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PubMed2006

Global and regional reproducibility of T2 relaxation time measurements in human patellar cartilage.

Seven T2 maps (multiecho (ME) sequence: 3000 ms, eight echoes with 13.2 ms of echo spacing, 20 sections) and T1-weighted (T1-w) fast low-angle shot (FLASH-water excitation (WE)) data sets from four imaging sessions (right patellae of 10 healthy volunteers) were obtained. A segmentation of cartilage (WE sequence) was overlaid on the ME data and T2 values were calculated for total cartilage, three layers, three facets (global), and 240 ROIs (regional). Reproducibility (precision error) was calculated as the root mean square average (RMSA) of the individual coefficients of variation (COVs, %) and standard deviations (SDs, ms) for intra- and intersession reproducibility. The precision error was 3-7% and 6-29% for global and regional T2, respectively. There was no difference between intra- and intersession reproducibility, but there was worse reproducibility in the superficial layers compared to the deeper layers. Peripheral ROI reproducibility (mean=13%) was worse than in the central portions (mean=11%), but omission of the periphery did not positively affect the globally calculated T2 reproducibility. The precision errors were small compared to reported changes in diseased cartilage, suggesting good discriminatory power of the technique. Our data provide a first estimate of global and regional reproducibility errors of T2 in healthy cartilage, and may serve as a basis for sample size calculations and aid study designs for longitudinal and cross-sectional trials in osteoarthritis (OA).

Adult↗
PubMed2003

Between-gel reproducibility of the human cerebrospinal fluid proteome.

This manuscript describes the between-gel reproducibility of the two-dimensional gel electrophoresis analysis of the human lumbar cerebrospinal fluid (CSF) proteome. This reproducibility study is a necessary component for our long-term research program that uses comparative proteomics to analyze lumbar CSF samples in a study of human idiopathic low back pain. A Protein-Plus Dodeca Cell electrophoresis apparatus and PDQuest software were used to measure the level of between-gel reproducibility of the CSF proteome. One pooled CSF sample was used to evaluate the level of within-sample, between-gel reproducibility, and a set of seven different CSF samples (CSF-1 to 7) was used to test the level of within-group and between-group variability. Differentially expressed proteins (six CSF samples versus the designated control, CSF-3) were characterized with mass spectrometry. The number of spots found in the pooled CSF sample was 490 +/- 30 (n = 10 gels); the percentage of protein spots found in those 10 gels was 92 +/- 6%, with a coefficient of variation of 6%; and a positive coefficient of correlation (r = 0.82) was found. In order to test the proof-of-principle, that set of seven CSF samples served as a test of our ability to perform reproducibility comparative proteomics, and to detect differentially expressed proteins within that set of test samples. One sample (CSF-3) served as the control for the other six to locate the differentially expressed proteins. A comparison of fifteen differentially expressed proteins found in that set of test CSF samples correlated with pathology. Matrix-assisted laser desorption/ionization-time-of-flight and electrospray ionization quadrupole ion trap mass spectrometry were used to characterize thirteen of those fifteen differentially expressed proteins. These results (reproducibility, protein characterization, set of test samples, and proof-of-principle) suggest that the analysis of human CSF two-dimensional gels can achieve a high level of within-sample and between-sample reproducibility, and that PDQuest software can measure the relative protein abundance in the human CSF proteome.

Adult↗
PubMed1996

Reproducibility of the data determined by scanning laser polarimetry.

BACKGROUND: Scanning laser polarimetry is a tool for measuring the retinal nerve fiber layer: both its cross-sectional surface (polarimetric data analysis) and its thickness (mean sector values). METHODS: Two observers examined 56 normal volunteers twice by means of scanning laser polarimetry (Nerve Fiber Analyzer type 1, software version 1.6). Measurements of the retinal nerve fiber layer were carried out in four equal sectors of a circle around the optic nerve head. The measured values of the sectors and the calculated ratios among them were used for statistical analysis. Interobserver and intraobserver reproducibility were analyzed following a balanced random three-way cross classification with interactions. Interobserver reproducibility was defined as the part of variance not influenced by the observers. Intraobserver reproducibility was defined as the part of variance not influenced by the time. RESULTS: For repeated measurements of the retinal nerve fiber layer, better intraobserver than interobserver reproducibility was found (0.57-0.79 vs 0.11-0.44). The interobserver reproducibility was improved (0.24-0.65) in comparison to the intraobserver reproducibility (0.32-0.68) by calculating the ratios of the measured values. CONCLUSION: The instrument is clinically useful only if used by the same observer. If measurements are performed by different observers the ratios of the measurements must be used. Further development in the apparatus is needed to improve interobserver reproducibility.

