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PubMed2004

Evaluating the reproducibility of sinus lavages with a saline solution administered directly in the maxillary sinus of patients after endoscopic sinus surgery.

INTRODUCTION: Chronic sinusitis is recognized as having a strong inflammatory component, and failures of endoscopic sinus surgery (ESS) are frequently attributed to persistent inflammation. A test that would allow rhinologists to evaluate the inflammatory state of a patient's sinuses would be helpful to evaluate cases refractory to therapy, determine appropriate medical therapy, and monitor the response to therapy. OBJECTIVES: The goal of this preliminary research is to assess the optimal method of collection and the reproducibility and specificity of sinus lavages. METHOD: Twelve patients who had undergone ESS were recruited. They were divided into two groups according to the persistence of their symptoms and the recurrence of acute sinusitis after ESS. The subjects were seen twice. Three successive lavages were collected from each maxillary sinus and were analyzed by cell count. RESULTS: Intrasession cell counts were most reproducible (Spearman rank correlation .7 for eosinophils and .6 for neutrophils) for the second lavage. Intersession cell counts were highly reproducible for eosinophils (r = .7) for the second lavage. The two-tailed t-test did not reveal any statistically significant differences between the good and the poor outcome groups. CONCLUSION: Assessment of eosinophil cell counts on sinus lavage is a feasible and reproducible method to evaluate the inflammatory state of a patient's sinuses in patients who have undergone ESS.

Acute Disease↗

PubMed1995

Reproducibility of the first-phase insulin response to intravenous glucose is not improved by retrograde cannulation and arterialization or the use of a lower glucose dose.

OBJECTIVE: To determine whether the reproducibility of the first-phase insulin response (FPIR) measured during an intravenous glucose tolerance test is improved by the use of a lower glucose dose or retrograde sampling from an arterialized hand vein. RESEARCH DESIGN AND METHODS: Previous studies have suggested that the high within-subject variation of FPIR measurement of up to 110% could be reduced by sampling from a retrograde cannulated and arterialized hand vein opposite to the cubital fossa vein through which the glucose was injected or by the use of a lower dose of glucose. Two low-dose (glucose, 5 g/m2 injected over 30 s) and two standard Islet Cell Antibody Registry Users Study (ICARUS) (glucose, 0.5 g/kg injected over 3 min) tests were performed on seven normal subjects at 2-week intervals. Samples were collected simultaneously from the cubital fossa vein, through which the glucose was injected, and from a retrograde cannulated, contralateral hand vein that was arterialized by heating. FPIR was expressed as the sum of the insulin measurements 1 and 3 min after the completion of the glucose injection and as the area under the insulin curve between 0 and 10 min. RESULTS: Responses to the mean sum of serum insulin concentrations at 1 and 3 min after intravenous glucose were significantly lower for the low-dose test (mean 94 mU/l) than for the high-dose test (mean 184 mU/l) for samples taken from the arm (P < 0.05); mean 0- to 10-min insulin areas were 367 and 596 mU/l for low- and high-dose tests, respectively (P < 0.05). Within-subject coefficients of variation for samples from the hand or the arm ranged from 0.33 to 17.5% and 1.3 to 38% for successive ICARUS and low-dose tests, respectively. Reproducibility, measured by the coefficient of variation between successive tests for each protocol, was not significantly different using samples taken from the arm or the contralateral hand. CONCLUSIONS: The intravenous glucose tolerance test is reproducible when performed by the same operator over a short time span. Reproducibility is not significantly improved by sampling from an arterialized, retrograde cannulated, contralateral hand vein. There is no case for changing the present ICARUS protocol to incorporate retrograde cannulation or low-dose (5 g/m2) glucose.

Adult↗

PubMed2000

Similar 9-year mortality risks and reproducibility for the World Health Organization and American Diabetes Association glucose tolerance categories: the Hoorn Study.

