Dermoscopy of pigmented skin lesions: results of a consensus meeting via the Internet

BACKGROUND

There is a need for better standardization of the dermoscopic terminology in assessing pigmented skin lesions.

OBJECTIVE

The virtual Consensus Net Meeting on Dermoscopy was organized to investigate reproducibility and validity of the various features and diagnostic algorithms.

METHODS

Dermoscopic images of 108 lesions were evaluated via the Internet by 40 experienced dermoscopists using a 2-step diagnostic procedure. The first-step algorithm distinguished melanocytic versus nonmelanocytic lesions. The second step in the diagnostic procedure used 4 algorithms (pattern analysis, ABCD rule, Menzies method, and 7-point checklist) to distinguish melanoma versus benign melanocytic lesions. kappa Values, log odds ratios, sensitivity, specificity, and positive likelihood ratios were estimated for all diagnostic algorithms and dermoscopic features.

RESULTS

Interobserver agreement was fair to good for all diagnostic methods, but it was poor for the majority of dermoscopic criteria. Intraobserver agreement was good to excellent for all algorithms and features considered. Pattern analysis allowed the best diagnostic performance (positive likelihood ratio: 5.1), whereas alternative algorithms revealed comparable sensitivity but less specificity. Interobserver agreement on management decisions made by dermoscopy was fairly good (mean kappa value: 0.53).

CONCLUSION

The virtual Consensus Net Meeting on Dermoscopy represents a valid tool for better standardization of the dermoscopic terminology and, moreover, opens up a new territory for diagnosing and managing pigmented skin lesions.

Rapid diagnostic tests compared with malaria microscopy for guiding outpatient treatment of febrile illness in Tanzania: randomised trial

OBJECTIVE

To compare rapid diagnostic tests (RDTs) for malaria with routine microscopy in guiding treatment decisions for febrile patients.

DESIGN

Randomised trial.

SETTING

Outpatient departments in northeast Tanzania at varying levels of malaria transmission.

PARTICIPANTS

2416 patients for whom a malaria test was requested.

INTERVENTION

Staff received training on rapid diagnostic tests; patients sent for malaria tests were randomised to rapid diagnostic test or routine microscopy

MAIN OUTCOME MEASURE

Proportion of patients with a negative test prescribed an antimalarial drug.

RESULTS

Of 7589 outpatient consultations, 2425 (32%) had a malaria test requested. Of 1204 patients randomised to microscopy, 1030 (86%) tested negative for malaria; 523 (51%) of these were treated with an antimalarial drug. Of 1193 patients randomised to rapid diagnostic test, 1005 (84%) tested negative; 540 (54%) of these were treated for malaria (odds ratio 1.13, 95% confidence interval 0.95 to 1.34; P=0.18). Children aged under 5 with negative rapid diagnostic tests were more likely to be prescribed an antimalarial drug than were those with negative slides (P=0.003). Patients with a negative test by any method were more likely to be prescribed an antibiotic (odds ratio 6.42, 4.72 to 8.75; P<0.001). More than 90% of prescriptions for antimalarial drugs in low-moderate transmission settings were for patients for whom a test requested by a clinician was negative for malaria.

CONCLUSIONS

Although many cases of malaria are missed outside the formal sector, within it malaria is massively over-diagnosed. This threatens the sustainability of deployment of artemisinin combination treatment, and treatable bacterial diseases are likely to be missed. Use of rapid diagnostic tests, with basic training for clinical staff, did not in itself lead to any reduction in over-treatment for malaria. Interventions to improve clinicians' management of febrile illness are essential but will not be easy.

TRIAL REGISTRATION

Clinical trials NCT00146796 [ClinicalTrials.gov].

Surface microscopy of pigmented basal cell carcinoma

OBJECTIVES

To describe the relevant morphologic features and to create a simple diagnostic method for pigmented basal cell carcinoma (BCC) using in vivo cutaneous surface microscopy (ie, dermoscopy, dermatoscopy, or oil epiluminescence microscopy).

