SEARCH · PubMed Health

Results for “Reproducibility”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,495 records · Page 83Linked to original sources

PubMed1996

Evaluation of the reproducibility of Auer's classification of DNA histogram in breast carcinoma.

In order to evaluate the reproducibility of the interpretation of DNA histograms obtained by two Static Image Analysis Systems (SIAS), the imprints of 50 cases of breast cancers of patients registered at Istituto Nazionale Tumori of Milan were analysed. The imprints were obtained by a single operator. After fixation, the cytological preparations were stained with the Feulgen reaction. The histograms were independently classified, according to Auer's classification, by four investigators. To evaluate the reproducibility of the classification (within investigator agreement) the histograms were submitted to each investigator at two distinct times and the within investigator agreement was estimated by the weighted kappa statistic (kw). The results of the reproducibility of Auer's classification were not entirely satisfactory (kw about 0.70). This preliminary result confirm the suggestion to adopt alternative methods of classification of the ploidy histograms.

Adenocarcinoma↗

PubMed1996

Reproducibility of subjective immunoscoring of steroid receptors in breast cancer.

OBJECTIVE: To evaluate the reproducibility of subjective immunoscoring of steroid receptors in breast cancer by inexperienced observers after brief training by one experienced observer. STUDY DESIGN: Thirteen inexperienced observers were trained for a few minutes semiquantitatively (0-4) to score tumor nuclei in two breast cancer frozen sections immunohistochemically stained each for estrogen or progesterone receptors. Then, the fractions of 0, 1, 2, 3 and 4 "stained" nuclei were estimated individually. Thereafter, the experienced observer pointed out the nuclei one by one, and the participants scored these nuclei individually. From these data, histoscores were calculated. RESULTS: When comparing individual scorings (n = 1,320) with the gold standard, discrepancies occurred mainly between scores 2 and 3, and the best concordance was achieved for the scores 0 and 4. For the histoscores, coefficients of variations for the estimated scores (7.3-33.7, mean 17.2) were systematically higher than those derived from nucleus-by-nucleus scoring (2.6-15.4, mean 10.3). CONCLUSION: Inexperienced observers can be trained quickly to arrive at fairly reproducible histoscores for immunohistochemically stained estrogen and progesterone receptors in breast cancer frozen sections. Nucleus-by-nucleus scoring seems to be more reproducible than estimating fractions of nuclei with certain positivity and should be recommended in cases of values close to the decision threshold.

Breast Neoplasms↗

PubMedDate not supplied

Comparison of inter-observer reproducibility between conventional chest radiography and AMBER in the evaluation of silicosis.

The aims of this study were to test inter-observer and intraobserver agreement in the diagnosis of silicosis using conventional chest radiography and AMBER. One hundred and fifteen patients underwent chest x-rays and AMBER for the diagnosis of silicosis. Five readers blindly and independently evaluated the radiograms with standard ILO/UC classification scales. Reproducibility was assessed using ANOVA repeated measurements methods. AMBER showed a better technical quality of radiograms than conventional chest x-rays; interobserver reproducibility was high and similar (R = 0.75); intraobserver agreement between chest x-rays and AMBER was high ranging from 0.62 to 0.86 for the 5 readers. Notwithstanding the absence of standards for profusion classification, the interobserver reproducibility with AMBER was similar to that obtained with chest x-rays. Moreover, the intraobserver agreement in profusion scoring between AMBER and chest radiography was high, suggesting that AMBER and chest radiography provided similar information in the evaluation of silicosis.

Aged↗

PubMed1996

[Perimetry with normal Octopus technique and Weber 'dynamic' technique. Initial results with reference to reproducibility of measurements in glaucoma patients].

