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Reproducibility
Kinds of Reproducibility Terms modified by Reproducibility Selected AbstractsANALYSIS OF SHORT-TERM REPRODUCIBILITY OF ARTERIAL VASOREACTIVITY BY PULSE-WAVE ANALYSIS AFTER PHARMACOLOGICAL CHALLENGECLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 1 2009Biju Paul SUMMARY 1Pulse-wave analysis (PWA) is an established method to assess arterial wave reflections and arterial vasoreactivity in humans. A high short-term reproducibility of baseline augmentation index (AIx) has been reported. However, the short-term reproducibility of AIx changes following pharmacological challenge with either inhaled salbutamol (endothelium-dependent vasodilatation) or sublingual glyceryl trinitrate (GTN; endothelium-independent vasodilatation), using appropriate statistical methods, is largely unknown. 2Baseline AIx and GTN- and salbutamol-mediated changes in AIx (all corrected for a heart rate of 75 b.p.m.) were measured on two separate occasions, 1 h apart, in 22 healthy controls (mean (±SD) age 52.0 ± 13.4 years) and 11 elderly patients with chronic heart failure (CHF; 73.1 ± 8.7 years). Reproducibility was assessed by measuring intraclass correlation coefficients (ICC), coefficients of variation (CV) and Bland,Altman plots. 3Baseline AIx showed good short-term reproducibility with high ICC in both the control and CHF groups (0.90 and 0.87, respectively). In contrast, in the control and CHF groups, the ICC of GTN- (0.58 and 0.17, respectively) and salbutamol-mediated (0.18 and 0.04, respectively) changes in AIx were substantially low. The CV was relatively low for baseline AIx in control and CHF groups (25.0 and 22.5%, respectively), but not for GTN- (22.3 and 59.8%, respectively) or salbutamol-mediated (45.1 and 184.0%, respectively) changes in AIx. Bland,Altman analysis revealed poor reproducibility, with limits of agreement beyond either +15% or ,15% for changes in AIx after GTN and salbutamol for both control and CHF groups. The changes in blood pressure and heart rate following pharmacological challenge were similar between the two measurements. 4The poor reproducibility of changes in AIx following pharmacological challenge questions the use of this method in acute studies. [source] Quantitative capillary electrophoresis and its application in analysis of alkaloids in tea, coffee, coca cola, and theophylline tabletsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 2 2009Mengjia Li Abstract A quantitative CE (qCE) system with high precision has been developed, in which a 4-port nano-valve was isolated from the electric field and served as sample injector. The accurate amount of sample was introduced into the CE system with high reproducibility. Based on this system, consecutive injections and separations were performed without voltage interruption. Reproducibilities in terms of RSD lower than 0.8% for retention time and 1.7% for peak area were achieved. The effectiveness of the system was demonstrated by the quantitative analysis of caffeine, theobromine, and theophylline in real samples, such as tea leaf, roasted coffee, coca cola, and theophylline tablets. [source] Reproducibility evaluation of gross and net walking efficiency in children with cerebral palsyDEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 1 2007Merel-Anne Brehm MSc In evaluating energy cost (EC) of walking, referred to as walking efficiency, the use of net measurement protocols (i.e. net=gross-resting) has recently been recommended. However, nothing is known about the comparative reproducibility of net protocols and the commonly used gross protocols. Ten minutes of resting and 5 minutes of walking at a self-selected speed were used to determine gross and net EC in 13 children with spastic cerebral palsy (CP; seven males, six females; mean age 8y 7mo [SD 3y 4mo], range 4y 1mo,13y) and in 10 children (three males, seven females) with typical development. In the former, their Gross Motor Function Classification System levels ranged from Level I to Level III; and seven had hemiplegia and six diplegia. There were four repeated sessions on different days, with periods of 1 week between sessions. Reproducibility was assessed for speed, and gross and net EC, by using the standard error of measurement. The results of this preliminary study showed that EC measurements were more variable for children with CP than for children with typical development. Furthermore, in both groups there was considerably more variability in the net measurements than in the gross measurements. We conclude that, on the basis of the methodology used, the use of gross EC, rather than net EC, seems a more sensitive measure of walking efficiency to detect clinically relevant changes in an individual child with CP. [source] Reproducibility, validity, and responsiveness of a disease-specific symptom questionnaire for gastroesophageal reflux diseaseDISEASES OF THE ESOPHAGUS, Issue 4 2000C. J. Allen The purpose of this study was to establish the reproducibility, validity, and responsiveness of a symptom questionnaire to assess patients with gastroesophageal reflux disease (GERD). A total of 300 patients with GERD completed questionnaires before and 6 months after laparoscopic Nissen fundoplication. Forty-six GERD patients who continued on omeprazole served as controls. Lower esophageal sphincter pressure, 24-h pH, and quality of life (SF36) were measured at baseline and follow-up. Reproducibility was calculated as an intraclass correlation coefficient (ICC) from a repeated-measures analysis of variance on symptom scores (SS) on two consecutive