Interobserver Error Research Articles

Accuracy of cut-off value by measurement of third molar index: Study of a Colombian sample

The aim of this cross-sectional study was to test the accuracy of cut-off value of 0.08 by measurement of third molar index (I3M) in assessing legal adult age of 18 years in a sample of Colombian children and young adults. Digital orthopantomographs of 288 Colombian children and young adults (163 girls and 125 boys), aged between 13 and 22 years, were analysed. Concordance correlation coefficient (ρc) and κ statistics (Cohen's Kappa coefficient) showed that repeatability and reproducibility are high for both intra- and inter-observer error. κ statistics for intra- and inter-observer agreement in decision on adult or minor was 0.913 and 0.877, respectively. Age distribution gradually decreases as I3M increases in both girls and boys. For girls, the sensitivity test was 95.1% (95% CI 87.1%–95%) and specificity was 93.8% (95% CI 87.1%–98.8%). The proportion of correctly classified individuals was 95.1%. For boys, the sensitivity test was 91.7% (95% CI 85.1%–96.8%) and specificity was 90.6% (95% CI 82.1%–97.8%). The proportion of correctly classified individuals was 89.7%. The cut-off value of 0.08 is highly useful to determine if a subject is 18 years of age or older or not.

Is forceps more useful than visualization for measurement of colon polyp size?

To identify whether the forceps estimation is more useful than visual estimation in the measurement of colon polyp size. We recorded colonoscopy video clips that included scenes visualizing the polyp and scenes using open biopsy forceps in association with the polyp, which were used for an exam. A total of 40 endoscopists from the Busan Ulsan Gyeongnam Intestinal Study Group Society (BIGS) participated in this study. Participants watched 40 pairs of video clips of the scenes for visual estimation and forceps estimation, and wrote down the estimated polyp size on the exam paper. When analyzing the results of the exam, we assessed inter-observer differences, diagnostic accuracy, and error range in the measurement of the polyp size. The overall intra-class correlation coefficients (ICC) of inter-observer agreement for forceps estimation and visual estimation were 0.804 (95%CI: 0.731-0.873, P < 0.001) and 0.743 (95%CI: 0.656-0.828, P < 0.001), respectively. The ICCs of each group for forceps estimation were higher than those for visual estimation (Beginner group, 0.761 vs 0.693; Expert group, 0.887 vs 0.840, respectively). The overall diagnostic accuracy for visual estimation was 0.639 and for forceps estimation was 0.754 (P < 0.001). In the beginner group and the expert group, the diagnostic accuracy for the forceps estimation was significantly higher than that of the visual estimation (Beginner group, 0.734 vs 0.613, P < 0.001; Expert group, 0.784 vs 0.680, P < 0.001, respectively). The overall error range for visual estimation and forceps estimation were 1.48 ± 1.18 and 1.20 ± 1.10, respectively (P < 0.001). The error ranges of each group for forceps estimation were significantly smaller than those for visual estimation (Beginner group, 1.38 ± 1.08 vs 1.68 ± 1.30, P < 0.001; Expert group, 1.12 ± 1.11 vs 1.42 ± 1.11, P < 0.001, respectively). Application of the open biopsy forceps method when measuring colon polyp size could help reduce inter-observer differences and error rates.

Computer-assisted Cobb angle measurement from posteroanterior radiographs by a curve fitting method

Incorrect determination of the top or end vertebrae of a scoliotic curve causes measurement errors when using the Cobb method. Such problems are due to subjectivity. This study was performed to minimize subjectivity by using a curve fitting method. A digitally scanned posteroanterior radiographic image was used for each patient. User-defined midpoints of the curvature, which indicate the midpoints of the vertebrae, were used to fit the polynomial equation. The locations of the top and end vertebrae were calculated using the first derivative of the fitted polynomial equation to obtain the analytical Cobb angle. The interobserver technical error of measurements was calculated as 1.06 degrees with a reliability coefficient of 1.00. The results indicate that 100% of the variations were not related to measurement error. Small angle variations show that subjectivity was minimized.