UNLABELLED: There is ample reason to strive for a shorter test without losing solid and reproducible information on the function of the eye. The purpose of this study was to compare the standard Octopus strategy with the 'dynamic strategy' of Weber in terms of time requirement and reproducibility of results, i.e., short-term as well as long-term fluctuations in glaucoma. MATERIALS AND METHODS: On an Octopus 1-2-3 automated perimeter, 23 experienced glaucoma patients with predominantly local loss completed three test sessions, each consisting of a short training test followed by six visual fields, i.e., the first 'stage' (16 test locations) of program GIX, beginning at random with one strategy, then alternating the strategies. RESULTS: The deviation from normal values of the 1104 test locations obtained with the standard and the dynamic strategy (mean +/- SD) was 5.2 +/- 7.5 dB and 4.6 +/- 7.3 dB (P < 0.02), respectively. The short-term fluctuation (given as variance) with the standard and the dynamic strategy averaged 8.3 +/- 5.9 dB2 and 10.2 +/- 5.8 dB2 (p < 0.02), respectively. The long-term fluctuation, i.e., 'test-to-test' variation (given as variance), with the standard and the dynamic strategy was 6.4 +/- 16.5 dB2 and 7.89 +/- 19.2 dB2 (P < 0.22), respectively. The total long-term fluctuation of the index mean defect, MD, averaged 1.8 +/- 2.7 dB2 and 1.3 +/- 1.7 dB2 (P = 0.69), respectively, with the standard and the dynamic strategy. The number or stimuli required with the standard and the dynamic strategy averaged 5.6 +/- 1.4 and 3.0 +/- 1.0 (P < 0.001), respectively. CONCLUSIONS: The dynamic strategy required 43% fewer stimuli and presented 23% (significantly) higher short-term fluctuation, but long-term fluctuations were similar for both strategies. The two strategies were comparable regarding the respective reproducibility of the results. However, further studies may investigate the sensitivity and the specificity of either strategy to distinguish disease from normal, or, change during a follow-up of a disease, and, may elucidate whether the observed differences between the two strategies are due to the modified step size, or, to the single (versus double) crossing of the threshold.

Adult↗

PubMed1997

Koilocytotic atypia in Papanicolaou smears. Reproducibility and biopsy correlations.

BACKGROUND: It would be useful if cervical smears containing koilocytes alone could be reliably separated from those containing other forms of nuclear atypia within the spectrum of low grade squamous intraepithelial lesions (LSIL) and that this separation was predictive of differences in biopsy follow-up. In this article, the authors sought to test this possibility. METHODS: Consecutive smears diagnosed as LSIL from 140 patients who had follow-up colposcopic biopsies were reviewed independently by three observers. The inter- and intraobserver reproducibility in diagnosing smears with koilocytes alone was assessed by the kappa statistic. Comparison of each reviewer's cytologic diagnosis with a reviewed biopsy diagnosis was assessed using chi-square analysis. The quantity of abnormal cells was compared with the presence or absence of a lesion on biopsy. RESULTS: Kappa values for any 2 observers agreeing on koilocytosis as a separate category ranged from 0.22-0.47 (poor to good). Intraobserver reproducibility across all cytologic categories ranged from 0.35-0.62 (poor to good). A cytologic diagnosis of koilocytosis predicted a lower rate of high grade SIL (HSIL) on initial biopsy for one of the observers, but not for the other two. Koilocytosis did not predict a lower rate of LSIL on initial biopsy or HSIL in follow-up biopsies for any observer. The quantity of cells on the initial smear did not correlate with a lesion on biopsy. CONCLUSIONS: Separation of LSIL into two diagnostic categories is not feasible because of its poor cytologic reproducibility and inability to predict differences in biopsy diagnosis. The quantity of abnormal cells in LSIL is not predictive of the detection of a lesion on biopsy.

Biopsy↗

PubMed1997

Minimum spanning tree analysis in advanced ovarian carcinoma. An investigation of sampling methods, reproducibility and correlation with histologic grade.

