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 127 records · Page 7Linked to original sources

PubMed1996

Short- and long-term reproducibility of time and frequency domain heart rate variability measurements in normal subjects.

OBJECTIVE: To obtain data relating to the reproducibility of the time and frequency domain measurements obtained from 10-min ECG recordings. METHODS: Eighteen normal volunteers underwent evaluations of time and frequency domain heart rate variability 2 weeks and 7 months after baseline analysis. The time domain parameters were mean NN, the standard deviation of NN intervals, the percentage of successive NN intervals > 50 ms and the root mean square successive difference of NN intervals. The frequency domain evaluations (total power, low frequency, and high frequency) were made by means of both the Fast Fourier Transform algorithm (FFT) and the autoregressive method (AR) from 10-min ECG recordings made under three different conditions: rest, controlled respiration, and after a passive head-up tilt test. Reproducibility was evaluated by means of the interclass correlation coefficient (ICC), comparing baseline values with the results obtained at the second week and the seventh month. Time domain evaluation were also made from 10-min ECG. RESULTS: All of the time domain measurements had an ICC > or = 0.75, except for the standard deviation of NN intervals, which had an ICC of 0.57. The frequency domain parameters obtained by means of either FFT or AR showed similar reproducibility. Low frequency was reproducible under all three conditions, total power only at rest, and high frequency only during controlled respiration. CONCLUSION: The reproducibility of frequency domain parameters depends on the analysed condition. These results are of primary importance when the effects of drugs or other interventions on heart rate variability are under investigation.

Adult↗

PubMedDate not supplied

Variation in late potentials and the reproducibility of their measurement.

The usefulness of a test depends on its reproducibility. This determines how closely the test result indicates the actual pathophysiologic state, how well it will predict that state in the future, and if interventions or further pathologic changes are reflected by the test. There is a variation in the parameters of the signal-averaged ECG, more so with spectral than with time domain measurements. These must be accounted for when estimating risk. If one presumes that risk is proportional to the extent of abnormality, then the variation in measurements simply means that only borderline cases can potentially be miscategorized. More important, the lack of reproducibility of measurements made from the signal-averaged ECG indicates that changes noted in an individual after an intervention, such as a surgical intervention, must be viewed with a jaundiced eye. Group changes are perhaps meaningful, and indicate a physiologic effect, but clinical decisions cannot be made unless the changes observed in an individual patient exceed the confidence limits of expected variation. There has been debate as to the usefulness of measurements made from the signal-averaged ECG in predicting antiarrhythmic drug effects (the effect of drugs is discussed elsewhere in this symposium). Here an analogy must be made to the suppression of asymptomatic ventricular ectopy. First, we cannot make a statement that there has been a drug effect unless the parameter measured changes beyond the confidence limits of normal variation or reproducibility. Second, we cannot translate a change in a measurement into a change in risk for arrhythmic events without subjecting that hypothesized relationship to a long-term placebo-controlled clinical trial, albeit acute electrophysiologic trials correlating changes in the signal-averaged ECG to ventricular tachycardia induction provide some insight. And perhaps the relationship must be tested independently for each drug assessed. In the same regard, there is much excitement about the benefits of thrombolytic therapy, but when diagnosing benefit to the individual patient we have to remember the lack of reproducibility of the measurements and also keep in mind that an improved signal-averaged ECG cannot be translated into an improved prognosis without long-term controlled studies. In summarizing the variation and reproducibility of measurements made from the signal-averaged ECG we avoided providing more than a sense of the extent of variation expected because precise confidence intervals depend on the particular techniques used to make the measurements.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗

PubMed1990

Day to day reproducibility of electrically inducible ventricular arrhythmias in survivors of acute myocardial infarction.

