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Results for “Reproducibility”

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At least 667 records · Page 37Linked to original sources

PubMed2003

Electrical impedance tomography to measure pulmonary perfusion: is the reproducibility high enough for clinical practice?

A possible clinical application of electrical impedance tomography (EIT) might be to monitor changes in the pulmonary circulation, provided the reproducibility of the EIT measurement is adequate. The purpose of this study was threefold: the intra- and inter-investigator variability of repeated measurements was investigated. Three different regions of interest (ROI) were analysed to assess the optimal ROI. Twenty-four healthy subjects and six patients were included. The Sheffield applied potential tomograph (DAS-01P, IBEES, Sheffield, UK) was used. Electrodes were attached by investigator A, and duplicate EIT measurements were performed. After detachment and 45 min of rest, the protocol was repeated by another investigator B, and afterwards by the initial investigator A. Three ROIs were analysed: whole circle, 'inner half circle' and contour. The mean difference in impedance changes between observers is presented in arbitrary units (AU) +/- SD. Finally, the influence of age, body composition and sex on the EIT result was examined. For the contour ROI, the mean difference for the intra-investigator situation was -1.44 x 10(-2) +/- 18.45 x 10(-2) AU (-0.7 +/- 9.0%), and was 5.46 x 10(-2) +/- 21.66 x 10(-2) AU (2.7 +/- 10.8%) for the inter-investigator situation. The coefficient of reproducibility of the intra- and inter-investigator reproducibility varied between 0.89 and 0.97 for all ROIs (P < 0.0001). There is a relation between impedance change and age (correlation coefficient r = -0.63, P < 0.01 for contour ROI), and between impedance change and body mass index (BMI) (r = -0.53, P < 0.05). We found a significant difference in mean impedance change between groups of males and females. In conclusion, EIT results are highly reproducible when performed by the same investigator as well as by two different investigators.

Adolescent↗

PubMed2003

Inhalation profiles in asthmatics and COPD patients: reproducibility and effect of instruction.

Turbuhaler and Salbutamol-Diskus produce therapeutic doses at peak inspiratory flow (PIF) of >30 L/min. However, the optimum flow for Fluticasone-Diskus and Turbuhaler, in terms of total emitted dose and fine particle mass, is >60 L/min. The Turbuhaler achieved a higher output at this flow, as compared to Diskus. For pMDI 25 < PIF < 90 L/min, an actuation time of 0.0-0.2 sec is optimal. The aim of this study was to examine the incidence of optimum inhalation profiles, the effect of instruction, reproducibility, and the relationship between inhalation profiles and patient characteristics in stable asthmatics and mild/moderate/severe COPD patients. For each device, triplicate inhalation profiles were recorded during 6 sessions in a 10-week period. All patients achieved PIF > 30 L/min using Diskus. After instruction, all Diskus inhalations were performed with >60 L/min, except 7% of the inhalations of the severe COPD patients. At least 95% of the Turbuhaler inhalations was also performed with the minimum flow; however, 19% of the inhalations of the severe COPD patients were not optimally performed. The hand-lung coordination was inadequate in 40% of pMDI inhalation profiles, and 80% was performed with a too high flow. The reproducibility of PIF of both dry powder inhalers (DPIs) was very high (coefficient of variation = 4-10%). The reproducibility of the pMDI variables was lower (coefficient of variation = 9-18%). The major lung function variables predictive for PIF(diskus) and PIF(turbuhaler) were maximal inspiratory mouth pressure (MIP), PIF, and inspiratory capacity. No significant predictive lung function variables for PIF(pMDI) were found. Most patients performed reproducible optimum inhalation profiles through Diskus and Turbuhaler. However, in the severe COPD group, 7-19% of the patients were not able to generate the optimum flows through the DPIs. For these patients, a flow-independent aerosol delivery system might be more suitable. The majority of patients were using the pMDI incorrectly. Instruction had no effect. So, we concluded that the pMDI should not be used in these patient groups because of the coordination problems.

Administration, Inhalation↗

PubMed2000

Somatostatin-receptor scintigraphy in Graves' disease: reproducibility and variance of orbital activity.