OBJECTIVE: To investigate sampling methods and reproducibility of minimum spanning tree (MST) variables in advanced ovarian cancer and their discriminative power for histologic grade. STUDY DESIGN: For the methodologic investigation, 30 cases of advanced ovarian cancer of the common epithelial types were used. These cases were equally distributed over the three histologic grades according to independent, "blind" assessments by three observers: well (n = 10), moderately (n = 10) and poorly (n = 10) differentiated. Additionally, the discriminative power of the MST variables for histologic grade was assessed in 64 cases (double-blind agreement upon grade by two observers). Measurements were performed on hematoxylin-eosin-stained tumor sections. In each field of vision the centers of gravity of tumor cell nuclei were interactively marked using a digitizing video overlay system, and an MST was computed. From each MST the number of points, total line length, average line length, minimum line length, maximum line length and percentage of points with one, two three and four neighbors were obtained. Optimal performance (coefficient of error < 5%) of the method was established when the MST was constructed in 12 systematically randomly selected fields of vision at a final magnification of 1,900x. RESULTS: Intraobserver and interobserver reproducibility showed good correlation coefficients for most MST variables. Univariate analysis revealed that total, average and minimum line length were significantly different between the three histologic grades. With a jacknifed stepwise discriminant analysis an overall correct classification of 75% for the three histologic grades was achieved in 64 cases, using the average line length, standard deviation of the line length and total line length. CONCLUSION: MST syntactic structure analysis offers an easy, fast and very reproducible technique that may be of help in objective grading of advanced ovarian cancers. Further studies are under way to investigate the prognostic value of MST analysis in advanced ovarian cancer.

Cell Differentiation↗

PubMed1997

Regional cerebral blood flow measurement with iodine-123-IMP autoradiography: normal values, reproducibility and sensitivity to hypoperfusion.

UNLABELLED: We recently proposed a simplified technique for measuring regional cerebral blood flow (rCBF) using the [123I]N-isopropyl-p-iodoamphetamine (IMP) autoradiographic (ARG) method with SPECT (the IMP-ARG method). We examined normal values of rCBF and the reproducibility and sensitivity to hypoperfusion in stroke patients using this method. METHODS: By using a standard arterial input, a single static scan, a fixed distribution volume (Vd) and one-point arterial blood sampling, we measured rCBF in 39 normal volunteers (19 men and 20 women; mean ages 61 +/- 11 yr for the men and 60 +/- 12 yr for the women). Eighteen neurologically stable patients with prior stroke (mean age = 65 +/- 11 yr) were studied twice at a mean interval of 97 days. In 16 patients (7 men and 9 women, mean age = 63 +/- 5 yr) with subarachnoid hemorrhage, rCBF was measured 1-2 wk after onset. Cerebral vasospasm was evaluated by repeated angiography. The mean rCBF in the vasospastic area was compared with that in a nonvasospastic area. RESULTS: The mean rCBFs of the cerebral cortex and centrum semiovale in the volunteers were 33.0 +/- 5.1 ml/100 g/min and 25.0 +/- 4.5 ml/100 g/min, respectively. There was no age-dependent change in rCBF, but the women showed significantly higher cortical rCBF than the men (p < 0.05). In the stroke patients, the whole-brain CBF values showed high reproducibility, with high correlations between those obtained at the first and second studies (y = -3.5 + 1.03x; r = 0.90; p < 0.001). In the subarachnoid hemorrhage patients, the vasospastic area showed significantly lower rCBF than the normal cortical rCBF (p < 0.01) and the nonvasospastic area (p < 0.01). Brain regions with rCBF levels below 20 ml/100 g/min showed infarction on the follow-up CT scan. CONCLUSION: The IMP-ARG method is reproducible, sensitive to hypoperfusion and feasible for the quantitative evaluation of rCBF in routine clinical practice.

Aged↗

PubMed1997

Reproducibility of laser Doppler flowmetry in the human optic nerve head.