Day to day reproducibility of the response to programmed ventricular stimulation has not been evaluated in survivors of acute myocardial infarction. Programmed ventricular stimulation was performed prospectively on 2 consecutive days in 56 patients on an average of 12 +/- 5 days (range 7 to 29) after an acute myocardial infarction. No patient had a history of documented or suspected sustained ventricular tachycardia or fibrillation occurring greater than 48 h after infarction. During initial programmed ventricular stimulation, 21 patients had induction of sustained ventricular tachycardia or fibrillation (Group I), and 35 patients had induction of either nonsustained ventricular tachycardia or no ventricular tachycardia (Group II). Repeat programmed ventricular stimulation in Group I patients induced sustained ventricular tachycardia or fibrillation in 16 of 21 patients (reproducibility 76%); the maximal induced response in the other 5 patients was nonsustained ventricular tachycardia in 2 patients and fewer than six repetitive ventricular responses in 3 patients. The day to day reproducibility was significantly higher for inducible sustained ventricular tachycardia of cycle length greater than or equal to 240 ms compared with rapid sustained ventricular tachycardia of cycle length less than 240 ms (100% versus 44%, p less than 0.009) or ventricular fibrillation (100% versus 43%, p less than 0.009). Repeat programmed ventricular stimulation in Group II patients did not induce sustained ventricular arrhythmias in 31 of 35 patients (reproducibility 89%). Thus, in survivors of acute myocardial infarction, inducible slow sustained ventricular tachycardia was a highly reproducible finding, whereas inducibility of rapid sustained ventricular tachycardia and ventricular fibrillation showed a significant day to day variability.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

Immediate reproducibility of electrically induced sustained monomorphic ventricular tachycardia before and during antiarrhythmic therapy.

The immediate reproducibility of sustained ventricular tachycardia induction was evaluated prospectively during 106 studies performed in 53 patients with clinical sustained monomorphic ventricular tachycardia. Programmed electrical stimulation was performed twice, using the same protocol during 53 drug-free studies and 53 subsequent studies on antiarrhythmic therapy. Sustained monomorphic ventricular tachycardia was reproduced in 104 (98%) of the 106 studies. There was no significant difference in the incidence of reproducible tachycardia in the drug-free state compared with that observed during treatment with different classes of antiarrhythmic drugs. An increase in the number of extrastimuli was required to reinitiate the tachycardia in 9 (11%) of 83 studies in which single or double extrastimuli were initially required to induce the tachycardia. In 39 (37%) of 104 studies with reproducible tachycardia induction, the two tachycardias significantly differed in electrocardiographic (ECG) configuration and cycle length. These observations suggest that the overall reproducibility of ventricular tachycardia induction is sufficiently high to provide a reliable marker for evaluating the efficacy of therapeutic interventions. However, specific tachycardia characteristics such as cycle length and ECG configuration are more variable even within the same study and may be less useful in assessing the effects of subsequent interventions.

Anti-Arrhythmia Agents↗

PubMed1990

Characteristics of individuals and long term reproducibility of dietary reports: the Tecumseh Diet Methodology Study.

Food frequency reports in 1967-1969 were compared to frequency reports of the same foods asked retrospectively in 1982-1983 and 1967-1969 for 1184 respondents aged 45-64 years in the Tecumseh Community Health Study. The kappa statistic for concordance of the retrospective and baseline reports was used as a summary measure of the individual's ability to reproduce his or her earlier diet report. Reproducibility was estimated for total diet, represented by 83 foods, and for 9 subsets of foods of epidemiologic interest. In bivariate and multivariate analyses, reproducibility was strongly related to stability of diet; those whose diets changed least over the 15-year period had greatest diet reproducibility. Greater total diet reproducibility was also found among men with higher education, among women of less than 110% desirable weight reporting no special diet and among women reporting no medications. Consistent with current models of memory, the retrospective report of diet was strongly related to the current report of diet. Agreement between the retrospective and baseline diet reports was greater than agreement between the current and baseline diet reports. This indicates that, as a proxy for past diet, the retrospective report of diet is superior to the current report. Similar relationships were found for the 9 subset of foods.

Body Weight↗

PubMed1994

Reproducibility of retinal nerve fiber layer evaluation by dynamics scanning laser ophthalmoscopy.

Scanning laser ophthalmoscopy is a laser-based image acquisition technique, which greatly improves the quality of the examination of the fundus and the retinal nerve fiber layer. To assess retinal nerve fiber layer imaging by scanning laser ophthalmoscopy and evaluate intra- and interobserver reproducibility in the classification of retinal nerve fiber layer defects, three independent observers evaluated on two separate occasions the videotaped images of 150 eyes of 80 consecutive patients with ocular hypertension or glaucoma. Ophthalmoscopy was performed using argon blue light (488 nm), confocal apertures of 3 to 1 mm, and 40-degree and 20-degree field angles. Of 150 eyes, 20 (13.3%) were excluded from the study because of the poor quality of the images (clinically significant cataract or myopic peripapillary atrophy). The retinal nerve fiber layer was evaluated qualitatively according to a standard classification: normal pattern, slit, wedge, and diffuse defects. Intraobserver reproducibility, evaluated by kappa statistic, was excellent (> or = 0.75): observer A = 0.78 (95% confidence limits, 0.67-0.88); observer B = 0.84 (95% confidence limits, 0.72-0.96); and observer C = 0.79 (95% confidence limits, 0.67-0.91). Interobserver reproducibility was also excellent in all cases: observers A-B = 0.84 (95% confidence limits, 0.71-0.98); observers A-C = 0.76 (95% confidence limits, 0.65-0.87); and observers B-C = 0.80 (95% confidence limits, 0.69-0.92). Kappa values ranged between 0.59 and 0.69 for intraobserver reproducibility and between 0.55 and 0.69 for interobserver reproducibility when using only those eyes in which abnormalities were noted by at least one observer.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Observer variation and reproducibility of endoscopic ultrasonography.

