SEARCH · PubMed Health

Results for “Reproducibility”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 379 records · Page 21Linked to original sources

PubMed2001

Reproducibility of QT parameters derived from 24-hour ambulatory ECG recordings in healthy subjects.

AIM: To estimate the reproducibility of QT parameters derived from 24-hour ambulatory ECG recordings. METHOD: Ten healthy volunteers aged 25 to 41 years participated. In two 24-hour ambulatory ECG recordings obtained 1 day apart, the QT interval was measured manually at stable heart rates in approximately 16 periods during daytime and 6 periods during nighttime. The association between the QT and RR interval was described by linear regression for day and nighttime separately and the following QT parameters were calculated: the QT interval at heart rate 60 beats/min during daytime (QT(60)day), slope(day), slope(night), and the difference in QT(60) between day and nighttime (DeltaQT(60)). The QT parameters were assessed four times for each participant to discriminate method inaccuracy from day to day variation. The reproducibility was estimated as the coefficient of repeatability, the relative error, and the ratio between within-subject variability and between-subject variability. RESULTS: The coefficient of repeatability, the relative error and the ratio, respectively, were 19 ms, 1.8% and 0.5 for QT(60)day, 0.076, 21% and 0.68 for slope(day), 0.116, 43% and 1.37 for slope(night), and 37 ms, 325% and 1.19 for DeltaQT(60) when estimating the overall day to day reproducibility. Inaccuracy of QT measurement accounted for approximately 40% of this variation, whereas the error caused by selecting segments was small. CONCLUSION: QT(60)day has a high reproducibility and may with advantage replace the conventional QT interval measured on a resting ECG. To assess QT dynamics, the slope of the regression line during daytime is suitable and the short term reproducibility acceptable for clinical trials. Regarding slope(night) and DeltaQT(60), the variation is high and the parameters should be used with caution.

Adult↗

PubMed2005

Reproducibility of multichannel intraluminal electrical impedance monitoring of gastroesophageal reflux.

OBJECTIVE: Esophageal impedance measurement is a novel method for gastroesophageal reflux monitoring. Reproducibility is an important aspect of every biomedical test. The aim of this study was therefore to asses the reproducibility of gastroesophageal reflux monitoring using impedance measurements. METHODS: Impedance and pH signals were recorded in 20 healthy volunteers during 90-min postprandial periods on two separate days. Hourly rates of gas, liquid, and mixed gas-liquid reflux episodes were measured in each recording period as well as percentage of time with pH < 4 and rate of acid reflux episodes. As a quantitative description of inter- and intraindividual variation for each variable, the mean percentage of covariation (100 x SD/mean: %COV) was calculated. As a second measure for reproducibility, Kendall's coefficients of concordance (W values) were calculated. RESULTS: For all variables, interindividual %COV was at least 50% higher than intraindividual %COV. Statistically significant concordances were found for gas reflux (W = 0.81, p= 0.04) and mixed reflux (W = 0.85, p= 0.03) while concordance for liquid reflux tended to be significant (W = 0.75, p= 0.08). This was comparable to the reproducibility of the number of acid reflux episodes and percentage of time with pH < 4 (W = 0.78, p= 0.05 and W = 0.88, p= 0.02, respectively). CONCLUSIONS: Postprandial gastroesophageal reflux data assessed with impedance monitoring are as reproducible as assessed with pH monitoring.

Adult↗

PubMed2004

Periodontal repair in dogs: examiner reproducibility in the supraalveolar periodontal defect model.