Somatostatin-receptor (SSTR) scintigraphy using the single photon emission computed tomography (SPECT) technique allows the assessment of orbital inflammation in patients with Graves' disease. Previous studies showed differences in orbital octreotide uptake already 4 hr after injection. In this study, analysis of inter-/intra-observer variance and reproducibility in the evaluation of orbital SPECT images was performed. First, SPECT data of one representative female patient with clinically active Graves' ophthalmopathy (GO), obtained 4 hr after intravenous injection of 110 MBq 111In-pentetreotide and processed by filtered backprojection, were analyzed. Transverse SPECT images were reconstructed, an optimal orbital image was selected and predetermined regions of interests (ROIs) for both orbits were positioned by three independent observers 15 to 19 times each. In a second step, SPECT data of 8 different patients with GO were evaluated in the same manner by four independent observers 3 to 4 times each. Variance component partitioning was used to compare the order of intra- and inter-observer variation. For the right and the left orbit, the inter-observer variance proportion was 90% and 79%, whereas intra-observer variance partition was 10% and 21%, respectively. The corresponding ratios 0.11 and 0.27 summarize the comparison of sources of variance. The overall reliability was 84%, representing the patients influence on the total variance. Intra-observer reliability for both orbits was 88%, 89%, 97% and 98% (mean over orbits), respectively for observers I to IV. Using the Spearman Brown prophecy formula it follows that two replications per patient are sufficient to ensure a minimum reproducibility of 90%, which is also confirmed by the low intra-observer variation. Furthermore, intra-class correlation as a measure of (multiple) observer reproducibility was 94%. In conclusion, due to the increased inter-observer variance proportion and the high variation in intra-observer reliability, evaluations of orbital SSTR scintigraphy have to be done by the same and experienced observer leading to comparable data. But an automatic and quantitative computerized technique for evaluation of these SPECT data should be exactly reproducible and probably lead to more accurate and representative results.

Adult↗

PubMed2006

Reproducible epidemiologic research.

The replication of important findings by multiple independent investigators is fundamental to the accumulation of scientific evidence. Researchers in the biologic and physical sciences expect results to be replicated by independent data, analytical methods, laboratories, and instruments. Epidemiologic studies are commonly used to quantify small health effects of important, but subtle, risk factors, and replication is of critical importance where results can inform substantial policy decisions. However, because of the time, expense, and opportunism of many current epidemiologic studies, it is often impossible to fully replicate their findings. An attainable minimum standard is "reproducibility," which calls for data sets and software to be made available for verifying published findings and conducting alternative analyses. The authors outline a standard for reproducibility and evaluate the reproducibility of current epidemiologic research. They also propose methods for reproducible research and implement them by use of a case study in air pollution and health.

Air Pollution↗

PubMed2026

Assessing reproducibility of Hi-C chromatin interactions using stratum-adjusted irreproducible discovery rate.

MOTIVATION: Hi-C is a powerful technology for mapping chromatin interactions genome-wide. However, interaction loops identified from Hi-C contact maps often vary across replicate experiments due to experimental noise, making reproducibility assessment essential. A major challenge lies in the genomic distance dependence of interaction strength, which systematically affects reproducibility but is overlooked by existing methods for reproducibility assessment. RESULTS: We introduce Stratum-Adjusted Irreproducible Discovery Rate (SIDR), a novel statistical model that integrates distance stratification into the widely-used Irreproducible Discovery Rate (IDR) framework. SIDR explicitly models the confounding effect of genomic distance, enabling global control of irreproducibility across interaction ranges. Through simulations and real Hi-C datasets, we demonstrate that SIDR improves discriminative power and recovers more biologically meaningful interactions than existing approaches, making it a valuable tool for robust and reproducible Hi-C analysis. AVAILABILITY: The R package SIDR is freely available on GitHub https://github.com/qunhualilab/SIDR.

Chromatin↗

PubMed1998

Reproducibility of cephalometric landmarks on conventional film, hardcopy, and monitor-displayed images obtained by the storage phosphor technique.

