Evaluate Interobserver Agreement Research Articles

Magnetic resonance imaging of the temporomandibular joint: Interobserver agreement in subjective classification of disk status

Objectives. To determine interobserver agreement in interpretation of magnetic resonance images of the temporomandibular joint by independent observers and to evaluate interobserver agreement within each subjectively assigned category. Study Design. Sixty magnetic resonance images of adolescent temporomandibular joints were randomly drawn for evaluation by 4 observers who had not previously worked together. All observers independently classified disk position on sagittal magnetic resonance images according to written classification criteria consisting of 6 categories. Results. Kappa statistics of agreement show moderate agreement among all observers for both medial (95% CI, 0.486-0.622) and lateral (95% CI, 0.450-0.566) components of the joint. Disk displacement without reduction was the category with the greatest agreement among all observers (κ = 0.914). Conclusion. Moderate to substantial observer agreement across all defined categories of disk status may be achieved among a number of observers when standardized classification criteria are used. Interobserver agreement is, however, not uniform across all categories of disk position described. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2000;90:102-7)

MR angiography as a screening tool for intracranial aneurysms: feasibility, test characteristics, and interobserver agreement.

MR angiography may be an appropriate tool to screen for unruptured intracranial aneurysms. Feasibility, test characteristics, and interobserver agreement in evaluation of MR angiograms were assessed by members of the MARS (Magnetic resonance Angiography in Relatives of patients with Subarachnoid hemorrhage) Study Group. We screened 626 first-degree relatives of a consecutive series of 193 patients with subarachnoid hemorrhage examined at two institutions. We used MR imaging and MR angiography (three-dimensional time-of-flight imaging at both institutions and additional three-dimensional phase-contrast imaging at one institution). Three observers independently assessed the MR angiograms. Conventional angiography was performed in relatives with possible or definite aneurysms on MR angiography and was considered the standard of reference. Thirty-three aneurysms were found in 25 (4%; 95% confidence interval [CI], 3-6%) of 626 relatives. Thirteen (8%) of 169 relatives who refused screening had MR-related reasons; an additional six persons could not be screened because of contraindications for MR imaging (pregnancy, n = 1; claustrophobia, n = 5). The positive predictive value of MR angiography was 100% (95% CI, 79-100%) for "definite" aneurysms and 58% (95% CI, 28-85%) for "possible" aneurysms. Sensitivity of MR angiography was estimated at 83% (95% CI, 65-94%) and specificity at 97% (95% CI, 94-98%). Interobserver agreement in the evaluation of MR angiograms was poor (kappa < .30), probably because different diagnostic strategies used by individual observers resulted in different use of the assessment category "possible aneurysm." MR angiography is a feasible screening tool for detection of intracranial aneurysms. Positive predictive value, sensitivity, and specificity are acceptable when at least two neuroradiologists independently assess MR angiograms.

Diagnosis of crystal-induced arthritis by synovial fluid examination for crystals: Lessons from an imperfect test

Diagnosis of the crystal-induced arthritides is primarily based on microscopic identification of crystals in synovial fluid. Therefore, we aimed to estimate the operating characteristics of this test and demonstrate its clinical use. Medline was searched for relevant studies. Sensitivity and specificity of identification of crystals were calculated, as were measures of interobserver agreement. Likelihood ratios were calculated and curves constructed using the solutions to the Bayesian equations. Four studies were identified. The rates of interobserver agreement were low; the false-negative rates in identifying calcium pyrophosphate crystals were particularly high. Only one study allowed calculation of the test operating characteristics, and this was a study that used synthetic crystals and therefore may not be directly useful in a clinical setting. There is a paucity of data about the accuracy of crystal identification. As it is clearly not a perfectly sensitive and specific test, the most prudent diagnostic strategy, as with essentially all diagnostic tests, is to establish a posterior probability of disease from a prior probability, based on the clinical features of the patient. Determining the operating characteristics of this test in conventional and reference laboratories should be a research priority for high quality clinical research on crystal arthropathies.

