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Results for “Sampling Errors”

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PubMed2000

[Evaluation of knowledge about climacteric in Andalusian women].

OBJECTIVES: To evaluate the level of knowledge about the menopause of Andalusian women between 30 and 60 years old; and to determine their knowledge's relationship with social and demographic variables, health service use and their position as regards the climacteric. DESIGN: Cross-sectional study. PARTICIPANTS: A sample of 770 Andalusian women between 30 and 60 was chosen, for a sample error of +/- 5% and 95% confidence interval, chosen through multi-stage sampling: at random with proportionality for province and size of habitat, and sampling by age quotas and educational background. MEASUREMENTS: The principal study variable was women's level of knowledge about the menopause, evaluated through a validated test of 56 dichotomous questions. In the descriptive analysis, the mean, standard deviation and 95% CIs were obtained; in the analysis of relationships, the test of homogeneity of means, and variance and regression analysis were used. RESULTS: On a scale of 0-56, the mean on the sample was 18.17 with a standard deviation of 14.37 (95% CI: 17.15-19.17). 57.9% of the sample polled had values of low or very low level of knowledge. In the analysis of relationships, and according to the variance analysis data, we found that the level of understanding is related (p < 0.001) to age (F = 64.21), educational background (F = 131.19), type of menopause (F = 8.94), and having received information on the menopause (F = 7.57). Of these four variables it is educational background which most explains the variability in knowledge (r = 0.52, p < 0.001). However, experience of the menopause or use of the health services for the menopause do not seem to affect knowledge about the climacteric period and its treatment. CONCLUSIONS: The lack of knowledge of the menopause shown by the population studied demonstrates the need for Health Education on this stage of life. The relationships analysis leads us to conclude that the profile of women studied who knew most was someone with middle/high educational background, aged 30-40, who had had a surgical menopause, and had received information about the menopause.

Adult↗

PubMed1995

Use of spectral analysis to test hypotheses on the origin of pinnipeds.

The evolutionary origin of the pinnipeds (seals, sea lions, and walruses) is still uncertain. Most authors support a hypothesis of a monophyletic origin of the pinnipeds from a caniform carnivore. A minority view suggests a diphyletic origin with true seals being related to the mustelids (otters and ferrets). The phylogenetic relationships of the walrus to other pinniped and carnivore families are also still particularly problematic. Here we examined the relative support for mono- and diphyletic hypotheses using DNA sequence data from the mitochondrial small subunit (12S) rRNA and cytochrome b genes. We first analyzed a small group of taxa representing the three pinniped families (Phocidae, Otariidae, and Odobenidae) and caniform carnivore families thought to be related to them. We inferred phylogenetic reconstructions from DNA sequence data using standard parsimony and neighbor-joining algorithms for phylogenetic inference as well as a new method called spectral analysis (Hendy and Penny) in which phylogenetic information is displayed independently of any selected tree. We identified and compensated for potential sources of error known to lead to selection of incorrect phylogenetic trees. These include sampling error, unequal evolutionary rates on lineages, unequal nucleotide composition among lineages, unequal rates of change at different sites, and inappropriate tree selection criteria. To correct for these errors, we performed additional transformations of the observed substitution patterns in the sequence data, applied more stringent structural constraints to the analyses, and included several additional taxa to help resolve long, unbranched lineages in the tree. We find that there is strong support for a monophyletic origin of the pinnipeds from within the caniform carnivores, close to the bear/raccoon/panda radiation. Evidence for a diphyletic origin was very weak and can be partially attributed to unequal nucleotide compositions among the taxa analyzed. Subsequently, there is slightly more evidence for grouping the walrus with the eared seals versus the true seals. A more conservative interpretation, however, is that the walrus is an early, but not the first, independent divergence from the common pinniped ancestor.

Algorithms↗

PubMed1998

[Computerized tomography and magnetic resonance in the study of retroperitoneal sarcomas].