The aim of the present study was to evaluate and compare the reproducibility of cephalometric landmarks on (1) conventional films, and images acquired by storage phosphor digital radiography both on (2) hardcopy and (3) monitor-displayed versions. The material consisted of 19 cephalograms for each image modality. The phosphor plates were scanned in an image reader and the 10-bit normalized, raw data digital images were converted to 8-bit TIFF images for PC monitor-display. The digital hardcopies were produced in a laser printer. Six observers were asked to record 21 cephalometric landmarks on each conventional film, hardcopy, and monitor-displayed image. For the films and hardcopies, the landmark co-ordinates were recorded via a digitizing tablet. For the monitor-displayed images, the co-ordinates were recorded directly from the monitor using a dedicated Windows-based cephalometric program. Reproducibility was defined as an observer's deviation (in mm) from the mean between all observers. Differences between the image modalities and between the observers were tested by two-way analysis of variance for each landmark. There was a statistically significant difference between the reproducibility of film, hardcopy and monitor-displayed images in 11 of the 21 landmarks. There was no unequivocal trend that one modality was always the best. For a full cephalometric recording (the sum of all 21 landmarks), the monitor-displayed images (mean = 25.3 mm) had a lower precision than film (P < 0.005) and hard-copy (P < 0.02). There was no significant difference between film (mean = 21.8 mm) and hardcopy (mean = 22.8 mm). The lower reproducibility seen for the monitor-displayed images is most probably of little clinical significance.

Adolescent↗

PubMed2003

Comparative reproducibility of three methods of radiographic assessment of alveolar bone grafting.

The aims of this study were to compare the reproducibility of three radiographic methods of assessing the quality of alveolar bone grafts, namely the Bergland, Kindelan and Chelsea Scales, and evaluate their application in the mixed and permanent dentitions. Additionally the use of occlusal versus periapical radiographs was assessed. Three examiners applied each scale on two occasions to the radiographs of 48 cleft lip and palate patients who had received alveolar bone grafts in 59 sites (11 had bilateral clefts). The agreement between repeated assessments by the same observer at different time points was measured by the kappa statistic, for each of the three assessors and each of the types of radiographic scale in turn. None of the three scales was found to be more reproducible than the others (kappa statistics for intraobserver variation ranged from 0.61 to 0.70). The agreement between observers was also similar across the three radiographic scales (multiple kappa statistics for inter-observer variation ranged from 0.45 to 0.51). Likewise, neither occlusal nor periapical radiographs were found to enable greater reproducibility of assessment. Surprisingly there was a tendency to greater reproducibility in the mixed than in the permanent dentition, which suggests the outcome of alveolar bone grafting may be assessed at an earlier stage than currently adopted. The outcome of alveolar bone grafting in this group of patients was generally successful.

Alveolar Process↗

PubMed2005

A measuring system for facial aesthetics in Caucasian adolescents: reproducibility and validity.

A new measuring system to judge facial aesthetics in young Caucasians is presented. The system uses sets of three photographs (one frontal, one three-quarter smiling, and one lateral) as a stimulus. Scores are performed on a visual analogue scale (VAS) with separate sets of reference photographs for girls and boys. The choice of the reference photographs was based on a panel evaluation of facial aesthetics of 40 boys and 40 girls from the archive of the orthodontic department. Reproducibility of the new measuring system was tested on a series of photographic sets (one frontal, one three-quarter smiling, and one lateral view) of 64 patients, using a panel of 78 adult laymen and 89 professionals. The panel members assessed these sets of photographs on a VAS, in relation to the reference sets. The system was shown to be reproducible. Although the intra-observer reproducibility was low, the reliability coefficient was excellent (Cronbach's alpha > or = 0.98). Validity was tested by comparing the scores on the new scales with those of the three-quarter smiling photographic views on an earlier published scale. The correlation between the ratings on the new measuring system and the earlier published scale was 0.82 for laymen and 0.77 for professionals. The new system is simple and flexible in its use, and reproducible and valid for assessing facial aesthetics in young Caucasians. The system can be used in further investigations on the evaluation of facial aesthetics.

Adolescent↗

PubMed2005

Reproducibility of 3D free-breathing magnetic resonance coronary vessel wall imaging.