Reliability of the Canadian Emergency Department Triage and Acuity Scale: Interrater Agreement

Study objective: To determine the rate of interobserver reliability of the Canadian Emergency Department Triage and Acuity Scale (CTAS). Methods: Ten physicians and 10 nurses were randomly selected to review and assign a triage level on 50 ED case summaries containing presenting complaint, mode of arrival, vital signs, and a verbatim triage note. The rate of agreement within and between groups of raters was determined using κ statistics. One-way, 2-way analysis of variance (ANOVA) and combined ANOVA were used to quantify reliability coefficients for intraclass and interclass correlations. Results: The overall chance-corrected agreement κ for all observers was .80 (95% confidence interval [CI] .79 to .81), and the probability of agreement between 2 random observers on a random case was .539. For nurses alone, κ=.84 (95% CI .83 to .85, P =.598), and for doctors alone, κ=.83 (95% CI .81 to .85, P =.566). The 1-way, 2-way ANOVA and combined ANOVA showed that the reliability coefficients (84%) for both nurses and physicians were similar to the κ values. A combined ANOVA showed there was a .2-point difference with physicians assigning a higher triage level. Conclusion: The high rate of interobserver agreement has important implications for case mix comparisons and suggests that this scale is understood and interpreted in a similar fashion by nurses and physicians. [Beveridge R, Ducharme J, Janes L, Beaulieu S, Walter S: Reliability of the Canadian Emergency Department Triage and Acuity Scale: Interrater agreement. Ann Emerg Med August 1999;34:155-159.]

Screening for Dementia in the Outpatient Setting: The Time and Change Test

To develop and validate the Time and Change (T&C) test, a simple, standardized method for detecting dementia in a diverse older outpatient population with varying levels of education. A prospective cohort validation study. Two outpatient clinics at an urban teaching hospital. The concurrent validation sample consisted of 100 consecutive outpatients 70 years of age or older who were 58% non-white and had a 16% dementia prevalence rate and educational levels ranging from 0 to 17+ years. Reliability was tested in a sample of 42 consecutive outpatients 75 years of age or older with a 36% dementia prevalence rate. T&C ratings were validated against a reference standard based on the Blessed Dementia Rating Scale and the Mini-Mental State Examination. Reliability, contribution to physician recognition of dementia, and ease of use were assessed. In the outpatient setting, the T&C had a sensitivity of 63%, specificity of 96%, a negative predictive value of 93%, a positive predictive value of 77%, and test-retest and inter-observer reliability agreement rates of 95% and 100%, respectively. When T&C results were added to the physician's documentation of dementia, the number of missed cases decreased from 44% to 19%, and the number of overcalled cases decreased by 100%. When timed cut points were added, the T&C test had a sensitivity of 94 to 100%, specificity of 37 to 46%, negative predictive value of 98 to 100%, positive predictive value of 23 to 25%, and test-retest and inter-observer agreement rates of 82% and 70 to 75%, respectively. The T&C test is a simple, accurate, reliable, performance-based tool that can improve physician ability to recognize dementia in diverse outpatient populations.

Interobserver agreement in sonographic diagnosis of breast tumors

Objective: To evaluate interobserver agreement in the interpretation of breast ultrasonography. Methods: 55 breast masses (30 benign, 24 malignant) were interpreted by seven radiologists using a CRT viewing station. US criteria for differentiating between benign and malignant lesions included shape, border, boundary echoes, internal echoes, posterior echoes, and bilateral shadows. Each criterion and the observers' final impression was scored using the 5-point rating scales. For analyzing interobserver agreement, the kappa ( κ) values were employed. Results: The κ values of shape and posterior echoes were significantly higher than those of the other four criteria ( P<0.05). Agreement was intermediate in border and internal echoes, and was low in boundary echoes and bilateral shadows. Agreement in the senior group (four observers) was relatively higher than that in the junior group (three observers) for all criteria but for internal echoes. Easily-diagnosed cases showed significantly higher κ values compared with more ambiguous cases ( P<0.05). Conclusion: Interobserver agreement in shape and posterior echoes was significantly higher than those of the other four criteria. Agreement was significantly dependent on case difficulty.

The Time and Change Test: A Simple Screening Test for Dementia

Although dementia screening tests are available, they have not gained widespread use in hospital or primary care settings. Our goal was to develop a simple, standardized, performance-based test incorporating real-world activities to augment screening efforts in older populations: the Time and Change (T&C) Test. The study followed a prospective cohort design, involving medicine and surgery services at an urban teaching hospital. From consecutive admissions, 776 participants aged 70-98 years, 14% with dementia, were enrolled. T&C ratings were validated against a reference standard based on the modified Blessed Dementia Rating Scale and the Mini-Mental State Examination (MMSE). Convergent validity with other cognitive measures, test-retest agreement, and interobserver reliability were assessed. The T&C Test had a sensitivity of 86%, specificity of 71%, and negative predictive value of 97%. The T&C Test demonstrated convergent agreement with three cognitive measures, agreeing most strongly with the MMSE (r = .58). Test-retest and interobserver agreement rates were 88% and 78%, respectively. Education explained 3% of the variance of the T&C Test, compared with 13% of the MMSE. The T&C Test took a mean of 22.9 seconds to complete and was acceptable to participants. Refusal of any test component occurred in 39 individuals (5%). The T&C Test is a simple, accurate, reliable, performance-based tool for detection of dementia. With its quick, easy-to-use, real-world nature, we hope the T&C Test will be used for widespread cognitive screening in older populations.