OBJECTIVE: To compare the risks of all-cause and cardiovascular disease (CVD) mortality in the American Diabetes Association (ADA) and World Health Organization (WHO) glucose tolerance categories after 9 years of follow-up in the Hoorn Study and to study the test-retest reproducibility of those categories. RESEARCH DESIGN AND METHODS: In this population-based cohort study of 2,468 elderly men and women, subjects were classified according to both the WHO and the ADA criteria. Causes of death were extracted from the medical records. Age- and sex-adjusted relative risks were estimated by Cox's proportional hazards model. Reproducibility of the diagnostic criteria was assessed in a sample of 1,109 subjects with duplicate oral glucose tolerance tests. RESULTS: Subjects with known diabetes had a four to five times higher risk of all-cause and CVD mortality compared with normal subjects (P<0.05). The relative risks of all-cause mortality were 1.67 (95% CI 1.09-2.57) and 1.56 (1.00-2.43) for newly diagnosed diabetic subjects according to the WHO and ADA criteria, respectively. The WHO and ADA criteria had similar levels of reproducibility The overall K was 0.59 (0.54-0.64) for WHO criteria and 0.61 (0.56-0.66) for ADA criteria. For the category of newly diagnosed diabetes according to WHO or ADA, the percentages of agreement for the second test compared with the first test were 77% (85/110) and 74% (74/100), respectively. CONCLUSIONS: Both sets of diagnostic criteria identify criteria-specific diabetic subjects with an increased mortality risk compared with normal subjects, and the reproducibility of both criteria is similar.

Aged↗

PubMed2005

Evaluation of intra- and interobserver reliability and image reproducibility to assess usefulness of high-resolution ultrasonography for measurement of anterior segment structures of canine eyes.

OBJECTIVE: To evaluate the usefulness of high-resolution ultrasonography (HRUS) for measurements of anterior segment structures in canine eyes. ANIMALS: 4 clinically normal Beagles. PROCEDURE: Images were obtained from 8 eyes with a handheld 20-MHz transducer. Eleven anterior segment structures on each image were measured 5 times by 2 independent observers. Coefficients of variation (CVs) for measurements were used to assess intraobserver reliability. Interobserver reliability was assessed by comparing measurements obtained by the 2 observers from the same images. Five images were sequentially obtained from 2 locations (ie, superior and temporal) to evaluate image reproducibility. Anterior segment structures were measured once on each image; image reproducibility was assessed by use of the CV for each parameter measured. Imaging location was assessed by comparison of CV for measurements from each location. RESULTS: CVs were < 10% for observer A for all measurements except the ciliary cleft area (11.63%). The CVs were > 10% for observer B for measurements of the angle recess area (18.51%) and ciliary cleft width (17.44%) and area (16.01%). Significant differences in measurements between observers were found for 5 of 11 anterior segment structures. Imaging the superior aspect of the globe provided the most reproducible images, although image reproducibility was still somewhat variable, with the highest and lowest CVs for measurements of 33.01% and 11.32%, respectively, in the superior position. CONCLUSIONS AND CLINICAL RELEVANCE: High-resolution ultrasound images can be used to reliably measure various anterior segment structures. Clinically relevant findings in the anterior segment of canine eyes may be detectable by use of HRUS.

Animals↗

PubMedDate not supplied

The encapsulation of a model protein in poly (D, L lactide-co-glycolide) microparticles of various sizes: an evaluation of process reproducibility.

Poly (D, L lactide-co-glycolide) and poly (D, L lactide) microparticles were prepared by solvent evaporation and the process reproducibility was evaluated in terms of the loading of a model protein into the microparticles, the microparticle size and the in-vitro release profiles of the protein. The results showed that the microencapsulation method allowed the preparation of microparticles with mean sizes from < 0.5 micron to 100 microns in size, with protein entrapment from 0.5 to 5% w/w. The microparticles were smooth and free from surface defects. Moreover, the reproducibility of the preparation method was demonstrated by the in-vitro release profiles obtained using different batches of microparticles prepared under similar conditions and by the reproducibility of microparticle size and protein loading. The results demonstrated that the preparation method was both robust and reproducible and allowed the preparation of microparticles with desired characteristics in terms of loading levels, particle size and release rates.