BACKGROUND: Histometric assessments are routinely used to evaluate biologic events ascertained in histologic sections acquired from animal and human studies. The objective of this study was to evaluate the intra- and inter-examiner reproducibility of histometric assessments in the supraalveolar periodontal defect model. METHODS: Histometric analysis using incandescent and polarized light microscopy, an attached digital camera system, and a PC-based image analysis system including a custom program for the supraalveolar periodontal defect model was performed on histologic sections acquired from one jaw quadrant in each of 12 dogs. The animals had received an experimental protocol including implantation of a coral biomaterial and guided tissue regeneration (GTR) barrier devices, and were evaluated following a 4-week healing interval. Histometric parameters were recorded and repeated within a 3-month interval by two examiners following brief training. Intra- and inter-examiner reproducibility was assessed using the intra-class correlation coefficient (ICC). RESULTS: Most parameters showed high intra-examiner ICCs. Parameters including defect height, connective tissue repair, bone regeneration (height/area), formation of a junctional epithelium, positioning of the GTR device, ankylosis, root resorption, and defect area yielded an ICC> or 0..9. The ICCs for bone density and biomaterial density were somewhat lower (0.8 and 0.7, respectively). The inter-examiner reproducibility was somewhat lower compared to the intra-examiner reproducibility. Nevertheless, the ICCs were generally high (ICC range: 0.6-0.9). CONCLUSIONS: Histometric evaluations in the supraalveolar periodontal defect model yield highly reproducible results, in particular when a single examiner performs the histometric measurements, even when the examiner was exposed to limited training.

Animals↗

PubMed1999

Reproducibility of irritant patch test reactions to sodium lauryl sulfate in a double-blind placebo-controlled randomized study using clinical scoring. Results from a study group of the German Contact Dermatitis Research Group (Deutsche Kontaktallergie-Gruppe, DKG).

Reading of doubtful patch test reactions can be improved by comparing them to defined negative, allergic and irritant controls. For the latter, an irritant patch test is needed that gives sufficiently reproducible results. In our double-blind, placebo-controlled, randomized study, we have analysed the synchronous reproducibility of patch tests with 0%, 0.0625%, 0.125%, 0.25%, 0.5% and 1.0% sodium lauryl sulfate (SLS). Tests and readings were done according to ESCD guidelines. 139 patients (75 women, 64 men) 18 to 77 years old were tested. The % of positive patients as well as the % of reproducible positive reactions increased with rising concentrations of SLS to a maximum of approximately 90% and 85%, respectively, with 1% SLS. Time courses of reactions were also related to the concentration of SLS: with 1% SLS, plateau-type time courses were most common (65%), followed by decrescendo- (23%) and crescendo-type reactions (12%). With 1% SLS, very similar mild to moderate reactions were obtained on days 2 and 3. The reaction threshold and reproducibility of tests were not related to age and sex of patients or to their own assessment of skin irritability. We conclude that 1% SLS is appropriate for an irritant patch test that gives sufficiently reproducible results.

Adolescent↗

PubMed2006

Reproducibility and relationship of single-joint strength vs multi-joint strength and power in aging individuals.

INTRODUCTION: Reliable and sensitive muscle strength/power assessments are essential when evaluating age-related and/or training-induced changes in maximal strength and power. AIM: To investigate the reproducibility and inter-relationship of single-joint isokinetic/isometric leg muscle strength vs multi-joint mechanical muscle function during counter-movement jump (CMJ) in moderately trained aging individuals (age 72.3+/-6.6). RESULTS: The within-subject coefficient of variation (CV(w-s)) for the single-joint test showed good reproducibility (<10%) for quadriceps and hamstring strength (except for hamstring isometric). Plantar flexion demonstrated good to moderate reproducibility (CV(w-s) range: 10.4-17.2%). Excellent to good CV(w-s) (<10%) was observed for all concentric CMJ parameters, except for plantar flexor mean work (CV(w-s)=13%). Eccentric CMJ parameters demonstrated good to moderate reproducibility (CV(w-s) range: 8.1-18.2%). Isokinetic and isometric quadriceps, hamstring and plantar flexor single-joint strength measurements were found to correlate with several CMJ parameters. CONCLUSION: Single-joint and multi-joint strength and power assessment tests of the lower limbs appear to be reproducible in aging individuals. Furthermore, associations between single-joint strength and multi-joint CMJ power and force variables exist. To evaluate functional capacity in elderly people further investigations must be carried out to identify specific power/strength parameters that are most tightly linked to functional performance.