Adolescent↗
PubMed2003

Gated blood pool SPECT improves reproducibility of right and left ventricular Fourier phase analysis in radionuclide angiography.

OBJECTIVES: The ventricular phase angle, a parametric method applied to Fourier phase analysis (FPA) in radionuclide ventriculography, allows the quantitative analysis of ventricular contractile synchrony. However, FPA reproducibility using gated blood pool SPECT (GBPS) has not been fully evaluated. The present study evaluates whether by using GBPS, the reproducibility of FPA could be improved over that in planar radionuclide angiography (PRNA). METHODS: Forty-three subjects underwent both GBPS and PRNA, of which 10 subjects were normal controls, 25 had dilated cardiomyopathy, and 8 had various heart diseases. Interventricular contractile synchrony was measured as the absolute difference in RV and LV mean ventricular phase angle as delta(phi) (RV - LV). Intraventricular contractile synchrony was measured as the standard deviation of the mean phase angle for the RV and LV blood pools (RVSD(phi), LVSD(phi)). Two nuclear physicians processed the same phase images of GBPS to evaluate the interobserver reproducibility of the phase angles using data from the 43 study participants. Phase images acquired from PRNA were processed in the same manner. RESULTS: Excellent reproducibility of delta(phi) (RV - LV) was obtained with both GBPS (Y = -3.10 + 0.89 x X; r = 0.901) and PRNA (Y = -4.51 + 0.81 x X; r = 0.834). In regard to RVSD(phi) reproducibility was not adequate with PRNA (Y = 18.56 + 0.35 x X; r = 0.424), while it was acceptable with GBPS (Y = 5.22 + 0.85 x X; r = 0.864). LVSD(phi) reproducibility was superior using both GBPS (Y = 4.15 + 0.97 x X; r = 0.965) and PRNA (Y = -0.55 + 0.98 x X; r = 0.910). CONCLUSION: Our results demonstrate FPA obtained using GBPS to be highly reproducible for evaluating delta(phi) (RV - LV), RVSD(phi) and LVSD(phi), in comparison with the PRNA method. We thus consider GBPS appropriate for evaluating ventricular contractile synchrony.

Adult↗
PubMed2005

Reproducibility of bone mineral density measurements using dual X-ray absorptiometry in daily clinical practice.

Bone mineral density (BMD) measurements are frequently performed repeatedly for each patient. Subsequent BMD measurements allow reproducibility to be assessed. Previous studies have suggested that reproducibility may be influenced by age and clinical status. The purpose of the study was to examine the reproducibility of BMD by dual energy X-ray absorptiometry (DXA) and to investigate the practical value of different measures of reproducibility in three distinct groups of subjects: healthy young volunteers, postmenopausal women and patients with chronic rheumatic diseases. Two hundred twenty-two subjects underwent two subsequent BMD measurements of the spine and hip. There were 60 young healthy subjects, 102 postmenopausal women and 60 patients with chronic rheumatic diseases (33 rheumatoid arthritis, 10 ankylosing spondylitis and 10 other systemic diseases). Forty-five patients (75%) among the third group were receiving corticosteroids. Reproducibility was expressed as the smallest detectable difference (SDD), coefficient of variation (CV), least significant change (LSC) and intraclass correlation coefficient (ICC). Sources of variation were investigated by linear regression analysis. The median interval between measurements was 0 days (range 0-7). The mean difference (SD) between the measurements (g/cm2) was -0.0001 (+/-0.003) and -0.0004 (+/-0.002) at L1-L4 and the total hip, respectively. At L1-L4 and the total hip, SDD (g/cm2) was +/-0.04 and +/-0.02, CV (%) was 2.02 and 1.29, and LSC (%) 5.60 and 3.56, respectively. The ICC at the spine and hip was 0.99 and 0.99, respectively. Only a minimal difference existed between the groups. Reproducibility in the three groups studied was good. In a repeated DXA scan, a BMD change, the least significant change (LSC) or the SDD should be regarded as significant. Use of the SDD is preferable to use of the CV and LSC because of its independence from BMD and its expression in absolute units. Expressed as SDD, a BMD change of at least +/-0.04 g/cm2 at L1-L4 and +/-0.02 g/cm2 at the total hip should be considered significant. This reproducibility seems independent from age and clinical status and improved in the hips by measuring the dual femur.