Lactic Acid↗

PubMed1988

Reproducibility study on the Scheimpflug Cataract Video Camera.

The Zeiss Scheimpflug Cataract Video Camera was designed to photograph, store and analyze cataracts in a semi-automated fashion for cross-sectional and longitudinal studies. We conducted a reproducibility study of this system. Twenty-four normal and 61 cataractous eyes were photographed twice by each of two of the authors in the 90 degree meridian and microdensitometry was performed on each of the stored images. Reproducibility was then determined using the intraclass correlation coefficient to determine whether or not the differences encountered were due to variability in the system or due to actual differences among the images. The intraclass correlation in the lens nucleus was 0.995 with 95% confidence limits of .992-.996. Therefore, reproducibility was 99.5%. In the anterior cortex, intraclass correlation was .941 with 95% confidence limits of .919-.959. In the posterior cortex intraclass correlation was .905 with 95% confidence limits of .870-.932. Reproducibility with this instrument was therefore excellent and with certain limitations, this may be a useful instrument in monitoring lens changes in certain diseases and the effects of anti-cataract agents.

Cataract↗

PubMed1993

The accuracy of the histological classification of lung carcinoma and its reproducibility: a study of 75 archival cases of adenosquamous carcinoma.

The classification of lung carcinoma into a small cell lung carcinoma (SCLC) and non-small cell lung carcinoma (NSCLC), is highly reproducible. There are few studies on the reproducibility of subtyping NSCLC, with anecdotal reports on the subtype of adenosquamous carcinoma. We undertook a study of 75 cases archived as adenosquamous carcinoma. All cases were accepted as NSCLC on independent review by three pathologists utilizing the 1982 World Health Organization (WHO) classification criteria. The acceptance rate of adenosquamous carcinoma by the three pathologists was 65%, 28%, and 65%. Cases not accepted as adenosquamous fell into the different subtypes of NSCLC, with a concordance rate between each pair of pathologists of 49%, 61% and 43%, indicating poor agreement between pathologists. The study confirms the high reproducibility of the classification into SCLC and NSCLC; it shows poor concordance for all subtypes of NSCLC with poor reproducibility of diagnosis of adenosquamous carcinoma as specified by the 1982 WHO classification. Physicians dealing with lung carcinoma should be aware of this limitation of classification.

Carcinoma, Adenosquamous↗

PubMed1993

Evaluation of the reproducibility and accuracy of ambulatory blood pressure monitoring using the Takeda TM-2420 automated blood pressure monitor.

The reproducibility of ambulatory blood pressure measurements was assessed in eight normotensive subjects who underwent three separate days of recording, using Takeda Medical TM-2420 (TM-2420) blood pressure monitors. The coefficients of variation of mean 24 hour systolic and diastolic blood pressure were 2.1% and 2.8% respectively. The corresponding values for systolic and diastolic blood pressure variability, were 19% and 14% respectively. Measurement intervals of greater than 30 minutes significantly reduced the reproducibility of mean day interval systolic measurements. The bias of the TM-2420 systolic and diastolic blood pressure measurements compared to standard sphygmomanometer measurement were 0 +/- 7 mmHg and 1 +/- 6 mmHg respectively. Ambulatory blood pressure monitoring provides reproducible estimates of mean systolic and diastolic blood pressure, however, blood pressure variability is poorly reproducible.

Adaptation, Physiological↗

PubMed2005

Reproducibility and validity of workers' self-reports of physical work demands.

The objective of this paper is to provide a systematic review of the reproducibility and validity of self-report questions concerning physical work demands. After a bibliographic search of Medline and Ergonomic Abstracts for 1980-2003, 15 articles meeting the eligibility criteria were reviewed for methodological quality; 82 formulations of questions on physical work demands were evaluated for reproducibility and 83 for validity. Questions evaluated for both reproducibility and validity that performed well in both sets of studies included those on duration or presence of sitting and standing posture, the presence of walking, kneeling or squatting postures, duration or frequency of hands above shoulders, manual handling of more than or less than 10 kg, general level of physical effort, presence and duration of whole-body vibration, and duration of the use of visual display terminals. Suggestions for improving the design of reproducibility and validity studies and directions for future research in physical workload measurement are proposed.

