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At least 235 records · Page 13Linked to original sources
PubMed1999

The reproducibility of repeat measures of airway inflammation in stable atopic asthma.

Measures of airway inflammation are increasingly being used as outcome measures in asthma intervention studies. Meaningful interpretation of observed changes in bronchial mucosal cell numbers should depend, in part, on the reproducibility of repeat measures over time. We wanted to investigate the reproducibility of immunopathologic and physiologic parameters after short and long measurement intervals. We therefore performed spirometry, bronchial provocation challenge, and fiberoptic bronchoscopy with endobronchial biopsy (always right upper lobe second-generation bronchus) at baseline, after 2 wk, and again after 8 wk on nine subjects with stable atopic asthma (receiving inhaled placebo and beta-agonist therapy only). Numbers of T cells, memory T cells (CD45Ro(+)), macrophages (CD68(+)), and eosinophils (EG1(+) and EG2(+)) on immunohistochemical stains of bronchial biopsies were quantified by computerized image analysis. Intraclass correlation coefficients (ICCs) of reproducibility were calculated for repeat measures of each parameter and a high ICC (greater than 0.6) was interpreted as "highly reproducible." Repeat measures of FEV(1), FEF(25-75%), and PC(20) were highly reproducible after short (2-wk) and long (8-wk) intervals. Only repeat measures of EG2(+) had an ICC greater than 0.6 after 8 wk. Repeat measures of CD45Ro(+), EG2(+), and T cell numbers (but not CD68(+) and EG1(+) cells) are highly reproducible and reliable parameters of asthmatic airway inflammation after a 2 wk interval.

Adolescent↗
PubMed2002

Reproducibility of blind protected bronchoalveolar lavage in mechanically ventilated children.

Blind protected bronchoalveolar lavage (BAL) could be an interesting tool in the diagnosis of ventilator-associated pneumonia in intubated children, but its reproducibility has never been evaluated. This study evaluates the reproducibility, feasibility, and safety of blind protected BAL in mechanically ventilated children. Two blind protected BAL were done, at a 2-hour interval, in 30 patients. The reproducibility of microbiologic and cytologic results was studied. A total of 60 BALs was analyzed. Bacterial growth was present in 26 of 60 BAL (43%). Reproducibility for the presence of bacteria on quantitative cultures was excellent (concordance, 93%; kappa [kappa], 0.86). Concordance for the type of bacteria isolated was 86% and for the number of bacteria was 79%. Reproducibility for the presence of neutrophils containing bacteria was perfect (concordance, 100%; kappa, 1) although only a few BALs had a positive result (8/60). Blind protected BAL was feasible in all patients and all samples were considered adequate for analysis. Complications were mostly benign and transitory except in two cases: one pneumothorax and one significant increase in intracranial pressure. Overall, blind protected BAL is a reproducible test in mechanically ventilated children, is easily feasible, and is usually well tolerated.

Adolescent↗
PubMed2001

Are reliability, reproducibility and validity the correct terms to assess the correctness of dietary studies?

Nutritional studies often use the terms reliability, reproducibility and validity to indicate the correctness of the study. These terms do not appear to have a universal meaning to all researchers. The components of a dietary study are the input, the data collection instrument and the compiled data. Frequently the data collection questionnaire/tool/instrument is tested for reliability, reproducibility or validity. The data collection questionnaire/tool/instrument is simply a structure, a vehicle for gathering data. An argument is presented that demonstrates the reasons that such a structure cannot be tested for reliability, reproducibility or validity. The logical approach to the use of the terms reliability, reproducibility and validity is presented. Reliability refers to the input component of the study, reproducibility may or may not lead to strengthening the study and validity refers to the truthfulness of the database generated. Validity must be derived from reliable and reproducible data.

Diet Surveys↗
PubMed1998

Sources of variability in the reproducibility of food frequency questionnaires.