Commentary on: The Reliability of Anthropometric Measurements Used Preoperatively in Aesthetic Breast Surgery.

Unfortunately, I could not really get enthused by this paper1 because it really states the obvious—that interobserver errors in breast surface measurements exist, but there are less observer errors in static measurements than so-called dynamic measurements, despite prestudy investigator training on standard assessment and usage of a caliper and measuring tape. In women with small breasts, this may perhaps be more surprising, and there are obviously inherent inaccuracies to consider, especially if measuring with a caliper over a concave or convex surface in which the true upper pole or lower pole may be difficult to elicit and be affected by the positioning or height of the observer. If the tape is used primarily, the measurement is subjective and will vary on contact pressure; the translation of a caliper distance to a measuring tape should show no error of course. …

Non-osteoporotic women with low-trauma fracture present altered birefringence in cortical bone

Areal bone mineral density (BMD) by DXA, although an important index, does not accurately assess risk of fragility fracture. Another bone structural parameter, the orientation of type I collagen, is known to add to risk determination, independently of BMD. Accordingly, we investigated the Haversian systems of transiliac crest biopsies from non-osteoporotic women with low-trauma fractures, matched to healthy women without fracture by age and BMD. We employed circularly polarized light (CPL) microscopy because 1) each of the extinct and bright birefringent signals of CPL corresponds to a specific collagen arrangement; and 2) CPL can employ magnification suitable to provide data, of manageable size, from the whole cortical component of a section of biopsy. Under CPL, the coaxial layers of osteons, called lamellae, appear either birefringent extinct or bright. On a section transverse to the Haversian system, the extinct lamella comprises mainly collagen forming small angles, and the bright lamella comprises mainly collagen forming large angles, relative to the general orientation of the Haversian system. We performed semi-automatic morphometry for birefringent and structural parameters for which we computed intra- and inter-observer errors. The statistical analysis used a linear mixed model to compare fracturing and non-fracturing groups while addressing pairing of fracturing and non-fracturing subjects, and linear regression to assess differences between matched subjects. We found significant reduction in 1) lamellar width and area for extinct lamella and bright lamella; 2) percentage of extinct birefringence in osteons, and 3) single osteon area; in the fracturing group; and in lamellar width in the fracturing subject of all pairs. Our results evidence the need to investigate, in a larger sample of subjects, the distribution of collagen orientation as a parameter diagnostic of increased fracture risk.

Magnitude of observer error using cone beam CT for prostate interfraction motion estimation: effect of reducing scan length or increasing exposure.

Objective:Cone beam CT (CBCT) enables soft-tissue registration to planning CT for position verification in radiotherapy. The aim of this study was to determine the interobserver error (IOE) in prostate position verification using a standard CBCT protocol, and the effect of reducing CBCT scan length or increasing exposure, compared with standard imaging protocol.Methods:CBCT images were acquired using a novel 7 cm length image with standard exposure (1644 mAs) at Fraction 1 (7), standard 12 cm length image (1644 mAs) at Fraction 2 (12) and a 7 cm length image with higher exposure (2632 mAs) at Fraction 3 (7H) on 31 patients receiving radiotherapy for prostate cancer. Eight observers (two clinicians and six radiographers) registered the images. Guidelines and training were provided. The means of the IOEs were compared using a Kruzkal–Wallis test. Levene's test was used to test for differences in the variances of the IOEs and the independent prostate position.Results:No significant difference was found between the IOEs of each image protocol in any direction. Mean absolute IOE was the greatest in the anteroposterior direction. Standard deviation (SD) of the IOE was the least in the left–right direction for each of the three image protocols. The SD of the IOE was significantly less than the independent prostate motion in the anterior–posterior (AP) direction only (1.8 and 3.0 mm, respectively: p = 0.017). IOEs were within 1 SD of the independent prostate motion in 95%, 77% and 96% of the images in the RL, SI and AP direction.Conclusion:Reducing CBCT scan length and increasing exposure did not have a significant effect on IOEs. To reduce imaging dose, a reduction in CBCT scan length could be considered without increasing the uncertainty in prostate registration. Precision of CBCT verification of prostate radiotherapy is affected by IOE and should be quantified prior to implementation.Advances in knowledge:This study shows the importance of quantifying the magnitude of IOEs prior to CBCT implementation.