DESIGN

Pigmented skin lesions were photographed in vivo using immersion oil (surface microscopy). All pigmented skin lesions were excised and reviewed for histological diagnosis. Photographs of 142 pigmented BCCs, 142 invasive melanomas, and 142 benign pigmented skin lesions were randomly divided into 2 equally sized training and test sets. Images from the training set were scored for 45 surface microscopy features. From this a model was derived and tested on the independent test set.

SETTING

All patients were recruited from the primary case and referral centers of the Sydney Melanoma Unit, Sydney, Australia, and the Skin and Cancer Unit, Skin and Cancer Associates, Plantation, Fla.

PATIENTS

A random sample (selected from a larger database) of patients whose lesions were excised.

MAIN OUTCOME MEASURES

Sensitivity and specificity of the model for diagnosis of pigmented BCCs.

RESULTS

The following model was created. For a pigmented BCC to be diagnosed it must not have the negative feature of a pigment network and must have 1 or more of the following 6 positive features: large gray-blue ovoid nests, multiple gray-blue globules, maple leaflike areas, spoke wheel areas, ulceration, and arborizing "treelike" telangiectasia. On an independent test set the model had a sensitivity of 97% for the diagnosis of pigmented BCCs and a specificity of 93% for the invasive melanoma set and 92% for the benign pigmented skin lesion set.

CONCLUSION

A robust surface microscopy method is described that allows the diagnosis of pigmented BCCs from invasive melanomas and benign pigmented skin lesions. Arch Dermatol. 2000;136:1012-1016

The reliability of diagnostic techniques in the diagnosis and management of malaria in the absence of a gold standard

The accuracy of techniques for the diagnosis of malaria are usually compared with optical microscopy, which is considered to be a gold standard. However, microscopy is prone to error and therefore makes it difficult to assess the reliability of other diagnostic techniques. We did a systematic review to assess the specificity and sensitivity of diagnostic techniques in different settings, using a statistical method that avoided defining a gold standard. Performance varied depending on species of the malaria parasite, level of parasitaemia, and immunity. Overall, histidine-rich protein 2 (HRP2)-based dipsticks showed a high sensitivity (92.7%) and specificity (99.2%) for Plasmodium falciparum in endemic areas. The acridine orange test was more sensitive (97.1%) in detecting P falciparum in epidemiological studies, with a specificity of 97.9%. In the absence of a gold standard, HRP2 dipsticks and acridine orange could provide an alternative for detecting falciparum infections in endemic areas and epidemiological studies, respectively. Microscopy still remains more reliable in detecting non-falciparum infections.

Monolayer stress microscopy: limitations, artifacts, and accuracy of recovered intercellular stresses

In wound healing, tissue growth, and certain cancers, the epithelial or the endothelial monolayer sheet expands. Within the expanding monolayer sheet, migration of the individual cell is strongly guided by physical forces imposed by adjacent cells. This process is called plithotaxis and was discovered using Monolayer Stress Microscopy (MSM). MSM rests upon certain simplifying assumptions, however, concerning boundary conditions, cell material properties and system dimensionality. To assess the validity of these assumptions and to quantify associated errors, here we report new analytical, numerical, and experimental investigations. For several commonly used experimental monolayer systems, the simplifying assumptions used previously lead to errors that are shown to be quite small. Out-of-plane components of displacement and traction fields can be safely neglected, and characteristic features of intercellular stresses that underlie plithotaxis remain largely unaffected. Taken together, these findings validate Monolayer Stress Microscopy within broad but well-defined limits of applicability.