The reproducibility of food frequency questionnaires varies widely. Since reports of past intake are known to be biased toward the present and the forces of supply and demand affect what people eat at a given point in time, the questionnaire may capture an atypical snapshot of consumption rather than the intended view of unusual consumption. The consumption of regularly consumed foods is the same throughout the year. The consumption of these foods is likely to be highly reproducible at another point in time. The consumption of seasonally consumed foods, however, fluctuates throughout the year, and may have peaks in winter or summer or particular holidays. There may be no common denominator among these foods necessary for the purpose of assessing reproducibility. Therefore, questionnaires that contain a combination of regularly and seasonally consumed foods, will be likely to have problems with reproducibility, the variance depending upon the number of seasonally consumed foods in the questionnaire. This explanation for variability in reproducing food frequency questionnaires raises a question about the importance of assessing reproducibility as a way of evaluating the worth of questionnaires. Perhaps an improved method of collecting data for seasonal foods is what is really needed to improve the quality of data collected.

Analysis of Variance↗
PubMed2004

Reproducibility of plantar pressure measurements in patients with chronic arthritis: a comparison of one-step, two-step, and three-step protocols and an estimate of the number of measurements required.

BACKGROUND: Plantar pressure measurement may be a helpful evaluation tool in patients with foot complaints. Determination of dynamic pressure distribution under the foot may give information regarding gait, progress of disorders, and the effect of treatment. However, for these measurements to have clinical application, reproducibility, consistency, and accuracy must be ascertained. We compared the reproducibility of measurements among one-step, two-step, and three-step protocols for data collection in patients with arthritis. In addition, the number of measurements needed for a consistent average was determined for the protocol that was found to be the most reproducible. METHODS: Twenty patients with foot complaints secondary to arthritis participated in the study. Each patient was tested with a pressure platform system using two of the three testing protocols. Reproducibility of contact time and maximal peak pressure were assessed. Intraclass Correlation Coefficients (ICC) were calculated for measurement results among protocols. In stage two of the study, the number of measurements needed for a consistent average was determined by calculating the first three measurements, the first five measurements, and then all seven measurements for both feet. ICC of three, five, and seven measurements were compared. The two-step protocol (13 patients), which was found in stage one of the study to be the most reproducible, was used for this determination. RESULTS: Reproducibility was found to be reasonable or good for all three measurement protocols. The mean values of contact time for the one-step protocol were found to be higher than the mean values of contact time for the two-step or three-step protocols in both feet. The differences between the one-step and three-step protocols were statistically significant for the left foot only. The mean peak pressure did not show statistically-significant differences among the three protocols. The one-step and three-step protocols were not used for stage two of the study. Using the two-step protocol, three measurements were found to be sufficient for obtaining a consistent average. CONCLUSIONS: The results of our study indicated that the one-step, two-step, and three-step protocols of collecting plantar pressure measurements in patients with foot complaints secondary to chronic arthritis were all similar. However, the use of the two-step protocol is recommended over the one-step and three-step protocols; the one-step protocol produced a longer stance phase that did not resemble normal walking and when comparing the two-step and three-step protocols, the two-step protocol was less time consuming and less strenuous for patients with painful feet.

Adolescent↗
PubMed2006

Diagnostic accuracy of the neurological upper limb examination I: inter-rater reproducibility of selected findings and patterns.

BACKGROUND: We have previously assessed the reproducibility of manual testing of the strength in 14 individual upper limb muscles in patients with or without upper limb complaints. This investigation aimed at additionally studying sensory disturbances, the mechanosensitivity of nerve trunks, and the occurrence of physical findings in patterns which may potentially reflect a peripheral neuropathy. The reproducibility of this part of the neurological examination has never been reported. METHODS: Two blinded examiners performed a semi-quantitative assessment of 82 upper limbs (strength in 14 individual muscles, sensibility in 7 homonymous territories, and mechanosensitivity of nerves at 10 locations). Based on the topography of nerves and their muscular and cutaneous innervation we defined 10 neurological patterns each suggesting a focal neuropathy. The individual findings and patterns identified by the two examiners were compared. RESULTS: Strength, sensibility to touch, pain and vibration, and mechanosensitivity were predominantly assessed with moderate to very good reproducibility (median kappa-values 0.54, 0.69, 0.48, 0.58, and 0.53, respectively). The reproducibility of the defined patterns was fair to excellent (median correlation coefficient = 0.75) and the overall identification of limbs with/without pattern(s) was good (kappa = 0.75). CONCLUSION: This first part of a study on diagnostic accuracy of a selective neurological examination has demonstrated a promising inter-rater reproducibility of individual neurological items and patterns. Generalization and clinical feasibility require further documentation: 1) Reproducibility in cohorts of other composition, 2) validity with comparison to currently applied standards, and 3) potential benefits that can be attained by the examination.