PURPOSE: We investigated the yield of CT and MRI in the diagnosis and staging of 15 patients with retroperitoneal sarcomas; these lesions are often asymptomatic and need radical surgery to avoid local recurrences. MATERIAL AND METHODS: April 1993, to September 1997, fifteen patients with retroperitoneal sarcomas were examined and then operated on. CT and CT-guided FNAB were always performed, while MRI was performed in 8 patients only. Because of the high risk of sampling errors, the bioptic specimens were immediately evaluated by a pathologist: a second sampling was required in 10 cases and a third sampling in 6 cases. MRI was performed with a .5 T system (GE Vectra); T1- and T2-weighted transverse images of the abdomen were acquired in all patients and additional coronal and sagittal images were acquired for each abnormal region. All patients underwent surgery and the pathologic diagnosis was compared with CT and MR findings. RESULTS: CT always allowed accurate location of the lesions and identification of their components, especially fat deposits. The cytologic examination of FNAB samples allowed the diagnosis of sarcoma in 12 of 15 cases. CT results were compared with MR findings in 8 patients and the latter method had better spatial definition of the abdominal masses, particularly of vascular structures, which is important for surgical planning. DISCUSSION: The present-day imaging techniques are very important to plan the surgical treatment of retroperitoneal sarcomas. In particular, CT has the advantage of high spatial resolution and excellent tissue contrast from abundant retroperitoneal fat tissue; it also permits the cytologic sampling of viable tumor tissue. However the bulk of such lesions often prevents CT from determining the tumor origin, in which case MRI provides better spatial resolution and vascular detailing, which helps surgical planning. CONCLUSIONS: Both CT and MRI are major tools in the diagnosis and staging of retroperitoneal sarcomas because they can accurately define the borders of large tumors and their relationships with surrounding organs. MRI has the advantage of characterizing the blood supply to the mass, but CT is better to guide FNAB.

Adult↗

PubMed1997

Fine-needle aspiration of thyroid nodules: correlation between cytology and histology and evaluation of discrepant cases.

BACKGROUND: The purpose of this study was to evaluate the results of thyroid fine-needle aspiration (FNA) and to determine the reasons for the discrepancies between the cytologic and histologic diagnoses. METHODS: The authors evaluated the cytologic and histologic results of 133 FNAs obtained from 92 patients who underwent subsequent thyroidectomies. RESULTS: The initial cytologic results were indeterminate in 39 of 133 cases (29%) because a neoplasm could not be ruled out. These cases corresponded histologically to 9 adenomatoid nodules (ANs), 14 follicular adenomas (FAs), and 16 malignant thyroid neoplasms. The reported FNA diagnoses of the remaining 94 cases (71%) were 48 ANs, 19 follicular neoplasms (FNs), 21 papillary carcinomas (PCs), and 6 cases of Hashimoto's thyroiditis (HT). Correlation of cytology and histology showed that 69 of 94 FNA results (73%) correlated with the histologic diagnoses, whereas 25 (27%) were discrepant. The discrepancies resulted from cytodiagnostic errors in 13 cases (52%), suboptimal smears in 11 (44%), and an FNA sampling error in 1 (4%). The false-negative rate of FNA was 19% and the false-positive rate was 6%. CONCLUSIONS: Diagnostic pitfalls and indeterminate FNA diagnoses were predominantly due to overlapping cytologic criteria between ANs, FNs, and follicular variants of PCs. Rendering a definite diagnosis on suboptimal FNA samples is also a significant source of pitfalls.

Adenoma↗

PubMed1988

Dealing with uncertainty: statistics for an aging population.

"Uncertainty in statistics and demographic projections for aging and other policy purposes comes from four sources: differences in definitions, sampling error, nonsampling error, and scientific uncertainty. Some of these uncertainties can be reduced by proper planning and coordination, but most often decisions have to be made in the face of some remaining uncertainty. Although decision makers have a tendency to ignore uncertainty, doing so does not lead to good policy-making. Techniques for estimating and reporting on uncertainty include sampling theory, assessment of experts' subjective distributions, sensitivity analysis, and multiple independent estimates." The primary geographical focus is on the United States.