days. Validity was established by correlating SS with 24-h pH and SF36 scores. Responsiveness was calculated as the the ratio of the mean paired difference in score in the surgical group to the within-subject variability in control subjects. Reproducibility was very high, as revealed by an ICC of 0.92. Strong correlations between SS and SF36 scores at baseline and after surgery demonstrated high cross-sectional validity. Correlation between change in SS and change in pH, SF36 pain, general health, and physical health scores demonstrated longitudinal validity. The mean (95% confidence interval) paired differences in SS were 25.6 (23.7, 27.5) in the study and 2.0 (,3.2, 7.3) in the control groups, and the responsive index was 1.0. The estimated minimally important clinical difference was 7. We conclude that the symptom score is a reproducible, valid, and responsive instrument for assessing symptoms caused by GERD. [source] Microflow Vessel Improving Reproducibility and Sensitivity of Electrochemical MeasurementsELECTROANALYSIS, Issue 23 2008Jan Krejci Abstract A new microflow system was designed and developed for electrochemical measurements. The electrochemical electrodes prepared using thick film technology were used in this arrangement. Results of various measurements such as simple amperometric measurement on the example of H2O2 detection, measurement with glucose oxidase (GOx) biosensor, soluble enzyme activity measurement etc. carried out using this system are reported. It was observed that the sensitivity and reproducibility of the electrochemical measurements is improved significantly. The new device performance was proved on H2O2 detection, activity of GOx measurement and heavy metals detection (measured concentration range: H2O2 10,9 to 10,1,M, glucose 10,6 to 10,2,M, activity of GOx 10,1 to 102,IU, heavy metals (Cu, Pb) 10,4 to 10,3,M). The microflow insert greatly reduces the overall size of the electrolyte vessel and measurements with sample quantity as low as 2,mL can be accomplished. [source] Retention of proteins and metalloproteins in open tubular capillary electrochromatography with etched chemically modified columns,ELECTROPHORESIS, Issue 18 2008Joseph J. Pesek Abstract Etched chemically modified capillaries with two different bonded groups (pentyl and octadecyl) are compared for their migration behavior of several common proteins and metalloproteins as well as metalloproteinases. Migration times, efficiency and peak shape are evaluated over the pH range of 2.1,8.1 to determine any effects of the bonded group on the electrochromatographic behavior of these compounds. One goal was to determine if the relative hydrophobicity of the stationary phase has a significant effect on proteins in the open tubular format of capillary electrochromatography as it does in HPLC. Reproducibility of the migration times is also investigated. [source] Determination of neutral carbohydrates by CZE with direct UV detectionELECTROPHORESIS, Issue 17 2007Stella Rovio Abstract A new CZE method relying on in-capillary reaction and direct UV detection at the wavelength 270,nm is presented for the simultaneous separation of the neutral carbohydrates xylitol, D -(,)-mannitol, sucrose, D -(+)-fucose, D -(+)-cellobiose, D -(+)-galactose, D -(+)-glucose, L -rhamnose, D -(+)-mannose, D -(,)-arabinose, D -(+)-xylose, and D -(,)-ribose. The alkaline electrolyte solution was prepared of 130,mM sodium hydroxide and 36,mM disodium hydrogen phosphate dihydrate. Separation of the sample mixture was achieved within 35,min. Calibration plots were linear in the range of 0.05,3,mM. Reproducibility of migration times was between 0.3 and 1.1%, and the detection limits for the analytes were 0.02 and 0.05,mM. The optimized method was applied for the determination of neutral monosaccharides in lemon, pineapple, and orange juices and a cognac sample. The methodology is fast since no other sample preparation except dilution is required. [source] Measurement of specific radioactivity in proteins separated by two-dimensional gel electrophoresisELECTROPHORESIS, Issue 5-6 2006Shaobo Zhou Abstract We report a method to quantify the specific radioactivity of proteins that have been separated by 2-DE. Gels are stained with SyproRuby, and protein spots are excised. The SyproRuby dye is extracted from each spot using DMSO, and the fluorescence is quantified automatically using a plate reader. The extracted gel piece is then dissolved in hydrogen peroxide and radioactivity is quantified by liquid scintillation counting. Gentle agitation with DMSO for 24,h was found to extract all the SyproRuby dye from gel fragments. The fluorescence of the extract was linearly related to the amount of BSA loaded onto a series of 1-D gels. When rat muscle samples were run on 2-DE gels, the fluorescence extracted from 54,protein spots showed a good correlation (r = 0.79, p < 0.001) with the corresponding spot intensity measured by conventional scanning and image analysis. DMSO extraction was found not to affect the amount of radioactive protein left in the gel. When a series of BSA solutions of known specific radioactivity were run on 2-DE gels, the specific radioactivity measured by the new method showed a good correlation (r = 0.98, p < 0.01, n = 5) with the specific radioactivity measured directly before loading. Reproducibility of the method was measured in a series of 2-DE gels containing proteins from the livers of rats and mice that had been injected with [35S]methionine. Variability tended to increase when the amount of radioactivity in the protein spot was low, but for samples containing