To investigate interobserver variation and reproducibility of endosonographic findings, both experienced and inexperienced endosonographers evaluated depth of tumor invasion (T stage) and presence of lymph node metastasis (N stage) in 50 patients with nonobstructing esophageal carcinoma. Results were compared with the findings by surgical pathology of the resected specimens. The kappa statistic (kappa) was used to assess interobserver and intraobserver agreement and consistency of accurate interpretation (reproducibility) for the two groups. Agreement between the experienced endosonographers was excellent (kappa = > .75) for T1 and T4 lesions, good (kappa = .61) for T3 lesions, but only poor (kappa = > .46) for T2 lesions. The overall agreement between the experienced endosonographers was equally good for both T and N stages. Agreement between the inexperienced endosonographers was poor for all T stages but was good for lymph node metastasis (kappa = .52). For experienced endosonographers, endosonographic reproducibility of histologically confirmed T4 lesions was excellent, followed closely by T3 and T2 lesions; T1 tumors were frequently interpreted differently by the same endosonographer. Reproducibility of N stage determinations was excellent for N0 lymph nodes and good for N1 nodes. Thus, for experienced endosonographers, interobserver agreement was excellent for all T stages except T2, whereas reproducibility of determination of depth of tumor invasion was good to excellent for T2, T3, and T4 lesions but poor for T1 lesions. As yet poorly defined operator and machine-dependent factors that cause misinterpretation of T1 and T2 tumors will require additional study.

Endoscopy↗

PubMed1995

Clinical study of location and reproducibility of three mandibular positions in relation to body posture and muscle function.

Clinical studies have confirmed the adequate reproducibility of both centric occlusion and centric relation when used as reference positions during treatment; however, the reproducibility of the neuromuscular position has been found inadequate. This study evaluated the location and reproducibility of these three mandibular positions in relation to body posture, sitting and supine, and bilateral muscle activity before and after the insertion of a flat mandibular positioning device equilibrated to balance the muscle functions, as shown by two electromyography biofeedback instruments. Intraoral recordings were made in 11 young subjects with complete natural dentition. Acrylic resin clutches that supported a screw point in the maxillary arch and painted glass in the mandibular arch were used and positioned not to interfere with the occlusion. The distances of the screw scratch from two of the edges of the painted glass were used to measure the anteroposterior and mediolateral locations with a micrometer. The reproducibility was evaluated by measuring the scratch surface by measuring the weight of the print cutouts made from photographs of the scratches taken with a stereoscope. The location and reproducibility of centric occlusion and centric relation were not affected by body posture. A more precise posterior neuromuscular position was obtained in the supine position. The insertion of a mandibular positioning device did not affect centric occlusion but gave a more precise centric relation. Neuromuscular position became as precise as centric occlusion and was located anteroposteriorly between centric occlusion and centric relation.

Acrylic Resins↗

PubMed1996

Reproducibility and condylar position of a physiologic maxillomandibular centric relation in upright and supine body position.

Better understanding of the physiologic features of the masticatory system has led to the evolution of the concept of maxillomandibular centric relation from the mechanical to physiological bases. However, the reproducibility of physiologic methods for centric relation determination has been criticized. In this clinical study the swallowing technique was modified to establish a physiologic centric relation in a reproducible manner. Condylar and disk positioning and reproducibility of the proposed modified swallowing technique (MST) were compared with the same parameters of a traditional technique, namely, the chin point guidance technique (CGT). Both techniques were studied with the patient in the upright and supine positions. Three interocclusal records were obtained for each technique-position combination for each of the 30 patients. The recorded maxillomandibular relations were analyzed on the three-dimensional analyzer. MST positioned the condyles in a more superoanterior position than did CGT, which was interpreted as a better seating of the condyles and disk in the articular fossae. There was no significant difference in reproducibility between MST and CGT on x, y, or z axes (p > 0.05), indicating that it is possible to establish a physiologic centric relation in a reproducible manner. The term "functional centric area" was proposed in this study to define a neuromuscularly determined centric occlusal scheme.