Aging↗

PubMed2002

Reproducibility of mammary gland structure during repeat setups in a supine position.

PURPOSE: In breast conserving therapy, complete excision of the tumor with an acceptable cosmetic outcome depends on accurate localization in terms of both the position of the lesion and its extent. We hypothesize that preoperative contrast-enhanced magnetic resonance (MR) imaging of the patient in a supine position may be used for accurate tumor localization and marking of its extent immediately prior to surgery. Our aims in this study are to assess the reproducibility of mammary gland structure during repeat setups in a supine position, to evaluate the effect of a breast immobilization device, and to derive reproducibility margins that take internal tissue shifts into account occurring between repeat setups. MATERIALS & METHODS: The reproducibility of mammary gland structure during repeat setups in a supine position is estimated by quantification of tissue shifts in the breasts of healthy volunteers between repeat MR setups. For each volunteer fiducials are identified and registered with their counter locations in corresponding MR volumes. The difference in position denotes the shift of breast tissue. The dependence on breast volume and the part of the breast, as well as the effect of a breast immobilization cast are studied. RESULTS: The tissue shifts are small with a mean standard deviation on the order of 1.5 mm, being slightly larger in large breasts (V> 1000 cm3), and in the posterior part (toward the pectoral muscle) of both small and large breasts. The application of a breast immobilization cast reduces the tissue shifts in large breasts. A reproducibility margin on the order of 5 mm will take the internal tissue shifts into account that occur between repeat setups. CONCLUSION: The results demonstrate a high reproducibility of mammary gland structure during repeat setups in a supine position.

Adult↗

PubMed2005

Reproducibility of the bladder shape and bladder shape changes during filling.

The feasibility of high precision radiotherapy to the bladder region is limited by bladder motion and volume changes. In the near future, we plan to begin treatment delivery of bladder cancer patients with the acquisition of a cone beam CT image on which the complete bladder will be semi-automatically localized. Subsequently, a bladder shape model that was developed in a previous study will be used for bladder localization and for the prediction of shape changes in the time interval between acquisition and beam delivery. For such predictions, knowledge about urinary inflow rate is required. Therefore, a series of MR images was acquired over 1 h with time intervals of 10 min for 18 healthy volunteers. To gain insight in the reproducibility of the bladder shape over longer periods of time, two additional MRI series were recorded for 10 of the volunteers. To a good approximation, the bladder volume increased linearly in time for all individuals. Despite receiving drinking instructions, we found a large variation in the inflow rate between individuals, ranging from 2.1 to 15 cc/min (mean value: 9 +/- 3 cc/min). In contrast, the intravolunteer variation was much smaller, with a mean standard deviation (SD) of 0.4 cc/min. The inflow rate was linearly correlated with age (negative slope). To study the reproducibility of the bladder shape, we compared bladder shapes of equal volume. For all individuals, the caudal part of the bladder was the most reproducible (variations<0.3 cm in all cases). The cranial and posterior parts of the bladder was much less reproducible, with local SD values up to approximately 1.2 cm for bladders with a volume of 200 cc. These large long-term variations were primarily caused by changes in position and filling of the small bowel and rectum. However, for short time intervals, the rectal filling was (nearly) constant. Therefore, the reproducibility of urinary inflow, combined with the previously developed shape model gives us an excellent tool to predict short-term shape changes. We intend to use this tool for further improvement of image-guided radiotherapy for bladder cancer patients.

Adult↗

PubMed2006

A computer simulated phantom study of tomotherapy dose optimization based on probability density functions (PDF) and potential errors caused by low reproducibility of PDF.