at least 10,dpm above background the CV was around 30%, which is comparable to that obtained when measuring protein expression by conventional image analysis of SyproRuby-stained 2-DE gels. Similar results were obtained whether spots were excised manually or using a spot excision robot. This method offers a high-throughput, cost-effective and reliable method of quantifying the specific radioactivity of proteins from metabolic labelling experiments carried out in,vivo, so long as sufficient quantities of radioactive tracer are used. [source] Long-term Reproducibility of fMRI Activation in Epilepsy Patients with Fixation Off SensitivityEPILEPSIA, Issue 7 2005Carlo Di Bonaventura No abstract is available for this article. [source] Reproducibility of a microbial river water community to self-organize upon perturbation with the natural chemical enantiomers, R - and S -carvoneFEMS MICROBIOLOGY ECOLOGY, Issue 2 2008Katja Lehmann Abstract A river water microbial community was studied in response to perturbation with the monoterpene enantiomers R - and S -carvone. The microbial community structure and function was also evaluated after enantiomers exposure was switched. Microbial communities were evaluated by length heterogeneity PCR. The addition of R - and S -carvone enriched for a range of functionally different communities: enantiomer-selective, racemic and ones that contain both. After 5 days incubation, the R - and S -carvone treatments developed a range of dominant microbial communities, which were increasingly dissimilar from the ones in which no carvone degradation had taken place (R -values: R -carvone 0.743, S -carvone 0.5007). There was an increase in the evenness of the microbial community structure upon carvone depletion. After the cross-over, the rate of carvone utilization was significantly faster than after the first carvone addition (P=0.008) as demonstrated by concomitant carvone and oxygen depletion. The main R -degrading community (450,456 bp) appeared enantioselective and largely unable to degrade S -carvone, whereas the S -carvone-degrading community (502,508 bp) appeared to have racemic catabolic capacity. In conclusion, chemical perturbations, such as enantiomers, might generate a significant shift in the river microbial ecology that can have implications for the function of a river in both a spatial and temporal context. [source] BDMC interlaboratory cone calorimeter test programmeFIRE AND MATERIALS, Issue 1 2002Joe Urbas In the spring of 1997, seven companies and industry associations from the USA and Canada decided to sponsor the cone calorimeter interlaboratory test programme. Reproducibility and repeatability were determined for the scalar variables measured in the cone calorimeter (ASTM E1354) according to the protocol developed by the Board for the Coordination of the Model Codes. The main requirement of the protocol was that the sample irradiance should be 75 kW/m2. The purpose of the project was to assist the model building code organizations, NFPA and various other groups in the development of a system to determine degrees of combustibility of building materials. Three US and one Canadian laboratory agreed to conduct tests on 16 materials. The results of this round robin show that the cone calorimeter, following the Board for the Coordination of the Model Codes protocol, can provide precision similar to that cited in the current cone calorimeter standards. It is recommended that further improvements of the standards are pursued and provisions are made to improve the quality of operation of the cone calorimeter in commercial laboratories to maintain and possibly improve its repeatability and reproducibility. Copyright © 2002 John Wiley & Sons, Ltd. [source] Comparison of Pb Purification by Anion-Exchange Resin Methods and Assessment of Long-Term Reproducibility of Th/U/Pb Ratio Measurements by Quadrupole ICP-MSGEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 2 2009Balz S. Kamber échange d'anions; purification de Pb; élimination de matrice A comparison between HBr-HCl and HBr-HNO3 based anion chemistry is presented to test the efficiency of Pb purification in the preparation of samples for isotope ratio measurement by ICP-MS. It was found that the small advantages in yield and blank offered by the HNO3 -based method were more than compensated by the more effective matrix removal of the HCl-based method. Apart from very zinc rich matrices (e.g., sphalerite), a careful single pass purification using HBr and HCl removed more than 99.9% of the matrix. In preparation for the isotope ratio analysis, a small (2,5% m/v) liquid sample aliquot was analysed to determine U, Th and Pb concentrations by solution quadrupole ICP-MS. This allowed accurate prediction of the expected ion signal and permitted optimal spiking with Tl, if desired, for mass bias correction. Long-term results for international rock reference materials showed reproducibilities of better than 1% (Th/U) and 1.5% (U/Pb). For most geological applications, such analyses obviate the need for isotope dilution concentration measurements. Les échantillons dont on veut mesurer la composition isotopique de Pb par ICP-MS sont préparés par élution sur résines anioniques. Une comparaison a été effectuée entre la chimie utilisant HBr-HCl et celle utilisant HBr-HNO3, pour vérifier leurs efficacités respectives. On montre que le léger avantage présenté par HNO3 pour ce qui concerne la qualité des blancs et le rendement était plus que compensé par la bien meilleure élimination de la matrice effectuée par la méthode utilisant HCl. A l'exception des matrices très riches