Significant Difference In Repeatability Research Articles

Agreement and repeatability of corneal tomography in healthy eyes using a new swept-source OCT, a rotating Scheimpflug camera, and a dual Scheimpflug-Placido system.

To investigate the accordance and repeatability of tomographic parameters measured by a new swept-source optical coherence tomographer (SS-OCT, ANTERION), a rotating Scheimpflug camera (RSC, Pentacam), and a dual Scheimpflug-Placido system (DSP, Galilei G6). Department of Ophthalmology of University of Hospital Carl Gustav Carus, Dresden, Germany. Prospective reliability analysis. Normal tomography was ensured by bilaterally evaluating appropriated parameters using RSC. All subjects received 3 consecutive measurements on each device by the same operator and in the uniform order RSC, SS-OCT, and DSP. Anterior (ACP) and posterior (PCP) corneal parameters such as flat and steep keratometry and corneal thickness were analyzed. Repeatability was assessed by using a coefficient of repeatability (CoR) and a coefficient of variation. Agreement between RSC and SS-OCT and between RSC and DSP were shown by Bland-Altman plots. This study included 30 randomly selected eyes of 30 healthy participants. CoR of ACP did not exceed 0.5 diopters. There were no statistically significant differences in repeatability of ACP obtained from the 3 devices (P > .05). For PCP and corneal thickness, there was statistically significant higher repeatability mostly found for SS-OCT as opposed to RSC and DSP (P < .05). For a wide range of analyzed parameters, there were large limits of agreement (95% LoA) found between the devices. The SS-OCT showed highly repeatable measurements in healthy subjects regarding anterior, posterior, and corneal thickness parameters. Repeatability of ACP did not differ between the devices. A mostly wide range of 95% LoA prevents interchangeability between the devices.

How Big is the Hole? Measuring Intra- and Inter-Individual Agreement in Macular Hole Size Measurements

ABSTRACT Purpose The size of a macular hole helps determine treatment planning and postoperative prognosis. The aim of this study was to examine intra- and inter-individual agreement in the measurement of full thickness macular hole (FTMH) size using optical coherence tomography (OCT) images. Methods Thirty OCT scans of FTMHs were reviewed by three vitreoretinal consultants and three vitreoretinal fellows. The FTMH size was recorded by each clinician independently and they repeated the measurements 3 weeks later. The repeatability of measurements was analysed using techniques of agreement measurement. Results The Coefficients of Repeatability (CR) for the intra-individual agreement were 46 µm, 73 µm and 60 µm for the consultant group and 44 µm, 60 µm and 57 µm for the fellow group. The Coefficients of Variation (CoV) of intra-individual repeatability were 3.8%, 5.9%, and 5.1% for the consultants and 3.5%, 5.2%, and 4.9% for the fellows. The CR for inter-individual agreement varied from 62 µm to 122 µm. There was no significant difference in repeatability of measurements between the consultant and the fellow groups (chi-squared, p = .95). Conclusions Manual OCT FTMH diameter measurements show poor intra- and inter-individual repeatability. Future work should aim to develop an automated method for measuring macular holes.

A photonumeric scale for the assessment of atrophic facial photodamage.

Photonumeric scales have consistently shown superiority over descriptive equivalents. They have the advantage of providing a consistent visual frame of reference by minimizing variability in perception and subjectivity. A photonumeric scale to assess hypertrophic facial photodamage already exists. However, there is currently no objective measure for atrophic facial photodamage. To address this, we have devised a nine-point photonumeric standardized scale. To design, test and validate a photonumeric scale for the assessment of atrophic facial photodamage against a descriptive scale for the same indication. A pool of 393 facial photographs (en face and 45° oblique) from 131 individuals with atrophic facial photodamage was created. Five photographic standards were selected and assigned grades zero through to eight, where zero is no photodamage and eight is severe atrophic photodamage, thus making a nine-point scale. Twenty photographs spanning the entire range of values were selected to test the scale. Testing was performed alongside a descriptive equivalent. A panel of 10 dermatologists, 10 nondermatology clinicians and 14 dermatology scientists marked the two scales; marking was repeated 1 week later. There was a significantly greater agreement between the graders using the photonumeric scale than the descriptive scale (kappa values 0·71 and 0·37 with standardized errors of 0·57 and 0·17, respectively) with no significant difference in repeatability between the two methods (P < 0·05). The study describes a new photonumeric scale for atrophic photodamage. This would be a useful adjunct in both the clinical and research settings.