Lung tumor motion trajectories measured by four-dimensional CT or dynamic MRI can be converted to a probability density function (PDF), which describes the probability of the tumor at a certain position, for PDF based treatment planning. Using this method in simulated sequential tomotherapy, we study the dose reduction of normal tissues and more important, the effect of PDF reproducibility on the accuracy of dosimetry. For these purposes, realistic PDFs were obtained from two dynamic MRI scans of a healthy volunteer within a 2 week interval. The first PDF was accumulated from a 300 s scan and the second PDF was calculated from variable scan times from 5 s (one breathing cycle) to 300 s. Optimized beam fluences based on the second PDF were delivered to the hypothetical gross target volume (GTV) of a lung phantom that moved following the first PDF The reproducibility between two PDFs varied from low (78%) to high (94.8%) when the second scan time increased from 5 s to 300 s. When a highly reproducible PDF was used in optimization, the dose coverage of GTV was maintained; phantom lung receiving 10%-20% prescription dose was reduced by 40%-50% and the mean phantom lung dose was reduced by 9.6%. However, optimization based on PDF with low reproducibility resulted in a 50% underdosed GTV. The dosimetric error increased nearly exponentially as the PDF error increased. Therefore, although the dose of the tumor surrounding tissue can be theoretically reduced by PDF based treatment planning, the reliability and applicability of this method highly depend on if a reproducible PDF exists and is measurable. By correlating the dosimetric error and PDF error together, a useful guideline for PDF data acquisition and patient qualification for PDF based planning can be derived.

Artifacts↗

PubMed2001

Reproducibility of interactive registration of 3D CT and MR pediatric treatment planning head images.

The reproducibility of an interactive image registration technique used as part of the radiotherapy treatment planning process was investigated for 3D CT and MR pediatric head images. Over a nine month period, 85 CT/MR image registrations, required for treatment planning, were repeated, 52 by the same operator and 33 by a different operator. All were performing image registrations for normal clinical care and the first registration was used clinically. Inter- and intra-operator reproducibility of the translation and rotation were calculated separately. The standard deviation of the average total translation and rotation was 0.39 mm and 1.7 degrees, and 0.58 mm and 2.8 degrees, respectively. The maximum difference between registrations was 1.1 mm and 4.1 degrees when repeated by the same operator, and 1.4 mm and 5.8 degrees when repeated by another operator. The variation for the lowest resolution parameters, out of plane translation and rotations, was 2 to 3 times larger than for in-plane movements. A registration took between 5 minutes and over half an hour for difficult cases, with a mean of 14.3 minutes. One to two millimeter reproducibility was not achieved and interactive registration was relatively time consuming. There is a clear image resolution effect on registration reproducibility, suggesting that reducing slice thickness could considerably improve registration reproducibility.

Adolescent↗

PubMed1991

Reproducibility of tolerance tests that are useful in the identification of campylobacteria.

Twenty type or other reference strains, each representing a different Campylobacter, Helicobacter, or Arcobacter taxon, were used to assess the reproducibility of 25 phenotypic tests that are used in the identification of such organisms. Twenty-two of the tests depended on growth inhibition, and each of these tolerance tests was performed by using three different basal media. Although the overall reproducibility of the tests with each basal medium exceeded 89%, the proportion of strains that were able to grow in a reproducible manner on the basal media varied from 100% for blood agar and 50% for nutrient agar to 5% for brucella agar. In general, test reproducibility was highest with the basal medium that supported the most luxuriant growth. For the majority of tests, the basal medium which gave the optimum reproducibility could be determined.

Animals↗

PubMed1999

Highly reproducible bactericidal activity test results by using a modified National Committee for Clinical Laboratory Standards broth macrodilution technique.