Adult↗
PubMed2005

Validity and reproducibility of arterial pulse wave velocity measurement using new device with oscillometric technique: a pilot study.

BACKGROUND: Availability of a range of techniques and devices allow measurement of many variables related to the stiffness of large or medium sized arteries. There is good evidence that, pulse wave velocity is a relatively simple measurement and is a good indicator of changes in arterial properties. The pulse wave velocity calculated from pulse wave recording by other methods like doppler or tonometry is tedious, time-consuming and above all their reproducibility depends on the operator skills. It requires intensive resource involvement. For epidemiological studies these methods are not suitable. The aim of our study was to clinically evaluate the validity and reproducibility of a new automatic device for measurement of pulse wave velocity that can be used in such studies. METHODS: In 44 subjects including normal healthy control and patients with coronary artery disease, heart brachial, heart ankle, brachial ankle and carotid femoral pulse wave velocities were recorded by using a new oscillometric device. Lead I and II electrocardiogram and pressure curves were simultaneously recorded. Two observers recorded the pulse wave velocity for validation and one observer recorded the velocity on two occasions for reproducibility. RESULTS AND DISCUSSION: Pulse wave velocity and arterial stiffness index were recorded in 24 control and 20 coronary artery disease patients. All the velocities were significantly high in coronary artery disease patients. There was highly significant correlation between the values noted by the two observers with low standard deviation. The Pearson's correlation coefficient for various velocities ranged from (r = 0.88-0.90) with (p < 0.0001). The reproducibility was also very good as shown by Bland-Altman plot; most of the values were lying within 2 SD. The interperiod measurements of pulse wave velocity were also significantly correlated (r = 0.71-0.98) (P < 0.0001). Carotid-femoral pulse wave velocity was found to correlate significantly with heart brachial, heart ankle, brachial ankle pulse wave velocity and arterial stiffness index values. Reproducibility of our method was good with very low variability in both interobserver and interperiod analysis. CONCLUSION: The new device "PeriScope" based on oscillometric technique has been found to be a simple, non-invasive and reproducible device for the assessment of pulse wave velocity and can be used to determine arterial stiffness in large population based studies.

Adult↗
PubMed2003

Reproducibility of quantitative dynamic contrast-enhanced MRI in newly presenting glioma.

We have investigated the reproducibility of dynamic contrast enhanced imaging techniques in nine patients with cerebral glioma. Patients were imaged twice with a 2 day interval between scans. Maps were produced of the time taken to achieve 90% enhancement (T90), the maximal intensity change per time interval ratio (MITR), the volume transfer coefficient between plasma and the extravascular extracellular space (K(trans)) and the extravascular extracellular contrast distribution volume, v(e). Measurements of K(trans) greater than 1.2 min(-1) were used to exclude pixels where first pass perfusion effects dominated the measurement. Measures of the test-retest coefficient of variation (CoV) and intraclass correlation coefficients were used to assess reproducibility for measurements from a volume of interest containing enhancing tissue from the whole tumour. MITR showed poor reproducibility (mean CoV 17.9%, 95% confidence limits for group comparisons 20.2%). T90 showed good reproducibility (mean CoV 7.1%, 95% confidence limits for group comparisons 5.2%). Calculated values of K(trans) and v(e) also showed good reproducibility (mean CoV 7.7% and 6.2% respectively, 95% confidence limits for group comparisons 6.2% and 4.8%, respectively). We conclude that the measurements of K(trans) and v(e) derived from pharmacokinetic analysis are sufficiently reproducible to support their use as a biological markers in therapeutic trials.

