Risco de resultado falso positivo no rastreamento mamográfico do Brasil / Risk of false-positive result in mammography screening in Brazil / Riesgo de resultados falsos positivos en el cribado mamográfico en Brasil

Resultados falsos positivos na mamografia de rastreamento são comuns a essa intervenção e trazem ônus para as mulheres e o sistema de saúde. O objetivo deste estudo foi estimar o risco de resultado falso positivo no rastreamento mamográfico brasileiro com base em dados de sistemas de informação do Sistema Único de Saúde (SUS). Foi realizado estudo de coorte histórica de mulheres de 40-69 anos, que realizaram mamografia de rastreamento e exame histopatológico de mama no SUS, nos anos de 2017 a 2019. A taxa de resultados falsos positivos foi estimada a partir da prevalência de resultados BI-RADS alterados na mamografia de rastreamento e da proporção de resultados benignos no exame histopatológico de mama. Das 10.671 mulheres com exame histopatológico no SUS, 46,2% apresentaram resultado benigno, sendo essa proporção significativamente maior em mulheres de 40-49 anos comparada à de mulheres de 50-69 anos. A estimativa de resultados falsos positivos foi de 8,18 casos por 100 mulheres na faixa etária de 40-49 anos, e de 6,06 por 100 mulheres na faixa de 50-69 anos. Essas informações são úteis aos gestores na avaliação de programas de rastreamento do câncer de mama, assim como aos profissionais de saúde, para que orientem a mulher sobre as implicações do rastreamento mamográfico.

False-positive results on mammography screening are common, putting a burden on both women and the health care system. This study aimed to estimate the risk of false-positive results in Brazilian mammography screening based on data from the Brazilian Unified National Health System (SUS) information systems. A retrospective cohort study was conducted with women aged 40-69 years, who underwent mammography screening and breast histopathological examination at SUS from 2017 to 2019. The rate of false-positive results was estimated based on the prevalence of altered BI-RADS results on mammography screening and the proportion of benign results on breast histopathological examination. Of the 10,671 women with histopathological examination at SUS, 46.2% had a benign result, and this proportion was significantly higher in women aged 40-49 years compared to women aged 50-69 years. The estimate of false-positive results was 8.18 cases per 100 women aged 40-49 years and 6.06 per 100 women aged 50-69 years. This information is useful for public managers in evaluating mammography screening programs, as well as for health care providers to guide women on the implications of mammography screening.

Los resultados falsos positivos en la mamografía de cribado son comunes en esta intervención y suponen prejuicios para las mujeres y el sistema de salud. El objetivo de este estudio fue estimar el riesgo de resultados falsos positivos en el cribado mamográfico brasileño a partir de los datos del sistema de información del Sistema Único de Salud (SUS). Se realizó un estudio de cohorte histórica de mujeres de 40-69 años, que se sometieron a mamografía de cribado y examen histopatológico de mama en el SUS, de 2017 a 2019. La tasa de resultados falsos positivos se estimó a partir de la prevalencia de resultados de BI-RADS alterados en la mamografía de cribado y la proporción de resultados benignos en el examen histopatológico de mama. De las 10.671 mujeres que se sometieron a examen histopatológico en el SUS, el 46,2% tuvo un resultado benigno, siendo esta proporción significativamente mayor en mujeres de 40-49 años en comparación con las mujeres de 50-69 años. La estimación de resultados falsos positivos fue de 8,18 casos por 100 mujeres en el grupo de edad de 40-49 años y 6,06 por 100 mujeres en el grupo de 50-69 años. Esta información es útil para los gestores en la evaluación de los programas de cribado de cáncer de mama, así como para los profesionales sanitarios en orientar a las mujeres sobre las implicaciones del cribado mamográfico.