PURPOSE: We sought to demonstrate reproducibility of the noninvasive laser Doppler flowmetry technique for measuring microvascular hemodynamics of the optic nerve head in human subjects. METHODS: Laser Doppler flowmetry was performed by four examiners on four human optic nerve heads during multiple sessions. Intersubject, interexaminer, intersession, and intrasession variabilities were calculated for velocity, blood volume, and blood flow (flux). RESULTS: Initial variability of measurements improved after 3 months' experience. The standard deviation of the intrasession variation for single readings was 18% of the velocity mean value and 24% of the flow (flux) mean value. Based on this, a sample size of 17 (power beta = 0.8, alpha = 0.05, paired t test) will demonstrate a 10% physiologic change in flux within a session if the average of five readings is used before and after the experimental perturbation. The intersession variation was 12% and 32% for velocity and flux, respectively. Because of this, a larger sample size or additional measurement sessions are required for detection of an experimental influence between two sessions. The coefficient of variation among subjects for single readings was 7% and 10% for velocity and flux, respectively. CONCLUSIONS: Reproducibility of velocity measurements is better than reproducibility of flux measurements. After experience with the method, laser Doppler flowmetry is sufficiently precise to permit feasible studies of human optic nerve head microvascular hemodynamics when physiologic perturbations are applied.

Adult↗

PubMed1997

Reproducibility of retardation measurements with the nerve fiber analyzer II.

PURPOSE: To evaluate the reproducibility of a scanning laser polarimeter, the Nerve Fiber Analyzer II (NFA II, Laser Diagnostic Technologies, San Diego, CA, U.S.A.). METHODS: Five independent retardation maps of the peripapillary retina of five normal eyes were acquired by three experienced operators (including V.S.G.) on each of three separate days for a total of 45 retardation maps per patient. Two methods of image processing, one using a baseline image and another using the individual scans, were used to compare the reproducibility of three summary measures, average retardation, integral, and retardation ratio. RESULTS: The average standard deviation (and its 95% confidence interval) of average retardation within a 10-pixel-width-band of the 9 baseline images was 0.43 degree (0.36-0.51 degree) with a mean coefficient of variation of 4.2% (3.8-4.5%). In a random effects model, each of the three retinal nerve fiber layer (RNFL) summary measures varied significantly by patient (p < 0.016), but not by operator (p > 0.19), or operator by patient interaction (p > 0.524). In addition, there was small, but statistically significant day-by-operator-within-patient (intraobserver) variation in the random effects model. CONCLUSIONS: These results suggest that the NFA II provides reproducible measurements and that, on average, measurements obtained by separate operators on different days are similar.

Adult↗

PubMed1998

Reproducibility and efficiency testing of two sampling methods for image analysis in cytology.

OBJECTIVE: Quantitative nuclear DNA analyses and nuclear morphometry have become a widely used tool in pathology. Nevertheless, studies done by different observers utilizing the same methods very often have shown different results. One of the reasons could be that different sampling methods were used. In this study two selection methods for image analyses (the consecutive selection method and the random selection method) were tested for reproducibility and efficiency. STUDY DESIGN: Using an interactive imaging analysis system, 10 cases (5 breast adenocarcinomas, 3 prostatic cancers, 1 sarcoma, 2 prostatic hyperplasias) were measured twice by using each sampling method. Median nuclear area and entropy (i.e., a statistical descriptor of DNA histograms) were the parameters calculated. RESULTS: The results showed that using the consecutive selection method, the number of individual nuclei in a cytologic sample that should be measured to obtain reproducible results was 150 for nuclear area and 110 for entropy. The corresponding figures using random systematic selection method were 80 for assessment of nuclear area and 100 for assessment of entropy. CONCLUSION: Both methods showed high reproducibility and a good correlation with each other. The mathematical idea of "plateau values," which was used to estimate the number of measurements needed, was considered a good contribution to increasing the efficiency of both methods.

Breast Neoplasms↗

PubMed1998

Validity and reproducibility of a food frequency questionnaire among Hispanic and non-Hispanic white women in New Mexico.