Evaluation of SARS-CoV-2 neutralizing antibodies using a CPE-based colorimetric live virus micro-neutralization assay in human serum samples

The micro-neutralization assay is a fundamental test in virology, immunology, vaccine assessment, and epidemiology studies. Since the SARS-CoV-2 outbreak at the end of December 2019 in China, it has become extremely important to have well-established and validated diagnostic and serological assays for this new emerging virus. Here, we present a micro-neutralization assay with the use of SARS-CoV-2 wild type virus with two different methods of read-out. We evaluated the performance of this assay using human serum samples taken from an Italian seroepidemiological study being performed at the University of Siena, along with the human monoclonal antibody CR3022 and some iper-immune animal serum samples against Influenza and Adenovirus strains. The same panel of human samples have been previously tested in enzyme-linked immunosorbent assay (ELISA) as a pre-screening. Positive, borderline, and negative ELISA samples were evaluated in neutralization assay using two different methods of read-out: subjective (by means of an inverted optical microscope) and objective (by means of a spectrophotometer). Our findings suggest that at least 50% of positive ELISA samples are positive in neutralization as well, and that method is able to quantify different antibody concentrations in a specific manner. Taken together, our results confirm that the colorimetric cytopathic effect-based microneutralization assay could be used as a valid clinical test method for epidemiological and vaccine studies.

Corneal thickness measurements: scanning-slit corneal topography and noncontact specular microscopy versus ultrasonic pachymetry

PURPOSE

To compare central corneal thickness measurements taken with 3 pachymetry systems: Orbscan scanning-slit corneal topography/pachymetry, Topcon SP2000P noncontact specular microscopy, and Tomey ultrasonic pachymetry.

SETTING

Multicenter study, Tokyo, Japan.

METHODS

In 216 healthy eyes of 114 subjects, scanning-slit topography, noncontact specular microscopy, and ultrasonic pachymetry were used in that sequence to record central corneal thickness. In another 20 healthy eyes of 13 subjects, 2 sets of measurements were repeated for each pachymetry to assess repeatability.

RESULTS

The mean central corneal thickness was compatible between scanning-slit topography (546.9 micrometers +/- 35.4 [SD] ) and ultrasonic pachymetry (548.1 +/- 33.0 micrometers); however, noncontact specular microscopy gave a significantly smaller mean (525.3 +/- 31.4 micrometers) than the other 2 tests (P<.001, Tukey multiple comparison). There were significant linear correlations between scanning-slit topography and noncontact specular microscopy (r = 0.846, P<.001), noncontact specular microscopy and ultrasonic pachymetry (r = 0.897, P<.001), and ultrasonic pachymetry and scanning-slit topography (r = 0.852, P<.001). Noncontact specular microscopy tended to show the best repeatability; however, the difference was not statistically significant (P =.663, repeated-measure analysis of variance).

CONCLUSIONS

Corneal thickness readings were comparable between scanning-slit topography and pachymetry; noncontact specular microscopy gave significantly smaller values. The measurements of the 3 methods showed significant linear correlations with one another. All methods provided acceptable repeatability of measurements.

Beyond Rayleigh's criterion: a resolution measure with application to single-molecule microscopy

Rayleigh's criterion is extensively used in optical microscopy for determining the resolution of microscopes. This criterion imposes a resolution limit that has long been held as an impediment for studying nanoscale biological phenomenon through an optical microscope. However, it is well known that Rayleigh's criterion is based on intuitive notions. For example, Rayleigh's criterion is formulated in a deterministic setting that neglects the photon statistics of the acquired data. Hence it does not take into account the number of detected photons, which, in turn, raises concern over the use of Rayleigh's criterion in photon-counting techniques such as single-molecule microscopy. Here, we re-examine the resolution problem by adopting a stochastic framework and present a resolution measure that overcomes the limitations of Rayleigh's criterion. This resolution measure predicts that the resolution of optical microscopes is not limited and that it can be improved by increasing the number of detected photons. Experimental verification of the resolution measure is carried out by imaging single-molecule pairs with different distances of separation. The resolution measure provides a quantitative tool for designing and evaluating single-molecule experiments that probe biomolecular interactions.