Multiparametric Magnetic Resonance Imaging of the Prostate: Repeatability of Volume and Apparent Diffusion Coefficient Quantification.

The aim of this study was to evaluate the repeatability of a region of interest (ROI) volume and mean apparent diffusion coefficient (ADC) in standard-of-care 3 T multiparametric magnetic resonance imaging (mpMRI) of the prostate obtained with the use of endorectal coil. This prospective study was Health Insurance Portability and Accountability Act compliant, with institutional review board approval and written informed consent. Men with confirmed or suspected treatment-naive prostate cancer scheduled for mpMRI were offered a repeat mpMRI within 2 weeks. Regions of interest corresponding to the whole prostate gland, the entire peripheral zone (PZ), normal PZ, and suspected tumor ROI (tROI) on axial T2-weighted, dynamic contrast-enhanced subtract, and ADC images were annotated and assessed using Prostate Imaging Reporting and Data System (PI-RADS) v2. Repeatability of the ROI volume for each of the analyzed image types and mean ROI ADC was summarized with repeatability coefficient (RC) and RC%. A total of 189 subjects were approached to participate in the study. Of 40 patients that gave initial agreement, 15 men underwent 2 mpMRI examinations and completed the study. Peripheral zone tROIs were identified in 11 subjects. Tumor ROI volume was less than 0.5 mL in 8 of 11 subjects. PI-RADS categories were identical between baseline-repeat studies in 11/15 subjects and differed by 1 point in 4/15. Peripheral zone tROI volume RC (RC%) was 233 mm (71%) on axial T2-weighted, 422 mm (112%) on ADC, and 488 mm (119%) on dynamic contrast-enhanced subtract. Apparent diffusion coefficient ROI mean RC (RC%) were 447 × 10 mm/s (42%) in PZ tROI and 471 × 10 mm/s (30%) in normal PZ. Significant difference in repeatability of the tROI volume across series was observed (P < 0.005). The mean ADC RC% was lower than volume RC% for tROI ADC (P < 0.05). PI-RADS v2 overall assessment was highly repeatable. Multiparametric magnetic resonance imaging sequences differ in volume measurement repeatability. The mean tROI ADC is more repeatable compared with tROI volume in ADC. Repeatability of prostate ADC is comparable with that in other abdominal organs.

Extracranial Soft-Tissue Tumors: Repeatability of Apparent Diffusion Coefficient Estimates from Diffusion-weighted MR Imaging.

Purpose To assess the repeatability of apparent diffusion coefficient (ADC) estimates in extracranial soft-tissue diffusion-weighted magnetic resonance imaging across a wide range of imaging protocols and patient populations. Materials and Methods Nine prospective patient studies and one prospective volunteer study, performed between 2006 and 2016 with research ethics committee approval and written informed consent from each subject, were included in this single-institution study. A total of 141 tumors and healthy organs were imaged twice (interval between repeated examinations, 45 minutes to 10 days, depending the on study) to assess the repeatability of median and mean ADC estimates. The Levene test was used to determine whether ADC repeatability differed between studies. The Pearson linear correlation coefficient was used to assess correlation between coefficient of variation (CoV) and the year the study started, study size, and volumes of tumors and healthy organs. The repeatability of ADC estimates from small, medium, and large tumors and healthy organs was assessed irrespective of study, and the Levene test was used to determine whether ADC repeatability differed between these groups. Results CoV aggregated across all studies was 4.1% (range for each study, 1.7%-6.5%). No correlation was observed between CoV and the year the study started or study size. CoV was weakly correlated with volume (r = -0.5, P = .1). Repeatability was significantly different between small, medium, and large tumors (P < .05), with the lowest CoV (2.6%) for large tumors. There was a significant difference in repeatability between studies-a difference that did not persist after the study with the largest tumors was excluded. Conclusion ADC is a robust imaging metric with excellent repeatability in extracranial soft tissues across a wide range of tumor sites, sizes, patient populations, and imaging protocol variations. Online supplemental material is available for this article.

