar volume (VA) were simultaneously measured during 9 s of breath holding. The transfer coefficient (KCO = DLCO/VA) was then calculated. CT scanning was performed during breath holding with the subjects in the supine position. Scanner analysis was done by 1) counting the linear and polygonal opacities (index of interstitial fluid accumulation) and 2) calculating the physical mean lung density and the mean slice mass. Results showed a significant reduction in DLCO (44.9 +/- 2.3 vs. 42.9 +/- 1.7 ml.min-1.mmHg-1; P triathlon and an increase in mean lung density (0.21 +/- 0.009 vs. 0.25 +/- 0.01 g/cm3; P long-distance race and showed a concomitant increase in CT lung density and in the number of opacities.

A longitudinal study of changes in Diffusion Tensor Value and their association with cognitive sequelae among patients with mild head injury.

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Munivenkatappa, Ashok; Bhagavatula, Indira D; Shukla, Dhaval P; Rajeswaran, Jamuna

2017-06-01

Diffusion tensor imaging (DTI) is an advanced and sensitive technique that detects sub-threshold pathology in normal imaging brain injury patients. Currently, there are no longitudinal DTI studies to look for time-based changes. The present study has investigated longitudinal imaging and its association with cognitive deficits. Twenty-one patients were available for MRI and neuropsychological test (NPT) assessment for all the 3 time points. Initially (presented with GCS 15 and normal scan findings. The DTI (Pvalues were correlated with specific time-point NPT scores using partial correlation (0.05). Right cerebral-hemisphere showed significant alterations in both anisotropy and diffusivity values overtime. Cingulate gyrus and occipital lobe showed prominent changes in anisotropy value. Significant improvement in thalamo-cortical anisotropy value after 3-4 months after injury was seen. The changes in diffusivity values were mainly seen in frontal, parietal lobe, right inferior fronto-occipital and superior longitudinal fasciculus, and posterior supramarginal gyrus. Time-related changes of tensor values of thalamus, frontal and temporal lobe had persistent and significant association with attention and learning/memory aspects. The findings of this study suggest that DTI detects and observes natural-recovery of brain regions affected by sub-threshold force.

Clinical usefulness of diffusion-weighted imaging using low and high b-values to detect rectal cancer

International Nuclear Information System (INIS)

Hosonuma, Tomonori; Tozaki, Mitsuhiro; Ichiba, Noriatsu; Sakuma, Tohru; Hayashi, Daichi; Yanaga, Katsuhiko; Fukuda, Kunihiko

2006-01-01

The purpose of this study was to assess the potential role of diffusion-weighted imaging (DWI) using low and high b-values to detect rectal cancer. The subjects were 15 patients diagnosed endoscopically with rectal cancer (m in 1 patient, sm in 0, mp in 3, ss in 7, se in 1, a in 3) and 20 patients diagnosed endoscopically with colon cancer and no other lesions (control group). Magnetic resonance imaging was performed using a 1.5T system. DWI was performed in the axial plane using echo planar imaging sequence (repetition time/echo time 1200/66, field of view 306 X 350 mm, reconstruction matrix 156 x 256, pixel size 2.0 x 1.4 x 8.0 mm) and acquired with 2 b-values (50 and 800 s/mm 2 ). Low and high b-value DW images were analyzed visually. A lesion was positive by detection of a focal area of high signal in the rectum in high b-value images. The apparent diffusion coefficient (ADC) values of areas of high signal in high b-value images were calculated from the low and high b-value images. High b-value images enabled visualization of all 15 rectal cancers. In the control group, 13 cases were classified as negative and 7 cases as positive for rectal cancer. Sensitivity for detection of rectal cancer was 100% (15/15), and specificity was 65% (13/20). The mean ADC values in 7 patients with false-positive lesions and in 15 patients with rectal cancer were 1.374 x 10 -3 mm 2 /s (standard deviation [SD]: 0.157) and 1.194 x 10 -3 mm 2 /s (SD: 0.152), respectively (P=0.026). DWI with low and high b-values may be used to screen for rectal cancer. (author)

Risk for COPD with Obstruction of Active Smokers with Normal Spirometry and Reduced Diffusion Capacity

Science.gov (United States)

Kaner, Robert J.; Sanders, Abraham; Vincent, Thomas L.; Mezey, Jason G.; Crystal, Ronald G.

2016-01-01

Background Smokers are assessed for COPD using spirometry, with COPD defined by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) as airflow limitation not fully reversible with bronchodilators. There is a subset of smokers with normal spirometry (by GOLD criteria), who have a low diffusion capacity (DLCO), a parameter linked to emphysema and small airway disease. The natural history of these “normal spirometry/low DLCO” smokers is unknown. Methods From a cohort of 1570 smokers in the New York City metropolitian area, all of whom had normal spirometry, two groups were randomly selected for lung function follow-up: smokers with normal spirometry/normal DLCO (n=59) and smokers with normal spirometry/low DLCO (n=46). All had normal history, physical examination, CBC, urinalysis, HIV status, α1-antitrypsin level, chest X-ray, FEV1, FVC, FEV1/FVC ratio and total lung capacity (TLC). Throughout the study, all continued to be active smokers. Findings In the normal spirometry/normal DLCO group assessed over 45 ± 20 months, 3% developed GOLD-defined COPD. In contrast, in the normal spirometry/low DLCO group, followed over 41 ± 31 months, 22% developed GOLD-defined COPD. Interpretation Despite appearing “normal” by GOLD, smokers with normal spirometry but low DLCO are at significant risk for developing COPD with obstruction to airflow. PMID:26541521

High b-value diffusion-weighted imaging in progressive multifocal leukoencephalopathy in HIV patients

International Nuclear Information System (INIS)

Godi, Claudia; De Vita, Enrico; Davagnanam, Indran; Tombetti, Enrico; Haddow, Lewis; Jaeger, Hans Rolf

2017-01-01

An ill-defined hyperintense edge and hypointense core on diffusion-weighted imaging (DWI) is typical of progressive multifocal leukoencephalopathy (PML). We aimed to investigate whether a b-value of 3,000 s/mm"2 (b3000) can improve visualisation of PML, or provide different structural information compared to 1,000 s/mm"2 (b1000). We retrospectively identified HIV-positive patients with confirmed PML studied under a clinical protocol including both b1000 and b3000 DWI. The rim and core of each PML lesion and normal-appearing white matter (NAWM) were outlined on trace-weighted DWI. Signal intensities, apparent diffusion coefficient (ADC) values and volumes were measured and compared between b1000 and b3000. Nine lesions from seven patients were analysed. The rim and core were better visualised on b3000, with higher signal of the rim and lower signal of the core compared to NAWM. The hyperintense rim had non-restricted average ADCs, but included foci of low ADC on both b3000 and b1000. Despite similar total lesion volumes, b3000 displayed significantly larger core and smaller rim volumes than b1000. b3000 improves visualisation of this important PML hallmark. Moreover, b3000 partly reclassifies tissue from rim into core, and might provide potentially more accurate biomarkers of PML activity and prognosis. (orig.)

High b-value diffusion-weighted imaging in progressive multifocal leukoencephalopathy in HIV patients

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Godi, Claudia [San Raffaele Scientific Institute, Neuroradiology Department, Milan (Italy); The National Hospital for Neurology and Neurosurgery, Lysholm Department of Neuroradiology, London (United Kingdom); UCL Institute of Neurology, Neuroradiological Academic Unit, Department of Brain Repair and Rehabilitation, London (United Kingdom); De Vita, Enrico; Davagnanam, Indran [The National Hospital for Neurology and Neurosurgery, Lysholm Department of Neuroradiology, London (United Kingdom); UCL Institute of Neurology, Neuroradiological Academic Unit, Department of Brain Repair and Rehabilitation, London (United Kingdom); Tombetti, Enrico [Vita-Salute San Raffaele University, Milan (Italy); Haddow, Lewis [University College London, Centre for Sexual Health and HIV Research, Research Department of Infection and Population Health, London (United Kingdom); Jaeger, Hans Rolf [The National Hospital for Neurology and Neurosurgery, Lysholm Department of Neuroradiology, London (United Kingdom); UCL Institute of Neurology, Neuroradiological Academic Unit, Department of Brain Repair and Rehabilitation, London (United Kingdom); University College Hospital, Centre of Medical Imaging, London (United Kingdom)

2017-09-15

An ill-defined hyperintense edge and hypointense core on diffusion-weighted imaging (DWI) is typical of progressive multifocal leukoencephalopathy (PML). We aimed to investigate whether a b-value of 3,000 s/mm{sup 2} (b3000) can improve visualisation of PML, or provide different structural information compared to 1,000 s/mm{sup 2} (b1000). We retrospectively identified HIV-positive patients with confirmed PML studied under a clinical protocol including both b1000 and b3000 DWI. The rim and core of each PML lesion and normal-appearing white matter (NAWM) were outlined on trace-weighted DWI. Signal intensities, apparent diffusion coefficient (ADC) values and volumes were measured and compared between b1000 and b3000. Nine lesions from seven patients were analysed. The rim and core were better visualised on b3000, with higher signal of the rim and lower signal of the core compared to NAWM. The hyperintense rim had non-restricted average ADCs, but included foci of low ADC on both b3000 and b1000. Despite similar total lesion volumes, b3000 displayed significantly larger core and smaller rim volumes than b1000. b3000 improves visualisation of this important PML hallmark. Moreover, b3000 partly reclassifies tissue from rim into core, and might provide potentially more accurate biomarkers of PML activity and prognosis. (orig.)

Diffusion tensor imaging of the cervical spinal cord in healthy adult population: normative values and measurement reproducibility at 3T MRI.

Science.gov (United States)

Brander, Antti; Koskinen, Eerika; Luoto, Teemu M; Hakulinen, Ullamari; Helminen, Mika; Savilahti, Sirpa; Ryymin, Pertti; Dastidar, Prasun; Ohman, Juha

2014-05-01

Compared to diffusion tensor imaging (DTI) of the brain, there is a paucity of reports addressing the applicability of DTI in the evaluation of the spinal cord. Most normative data of cervical spinal cord DTI consist of relatively small and arbitrarily collected populations. Comprehensive normative data are necessary for clinical decision-making. To establish normal values for cervical spinal cord DTI metrics with region of interest (ROI)- and fiber tractography (FT)-based measurements and to assess the reproducibility of both measurement methods. Forty healthy adults underwent cervical spinal cord 3T MRI. Sagittal and axial conventional T2 sequences and DTI in the axial plane were performed. Whole cord fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values were determined at different cervical levels from C2 to C7 using the ROI method. DTI metrics (FA, axial, and radial diffusivities based on eigenvalues λ1, λ2, and λ3, and ADC) of the lateral and posterior funicles were measured at C3 level. FA and ADC of the whole cord and the lateral and posterior funicles were also measured using quantitative tractography. Intra- and inter-observer variation of the measurement methods were assessed. Whole cord FA values decreased and ADC values increased in the rostral to caudal direction from C2 to C7. Between the individual white matter funicles no statistically significant difference for FA or ADC values was found. Both axial diffusivity and radial diffusivity of both lateral funicles differed significantly from those of the posterior funicle. Neither gender nor age correlated with any of the DTI metrics. Intra-observer variation of the measurements for whole cord FA and ADC showed almost perfect agreement with both ROI and tractography-based measurements. There was more variation in measurements of individual columns. Inter-observer agreement varied from moderate to strong for whole cord FA and ADC. Both ROI- and FT-based measurements are applicable

Enhancement of crop photosynthesis by diffuse light: quantifying the contributing factors.

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Li, T; Heuvelink, E; Dueck, T A; Janse, J; Gort, G; Marcelis, L F M

2014-07-01

global irradiance was high. Diffuse light enhanced crop photosynthesis. A more uniform horizontal PPFD distribution played the most important role in this enhancement, and a more uniform vertical PPFD distribution and higher leaf photosynthetic capacity contributed more to the enhancement of crop photosynthesis than did higher values of LAI. © The Author 2014. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Apparent Diffusion Coefficient (ADC) value: a potential imaging biomarker that reflects the biological features of rectal cancer.

Science.gov (United States)

Sun, Yiqun; Tong, Tong; Cai, Sanjun; Bi, Rui; Xin, Chao; Gu, Yajia

2014-01-01

We elected to analyze the correlation between the pre-treatment apparent diffusion coefficient (ADC) and the clinical, histological, and immunohistochemical status of rectal cancers. Forty-nine rectal cancer patients who received surgical resection without neoadjuvant therapy were selected that underwent primary MRI and diffusion-weighted imaging (DWI). Tumor ADC values were determined and analyzed to identify any correlations between these values and pre-treatment CEA or CA19-9 levels, and/or the histological and immunohistochemical properties of the tumor. Inter-observer agreement of confidence levels from two separate observers was suitable for ADC measurement (k  =  0.775). The pre-treatment ADC values of different T stage tumors were not equal (p  =  0.003). The overall trend was that higher T stage values correlated with lower ADC values. ADC values were also significantly lower for the following conditions: tumors with the presence of extranodal tumor deposits (p  =  0.006) and tumors with CA19-9 levels ≥ 35 g/ml (p  =  0.006). There was a negative correlation between Ki-67 LI and the ADC value (r  =  -0.318, p  =  0.026) and between the AgNOR count and the ADC value (r  =  -0.310, p  =  0.030). Significant correlations were found between the pre-treatment ADC values and T stage, extranodal tumor deposits, CA19-9 levels, Ki-67 LI, and AgNOR counts in our study. Lower ADC values were associated with more aggressive tumor behavior. Therefore, the ADC value may represent a useful biomarker for assessing the biological features and possible relationship to the status of identified rectal cancers.

Correlation of the apparent diffusion coefficient and the standardized uptake value in neoplastic lesions: a meta-analysis.

Science.gov (United States)

Shen, Guohua; Ma, Huan; Liu, Bin; Ren, Pengwei; Kuang, Anren

2017-12-01

Diffusion-weighted imaging and fluorine-18-fluorodeoxyglucose PET are increasingly being recognized as feasible oncological techniques. The apparent diffusion coefficient (ADC) measured by diffusion-weighted imaging and the standardized uptake value (SUV) from fluorine-18-fluorodeoxyglucose PET have similar clinical applications. The aim of this study was to assess the correlation between these two parameters in various cancers. Several major databases were searched for eligible studies. The correlation coefficient (ρ) values were pooled in a random-effects model. Begg's test was used to analyze the existence of publication bias and the sources of heterogeneity were explored in subgroup analyses on the basis of study design, diagnostic method, scanning modality, and tumor type. Thirty-five articles were accepted. The pooled ρ value of all of the accepted studies was -0.30 (95% confidence interval: -0.33 to -0.27), and notable heterogeneity was present (I=69.4%, Pcorrelation. The pooled ρ values were -0.26, -0.33, -0.32, and -0.33 for the SUVmax/ADCmean, SUVmax/ADCmin, SUVmean/ADCmean, and SUVmean/ADCmin relationships, respectively. The study design and diagnostic method were potential sources of heterogeneity. Lung cancer showed a stronger correlation (ρ=-0.42) than head and neck cancer (ρ=-0.27), cervical cancer (ρ=-0.21), and breast cancer (ρ=-0.23). A Begg's test indicated no significant publication bias among the accepted studies (P>0.05). The two functional parameters of ADC and SUV showed a very weak inverse correlation, which may contribute toward a sophisticated characterization of tumor biology. However, the findings require further validation with trials with large samples and different tumor types.

Carrying capacity in a heterogeneous environment with habitat connectivity.

Science.gov (United States)

Zhang, Bo; Kula, Alex; Mack, Keenan M L; Zhai, Lu; Ryce, Arrix L; Ni, Wei-Ming; DeAngelis, Donald L; Van Dyken, J David

2017-09-01

A large body of theory predicts that populations diffusing in heterogeneous environments reach higher total size than if non-diffusing, and, paradoxically, higher size than in a corresponding homogeneous environment. However, this theory and its assumptions have not been rigorously tested. Here, we extended previous theory to include exploitable resources, proving qualitatively novel results, which we tested experimentally using spatially diffusing laboratory populations of yeast. Consistent with previous theory, we predicted and experimentally observed that spatial diffusion increased total equilibrium population abundance in heterogeneous environments, with the effect size depending on the relationship between r and K. Refuting previous theory, however, we discovered that homogeneously distributed resources support higher total carrying capacity than heterogeneously distributed resources, even with species diffusion. Our results provide rigorous experimental tests of new and old theory, demonstrating how the traditional notion of carrying capacity is ambiguous for populations diffusing in spatially heterogeneous environments. © 2017 John Wiley & Sons Ltd/CNRS.

Diagnostic value of MR diffusion weighted imaging in prostate cancer of central glands

International Nuclear Information System (INIS)

Xiao Lihua; Zheng Xiaolin; He Qiang; Luo Daosheng; Zhang Kunlin; Zou Yujian

2010-01-01

Objective: To discuss the diagnostic value of diffusion weighted imaging (DWI) in prostate cancer of central glands (CGPca) and differentiate from benign hyperlasia (BHP). Methods: All patients included 15 cases of prostate cancer of central glands and 20 cases of benign prostatic hyperplasia. DWI were obtained with factor b of 800 s/mm 2 . DWI and ADC map appearances were reviewed in all patients. ADC values of CGPca and PBH tissues were measured and analysed statistically. Results: All of 15 CGPca cases showed markedly markedly high-signal on DWI and low-signal on ADC map, both could clearly demonstrate the area of CGPca. But 6 cases were misdiagnosed as PBH by conventional imaging because of the tumors limited to central glands. The mean ADG values of CGPca cases and BPH cases were (0.93±0.13) x 10 -3 mm 2 /s and (11.53±0.12) x 10 -3 mm 2 /s respectively. There were significant differences in CGPca and BPH. Conclusion: It has an important clinical value in diagnosing prostate cancer of central glands and differentiating from BHP with DWI and ADC values. (authors)

Usefulness of Apparent Diffusion Coefficient Values in the Nasopharynx and the Oropharynx: Differentiation of Benign and Malignant Lesions

International Nuclear Information System (INIS)

Kwon, Hoon; Kim, Hak Jin; Sol, Yu Li; Lee, Tae Hong; Yeom, Jeong A; Kim, Ah Rong

2012-01-01

In several previous studies, apparent diffusion coefficient (ADC) calculation was applied in the evaluation of head and neck tumors and is a promising technique for this application. As a result, we reevaluated the usefulness of ADC measurement with differentiation of benign and malignant pathology in the nasopharynx and oropharynx. The study population consisted of 87 consecutive patients who had undergone routine nasopharyngeal and oropharyngeal MR imaging at our institution, which included diffusion weighted image and ADC map, with a clinically suspected primary tumor of nasopharynx and oropharynx. The mean ADC values in the benign and malignant groups were compared and the malignant group was divided into the lymphoma and carcinoma groups. A statistically significant difference in ADC values among the benign and malignant groups using independent samples t-test with a p -3 mm 2 /s was used to distinguish between benign and malignancy, accuracy was 85%. ADC values were useful for distinguishing between benign and malignancy in the nasopharynx and oropharynx.

Demonstration of non-Gaussian restricted diffusion in tumor cells using diffusion-time dependent diffusion weighted MR contrast

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Tuva Roaldsdatter Hope

2016-08-01

Full Text Available The diffusion weighted imaging (DWI technique enables quantification of water mobility for probing microstructural properties of biological tissue, and has become an effective tool for collecting information about the underlying pathology of cancerous tissue. Measurements using multiple b-values have indicated a bi-exponential signal attenuation, ascribed to fast (high ADC and slow (low ADC diffusion components. In this empirical study, we investigate the properties of the diffusion time (∆ - dependent components of the diffusion-weighted (DW signal in a constant b-value experiment. A Xenograft GBM mouse was imaged using ∆ = 11 ms, 20 ms, 40 ms, 60 ms and b=500-4000 s/mm2 in intervals of 500s/mm2. Data was corrected for EPI distortions and the ∆-dependence on the DW signal was measured within three regions of interest (intermediate- and high-density tumor regions and normal appearing brain tissue regions (NAB. In this empirical study we verify the assumption that the slow decaying component of the DW-signal is non-Gaussian and dependent on ∆, consistent with restricted diffusion of the intracellular space. As the DW-signal as a function of ∆ is specific to restricted diffusion, manipulating ∆ at constant b-value (cb provides a complementary and direct approach for separating the restricted from the hindered diffusion component. Our results show that only tumor tissue signal of our data demonstrate ∆-dependence, based on a bi-exponential model with a restricted diffusion component, we successfully estimated the restricted ADC, signal volume fraction and cell size within each tumor ROI.

Defect-Mediated Lithium Adsorption and Diffusion on Monolayer Molybdenum Disulfide

OpenAIRE

Sun, Xiaoli; Wang, Zhiguo; Fu, Yong Qing

2015-01-01

Monolayer Molybdenum Disulfide (MoS2) is a promising anode material for lithium ion batteries because of its high capacities. In this work, first principle calculations based on spin density functional theory were performed to investigate adsorption and diffusion of lithium on monolayer MoS2 with defects, such as single- and few-atom vacancies, antisite, and grain boundary. The values of adsorption energies on the monolayer MoS2 with the defects were increased compared to those on the pristin...

Apparent Diffusion Coefficient (ADC value: a potential imaging biomarker that reflects the biological features of rectal cancer.

Directory of Open Access Journals (Sweden)

Yiqun Sun

Full Text Available OBJECTIVE: We elected to analyze the correlation between the pre-treatment apparent diffusion coefficient (ADC and the clinical, histological, and immunohistochemical status of rectal cancers. MATERIALS AND METHODS: Forty-nine rectal cancer patients who received surgical resection without neoadjuvant therapy were selected that underwent primary MRI and diffusion-weighted imaging (DWI. Tumor ADC values were determined and analyzed to identify any correlations between these values and pre-treatment CEA or CA19-9 levels, and/or the histological and immunohistochemical properties of the tumor. RESULTS: Inter-observer agreement of confidence levels from two separate observers was suitable for ADC measurement (k  =  0.775. The pre-treatment ADC values of different T stage tumors were not equal (p  =  0.003. The overall trend was that higher T stage values correlated with lower ADC values. ADC values were also significantly lower for the following conditions: tumors with the presence of extranodal tumor deposits (p  =  0.006 and tumors with CA19-9 levels ≥ 35 g/ml (p  =  0.006. There was a negative correlation between Ki-67 LI and the ADC value (r  =  -0.318, p  =  0.026 and between the AgNOR count and the ADC value (r  =  -0.310, p  =  0.030. CONCLUSION: Significant correlations were found between the pre-treatment ADC values and T stage, extranodal tumor deposits, CA19-9 levels, Ki-67 LI, and AgNOR counts in our study. Lower ADC values were associated with more aggressive tumor behavior. Therefore, the ADC value may represent a useful biomarker for assessing the biological features and possible relationship to the status of identified rectal cancers.

Comparing Resource Adequacy Metrics and Their Influence on Capacity Value: Preprint

Energy Technology Data Exchange (ETDEWEB)

Ibanez, E.; Milligan, M.

2014-04-01

Traditional probabilistic methods have been used to evaluate resource adequacy. The increasing presence of variable renewable generation in power systems presents a challenge to these methods because, unlike thermal units, variable renewable generation levels change over time because they are driven by meteorological events. Thus, capacity value calculations for these resources are often performed to simple rules of thumb. This paper follows the recommendations of the North American Electric Reliability Corporation?s Integration of Variable Generation Task Force to include variable generation in the calculation of resource adequacy and compares different reliability metrics. Examples are provided using the Western Interconnection footprint under different variable generation penetrations.

Pancreatic cancer: Lack of association between apparent diffusion coefficient values and adverse pathological features

International Nuclear Information System (INIS)

Rosenkrantz, A.B.; Matza, B.W.; Sabach, A.; Hajdu, C.H.; Hindman, N.

2013-01-01

Aim: To identify retrospectively potential associations between apparent diffusion coefficient (ADC) values of pancreatic adenocarcinoma and tumour grade as well as other pathological features, using histopathological assessment from the Whipple procedure as the reference standard. Materials and methods: Thirty patients with pancreatic adenocarcinoma underwent magnetic resonance imaging (MRI) including diffusion-weighted imaging with b-values of 0 and 500 s/mm 2 before the Whipple procedure. Two radiologists independently recorded the ADC values of the tumour and benign pancreas for all cases. ADC values were compared with histopathological findings following the Whipple procedure. Results: The intra-class correlation coefficient was 0.689 for benign pancreas and 0.695 for tumours, indicating good inter-reader agreement for ADC values. The mean ADC value was significantly lower in tumours than in benign pancreas for both readers (reader 1: 1.74 ± 0.34 × 10 −3 mm 2 /s versus 2.08 ± 0.48 × 10 −3 mm 2 /s, respectively, p = 0.006; reader 2: 1.69 ± 0.41 × 10 −3 mm 2 /s versus 2.11 ± 0.54 × 10 −3 mm 2 /s, respectively, p −3 mm 2 /s versus 1.78 ± 0.33 × 10 −3 mm 2 /s, respectively, p = 0.491; reader 2: 1.62 ± 0.33 × 10 −3 mm 2 /s versus 1.75 ± 0.49 × 10 −3 mm 2 /s, respectively, p = 0.405). The area under the curve (AUC) for differentiation of poorly and well/moderately differentiated tumours was 0.611 and 0.596 for readers 1 and 2, respectively, and was not significantly better than an AUC of 0.500 for either reader (p ≥ 0.306). In addition, ADC was not significantly different for either reader between tumours with stage T3 versus stage T1/T2, between tumours with and without metastatic peri-pancreatic lymph nodes, or between tumours located in the pancreatic head versus other pancreatic regions (p ≥ 0.413). Conclusion: No associations between ADC values of pancreatic adenocarcinoma and tumour grade or other adverse pathological features

Strain enhanced lithium adsorption and diffusion on silicene.

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Wang, Xiao; Luo, Youhua; Yan, Ting; Cao, Wei; Zhang, Meng

2017-03-01

The performance of Li-ion batteries relies heavily on the capacity and stability of constituent electrodes. Recently synthesized 2D silicene has demonstrated excellent Li-ion capacity with high charging rates. To explore the external influences for battery performance, in this work, first-principles calculations are employed to investigate the effect of external strain on the adsorption and diffusion of Li on silicene monolayers. It was found that tensile strain could enhance Li binding on silicene. The diffusion barrier is also calculated and the results show that Li diffusion through silicene is facilitated by tensile strain, whereas the strain has a limited effect on the energy barrier of diffusion parallel to the plane of pristine silicene. Our results suggest that silicene could be a promising electrode material for lithium ion batteries.

The value of the abnormalities of bronchovascular bundles in the diagnosis of diffused lung diseases

International Nuclear Information System (INIS)

Li Tieyi; Ji Jingling

1997-01-01

To evaluate the abnormalities of bronchovascular bundles in the differential diagnosis of the diffuse lung disease, seventy-two patients with diffuse lung diseases were evaluated, 15 of 72 patients were pathologically proven and the others clinically proven. Of these 72 patients, there were 33 patients with diffuse pulmonary interstitial disease, 5 patients with pulmonary parenchymal disease, 14 patients with bronchial disease, and 20 patients with disseminated disease. All patients had conventional CT scan of the chest, some also had HRCT scan. All CT images were jointly reviewed by two radiologists. The features of the abnormalities of bronchovascular bundles included: (1) Thinning of bronchovascular bundles, predominantly seen in diffuse interstitial disease of lung and chronic bronchitis; (2) thickening of bronchovascular bundles, predominantly seen in interstitial diseases and disseminated lung diseases such as sarcoidosis and lymphangitis carcinomatosis with beaded appearance of bronchovascular bundles; (3) Increased visibility of bronchovascular bundles, predominantly seen in bronchiolitis and disseminated lung diseases. CT features of the abnormalities of bronchovascular bundles are present in 80% of diffuse lung diseases. The features are not specific, but the beaded bronchovascular bundles are always seen in sarcoidosis and lymphangitis carcinomatosis. In making a distinction between idiopathic pulmonary fibrosis and chronic bronchitis complicated with interstitial fibrosis, the position of diaphragm is of value in differential diagnosis, normal or elevated diaphragm is usually seen in the former, while low and flattened diaphragm in the latter. Change of the appearance of bronchovascular bundles from normality to abnormality reflects the process of development of the lung disease

Diffusion-Weighted Imaging and Diffusion Tensor Imaging of Asymptomatic Lumbar Disc Herniation

OpenAIRE

Sakai, Toshinori; Miyagi, Ryo; Yamabe, Eiko; Fujinaga, Yasunari; Bhatia, Nitin N.; Yoshioka, Hiroshi

2014-01-01

Diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) were performedon a healthy 31-year-old man with asymptomatic lumbar disc herniation. Althoughthe left S1 nerve root was obviously entrapped by a herniated mass, neither DWI nor DTI showed any significant findings for the nerve root. Decreased apparent diffusion coefficient (ADC) values and increased fractional anisotropy (FA) values were found. These results are contrary to those in previously published studies of symptomatic...

Glucocorticoid treatment of brain tumor patients: changes of apparent diffusion coefficient values measured by MR diffusion imaging

International Nuclear Information System (INIS)

Minamikawa, Sosuke; Kono, Kinuko; Nakayama, Keiko; Yokote, Hiroyuki; Tashiro, Takahiko; Inoue, Yuichi; Nishio, Akimasa; Hara, Mitsuhiro

2004-01-01

Glucocorticoids (GCC) generally are administered to patients with brain tumors to relieve neurological symptoms by decreasing the water content in a peritumoral zone of edema. We hypothesized that diffusion imaging and apparent diffusion coefficient (ADC) values could detect subtle changes of water content in brain tumors and in peritumoral edema after GCC therapy. The study consisted of 13 patients with intra-axial brain tumor, and ADC was measured in the tumor, within peritumoral edema, and in normal white matter remote from the tumor before and after GCC therapy. ADC also was measured in normal white matter in four control patients with no intracranial disease who were treated with GCC for other indications. Conventional MR images showed no visually evident interval change in tumor size or the extent of peritumoral edema in any subject after GCC therapy, which nonetheless resulted in a decrease in mean ADC of 7.0% in tumors (P 0.05, not significant) and 5.8% in normal white matter (P<0.05). In patients with no intracranial disease, GCC therapy decreased mean ADC in white matter by 5.4% (P<0.05). ADC measurement can demonstrate subtle changes in the brain after GCC therapy that cannot be observed by conventional MR imaging. Measurement of ADC proved to be a sensitive means of assessing the effect of GCC therapy, even in the absence of visually discernible changes in conventional MR images. (orig.)

Diffusion weighted imaging of liver lesions suspect for metastases: Apparent diffusion coefficient (ADC) values and lesion contrast are independent from Gd-EOB-DTPA administration

International Nuclear Information System (INIS)

Benndorf, Matthias; Schelhorn, Juliane; Dietzel, Matthias; Kaiser, Werner A.; Baltzer, Pascal A.T.

2012-01-01

Purpose: Gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) enhanced liver MRI is widely used for detection and differentiation of focal liver lesions. Diffusion weighted imaging (DWI) including apparent diffusion coefficient (ADC) measurements is increasingly utilised as a fast and, with limitations, quantitative method for liver lesion detection and characterisation. Herein we investigate whether the administration of Gd-EOB-DTPA affects DWI. Materials and methods: 31 consecutive patients referred to standardised liver MRI (1.5 T, Gd-EOB-DTPA, 0.025 mmol/kg) were retrospectively reviewed. All underwent a breathhold DWI sequence before and after contrast agent administration (EPI-DWI, TR/TE (effective): 2100/62 ms, b-values: 0 and 800 s/mm 2 ). Patients with previously treated liver lesions were excluded. Signal intensity of lesion, parenchyma and noise on DWI images as well as the ADC value were measured after identification by two observers in consensus using manually placed regions of interest. The reference standard was imaging follow-up determined separately by two radiologists. Data analysis included signal-to-noise (SNR) ratio and contrast-to-noise ratio (CNR) calculations, comparisons were drawn by employing multiple Bonferroni corrected Wilcoxon signed-rank tests. Results: 50 malignant and 39 benign lesions were identified. Neither SNR, CNR nor ADC values showed significant differences between pre- and postcontrast DWI. Both pre- and postcontrast ADC values differed significantly between benign and malignant lesions (P < 0.001). Conclusion: We did not identify a significant influence of Gd-EOB-DTPA on DWI of liver lesions. This allows for individual tailoring of imaging protocols according to clinical needs.

Estimating the Diffusion Coefficients of Sugars Using Diffusion Experiments in Agar-Gel and Computer Simulations.

Science.gov (United States)

Miyamoto, Shuichi; Atsuyama, Kenji; Ekino, Keisuke; Shin, Takashi

2018-01-01

The isolation of useful microbes is one of the traditional approaches for the lead generation in drug discovery. As an effective technique for microbe isolation, we recently developed a multidimensional diffusion-based gradient culture system of microbes. In order to enhance the utility of the system, it is favorable to have diffusion coefficients of nutrients such as sugars in the culture medium beforehand. We have, therefore, built a simple and convenient experimental system that uses agar-gel to observe diffusion. Next, we performed computer simulations-based on random-walk concepts-of the experimental diffusion system and derived correlation formulas that relate observable diffusion data to diffusion coefficients. Finally, we applied these correlation formulas to our experimentally-determined diffusion data to estimate the diffusion coefficients of sugars. Our values for these coefficients agree reasonably well with values published in the literature. The effectiveness of our simple technique, which has elucidated the diffusion coefficients of some molecules which are rarely reported (e.g., galactose, trehalose, and glycerol) is demonstrated by the strong correspondence between the literature values and those obtained in our experiments.

Value of apparent diffusion coefficient (ADC) in assessing radiotherapy and chemotherapy success in cervical cancer.

Science.gov (United States)

Fu, Zhan-Zhao; Peng, Yong; Cao, Li-Yan; Chen, Yan-Sheng; Li, Kun; Fu, Bao-Hong

2015-06-01

We investigated the clinical significance of apparent diffusion coefficient (ADC) values in diffusion-weighted magnetic resonance imaging (DWI) in monitoring the efficacy of radiotherapy (RT) and chemotherapy (CT) treatments in cervical cancer. In order to identify relevant high quality clinical cohort studies reporting the use of DWI in cervical cancers, the following electronic databases in English and Chinese languages were comprehensively searched: MEDLINE, Science Citation Index database, Cochrane Library Database, PubMed, Embase, CINAHL, and Current Contents Index; Chinese Biomedical Database, Chinese Journal Full-Text Database. All selected studies were published prior to March 2014, and data extracted from these studies were analyzed using STATA 12.0 statistical software. We initially retrieved 196 articles (79 Chinese articles and 117 English articles) through database searches and finally selected sixteen cohort studies for this meta-analysis. The 16 studies contained a combined total of 517 subjects, and all selected studies reported the mean ADC value (10(-3) mm(2)/s) in DWI in cervical cancer patients treated with RT and CT. Combined standardized mean difference (SMD) suggested that the mean post-RT and mean post-CT ADC values were significantly higher than the mean pre-RT and mean pre-CT ADC values, respectively, in cervical cancer patients (SMD=2.95, 95% CI=2.19-3.72, P900 (SMD=2.55, 95% CI=1.78-3.32, P<0.001). The mean ADC value in patients without residual tumor post-RT and post-CT treatment was significantly higher than seen in patients with residual tumors (SMD=0.80, 95% CI=0.49-1.12, P<0.001). Our meta-analysis revealed a significant correlation between mean ADC values and the clinical response to RT and CT treatment. Thus, ADC values in DWI may be effective in evaluating the clinical outcome of treatments in cervical cancer patients. Copyright © 2015 Elsevier Inc. All rights reserved.

Diffusion Tensor Imaging for the Differentiation of Microangiopathy, Infarction and Perfusion-Diffusion Mismatch Lesions

International Nuclear Information System (INIS)

Ha, Dong Ho; Choi, Sun Seob; Kang, Myong Jin; Lee, Jin Hwa; Yoon, Seong Kuk; Nam, Kyung Jin

2009-01-01

This study was designed to evaluate the usefulness of diffusion tensor imaging (DTI) and the DTI indices for differentiating between microangiopathy lesions, acute infarction lesions and perfusion-diffusion mismatch areas. DTI was performed in 35 patients with the use of a 1.5 Tesla MRI system. The MRI parameters were as follows: a spin echo EPI sequence with a bvalue = 1000 s/mm 2 , 25 diffusion directions, a repetition time of 8400 msec, an echo time of 75 msec, a matrix size of 128 x 128, a FOV of 22 cm and a 4 mm slice thickness. From the diffusion tensor images, the apparent diffusion coefficient (ADC), fractional anisotropy (FA), volume ratio (VR), relative anisotropy (RA), anisotropy index (AI), exponential ADC (eADC) and magnitude diffusion coefficient (MDC) were measured for the contra-lateral normal area (28 cases), the microangiopathy lesions (10 cases), the infarction lesions (17 cases) and the perfusion-diffusion mismatch area (8 cases). As compared to the normal area, the microangiopathy lesions showed increased ADC and MDC values and decreased FA, VR, RA, AI and eADC values. The infarction lesions showed increased VR, RA and eADC values, a normal FA, a decreased AI and decreased ADC and MDC values. The mismatch area showed a similar pattern as that for the microangiopathy lesions; however, the differences were not prominent, with an increase of the ADC and MDC values and a decrease of FA, VR, RA, AI and eADC values. The DTI indices could have a role in making the differential diagnosis of microangiopathy, acute infarction and perfusion-diffusion mismatch lesions

Apparent diffusion coefficient values and dynamic contrast enhancement patterns in differentiating seminomas from nonseminomatous testicular neoplasms

Energy Technology Data Exchange (ETDEWEB)

Tsili, Athina C., E-mail: a_tsili@yahoo.gr [Department of Radiology, Medical School, University of Ioannina, 45110 Ioannina (Greece); Sylakos, Anastasios, E-mail: anasylakos@yahoo.gr [Department of Urology, Medical School, University of Ioannina, 45110 Ioannina (Greece); Ntorkou, Alexandra, E-mail: alexdorkou@yahoo.com [Department of Radiology, Medical School, University of Ioannina, 45110 Ioannina (Greece); Stavrou, Sotirios, E-mail: s.sotiris@yahoo.gr [Department of Urology, Medical School, University of Ioannina, 45110 Ioannina (Greece); Astrakas, Loukas G., E-mail: astrakas@uoi.gr [Department of Medical Physics, Medical School, University of Ioannina, 45110 Ioannina (Greece); Sofikitis, Nikolaos, E-mail: akrosnin@hotmail.com [Department of Urology, Medical School, University of Ioannina, 45110 Ioannina (Greece); Argyropoulou, Maria I., E-mail: margyrop@cc.uoi.gr [Department of Radiology, Medical School, University of Ioannina, 45110 Ioannina (Greece)

2015-07-15

Highlights: • Functional MRI in the characterization of testicular germ cell tumors was assessed. • ADC values proved useful in the characterization of testicular germ cell tumors. • Testicular germ cell tumors had similar enhancement patterns of dynamic MRI. - Abstract: Introduction: The aim of this study is to investigate the role of apparent diffusion coefficient (ADC) values and dynamic contrast enhancement (DCE) patterns in differentiating seminomas from nonseminomatous germ cell tumors (NSGCTs). Materials and methods: The MRI examinations of the scrotum of 26 men with histologically proven testicular GCTs were reviewed. DWI was performed in all patients, using a single shot, multi-slice spin-echo planar diffusion pulse sequence and b-values of 0 and 900 s/mm{sup 2}. Subtraction DCE-MRI was performed in 20 cases using a 3D fast-field echo sequence after gadolinium administration. Time-signal intensity curves were created and semi-quantitative parameters (peak enhancement, time to peak, wash-in and wash-out rate) were calculated. The Student's t-test was used to compare the mean values of ADC, peak enhancement, time to peak, wash-in and wash-out rate between seminomas and NSGCTs. ROC analysis was also performed. Results: Histopathology disclosed the presence of 15 seminomas and 11 NSGCTs. The mean ± s.d. of ADC values (× 10{sup −3} mm{sup 2}/s) of seminomas (0.59 ± 0.009) were significantly lower than those of NSGCTs (0.90 ± 0.33) (P = 0.01). The optimal ADC cut-off value was 0.68 × 10{sup −3} mm{sup 2}/s. No differences between the two groups were observed for peak enhancement (P = 0.18), time to peak (P = 0.63) wash-in rate (P = 0.32) and wash-out rate (P = 0.18). Conclusions: ADC values may be used to preoperatively differentiate seminomas from NSGCTs.

Apparent diffusion coefficient values and dynamic contrast enhancement patterns in differentiating seminomas from nonseminomatous testicular neoplasms

International Nuclear Information System (INIS)

Tsili, Athina C.; Sylakos, Anastasios; Ntorkou, Alexandra; Stavrou, Sotirios; Astrakas, Loukas G.; Sofikitis, Nikolaos; Argyropoulou, Maria I.

2015-01-01

Highlights: • Functional MRI in the characterization of testicular germ cell tumors was assessed. • ADC values proved useful in the characterization of testicular germ cell tumors. • Testicular germ cell tumors had similar enhancement patterns of dynamic MRI. - Abstract: Introduction: The aim of this study is to investigate the role of apparent diffusion coefficient (ADC) values and dynamic contrast enhancement (DCE) patterns in differentiating seminomas from nonseminomatous germ cell tumors (NSGCTs). Materials and methods: The MRI examinations of the scrotum of 26 men with histologically proven testicular GCTs were reviewed. DWI was performed in all patients, using a single shot, multi-slice spin-echo planar diffusion pulse sequence and b-values of 0 and 900 s/mm 2 . Subtraction DCE-MRI was performed in 20 cases using a 3D fast-field echo sequence after gadolinium administration. Time-signal intensity curves were created and semi-quantitative parameters (peak enhancement, time to peak, wash-in and wash-out rate) were calculated. The Student's t-test was used to compare the mean values of ADC, peak enhancement, time to peak, wash-in and wash-out rate between seminomas and NSGCTs. ROC analysis was also performed. Results: Histopathology disclosed the presence of 15 seminomas and 11 NSGCTs. The mean ± s.d. of ADC values (× 10 −3 mm 2 /s) of seminomas (0.59 ± 0.009) were significantly lower than those of NSGCTs (0.90 ± 0.33) (P = 0.01). The optimal ADC cut-off value was 0.68 × 10 −3 mm 2 /s. No differences between the two groups were observed for peak enhancement (P = 0.18), time to peak (P = 0.63) wash-in rate (P = 0.32) and wash-out rate (P = 0.18). Conclusions: ADC values may be used to preoperatively differentiate seminomas from NSGCTs

Bioremediation capacity, nutritional value and biorefining of macroalga Saccharina latissima

DEFF Research Database (Denmark)

Silva Marinho, Goncalo

Macroalgae have the ability to assimilate and convert waste nutrients (N and P) into valuable biomass. In this context, they have been extensively studied for their bioremediation potential for integrated multi-trophic aquaculture (IMTA). With a global aquaculture production of 23.8 million tonnes...... attention as sustainable feedstock for biorefinery. Nevertheless, macroalgae resources are still very little explored in western countries. The aim of this study was fulfilled by the investigation of the bioremediation potential of the macroalga Saccharina latissima cultivated at a reference site (control...... two growing seasons enhanced the biomass yield and thus value, but not the bioremediation capacity. Harvest time had a significant impact in overall chemical composition, while cultivation site did not generally result in marked differences. The growth of epiphytic organisms from July to November...

Diffusion of Tritiated Water (HTO) and 22Na+-Ions through Non-Degraded Hardened Cement Pastes - II. Modelling Results

International Nuclear Information System (INIS)

Jakob, A.