Aged↗
PubMed1999

A comparison of the reproducibility and the sensitivity to change of visual analogue scales, Borg scales, and Likert scales in normal subjects during submaximal exercise.

OBJECTIVE: To assess which subjective scale, the visual analogue scale (VAS), the Borg CR10 (Borg) scale, or the Likert scale (LS), if any, is decidedly more reproducible and sensitive to change in the assessment of symptoms. DESIGN: Prospective clinical study. SETTING: Exercise laboratory. PARTICIPANTS: Twenty-three physically active male subjects (mean +/- SD age of 30 +/- 4 years old) were recruited. INTERVENTION: Each subject attended the exercise laboratory on four occasions at intervals of 1 week. Three subjective scales were used: (1) the VAS (continuous scale); (2) the Borg scale (12 fixed points); and (3) the Likert scale (LS; 5 fixed points). Four identical submaximal tests were given (2 min at 60% maximum oxygen uptake [VO(2)max] and 6 min at 70% VO(2)max). Two tests were undertaken to assess the reproducibility of scores that were obtained with each subjective scale. Two other tests were undertaken to assess the sensitivity of each scale to a change in symptom perception: a double-blind treatment with propranolol, 80 mg, (ie, active therapy; to increase the sensation of breathlessness and general fatigue during exercise) or matching placebo. The subjective scale scores were measured at 1 min 30 s, 5 min 30 s, and 7 min 15 s of exercise. Reproducibility was defined as the proportion of total variance (ie, between-subject plus within-subject variance) explained by the between-subject variance given as a percentage. Sensitivity was defined as the effect of the active drug therapy over the variation within subjects. RESULTS: Overall, the VAS performed best in terms of reproducibility for breathlessness and general fatigue, with reproducibility coefficients as high as 78%. For sensitivity, the VAS was best for breathlessness (ratio, 2.7) and the Borg scale was most sensitive for general fatigue (ratio, 3.0). The relationships between the respective psychological and physiologic variables were reasonably stable throughout the testing procedure, with overall typical correlations of 0.73 to 0.82 CONCLUSION: This study suggests that subjective scales can reproducibly measure symptoms during steady-state exercise and can detect the effect of a drug intervention. The VAS and Borg scales appear to be the best subjective scales for this purpose.

Adrenergic beta-Antagonists↗
PubMed1990

Long-term reproducibility of tests of small airways function. Comparisons with spirometry.

We used a tracking index to measure the reproducibility of single breath nitrogen test variables (CV/VC, CC/TLC, delta N2/L) and spirometric variables (FEV1 and FEV1/FVC) and to compare the characteristics of individuals whose pulmonary function tracks well with those whose pulmonary function tracks poorly. Data were derived from two cohorts followed longitudinally over a 9-11 year period. All variables were adjusted for age, sex and height by expressing them as Z-scores. In all smoking groups and in both cohorts, the tracking index was highest for FEV1, indicating that this variable was the most reproducible over the period of follow-up; delta N2/L and FEV1/FVC had very similar but slightly lower tracking indices; CV/VC consistently had the lowest tracking indices. Tracking indices were generally higher in smokers than in nonsmokers. The reproducibility of CC/TLC increased over the period of follow-up whereas the FEV1 reproducibility remained constant. We found no significant difference between those with high tracking indices and those with low indices in terms of sex, smoking status, prevalence of respiratory symptoms, history of respiratory disease, and rate of decline of FEV1. We conclude that FEV1 is the most reproducible of the variables examined, both within and between individuals, and that poor tracking or reproducibility are not related to smoking or to the presence of respiratory symptoms or disease.

Adult↗
PubMed2000

The accuracy and reproducibility of radiographic assessment of stress-shielding. A postmortem analysis.