Does repeatable behaviour in the laboratory represent behaviour under natural conditions? A formal comparison in sea anemones

Animal personality studies rely on collecting repeated behavioural data either in the field or under laboratory conditions. Conditions in the field should be far less stable than controlled laboratory conditions, and hence represent a potential source of variation in behaviour. Here we report on the first experiment to our knowledge that formally compares the repeatability of identical behaviours in the laboratory and the field, and across the transition from laboratory to field. Using a design that controls for observation number we compared two groups of sea anemones, observed across two experimental phases, either (1) in the field followed by the laboratory or (2) in the laboratory only. We analysed differences in behaviour across a range of levels including repeatability and its between- and within-individual variance components. Although mean startle response durations varied between the laboratory and field, there was no significant difference in repeatability across situations. Within-individual variance differed between the two periods of the experiment for animals observed only in the laboratory but this effect was not present for those that transitioned from field to laboratory. Furthermore, the rank order of individual responses was stable for animals observed only in the laboratory but changed for those that transitioned from field to laboratory. These results show that although repeatability estimates in the laboratory can yield results like those obtained in the field, the underlying components of consistent variation in behaviour might be influenced by an interaction between prior experiences and the current situation in which the animals are observed.

Repeatability of Quantitative Whole-Body 18F-FDG PET/CT Uptake Measures as Function of Uptake Interval and Lesion Selection in Non-Small Cell Lung Cancer Patients.

Change in (18)F-FDG uptake may predict response to anticancer treatment. The PERCIST suggest a threshold of 30% change in SUV to define partial response and progressive disease. Evidence underlying these thresholds consists of mixed stand-alone PET and PET/CT data with variable uptake intervals and no consensus on the number of lesions to be assessed. Additionally, there is increasing interest in alternative (18)F-FDG uptake measures such as metabolically active tumor volume and total lesion glycolysis (TLG). The aim of this study was to comprehensively investigate the repeatability of various quantitative whole-body (18)F-FDG metrics in non-small cell lung cancer (NSCLC) patients as a function of tracer uptake interval and lesion selection strategies. Eleven NSCLC patients, with at least 1 intrathoracic lesion 3 cm or greater, underwent double baseline whole-body (18)F-FDG PET/CT scans at 60 and 90 min after injection within 3 d. All (18)F-FDG-avid tumors were delineated with an 50% threshold of SUVpeak adapted for local background. SUVmax, SUVmean, SUVpeak, TLG, metabolically active tumor volume, and tumor-to-blood and -liver ratios were evaluated, as well as the influence of lesion selection and 2 methods for correction of uptake time differences. The best repeatability was found using the SUV metrics of the averaged PERCIST target lesions (repeatability coefficients < 10%). The correlation between test and retest scans was strong for all uptake measures at either uptake interval (intraclass correlation coefficient > 0.97 and R(2) > 0.98). There were no significant differences in repeatability between data obtained 60 and 90 min after injection. When only PERCIST-defined target lesions were included (n = 34), repeatability improved for all uptake values. Normalization to liver or blood uptake or glucose correction did not improve repeatability. However, after correction for uptake time the correlation of SUV measures and TLG between the 60- and 90-min data significantly improved without affecting test-retest performance. This study suggests that a 15% change of SUVmean/SUVpeak at 60 min after injection can be used to assess response in advanced NSCLC patients if up to 5 PERCIST target lesions are assessed. Lower thresholds could be used in averaged PERCIST target lesions (<10%).

Fat quantification in skeletal muscle using multigradient-echo imaging: Comparison of fat and water references.