en zinc (par ex sphalérite) une seule purification soigneuse avec HBr et HCl éliminait plus de 99.9% de la matrice. Pour préparer l'analyse isotopique, un petit volume (2,5% m/v) était prélevé afin d'analyser les concentrations en U, Th et Pb par ICP-MS à quadrupôle. Ceci permettait de prédire de façon précise l'intensité du signal espérée et d'optimiser la quantité de solution de spike de Tl à mettre si on souhaite corriger ainsi le biais de masse. Les résultats sur le long terme obtenus sur des roches, matériaux de référence internationale, ont montré des reproductibilités meilleures que 1% (Th/U) et 1.5% (U/Pb). Pour la plupart des applications, des analyses de cette qualité suppriment le besoin de mesures de concentrations par dilution isotopique. [source] Reply to the letter of Rogers et al. entitled "Reproducibility of cancer diagnosis using hair"INTERNATIONAL JOURNAL OF CANCER, Issue 4 2006Veronica J. James No abstract is available for this article. [source] Diagnosis of peripheral arterial disease in general practice: can the ankle,brachial index be measured either by pulse palpation or an automatic blood pressure device?,INTERNATIONAL JOURNAL OF CLINICAL PRACTICE, Issue 7 2008V. Aboyans Summary Background:, Despite its validity as a screening test for peripheral arterial disease (PAD), and its prognostic value, the ankle,brachial index (ABI) is infrequently used in primary care, probably because a Doppler device is required, along with the requisite skill for its use. We hypothesized that ABI could be accurately measured either by pulse palpation (pABI) or automatic blood pressure devices (autoABI) instead of Doppler method (dABI). Design and methods:, In 54 subjects, we compared the results and the intra-observer reproducibility of pABI to dABI, as well as the inter-observer reproducibility of both pABI and autoABI to dABI. Arm and ankle systolic pressures were measured by the three methods by two observers. The first observer repeated pABI and dABI measurements. The results were compared by the Student paired t -test. Reproducibility was assessed by the intra-class correlation coefficient of agreement (R) and the Bland and Altman method. Results:, The mean dABI obtained by the first observers was 1.03 ± 0.26 vs. a pABI of 0.85 ± 0.44 (p < 0.0001) and an autoABI of 1.09 ± 0.31 (p < 0.05). The intra-observer R -coefficient was at 0.89 for dABI vs. 0.60 for pABI (p < 0.05). The inter-observer R -coefficients were 0.79 for dABI vs. 0.40 for pABI (p < 0.05) and 0.44 for autoABI (p < 0.05). Conclusion:, Neither pulse palpation nor automatic oscillometric devices can be recommended as reliable methods for ABI measurement. [source] Reproducibility of 3-dimensional sonographic measurements of fetal and placental volume at gestational ages of 11,18 weeksJOURNAL OF CLINICAL ULTRASOUND, Issue 3 2007Koen Deurloo MD Abstract Purpose. Determine the reproducibility of 3D ultrasound (3DUS) measurements of fetal and placental volumes. Methods. We included 34 pregnant women between gestational weeks (GW) 11,18. Two operators independently acquired fetal and placental volumes using 3DUS. Each volume was acquired twice and stored on disk for off-line analysis. Intra- and interobserver reproducibility was expressed in the intra- and interclass correlation coefficient (intra-CC and inter-CC). In addition, the 3DUS volumes acquired by the first operator were calculated by the second and vice-versa to evaluate the effect of volume acquisition and caliper placement. A value >0.75 was considered a good agreement. Results. Fetal and placental volume measurements were successful in 97% of all cases. Between GW 11,14 and 14,18 the median fetal volume was 20.8 (5.0,35.1) and 51.7 (37.9,132.8) ml, the median placental volume was 71.3 (40.9,111.9) and 120.7 (94.2, 273.7) ml. Bland-Altman plots were used for statistical analysis. The intraobserver reproducibility was good for fetus (intra-CC: 0.99; 0.99) and placenta (intra-CC: 0.99; 0.98). Also, interobserver reproducibility was good for fetus (inter-CC 0.98) and placenta (inter-CC 0.98). In addition, regardless of the operator who acquired the volumes, the inter-CC remained good for both fetus (inter-CC: 0.99; 0.99) and placenta (inter-CC: 0.97; 0.99). Conclusion. The reproducibility of fetal and placental volume measurements by 3DUS between GW 11,18 is good. In addition, individually chosen caliper placement and volume acquisition has no effect on the calculation of either volumes. © 2007 Wiley Periodicals, Inc. J Clin Ultrasound, 2007 [source] Sonographic guidance for electron boost planning after breast-conserving surgeryJOURNAL OF CLINICAL ULTRASOUND, Issue 7 2004Antje Warszawski MD Abstract Purpose This study was conducted to determine the feasibility of using sonography for electron boost planning in breast cancer treatment and to define the factors that influence the accuracy and reproducibility of this technique. Patients and Methods Seventy-seven patients underwent 102 sonographic examinations after breast-conserving surgery and before and after radiotherapy. The size of the electron boost field was defined by measuring the postoperative cavity. Reproducibility of the sonographic findings was investigated in 25 of the patients who were examined before and after radiotherapy (at a total dose of 46,50.4 Gy). Depth (distance from the skin surface to the posterior aspect of the postoperative cavity) was measured, and sonographic appearance of the postoperative cavity was evaluated. Type of surgical procedure, time elapsed since surgery, use of systemic therapy, menopausal status, breast size, and