Absorptiometry, Photon↗
PubMed2006

The intersubject and intrasubject reproducibility of FMRI activation during three encoding tasks: implications for clinical applications.

The goal of the present study was to evaluate the inter- and intrasubject reproducibility of FMRI activation for three memory encoding tasks previously used in the context of presurgical functional mapping. The primary region of interest (ROI) was the medial temporal lobe (MTL). Comparative ROIs included the inferior frontal and fusiform gyri which are less affected by susceptibility-induced signal losses than the MTL regions. Eighteen subjects were scanned using three memory encoding paradigms: word-pair, pattern, and scene encoding. Nine subjects underwent repeat scanning. Intersubject reproducibility of FMRI activation was evaluated by examining the percent of subjects who showed activation within a given ROI and the range to which individual laterality indices (LIs) varied from the mean. Intrasubject test-retest reproducibility was evaluated by examining the LI test-retest correlation, the average difference between LIs from two separate imaging sessions, and concordance ratios of activation volumes (R(volume) and R(overlap)). For scene encoding the reproducibility of activation volume and LIs within the MTL were as good as or better than the reproducibility within the fusiform and inferior frontal ROIs. For pattern encoding and word-pair encoding, the reproducibility of activation volume and LIs within the MTL tended to be worse compared to the fusiform and inferior frontal ROIs. The differences in FMRI reproducibility appeared more dependent on the task than the susceptibility effects. The results of this study suggest that FMRI-based assessment of the neural substrates of memory using a scene encoding task may be a useful clinical tool.

Acoustic Stimulation↗
PubMed1992

Reproducibility of mitosis counting in 2,469 breast cancer specimens: results from the Multicenter Morphometric Mammary Carcinoma Project.

The Multicenter Morphometric Mammary Carcinoma Project is a prospective study on the reproducibility and prognostic value of routine quantitative assessments, especially the mitotic activity index (MAI), the multivariate prognostic index (MPI; a combination of MAI, tumor size, and lymph node status), the mean nuclear area, and DNA ploidy assessments in patients with invasive breast cancer. Fourteen pathology laboratories providing routine services to 35 hospitals throughout The Netherlands are participating in this project. In this article, the reproducibility of MAI and MPI assessments is described. Assessment of the MAI was, according to a strict protocol, first performed in the participating laboratories; thereafter, slides were transferred to the coordination center in Amsterdam for quality control. Analysis of the reproducibility of the assessments in 2,469 patients showed correlation coefficients between 0.81 and 0.96 (mean, 0.91) for the MAI and between 0.91 and 0.97 (mean, 0.96) for the MPI. The reproducibility was fairly constant in time, although it showed a slight drop in the middle of the 2-year intake period. A prognostically relevant discrepancy in MPI (caused by differences in MAI) between the original and quality control assessments was found in only 7.2% of the cases. When analyzing the reasons for these discrepancies, a plausible explanation could be found in all cases: bad tissue processing and ignorance of or negligence in following the protocol guidelines for selection of the counting area or in the process of counting were the most important flaws. Since these errors are largely controllable, an even lower discrepancy rate is theoretically achievable. In conclusion, in a routine setting it can be learned, within a reasonable time, to perform mitosis counting in a highly reproducible way if a strict protocol is carefully followed. This opens the way for a wider application of the MAI and MPI in breast cancer patients. Motivation is, however, an important factor to obtain reproducible results, and ongoing quality control is essential to guarantee the reproducibility of the assessments.

Breast Neoplasms↗
PubMed1992

Frequency versus time domain analysis of signal-averaged electrocardiograms. I. Reproducibility of the results.