AIMS: Although the coronary artery vessel wall can be imaged non-invasively using magnetic resonance imaging (MRI), the in vivo reproducibility of wall thickness measures has not been previously investigated. Using a refined magnetization preparation scheme, we sought to assess the reproducibility of three-dimensional (3D) free-breathing black-blood coronary MRI in vivo. METHODS AND RESULTS: MRI vessel wall scans parallel to the right coronary artery (RCA) were obtained in 18 healthy individuals (age range 25-43, six women), with no known history of coronary artery disease, using a 3D dual-inversion navigator-gated black-blood spiral imaging sequence. Vessel wall scans were repeated 1 month later in eight subjects. The visible vessel wall segment and the wall thickness were quantitatively assessed using a semi-automatic tool and the intra-observer, inter-observer, and inter-scan reproducibilities were determined. The average imaged length of the RCA vessel wall was 44.5+/-7 mm. The average wall thickness was 1.6+/-0.2 mm. There was a highly significant intra-observer (r=0.97), inter-observer (r=0.94), and inter-scan (r=0.90) correlation for wall thickness (all P<0.001). There was also a significant agreement for intra-observer, inter-observer, and inter-scan measurements on Bland-Altman analysis. The intra-class correlation coefficients for intra-observer (r=0.97), inter-observer (r=0.92), and inter-scan (r=0.86) analyses were also excellent. CONCLUSION: The use of black-blood free-breathing 3D MRI in conjunction with semi-automated analysis software allows for reproducible measurements of right coronary arterial vessel-wall thickness. This technique may be well-suited for non-invasive longitudinal studies of coronary atherosclerosis.

Adult↗

PubMed1997

Estimation of reproducibility and relative validity of the questions included in the EPIC Physical Activity Questionnaire.

BACKGROUND: The EPIC core questionnaire on lifestyle contains a number of questions on physical activity designed to rank subjects according to level of physical activity (short PA questionnaire). These questions are based on a more extensive questionnaire designed to measure absolute total energy expenditure (extensive PA questionnaire), that was validated in a pilot study preceding EPIC. Reproducibility and relative validity of the short PA questionnaire were estimated by selecting, from the pilot study data, the answers to a number of questions from the extensive questionnaire that resembled those actually included in the short version. METHODS: The population of the pilot study consisted of 126 men and women aged between 20 and 70 years. Reproducibility was estimated by administering the extensive questionnaire three times: at baseline, and after 5 and 11 months. In order to determine the relative validity of the extensive questionnaire, a 3-day activity diary, repeated four times, was used as the reference method. RESULTS: Over the study period (13 months), mean absolute energy expenditure, estimated from the questions included in the short questionnaire, was fairly constant in men but not in women. REPRODUCIBILITY: Spearman correlation coefficients ranged from 0.47 to 0.89 in men, and from 0.49 to 0.81 in women. RELATIVE VALIDITY: Spearman correlation coefficients between the short questionnaire and the diary were between 0.32 and 0.81 for men, and between 0.28 and 0.72 for women. CONCLUSIONS: The questions selected for the short questionnaire are not suitable for estimating energy expenditure at an absolute level. Reproducibility and relative validity of the ranking of subjects seemed satisfactory and comparable to the extensive questionnaire. The results imply that the short questionnaire is suitable for ranking subjects in the EPIC study.

Adult↗

PubMed1997

Reproducibility and relative validity of food group intake in a food frequency questionnaire developed for the German part of the EPIC project. European Prospective Investigation into Cancer and Nutrition.

BACKGROUND: For the German part of the European Prospective Investigation into Cancer and Nutrition (EPIC), a self-administered, optically-readable food frequency questionnaire (FFQ), including 158 food items and 87 coloured portion size photographs, was developed to assess the usual food and nutrient intake of individuals during the past year. In 1991/1992, the reproducibility and validity of the questionnaire measurements were studied according to the EPIC protocol. This article reports the results on reproducibility and relative validity of measurement of food group intake. METHODS: A total of 104 men and women aged 35-64 years, who are members of the local health insurance institution, AOK Heidelberg, participated in this study. Reproducibility of the questionnaire measurements was obtained by a repeated administration of the FFQ to the same study subjects at a 6-month interval. The mean of 12 24-hour dietary recalls applied at monthly intervals served as reference method for the estimation of the relative validity of questionnaire measurements. A second version of the FFQ that integrated questions on general food consumption patterns was also investigated. RESULTS: Spearman test-retest correlations of food group intake ranged from 0.49 for bread to 0.89 for alcoholic beverages (median = 0.70). Spearman correlations between food group intake values derived from the 24-hour diet recalls and the FFQ completed in the summer of 1992 varied from 0.14 for legumes to 0.90 for alcoholic beverages (median = 0.45). Correction for attenuation due to within-person error in the reference method as well as the correction for general consumption patterns improved the correlations. CONCLUSION: The results indicate that our newly developed FFQ gives reproducible estimates of food group intake. Large day-to-day variation in food group intake complicated the evaluation of FFQ validity. Overall, moderate levels of relative validity were observed for estimates of food group intake.