Reliability of malaria microscopy in epidemiological studies: results of quality control

To assess the interrater reproducibility of malaria microscopy in epidemiological studies, 711 thick blood films from population-based surveys were randomly selected and reread by 4 experienced microscopists. Sample estimates of the prevalence of P. falciparum infection, geometric mean parasite density and the proportion of samples above various parasite density cut-off levels were almost identical in the routine and quality control readings. Differences were, however, encountered in the sample estimates for gametocyte ratio, proportion of mixed infection and average density index. In all three cases the quality control result was significantly higher than the routine evaluation. On the level of the individual slide there was good interrater agreement for the presence of P. falciparum infections (Kappa index kappa = 0.79) which was even better when parasite densities between 4 and 100/microl were excluded (kappa = 0.94). With respect to the assessment of parasite density, a high level of disagreement was found. While the mean difference between the two readings was not different from 0, the second reading was between 0.12 and 10 times that of the first. However, the level of disagreement significantly fell with increasing parasite densities. Thus malaria microscopy is very reliable for the estimation of parasite ratios and geometric mean parasite densities within and between studies as long as the same methodology is used, but tends to underestimate the gametocyte ratio and proportion of mixed infections. Care must be taken, however, when individual parasite density is related to other explanatory variables, due to the high degree of variability in the parasite enumeration.

Comparison of field and expert laboratory microscopy for active surveillance for asymptomatic Plasmodium falciparum and Plasmodium vivax in western Thailand

Microscopy of Giemsa-stained thick and thin films by a skilled microscopist has remained the standard laboratory method for the diagnosis of malaria. However, diagnosis of malaria with this method is problematic since interpretation of results requires considerable expertise, particularly at low parasite levels. We compared the efficacy of "field" and "expert laboratory" microscopy for active surveillance of Plasmodium falciparum and P. vivax in western Thailand. Field microscopy consisted of an approximately five-minute read (50-100 fields) of a thick film at x700 using a natural light source, whereas expert laboratory microscopy consisted of a 20-minute read (number of parasites per 500 leukocytes) at x1,000 using a high-quality, well-maintained microscope with an artificial light source. All discordant and 20% of concordant results were cross-checked blindly. A total of 3,004 blood films collected between May and November 2000 were included in the study, of which 156 (5.2%) were positive for P. falciparum, 177 (5.9%) for P. vivax, and 4 (0.1%) for both P. falciparum and P. vivax by expert microscopy. A total of 84.4% (135 of 160) of the P. falciparum-positive slides and 93.9% of the P. vivax-positive slides had a parasitemia of less than 500/microL. Field microscopy was specific (99.3%) but not sensitive (10.0%) for the diagnosis of P. falciparum malaria, with a positive predictive value (PPV) of 43.2% and a negative predictive value (NPV) of 95.1%. The corresponding specificity and sensitivity for the diagnosis of P. vivax malaria were 99.2% and 7.1%, respectively, with a PPV of 38.7% and an NPV of 93.9%. Field microscopy, as defined in this study, is not an effective method for active malaria surveillance in western Thailand, where prevalence and parasitemia rates are low.

OME-NGFF: a next-generation file format for expanding bioimaging data-access strategies

The rapid pace of innovation in biological imaging and the diversity of its applications have prevented the establishment of a community-agreed standardized data format. We propose that complementing established open formats such as OME-TIFF and HDF5 with a next-generation file format such as Zarr will satisfy the majority of use cases in bioimaging. Critically, a common metadata format used in all these vessels can deliver truly findable, accessible, interoperable and reusable bioimaging data.

Designing a rigorous microscopy experiment: Validating methods and avoiding bias

Images generated by a microscope are never a perfect representation of the biological specimen. Microscopes and specimen preparation methods are prone to error and can impart images with unintended attributes that might be misconstrued as belonging to the biological specimen. In addition, our brains are wired to quickly interpret what we see, and with an unconscious bias toward that which makes the most sense to us based on our current understanding. Unaddressed errors in microscopy images combined with the bias we bring to visual interpretation of images can lead to false conclusions and irreproducible imaging data. Here we review important aspects of designing a rigorous light microscopy experiment: validation of methods used to prepare samples and of imaging system performance, identification and correction of errors, and strategies for avoiding bias in the acquisition and analysis of images.