2002-12-01

In this report, the procedure and the results of an inverse modelling study on the through-diffusion of tritiated water (HTO) and 2 2Na + -ions are presented using high-porous hardened cement pastes with a water/cement ratio of 1.3 in the first stage of the cement degradation. For the analysis two alternative models were applied: 1) a diffusion model where a possible sorption of the tracer was entirely neglected, and 2) a diffusion model with linear sorption. The analysis of the through-diffusion phase allowed extracting values for the effective diffusion coefficient (D e ) and the rock-capacity factor (α). Both models could fit the breakthrough curves equally well, and also mass-balance considerations did not allow to clearly preferring one of the two competing models to the other. But blind-predictions for tracer out-diffusion using the best-fit parameter values deduced from analysing the former through-diffusion phase gave a clear indication that linear sorption had to be included in the diffusion model. The extracted K d values for HTO are in excellent agreement with values from batch sorption experiments and are of the order of 0.8. 10 -3 m 3 /kg. Those for 2 2Na + are of the order of 1.0. 10 -3 m 3 /kg and are by a factor of two larger than values from batch sorption experiments. The values for the effective diffusion coefficients for HTO are of the order of (2-3).10 -1 0 m 2 /s, and those for sodium are roughly by a factor of two smaller than values for HTO. On the one hand, the observed tracer uptake could only partially be addressed to isotope exchange; the most obvious process which could account for the remaining part of the uptaken tracer mass is diffusion into a second type of porosity, the dead-end pores. On the other hand, the results and conclusions drawn are encouraging for future investigations; therefore no major deficiency concerning the applied equipment and the modelling methodology could be detected. In the report, however, some suggestions

Network analysis of surgical innovation: Measuring value and the virality of diffusion in robotic surgery.

Science.gov (United States)

Garas, George; Cingolani, Isabella; Panzarasa, Pietro; Darzi, Ara; Athanasiou, Thanos

2017-01-01

Existing surgical innovation frameworks suffer from a unifying limitation, their qualitative nature. A rigorous approach to measuring surgical innovation is needed that extends beyond detecting simply publication, citation, and patent counts and instead uncovers an implementation-based value from the structure of the entire adoption cascades produced over time by diffusion processes. Based on the principles of evidence-based medicine and existing surgical regulatory frameworks, the surgical innovation funnel is described. This illustrates the different stages through which innovation in surgery typically progresses. The aim is to propose a novel and quantitative network-based framework that will permit modeling and visualizing innovation diffusion cascades in surgery and measuring virality and value of innovations. Network analysis of constructed citation networks of all articles concerned with robotic surgery (n = 13,240, Scopus®) was performed (1974-2014). The virality of each cascade was measured as was innovation value (measured by the innovation index) derived from the evidence-based stage occupied by the corresponding seed article in the surgical innovation funnel. The network-based surgical innovation metrics were also validated against real world big data (National Inpatient Sample-NIS®). Rankings of surgical innovation across specialties by cascade size and structural virality (structural depth and width) were found to correlate closely with the ranking by innovation value (Spearman's rank correlation coefficient = 0.758 (p = 0.01), 0.782 (p = 0.008), 0.624 (p = 0.05), respectively) which in turn matches the ranking based on real world big data from the NIS® (Spearman's coefficient = 0.673;p = 0.033). Network analysis offers unique new opportunities for understanding, modeling and measuring surgical innovation, and ultimately for assessing and comparing generative value between different specialties. The novel surgical innovation metrics developed may

MR diffusion weighted imaging of gastric cancer: b-value determination and comparison with routine sequences

International Nuclear Information System (INIS)

Zhao Xiaopeng; Tang Lei; Sun Yingshi; Li Jie; Cao Kun

2007-01-01

Objective: To choose the optimal b-values for the DWI of gastric cancer (GC), and investigate the value of DWI in the diagnosis of GCs. Methods: MRI examinations (T 1 WI, T 2 WI, and DWI) were performed on 31 patients with gastric cancer. Three diffusion-weighted sequences were designed with different b values, including 300 s/mm 2 (low), 600 s/mm 2 (intermediate), and 1000 s/mm 2 (high). Free water grade was used to evaluate the suppression of content in gastric lumen. Background contrast grade was used to evaluate the discriminating ability of different sequences between GC and nearby tissues. The ADCs of GCs, nearby gastric wall region, and free water in gastric lumen were measured. SNR Ca , CNR Ca-GW and SIR CaGW of high b-value DWI and routine MRI sequences were evaluated and compared. Results: The signal intensity of free water in gastric lumen decreased as b-value increased, and the SIR were 8.11± 0.77 (b=300 s/mm 2 ), 2.70±0.35 (b=600 s/mm 2 ), and 1.13±0.22 (b=1000 s/mm 2 ) (F55.368, P 2 =16.692, P 2 =9.923, P -3 mm 2 /s, (1.43±0.41) x 10 -3 mm 2 /s, and (1.18±0.25) x 10 -3 mm 2 /s; (F=12.066, P 1 WI (CNR: 12.46 vs. 2.35, Z=-3.746, P 2 WI (CNR: 12.46 vs. 3.92, Z=-3.518, P 2 ) is reasonable for DWI of GCs, which can reflect diffusion condition of water molecules more accurately, suppress signal of content in gastric lumen, and possess higher contrast. DWI can be a supplementary method of routine MRI examination for better demonstration of gastric cancers. (authors)

Diffusion-weighted imaging of breast lesions: Region-of-interest placement and different ADC parameters influence apparent diffusion coefficient values

Energy Technology Data Exchange (ETDEWEB)

Bickel, Hubert; Pinker, Katja; Polanec, Stephan; Magometschnigg, Heinrich; Wengert, Georg; Spick, Claudio; Helbich, Thomas H.; Baltzer, Pascal [Medical University Vienna, Division of Molecular and Gender Imaging, Department of Biomedical Imaging and Image-Guided Therapy, Vienna (Austria); Bogner, Wolfgang [Medical University Vienna - MR Center of Excellence, Department of Biomedical Imaging and Image-Guided Therapy, Vienna (Austria); Bago-Horvath, Zsuzsanna [Medical University Vienna, Department of Pathology, Vienna (Austria)

2017-05-15

To investigate the influence of region-of-interest (ROI) placement and different apparent diffusion coefficient (ADC) parameters on ADC values, diagnostic performance, reproducibility and measurement time in breast tumours. In this IRB-approved, retrospective study, 149 histopathologically proven breast tumours (109 malignant, 40 benign) in 147 women (mean age 53.2) were investigated. Three radiologists independently measured minimum, mean and maximum ADC, each using three ROI placement approaches:1 - small 2D-ROI, 2 - large 2D-ROI and 3 - 3D-ROI covering the whole lesion. One reader performed all measurements twice. Median ADC values, diagnostic performance, reproducibility, and measurement time were calculated and compared between all combinations of ROI placement approaches and ADC parameters. Median ADC values differed significantly between the ROI placement approaches (p <.001). Minimum ADC showed the best diagnostic performance (AUC.928-.956), followed by mean ADC obtained from 2D ROIs (.926-.94). Minimum and mean ADC showed high intra- (ICC.85-.94) and inter-reader reproducibility (ICC.74-.94). Median measurement time was significantly shorter for the 2D ROIs (p <.001). ROI placement significantly influences ADC values measured in breast tumours. Minimum and mean ADC acquired from 2D-ROIs are useful for the differentiation of benign and malignant breast lesions, and are highly reproducible, with rapid measurement. (orig.)

Matrix diffusion in crystalline rocks: coupling of anion exclusion, surface diffusion and surface complexation

International Nuclear Information System (INIS)

Olin, M.; Valkiainen, M.; Aalto, H.

1997-12-01

This report includes both experimental and modelling parts. Also, a novel approach to the diffusion experiments is introduced, where ions of the same electric charge diffuse in opposite directions through the same rock sample. Six rock-types from Olkiluoto radioactive waste disposal investigation site were used in the experiments: granite, weathered granite, mica gneiss, weathered mica gneiss, tonalite and altered mica gneiss/migmatite. The experiments consisted of the determination of the effective diffusion coefficient and the rock capacity factor for tritium, chloride (Cl-36) and sodium (Na-22). The modelling consisted of a chemical model for small pores (< 100 nm), a model for counter ion diffusion and models for the laboratory experiments

Matrix diffusion in crystalline rocks: coupling of anion exclusion, surface diffusion and surface complexation

Energy Technology Data Exchange (ETDEWEB)

Olin, M.; Valkiainen, M.; Aalto, H. [VTT Chemical Technology, Espoo (Finland)

1997-12-01

This report includes both experimental and modelling parts. Also, a novel approach to the diffusion experiments is introduced, where ions of the same electric charge diffuse in opposite directions through the same rock sample. Six rock-types from Olkiluoto radioactive waste disposal investigation site were used in the experiments: granite, weathered granite, mica gneiss, weathered mica gneiss, tonalite and altered mica gneiss/migmatite. The experiments consisted of the determination of the effective diffusion coefficient and the rock capacity factor for tritium, chloride (Cl-36) and sodium (Na-22). The modelling consisted of a chemical model for small pores (< 100 nm), a model for counter ion diffusion and models for the laboratory experiments. 21 refs.

Diffusion in Altered Tonalite Sample Using Time Domain Diffusion Simulations in Tomographic Images Combined with Lab-scale Diffusion Experiments

Science.gov (United States)

Voutilainen, M.; Sardini, P.; Togneri, L.; Siitari-Kauppi, M.; Timonen, J.

2010-12-01

In this work an effect of rock heterogeneity on diffusion was investigated. Time domain diffusion simulations were used to compare behavior of diffusion in homogeneous and heterogeneous 3D media. Tomographic images were used as heterogeneous rock media. One altered tonalite sample from Sievi, Finland, was chosen as test case for introduced analysis procedure. Effective diffusion coefficient of tonalite sample was determined with lab-scale experiments and the same coefficient was used also for homogeneous media. Somewhat technically complicated mathematical solution for analysis of through diffusion experiment is shortly described. Computed tomography (CT) is already quite widely used in many geological, petrological, and paleontological applications when the three-dimensional (3D) structure of the material is of interest, and is an excellent method for gaining information especially about its heterogeneity, grain size, or porosity. In addition to offering means for quantitative characterization, CT provides a lot of qualitative information [1]. A through -diffusion laboratory experiment using radioactive tracer was fitted using the Time Domain Diffusion (TDD) method. This rapid particle tracking method allows simulation of the heterogeneous diffusion based on pore-scale images and local values of diffusivities [2]. As a result we found out that heterogeneity has only a small effect to diffusion coefficient and in-diffusion profile for used geometry. Also direction dependency was tested and was found to be negligible. Whereas significant difference between generally accepted value and value obtained from simulations for constant m in Archie’s law was found. [1] Voutilainen, M., Siitari-Kauppi, M., Sardini, P., and Timonen, J., (2010). On pore-space characterization of an altered tonalite by X-ray µCT and the 14C-PMMA method (in progress). [2] Sardini, P., Robinet, J., Siitari-Kauppi, M., Delay, F., and Hellmuth, K-H, (2007). On direct simulation of heterogeneous

Can broader diffusion of value-based insurance design increase benefits from US health care without increasing costs? Evidence from a computer simulation model.

Science.gov (United States)

Braithwaite, R Scott; Omokaro, Cynthia; Justice, Amy C; Nucifora, Kimberly; Roberts, Mark S

2010-02-16

Evidence suggests that cost sharing (i.e.,copayments and deductibles) decreases health expenditures but also reduces essential care. Value-based insurance design (VBID) has been proposed to encourage essential care while controlling health expenditures. Our objective was to estimate the impact of broader diffusion of VBID on US health care benefits and costs. We used a published computer simulation of costs and life expectancy gains from US health care to estimate the impact of broader diffusion of VBID. Two scenarios were analyzed: (1) applying VBID solely to pharmacy benefits and (2) applying VBID to both pharmacy benefits and other health care services (e.g., devices). We assumed that cost sharing would be eliminated for high-value services (value services ($100,000-$300,000 per life-year or unknown), and would be increased for low-value services (>$300,000 per life-year). All costs are provided in 2003 US dollars. Our simulation estimated that approximately 60% of health expenditures in the US are spent on low-value services, 20% are spent on intermediate-value services, and 20% are spent on high-value services. Correspondingly, the vast majority (80%) of health expenditures would have cost sharing that is impacted by VBID. With prevailing patterns of cost sharing, health care conferred 4.70 life-years at a per-capita annual expenditure of US$5,688. Broader diffusion of VBID to pharmaceuticals increased the benefit conferred by health care by 0.03 to 0.05 additional life-years, without increasing costs and without increasing out-of-pocket payments. Broader diffusion of VBID to other health care services could increase the benefit conferred by health care by 0.24 to 0.44 additional life-years, also without increasing costs and without increasing overall out-of-pocket payments. Among those without health insurance, using cost saving from VBID to subsidize insurance coverage would increase the benefit conferred by health care by 1.21 life-years, a 31% increase

Carbon dioxide sequestration: Modeling the diffusive and convective transport under a CO2 cap

KAUST Repository

Allen, Rebecca

2012-01-01

A rise in carbon dioxide levels from industrial emissions is contributing to the greenhouse effect and global warming. CO2 sequestration in saline aquifers is a strategy to reduce atmospheric CO2 levels. Scientists and researchers rely on numerical simulators to predict CO2 storage by modeling the fluid transport behaviour. Studies have shown that after CO2 is injected into a saline aquifer, undissolved CO2 rises due to buoyant forces and will spread laterally away from the injection site under an area of low permeability. CO2 from this ‘capped\\' region diffuses into the fluid underlying it, and the resulting CO2-fluid mixture increases in density. This increase in density leads to gravity-driven convection. Accordingly, diffusive-convective transport is important to model since it predicts an enhanced storage capacity of the saline aquifer. This work incorporates the diffusive and convective transport processes into the transport modeling equation, and uses a self-generated code. Discretization of the domain is done with a cell-centered finite difference method. Cases are set up using similar parameters from published literature in order to compare results. Enhanced storage capacity is predicted in this work, similar to work done by others. A difference in the onset of convective transport between this work and published results is noticed and discussed in this paper. A sensitivity analysis is performed on the density model used in this work, and on the diffusivity value assumed. The analysis shows that the density model and diffusivity value is a key component on simulation results. Also, perturbations are added to porosity and permeability in order to see the effect of perturbations on the onset of convection, and results agree with similar findings by others. This work provides a basis for studying other cases, such as the impact of heterogeneity on the diffusion-convective transport. An extension of this work may involve the use of an equation of state to

Diffusion MRI findings in phenylketonuria

International Nuclear Information System (INIS)

Sener, R.N.

2003-01-01

Two patients with phenylketonuria were studied who were under dietary control since infancy, and who were mentally normal. Diffusion MRI was obtained using a spin-echo, echo-planar sequence with a gradient strength of 30 mT/m at 1.5 T. A trace sequence (TR=5700 ms, and TE=139 ms) was used, acquired in 22 s. Heavily diffusion-weighted (b=1000 mm 2 /s) images, and the apparent diffusion coefficient (ADC) values from automatically generated ADC maps were studied. There were two different patterns in these two patients, restricted and increased diffusion patterns. Restricted diffusion pattern consisted of high-signal on b=1000 s/mm 2 images with low ADC values ranging from 0.46 to 0.57 x 10 -3 mm 2 /s. Increased diffusion pattern consisted of normal b=1000 s/mm 2 images with high ADC values ranging from 1.37 to 1.63 x 10 -3 mm 2 /s. It is likely that these values reflected presence of two different histopathological changes in phenylketonuria or reflected different stages of the same disease. (orig.)

Lung function and exercise capacity in young adults born prematurely

NARCIS (Netherlands)

Vrijlandt, EJLE; Gerritsen, J; Boezen, HM; Grevink, RG; Duiverman, EJ

2006-01-01

Rationale: Limited information is available about the long-term outcome of lung function and exercise capacity in young adults born prematurely. Objective: To determine long-term effects of prematurity on lung function (volumes, diffusing capacity) and exercise capacity in expreterms compared with

Carpal tunnel syndrome assessment with diffusion tensor imaging. Value of fractional anisotropy and apparent diffusion coefficient

Energy Technology Data Exchange (ETDEWEB)

Klauser, A.S.; Kremser, C. [Medical University of Innsbruck, Department of Radiology, Innsbruck (Austria); Abd Ellah, M. [Medical University of Innsbruck, Department of Radiology, Innsbruck (Austria); Assiut University, Department of Diagnostic Radiology, South Egypt Cancer Institute, Assiut (Egypt); Taljanovic, M. [University of Arizona, College of Medicine, Banner- University Medical Center, Department of Medical Imaging, Tucson (United States); Schmidle, G.; Gabl, M. [Medical University of Innsbruck, Department for Trauma Surgery, Innsbruck (Austria); Cartes-Zumelzu, F.; Steiger, R.; Gizewski, E.R. [Medical University of Innsbruck, Department of Neuroradiology, Neuroimaging core facility, Innsbruck (Austria)

2018-03-15

To quantitatively assess carpal tunnel syndrome (CTS) with DTI by evaluating two approaches to determine cut-off values. In forty patients with CTS diagnosis confirmed by nerve conduction studies (NCs) and 14 healthy subjects (mean age 58.54 and 57.8 years), cross-sectional area (CSA), apparent diffusion coefficient (ADC) and fractional anisotropy (FA) at single and multiple levels with intraobserver agreement were evaluated. Maximum and mean CSA and FA showed significant differences between healthy subjects and patients (12.85 mm{sup 2} vs. 28.18 mm{sup 2}, p < 0.001, and 0.613 vs. 0.524, p=0.007, respectively) (10.12 mm{sup 2} vs. 19.9 mm{sup 2}, p<0.001 and 0.617 vs. 0.54, p=0.003, respectively), but not maximum and mean ADC (p > 0.05). For cut-off values, mean and maximum CSA showed the same sensitivity and specificity (93.3 %). However, mean FA showed better sensitivity than maximum FA (82.6 % vs. 73.9 %), but lower specificity (66.7 % vs. 80 %), and significant correlation for maximum CSA, 97 % (p < 0.01), with good correlation for maximum ADC and FA, 84.5 % (p < 0.01) and 62 % (p=0.056), respectively. CSA and FA showed significant differences between healthy subjects and patients. Single measurement at maximum CSA is suitable for FA determination. (orig.)

Benign and malignant skull-involved lesions: discriminative value of conventional CT and MRI combined with diffusion-weighted MRI.

Science.gov (United States)

Tu, Zhanhai; Xiao, Zebin; Zheng, Yingyan; Huang, Hongjie; Yang, Libin; Cao, Dairong

2018-01-01

Background Little is known about the value of computed tomography (CT) and magnetic resonance imaging (MRI) combined with diffusion-weighted imaging (DWI) in distinguishing malignant from benign skull-involved lesions. Purpose To evaluate the discriminative value of DWI combined with conventional CT and MRI for differentiating between benign and malignant skull-involved lesions. Material and Methods CT and MRI findings of 58 patients with pathologically proven skull-involved lesions (43 benign and 15 malignant) were retrospectively reviewed. Conventional CT and MRI characteristics and apparent diffusion coefficient (ADC) value of the two groups were evaluated and compared. Multivariate logistic regression and receiver operating characteristic (ROC) curve analyses were performed to assess the differential performance of each parameter separately and together. Results The presence of cortical defects or break-through and ill-defined margins were associated with malignant skull-involved lesions (both P benign and malignant skull-involved lesions. Conclusion The combination of CT, MRI, and DWI can help to differentiate malignant from benign skull-involved lesions. CT + MRI + DWI offers optimal sensitivity, while DWI offers optimal specificity.

Acute effects of combined exercise and oscillatory positive expiratory pressure therapy on sputum properties and lung diffusing capacity in cystic fibrosis: a randomized, controlled, crossover trial.

Science.gov (United States)

Radtke, Thomas; Böni, Lukas; Bohnacker, Peter; Maggi-Beba, Marion; Fischer, Peter; Kriemler, Susi; Benden, Christian; Dressel, Holger

2018-06-14

Regular airway clearance by chest physiotherapy and/or exercise is critical to lung health in cystic fibrosis (CF). Combination of cycling exercise and chest physiotherapy using the Flutter® device on sputum properties has not yet been investigated. This prospective, randomized crossover study compared a single bout of continuous cycling exercise at moderate intensity (experiment A, control condition) vs a combination of interval cycling exercise plus Flutter® (experiment B). Sputum properties (viscoelasticity, yield stress, solids content, spinnability, and ease of sputum expectoration), pulmonary diffusing capacity for nitric oxide (DLNO) and carbon monoxide (DLCO) were assessed at rest, directly and 45 min post-exercise (recovery) at 2 consecutive visits. Primary outcome was change in sputum viscoelasticity (G', storage modulus; G", loss modulus) over a broad frequency range (0.1-100 rad.s - 1 ). 15 adults with CF (FEV 1 range 24-94% predicted) completed all experiments. No consistent differences between experiments were observed for G' and G" and other sputum properties, except for ease of sputum expectoration during recovery favoring experiment A. DLNO, DLCO, alveolar volume (V A ) and pulmonary capillary blood volume (V cap ) increased during experiment A, while DLCO and V cap increased during experiment B (all P < 0.05). We found no differences in absolute changes in pulmonary diffusing capacity and its components between experiments, except a higher V A immediately post-exercise favoring experiment A (P = 0.032). The additional use of the Flutter® to moderate intensity interval cycling exercise has no measurable effect on the viscoelastic properties of sputum compared to moderate intensity continuous cycling alone. Elevations in diffusing capacity represent an acute exercise-induced effect not sustained post-exercise. ClinicalTrials.gov; No.: NCT02750722 ; URL: clinical.trials.gov; Registration date: April 25th, 2016.

Defect-Mediated Lithium Adsorption and Diffusion on Monolayer Molybdenum Disulfide.

Science.gov (United States)

Sun, Xiaoli; Wang, Zhiguo; Fu, Y Q

2015-12-22

Monolayer Molybdenum Disulfide (MoS2) is a promising anode material for lithium ion batteries because of its high capacities. In this work, first principle calculations based on spin density functional theory were performed to investigate adsorption and diffusion of lithium on monolayer MoS2 with defects, such as single- and few-atom vacancies, antisite, and grain boundary. The values of adsorption energies on the monolayer MoS2 with the defects were increased compared to those on the pristine MoS2. The presence of defects causes that the Li is strongly bound to the monolayer MoS2 with adsorption energies in the range between 2.81 and 3.80 eV. The donation of Li 2s electron to the defects causes an enhancement of adsorption of Li on the monolayer MoS2. At the same time, the presence of defects does not apparently affect the diffusion of Li, and the energy barriers are in the range of 0.25-0.42 eV. The presence of the defects can enhance the energy storage capacity, suggesting that the monolayer MoS2 with defects is a suitable anode material for the Li-ion batteries.

Research on the effect of culture time on the kombucha tea beverage's antiradical capacity and sensory value.

Science.gov (United States)

Gramza-Michałowska, Anna; Kulczyński, Bartosz; Xindi, Yuan; Gumienna, Małgorzata

2016-01-01

Recent consumption trends shows high consumer acceptability and growing medicinal interest in the biological value of kombucha tea. This tea is a sweetened tea leaf brew fermented with a layer containing mainly acetic acid bacteria, yeast and lactic acid bacteria. The main antioxidants in tea leaves are polyphenols, the consumption of which is proven to be beneficial for human health, e.g. protecting from reactive oxygen species (ROS). The aim of the present research was to evaluate antiradical activity, total polyphenol content (TPC) and sensory value of kombucha tea brews. In the present study, Kombucha tea beverages were analyzed for TPC content, DPPH radical scavenging method and sensory value. The highest TPC content and DPPH radical scavenging capacity values were evaluated in yellow tea samples, both unfermented and kombucha, which did not differ within the storage time. The results of sensory evaluations of kombucha tea brews depend on the tea leaf variety used for preparing the drink. Research indicates that the fermentation process of tea brews with kombucha microbiota does not affect significantly its polyphenol content and antiradical capacity, and retains its components' biological activity.

Evaluating the Value of High Spatial Resolution in National Capacity Expansion Models using ReEDS

Energy Technology Data Exchange (ETDEWEB)

Krishnan, Venkat; Cole, Wesley

2016-07-18

This poster is based on the paper of the same name, presented at the IEEE Power & Energy Society General Meeting, July18, 2016. Power sector capacity expansion models (CEMs) have a broad range of spatial resolutions. This paper uses the Regional Energy Deployment System (ReEDS) model, a long-term national scale electric sector CEM, to evaluate the value of high spatial resolution for CEMs. ReEDS models the United States with 134 load balancing areas (BAs) and captures the variability in existing generation parameters, future technology costs, performance, and resource availability using very high spatial resolution data, especially for wind and solar modeled at 356 resource regions. In this paper we perform planning studies at three different spatial resolutions - native resolution (134 BAs), state-level, and NERC region level - and evaluate how results change under different levels of spatial aggregation in terms of renewable capacity deployment and location, associated transmission builds, and system costs. The results are used to ascertain the value of high geographically resolved models in terms of their impact on relative competitiveness among renewable energy resources.

Apparent diffusion coefficient measurement in glioma: Influence of region-of-interest determination methods on apparent diffusion coefficient values, interobserver variability, time efficiency, and diagnostic ability.

Science.gov (United States)

Han, Xu; Suo, Shiteng; Sun, Yawen; Zu, Jinyan; Qu, Jianxun; Zhou, Yan; Chen, Zengai; Xu, Jianrong

2017-03-01

To compare four methods of region-of-interest (ROI) placement for apparent diffusion coefficient (ADC) measurements in distinguishing low-grade gliomas (LGGs) from high-grade gliomas (HGGs). Two independent readers measured ADC parameters using four ROI methods (single-slice [single-round, five-round and freehand] and whole-volume) on 43 patients (20 LGGs, 23 HGGs) who had undergone 3.0 Tesla diffusion-weighted imaging and time required for each method of ADC measurements was recorded. Intraclass correlation coefficients (ICCs) were used to assess interobserver variability of ADC measurements. Mean and minimum ADC values and time required were compared using paired Student's t-tests. All ADC parameters (mean/minimum ADC values of three single-slice methods, mean/minimum/standard deviation/skewness/kurtosis/the10 th and 25 th percentiles/median/maximum of whole-volume method) were correlated with tumor grade (low versus high) by unpaired Student's t-tests. Discriminative ability was determined by receiver operating characteristic curves. All ADC measurements except minimum, skewness, and kurtosis of whole-volume ROI differed significantly between LGGs and HGGs (all P determination methods. Whole-volume histogram analysis did not yield better results than single-slice methods and took longer. Mean ADC value derived from single-round ROI is the most optimal parameter for differentiating LGGs from HGGs. 3 J. Magn. Reson. Imaging 2017;45:722-730. © 2016 International Society for Magnetic Resonance in Medicine.

The impact of convective drying on the color, phenolic content and antioxidant capacity of noni (Morinda citrifolia L.

Directory of Open Access Journals (Sweden)

Ana Isabel MIRELES-ARRIAGA

Full Text Available Abstract The effect of thin-layer drying temperature on color, phenolic content and antioxidant capacity of noni slices was investigated. Noni slices were air-dried at 50, 60 and 70 °C under natural convection conditions. Drying curves were fitted to thin-layer drying models in order to evaluate the drying characteristics of the product. In addition, an unsteady-state diffusion equation was numerically solved considering both product shrinkage and a variable mass Biot number in boundary condition to accurately estimate water diffusivity in a process with external resistance to mass transfer. Results revealed that the Aghbashlo model accurately reproduced the experimental behavior. As expected, water diffusivities, corrected for shrinkage, increased with the use of higher drying temperatures, with values in the range of 1.80-3.19 to ×10-9 m2/s. On the other hand, while drying caused a reduction in product lightness (24-31% and total phenolic content (20-28%, the antioxidant capacity of dried noni was high (82-93% DPPH inhibition, which is advantageous for the further storage or processing of this fruit.

Task 5. Grid interconnection of building integrated and other dispersed photovoltaic power systems. Grid-connected photovoltaic power systems: power value and capacity value of PV systems

Energy Technology Data Exchange (ETDEWEB)

Groppi, F.

2002-02-15

This report for the International Energy Agency (IEA) made by Task 5 of the Photovoltaic Power Systems (PVPS) programme takes a look at the power value and capacity value of photovoltaic power systems. The mission of the Photovoltaic Power Systems Programme is to enhance the international collaboration efforts which accelerate the development and deployment of photovoltaic solar energy. Task 5 deals with issues concerning grid-interconnection and dispersed PV power systems. This report summarises the results of a study aimed to assess the benefits that may be obtained when distributed PV production systems are present in a low-voltage grid. The basic aspects concerning the power-value and those related to the capacity-value are discussed. Data obtained from simulations are presented and discussed. A simple concept shows that great variation occurs if varying load patterns are taken into account. The power-value of PV generation in the grid varies instant by instant depending on the current level of power production and on the surrounding load conditions. Although the three case-studies considered do not cover all the possibilities of coupling between PV and loads, the results obtained show a good differentiation among users with PV production which leads to interesting conclusions.

Autonomous cars and dynamic bottleneck congestion: The effects on capacity, value of time and preference heterogeneity

NARCIS (Netherlands)

van den Berg, V.A.C.; Verhoef, E.T.

2016-01-01

‘Autonomous cars’ are cars that can drive themselves without human control. Autonomous cars can safely drive closer together than cars driven by humans, thereby possibly increasing road capacity. By allowing drivers to perform other activities in the vehicle, they may reduce the value of travel time

Added value of diffusion-weighted magnetic resonance imaging for the detection of pancreatic fluid collection infection

Energy Technology Data Exchange (ETDEWEB)

Borens, Bruno [Polyclinique Santa Maria, Nice (France); Arvanitakis, Marianna; Eisendrath, Pierre; Toussaint, Emmanuel; Deviere, Jacques [Erasme Hospital, Department of Gastroenterology, Brussels (Belgium); Absil, Julie; Matos, Celso; Bali, Maria Antonietta [Erasme Hospital, Department of Radiology, Brussels (Belgium); El Bouchaibi, Said [Epicura, Ath (Belgium)

2017-03-15

To investigate the added value of diffusion-weighted (DW) magnetic resonance (MR) imaging in the detection of infection in pancreatic fluid collections (PFC). Forty-patients with PFC requiring endoscopic-transmural drainage underwent conventional-MR and DW-MR imaging (b = 1000 s/mm{sup 2}) before endoscopy. MR images were divided into two sets (set1, conventional-MR; set2, conventional-MR, DW-MR and ADC maps) and randomized. Two independent readers performed qualitative and quantitative (apparent diffusion coefficient, ADC) image analysis. Bacteriological analysis of PFC content was the gold standard. Non-parametric tests were used for comparisons. Sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV) and accuracy were calculated for the two sets for both readers. Receiver operating characteristic curves (ROC) were drawn to assess quantitative DW-MR imaging diagnostic performance. For both readers, sensitivity, specificity, NPV, PPV and accuracy for infected PFCs were higher for set2 (P >.05). ADC were lower in infected versus non-infected PFCs (P ≤.031). Minimum ADC cut-off: 1,090 x 10{sup -3} mm{sup 2}/s for reader 1 and 1,012 x 10{sup -3} mm{sup 2}/s for reader 2 (sensitivity and specificity 67 % and 96 % for both readers). Qualitative information provided by DW-MR may help to assess PFCs infection. Infected PFCs show significantly lower ADCs compared to non-infected ones. (orig.)

Added value of diffusion-weighted magnetic resonance imaging for the detection of pancreatic fluid collection infection

International Nuclear Information System (INIS)

Borens, Bruno; Arvanitakis, Marianna; Eisendrath, Pierre; Toussaint, Emmanuel; Deviere, Jacques; Absil, Julie; Matos, Celso; Bali, Maria Antonietta; El Bouchaibi, Said

2017-01-01

To investigate the added value of diffusion-weighted (DW) magnetic resonance (MR) imaging in the detection of infection in pancreatic fluid collections (PFC). Forty-patients with PFC requiring endoscopic-transmural drainage underwent conventional-MR and DW-MR imaging (b = 1000 s/mm"2) before endoscopy. MR images were divided into two sets (set1, conventional-MR; set2, conventional-MR, DW-MR and ADC maps) and randomized. Two independent readers performed qualitative and quantitative (apparent diffusion coefficient, ADC) image analysis. Bacteriological analysis of PFC content was the gold standard. Non-parametric tests were used for comparisons. Sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV) and accuracy were calculated for the two sets for both readers. Receiver operating characteristic curves (ROC) were drawn to assess quantitative DW-MR imaging diagnostic performance. For both readers, sensitivity, specificity, NPV, PPV and accuracy for infected PFCs were higher for set2 (P >.05). ADC were lower in infected versus non-infected PFCs (P ≤.031). Minimum ADC cut-off: 1,090 x 10"-"3 mm"2/s for reader 1 and 1,012 x 10"-"3 mm"2/s for reader 2 (sensitivity and specificity 67 % and 96 % for both readers). Qualitative information provided by DW-MR may help to assess PFCs infection. Infected PFCs show significantly lower ADCs compared to non-infected ones. (orig.)

Comparison of the diagnostic performances of diffusion parameters in diffusion weighted imaging and diffusion tensor imaging of breast lesions

International Nuclear Information System (INIS)

Cakir, Ozgur; Arslan, Arzu; Inan, Nagihan; Anık, Yonca; Sarısoy, Tahsin; Gumustas, Sevtap; Akansel, Gur

2013-01-01

Purpose: To evaluate the diagnostic efficiency of the diffusion parameters measured by conventional diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) for discrimination of malignant breast lesions from benign lesions and the normal breast. Materials and methods: The study included 52 women with 55 breast lesions (30 malignant, 25 benign). DTI and DWI were performed complementary to dynamic contrast MRI at 3T. Apparent diffusion coefficient (ADC) of DWI, mean diffusivity (MD) and fractional anisotropy (FA) values of DTI were measured for lesions and contralateral breast parenchyma in each patient. We used b factors of 0, 50, 850, 1000 and 1500 s/mm 2 for DWI and b 0 and 1000 s/mm 2 for DTI. ADC, MD and FA values were compared between malignant and benign lesions, and the normal parenchyma by univariate and multivariate analyses. Results: Diffusion parameters showed no difference according to menopausal status in the normal breast. ADC and MD values of the malignant lesions were significantly lower than benign lesions and normal parenchyma (p = 0.001). The FA showed no statistical significance. With the cut-off values of ≤1.23 × 10 −3 mm 2 /s (b 0–1000 s/mm 2 ) and ≤1.12 × 10 −3 mm 2 /s (b 0–1500 s/mm 2 ), ADC showed 92.85% and 96.15% sensitivity; 72.22% and 73.52% PPV, respectively. With a cut-off value of ≤1.27 × 10 −3 mm 2 /s (b 1000 s/mm 2 ), MD was 100% sensitive with a PPV of 65.90%. Comparing the diagnostic performance of the parameters in DTI with DWI, we obtained similar efficiency of ADC with b values of 0,1000 and 0,1500 s/mm 2 and MD with a b value of 0, 1000 s/mm 2 (AUC = 0.82 ± 0.07). Conclusion: ADC of DWI and MD of DTI values provide significant discriminative factors for benign and malignant breast lesions. FA measurement was not discriminative. Supported with clinical and dynamic contrast MRI findings, DWI and DTI findings provide significant contribution to the final radiologic decision

Comparison of the diagnostic performances of diffusion parameters in diffusion weighted imaging and diffusion tensor imaging of breast lesions

Energy Technology Data Exchange (ETDEWEB)

Cakir, Ozgur, E-mail: cakirozgur@hotmail.com; Arslan, Arzu, E-mail: arzu.s.arslan@gmail.com; Inan, Nagihan, E-mail: nagihaninan@yahoo.com.tr; Anık, Yonca, E-mail: yoncaanik@yahoo.com; Sarısoy, Tahsin, E-mail: htsarisoy@yahoo.com; Gumustas, Sevtap, E-mail: svtgumustas@yahoo.com; Akansel, Gur, E-mail: gakansel@gmail.com

2013-12-01

Purpose: To evaluate the diagnostic efficiency of the diffusion parameters measured by conventional diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) for discrimination of malignant breast lesions from benign lesions and the normal breast. Materials and methods: The study included 52 women with 55 breast lesions (30 malignant, 25 benign). DTI and DWI were performed complementary to dynamic contrast MRI at 3T. Apparent diffusion coefficient (ADC) of DWI, mean diffusivity (MD) and fractional anisotropy (FA) values of DTI were measured for lesions and contralateral breast parenchyma in each patient. We used b factors of 0, 50, 850, 1000 and 1500 s/mm{sup 2} for DWI and b 0 and 1000 s/mm{sup 2} for DTI. ADC, MD and FA values were compared between malignant and benign lesions, and the normal parenchyma by univariate and multivariate analyses. Results: Diffusion parameters showed no difference according to menopausal status in the normal breast. ADC and MD values of the malignant lesions were significantly lower than benign lesions and normal parenchyma (p = 0.001). The FA showed no statistical significance. With the cut-off values of ≤1.23 × 10{sup −3} mm{sup 2}/s (b 0–1000 s/mm{sup 2}) and ≤1.12 × 10{sup −3} mm{sup 2}/s (b 0–1500 s/mm{sup 2}), ADC showed 92.85% and 96.15% sensitivity; 72.22% and 73.52% PPV, respectively. With a cut-off value of ≤1.27 × 10{sup −3} mm{sup 2}/s (b 1000 s/mm{sup 2}), MD was 100% sensitive with a PPV of 65.90%. Comparing the diagnostic performance of the parameters in DTI with DWI, we obtained similar efficiency of ADC with b values of 0,1000 and 0,1500 s/mm{sup 2} and MD with a b value of 0, 1000 s/mm{sup 2} (AUC = 0.82 ± 0.07). Conclusion: ADC of DWI and MD of DTI values provide significant discriminative factors for benign and malignant breast lesions. FA measurement was not discriminative. Supported with clinical and dynamic contrast MRI findings, DWI and DTI findings provide significant

Evaluating the Value of High Spatial Resolution in National Capacity Expansion Models using ReEDS: Preprint

Energy Technology Data Exchange (ETDEWEB)

Krishnan, Venkat; Cole, Wesley

2016-07-01

Power sector capacity expansion models (CEMs) have a broad range of spatial resolutions. This paper uses the Regional Energy Deployment System (ReEDS) model, a long-term national scale electric sector CEM, to evaluate the value of high spatial resolution for CEMs. ReEDS models the United States with 134 load balancing areas (BAs) and captures the variability in existing generation parameters, future technology costs, performance, and resource availability using very high spatial resolution data, especially for wind and solar modeled at 356 resource regions. In this paper we perform planning studies at three different spatial resolutions--native resolution (134 BAs), state-level, and NERC region level--and evaluate how results change under different levels of spatial aggregation in terms of renewable capacity deployment and location, associated transmission builds, and system costs. The results are used to ascertain the value of high geographically resolved models in terms of their impact on relative competitiveness among renewable energy resources.

Diffusion MRI findings in phenylketonuria

Energy Technology Data Exchange (ETDEWEB)

Sener, R.N. [Dept. of Radiology, Ege Univ. Hospital, Izmir (Turkey)

2003-12-01

Two patients with phenylketonuria were studied who were under dietary control since infancy, and who were mentally normal. Diffusion MRI was obtained using a spin-echo, echo-planar sequence with a gradient strength of 30 mT/m at 1.5 T. A trace sequence (TR=5700 ms, and TE=139 ms) was used, acquired in 22 s. Heavily diffusion-weighted (b=1000 mm{sup 2}/s) images, and the apparent diffusion coefficient (ADC) values from automatically generated ADC maps were studied. There were two different patterns in these two patients, restricted and increased diffusion patterns. Restricted diffusion pattern consisted of high-signal on b=1000 s/mm{sup 2} images with low ADC values ranging from 0.46 to 0.57 x 10{sup -3} mm{sup 2}/s. Increased diffusion pattern consisted of normal b=1000 s/mm{sup 2} images with high ADC values ranging from 1.37 to 1.63 x 10{sup -3} mm{sup 2}/s. It is likely that these values reflected presence of two different histopathological changes in phenylketonuria or reflected different stages of the same disease. (orig.)

Clinical utility of high b-value diffusion-weighted magnetic resonance imaging in post-resuscitative encephalopathy

International Nuclear Information System (INIS)

Kano, Hitoshi; Danjou, Wataru; Yamazaki, Kei

2002-01-01

It is very important to estimate brain functional capacity immediately after successful cardiopulmonary resuscitation (CPR) to determine subsequent treatment strategy and to elucidate the pathophysiology of patients with post-resuscitative encephalopathy. However, computed tomography scanning, electric encephalography and conventional magnetic resonance imaging do not contribute significantly to the assessment of brain functions immediately after CPR. Recently, diffusion-weighted magnetic resonance imaging (DW-MRI) has been applied to the patients with post-resuscitative encephalopathy. However, no papers have described serial clinical and repeated DW-MRI studies of patients during the acute phase of post-resuscitative encephalopathy. Moreover, in some cases, high signal intensity in the cortex after CPR is indistinguishable from normal cortex. Thus, we tried to apply high b-value DW-MRI to estimate the brain function of patients with post-resuscitative encephalopathy. This study was performed on 11 patients with post-resuscitative encephalopathy and 5 healthy volunteers as controls. DW-MRI was performed using GYROSCAN 1.5 Tesla MR imager (Philips) with single-shot echo-planner imaging sequences performed 3 times, first within 24 hours after CPR, second between day 3 to 6, and third more than 7 days after CPR. And we tested the usefulness of DW-MRI at 800, 1000, 1500, 2000 and 3000 in b value. Five patients survived, one fully recovered and four remained in a vegetative state. The other six died with clinical brain death. The first DW-MRI revealed in high signal intensity in the frontal and the parietal lobes in all patients who eventually progressed to a vegetative state or brain death. This result was much more wide-spread in the latter patients, while it was never seen in the patients who recovered fully. The high signal intensity areas increased in follow-up DW-MRI studies. The signal intensity remained high in some parts, while it decreased in other parts with

Clinical utility of high b-value diffusion-weighted magnetic resonance imaging in post-resuscitative encephalopathy

Energy Technology Data Exchange (ETDEWEB)

Kano, Hitoshi; Danjou, Wataru; Yamazaki, Kei [Sapporo City General Hospital (Japan)] (and others)

2002-03-01

It is very important to estimate brain functional capacity immediately after successful cardiopulmonary resuscitation (CPR) to determine subsequent treatment strategy and to elucidate the pathophysiology of patients with post-resuscitative encephalopathy. However, computed tomography scanning, electric encephalography and conventional magnetic resonance imaging do not contribute significantly to the assessment of brain functions immediately after CPR. Recently, diffusion-weighted magnetic resonance imaging (DW-MRI) has been applied to the patients with post-resuscitative encephalopathy. However, no papers have described serial clinical and repeated DW-MRI studies of patients during the acute phase of post-resuscitative encephalopathy. Moreover, in some cases, high signal intensity in the cortex after CPR is indistinguishable from normal cortex. Thus, we tried to apply high b-value DW-MRI to estimate the brain function of patients with post-resuscitative encephalopathy. This study was performed on 11 patients with post-resuscitative encephalopathy and 5 healthy volunteers as controls. DW-MRI was performed using GYROSCAN 1.5 Tesla MR imager (Philips) with single-shot echo-planner imaging sequences performed 3 times, first within 24 hours after CPR, second between day 3 to 6, and third more than 7 days after CPR. And we tested the usefulness of DW-MRI at 800, 1000, 1500, 2000 and 3000 in b value. Five patients survived, one fully recovered and four remained in a vegetative state. The other six died with clinical brain death. The first DW-MRI revealed in high signal intensity in the frontal and the parietal lobes in all patients who eventually progressed to a vegetative state or brain death. This result was much more wide-spread in the latter patients, while it was never seen in the patients who recovered fully. The high signal intensity areas increased in follow-up DW-MRI studies. The signal intensity remained high in some parts, while it decreased in other parts with

Value of diffusion-weighted MR imaging in the diagnosis of Creutzfeldt-Jakob disease

International Nuclear Information System (INIS)

Xu Quangang; Wu Weiping; Huang Dehui; Zhang Jiatang; Lang Senyang; Pu Chuanqiang

2005-01-01

Objective: To assess the diagnosis value of diffusion- weighted imaging (DWI) in Creutzfeldt-Jakob disease (CJD). Methods: 8 cases of sporadic CJD who underwent MRI were reported. 4 cases were definite, 3 cases were probable and 1 case was possible. The sensitivity of DWI and conventional MRI were compared. Results: T 1 WI and T 2 WI revealed no abnormal signals except nonspecific diffuse brain atrophy in 4 cases, whereas DWI detected hyperintense abnormalities in all cases. 2 cases showed linear lesions only in the cerebral cortex, and 6 cases showed lesions in both the cerebral cortex and the striatum. The lesions were symmetric in 5 cases, but were asymmetric in the other 3 cases. Although fluid- attenuated inversion recovery (FLAIR) imaging also showed cortical hyperintensity in 1 case, the high signal changes were more evident and extensive on DWI. Conclusions: The hyperintense changes in the cerebral cortices and/or striata on DWI are considered characteristic of CJD. DWI is more sensitive than conventional MRI in depicting lesions of CJD and may be an essential tool for the early diagnosis of this disease. (authors)

Restricted diffusion of CrEDTA and cyanocobalamine across the exchange vessels in rat hindquarters.