Usefulness of videoduodenoscopy and vital dye staining as indicators of mucosal atrophy of celiac disease: assessment of interobserver agreement

Background: The present study was designed to determine the diagnostic usefulness of videoduodenoscopic inspection alone and the addition of vital dye staining in the detection of celiac disease. We additionally sought to evaluate interobserver agreement for specific duodenoscopic markers of mucosal atrophy. Methods: One hundred sixty-seven consecutive subjects who underwent duodenoscopy for intestinal biopsy were included in a prospective controlled study. Endoscopic examination was performed by experienced endoscopists according to a set protocol using methylene blue (1%) dye. All procedures were recorded on videotape, but only 20 (10 with atrophy and 10 normal) were used in a blinded, independent, randomized analysis by five reviewers to evaluate interobserver agreement. Endoscopic signs indicative of mucosal atrophy were as follows: reduction in the number or loss of Kerkring's folds, “scalloped” folds, “mosaic pattern,” and visualization of the underlying blood vessels. Results: Eighty-seven patients had celiac disease (57 newly diagnosed, 30 when treated). Seven treated patients had nonatrophic mucosa. In 80 patients the final diagnosis excluded celiac disease. Videoendoscopic inspection alone correctly identified 75 of 80 patients with complete mucosal atrophy and 86 of 87 with normal mucosa. False-negative diagnoses occurred in treated celiac patients with mild atrophy. Mosaic pattern (89%) and scalloped folds (86%) were the most useful endoscopic signs. Vital dye staining, as assessed by experienced endoscopists, provided identical results to those obtained by inspection alone. Sensitivity, specificity, and positive and negative predictive values for the presence of one or more than one feature were 94%, 100%, 100%, and 96%, respectively. The agreement (κ statistics) among observers was excellent for the mosaic pattern (κ: 0.76 for both the videoendoscopic inspection alone and dye staining) and the scalloped folds (κ: 0.83 and 0.76, respectively) and was fair (κ: 0.41 and 0.59, respectively) for the reduction in the number or loss of duodenal folds. Conclusion: This study confirms that videoduodenoscopy is useful in the detection of intestinal atrophy. Dye staining produces a better delineation of scalloped folds and mosaic pattern in the atrophic mucosa, but did not provide additional information to the expert endoscopist. Finally, interobserver agreement was excellent for the most prevalent signs. (Gastrointest Endosc 1998;47:223-9.)

Evaluation of interobserver agreement of cardiotocograms

Objective: To evaluate interobserver agreement in visual analysis of each cardiotocographic event. Methods: Three experts independently divided 16 antepartum and 17 intrapartum cardiotocograms into baseline segments, accelerations and decelerations, according to the FIGO guidelines. Baseline segments were further classified as having normal, reduced or increased variability and decelerations as early, late and variable. Uterine activity was divided into tonus and contractions. Agreement was assessed by the proportions of agreement ( pa) with 95% confidence intervals. Results: Reproducibility in assessment of baseline segments with normal variability, accelerations and uterine activity was acceptable ( pa = 0.56–0.71) whereas that of other segments was not ( pa = 0.14–0.45). Conclusions: Analysis of most cardiotocographic events is poorly reproducible, even when experts use the FIGO guidelines. This may be explained by some still ambiguous guidelines, by eyeball limitations in evaluation of subtle events, and by the incapacity of busy clinicians to assess complex and multiple cardiotocographic events in a systematic and disciplined fashion.

The reproducibility of the results of transvaginal sonography of the uterus in patients with abnormal uterine bleeding.