Three repeated signal-averaged electrocardiographic (ECG) recordings were made in 40 subjects (15 healthy volunteers, 10 patients with ventricular tachycardia without apparent heart disease and 15 patients with ventricular tachycardia after myocardial infarction). In each subject, the three recordings were made within 25 min. The recordings were subsequently analyzed by 1) the conventional time domain method of signal-averaged ECG analysis with use of filter settings of 25 to 250 Hz and 40 to 250 Hz, 2) a spectral analysis method computing the energy area within the spectral boundaries of 40 to 140 Hz and the ratio between the energies of areas within the boundaries 40 to 140 Hz and 0 to 40 Hz, and 3) spectral temporal mapping computing the "normality factor." The study compared the reproducibility of these three approaches to the analysis of signal-averaged ECGs. First, the reproducibility of the diagnostic conclusions (that is, of the diagnosis of late potentials) was compared for the time domain method and for spectral temporal mapping. Second, the reproducibility of the numeric values of individual indexes provided by different methods was compared for all methods by computing the ratios between standard deviations of measurements in individual patients and standard deviation of all measurements. The reproducibility of diagnostic conclusions was significantly higher for the time domain method than for spectral temporal mapping (p less than 0.05, sign test). The numeric reproducibility of the normality factors produced by spectral temporal mapping was significantly lower than the numeric reproducibility of the values of all indexes provided by time domain, spectral area and spectral area ratio methods (p less than 0.05 to 0.00005, Wilcoxon tests). Spectral temporal mapping was the least reproducible method for the analysis of signal-averaged ECGs.

Adult↗
PubMed1990

Short- and long-term reproducibility of radioisotopic examination of gastric emptying.

Reproducibility of gastric emptying (GE) of a radiolabelled solid meal was assessed. The short-term reproducibility was evaluated on the basis of 12 paired GE examinations performed 1-3 days apart. Twelve paired GE examinations taken 3-8 months apart enabled long-term reproducibility assessment. Reproducibility of GE parameters was expressed in terms of the coefficient of variation, CV. No significant between-day variation of solid GE was found either regarding the short-term or the long-term reproducibility. Although slightly higher CV values characterized the long-term reproducibility of the GE parameters considered, the variations of the differences between repeated GE examinations did not differ significantly between short- and long-term GE reproducibility. The results obtained justify the use of radioisotopic GE measurement for the assessment of early and late results of pharmacologic or surgical management.

Adult↗
PubMed2006

Intra- and inter-observer reproducibility of the Recurrent Varicose Veins after Surgery (REVAS) classification.

OBJECTIVES: To evaluate intra- and inter-observer reproducibility of the classification for recurrent varicose veins after surgery (REVAS). DESIGN: Intra- and inter-observer reproducibility of each component of the REVAS classification were evaluated by a Kappa test. MATERIAL AND METHODS: A multi-centre study conducted in 8 countries enrolled 199 REVAS patients. Patients were examined twice by the same observer, and once by another physician. Investigations included physical examination and duplex scanning. A form based on the CEAP and the REVAS classification was filled in after each examination. RESULTS: The analysis revealed that of the 8 items in the REVAS, intra-observer reproducibility was excellent for three items and good for five, and that inter-observer reproducibility was good for 6 items and moderate for two. Making a slight change in the proposed answers to one question, which is somewhat ambiguous, would increase inter-observer reproducibility. Analysis of the cause of intermediate reproducibility underlines the necessity of validating a duplex scanning protocol and a standardised duplex scanning report. CONCLUSION: The good or excellent intra-observer reproducibility of the REVAS provides the main required criteria for use in clinical trials or cohort studies where patients are usually followed up by the same investigator to determine their spontaneous or treatment-related outcome.

Humans↗
PubMed2004

Inter- and intra-study reproducibility of contrast echocardiography for assessment of interventricular septal wall perfusion rate in humans.