Science.gov (United States)

Haraldsson, B; Rippe, B

1986-07-01

The degree of diffusional restriction of skeletal muscle capillary walls to small solutes was estimated from the permeability surface area products (PS) of CrEDTA (MW = 341) and cyanocobalamine (MW = 1355), using computerized 'on-line' recordings of venous single injection indicator dilution curves. Experiments were performed on isolated perfused maximally vasodilated rat hindquarters during largely isogravimetric conditions and the arrangements allowed for measurements of capillary filtration coefficients (CFC). Extraction of tracer varied markedly as a function of transit time and, furthermore, PS increased with increasing flows, both these phenomena indicating tissue and flow heterogeneity. At maximal flows the disturbing influence of heterogeneity will be minimal and hence the diffusion capacities obtained by extrapolating PS area to infinite flows, so called PS tot values, were considered to give the best estimation of the 'true' capillary diffusion capacities. The value of PS tot was 12.9 +/- 0.5 for CrEDTA and 5.1 +/- 0.3 ml min-1 per 100 g for vitamin B12. The calculated PS tot ratio of 2.59 +/- 0.11 indicates restricted diffusion through equivalent pores of radius 53 A, whereas the ratio of the free diffusion coefficients for these solutes is 1.79. Using PS peak for the calculations (totally neglecting heterogeneity) the pore radius was, however, markedly overestimated. Thus, for a PS-ratio of 1.89 +/- 0.04 for CrEDTA vs. B12 an equivalent pore radius of 300 A was calculated. Also, using PS area (only partly correcting for heterogeneity) overestimated the pore radius (70 A) from a mean PS-ratio of 2.33 +/- 0.05. It was concluded that the equivalent pore radius in rat hindquarter microvascular walls is 53 A or even smaller in essential agreement with data from osmotic transient experiments in the same preparation (r approximately 40 A).

Application value of MR diffusion weighted imaging of apparent diffusion coefficient in diagnosis of breast nodular lesions

International Nuclear Information System (INIS)

Zhu Ping; Wang Yafei; Huang Hao; Liu Qinfang; Chen Yerong; Shan Xiuhong; Tan Jishan

2011-01-01

Objective: To estimate the applications of ADC value and rADC value in the diagnosis of nodular lesions of breasts. Methods: Fifty-two cases with 66 nodular lesions of breasts confirmed by histopathology underwent diffusion-weighted magnetic resonance imaging. Three b values (0, 800 and 1000 s/mm 2 ) were applied. The mean ADC values of the breast nodules, the ADC values of ipsilateral breast (rADC 1 ) and ADC values of contralateral breast (rADC 2 ) were respectively measured. The independent-samples t-test and chi-square test were used for statistical analyses. Results: Of the 52 patients, there were 18 patients with infiltrating ductal carcinoma and 34 patients with fibroadenoma. 50 patients with 64 lesions were examined by DWI. (1) at b = 800 s/mm 2 , the mean ADC values of malignant nodules [(1.01±0.09) × 10 -3 mm 2 /s], rADC 800-1 (0.52±0.07) and rADC 800-2 (0.51±0.06) were lower than that of the benign nodules [ADC value = (1.54±0.28) × 10 -3 mm 2 /s, t=8.217, P 800-1 = 0.77±0.15, t=9.339, P 800-2 =0.76±0.14, t=10.394, P 800-1 and rADC 800-2 were respectively 1.05×10 -3 mm 2 /s, 0.55 and 0.53. The sensitivities of the three methods were 75.0%, 65.0% and 60.0%; the specificities were 100.0%, 95.7% and 97.8%; the positive predictive values were respectively 100.0%, 86.7% and 92.3%; the negative predictive values were 90.2%, 86.3% and 84.9%; the diagnosis accordance rates were respectively 92.4%, 86.4% and 86.4%. (2) at b = 1000 s/mm 2 , the mean ADC values of malignant nodules [(0.93±0.08) × 10 -3 mm 2 /s], rADC 1000-1 (0.53±0.09) and rADC 1000-2 (0.52±0.07) were also lower than that of the benign nodules [ADC value = (1.45±0.28) × 10 -3 mm 2 /s, t=11.844, P 1000-1 =0.75±0.16, t= 5.820, P 1000-2 =0.74±0.15, t=8.082, P 1000-1 and rADC 1000-2 were respectively 0.97×10 -3 mm 2 /S, 0.58, 0.55. The sensitivities were all 70.0%; the specificities were respectively 100.0%, 95.7% and 93.5%; the positive predictive values were 100.0%, 87.5% and 82

Network analysis of surgical innovation: Measuring value and the virality of diffusion in robotic surgery.

Directory of Open Access Journals (Sweden)

George Garas

Full Text Available Existing surgical innovation frameworks suffer from a unifying limitation, their qualitative nature. A rigorous approach to measuring surgical innovation is needed that extends beyond detecting simply publication, citation, and patent counts and instead uncovers an implementation-based value from the structure of the entire adoption cascades produced over time by diffusion processes. Based on the principles of evidence-based medicine and existing surgical regulatory frameworks, the surgical innovation funnel is described. This illustrates the different stages through which innovation in surgery typically progresses. The aim is to propose a novel and quantitative network-based framework that will permit modeling and visualizing innovation diffusion cascades in surgery and measuring virality and value of innovations.Network analysis of constructed citation networks of all articles concerned with robotic surgery (n = 13,240, Scopus® was performed (1974-2014. The virality of each cascade was measured as was innovation value (measured by the innovation index derived from the evidence-based stage occupied by the corresponding seed article in the surgical innovation funnel. The network-based surgical innovation metrics were also validated against real world big data (National Inpatient Sample-NIS®.Rankings of surgical innovation across specialties by cascade size and structural virality (structural depth and width were found to correlate closely with the ranking by innovation value (Spearman's rank correlation coefficient = 0.758 (p = 0.01, 0.782 (p = 0.008, 0.624 (p = 0.05, respectively which in turn matches the ranking based on real world big data from the NIS® (Spearman's coefficient = 0.673;p = 0.033.Network analysis offers unique new opportunities for understanding, modeling and measuring surgical innovation, and ultimately for assessing and comparing generative value between different specialties. The novel surgical innovation metrics

Differential diagnostic value of diffusion weighted imaging on brain abscess and necrotic or cystic brain tumors

International Nuclear Information System (INIS)

Zhang Xiaoya; Yin Jie; Wang Kunpeng; Zhang Jiandang; Liang Biling

2009-01-01

Objective: To investigate the value of diffusion weighted imaging (DWI)on brain abscess and necrotic or cystic brain tumors. Methods: 27 cases with brain abscesses and 33 cases with necrotic or cystic brain tumors (gliomas or metastases) were performed conventional MRI and DWI. Apparent diffusion coefficient (ADC) of region of interest (ROI) was measured and statistically tested. Sensitivity and specificity were calculated and compared with conventional MR and DWI. Results: Hyperintensity signal was seen on most brain abscesses. All necrotic or cystic brain tumors showed hypointensity signal on DWI. There was statistical significance on ADC of them. The sensitivity and specificity of conventional MRI was lower than that of DWI. Conclusion: DWI and ADC were useful in distinguishing brain abscessed from necrotic or cystic brain tumors, which was important in addition to conventional MRI. (authors)

Standard-b-Value Versus Low-b-Value Diffusion-Weighted Imaging in Hepatic Lesion Discrimination: A Meta-analysis.

Science.gov (United States)

Xiong, Hui; Zeng, Yuan-Lin

2016-01-01

We sought to determine the comparative diagnostic performance of standard-b-value (500-1000s/mm) versus low-b-value (≤500 s/mm) diffusion-weighted imaging (DWI) in the discrimination of hepatic lesions. A total of 1775 hepatic malignant lesions and 1120 benign hepatic lesions from 21 studies were included. (1) The global sensitivity was 0.86 (95% confidence interval [CI], 0.847-0.879), the specificity was 0.82 (95% CI, 0.797-0.842), the positive likelihood ratio (PLR) was 6.234 (95% CI, 4.260-9.123), the negative likelihood ratio (NLR) was 0.175 (95% CI, 0.135-0.227), and diagnostic odds ratio (DOR) was 42.836 (95% CI, 24.134-76.031). The area under the curve (AUC) and Q* index were 0.93 and 0.87. Publication bias was not present (P > 0.05). (2)The sensitivity of a subgroup meta-analysis of standard-b-value DWI was 0.858 (95% CI, 0.835-0.880), the specificity was 0.836 (95% CI, 0.807-0.863), the PLR was 6.527 (95% CI, 3.857-11.046), the NLR was 0.168 (95% CI, 0.123-0.239), and the DOR was 49.716 (95% CI, 22.897-107.98). The AUC and Q* index were 0.941 and 0.88. (3)The sensitivity of a subgroup meta-analysis of low-b-value DWI was 0.87 (95% CI, 0.84-0.89), the specificity was 0.80 (95% CI, 0.76-0.83), the PLR was 6.22 (95% CI, 3.29-11.76), the NLR was 0.19 (95% CI, 0.12-0.29), and the DOR was 37.14 (95% CI, 14.80-93.18). The AUC and Q* index were 0.922 and 0.86. Hepatic DWI is useful in differentiating between malignant and benign hepatic lesions. Standard-b-value DWI displayed an overall superior diagnostic accuracy over low-b-value DWI. Further trials needed to determine whether increasing b values beyond 1000 s/mm affects the diagnostic accuracy of hepatic lesion discrimination.

Change in Diffusing Capacity After Radiation as an Objective Measure for Grading Radiation Pneumonitis in Patients Treated for Non-Small-Cell Lung Cancer

Energy Technology Data Exchange (ETDEWEB)

Lopez Guerra, Jose Luis [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Department of Radiation Oncology, Hospitales Universitarios Virgen del Rocio, Seville (Spain); Gomez, Daniel, E-mail: dgomez@mdanderson.org [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Zhuang Yan; Levy, Lawrence B. [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Eapen, George [Department of Pulmonary Medicine, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Liu Hongmei; Mohan, Radhe; Komaki, Ritsuko; Cox, James D.; Liao Zhongxing [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX (United States)

2012-08-01

Purpose: Scoring of radiation pneumonitis (RP), a dose-limiting toxicity after thoracic radiochemotherapy, is subjective and thus inconsistent among studies. Here we investigated whether the extent of change in diffusing capacity of the lung for carbon monoxide (DLCO) after radiation therapy (RT) for non-small-cell lung cancer (NSCLC) could be used as an objective means of quantifying RP. Patients and Methods: We analyzed potential correlations between DLCO and RP in 140 patients who received definitive RT ({>=}60 Gy) with or without chemotherapy for primary NSCLC. All underwent DLCO analysis before and after RT. Post-RT DLCO values within 1 week of the RP diagnosis (Grade 0, 1, 2, or 3) were selected and compared with that individual's preradiation values. Percent reductions in DLCO and RP grade were compared by point biserial correlation in the entire patient group and in subgroups stratified according to various clinical factors. Results: Patients experiencing Grade 0, 1, 2, or 3 RP had median percentage changes in DLCO after RT of 10.7%, 13%, 22.1%, or 35.2%. Percent reduction in DLCO correlated with RP Grade {<=}1 vs. {>=}2 (p = 0.0004). This association held for the following subgroups: age {>=}65 years, advanced stage, smokers, use of chemotherapy, volume of normal lung receiving at least 20 Gy {>=}30%, and baseline DLCO or forced expiratory volume in 1 second {>=}60%. Conclusions: By correlating percent change in DLCO from pretreatment values at the time of diagnosis of RP with RP grade, we were able to identify categories of RP based on the change in DLCO. These criteria provide a basis for an objective scoring system for RP based on change in DLCO.

Initial-boundary value problems for multi-term time-fractional diffusion equations with x-dependent coefficients

OpenAIRE

Li, Zhiyuan; Huang, Xinchi; Yamamoto, Masahiro

2018-01-01

In this paper, we discuss an initial-boundary value problem (IBVP) for the multi-term time-fractional diffusion equation with x-dependent coefficients. By means of the Mittag-Leffler functions and the eigenfunction expansion, we reduce the IBVP to an equivalent integral equation to show the unique existence and the analyticity of the solution for the equation. Especially, in the case where all the coefficients of the time-fractional derivatives are non-negative, by the Laplace and inversion L...

Values of decentralized systems that avoid investments in idle capacity within the wastewater sector: a theoretical justification.

Science.gov (United States)

Wang, Sheng

2014-04-01

In this work, the values of decentralized (onsite) systems that avoid investments in idle capacity within wastewater plans are quantitatively justified using the specific net present value (SNPV) approach. SNPV is a currently proposed criterion in environmental engineering economics that is defined as the net present value of the cost per unit of service or per population equivalent (PE). The SNPV approach was reintroduced with bugs fixed and then applied to the economic analysis of the capital and operating costs of one-stage completed central plants, stage-expanded central plants, and decentralized treatment facilities. The results show that under a demand growth scenario, the central plant will inevitably reach idle capacity, which can be reduced by a staged expansion. However, the staged expansion plan will lose the economies of scale and, hence, is only viable under projections of a low or moderate price inflation rate or high demand growth rate. Onsite treatment systems can theoretically achieve 100% utilization. Assuming that the capital costs per PE of the onsite and central systems are equal, the former is economically favorable in most cases of price inflation as a result of its cost saving on idle capacity. Onsite treatment systems can be viable even though their capital expenditures per PE are higher than that of a comparable centralized option as to a capital investment. This finding suggests wide opening of onsite technology choices. Use of the SNPV showed that average operating expenses of centralized plants decrease as demand growth rates increase as a benefit of economies of scale, whereas those of onsite treatment systems depend only on price inflation. Semi-decentralized systems feature both the financial advantage of the onsite system (capital investment) and the superiority of centralized systems (operation and maintenance); thus, it is worth consideration. The results of this study illustrate not only the value of decentralized systems but

Diffuse Ceiling Ventilation

DEFF Research Database (Denmark)

Zhang, Chen; Yu, Tao; Heiselberg, Per Kvols

cooling capacity, energy saving, low investment cost and low noise level; while the limitations include condensation risk and the limit on the room geometry. Furthermore, the crucial design parameters are summarized and their effects on the system performance are discussed. In addition to the stand...... is not well structured with this system. These become the motivations in developing the design guide. This design guide aims to establish a systematic understanding of diffuse ceiling ventilation and provide assistance in designing of such a system. The guide is targeted at design engineers, architects...... and manufacturers and the users of diffuse ceiling technology. The design guide introduces the principle and key characteristics of room air distribution with diffuse ceiling ventilation. It provides an overview of potential benefit and limitations of this technology. The benefits include high thermal comfort, high...

Can broader diffusion of value-based insurance design increase benefits from US health care without increasing costs? Evidence from a computer simulation model.

Directory of Open Access Journals (Sweden)

R Scott Braithwaite

2010-02-01

Full Text Available BACKGROUND: Evidence suggests that cost sharing (i.e.,copayments and deductibles decreases health expenditures but also reduces essential care. Value-based insurance design (VBID has been proposed to encourage essential care while controlling health expenditures. Our objective was to estimate the impact of broader diffusion of VBID on US health care benefits and costs. METHODS AND FINDINGS: We used a published computer simulation of costs and life expectancy gains from US health care to estimate the impact of broader diffusion of VBID. Two scenarios were analyzed: (1 applying VBID solely to pharmacy benefits and (2 applying VBID to both pharmacy benefits and other health care services (e.g., devices. We assumed that cost sharing would be eliminated for high-value services ($300,000 per life-year. All costs are provided in 2003 US dollars. Our simulation estimated that approximately 60% of health expenditures in the US are spent on low-value services, 20% are spent on intermediate-value services, and 20% are spent on high-value services. Correspondingly, the vast majority (80% of health expenditures would have cost sharing that is impacted by VBID. With prevailing patterns of cost sharing, health care conferred 4.70 life-years at a per-capita annual expenditure of US$5,688. Broader diffusion of VBID to pharmaceuticals increased the benefit conferred by health care by 0.03 to 0.05 additional life-years, without increasing costs and without increasing out-of-pocket payments. Broader diffusion of VBID to other health care services could increase the benefit conferred by health care by 0.24 to 0.44 additional life-years, also without increasing costs and without increasing overall out-of-pocket payments. Among those without health insurance, using cost saving from VBID to subsidize insurance coverage would increase the benefit conferred by health care by 1.21 life-years, a 31% increase. CONCLUSION: Broader diffusion of VBID may amplify benefits from

Reference values for paediatric pulmonary function testing: The Utrecht dataset.

Science.gov (United States)

Koopman, Marije; Zanen, Pieter; Kruitwagen, Cas L J J; van der Ent, Cornelis K; Arets, Hubertus G M

2011-01-01

Since populations evolve, measurement protocols and equipment improve and analysis techniques progress, there is an ongoing need to reassess reference data for pulmonary function tests. Furthermore, reference values for total lung capacity and carbon monoxide diffusion capacity are scarcely available in children. We aimed to provide updated reference equations for most commonly used pulmonary function indices in Caucasian children. In the 'Utrecht Pulmonary Function Reference Data Study' we collected data in Caucasian children aged 2-18 years. We analyzed them using the 'Generalized Additive Models for Location Scale and Shape' (GAMLSS) statistical method. Measurements of interrupter resistance (R(int)) (n = 877), spirometry (n = 1042), body plethysmography (n = 723) and carbon monoxide diffusion/helium dilution (n = 543) were obtained in healthy children. Height (or the natural logarithm of height) and age (or the natural logarithm of age) were both significantly related to most outcome measures. Also sex was a significant determinant, except for RV, RV/TLC, FRC(pleth), Raw(0,5), Raw(tot), R(int) and FEF values. The application of previously published reference equations on the study population resulted in misinterpretation of pulmonary function. These new paediatric reference equations provide accurate estimates of the range of normality for most commonly used pulmonary function indices, resulting in less underdiagnosis and overdiagnosis of pulmonary diseases. Copyright © 2010 Elsevier Ltd. All rights reserved.

Excess Diffuse Light Absorption in Upper Mesophyll Limits CO2 Drawdown and Depresses Photosynthesis.

Science.gov (United States)

Earles, J Mason; Théroux-Rancourt, Guillaume; Gilbert, Matthew E; McElrone, Andrew J; Brodersen, Craig R

2017-06-01

In agricultural and natural systems, diffuse light can enhance plant primary productivity due to deeper penetration into and greater irradiance of the entire canopy. However, for individual sun-grown leaves from three species, photosynthesis is actually less efficient under diffuse compared with direct light. Despite its potential impact on canopy-level productivity, the mechanism for this leaf-level diffuse light photosynthetic depression effect is unknown. Here, we investigate if the spatial distribution of light absorption relative to electron transport capacity in sun- and shade-grown sunflower ( Helianthus annuus ) leaves underlies its previously observed diffuse light photosynthetic depression. Using a new one-dimensional porous medium finite element gas-exchange model parameterized with light absorption profiles, we found that weaker penetration of diffuse versus direct light into the mesophyll of sun-grown sunflower leaves led to a more heterogenous saturation of electron transport capacity and lowered its CO 2 concentration drawdown capacity in the intercellular airspace and chloroplast stroma. This decoupling of light availability from photosynthetic capacity under diffuse light is sufficient to generate an 11% decline in photosynthesis in sun-grown but not shade-grown leaves, primarily because thin shade-grown leaves similarly distribute diffuse and direct light throughout the mesophyll. Finally, we illustrate how diffuse light photosynthetic depression could overcome enhancement in canopies with low light extinction coefficients and/or leaf area, pointing toward a novel direction for future research. © 2017 American Society of Plant Biologists. All Rights Reserved.

Correlation between tissue metabolism and cellularity assessed by standardized uptake value and apparent diffusion coefficient in peritoneal metastasis.

Science.gov (United States)

Yu, Xue; Lee, Elaine Yuen Phin; Lai, Vincent; Chan, Queenie

2014-07-01

To evaluate the correlation between standardized uptake value (SUV) (tissue metabolism) and apparent diffusion coefficient (ADC) (water diffusivity) in peritoneal metastases. Patients with peritoneal dissemination detected on (18)F-fluorodeoxyglucose positron emission tomography combined with computed tomography (FDG-PET/CT) were prospectively recruited for MRI examinations with informed consent and the study was approved by the local Institutional Review Board. FDG-PET/CT, diffusion-weighted imaging (DWI), MRI, and DWI/MRI images were independently reviewed by two radiologists based on visual analysis. SUVmax/SUVmean and ADCmin/ADCmean were obtained manually by drawing ROIs over the peritoneal metastases on FDG-PET/CT and DWI, respectively. Diagnostic characteristics of each technique were evaluated. Pearson's coefficient and McNemar and Kappa tests were used for statistical analysis. Eight patients were recruited for this prospective study and 34 peritoneal metastases were evaluated. ADCmean was significantly and negatively correlated with SUVmax (r = -0.528, P = 0.001) and SUVmean (r = -0.548, P = 0.001). ADCmin had similar correlation with SUVmax (r = -0.508, P = 0.002) and SUVmean (r = -0.513, P = 0.002). DWI/MRI had high diagnostic performance (accuracy = 98%) comparable to FDG-PET/CT, in peritoneal metastasis detection. Kappa values were excellent for all techniques. There was a significant inverse correlation between SUV and ADC. © 2013 Wiley Periodicals, Inc.

Basic consideration of diffusion/perfusion imaging

International Nuclear Information System (INIS)

Tamagawa, Yoichi; Kimura, Hirohiko; Matsuda, Tsuyoshi; Kawamura, Yasutaka; Nakatsugawa, Shigekazu; Ishii, Yasushi; Sakuma, Hajime; Tsukamoto, Tetsuji.

1990-01-01

In magnetic resonance imaging (MRI), microscopic motion of biological system such as molecular diffusion of water and microcirculation of blood in the capillary network (perfusion) has been proposed to cause signal attenuation as an intravoxel incoherent motion (IVIM). Quantitative imaging of the IVIM phenomenon was attempted to generate from a set of spin-echo (SE) sequences with or without sensitization by motion probing gradient (MPG). The IVIM imaging is characterized by a parameter, apparent diffusion coefficient (ADC), which is an integration of both the diffusion and the perfusion factor on voxel-by-voxel basis. Hard ware was adjusted to avoid image artifact mainly produced by eddy current. Feasibility of the method was tested using bottle phantom filled with water at different temperature and acetone, and the calculated ADC values of these media corresponded well with accepted values of diffusion. The method was then applied to biological system to investigate mutual participation of diffusion/perfusion on the ADC value. The result of tumor model born on nude mouse suggested considerable participation of perfusion factor which immediately disappeared after sacrificing the animal. Meanwhile, lower value of sacrificed tissue without microcirculation was suggested to have some restriction of diffusion factor by biological tissue. To substantiate the restriction effect on the diffusion, a series of observation have made on a fiber phantom, stalk of celory with botanical fibers and human brain with nerve fibers, in applying unidirectional MPG along the course of these banch of fiber system. The directional restriction effect of diffusion along the course of fiber (diffusion anisotrophy) was clearly visualized as directional change of ADC value. The present method for tissue characterization by diffusion/perfusion on microscopic level will provide a new insight for evaluation of functional derangement in human brain and other organs. (author)

Comparative Analysis of Signal Intensity and Apparent Diffusion Coefficient at Varying b-values in the Brain : Diffusion Weighted-Echo Planar Image (T2 and FLAIR) Sequence

International Nuclear Information System (INIS)

Oh, Jong Kap; Im, Jung Yeol

2009-01-01

Diffusion-weighted imaging (DWI) has been demonstrated to be a practical method for the diagnosis of various brain diseases such as acute infarction, brain tumor, and white matter disease. In this study, we used two techniques to examine the average signal intensity (SI) and apparent diffusion coefficient (ADC) of the brains of patients who ranged in age from 10 to 60 years. Our results indicated that the average SI was the highest in amygdala (as derived from DWI), whereas that in the cerebrospinal fluid was the lowest. The average ADC was the highest in the cerebrospinal fluid, whereas the lowest measurement was derived from the pons. The average SI and ADC were higher in T 2 -DW-EPI than in FLAIR-DW-EPI. The higher the b-value, the smaller the average difference in both imaging techniques; the lower the b-value, the greater the average difference. Also, comparative analysis of the brains of patients who had experienced cerebral infarction showed no distinct lesion in the general MR image over time. However, there was a high SI in apparent weighted images. Analysis of other brain diseases (e.g., bleeding, acute, subacute, chronic infarction) indicated SI variance in accordance with characteristics of the two techniques. The higher the SI, the lower the ADC. Taken together, the value of SI and ADC in accordance with frequently occurring areas and various brain disease varies based on the b-value and imaging technique. Because they provide additional useful information in the diagnosis and treatment of patients with various brain diseases through signal recognition, the proper imaging technique and b-value are important for the detection and interpretation of subacute stroke and other brain diseases.

The value of routine bone marrow biopsy in patients with diffuse large B-cell lymphoma staged with PET/CT

DEFF Research Database (Denmark)

Alzahrani, M; El-Galaly, T C; Hutchings, M

2016-01-01

BACKGROUND: The added diagnostic and prognostic value of routine bone marrow biopsy (BMB) in patients with diffuse large B-cell lymphoma (DLBCL) undergoing positron emission tomography combined with computed tomography (PET/CT) staging is controversial. PATIENTS AND METHODS: Patients with newly d...

Simulation of gas hydrogen diffusion through partially water saturated mono-modal materials

International Nuclear Information System (INIS)

Boher, C.; Lorente, S.; Frizon, F.; Bart, F.

2012-01-01

Concerning the disposal of nuclear wastes, it is important to design concrete envelopes with pore networks that allow the diffusion of hydrogen towards the outside. This work documents the relationship between geo-polymers, which are materials with a quasi mono-modal pore network, and their gaseous diffusivity capacities. Using a mono-modal material allows studying a specific pore size contribution to gaseous diffusion. The pore network is characterized by mercury porosimetry. These experimental results are used as data in a model named MOHYCAN. The modeling work consists of creating a virtual pore network. Then, water layers are deposited in this network to simulate variable water saturation levels. Finally hydrogen is transported through the virtual network using a combination of ordinary diffusion and Knudsen diffusion. MOHYCAN calculates the hydrogen diffusion coefficient for water saturation degree from 0% to 100%. The impacts of the pore network arrangement or the pore network discretization have been studied. The results are, for a quasi mono-modal material: -) the diffusion coefficient is not sensitive to different virtual pore network arrangement; -) the diffusion coefficient values have a sharp drop at specific water saturation (this is due to the water saturation of the main and unique pore family); -) a 2 pores family based model is sufficient to represent the pore network. Theses observations will not be valid if we consider a material with a large pore size distribution, like cementitious materials

The predictability for the prognosis of breast cancer using the apparent diffusion coefficient value of diffusion weighted 3T MRI and the standardized uptake value of positron emission tomography/CT: Assessment of prognostic factor

International Nuclear Information System (INIS)

Lim, Seong Joo; Kim, Keum Won; Jang, Hye Young; Hwang, Cheol Mog; Kim, Dae Ho; Sohn, Jang Sihn; Kim, Jin Suk; Lee, Jin Yong

2012-01-01

To correlate the apparent diffusion coefficient (ADC) value and peak standardized uptake value (pSUV) with histologic grade and clinical prognostic factors of breast ductal carcinoma. Fifty breast cancers of 49 patients (age range: 37-83 years, mean: 53 years) were studied retrospectively. The breast cancers included 4 ductal carcinoma in situ (DCIS) and 46 invasive ductal carcinomas (IDC). The relationships for both pSUV and ADC values with clinicopathological prognostic factors (age, tumor size, histologic grade, nodal metastasis, hormone receptor and HER-2 neu status) were statistically evaluated. The histologic type of ductal carcinoma include DCIS (n = 4) and IDC (n = 46, grade 1 = 10, grade 2 = 13, and grade 3 = 23). pSUV was associated with histologic grade and tumor size and the ADC value was associated with histologic grade (p < 0.05). As the histologic grade becomes higher, the ADC values decrease, while pSUV and pSUV/ADC increase (p < 0.05). The characterization accuracy of pSUV/ADC (90.2%) was higher than pSUV (86.7%) and ADC values (25.4%) alone for the diagnosis of breast cancer (p < 0.05). pSUV and ADC values correlated with histologic grade, and tumor size. The pSUV/ADC value had a high accuracy for the diagnosis of breast cancer. Therefore, pSUV and ADC values provided additional information for predicting histologic grade and prognosis of breast cancer

Diffusion-weighted MR imaging of the pancreas: optimizing b-value for visualization of pancreatic adenocarcinoma

International Nuclear Information System (INIS)

Fukukura, Yoshihiko; Shindo, Toshikazu; Hakamada, Hiroto; Takumi, Koji; Umanodan, Tomokazu; Nakajo, Masanori; Kamimura, Kiyoshisa; Umanodan, Aya; Ideue, Junnichi; Yoshiura, Takashi

2016-01-01

To determine the optimal b-value of 3.0-T diffusion-weighted imaging (DWI) for visualizing pancreatic adenocarcinomas Fifty-five patients with histologically confirmed pancreatic adenocarcinoma underwent DWI with different b-values (b = 500, 1000, 1500, and 2000 s/mm"2) at 3.0 T. For each b-value, we retrospectively evaluated DWI findings of pancreatic adenocarcinomas (clear hyperintensity relative to the surrounding pancreas, hyperintensity with an unclear distal border, and isointensity) and image quality, and measured tumour-to-pancreas signal intensity (SI) ratios. DWI findings, image quality, and tumour-to-pancreas SI ratios were compared between the four b-values. There was a significantly higher incidence of tumours showing clear hyperintensity on DWI with b-value of 1500 s/mm"2 than on that with b-value of 1000 s/mm"2 (P < 0.001), and on DWI with b-value of 1000 s/mm"2 than on that with b-value of 500 s/mm"2 (P < 0.001). The tumour-to-distal pancreas SI ratio was higher with b-value of 1500 s/mm"2 than with b-value of 1000 s/mm"2 (P < 0.001), and with b-value of 1000 s/mm"2 than with b-value of 500 s/mm"2 (P < 0.001). A lower image quality was obtained at increasing b-values (P < 0.001); the lowest scores were observed with b-value of 2000 s/mm"2. The use of b = 1500 s/mm"2 for 3.0-T DWI can improve the delineation of pancreatic adenocarcinomas. (orig.)

Diffusion-weighted imaging in relation to morphology on dynamic contrast enhancement MRI. The diagnostic value of characterizing non-puerperal mastitis

Energy Technology Data Exchange (ETDEWEB)

Zhang, Lina; Chu, Jianguo; Zhang, Weisheng; Liu, Ailian; Song, Qingwei [First Affiliated Hospital of Dalian Medical University, Department of Radiology, Dalian, Liaoning (China); Hu, Jiani; Guys, Nicholas [Wayne State University, Department of Radiology, Detroit, MI (United States); Meng, Jinli [Chengban Branch of West China Hospital, Department of Radiology, Chengdu, Sichuan (China); Wang, Shaowu [Second Affiliated Hospital of Dalian Medical University, Department of Radiology, Dalian, Liaoning (China)

2018-03-15

To demonstrate the value of diffusion-weighted imaging (DWI) in the characterisation of mastitis lesions. Sixty-one non-puerperal patients with pathologically confirmed single benign mastitis lesions underwent preoperative examinations with conventional MRI and axial DWI. Patients were categorised into three groups: (1) periductal mastitis (PDM), (2) granulomatous lobular mastitis (GLM), and (3) infectious abscess (IAB). Apparent diffusion coefficient (ADC) values of each lesion were recorded. A one-way ANOVA with logistic analysis was performed to compare ADC values and other parameters. Discriminative abilities of DWI modalities were compared using the area under the receiver operating characteristic curve (AUC). P < 0.05 was considered statistically significant. ADC values differed significantly among the three groups (P = 0.003) as well as between PDM and IAB and between PDM and GLM. The distribution of non-mass enhancement on dynamic contrast-enhanced (DCE) MRI differed significantly among the three groups (P = 0.03) but not between any two groups specifically. There were no differences in lesion location, patient age, T{sub 2}WI or DWI signal intensity, enhancement type, non-mass internal enhancement, or mass enhancement characteristics among the three groups. ADC values and the distribution of non-mass enhancement are valuable in classifying mastitis subtypes. (orig.)

Meta-Analysis of the Correlation between Apparent Diffusion Coefficient and Standardized Uptake Value in Malignant Disease.

Science.gov (United States)

Deng, Shengming; Wu, Zhifang; Wu, Yiwei; Zhang, Wei; Li, Jihui; Dai, Na; Zhang, Bin; Yan, Jianhua

2017-01-01

The objective of this meta-analysis is to explore the correlation between the apparent diffusion coefficient (ADC) on diffusion-weighted MR and the standard uptake value (SUV) of 18 F-FDG on PET/CT in patients with cancer. Databases such as PubMed (MEDLINE included), EMBASE, and Cochrane Database of Systematic Review were searched for relevant original articles that explored the correlation between SUV and ADC in English. After applying Fisher's r -to- z transformation, correlation coefficient ( r ) values were extracted from each study and 95% confidence intervals (CIs) were calculated. Sensitivity and subgroup analyses based on tumor type were performed to investigate the potential heterogeneity. Forty-nine studies were eligible for the meta-analysis, comprising 1927 patients. Pooled r for all studies was -0.35 (95% CI: -0.42-0.28) and exhibited a notable heterogeneity ( I 2 = 78.4%; P correlation coefficients of ADC/SUV range from -0.12 (lymphoma, n = 5) to -0.59 (pancreatic cancer, n = 2). We concluded that there is an average negative correlation between ADC and SUV in patients with cancer. Higher correlations were found in the brain tumor, cervix carcinoma, and pancreas cancer. However, a larger, prospective study is warranted to validate these findings in different cancer types.

Turbulent eddy diffusion models in exposure assessment - Determination of the eddy diffusion coefficient.

Science.gov (United States)

Shao, Yuan; Ramachandran, Sandhya; Arnold, Susan; Ramachandran, Gurumurthy

2017-03-01

The use of the turbulent eddy diffusion model and its variants in exposure assessment is limited due to the lack of knowledge regarding the isotropic eddy diffusion coefficient, D T . But some studies have suggested a possible relationship between D T and the air changes per hour (ACH) through a room. The main goal of this study was to accurately estimate D T for a range of ACH values by minimizing the difference between the concentrations measured and predicted by eddy diffusion model. We constructed an experimental chamber with a spatial concentration gradient away from the contaminant source, and conducted 27 3-hr long experiments using toluene and acetone under different air flow conditions (0.43-2.89 ACHs). An eddy diffusion model accounting for chamber boundary, general ventilation, and advection was developed. A mathematical expression for the slope based on the geometrical parameters of the ventilation system was also derived. There is a strong linear relationship between D T and ACH, providing a surrogate parameter for estimating D T in real-life settings. For the first time, a mathematical expression for the relationship between D T and ACH has been derived that also corrects for non-ideal conditions, and the calculated value of the slope between these two parameters is very close to the experimentally determined value. The values of D T obtained from the experiments are generally consistent with values reported in the literature. They are also independent of averaging time of measurements, allowing for comparison of values obtained from different measurement settings. These findings make the use of turbulent eddy diffusion models for exposure assessment in workplace/indoor environments more practical.

Intraparenchymal epidermoid cysts in the brain: diagnostic value of MR diffusion-weighted imaging

Energy Technology Data Exchange (ETDEWEB)

Hu, X.-Y. [Medical Imaging Center, The First Affiliated Hospital of Suzhou, Jiangsu Province (China); Hu, C.-H. [Imaging Center, Soochow University (China)], E-mail: wpdrhxy@hotmail.com; Fang, X.-M.; Cui, L.; Zhang, Q.-H. [Medical Imaging Center, The First Affiliated Hospital of Suzhou, Jiangsu Province (China)

2008-07-15

Aim: To evaluate the value of magnetic resonance (MR) diffusion-weighted imaging (DWI) and apparent diffusion coefficients (ADC) maps in the diagnosis of intraparenchymal epidermoid cysts (ECs). Materials and methods: Six cases of histopathologically proven intraparenchymal ECs were studied. All patients were examined with conventional MR (T1WI, T2WI, contrast-enhanced T1WI) and DWI sequences. Along with the mean ADC values (mADC) of the ECs, the cerebrospinal fluid (CSF) and grey matter (GM) were measured. Qualitative and quantitative assessments, as well as MRI findings, were retrospectively analysed using a double blind method by three radiologists in consensus. Results: Four lesions were located in the cerebellum, among them, one was accompanied by an arachnoid cyst; one huge lesion crossed the parenchyma of the frontal and temporal lobes; the other was located in the left temporal lobe. Two lesions had a homogeneous CSF-like intensity on both T1WI and T2WI. The other four were of mixed-intensity on both T1WI and T2WI. All lesions were strikingly hyperintense on DWI, and iso- or slightly hypointense on ADC (relative to the brain). The mADCs of the ECs were significantly higher than that of GM, but significantly lower than that of CSF. Three cases (3/6) were accurately diagnosed using conventional MR sequences without DWI, but in the remaining three cases, correct diagnosis could only be made with help of DWI. Conclusion: DWI sequences can facilitate the diagnosis of intraparenchymal ECs, thus alerting surgeons of the risk of chemical meningitis at surgery. The MR findings of intraparenchymal ECs are basically as the same as those of extracerebral ECs, but the former is likely to have a mixed signal. The hyperintense signal of ECs on DWI is probably caused by the T2 shine-through effect in tumour tissue.

Amide proton transfer imaging to discriminate between low- and high-grade gliomas: added value to apparent diffusion coefficient and relative cerebral blood volume

Energy Technology Data Exchange (ETDEWEB)

Choi, Yoon Seong; Ahn, Sung Soo; Lee, Seung-Koo [Yonsei University College of Medicine, Department of Radiology and Research Institute of Radiological Science, College of Medicine, Seoul (Korea, Republic of); Chang, Jong Hee; Kang, Seok-Gu [Yonsei University College of Medicine, Department of Neurosurgery, Seoul (Korea, Republic of); Kim, Se Hoon [Yonsei University College of Medicine, Department of Pathology, Seoul (Korea, Republic of); Zhou, Jinyuan [Johns Hopkins University School of Medicine, Division of MRI Research, Department of Radiology, Baltimore, MD (United States)

2017-08-15

To evaluate the added value of amide proton transfer (APT) imaging to the apparent diffusion coefficient (ADC) from diffusion tensor imaging (DTI) and the relative cerebral blood volume (rCBV) from perfusion magnetic resonance imaging (MRI) for discriminating between high- and low-grade gliomas. Forty-six consecutive adult patients with diffuse gliomas who underwent preoperative APT imaging, DTI and perfusion MRI were enrolled. APT signals were compared according to the World Health Organization grade. The diagnostic ability and added value of the APT signal to the ADC and rCBV for discriminating between low- and high-grade gliomas were evaluated using receiver operating characteristic (ROC) analyses and integrated discrimination improvement. The APT signal increased as the glioma grade increased. The discrimination abilities of the APT, ADC and rCBV values were not significantly different. Using both the APT signal and ADC significantly improved discrimination vs. the ADC alone (area under the ROC curve [AUC], 0.888 vs. 0.910; P = 0.007), whereas using both the APT signal and rCBV did not improve discrimination vs. the rCBV alone (AUC, 0.927 vs. 0.923; P = 0.222). APT imaging may be a useful imaging biomarker that adds value to the ADC for discriminating between low- and high-grade gliomas. (orig.)

The clinical value of MR diffusion-weighted imaging in the follow-up observation of hepatocellular carcinoma after transcatheter arterial chemoembolization

International Nuclear Information System (INIS)

Li Zhenwu; Zhang Wei; Sun Lijun; Qi Shun

2010-01-01

Objective: To discuss the clinical value of MR diffusion-weighted imaging (DWI) in the follow-up of hepatocellular carcinoma after transcatheter arterial chemo embolization (TACE). Methods: MR DWI was performed in 16 patients with hepatocellular carcinoma after receiving TACE. The DWI findings were compared with DSA and/or CT signs. The mean apparent diffusion coefficient (ADC) value of each lesion was determined separately, and the mean ADC value of intra-hepatic metastatic lesion was compared with that of the primary lesion. Results: A total of 18 lesions were revealed in DSA, of which satisfactory iodinated oil deposit was seen in 11 (satisfactory group) and poor deposit in 7 (poor group). After TACE, the mean ADC value of normal hepatic parenchyma showed no obvious changes when compared to its preoperative value (t = 0.54, P > 0.05). The mean ADC value obtained in poor group was significantly lower than that obtained in satisfactory group (t = 4.81, P < 0.01). In satisfactory group the preoperative ADC values were higher than the postoperative ones (t = 6.81, P < 0.01), while in poor group no significant difference was found between preoperative and postoperative ADC values. In addition, twelve intra-hepatic metastases were detected on DWI. Statistically significant difference in the mean ADC value existed between the metastatic lesions and the primary lesions (t = 4.61, P < 0.01). Conclusion: DWI is very sensitive in detecting hepatic metastatic lesions and, therefore, can be used to evaluate the therapeutic effect of TACE. (authors)

Diagnostic value of diffusion weighted MRI and ADC in differential diagnosis of cavernous hemangioma of the liver.

Science.gov (United States)

Tokgoz, Ozlem; Unlu, Ebru; Unal, Ilker; Serifoglu, Ismail; Oz, Ilker; Aktas, Elif; Caglar, Emrah

2016-03-01

To investigate the use of diffusion weighted magnetic resonance imaging (DWI) and the apparent diffusion coefficient (ADC) values in the diagnosis of hemangioma. The study population consisted of 72 patients with liver masses larger than 1 cm (72 focal lesions). DWI examination with a b value of 600 s/mm2 was carried out for all patients. After DWI examination, an ADC map was created and ADC values were measured for 72 liver masses and normal liver tissue (control group). The average ADC values of normal liver tissue and focal liver lesions, the "cut-off" ADC values, and the diagnostic sensitivity and specificity of the ADC map in diagnosing hemangioma, benign and malignant lesions were researched. Of the 72 liver masses, 51 were benign and 21 were malignant. Benign lesions comprised 38 hemangiomas and 13 simple cysts. Malignant lesions comprised 9 hepatocellular carcinomas, and 12 metastases. The highest ADC values were measured for cysts (3.782±0.53×10(-3) mm(2)/s) and hemangiomas (2.705±0.63×10(-3) mm(2)/s). The average ADC value of hemangiomas was significantly higher than malignant lesions and the normal control group (p<0.001). The average ADC value of cysts were significantly higher when compared to hemangiomas and normal control group (p<0.001). To distinguish hemangiomas from malignant liver lesions, the "cut-off" ADC value of 1.800×10(-3) mm(2)/s had a sensitivity of 97.4% and a specificity of 90.9%. To distinguish hemangioma from normal liver parenchyma the "cut-off" value of 1.858×10(-3) mm(2)/s had a sensitivity of 97.4% and a specificity of 95.7%. To distinguish benign liver lesions from malignant liver lesions the "cut-off" value of 1.800×10(-3) mm(2)/s had a sensitivity of 96.1% and a specificity of 90.0%. DWI and quantitative measurement of ADC values can be used in differential diagnosis of benign and malignant liver lesions and also in the diagnosis and differentiation of hemangiomas. When dynamic examination cannot distinguish cases with

Citizenship Education: Cultivating a Critical Capacity to Implement Universal Values Nationally

Directory of Open Access Journals (Sweden)

Katarzyna Twarog

2017-04-01

Full Text Available Citizenship and citizenship education face challenges due to globalizing factors affecting modern liberal-democratic states. Earlier models of citizenship, which were based on assimilation into the dominant society, have been challenged by scholars seeking to create a fuller understanding of citizenship more inclusive of diversity. This paper addresses the works of Martha Nussbaum and James A. Banks who present two possibilities for citizenship education: purified patriotism (Nussbaum and transformative citizenship education (Banks. By considering values, identity and the national narrative, this paper compares their views in relation to these topics as well as gives supporting and opposing ideas from other scholars. It concludes by stating that these authors share a common commitment to the need for a critical civic culture, which in turn requires a willingness and openness on the part of all citizens to use their imagination and help foster the critical capacity to think anew. In this way, the traditional dichotomous debate over citizenship, values and identity within the nation and the world might be transformed. By utilizing what Freire refers to as deliberative dialogue, we can foster creative solutions to ensure that universal values of justice, tolerance, recognition and equality are not merely democratic ideals, but are practiced by all individuals and institutions. Furthermore, this paper addresses the need for a teacher training program which would teach educators how to promote and endorse a critical culture through dialogue within the classroom and create citizens who are capable of using their imagination and critical thinking to function cooperatively within a multicultural society.