Bactericidal testing historically has exhibited variable reproducibility, even when prior standardized methods were employed. Several modifications to the National Committee for Clinical Laboratory Standards (NCCLS) broth macrodilution method are proposed to improve reproducibility. Recommended changes from the approved NCCLS guidelines (M21-A and M26-A) include omitting serum supplementation of Mueller-Hinton broth, incubating tubes at 35 degrees C for 24 h with no agitation until they are sampled, running all tests in duplicate with six dilutions instead of nine, reincubating the test for an additional 24 h to resolve discrepant bactericidal activity test results, using a single 0.1-ml sample from each clear tube for subculture, and adopting an alternate method for calculating endpoint determination. In order to test these recommendations in a clinical laboratory setting, we used the modified methodology on 224 separate tests for bactericidal activity. There were 102 serum bactericidal titer (SBT) and 122 minimum bactericidal concentration (MBC) assays performed. By defining reproducibility as agreement between duplicate tests +/- 1 dilution, we found 207 of 224 tests (92%) were reproducible at the 24-h subculture point (94% for the SBT assay and 91% for the MBC assay). When the 17 assays with discrepant results were incubated an additional 24 h for a second subculture, only 1 of 224 tests (0.4%) remained discrepant. The method used is practical for a clinical laboratory that chooses to perform bactericidal activity testing and assures a high level of reproducibility between duplicate assays. The total cost of a test was approximately $25.00.

Anti-Bacterial Agents↗

PubMed2004

Reproducibility of bone mineral density measurement in daily practice.

BACKGROUND: Bone mineral density (BMD) measurements are frequently performed repeatedly for each patient. Subsequent BMD measurements allow reproducibility to be assessed. OBJECTIVE: To examine the reproducibility of BMD by dual energy x ray absorptiometry (DXA) and to investigate the practical value of different measures of reproducibility in a group of postmenopausal women. METHODS: Ninety five women, mean age 59.9 years, underwent two subsequent BMD measurements of spine and hip. Reproducibility was expressed as smallest detectable difference (SDD), coefficient of variation (CV), and intraclass correlation coefficient (ICC). Sources of variation were investigated by multilevel analysis. RESULTS: The median interval between measurements was 0 days (range 0-45). The mean difference (SD) between the measurements (g/cm(2)) was -0.001 (0.02) and -0.0004 (0.02) at L1-4 and the total hip, respectively. At L1-4 and the total hip, SDD (g/cm(2)) was +/-0.05 and +/-0.04 and CV (%) was 1.92 and 1.59, respectively. The ICC at spine and hip was 0.99. CONCLUSIONS: Reproducibility in the postmenopausal women studied was good. In a repeated DXA scan a BMD change exceeding 2 radical 2CV (%), the least significant change (LSC), or the SDD should be regarded as significant. Use of the SDD is preferable to use of the CV and LSC (%) because of its independence from BMD and its expression in absolute units. Expressed as SDD, a BMD change of at least +/-0.05 g/cm(2) at L1-4 and +/-0.04 g/cm(2) at the total hip should be considered significant.

Absorptiometry, Photon↗

PubMed2004

Reproducibility of circadian retinal and optic nerve head blood flow measurements by Heidelberg retina flowmetry.

BACKGROUND/AIM: The Heidelberg retina flowmeter (HRF) is designed to measure retinal capillary blood flow. Previous studies however showed weak reproducibility of data. The intraindividual reproducibility of circadian HRF measurements was examined in healthy subjects in three locations of the retina. METHODS: 36 healthy volunteers (27.3 (SD 4.3) years) were examined by HRF seven times a day (t0-t6). Using a default window of 10 x 10 pixels, three consecutive measurements were performed in three precise focusing planes: superficial, intermediate and deep layer, peripapillary retina, neuroretinal rim and cup, respectively. Images of identical tissue locations identified by capillary landmarks of each layer were selected to quantify the retinal microcirculation of each volunteer. Means and standard deviations of all flow results of a given subject were calculated, at t0-t6 and the coefficients of variation as a measure of reproducibility. RESULTS: The coefficients of variation ranged between 8.4% and 41.0% in the superficial layer (mean 19.8% (SD 8.4%)), 10.6%, and 43.0% in the intermediate layer (mean 24.0% (SD 8.4%)), and 9.9% and 84.0% (mean 29.6% (SD 15.8%)) in the deep layer. CONCLUSIONS: These data show the best reproducibility of measurements in the superficial layer followed by the intermediate and the deep layer. Clinically, this is an unsatisfactory intraindividual reproducibility of flow values in each studied layer.