Revisiting the Phenice technique sex classification results reported by MacLaughlin and Bruce (1990).

Phenice (Am J Phys Anthropol 30 (1969):297-301) reported a success rate of 96% for his method of sex determination based on three morphological features of the pelvis. Numerous studies have tested and evaluated the method with affirmative results. The results of the study by MacLaughlin and Bruce (J Forensic Sci 35 (1990):1384-1392) were inconsistent with other studies, reporting far lower rates of accuracy and a greater degree of interobserver error. The authors believe that this may be the result of the inclusion of an "ambiguous" classification category. Revised modelling using forced classification of sex provides much higher classification rates with the implication that the poor results reported by MacLaughlin and Bruce were due to methodological error for the most part.

The Use of Femoral Neck Axis Length to Estimate Sex and Ancestry.

Having multiple reliable methods of estimating sex and ancestry from various skeletal features increases the likelihood of identifying skeletal remains. Femoral neck axis length (FNAL), as measured in living individuals, has been shown to vary by sex and ancestry. FNAL has not, however, been previously measured directly from skeletonized remains and investigated for its potential use in forensic anthropological applications. This research proposes a method for measuring FNAL from skeletal remains, determines the reliability and repeatability of the measurement, and assesses the validity of FNAL in sex and ancestry estimation. Results showed low interobserver error in the measurement of FNAL (TEM=0.33 mm, R=0.99). Significant differences in FNAL were found between sexes as well as between American Black, American White, and Native American groups. FNAL can correctly classify sex in ~86% of all cases and is considered valuable to sex estimation. The value of FNAL to ancestry estimation, however, is considered limited.

Quantification of Maxillary Dental Arcade Curvature and the Estimation of Biological Ancestry in Forensic Anthropology.

Previous studies suggest that palate shape is a useful indicator of biological ancestry in human remains. This study evaluates interobserver error in ancestry estimation using palate shape and explores palate shape variation in Gullah (descendants of West Africans) and Seminole (Indigenous American) population samples using geometric morphometric analysis. Ten participants were asked to ascribe biological ancestry and shape to 28 dental casts based on a classification scheme employed in previous studies. The mean correct classification was 42.0%, indicating that the likelihood of assigning the correct ancestry is very poor and not significantly different from random assignment (p = 0.12). The accuracy analysis based on categorical classification of the casts was complemented by geometric morphometric analysis of nine 3D landmarks reflecting palate shape of 158 casts. Principal component analysis results show no difference between populations regarding palate shape, and cross-validated discriminant function analysis correctly classified only 62.0% of the specimens. Combined, these results show that previous methods to estimate ancestry are inaccurate and that this inaccuracy is probably due to a lack of palate shape differences between groups, rather than limitation of the analytical method per se. Therefore, we recommend caution should be used when choosing to apply the analysis of palate shape in forensically relevant contexts.

Infra-renal abdominal aortic calcification volume does not predict small abdominal aortic aneurysm growth

BackgroundVascular calcification is a common finding in abdominal aortic aneurysms (AAA) however whether it predicts aneurysm expansion is controversial. Objectives1) To establish a reproducible method of assessing AAA calcification using computed tomography (CT); 2) To investigate the association between AAA calcification and growth. MethodPatients were identified from a prospectively maintained small AAA surveillance database. To be included patients required at least two CT scans a minimum of 6 months apart. All patients had a maximal AAA diameter of ≤55 mm on their initial scan. Infra-renal aortic calcification volume, total infra-renal aortic volume and maximal AAA diameter were measured. Reproducibility was assessed from repeat scans performed on 31 patients. AAA growth, estimated by volume change per year, was compared between patients with baseline infra-renal aortic calcification volumes< and ≥median. Results95% agreement limits (lower, upper) for intra and inter-observer error in measuring infra-renal aortic calcification volume were 0.68, 97 mm3 and −140, 5.8 mm3, respectively. Concordance correlation coefficients for inter and intra-observer variability in measuring infra-renal aortic calcification volume were 0.99 and 0.99, respectively. Patients with infra-renal aortic calcification volume < median (n = 44) and ≥median (n = 44) had an infra-renal aortic volume increase of 6.0 cm3/yr and 7.8 cm3/yr, respectively (p = 0.66). Mean percentage infra-renal aortic volume increase/yr was found to be 4.2 ± 6.4 and 8.9 ± 6.2 for patients with and without diabetes, respectively (p = 0.003). ConclusionInfra-renal aortic calcification volume can be assessed reproducibly from CT images. Infra-renal aortic calcification volume did not predict small AAA growth.