To investigate the precision, accuracy, and repeatability of water/fat imaging-based fat quantification in muscle tissue using a large flip angle (FA) and a fat reference for the calculation of the proton density fat fraction (FF). Comparison is made to a small FA water reference approach. An Intralipid phantom and both forearms of six patients suffering from lymphedema and 10 healthy volunteers were investigated at 1.5T. Two multigradient-echo sequences with eight echo times and FAs of 10° and 85° were acquired. For healthy volunteers, the acquisition of the right arm was performed twice with repositioning. From each set, water reference FF and fat reference FF images were reconstructed and the average FF and the standard deviation were calculated within the subfascial compartment. The small FA water reference was considered the reference standard. A high agreement was found between the small FA water reference and large FA fat reference methods (FF bias = 0.31%). In this study, the large FA fat reference approach also resulted in higher precision (38% smaller FF standard deviation in homogenous muscle tissue), but no significant difference in repeatability between the various methods was detected (coefficient of repeatability of small FA water reference approach 0.41%). The precision of fat quantification in muscle tissue can be increased with maintained accuracy using a larger flip angle, if a fat reference instead of a water reference is used.

The Repeatability of Best Corrected Acuity in Normal and Amblyopic Children 4 to 12 Years of Age

The main purpose of this work was to measure repeatability of line-by-line logMAR (logarithm of the minimum angle of resolution) acuity in normal and amblyopic children, while adequately controlling for optical defocus. The Lea Symbols Chart is a constant-crowding, equal-logMAR increment chart similar in design to the Early Treatment Diabetes Retinopathy Study [ETDRS] chart. LogMAR visual acuity was tested twice in each eye of 32 amblyopic and 11 normal children. Each test commenced with screening in which one of the three central symbols was chosen for identification starting with the 1.0- or 0.9-logMAR line, progressing to every second line until incorrect identification occurred. Symbol-by-symbol presentation then commenced at the logMAR line containing the last correctly identified symbol. The threshold was recorded as the last logMAR line where four of four or four of five correct responses occurred (i.e., line-by-line scoring). Retesting by the same examiner was identical and occurred within the same session. There was no significant difference in repeatability among normal, fellow, or amblyopic eyes. The difference between test and retest thresholds lay between +/-0.10 logMAR in 93% of eyes. The 95% limits of agreement for the difference was +/-0.18 logMAR. Repeatability in eyes tested first did not differ from that in those tested second in either the normal or amblyopic groups. In the age-group tested, the line-by-line method of threshold scoring compares favorably with previous reports of both line-by-line and interpolated threshold scoring. There was no clinically meaningful difference in repeatability between the normal and amblyopic children tested.

Falling Weight Deflectometer Correlation

The falling weight deflectometer (FWD) is commonly used to perform project-and network-level structural evaluations. Some highway agencies perform network-level FWD testing as a part of their pavement management systems to assess in situ structural capacity, remaining service life, and current rehabilitation needs. Through prediction models, future condition and needs are also estimated. In contrast, project-level FWD testing is typically performed as part of the rehabilitation design process. Calibrated FWD equipment provides repeatable data for a pavement section (i.e., data obtained with the same unit, at the same location, and under similar conditions). However, different FWD devices manufactured by the same or different manufacturers do not necessarily provide similar deflection basins when they test the same section, even if they are calibrated. This paper summarizes the results of a study performed for the New Jersey Department of Transportation to assess the differences among the FWD devices available in New Jersey and to correlate the results obtained with the different devices. Two rounds of testing were performed on flexible and rigid pavement sections located in the FAA William J. Hughes Technical Center in Atlantic City. The first testing cycle was performed in November 2002, and the second was performed in May 2004. The analysis results indicate that significant differences in repeatability and reproducibility may exist between different FWD devices.

Falling Weight Deflectometer Correlation

The falling weight deflectometer (FWD) is commonly used to perform project- and network-level structural evaluations. Some highway agencies perform network-level FWD testing as a part of their pavement management systems to assess in situ structural capacity, remaining service life, and current rehabilitation needs. Through prediction models, future condition and needs are also estimated. In contrast, project-level FWD testing is typically performed as part of the rehabilitation design process. Calibrated FWD equipment provides repeatable data for a pavement section (i.e., data obtained with the same unit, at the same location, and under similar conditions). However, different FWD devices manufactured by the same or different manufacturers do not necessarily provide similar deflection basins when they test the same section, even if they are calibrated. This paper summarizes the results of a study performed for the New Jersey Department of Transportation to assess the differences among the FWD devices available in New Jersey and to correlate the results obtained with the different devices. Two rounds of testing were performed on flexible and rigid pavement sections located in the FAA William J. Hughes Technical Center in Atlantic City. The first testing cycle was performed in November 2002, and the second was performed in May 2004. The analysis results indicate that significant differences in repeatability and reproducibility may exist between different FWD devices.