Adult↗

PubMed2005

Signal in noise: evaluating reported reproducibility of serum proteomic tests for ovarian cancer.

Proteomic profiling of serum initially appeared to be dramatically effective for diagnosis of early-stage ovarian cancer, but these results have proven difficult to reproduce. A recent publication reported good classification in one dataset using results from training on a much earlier dataset, but the authors have since reported that they did not perform the analysis as described. We examined the reproducibility of the proteomic patterns across datasets in more detail. Our analysis reveals that the pattern that enabled successful classification is biologically implausible and that the method, properly applied, does not classify the data accurately. We show that the method used in previously published studies does not establish reproducibility and performs no better than chance for classifying the second dataset, in part because the second dataset is easy to classify correctly. We conclude that the reproducibility of the proteomic profiling approach has yet to be established.

Female↗

PubMed1995

Reproducibility of fine-needle aspiration biopsy in the diagnosis of acute rejection of renal allografts.

BACKGROUND: Although it has been used as a diagnostic tool in many renal transplant centres the reproducibility of fine-needle aspiration biopsy (FNAB) has not been critically evaluated. METHODS: In the present study material sequentially obtained from 15 patients (177 aspirations) over a 3-month period following renal transplantation was evaluated by two independent observers. Intraobserver reproducibility was studied through the analysis of two evaluations by observer 1 performed 8 months apart. Interobserver reproducibility was calculated comparing the second evaluation of observer 1 with the evaluation of observer 2. All evaluations were performed blindly. Slides and protocols of individual patients were chronologically arranged and thus interpreted. Representation, total corrected increment (TCI), accuracy, and the percent agreement for the diagnosis of acute rejection were evaluated. RESULTS: No intraobserver statistically significant differences were observed. Differences observed in interobserver evaluation of TCI either during, or out of acute rejection episodes, well as the representative quality of the sample and accuracy, were not statistically significant. The percent of agreement for the presence or absence of acute rejection was 77.5% for the intraobserver comparison and 76.7% for the interobserver evaluation. Both values showing either a non-significant value for the difference or a statistical significance for the concordance. CONCLUSION: We concluded that FNAB is an accurate method with fairly good intra- and interobserver reproducibility for the diagnosis of acute rejection of renal allografts.

Acute Disease↗

PubMed1992

Dietary assessment of older Iowa women with a food frequency questionnaire: nutrient intake, reproducibility, and comparison with 24-hour dietary recall interviews.

The authors report the results of a dietary survey of 38,121 Iowa women, 55-69 years of age in 1986, based on a semiquantitative food frequency questionnaire previously tested among Boston-area women aged 34-59 years. The Iowa women, compared with the younger Boston-area women, consumed a similar amount of calories (1,767 vs. 1,844 kcal) and a similar amount of total calories from fat (35 vs. 37%) but had markedly greater intake of the following micronutrients after including supplement use: iron (+18%), calcium (+33%), vitamin A (+43%), riboflavin (+46%), thiamine (+50%), and pyridoxine (+122%). The reproducibility of the questionnaire was examined in two more administrations to 44 of the Iowa women in January and June of 1988. Reproducibility was highest for alcohol (Pearson's r = 0.99), caffeine (r = 0.95), and vitamin E (r = 0.90) and lowest for sucrose (r = 0.53), polyunsaturated fat (r = 0.56), and iron (r = 0.59). Micronutrient intakes were generally more reproducible than macronutrient intakes. The agreement between the June 1988 questionnaire and the average of five 24-hour dietary recalls was also assessed in the 44 subjects. The median correlations of energy-adjusted intake were as follows: for macronutrients, r = 0.45; for micronutrients without supplements, r = 0.33; and for micronutrients with supplements, r = 0.64. This food frequency questionnaire appears to be reasonably reproducible and accurate, so that its use may be extended to epidemiologic studies of older women with a broad range of socioeconomic backgrounds.

Energy Intake↗

PubMed2003

International variation in histologic grading is large, and persistent feedback does not improve reproducibility.