Interobserver Variability in the Measurement of Lower Leg Compartment Pressures

To determine whether interobserver technical variations and errors in the measurement of compartment pressures may affect measurement accuracy. Four above-knee cadaveric specimens were used to create a consistent model of lower leg compartment syndrome. Thirty-eight physicians examined the limbs and measured 4 compartment pressures using the Intra-Compartmental Pressure Monitor (Stryker Orthopaedics). They were observed for correct assembly and use of the monitor. Measurements obtained were compared with known pressures. Of the total number of compartment measurements, 31% were made using the correct technique, 39% were made with lesser errors in technique, and 30% were made with catastrophic errors. Only 60% of measurements made with the correct technique were within 5 mm Hg of the standard pressure. Accuracy dropped to 42% for measurements taken with small errors in technique and 22% when a catastrophic error was committed. Variations in use of a commercially available pressure monitor exist, and errors are common. Proper use improved accuracy, but even with proper technique, 40% of the measurements were >5 mm Hg from the actual pressure. Based on our data, measurement accuracy with this device should be questioned and viewed within a range. Regular review and education of technique is strongly recommended.

Is There Any Correlation Between Patient Height and Patellar Tendon Length?

A potential specific problem of patellar tendon graft in ACL reconstruction is the possibility of graft-tunnel mismatch which could be more problematic with anatomic ACL reconstruction where the femoral tunnel is placed low on the lateral wall of the lateral femoral condyle. The occasional occurrence of this mismatch raises the question that whether a correlation exists between patient height and patellar tendon length. The purpose of the present study was to measure patellar tendon length as an anthropometric finding and to evaluate whether a correlation exists between patient height and patellar tendon length. Intra-operative measurement of patellar tendon length was carried out in 267 consecutive patients during bone-patellar tendon-bone (BTB) graft ACL reconstruction. Patient age, gender, height were recorded. The patellar tendon measurements were done independently by two surgeons and the possible inter-observer errors were checked. The data were analyzed using the Pearson correlation. The mean length of the patellar tendon was 46.4 ± 4.8 mm (Mean ± SD) with a range of 32-61 mm. The mean patient height was 177 ± 7 cm (Mean ± SD) with a range of 159-197 cm. A weak positive correlations were found between patient height and patellar tendon length (Pearson r = 0.24, P< 0.001). The linear regression equation for patellar tendon length (y, in millimeters) as a function of patient height (x, in centimeters) can be expressed as y=16.54 + 0.17x. Our study showed a weak correlation between patellar tendon length and patient height. This finding is in contrast to the usual measurements in human anthropometry in which taller individuals have normally longer tendons and ligaments. The graft-tunnel mismatch may be the result of this variation.