Our objectives were to determine the reproducibility, or interobserver agreement, of transvaginal sonographic imaging of the uterus in patients with abnormal uterine bleeding and to identify the effect of observer experience. Transvaginal ultrasound findings of 235 patients with abnormal uterine bleeding were recorded systematically on videotape. Recordings were reviewed by three observers who had different levels of experience, and who were asked to judge the endometrium/uterine cavity and myometrium separately as being normal, abnormal or inconclusive, according to predefined criteria. Reproducibility was expressed by the observed rates of interobserver agreement and by kappa statistics. The differences in agreement between observer pairs were analyzed by means of McNemar's chi 2 test. The observed rates of agreement for the judgement of the endometrium/uterine cavity varied from 0.85 to 0.89, with a kappa value ranging from 0.70 to 0.78 between observers. The judgment of the myometrium resulted in agreement rates of 0.86-0.91 and kappa values of 0.67-0.80. Although the effect of experience was evident, the differences in agreement between observers were not significant (p > 0.01). The reproducibility of the results of transvaginal sonography of the uterus in patients with abnormal uterine bleeding was good. Observations of the endometrium/ uterine cavity with a normal appearance were the most highly reproducible, with the smallest effect of observer experience. This may reduce the need for invasive diagnostic procedures in patients with abnormal uterine bleeding.

Histological grading of breast cancer: a study of reproducibility of consensus grading

Summary There has been a resurgence of interest in the use of histological grade in predicting prognosis in patients with breast cancer, although several studies have questioned the reproducibility of the techniques used. Interobserver agreement rates of 90% have been reported by the Nottingham group, recognized experts in the field, but a previous study from this institution showed only a 70% agreement rate between two patho- logists independently reviewing histological sections. This study reports the results of an attempt to improve internal consistency in reporting histological grade by using established, well defined criteria, and a consensus opinion by pathologists ‘trained’ in the method. Criteria established by the Nottingham group were used by three pathologists to obtain a consensus histological grade in 98 cases of breast cancer, assessed on two occasions at an interval of 6 months. The intra-observer agreement rate of 86 % showed an improvement on the previous interobserver agreement rate, and is comparable to agreement rates of 90% reported by the Nottingham group. Relative disagreement rate (RDR) of 0.10 (95% CI 0.05–0.19) and kappa statistic 0.77 (95% CI 0.66–0.88) also showed improvement over previous results, and compares favourably with other studies. The results suggest ‘training’ of pathologists in assessing histological grade, strict adherence to guidelines, and a consensus opinion, may all contribute to greater reproducibility.

Interobserver agreement in the results of Doppler examinations of extrauterine pelvic tumors

The aim of this study was to evaluate interobserver agreement in the results of Doppler measurements of peak systolic velocity (PSV), time-averaged maximum velocity (TAMXV) and the color content of tumor scans in extrauterine pelvic tumors. The results of transvaginal color and spectral Doppler examinations of 66 extrauterine pelvic masses obtained by two observers experienced in ultrasonography were compared. Each observer aimed to obtain the highest possible Doppler shift from arteries in the wall, septa and solid parts of each tumor. Tumor vascularization was assessed in terms of the 'tumor color score', i.e. the color content of the Doppler scan as rated for the tumor as a whole by each observer on a visual analog scale. The tumors were classified according to arbitrarily chosen cut-off limits for the tumor color score, the highest tumor TAMXV and the highest tumor PSV. Inter-class correlation coefficient values for TAMXV and PSV were < or = 0.75, whereas that for tumor color score was 0.89. Interobserver agreement was complete for the detection of color in tumors (Kappa value 1.0), excellent for the recording of arterial Doppler shift spectra from tumors (Kappa value 0.82), and moderate or good for classifying tumors based on cut-off limits for TAMXV, PSV (Kappa values ranging from 0.44 to 0.67) and tumor color score (Kappa values ranging from 0.59 to 0.66).(ABSTRACT TRUNCATED AT 250 WORDS)

Interobserver Variation in Tumor Staging

Interobserver agreement in cardioesophageal and rectal tumor evaluation is generally good, especially for uT1 and uT4 tumors. Diagnosis of a uT2 tumor is difficult and results in poor agreement. However, the proportion of agreement is satisfactory for distinguishing tumors that invade the mediastinal or the perirectal fat from those that do not, a situation that may be the most relevant from a therapeutic point of view. In cases of cardioesophageal tumor, agreement for metastatic LN is lower and depends on the sites involved, with the best agreement for intra-abdominal LN, which may indicate a worse prognosis. Lack of agreement in EUS images can be avoided by precise manipulation of the echoendoscope in the upper part of the mediastinum and by improving training and the definitions regarding EUS.

Observer variability in the histologic assessment of oral premalignant lesions.