Change in Diffusing Capacity After Radiation as an Objective Measure for Grading Radiation Pneumonitis in Patients Treated for Non-Small-Cell Lung Cancer

International Nuclear Information System (INIS)

Lopez Guerra, Jose Luis; Gomez, Daniel; Zhuang Yan; Levy, Lawrence B.; Eapen, George; Liu Hongmei; Mohan, Radhe; Komaki, Ritsuko; Cox, James D.; Liao Zhongxing

2012-01-01

Purpose: Scoring of radiation pneumonitis (RP), a dose-limiting toxicity after thoracic radiochemotherapy, is subjective and thus inconsistent among studies. Here we investigated whether the extent of change in diffusing capacity of the lung for carbon monoxide (DLCO) after radiation therapy (RT) for non-small-cell lung cancer (NSCLC) could be used as an objective means of quantifying RP. Patients and Methods: We analyzed potential correlations between DLCO and RP in 140 patients who received definitive RT (≥60 Gy) with or without chemotherapy for primary NSCLC. All underwent DLCO analysis before and after RT. Post-RT DLCO values within 1 week of the RP diagnosis (Grade 0, 1, 2, or 3) were selected and compared with that individual’s preradiation values. Percent reductions in DLCO and RP grade were compared by point biserial correlation in the entire patient group and in subgroups stratified according to various clinical factors. Results: Patients experiencing Grade 0, 1, 2, or 3 RP had median percentage changes in DLCO after RT of 10.7%, 13%, 22.1%, or 35.2%. Percent reduction in DLCO correlated with RP Grade ≤1 vs. ≥2 (p = 0.0004). This association held for the following subgroups: age ≥65 years, advanced stage, smokers, use of chemotherapy, volume of normal lung receiving at least 20 Gy ≥30%, and baseline DLCO or forced expiratory volume in 1 second ≥60%. Conclusions: By correlating percent change in DLCO from pretreatment values at the time of diagnosis of RP with RP grade, we were able to identify categories of RP based on the change in DLCO. These criteria provide a basis for an objective scoring system for RP based on change in DLCO.

Additional value of diffusion-weighted imaging to evaluate multifocal and multicentric breast cancer detected using pre-operative breast MRI

Energy Technology Data Exchange (ETDEWEB)

Song, Sung Eun; Park, Eun Kyung; Cho, Kyu Ran; Cho, Sung Bum [Korea University Anam Hospital, Korea University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Seo, Bo Kyoung [Korea University Ansan Hospital, Korea University College of Medicine, Department of Radiology, Ansan (Korea, Republic of); Woo, Ok Hee [Korea University Guro Hospital, Korea University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Jung, Seung Pil [Korea University Anam Hospital, Korea University College of Medicine, Department of Surgery, Seoul (Korea, Republic of)

2017-11-15

To investigate whether diffusion-weighted imaging (DWI) aids pre-operative dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) to evaluate additional lesions in breast cancer patients. DCE-MRI and DWI were performed on 131 lesions, with available histopathological results. The apparent diffusion coefficient (ADC) of each lesion was measured, and the cut-off value for differentiation between malignant and benign lesions was calculated. A protocol combining the ADC cut-off value with DCE-MRI was validated in a cohort of 107 lesions in 77 patients. When an ADC cut-off value of 1.11 x 10{sup -3} mm{sup 2}/s from the development cohort was applied to the additional lesions in the validation cohort, the specificity increased from 18.9% to 67.6% (P < 0.001), and the diagnostic accuracy increased from 61.7% to 82.2% (P = 0.05), without significant loss of sensitivity (98.6% vs. 90.0%, P = 0.07). The negative predictive values of lesions in the same quadrant had decreased, as had those of lesions ≥1 cm in diameter. The ADC cut-off value in the validation cohort was 1.05 x 10{sup -3} mm{sup 2}/s. Additional implementation of DWI for breast lesions in pre-operative MRI can help to obviate unnecessary biopsies by increasing specificity. However, to avoid missing cancers, clinicians should closely monitor lesions located in the same quadrant or lesions ≥1 cm. (orig.)

Diffusion-weighted MR imaging of the pancreas: optimizing b-value for visualization of pancreatic adenocarcinoma

Energy Technology Data Exchange (ETDEWEB)

Fukukura, Yoshihiko; Shindo, Toshikazu; Hakamada, Hiroto; Takumi, Koji; Umanodan, Tomokazu; Nakajo, Masanori; Kamimura, Kiyoshisa; Umanodan, Aya; Ideue, Junnichi; Yoshiura, Takashi [Kagoshima University Graduate School of Medical and Dental Sciences, Department of Radiology, Kagoshima City (Japan)

2016-10-15

To determine the optimal b-value of 3.0-T diffusion-weighted imaging (DWI) for visualizing pancreatic adenocarcinomas Fifty-five patients with histologically confirmed pancreatic adenocarcinoma underwent DWI with different b-values (b = 500, 1000, 1500, and 2000 s/mm{sup 2}) at 3.0 T. For each b-value, we retrospectively evaluated DWI findings of pancreatic adenocarcinomas (clear hyperintensity relative to the surrounding pancreas, hyperintensity with an unclear distal border, and isointensity) and image quality, and measured tumour-to-pancreas signal intensity (SI) ratios. DWI findings, image quality, and tumour-to-pancreas SI ratios were compared between the four b-values. There was a significantly higher incidence of tumours showing clear hyperintensity on DWI with b-value of 1500 s/mm{sup 2} than on that with b-value of 1000 s/mm{sup 2} (P < 0.001), and on DWI with b-value of 1000 s/mm{sup 2} than on that with b-value of 500 s/mm{sup 2} (P < 0.001). The tumour-to-distal pancreas SI ratio was higher with b-value of 1500 s/mm{sup 2} than with b-value of 1000 s/mm{sup 2} (P < 0.001), and with b-value of 1000 s/mm{sup 2} than with b-value of 500 s/mm{sup 2} (P < 0.001). A lower image quality was obtained at increasing b-values (P < 0.001); the lowest scores were observed with b-value of 2000 s/mm{sup 2}. The use of b = 1500 s/mm{sup 2} for 3.0-T DWI can improve the delineation of pancreatic adenocarcinomas. (orig.)

Evaluation of diffusion parameters of radon in porous material by flow-through diffusion experiment

International Nuclear Information System (INIS)

Chunnan Hsu; Shihchin Tsai; Shihming Liang

1994-01-01

The effectiveness of a material in reducing the fluence rate of Rn from soil was assessed in this study by using a flow-through diffusion experiment to evaluate the diffusion parameters -apparent diffusion coefficient and capacity factor - of radon (Rn) in a porous material. An improved method based on the nonlinear least-squares and Marquardt's method (NLSM method) was proposed to provide more reliable analyses of experimental data than the graphical method. The NLSM method was confirmed by the experimental results to be capable of estimating the diffusion parameters, even if the process was transient. This method was also demonstrated to correlate sufficiently with the results by the conventional method while the process had already reached steady-state. Natural mordenite was employed in this study as a testing material because it has more effective sorption for noble gas than any other earthen material. (author)

Comparative Analysis of Signal Intensity and Apparent Diffusion Coefficient at Varying b-values in the Brain : Diffusion Weighted-Echo Planar Image (T{sub 2} and FLAIR) Sequence

Energy Technology Data Exchange (ETDEWEB)

Oh, Jong Kap [Dept. of Radiology, Cheomdan Medical Center, Gwangju (Korea, Republic of); Im, Jung Yeol [Dept. of Digital Management Information Graduate School of Nambu Univesity, Gwangju (Korea, Republic of)

2009-09-15

Diffusion-weighted imaging (DWI) has been demonstrated to be a practical method for the diagnosis of various brain diseases such as acute infarction, brain tumor, and white matter disease. In this study, we used two techniques to examine the average signal intensity (SI) and apparent diffusion coefficient (ADC) of the brains of patients who ranged in age from 10 to 60 years. Our results indicated that the average SI was the highest in amygdala (as derived from DWI), whereas that in the cerebrospinal fluid was the lowest. The average ADC was the highest in the cerebrospinal fluid, whereas the lowest measurement was derived from the pons. The average SI and ADC were higher in T{sub 2}-DW-EPI than in FLAIR-DW-EPI. The higher the b-value, the smaller the average difference in both imaging techniques; the lower the b-value, the greater the average difference. Also, comparative analysis of the brains of patients who had experienced cerebral infarction showed no distinct lesion in the general MR image over time. However, there was a high SI in apparent weighted images. Analysis of other brain diseases (e.g., bleeding, acute, subacute, chronic infarction) indicated SI variance in accordance with characteristics of the two techniques. The higher the SI, the lower the ADC. Taken together, the value of SI and ADC in accordance with frequently occurring areas and various brain disease varies based on the b-value and imaging technique. Because they provide additional useful information in the diagnosis and treatment of patients with various brain diseases through signal recognition, the proper imaging technique and b-value are important for the detection and interpretation of subacute stroke and other brain diseases.

Identification of the primary motor cortex: value of T2 echo-planar imaging, diffusion-weighted imaging and quantitative apparent diffusion coefficient measurement at 3 T

International Nuclear Information System (INIS)

Dincer, Alp; Erzen, Canan; Oezyurt, Onur; Pamir, M.N.

2010-01-01

To investigate the primary motor cortex (PMC) concerning T2 shortening on T2 echo-planar imaging (EPI-T2) and the double-layer sign on diffusion-weighted imaging (DWI), and also to measure its apparent diffusion coefficient (ADC). 3-T MR DWI was performed in 134 adult volunteers and 64 patients. T2 shortening was graded as hypointense or isointense compared with the signal of the superior frontal cortex (SFC). The double-layer sign of the PMC was graded as present or absent. Both findings (T2 shortening and double-layer sign) were evaluated independently by two authors. ADC of the PMC and the SFC were calculated using manually selected ROIs. T2 shortening was found in 131 adults and 62 patients by author 1 and in 132 adults and 61 patients by author 2 (κ = 0.96 and 0.91). The double-layer sign was found in 131 adults and 61 patients by author 1 and in 127 adults and 58 patients by author 2 (κ = 0.94 and 0.91). ADC values of the PMC and the SFC were different for all subjects (p < 0.01). T2 shortening and/or the double-layer sign on 3-T MR can be used to locate the PMC. The difference in ADC values between PMC and SFC is a distinguishing feature. (orig.)

An homeopathic cure to pure Xenon large diffusion

CERN Document Server

Azevedo, C.D.R.; Freitas, E.D.C.; Gonzalez-Diaz, D.; Monrabal, F.; Monteiro, C.M.B.; dos Santos, J. M. F.; Veloso, J.F.C.A.; Gomez-Cadenas, J. J

2016-02-03

The NEXT neutrinoless double beta decay experiment will use a high- pressure gas electroluminescence-based TPC to search for the decay of Xe-136. One of the main advantages of this technology is the possibility to reconstruct the topology of events with energies close to Qbb. The rejection potential associated to the topology reconstruction is limited by our capacity to prop- erly reconstruct the original path of the electrons in the gas. This reconstruction is limited by different factors that include the geometry of the detector, the density of the sensors in the tracking plane and the separation among them, etc. Ultimately, the resolution is limited by the physics of electron diffusion in the gas. In this paper we present a series of molecular additives that can be used in Xenon gas at very low partial pressure to reduce both longitudinal and transverse diffusion. We will show the results of different Monte-Carlo simulations of electron transport in the gas mixtures from wich we have extracted the value of...

Diffusion tensor imaging in spinal cord compression

International Nuclear Information System (INIS)

Wang, Wei; Qin, Wen; Hao, Nanxin; Wang, Yibin; Zong, Genlin

2012-01-01

Background Although diffusion tensor imaging has been successfully applied in brain research for decades, several main difficulties have hindered its extended utilization in spinal cord imaging. Purpose To assess the feasibility and clinical value of diffusion tensor imaging and tractography for evaluating chronic spinal cord compression. Material and Methods Single-shot spin-echo echo-planar DT sequences were scanned in 42 spinal cord compression patients and 49 healthy volunteers. The mean values of the apparent diffusion coefficient and fractional anisotropy were measured in region of interest at the cervical and lower thoracic spinal cord. The patients were divided into two groups according to the high signal on T2WI (the SCC-HI group and the SCC-nHI group for with or without high signal). A one-way ANOVA was used. Diffusion tensor tractography was used to visualize the morphological features of normal and impaired white matter. Results There were no statistically significant differences in the apparent diffusion coefficient and fractional anisotropy values between the different spinal cord segments of the normal subjects. All of the patients in the SCC-HI group had increased apparent diffusion coefficient values and decreased fractional anisotropy values at the lesion level compared to the normal controls. However, there were no statistically significant diffusion index differences between the SCC-nHI group and the normal controls. In the diffusion tensor imaging maps, the normal spinal cord sections were depicted as fiber tracts that were color-encoded to a cephalocaudal orientation. The diffusion tensor images were compressed to different degrees in all of the patients. Conclusion Diffusion tensor imaging and tractography are promising methods for visualizing spinal cord tracts and can provide additional information in clinical studies in spinal cord compression

Prognostic value of interim FDG-PET in R-CHOP-treated diffuse large B-cell lymphoma : Systematic review and meta-analysis

NARCIS (Netherlands)

Adams, Hugo J A; Kwee, Thomas C.

2016-01-01

This study aimed to systematically review and meta-analyze the prognostic value of interim 18F-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) in diffuse large B-cell lymphoma (DLBCL) patients treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone

Thermal conductivities and diffusivities of rocks in four shallow ONKALO holes and drillholes OL-KR46 and OL-KR56

International Nuclear Information System (INIS)

Korpisalo, A.; Suppala, I.; Kukkonen, I.; Koskinen, T.

2013-11-01

The thermal drillhole device (76 mm drillholes) used in this study for determining thermal properties of rocks in situ was developed and constructed under TERO projects in Geological Survey of Finland with Posiva in early 2000's. After the renovation of the device in 2010, the new TERO76 device has now been taken into the productive use. In addition to the numerical inversion technique a rapid interpretation tool makes it possible to calculate the first estimates of thermal properties of the measurements already in the field. The thermal properties of the measurements are estimated by using both a numerical optimization and a simple solution of infinite line model. Because of the unique measurement geometry only the thermal conductivities can directly be estimated accurately (5 %) using the late times of heating periods. The methods can't directly give the thermal diffusivities or heat capacities at a necessary accuracy. However, thermal diffusivities can be estimated by using the specific heat capacities and densities of the known rock types or the laboratory results on diffusivity-conductivity relationship of different Olkiluoto rock types. The latter technique is applied in this study. Thermal properties were measured in four shallow ONKALO drillholes (ONK-PP379, ONK-PP380, ONK-PP381, ONK-PP382) in the Demonstration tunnel 2 (ONK-TDT-4399-30) at +420 m level and in deep drillholes OL-KR46 and OL-KR56 from the surface. In the drillholes in tunnel, the average numerical values fall within 3.31 and 4.19 Wm - 1 K- 1 for the conductivities and 1.75-2.26 x 10 -6 m 2 s -1 for the diffusivities. The corresponding analytical values are within 3.19-3.99 Wm -1 K -1 and 1.68-2.15 x 10 -6 m 2 s -1 . In drillholes OL-KR46 and OL-KR56, the average numerical values fall within 3.42-4.06 and 3.30-3.77 Wm -1 K -1 for the conductivities and 1.81-2.18 and 1.75-2.02 x 10 -6 m 2 s -1 for the diffusivities. The corresponding average analytical conductivities fall within 3.22-3.81 and

Meta-Analysis of the Correlation between Apparent Diffusion Coefficient and Standardized Uptake Value in Malignant Disease

Directory of Open Access Journals (Sweden)

Shengming Deng

2017-01-01

Full Text Available The objective of this meta-analysis is to explore the correlation between the apparent diffusion coefficient (ADC on diffusion-weighted MR and the standard uptake value (SUV of 18F-FDG on PET/CT in patients with cancer. Databases such as PubMed (MEDLINE included, EMBASE, and Cochrane Database of Systematic Review were searched for relevant original articles that explored the correlation between SUV and ADC in English. After applying Fisher’s r-to-z transformation, correlation coefficient (r values were extracted from each study and 95% confidence intervals (CIs were calculated. Sensitivity and subgroup analyses based on tumor type were performed to investigate the potential heterogeneity. Forty-nine studies were eligible for the meta-analysis, comprising 1927 patients. Pooled r for all studies was −0.35 (95% CI: −0.42–0.28 and exhibited a notable heterogeneity (I2 = 78.4%; P < 0.01. In terms of the cancer type subgroup analysis, combined correlation coefficients of ADC/SUV range from −0.12 (lymphoma, n = 5 to −0.59 (pancreatic cancer, n = 2. We concluded that there is an average negative correlation between ADC and SUV in patients with cancer. Higher correlations were found in the brain tumor, cervix carcinoma, and pancreas cancer. However, a larger, prospective study is warranted to validate these findings in different cancer types.

Emotion and Value in the Evaluation of Medical Decision-Making Capacity: A Narrative Review of Arguments.

Science.gov (United States)

Hermann, Helena; Trachsel, Manuel; Elger, Bernice S; Biller-Andorno, Nikola

2016-01-01

Ever since the traditional criteria for medical decision-making capacity (understanding, appreciation, reasoning, evidencing a choice) were formulated, they have been criticized for not taking sufficient account of emotions or values that seem, according to the critics and in line with clinical experiences, essential to decision-making capacity. The aim of this paper is to provide a nuanced and structured overview of the arguments provided in the literature emphasizing the importance of these factors and arguing for their inclusion in competence evaluations. Moreover, a broader reflection on the findings of the literature is provided. Specific difficulties of formulating and measuring emotional and valuational factors are discussed inviting reflection on the possibility of handling relevant factors in a more flexible, case-specific, and context-specific way rather than adhering to a rigid set of operationalized criteria.

Regional diffusion changes of cerebral grey matter during normal aging-A fluid-inversion prepared diffusion imaging study

International Nuclear Information System (INIS)

Ni Jianming; Chen Shuang; Liu Jianjun; Huang Gang; Shen Tianzhen; Chen Xingrong

2010-01-01

Background and purpose: Although diffusion characteristics of white matter (WM) and its aging effects have been well described in the literature, diffusion characteristics of grey matter (GM), especially the cortical GM, have not been fully evaluated. In the present study, we used the fluid-inversion prepared diffusion imaging (FLIPD) technique to determine if there are age-related water diffusivity changes in GM. Materials and methods: 120 healthy volunteers were recruited for our study. They were divided into three age groups: group one (20-39 years old), group two (40-59 years old) and group three (60 years or older). All patients were evaluated with MRI using FLIPD at 3.0 T. Apparent diffusion coefficient (ADC) values of the frontal GM, cingulate cortex and thalami were determined bilaterally by region-of-interest analysis. Results: Group three had significantly higher ADC values in both thalami and the left frontal GM compared to group two or group one. No ADC value difference was found among the three groups in the right frontal GM and bilateral cingulate cortex. There was a significant positive correlation between individual ADC values and age in both thalami and left frontal GM. For the cingulate cortex and the right frontal GM, ADC values did not correlate significantly with advancing age. Conclusion: Statistically significant age-related diffusion changes were observed in both thalami and the left frontal cortex. The data reported here may serve as a reference for future studies.

A systematic determination of diffusion coefficients of trace elements in open and restricted diffusive layers used by the diffusive gradients in a thin film technique

DEFF Research Database (Denmark)

Shiva, Amir Houshang; Teasdale, Peter R.; Bennett, William W.

2015-01-01

A systematic comparison of the diffusion coefficients of cations (Al, Cd, Co, Cu, Mn, Ni, Pb, Zn) and oxyanions (Al, As, Mo, Sb, V, W) in open (ODL) and restricted (RDL) diffusive layers used by the DGT technique was undertaken. Diffusion coefficients were measured using both the diffusion cell...... concentrations required with the Dcell measurements. This is the first time that D values have been reported for several oxyanions using RDL. Except for Al at pH 8.30 with ODL, all DDGT measurements were retarded relative to diffusion coefficients in water (DW) for both diffusive hydrogels. Diffusion in RDL...

The application value of diffusion-weighted magnetic resonance imaging in gross tumor volume delineation of esophageal squamous cell carcinoma

International Nuclear Information System (INIS)

Hou Dongliang; Shi Gaofeng; Gao Xianshu

2012-01-01

Objective: To analyze the application value of diffusion-weighted magnetic resonance imaging (DWMRI) in gross tumor volume (GTV) delineation of esophageal squamous cell carcinoma (SCC). Methods: Twenty-nine patients with esophageal SCC treated with radical surgery were analyzed. Routine CT scan, MRI T 2 -weighted and DWMRI were employed before surgery; diffusion-sensitive gradient b-values were taken 400, 600 and 800 s/mm 2 . GTVs were delineated using CT, MRI T 2 -weighted images and DWMRI under different b-value images. The length of GTVs measured under different images was compared with the pathological length and confirm the most accurate imaging condition. Use radiotherapy planning system to fuse DWMRI images and CT images to investigate the possibility of delineate GTVs on fused images. Results: The difference of GTV length value between CT, T 2 WI images and specimen was 3.36 mm and 2.84 mm. When b =400,600 and 800 s/mm 2 , the difference between GTV length value on the DWMRI images and on specimen was 0.47 mm, -0.47 mm and - 1.53 mm; the correlation coefficient of the measuring esophageal lengths on DWMRI images and the pathological lengths was 0.928, 0.927 and 0.938. DWMRI images and CT images could fuse accurately on radiotherapy planning system. GTV margin could.show clearly on fused images. Conclusions: DWMRI images can display the esophageal carcinoma lengths and margin accurately. When DWMRI images fused with CT images, GTV margin could show clearly,it can be used to delineate GTV accurately. (authors)

[Carbon monoxide tests in a steady state. Uptake and transfer capacity, normal values and lower limits].

Science.gov (United States)

Ramonatxo, M; Préfaut, C; Guerrero, H; Moutou, H; Bansard, X; Chardon, G

1982-01-01

The aim of this study was to establish data which would best demonstrate the variations of different tests using Carbon Monoxide as a tracer gas (total and partial functional uptake coefficient and transfer capacity) to establish mean values and lower limits of normal of these tests. Multivariate statistical analysis was used; in the first stage a connection was sought between the fractional uptake coefficient (partial and total) to other parameters, comparing subjects and data. In the second stage the comparison was refined by eliminating the least useful data, trying, despite a small loss of material, to reveal the most important connections, linear or otherwise. The fractional uptake coefficients varied according to sex, also the variation of the partial alveolar-expired fractional uptake equivalent (DuACO) was largely a function of respiratory rate and tidal volume. The alveolar-arterial partial fractional uptake equivalent (DuaCO) depended more on respiratory frequency and age. Finally the total fractional uptake coefficient (DuCO) and the transfer capacity corrected per liter of ventilation (TLCO/V) were functions of these parameters. The last stage of this work, after taking account of the statistical observations consistent with the facts of these physiological hypotheses led to a search for a better way of approaching the laws linking the collected data to the fractional uptake coefficient. The lower limits of normal were arbitrarily defined, separating those 5% of subjects deviating most strongly from the mean. As a result, the relationship between the lower limit of normal and the theoretical mean value was 90% for the partial and total fractional uptake coefficient and 70% for the transfer capacity corrected per liter of ventilation.

Median nerve cross-sectional area and MRI diffusion characteristics: normative values at the carpal tunnel

International Nuclear Information System (INIS)

Yao, Lawrence; Gai, Neville

2009-01-01

Enlargement of the median nerve is an objective potential imaging sign of carpal tunnel syndrome. Diffusion tensor MRI (DTI) may provide additional structural information that may prove useful in characterizing median neuropathy. This study further examines normal values for median nerve cross-sectional area (CSA), apparent diffusion coefficient (ADC), and fractional anisotropy (FA). Twenty-three wrists in 17 healthy volunteers underwent MRI of the wrist at 3 T. In 13 subjects, DTI was performed at a B value of 600 mm 2 /s. Median nerve CSA, ADC, and FA were analyzed at standardized anatomic levels. Mean (SD) median nerve CSA within the proximal carpal tunnel was 10.0 (3.4) mm 2 . The mean (SD) FA of the median nerve was 0.71 (0.06) and 0.70 (0.13) proximal to and within the carpal tunnel, respectively. There was a significant difference between nerve CSA and ADC, but not FA, at the distal forearm and proximal carpal tunnel. Nerve CSA, ADC, and FA did not differ between men and women or between dominant and non-dominant wrists. Nerve CSA at the proximal carpal tunnel was positively correlated with subject age and body mass index. Our results suggest a 90% upper confidence limit for normal median nerve CSA of 14.4 mm 2 at the proximal carpal tunnel, higher than normal limits reported by many ultrasound studies. We observed a difference between the CSA and ADC, but not the FA, of the median nerve at the distal forearm and proximal carpal tunnel levels. (orig.)

Left ventricular assist device: exercise capacity evolution and rehabilitation added value.

Science.gov (United States)

Lamotte, Michel X; Chimenti, Sara; Deboeck, Gael; Gillet, Alexis; Kacelenenbogen, Raymond; Strapart, Jonathan; Vandeneynde, Frédéric; Van Nooten, Guido; Antoine, Martine

2018-06-01

With more than 15,000 implanted patients worldwide and a survival rate of 80% at 1-year and 59% at 5-years, left ventricular assist device (LVAD) implantation has become an interesting strategy in the management of heart failure patients who are resistant to other kinds of treatment. There are limited data in the literature on the change over time of exercise capacity in LVAD patients, as well as limited knowledge about the beneficial effects that rehabilitation might have on these patients. Therefore, the aim of our study was to evaluate the evolution of exercise capacity on a cohort of patients implanted with the same device (HeartWare © ) and to analyse the potential impact of rehabilitation. Sixty-two patients implanted with a LVAD between June 2011 and June 2015 were screened. Exercise capacity was evaluated by cardiopulmonary exercise testing at 6 weeks, 6 and 12 months after implantation. We have observed significant differences in the exercise capacity and evolution between the trained and non-trained patients. Some of the trained patients nearly normalised their exercise capacity at the end of the rehabilitation programme. Exercise capacity of patient implanted with a HeartWare © LVAD increased in the early period after implantation. Rehabilitation allowed implanted patients to have a significantly better evolution compared to non-rehabilitated patients.

Clinical relevance of the apparent diffusion coefficient value of metastatic bone tumours on diffusion-weighted MRI images: differences according to the types of primary tumour, the affected bones, and clinical factors.

Science.gov (United States)

Cha, M J; Yoon, Y C

2015-10-01

To evaluate whether the apparent diffusion coefficient (ADC) of metastatic bone tumours on diffusion-weighted magnetic resonance imaging (MRI) images differs according to the type of primary cancer, the affected bone, and clinical factors. For this retrospective study, two radiologists reviewed MRI images, including ADC maps, of 67 patients (M:F=38:29; median age, 48 years) who were diagnosed with bone metastasis by means of histological or clinical confirmation. The primary tumours included 29 lung adenocarcinomas, 15 invasive ductal adenocarcinomas of the breast, 13 hepatocellular carcinomas, six prostatic carcinomas, and four renal cell carcinomas. ADC values of the metastatic tumour were compared according to the type of primary malignancy, the affected bone, and the age and sex of the patient using Kruskal-Wallis and Mann-Whitney U-tests with Bonferroni correction. In addition, pre-contrast CT images were available in 38 of 67 patients; a subanalysis of the CT radiodensity and ADC values were performed with Spearman correlation. The mean, standard deviation, and minimum and maximum values of the ADC of metastatic bone tumours did not differ significantly according to type of primary malignancy, the affected bone, or clinical variables (p>0.1). The ADC value was not significantly correlated with CT radiodensity (p=0.24). Intra- and interobserver agreements for the mean ADC values were excellent (intra-observer: p=0.98; interobserver: p=0.98). Assessment of the ADC value of metastatic bone tumours is not reliable for differentiation of the type of primary cancer. Copyright © 2015 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Disorder effect on heat capacity, self-diffusion coefficient, and choosing best potential model for melting temperature, in gold–copper bimetallic nanocluster with 55 atoms

International Nuclear Information System (INIS)

Taherkhani, Farid; Akbarzadeh, Hamed; Feyzi, Mostafa; Rafiee, Hamid Reza

2015-01-01

Molecular dynamics simulation has been implemented for doping effect on melting temperature, heat capacity, self-diffusion coefficient of gold–copper bimetallic nanostructure with 55 total gold and copper atom numbers and its bulk alloy. Trend of melting temperature for gold–copper bimetallic nanocluster is not same as melting temperature copper–gold bulk alloy. Molecular dynamics simulation of our result regarding bulk melting temperature is consistence with available experimental data. Molecular dynamics simulation shows that melting temperature of gold–copper bimetallic nanocluster increases with copper atom fraction. Semi-empirical potential model and quantum Sutton–Chen potential models do not change melting temperature trend with copper doping of gold–copper bimetallic nanocluster. Self-diffusion coefficient of copper atom is greater than gold atom in gold–copper bimetallic nanocluster. Semi-empirical potential within the tight-binding second moment approximation as new application potential model for melting temperature of gold–copper bulk structure shows better result in comparison with EAM, Sutton–Chen potential, and quantum Sutton–Chen potential models

Disorder effect on heat capacity, self-diffusion coefficient, and choosing best potential model for melting temperature, in gold–copper bimetallic nanocluster with 55 atoms

Energy Technology Data Exchange (ETDEWEB)

Taherkhani, Farid, E-mail: faridtaherkhani@gmail.com, E-mail: f.taherkhani@razi.ac.ir [Razi University, Department of Physical Chemistry (Iran, Islamic Republic of); Akbarzadeh, Hamed [Hakim Sabzevari University, Department of Chemistry (Iran, Islamic Republic of); Feyzi, Mostafa; Rafiee, Hamid Reza [Razi University, Department of Physical Chemistry (Iran, Islamic Republic of)

2015-01-15

Molecular dynamics simulation has been implemented for doping effect on melting temperature, heat capacity, self-diffusion coefficient of gold–copper bimetallic nanostructure with 55 total gold and copper atom numbers and its bulk alloy. Trend of melting temperature for gold–copper bimetallic nanocluster is not same as melting temperature copper–gold bulk alloy. Molecular dynamics simulation of our result regarding bulk melting temperature is consistence with available experimental data. Molecular dynamics simulation shows that melting temperature of gold–copper bimetallic nanocluster increases with copper atom fraction. Semi-empirical potential model and quantum Sutton–Chen potential models do not change melting temperature trend with copper doping of gold–copper bimetallic nanocluster. Self-diffusion coefficient of copper atom is greater than gold atom in gold–copper bimetallic nanocluster. Semi-empirical potential within the tight-binding second moment approximation as new application potential model for melting temperature of gold–copper bulk structure shows better result in comparison with EAM, Sutton–Chen potential, and quantum Sutton–Chen potential models.

Some theoretical aspects of capacity increment in gaseous diffusion

Energy Technology Data Exchange (ETDEWEB)

Coates, J. H.; Guais, J. C.; Lamorlette, G.

1975-09-01

Facing to the sharply growing needs of enrichment services, the problem of implementing new capacities must be included in an optimized scheme spread out in time. In this paper the alternative solutions will be studied first for an unique increment decision, and then in an optimum schedule. The limits of the analysis will be discussed.

Validity of apparent diffusion coefficient hyperpolarized 3He-MRI using MSCT and pulmonary function tests as references

DEFF Research Database (Denmark)

Diaz, Sandra; Casselbrant, Ingrid; Piitulainen, Eeva

2008-01-01

PURPOSE: To compare apparent diffusion coefficient (ADC) measurements from hyperpolarized (HP) helium ((3)He)-magnetic resonance imaging (MRI) with quantitative data from multislice Computed Tomography (CT) (MSCT) of the whole lungs and pulmonary function tests (PFT). MATERIALS AND METHODS: Twenty......-seven subjects, 22 with established emphysema and 5 with preclinical emphysema defined by PFT criteria, were examined with HP (3)He-MRI and MSCT. Mean age was 55 (+/-12) years, 18 female and 9 male. Mean ADC from (3)He-MRI was compared with emphysema index (EI), 15th percentile and mean lung density (MLD) values...... from MSCT. Both mean ADC and MSCT data were compared to PFT, especially percent of predicted diffusing capacity of carbon monoxide (%predicted DLCO), using Pearson's correlation test. RESULTS: Mean ADC and standard deviation values were 0.392+/-0.119 cm(2)/s for the established emphysema group and 0...

The added value of advanced neuro-imaging (MR diffusion ...

African Journals Online (AJOL)

Introduction: Primary CNS lymphoma is difficult to diagnose with conventional imaging modalities. Magnetic resonance proton spectroscopy, dynamic susceptibility contrast DSC perfusion and diffusion weighted images have been recently investigated as a problem-solving tool for evaluation of primary CNS lymphoma with ...

Diffusion-weighted MR and apparent diffusion coefficient in the evaluation of severe brain injury

International Nuclear Information System (INIS)

Nakahara, M.; Ericson, K.; Bellander, B.M.

2001-01-01

Purpose: To study apparent diffusion coefficient (ADC) maps in severely brain-injured patients. Material and Methods: Four deeply comatose patients with severe brain injury were investigated with single-shot, diffusion-weighted, spin-echo echo planar imaging. The tetrahedral diffusion gradient configuration and four iterations of a set of b-values (one time of 0 mm2/s, and four times of 1000 mm2/s) were used to create isotropic ADC maps with high signal-to-noise ratio. ADC values of gray and white matter were compared among patients and 4 reference subjects. Results: one patient was diagnosed as clinically brain dead after the MR examination. The patient's ADC values of gray and white matter were significantly lower than those of 3 other brain-injured patients. In addition the ADC value of white matter was significantly lower than that of gray matter. Conclusion: The patient with fatal outcome shortly after MR examination differed significantly from other patients with severe brain injury but non-fatal outcome, with regard to ADC values in gray and white matter. This might indicate a prognostic value of ADC maps in the evaluation of traumatic brain injury

Investigation of a phantom for diffusion weighted imaging that controlled the apparent diffusion coefficient using gelatin and sucrose

International Nuclear Information System (INIS)

Tamura, Takayuki; Usui, Shuji; Akiyama, Mitoshi

2009-01-01

When studying diffusion weighted imaging (DWI), it is important to create a phantom that has a reliably controlled diffusion coefficient. In this study, we investigated phantoms to control both the diffusion coefficient and the T2-value by changing the concentration of gelatin or sucrose and MnCl 2 , respectively. The results showed that the diffusion coefficient decreased linearly with increases in the gelatin or sucrose concentration, and decreasing of their relaxation times was observed. By properly adjusting the MnCl 2 concentrations, we were able to equalize the T2-values between phantoms having different gelatin or sucrose concentrations. Temperature dependence of the diffusion coefficient was also revealed. This phantom can be made stable for a few months by adding a small amount of NaN 3 as an antiseptic agent, has a diffusion coefficient similar to that of neural tissue or clinical tumor, and is able to control the T2-value properly. We consider this phantom suitable for studying SE-type DWI and contributes to elucidation of this technique. (author)

Pulmonary hypertension in patients with idiopathic pulmonary fibrosis - the predictive value of exercise capacity and gas exchange efficiency.

Directory of Open Access Journals (Sweden)

Sven Gläser

Full Text Available Exercise capacity and survival of patients with IPF is potentially impaired by pulmonary hypertension. This study aims to investigate diagnostic and prognostic properties of gas exchange during exercise and lung function in IPF patients with or without pulmonary hypertension. In a multicentre setting, patients with IPF underwent right heart catheterization, cardiopulmonary exercise and lung function testing during their initial evaluation. Mortality follow up was evaluated. Seventy-three of 135 patients [82 males; median age of 64 (56; 72 years] with IPF had pulmonary hypertension as assessed by right heart catheterization [median mean pulmonary arterial pressure 34 (27; 43 mmHg]. The presence of pulmonary hypertension was best predicted by gas exchange efficiency for carbon dioxide (cut off ≥152% predicted; area under the curve 0.94 and peak oxygen uptake (≤56% predicted; 0.83, followed by diffusing capacity. Resting lung volumes did not predict pulmonary hypertension. Survival was best predicted by the presence of pulmonary hypertension, followed by peak oxygen uptake [HR 0.96 (0.93; 0.98]. Pulmonary hypertension in IPF patients is best predicted by gas exchange efficiency during exercise and peak oxygen uptake. In addition to invasively measured pulmonary arterial pressure, oxygen uptake at peak exercise predicts survival in this patient population.

Comparison between total lung capacity and residual volume values obtained by pletysmography and single breath methods with methane

Directory of Open Access Journals (Sweden)

Ricardo Marques Dias

2006-11-01

Full Text Available We analyzed pulmonary function tests of twenty asthmatic patients from Gaffrée e Guinle University Hospital, classified according to Brazilian Guidelines for Asthma (2002, similar to GINA, into mild persistent or moderate (9 or severe (11 asthma. We obtained parameters from spirometry, plethysmograph(PL and single breath technique for diffusion capacity (SB, with methane. Total lung capacity and residual volume were called TLCPL and RVPL when measured by pletysmography and TLCSB and RVSB when determined by single breath test. There were 13 women and 7 men with mean age of 47.6 years. The pulmonary dysfunction degree to FEV1/FVC was 58.8% with CI95=53.9 to 63.6. The mean values in litres for TLCPL (5.94 and RVPL (2.55 were significantly higher than for TLCSB (4.73 and RVSB (1.66. Multiple regression equations were determined for TLCPL e RVPL using only single breath values, TLCSB or RVSB, and spirographic parameters, with significant regression coefficients. However, the inclusion of spirometric parameters, except for FVC, did not improve the predicted capacity for the equations. Considering only the TLCSB, r2=0.79, the equation is: TLCPL=(TLCSB*1.025+1.088, with EPE=0.64. The regression for RVPL, r2=0.23, is: RVPL=(RVSB*0.9268+1.012. The results obtained after bronchodilation with 400 mcg of salbutamol did not improve the regression. We concluded that the SB technique did not obtain the same results as pletysmography for TLC and RV, but for TLC this difference can be predicted. Resumo: Foram analisados exames de função pulmonar de 20 asmáticos, em acompanhamento no HU Gaffrée Guinle, classificados, segundo o Consenso Brasileiro (2002, em asma leve persistente ou moderada (9 e grave (11. Foram obtidos os valores dos parâmetros da espirografia, da pletismografia e da técnica de respiração única, com metano, para a medida da difusão pulmonar (DLco. Assim, a capacidade pulmonar total e o volume residual, quando

The value of the apparent diffusion coefficient in MR diffusion weighted imaging for the differential diagnosis of sinonasal masses

International Nuclear Information System (INIS)

Wang Yongzhe; Yang Bentao; Xian Junfang; Li Jing; Chen Guangli

2014-01-01

Objective: To investigate the diagnostic value of apparent diffusion coefficient in the evaluation of sinonasal masses. Methods: Sixty-seven sinonasal solid masses over 1 cm in diameter confirmed by pathology were retrospectively analyzed, all patients underwent preoperative routine MRI with DWI, the ADC values were measured in ROI within the solid mass. The patients were divided into benign and malignant groups by the histopathology, according to pathological findings, the patients were further divided into the hematolymphoid tumors, the malignancy of epithelium and mesenchymal tissue, the benign tumors of epithelial and mesenchymal tissue, and vasogenic masses. ANOVA test and t test were used to compare the ADC values of different groups. The receiver operating characteristic curve (ROC) was constructed using various cut points of ADC for different parameters to confirm the diagnostic threshold value and evaluate the diagnostic efficacy. Results: All lesions were solitary. There were 22 malignant tumors, of which 6 lesions were hematolymphoid tumors and 16 lesions malignancy from epithelium and mesenchymal tissue. There were 45 benign tumors, of which 22 lesions were benign tumors from epithelium and mesenchymal tissue and 23 lesions vasogenic masses. The mean ADC value of malignant and benign masses was (0.88 ± 0.26) × 10 -3 mm 2 /s and (1.54 ± 0.41) × 10 -3 mm 2 /s respectively. There was statistically significant differences between them (t=6.897, P <0.01). The mean ADC value was(0.63 ± 0.10) × 10 -3 mm 2 /s in hematolymphoid tumors,(0.97 ±0.24) × 10 -3 mm 2 /s in malignancy from epithelium and mesenchymal tissue, (1.38 ± 0.23) × 10 -3 mm 2 /s in benign tumors from epithelium and mesenchymal tissue,(1.68 ± 0.49) × 10 -3 mm 2 /s in vasogenic masses respectively. There was statistically significant difference among all 4 groups(F=22.788, P<0.01), and the differences between any 2 groups were still statistically significant (P <0.05). The area under

EMOTION AND VALUE IN THE EVALUATION OF MEDICAL DECISION-MAKING CAPACITY: A NARRATIVE REVIEW OF ARGUMENTS

Directory of Open Access Journals (Sweden)

Helena eHermann

2016-05-01

Full Text Available Ever since the traditional criteria for medical decision-making capacity (understanding, appreciation, reasoning, evidencing a choice were formulated, they have been criticized for not taking sufficient account of emotions or values that seem, according to the critics and in line with clinical experiences, essential to decision-making capacity. The aim of this paper is to provide a nuanced and structured overview of the arguments provided in the literature emphasizing the importance of these factors and arguing for their inclusion in competence evaluations. Moreover, a broader reflection on the findings of the literature is provided. Specific difficulties of formulating and measuring emotional and valuational factors are discussed inviting reflection on the possibility of handling relevant factors in a more flexible, case-specific, and context-specific way rather than adhering to a rigid set of operationalized criteria.

Diffusive transport of strontium-85 in sand-bentonite mixtures

International Nuclear Information System (INIS)

Gillham, R.W.; Robin, M.J.L.; Dytynyshyn, D.J.

1983-06-01

Diffusion experiments have been used to determine the transport of 85 Sr in sand-bentonite mixtures. The diffusion experiments were performed on one natural soil (Chalk River sand) and on seven mixtures of bentonite and silica sand, containing from 0 percent to 100 percent bentonite. Two non-reactive solutes ( 36 Cl and 3 H) and one reactive solute ( 85 Sr) were used in the study. The experiments with non-reactive solutes yielded estimates of tortuosity factors. Retardation factors were obtained from experimental porosities, experimental bulk densities, and from batch distribution coefficients (Ksub(d)). These Ksub(d) values are a simple way of describing the solute/medium reaction, and are based on the assumption that the cation-exchange reaction may be described by a linear adsorption isotherm passing through the origin. The results demonstrate that, for practical purposes and for our experimental conditions, the use of the distribution coefficient provides a convenient means of calculating the effective diffusion coefficient for 85 Sr. The porosity and bulk density were also found to have a considerable influence on the effective diffusion coefficient, through the retardation factor. Mixtures containing 5-10 percent bentonite were found to be more effective in retarding 85 Sr than either sand alone, or mixtures containing more bentonite. In the soils of higher bentonite content, the effect of increased cation-exchange capacity was balanced by a decreasing ratio of bulk density to porosity

Differences in Gaussian diffusion tensor imaging and non-Gaussian diffusion kurtosis imaging model-based estimates of diffusion tensor invariants in the human brain.