Americas↗

PubMed1978

An evaluation of blood smears made by a new method using a spinner and diluted blood.

Blood smears were prepared with the use of a spinner, which rotated with a fixed velocity for a fixed time. All blood samples used for spun smears were diluted with a fixed ratio of buffered isotonic saline solution. Distribution of cells in these smears was found to be random. The average number of cells per unit area was substantially uniform from place to place on the same slide and on multiple slides made with the smae sample. The distribution of leukocytes by type was also iniform. For different blood samples, the average number of cells per unit area in the smears correlated well with the measured cell concentrations per unit volume in the samples for leukocytes, erythrocytes and platelets. Leukocyte differential counts on replicate spun smears using the same bloods also agreed to within the sampling error. They similarly agreed with differential counts on pulled smears made from undiluted samples of the same bloods. With few exceptions, erythrocytic morphology on the spun smears was comparable to that on the good areas of pulled smears made with undiluted samples of the same bloods. Nearly all the spun smears were suitable for both viual and fully automated hematologic examination for leukocytes, erythrocytes, and platelets. This was true over nearly the whole area of each spun slide. In these ways this spinner method makes smears whose consistently high quality is little affected by either the properties of the blood sample or the skill of maker.

Blood Cell Count↗

PubMedDate not supplied

Endoscopic ultrasound-guided fine needle aspiration of the pancreas. Diagnostic utility and accuracy.

OBJECTIVE: Endoscopic ultrasound-guided fine needle aspiration biopsy (EUS-FNAB) is regarded as a safe and reliable procedure for diagnosing and staging of pancreatic neoplasms. This study retrospectively evaluated both the diagnostic utility and accuracy of pancreatic EUS-FNABs and potential cytologic pitfalls when using Diff-Quik stain for on-site evaluation. STUDY DESIGN: Pancreatic EUS-FNABs performed between 1995 and 1998 were identified from the files of the Department of Pathology. All patients were studied via a linear-array ultrasound endoscope with an FNAB device. Immediate evaluation of the specimen by a pathologist using air-dried slides and Diff-Quik stain was done on all cases. An average of five passes (range, three to nine) were performed. Five cytologic categories were identified: nondiagnostic, benign, atypical, suspicious and malignant. EUS disease staging, histologic correlation and clinical follow-up were reviewed. RESULTS: Sixty-nine consecutive pancreative FNABs were evaluated in the study period. The patients comprised 38 females and 31 males with a mean age of 65 years (range, 36-83). Histologic correlation was available on 40 patients, and follow-up was available on the remaining 29. The cytologic diagnoses included: 31 malignant, 8 suspicious, 6 atypical, 20 benign and 4 nondiagnostic. Forty-three cases were true positive, 9 were true negative, 2 were false positive, and 11 were false negative. The overall sensitivity was 80% and specificity was 82%. CONCLUSION: The study showed that cytologic evaluation of pancreatic EUS-FNABs has 80% sensitivity and 82% specificity. False negative diagnosis was usually due to sampling error. A nondiagnostic cytologic diagnosis should be rendered in the absence of adequate sampling of a lesion. On-site cytologic evaluation of EUS-FNABs aids in guaranteeing specimen adequacy, and the pathologist should be trained to evaluate Diff-Quik-stained samples.

Adenocarcinoma↗

PubMed2004

A comparative evaluation of accelerated solvent extraction and Polytron extraction for quantification of lipids and extractable organochlorine in fish.