The purpose of this study was to assess the validity and reproducibility of an interviewer-administered, semi-quantitative food frequency questionnaire (FFQ) among 132 volunteer New Mexico Hispanic (H) and non-Hispanic white (NHW) women, aged 35-74 years, with (n = 47) and without (n = 85) a breast cancer history, and to add to the limited data presently available on the performance of FFQs among different ethnic groups. Validity was measured at one month and six months from baseline against four-day food records, and reproducibility was tested by comparing FFQs. Unadjusted validity correlation coefficients were highest at one month, ranging from 0.38 (polyunsaturated and monounsaturated fat) to 0.57 (calcium); energy-adjusted correlation coefficients were highest at six months, ranging from 0.15 (polyunsaturated fat) to 0.68 (calcium). Energy-adjusted correlation coefficients were statistically significant by ethnicity for vitamins A and C, protein, carotene and calcium, and by case status for saturated fat, folate, fiber, and vitamins A and E. Reproducibility correlation coefficients (unadjusted) ranged from 0.40 (polyunsaturated fat) to 0.71 (carbohydrate, retinol); energy-adjusted correlation coefficients ranged from 0.42 (vitamin E) to 0.78 (fiber), and differed significantly by ethnicity for saturated fat and retinol, and by case status for carbohydrate. Overall, our FFQ has comparable characteristics to other FFQs and is suitable for use with New Mexico's H and NHW women.

Adult↗

PubMed1998

Enhanced accuracy and reproducibility in reporting of lung scintigrams by a segmental reference chart.

UNLABELLED: The diagnostic probability of pulmonary embolic disease is based on the recognition of unmatched segmental perfusion defects. Although interobserver and intraobserver reproducibility have been studied, accuracy has been an elusive goal due to the lack of a gold standard. We investigated the accuracy and reproducibility of reporting in a virtual scintigraphic model of the lungs, with and without the use of a lung segmental reference chart. METHODS: A Monte Carlo package was used to model lung scintigraphy from a digital phantom of the human lungs. An ideal lung segmental reference chart was created from the phantom. Five experienced nuclear medicine physicians reported a set of all possible defects involving 100% of a segment, without and with the chart. A further set of defects involving 45%-55% of a segment in the lower lobes was investigated using the chart. RESULTS: There was a significant improvement in accuracy (from 48% to 72%) and intraobserver agreement (from 61% to 77%) with the chart. The accuracy of reporting defects in the upper and middle lobes was consistently better than that in the lower lobes. There was no significant difference between the accuracy of reporting large defects and that of reporting moderate defects in the lower lobes. CONCLUSION: The lung segmental reference chart significantly improves both the accuracy and reproducibility of reporting lung scintigrams; however, although reporting in the lung bases is improved, absolute accuracy is substantially less than that in the upper and middle lobes. This emphasizes the need for caution because the lung bases are the most common site of embolic disease.

Computer Simulation↗

PubMedDate not supplied

Reproducibility of LSI HER-2/neu SpectrumOrange and CEP 17 SpectrumGreen Dual Color deoxyribonucleic acid probe kit. For enumeration of gene amplification in paraffin-embedded specimens: a multicenter clinical validation study.