BACKGROUND: Although periprosthetic bone loss remains a major concern in total hip arthroplasty, radiographic assessment of such loss is both difficult and subjective. In the present study, we assessed the ability of orthopaedic surgeons to reproducibly recognize changes in periprosthetic bone density on radiographs. We hypothesized that assessment of periprosthetic bone loss on plain radiographs is not reliable enough to justify its use in outcomes research. METHODS: Twenty-nine unilateral total hip replacements and the surrounding bone were retrieved at autopsy, and radiographs were made; radiographs of the contralateral, normal femur were also made after implantation of an identical prosthesis and used as a control. Three orthopaedic surgeons independently examined the specimen radiographs and classified bone loss in each of sixteen femoral zones. Bone loss was recorded as present if the bone of the femur that had had in vivo implantation showed evidence of cortical thinning, increased porosity, or decreased density (either cortical or trabecular) when compared with the control femur. The kappa coefficient was used to quantify interobserver and intraobserver reproducibility in determining bone loss for the 464 zones examined and in determining the Engh and Bobyn stress-shielding classification of each femur. In fourteen femoral pairs, bone loss was also quantified with dual-energy x-ray absorptiometry, and the resulting value was then compared with the bone-loss classification that had been determined radiographically. RESULTS: First, the surgeons agreed on the presence or absence of bone loss in 73 percent (337) of the 464 zones. The interobserver kappa value of 0.58 denoted only good reproducibility. The intraobserver reproducibility was better; the surgeon's initial evaluation of bone loss agreed with his second evaluation for 90 percent of the zones (kappa = 0.74). Second, the three surgeons agreed on the degree of stress-shielding, according to the Engh and Bobyn classification, in 66 percent (nineteen) of the twenty-nine femora. The kappa value for this comparison was only 0.27, indicating marginal reproducibility. Third, although there was some agreement among reviewers when there was 20 to 60 percent reduction in bone-mineral content as determined with dual-energy x-ray absorptiometry, excellent agreement among the examiners (kappa = 0.85) was not achieved until bone loss averaged 70 percent. CONCLUSIONS: On the basis of these results, we suggest caution in interpreting results from studies of femoral bone loss that have used plain radiographic analysis if the authors have not provided interobserver reliability data. We question the utility of evaluating periprosthetic bone loss on radiographs, since the loss is not reproducibly recognized until 70 percent of the bone is gone.

Absorptiometry, Photon↗
PubMed2006

[Reproducibility of optic nerve head and retinal nerve fiber layer thickness measurements using optical coherence tomography].

PURPOSE: To evaluate the reproducibility of repeated quantitative measurements of optic nerve head topography and retinal nerve fiber layer thickness. METHODS: This study included 32 normal subjects, 41 patients with ocular hypertension and 33 patients with glaucoma. The study groups were defined by the intraocular pressure levels, optic disc stereo-photographs and perimetric performance. Optic disc and retinal nerve fiber layer assessments were performed by ocular coherence tomography (OCT III, Zeiss Instruments). OCT examination was repeated three times in each subject and the coefficient of variability was elaborated for each parameter and group of the study, and compared among them. RESULTS: The average retinal nerve fiber layer thickness measurement showed the best reproducibility figures with a coefficient of variability of 5.9%. The inferior quadrant and the 10, 6 and 7 clock-hours (coefficients of variability 6.3%, 7.4%, 7.5% and 8.6% respectively) showed higher reproducibility. The optic nerve head assessment showed the best reproducibility for the cup-to-disc ratios (vertical, horizontal and area ratios), with a coefficient of variability of 5.0%, 4.2% and 6.6% respectively. Although differences among groups were barely statistically significant, the glaucoma group showed coefficients of variability higher than the other two groups. CONCLUSIONS: Optic nerve head analysis and retinal nerve fiber layer thickness can be reproducibly assessed by OCT. The reproducibility of the device supports its potential use for ocular hypertension follow-up, although its use in glaucoma patients may present difficulties in some parameters.