Adult↗

PubMed1992

Reproducibility in monitoring nocturnal penile tumescence and rigidity.

The evaluation of sexual dysfunction has improved with the advent of methods to test nocturnal penile tumescence that also monitor penile rigidity. Earlier techniques may not have recorded abnormal rigidity despite normal tumescence. To test the reproducibility of penile tumescence and rigidity, the results of initial and repeat tracings performed a mean of 39 days apart were compared in 17 patients (median age 62 years). Three nocturnal patterns were identified. 1) Among the 17 patients the initial penile tumescence and rigidity pattern was reproduced on repeat testing in 15. 2) Patterns that were not reproduced in the other 2 patients were explained by the ingestion of alcohol or because of a febrile illness during the period monitored. 3) Nocturnal penile rigidity and tumescence tracings from these patients reproduced previous patterns. Monitoring of nocturnal penile tumescence and rigidity is a useful and reproducible tool in the evaluation of male sexual dysfunction.

Adult↗

PubMed1998

Reproducibility of neuroendocrine lung tumor classification.

For a tumor classification scheme to be useful, it must be reproducible and it must show clinical significance. Classification of neuroendocrine lung tumors is a difficult problem with little information about interobserver reproducibility. We sought to evaluate the classification of typical carcinoid (TC), atypical carcinoid (AC), large-cell neuroendocrine carcinoma (LCNEC), and small-cell carcinoma (SCC) tumors as proposed by W.D. Travis et al (Am J Surg Pathol 15:529, 1991). Forty neuroendocrine tumors were retrieved from the Armed Forces Institute of Pathology (AFIP) files and independently evaluated by five lung pathologists and classified as TC, AC, LCNEC, or SCC (pure SCC, mixed small cell/large cell, and combined SCC). A single hematoxylin and eosin-stained slide from each case was reviewed. Each participant was provided a set of tables summarizing the criteria for separation of the four major categories. Agreement was regarded as unanimous if all five pathologists agreed, a majority if four agreed, and a consensus if three or more pathologists agreed. The kappa statistic was calculated to measure the degree of agreement between two observers. A consensus diagnosis was achieved in all 40 cases (100%), a majority agreement in 31 of 40 (78%), and unanimous agreement in 22 of 40 (55%) of cases. Unanimous agreement occurred in seven of SCC (70%), seven of TC (58%), four of AC (50%), and four of LCNEC (40%). A majority diagnosis was achieved in 11 of 12 (92%) of TC, 9 of 10 (90%) of SCC, 6 of 8 (75%) of AC, and 5 of 10 (50%) of LCNEC. Most of the kappa values were 0.70 or greater, falling into the substantial agreement category. The most common disagreements fell between LCNEC and SCC, followed by TC and AC, and AC and LCNEC. The highest reproducibility occurred for SCC and TC, with disagreement in 8% and 10% of the diagnoses, respectively. For TC, 10% of the diagnoses rendered were AC. For AC, 15% of the diagnoses were rendered as TC, with 2.5% called LCNEC and 2.5% called SCC. For LCNEC, 18% and 4% of the diagnoses were called SCC and AC, respectively. For SCC, 4% of the diagnoses were called AC and 4% were called LCNEC. Thus, using the classification scheme tested, a consensus diagnosis can be achieved for virtually all neuroendocrine lung tumors with substantial agreement between experienced lung pathologists. Classification of NE tumors is most reproducible for classification of TC and SCC but less reproducible for AC and LCNEC. These results indicate a need for more careful definition and application of criteria for TC versus AC and SCC versus LCNEC.

Carcinoid Tumor↗

PubMed1997

The reproducibility of color Doppler duplex sonography in the measurement of renal arterial blood velocity.

In this study, the reproducibility of color Doppler duplex sonography for repeated measurements of renal blood flow was evaluated in 14 healthy subjects. We examined the reproducibility for different examiners and different time intervals between the examinations. Doppler frequency sonograms were analyzed with several parameters, and statistical evaluation was performed by calculating both the correlation coefficient (r) and coefficient of variation (CV). Peak systolic velocity (S), early diastolic velocity (D1) and mean velocity (MV) showed good reproducibility (r = 0.902-0.992, CV = 2.15-8.16%). On the other hand, end-diastolic velocity (D2), acceleration time (AT) and acceleration index (AI) showed poor reproducibility. We conclude that the reproducibility of this method is acceptable for repeated measurements of renal blood velocity, using suitable parameters S, D1 and MV.