Overexpression and/or amplification of HER-2/neu gene have been found to be prognostic and predictive in breast and other cancers. Fluorescence in situ hybridization (FISH) assay, with its sensitivity and specificity, can be a superior method of detection when its performance characteristics are demonstrated. A multicenter study was initiated to evaluate the reproducibility of the LSI HER-2/neu SpectrumOrange and CEP 17 SpectrumGreen Dual Color DNA Probe for enumeration of both the HER-2/neu gene and chromosome 17 (signals) in interphase cells. Section slides were prepared from four cell lines (H, E, R, and N) with known ratios of the HER-2/neu to CEP 17 copy numbers (approximately H = 1.10, E = 1.70, R = 4.50, N = 9.0). The study variable was the ratios of the HER-2/neu to chromosome 17 copy numbers. Reproducibility with respect to assay, site, lot, day and reader was evaluated at 3 centers. Out of 120 specimen slides, 100 percent were successfully assayed. There were no significant differences among: (1) four repeated assays of the same specimen (p = 0.99), (2) the four probe lots (p = 0.33), or (3) the four study days (p = 0.54). There was statistically significant, but not important differences among centers and between readers. The ratios of the HER-2/neu to chromosome 17 copy numbers were estimated with accuracy and precision; the mean ratios (and sd) for specimens, H, E, R, and N were 1.05 (0.06), 1.81 (0.12), 4.48 (0.28), and 8.60 (1.23), respectively. In summary, assays with the LSI HER-2/neu and CEP 17 Dual Color DNA Probe Kit, conducted at three sites by 6 different technicians, over 8 assay days, using kits from four lots, were performed with a high success rate in paraffin-embedded specimens. The signal enumeration was also accurate and precise. This study demonstrated that the results obtained by using the LSI HER-2/neu SpectrumOrange and CEP 17 SpectrumGreen Dual Color DNA Probe Kit are reliable and reproducible.

Breast Neoplasms↗

PubMedDate not supplied

Ultrafast CT scoring system for assessing bronchopulmonary dysplasia: reproducibility and clinical correlation.

PURPOSE: To evaluate the reproducibility of the Ultrafast CT (UFCT) scoring system and assess its usefulness in monitoring clinical severity in infants with bronchopulmonary dysplasia (BPD). MATERIALS AND METHODS: UFCT scoring was done in 22 infants (15 boys and 7 girls aged 1 to 37 months) with BPD. A total of 258 lung fields were evaluated for the presence of hyperaeration, linear opacities, triangular subpleural opacities, and bronchovascular bundle distortion or thickening, and UFCT scores were given. Intraobserver and interobserver agreement and reproducibility of UFCT scores were statistically analyzed. In 12 patients, UFCT scores were linearly correlated with clinical severity scores based on respiratory dysfunction and complexity of care. RESULTS: "Hyperaeration," which was the most frequent (18 of 22, 81.8%) finding, showed high concordance (kappa = 0.73, p < 0.001, kappa = 0.59, p < 0.001), and its UFCT scores significantly correlated with intraobserver and interobserver analyses (r = 0.94, p < 0.001, r = 0.82, p < 0.001, respectively). UFCT scores for hyperaeration significantly correlated with clinical scores (r = 0.75, p < 0.01), whereas those for the others did not. CONCLUSION: UFCT is useful for assessing BPD. Hyperaeration was the most common and reproducible finding, and its extent significantly correlated with clinical severity.

Bronchopulmonary Dysplasia↗

PubMed1998

[Reproducibility of heart rate variability in the chronic phase of myocardial infarction].

Evaluation of heart rate variability is a common method of assessing autonomic nervous system function and its effects on heart rate in different conditions. The reproducibility of the technique is not known in the chronic phase of myocardial infarction. The aim of this study was therefore to assess the reproducibility of the measurement in 54 subjects who were clinically stable with no change in treatment at a distance from acute or semi-recent (> 2 years) myocardial infarction, after an interval of one month. The temporal and spectral analysis of heart rate variability included measurement of the standard deviation of the normal RR intervals (SDNN), on the mean heart rate, the percentage of RR intervals greater than 50 ms than the adjacent interval (pNN50), the coefficient of variability (CV), the square root of the differences between successive RR intervals (rMSSD), the power of low frequencies (LF) and high frequencies (HF) and of the fractional spectral power (LF/HF). No significant changes in these parameters were observed. Analysis of individual variations showed that the heart rate was the most stable parameter: for evaluation of vagal tone, the rMSSD showed less variability than the pNN50 and HF. The presence of cardiac disease did not influence these results. The authors conclude that parameters of evaluation of heart rate variability in temporal and spectral analysis are globally reproducible in stable subjects. However, individual values may change from one measurement to another. Nevertheless, abnormal variability is constantly observed at the second investigation and, similarly, normal variability also remains unchanged. These individual variations suggest that, for the demonstration of change in these parameters of variability with treatment, large population groups must be studied.