Computer Terminals↗

PubMed1995

Color Doppler imaging of the eye: normal ranges, reproducibility, and observer variation.

Color Doppler ultrasonography has numerous potential applications in the diagnosis and monitoring of many ocular disease processes. One of its advantages over other investigative and diagnostic tests is its safety and repeatability. To be able to fully assess this technique it is important to have good control data and to know the reproducibility of the technique for each of the retrobulbar vessels. Color Doppler ultrasonography was performed on 80 volunteers, and normal ranges of blood velocity were calculated for the ophthalmic artery and for the central retinal artery and vein. Reduction in the peak systolic and end diastolic velocities in the ophthalmic artery and an increase in resistive index in the central retinal artery and vein were noted with advancing age. With regard to reproducibility of the retrobulbar vessels, 15 healthy persons were chosen at random and intra- and interobserver studies performed. The most reliable and reproducible vessels were the ophthalmic artery and central retinal artery and vein. Greater variation was noted in the posterior ciliary vessels, whereas the superior ophthalmic and vortex veins were unreliable in both detection and velocity measurement. The results provide normal ranges for future studies and demonstrate that reproducible results can be obtained for the orbital vasculature using color Doppler imaging.

Adult↗

PubMed1999

Lumen reduction measurements of the internal carotid artery before and after Levovist enhancement: reproducibility and agreement with angiography.

Our aim was to assess reproducibility of three different lumen reduction measuring methods--North American Symptomatic Carotid Endarterectomy Trial, European Carotid Surgery Trial, and common carotid--using power Doppler and color Doppler sonography before and after Levovist enhancement. We included 20 symptomatic patients with mild or severe carotid disease. North American Symptomatic Carotid Endarterectomy Trial, European Carotid Surgery Trial, and common carotid measurements on longitudinal views and European Carotid Surgery Trial measurements on transverse views were performed. Examinations were repeated and the results compared to assess reproducibility of measurements. Correlation with angiography was obtained by calculating Pearson correlation coefficients. Reproducibility was significantly better (P < 0.05) for European Carotid Surgery Trial and common carotid measurements (95% limits of agreement between -10% to 10% and -19% to 17%) as compared to North American Symptomatic Carotid Endarterectomy Trial measurements (95% limits of agreement between -11% to 21% and -21% to 23%). Variability of measurements after enhancement increased slightly (not significant) for both power and color Doppler sonography. Additionally, European Carotid Surgery Trial measurements, using nonenhanced power Doppler or color Doppler sonography, did not correlate significantly with angiography, whereas North American Symptomatic Carotid Endarterectomy Trial and common carotid measurements correlated well with angiography, particularly in power Doppler mode after enhancement (r = 0.88 and r = 0.82, respectively). We conclude that for lumen reduction measurements of the internal carotid artery with power and color Doppler sonography, the common carotid method is the only method that is reproducible and has good correlation with angiography, which slightly improves after Levovist enhancement.

Aged↗

PubMed2005

Intraobserver and interobserver reproducibility of ovarian volume, antral follicle count, and vascularity indices obtained with transvaginal 3-dimensional ultrasonography, power Doppler angiography, and the virtual organ computer-aided analysis imaging program.