Adult↗

PubMed1999

Grading nuclear cataract: reproducibility and validity of a new method.

AIMS: To assess the reproducibility and validity of a new instrument for grading nuclear cataract-the laser slit lamp, by comparison with an established method of lens grading-the Lens Opacities Classification System III (LOCS III). METHODS: 62 volunteers (113 eyes) were examined on two occasions. At each visit, a video image of the anterior segment was captured with the laser slit lamp and stored digitally. A measure of lens opacity for each laser slit lamp image was calculated using image analysis software. Each lens was also photographed on both visits for LOCS III grading of nuclear colour and nuclear opalescence. RESULTS: There was a linear increasing relation between the laser slit lamp measure of nuclear lens opacity and the LOCS III nuclear opalescence scores. The overall reproducibility of the laser slit lamp measurement was comparable with LOCS III (intraclass correlation coefficient of 95% (95% CI 92.9-96.5) for the laser slit lamp method; 97% (95% CI 95. 6-97.9) for the LOCS III method). However, among healthy subjects, the reproducibility was lower (intraclass correlation for the laser slit lamp of 38.6% (95% CI 12.9-59.2) and 76.1% (95% CI 62.3-85.4) for LOCS III. CONCLUSION: The laser slit lamp appears to give a valid measurement of nuclear cataract. The reproducibility of the instrument was high and similar to that of LOCS III. Modifications to the design would have to be made to improve its reproducibility among healthy subjects. It is simpler than other objective instruments, and could be useful in large scale studies of cataract.

Adult↗

PubMed1999

Reproducibility of fundus autofluorescence measurements obtained using a confocal scanning laser ophthalmoscope.

AIM: To evaluate the reproducibility of the background fundus autofluorescence measurements obtained using a confocal scanning laser ophthalmoscope. METHODS: 10 normal volunteers and 10 patients with retinal disease were included in the study. One eye per subject was chosen randomly. Five images of the same eye of each individual were obtained, after pupillary dilatation, by two investigators using a confocal scanning laser ophthalmoscope. Background fundus autofluorescence was measured at 7 degrees temporal to the fovea in normal volunteers and between 7 and 15 degrees temporal to the fovea in patients. Within session reproducibility of the measurements obtained by each investigator and interobserver reproducibility were evaluated. RESULTS: For investigator 1 the median values of fundus autofluorescence obtained were 31.9 units for normal volunteers and 27.3 units for patients. The median largest differences in readings in normal volunteers was 5.7 units (range 1.4-13.5 units) and in patients 4.2 units (1.5-15.1 units). For investigator 2 the median values of fundus autofluorescence obtained were 28.9 units for normal volunteers and 27.4 units for patients. The median largest difference in readings in normal volunteers was 3.6 units (2.7-11.7 units), and in patients 4.1 units (1.5-9.3 units). The median interobserver difference in readings in normal volunteers was 3.3 units and for patients 6.6 units. The median greatest interobserver difference in measurements obtained for normal volunteers was 8.8 units (8.4-23.0 units) and for patients 11.1 units (7.1-40.8 units). CONCLUSION: Within session reproducibility of the measurements of background fundus autofluorescence was satisfactory. Although interobserver reproducibility was moderate, the variability of the measurements of fundus autofluorescence between observers appears to be small when compared with variation in fundus autofluorescence with age and disease.