Adult↗

PubMed1998

[Reproducibility of histoprognostic grades of invasive breast cancer].

In the framework of the quality assurance of the pathologists involved in the screening campaign it was proposed to test the reproducibility of the classical SCARFF, BLOOM and RICHARDSON (SBR) grade and the ELSTON-ELLIS grade (E-E) mentioned in the recent European recommendations. Twenty-four cases of invasive carcinoma were analyzed by 21 pathologists. Sixty-eight per cent agreement was obtained for the SBR grade and 69% for the E-E grade in the first round and vice versa in the second round. The mean value of the kappa test was 0.54 with SBR and 0.53 with E-E. The differentiation of the carcinoma was found to be the most reliable index (kappa score greater than 0.5), followed by the mitotic index (kappa score = 0.39 for SBR and 0.36 for E-E), and the nuclear polymorphism obtained the lowest score (kappa score ranging from 0.33 to 0.38). In our hands, the use of the E-E grade did not improve the reproducibility particularly for the mitotic index. Our results suggest however that the reproducibility may be improved by training.

Breast Neoplasms↗

PubMed1985

Induction of reproducible brain infarction by photochemically initiated thrombosis.

We have used a photochemical reaction in vivo to induce reproducible thrombosis leading to cerebral infarction in rats. After the intravenous injection of rose bengal, a potent photosensitizing dye, an ischemic lesion was formed by irradiating the left parietal convexity of the exposed skull for 20 minutes with green light (560 nm) from a filtered xenon arc lamp. Animals were allowed to survive from 30 minutes to 15 days after irradiation. Early microscopic alterations within the irradiated zone included the formation of thrombotic plugs and adjacent red blood cell stasis within pial and parenchymal vessels. Scanning electron microscopy revealed frequent platelet aggregates adhering to the vascular endothelium, often resulting in vascular occlusion. Carbon-black brain perfusion demonstrated that occlusion of vascular channels progressed after irradiation and was complete within 4 hours. Histopathological examination at 1, 5, and 15 days revealed that the associated infarct evolved reproducibly through several characteristic stages, including a phase of massive macrophage infiltration. Although cerebral infarction in this model is initiated by thrombosis of small blood vessels, the fact that the main pathological features of stroke are consistently reproduced should permit its use in assessing treatment regimens. Further, the capability of producing infarction in preselected cortical regions may facilitate the study of behavioral, functional, and structural consequences of acute and chronic stroke.

Animals↗

PubMed1984

Reproducibility of ventricular function measurements by contrast angiography.

Interobserver reproducibility of single plane contrast angiographic measurements of end-diastolic volume (EDV/m2), end-systolic volume (ESV/m2), stroke volume (SV/m2), and ejection fraction (EF) was studied in two groups of patients. The first group (n = 42) was an unselected, consecutive series of patients in which the calculations of volume were performed manually, representing day-to-day results from a clinical quantitative angiographic laboratory. The second group (n = 31) was selected on the basis of optimal filming technique and volume calculations were performed digitally with the aid of a computer. This group characterizes the reproducibility that could be attained for investigational purposes. In the selected group, interobserver reproducibility of four regional ejection fractions was determined. The correlation coefficient (r), standard error of the estimate (Sy.x), average difference, and 95% confidence limits are given. Measurement variation accounted for 9-15% of the variance in this study for EDV/m2 (consecutive series), indicating that caution is needed when relating contrast angiographic measurements to other (e.g., noninvasive) measures of volume by simple linear regression.

Angiocardiography↗