Optimal conditions for extraction methods using an accelerated solvent extractor (ASE) and a Polytron homogenizer were established for quantification of (crude) lipids and extractable organochlorine (EOCl) in fish. The two methods, an ASE consecutive extraction at 55 and 100 degrees C for ground, freeze-dried filets, and a Polytron extraction at room temperature with four repetitions for ground, wet filets and with two repetitions for wet fish livers were evaluated in terms of reproducibility and comparability. With respect to lipid measurement, the two methods have comparable reproducibility and the experimental errors are relatively small compared to natural variations of fish to fish within a sampling site. For EOCl measurement, the relative standard deviation tends to increase with decreasing levels of EOCl in specimens. An important factor for the relative standard deviation of measurements of analytes present at trace levels in fish matrices is sampling error in taking aliquots. Statistical analysis using a paired comparison design showed that measurement values (crude lipids or EOCl) obtained from these two extraction methods are, in general, not equivalent. There is a good correlation between the two methods for lipid measurement; whereas for EOCl measurements, high degrees of correlation exist within the exposed fish group, but not in the reference group.

Animals↗

PubMed2002

Publication bias in ecology and evolution: an empirical assessment using the 'trim and fill' method.

Recent reviews of specific topics, such as the relationship between male attractiveness to females and fluctuating asymmetry or attractiveness and the expression of secondary sexual characters, suggest that publication bias might be a problem in ecology and evolution. In these cases, there is a significant negative correlation between the sample size of published studies and the magnitude or strength of the research findings (formally the 'effect size'). If all studies that are conducted are equally likely to be published, irrespective of their findings, there should not be a directional relationship between effect size and sample size; only a decrease in the variance in effect size as sample size increases due to a reduction in sampling error. One interpretation of these reports of negative correlations is that studies with small sample sizes and weaker findings (smaller effect sizes) are less likely to be published. If the biological literature is systematically biased this could undermine the attempts of reviewers to summarise actual biology relationships by inflating estimates of average effect sizes. But how common is this problem? And does it really affect the general conclusions of'literature reviews? Here, we examine data sets of effect sizes extracted from 40 peer-reviewed, published meta-analyses. We estimate how many studies are missing using the newly developed 'trim and fill' method. This method uses asymmetry in plots of effect size against sample size ('funnel plots') to detect missing' studies. For random-effect models of meta-analysis 38% (15/40) of data sets had a significant number of 'missing' studies. After correcting for potential publication bias, 21 % (8/38) of weighted mean effects were no longer significantly greater than zero, and 15% (5/34) were no longer statistically robust when we used random-effects models in a weighted meta-analysis. The mean correlation between sample size and the magnitude of standardised effect size was also significantly negative (r(s) = -0.20, P < 0.0001). Individual correlations were significantly negative (P<0.10) in 35% (14/40) of cases. Publication bias may therefore affect the main conclusions of at least 15-21% of meta-analyses. We suggest that future literature reviews assess the robustness of their main conclusions by correcting for potential publication bias using the 'trim and fill' method.

Animals↗

PubMed1997

Epidemiological study of Paget's disease of bone in a zone of the Province of Salamanca (Spain). The Paget's disease of the bone study group of Salamanca.

Bone Paget's disease is heterogeneously distributed and several foci of high prevalence have been reported in Spain. The aim of the present work was to determine the prevalence of the disease in a zone situated in the northwestern sector of the Province of Salamanca (Spain) using a cross sectional epi-demiological study. Sample choice was based on a stratified sampling according to the residence, age and sex of the inhabitants of the zone. A sampling error of 5% and a confidence level of 95% were considered; these afforded a sample of 378 units. Final choice of the subjects was based on a random pathway method. Data collection was accomplished with a personal interview using a 31-item questionnaire and analytical screening (AP and GGT). The field work was carried out over a one-year period. The data were input onto a calculation sheet for analysis and epidemiological interpretation. Finally, clinico-radiological confirmation of the cases deemed positive in the screening was accomplished. The prevalence of PBD in the zone studied is 5.7% (95% CI: 4.5-6.9). The highest percentage of patients lies within the age group between 70-79 years; most of these patients were women. The mean residence time in the zone was 66 years. According to the findings, this geographic zone has a high prevalence of PBD.

Adult↗

PubMed1998

Zonal biopsy in the detection of prostate cancer in Japanese men.