Test-retest reliability of pure-tone thresholds from 0.5 to 16 kHz using Sennheiser HDA 200 and Etymotic Research ER-2 earphones.

The purposes of the study were: (1) To evaluate the intrasession test-retest reliability of pure-tone thresholds measured in the 0.5-16 kHz frequency range for a group of otologically healthy subjects using Sennheiser HDA 200 circumaural and Etymotic Research ER-2 insert earphones and (2) to compare the data with existing criteria of significant threshold shifts related to ototoxicity and noise-induced hearing loss. Auditory thresholds in the frequency range from 0.5 to 6 kHz and in the extended high-frequency range from 8 to 16 kHz were measured in one ear of 138 otologically healthy subjects (77 women, 61 men; mean age, 24.4 yr; range, 12-51 yr) using HDA 200 and ER-2 earphones. For each subject, measurements of thresholds were obtained twice for both transducers during the same test session. For analysis, the extended high-frequency range from 8 to 16 kHz was subdivided into 8 to 12.5 and 14 to 16 kHz ranges. Data for each frequency and frequency range were analyzed separately. There were no significant differences in repeatability for the two transducer types for all frequency ranges. The intrasession variability increased slightly, but significantly, as frequency increased with the greatest amount of variability in the 14 to 16 kHz range. Analyzing each individual frequency, variability was increased particularly at 16 kHz. At each individual frequency and for both transducer types, intrasession test-retest repeatability from 0.5 to 6 kHz and 8 to 16 kHz was within 10 dB for >99% and >94% of measurements, respectively. The results indicated a false-positive rate of <3% in reference to the criteria for cochleotoxicity for both transducer types. In reference to the Occupational Safety and Health Administration Standard Threshold Shift criteria for noise-induced hazards, the results showed a minor false-positive rate of <1% for the HDA 200. Repeatability was similar for both transducer types. Intrasession test-retest repeatability from 0.5 to 12.5 kHz at each individual frequency including the frequency range susceptible to noise-induced hearing loss was excellent for both transducers. Repeatability was slightly, but significantly poorer in the frequency range from 14 to 16 kHz compared with the frequency ranges from 0.5 to 6 or 8 to 12.5 kHz. Measurements in the extended high-frequency range from 8 to 14 kHz, but not up to 16 kHz, may be recommended for monitoring purposes.

Comparison of post-stress ejection fraction and relative left ventricular volumes by automatic analysis of gated myocardial perfusion single-photon emission computed tomography acquired in the supine and prone positions

We have previously described an automatic method for measuring left ventricular ejection fraction (LVEF) for myocardial perfusion single-photon emission computed tomography (SPECT). The repeatability of this method has not been previously described. This study compares LVEF and relative end-systolic and end-diastolic volumes assessed from myocardial perfusion SPECT by our automatic method in 180 consecutive patients undergoing gated myocardial perfusion SPECT with injection of 99mTc-labeled sestamibi in whom the acquisitions were performed sequentially in supine and prone positions. The algorithm operated completely automatically in the prone and supine positions in 178 of the 180 patients. Very high correlations were observed for LVEF (r = 0.93), relative left ventricular end-systolic volume (r = 0.98), and relative left ventricular end-diastolic volume (r = 0.97). The mean paired absolute difference between LVEFs in the prone and supine position was 3.8+/-3.2, for left ventricular end-systolic volume was 4.9+/-4.8 ml, and for left ventricular end-diastolic volume was 7.4+/-6.7 ml. When patients were classified by the extent and severity of stress perfusion defect, there was no significant difference in repeatability for the measurements in any category. Our algorithm for automatic quantification of LVEF and relative end-systolic and end-diastolic volumes from gated 99mTc sestamibi myocardial perfusion SPECT is repeatable. When performed in the prone position, values of ejection fractions and ventricular volumes are essentially identical to those obtained in the supine position.