Female↗
PubMed2005

Endometrial volume and vascularity measurements by transvaginal 3-dimensional ultrasonography and power Doppler angiography in stimulated and tumoral endometria: an interobserver reproducibility study.

OBJECTIVE: The purpose of this study was to evaluate interobserver reproducibility of endometrial volume and vascular indices of the endometrium and subendometrial area estimated by 3-dimensional power Doppler angiography (3D-PDA) using the Virtual Organ Computer-Aided Analysis program, determining the influence of the endometrial growth etiology on measurements. METHODS: Forty women underwent 3D-PDA ultrasonography. Group A comprised 25 women scanned on the day after controlled ovarian stimulation with human chorionic gonadotropin. Group B comprised 15 patients who had uterine bleeding and questionable endometrial thickening. (Histologic evaluation revealed 10 endometrial cancers and 5 endometrial hyperplasias.) A single observer examined all patients and acquired all volume data sets. Forty volume data sets were then analyzed with the Virtual Organ Computer-Aided Analysis program by 2 different observers. Endometrial volume and vascularity indices (vascularization index [VI], flow index [FI], and vascularization flow index [VFI]) of the endometrium and subendometrium were manually calculated in the coronal plane with a 9 degrees rotation step. An intraclass correlation coefficient (ICC) was used to assess interobserver reliability. RESULTS: Endometrial volume was more reproducible in group A (ICC = 0.98) than in group B (ICC = 0.58) (P < .05). Endometrial and subendometrial VI, FI, and VFI also presented good reproducibility with ICC greater than 0.84. The ICC was not statistically different for endometrial and subendometrial VI, FI, and VFI according to patient group, although subendometrial VFI was less reproducible in group B (ICC = 0.53) than in group A (ICC = 0.88). CONCLUSIONS: Endometrial volume and endometrial and subendometrial 3D power Doppler indices have acceptable reproducibility. The interobserver reproducibility in tumoral endometrium was more similar than in stimulated endometrium. Our results indicate that 3D-PDA is a reliable method to evaluate physiologic and pathologic endometrial changes.

Adult↗
PubMed1999

Reproducibility and validity of radioimmunoassays for urinary hormones and metabolites in pre- and postmenopausal women.

The reproducibility of RIAs of circulating sex hormones has been evaluated as part of recent epidemiological investigations, but none seem to have addressed the reproducibility or validity of RIAs for urinary hormones or their metabolites. As part of a case-control study of breast cancer in Asian-American women, 12-h overnight urine samples were obtained, and a methodological study was conducted to identify laboratories capable of assaying urinary hormones. For the reproducibility component of this study, two laboratories with extensive experience in hormone assays measured urinary estrone, estradiol, estriol, pregnanediol glucuronide, and estrone glucuronide using samples from 15 women (5 midfollicular, 5 midluteal, and 5 postmenopausal). Variance estimates from these measurements were used to calculate the laboratory variability (coefficient of variation) and to assess the magnitude of the biological variability among the women in relation to the total variability (intraclass correlation coefficient). For the validity component, urinary estrone, estradiol, and estriol levels were measured in the same samples by gas chromatography-mass spectroscopy in the laboratory of Dr. Herman Adlercreutz (University of Helsinki, Helsinki, Finland). We found that the degree of assay reproducibility differed between the laboratories, but that laboratory variability was usually low compared with the range of hormone values among women, particularly for the estrogens. Values for estrone and estradiol were well correlated among all of the laboratories. For estriol, the RIAs tended to overestimate levels compared with gas chromatography-mass spectroscopy. In one laboratory, assays for pregnanediol glucuronide and estrone glucuronide were consistently reproduced; in the other, the reproducibility of the RIA for pregnanediol glucuronide was problematic, and estrone glucuronide was not measured. Despite some limitations, urinary hormones and their metabolites can be reliably measured by current RIAs in large investigations attempting to link hormone level to disease risk and may be particularly advantageous for studies of postmenopausal women, where serum concentrations of estrone and estradiol are low and assay measurements are not as dependable.