To reduce sampling error as much as possible in the detection of prostate cancer, extensive transition zone sampling, in addition to the standard sextant random systematic biopsies, has been proposed. Improved biopsy techniques should make possible earlier and more effective detection of prostate cancer in a population where the incidence is low. Evaluation of such biopsies for elderly Japanese males is thus required. A total of 344 Japanese patients participated in this study. They underwent two transition zone biopsies in addition to systematic biopsy. Fifty-five of the 344 patients (16.0%) had cancer. Both biopsies were positive in 33 patients (60.0%), the standard systematic sextant biopsy alone demonstrated cancer in further 20 (36.4%) and the transition zone biopsy alone was positive in two others (3.6%). The two patients with cancer only in the transition zone biopsy cores had palpable abnormality and elevated prostate specific antigen. None of those with palpably benign glands or those with prior negative biopsies had cancer in the transition zone. Two additional cores from the transition zone led to no increase in morbidity of biopsy. Transition zone biopsy would not significantly contribute to the detection of prostate cancer in the present Japanese elderly male population. Though possibly of some value for certain patients, this biopsy does not warrant routine use.

Adult↗

PubMed1990

Immunohistological study of oestrogen receptors in breast carcinomas that are biochemically receptor negative.

The reliability of an immunohistological method, applied to paraffin wax sections, was assessed for determination of oestrogen receptor content of biochemically oestrogen receptor negative breast carcinomata. Sixty consecutive tumours with oestrogen receptor concentrations of less than 10 fmol/mg cytosol protein, as estimated by dextran-coated charcoal biochemical assay, were examined. Paraffin wax sections were treated with DNAse before applying a peroxidase-anti-peroxidase method using ER-ICA monoclonal antibodies. Fifty one cases (85%) were negative, six (10%) weakly positive, and three (5%) were moderately positive. No strongly positive cases were seen. It is suggested that cases with weakly positive staining, especially when localised to a small area, should be regarded as negative. On the other hand, as the three moderately stained cases included two small tubular carcinomas and an invasive ductal carcinoma with high progesterone receptor concentrations, it is more likely that the biochemical assay in these cases represented false negative results due to sampling error or inclusion of fibrous or other non-neoplastic tissue in the assayed samples. It is concluded that the immunohistological method used here is fairly reliable and would be especially valuable for determination of oestrogen receptor content in small, mammographically detected tumours from which no tissue would be available for biochemical assay or frozen section examination.

Adenocarcinoma↗

PubMed2006

Lifting a veil on diversity: a Bayesian approach to fitting relative-abundance models.

Bayesian methods incorporate prior knowledge into a statistical analysis. This prior knowledge is usually restricted to assumptions regarding the form of probability distributions of the parameters of interest, leaving their values to be determined mainly through the data. Here we show how a Bayesian approach can be applied to the problem of drawing inference regarding species abundance distributions and comparing diversity indices between sites. The classic log series and the lognormal models of relative- abundance distribution are apparently quite different in form. The first is a sampling distribution while the other is a model of abundance of the underlying population. Bayesian methods help unite these two models in a common framework. Markov chain Monte Carlo simulation can be used to fit both distributions as small hierarchical models with shared common assumptions. Sampling error can be assumed to follow a Poisson distribution. Species not found in a sample, but suspected to be present in the region or community of interest, can be given zero abundance. This not only simplifies the process of model fitting, but also provides a convenient way of calculating confidence intervals for diversity indices. The method is especially useful when a comparison of species diversity between sites with different sample sizes is the key motivation behind the research. We illustrate the potential of the approach using data on fruit-feeding butterflies in southern Mexico. We conclude that, once all assumptions have been made transparent, a single data set may provide support for the belief that diversity is negatively affected by anthropogenic forest disturbance. Bayesian methods help to apply theory regarding the distribution of abundance in ecological communities to applied conservation.

Animals↗

PubMedDate not supplied

Variability of vaginal pH determination by patients and clinicians.