Sex Determination of Human Crania Using 3D Surface Scanning of the Mastoid Process

Historically, sex determination of human skulls has been dependent on visual examination and qualitative scoring of sexually dimorphic features such as the mastoid process. The accuracy of this method relies heavily on observer experience. We report a new method for sex determination based on quantitative analysis of the mastoid process. A Polhemus FastScan 3D laser scanner is employed to capture cranial surface morphology. The scan protocol generates 2 mesh models that are imported and aligned using Geomagic Design X64 software to create a single digital model per cranium. From the model, the mastoid process is isolated and its volume measured. Total cranial volume is also estimated from the model, allowing computation of a mastoid ratio (mastoid volume:cranial volume) for each specimen. A pilot study was performed utilizing a small sample of crania from known-sex Medieval Nubian individuals. Results demonstrate little overlap in the range of male vs female absolute mastoid volume. Intra-observer measurement error is low. A t-test shows significant differences (p < 0.05) between male and female mastoid ratios, demonstrating the utility of this method for sex determination. Moreover, the new method is advantageous because the scan protocol is quick; it captures a permanent record of each specimen; and unlike qualitative scoring, it can be executed consistently with minimal training. Future work will focus on evaluating inter-observer error, testing the method across population samples, and devising protocols for other dimorphic features, with the goal of developing a comprehensive multivariate method for sexing skulls based on 3D surface scanning.

Reliability study for the Rib Index in chest radiographs of a control group.

BackgroundThe Rib Index, (RI), extracted from the double rib contour sign (DRCS) on lateral spinal radiographs to evaluate rib hump deformity, (RHD), in idiopathic scoliosis, (IS), patients, has been previously introduced. Although various papers using the RI have been published, no study on its reproducibility has been reported. The aim of this report is to estimate the variations of the RI in a number of a pair set of lateral chest radiographs (LCRs). The hypothesis was that the RI should have minimal variability for each subject having successive LCRs.MethodsSeventy randomized patients who were treated in the hospital for lung diseases (mainly pneumonia or other communicable lung diseases), were initially included in the study. Each of these patients had two successive LCRs (named A and B group of radiographs) at the radiological department of the hospital, by the same technician, during the course of their treatment. The radiation source - patient distance was constant. LCRs obtained at an incorrect patient’s position, or from patients who underwent a thoracic intervention and all LCRs with symmetric hemi-thoraces were excluded from the study. The LCRs of 49 patients were deemed suitable for inclusion in the study. The RI was calculated in both (A and B) LCRs of each patient. The statistical analysis included the following techniques: paired t-test, Pearson correlation coefficient and intra- and inter-observer error using the formula (SD/√2)/2, where SD is this of the differences of the two sets of measurement (As-Bs). The SPSS v16 statistical package was used.ResultsIn the 49 pairs of LCRs there was no statistical difference of the RI, (paired t-test p< 0.314). The RI in the A and B group of LCRs was perfectly correlated (correlation coefficient = 0,924, p < 0.0001). The intra-observer error was 0.0080 while the inter-observer error 0.0213 in terms of 95% CI.ConclusionThe RI proves to be a reliable method to evaluate the thoracic deformity and the effect of surgical or non-operative treatment on the IS RHD. RI is a simple method, a safe reproducible way to assess the RHD based on lateral radiographs, without the need for any further special radiographs and exposure to additional radiation.

The reliability of Cameriere's method in Turkish children: A preliminary report

Dental age estimation in children is an important issue both legally and medically. Currently, however, there is a lack of contemporary dental age estimation standards for a Turkish population. This study assessed the accuracy of Cameriere's method by examining the panoramic radiographs of 573 healthy Turkish children between the ages of 8 and 15 years. Radiographs of the left permanent developing mandibular teeth, except wisdom teeth, were evaluated. All subjects were divided into 7 groups according to their chronological age. The Intra-class Correlation Coefficient was used to determine the intra- and inter-observer agreement error. A comparison of the distributions of estimation errors among age groups was performed using the Nemenyi test. There were no significant differences between inter-observer (p=0.352), and intra-observer readings after 2 weeks (p=0.275 and p=0.273, respectively). The dental age was underestimated when using Cameriere's method with a mean difference of −0.35 years (−0.24 years for girls and −0.47 years for boys). The median values of the differences between dental and chronological age were −0.44 years in boys (range: −3.70, 4.06) and −0.21 years in girls (range: −2.74, 3.29). In addition, the differences between dental and chronological ages in the different age groups decreased with increasing chronological age. Results from the Nemenyi test implied that Cameriere's method is more accurate for girls than for boys in this cohort of a Turkish population.