OBJECTIVES: The purpose of this study was to assess intraobserver and interobserver reproducibility of the parameters of ovarian response and oocyte ability, studied by 3-dimensional ultrasonography and power Doppler angiography (PDA), and the possible influence of the ovarian functional stage. METHODS: Twenty-nine women were included in an in vitro fertilization program. Fourteen women were evaluated after pituitary suppression (basal group), and 15 were scanned on the human chorionic gonadotropin administration day, after gonadotropin ovarian stimulation (stimulated group). A first observer acquired 2 volumes for each ovary. Another observer performed a second analysis of the volumes acquired by the first observer. We analyzed ovarian volume, follicle number in the basal group, vascularization index, flow index, and vascularization-flow index. The volumes were processed by the Virtual Organ Computer-Aided Analysis imaging program using plane A and 15 degrees rotational steps. RESULTS: Ovarian volume showed excellent intraobserver and interobserver agreement, with an intraclass correlation coefficient (Intra-CC) and an interclass correlation coefficient (Inter-CC) close to the unit. The Intra-CC and Inter-CC about the number of follicles were 0.964 and 0.978, respectively. Vascularity indices showed an Intra-CC greater than 0.90. The vascularization index and the vascularization-flow index showed higher interobserver than intraobserver reproducibility (Inter-CC > 0.96 for both). The flow index Inter-CC was 0.898. The reproducibility differences between the basal and stimulated ovary measurements were not significant. CONCLUSIONS: There is an excellent intraobserver and interobserver reproducibility of the ovarian volume, follicle counts, and 3-dimensional PDA indices. The ovarian functional stage has no influence on the reliability. Three-dimensional ultrasonography and PDA improve the study of ovarian parameters, and their reliability impels a change in the current clinical routine of performing and interpreting ultrasonography.

Adult↗

PubMed1999

Regional reproducibility of microsatellite instability in sporadic colorectal cancer.

The reproducibility of microsatellite instability from different regions of the same sporadic colon cancer has not been addressed. We therefore microdissected and extracted DNA from three to nine separate regions of 13 highly unstable sporadic colon cancers. Each region was then evaluated by polymerase chain reaction amplification of 17 microsatellites: 10 tetranucleotide repeats, 2 noncoding mononucleotide repeats (BAT-26 and BAT-40), and 5 coding mononucleotide repeats (TGFBRII, BAX, MSH3, MSH6, IGFIIR). Microsatellite instability showed 100% regional reproducibility with respect to either the panel of 10 tetranucleotide repeats or BAT-26, and nearly 100% reproducibility with BAT-40, although regional variation in the percent instability and the size of unstable alleles was present. TGFBRII was more frequently mutated than any other coding mononucleotide repeat; frame shifts in this gene were identified in nearly every region of every tumor. Each of the five coding repeats showed regional variability in at least one tumor, and 10 of the 13 tumors showed variability with at least one coding repeat. This variability took the form of different mutant alleles (TGFBRII, BAX, MSH3) or mutations present in some but not all regions of a tumor (MSH6, IGFIIR, BAX, MSH3). We conclude that the regional reproducibility of generalized microsatellite instability as measured by noncoding repeats indicates that sampling is not a problem in these highly unstable tumors, and that the mismatch repair deficiency phenotype is acquired in the very late adenoma stage or early cancer stage of sporadic colonic tumorigenesis. The high frequency of TGFBRII mutations is consistent with acquisition of these mutations at a similar stage of tumorigenesis. The regional variability with respect to the presence or absence of a mutation in the other four coding mononucleotide repeats could lead to sampling error and is consistent with a somewhat later time of acquisition of these mutations. Genes Chromosomes Cancer 26:106-114, 1999.

Adult↗

PubMed1999

Reproducibility and accuracy of MR imaging of the brain after severe birth asphyxia.