Counting mitoses: SI(ze) matters!

Mitoses are often assessed by pathologists to assist the diagnosis of cancer, and to grade malignancy, informing prognosis. Historically, this has been done by expressing the number of mitoses per n high power fields (HPFs), ignoring the fact that microscope fields may differ substantially, even at the same high power (×400) magnification. Despite a requirement to define HPF size in scientific papers, many authors fail to address this issue adequately. The problem is compounded by the switch to digital pathology systems, where ×400 equivalent fields are rectangular and also vary in the area displayed. The potential for error is considerable, and at times this may affect patient care. This is easily solved by the use of standardized international (SI) units. We, therefore, recommend that features such as mitoses are always counted per mm2, with an indication of the area to be counted and the method used (usually "hotspot" or "average") to obtain the results.

Comparison of confocal biomicroscopy and noncontact specular microscopy for evaluation of the corneal endothelium

PURPOSE

To compare the clinical efficacy of confocal biomicroscopy with that of noncontact specular microscopy for the evaluation of the corneal endothelium.

METHODS

The corneal endothelium was examined in 14 normal subjects (28 eyes) and in 6 patients (11 eyes) with Fuchs corneal endothelial dystrophy using a noncontact specular microscope (SP-2000P, Topcon, Japan) and a confocal biomicroscope (ConfoScan, Tomey, Japan). The images and the calculated densities of corneal endothelial cells obtained by the 2 techniques were compared.

RESULTS

For normal subjects, the images of corneal endothelial cells obtained by the 2 techniques were almost identical, although the density of these cells determined by confocal biomicroscopy (2916 +/- 334 cells/mm2) was slightly higher than that determined by noncontact specular microscopy (2765 +/- 323 cells/mm2). In contrast, whereas clear images of corneal endothelial cells, allowing the determination of cell density, were obtained for all 11 eyes of the patient group by confocal biomicroscopy, clear images were obtained for only 4 of these 11 eyes (36.4%) by noncontact specular microscopy.

CONCLUSION

Both noncontact specular microscopy and confocal biomicroscopy revealed the shapes and number of endothelial cells in the normal cornea. However, for corneas with Fuchs dystrophy, clear images were obtained only by confocal biomicroscopy. Confocal biomicroscopy is thus an effective tool for evaluation of the diseased corneal endothelium.

Avoiding a replication crisis in deep-learning-based bioimage analysis

Deep learning algorithms are powerful tools to analyse, restore and transform bioimaging data, increasingly used in life sciences research. These approaches now outperform most other algorithms for a broad range of image analysis tasks. In particular, one of the promises of deep learning is the possibility to provide parameter-free, one-click data analysis achieving expert-level performances in a fraction of the time previously required. However, as with most new and upcoming technologies, the potential for inappropriate use is raising concerns among the biomedical research community. This perspective aims to provide a short overview of key concepts that we believe are important for researchers to consider when using deep learning for their microscopy studies. These comments are based on our own experience gained while optimising various deep learning tools for bioimage analysis and discussions with colleagues from both the developer and user community. In particular, we focus on describing how results obtained using deep learning can be validated and discuss what should, in our views, be considered when choosing a suitable tool. We also suggest what aspects of a deep learning analysis would need to be reported in publications to describe the use of such tools to guarantee that the work can be reproduced. We hope this perspective will foster further discussion between developers, image analysis specialists, users and journal editors to define adequate guidelines and ensure that this transformative technology is used appropriately.

Overdiagnosis and mistreatment of malaria among febrile patients at primary healthcare level in Afghanistan: observational study

OBJECTIVE

To assess the accuracy of malaria diagnosis and treatment at primary level clinics in Afghanistan.

DESIGN

Prospective observational study.

SETTING

22 clinics in two Afghan provinces, one in the north (adjoining Tajikistan) and one in the east (adjoining Pakistan); areas with seasonal transmission of Plasmodium vivax and Plasmodium falciparum.