Adolescent↗

PubMed1990

Observer reproducibility in grading dysplasia in colorectal adenomas: comparison between two different grading systems.

The two most well known and well defined grading systems for dysplasia in colorectal adenomas were compared with regard to reproducibility. The Konishi-Morson system (KMS) operates with several histological and cytological variables and grades of mild, moderate, and severe dysplasia. The Kozuka system is based on the extent of nuclear pseudostratification and also has three grades of dysplasia (III-V). As the group of severe dysplasia is very large in this system, it was extended with two higher grades, similarly based on individual histological criteria, known hereafter as the extended Kozuka system (EKS). Fifty six adenomas were graded by two observers, each observer grading twice according to the KMS criteria and twice according to EKS criteria. Intraobserver reproducibility was excellent for the KMS and moderate for the EKS, but this was not significant. The overall interobserver reproducibility was similar (moderate) for the KMS and for the EKS. Kappa values for interobserver reproducibility on individual categories were excellent for severe dysplasia according to the KMS, but low for all other categories in both systems. By simplifying both systems into two groups a high reproducibility can be obtained, but this implies that all the original grades (III-V) for the EKS must be grouped together. It is therefore recommended that a simplified KMS is used for further studies on the biological importance of dysplasia and for comparison between histological changes and other markers for colorectal neoplasia.

Adenoma↗

PubMed1994

Accuracy, reproducibility, and variability of hand-held dynamometry in motor neuron disease.

A spring-loaded device that "breaks" at preset forces was used to assess readings obtained by hand-held dynamometry by three raters with varying experience in the method. Overall accuracy (3%), but not reproducibility or variability, was improved by greater experience. Readings obtained jointly by three raters had 53% greater variability than those obtained by a single rater. Nine muscle groups in 19 patients with motor neuron disease were assessed at 10 sessions (three replications per session) over six days by the experienced rater. Muscle force was expressed relative to that of 22 matched normal controls. The reproducibility was good with a mean % difference of 13.2 and repeatability coefficient of 2.17 kg-force for readings six days apart; the overall correlation coefficient was 0.98. The mean coefficient of variation (CV) of 10 readings was 9.9%. The poorer reproducibility and greater variability seen in clinically weaker muscles may account for differences in patients with bulbar palsy and classical amyotrophic lateral sclerosis; the degree of spasticity had no effect. The rater was estimated to contribute 37% of the total variability when testing patients. The use of a composite score by combining normalised dynamometry readings of eight limb muscles improved mean % difference to 6.7 and mean CV to 5.8%. The reproducibility and variability of hand-held dynamometry readings obtained by a single rater compare well with those of fixed devices. Readings from single raters, irrespective of experience, have similar reproducibility and variability. If, however, multiple raters are used in longitudinal assessments of individual patients, as occurs in clinical trials, the variability of their combined readings should be estimated when calculating the same size required.

Adult↗

PubMed2005

Human brain: reliability and reproducibility of pulsed arterial spin-labeling perfusion MR imaging.

The Committee of Human Research of the University of California San Francisco approved this study, and all volunteers provided written informed consent. The goal of this study was to prospectively determine the global and regional reliability and reproducibility of noninvasive brain perfusion measurements obtained with different pulsed arterial spin-labeling (ASL) magnetic resonance (MR) imaging methods and to determine the extent to which within-subject variability and random noise limit reliability and reproducibility. Thirteen healthy volunteers were examined twice within 2 hours. The pulsed ASL methods compared in this study differ mainly with regard to magnetization transfer and eddy current effects. There were two main results: (a) Pulsed ASL MR imaging consistently had high measurement reliability (intraclass correlation coefficients greater than 0.75) and reproducibility (coefficients of variation less than 8.5%), and (b) random noise rather than within-subject variability limited reliability and reproducibility. It was concluded that low signal-to-noise ratios substantially limit the reliability and reproducibility of perfusion measurements.

Adult↗