radiation dose were investigated for their influence on sonographic appearance and visualization of the postoperative cavity. Results The postoperative cavity was well visualized in 78% of patients and visualized with some difficulty in 22%. In all but 5 patients, it was hypoechoic and inhomogeneous. The mean depth of the postoperative cavity after radiotherapy was 27 ± 4 mm. Smaller breast (p < 0.001) and younger age (p < 0.05) were associated with decreased visibility of the postoperative cavity. Sonographic appearance was the same before and after radiotherapy, but the mean difference in postoperative cavity depth between the 2 measurements was 2 mm (range, 0,4 mm). In 43/77 (56%) of the patients, changes in electron energy or in field size were required after sonographic measurement. Conclusion Sonography is a useful and reproducible means of electron boost planning, helping to avoid underdosage of the postoperative cavity and overdosage of normal tissue. © 2004 Wiley Periodicals, Inc. J Clin Ultrasound 32:333,337, 2004 [source] Reproducibility of black blood dynamic contrast-enhanced magnetic resonance imaging in aortic plaques of atherosclerotic rabbitsJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 1 2010Claudia Calcagno MD Abstract Purpose: To investigate the short-term reproducibility of black-blood dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) in atherosclerotic rabbits to evaluate the potential of this technique to be a reliable readout of plaque progression and/or regression upon therapeutic intervention. Materials and Methods: Atherosclerotic rabbits were imaged at baseline and 24 hours later with DCE-MRI on a 1.5T MRI system. DCE-MRI images were analyzed by calculating the area under the signal intensity versus time curve (AUC). Intraclass correlation coefficients (ICCs) were used to evaluate interscan, intraobserver, and interobserver reproducibility. In addition, the test,retest coefficient of variation (CoV) was evaluated. Results: Statistical analyses showed excellent interscan, intraobserver, and interobserver agreement. All ICCs were greater than 0.75, P < 0.01 indicating excellent agreement between measurements. Conclusion: Experimental results show good interscan and excellent intra- and interobserver reproducibility, suggesting that DCE-MRI could be used in preclinical settings as a read-out for novel therapeutic interventions for atherosclerosis. This preliminary work encourages investigating the reproducibility of DCE-MRI also in clinical settings, where it could be used for monitoring high-risk patients and in longitudinal clinical drug trials. J. Magn. Reson. Imaging 2010;32:191,198. © 2010 Wiley-Liss, Inc. [source] Hyperpolarized 3He apparent diffusion coefficient MRI of the lung: Reproducibility and volume dependency in healthy volunteers and patients with emphysemaJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2008Sandra Diaz MD Abstract Purpose To measure the apparent diffusion coefficient (ADC) of hyperpolarized (HP) 3He gas using diffusion weighted MRI in healthy volunteers and patients with emphysema and examine the reproducibility and volume dependency. Materials and Methods A total of eight healthy volunteers and 16 patients with emphysema were examined after inhalation of HP 3He gas mixed with nitrogen (N2) during breathhold starting from functional residual capacity (FRC) in supine position. Coronal diffusion-sensitized MR images were acquired. Each subject was imaged on three separate days over a seven-day period and received two different volumes (6% and 15% of total lung capacity [TLC]) of HP 3He each day. ADC maps and histograms were calculated. The mean and standard deviation (SD) of the ADC at different days and volumes were compared. Results The reproducibility of the mean ADC and SD over several days was good in both healthy volunteers and patients (SD range of 0.003,0.013 cm2/second and 0.001,0.009 cm2/second at 6% and 15% of TLC for healthy volunteers, and a SD range of 0.001,0.041 cm2/second and 0.001,0.011 cm2/second, respectively, for patients). A minor but significant increase in mean ADC with increased inhaled gas volume was observed in both groups. Conclusion Mean ADC and SD of HP 3He MRI is reproducible and discriminates well between healthy controls and patients with emphysema at the higher gas volume. This method is robust and may be useful to gain new insights into the pathophysiology and course of emphysema. J. Magn. Reson. Imaging 2008. © 2008 Wiley-Liss, Inc. [source] Reproducibility and dependence on diffusion weighting of line scan diffusion in the lumbar intervertebral discsJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2005David C. Newitt PhD Abstract Purpose To investigate the dependence of line scan diffusion imaging (LSDI) in the lumbar vertebral discs on diffusion weighting, fat suppression (FS), and postprocessing noise correction. Materials and Methods Eleven normal volunteers were scanned using 4 b-value and 12 b-value LSDI protocols, with and without FS. Three repeated four b-value scans were performed for evaluation of the reproducibility of apparent diffusion coefficient (ADC) values calculated with mono- and biexponential decay models. Two-point ADC analysis for 12 b-value scans was performed with and without noise correction to evaluate the ADC dependence on diffusion weighting. Correlations between different ADC calculation and acquisition methods were evaluated. Results Monoexponential ADC measures had a coefficient of variation (CV) under 3%, while use of a constrained biexponential increased the CV to 6% to 9%. Strong dependence on