Adult↗
PubMed2000

Reproducibility of visual activation in functional MR imaging and effects of postprocessing.

BACKGROUND AND PURPOSE: Functional MR imaging studies of the brain should be interpreted in the context of their reproducibility. We assessed the reproducibility of visual activation measured by functional MR imaging and analyzed the effect of image transformation to standard space. METHODS: Seven healthy volunteers were studied twice with echo-planner functional MR imaging at 1.5 T during visual stimulation. The studies were separated by an interval of 2 to 7 days. Functional images were analyzed after spatial normalization to the space described by Talairach and Tournoux and/or after coregistration of the images of the second study with the images of the first study. The number of active voxels for each study was determined at three thresholds. In addition, the change in the center of the mass of activation, the mean change in signal intensity, and the mean t value within the activated area were measured. These reproducibility indexes were calculated for the spatially normalized and nonnormalized data for each subject. RESULTS: Variations in visual activation were observed between the two studies in the same individual as well as across subjects. There was no evidence of an effect from image transformation on reproducibility on any of the measures. CONCLUSION: Our findings show that the reproducibility of activation in functional MR imaging may be much more variable across subjects than suggested in previous studies. The use of different types of image transformation (coregistration, spatial normalization) does not significantly affect the reproducibility of visual activation.

Adult↗
PubMed2005

Assessment of the long-term reproducibility of baseline and dobutamine-induced myocardial blood flow in patients with stable coronary artery disease.

UNLABELLED: Although physical exercise is the preferred stimulus for cardiac stress testing, pharmacologic agents are useful in patients who are unable to exercise. Previous studies have demonstrated short-term repeatability of exercise and adenosine stress, but little data exist regarding dobutamine (Dob) stress or the long-term reproducibility of pharmacologic stressors in coronary artery disease (CAD) patients. PET allows accurate, noninvasive quantification of myocardial blood flow (MBF) and coronary flow reserve (CFR). The aim of the study was to investigate the long-term reproducibility of Dob stress on MBF and CFR in CAD patients using PET. METHODS: Fifteen patients with chronic stable angina and angiographically proven CAD (>70% stenosis in at least 1 major coronary artery) underwent PET with (15)O-labeled water and Dob stress at baseline (time [t] = 0) and after 24 wk (t = 24). MBF at rest and MBF during Dob stress were calculated for the whole left ventricle, the region subtended by the most severe coronary artery stenosis (Isc), and remote myocardium subtended by arteries with minimal or no disease (Rem). Reproducibility was assessed using the Bland-Altman (BA) repeatability coefficient and was also expressed as a percentage of the mean value of the 2 measurements (%BA). RESULTS: Dob dose (30 +/- 11 vs. 031 +/- 11 microg/kg/min; P = not significant [ns]) and peak Dob rate.pressure product (20,738 +/- 3,947 vs. 20,047 +/- 3,455 mm Hg x beats/min; P = ns) were comparable at t = 0 and t = 24. There was no significant difference in resting or Dob MBF (mL/min/g) between t = 0 and t = 24 for the whole left ventricle (1.03 +/- 0.19 vs. 1.10 +/- 0.20 and 2.02 +/- 0.44 vs. 2.09 +/- 0.57; P = ns for both), Isc (1.05 +/- 0.24 vs. 1.10 +/- 0.26 and 1.79 +/- 0.53 vs. 1.84 +/- 0.62; P = ns for both), or Rem (1.03 +/- 0.23 vs. 1.10 +/- 0.26 and 2.27 +/- 0.63 vs. 2.26 +/- 0.63; P = ns for both) territories. Global (1.98 +/- 0.40 vs. 1.90 +/- 0.46; P = ns) and regional CFR (Isc: 1.65 +/- 0.40 vs. 1.67 +/- 0.47, and Rem: 2.25 +/- 0.57 vs. 2.06 +/- 0.51; P = ns) were reproducible. The BA repeatability coefficients (and %BA) for MBF in ischemic and remote territories were 0.3 (28%) and 0.26 (24%) at rest and 0.49 (27%) and 0.58 (26%) during Dob stress. CONCLUSION: In patients with clinically stable CAD, Dob induces reproducible changes in both global and regional MBF and CFR over a time interval of 24 wk. The reproducibility of MBF and CFR with Dob was comparable with the short-term repeatability reported for adenosine and physical exercise in healthy subjects.