PARTICIPANTS

2357 patients of all ages enrolled if clinicians suspected malaria.

INTERVENTIONS

Established (>5 years) microscopy (12 clinics in east Afghanistan), newly established microscopy (five clinics in north Afghanistan), and no laboratory (five clinics in north Afghanistan). All clinics used the national malaria treatment guidelines.

MAIN OUTCOME MEASURES

Proportion of patients positive and negative for malaria who received a malaria drug; sensitivity and specificity of clinic based diagnosis; prescriber's response to the result of the clinic slide; and proportion of patients positive and negative for malaria who were prescribed antibiotics. Outcomes were measured against a double read reference blood slide.

RESULTS

In health centres using clinical diagnosis, although 413 of 414 patients were negative by the reference slide, 412 (99%) received a malaria drug and 47 (11%) received an antibiotic. In clinics using new microscopy, 37% (75/202) of patients who were negative by the reference slide received a malaria drug and 60% (103/202) received an antibiotic. In clinics using established microscopy, 50.8% (645/1269) of patients who were negative by the reference slide received a malaria drug and 27.0% (342/1269) received an antibiotic. Among the patients who tested positive for malaria, 94% (443/472) correctly received a malaria drug but only 1 of 6 cases of falciparum malaria was detected and appropriately treated. The specificity of established and new microscopy was 72.9% and 79.9%, respectively. In response to negative clinic slide results, malaria drugs were prescribed to 270/905 (28.8%) and 32/154 (21%) and antibiotics to 347/930 (37.3%) and 99/154 (64%) patients in established and new microscopy arms, respectively. Nurses were less likely to misprescribe than doctors.

CONCLUSIONS

Despite a much lower incidence of malaria in Afghanistan than in Africa, fever was substantially misdiagnosed as malaria in this south Asian setting. Inaccuracy was attributable to false positive laboratory diagnoses of malaria and the clinicians' disregard of negative slide results. Rare but potentially fatal cases of falciparum malaria were not detected, emphasising the potential role of rapid diagnostic tests. Microscopy increased the proportion of patients treated with antibiotics producing a trade-off between overtreatment with malaria drugs and probable overtreatment with antibiotics.

An evaluation of image quality and accuracy of eye bank measurement of donor cornea endothelial cell density in the Specular Microscopy Ancillary Study

PURPOSE

The Specular Microscopy Ancillary Study was designed to examine donor corneal endothelial specular image quality, compare the central endothelial cell density determined by eye banks with the endothelial cell density determined by a central specular microscopy reading center, and evaluate donor factors that may have an impact on specular image quality and endothelial cell density accuracy.

DESIGN

Nonrandomized comparative trial.

PARTICIPANTS

Endothelial specular images of donor corneas assigned in the Cornea Donor Study.

METHODS

Certified readers assessed donor image quality (analyzable from fair to excellent vs. unanalyzable) and determined the central endothelial cell density. Independent adjudication was performed if there was a difference in the quality of grading or if the endothelial cell density varied by > or =5.0% between readers. Average reading center-determined endothelial cell density was compared with the endothelial cell density determined by each eye bank.

MAIN OUTCOME MEASURES

Evaluation of image quality and accuracy of endothelial cell density.

RESULTS

Of 688 donor endothelial images submitted by 23 eye banks, 663 (96%) were analyzable (excellent, 40 [6%]; good, 302 [44%]; fair, 321 [47%]), and 25 (4%) were unanalyzable by reading center standards. In situ retrieval and greater epithelial exposure correlated with a higher image quality grading. The eye bank-determined endothelial cell density of 434 of the 663 (65%) analyzable images were within 10% of the endothelial cell density determined by the reading center, whereas 185 (28%) were more than 10% higher and 44 (7%) were more than 10% lower. Greater variation in endothelial cell density between the eye banks and the reading center was observed with shorter time of death to preservation, presence of an epithelial defect, folds in Descemet's membrane, lower image quality, and the use of fixed-frame or center method endothelial cell density analysis.