b-value was seen from chemically shifted marrow fat signal and noise. These systematic variations in ADC were eliminated using noise correction and FS. ADC values from 4 and 12 b-value FS scans correlated strongly (R2 = 0.91), while biexponentially derived ADC values correlated moderately well with the FS ADC (R2 = 0.51). Conclusion LSDI gives reproducible ADC measurements in the lumbar discs, largely independent of b-value and signal-to-noise ratio (SNR) when used with noise correction and FS. J. Magn. Reson. Imaging 2005;21:482,488. © 2005 Wiley-Liss, Inc. [source] Reproducibility of jaw movements in patients with craniomandibular disordersJOURNAL OF ORAL REHABILITATION, Issue 11 2006M. STIESCH-SCHOLZ summary, It has never been investigated, if mandibular movements of patients with craniomandibular disorders (CMD) result in a lower reproducibility of dynamic functional parameters which are used for the individual articulator setting. The aim of the present study was to compare the reproducibility of electronically registered functional parameters in patients with CMD and in a control group. Dynamic functional parameters were recorded in 30 patients and 30 volunteers with a computerized ultrasound system (ARCUSdigma). The whole registration was performed three times during one session and three times at a second session 1 week later. The horizontal condylar inclination in the patient group gave a standard deviation of 2·17° ± 0·95°, indicating poorer reproducibility than in the volunteer group, for which the standard deviation was 1·37° ± 0·42°. The reproducibility of measurements of the Bennett angle was also poorer in the patient group than in the volunteer group, with standard deviations of 1·70° ± 0·62° and 1·22° ± 0·40°, respectively. The standard deviations calculated for determination of incisal inclination during laterotrusion was 3·02° ± 1·49° for patients and 2·30° ± 1·17° for volunteers. The standard deviations for incisal inclination during protrusion was 2·02° ± 0·95° for patients and 2·06° ± 1·82° for volunteers. The reproducibility of measurement of horizontal condylar inclination, Bennett angle and incisal inclination during laterotrusion therefore showed significantly lower reproducibility in the patient group than in the volunteer group (P < 0·05). The overall reproducibility of the measurements was nevertheless good in both groups, with standard deviations under 3·1°, so that an individual setting of an articulator seems useful even in patients with CMD. [source] Reproducibility of lateral excursive tooth contact in a semi-adjustable articulator depending on the type of lateral guidanceJOURNAL OF ORAL REHABILITATION, Issue 3 2005A. J. CARO summary, The purposes of this study were (i) to compare the reproducibility of lateral tooth contacts of casts mounted in a semi-adjustable articulator when condylar guidance was set by different methods and (ii) to assess the margin of error of the variations of condylar guidance without changing lateral tooth contacts, depending on the type of lateral guidance. In subjects with different types of lateral guidance, intraoral lateral tooth contacts identified with occlusal registration strips were compared with those identified by use of a semi-adjustable articulator, setting the condylar guidance in four different ways: using protrusive wax wafers, by axiography and by adding and subtracting 5° from the value of condylar guidance obtained by protrusive wax wafers. Tolerance to variations of condylar guidance without changing lateral tooth contacts was determined by increasing and decreasing the value of condylar guidance until lateral tooth contacts changed. Different ways of setting condylar guidance on a semi-adjustable articulator give rise to different values of condylar guidance in the same subject. The occlusal repercussions of these variations of condylar guidance values depend on the type of lateral guidance. Canine protection had the greatest tolerance to variations in the setting of condylar guidance without changing lateral occlusal contacts. [source] Measurement of the setting expansion of phosphate-bonded investment materials: Part II , An evaluation of the Casting-Ring Test at 10 laboratoriesJOURNAL OF ORAL REHABILITATION, Issue 7 2004C. H. Lloyd summary, The Casting-Ring Test has the potential to fulfil the requirement for a reliable ,Standard' test to measure the setting expansion of phosphate-bonded investment materials. The purpose of this study was to investigate the reproducibility of the measurements and the value that is produced at 10 test sites. The Casting-Ring Test apparatus, three phosphate-bonded investment products and one ring liner product were sent to the 10 participants, together with a detailed test protocol. Participants were asked to use their normal vacuum mixers. Reproducibility at individual sites was good. However, there were significant differences between test sites for the mean setting expansions, attributed to the range of vacuum mixers employed. From these results, the Casting-Ring Test appears to satisfy the requirements for adoption as an ISO standard test. The effect produced by different vacuum-mixer models would be manifest in any test. Not only does this have implications when determining the value of setting expansion for product information, but such a range of setting expansions will also be reproduced during production of moulds in commercial dental laboratory practice. However, for any specific product and vacuum-mixer combination, the setting expansion will be consistent and will not vary from mould to mould. [source] Combined