Angina, Unstable↗
PubMed2006

Field, coil, and echo-time influence on sensitivity and reproducibility of brain proton MR spectroscopy.

BACKGROUND AND PURPOSE: Clinical MR imaging scanners now offer many choices of hardware configurations that were not available in the first 25 years of their existence. Our goal was to assess the influence of coil technology, magnetic field strength, and echo time (TE) on the sensitivity, reflected by the signal intensity-to-noise-ratio (SNR) and reproducibility of proton MR spectroscopy (1H-MR spectroscopy). MATERIAL AND METHODS: The SNR, the intersubject reproducibility, and the intrasubject reproducibility of N-acetylaspartate (NAA), creatine (Cr), and choline (Cho) levels were compared at the common TEs of 30, 144, and 288 ms, by using 1H-MR spectroscopy in 6 volunteers at (1) 3T with a single-element quadrature (SEQ); (2) 1.5T with SEQ; and (3) 1.5T with a 12-channel phased-array (PA) head coil. RESULTS: In terms of sensitivity, the best SNR for all metabolites was obtained at the shortest TE (30 ms). It was comparable between the 3 and 1.5T with the PA, but approximately 35% better than the 1.5T with SEQ. This SNR difference declined <25% at TE of 144 ms and to equity among all imagers at TE of 288 ms. Reproducibility, reflected in the coefficient of variation (CV), was best for NAA at TE of 288 ms, 15%-50% better than at TE of 30 ms in either gray (GM) or white matter (WM). The CV for Cr was best, at TE of 288 ms for GM, but its WM results were independent of TE. Metabolite level reproducibility did not depend on coil technology or magnetic field strength. CONCLUSIONS: For the same coil type, the SNR of all major metabolites was approximately 35% better at 3T than at 1.5T. This advantage, however, was offset at 1.5T with a PA coil, making it a cost-effective upgrade for existing scanners. Surprisingly and counterintuitively, despite the lowest SNR, the best reproducibility was obtained at the longest TE (288 ms), regardless of field or coil.

Adult↗
PubMed2006

Intrasubject reproducibility of functional MR imaging activation in language tasks.

BACKGROUND AND PURPOSE: The purpose of this study was to examine the reproducibility of functional MR imaging (fMRI) activation (volume and laterality) within both inferior frontal and temporoparietal regions of interest for both receptive and expressive language tasks. METHODS: Ten healthy volunteers participated in fMRI experiments for 6 language tasks: verb generation, confrontation naming, semantic decision making, visual sentence comprehension, auditory sentence comprehension, and story listening. Each subject was scanned during 2 separate sessions separated by a minimum of 4 weeks. Laterality of activation was defined by laterality indices (LIs), which were calculated by 2 methods: one method based on the measured volume of activation and the other method based on the F statistic of the activation. Reproducibility was calculated by using concurrence ratios for the volume of activation (R(overlap), R(volume)) and test-retest correlation for LIs. RESULTS: All tasks generated reproducible LIs within at least one of the regions of interest, but verb generation produced the highest test-retest correlations (r = 0.99) within both regions of interest. Verb generation was associated with the highest average concurrence ratios within the inferior frontal region of interest (R(overlap) = 45.2; R(volume) = 70.9). In general, the concurrence ratios were lower within the temporoparietal region of interest compared with the inferior frontal region of interest. LIs calculated with F statistics were more reproducible than the LIs calculated by activation volume. CONCLUSION: fMRI is able to provide reproducible LIs in both inferior frontal and temporoparietal regions for assessing hemispheric dominance in language processing. The volume of activation, especially within the temporoparietal regions, is less reproducible than the laterality of activation, so the former should be used with caution.

Adult↗