Science.gov (United States)

Lanzafame, S; Giannelli, M; Garaci, F; Floris, R; Duggento, A; Guerrisi, M; Toschi, N

2016-05-01

An increasing number of studies have aimed to compare diffusion tensor imaging (DTI)-related parameters [e.g., mean diffusivity (MD), fractional anisotropy (FA), radial diffusivity (RD), and axial diffusivity (AD)] to complementary new indexes [e.g., mean kurtosis (MK)/radial kurtosis (RK)/axial kurtosis (AK)] derived through diffusion kurtosis imaging (DKI) in terms of their discriminative potential about tissue disease-related microstructural alterations. Given that the DTI and DKI models provide conceptually and quantitatively different estimates of the diffusion tensor, which can also depend on fitting routine, the aim of this study was to investigate model- and algorithm-dependent differences in MD/FA/RD/AD and anisotropy mode (MO) estimates in diffusion-weighted imaging of human brain white matter. The authors employed (a) data collected from 33 healthy subjects (20-59 yr, F: 15, M: 18) within the Human Connectome Project (HCP) on a customized 3 T scanner, and (b) data from 34 healthy subjects (26-61 yr, F: 5, M: 29) acquired on a clinical 3 T scanner. The DTI model was fitted to b-value =0 and b-value =1000 s/mm(2) data while the DKI model was fitted to data comprising b-value =0, 1000 and 3000/2500 s/mm(2) [for dataset (a)/(b), respectively] through nonlinear and weighted linear least squares algorithms. In addition to MK/RK/AK maps, MD/FA/MO/RD/AD maps were estimated from both models and both algorithms. Using tract-based spatial statistics, the authors tested the null hypothesis of zero difference between the two MD/FA/MO/RD/AD estimates in brain white matter for both datasets and both algorithms. DKI-derived MD/FA/RD/AD and MO estimates were significantly higher and lower, respectively, than corresponding DTI-derived estimates. All voxelwise differences extended over most of the white matter skeleton. Fractional differences between the two estimates [(DKI - DTI)/DTI] of most invariants were seen to vary with the invariant value itself as well as with MK

Effects of MR parameter changes on the quantification of diffusion anisotropy and apparent diffusion coefficient in diffusion tensor imaging: Evaluation using a diffusional anisotropic phantom

Energy Technology Data Exchange (ETDEWEB)

Kim, Sang Joon; Choi, Choong Gon; Kim, Jeong Kon [Dept. of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea, Republic of); Yun, Sung Cheol [Dept. of Biostatistics, University of Ulsan College of Medicine, Seoul (Korea, Republic of); Jeong, Ha Kyu [Dept. of Radiology, East-West Neomedical Center, Kyung Hee University College of Medicine, Seoul (Korea, Republic of); Kim, Eun Ju [Clinical Scientist, MR, Philips Healthcare, Seoul (Korea, Republic of)

2015-04-15

To validate the usefulness of a diffusional anisotropic capillary array phantom and to investigate the effects of diffusion tensor imaging (DTI) parameter changes on diffusion fractional anisotropy (FA) and apparent diffusion coefficient (ADC) using the phantom. Diffusion tensor imaging of a capillary array phantom was performed with imaging parameter changes, including voxel size, number of sensitivity encoding (SENSE) factor, echo time (TE), number of signal acquisitions, b-value, and number of diffusion gradient directions (NDGD), one-at-a-time in a stepwise-incremental fashion. We repeated the entire series of DTI scans thrice. The coefficients of variation (CoV) were evaluated for FA and ADC, and the correlation between each MR imaging parameter and the corresponding FA and ADC was evaluated using Spearman's correlation analysis. The capillary array phantom CoVs of FA and ADC were 7.1% and 2.4%, respectively. There were significant correlations between FA and SENSE factor, TE, b-value, and NDGD, as well as significant correlations between ADC and SENSE factor, TE, and b-value. A capillary array phantom enables repeated measurements of FA and ADC. Both FA and ADC can vary when certain parameters are changed during diffusion experiments. We suggest that the capillary array phantom can be used for quality control in longitudinal or multicenter clinical studies.

Prognostic Value of the Apparent Diffusion Coefficient in Newborns with Hypoxic-Ischaemic Encephalopathy Treated with Therapeutic Hypothermia.

Science.gov (United States)

Heursen, Eva-Marie; Zuazo Ojeda, Amaya; Benavente Fernández, Isabel; Jimenez Gómez, Gema; Campuzano Fernández-Colima, Rosalía; Paz-Expósito, José; Lubián López, Simón Pedro

2017-01-01

Apparent diffusion coefficient (ADC) quantification has been proven to be of prognostic value in term newborns with hypoxic-ischaemic encephalopathy (HIE) who were treated under normothermia. To evaluate the prognostic value of ADC in standardized brain regions in neonates with HIE who were treated with therapeutic hypothermia (TH). This prospective cohort study included 54 term newborns who were admitted with HIE and treated with TH. All magnetic resonance imaging examinations were performed between days 4 and 6 of life, and ADC values were measured in 13 standardized regions of the brain. At 2 years of age we explored whether ADC values were related to composite outcomes (death or survival with abnormal neurodevelopment). The severity of HIE is inversely related to ADC values in different brain regions. We found that lower ADC values in the posterior limb of the internal capsule (PLIC), the thalami, the semioval centre, and frontal and parietal white matter were related to adverse outcomes. ADC values in the PLIC and thalami are good predictors of adverse outcomes (AUC 0.86 and 0.76). Low ADC values in the PLIC, thalamus, semioval centre, and frontal and parietal white matter in full-term infants with HIE treated with TH were associated with a poor outcome. © 2017 S. Karger AG, Basel.

Prediction of pancreatic neuroendocrine tumour grade with MR imaging features: added value of diffusion-weighted imaging

Energy Technology Data Exchange (ETDEWEB)

Lotfalizadeh, Emad; Vullierme, Marie-Pierre; Allaham, Wassim [University Hospitals Paris Nord Val de Seine, Department of Radiology, Clichy, Hauts-de-Seine (France); Ronot, Maxime; Vilgrain, Valerie [University Hospitals Paris Nord Val de Seine, Department of Radiology, Clichy, Hauts-de-Seine (France); University Paris Diderot, Paris (France); INSERM U1149, Centre de Recherche Biomedicale Bichat-Beaujon, CRB3, Paris (France); Wagner, Mathilde [University Hospitals Paris Nord Val de Seine, Department of Radiology, Clichy, Hauts-de-Seine (France); INSERM U1149, Centre de Recherche Biomedicale Bichat-Beaujon, CRB3, Paris (France); Cros, Jerome; Couvelard, Anne [University Paris Diderot, Paris (France); University Hospitals Paris Nord Val de Seine, Department of Pathology, Clichy, Hauts-de-Seine (France); Hentic, Olivia; Ruzniewski, Philippe [University Hospitals Paris Nord Val de Seine, Department of Gastroenterology, Clichy, Hauts-de-Seine (France)

2017-04-15

To evaluate the value of MR imaging including diffusion-weighted imaging (DWI) for the grading of pancreatic neuroendocrine tumours (pNET). Between 2006 and 2014, all resected pNETs with preoperative MR imaging including DWI were included. Tumour grading was based on the 2010 WHO classification. MR imaging features included size, T1-w, and T2-w signal intensity, enhancement pattern, apparent (ADC) and true diffusion (D) coefficients. One hundred and eight pNETs (mean 40 ± 33 mm) were evaluated in 94 patients (48 women, 51 %, mean age 52 ± 12). Fifty-five (51 %), 42 (39 %), and 11 (10 %) tumours were given the following grades (G): G1, G2, and G3. Mean ADC and D values were significantly lower as grade increased (ADC: 2.13 ± 0.70, 1.78 ± 0.72, and 0.86 ± 0.22 10{sup -3} mm{sup 2}/s, and D: 1.92 ± 0.70, 1.75 ± 0.74, and 0.82 ± 0.19 10{sup -3} mm{sup 2}/s G1, G2, and G3, all p < 0.001). A higher grade was associated with larger sized tumours (p < 0.001). The AUROC of ADC and D to differentiate G3 and G1-2 were 0.96 ± 0.02 and 0.95 ± 0.02. Optimal cut-off values for the identification of G3 were 1.19 10{sup -3} mm{sup 2}/s for ADC (sensitivity 100 %, specificity 92 %) and 1.04 10{sup -3} mm{sup 2}/s for D (sensitivity 82 %, specificity 92 %). Morphological/functional MRI features of pNETS depend on tumour grade. DWI is useful for the identification of high-grade tumours. (orig.)

Effects of exercise training on coronary transport capacity

International Nuclear Information System (INIS)

Laughlin, M.H.

1985-01-01

Coronary transport capacity was estimated in eight sedentary control and eight exercise-trained anesthetized dogs by determining the differences between base line and the highest coronary blood flow and permeability-surface area product (PS) obtained during maximal adenosine vasodilation with coronary perfusion pressure constant. The anterior descending branch of the left coronary artery was cannulated and pump- perfused under constant-pressure conditions (approximately equal to 100 Torr) while aortic, central venous, and coronary perfusion pressures, heart rate, electrocardiogram, and coronary flow were monitored. Myocardial extraction and PS of 51 Cr-labeled ethylenediaminetetraacetic acid were determined with the single-injection indicator-diffusion method. The efficacy of the 16 +/- 1 wk exercise training program was shown by significant increases in the succinate dehydrogenase activities of the gastrocnemius, gluteus medialis, and long head of triceps brachii muscles. There were no differences between control and trained dogs for either resting coronary blood flow or PS. During maximal vasodilation with adenosine, the trained dogs had significantly lower perfusion pressures with constant flow and, with constant-pressure vasodilation, greater coronary blood flow and PS. It is concluded that exercise training in dogs induces an increased coronary transport capacity that includes increases in coronary blood flow capacity (26% of control) and capillary diffusion capacity (82% of control)

Hidden Wholesale: The drug diffusing capacity of online drug cryptomarkets

OpenAIRE

Aldridge, Judith A; Décary-Hétu, David

2016-01-01

Background: In spite of globalizing processes ‘offline’ retail drug markets remain localized and – in recent decades – typically ‘closed’, in which dealers sell primarily to known customers. We characterize drug cryptomarkets as ‘anonymous open’ marketplaces that allow the diffusion of drugs across locales. Where cryptomarket customers make stock-sourcing purchases for offline distribution, the cryptomarket may indirectly serve drug users who are not themselves cryptomarket customers, thereby...

Diffusion-weighted imaging (b value = 1500 s/mm(2)) is useful to decrease false-positive breast cancer cases due to fibrocystic changes.

Science.gov (United States)

Ochi, Miho; Kuroiwa, Toshiro; Sunami, Shunya; Murakami, Junji; Miyahara, Shinichiro; Nagaie, Takashi; Oya, Masafumi; Yabuuchi, Hidetake; Hatakenaka, Masamitsu

2013-04-01

We aimed to evaluate the application of apparent diffusion coefficient (ADC) values calculated from diffusion-weighted imaging (DWI) (b value = 1500 s/mm(2)) in the breast imaging reporting and data system (BI-RADS). For 104 cases of breast lesions with definitive histology diagnosis (45 benign cases, 59 malignant cases) in which breast magnetic resonance imaging was performed, ADC values were compared between benign and malignant cases, between ductal carcinoma in situ (DCIS) and fibrocystic changes, and between DCIS and ductal hyperplasia (one type of fibrocystic change). Diagnostic accuracy was compared for a total of 101 images and for 34 images including only nine DCIS and 25 fibrocystic changes between BI-RADS alone (with categories 4a, 4b, and 5 defined as malignancies) and BI-RADS plus ADC. There were significant differences in mean ADC values between malignant and benign cases (p fibrocystic changes (p fibrocystic changes (40.9% for BI-RADS alone, 64.3% for BI-RADS plus ADC), resulting in a significant improvement in diagnostic accuracy with the addition of ADC. Adding ADC values calculated from DWI (b value = 1500 s/mm(2)) to BI-RADS is a useful way to improve differential diagnostic accuracy for malignant tumors and benign lesions, especially for DCIS versus fibrocystic changes, except in cases of ductal hyperplasia.

Models of diffuse solar radiation

Energy Technology Data Exchange (ETDEWEB)

Boland, John; Ridley, Barbara [Centre for Industrial and Applied Mathematics, University of South Australia, Mawson Lakes Boulevard, Mawson Lakes, SA 5095 (Australia); Brown, Bruce [Department of Statistics and Applied Probability, National University of Singapore, Singapore 117546 (Singapore)

2008-04-15

For some locations both global and diffuse solar radiation are measured. However, for many locations, only global is measured, or inferred from satellite data. For modelling solar energy applications, the amount of radiation on a tilted surface is needed. Since only the direct component on a tilted surface can be calculated from trigonometry, we need to have diffuse on the horizontal available. There are regression relationships for estimating the diffuse on a tilted surface from diffuse on the horizontal. Models for estimating the diffuse radiation on the horizontal from horizontal global that have been developed in Europe or North America have proved to be inadequate for Australia [Spencer JW. A comparison of methods for estimating hourly diffuse solar radiation from global solar radiation. Sol Energy 1982; 29(1): 19-32]. Boland et al. [Modelling the diffuse fraction of global solar radiation on a horizontal surface. Environmetrics 2001; 12: 103-16] developed a validated model for Australian conditions. We detail our recent advances in developing the theoretical framework for the approach reported therein, particularly the use of the logistic function instead of piecewise linear or simple nonlinear functions. Additionally, we have also constructed a method, using quadratic programming, for identifying values that are likely to be erroneous. This allows us to eliminate outliers in diffuse radiation values, the data most prone to errors in measurement. (author)

Correlation between apparent diffusion coefficients and standardized uptake values in hybrid {sup 18}F-FDG PET/MR: Preliminary results in rectal cancer

Energy Technology Data Exchange (ETDEWEB)

Jeong, Ju Hye [Dept. of Nuclear Medicine, Kyungpook National University Hospital, Daegu (Korea, Republic of); Cho, Ihn Ho; Chun, Kyung Ah; Kong, Eun Jung; Kwon, Sang Don; Kim, Jae Hwang [Yeungnam University Hospital, Daegu (Korea, Republic of)

2016-06-15

Fluorine-18-fluorodeoxyglucose ({sup 18}F-FDG) positron emission tomography (PET) and diffusion-weighted magnetic resonance imaging (DWI) share the same role in clinical oncology and it is feasible to obtain the standardized uptake value (SUV) and apparent diffusion coefficient (ADC) simultaneously by emerging the hybrid positron emission tomography/magnetic resonance (PET/MR). This study investigated the correlation between the ADCs of rectal cancer lesions and their SUVs derived from hybrid PET/MR. Nine patients with histologically proven rectal adenocarcinoma (5 men, 4 women; mean age, 70 ± 15.91 years) underwent torso {sup 18}F-FDG PET/CT and regional hybrid {sup 18}F-FDG PET/MR sequentially. A fixed threshold value of 40 % of maximum uptake was used to determine tumor volume of interest (VOI) on PET image; SUV{sub max}, SUV{sub peak}, and SUV{sub mean} were calculated automatically. A single freehand region of interest (ROI) was drawn on high b-value (b1000) DWI image and copied to corresponding ADC map to determine the ADCmean of rectal cancer lesion. Spearman'rank correlation coefficient (ρ) was calculated to determine the correlation between SUVs and ADC values. SUV{sub max}, SUV{sub peak}, and SUV{sub mean} derived by hybrid PET/MR were 12.35 ± 4.66 (mean ± standard deviation), 9.66  ± 3.15 and 7.41 ± 2.54, respectively. The ADCmean value of rectal cancer lesions was 1.02 ± 0.08 × 10{sup -3}mm{sup 2}/s. ADCmean was significantly and inversely correlated with SUV values (SUV{sub max}, ρ = -0.95, p < 0.001; SUV{sub peak}, ρ = -0.93, p < 0.001; SUV{sub mean}, ρ = -0.91, p = 0.001). This preliminary hybrid PET/MR study demonstrates a significant inverse correlation exists between metabolic activity on {sup 18}F-FDG PET and water diffusion on DWI in rectal cancer.

Intravoxel Incoherent Motion and Quantitative Non-Gaussian Diffusion MR Imaging: Evaluation of the Diagnostic and Prognostic Value of Several Markers of Malignant and Benign Breast Lesions.

Science.gov (United States)

Iima, Mami; Kataoka, Masako; Kanao, Shotaro; Onishi, Natsuko; Kawai, Makiko; Ohashi, Akane; Sakaguchi, Rena; Toi, Masakazu; Togashi, Kaori

2018-05-01

Purpose To investigate the performance of integrated approaches that combined intravoxel incoherent motion (IVIM) and non-Gaussian diffusion parameters compared with the Breast Imaging and Reporting Data System (BI-RADS) to establish multiparameter thresholds scores or probabilities by using Bayesian analysis to distinguish malignant from benign breast lesions and their correlation with molecular prognostic factors. Materials and Methods Between May 2013 and March 2015, 411 patients were prospectively enrolled and 199 patients (allocated to training [n = 99] and validation [n = 100] sets) were included in this study. IVIM parameters (flowing blood volume fraction [fIVIM] and pseudodiffusion coefficient [D*]) and non-Gaussian diffusion parameters (theoretical apparent diffusion coefficient [ADC] at b value of 0 sec/mm 2 [ADC 0 ] and kurtosis [K]) by using IVIM and kurtosis models were estimated from diffusion-weighted image series (16 b values up to 2500 sec/mm 2 ), as well as a synthetic ADC (sADC) calculated by using b values of 200 and 1500 (sADC 200-1500 ) and a standard ADC calculated by using b values of 0 and 800 sec/mm 2 (ADC 0-800 ). The performance of two diagnostic approaches (combined parameter thresholds and Bayesian analysis) combining IVIM and diffusion parameters was evaluated and compared with BI-RADS performance. The Mann-Whitney U test and a nonparametric multiple comparison test were used to compare their performance to determine benignity or malignancy and as molecular prognostic biomarkers and subtypes of breast cancer. Results Significant differences were found between malignant and benign breast lesions for IVIM and non-Gaussian diffusion parameters (ADC 0 , K, fIVIM, fIVIM · D*, sADC 200-1500, and ADC 0-800 ; P < .05). Sensitivity and specificity for the validation set by radiologists A and B were as follows: sensitivity, 94.7% and 89.5%, and specificity, 75.0% and 79.2% for sADC 200-1500 , respectively; sensitivity, 94.7% and 96.1%, and

Spatial Mapping of Translational Diffusion Coefficients Using Diffusion Tensor Imaging: A Mathematical Description.

Science.gov (United States)

Shetty, Anil N; Chiang, Sharon; Maletic-Savatic, Mirjana; Kasprian, Gregor; Vannucci, Marina; Lee, Wesley

2014-01-01

In this article, we discuss the theoretical background for diffusion weighted imaging and diffusion tensor imaging. Molecular diffusion is a random process involving thermal Brownian motion. In biological tissues, the underlying microstructures restrict the diffusion of water molecules, making diffusion directionally dependent. Water diffusion in tissue is mathematically characterized by the diffusion tensor, the elements of which contain information about the magnitude and direction of diffusion and is a function of the coordinate system. Thus, it is possible to generate contrast in tissue based primarily on diffusion effects. Expressing diffusion in terms of the measured diffusion coefficient (eigenvalue) in any one direction can lead to errors. Nowhere is this more evident than in white matter, due to the preferential orientation of myelin fibers. The directional dependency is removed by diagonalization of the diffusion tensor, which then yields a set of three eigenvalues and eigenvectors, representing the magnitude and direction of the three orthogonal axes of the diffusion ellipsoid, respectively. For example, the eigenvalue corresponding to the eigenvector along the long axis of the fiber corresponds qualitatively to diffusion with least restriction. Determination of the principal values of the diffusion tensor and various anisotropic indices provides structural information. We review the use of diffusion measurements using the modified Stejskal-Tanner diffusion equation. The anisotropy is analyzed by decomposing the diffusion tensor based on symmetrical properties describing the geometry of diffusion tensor. We further describe diffusion tensor properties in visualizing fiber tract organization of the human brain.

Peritoneal transport in CAPD patients with permanent loss of ultrafiltration capacity

International Nuclear Information System (INIS)

Heimbuerger, O.W.; Waniewski, J.; Werynski, A.; Tranaeus, A.; Lindholm, B.

1990-01-01

During a 10 year period, 14 out of 227 patients (6.2%) undergoing continuous ambulatory peritoneal dialysis (CAPD) developed permanent loss of ultrafiltration capacity (UFC). The risk of UFC loss increased from 2.6% after one year to 30.9% after six years of treatment. A six hour, single dwell study with glucose 3.86% dialysis fluid was carried out in nine of the UFC loss patients and in 18 CAPD patients with normal UFC. Intraperitoneal dialysate volumes were calculated using 131I-tagged albumin (RISA) as volume marker with a correction applied for its elimination from the peritoneal cavity. The RISA elimination coefficient (KE), which can serve as an estimation of the upper limit of the lymphatic flow, was also calculated. Diffusive mass transport coefficients (KBD) for investigated solutes (glucose, creatinine, urea, potassium, total protein, albumin and beta 2-microglobulin) were calculated during a period of dialysate isovolemia. Two patterns of UFC loss were observed: (a) seven patients had high KBD values for small solutes resulting in rapid uptake of glucose, whereas KBD values for proteins were normal; (b) two patients had normal KBD values but a threefold increase both in the fluid reabsorption rate and KE. We conclude that loss of the osmotic driving force (due to increased diffusive mass transport for small solutes) and increased fluid reabsorption (possibly due to increased lymphatic reabsorption) are the two major causes of permanent loss of UFC in CAPD patients

Functional evaluation of hydronephrosis by diffusion-weighted MR imaging: Relationship between apparent diffusion coefficient and split glomerular filtration rate

International Nuclear Information System (INIS)

Toyoshima, S.; Noguchi, K.; Seto, H.; Shimizu, M.; Watanabe, N.

2000-01-01

To determine the relationship between apparent diffusion coefficient (ADC) values measured by diffusion-weighted MR imaging and split renal function determined by renal scintigraphy in patients with hydronephrosis. Material and Methods: Diffusion-weighted imaging on a 1.5 T MR unit and renal scintigraphy were performed in 36 patients with hydronephrosis (45 hydronephrotic kidneys, 21 non-hydronephrotic kidneys). ADC values of the individual kidneys were measured by diffusion-weighted MR imaging. Split renal function (glomerular filtration rate (GFR)) was determined by renal scintigraphy using 99m Tc-DTPA. The relationship between ADC values and split GFR was examined in 66 kidneys. The hydronephrotic kidneys were further classified into three groups (severe renal dysfunction, GFR 25 ml/min, n=28), and mean values for ADCs were calculated. Results: In hydronephrotic kidneys, there was a moderate positive correlation between ADC values and split GFR (R2=0.56). On the other hand, in non-hydronephrotic kidneys, poor correlation between ADC values and split GFR was observed (R2=0.08). The mean values for ADCs of the dysfunctioning hydronephrotic kidneys (severe renal dysfunction, 1.32x10 -3 ±0.18x10 -3 mm 2 /s; moderate renal dysfunction, 1.38x10 -3 ±0.10x10 -3 mm2/s) were significantly lower than that of the normal functioning hydronephrotic kidneys (1.63x10 -3 ±0.12±10 -3 mm 2 /s). Conclusion: These results indicated that measurement of ADC values by diffusion-weighted MR imaging has a potential value in the evaluation of the functional status of hydronephrotic kidneys

Self diffusion in tungsten

International Nuclear Information System (INIS)

Mundy, J.N.; Rothman, S.J.; Lam, N.Q.; Nowicki, L.J.; Hoff, H.A.

1978-01-01

The lack of understanding of self-diffusion in Group VI metals together with the wide scatter in the measured values of tungsten self-diffusion has prompted the present measurements to be made over a wide temperature range (1/2Tsub(m) to Tsub(m)). The diffusion coefficients have been measured in the temperature range 1430-2630 0 C. The present measurements show non-linear Arrhenius behavior but a reliable two-exponential fit of the data should await further measurements. (Auth.)

Measurements of integrated direct, diffuse and global ultraviolet-B radiation

International Nuclear Information System (INIS)

Utrillas, M.P.; Pedrós, R.; Gandía, S.; Gómez-Amo, J.L.; Estellés, V.; Martínez-Lozano, J.A.

2015-01-01

We present the first multiyear set of simultaneous measurements of the global ultraviolet-B radiation and its two components: direct and diffuse. The measurements have been taken with four YES-UVB-1 radiometers: two radiometers to measure the diffuse radiation, one provided with a shadow band and the other with a shadow disk on a Sun tracker; a radiometer to measure the global horizontal radiation; and a Sun-tracking radiometer to measure the direct radiation with an especially designed radiance collimator. The diffuse minute-values measured with both instruments agree within a coefficient correlation of 1.00. The diffuse component represents at least 50% of the global UVB (ultraviolet-B) radiation. The minute values of global UVB irradiance obtained by adding the direct and diffuse components concur with the measured global irradiance. Therefore, the measurement of the direct irradiance enables the estimation of the diffuse component, and gives an insight into the factors that affect its value, especially aerosols. - Highlights: • Simultaneous measurements of global, direct and diffuse UVB (ultraviolet-B) radiation. • The diffuse minute-values are at least 50% of the global ones. • The diffuse measurements are highly correlated to the aerosol load. • The sum of direct + diffuse radiation concur with the measured global.

Study on diffusion behavior of nuclide in buffer material

International Nuclear Information System (INIS)

Suzuki, Satoru

2002-05-01

Bentonite is a promising candidate of buffer material for geological disposal of high-level radioactive waste (HLW). Mass transport in bentonite is mainly controlled by diffusion process because of extremely low-permeability. Geological environments, e.g. salinity of ground water and temperature can strongly influence on migration behavior in bentonite, and therefore diffusivity and diffusion mechanism have been investigated experimentally and theoretically. In chapter 1, the author summarizes how the diffusivity in the buffer material has been treated in the safety assessment. In chapter 2, results of diffusion experiments as a function of salinity and temperature have been shown. In chapter 3, relationship between diffusivity and pore structure of bentonite has been investigated theoretically. In chapter 4, sorption structure of strontium on smectite has been studied by using molecular dynamics simulation. In chapter 5, vibrational property of pore water has been investigated. Diffusivity in bentonite has been discussed based on rock capacity factor, microstructure and interaction between diffusant and bentonite. (author)

Radionuclide diffusion in soils. III

International Nuclear Information System (INIS)

Cipakova, A.; Szabova, T.

1988-01-01

Samples were taken of five soil types for determining diffusion coefficients, namely chernozem, illimerized brown soil, degraded chernozem, gleizated brown soil and heavy loamy brown soil. 5 layers of soil having a thickness of 1 cm each were placed in diffusion columns. 20 ml of water with 0.45 MBq 85 Sr of distilled water was poured over the columns. 10 ml of distilled water was poured over the columns every 5 days for monitoring the effect of the amount of precipitation and its distribution - a similarity with rainfall in the driest month, 41 ml of distilled water was then poured over the column every 5 days or 82 ml of distilled water every 10 days - imitating the month with the highest rainfall level. The effect of salts and various concentrations of salt mixtures on the value of the diffusion coefficient were monitored in solutions of NaNO 3 , KNO 3 and Ca(NO 3 ) 2 with added activity 0.45 MGq of 85 SrCl 2 . Diffusion was monitored for 101 days. All measured values are tabulated. The smallest diffusion coefficient was found in chernozem in the presence of H 2 O and the highest value was found in illimerized brown soil in the presence of 0.15 M of KNO 3 . (E.S.). 2 tabs., 10 refs

Effects of time-dependent diffusion behaviors on the rumor spreading in social networks

Energy Technology Data Exchange (ETDEWEB)

Qiu, Xiaoyan [School of Management, Shanghai University, Shanghai 200444 (China); Zhao, Laijun, E-mail: ljzhao70@sjtu.edu.cn [Sino–US Global Logistics Institute, Shanghai Jiao Tong University, Shanghai 200030 (China); Antai College of Economics and Management, Shanghai Jiao Tong University, Shanghai 200052 (China); Wang, Jiajia [Sino–US Global Logistics Institute, Shanghai Jiao Tong University, Shanghai 200030 (China); Antai College of Economics and Management, Shanghai Jiao Tong University, Shanghai 200052 (China); Wang, Xiaoli [School of Management, Shanghai University of Engineering Science, Shanghai 201620 (China); Wang, Qin [College of Transport & Communications, Shanghai Maritime University, Shanghai 201306 (China)

2016-05-27

When considering roles of realistic external forces (e.g. authorities) and internal forces (e.g. the forgetting nature of human), diffusion behaviors like spreading, stifling and forgetting behaviors are time-dependent. They were incorporated in an SIR-like rumor spreading model to investigate the effects to rumor spreading dynamics. Mean-field equations were derived, and the steady state analysis was conducted. Simulations were carried out on different complex networks. We demonstrated that the combination of the three variable diffusion behaviors provides a faster and larger spreading expansion capacity. Network structure matters considerably in rumor spreading dynamics. - Highlights: • We incorporate time-dependent diffusion behaviors into a SIR-like rumor spreading model. • The combination of the three variable diffusion behaviors provides a faster and larger spreading expansion capacity. • Network structure matters considerably in rumor spreading dynamics.

Effects of time-dependent diffusion behaviors on the rumor spreading in social networks

International Nuclear Information System (INIS)

Qiu, Xiaoyan; Zhao, Laijun; Wang, Jiajia; Wang, Xiaoli; Wang, Qin

2016-01-01

When considering roles of realistic external forces (e.g. authorities) and internal forces (e.g. the forgetting nature of human), diffusion behaviors like spreading, stifling and forgetting behaviors are time-dependent. They were incorporated in an SIR-like rumor spreading model to investigate the effects to rumor spreading dynamics. Mean-field equations were derived, and the steady state analysis was conducted. Simulations were carried out on different complex networks. We demonstrated that the combination of the three variable diffusion behaviors provides a faster and larger spreading expansion capacity. Network structure matters considerably in rumor spreading dynamics. - Highlights: • We incorporate time-dependent diffusion behaviors into a SIR-like rumor spreading model. • The combination of the three variable diffusion behaviors provides a faster and larger spreading expansion capacity. • Network structure matters considerably in rumor spreading dynamics.

Measurement of thermal diffusivity of depleted uranium metal microspheres

Science.gov (United States)

Humrickhouse-Helmreich, Carissa J.; Corbin, Rob; McDeavitt, Sean M.

2014-03-01

The high void space of nuclear fuels composed of homogeneous uranium metal microspheres may allow them to achieve ultra-high burnup by accommodating fuel swelling and reducing fuel/cladding interactions; however, the relatively low thermal conductivity of microsphere nuclear fuels may limit their application. To support the development of microsphere nuclear fuels, an apparatus was designed in a glovebox and used to measure the apparent thermal diffusivity of a packed bed of depleted uranium (DU) microspheres with argon fill in the void spaces. The developed Crucible Heater Test Assembly (CHTA) recorded radial temperature changes due to an initial heat pulse from a central thin-diameter cartridge heater. Using thermocouple positions and time-temperature data, the apparent thermal diffusivity was calculated. The thermal conductivity of the DU microspheres was calculated based on the thermal diffusivity from the CHTA, known material densities and specific heat capacities, and an assumed 70% packing density based on prior measurements. Results indicate that DU metal microspheres have very low thermal conductivity, relative to solid uranium metal, and rapidly form an oxidation layer even in a low oxygen environment. At 500 °C, the thermal conductivity of the DU metal microsphere bed was 0.431 ± 0.0560 W/m-K compared to the literature value of approximately 32 W/m-K for solid uranium metal.

Measurement of thermal diffusivity of depleted uranium metal microspheres

Energy Technology Data Exchange (ETDEWEB)

Humrickhouse-Helmreich, Carissa J., E-mail: carissahelmreich@tamu.edu [Texas A and M University, Department of Nuclear Engineering, 337 Zachry Engineering Center, 3133 TAMU, College Station, TX 77843 (United States); Corbin, Rob, E-mail: rcorbin@terrapower.com [TerraPower, LLC, 330 120th Ave NE, Suite 100, Bellevue, WA 98005 (United States); McDeavitt, Sean M., E-mail: mcdeavitt@tamu.edu [Texas A and M University, Department of Nuclear Engineering, 337 Zachry Engineering Center, 3133 TAMU, College Station, TX 77843 (United States)

2014-03-15

The high void space of nuclear fuels composed of homogeneous uranium metal microspheres may allow them to achieve ultra-high burnup by accommodating fuel swelling and reducing fuel/cladding interactions; however, the relatively low thermal conductivity of microsphere nuclear fuels may limit their application. To support the development of microsphere nuclear fuels, an apparatus was designed in a glovebox and used to measure the apparent thermal diffusivity of a packed bed of depleted uranium (DU) microspheres with argon fill in the void spaces. The developed Crucible Heater Test Assembly (CHTA) recorded radial temperature changes due to an initial heat pulse from a central thin-diameter cartridge heater. Using thermocouple positions and time–temperature data, the apparent thermal diffusivity was calculated. The thermal conductivity of the DU microspheres was calculated based on the thermal diffusivity from the CHTA, known material densities and specific heat capacities, and an assumed 70% packing density based on prior measurements. Results indicate that DU metal microspheres have very low thermal conductivity, relative to solid uranium metal, and rapidly form an oxidation layer even in a low oxygen environment. At 500 °C, the thermal conductivity of the DU metal microsphere bed was 0.431 ± 0.0560 W/m-K compared to the literature value of approximately 32 W/m-K for solid uranium metal.

Measurement of thermal diffusivity of depleted uranium metal microspheres

International Nuclear Information System (INIS)

Humrickhouse-Helmreich, Carissa J.; Corbin, Rob; McDeavitt, Sean M.

2014-01-01

The high void space of nuclear fuels composed of homogeneous uranium metal microspheres may allow them to achieve ultra-high burnup by accommodating fuel swelling and reducing fuel/cladding interactions; however, the relatively low thermal conductivity of microsphere nuclear fuels may limit their application. To support the development of microsphere nuclear fuels, an apparatus was designed in a glovebox and used to measure the apparent thermal diffusivity of a packed bed of depleted uranium (DU) microspheres with argon fill in the void spaces. The developed Crucible Heater Test Assembly (CHTA) recorded radial temperature changes due to an initial heat pulse from a central thin-diameter cartridge heater. Using thermocouple positions and time–temperature data, the apparent thermal diffusivity was calculated. The thermal conductivity of the DU microspheres was calculated based on the thermal diffusivity from the CHTA, known material densities and specific heat capacities, and an assumed 70% packing density based on prior measurements. Results indicate that DU metal microspheres have very low thermal conductivity, relative to solid uranium metal, and rapidly form an oxidation layer even in a low oxygen environment. At 500 °C, the thermal conductivity of the DU metal microsphere bed was 0.431 ± 0.0560 W/m-K compared to the literature value of approximately 32 W/m-K for solid uranium metal

Diffusion weighted imaging by MR method

International Nuclear Information System (INIS)

Horikawa, Yoshiharu; Naruse, Shoji; Ebisu, Toshihiko; Tokumitsu, Takuaki; Ueda, Satoshi; Tanaka, Chuzo; Higuchi, Toshihiro; Umeda, Masahiro.

1993-01-01

Diffusion weighted magnetic resonance imaging is a recently developed technique used to examine the micromovement of water molecules in vivo. We have applied this technique to examine various kinds of brain diseases, both experimentally and clinically. The calculated apparent diffusion coefficient (ADC) in vivo showed reliable values. In experimentally induced brain edema in rats, the pathophysiological difference of the type of edema (such as cytotoxic, and vasogenic) could be differentiated on the diffusion weighted MR images. Cytotoxic brain edema showed high intensity (slower diffusion) on the diffusion weighted images. On the other hand, vasogenic brain edema showed a low intensity image (faster diffusion). Diffusion anisotropy was demonstrated according to the direction of myelinated fibers and applied motion proving gradient (MPG). This anisotropy was also demonstrated in human brain tissue along the course of the corpus callosum, pyramidal tract and optic radiation. In brain ischemia cases, lesions were detected as high signal intensity areas, even one hour after the onset of ischemia. Diffusion was faster in brain tumor compared with normal brain. Histological differences were not clearly reflected by the ADC value. In epidermoid tumor cases, the intensity was characteristically high, was demonstrated, and the cerebrospinal fluid border was clearly demonstrated. New clinical information obtainable with this molecular diffusion method will prove to be useful in various clinical studies. (author)

Analysis of the Diffuse Domain Method for Second Order Elliptic Boundary Value Problems

NARCIS (Netherlands)

Burger, Martin; Elvetun, Ole; Schlottbom, Matthias

2017-01-01

The diffuse domain method for partial differential equations on complicated geometries recently received strong attention in particular from practitioners, but many fundamental issues in the analysis are still widely open. In this paper, we study the diffuse domain method for approximating second

Diagnostic value of structural and diffusion imaging measures in schizophrenia

Directory of Open Access Journals (Sweden)

Jungsun Lee

Full Text Available Objectives: Many studies have attempted to discriminate patients with schizophrenia from healthy controls by machine learning using structural or functional MRI. We included both structural and diffusion MRI (dMRI and performed random forest (RF and support vector machine (SVM in this study. Methods: We evaluated the performance of classifying schizophrenia using RF method and SVM with 504 features (volume and/or fractional anisotropy and trace from 184 brain regions. We enrolled 47 patients and 23 age- and sex-matched healthy controls and resampled our data into a balanced dataset using a Synthetic Minority Oversampling Technique method. We randomly permuted the classification of all participants as a patient or healthy control 100 times and ran the RF and SVM with leave one out cross validation for each permutation. We then compared the sensitivity and specificity of the original dataset and the permuted dataset. Results: Classification using RF with 504 features showed a significantly higher rate of performance compared to classification by chance: sensitivity (87.6% vs. 47.0% and specificity (95.9 vs. 48.4% performed by RF, sensitivity (89.5% vs. 48.0% and specificity (94.5% vs. 47.1% performed by SVM. Conclusions: Machine learning using RF and SVM with both volume and diffusion measures can discriminate patients with schizophrenia with a high degree of performance. Further replications are required. Keywords: Classification, Diffusion MRI, Random forest, Support vector machine, Schizophrenia

The influence of the b-value combination on apparent diffusion coefficient based differentiation between malignant and benign tissue in cervical cancer

NARCIS (Netherlands)

Hoogendam, Jacob P.; Klerkx, Wenche M.; de Kort, Gerard A. P.; Bipat, Shandra; Zweemer, Ronald P.; Sie-Go, Daisy M. D. S.; Verheijen, René H. M.; Mali, Willem P. T. M.; Veldhuis, Wouter B.

2010-01-01

To analyze the influence of different b-value combinations on apparent diffusion coefficient (ADC)-based differentiation of known malignant and benign tissue in cervical cancer patients. A total of 35 patients with stage IB1, IB2, IIA cervical cancer underwent a 3.0T MRI scan prior to radical

Renal water molecular diffusion characteristics in healthy native kidneys: assessment with diffusion tensor MR imaging.

Directory of Open Access Journals (Sweden)

Zhenfeng Zheng

Full Text Available BACKGROUND: To explore the characteristics of diffusion tensor imaging (DTI and magnetic resonance (MR imaging in healthy native kidneys. METHODS: Seventy-three patients without chronic kidney disease underwent DTI-MRI with spin echo-echo planar (SE-EPI sequences accompanied by an array spatial sensitivity encoding technique (ASSET. Cortical and medullary mean, axial and radial diffusivity (MD, AD and RD, fractional anisotropy (FA and primary, secondary and tertiary eigenvalues (λ1, λ2, λ3 were analysed in both kidneys and in different genders. RESULTS: Cortical MD, λ2, λ3, and RD values were higher than corresponding medullary values. The cortical FA value was lower than the medullary FA value. Medullary λ1 and RD values in the left kidney were lower than in the right kidney. Medullary λ2, and λ3 values in women were higher than those in men. Medullary FA values in women were lower than those in men. Medullary FA (r = 0.351, P = 0.002 and λ1 (r = 0.277, P = 0.018 positively correlated with eGFR. Medullary FA (r = -0.25, P = 0.033 negatively correlated with age. CONCLUSIONS: Renal water molecular diffusion differences exist in human kidneys and genders. Age and eGFR correlate with medullary FA and primary eigenvalue.

Economic value analysis of the return from the Korean astronaut program and the science culture diffusion activity in Korea

Science.gov (United States)

Yi, Soyeon; Jang, Hyun-Jin; Lee, Hyo Suk; Yu, Jong-Phil; Kim, Soyeon; Lee, Joohee; Hur, Hee-Young

2013-06-01

In this study, we analyze the economic effects from the Korean Astronaut Program (KAP) and the subsequent Science Culture Diffusion Activity (SCDA). Korea has had a huge practical effect on the development of science and technology and has increased international awareness of Korea by producing Korea's first astronaut. There has also been a large, ripple effect on space related industries. In addition, the KAP has exercised a far-reaching influence on Korean society and culture by boosting all science and engineering and inspiring national pride. After the KAP, astronauts' outreach activities, such as lectures for the general public; interviews on television, newspapers and magazines; participating in children's science camps; and distributing publications and DVDs about astronaut program for general public, were instituted for diffusing science culture. Thus, positive effects such as the promotion of Korea's level of technology, student interest in science and engineering fields, and the expansion of the industrial base were reinforced after the KAP. This study is aimed at evaluating the economic significance and the value of return through analyzing the effects of the KAP and the subsequent Science Culture Diffusion Activity.

The predictive value of the antioxidant capacity of structurally related flavonoids using the Trolox equivalent antioxidant capacity (TEAC) assay

NARCIS (Netherlands)

Berg, R. van den; Haenen, G.R.M.M.; Berg, H. van den; Vijgh, W. van der; Bast, A.

2000-01-01

The antioxidant capacity of a series of structurally related flavonoids is quantified by the amount of ABTS [2,2'-azinobis-(3-ethylbenzthiazoline-6-sulfonate)] radical anions (ABTS(.)-) that is able to react with the flavonoid and expressed as the Trolox equivalent antioxidant capacity (TEAC). To

Diffuse and focal presentations of brainstem tumors in children: the images and the prognostic value

International Nuclear Information System (INIS)

Menor, F.; Canete, A.; Romero, M. J.; Trilles, L.; Carvajal, E.; Marti-Bonmati, L.

2000-01-01

To determine whether the presentation of brainstem tumors as diffuse or focal lesions showed any prognostic value in children. A retrospective review was carried out of the neuroradiological findings in 43 children with brainstem tumors, all of whom underwent computed tomography (CT) and 31 of whom underwent magnetic resonance (MR). The diffuse tumors (n=20) were all located in the pons, spreading to mesencephalon in 6 cases and to medulla oblongata in 1, and exhibiting exophytic growth, preferentially to the prepontine cistern. They presented homogeneous low attenuation in CT (90%) and decrease/increased signal intensity in T1/T2-weighted MR images (91.6%). Contrast uptake was observed in 20% of cases, with agreement between CT and MR. The patients showed a good initial response to treatment (70%), a high rate of relapse (80%) and a 5-year survival of 12%. The focal tumors were located in the pons (11 cases, spreading to the medulla oblongata in 2), mesencephalon (11 cases, 9 tectal and 2 peduncular) and medulla oblongata (1 case), and exhibited exophytic growth predominantly to the pontocerebellar junction and to the cerebellar peduncles. They showed a certain tendency toward heterogeneity (21.7%), toward isoattenuation in CT (47.8%) and isointensity in T1-weighted MR images (26.3%). CT showed a rate of tumor uptake of 26%, while the rate of contrast iptake was 58% MR. Fifty percent of these lesions responded well to therapy, with a recurrence rate of 28% and 4-year survival of 63%. Neuroimaging helps to define two basic patterns in brainstem tumors that play a role in prognosis. The diffuse tumor, which characteristically shows a good initial response to therapy, has a worse prognosis, probably reflecting its histological aggressiveness. (Author) 21 refs

Diffusion-weighted imaging and diffusion tensor imaging of asymptomatic lumbar disc herniation.