BACKGROUND AND PURPOSE: MR imaging of the brain can be used to detect cerebral damage after suspected hypoxic-ischemic injury. This study examines the reproducibility and accuracy of MR imaging soon after severe birth asphyxia. METHODS: During a 48-month period, full-term newborn neonates, who died within the first week as a result of severe hypoxic ischemic encephalopathy, were included in the study if they had undergone early (<5 days old) MR imaging and postmortem neuropathologic studies. Two trained observers assessed reproducibility by examining multiple brain regions independently with current criteria and then defining and applying improved criteria. Accuracy of MR findings was tested by comparing the brain regions about which the two imaging raters agreed to those regions about which the two pathologists agreed. RESULTS: Eight neonates, with a median gestational age of 40 weeks (range, 38-40 weeks) and who suffered severe birth asphyxia, were included in the study. In the reproducibility study, MR imaging agreement was moderate when current criteria were used (k = .44). Using the improved criteria, agreement increased considerably (k = .62). Much of this improvement was due to limiting the analyses to the posterior limb of the internal capsule, thalamus, parietal cortex, hippocampus, and medulla. The posterior limb of the internal capsule was the most reliable region analyzed. MR imaging agreement was similar to that achieved by two experienced pathologists reviewing the histologic sections (k = .66). In the accuracy study, MR imaging abnormality was predictive of pathologic abnormality with a sensitivity of .79 and a positive predictive value of 1.0. The predictive value of a single MR imaging abnormality was .79 (95% confidence interval, .61-.96). CONCLUSION: Criteria that provide substantial reproducibility and accuracy for the interpretation of MR imaging findings very early after birth asphyxia can be derived.

Asphyxia Neonatorum↗

PubMed2000

A multicenter trial on interobserver reproducibility in reporting on 99mTc-DMSA planar scintigraphy: a Belgian survey.

UNLABELLED: Conflicting opinions have been expressed regarding reproducibility in 99mTc-dimercaptosuccinic acid (DMSA) planar renal image interpretation. The purpose of this investigation was to determine the level of interobserver variability among a large group of Belgian nuclear medicine physicians who evaluated a randomly selected series of DMSA planar scintigraphic examinations performed on children and adults. METHODS: All Belgian nuclear medicine centers (n = 82) were invited to participate in a reproducibility study on 99mTc-DMSA scintigraphy. 99mTc-DMSA scans obtained on 10 adults and 40 children were randomly selected from the databases of 2 hospitals. Those participating in this investigation (65 centers = 79%) received a series of computer disks containing 50 99mTc-DMSA studies. To avoid potential problems related to unfamiliar display, the disks were formatted to be interpretable using the participants' own computer systems. Each participant was then free to use his or her usual display (hard copies, contrast enhancement, color scale, gray scale, and so forth). For each kidney, the observers had to choose between the following answers: normal, abnormal, equivocal, and lack of quality. RESULTS: Forty-two responses were obtained from a wide variety of institutions and from observers with different levels of experience in interpreting 99mTc-DMSA scintigraphy. Altogether, the following data were obtained: 60.8% normal, 25.2% abnormal, 7.0% equivocal, and 3.2% lack of quality. The median percentage of agreement (overall reproducibility) for the 42 observers was 92%. When the results of all 42 observers were compared, the median agreements on normality and abnormality were 93.5% and 90.5%, respectively. In a small number (n = 4) of kidneys, reproducibility was poor and ranged from 51% to 70%. Except for 2 outliers, all observers had almost the same level of performance. CONCLUSION: A large number of Belgian nuclear medicine physicians participated in evaluating a large randomly selected sample of 99mTc-DMSA studies, and excellent interobserver agreement was found.

Adolescent↗

PubMed1999

[How reproducible is blood pressure measurement? Intra- and interindividual blood pressure variability in routine practice].

Considering the reproducibility of blood pressure readings the epidemiologist and the physician in his clinical work take two different points of view. Studying drug effects the epidemiologist is interested in significant differences of blood pressures in a study population. The physician however, who estimates the effect of his prescription given to an individual patient has to compare single blood pressure readings in single individuals. In a pharmacological study we accept without any doubt the need of certain numbers of investigations to define a difference of 10 mm Hg as significant. In clinical routine however we behave quite differently and judge single readings intuitively as equal or different, independent of any statistical considerations. Not only the doctor but also the scientific societies with the highest reputation share the same point of view. In their recommendations they accept an arithmetic mean of two blood pressure readings as sufficient to judge blood pressures in individuals. In order to discuss this topic primarily from the doctors point, we analysed repeated blood pressure readings of 21 volunteers who tested 20 different blood pressure devices. We conclude, that the ongoing practice of judging the blood pressures of the patients meets only the needs of the epidemiologist. Reproducibility of single readings or mean values of two readings however are insufficient to draw satisfactory conclusions from the distributions of blood pressure in single individuals. Due to the short and long term blood pressure variability increasing the numbers of readings within a single day does not improve reproducibility sufficiently. It seems that the amount of blood pressure readings which are necessary to improve reproducibility of "the patients blood pressures" should be increased and taken over several days. If this is true, daily self-recordings should be the most promising approach.

