Multicenter Repeatability and Reproducibility of MR Fingerprinting in Phantoms and in Prostatic Tissue
Wei‐Ching LoLeonardo Kayat BittencourtAnanya PandaYun JiangJunichi TokudaRavi T. SeethamrajuClare M. TempanyVerena Carola ObmannKatherine Landau WrightMark A. GriswoldNicole SeiberlichVikas Gulani
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To evaluate multicenter repeatability and reproducibility of T1 and T2 maps generated using MR fingerprinting (MRF) in the International Society for Magnetic Resonance in Medicine/National Institute of Standards and Technology MRI system phantom and in prostatic tissues.MRF experiments were performed on 5 different 3 Tesla MRI scanners at 3 different institutions: University Hospitals Cleveland Medical Center (Cleveland, OH), Brigham and Women's Hospital (Boston, MA) in the United States, and Diagnosticos da America (Rio de Janeiro, RJ) in Brazil. Raw MRF data were reconstructed using a Gadgetron-based MRF online reconstruction pipeline to yield quantitative T1 and T2 maps. The repeatability of T1 and T2 values over 6 measurements in the International Society for Magnetic Resonance in Medicine/National Institute of Standards and Technology MRI system phantom was assessed to demonstrate intrascanner variation. The reproducibility between the 4 clinical scanners was assessed to demonstrate interscanner variation. The same-day test-retest normal prostate mean T1 and T2 values from peripheral zone and transitional zone were also compared using the intraclass correlation coefficient and Bland-Altman analysis.The intrascanner variation of values measured using MRF was less than 2% for T1 and 4.7% for T2 for relaxation values, within the range of 307.7 to 2360 ms for T1 and 19.1 to 248.5 ms for T2 . Interscanner measurements showed that the T1 variation was less than 4.9%, and T2 variation was less than 8.1% between multicenter scanners. Both T1 and T2 values in in vivo prostatic tissue demonstrated high test-retest reliability (intraclass correlation coefficient > 0.92) and strong linear correlation (R2 > 0.840).Prostate MRF measurements of T1 and T2 are repeatable and reproducible between MRI scanners at different centers on different continents for the above measurement ranges.Keywords:
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This report describes, and gives the results of, an experiment designed to study the reproducibility and repeatability of the polished-stone value (PSV) determination when carried out according to the procedure given in BS 812 : 1967. Repeatability and reproducibility estimates were obtained from analyses of: (A) measured test results, and (B) test results 'corrected' by a factor based on the values obtained on Enderby control specimens. The analyses showed that the repeatability and reproducibility estimates on the measured test results for a single measurement were 4.9 and 6.0 units respectively, but for the 'corrected' test results both estimates were reduced to 4.2 units. These results confirmed the value (six units) for the reproducibility of the test which is quoted in the current edition of BS 812, but showed that the incorporation of a 'correction' technique into the procedures would appreciably improve its precision.
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The working sheet and computing formula were prepared by Excel for laboratories to calculate repeatability and reproducibility of monitoring method.It solved the exclusion and deletion of experimental data in some laboratories.The principle of statistics method depended on Accuracy(trueness and precision)of measurement methods and results Part 2:Basic method for the determination of repeatability and reproducibility of a standard measurement method(GB/T 6379.2-2004).
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To determine repeatability and reproducibility of A-scan biometry quantitative findings in order to uniformly evaluate lenticular cataract changes.Seventeen eyes from seventeen cataract patients were examined by three (trainee ophthalmologists). Results (ratio of mean internal lens spikes height/lens anterior surface spike height) were compared using coefficient of variation (CV), repeatability coefficient (CR), and intraclass correlation coefficients (ICC).Intra-observer consistency was CV = 0.36, CR = 0.49, and ICC = 0.778 for the first operator; CV = 0.33, CR = 0.52, and ICC = 0.642 for the second operator; and CV = 0.32, CR = 0.53, and ICC = 0.567 for the third operator. Concerning inter-observer agreement: CV (in 6 of 7 eyes) was > 8%, CR was > 0.21, and intraclass correlation coefficient for all eyes was < 0.81.Regarding repeatability and reproducibility, although there is a tendency for statistical significance, variability of the results does not allow the use of the method as a complementary clinical tool for comparing results. Standardization of this procedure, in order to achieve higher test reliability, might be the aim of relevant future studies, although there are a number of points that have to be addressed.
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Objectives: To determine and compare the repeatability and reproducibility of anterior scleral parameters measured by the corneoscleral profile (CSP) module of Pentacam in keratoconus (KC) and control eyes. Methods: This is a prospective observational study. Thirty KC participants (30 eyes) and 24 control participants (24 eyes) were examined three times using the CSP. Sagittal height mean (SHM), sagittal height astigmatism (SHA), and mean bulbar slope (BSM) were measured in 12 mm and 16 mm chord lengths. The repeatability and reproducibility of these measurements were also assessed. Coefficients of variation (CoV), intraclass correlation coefficient (ICC), coefficient of repeatability (CoR1), and coefficient of reproducibility (CoR2) were adopted to assess the reliability. Results: In the KC and control groups, SHM showed high repeatability and reproducibility (coefficients of variation [CoVs]≤0.96%, intraclass correlation coefficient [ICCs]≥0.97), and SHM of control eyes showed higher repeatability and reproducibility than that of KC eyes at 12 mm chord length (KC group, CoRs ranged from 35.56 μm to 43.52 μm, control group, ranged from 23.50 μm to 30.31 μm) and 16 mm chord length (KC group, CoRs ranged from 79.54 μm to 81.58 μm, control group, ranged from 48.25 μm to 66.10 μm). Mean bulbar slope also showed high repeatability and reproducibility (CoVs≤3.65%, CoRs≤2.64). Furthermore, the SHA of control eyes showed higher repeatability and reproducibility when compared with KC eyes (control group: CoVs≤29.95%, KC group: CoVs≥32.67%). Conclusions: Keratoconus and control eyes demonstrated high repeatability and reproducibility when using CSP measurements, which may prove helpful in fitting contact lenses.
