Robust automated reading of the skin prick test via 3D imaging and parametric surface fitting

The conventional reading of the skin prick test (SPT) for diagnosing allergies is prone to inter- and intra-observer variations. Drawing the contours of the skin wheals from the SPT and scanning them for computer processing is cumbersome. However, 3D scanning technology promises the best results in terms of accuracy, fast acquisition, and processing. In this work, we present a wide-field 3D imaging system for the 3D reconstruction of the SPT, and we propose an automated method for the measurement of the skin wheals. The automated measurement is based on pyramidal decomposition and parametric 3D surface fitting for estimating the sizes of the wheals directly. We proposed two parametric models for the diameter estimation. Model 1 is based on an inverted Elliptical Paraboloid function, and model 2 on a super-Gaussian function. The accuracy of the 3D imaging system was evaluated with validation objects obtaining transversal and depth accuracies within ± 0.1 mm and ± 0.01 mm, respectively. We tested the method on 80 SPTs conducted in volunteer subjects, which resulted in 61 detected wheals. We analyzed the accuracy of the models against manual reference measurements from a physician and obtained that the parametric model 2 on average yields diameters closer to the reference measurements (model 1: -0.398 mm vs. model 2: -0.339 mm) with narrower 95% limits of agreement (model 1: [-1.58, 0.78] mm vs. model 2: [-1.39, 0.71] mm) in a Bland-Altman analysis. In one subject, we tested the reproducibility of the method by registering the forearm under five different poses obtaining a maximum coefficient of variation of 5.24% in the estimated wheal diameters. The proposed method delivers accurate and reproducible measurements of the SPT. © 2019 Pineda et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Departamento Administrativo de Ciencia, Tecnología e Innovación (COLCIENCIAS), COLCIENCIAS: 538871552485 C2018P018, C2018P005This study was supported by Colciencias (www.colciencias.gov.co, Grant 538871552485) and by Universidad Tecnol?gica de Bolivar (www.utb.edu.co, Grants C2018P005 and C2018P018), Colombia

Reliability of a novel electro-medical device for wheal size measurement in allergy skin testing: An exploratory clinical trial

Skin prick testing (SPT) is the cornerstone of IgE-mediated allergy diagnosis,1 due to its high sensitivity and specificity.2 However, a uniform method for wheal measurement does not exist. Ansotegui et al.2 recommends to measure wheals in millimeters with a ruler, in many centers they are outlined with a pen and transfer by tape to a paper and then measured. Subsequently, the specialist is able to manually measure the maximum (MD) and orthogonal diameter (OD) of the wheal. This procedure is time consuming and makes repro-ducible measurements difficult.2,3 Knowing the wheal's area could help make a more accurate diagnosis.4 Over the last 30 years, many attempts have been made to develop a device to measure the size of SPT.3 Nexkin DSPT® (Figure S1A,B) is a novel mechatronic system based on 3D laser technology, that automatically locates allergen's wheal and measures its size (MD, OD and area in square millimeters) (Figure S1C)

Skin prick test wheal detection in 3D images via convolutional neural networks

The skin prick test (SPT) is performed to diagnose different types of allergies. This medical procedure requires measuring the size of the skin wheals that appear when the test is performed. However, the manual measurement method is cumbersome and suffers from intraand inter-observer errors. Thus, multiple approaches have been developed to improve the reproducibility of the test. This work aims to improve part of the automated reading of the SPT to improve the reliability of the wheal detection procedure through the use of convolutional neural networks (CNN). Our proposal starts from the 3D images of the SPT from the arm of patients. They are processed for global surface removal, and then a CNN is trained to produce an output mask that detects the wheals. Finally, the contour of each wheal and its largest diameter is obtained. Encouraging results with mean difference 0.966 mm and mean coefficient of variation 7.29% show that the proposed method provides reliable automated skin wheal detection

IgE allergy diagnostics and other relevant tests in allergy, a World Allergy Organization position paper