CONCLUSIONS

Overall, donor endothelial specular image quality and accuracy of endothelial cell density determination were good. However, the data suggest that factors that may affect image quality and contribute to variation in interpretation of the endothelial cell density should be addressed, because the donor endothelial cell density is an important parameter for assessing long-term corneal graft survival.

Digital imaging in pathology: the case for standardization

The process of digital imaging in microscopy is a series of operations, each contributing to the quality of the final image that is displayed on the computer monitor. The operations include sample preparation and staining by histology, optical image formation by the microscope, digital image sampling by the camera sensor, postprocessing and compression, transmission across the network and display on the monitor. There is an extensive literature about digital imaging and each step of the process is fairly well understood. However, the complete process is very hard to standardize or even to understand fully. The important concepts for pathology imaging standards are: (1) systems should be able to share image files, (2) the standards should allow the transmission of information on baseline colours and recommended display parameters, (3) the images should be useful to the pathologist, not necessarily better or worse than direct examination of a slide under the microscope, (4) a mechanism to evaluate image quality objectively should be present, (5) a mechanism to adjust and correct the minor errors of tissue processing should be developed, (6) a public organization should support pathologists in the development of standards.

Establishing a malaria diagnostics centre of excellence in Kisumu, Kenya

Background

Malaria microscopy, while the gold standard for malaria diagnosis, has limitations. Efficacy estimates in drug and vaccine malaria trials are very sensitive to small errors in microscopy endpoints. This fact led to the establishment of a Malaria Diagnostics Centre of Excellence in Kisumu, Kenya. The primary objective was to ensure valid clinical trial and diagnostic test evaluations. Key secondary objectives were technology transfer to host countries, establishment of partnerships, and training of clinical microscopists.

Case description

A twelve-day "long" and a four-day "short" training course consisting of supervised laboratory practicals, lectures, group discussions, demonstrations, and take home assignments were developed. Well characterized slides were developed and training materials iteratively improved. Objective pre- and post-course evaluations consisted of 30 slides (19 negative, 11 positive) with a density range of 50–660 parasites/μl, a written examination (65 questions), a photographic image examination (30 images of artifacts and species specific characteristics), and a parasite counting examination.

Discussion and Evaluation

To date, 209 microscopists have participated from 11 countries. Seventy-seven experienced microscopists participated in the "long" courses, including 47 research microscopists. Sensitivity improved by a mean of 14% (CI 9–19%) from 77% baseline (CI 73–81 %), while specificity improved by a mean of 17% (CI 11–23%) from 76% (CI 70–82%) baseline. Twenty-three microscopists who had been selected for a four-day refresher course showed continued improvement with a mean final sensitivity of 95% (CI 91–98%) and specificity of 97% (CI 95–100%). Only 9% of those taking the pre-test in the "long" course achieved a 90% sensitivity and 95% specificity, which increased to 61% of those completing the "short" course. All measures of performance improved substantially across each of the five organization types and in each course offered.

Conclusion

The data clearly illustrated that false positive and negative malaria smears are a serious problem, even with research microscopists. Training dramatically improved performance. Quality microscopy can be provided by the Centre of Excellence concept. This concept can be extended to other diagnostics of public health importance, and comprehensive disease control strategies.

Comparison of cytology proficiency testing: glass slides vs. virtual slides

OBJECTIVE

To compare proficiency testing in gynecologic cytology using glass slides vs. virtual slides.

STUDY DESIGN

To compare performance, a sample of 111 individuals (pathologists = 52, cytotechnologists = 59) from participating in-state laboratories were administered 2 proficiency tests. The annual test of the Maryland Cytology Proficiency Testing Program (MCPTP) was administered to individuals in their laboratories following normal work practice (i.e., using microscopes and equipment with which they were familiar). The other test was CytoView II (Centers for Disease Control and Prevention, Atlanta, Georgia, U.S.A.), a computer-based test composed of virtual slides captured from the MCPTP's glass slides, which test administration personnel transported to the individual's laboratory and administered using 1 of 2 laptop computers. ANOVA was used to compare the performance on the 2 tests and the effect of various potential confounding variables. The slides were evaluated by comparing the performance average for each glass slide to that of the matching virtual slides. All data analysis was performed at the 95% confidence interval.