Entheseal changes and sexual division of labor in a North-African population: The case of the pre-Hispanic period of the Gran Canaria Island (11th–15th c. CE)

The aim of this paper is to investigate the relationship between entheseal changes and sexual division of labor in the pre-Hispanic population of Gran Canaria Island (Spain). Ethnohistorical records from the period of contact between Europeans and the Canarian indigenous population provide rich information about the different activities performed by men and women. For this purpose, entheseal changes in a sample of 138 individuals (82 males and 56 females) buried in ten pre-Hispanic cemeteries (11th and 15th centuries cal. CE) were analyzed. Forty-one entheses located in the clavicle, humerus, ulna and radius were analyzed (fibrous and fibro-cartilaginous attachment sites). Entheses were graded using a visual and descriptive standard which summarized the entheseal changes. This method interprets the changes as a sign of robustness on a scale from low to high development and includes enthesopathies. The intra- and inter-observer error of this method was minimal. Sex differences in the degree of robustness, bilateral asymmetry, sexual dimorphism and principal components analyses were tested in this sample. The results indicate significant variance in the entheseal robustness between males and females. They also suggest the impact of certain biomechanical chains (pronosupination, shoulder rotation, etc.) in entheseal changes. These results contribute to an interdisciplinary approach to the study of the sexual division of labor in the pre-Hispanic society of Gran Canaria.

Measurement standards for human metacarpals.

Standards for measuring the metacarpals are absent from commonly used osteometric guides. Perhaps the closest to a set of standard measurements in common use today are those proposed by Scheuer and Elkington (Scheuer and Elkington: J Forensic Sci 38 (1993) 769-788) for forensic sex assessment. They include caliper measurements of interarticular length, base and head width, base and head height, and maximum midshaft diameter. Over the last decade, a new set of measurements that encompass similar dimensions to those used by Scheuer and Elkington, but which are taken with a mini-osteometric board (MOB) have been developed by the lead author. Use of the MOB avoids the need to manipulate both the bone and calipers in three-dimensional space and causes less strain on the hands. However, the question of intra- and interobserver accuracy has not been adequately addressed for either set of measurements. The purpose of this study was to test both the Scheuer/Elkington and MOB measurements on 20 hands from 10 anatomical skeletons for intra- and inter-observer accuracy. The study found that 92% of the MOB measures had a lower intraobserver error, and 88% had a lower interobserver error than did the caliper measurements. It also found that the maximum midshaft diameter measurement used by Scheuer and Elkington is more repeatable than a mediolateral diameter. Overall, 88% of the 25 MOB measurements had median intraobserver error rates of under 1.5%, compared with 60% of the caliper measurements. Furthermore, the MOB measurements as a set were taken 10 to 12% faster than the caliper measurements.

Advances in clinical estimation of foetal weight before delivery

Accurate estimation of foetal weight is of paramount importance before delivery. Clinical estimation of foetal weight is an important and necessary skill in management of obstetrics patients because of its simplicity; and if it is found to be as accurate as sonographic measurement as some studies suggest, it may be considered for screening of foetal weight especially in low-resource settings where ultrasound is unavailable. The aim of this review is to search for various literatures where clinical methods of foetal weight estimation were used and to examine these methods critically for possible recommendation for their use among obstetrics residents and healthcare practitioners. Electronic search of Medline, Pub Med, Health Internetwork Access to Research Initiative (HINARI) and Google Scholar databases from 1953 to 10th December 2014 was conducted for studies which compared clinical and sonographic foetal weight estimation. Various formulae have been suggested by researchers over the years. The methods however depend on the clinical dexterity of clinicians' and not on specific measurements. No simple and easily applied formula has yet been suggested to transform an external maternal measurement into an estimated foetal weight. Researchers on estimation of foetal weight should work towards a consensus and reproducible formula for clinical foetal weight estimation. Symphysio fundal height (SFH) measurement with a tape-measure seems a simple clinical method because it is cheap, readily available, non-invasive and acceptable to patients. These skills should be practiced by senior obstetricians and taught to midwifes, house officers, medical officers and obstetrics residents. It is however subjected to various degrees of intra-observer and inter-observer errors and studies comparing the different formulae are lacking. Therefore, further researches are needed to improve reliability and reproducibility of these clinical methods. The reliability of other clinical methods other than Dare' method should also be explored.