Currently, testing for immunoglobulin E (IgE) sensitization is the cornerstone of diagnostic evaluation in suspected allergic conditions. This review provides a thorough and updated critical appraisal of the most frequently used diagnostic tests, both in vivo and in vitro. It discusses skin tests, challenges, and serological and cellular in vitro tests, and provides an overview of indications, advantages and disadvantages of each in conditions such as respiratory, food, venom, drug, and occupational allergy. Skin prick testing remains the first line approach in most instances; the added value of serum specific IgE to whole allergen extracts or components, as well as the role of basophil activation tests, is evaluated. Unproven, non-validated, diagnostic tests are also discussed. Throughout the review, the reader must bear in mind the relevance of differentiating between sensitization and allergy; the latter entails not only allergic sensitization, but also clinically relevant symptoms triggered by the culprit allergen

Use of electronic medical records and biomarkers to manage risk and resource efficiencies

Peer reviewedPublisher PD

Validation of a food frequency questionnaire for children and adolescents aged 4 to 11 years living in Salvador, Bahia.

OBJECTIVE: To assess the validity of a food frequency questionnaire (FFQ) by applying it to children and adolescents living in Salvador, Bahia. METHODS: The validity of this FFQ with 98 food items was investigated among 108 children and adolescents who were selected from a sample of 1445 that had been planned for a study on the risk factors for asthma and other allergic diseases. The adults responsible for these children and adolescents gave responses for a 24-hour recall (R24h) and an FFQ. The average energy and nutrient values from the FFQ were compared with those from the R24h by means of the paired t test and Pearson correlation coefficients. The concordance was evaluated using the Bland-Altman method and kappa statistics. RESULTS: The energy and nutrient intake estimated using the FFQ was significantly higher than what was obtained using the R24h. The correlation coefficients adjusted for energy were statistically significant for protein, fat, vitamin C and zinc. The weighted kappa values ranged from 0.06 for vitamin A (p = 0.24) to 0.34 for energy (p < 0.00). The results from the Bland-Altman plots for lipid, protein and zinc showed the most significant validity parameters, and zinc was found to show the best concordance. CONCLUSION: The results suggest that the FFQ showed satisfactory validity for use in studies involving children and adolescents

Exploring the waveform characteristics of tidal breathing carbon dioxide, measured using the N-Tidal C device in different breathing conditions (The General Breathing Record Study): protocol for an observational, longitudinal study

Background: In an increasingly comorbid population, there are significant challenges to diagnosing the cause of breathlessness, and once diagnosed, considerable difficulty in detecting deterioration early enough to provide effective intervention. The burden of the breathless patient on the health care economy is substantial, with asthma, chronic heart failure, and pneumonia affecting over 6 million people in the United Kingdom alone. Furthermore, these patients often have more than one contributory factor to their breathlessness symptoms, with conditions such as dysfunctional breathing pattern disorders—an under-recognized component. Current methods of diagnosing and monitoring breathless conditions can be extensive and difficult to perform. As a consequence, home monitoring is poorly complied with. In contrast, capnography (the measurement of tidal breath carbon dioxide) is performed during normal breathing. There is a need for a simple, easy-to-use, personal device that can aid in the diagnosis and monitoring of respiratory and cardiac causes of breathlessness.Objective: The aim of this study was to explore the use of a new, handheld capnometer (called the N-Tidal C) in different conditions that cause breathlessness. We will study whether the tidal breath carbon dioxide (TBCO2) waveform, as measured by the N-Tidal C, has different characteristics in a range of respiratory and cardiac conditions.Methods: We will perform a longitudinal, observational study of the TBCO2 waveform (capnogram) as measured by the N-Tidal C capnometer. Participants with a confirmed diagnosis of asthma, breathing pattern disorders, chronic heart failure, motor neurone disease, pneumonia, as well as volunteers with no history of lung disease will be asked to provide twice daily, 75-second TBCO2 collection via the N-Tidal C device for 6 months duration. The collated capnograms will be correlated with the underlying diagnosis and disease state (stable or exacerbation) to determine if there are different TBCO2 characteristics that can distinguish different respiratory and cardiac causes of breathlessness.Results: This study’s recruitment is ongoing. It is anticipated that the results will be available in late 2018.Conclusions: The General Breathing Record Study will provide an evaluation of the use of capnography as a diagnostic and home-monitoring tool for various diseases