Histopathologic examination of oral leukoplakias has a major impact on the assessment of prognosis and treatment planning. We investigated the extent of agreement in grading epithelial dysplasia between pathologists with the same or different educational backgrounds. Two general pathologists and two oral pathologists were each given 100 sections of oral leukoplakia to grade from no dysplasia to carcinoma in-situ. The interobserver agreement rates were in the range of 49% to 69%. The calculated kappa values were in the range of 27% to 45%, showing poor to moderate agreement between the pathologists. When comparing the kappa values between the two pairs of pathologists with the same education, these values did not diverge from the general level of kappa values, indicating that the interobserver variability was due to individual differences rather than to educational background.

Further evaluation of reproducibility and prognostic value of histologic typing and grading in FIGO stage I ovarian cancer patients without systemic locoregional adjuvant treatment.

In order to analyse the reproducibility and prognostic value of histologic typing and different methods of histologic grading, 102 hematoxylin and eosin stained slides of primary FIGO stage I ovarian cancers of the common epithelial types were evaluated. Patients were treated by surgery only. Histologic typing was done using the FIGO criteria and overall total agreement was 61%. Survival was not statistically significant (P-value range: 0.31-0.66). For grading, three different methods were used: (a) the 'intuitive' method; (b) the FIGO method; and (c) the so-called Pathology Research and Practice (PRP) method, which is based on invasion, architecture and nuclear atypia. The best intra- and interobserver results were obtained with the PRP criteria (interobserver agreement rate: 84.3%, varkappa 0.67; intraobserver agreement rate: 87.3%, K 0.76). Univariate survival analyses showed significant differences between grades for all methods and observers. Results of the PRP method were clearly better than for the FIGO method (PRP, Mantel-Cox range 6.70-24.52,P-value range 0.07 - < 0.0001; FIGO, Mantel-Cox range 5.31-6.77,P-value range 0.07-0.034). The 5-year survival per grade showed considerable variation within and between the observers, and was higher with higher grade. We conclude that the assessment of histologic type was reproducible but prognostically not significant in this set of FIGO stage I ovarian cancer patients. The intra- and interobserver reproducibility of the same grading method was fair to good, and showed highly significant results for survival from the PRP method. However, application of different grading methods could result in considerable prognostic variations for the 'same' grades.

Technique for Determining Glaucomatous Visual Field Progression by Using Animation Graphics

The first two visual field examinations of each of 16 glaucoma suspects and 16 glaucoma patients, who were followed up for a median of 7.46 years with seven examinations, were averaged. Three-dimensional color-coded images of the visual field were then generated. After correcting for test-retest variability, the images, as well as additional interpolated images, were aligned and presented in rapid succession to create an animation sequence. Five glaucoma specialists trained themselves to classify the visual fields as either progressing or not progressing. The interobserver and intraobserver agreement rates were then calculated. Perfect agreement (100% concordance) between the observers was obtained for 18 (56.3%) subjects, and at least 80% concordance was obtained for 27 (84.4%) subjects. Of the eight sequences that were repeated to test intraobserver agreement, four of the five observers had a value of at least 87.5%.

Effects of chemical restraint on the endoscopic appearance of laryngeal and pharyngeal anatomy and sensation in adult cattle

Summary Effects of 2 drugs commonly used for chemical restraint of cattle were evaluated for their effect on laryngeal and pharyngeal anatomy, function, and response to stimuli. Eighteen adult Jersey cows, free of respiratory tract disease, were studied. Cows were assigned at random to 1 of 3 treatment groups. Endoscopic evaluations were performed before and at a predetermined time interval after administration of each drug. Responses to stimuli were evaluated by stimulating 7 preselected sites (epiglottis, left and right arytenoid cartilages, left and right vocal folds, and left and right dorsolateral pharyngeal walls) with a closed, transendoscopic biopsy probe. Xylazine HCl (0.05 mg/kg of body weight, IV) was administered to group-1 cows (n = 6), and endoscopy was repeated 5 minutes after administration of the drug. Xylazine (0.07 mg/kg, IV) was administered to group-2 cows (n = 6), and endoscopy was repeated 5 minutes after administration of the drug. Acepromazine maleate (0.035 mg/kg, IV) was administered to group-3 cows (n = 6), and endoscopy was repeated 10 minutes after administration of the drug. Responses to stimuli were scored as brisk (0), moderate (1), slow (2), and absent (3). Scores for responses to stimuli were compared, using the Wilcoxon signed-rank test for data within groups, and a general linear models procedure, using the Kruskal-Wallis test between groups. Interobserver agreement rates were generated for each group. A value of P&lt; 0.05 was considered significant. Xylazine profoundly changed laryngeal sensitivity and function at both dosages. The corniculate processes of the arytenoid cartilages were observed to be in a markedly adducted position after sedation. Response to stimuli was significantly (P = 0.03) slower than normal after sedation, using both dosages. Displacement of the soft palate dorsal to the epiglottis was persistent in 50% of the cows after stimulation tests subsequent to sedation with xylazine. Acepromazine had a mild effect on laryngeal sensitivity and function. The corniculate processes of the arytenoid cartilages were observed in paramedian position after sedation. Acepromazine did not significantly affect responses to stimuli. Effects of sedation on responses to stimuli were not significantly different for groups 1 and 2. However, effects for group 3 were significantly different from those for groups 1 and 2 (P = 0.006 and 0.004, respectively). Endoscopic evaluation of the proximal portion of the respiratory tract of cattle should be performed without sedation, when possible. If sedation is required to facilitate restraint for endoscopy, acepromazine maleate is recommended over xylazine on the basis of results of this study.