Science.gov (United States)

Sakai, Toshinori; Miyagi, Ryo; Yamabe, Eiko; Fujinaga, Yasunari; N Bhatia, Nitin; Yoshioka, Hiroshi

2014-01-01

Diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) were performed on a healthy 31-year-old man with asymptomatic lumbar disc herniation. Although the left S1 nerve root was obviously entrapped by a herniated mass, neither DWI nor DTI showed any significant findings for the nerve root. Decreased apparent diffusion coefficient (ADC) values and increased fractional anisotropy (FA) values were found. These results are contrary to those in previously published studies of symptomatic patients, in which a combination of increased ADC and decreased FA seem to have a relationship with nerve injury and subsequent symptoms, such as leg pain or palsy. Our results seen in an asymptomatic subject suggest that the compressed nerve with no injury, such as edema, demyelination, or persistent axonal injury, may be indicated by a combination of decreased ADC and increased FA. ADC and FA could therefore be potential tools to elucidate the pathomechanism of radiculopathy.

Diffusion kurtosis imaging of the liver at 3 Tesla: in vivo comparison to standard diffusion-weighted imaging.

Science.gov (United States)

Budjan, Johannes; Sauter, Elke A; Zoellner, Frank G; Lemke, Andreas; Wambsganss, Jens; Schoenberg, Stefan O; Attenberger, Ulrike I

2018-01-01

Background Functional techniques like diffusion-weighted imaging (DWI) are gaining more and more importance in liver magnetic resonance imaging (MRI). Diffusion kurtosis imaging (DKI) is an advanced technique that might help to overcome current limitations of DWI. Purpose To evaluate DKI for the differentiation of hepatic lesions in comparison to conventional DWI at 3 Tesla. Material and Methods Fifty-six consecutive patients were examined using a routine abdominal MR protocol at 3 Tesla which included DWI with b-values of 50, 400, 800, and 1000 s/mm 2 . Apparent diffusion coefficient maps were calculated applying a standard mono-exponential fit, while a non-Gaussian kurtosis fit was used to obtain DKI maps. ADC as well as Kurtosis-corrected diffusion ( D) values were quantified by region of interest analysis and compared between lesions. Results Sixty-eight hepatic lesions (hepatocellular carcinoma [HCC] [n = 25]; hepatic adenoma [n = 4], cysts [n = 18]; hepatic hemangioma [HH] [n = 18]; and focal nodular hyperplasia [n = 3]) were identified. Differentiation of malignant and benign lesions was possible based on both DWI ADC as well as DKI D-values ( P values were in the range of 0.04 to < 0.0001). Conclusion In vivo abdominal DKI calculated using standard b-values is feasible and enables quantitative differentiation between malignant and benign liver lesions. Assessment of conventional ADC values leads to similar results when using b-values below 1000 s/mm 2 for DKI calculation.

Diagnostic value of sonography, ultrasound-guided fine-needle aspiration cytology, and diffusion-weighted MRI in the characterization of cold thyroid nodules

Energy Technology Data Exchange (ETDEWEB)

Schueller-Weidekamm, Claudia [Department of Diagnostic Radiology, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria)], E-mail: claudia.schueller-weidekamm@meduniwien.ac.at; Schueller, Gerd [Department of Diagnostic Radiology, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria); Kaserer, Klaus [Department of Pathology, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria); Scheuba, Christian [Department of Surgery, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria); Ringl, Helmut; Weber, Michael; Czerny, Christian; Herneth, Andreas M. [Department of Diagnostic Radiology, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria)

2010-03-15

Introduction: The purpose of this prospective study was to assess the diagnostic value of different modalities for the characterization of cold thyroid nodules. Methods: In 35 patients with cold nodules, thyroid carcinoma was suspected on scintigraphy. These patients were prospectively investigated with sonography, ultrasound-guided fine-needle aspiration (USgFNA), and quantitative diffusion-weighted imaging magnetic resonance imaging (DWI) (navigated echo-planar imaging; maximum b-value 800 s/mm{sup 2}) prior to surgery. The sonographic findings, USgFNA cytology, and the apparent diffusion coefficient (ADC) values of DWI were correlated with the postoperative histology of benign and malignant lesions. Statistical analysis was performed with the Kruskal-Wallis test and the Fisher's exact test. P < .05 denoted statistical significance. Results: The accuracy of sonography and USgFNA was 64% and 68.8%, respectively. The sensitivity was 86.7% and 80%, respectively. Specificity was only 57.2% and 50%, respectively. The median ADC values for carcinoma and adenoma were 2.73 x 10{sup -3} mm{sup 2}/s and 1.93 x 10{sup -3} mm{sup 2}/s, respectively (P < .001). There was no significant difference between the median ADC value for Hashimoto thyroiditis (3.46 x 10{sup -3} mm{sup 2}/s) and carcinoma. An ADC value of 2.25 x 10{sup -3} mm{sup 2}/s or higher was proven to be the cut-off value for differentiating between benign and malignant cold thyroid nodules, with an accuracy of 88%, a sensitivity of 85%, and a specificity of 100%. Conclusions: These results show that quantitative DWI is a more reliable diagnostic method for differentiation between benign and malignant thyroid lesions than sonography or USgFNA. However, further studies including a larger study population are necessary to confirm our study results.

Inward Cationic Diffusion and Percolation Transition in Glass-Ceramics

DEFF Research Database (Denmark)

Smedsklaer, Morten Mattrup; Yue, Yuanzheng; Mørup, Steen

2010-01-01

We show the quantitative correlation between the degree of crystallization and the cationic diffusion extent in iron-containing diopside glass–ceramics at the glass transition temperature. We find a critical degree of crystallization, above which the diffusion extent sharply drops with the degree...... of crystallization. Below the critical value, the diffusion extent decreases only slightly with the degree of crystallization. No cationic diffusion is observed in the fully crystalline materials. The critical value might be associated with a percolation transition from an interconnected to a disconnected glass...

Development of a new free radical absorption capacity assay method for antioxidants: aroxyl radical absorption capacity (ARAC).

Science.gov (United States)

Nagaoka, Shin-ichi; Nagai, Kanae; Fujii, Yuko; Ouchi, Aya; Mukai, Kazuo

2013-10-23

A new free radical absorption capacity assay method is proposed with use of an aroxyl radical (2,6-di-tert-butyl-4-(4'-methoxyphenyl)phenoxyl radical) and stopped-flow spectroscopy and is named the aroxyl radical absorption capacity (ARAC) assay method. The free radical absorption capacity (ARAC value) of each tocopherol was determined through measurement of the radical-scavenging rate constant in ethanol. The ARAC value could also be evaluated through measurement of the half-life of the aroxyl radical during the scavenging reaction. For the estimation of the free radical absorption capacity, the aroxyl radical was more suitable than the DPPH radical, galvinoxyl, and p-nitrophenyl nitronyl nitroxide. The ARAC value in tocopherols showed the same tendency as the free radical absorption capacities reported previously, and the tendency was independent of an oxygen radical participating in the scavenging reaction and of a medium surrounding the tocopherol and oxygen radical. The ARAC value can be directly connected to the free radical-scavenging rate constant, and the ARAC method has the advantage of treating a stable and isolable radical (aroxyl radical) in a user-friendly organic solvent (ethanol). The ARAC method was also successfully applied to a palm oil extract. Accordingly, the ARAC method would be useful in free radical absorption capacity assay of antioxidative reagents and foods.

Comparison of radon diffusion coefficients measured by transient-diffusion and steady-state laboratory methods

International Nuclear Information System (INIS)

Kalwarf, D.R.; Nielson, K.K.; Rich, D.C.; Rogers, V.C.

1982-11-01

A method was developed and used to determine radon diffusion coefficients in compacted soils by transient-diffusion measurements. A relative standard deviation of 12% was observed in repeated measurements with a dry soil by the transient-diffusion method, and a 40% uncertainty was determined for moistures exceeding 50% of saturation. Excellent agreement was also obtained between values of the diffusion coefficient for radon in air, as measured by the transient-diffusion method, and those in the published literature. Good agreement was also obtained with diffusion coefficients measured by a steady-state method on the same soils. The agreement was best at low moistures, averaging less than ten percent difference, but differences of up to a factor of two were observed at high moistures. The comparison of the transient-diffusion and steady-state methods at low moistures provides an excellent verification of the theoretical validity and technical accuracy of these approaches, which are based on completely independent experimental conditions, measurement methods and mathematical interpretations

Mimetic Discretization of Vector-valued Diffusion Problems

DEFF Research Database (Denmark)

Olesen, Kennet

this is the balance of the change of mass in a finite volume with mass fluxes across the surfaces bounding this volume? In the FDM and FEM the derivatives in the gradient-, curl- and divergence operator are approximated by formulating expressions with respect to a finite number of selected points. The continuous...... gradient-, curl- and divergence operators are derived based on geometrical considerations on finite domains, and by introducing geometry into the numerical scheme these operators can be replicated exactly. To incorporate the geometry into the PDEs the field of differential geometry is applied, which has...... of different dimensions through Stokes' theorem. - A clear separation of balance/equilibrium equations and constitutive equations is possible. As mentioned the emphasis is put on diffusion dominated problems containing second order tensors. Earlier work has developed a rigorous framework for problems involving...

ON INTERSECTIONS OF INDEPENDENT NONDEGENERATE DIFFUSION PROCESSES

Institute of Scientific and Technical Information of China (English)

Zhenlong CHEN

2014-01-01

Let X(1) = {X(1)(s), s ∈ R+} and X(2) = {X(2)(t), t ∈ R+} be two inde-pendent nondegenerate diffusion processes with values in Rd. The existence and fractal dimension of intersections of the sample paths of X (1) and X (2) are studied. More gener-ally, let E1, E2⊆(0,∞) and F ⊂Rd be Borel sets. A necessary condition and a suffcient condition for P{X(1)(E1)∩X(2)(E2)∩F 6=∅}>0 are proved in terms of the Bessel-Riesz type capacity and Hausdorff measure of E1 × E2 × F in the metric space (R+× R+× Rd,ρb), whereρb is an unsymmetric metric defined in R+× R+× Rd. Under reasonable conditions, results resembling those of Browian motion are obtained.

Diagnostic value of proton MR spectroscopy and diffusion-weighted MR imaging in childhood inherited neurometabolic brain diseases and review of the literature

Energy Technology Data Exchange (ETDEWEB)

Cakmakci, Handan, E-mail: handan.cakmakci@deu.edu.t [Dokuz Eylul University Faculty of Medicine, Department of Radiology, Izmir (Turkey); Pekcevik, Yeliz [Dokuz Eylul University Faculty of Medicine, Department of Radiology, Izmir (Turkey); Yis, Uluc [Dokuz Eylul University Faculty of Medicine, Department of Pediatric Neurology, Izmir (Turkey); Unalp, Aycan [Behcet Uz Hospital, Department of Pediatric Neurology, Izmir (Turkey); Kurul, Semra [Dokuz Eylul University Faculty of Medicine, Department of Pediatric Neurology, Izmir (Turkey)

2010-06-15

The purpose of this study is to evaluate parenchymal diffusion properties and metabolite ratios in affected brain tissues of inherited neurometabolic brain diseases with an overview of the current literature about the diagnostic data of both techniques in childhood inherited metabolic brain diseases. The study group was consisting, 19 patients (15 males, 4 females; mean age, 54 months (4.5 years); age range, 1-171 months (14.25 years)) diagnosed with inherited neurometabolic brain disease. Single- and multivoxel proton MRS was carried out and NAA/Cr, Cho/Cr, mI/Cr, Glx/Cr ratios were calculated. Presence of lactate peak and abnormal different peaks were noted. ADC values were calculated from brain lesions. Results are compared with age and sex matched normal subjects. Elevated NAA/Cr ratio (Canavan disease), galactitol peak (galactosemia) at 3.7 ppm, branched chain amino acids (Maple syrup urine disease-MSUD) at 0.9 ppm were seen on different diseases. In Leigh disease and MSUD restricted diffusion was detected. Different diffusion properties were seen only in one Glutaric aciduria lesions. NAA/Cr ratios and calculated ADC values were significantly different from normal subjects (p < 0.05). DWI combined with MRS are complementary methods to routine cranial MRI for evaluating neurometabolic diseases which can give detailed information about neurochemistry of affected brain areas.

Diagnostic value of proton MR spectroscopy and diffusion-weighted MR imaging in childhood inherited neurometabolic brain diseases and review of the literature

International Nuclear Information System (INIS)

Cakmakci, Handan; Pekcevik, Yeliz; Yis, Uluc; Unalp, Aycan; Kurul, Semra

2010-01-01

The purpose of this study is to evaluate parenchymal diffusion properties and metabolite ratios in affected brain tissues of inherited neurometabolic brain diseases with an overview of the current literature about the diagnostic data of both techniques in childhood inherited metabolic brain diseases. The study group was consisting, 19 patients (15 males, 4 females; mean age, 54 months (4.5 years); age range, 1-171 months (14.25 years)) diagnosed with inherited neurometabolic brain disease. Single- and multivoxel proton MRS was carried out and NAA/Cr, Cho/Cr, mI/Cr, Glx/Cr ratios were calculated. Presence of lactate peak and abnormal different peaks were noted. ADC values were calculated from brain lesions. Results are compared with age and sex matched normal subjects. Elevated NAA/Cr ratio (Canavan disease), galactitol peak (galactosemia) at 3.7 ppm, branched chain amino acids (Maple syrup urine disease-MSUD) at 0.9 ppm were seen on different diseases. In Leigh disease and MSUD restricted diffusion was detected. Different diffusion properties were seen only in one Glutaric aciduria lesions. NAA/Cr ratios and calculated ADC values were significantly different from normal subjects (p < 0.05). DWI combined with MRS are complementary methods to routine cranial MRI for evaluating neurometabolic diseases which can give detailed information about neurochemistry of affected brain areas.

Installed capacity in New York

International Nuclear Information System (INIS)

Charlton, J.

2006-01-01

This presentation discussed capacity issues related to the New York Independent System Operator (NYISO). The NYISO's market volume was approximately $11 billion in 2005, and it was responsible for providing 32,075 MW of electricity at peak load to its users. Regulatory uncertainty is currently discouraging investment in new generating resources. All load serving entities are required to contract for sufficient capacity in order to meet their capacity obligations. Market participants currently determine capacity and energy revenues. The NYISO market allows suppliers to recover variable costs for providing ancillary services, and the economic value of the revenue source governs decisions made in the wholesale electricity market. The installed capacity market was designed as a spot auction deficiency auction. Phased-in demand curves are used to modify the installed capacity market's design. A sloped demand curve mechanism is used to value capacity above the minimum requirement for both reliability and competition. Participation in the day-ahead market enhances competition and exerts downward pressure on energy and ancillary service market prices. It was concluded that the market structures and design features of the installed capacity markets recognize the need for system reliability in addition to encouraging robust competition and recognizing energy price caps and regulatory oversights. tabs., figs

Diffusion of gases in solids: rare gas diffusion in solids; tritium diffusion in fission and fusion reactor metals. Final report

International Nuclear Information System (INIS)

Abraham, P.M.; Chandra, D.; Mintz, J.M.; Elleman, T.S.; Verghese, K.

1976-01-01

Major results of tritium and rare gas diffusion research conducted under the contract are summarized. The materials studied were austenitic stainless steels, Zircaloy, and niobium. In all three of the metal systems investigated, tritium release rates were found to be inhibited by surface oxide films. The effective diffusion coefficients that control tritium release from surface films on Zircaloy and niobium were determined to be eight to ten orders of magnitude lower than the bulk diffusion coefficients. A rapid component of diffusion due to grain boundaries was identified in stainless steels. The grain boundary diffusion coefficient was determined to be about six orders of magnitude greater than the bulk diffusion coefficient for tritium in stainless steel. In Zircaloy clad fuel pins, the permeation rate of tritium through the cladding is rate-limited by the extremely slow diffusion rate in the surface films. Tritium diffusion rates through surface oxide films on niobium appear to be controlled by cracks in the surface films at temperatures up to 600 0 C. Beyond 600 0 C, the cracks appear to heal, thereby increasing the activation energy for diffusion through the oxide film. The steady-state diffusion of tritium in a fusion reactor blanket has been evaluated in order to calculate the equilibrium tritium transport rate, approximate time to equilibrium, and tritium inventory in various regions of the reactor blanket as a function of selected blanket parameters. Values for these quantities have been tabulated

Diffusion-weighted MR imaging for detection of extrahepatic cholangiocarcinoma

International Nuclear Information System (INIS)

Cui, Xing-Yu; Chen, Hong-Wei; Cai, Song; Bao, Jian; Tang, Qun-Feng; Wu, Li-Yuan; Fang, Xiang-Ming

2012-01-01

Objectives: To measure the sensitivity of diffusion-weighted imaging (DWI) and determine the most appropriate b value for DWI; to explore the correlation between the apparent diffusion coefficient (ADC) value and the degree of extrahepatic cholangiocarcinoma differentiation. Methods: Preoperative diffusion-weighted imaging and magnetic resonance examinations were performed for 31 patients with extrahepatic cholangiocarcinoma. Tumor ADC values were measured, and the signal-to-noise ratio, contrast-to-noise ratio, and signal-intensity ratio between the diffusion-weighted images with various b values as well as the T2-weighted images were calculated. Pathologically confirmed patients were pathologically graded to compare the ADC value with different b values of tumor at different degrees of differentiation, and the results were statistically analyzed by using the Friedman test. Results: A total of 29 cases of extrahepatic cholangiocarcinoma were detected by DWI. As the b value increased, tumor signal-to-noise ratio and contrast-to-noise ratio between the tumor and normal liver gradually decreased, but the tumor signal-intensity ratio gradually increased. When b = 800 s/mm 2 , contrast-to-noise ratio between tumor and normal liver, tumor signal-intensity ratio, and tumor signal-to-noise ratio of diffusion-weighted images were all higher than those of T2-weighted images; the differences were statistically significant (P 2 was the best in DWI of extrahepatic cholangiocarcinoma; the lesion ADC value declined as the degree of cancerous tissue differentiation decreased.

Accelerated diffusion controlled creep of polycrystalline materials. Communication 1. Model of diffusion controlled creep acceleration

International Nuclear Information System (INIS)

Smirnova, E.S.; Chuvil'deev, V.N.

1998-01-01

The model is suggested which describes the influence of large-angle grain boundary migration on a diffusion controlled creep rate in polycrystalline materials (Coble creep). The model is based on the concept about changing the value of migrating boundary free volume when introducing dislocations distributed over the grain bulk into this boundary. Expressions are obtained to calculate the grain boundary diffusion coefficient under conditions of boundary migration and the parameter, which characterized the value of Coble creep acceleration. A comparison is made between calculated and experimental data for Cd, Co and Fe

Results on positron diffusion in Si

International Nuclear Information System (INIS)

Nielsen, B.; Lynn, K.G.; Vehanen, A.; Schultz, P.J.

1984-10-01

Positron diffusion in Si(100) and Si(111) has been measured using a variable energy positron beam. The diffusion related parameter, E 0 is found to be 4.2 +- 0.2 keV, significantly longer than previously reported values. The positron diffusion coefficient is estimated at D/sub +/ = 2.3 +- 0.4 cm 2 /sec, the uncertainty arising mainly from the characteristics of the assumed positron implantation profile. A drastic reduction in E 0 is found after heating the sample to 1300 0 K, showing that previously reported low values of E 0 are associated with the thermal history of the sample. A high sensitivity to defects introduced by low energy ion bombardment is found, and the defect recovery was followed during heat treatments. Reconstruction of the Si(111) surface into the so-called 7 x 7 structure had no detectable influence on the positron diffusion behavior. No changes in the positron diffusion was observed after covering the surface with atomic hydrogen. However the yield of positronium formation at the surface was enhanced, attributed to an increased density of states at the surface

Functional evaluation of the kidney by diffusion-weighted MR imaging

International Nuclear Information System (INIS)

Hasegawa, Taro; Hasegawa, Norio; Irie, Takeo; Fukuda, Kunihiko

2003-01-01

The purpose of this study was to determine the relationship between the apparent diffusion coefficient (ADC) and diffuse renal disease by diffusion-weighted echo planar magnetic resonance (MR) imaging (EPI). Ten volunteers, seven patients with chronic renal failure and eighteen recipients of renal transplants were examined with diffusion-weighted EPI. We compared renal function (serum creatinine level) with provided ADC value. The average ADC values were 2.63 x 10 -3 mm 2 /sec for the whole kidney, 2.67 x 10 -3 mm 2 /sec for the cortex and 2.61 x 10 -3 mm 2 /sec for the medulla in normal kidneys. ADC values in the whole kidney, the cortex and the medulla in chronic renal failure were significantly lower than those for normal kidneys. In renal transplantation kidneys, the ADC values in the cortex were significantly lower than those for normal kidney. There was a linear correlation between ADC value and serum creatinine level. Our results show that diffusion-weighted MR imaging may be useful to identify renal dysfunction. (author)

Tuberous sclerosis: diffusion MRI findings in the brain

International Nuclear Information System (INIS)

Sener, R.N.

2002-01-01

Diffusion MRI has mainly been used for detection of acute ischemia, and for distinction of cytotoxic and vasogenic edema. We applied diffusion MRI in patients with tuberous sclerosis in order to evaluate diffusion imaging characteristics of parenchymal changes. Five children with known tuberous sclerosis were included in this study. The MRI examinations were performed on a 1.5-T MR unit. Diffusion MRI was obtained using the echo-planar imaging sequence. Apparent diffusion coefficient (ADC) values from the abnormal brain parenchyma were calculated directly from automatically generated ADC maps. Seven normal children were available for comparison. In this control group the mean ADC value of the normal white matter was 0.84±0.12 x 10 -3 mm 2 /s. In tuberous sclerosis patients the mean ADC value of the white matter hamartomas (n=20) was apparently high (1.52±0.24 x 10 -3 mm 2 /s) compared with that of normal white matter. The ADC value of calcified hamartomas was ''zero''. The ADC value within a giant cell tumor was 0.89 x 10 -3 mm 2 /s, similar to that of normal cerebral white matter. The ADC maps were superior to b=1000 s/mm 2 (true diffusion) images with respect to lesion evaluation, and they provided mathematical information on tissue integrity. With respect to detection of the exact numbers and sizes of the parenchymal hamartomas fluid-attenuated inversion recovery images were superior to ADC maps. It is believed that diffusion MRI can be useful in evaluation of various parenchymal changes associated with tuberous sclerosis. Further studies on tuberous sclerosis, and on various brain lesions, would provide increasing data on this relatively new MRI sequence. (orig.)

Uranium enrichment by the gaseous diffusion process

International Nuclear Information System (INIS)

Petit, J.F.

1977-01-01

After a brief description of the process and technology (principle, stage constitution, cascade constitution, and description of a plant), the author gives the history of gaseous diffusion and describes the existing facilities. Among the different enrichment processes contemplated in the USA during and after the last world war, gaseous diffusion has been the only one to be developed industrially on a wide scale in the USA, then in the UK, in the USSR and in France. The large existing capacities in the USA provided the country with a good starting base for the development of a light-water nuclear power plant programme, the success of which led to a shortfall in production means. France and the USA, possessing the necessary know-how, have been able to undertake the realization of two industrial programmes: the CIP-CUP programme in the USA and the Eurodif project in France. Current plans still call for the construction of several plants by 1990. Can the gaseous diffusion process meet this challenge. Technically, there is no doubt about it. Economically, this process is mainly characterized by large energy consumption and the necessity to build large plants. This leads to a large investment, at least for the first plant. Other processes have been developed with a view to reducing both energy and capital needs. However, in spite of continuous studies and technological progress, no process has yet proved competitive. Large increments in capacities are still expected to come from gaseous diffusion, and several projects taking into account the improvements in flexibility, automatization, reliability and reduced investment, are analysed in the paper. Combining new facilities with existing plants has already proved to be of great interest. This situation explains why gaseous diffusion is being further investigated and new processes are being studied. (author)

Diffusion tensor magnetic resonance imaging of the breast: a pilot study

International Nuclear Information System (INIS)

Baltzer, Pascal A.T.; Schaefer, Anja; Dietzel, Matthias; Kaiser, Werner A.; Graessel, David; Gajda, Mieczyslaw; Camara, Oumar

2011-01-01

Diffusion-weighted MR imaging has shown diagnostic value for differential diagnosis of breast lesions. Diffusion tensor imaging (DTI) adds information about tissue microstructure by addressing diffusion direction. We have examined the diagnostic application of DTI of the breast. A total of 59 patients (71 lesions: 54 malignant, 17 benign) successfully underwent prospective echo planar imaging-DTI (EPI-DTI) (1.5 T). First, diffusion direction both of parenchyma as well as lesions was assessed on parametric maps. Subsequently, apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values were measured. Statistics included univariate (Mann-Whitney U test, receiver operating analysis) and multivariate (logistic regression analysis, LRA) tests. Main diffusion direction of parenchyma was anterior-posterior in the majority of cases (66.1%), whereas lesions (benign, malignant) showed no predominant diffusion direction in the majority of cases (23.9%). ADC values showed highest differences between benign and malignant lesions (P < 0.001) with resulting area under the curve (AUC) of 0.899. FA values were lower in benign (interquartile range, IR, 0.14-0.24) compared to malignant lesions (IR 0.21-0.35, P < 0.002) with an AUC of 0.751-0.770. Following LRA, FA did not prove to have incremental value for differential diagnosis over ADC values. Microanatomical differences between benign and malignant breast lesions as well as breast parenchyma can be visualized by using DTI. (orig.)

The value of diffusion tensor imaging in differentiating high-grade gliomas from brain metastases: a systematic review and meta-analysis.

Directory of Open Access Journals (Sweden)

Rui Jiang

Full Text Available Differentiation of high-grade gliomas and solitary brain metastases is an important clinical issue because the treatment strategies differ greatly. Our study aimed to investigate the potential value of diffusion tensor imaging (DTI in differentiating high-grade gliomas from brain metastases using a meta-analytic approach.We searched Pubmed, Embase and the Cochrane Library for relevant articles published in English. Studies that both investigated high-grade gliomas and brain metastases using DTI were included. Random effect model was used to compare fractional anisotropy (FA and mean diffusivity (MD values in the two tumor entities.Nine studies were included into the meta-analysis. In the peritumoral region, compared with brain metastases, high-grade gliomas had a significant increase of FA (SMD  = 0.47; 95% CI, 0.22-0.71; P<0.01 and a significant decrease of MD (SMD  = -1.49; 95% CI, -1.91 to -1.06; P<0.01. However, in the intratumoral area, no significant change in FA (SMD  = 0.16; 95% CI, -0.49 to 0.82; P = 0.73 or MD (SMD  = 0.34; 95% CI, -0.91 to 1.60; P = 0.59 was detected between gliomas and metastases.High-grade gliomas may be distinguished from brain metastases by comparing the peritumoral FA and MD values. DTI appears to be a promising tool in diagnosing solitary intracranial lesions.

MR imaging evidence of anisotropic diffusion in the cat brain

International Nuclear Information System (INIS)

Moseley, M.E.; Mintorovich, J.; Cohen, Y.; Chilevitt, L.; Tsuruda, J.; Norman, D.; Weinstein, P.

1989-01-01

This paper discusses a study of diffusion behavior of brain water in the cat. Diffusion-weighted images, acquired with large gradient b values of 1,000-2,000 sec/mm 2 , showed no clear evidence of anisotropic water diffusion in either gray matter or basal ganglia. Large directional differences in image intensities and diffusion values were observed in cortical and deep white matter. Faster diffusion was sen when the direction of the applied diffusion gradient was parallel to the orientation of the white matter. Diffusion perpendicular to the gradient direction was significantly lower. This effect was proportional to gradient duration and strength and was seen in both pre- and immediate post-mortem images in all axial, sagittal, and coronal images

Review of enhanced vapor diffusion in porous media

International Nuclear Information System (INIS)

Webb, S.W.; Ho, C.K.

1998-01-01

Vapor diffusion in porous media in the presence of its own liquid has often been treated similar to gas diffusion. The gas diffusion rate in porous media is much lower than in free space due to the presence of the porous medium and any liquid present. However, enhanced vapor diffusion has also been postulated such that the diffusion rate may approach free-space values. Existing data and models for enhanced vapor diffusion, including those in TOUGH2, are reviewed in this paper

Fractional anisotropy and diffusivity changes in thyroid-associated orbitopathy

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Han, Ji Sung; Seo, Hyung Suk; Lee, Young Hen [Korea University Ansan Hospital, Department of Radiology, Ansan, Gyeonggido (Korea, Republic of); Lee, Hwa [Korea University Ansan Hospital, Department of Ophthalmology, Ansan (Korea, Republic of); Suh, Sang-il [Korea University Guro Hospital, Department of Radiology, Seoul (Korea, Republic of); Jeong, Eun-Kee; Sapkota, Nabraj [University of Utah, Utah Center for Advanced Imaging Research, Salt Lake City, UT (United States); Kim, Ki Joon [Nanoori Hospital, Department of Neurosurgery, Seoul (Korea, Republic of)

2016-12-15

To investigate the extraocular muscle (EOM) changes in thyroid-associated orbitopathy (TAO) on DTI and the correlations between DTI parameters and clinical features. Twenty TAO patients and 20 age- and sex-matched controls provided informed consent and were enrolled. Ten-directional DTI was acquired in orbit. Fractional anisotropy (FA), mean, axial, and radial diffusivities were obtained at medial and lateral EOMs in both orbits. EOM thickness was measured in patients using axial CT images. FA and diffusivities were compared between patients and controls. The relationships between DTI values and muscle thickness and exophthalmos were evaluated. DTI values compared between patients in active and inactive phases by clinical activity score of TAO. DTI values were also compared between acute and chronic stages by the duration of disease. In medial EOM, FA was significantly lower in patients (p < 0.001) and negatively correlated with muscle thickness (r = -0.604, p < 0.001). Radial diffusivity was significantly higher in patients (p = 0.010) and correlated with muscle thickness (r = 0.349, p = 0.027). In lateral EOM, DTI values did not differ between patients and controls. In the acute stage, the diffusivities of the medial rectus EOM were increased compared with the chronic stage. DTI values of the medial and lateral rectus EOM did not differ significantly between active and inactive phases. DTI can be used to diagnose TAO with FA and radial diffusivity change in EOM. Diffusivities can be used to differentiate acute and chronic stage of TAO. However, DTI values showed limitation in reflecting TAO activity according to the CAS. (orig.)

Predictive value of diffusion-weighted imaging without and with including contrast-enhanced magnetic resonance imaging in image analysis of head and neck squamous cell carcinoma

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Noij, Daniel P., E-mail: d.noij@vumc.nl [Department of Radiology and Nuclear Medicine, VU University Medical Center, De Boelelaan 1117, Amsterdam, Noord-Holland (Netherlands); Pouwels, Petra J.W., E-mail: pjw.pouwels@vumc.nl [Department of Physics and Medical Technology, VU University Medical Center, De Boelelaan 1117, Amsterdam, Noord-Holland (Netherlands); Ljumanovic, Redina, E-mail: rljumanovic@adventh.org [Department of Radiology and Nuclear Medicine, VU University Medical Center, De Boelelaan 1117, Amsterdam, Noord-Holland (Netherlands); Knol, Dirk L., E-mail: dirklknol@gmail.com [Department of Epidemiology and Biostatistics, VU University Medical Center, De Boelelaan 1117, Amsterdam, Noord-Holland (Netherlands); Doornaert, Patricia, E-mail: p.doornaert@vumc.nl [Department of Radiation Oncology, VU University Medical Center, De Boelelaan 1117, Amsterdam, Noord-Holland (Netherlands); Bree, Remco de, E-mail: r.debree@vumc.nl [Department of Otolaryngology – Head and Neck Surgery, VU University Medical Center, De Boelelaan 1117, Amsterdam, Noord-Holland (Netherlands); Castelijns, Jonas A., E-mail: j.castelijns@vumc.nl [Department of Radiology and Nuclear Medicine, VU University Medical Center, De Boelelaan 1117, Amsterdam, Noord-Holland (Netherlands); Graaf, Pim de, E-mail: p.degraaf@vumc.nl [Department of Radiology and Nuclear Medicine, VU University Medical Center, De Boelelaan 1117, Amsterdam, Noord-Holland (Netherlands)

2015-01-15

Highlights: • Primary tumor volume and lymph node ADC1000 are predictors of survival. • CE-T1WI does not improve the prognostic capacity of DWI. • Using CE-T1WI for ROI placement results in lower interobserver agreement. - Abstract: Objectives: To assess disease-free survival (DFS) in head and neck squamous cell carcinoma (HNSCC) treated with (chemo)radiotherapy ([C]RT). Methods: Pretreatment MR-images of 78 patients were retrospectively studied. Apparent diffusion coefficients (ADC) were calculated with two sets of two b-values: 0–750 s/mm{sup 2} (ADC{sub 750}) and 0–1000 s/mm{sup 2} (ADC{sub 1000}). One observer assessed tumor volume on T1-WI. Two independent observers assessed ADC-values of primary tumor and largest lymph node in two sessions (i.e. without and with including CE-T1WI in image analysis). Interobserver and intersession agreement were assessed with intraclass correlation coefficients (ICC) separately for ADC{sub 750} and ADC{sub 1000}. Lesion volumes and ADC-values were related to DFS using Cox regression analysis. Results: Median follow-up was 18 months. Interobserver ICC was better without than with CE-T1WI (primary tumor: 0.92 and 0.75–0.83, respectively; lymph node: 0.81–0.83 and 0.61–0.64, respectively). Intersession ICC ranged from 0.84 to 0.89. With CE-T1WI, mean ADC-values of primary tumor and lymph node were higher at both b-values than without CE-T1WI (P < 0.001). Tumor volume (sensitivity: 73%; specificity: 57%) and lymph node ADC{sub 1000} (sensitivity: 71–79%; specificity: 77–79%) were independent significant predictors of DFS without and with including CE-T1WI (P < 0.05). Conclusions: Pretreatment primary tumor volume and lymph node ADC{sub 1000} were significant independent predictors of DFS in HNSCC treated with (C)RT. DFS could be predicted from ADC-values acquired without and with including CE-T1WI in image analysis. The inclusion of CE-T1WI did not result in significant improvements in the predictive value of

Value of diffusion-weighted imaging in predicting parametrial invasion in stage IA2-IIA cervical cancer

International Nuclear Information System (INIS)

Park, Jung Jae; Kim, Chan Kyo; Park, Sung Yoon; Park, Byung Kwan; Kim, Bohyun

2014-01-01

To investigate the value of diffusion-weighted imaging (DWI) in evaluating parametrial invasion (PMI) in stage IA2-IIA cervical cancer. A total of 117 patients with stage IA2-IIA cervical cancer who underwent preoperative MRI and radical hysterectomy were included in this study. Preoperative clinical variables and MRI variables were analysed and compared between the groups with and without pathologically proven PMI. All variables except age were significantly different between patients with and without pathologic PMI (P < 0.05). All variables except squamous cell carcinoma (SCC) antigen were also significantly correlated with pathologic PMI on univariate analysis (P < 0.05). Multivariate analysis indicated that PMI on MRI (P < 0.001) and tumour apparent diffusion coefficient (ADC) (P = 0.029) were independent predictors of pathologic PMI. Area under the curve of PMI on MRI increased significantly from 0.793 to 0.872 when combined with tumour ADC (P = 0.002). When PMI on MRI was further stratified by tumour ADC, the false negative rate was 2.0 % (1/49). In stage IA2-IIA cervical cancer, tumour ADC and PMI on MRI seem to be independent predictors of pathologic PMI. Combining the two predictors improved the diagnostic performance of identifying patients at low risk of pathologic PMI. (orig.)

Apparent diffusion coefficient in the analysis of prostate cancer: determination of optimal b-value pair to differentiate normal from malignant tissue.

Science.gov (United States)

Adubeiro, Nuno; Nogueira, Maria Luísa; Nunes, Rita G; Ferreira, Hugo Alexandre; Ribeiro, Eduardo; La Fuente, José Maria Ferreira

Determining optimal b-value pair for differentiation between normal and prostate cancer (PCa) tissues. Forty-three patients with diagnosis or PCa symptoms were included. Apparent diffusion coefficient (ADC) was estimated using minimum and maximum b-values of 0, 50, 100, 150, 200, 500s/mm2 and 500, 800, 1100, 1400, 1700 and 2000s/mm2, respectively. Diagnostic performances were evaluated when Area-under-the-curve (AUC)>95%. 15 of the 35 b-values pair surpassed this AUC threshold. The pair (50, 2000s/mm2) provided the highest AUC (96%) with ADC cutoff 0.89×10- 3 mm 2 /s, sensitivity 95.5%, specificity 93.2% and accuracy 94.4%. The best b-value pair was b=50, 2000s/mm2. Copyright © 2017 Elsevier Inc. All rights reserved.

Clinical utility of apparent diffusion coefficient values obtained using high b-value when diagnosing prostate cancer using 3 tesla MRI: comparison between ultra-high b-value (2000 s/mm²) and standard high b-value (1000 s/mm²).

Science.gov (United States)

Kitajima, Kazuhiro; Takahashi, Satoru; Ueno, Yoshiko; Yoshikawa, Takeshi; Ohno, Yoshiharu; Obara, Makoto; Miyake, Hideaki; Fujisawa, Masato; Sugimura, Kazuro

2012-07-01

To determine whether the apparent diffusion coefficient (ADC) obtained using b = 2000 s/mm(2) upon 3 Tesla (T) diffusion-weighted MRI is superior to b = 1000 s/mm(2) for discriminating malignant from normal prostate tissue and predicting the aggressiveness of prostate cancer, using histopathological findings of radical prostatectomy as a reference. Eighty prostate cancer patients underwent preoperative 3T MRI including diffusion weighted imaging with b-values of 0, 1000, and 2000 s/mm(2) . ADCs were measured for malignant lesions and normal sites on three sets of ADC maps calculated with monoexponential fitting between b = 0 and 1000, 0 and 2000, and 1000 and 2000, respectively. The relationship between the ADC and Gleason score was evaluated. The areas under the ROC curves for b = 0,1000, b = 0,2000, and b = 1000,2000 were 0.896, 0.937, and 0.857, respectively, in the peripheral zone (PZ) and 0.877, 0.889, and 0.731, respectively, in the transition zone (TZ). The difference between b = 0,1000 and b = 0,2000 was significant in PZ (P = 0.033), but not in TZ (P = 0.84). Weak but significant negative correlations were identified between ADCs and Gleason score in both PZ and TZ cancer at b = 0,1000 and b = 0,2000 (r = -0.323 to -0.341). For 3T MRI, ADCs using b = 0,2000 are more accurate than b = 0,1000 for diagnosing PZ cancer, and as accurate for TZ cancer. Copyright © 2012 Wiley Periodicals, Inc.

Diffusion in a liquid alloy - theories and experiments

International Nuclear Information System (INIS)

Chastang, C.

1997-01-01

Different theories concerning the calculation of diffusion coefficients in liquid metals, as well for auto as for hetero-diffusion are presented and some experimental procedures using tracer techniques in shear cells and capillary tubes are described. Diffusion curves are calculated with the TRIO-EF code. Calculated and measured values of diffusion coefficients are compared and discussed with regard to various diffusion mechanisms. Copper gadolinium mixtures have been investigated in more detail. (C.B.)

Advanced manufacturing: Technology diffusion

Energy Technology Data Exchange (ETDEWEB)

Tesar, A.

1995-12-01

In this paper we examine how manufacturing technology diffuses rom the developers of technology across national borders to those who do not have the capability or resources to develop advanced technology on their own. None of the wide variety of technology diffusion mechanisms discussed in this paper are new, yet the opportunities to apply these mechanisms are growing. A dramatic increase in technology diffusion occurred over the last decade. The two major trends which probably drive this increase are a worldwide inclination towards ``freer`` markets and diminishing isolation. Technology is most rapidly diffusing from the US In fact, the US is supplying technology for the rest of the world. The value of the technology supplied by the US more than doubled from 1985 to 1992 (see the Introduction for details). History shows us that technology diffusion is inevitable. It is the rates at which technologies diffuse to other countries which can vary considerably. Manufacturers in these countries are increasingly able to absorb technology. Their manufacturing efficiency is expected to progress as technology becomes increasingly available and utilized.

Research of Innovation Diffusion on Industrial Networks

Directory of Open Access Journals (Sweden)

Yongtai Chen

2014-01-01

Full Text Available The real value of innovation consists in its diffusion on industrial network. The factors which affect the diffusion of innovation on industrial network are the topology of industrial network and rules of diffusion. Industrial network is a complex network which has scale-free and small-world characters; its structure has some affection on threshold, length of path, enterprise’s status, and information share of innovation diffusion. Based on the cost and attitude to risk of technical innovation, we present the “avalanche” diffusing model of technical innovation on industrial network.

Comparison of non-Gaussian and Gaussian diffusion models of diffusion weighted imaging of rectal cancer at 3.0 T MRI.

Science.gov (United States)

Zhang, Guangwen; Wang, Shuangshuang; Wen, Didi; Zhang, Jing; Wei, Xiaocheng; Ma, Wanling; Zhao, Weiwei; Wang, Mian; Wu, Guosheng; Zhang, Jinsong

2016-12-09

Water molecular diffusion in vivo tissue is much more complicated. We aimed to compare non-Gaussian diffusion models of diffusion-weighted imaging (DWI) including intra-voxel incoherent motion (IVIM), stretched-exponential model (SEM) and Gaussian diffusion model at 3.0 T MRI in patients with rectal cancer, and to determine the optimal model for investigating the water diffusion properties and characterization of rectal carcinoma. Fifty-nine consecutive patients with pathologically confirmed rectal adenocarcinoma underwent DWI with 16 b-values at a 3.0 T MRI system. DWI signals were fitted to the mono-exponential and non-Gaussian diffusion models (IVIM-mono, IVIM-bi and SEM) on primary tumor and adjacent normal rectal tissue. Parameters of standard apparent diffusion coefficient (ADC), slow- and fast-ADC, fraction of fast ADC (f), α value and distributed diffusion coefficient (DDC) were generated and compared between the tumor and normal tissues. The SEM exhibited the best fitting results of actual DWI signal in rectal cancer and the normal rectal wall (R 2  = 0.998, 0.999 respectively). The DDC achieved relatively high area under the curve (AUC = 0.980) in differentiating tumor from normal rectal wall. Non-Gaussian diffusion models could assess tissue properties more accurately than the ADC derived Gaussian diffusion model. SEM may be used as a potential optimal model for characterization of rectal cancer.

Concentration dependent hydrogen diffusion in tungsten

Energy Technology Data Exchange (ETDEWEB)

Ahlgren, T., E-mail: tommy.ahlgren@helsinki.fi; Bukonte, L.

2016-10-15

The diffusion of hydrogen in tungsten is studied as a function of temperature, hydrogen concentration and pressure using Molecular Dynamics technique. A new analysis method to determine diffusion coefficients that accounts for the random oscillation of atoms around the equilibrium position is presented. The results indicate that the hydrogen migration barrier of 0.25 eV should be used instead of the presently recommended value of 0.39 eV. This conclusion is supported by both experiments and density functional theory calculations. Moreover, the migration volume at the saddle point for H in W is found to be positive: ΔV{sub m} ≈ 0.488 Å{sup 3}, leading to a decrease in the diffusivity at high pressures. At high H concentrations, a dramatic reduction in the diffusion coefficient is observed, due to site blocking and the repulsive H-H interaction. The results of this study indicates that high flux hydrogen irradiation leads to much higher H concentrations in tungsten than expected. - Highlights: • The recommended value of 0.39 eV for the H in W migration barrier should be changed to 0.25 eV. • The random oscillation of atoms around the equilibrium position can be dealt with in diffusion simulations. • Hydrogen diffusion in tungsten is highly concentration dependent.