Histologic grading systems are used to guide diagnosis, therapy, and audit on an international basis. The reproducibility of grading systems is usually tested within small groups of pathologists who have previously worked or trained together. This may underestimate the international variation of scoring systems. We therefore evaluated the reproducibility of an established system, the Banff classification of renal allograft pathology, throughout Europe. We also sought to improve reproducibility by providing individual feedback after each of 14 small groups of cases. Kappa values for all features studied were lower than any previously published, confirming that international variation is greater than interobserver variation as previously assessed. A prolonged attempt to improve reproducibility, using numeric or graphical feedback, failed to produce any detectable improvement. We then asked participants to grade selected photographs, to eliminate variation induced by pathologists viewing different areas of the slide. This produced improved kappa values only for some features. Improvement was influenced by the nature of the grade definitions. Definitions based on "area affected" by a process were not improved. The results indicate the danger of basing decisions on grading systems that may be applied very differently in different institutions.

Europe↗

PubMed1994

A study of the reproducibility of long-term recall in the elderly.

We assessed reproducibility of long-term recall (over periods of up to 82 years) by repeat interviews 1-3 months apart in 63 people age 65-95 years. We assessed weight, height, physical activity, smoking, reproductive factors, and consumption of alcohol, coffee, tea, milk, cheese, and fruit. Reproducibility was acceptable for most variables. Spearman rank correlation coefficients ranged from 0.95 to 0.36; kappas ranged from 0.97 to 0.35. Past physical activity was the least reproducible variable. Older age, cognitive impairment, and male gender were associated with reduced reproducibility.

Age Factors↗

PubMed1989

Reproducibility in the analysis of multigated radionuclide studies of left ventricular ejection fraction.

The authors determined the reproducibility (the standard deviation [SD]) in the analysis of multigated radionuclide studies of left ventricular ejection fraction (LVEF). Radionuclide studies from a consecutive series of 38 patients suspected of ischemic heart disease were analyzed independently by four nuclear medicine physiologists and four laboratory technicians. Each study was analyzed three times by each of the observers. Based on the analyses of the eight observers, the SD could be estimated by the use of a variance component model for LVEF determinations calculated as the average of the analyses of an arbitrary number of observers making an arbitrary number of analyses. This study presents the SDs for LVEF determinations based on the analyses of one to five observers making one to five analyses each. The SD of a LVEF determination decreased from 3.96% to 2.98% when an observer increased his number of analyses from one to five. A more pronounced decrease in the SD from 3.96% to 1.77% was obtained when the LVEF determinations were based on the average of a single analysis made by one to five observers. However, when dealing with the difference between LVEF determinations from two studies, the highest reproducibility was obtained if the LVEF determinations at both studies were based on the analyses made by the same observer. No significant difference was found in the reproducibility of analyses made by nuclear medicine physicians and laboratory technicians. Our study revealed that to increase the reproducibility of LVEF determinations, special efforts should be made to standardize the outlining of the end-systolic region interest.

Adult↗

PubMed1996

Color duplex measurement of cerebral blood flow volume: intra- and interobserver reproducibility and habituation to serial measurements in normal subjects.

Color duplex flowmetry of internal carotid and vertebral arteries permits estimation of intravascular flow volumes and global cerebral blood flow volume (CBFV) by summing the flow volumes measured in each of the four extracranial vessels. Intravascular flow volumes were calculated as the product of angle-corrected time-averaged flow velocity and the cross-sectional area of the vessel. The reliability of this new method was tested in a prospective, intra- and interdiane, intra- and interobserver reproducibility study of 32 healthy subjects aged 7-57 years. In each subject, CBFV was tested by each observer twice on day 1 and once on day 2 in consecutive recordings. In each artery, both examiners found closely similar mean intravascular flow volumes. Intradiane interobserver reproducibility of CBFV was high on both days (correlation coefficient, CC, 0.90 and 0.85, p < or = 0.0001; coefficient of variance, CV, 10.0 and 10.4%, respectively), as was the interdiane comparison (CC = 0.81, p < or = 0.0001; CV < or = 13.3%). Intraobserver reproducibility was even higher. On both days, there was a progressive decrease in CBFV from each subject's first to the last examination within a 1-h examination period (day 1: 717 +/- 150 ml/min to 690 +/- 120 ml/min; difference, p < or = 0.05; day 2: 700 +/- 120 ml/min to 665 +/- 126 ml/min; difference, p < or = 0.01). This habituation effect was more pronounced in subjects with high initial CBFV. Reproducibility of CBFV is comparable to that of mean CBF measurements with 133Xe inhalation and H2 15(O) positron emission tomography techniques reported by other groups. This method makes serial bedside-monitoring of CBFV feasible without posing the risks of radiation exposure.

Adolescent↗