PURPOSE: Measurement of intravaginal pH provides a reasonable assessment of vaginal health but is fraught with the potential for several sampling errors. The purposes of the study were to determine the variability of self-sampled vaginal pH among women using an inexpensive swab-based pH test compared with a clinician-obtained specimen, and variability of vaginal pH within 3 regions of the normal vagina. METHODS: In this cross-sectional study, women obtained a vaginal specimen using a cotton-tip applicator, transferred it to pH paper, and interpreted the results. A clinician also blindly interpreted these tests. Thereafter, a clinician obtained 3 swab specimens from the proximal, middle, and distal vagina for pH testing. Results were compared using Wilcoxon signed rank test, interclass correlation coefficients, Bland-Altman plots, and mixed-model analysis of variance. RESULTS: Interclass correlation coefficients were moderately high comparing subjects with clinician for the swab-based pH test (0.74). Subjects' swab pH values (4.5) were significantly lower than clinicians' pH values (4.7, P = .0001). Intravaginal pH did not vary between the 3 anatomic locations. CONCLUSIONS: Self-sampled intravaginal pH interpretations vary slightly compared with clinician-obtained specimens. Because swab pH sampling does not detect an intravaginal pH gradient in normal women, self-sampling technique may vary considerably without affecting outcomes. Our findings support self-sampling for vaginal pH before using over-the-counter products for presumed vaginitis.

Adolescent↗

PubMed1995

Histopathological concordance of paired renal allograft biopsy cores. Effect on the diagnosis and management of acute rejection.

To assess the effect of sampling error on renal allograft biopsies, we determined the concordance of diagnoses between 2 biopsy samples from the same renal allograft and the frequency with which 1 biopsy sample would underdiagnose or lead to the undertreatment of acute rejection. Two core samples from the same allograft biopsy procedure were labeled as core A and core B and presented to both unblinded and blinded pathologists, and each pathologist independently assigned an acute and a chronic rejection grade. A set of clinical data with pertinent prebiopsy information was combined with either the core A or core B histopathological diagnosis and presented to 3 transplant nephrologists who made treatment recommendations for each combination. Two cores were obtained in 79 allograft biopsies. Core pairs differed by > or = 1 grade of acute rejection in 30% and 50% of cases for unblinded and blinded pathologist readings, respectively. Moderate or severe acute rejection would have been missed with a 1 core in 9.5% of cases, increasing to 25.6% if only biopsy pairs containing at least 1 reading of moderate or severe acute rejection are included. Therapy would have failed to be increased with a single core in 7.5% of cases, increasing to 10.5% if only pairs containing at least one recommendation of an increase in therapy are included. The use of 2 cores of renal allograft tissue provides better diagnostic information and thereby leads to appropriate increases in antirejection therapy without increasing the complication rate of the procedure.

Adult↗

PubMed1999

Limitations with light microscopy in the detection of colorectal cancer cells.

PURPOSE: The failure of light microscopy to predict individual patient survival accurately in pStage I and II colorectal carcinoma can hinder planning postoperative therapy and follow-up. This study was designed and conducted in two parts to assess the influence of relative sensitivity of the light microscope on the pathologist's ability to detect malignant cells in lymph nodes. METHODS: The first part of the study examined the issue of sampling error as a fraction of the number of lymph node sections examined by asking the question, "Does increasing the number of sections (sampling) taken from the block increase tumor cell detection in a lymph node?" Three levels of five sections 4 to 5 microm thick separated by 15 to 20 microm were obtained from each of 494 blocks from 173 cases of pStage I and II colorectal carcinoma. A total of 1,721 lymph nodes were examined. Sections from each level were stained with hematoxylin and eosin and for the expression of cytokeratin. The second part of the study examined the relative sensitivity of the light microscope to detect tumor cells in a lymph node. To simulate lymph nodes, cell blocks were made that contained 10(6) or 10(7) mononuclear cells admixed with increasing numbers of SW480 tumor cells (0, 50, 10(2), 5 x 10(2), 10(3), and 5 x 10(3)). Three pathologists independently examined sections from ten control and ten experimental blocks. RESULTS: Results from the first part of the study demonstrated cytokeratin-positive cells in 278 lymph nodes from 102 of 172 (59 percent) cases. These cells were identified in the first level in 177 (64 percent) as compared with the second or third level or both in 101 (36 percent) of the lymph nodes. Results from the second part of the study demonstrated an overall sensitivity of light microscopic examination of hematoxylin and eosin-stained sections to be approximately 23 percent, representing tumor cells correctly detected in 7 sections of the 30 sections containing tumor cells. The overall specificity was 87 percent or 26 sections correctly classified as lacking tumor cells of a possible 30. Immunohistochemical staining for cytokeratin expression improved sensitivity of the light microscope to detect tumor cells to 18 of 30 (60 percent) and the specificity to 30 of 30 (100 percent). CONCLUSION: This study demonstrates several sources of variability that can induce errors in pathologic staging. These include 1) inadequate section, i.e., sampling, of lymph nodes, 2) use of only hematoxylin and eosin-stained sections, 3) samples with tumor cells below the level of detection sensitivity of the light microscope, and 4) observer variability.