Natural gas diffusion model and diffusion computation in well Cai25 Bashan Group oil and gas reservoir

Institute of Scientific and Technical Information of China (English)

无

2001-01-01

Natural gas diffusion through the cap rock is mainly by means ofdissolving in water, so its concentration can be replaced by solubility, which varies with temperature, pressure and salinity in strata. Under certain geological conditions the maximal solubility is definite, so the diffusion com-putation can be handled approximately by stable state equation. Furthermore, on the basis of the restoration of the paleo-buried history, the diffusion is calculated with the dynamic method, and the result is very close to the real diffusion value in the geological history.

Suitability of various materials for porous filters in diffusion experiments

Energy Technology Data Exchange (ETDEWEB)

Aldaba, David; Vidal, Miquel; Rigol, Anna [Univ. de Barcelona (Spain). Dept. de Quimica Analitica; Glaus, Martin; Van Loon, Luc [Paul Scherrer Institut, Villigen PSI (Switzerland). Lab. for Waste Management; Leupin, Olivier [Nagra, Wettingen (Switzerland)

2014-10-01

The suitability of different porous materials (stainless steel, VYCOR {sup registered} glass, Al{sub 2}O{sub 3} and PEEK) for use as confining filters in diffusion experiments was evaluated by measuring the effective diffusion coefficients (D{sub e}) of neutral (HTO) and ionic solutes (Na{sup +}, Cs{sup +}, Sr{sup 2+}, Cl{sup -}, SeO{sub 4}{sup 2-}) in the materials in through-diffusion experiments. For stainless steel filters, the D{sub e} values of the target solutes correlated satisfactorily with their bulk diffusion coefficient in water (D{sub w}); thus, the diffusion process in the stainless steel filters was primarily controlled by the diffusivity of the solvated ions. For the remaining materials, the D{sub e} and D{sub w} values were also correlated for the target solutes, and the geometric factors were in the sequence: VYCOR {sup registered} glass < Al{sub 2}O{sub 3} < PEEK. Stainless steel and VYCOR {sup registered} glass were the most appropriate materials because of their high D{sub e} values, but a specific interaction of caesium with VYCOR {sup registered} glass was hypothesised because the D{sub e} values obtained for this solute were slightly higher than expected.

A Longitudinal Magnetic Resonance Imaging Study of the Apparent Diffusion Coefficient Values in Corpus Callosum during the First Year after Traumatic Brain Injury

Science.gov (United States)

Håberg, Asta Kristine; Skandsen, Toril; Finnanger, Torun Gangaune; Vik, Anne

2014-01-01

Abstract The objective of this study was to explore the evolution of apparent diffusion coefficient (ADC) values in magnetic resonance imaging (MRI) in normal-appearing tissue of the corpus callosum during the 1st year after traumatic brain injury (TBI), and relate findings to outcome. Fifty-seven patients (mean age 34 [range 11–63] years) with moderate to severe TBI were examined with diffusion weighted MRI at three time points (median 7 days, 3 and 12 months), and a sex- and age-matched control group of 47 healthy individuals, were examined once. The corpus callosum was subdivided and the mean ADC values computed blinded in 10 regions of interests without any visible lesions in the ADC map. Outcome measures were Glasgow Outcome Scale Extended (GOSE) and neuropsychological domain scores at 12 months. We found a gradual increase of the mean ADC values during the 12 month follow-up, most evident in the posterior truncus (r=0.19, pGOSE score ≤6) showed evidence of increased mean ADC values in the genu and posterior truncus at 12 months. Mean ADC values in posterior parts of the corpus callosum at 3 months predicted the sensory-motor function domain score (p=0.010–0.028). During the 1st year after moderate and severe TBI, we demonstrated a slowly evolving disruption of the microstructure in normal appearing corpus callosum in the ADC map, most evident in the posterior truncus. The mean ADC values were associated with both outcome and ability to perform speeded, complex sensory-motor action. PMID:23837731

Peritumoral edema of meningiomas and metastatic brain tumors: differences in diffusion characteristics evaluated with diffusion-tensor MR imaging

Energy Technology Data Exchange (ETDEWEB)

Toh, Cheng-Hong; Wong, Alex M.-C; Wong, Ho-Fai; Wan, Yung-Liang [Chang Gung Memorial Hospital, Department of Medical Imaging and Intervention, Tao-Yuan (China); Chang Gung University, School of Medicine and Medical Technology, Tao-Yuan (China); Wei, Kuo-Chen [Chang Gung Memorial Hospital, Department of Neurosurgery, Tao-Yuan (China); Chang Gung University, School of Medicine and Medical Technology, Tao-Yuan (China); Ng, Shu-Hang [Chang Gung Memorial Hospital, Department of Medical Imaging and Intervention, Tao-Yuan (China); Chang Gung University, School of Medicine and Medical Technology, Tao-Yuan (China); Chang Gung Memorial Hospital, Molecular Image Center, Tao-Yuan (China)

2007-06-15

We prospectively compared the fractional anisotropy (FA) and mean diffusivity (MD) of the peritumoral edema of meningiomas and metastatic brain tumors with diffusion-tensor magnetic resonance (MR) imaging. The study protocol was approved by the local ethics committee, and written informed consent was obtained. Preoperative diffusion-tensor MR imaging was performed in 15 patients with meningiomas and 11 patients with metastatic brain tumors. Regions of interest (ROI) were placed in the peritumoral edema and normal-appearing white matter (NAWM) of the contralateral hemisphere to measure the FA and MD. The FA and MD ratios were calculated for each ROI in relation to the NAWM of the contralateral hemisphere. Changes in peritumoral MD and FA, in terms of primary values and ratios, were compared using a two-sample t-test; P < 0.05 was taken as indicating statistical significance. The mean MD values (x 10{sup -3} mm{sup 2}/s) of the peritumoral edema for metastases and meningiomas, respectively, were 0.902 {+-} 0.057 and 0.820 {+-} 0.094, the mean MD ratios were 220.3 {+-} 22.6 and 193.1 {+-} 23.4, the mean FA values were 0.146 {+-} 0.026 and 0.199 {+-} 0.052, and the mean FA ratios were 32.3 {+-} 5.9 and 46.0 {+-} 12.1. All the values were significantly different between metastases and meningiomas (MD values P = 0.016, MD ratios P = 0.006, FA values P = 0.005, FA ratios P = 0.002). The peritumoral edema of metastatic brain tumors and meningiomas show different MD and FA on diffusion-tensor MR imaging. (orig.)

Intravoxel water diffusion heterogeneity MR imaging of nasopharyngeal carcinoma using stretched exponential diffusion model

International Nuclear Information System (INIS)

Lai, Vincent; Khong, Pek Lan; Lee, Victor Ho Fun; Lam, Ka On; Sze, Henry Chun Kin; Chan, Queenie

2015-01-01

To determine the utility of stretched exponential diffusion model in characterisation of the water diffusion heterogeneity in different tumour stages of nasopharyngeal carcinoma (NPC). Fifty patients with newly diagnosed NPC were prospectively recruited. Diffusion-weighted MR imaging was performed using five b values (0-2,500 s/mm 2 ). Respective stretched exponential parameters (DDC, distributed diffusion coefficient; and alpha (α), water heterogeneity) were calculated. Patients were stratified into low and high tumour stage groups based on the American Joint Committee on Cancer (AJCC) staging for determination of the predictive powers of DDC and α using t test and ROC curve analyses. The mean ± standard deviation values were DDC = 0.692 ± 0.199 (x 10 -3 mm 2 /s) for low stage group vs 0.794 ± 0.253 (x 10 -3 mm 2 /s) for high stage group; α = 0.792 ± 0.145 for low stage group vs 0.698 ± 0.155 for high stage group. α was significantly lower in the high stage group while DDC was negatively correlated. DDC and α were both reliable independent predictors (p < 0.001), with α being more powerful. Optimal cut-off values were (sensitivity, specificity, positive likelihood ratio, negative likelihood ratio) DDC = 0.692 x 10 -3 mm 2 /s (94.4 %, 64.3 %, 2.64, 0.09), α = 0.720 (72.2 %, 100 %, -, 0.28). The heterogeneity index α is robust and can potentially help in staging and grading prediction in NPC. (orig.)

Diffusion tensor magnetic resonance imaging of the pancreas.

Directory of Open Access Journals (Sweden)

Noam Nissan

Full Text Available To develop a diffusion-tensor-imaging (DTI protocol that is sensitive to the complex diffusion and perfusion properties of the healthy and malignant pancreas tissues.Twenty-eight healthy volunteers and nine patients with pancreatic-ductal-adenocacinoma (PDAC, were scanned at 3T with T2-weighted and DTI sequences. Healthy volunteers were also scanned with multi-b diffusion-weighted-imaging (DWI, whereas a standard clinical protocol complemented the PDAC patients' scans. Image processing at pixel resolution yielded parametric maps of three directional diffusion coefficients λ1, λ2, λ3, apparent diffusion coefficient (ADC, and fractional anisotropy (FA, as well as a λ1-vector map, and a main diffusion-direction map.DTI measurements of healthy pancreatic tissue at b-values 0,500 s/mm² yielded: λ1 = (2.65±0.35×10⁻³, λ2 = (1.87±0.22×10⁻³, λ3 = (1.20±0.18×10⁻³, ADC = (1.91±0.22×10⁻³ (all in mm²/s units and FA = 0.38±0.06. Using b-values of 100,500 s/mm² led to a significant reduction in λ1, λ2, λ3 and ADC (p<.0001 and a significant increase (p<0.0001 in FA. The reduction in the diffusion coefficients suggested a contribution of a fast intra-voxel-incoherent-motion (IVIM component at b≤100 s/mm², which was confirmed by the multi-b DWI results. In PDACs, λ1, λ2, λ3 and ADC in both 0,500 s/mm² and 100,500 s/mm² b-values sets, as well as the reduction in these diffusion coefficients between the two sets, were significantly lower in comparison to the distal normal pancreatic tissue, suggesting higher cellularity and diminution of the fast-IVIM component in the cancer tissue.DTI using two reference b-values 0 and 100 s/mm² enabled characterization of the water diffusion and anisotropy of the healthy pancreas, taking into account a contribution of IVIM. The reduction in the diffusion coefficients of PDAC, as compared to normal pancreatic tissue, and the smaller change in these coefficients in PDAC

Measurement of the apparent diffusion coefficient in paediatric mitochondrial encephalopathy cases and a comparison of parenchymal changes associated with the disease using follow-up diffusion coefficient measurements

Energy Technology Data Exchange (ETDEWEB)

Uysal, Fatma, E-mail: afatmauysal@gmail.com [Dokuz Eylül University, Department of Pediatric Radiology, Izmir (Turkey); Çakmakçı, Handan, E-mail: handan.cakmakci@deu.edu.tr [Dokuz Eylül University, Department of Pediatric Radiology, Izmir (Turkey); Yiş, Uluç, E-mail: ulucyis@deu.edu.tr [Dokuz Eylül University, Department of Pediatric Neurology, Izmir (Turkey); Ellidokuz, Hülya, E-mail: hulyaellidokuz@deu.edu.tr [Dokuz Eylül University, Department of Medical Statistics, Izmir (Turkey); Hız, Ayşe Semra, E-mail: aysesemrahiz@deu.edu.tr [Dokuz Eylül University, Department of Pediatric Neurology, Izmir (Turkey)

2014-01-15

Objectives: To reveal the contribution of MRI and diffusion-weighted imaging (DWI) to the diagnosis of mitochondrial encephalopathy (ME) and to evaluate the parenchymal changes associated with this disease in the involved parenchymal areas using the apparent diffusion coefficient (ADC) parameter. Methods: Ten patients who had undergone MRI and DWI analysis with a pre-diagnosis of neurometabolic disease, and who were subsequently diagnosed with ME in laboratory and/or genetic studies, were included in our study. ADC values were compared with a control group composed of 20 patients of similar age with normal brains. Evaluations involved measurements made in 20 different areas determined on the ADC map. The dominance or contribution of ADC coefficient measurements to the conventional sequences was compared with the controls. Results: In the first examination, an increase in both diffusion and ADC values was detected in six cases and diffusion restriction and a decrease in ADC values in three patients. While an increase in both diffusion and ADC values was demonstrated in four cases, there was diffusion restriction and a decrease in ADC values in three cases in the control examinations. Conclusions: DWI provides information that complements conventional MRI sequences in the diagnosis of ME.

Intracerebral metastasis showing restricted diffusion: Correlation with histopathologic findings

Energy Technology Data Exchange (ETDEWEB)

Duygulu, G. [Radiology Department, Ege University Medicine School, Izmir (Turkey); Ovali, G. Yilmaz [Radiology Department, Celal Bayar University Medicine School, Manisa (Turkey)], E-mail: gulgun.yilmaz@bayar.edu.tr; Calli, C.; Kitis, O.; Yuenten, N. [Radiology Department, Ege University Medicine School, Izmir (Turkey); Akalin, T. [Pathology Department, Ege University Medicine School, Izmir (Turkey); Islekel, S. [Neurosurgery Department, Ege University Medicine School, Izmir (Turkey)

2010-04-15

Objective: We aimed to detect the frequency of restricted diffusion in intracerebral metastases and to find whether there is correlation between the primary tumor pathology and diffusion-weighted MR imaging (DWI) findings of these metastases. Material and methods: 87 patients with intracerebral metastases were examined with routine MR imaging and DWI. 11 hemorrhagic metastatic lesions were excluded. The routine MR imaging included three plans before and after contrast enhancement. The DWI was performed with spin-echo EPI sequence with three b values (0, 500 and 1000), and ADC maps were calculated. 76 patients with metastases were grouped according to primary tumor histology and the ratios of restricted diffusion were calculated according to these groups. ADCmin values were measured within the solid components of the tumors and the ratio of metastases with restricted diffusion to that which do not show restricted diffusion were calculated. Fisher's exact and Mann-Whitney U tests were used for the statistical analysis. Results: Restricted diffusion was observed in a total of 15 metastatic lesions (19, 7%). Primary malignancy was lung carcinoma in 10 of these cases (66, 6%) (5 small cell carcinoma, 5 non-small cell carcinoma), and breast carcinoma in three cases (20%). Colon carcinoma and testicular teratocarcinoma were the other two primary tumors in which restricted diffusion in metastasis was detected. There was no statistical significant difference between the primary pathology groups which showed restricted diffusion (p > 0.05). ADCmin values of solid components of the metastasis with restricted diffusion and other metastasis without restricted diffusion also showed no significant statistical difference (0.72 {+-} 0.16 x 10{sup -3} mm{sup 2}/s and 0.78 {+-} 21 x 10{sup -3} mm{sup 2}/s respectively) (p = 0.325). Conclusion: Detection of restricted diffusion on DWI in intracerebral metastasis is not rare, particularly if the primary tumor is lung or breast

Parametrical analysis on the diffuse ceiling ventilation by experimental and numerical studies

DEFF Research Database (Denmark)

Zhang, Chen; Kristensen, Martin Heine; Jensen, Jakob Sølund

2016-01-01

This paper aims to investigate the performance of diffuse ceiling ventilation in a classroom. An experimental study is carried out in a test chamber to examine the impact of diffuse ceiling opening area on the system cooling capacity and thermal comfort. The results indicate that diffuse ceiling ....... The numerical results reveal that even distribution of heat sources gives a lower draught risk environment than centralized distribution. In addition, there is a significant increase on the draught risk with increase of room height....

Diffusion paths in Ti-Zr-Nb system

International Nuclear Information System (INIS)

Omasheva, G.Sh.; Gryzunov, V.I.; Sokolovskaya, E.M.

1992-01-01

Mutual diffusion at the temperature of 1273 K was studied. Diffusional paths were plotted and matrix of mutual diffusion coefficients D ij k for 26 points of concentrational triangle was calculated. It is ascertained that all diffusion coefficients are concentration-depending values, they wary by three orders with the change in the composition, corresponding to titanium angle, to niobium one

Bounded fractional diffusion in geological media: Definition and Lagrangian approximation

Science.gov (United States)

Zhang, Yong; Green, Christopher T.; LaBolle, Eric M.; Neupauer, Roseanna M.; Sun, HongGuang

2016-01-01

Spatiotemporal Fractional-Derivative Models (FDMs) have been increasingly used to simulate non-Fickian diffusion, but methods have not been available to define boundary conditions for FDMs in bounded domains. This study defines boundary conditions and then develops a Lagrangian solver to approximate bounded, one-dimensional fractional diffusion. Both the zero-value and non-zero-value Dirichlet, Neumann, and mixed Robin boundary conditions are defined, where the sign of Riemann-Liouville fractional derivative (capturing non-zero-value spatial-nonlocal boundary conditions with directional super-diffusion) remains consistent with the sign of the fractional-diffusive flux term in the FDMs. New Lagrangian schemes are then proposed to track solute particles moving in bounded domains, where the solutions are checked against analytical or Eularian solutions available for simplified FDMs. Numerical experiments show that the particle-tracking algorithm for non-Fickian diffusion differs from Fickian diffusion in relocating the particle position around the reflective boundary, likely due to the non-local and non-symmetric fractional diffusion. For a non-zero-value Neumann or Robin boundary, a source cell with a reflective face can be applied to define the release rate of random-walking particles at the specified flux boundary. Mathematical definitions of physically meaningful nonlocal boundaries combined with bounded Lagrangian solvers in this study may provide the only viable techniques at present to quantify the impact of boundaries on anomalous diffusion, expanding the applicability of FDMs from infinite do mains to those with any size and boundary conditions.

Evaluation of the performance of three diffuse hourly irradiation models on tilted surfaces according to the utilizability concept

International Nuclear Information System (INIS)

Posadillo, R.; Lopez Luque, R.

2009-01-01

The performance of three diffuse hourly irradiation models on tilted surfaces was evaluated by making a database of hourly global and diffuse solar irradiation on a horizontal surface, as well as global solar irradiation on a tilted surface, recorded in a solar radiation station located at Cordoba University (Spain). The method for a comparison of the performance of these models was developed from a study of the 'utilizable energy' statistics, a value representing, for a specific period of time, the mean monthly radiation that exceeded a critical level of radiation. This model comparison method seemed to us to be highly suitable since it provides a way of comparing the capacity of these models to estimate, however, much energy is incident on a tilted surface above a critical radiation level. Estimated and measured values were compared using the normalized RMBE and RRMSE statistics. According to the results of the method let us verify that, of the three models evaluated, one isotropic and two anisotropic, the Reindl et al. anisotropic model was the one giving the best results.

[Quantitative analysis of diffusion-weighted magnetic resonance images during chemoradiation therapy for cancer of the cervix uteri: Prognostic role of pretreatment diffusion coefficient values].

Science.gov (United States)

Kharuzhyk, S A

2015-01-01

to carry out a quantitative analysis of diffusion-weighted magnetic resonance images (DWI) in cancer of the cervix uteri (CCU) and to estimate the possibility of using pretreatment measured diffusion coefficient (MDC) to predict chemoradiation therapy (CRT). The investigation prospectively enrolled 46 women with morphologically verified Stages IB-IVB CCU. All the women underwent diffusion-weighted magnetic resonance imaging of pelvic organs before and after treatment. A semiautomatic method was used to determine tumor signal intensity (SI) on DWI at b 1000 s/mm2 (SI b1000) and tumor MDC. The reproducibility of MDC measurements was assessed in 16 randomly selected women. The investigators compared the pretreatment quantitative DWI measures in complete and incomplete regression (CR and IR) groups and the presence and absence of tumor progression during a follow-up. An association of MDC with progression-free and overall survivals (PFS and OS) was determined in the patients. A semiautomatic tumor segmentation framework could determine the pretreatment quantitative DMI measures with minimal time spent and high reproducibility. The mean tumor MDC was 0.82 +/- 0.14 x 10(-3) mm2/s. CR and IR were established in 28 and 18 women, respectively. The MDC < or = 0.83 x 10(-3) mm2/s predicted CR with a sensitivity of 64.3% and a specificity of 77.8% (p=0.007). The median follow-up was 47 months (range, 3-82 months). With the MDC < or = 0.86 x 10(-3) mm2/s, 5-year PFS was 74.1% versus 42.1% with a higher MDC (p=0.023) and 5-year OS was 70.4 and 40.6%, respectively (p=0.021). The survival difference was insignificant in relation to the degree of tumor regression. The pretreatment IS at b1000 was of no prognostic value. The pretreatment tumor MDC may serve as a biomarker for predicting the efficiency of CRT for CCU.

New insights into the aspects of pulmonary diffusing capacity in Fontan patients

DEFF Research Database (Denmark)

Idorn, Lars; Hanel, Birgitte; Jensen, Annette S

2014-01-01

by 48.3 ± 17.4% in the Fontan group and by 20.2 ± 13.9% in the control group (p = 0.001). In a multiple linear regression analysis including the explanatory variables of surgical data and exercise data at rest and peak exercise, the resting cardiac index was an independent predictor of the diffusing...

Phonon model of perovskite thermal capacity

International Nuclear Information System (INIS)

Kesler, Ya.A.; Poloznikova, M.Eh.; Petrov, K.I.

1983-01-01

A model for calculating the temperature curve of thermal capacity of perovskite family crystals on the basis of vibrational spectra is proposed. Different representatives of the perovskite family: cubic SrTiO 3 , tetragonal BaTiO 3 and orthorbombic CaTiO 3 and LaCrO 3 are considered. The total frequency set is used in thermal capacity calcUlations. Comparison of the thermal capacity values of compounds calculated on the basis of the proposed model with the experimental values shows their good agreement. The method is also recommended for other compounds with the perovskite-like structure

The value of information in explicit cross-border capacity auction regimes in electricity markets

International Nuclear Information System (INIS)

Richter, Jan; Viehmann, Johannes

2014-01-01

We study two electricity markets connected by a fixed amount of cross-border capacity. The total amount of capacity is known to all electricity traders and allocated via an auction. The capacity allocated to each bidder in the auction remains private information. We assume that traders are faced with a demand function reflecting the relationship between electricity transmitted between the markets and the spot price difference. Therefore, traders act like Bayesian–Cournot oligopolists in exercising their transmission rights when presented with incomplete information about the competitors’ capacities. Our analysis breaks down the welfare effect into three different components: Cournot behavior, capacity constraints, and incomplete information. We find that social welfare increases with the level of information with which traders are endowed. - Highlights: • We regard the utilization of explicitly auctioned cross-border capacities in electricity markets as a Bayesian Cournot game. • We analyze social welfare and find three forces diminishing it, (1) firms play a cournot game, (2) the presence of capacity constraints, (3) incomplete information. • We derive information regimes from “real world” examples and analyze their effect on social welfare

Diffusion-controlled reaction. V. Effect of concentration-dependent diffusion coefficient on reaction rate in graft polymerization

International Nuclear Information System (INIS)

Imre, K.; Odian, G.

1979-01-01

The effect of diffusion on radiation-initiated graft polymerization has been studied with emphasis on the single- and two-penetrant cases. When the physical properties of the penetrants are similar, the two-penetrant problems can be reduced to the single-penetrant problem by redefining the characteristic parameters of the system. The diffusion-free graft polymerization rate is assumed to be proportional to the upsilon power of the monomer concentration respectively, and, in which the proportionality constant a = k/sub p/R/sub i//sup w//k/sub t//sup z/, where k/sub p/ and k/sub t/ are the propagation and termination rate constants, respectively, and R/sub i/ is the initiation rate. The values of upsilon, w, and z depend on the particular reaction system. The results of earlier work were generalized by allowing a non-Fickian diffusion rate which predicts an essentially exponential dependence on the monomer concentration of the diffusion coefficient, D = D 0 [exp(deltaC/M)], where M is the saturation concentration. A reaction system is characterized by the three dimensionless parameters, upsilon, delta, and A = (L/2)[aM/sup (upsilon--1)//D 0 ]/sup 1/2/, where L is the polymer film thickness. Graft polymerization tends to become diffusion controlled as A increases. Larger values of delta and ν cause a reaction system to behave closer to the diffusion-free regime. Transition from diffusion-free to diffusion-controlled reaction involves changes in the dependence of the reaction rate on film thickness, initiation rate, and monomer concentration. Although the diffusion-free rate is w order in initiation rate, upsilon order in monomer, and independent of film thickness, the diffusion-controlled rate is w/2 order in initiator rate and inverse first-order in film thickness. Dependence of the diffusion-controlled rate on monomer is dependent in a complex manner on the diffusional characteristics of the reaction system. 11 figures, 4 tables

Porosity, sorption and diffusivity data compiled for the SKB 91 study

International Nuclear Information System (INIS)

Brandberg, F.; Skagius, K.

1991-04-01

The SKB 91 study is an integrated safety analysis of the KBS-3 concept of a repository located in the Finnsjoen area. For this study, values of important transport parameters in the bentonite backfill and in the rock are proposed. K d -values, diffusivities and diffusion porosity for different elements in compacted MX-80 bentonite are based on experimental data found in the literature. With regard to sorption, both a best estimate and a conservative value is given. Because sorption on bentonite is very much dependent on the conditions prevailing and experimental data are limited and not necessary representative for the conditions expected in the repository, the proposed best estimate values may include large uncertainties. Data proposed for rock are matrix diffusivities, matrix porosity and diffusivity in mobile bulk water. These values are based on experimental results on Finnsjoe rock. (au)

Singular value decomposition metrics show limitations of detector design in diffuse fluorescence tomography.

Science.gov (United States)

Leblond, Frederic; Tichauer, Kenneth M; Pogue, Brian W

2010-11-29

The spatial resolution and recovered contrast of images reconstructed from diffuse fluorescence tomography data are limited by the high scattering properties of light propagation in biological tissue. As a result, the image reconstruction process can be exceedingly vulnerable to inaccurate prior knowledge of tissue optical properties and stochastic noise. In light of these limitations, the optimal source-detector geometry for a fluorescence tomography system is non-trivial, requiring analytical methods to guide design. Analysis of the singular value decomposition of the matrix to be inverted for image reconstruction is one potential approach, providing key quantitative metrics, such as singular image mode spatial resolution and singular data mode frequency as a function of singular mode. In the present study, these metrics are used to analyze the effects of different sources of noise and model errors as related to image quality in the form of spatial resolution and contrast recovery. The image quality is demonstrated to be inherently noise-limited even when detection geometries were increased in complexity to allow maximal tissue sampling, suggesting that detection noise characteristics outweigh detection geometry for achieving optimal reconstructions.

Correlation of total, diffuse, and direct solar radiation

Science.gov (United States)

Buyco, E. H.; Namkoong, D.

1977-01-01

Present requirements for realistic solar energy system evaluations necessitate a comprehensive body of solar-radition data. The data should include both diffuse and direct solar radiation as well as their total on an hourly (or shorter) basis. In general, however, only the total solar radiation values were recorded. This report presents a correlation that relates the diffuse component of an hourly total solar radiation value to the total radiation ratio of the maximum value attainable. The data used were taken at the Blue Hill Observatory in Milton, Massachusetts, for the period 1952. The relation - in the form of the data plots - can be used in situations in which only the hourly total radiation data are available but the diffuse component is desired.

Specific Heat Capacity of Alloy 690 for Simulating Neutron Irradiation

International Nuclear Information System (INIS)

Park, Dae Gyu; Kim, Hee Moon; Song, Woong Sub; Baik, Seung Je; Joo, Young Sun; Ahn, Sang Bok; Park, Jin Seok; Lee, Won Jae; Ryu, Woo Seok

2011-01-01

The KAERI(Korea Atomic Energy Research Institute) is developing new type of nuclear reactor, so called 'SMART'(System Integrated Modular Advanced Reactor) which has many features of small power and system integrated modular type. Alloy 690 was selected as the candidate material for the heat exchanger tube of the steam generator of SMART. The SMART R and D is now facing the stage of engineering verification and approval of standard design to apply to DEMO reactors. Therefore, the material performance under the relevant environment is required to be evaluated. The important material performance issues are mechanical properties i.e. (fracture toughness, tensile and hardness) and thermal properties i.e. (thermal diffusivity, specific heat capacity and thermal conductivity) for which the engineering database is necessary to design a steam generator. However, the neutron post irradiation characteristics of the alloy 690 are barely known. As a result, PIE(Post Irradiation Examination) of thermal properties are planed and performed successfully. But specific heat capacity measurement is not performed because of not having proper test system for irradiated materials. Therefore in order to verify the effect of neutron irradiation for alloy 690, simulation method is adopted. In general, high energy neutron bombardment in material bring about lattice defects i.e. void, pore and dislocation. Dominant factor to impact to heat capacity is mainly dislocation in material. Therefore, simulation of neutron irradiation is devised by material rolling method in order to make artificial dislocation in alloy 690 as same effect of neutron irradiation. After preparing test specimens, heat capacity measurements are performed and results are compared with rolled materials and un-rolled materials to verify the effect of neutron irradiation simulation. Main interest of simulation is that heat capacity value is changed by neutron irradiation

Surface and bulk modified high capacity layered oxide cathodes with low irreversible capacity loss

Science.gov (United States)

Manthiram, Arumugam (Inventor); Wu, Yan (Inventor)

2010-01-01

The present invention includes compositions, surface and bulk modifications, and methods of making of (1-x)Li[Li.sub.1/3Mn.sub.2/3]O.sub.2.xLi[Mn.sub.0.5-yNi.sub.0.5-yCo.sub.2- y]O.sub.2 cathode materials having an O3 crystal structure with a x value between 0 and 1 and y value between 0 and 0.5, reducing the irreversible capacity loss in the first cycle by surface modification with oxides and bulk modification with cationic and anionic substitutions, and increasing the reversible capacity to close to the theoretical value of insertion/extraction of one lithium per transition metal ion (250-300 mAh/g).

Manipulating the antioxidant capacity of halophytes to increase their cultural and economic value through saline cultivation.

Science.gov (United States)

Boestfleisch, Christian; Wagenseil, Niko B; Buhmann, Anne K; Seal, Charlotte E; Wade, Ellie Merrett; Muscolo, Adele; Papenbrock, Jutta

2014-08-13

Halophytes, salt-tolerant plants, are a source of valuable secondary metabolites with potential economic value. The steady-state pools of many stress-related metabolites are already enhanced in halophytes when compared with glycophytes, but growth under conditions away from the optimum can induce stress and consequently result in changes to secondary metabolites such as antioxidants. However, direct evidence for increasing the concentration of valuable secondary metabolites as a consequence of altering the salinity of the growing environment still remains equivocal. To address this, we analysed a range of metabolites with antioxidant capacity (including total phenols, flavonoids, ascorbate, reduced/oxidized glutathione and reactive oxygen species scavenging enzymes) in seedlings and plants from different families (Amaranthaceae, Brassicaceae, Plantaginaceae and Rhizophoraceae) and habitats grown under different salt concentrations. We show that it is possible to manipulate the antioxidant capacity of plants and seedlings by altering the saline growing environment, the length of time under saline cultivation and the developmental stage. Among the species studied, the halophytes Tripolium pannonicum, Plantago coronopus, Lepidium latifolium and Salicornia europaea demonstrated the most potential as functional foods or nutraceuticals. Published by Oxford University Press on behalf of the Annals of Botany Company.

Relationship between pretreatment FDG-PET and diffusion-weighted MRI biomarkers in diffuse large B-cell lymphoma

Science.gov (United States)

de Jong, Antoinette; Kwee, Thomas C; de Klerk, John MH; Adam, Judit A; de Keizer, Bart; Fijnheer, Rob; Kersten, Marie José; Ludwig, Inge; Jauw, Yvonne WS; Zijlstra, Josée M; den Bos, Indra C Pieters - Van; Stoker, Jaap; Hoekstra, Otto S; Nievelstein, Rutger AJ

2014-01-01

The purpose of this study was to determine the correlation between the 18F-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) standardized uptake value (SUV) and the diffusion-weighted magnetic resonance imaging (MRI) apparent diffusion coefficient (ADC) in newly diagnosed diffuse large B-cell lymphoma (DLBCL). Pretreatment FDG-PET and diffusion-weighted MRI of 21 patients with histologically proven DLBCL were prospectively analyzed. In each patient, maximum, mean and peak standardized uptake value (SUV) was measured in the lesion with visually highest FDG uptake and in the largest lesion. Mean ADC (ADCmean, calculated with b-values of 0 and 1000 s/mm2) was measured in the same lesions. Correlations between FDG-PET metrics (SUVmax, SUVmean, SUVpeak) and ADCmean were assessed using Pearson’s correlation coefficients. In the lesions with visually highest FDG uptake, no significant correlations were found between the SUVmax, SUVmean, SUVpeak and the ADCmean (P=0.498, P=0.609 and P=0.595, respectively). In the largest lesions, there were no significant correlations either between the SUVmax, SUVmean, SUVpeak and the ADCmean (P=0.992, P=0.843 and P=0.894, respectively). The results of this study indicate that the glycolytic rate as measured by FDG-PET and changes in water compartmentalization and water diffusion as measured by the ADC are independent biological phenomena in newly diagnosed DLBCL. Further studies are warranted to assess the complementary roles of these different imaging biomarkers in the evaluation and follow-up of DLBCL. PMID:24795837

Variability of non-Gaussian diffusion MRI and intravoxel incoherent motion (IVIM) measurements in the breast.

Science.gov (United States)

Iima, Mami; Kataoka, Masako; Kanao, Shotaro; Kawai, Makiko; Onishi, Natsuko; Koyasu, Sho; Murata, Katsutoshi; Ohashi, Akane; Sakaguchi, Rena; Togashi, Kaori

2018-01-01

We prospectively examined the variability of non-Gaussian diffusion magnetic resonance imaging (MRI) and intravoxel incoherent motion (IVIM) measurements with different numbers of b-values and excitations in normal breast tissue and breast lesions. Thirteen volunteers and fourteen patients with breast lesions (seven malignant, eight benign; one patient had bilateral lesions) were recruited in this prospective study (approved by the Internal Review Board). Diffusion-weighted MRI was performed with 16 b-values (0-2500 s/mm2 with one number of excitations [NEX]) and five b-values (0-2500 s/mm2, 3 NEX), using a 3T breast MRI. Intravoxel incoherent motion (flowing blood volume fraction [fIVIM] and pseudodiffusion coefficient [D*]) and non-Gaussian diffusion (theoretical apparent diffusion coefficient [ADC] at b value of 0 sec/mm2 [ADC0] and kurtosis [K]) parameters were estimated from IVIM and Kurtosis models using 16 b-values, and synthetic apparent diffusion coefficient (sADC) values were obtained from two key b-values. The variabilities between and within subjects and between different diffusion acquisition methods were estimated. There were no statistical differences in ADC0, K, or sADC values between the different b-values or NEX. A good agreement of diffusion parameters was observed between 16 b-values (one NEX), five b-values (one NEX), and five b-values (three NEX) in normal breast tissue or breast lesions. Insufficient agreement was observed for IVIM parameters. There were no statistical differences in the non-Gaussian diffusion MRI estimated values obtained from a different number of b-values or excitations in normal breast tissue or breast lesions. These data suggest that a limited MRI protocol using a few b-values might be relevant in a clinical setting for the estimation of non-Gaussian diffusion MRI parameters in normal breast tissue and breast lesions.

Estimation of optimal b-value sets for obtaining apparent diffusion coefficient free from perfusion in non-small cell lung cancer.

Science.gov (United States)

Karki, Kishor; Hugo, Geoffrey D; Ford, John C; Olsen, Kathryn M; Saraiya, Siddharth; Groves, Robert; Weiss, Elisabeth

2015-10-21

The purpose of this study was to determine optimal sets of b-values in diffusion-weighted MRI (DW-MRI) for obtaining monoexponential apparent diffusion coefficient (ADC) close to perfusion-insensitive intravoxel incoherent motion (IVIM) model ADC (ADCIVIM) in non-small cell lung cancer. Ten subjects had 40 DW-MRI scans before and during radiotherapy in a 1.5 T MRI scanner. Respiratory triggering was applied to the echo-planar DW-MRI with TR ≈ 4500 ms, TE  =  74 ms, eight b-values of 0-1000 μs μm(-2), pixel size  =  1.98 × 1.98 mm(2), slice thickness  =  6 mm, interslice gap  =  1.2 mm, 7 axial slices and total acquisition time ≈6 min. One or more DW-MRI scans together covered the whole tumour volume. Monoexponential model ADC values using various b-value sets were compared to reference-standard ADCIVIM values using all eight b-values. Intra-scan coefficient of variation (CV) of active tumour volumes was computed to compare the relative noise in ADC maps. ADC values for one pre-treatment DW-MRI scan of each of the 10 subjects were computed using b-value pairs from DW-MRI images synthesized for b-values of 0-2000 μs μm(-2) from the estimated IVIM parametric maps and corrupted by various Rician noise levels. The square root of mean of squared error percentage (RMSE) of the ADC value relative to the corresponding ADCIVIM for the tumour volume of the scan was computed. Monoexponential ADC values for the b-value sets of 250 and 1000; 250, 500 and 1000; 250, 650 and 1000; 250, 800 and 1000; and 250-1000 μs μm(-2) were not significantly different from ADCIVIM values (p > 0.05, paired t-test). Mean error in ADC values for these sets relative to ADCIVIM were within 3.5%. Intra-scan CVs for these sets were comparable to that for ADCIVIM. The monoexponential ADC values for other sets-0-1000; 50-1000; 100-1000; 500-1000; and 250 and 800 μs μm(-2) were significantly different from the ADCIVIM values. From Rician noise

A theoretical model to determine the capacity performance of shape-specific electrodes

Science.gov (United States)

Yue, Yuan; Liang, Hong

2018-06-01

A theory is proposed to explain and predict the electrochemical process during reaction between lithium ions and electrode materials. In the model, the process of reaction is proceeded into two steps, surface adsorption and diffusion of lithium ions. The surface adsorption is an instantaneous process for lithium ions to adsorb onto the surface sites of active materials. The diffusion of lithium ions into particles is determined by the charge-discharge condition. A formula to determine the maximum specific capacity of active materials at different charging rates (C-rates) is derived. The maximum specific capacity is correlated to characteristic parameters of materials and cycling - such as size, aspect ratio, surface area, and C-rate. Analysis indicates that larger particle size or greater aspect ratio of active materials and faster C-rates can reduce maximum specific capacity. This suggests that reducing particle size of active materials and slowing the charge-discharge speed can provide enhanced electrochemical performance of a battery cell. Furthermore, the model is validated by published experimental results. This model brings new understanding in quantification of electrochemical kinetics and capacity performance. It enables development of design strategies for novel electrodes and future generation of energy storage devices.

Nitrogen diffusion in near-surface range of ion doped molybdenum

CERN Document Server

Zamalin, E Y

2001-01-01

The dynamics of change in nitrogen near-the-surface concentration in the Mo ion-alloyed monocrystalline foil is studied through the Auger-electron spectroscopy and the secondary ion mass spectrometry. The implantation dose constituted 5 x 10 sup 1 sup 7 ion/cm sup 2 and the implantation energy equaled 50 and 100 keV. The samples diffusion annealing was performed at the temperature of 800-900 deg C. The evaluation of the nitrogen diffusion coefficient indicates the values by 3-5 orders lesser than the diffusion coefficient in the nitrogen solid-state solution in the molybdenum. At the same time the molybdenum self-diffusion coefficient value is by 3-5 orders lesser as compared to the obtained value. The supposition is made, the the surplus nitrogen relative to the solubility limit is deposited on the radiation defects and in the process of the diffusion annealing it nitrates together with them

Capacity Expansion Modeling for Storage Technologies

Energy Technology Data Exchange (ETDEWEB)

Hale, Elaine; Stoll, Brady; Mai, Trieu

2017-04-03

The Resource Planning Model (RPM) is a capacity expansion model designed for regional power systems and high levels of renewable generation. Recent extensions capture value-stacking for storage technologies, including batteries and concentrating solar power with storage. After estimating per-unit capacity value and curtailment reduction potential, RPM co-optimizes investment decisions and reduced-form dispatch, accounting for planning reserves; energy value, including arbitrage and curtailment reduction; and three types of operating reserves. Multiple technology cost scenarios are analyzed to determine level of deployment in the Western Interconnection under various conditions.

Improvement in performance of a direct solar-thermally driven diffusion-absorption refrigerator; Leistungssteigerung einer direkt solarthermisch angetriebenen Diffusions-Absorptionskaeltemaschine

Energy Technology Data Exchange (ETDEWEB)

Schmid, Fabian; Bierling, Bernd; Spindler, Klaus [Stuttgart Univ. (Germany). Inst. fuer Thermodynamik und Waermetechnik (ITW)

2012-07-01

The diffusion-absorption refrigeration process offers the possibility of a wear-free refrigeration system without electricity and noise. At the Institute for Thermodynamics and Thermal Engineering (Stuttgart, Federal Republic of Germany), a decentralized solar refrigeration system is developed based on this process. The expeller and the thermosiphon pump of this process are integrated in the collector, and thus are heated directly. The diffusion-absorption refrigeration process also can be used for domestic water heating by means of a second cycle in the collector. A cooling capacity of 400 W is to be achieved for each solar collector (2.5 m{sup 2}). Several refrigeration systems can be modular interconnected for higher cooling capacities. As part of the DKV Conference 2011, the construction of the plant, the first measurement data and results were presented. Since then, both the cooling capacity and the coefficient of performance of the diffusion-absorption refrigeration system could be increased significantly. For this, solvent heat exchanger, evaporator, absorber and gas heat exchanger have been optimized in terms of system efficiency. In addition, a stable system operation could be achieved by means of a bypass line. About this line, an exaggerated refrigerant already is removed in the solvent heat exchanger. In addition, a condensate pre-cooler was integrated in order to increase the efficiency. For a detailed investigation of the auxiliary gas cycle facilities, the volume flow and the concentration of the auxiliary gas circuit were examined under utilization of an ultrasonic sensor. In order to evaluate the influence factors by means of a parametric study, the mass transfer in the auxiliary gas circuit was simulated using the two-fluid model. The results of these studies, the current system configuration and the current results are presented in the contribution under consideration.

Interference and memory capacity effects in memristive systems

Science.gov (United States)

Hermiz, John; Chang, Ting; Du, Chao; Lu, Wei

2013-02-01

Short-term memory implies the existence of a capacity limit beyond which memory cannot be securely formed and retained. The underlying mechanisms are believed to be two primary factors: decay and interference. Here, we demonstrate through both simulation and experiment that the memory capacity effect can be implemented in a parallel memristor circuit, where decay and interference are achieved by the inherent ion diffusion in the device and the competition for current supply in the circuit, respectively. This study suggests it is possible to emulate high-level biological behaviors with memristor circuits and will stimulate continued studies on memristor-based neuromorphic circuits.

Endometrial Stromal Sarcoma of the Uterus: Magnetic Resonance Imaging Findings Including Apparent Diffusion Coefficient Value and Its Correlation With Ki-67 Expression.

Science.gov (United States)

Li, Hai Ming; Liu, Jia; Qiang, Jin Wei; Gu, Wei Yong; Zhang, Guo Fu; Ma, Feng Hua

2017-11-01

This study aimed to investigate the conventional magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) features of endometrial stromal sarcoma (ESS) including a preliminary investigation of the correlation between the apparent diffusion coefficient (ADC) value and Ki-67 expression. The clinical and MRI data of 15 patients with ESS confirmed by surgery and pathology were analyzed retrospectively. The conventional MR morphological features, signal intensity on DWI, ADC value (n = 14), and clinicopathological marker Ki-67 (n = 13) were evaluated. Of 15 patients with ESS, 13 tumors were low-grade ESS (LGESS), and the remaining 2 were high-grade ESS (HGESS); 9 tumors were located in the myometrium, 5 were located in the endometrium and/or cervical canal, and 1 was located in extrauterine. Thirteen (87%) of 15 tumors showed a homo- or heterogeneous isointensity on T1-weighted imaging and a heterogeneous hyperintensity on T2-weighted imaging. The hypointense bands were observed in 11 tumors (73%) on T2-weighted imaging. The degenerations (cystic/necrosis/hemorrhage) were observed in 7 LGESS tumors and 2 HGESS tumors. The DWI hyperintensity was observed in 13 tumors (93%) and isointensity in remaining 1. The mean ADC value of the solid components in 14 ESSs was (1.05 ± 0.20) × 10mm/s. The contrast-enhanced MRI showed an obvious enhancement in 14 tumors (93%) (heterogeneous in 7 LGESSs and 2 HGESSs; homogeneous in 5 LGESSs). The ADC value was inversely correlated with the Ki-67 expression (r = -0.613, P = 0.026). Patients with ESS showed some characteristics on conventional MRI and DWI, and there was an inverse correlation between the ADC value and Ki-67 expression.