Reproducibility, Repeatability, and Degree of Expertise Required to Assess Body Condition Score in Beef Cattle

AbstractNinety-eight Hereford × Angus beef cows were used to determine reproducibility (the correlation between an animal’s score by one technician and its score by a different technician), repeatability (the correlation between an animal’s score on one occasion and its score by the same technician on another occasion), and degree of expertise required to assess body condition. Body condition score (BCS) was determined by using a nine-point scale in which 1 represents an emaciated cow and 9 an obese cow. Three groups of technicians with different degrees of expertise scored the cows. Each technician scored the cows at a second time, later in the same day Group 1 (Gl) consisted of four technicians with at least 2yr of experience in using the BCS system. Group 2 (G2) was five technicians that were familiar with cattle but they had no previous experience scoring cows and were trained the day before the experiment as to how to score the animals by a member of Gl. Group 3 (G3) consisted of four technicians with no experience with cattle and they were simply instructed to give the cows a score between 2 and 8. Reproducibility was 0.65a, 0.42b, and 0.50ab, for Gl, G2, and G3, respectively (P<0.05), and was less than repeatability (0.83a, 0.68b, and 0.59b, for Gl, G2, and G3, respectively; P<0.05), indicating that periodical training of technicians is needed to standardize the system. In Gl, technicians disagreed on the BCS of a cow by more than 1 unit in only 4% of the animals, suggesting that the nine-point scale is a precise system to evaluate cows within 1 unit of BCS. The significant difference in repeatability and reproducibility between G2 and Gl suggests that more than one training session is needed to learn how to assess BCS.

A Photonumeric Scale for the Assessment of Cutaneous Photodamage

The assessment of the severity of cutaneous photodamage and its response to treatment is an impractical consideration for most practitioners without extensive experience or recourse to high-quality, standardized, baseline photographs. To address this problem, a nine-point photonumeric standard scale was developed using photographs of subjects representing grades of photodamage from none to severe. This scale was formally tested in a side-by-side comparison with a conventional and widely used written descriptive scale. A panel of seven graders used both scales to score two sets of 25 photographs of photodamaged individuals, and the intergrader agreement and repeatability for the scales were calculated. The photonumeric scale demonstrated significantly greater agreement between graders than did the descriptive scale (chance-corrected agreements of 0.31 and 0.11, respectively, P less than .0001) with no significant difference in repeatability between the two methods. This study demonstrates that the photonumeric standard scale is superior to existing methodology in the accurate assessment of cutaneous photodamage and would be a useful adjunct to studies of the efficacy of skin repair agents for this indication.

Comparison of two systems for sample preparation and injection by dynamic headspace GC analysis

AbstractThe performance of two commercially available systems employing dynamic headspace techniques for collection, enrichment, and injection of volatile compounds has been compared by GC analysis of test mixtures and dairy products. For technical reasons, it has not been possible to crate identical sorbent materials for both kinds of trap were not available, the most similar adsorbent available were chosen. The total quantity of volatile compounds from a test mixture at the column head was calculated using a theoretical model which enables comparable working conditions to be obtained. Under these circumstances special attention was paid to the repeatability of the data obtained from a test mixture in order to ensure reliable results in quantitative analysis. Significant differences in repeatability between the two systems seemed to originate from their distinctly different technical designs.A qualitative comparison of the systems has been performed using a sample of Swiss cheese. On the basis of the results obtained the systems have been dedicated to different applications in the laboratory of the FAM.

A technique for the serial extraction treatment of Class II and deep-bite malocclusion

2. The Myo-Monitor technique was the least repeatable or most variable technique for recording maxillomandibular relationship. 3. There was no significant difference in repeatability between the bilateral manipulation technique and the leaf gauge technique for taking maxillomandibular records. 4. There was a large significant difference in repeatability between the bilateral manipulation technique and the Myo-Monitor technique for taking maxillomandibular records.