Colorectal Neoplasms↗

PubMed2000

Telemedicine: application of telepathology-remote microscopy for intraoperative diagnoses on frozen sections.

Due to the time delay, intraoperative consultations result in an extension of operation times, leading to prolonged anesthesia and idle time during surgery. Using a remote controlled microscope for telepathology, transfer times between hospital and pathologist can be eliminated and pathological expertise obtained independently of the geographic location of the hospital. In cooperation with a community hospital located 100 km apart from the Institute of Pathology of the Justus Liebig University Giessen, telepathological intraoperative consultations have been performed since 1999. After preparation and staining of the cryosection in the hospital, the slide was examined in our institute using a remote-controlled microscope (Leica DMRXA) and a special telepathological software (Leica TPS1). Data were transferred via two ISDN connections in parallel. The telepathology system contains an additional macroscopic examination equipment. Up to now more than 40 telepathological consultations have been done. Time required for the microscopic diagnosis ranged between 4 and 25 minutes. The amount of time saved, compared to the transfer to the next available pathologist, was approximately 45 minutes. In our experience, telepathological diagnoses were fully in accordance with conventional diagnoses routinely performed afterwards. The application of telepathology can lead to a significant shortening of surgery time if a pathologist is locally not available. In the study presented, no diagnostic errors occurred. The additional application of a macroscopic equipment allows inspection and interactive guidance for sampling, thus preventing sampling errors.

Efficiency↗

PubMed2002

Comparison of semi-automated image analysis and manual methods for tissue quantification in pancreatic carcinoma.

Objective measurements of tissue area during histological examination of carcinoma can yield valuable prognostic information. However, such measurements are not made routinely because the current manual approach is time consuming and subject to large statistical sampling error. In this paper, a semi-automated image analysis method for measuring tissue area in histological samples is applied to the measurement of stromal tissue, cell cytoplasm and lumen in samples of pancreatic carcinoma and compared with the standard manual point counting method. Histological samples from 26 cases of pancreatic carcinoma were stained using the sirius red, light-green method. Images from each sample were captured using two magnifications. Image segmentation based on colour cluster analysis was used to subdivide each image into representative colours which were classified manually into one of three tissue components. Area measurements made using this technique were compared to corresponding manual measurements and used to establish the comparative accuracy of the semi-automated image analysis technique, with a quality assurance study to measure the repeatability of the new technique. For both magnifications and for each tissue component, the quality assurance study showed that the semi-automated image analysis algorithm had better repeatability than its manual equivalent. No significant bias was detected between the measurement techniques for any of the comparisons made using the 26 cases of pancreatic carcinoma. The ratio of manual to semi-automatic repeatability errors varied from 2.0 to 3.6. Point counting would need to be increased to be between 400 and 1400 points to achieve the same repeatability as for the semi-automated technique. The results demonstrate that semi-automated image analysis is suitable for measuring tissue fractions in histological samples prepared with coloured stains and is a practical alternative to manual point counting.

Algorithms↗