Review of sorption and diffusion data for SR 97

Energy Technology Data Exchange (ETDEWEB)

Stenhouse, M. [Monitor Scientific, LLC, Denver, CO (United States)

2000-12-01

studied. There is always likely to be a lack of experimental data to support what is effectively expert judgement. Therefore, the best management approach is to focus on those elements for which no data exist (to confirm or update current recommendations, as appropriate), or for radionuclides which appear as key contributors to dose. In the latter case, variation in K{sub d} values can be explored by sensitivity analysis and, where a factor of 10 reduction is significant in terms of a radionuclide's contribution to total dose, experimental work should be carried out. Thus, Andersson's recommendation for probabilistic cases should ensure that any K{sub d} -limiting cases are identified. Radionuclide transport through the bentonite buffer is taken into account via diffusion, with sorption where merited. The input parameters required, therefore, are effective diffusion coefficient, D{sub e}, distribution coefficient, K{sub d} , and porosity, {epsilon}. Andersson notes that the code used by SKB to model migration through the near field can use only one value of porosity, which leads to logistical problems regarding data input. In particular, K{sub d} values must be 'manipulated' to yield a D{sub e} (effective diffusion coefficient) value representative of the transport porosity and the true sorption capacity for that radionuclide. In this regard, comparison of K{sub d} values with other programmes must be treated with caution. For input to the work of Yu and Neretnieks, who provided recommendations on relevant K{sub d} values for sorption on compacted bentonite, the lack of a reference porewater seems a major omission. The omission may well have been influenced by the lack of a consensus in how to establish a reference porewater composition. It is now well established that K{sub d} values obtained from batch sorption experiments must be treated with caution when applying such values to sorption on compacted bentonite. In particular, measurements using

Thermal Diffusivity in Bone and Hydroxyapatite

Science.gov (United States)

Calderón, A.; Peña Rodríguez, G.; Muñoz Hernández, R. A.; Díaz Gongora, J. A. I.; Mejia Barradas, C. M.

2004-09-01

We report thermal diffusivity measurements in bull bone and commercial hydroxyapatite (HA), both in powder form, in order to determinate the thermal compatibility between these materials. Besides this, we report a comparison between these measured values and those of metallic samples frequently used in implants, as high purity titanium and stainless steel. Our results show a good thermal compatibility (74%) between HA and bone, both in powder form. Finally, it was obtained a one order of magnitude difference between the thermal diffusivity values of metallic samples and those corresponding values to bone and HA being this difference greater in titanium than in stainless steel, which is important to consider in some biomedical and dental applications.

Cesium diffusion in graphite

International Nuclear Information System (INIS)

Evans, R.B. III; Davis, W. Jr.; Sutton, A.L. Jr.

1980-05-01

Experiments on diffusion of 137 Cs in five types of graphite were performed. The document provides a completion of the report that was started and includes a presentation of all of the diffusion data, previously unpublished. Except for data on mass transfer of 137 Cs in the Hawker-Siddeley graphite, analyses of experimental results were initiated but not completed. The mass transfer process of cesium in HS-1-1 graphite at 600 to 1000 0 C in a helium atmosphere is essentially pure diffusion wherein values of (E/epsilon) and ΔE of the equation D/epsilon = (D/epsilon) 0 exp [-ΔE/RT] are about 4 x 10 -2 cm 2 /s and 30 kcal/mole, respectively

High-throughput ab-initio dilute solute diffusion database.

Science.gov (United States)

Wu, Henry; Mayeshiba, Tam; Morgan, Dane

2016-07-19

We demonstrate automated generation of diffusion databases from high-throughput density functional theory (DFT) calculations. A total of more than 230 dilute solute diffusion systems in Mg, Al, Cu, Ni, Pd, and Pt host lattices have been determined using multi-frequency diffusion models. We apply a correction method for solute diffusion in alloys using experimental and simulated values of host self-diffusivity. We find good agreement with experimental solute diffusion data, obtaining a weighted activation barrier RMS error of 0.176 eV when excluding magnetic solutes in non-magnetic alloys. The compiled database is the largest collection of consistently calculated ab-initio solute diffusion data in the world.

"Value"ing Children Differently? Migrant Children in Education

Science.gov (United States)

Devine, Dympna

2013-01-01

This paper considers dilemmas around "value" and the "valuing" of children and childhood(s) in schools. I argue that in neo-liberal contexts, processes of children's identity making become aligned with the idea of the corporate citizen--value and worth derived from the capacity to produce, excel, self-regulate as well as…

Carbon Sequestration in Saline Aquifers: Modeling Diffusive and Convective Transport Of a Carbon-­Dioxide Cap

KAUST Repository

Allen, Rebecca

2011-05-01

An increase in the earth’s surface temperature has been directly linked to the rise of carbon dioxide (CO2) levels In the atmosphere and an enhanced greenhouse effect. CO2 sequestration is one of the proposed mitigation Strategies in the effort to reduce atmospheric CO2 concentrations. Globally speaking, saline aquifers provide an adequate storage capacity for the world’s carbon emissions, and CO2 sequestration projects are currently underway in countries such as Norway, Germany, Japan, USA, and others. Numerical simulators serve as predictive tools for CO2 storage, yet must model fluid transport behavior while coupling different transport processes together accurately. With regards to CO2 sequestration, an extensive amount of research has been done on the diffusive-convective transport that occurs under a cap of CO2-saturated fluid, which results after CO2 is injected into an aquifer and spreads laterally under an area of low permeability. The diffusive-convective modeling reveals an enhanced storage capacity in saline aquifers, due to the density increase between pure fluid and CO2‐saturated fluid. This work presents the transport modeling equations that are used for diffusive- convective modeling. A cell-centered finite difference method is used, and simulations are run using MATLAB. Two cases are explored in order to compare the results from this work’s self-generated code with the results published in literature. Simulation results match relatively well, and the discrepancy for a delayed onset time of convective transport observed in this work is attributed to numerical artifacts. In fact, onset time in this work is directly attributed to the instability of the physical system: this instability arises from non-linear coupling of fluid flow, transport, and convection, but is triggered by numerical errors in these simulations. Results from this work enable the computation of a value for the numerical constant that appears in the onset time equation that

Continuous diffusion signal, EAP and ODF estimation via Compressive Sensing in diffusion MRI.

Science.gov (United States)

Merlet, Sylvain L; Deriche, Rachid

2013-07-01

In this paper, we exploit the ability of Compressed Sensing (CS) to recover the whole 3D Diffusion MRI (dMRI) signal from a limited number of samples while efficiently recovering important diffusion features such as the Ensemble Average Propagator (EAP) and the Orientation Distribution Function (ODF). Some attempts to use CS in estimating diffusion signals have been done recently. However, this was mainly an experimental insight of CS capabilities in dMRI and the CS theory has not been fully exploited. In this work, we also propose to study the impact of the sparsity, the incoherence and the RIP property on the reconstruction of diffusion signals. We show that an efficient use of the CS theory enables to drastically reduce the number of measurements commonly used in dMRI acquisitions. Only 20-30 measurements, optimally spread on several b-value shells, are shown to be necessary, which is less than previous attempts to recover the diffusion signal using CS. This opens an attractive perspective to measure the diffusion signals in white matter within a reduced acquisition time and shows that CS holds great promise and opens new and exciting perspectives in diffusion MRI (dMRI). Copyright © 2013 Elsevier B.V. All rights reserved.

Value of diffusion-weighted images in differentiating mid-course responders to chemotherapy for osteosarcoma compared to the histological response: preliminary results

International Nuclear Information System (INIS)

Baunin, C.; Schmidt, G.; Aschero, A.; Ruocco, A.; Bourliere, B.; Gorincour, G.; Desvignes, C.; Colavolpe, N.; Petit, P.; Baumstarck, K.; Auqier, P.; Bouvier, C.; Gentet, J.C.; Bollini, G.

2012-01-01

Preoperative diffusion-weighted MRI (DW-MRI) has been described as an efficient method to differentiate good and poor responders to chemotherapy in osteosarcoma patients. A DW-MRI performed earlier during treatment could be helpful in monitoring chemotherapy. To assess the accuracy of DW-MRI in evaluating response to chemotherapy in the treatment of osteosarcoma, more specifically at mid-course of treatment. This study was carried out on a prospective series of adolescents treated for long-bone osteosarcoma. MR examinations were performed at diagnosis (MRI-1), at mid-course of chemotherapy (MRI-2), and immediately before surgery (MRI-3). A DW sequence was performed using diffusion gradients of b0 and b900. The apparent diffusion coefficients (ADC1, ADC2, ADC3, respectively), their differentials (ADC2 - ADC1 and ADC3 - ADC1), and their variation (ADC2 - ADC1/ADC1 and ADC3 - ADC1/ADC1) were calculated for each of these three time points. Fifteen patients were included. Patients with no increase in ADC showed a poor response to chemotherapy on their histology results. At mid-course, the three calculated values were significantly different between good and poor responders. ADC2 - ADC1 enabled us to detect, with 100% specificity, four out of seven of the poor responders. There was no significant difference in the values at MRI-3 between the two groups. DW-MRI performed both at baseline and mid-course of neoadjuvant chemotherapy is an efficient method to predict further histological response of osteosarcoma. This method could be used as an early prognostic factor to monitor preoperative chemotherapy. (orig.)

Value of diffusion-weighted images in differentiating mid-course responders to chemotherapy for osteosarcoma compared to the histological response: preliminary results

Energy Technology Data Exchange (ETDEWEB)

Baunin, C.; Schmidt, G.; Aschero, A.; Ruocco, A.; Bourliere, B.; Gorincour, G.; Desvignes, C.; Colavolpe, N.; Petit, P. [Hopital Timone Enfants, Service d' Imagerie Pediatrique et Prenatale, Marseille Cedex 05 (France); Baumstarck, K.; Auqier, P. [Faculte de Medecine de Marseille, Service de Sante Publique, Marseille Cedex 05 (France); Bouvier, C. [Hopital Timone, Service d' Anatomopathologie, Marseille Cedex 05 (France); Gentet, J.C. [Hopital Timone Enfants, Service d' Oncologie Pediatrique, Marseille Cedex 05 (France); Bollini, G. [Hopital Timone Enfants, Service d' Orthopedie Pediatrique, Marseille Cedex 05 (France)

2012-09-15

Preoperative diffusion-weighted MRI (DW-MRI) has been described as an efficient method to differentiate good and poor responders to chemotherapy in osteosarcoma patients. A DW-MRI performed earlier during treatment could be helpful in monitoring chemotherapy. To assess the accuracy of DW-MRI in evaluating response to chemotherapy in the treatment of osteosarcoma, more specifically at mid-course of treatment. This study was carried out on a prospective series of adolescents treated for long-bone osteosarcoma. MR examinations were performed at diagnosis (MRI-1), at mid-course of chemotherapy (MRI-2), and immediately before surgery (MRI-3). A DW sequence was performed using diffusion gradients of b0 and b900. The apparent diffusion coefficients (ADC1, ADC2, ADC3, respectively), their differentials (ADC2 - ADC1 and ADC3 - ADC1), and their variation (ADC2 - ADC1/ADC1 and ADC3 - ADC1/ADC1) were calculated for each of these three time points. Fifteen patients were included. Patients with no increase in ADC showed a poor response to chemotherapy on their histology results. At mid-course, the three calculated values were significantly different between good and poor responders. ADC2 - ADC1 enabled us to detect, with 100% specificity, four out of seven of the poor responders. There was no significant difference in the values at MRI-3 between the two groups. DW-MRI performed both at baseline and mid-course of neoadjuvant chemotherapy is an efficient method to predict further histological response of osteosarcoma. This method could be used as an early prognostic factor to monitor preoperative chemotherapy. (orig.)

Diffusion-weighted Imaging Is a Sensitive and Specific Magnetic Resonance Sequence in the Diagnosis of Ankylosing Spondylitis.

Science.gov (United States)

Bradbury, Linda A; Hollis, Kelly A; Gautier, Benoît; Shankaranarayana, Sateesh; Robinson, Philip C; Saad, Nivene; Lê Cao, Kim-Anh; Brown, Matthew A

2018-06-01

We tested the discriminatory capacity of diffusion-weighted magnetic resonance imaging (DWI) and its potential as an objective measure of treatment response to tumor necrosis factor inhibition in ankylosing spondylitis (AS). Three cohorts were studied prospectively: (1) 18 AS patients with Bath Ankylosing Spondylitis Disease Activity Index > 4, and erythrocyte sedimentation rate > 25 and/or C-reactive protein > 10 meeting the modified New York criteria for AS; (2) 20 cases of nonradiographic axial spondyloarthritis (nr-axSpA) as defined by the Assessment of Spondyloarthritis international Society (ASAS) criteria; and (3) 20 non-AS patients with chronic low back pain, aged between 18 and 45 years, who did not meet the imaging arm of the ASAS criteria for axSpA. Group 1 patients were studied prior to and following adalimumab treatment. Patients were assessed by DWI and conventional magnetic resonance imaging (MRI), and standard nonimaging measures. At baseline, in contrast to standard nonimaging measures, DWI apparent diffusion coefficient (ADC) values showed good discriminatory performance [area under the curve (AUC) > 80% for Group 1 or 2 compared with Group 3]. DWI ADC values were significantly lower posttreatment (0.45 ± 0.433 before, 0.154 ± 0.23 after, p = 0.0017), but had modest discriminating capacity comparing pre- and posttreatment measures (AUC = 68%). This performance was similar to the manual Spondyloarthritis Research Consortium of Canada (SPARCC) scoring system. DWI is informative for diagnosis of AS and nr-axSpA, and has moderate utility in assessment of disease activity or treatment response, with performance similar to that of the SPARCC MRI score.

Intravoxel water diffusion heterogeneity MR imaging of nasopharyngeal carcinoma using stretched exponential diffusion model

Energy Technology Data Exchange (ETDEWEB)

Lai, Vincent; Khong, Pek Lan [University of Hong Kong, Department of Diagnostic Radiology, Li Ka Shing Faculty of Medicine, Queen Mary Hospital, Pok Fu Lam (China); Lee, Victor Ho Fun; Lam, Ka On; Sze, Henry Chun Kin [University of Hong Kong, Department of Clinical Oncology, Li Ka Shing Faculty of Medicine, Queen Mary Hospital, Pok Fu Lam (China); Chan, Queenie [Philips Healthcare, Hong Kong, Shatin, New Territories (China)

2015-06-01

To determine the utility of stretched exponential diffusion model in characterisation of the water diffusion heterogeneity in different tumour stages of nasopharyngeal carcinoma (NPC). Fifty patients with newly diagnosed NPC were prospectively recruited. Diffusion-weighted MR imaging was performed using five b values (0-2,500 s/mm{sup 2}). Respective stretched exponential parameters (DDC, distributed diffusion coefficient; and alpha (α), water heterogeneity) were calculated. Patients were stratified into low and high tumour stage groups based on the American Joint Committee on Cancer (AJCC) staging for determination of the predictive powers of DDC and α using t test and ROC curve analyses. The mean ± standard deviation values were DDC = 0.692 ± 0.199 (x 10{sup -3} mm{sup 2}/s) for low stage group vs 0.794 ± 0.253 (x 10{sup -3} mm{sup 2}/s) for high stage group; α = 0.792 ± 0.145 for low stage group vs 0.698 ± 0.155 for high stage group. α was significantly lower in the high stage group while DDC was negatively correlated. DDC and α were both reliable independent predictors (p < 0.001), with α being more powerful. Optimal cut-off values were (sensitivity, specificity, positive likelihood ratio, negative likelihood ratio) DDC = 0.692 x 10{sup -3} mm{sup 2}/s (94.4 %, 64.3 %, 2.64, 0.09), α = 0.720 (72.2 %, 100 %, -, 0.28). The heterogeneity index α is robust and can potentially help in staging and grading prediction in NPC. (orig.)

Irradiation effects of the zirconium oxidation and the uranium diffusion in zirconia; Effets d'irradiation sur l'oxydation du zirconium et la diffusion de l'uranium dans la zircone

Energy Technology Data Exchange (ETDEWEB)

Bererd, N

2003-07-01

The context of this study is the direct storage of spent fuel assemblies after operation in reactor. In order to obtain data on the capacities of the can as the uranium diffusion barrier, a fundamental study has been carried out for modelling the internal cladding surface under and without irradiation. The behaviour of zirconium in reactor conditions has at first been studied. A thin uranium target enriched with fissile isotope has been put on a zirconium sample, the set being irradiated by a thermal neutrons flux leading to the fission of the deposited uranium. The energetic history of the formed fission products has revealed two steps: 1)the zirconium oxidation and 2)the diffusion of uranium in the zirconia formed at 480 degrees C. A diffusion coefficient under irradiation has been measured. Its value is 10{sup -15} cm{sup 2}.s{sup -1}. In order to be able to reveal clearly the effect of the irradiation by the fission products on the zirconium oxidation, measurements of thermal oxidation and under {sup 129}Xe irradiation have been carried out. They have shown that the oxidation is strongly accelerated by the irradiation and that the temperature is negligible until 480 degrees C. On the other hand, the thermal diffusion of the uranium in zirconium and in zirconia has been studied by coupling ion implantation and Rutherford backscattering spectroscopy. This study shows that the uranium diffuses in zirconium and is trapped in zirconia in a UO{sub 3} shape. (O.M.)

REDUCTION CAPACITY OF SALTSTONE AND SALTSTONE COMPONENTS

Energy Technology Data Exchange (ETDEWEB)

Roberts, K.; Kaplan, D.

2009-11-30

The duration that saltstone retains its ability to immobilize some key radionuclides, such as technetium (Tc), plutonium (Pu), and neptunium (Np), depends on its capacity to maintain a low redox status (or low oxidation state). The reduction capacity is a measure of the mass of reductants present in the saltstone; the reductants are the active ingredients that immobilize Tc, Pu, and Np. Once reductants are exhausted, the saltstone loses its ability to immobilize these radionuclides. The reduction capacity values reported here are based on the Ce(IV)/Fe(II) system. The Portland cement (198 {micro}eq/g) and especially the fly ash (299 {micro}eq/g) had a measurable amount of reduction capacity, but the blast furnace slag (820 {micro}eq/g) not surprisingly accounted for most of the reduction capacity. The blast furnace slag contains ferrous iron and sulfides which are strong reducing and precipitating species for a large number of solids. Three saltstone samples containing 45% slag or one sample containing 90% slag had essentially the same reduction capacity as pure slag. There appears to be some critical concentration between 10% and 45% slag in the Saltstone formulation that is needed to create the maximum reduction capacity. Values from this work supported those previously reported, namely that the reduction capacity of SRS saltstone is about 820 {micro}eq/g; this value is recommended for estimating the longevity that the Saltstone Disposal Facility will retain its ability to immobilize radionuclides.

The Trouble with Diffusion

Directory of Open Access Journals (Sweden)

R.T. DeHoff

2002-09-01

Full Text Available The phenomenological formalism, which yields Fick's Laws for diffusion in single phase multicomponent systems, is widely accepted as the basis for the mathematical description of diffusion. This paper focuses on problems associated with this formalism. This mode of description of the process is cumbersome, defining as it does matrices of interdiffusion coefficients (the central material properties that require a large experimental investment for their evaluation in three component systems, and, indeed cannot be evaluated for systems with more than three components. It is also argued that the physical meaning of the numerical values of these properties with respect to the atom motions in the system remains unknown. The attempt to understand the physical content of the diffusion coefficients in the phenomenological formalism has been the central fundamental problem in the theory of diffusion in crystalline alloys. The observation by Kirkendall that the crystal lattice moves during diffusion led Darken to develop the concept of intrinsic diffusion, i.e., atom motion relative to the crystal lattice. Darken and his successors sought to relate the diffusion coefficients computed for intrinsic fluxes to those obtained from the motion of radioactive tracers in chemically homogeneous samples which directly report the jump frequencies of the atoms as a function of composition and temperature. This theoretical connection between tracer, intrinsic and interdiffusion behavior would provide the basis for understanding the physical content of interdiffusion coefficients. Definitive tests of the resulting theoretical connection have been carried out for a number of binary systems for which all three kinds of observations are available. In a number of systems predictions of intrinsic coefficients from tracer data do not agree with measured values although predictions of interdiffusion coefficients appear to give reasonable agreement. Thus, the complete

Peritumoral edema of meningiomas and metastatic brain tumors: differences in diffusion characteristics evaluated with diffusion-tensor MR imaging

International Nuclear Information System (INIS)

Toh, Cheng-Hong; Wong, Alex M.-C; Wong, Ho-Fai; Wan, Yung-Liang; Wei, Kuo-Chen; Ng, Shu-Hang

2007-01-01

We prospectively compared the fractional anisotropy (FA) and mean diffusivity (MD) of the peritumoral edema of meningiomas and metastatic brain tumors with diffusion-tensor magnetic resonance (MR) imaging. The study protocol was approved by the local ethics committee, and written informed consent was obtained. Preoperative diffusion-tensor MR imaging was performed in 15 patients with meningiomas and 11 patients with metastatic brain tumors. Regions of interest (ROI) were placed in the peritumoral edema and normal-appearing white matter (NAWM) of the contralateral hemisphere to measure the FA and MD. The FA and MD ratios were calculated for each ROI in relation to the NAWM of the contralateral hemisphere. Changes in peritumoral MD and FA, in terms of primary values and ratios, were compared using a two-sample t-test; P -3 mm 2 /s) of the peritumoral edema for metastases and meningiomas, respectively, were 0.902 ± 0.057 and 0.820 ± 0.094, the mean MD ratios were 220.3 ± 22.6 and 193.1 ± 23.4, the mean FA values were 0.146 ± 0.026 and 0.199 ± 0.052, and the mean FA ratios were 32.3 ± 5.9 and 46.0 ± 12.1. All the values were significantly different between metastases and meningiomas (MD values P 0.016, MD ratios P = 0.006, FA values P = 0.005, FA ratios P = 0.002). The peritumoral edema of metastatic brain tumors and meningiomas show different MD and FA on diffusion-tensor MR imaging. (orig.)

New definition of the cell diffusion coefficient

International Nuclear Information System (INIS)

Koehler, P.

1975-01-01

As was shown in a recent work by Gelbard, the usually applied Benoist definition of the cell diffusion coefficient gives two different values if two different definitions of the cell are made. A new definition is proposed that preserves the neutron balance for the homogenized lattice and that is independent of the cell definition. The resulting diffusion coefficient is identical with the main term of Benoist's diffusion coefficient

Essays in energy policy and planning modeling under uncertainty: Value of information, optimistic biases, and simulation of capacity markets

Science.gov (United States)

Hu, Ming-Che

Optimization and simulation are popular operations research and systems analysis tools for energy policy modeling. This dissertation addresses three important questions concerning the use of these tools for energy market (and electricity market) modeling and planning under uncertainty. (1) What is the value of information and cost of disregarding different sources of uncertainty for the U.S. energy economy? (2) Could model-based calculations of the performance (social welfare) of competitive and oligopolistic market equilibria be optimistically biased due to uncertainties in objective function coefficients? (3) How do alternative sloped demand curves perform in the PJM capacity market under economic and weather uncertainty? How does curve adjustment and cost dynamics affect the capacity market outcomes? To address the first question, two-stage stochastic optimization is utilized in the U.S. national MARKAL energy model; then the value of information and cost of ignoring uncertainty are estimated for three uncertainties: carbon cap policy, load growth and natural gas prices. When an uncertainty is important, then explicitly considering those risks when making investments will result in better performance in expectation (positive expected cost of ignoring uncertainty). Furthermore, eliminating the uncertainty would improve strategies even further, meaning that improved forecasts of future conditions are valuable ( i.e., a positive expected value of information). Also, the value of policy coordination shows the difference between a strategy developed under the incorrect assumption of no carbon cap and a strategy correctly anticipating imposition of such a cap. For the second question, game theory models are formulated and the existence of optimistic (positive) biases in market equilibria (both competitive and oligopoly markets) are proved, in that calculated social welfare and producer profits will, in expectation, exceed the values that will actually be received

Electrolyte diffusion in compacted montmorillonite engineered barriers

International Nuclear Information System (INIS)

Jahnke, F.M.; Radke, C.J.

1985-09-01

The bentonite-based engineered barrier or packing is a proposed component of several designs conceived to dispose of high-level nuclear waste in geologic repositories. Once radionuclides escape the waste package, they must first diffuse through the highly impermeable clay-rich barrier before they reach the host repository. To determine the effectiveness of the packing as a sorption barrier in the transient release period and as a mass-transfer barrier in the steady release period over the geologic time scales involved in nuclear waste disposal, a fundamental understanding of the diffusion of electrolytes in compacted clays is required. We present, and compare with laboratory data, a model quantifying the diffusion rates of cationic cesium and uncharged tritium in compacted montmorillonite clay. Neutral tritium characterizes the geometry (i.e., tortuosity) of the particulate gel. After accounting for cation exchange, we find that surface diffusion is the dominant mechanism of cation transport, with an approximate surface diffusion coefficient of 2 x 10 -6 cm 2 /s for cesium. This value increases slightly with increasing background ionic strength. The implications of this work for the packing as a migration barrier are twofold. During the transient release period, K/sub d/ values are of little importance in retarding ion migration. This is because sorption also gives rise to a surface diffusion path, and it is surface diffusion which controls the diffusion rate of highly sorbing cations in compacted montmorillonite. During the steady release period, the presence of surface diffusion leads to a flux through the packing which is greatly enhanced. In either case, if surface diffusion is neglected, the appropriate diffusion coefficient of ions in compacted packing will be in considerable error relative to current design recommendations. 11 refs., 4 figs., 1 tab

Pressure effect on grain boundary diffusion

International Nuclear Information System (INIS)

Smirnova, E.S.; Chuvil'deev, V.N.

1997-01-01

The influence of hydrostatic pressure on grain boundary diffusion and grain boundary migration in metallic materials is theoretically investigated. The model is suggested that permits describing changes in activation energy of grain boundary self-diffusion and diffusion permeability of grain boundaries under hydrostatic pressure. The model is based on the ideas about island-type structure of grain boundaries as well as linear relationship of variations in grain boundary free volume to hydrostatic pressure value. Comparison of theoretical data with experimental ones for a number of metals and alloys (α-Zr, Sn-Ge, Cu-In with Co, In, Al as diffusing elements) shows a qualitative agreement

On routing strategy with finite-capacity effect on scale-free networks

International Nuclear Information System (INIS)

Tang, S.; Jiang, X.; Ma, L.; Zhang, Z.; Zheng, Z.

2010-01-01

We propose a class of systems with finite-capacity effect to investigate routing-strategy optimization. The local topology and the variable capacity, two crucial elements for routing, are naturally coupled by considering the interactions among packets. We show how the combination of these two elements controls the normal and efficient functioning of routing in the frame of condensation and coverage, respectively. Specifically, it is shown that the dynamic behaviors of diffusing packets exhibit condensation, for which exact results of the stationary state and phase transition are given. Further, we explore the diffusion coverage of routed packets through simulation. Various alternatives for the strategy parameters are illustrated to apply standard techniques to alleviate condensation and accelerate coverage. Our results provide a practical way for the design of optimal routing strategies in complex networks by the manipulation of a few parameters. (author)

Periodic heat wave determination of thermal diffusivity of clays ...

African Journals Online (AJOL)

The responses of Ankaful, Tetegu (# 1 & 2) and Mamfe clays to periodic heat waves were analyzed to deter-mine the thermal diffusivity values. The temperature amplitude attenuated with depth of penetration, while the phase shift increased. The thermal diffusivity values ranged from 3.0 - 9.5 x 10P-7P mP2P/s by amplitude ...

Groundwater environmental capacity and its evaluation index.

Science.gov (United States)

Xing, Li Ting; Wu, Qiang; Ye, Chun He; Ye, Nan

2010-10-01

To date, no unified and acknowledged definition or well-developed evaluation index system of groundwater environment capacity can be found in the academia at home or abroad. The article explores the meaning of water environment capacity, and analyzes the environmental effects caused by the exploitation of groundwater resources. This research defines groundwater environmental capacity as a critical value in terms of time and space, according to which the groundwater system responds to the external influences within certain goal constraint. On the basis of observing the principles of being scientific, dominant, measurable, and applicable, six level 1 evaluation indexes and 11 constraint factors are established. Taking Jinan spring region for a case study, this research will adopt groundwater level and spring flow as constraint factors, and the allowable groundwater yield as the critical value of groundwater environmental capacity, prove the dynamic changeability and its indicating function of groundwater environmental capacity through calculation, and finally point out the development trends of researches on groundwater environmental capacity.

Specific cooling capacity of liquid nitrogen

Science.gov (United States)

Kilgore, R. A.; Adcock, J. B.

1977-01-01

The assumed cooling process and the method used to calculate the specific cooling capacity of liquid nitrogen are described, and the simple equation fitted to the calculated specific cooling capacity data, together with the graphical form calculated values of the specific cooling capacity of nitrogen for stagnation temperatures from saturation to 350 K and stagnation pressures from 1 to 10 atmospheres, are given.

Apparent diffusion coefficient maps obtained from high b value diffusion-weighted imaging in the preoperative evaluation of gliomas at 3T: comparison with standard b value diffusion-weighted imaging

Energy Technology Data Exchange (ETDEWEB)

Zeng, Qiang; Ling, Chenhan; Zhang, Jianmin [Second Affiliated Hospital of Zhejiang University School of Medicine, Department of Neurosurgery, Hangzhou, Zhejiang (China); Dong, Fei; Jiang, Biao [Second Affiliated Hospital of Zhejiang University School of Medicine, Department of Radiology, Hangzhou, Zhejiang (China); Shi, Feina [Second Affiliated Hospital of Zhejiang University School of Medicine, Department of Neurology, Hangzhou, Zhejiang (China)

2017-12-15

To assess whether ADC maps obtained from high b value DWI were more valuable in preoperatively evaluating the grade, Ki-67 index and outcome of gliomas. Sixty-three patients with gliomas, who underwent preoperative multi b value DWI at 3 T, were enrolled. The ADC{sub 1000}, ADC{sub 2000} and ADC{sub 3000} maps were generated. Receiver operating characteristic analyses were conducted to determine the area under the curve (AUC) in differentiating high-grade gliomas (HGG) from low-grade gliomas (LGG). Pearson correlation coefficients (R value) were calculated to investigate the correlation between parameters with the Ki-67 proliferation index. Survival analysis was conducted by using Cox regression. The AUC of the mean ADC{sub 1000} value (0.820) was lower than that of the mean ADC{sub 2000} value (0.847) and mean ADC{sub 3000} value (0.875) in differentiating HGG from LGG. The R value of the mean ADC{sub 1000} value (-0.499) was less negative than that of the mean ADC{sub 2000} value (-0.530) and mean ADC{sub 3000} value (-0.567). The mean ADC{sub 3000} value was an independent prognosis factor for gliomas (p = 0.008), while the mean ADC{sub 1000} and ADC{sub 2000} values were not. ADC maps obtained from high b value DWI might be a better imaging biomarker in the preoperative evaluation of gliomas. (orig.)

Heat Capacity Analysis Report

International Nuclear Information System (INIS)

Findikakis, A.

2004-01-01

The purpose of this report is to provide heat capacity values for the host and surrounding rock layers for the waste repository at Yucca Mountain. The heat capacity representations provided by this analysis are used in unsaturated zone (UZ) flow, transport, and coupled processes numerical modeling activities, and in thermal analyses as part of the design of the repository to support the license application. Among the reports that use the heat capacity values estimated in this report are the ''Multiscale Thermohydrologic Model'' report, the ''Drift Degradation Analysis'' report, the ''Ventilation Model and Analysis Report, the Igneous Intrusion Impacts on Waste Packages and Waste Forms'' report, the ''Dike/Drift Interactions report, the Drift-Scale Coupled Processes (DST and TH Seepage) Models'' report, and the ''In-Drift Natural Convection and Condensation'' report. The specific objective of this study is to determine the rock-grain and rock-mass heat capacities for the geologic stratigraphy identified in the ''Mineralogic Model (MM3.0) Report'' (BSC 2004 [DIRS 170031], Table 1-1). This report provides estimates of the heat capacity for all stratigraphic layers except the Paleozoic, for which the mineralogic abundance data required to estimate the heat capacity are not available. The temperature range of interest in this analysis is 25 C to 325 C. This interval is broken into three separate temperature sub-intervals: 25 C to 95 C, 95 C to 114 C, and 114 C to 325 C, which correspond to the preboiling, trans-boiling, and postboiling regimes. Heat capacity is defined as the amount of energy required to raise the temperature of a unit mass of material by one degree (Nimick and Connolly 1991 [DIRS 100690], p. 5). The rock-grain heat capacity is defined as the heat capacity of the rock solids (minerals), and does not include the effect of water that exists in the rock pores. By comparison, the rock-mass heat capacity considers the heat capacity of both solids and pore

A Catalyst-for-Change Approach to Evaluation Capacity Building

Science.gov (United States)

Garcia-Iriarte, Edurne; Suarez-Balcazar, Yolanda; Taylor-Ritzler, Tina; Luna, Maria

2011-01-01

Evaluation capacity building (ECB) has become a popular approach for helping community-based organizations (CBOs) to meet their funders' demands for accountability. This case study reports the ECB process with one staff member using a catalyst-for-change approach. The authors analyzed the role of the catalyst in diffusing evaluation knowledge and…

Underlying Dimensions and Organizational Values in Organizational Learning: Strategy for Capacity Building in Developing Countries

Directory of Open Access Journals (Sweden)

María Isabel Rivera Vargas

2013-09-01

Full Text Available The idea that organizational learning is closely linked to innovation became firmly established by the end of the nineties (Argyris and Schön, 1978; Watkins and Marsick, 1993; Nonaka and Takeuchi, 1995, however, very little research in these topics is done in developing countries. Therefore, the objective of this article is to expose the underlying dimensions as well as the organizational values that should characterize an organizational learning process, as a strategy for technological capacities construction in small and medium size firms. Consequently, through analytical-synthetic methodology including a case study analysis, this article evidence those determinants characteristics of an organizational learning approach to promote the planning of technological learning processes for catching up in order for developing countries to get into the path of innovation.

Moisture diffusivity in structure of random fractal fiber bed

Energy Technology Data Exchange (ETDEWEB)

Zhu, Fanglong, E-mail: zhufanglong_168@163.com [College of Textile, Zhongyuan University of Technology, Zhengzhou City (China); The Chinese People' s Armed Police Forces Academy, Langfan City (China); Zhou, Yu; Feng, Qianqian [College of Textile, Zhongyuan University of Technology, Zhengzhou City (China); Xia, Dehong [School of Mechanical Engineering, University of Science and Technology, Beijing (China)

2013-11-08

A theoretical expression related to effective moisture diffusivity to random fiber bed is derived by using fractal theory and considering both parallel and perpendicular channels to diffusion flow direction. In this Letter, macroporous structure of hydrophobic nonwoven material is investigated, and Knudsen diffusion and surface diffusion are neglected. The effective moisture diffusivity predicted by the present fractal model are compared with water vapor transfer rate (WVTR) experiment data and calculated values obtained from other theoretical models. This verifies the validity of the present fractal diffusivity of fibrous structural beds.

Devil's in the (diffuse) detail

International Nuclear Information System (INIS)

Welberry, R.

2006-07-01

X-ray crystallography is an important workhorse in the world of solid-state chemistry. However, while it's a powerful tool in determining the average structure in a crystal lattice, conventional crystallography is very limited when it comes to understanding nano-scale disorder within that crystal structure. And when it comes to understanding the properties of many important materials, the devil is in the detail. X-ray diffraction is still one of the keys to understanding this finer scale structure but using it requires a capacity to read between the lines - to understand the diffuse diffraction that most crystallography ignores. Scientists at the Research School of Chemistry are leading the world in this field. Their work on modelling nano-scaled disorder using diffuse diffraction is opening up new possibilities in understanding and modifying many of our most important materials

Network capacity auctions: promise and problems

International Nuclear Information System (INIS)

Newbery, David M.

2003-01-01

Well-designed auctions work favorably for allocating idiosyncratic properties efficiently. Auctions are used to allocate entry capacity for United Kingdom gas and inter-connector capacity for electricity in several European Union countries and can work well for allocating existing capacity, though careful auction design is needed to mitigate potential market power. Using auction prices to guide investment decisions in networks is problematic if bidders fear that sub-optimal investment will be compensated by regulatory fiat, lowering future capacity values. (Author)

An integrated approach to evaluate food antioxidant capacity.

Science.gov (United States)

Sun, T; Tanumihardjo, S A

2007-11-01

Many methods are available for determining food antioxidant capacity, which is an important topic in food and nutrition research and marketing. However, the results and inferences from different methods may vary substantially because each complex chemical reaction generates unique values. To get a complete and dynamic picture of the ranking of food antioxidant capacity, relative antioxidant capacity index (RACI), a hypothetical concept, is created from the perspective of statistics by integrating the antioxidant capacity values generated from different in vitro methods. RACI is the mean value of standard scores transformed from the initial data generated with different methods for each food item. By comparing the antioxidant capacity of 20 commonly consumed vegetables in the U.S. market that were measured with 7 chemical methods, we demonstrated that the RACI correlated strongly with each method. The significant correlation of RACI with an independent data set further confirmed that RACI is a valid tool to assess food antioxidant capacity. The key advantage of this integrated approach is that RACI is in a numerical scale with no units and has consistent agreement with chemical methods. Although it is a relative index and may not represent a specific antioxidant property of different food items, RACI provides a reasonably accurate rank of antioxidant capacity among foods. Therefore, it can be used as an integrated approach to evaluate food antioxidant capacity.

Diffusion in building wakes

International Nuclear Information System (INIS)

Ramsdell, J.V.

1988-03-01

Straight-line Gaussian models adequately describe atmospheric diffusion for many applications. They have been modified for use in estimating diffusion in building wakes by adding terms that include projected building area and by redefining the diffusion coefficients so that the coefficients have minimum values that are related to building dimensions. In a recent study, Ramsdell reviewed the building-wake dispersion models used by the Nuclear Regulatory Commission (NRC) in its control room habitability assessments. The review included comparison of model estimates of centerline concentrations with concentrations observed in experiments at seven nuclear reactors. In general, the models are conservative in that they tend to predict concentrations that are greater than those actually observed. However, the models show little skill in accounting for variations in the observed concentrations. Subsequently, the experimental data and multiples linear regression techniques have been used to develop a new building wake diffusion model. This paper describes the new building wake model and compares it with other models. 8 refs., 2 figs

Value of MR diffusion weighted imaging in the diagnosis of hepatic fibrosis of rat

International Nuclear Information System (INIS)

Fan Guohua; Gong Jianping; Shen Junkang; Zhang Caiyuan; Xu Xiaoqiu; Xu Liang; Yu Zeyang; Zhang Wei; Wu Haorong

2013-01-01

Objective: To investigate the value of DWI in the early diagnosis and staging of hepatic fibrosis of rats. Methods: Rat model with hepatic fibrosis was established by using carbon tetrachloride. By using completely randomized design random digits table, 5 or 6 rats were assigned to model group and 1 or 2 rats to the control group. After drug administration from the second week to the end of 16th weeks, a total of 72 rats of model group and 30 rats of control group were included in this study to undergo DWI scanning. The signal intensity of DWI, the value of ADC and exponential apparent diffusion coefficient (EADC) for different b values (b = 0, 300, 600, 800 and 1000 s/mm"2 respectively) were calculated. The rats were sacrificed to death to have pathologic examination in 4h after DWI scanning. Seventy-two model rats with hepatic fibrosis were grouped according to their pathological staging. The difference of the value of hepatic signal-to-noise ratio (SNR) of different b values, and the value of ADC and EADC among control group and model groups were compared by analysis of variance with completely randomized design data rank transformation and SNK multiple comparison. The correlation of SNR and b values, and staging of hepatic fibrosis and the value of ADC and EADC were tested by rank correlation analysis. Results: (1) The signal intensity of DWI of the rats of model group showed the tendency of increase with the increase of stage of hepatic fibrosis. (2) SNR showed the tendency of decrease with the increase of b values. When b value was 600 s/mm"2 or 800 s/mm"2, SNR was 31.2 ± 11.6 and 24.8 ± 6.8 respectively and the quality of images was good. (3) There were 17 rats in grade 1, 21 rats in grade 2, 19 rats in grade 3 and 15 rats in grade 4 of hepatic fibrosis. The value of ADC of control group and of grade 1 to 4 of hepatic fibrosis were (1.65 ± 0.38) × 10"-"3, (1.34 ± 0.32) × 10"-"3, (1.04 ± 0.20) × 10"-"3, (0.99 ± 0.19) × 10"-"3, (0.62 ± 0.21) × 10

Current limiting capability of diffused resistors

International Nuclear Information System (INIS)

Shedd, W.; Cappelli, J.

1979-01-01

An experimental evaluation of the current limiting capability of dielectrically isolated diffused resistors at transient ionizing dose rates up to 6*10 12 rads(Si)/sec is presented. Existing theoretical predictions of the transient response of diffused resistors are summarized and compared to the experimentally measured values. The test resistors used allow the effects of sheet resistance and geometry on the transient response to be determined. The experimental results show that typical dielectrically isolated diffused resistors maintain adequate current limiting capability for use in radiation hardened integrated circuits

Diffusion in copper sulphides. An experimental study of chalcocite, chalcopyrite and bornite

International Nuclear Information System (INIS)

Berger, R.; Bucur, R.V.

1996-01-01

Diffusion measurements on three copper-containing sulphides have been performed by an electrochemical potentiometric method. Chalcocite (Cu 2 S), Chalcopyrite (CuFeS 2 ) and Bornite (Cu 5 FeS 4 ) were synthesized and fully characterized by X-ray diffraction. The diffusivities were measured on compacted powders yielding both the chemical and the component diffusion coefficients in the temperature range 5-50 C. The chemical diffusion coefficients found were: for Chalcocite 38.7*exp (-5600/T), for Chalcopyrite 15.4*exp(-6000/T) and for Bornite 14.4*exp(-4900/T). The diffusion coefficient for Chalcocite is in good agreement with values found previously, and a reasonable agreement is also found for Chalcopyrite and Bornite when our data are compared with values acquired at much higher temperatures with a different technique. The activation energies (here on a Kelvin scale) are remarkably similar for the three sulfides, considering that their relative errors are of a 10% magnitude, which indicates that the bonding strengths and the diffusion mechanisms are similar. The chemical diffusion coefficients which enter the empirical Fick's diffusion laws that describe concentration changes, are of the order of exp(-8) to exp (-7) cm 2 /s at room temperature. Such values bring the ion mobilities near values found for solid state 'fast ion conductors', used as electrolytes at elevated temperatures. 17 refs, 8 figs, 5 tabs

Group additivity values for enthalpies of formation (298 K), entropies (298 K), and molar heat capacities (300 K < T < 1500 K) of gaseous fluorocarbons

International Nuclear Information System (INIS)

Van Otterloo, Maren K.; Girshick, Steven L.; Roberts, Jeffrey T.

2007-01-01

A group additivity method was developed to estimate standard enthalpies of formation and standard entropies at 298 K of linear radical and closed-shell, gaseous fluorocarbon neutrals containing four or more carbon atoms. The method can also be used to estimate constant pressure molar heat capacities of the same compounds over the temperature range 300 K to 1500 K. Seventeen groups and seven fluorine-fluorine interaction terms were defined from 12 fluorocarbon molecules. Interaction term values from Yamada and Bozzelli [T. Yamada, J.W. Bozzelli, J. Phys. Chem. A 103 (1999) 7373-7379] were utilized. The enthalpy of formation group values were derived from G3MP2 calculations by Bauschlicher and Ricca [C.W. Bauschlicher, A. Ricca, J. Phys. Chem. A 104 (2000) 4581-4585]. Standard entropy and molar heat capacity group values were estimated from ab initio geometry optimization and frequency calculations at the Hartree-Fock level using the 6-31G(d) basis set. Enthalpies of formation for larger fluorocarbons estimated from the group additivity method compare well to enthalpies of formation found in the literature

The predictive value of MR diffusion weighted imaging on the delayed encephalopathy after carbon monoxide poisoning