oxygen and silicon isotope analysis of biogenic silica,JOURNAL OF QUATERNARY SCIENCE, Issue 4 2008Melanie J. Leng Abstract There is increasing interest in the use of biogenic silica O and Si isotope ratios to understand climate and environmental processes. Virtually all of the fairly substantial body of literature deals with either oxygen or silicon. This is partly because measurement of oxygen isotope composition is done using either vacuum dehydration, isotope exchange or stepped fluorination techniques, while increasingly researchers are turning to multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) for Si isotope analysis, even though Si isotope analysis can be done using fluorination methods used for the oxygen isotope measurements. Here we describe a procedure for simultaneous determination of isotopic abundances of oxygen and silicon from the same aliquot of biogenic silica. Pure silica is dissociated into O and Si compounds using a fluorination technique, in which reaction with bromine pentafluoride (BrF5) produces oxygen (O2, subsequently converted to CO2), silicon tetrafluoride (SiF4) and other fluorine by-products (e.g. BrF3). These compounds are cryogenically separated using cold traps. Yields for oxygen and silicon recovery are 70,80% for biogenic silica depending on the nature of the hydrous layer and 97,99% for pure quartz. Reproducibility of the oxygen isotopic composition is ca. 0.3, and silicon between 0.06,0.12,. © Natural Environment Research Council (NERC) copyright 2008. Reproduced with the permission of NERC. Published by John Wiley & Sons, Ltd. [source] A novel HS-SBSE system coupled with gas chromatography and mass spectrometry for the analysis of organochlorine pesticides in water samplesJOURNAL OF SEPARATION SCIENCE, JSS, Issue 20 2008Paula Grossi Abstract A methodology to analyze organochlorine pesticides (OCPs) in water samples has been accomplished by using headspace stir bar sorptive extraction (HS-SBSE). The bars were in house coated with a thick film of PDMS in order to properly work in the headspace mode. Sampling was done by a novel HS-SBSE system whereas the analysis was performed by capillary GC coupled mass spectrometric detection (HS-SBSE-GC-MS). The extraction optimization, using different experimental parameters has been established by a standard equilibrium time of 120 min at 85°C. A mixture of ACN/toluene as back extraction solvent promoted a good performance to remove the OCPs sorbed in the bar. Reproducibility between 2.1 and 14.8% and linearity between 0.96 and 1.0 were obtained for pesticides spiked in a linear range between 5 and 17 ng/g in water samples during the bar evaluation. [source] Reproducibility of the Italian ISQ method for quality classification of bread wheats: An evaluation by expert assessorsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 5 2007Giorgia Foca Abstract The great variety of different bakery products in Italy has led to the development of a method, the Synthetic Index of Quality (Indice Sintetico di Qualità, ISQ), for the classification of bread wheats in different quality categories. Based on chemical and rheological properties, each wheat sample is assigned to the most suitable class by an expert assessor. In many cases this procedure is not straightforward, making the class assignation uncertain, thus leading to the possibility of controversies during the trading phase. In the present study, in order to have a quantitative estimate of the validity and reliability of this procedure, a panel composed of nine expert assessors was utilised for the repeated evaluation of 100 samples of bread wheats of various qualities. The results suggest that the proposed approach can be used both to monitor the reliability of the single assessors, and to identify samples whose class assignation is reasonably indubitable, e.g. to be used for the development of automated classification methods. Moreover, the analysis of the most uncertain assignation cases can be useful in order to enhance the ISQ classification method itself. Copyright © 2007 Society of Chemical Industry [source] Reproducibility of Airway Responsiveness in Horses Using Flowmetric Plethysmography and Histamine BronchoprovocationJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 3 2009R. D. Nolen-Walston Background: Inflammatory airway disease has a high prevalence in horses, but is often a diagnostic challenge. Flowmetric plethysmography and histamine bronchoprovocation (FP/HBP) is a simple and effective tool for diagnosis, but reproducibility of these measurements made over time has not been established. Hypothesis: We hypothesize that the measurement of airway responsiveness in horses using FP/HBP is consistent over both short and long periods of time. Animals: Twenty-nine healthy adult horses from 2 university herds. Methods: In this prospective experimental study, airway responsiveness was determined in each horse at day 0 (baseline [BL]) with FP/ HBP, using PC35 (provocative concentration of histamine needed to increase ,flow by 35%) as a measure of airway responsiveness. Each horse was re-tested 1,4 weeks after BL (short-term [ST]) and again at 3,12 months after BL (long-term [LT]). Results: In the ST period, 23/27 (85%) of the horses had a PC35 that was within 1 doubling concentration of histamine of their BL value, with a mean change of 0.52 doubling concentrations (95% CI 0.26,0.79, range 0,2.06). For the LT data, 19/26 (73%) of horses were within 1 doubling concentration of their BL value, with a mean change of 0.81 doubling concentrations (95% CI 0.45,1.17, range 0.14,3.10). There was