Performance Of Diagnostic Methods Research Articles

Leishmaniasis in Norway.

Leishmaniasis is a rare but potentially severe tropical infectious disease, and Norwegian clinicians are generally unfamiliar with its diagnosis and treatment. This study aimed to investigate the number of cases diagnosed, performance of diagnostic methods and treatment of leishmaniasis at five university hospitals in Norway. The number of cases, diagnosis and treatment of suspected leishmaniasis were registered prospectively in the period March 2014 - September 2017 at the university hospitals of Bergen, Oslo, Stavanger, Trondheim and Tromsø. A total of 13patients with leishmaniasis were registered in the period. Visceral leishmaniasis was diagnosed in two patients infected in the Mediterranean region, after 7 and 8 weeks with symptoms. The diagnosis was made by serology as well as microscopy and/or polymerase chain reaction tests (PCR) on spleen, blood and bone marrow. Both patients were treated effectively with liposomal amphotericin B. Cutaneous leishmaniasis was diagnosed in 11patients, and samples from 10 of these tested positive with PCR. Two patients were infected with potentially mucotropic species. Liposomal amphotericin B was the first-line choice for all those who received treatment, but one patient recovered only after local therapy with sodium stibogluconate. Assessment of visceral leishmaniasis was undertaken according to international guidelines. The patients were diagnosed late in the disease course, presumably because the disease is rare and not well known in Norway. Cutaneous leishmaniasis was diagnosed with PCR, but none of the patients received local treatment as the first-line choice, as recommended in suitable cases, presumably because the drugs are not readily available in Norway and many clinicians are unfamiliar with the route of administration with local infiltration.

Real time strain elastography for differentiation of solid renal masses

Objective: The aim of this study was to investigate the diagnostic performance of real time strain elastography for evaluation of solid renal masses. Material and methods: Forty two patients who were incidentally detected solid renal masses underwent Real Time Strain Elastography. Strain index value was detected for each lesion by dividing ROI of lesion to ROI of adjacent renal cortex. Strain index values and color encoding patterns of lesions and renal parenchyma were obtained. Mean strain index values and color encoding patterns for benign and malignant lesions were compared. Also by using ROC curve, cut-off value was obtained and diagnostic performance of method was evaluated. Results: Any statistically significant difference of mean ages of patients was not found. Mean strain index value of malignant lesions were significantly higher than benign lesions. When cut-off value for strain index ratio was taken 0.3, high diagnostic performance was obtained for differentiation of solid renal masses as benign or malignant. Conclusion: Real time strain elastography can be useful for differentiation of solid renal masses as malignant or benign.

Impact of ribotype on Clostridioides difficile diagnostics

This study investigates the performance of diagnostic methods for detection of Clostridioides difficile infection in Sweden, including impact of PCR ribotype on diagnostic performance. Between 2011 and 2016, a total of 17,878 stool samples from 26 laboratories were tested by either well-type enzyme immunoassays (EIAs), membrane bound EIAs, cell cytotoxicity neutralization assay (CTA), or nucleic acid amplification tests (NAATs) and subsequently cultured for C. difficile. Roughly half of the samples (9454/17878) were subjected to diagnostic testing both on the fecal sample and on the 1323 isolated C. difficile strains. All C. difficile isolates were typed by PCR ribotyping, and the isolates were classified as toxigenic or non-toxigenic based on the empirical knowledge of the association between toxin-positivity and ribotype. The overall sensitivity, specificity, and positive and negative predictive values were highest for NAATs and membrane EIAs. Ribotype-specific sensitivity varied greatly between methods and ribotypes. All methods had 100% sensitivity against ribotype 027 and 013. For other types, the sensitivity ranged from 33 to 85% in fecal samples and from 78 to 100% on isolates. For the most prevalent ribotypes (014, 020, and 001), the sensitivity varied between 38 and 100% in the fecal samples, with the lowest sensitivity observed for well-type EIAs and CTA. The large variation in diagnostic sensitivity implies that type distribution significantly affects the outcome when evaluating diagnostic performance. Furthermore, performing comparative studies of diagnostic tests in settings with high prevalence of ribotype 027 will overestimate the general performance of diagnostic tests.