Validation of a quantitative lateral flow immunoassay (LFIA)-based point-of-care (POC) rapid test for SARS-CoV-2 neutralizing antibodies

With the widespread use of coronavirus disease 2019 (COVID-19) vaccines, a rapid and reliable method to detect SARS-CoV-2 neutralizing antibodies (NAbs) is extremely important for monitoring vaccine effectiveness and immunity in the population. The purpose of this study was to evaluate the performance of the RapiRead (TM) reader and the TestNOW (TM) COVID-19 NAb rapid point-of-care (POC) test for quantitative measurement of antibodies against the spike protein receptor-binding domain of severe respiratory syndrome coronavirus 2 (SARS-CoV-2) in different biological matrices compared to chemiluminescence immunoassay (CLIA) methods. Ninety-four samples were collected and analyzed using a RapiRead (TM) reader and TestNOW (TM) COVID-19 NAb kits for detecting neutralizing antibodies, and then using two CLIAs. The data were compared statistically using the Kruskal-Wallis test for more than two groups or the Mann-Whitney test for two groups. Specificity and sensitivity were evaluated using a receiver operating characteristic (ROC) curve. Good correlation was observed between the rapid lateral flow immunoassay (LFIA) test system and both CLIA methods. RapiRead (TM) reader/TestNOW (TM) COVID-19 NAb vs. Maglumi: correlation coefficient (r) = 0.728 for all patients; r = 0.841 for vaccinated patients. RapiRead (TM) reader/TestNOW (TM) COVID-19 NAb vs. Mindray: r = 0.6394 in all patients; r = 0.8724 in vaccinated patients. The time stability of the POC serological test was also assessed considering two times of reading, 12 and 14 minutes. The data revealed no significant differences. The use of a RapiRead (TM) reader and TestNOW (TM) COVID-19 NAb assay is a quantitative, rapid, and valid method for detecting SARS-CoV-2 neutralizing antibodies and could be a useful tool for screening studies of SARS-CoV-2 infection and assessing the efficacy of vaccines in a non-laboratory context

Non-invasive technology to determine the haemoglobin level of blood donors at the SANBS

Background: Predonation haemoglobin (Hb) check has been done traditionally by the copper sulphate (CuSO4), or the haemocue haemoglobinometer methods. Both of these require a fingerprick of the donor to obtain capillary blood samples. It is thought that a non-invasive, but accurate method of Hb check will reduce stress to the donor and improve the donation experience.Aim: This study aims to establish the suitability of a non-invasive method, the HaemospectR transcutaneous Hb measurement system for screening prospective donors at the cut-off Hb value of 12.5g/dl.Materials and methods: All donors who presented for platelet and/or plasma donation at the multi-disciplinary donor centre of SANBS in Port Elizabeth were considered for enrolment. Hb was measured by both the standard automated method on venous EDTA samples, and by the HaemospectR transcutaneous Hb measuring device.Results: A total of 161 subjects were studied, including white, black, and coloured, male and female donors. The calculated sensitivity of the HaemospectR was 94.6%. The average percentage variance in Hb measurement between the two methods was 1.2%, while 70.8% of subjects had a percentage variance within10% of the venous Hb result.Discussion and conclusion: The result shows that the accuracy of the HaemospectR measurement was within the 1.5g/dl ascribed to the CuSO4 method. This suggests that the non-invasive method was at least as sensitive as the traditional screening methods. Further large-scale study is recommended to validate the findings in this pilot study.Keywords: Donor screening, haemoglobin, non-invasive, capillary sample; copper sulphat