Interobserver agreement using computed radiography in the adult intensive care unit

We determined whether computed radiographs in an adult intensive care unit produce greater agreement between readers in descriptions of radiologic findings and interval changes. Fifty-six conventional radiographs and 56 computed radiographs were obtained on 28 patients. Computed and conventional radiographs were imaged simultaneously in a single exposure with the use of a sandwich cassette. The two sets of films per patient were taken less than 1 week apart. Four readers evaluated the chest films and judged interval changes with the use of standardized confidence scales. Overall exposure and film quality also were evaluated. Computed radiographs were rated better in overall quality. Tubes and lines were detected with comparable accuracy. Interobserver agreement in the evaluation of radiologic descriptors was generally greater with computed radiographs (intraclass correlation). No differences were noted in interobserver agreement in the judgment of interval changes. The diagnostic usefulness of computed radiography is comparable to conventional films in the intensive care unit. The higher interobserver agreement rate for radiologic descriptors with computed radiography is an added advantage of the system.

A multi-institutional study of interobserver agreement in the evaluation of dementia with rCBF/SPET technetium-99m exametazime (HMPAO)

Although specific patterns of technetium-99m exametazime [99mTc-hexamethylpropylene amine oxime (HMPAO)] brain single-photon emission tomography (SPET) uptake have been described for patients with dementia, no multi-institutional study has evaluated interobserver agreement. Interobserver agreement for 99mTc-HMPAO brain SPET uptake patterns in 50 clinically diagnosed demented subjects from four institutions were studied. Neurologists classified these subjects as presumed Alzheimer's disease (n = 21), confirmed Alzheimer's disease (n = 10), multi-infarct dementia (n = 9), HIV-related dementia (n = 7), or "mixed" (n = 3). In addition 20 normal (five per institution) 99mTc-HMPAO studies were included in a randomized blinded evaluation by three readers each from a different institution. Readers classified the general appearance of the images in one of four categories: normal, globally decreased uptake, focal areas of decreased uptake, and patchy changes in uptake. Consensus results show a sensitivity of 72% and specificity of 79% for identifying abnormalities in scans of demented subjects. Readers also rated 99mTc-HMPAO uptake in eight designated regions in each hemisphere. Significant reader agreement (P < 0.01) for the classification by general appearance and the ratings of regional uptake was obtained. This study demonstrates that interpretation of regional cerebral blood flow/SPET images is concordant across multiple institutions and readers.

The reliability of staging and grading of bladder tumours. Impact of misinformation on the pathologist's diagnosis.

The influence of misinformation on the reliability of the histopathological classification of bladder tumours was analysed. Four consultant pathologists assessed 40 biopsy specimens of bladder tumours staging invasion and grading the specimens according to the Bergkvist classification. A random sample of 20 specimens was accompanied by systematically distorted information ("bias"-unknown to the pathologists) about previous histological grading of the patient (bias group); the other 20 specimens were used as control group (non bias group). After 6 months a second round with the same specimens was arranged to assess the influence of bias on the intraobserver variation. Using kappa (kappa) statistics the chance corrected interobserver agreement rate was poor both in staging of invasion and grading according to the Bergkvist classification (kappa < 0.50). The kappa values in the intraobserver study ranged from poor to excellent with a tendency towards lower kappa when the observer had been biased. The kappa values in the assessment of malignancy were acceptable to excellent. False information did not affect the pathologists' diagnosis significantly.