AIMS: To assess inter- and intra-study reproducibility of myocardial contrast echocardiography (MCE) imaging for quantitative measurement of myocardial perfusion rate in humans in ambulatory setting. METHODS AND RESULTS: In 20 subjects, we performed 2 MCE tests 20-40 min apart on the same day under the same standardized protocol, and evaluated single-reader between-study and between-reading reproducibility of assessment of indicators of myocardial perfusion rate, such as the slope of video-intensity change k, and the factors A (peak video-intensity) and B (background video-intensity after bubble destruction) and the product k X A. The region of interest was placed at the mid-posterior interventricular septal wall visualized in apical 4-chamber view. In a sub-analysis, we evaluated indicators of myocardial perfusion rate comparing subjects with normal vs. those with subnormal ejection fraction (EF). Inter-study reproducibility of assessment of k was relatively low (intraclass correlation coefficient = 0.36), whereas intra-study reproducibility was fair (intraclass correlation coefficient = 0.61). The parameters k X A and B showed higher reproducibility than the k (inter- and intra-study intraclass correlation coefficients 0.64 and 0.75, 0.74 and 0.91, respectively). For reference, reproducibility data of the depth of the region of interest, of EF and CO were excellent. k and k X A were lower in subjects with low vs. those with normal EF. Only k and k X A were lower in subjects with subnormal than in those with normal EF. CONCLUSIONS: The MCE-derived indicator of myocardial perfusion rate k X A showed fairly good between-study and between-reading reproducibility.

Aged↗
PubMed2004

Reproducibility of organ position using voluntary breath-hold method with spirometer for extracranial stereotactic radiotherapy.

PURPOSE: To evaluate in healthy volunteers the reproducibility of organ position using a voluntary breath-hold method with a spirometer and the feasibility of this method for extracranial stereotactic radiotherapy in a clinical setting. METHODS AND MATERIALS: For this study, 5 healthy volunteers were enrolled. After training sessions, they held their breath at the end-inspiration and the end-expiration phase under spirometer-based monitoring. Computed tomography (CT) scans were performed twice at each respiratory phase, with a 10-min interval, on 2 separate days. The total number of CT scans was four at each respiratory phase. After CT volume data were transferred to a three-dimensional treatment-planning system, digitally reconstructed radiographs (DRRs) were calculated for anterior-posterior and left-right beams. Verification was performed with DRRs relative to the diaphragm position, bony landmarks, and the isocenter in each healthy volunteer at each respiratory phase. To evaluate intrafraction reproducibility, we measured the distance between diaphragm position and bony landmarks. To evaluate interfraction reproducibility, we measured the distance between diaphragm position and the isocenter. Reproducibility and setup error were defined as the average value of the differences between each DRR with regard to the first DRR. RESULTS: Intrafraction reproducibility of the caudal-cranial direction was 4.0 +/- 3.5 mm at the end-inspiration phase and 2.2 +/- 2.0 mm at the end-expiration phase. Interfraction reproducibility of the caudal-cranial direction was 5.1 +/- 4.8 mm at the end-inspiration phase and 2.1 +/- 1.8 mm at the end-expiration phase. The end-expiration phase was more stable than the end-inspiration phase. CONCLUSIONS: The voluntary breath-hold method with a spirometer is feasible, with relatively good reproducibility. We are encouraged about the use of this technique clinically for extracranial stereotactic radiotherapy.

Diaphragm↗
PubMed2004

Influence of the quality of tibial plateau alignment on the reproducibility of computer joint space measurement from Lyon schuss radiographic views of the knee in patients with knee osteoarthritis.

RATIONALE: The quality of medial tibial plateau (MT-Plateau) alignment is one of the key elements for accuracy and sensitivity to change of knee radiography in knee osteoarthritis (OA). AIM: To evaluate the influence of the quality of the MT-Plateau alignment on the reproducibility of joint space width (JSW) measurement in knee radiographs. METHODS: One hundred and twenty-seven knee radiographs (99 OA), performed using a standardized radiographic procedure (Lyon schuss (LS) view). Evaluation of the quality of MT-Plateau alignment. Computerized measurement of the JSW, twice, 1-month apart, using a semi-automated and an automated method of measurement. Assessment of the reproducibility of repeated measurements: calculation of intra-observer coefficient of correlation, smallest detectable difference (SDD) and coefficient of variation (CV). RESULTS: MT-Plateau alignment was satisfactory in 99 radiographs (77.9%). Reproducibility was excellent in both satisfactory and non-satisfactory radiographs, irrespective of the method of measurement used. The automated measurement was more reproducible than the semi-automated one (CV 1.15% and 3.23%). SDD and CV were better in satisfactory than in non-satisfactory MT-Plateau aligned radiographs. CONCLUSION: These results confirm that computer measurement of the medial tibio-femoral JSW, from LS digitized radiographs, is highly reproducible, irrespective of the quality of the radiograph. However, the quality of the MT-Plateau alignment influences the reproducibility of JSW measurement. The automated measurement was more reproducible than the semi-automated one.