The Definition of Multiple Sclerosis: Implications for Research

The original McDonald criteria for the diagnosis of MS were intended for the use of practicing physicians [1]. These criteria, and subsequent revisions [1-3], regard MS as a clinical problem, diagnosed by both clinical and paraclinical criteria. Emphasis is placed on the importance of obtaining objective evidence of dissemination of lesions in space and time, and the exclusion of better explanations of the clinical findings. In opposition to what might be considered a clinical ‘definition’ of MS, is a pathological definition, as it could be argued that tissue studies are the only way to prove an MS diagnosis and to exclude alternative diagnostic possibilities [1,4,5]. What are the relative merits of a clinical vs. pathological definition of MS? A clinical definition of MS has several difficulties. Firstly, the original criteria had low sensitivity and specificity for the diagnosis of MS in nonWestern populations: the 2010 revision of the McDonald criteria addressed this issue [3]. Secondly, a clinical definition of MS excludes subclinical cases of MS that are identifiable by pathological studies, e.g. at autopsy [4]. The real merit of using a clinical definition of MS is obviously in decision trees. That is, the division of patients in the clinical setting into MS or not-MS categories facilitates decisions about treatment options and other aspects of patient management [1-3]. As a practicing pathologist, I am tempted to argue for a pathological definition of MS, as I would expect that identification of inflammatory and demyelinating lesions typical of MS will more readily exclude Non-MS Pathologies than will clinical and paraclinical criteria. Also, a pathological definition will have optimal value in answering research questions about tissue changes in MS. However, a pathological definition of MS has several difficulties. Firstly, every pathologist is aware of both intra-observer and inter-observer variability in interpreting tissue pathology: an influential study more than 20 years ago showed that even expert pathologists, reviewing identical slides from the same breast biopsy material and applying known diagnostic criteria, often make different diagnoses [6]. Secondly, a pathological definition has minimal utility as a clinical tool, as CNS biopsies are not performed routinely in patients with putative MS and are unlikely to become part of routine assessment in the future. Thus, we are left with the clinical definition of MS. I cannot comment on the extent of intraobserver or inter-observer error among neurologists expert in MS, but expect that there must be some: the original McDonald criteria identified a subjective component to the diagnosis of MS [1]. Moreover, the clinical definition of MS is heuristic. By this, I mean that the clinical definition is a practical definition, which is neither perfect nor optimal but provides an approximation that is sufficient for its main purpose, namely to make clinical decisions.

Mathematical (diagnostic) algorithms in the digitization of oral histopathology: The new frontier in histopathological diagnosis

The technological progress in the digitalization of a complete histological glass slide has opened a new door in the tissue based diagnosis. Automated slide diagnosis can be made possible by the use of mathematical algorithms which are formulated by binary codes or values. These algorithms (diagnostic algorithms) include both object based (object features, structures) and pixel based (texture) measures. The intra- and inter-observer errors inherent in the visual diagnosis of a histopathological slide are largely replaced by the use of diagnostic algorithms leading to a standardized and reproducible diagnosis. The present paper reviews the advances in digital histopathology especially related to the use of mathematical algorithms (diagnostic algorithms) in the field of oral histopathology. The literature was reviewed for data relating to the use of algorithms utilized in the construction of computational software with special applications in oral histopathological diagnosis. The data were analyzed, and the types and end targets of the algorithms were tabulated. The advantages, specificities and reproducibility of the software, its shortcomings and its comparison with traditional methods of histopathological diagnosis were evaluated. Algorithms help in automated slide diagnosis by creating software with possible reduced errors and bias with a high degree of specificity, sensitivity, and reproducibility. Akin to the identification of thumbprints and faces, software for histopathological diagnosis will in the near future be an important part of the histopathological diagnosis.