Adult↗

PubMed1990

Five-year reproducibility of natural head posture: a longitudinal study.

Natural head posture (NHP) is being increasingly used as the logical reference position for the evaluation of craniofacial morphology. The basic premise underlying its use is that the long-term clinical reproducibility (variability) of NHP is significantly less than the variability of conventional intracranial reference planes with respect to the vertical. This study reports the results of a 5-year longitudinal study evaluating the reproducibility over time of NHP lateral cephalometric radiographs. The subjects were 126 randomly selected Chinese children in Hong Kong who were first assessed at the age of 12 years. Thirty subjects were recorded after 5 years. NHP reproducibility deteriorated over time but showed signs of stabilizing after 1 to 1 1/2 years. The method error was 1.93 degrees after 1 to 2 hours, 2.34 degrees after 3 to 6 months, and 3.04 degrees after 5 years. The individual variability of NHP reproducibility also increased over time. The standard deviation of the SN/vertical angulation was 2.61 degrees after 1 to 2 hours, 3.16 degrees after 3 to 6 months, and 4.20 degrees after 5 years. Further longitudinal data are required to determine whether NHP reproducibility continues to deteriorate after 5 years. After 5 years, however, the variance of NHP (9.24 degrees [= 3.04(2)]) remains significantly less than the variance of intracranial reference planes to the vertical (25 degrees to 36 degrees).

Cephalometry↗

PubMedDate not supplied

Sonicated echocardiographic contrast agents: reproducibility studies.

This article describes the production, analysis, and reproducibility of forming microbubbles for contrast ultrasound imaging. The sonication method used to generate microbubbles was tested by four independent observers, and a subsequent laser particle counter analysis of microbubble size and concentration determined the reproducibility of the method. The results indicated that the mean bubble size was 3.3 +/- 1.2 microns for the entire group, based on three trials of each of the four participants. The characteristics of the bubble size of the microbubbles between observers were assessed with a Poisson distribution with the reproducibility based on the sample mean for each observer's trials. Standardization and calibration of the laser particle counter was accomplished with commercially available latex spheres, sonicated albumin microspheres, and a Coulter counter analysis. Our results indicate that the sonication technique generates small microbubbles with a reproducible uniform size distribution. The method of microbubble production is reproducible and can be widely applied for use in contrast echocardiographic perfusion imaging of tissue in a variety of research and clinical studies.

Air↗

PubMed1997

Mid- and long-term reproducibility of noninvasive measurements of spontaneous arterial baroreflex sensitivity in healthy volunteers.

Baroreflex sensitivity (BRS) is altered in a variety of circumstances and could be considered as a marker for the prognosis of some cardiovascular diseases. The present study was designed to evaluate the reproducibility of noninvasive measures of BRS, both at mid- and at long-term. Fourteen healthy volunteers were examined on three occasions (first interval = 1 week, second interval = 1 year). Each recording was performed using a noninvasive photoplethysmographic device (Finapres 2300, Ohmeda), both in supine and standing positions. Two different methods of measurement were used: the sequences method and cross spectral analysis. The reproducibility of BRS measures was as satisfactory at mid- as at long-term for the sequences method (intraclass coefficient [ICC] = 0.87 and 0.86, respectively), but it was better at mid- than at long-term for the cross-spectral analysis (ICC = 0.85 and 0.54, respectively). The measures performed in standing position were obviously more reproducible than those made in recumbent position (ICC = 0.87 and 0.70 for the sequences method, 0.85 and 0.71 for the cross-spectral analysis, respectively). Due to the high reproducibility of these noninvasive measures, the number of patients to be included in a pharmacological study was calculated as rather small: for example, only 20 patients are required for detecting a change in upright BRS of 3 msec/mm Hg, at long-term (sequences method). Likewise, the magnitude of the regression to the mean, which has to be expected in patients selected for a follow-up study, turned out to be low: for example, <15% of the difference between the patient group mean value and the reference value, both at mid- and at long-term (standing position, sequences method). We conclude that: 1) The noninvasive measures of BRS in standing position are reproducible enough to allow longitudinal studies to be conducted over either a short or a long period; 2) The long-term reliability of the sequences method seems to be higher than that of the cross-spectral analysis; and 3) Subtle changes in SBR may be noninvasively detected within small patient groups.