Aged↗
PubMed2005

A method for generating reproducible evidence in fMRI studies.

Insights into cognitive neuroscience from neuroimaging techniques are now required to go beyond the localisation of well-known cognitive functions. Fundamental to this is the notion of reproducibility of experimental outcomes. This paper addresses the central issue that functional magnetic resonance imaging (fMRI) experiments will produce more desirable information if researchers begin to search for reproducible evidence rather than only p value significance. The study proposes a methodology for investigating reproducible evidence without conducting separate fMRI experiments. The reproducible evidence is gathered from the separate runs within the study. The associated empirical Bayes and ROC extensions of the linear model provide parameter estimates to determine reproducibility. Empirical applications of the methodology suggest that reproducible evidence is robust to small sample sizes and sensitive to both the magnitude and persistency of brain activation. It is demonstrated that research findings in fMRI studies would be more compelling with supporting reproducible evidence in addition to standard hypothesis testing evidence.

Algorithms↗
PubMed1997

Reproducibility of time-domain indexes of heart rate variability in patients with vasovagal syncope.

The aim of this study was to examine whether the indexes of heart rate variability (HRV) are stable from day-to-day in patients with vasovagal syncope and whether the stability of the HRV indexes is linked with that of the clinical results of the tilt test. Nineteen patients with a history of syncopal episodes and a positive tilt test underwent a second test 1 week later. Of these, 11 (group P-P) also had a positive second test, whereas 8 (group P-N) had a negative second test. Fifteen healthy volunteers served as a control group. Five time domain indexes were derived: the mean of all coupling intervals between normal beats (mean NN), the SD about the mean of all coupling intervals between normal beats (SDNN), the mean of all 5-minute standard deviations of NNs (SD), the proportion of adjacent normal RR intervals differing by >50 ms (pNN50), the root-mean-square of the difference between successive RRs (rMSSD) and the standard deviations of 5-minute mean NN intervals (SDANN). The control group showed good reproducibility of all HRV indexes (slope 0.86 to 0.97). The syncopal patients taken as a whole had significantly less reproducibility than the controls in the pNN50 parameter. This difference was due entirely to the patients in the P-N group, who had a remarkable lack of reproducibility in both the pNN50 and rMSSD measures (slope pNN50, 0.52; rMSSD, 0.78), whereas the P-P group had a reproducibility of all HRV indexes, which was no different from that in controls (slope 0.83 to 1.04). In patients with vasovagal syncope, certain HRV measures that express parasympathetic tone did not show the high reproducibility found in normal subjects. Syncopal patients who lack reproducibility in these HRV parameters also show a lack of reproducibility in the clinical result of tilt testing.

Analysis of Variance↗
PubMed1996

Reproducibility of orthostatic hypotension in symptomatic elderly.

PURPOSE: Variations in the reported prevalence of orthostatic hypotension (4% to 33%) are attributed to population selection and varied criteria used to define orthostatic hypotension. Variation in the reproducibility of hemodynamic responses to orthostasis could be a further confounding variable. The purpose of this study was to evaluate reproducibility of orthostatic blood pressure changes in patients with documented symptomatic orthostatic hypotension. PATIENTS AND METHODS: Forty outpatients (mean age 77+/- 8 years; 24 women) were recruited after initial presentation to a morning outpatient clinic with postural symptoms of dizziness (92%), falls (67.5%), or syncope (30%). Patients had a symptomatic drop in orthostatic systolic blood pressure of >20 mm Hg documented in clinic. Subsequent cardiovascular assessment included autonomic function tests, carotid sinus massage (supine and erect), and prolonged head-up tilt tests. Blood pressure and heart rate measurements were repeated during standing and head-up tilt on two further attendances in the morning. RESULTS: A total of 67.5% patients had a drop in systolic blood pressure of >20 mm Hg on both visits during orthostatic stimuli; in the remainder, the response was not reproducible, and 5% had no significant orthostatic drop at either attendance. In 19 patients autonomic function tests were abnormal; orthostatic hypotension was reproducible in 79% of this group. In patients with normal autonomic function tests, 57% had reproducible orthostatic hypotension, of which only 60% were reproducible in those patients when further assessed in the afternoon. CONCLUSIONS: Orthostatic blood pressure responses may not be reproducible in patients with documented symptomatic orthostatic hypotension, particularly if autonomic function is normal and measurements are taken in the afternoon. Repeated systolic blood pressure measurements in the morning may be necessary to make a diagnosis in older patients with suspected orthostatic hypotension.