Adult↗

PubMed2000

Reproducibility of p53 immunohistochemistry in bladder tumors. National Cancer Institute, Bladder Tumor Marker Network.

The National Cancer Institute Bladder Tumor Marker Network conducted a study to evaluate the reproducibility of immunohistochemistry for measuring p53 expression in bladder tumors. Fifty paraffin blocks (10 from each of the five network institutions) were chosen at random from among high-grade invasive primary bladder tumors. Two sections from each block were sent to each laboratory for staining and scoring, and then all sections were randomly redistributed among the laboratories for a second scoring. Intra- and interlaboratory reproducibility was assessed with regard to both staining and scoring. For overall assessments of p53 positivity, the results demonstrated that intralaboratory reproducibility was quite good. Concordance across the five participating laboratories was high for specimens exhibiting no or minimal nuclear immunostaining of tumor cells or high percentages of tumor cells with nuclear immunoreactivities. However, there was a reduced level of concordance on specimens with percentages of stained tumor cells in an intermediate range. The discordancies were due mainly to staining differences in one of the five laboratories and scoring differences in another laboratory. These results indicate that some caution must be used in comparing results across studies from different groups. Standardization of staining protocols and selection of a uniform threshold for binary interpretation of results may improve assay reproducibility between laboratories.

Analysis of Variance↗

PubMed2000

Test-retest reproducibility of extrastriatal dopamine D2 receptor imaging with [123I]epidepride SPECT in humans.

UNLABELLED: This study evaluated the test-retest reproducibility of D2 receptor quantification in the thalamus and temporal cortex using [123I]epidepride SPECT. METHODS: Ten healthy volunteers (4 men, 6 women; age range, 19-46 y) underwent 2 SPECT studies (interval, 2-26 d) using a bolus-plus-constant-infusion paradigm (bolus-to-infusion ratio = 6 h; infusion time = 9 h). Plasma clearance (in liters per hour) and free fraction (f1) of the parent tracer were measured. Radioactivity (in becquerels per gram) in the thalamus, temporal cortex, and cerebellum were normalized to the infusion rate (in becquerels per hour). Normalized striatal radioactivity was also measured to assess reproducibility in regions with a high density of receptors and better counting statistics. The outcome measures obtained were V3 (receptor density [Bmax]/equilibrium dissociation constant [KD]), V3' (f1 x Bmax/KD), and RT (specific-to-nondisplaceable tissue ratio). RESULTS: Test-retest variability and reliability (intraclass correlation coefficient) were 10.8% and 0.88, respectively, for plasma clearance and 15.3% and 0.77, respectively, for f1. The test-retest variability of brain-specific (target minus nondisplaceable) radioactivity was higher in the thalamus and temporal cortex than in the striatum, although reliability was comparable. Among the outcome measures, V3' showed better test-retest variability and reliability in the thalamus (13.3% and 0.75, respectively) and temporal cortex (13.4% and 0.86, respectively). CONCLUSION: Brain radioactivity was the main source of variability for quantification of extrastriatal D2 receptors with [123I]epidepride. The reproducibility of outcome measures in extrastriatal regions was good. However, because receptor density was lower in extrastriatal regions than in the striatum, the counting statistics in these regions were low and reproducibility was affected by the higher test-retest variability of brain-specific radioactivity. Compared with V3 and V3', RT showed less test-retest variability in the thalamus and temporal cortex but lower reliability. Moreover, measurement of RT may be affected by the presence of potential lipophilic metabolites entering the brain.

Adult↗