RESULTS

The mean score of the individuals (n = 111) on the MCPTP test was 99.2% (SD = 2.2, range = 90-100%). The mean score of the individuals (n = 111) on CytoView II was 96.8% (SD = 5.8, range = 70-100%). No individual scored < 90% on the glass slide test (pass rate = 100%). Eight individuals (pathologists = 3, cytotechnologists = 5) scored < 90% on the CytoView II (pass rate = 93.8%). Comparison of an individual's performance on the 2 tests demonstrated a significant difference. When virtual slides that did not attain a 90% consensus were excluded from the scoring, a comparison of individual pass rate for the glass slide test (100%) and computer-based test (99.1%) did not demonstrate significant difference.

CONCLUSION

Each slide (glass or virtual) must be field validated by cytotechnologists and pathologists. If field validation and Clinical Laboratory Improvement Amendment referencing of virtual slides are comparable to those of glass slides, computer-based testing can be equivalent.

Dark ground microscopy and treponemal serological tests in the diagnosis of early syphilis

OBJECTIVES

To evaluate the use of dark ground microscopy (DGM) and treponemal serological tests in the diagnosis of primary (PS) and secondary (SS) syphilis.

METHODS

A retrospective case note review of patients with early syphilis who attended our department between January 2001 and December 2002. Data were collected on demographics, results of treponemal serology and DGM.

RESULTS

50 individuals had PS and 36 individuals had SS. DGM was performed in 31/50 (62%) of PS cases and this was positive in 97%. In 17 (34%) cases of PS, treponemal EIA was negative initially. DGM was performed on 13 of these, all of which were positive. Therefore, EIA had a sensitivity of 57% when compared to DGM. In 27 patients where EIA-IgM was performed, this was positive in 22 (81%), of which 12 were EIA negative on initial screening. All SS cases had positive EIA. DGM was performed in 19/36 (52%) of SS cases and was positive in 16/19--that is, a sensitivity of 84% when compared to EIA. The major reason why DGM was not performed in the cases of PS was that herpes was the presumed diagnosis and in SS the rash was attributed to other causes.

CONCLUSIONS

DGM is a rapid and sensitive test while EIA takes time for results and is less sensitive in PS. EIA-IgM is a useful adjunct in PS. DGM allows immediate diagnosis, treatment, and partner notification preventing further transmission. Genitourinary medicine clinics should have trained staff to perform DGM on all anogenital ulcers and suspected syphilitic lesions.

A randomized controlled trial of the diagnostic accuracy of internet-based telepathology compared with conventional microscopy

AIMS

To compare the diagnostic accuracy of internet-based virtual microscopy with conventional light microscopy, in the context of renal biopsies assessed by participants in the UK National Renal Pathology External Quality Assessment (EQA) Scheme.

METHODS AND RESULTS

'Virtual slides' of current EQA cases were made available over the internet to participants in the scheme. The approach permitted what may reasonably be described as a randomized controlled trial of the diagnostic accuracy of this mode of telepathology, in the context of renal pathology. No significant difference in diagnostic accuracy could be detected between the diagnoses proffered on the basis of virtual slides and conventional slides; but using virtual slides took pathologists considerably longer.

CONCLUSIONS

This result provides some encouragement for the implementation of such virtual slide-based telepathology systems. However, in failing to detect a difference, equivalence of diagnostic accuracy has not been proved; nor has the relevance of this result to other fields of histopathology been demonstrated. A decision to implement a diagnostic telepathology system requires consideration of numerous factors beyond diagnostic accuracy, including financial, legal, professional and ethical issues.