no significant difference in reproducibility between the 2 groups of subjects. Conclusions and Clinical Importance: Repeated measurements of airway responsiveness obtained with FP/HBP show acceptable reproducibility over time periods up to a year. However, caution must be used when testing horses when ambient air temperature is low. [source] Quantitative Assessment of Regional Right Ventricular Myocardial Velocities in Awake Dogs by Doppler Tissue Imaging: Repeatability, Reproducibility, Effect of Body Weight and Breed, and Comparison with Left Ventricular Myocardial VelocitiesJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 6 2005Valérie Chetboul Right ventricular myocardial (RVM) motion is poorly documented. The objective of this study was to determine the variability of RVM velocities by tissue Doppler imaging (TDI) in healthy dogs (study 1), to analyze RVM motion in a large healthy canine population (study 2), and to compare the results with those obtained for the left ventricular free wall. Six healthy Beagle Dogs were monitored in study 1, and 64 healthy dogs of 14 different breeds were monitored in study 2. Velocities were recorded in 2 segments (basal and apical) of the right and left myocardial walls. In study 1, 36 TDI examinations were performed for 4 days, whereas a single TDI examination was performed on each dog in study 2. All velocity profiles included 1 positive systolic wave and 2 negative diastolic waves. The lowest intraday and interday coefficient of variation values of the right TDI variables were observed at the base (3.5,16.1%). The variability of the right apical velocities was much higher, with most coefficient of variation values >15%. RVM velocities were higher in the basal than in the apical segments (P < .001) and were higher than the left velocities of the corresponding segment (P < .01). Body weight and breed had an effect on only a few right and left TDI variables. TDI provides a repeatable and reproducible method for evaluating basal RV function in the dog. These data also demonstrate the heterogeneity of the myocardial velocities between the left and the right ventricles and between the base and the apex. [source] Reproducibility and limitations of transient elastographyLIVER INTERNATIONAL, Issue 5 2009Mireen Friedrich-Rust No abstract is available for this article. [source] Normal cerebral perfusion measurements using arterial spin labeling: Reproducibility, stability, and age and gender effectsMAGNETIC RESONANCE IN MEDICINE, Issue 4 2004Laura M. Parkes Abstract Before meaningful conclusions can be drawn from clinical measures of cerebral blood perfusion, the precision of the measurement must be determined and set in the context of inter- and intrasubject sources of variability. This work establishes the reproducibility of perfusion measurements using the noninvasive MRI technique of continuous arterial spin labeling (CASL). Perfusion was measured in 34 healthy normal subjects. Intersubject variability was assessed, and age and gender contributions were estimated. Intersubject variation was found to be large, with up to 100% perfusion difference for subjects of the same age and gender. Repeated measurements in one subject showed that perfusion remains remarkably stable in the short term when compared with intersubject variation and the large capacity for perfusion change in the brain. A significant decrease in the ratio of gray-matter to white-matter perfusion was found with increasing age (0.79% per year (P < 0.0005)). This appears to be due mainly to a reduction in gray-matter perfusion, which was found to decrease by 0.45% per year (P = 0.04). Regional analysis suggested that the gray-matter age-related changes were predominantly localized in the frontal cortex. Whole-brain perfusion was 13% higher (P = 0.02) in females compared to males. Magn Reson Med 51:736,743, 2004. © 2004 Wiley-Liss, Inc. [source] Automatic segmentation of the brain and intracranial cerebrospinal fluid in T1 -weighted volume MRI scans of the head, and its application to serial cerebral and intracranial volumetryMAGNETIC RESONANCE IN MEDICINE, Issue 5 2003Louis Lemieux A new fully automatic algorithm for the segmentation of the brain and total intracranial cerebrospinal fluid (CSF) from T1 -weighted volume MRI scans of the head, called Exbrain v.2, is described. The algorithm was developed in the context of serial intracranial volumetry. A brain mask obtained using a previous version of the algorithm forms the basis of the CSF segmentation. Improved brain segmentation is then obtained by iterative tracking of the brain,CSF interface. Gray matter (GM), white matter (WM), and intracranial CSF volumes and probability maps are calculated based on a model of intensity probability distribution (IPD) that includes two partial volume classes: GM-CSF and GM-WM. Accuracy was assessed using the Montreal Neurological Institute's (MNI) digital phantom scan. Reproducibility was assessed using scan pairs from 24 controls and 10 patients with epilepsy. Segmentation overlap with the gold standard was 98% for the brain and 95%, 96%, and 97% for the GM, WM, and total intracranial contents, respectively; CSF overlap was 86%. In the controls, the Bland and Altman coefficient of reliability (CR) was 35.2 cm3 for the total brain volume (TBV) and 29.0 cm3 for the intracranial volume (ICV). Scan-matching reduced CR to 25.2 cm3 and 17.1 cm3 for the TBV and ICV, respectively. For the patients, similar CR values were obtained for the ICV. Magn Reson Med 49:872,884, 2003. © 2003 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||||||||||||||||||||