Adult↗

PubMed1998

Examination of reproducibility in microbiological degradation experiments.

Experimental data indicate that certain microbiological degradation experiments have a limited reproducibility. Nine identical batch experiments were carried out on 3 different days to examine reproducibility. A pure culture, isolated from soil, grew with toluene as the only carbon and energy source. Toluene was degraded under aerobic conditions at a constant temperature of 28 degrees C. The experiments were modelled by a Monod model--extended to meet the air/liquid system, and the parameter values were estimated using a statistical nonlinear estimation procedure. Model reduction analysis resulted in a simpler model without the biomass decay term. In order to test for model reduction and reproducibility of parameter estimates, a likelihood ratio test was employed. The limited reproducibility for these experiments implied that all 9 batch experiments could not be described by the same set of parameter values. However, experiments carried out the same day (within the same run) were more uniform than experiments carried out on different days (between runs), and a common set of parameter estimates could be accepted for experiments within runs, but not for experiments from different runs. The limited reproducibility may be caused by variability in the preculture, or more precisely, variations in the physiological state of the bacteria in the precultures just before used as inoculum.

Biodegradation, Environmental↗

PubMed1998

Reproducibility of self-reported past body weight.

OBJECTIVE: To examine the reproducibility of self-reported past body weight for ages 25 and 40 y and effects influencing recall of body weight. DESIGN AND SUBJECTS: Repeated administration of a computer-guided interview including questions on past body weight for 25 and 40 y of age to 120 middle-aged participants of a validation study on dietary assessment methods at the EPIC-Potsdam study centre. Recall error was defined as difference in body weight reported in the second compared to the first interview. Reproducibility of recall of body weight was assessed by plotting the difference between the interviews against the mean of the recalled weight. Possible influences of sex, age, measured current body weight, current body mass index, and highest education attained on recall error were examined. RESULTS: Mean difference in recalled body weight was small, but variation of differences was considerable. Classification into recall error strata demonstrated reproducibility of weight recall within +/-3 kg for 75.8% for weight recall for age 25 y and 81.7% for age 40 y, respectively. Absolute recall error was not influenced by age, sex, current body weight, current BMI, and educational attainment. CONCLUSIONS: We observed a high degree of reproducibility of self-reported past body weight for ages 25 and 40 y between the two interviews administered. With respect to reproducibility administration of a single questionnaire or interview to obtain information on past body weight thus seems to be sufficient.

Adult↗

PubMed1997

Reproducibility of fat area measurements in young, non-obese subjects by computerized analysis of magnetic resonance images.

OBJECTIVE: To assess reproducibility, expressed as both inter-observer variability and intra-observer variability, of fat area measurements on images obtained by magnetic resonance (MR); to compare variability between fat area measurements, calculated from a single image per body region and from the average fat area of three images, and to determine reproducibility of image acquisition at the abdominal level. SUBJECTS: Thirty young, non-obese subjects (reproducibility of image analysis) and nine young, non-obese subjects (reproducibility of image acquisition). METHODS: Three MR images at the level of the abdomen (in 30 subjects) and at the level of the hip and thigh (in 14 of them). Quantification of subcutaneous fat depots (abdomen, hip and thigh) and visceral fat depots using an image-analyzing computer program. Assessment of variability of image analysis for fat area measurements between two observers and within observers. Assessment of reproducibility of image acquisition at the abdominal level (in nine subjects). RESULTS: Subcutaneous fat areas in all body regions were quantified with coefficients of variation (CV) ranging from only 2.1%-4.9%. By contrast, visceral fat area measurements showed markedly higher CVs (range: 9.4%-17.6%). Moreover, relative variability was much larger in small visceral fat areas (CVs up to 25.6%). The majority of CVs, calculated for intra-observer variability and calculated from the average fat area measurements of three images, was lower than calculated for inter-observer variability and for one single image, respectively. In particular, for the visceral fat depot, this reduction in variability had practical consequences for the number of subjects required for a study. Variation of repeated image acquisition was in the same range as variation of repeated measurements on the same image. CONCLUSION: One image per body site is sufficient to obtain a reliable estimate of subcutaneous fat depots. For estimations of the visceral fat depot, the average area measurements of three images reduces variability and increases statistical power. The availability of one single experienced observer during a study adds to accuracy.

Abdomen↗