Evaluation of Aircraft Engine Gas Path Diagnostic Methods Through ProDiMES

Propulsion diagnostic method evaluation strategy (ProDiMES) offers an aircraft engine diagnostic benchmark problem where the performance of candidate diagnostic methods is evaluated while a fair comparison can be established. In the present paper, the performance evaluation of a number of gas turbine diagnostic methods using the ProDiMES software is presented. All diagnostic methods presented here were developed at the Laboratory of Thermal Turbomachinery of the National Technical University of Athens (LTT/NTUA). Component, sensor, and actuator fault scenarios that occur in a fleet of deteriorated twin-spool turbofan engines are considered. The performance of each diagnostic method is presented through the evaluation metrics introduced in the ProDiMES software. Remarks about each methods performance as well as the detectability and classification rates of each fault scenario are made.

Performance of Different Methods for Detection of Incipient Occlusal Caries Lesions: An In Vitro Study.

The aim of this in vitro study was to evaluate the diagnostic performance of visual inspection (VI), laser fluorescence (LF pen), fluorescence camera (FC), and alternating current impedance spectroscopy technique (ACIST) for detection of incipient occlusal caries lesions. Histology was used as the gold standard to determine the interexaminer reliability of the methods, among three examiners with different levels of experiences (Examiner 1: 5 years; examiner 2: 10 years; and examiner 3: 25 years). One hundred two molar teeth were selected. The occlusal surfaces of teeth were evaluated with VI, LF pen, FC, and ACIST devices independently by three examiners. Diagnostic performances of methods were evaluated with binormal receiver-operating characteristics analysis. Interexaminer agreement of detection methods was assessed using Cohen's kappa coefficient values (p < 0.001). Incipient enamel lesions were determined more successfully with VI by all examiners. All detection methods were presented with statistically acceptable interexaminer agreement (p < 0.001). For D2 and D3 thresholds, FC for examiner 1, VI for examiner 2, and both VI and FC for examiner 3 demonstrated statistically high sensitivity and specificity (p < 0.05). It can be concluded that diagnostic performance of the methods was insufficient for detecting incipient occlusal caries lesions by itself. Performance can be improved by using them with VI as a traditional caries detection method.

Improving the detection of anthelmintic resistance: Evaluation of faecal egg count reduction test procedures suitable for farm routines

The faecal egg count reduction test (FECRT) is the main method of detection of anthelmintic resistance (AR) in nematodes of veterinary importance. However, although the FECRT is standardised, the diagnostic performance of this method has not been fully characterised. In this survey Monte Carlo routines were used to simulate the estimation of faecal egg count reduction (FECR) with several FECRT protocols that were performed under different field and laboratory conditions. The goal was to determine, from a practical viewpoint, the most suitable protocols for farm routines and to evaluate the diagnostic performance of FECRTs across different parasitological scenarios with several levels of AR. The simulated field procedures included variations in the sample size and the sampling (or not) of a control group, whereas the simulated laboratory procedures comprised group mean individual-based vs. composite-based FECR estimations and variations in the egg detection threshold of the McMaster technique. For composite procedures, the random weight variations among individual samples and an increased number of McMaster chamber counts were also simulated. The results showed that FECRTs were moderately affected by inaccuracy but crucially affected by imprecision, and both parameters were clearly dependent on the parasitological conditions and the laboratory and field procedures used. An individual-based FECRT method performed without a control group was the most appropriate to quantify the AR, whereas a composite-based method with a control group was the easiest method for discriminating susceptible and resistant parasite populations. More interestingly, the diagnostic performance of the simulated FECRT methods was low for the procedures that are currently recommended by the World Association for the Advancement of Veterinary Parasitology (W.A.A.V.P.) and for many of the typical field and laboratory procedures that are currently implemented. Therefore, the results suggest that the diagnostic performance of the FECRT should be re-evaluated, and the recommendations of the W.A.A.V.P. should be redefined. Finally, theoretic critical conditions for FECRT procedures have been defined to improve future AR surveys and to allow the interpretation of FECRT results with the necessary caution according to the diagnostic performance expected for every FECRT procedure and parasitological scenario.