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The paper deals with the influence of interactions between parts and appraisers on the results of the analysis of repeatability and reproducibility of the measurement system. The appropriate interactions have been created by simulated changes of selected values measured within the framework of real gauge repeatability and reproducibility study and evaluation was performed using average and range method and analysis of variance (ANOVA). Effects of changes type and size on the results of the analysis (%EV – repeatability; %AV – reproducibility; %INT – interaction between operators and parts; %GRR – gauge repeatability and reproducibility; ndc – number of distinct categories) are compared and mechanisms of these effects are analysed.
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The aim of this study was to evaluate repeatability and reproducibility of newly calculated biomechanical parameters of the cornea, developed by our research group.One eye from each of the 23 healthy subjects was measured three times consecutively, three times at different daytimes and on three different days. The within-subject standard deviation and coefficient of variation, as well as the intraclass correlation coefficient, were calculated for every parameter in each group.Excellent repeatability and reproducibility (coefficient of variation < 5%, intraclass correlation coefficient > 0.75) was found for corrected values measured at A1, HC, and A2 time points (2nd A2 Time, 2nd A1 Time, 2nd HC Time, 2nd HC Def Amp and 2nd A1 Def Amp). Corneal-specific stiffness parameters, which showed good repeatability and reliability, were DA_cor (coefficient of variation = 4.02%, intraclass correlation coefficient = 0.919), KcLinear (coefficient of variation = 4.03%, intraclass correlation coefficient = 0.895), areaForceCornea (coefficient of variation = 3.34%, intraclass correlation coefficient = 0.853) and E2 (coefficient of variation = 4.1%, intraclass correlation coefficient = 0.78). Overall, most parameters fell into the category of good reliability (high intraclass correlation coefficient) and poor reproducibility (low coefficient of variation), including all the parameters describing extraocular deformation (DA_ext, AEPvED, AUC EDef, areaForceExtra, Kg and μg). Comparing the coefficient of variation values for intrasession, intersession and daytime measurements, there were no indices for diurnal changes.Most parameters showed good repeatability and reliability. The extraocular stiffness parameters showed poor reproducibility. KcLinear can serve as a very reliable and repeatable indicator of corneal stiffness.
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Repeatability and reproducibility estimates of standard analysis were used to determine the uncertainty for lead content in copper,lead and zinc ores,by the EDTA volumetric method.Excesses in laboratory bias and repeatability were examined by 7 different laboratories collaborating for this experiment.It was determined that the measurement uncertainty relates to the accuracy of reproducibility when bias and precision are the dominant factors.This method proved to be efficient and effective by employing standards in collaboration experiments.
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Few studies assess repeatability and reproducibility in registers of resonance frequency analysis (a value of dental implant stability).Few studies assess repeatability and reproducibility in resonance frequency analyses (implant stability evaluation). This study is aimed at assessing reliability (repeatabilty and reproducibility) in the Osstell Mentor® system using the intraclass correlation coefficient (ICC) as the statistical method.ISQ measurements of RFA were carried out by means of the Osstell Mentor® instrument in 58 implants in 19 patients. Six measurements were performed on each implant by means of two different Smart-Pegs (I and II). Three consecutive measurements were registered with each transducer.Average ISQ varied from 72.43 to 72.60 and 73.26 in the first, second and third measurements, respectively with the SamrtPeg I and from 72.98 to 73.26 and 73.74 in the first, second and third measurements, respectively with the SamrtPeg II . Exactly equal values were observed in 10.43 and 12.1% of the cases with Smart-Pegs I and II, respectively. The intraclass correlation coefficient was 0.96 and 0.96 for Smart Pegs I and II, respectively. Repeatability and reproducibility was 0.97 for both Smart-Pegs I and II.The RFA system contributed by Osstell Mentor® renders almost perfect reproducibility and repeatability, as proven by statistical analysis carried out by means of ICC with 95% confidence level. This instrument contributes highly reliable RFA measurements in dental implants.
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Abstract To identify robust and reproducible methods of cerebellar morphometry that can be used in future large-scale structural MRI studies, we investigated the replicability, repeatability, and longterm reproducibility of three fully-automated software tools: FreeSurfer, CERES, and ACAPULCO. Replicability was defined as computational replicability, determined by comparing two analyses of the same high-resolution MRI data set performed with identical analysis software and computer hardware. Repeatability was determined by comparing the analyses of two MRI scans of the same participant taken during two independent MRI sessions on the same day for the Kirby-21 study. Long-term reproducibility was assessed by analyzing two MRI scans of the same participant in the longitudinal OASIS-2 study. We determined percent difference, the image intraclass correlation coefficient, the coefficient of variation, and the intraclass correlation coefficient between two analyses. Our results show that CERES and ACAPULCO use stochastic algorithms that result in surprisingly high differences between identical analyses for ACAPULCO and small differences for CERES. Changes between two consecutive scans from the Kirby-21 study were less than ±5% in most cases for FreeSurfer and CERES (i.e., demonstrating high repeatability). As expected, long-term reproducibility was lower than repeatability for all software tools. In summary, CERES is an accurate, as demonstrated before, and reproducible tool for fully-automated segmentation and parcellation of the cerebellum. We conclude with recommendations for the assessment of replicability, repeatability, and longterm reproducibility in future studies on cerebellar structure.
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