Accidental Falls↗
PubMedDate not supplied

Reproducibility of color Doppler imaging for orbital arteries in Japanese patients with normal-tension glaucoma.

The reproducibility of measurements by color Doppler imaging (CDI) were evaluated in Japanese patients with normal-tension glaucoma. Measurements were taken in the central retinal artery, the ophthalmic artery, and the short posterior ciliary arteries. Reproducibility was evaluated by calculating the coefficients of reproducibility for the peak systolic and end diastolic velocities and for the resistance index. The coefficient of reproducibility was calculated as magnitude of V1 - V2/¿(V1 + V2)/2¿ where V1 is the value of the first measurement and V2 is the value of the measurement taken 48 hours later. In calculating the resistance index of the orbital arteries, the central retinal artery and the short posterior ciliary artery temporal to the optic nerve both had coefficients of reproducibility of 0.04 +/- 0.04 (mean +/- standard deviation); the ophthalmic artery and the short posterior ciliary artery nasal to the optic nerve both had coefficients of reproducibility of 0.04 +/- 0.05. The high reproducibility of the CDI technique supports the validity of using CDI in a clinical setting to measure the hemodynamic parameters of small retrobulbar blood vessels.

Adult↗
PubMed1996

Interlaboratory reproducibility of semiautomated cell cycle analysis of flow cytometry DNA-histograms obtained from fresh material of 1,295 breast cancer cases.

Conflicting prognostic results have been published as to the DNA variables, such as DNA ploidy, DNA index, and % S-phase cells for breast cancer patients. These variables can be obtained by interpreting DNA histograms by cell cycle analysis. Explanations for these conflicting results might be found on the level of the interpretation of the DNA histograms. In a previous study, the semi automated cell cycle analysis computer program MultiCycle (Phoenix Flow Systems, San Diego, CA) showed high intralaboratory reproducibility. However, what types of DNA histograms may cause disagreements was still unclear. The aim of this study was to determine the interlaboratory reproducibility of MultiCycle-based cell cycle analysis of 1,295 flow cytometric DNA histograms derived from fresh frozen breast cancer material and to clarify potential sources of interobserver variation when analyzing DNA histograms. DNA ploidy classification into diploid, hyperdiploid, tetraploid, hypertetraploid, and multiploid showed an interlaboratory agreement of 94% (kappa value = 0.92). The 6% discrepancies (n = 74) were caused by tetraploid peaks, as established in one laboratory, which shifted outside the tetraploid region on reanalysis by the other laboratory (37%), shoulders sometimes interpreted as peaks (24%), small peaks not always recognized as such (24%), fitting failures (10%), and overlooking of tetraploid peaks (5%). Furthermore, the cell cycle analysis variables showed variable reproducibility. The % S-phase cells of the first, second, and third cell cycle showed overall a moderate reproducibility (0.62 < or = R < or = 0.79), but the average % S-phase cells and the average aneuploid % S-phase cells were more reproducible with correlation coefficients of 0.89 and 0.81, respectively. The coefficient of variation of the G0/G1 peak of the first cell cycle, the DNA indices and the % diploid cells were highly reproducible (R > or = 0.94), and the % G2/M-phase cells of the first, second, and third cell cycle were poorly reproducible (0.22 < or = R < or = 0.68). When a cut-point was used at the mean value of 7% for the average % S-phase cells, the number of "threshold discrepancy cases" was 6%. Sources of variation for cell cycle analysis were variations in the debris correction procedures, disagreement about the modes of the aneuploid peaks, disagreement about small peaks, shoulders sometimes interpreted as peaks, and overlooking of tetraploid peaks.

Autoanalysis↗