Application value of modified magnetic bead screening for enrichment of cell-free fetal DNA from maternal peripheral blood in non-invasive prenatal testing / 中华围产医学杂志

Objective:To evaluate the value of modified magnetic bead screening for enrichment of cell-free fetal DNA (cffDNA) in non-invasive prenatal testing (NIPT).Methods:This study retrospectively recruited 31 cases with low concentration of cffDNA (<6.00%), Z value in the gray zone (3.00-4.00) at the first detection, or false-positive (confirmed by invasive prenatal diagnosis) or false-negative (confirmed by postnatal chromosome test) results among 11 000 pregnant women who underwent routine NIPT in Beijing Haidian District Maternal and Child Health Care Hospital from October 2017 to December 2019. Plasma samples collected for the first-time routine NIPT were used to enrich cffDNA using modified magnetic beads for NIPT (modified NIPT). Wilcoxon rank sum test was used to compare the modified NIPT with the routine NIPT in detecting the cffDNA concentrations of male fetuses.Results:Among the 31 pregnant women, there were 13 cases with low cffDNA concentration in routine NIPT, 11 having false-positive results in the routine NIPT (three for trisomy 13, four for trisomy 18 and four for trisomy 21, all were confirmed by invasive prenatal diagnosis), six with gray-zone Z values in the first-time NIPT (retesting indicating low risk) and one having false negative result for trisomy 21 (confirmed by postnatal chromosome test). Cell-free DNA (cfDNA) fragments less than 150 bp were effectively enriched using the modified magnetic bead screening and the concentration of cffDNA was increased from 4.43% (2.45%-17.61%) in routine NIPT to 13.46% (7.75%-36.64%) in the modified NIPT ( Z=-14.22, P<0.01). Results of the modified NIPT indicated that 13 cases with low cffDNA concentration of routine NIPT were successfully detected as low risk, as well as the risks in the six cases with gray-zone Z value and six of the 11 false-positive cases in the routine NIPT were low, which were consistent with the retest results of the routine NIPT, while high risk was found in one false-negative case. Conclusions:The modified NIPT could reduce the false positive rate by lowering the failure rate caused by low concentration of cffDNA and is able to identify false-negative cases. Compared with the routine NIPT, it shows a higher success rate and a lower false positive rate.

Clinical value of noninvasive prenatal testing in vanishing twin pregnancies / 中华围产医学杂志

Objective:To analyze the clinical value of noninvasive prenatal testing (NIPT) in vanishing twin (VT) pregnancies.Methods:A total of 164 VT pregnancies that underwent NIPT in Peking University Third Hospital from January 2017 to December 2020 were enrolled. Gestational age at onset of vanishing, results of NIPT and invasive prenatal diagnosis, blood sampling time points, and pregnancy outcomes were retrospectively analyzed using two independent samples t test and Chi-square test. Results:(1) Of the 164 cases, six had positive results for NIPT, but negative results for karyotype analysis or single nucleotide polymorphism genotyping, with a false positive rate of 3.7% (6/164) for NIPT and all of them were delivered at term. Four pregnancies terminated in the second trimester, including two fetal malformation cases and one unexplained intrauterine death whose single nucleotide polymorphisms results are all normal and one inevitable abortion case due to premature rupture of membrane who refused amniocentesis. The other 154 women all gave birth to normal phenotype babies including 12 preterm ones. (2) The false-positive rate of NIPT was lower in VT pregnancies diagnosed at less than eight gestational weeks than those diagnosed after [1.5% (2/134) vs 13.3% (4/30), χ2=6.68, P=0.010]. The false-positive rate was 6.9% (4/58) in women diagnosed at or below eight weeks between the occurrence of VT and blood sampling and was 1.9% (2/106) in those with interval more than eight weeks, but without significant difference ( χ2=1.44, P=0.231). Conclusions:Although VT pregnancies exist false-positive results in NIPT, screening is still recommended based on fully informed consent to reduce unnecessary invasive prenatal diagnosis. The earlier the onset of VT, the lower the NIPT false positive rate, but whether extending the sampling interval would reduce the risk of false-positive needs further study.

Dificultades en la detección de genomas del nuevo coronavirus 2 (SARS CoV-2) / Pandemic and social inequiality: the popular neighborhoods of the Buenos Aires suburbs in preventive social isolation

RESUMEN El manejo de las infecciones virales respiratorias, tanto a nivel nacional como a nivel mundial, requiere resultados científicos de calidad. La reacción en cadena de la polimerasa de transcriptasa inversa (rRT-PCR, por su sigla en inglés) es considerada el "patrón de oro" para detectar el genoma del nuevo coronavirus 2 (SARS-CoV-2), agente causal de la enfermedad por el nuevo coronavirus (COVID-19) sobre todo en la fase aguda de la infección. Su uso es controvertido fuera de un contexto de exposición viral. El objetivo del presente trabajo es analizar escollos encontrados durante la detección del genoma del SARS-CoV-2 que pueden producir resultados falsos. Los falsos negativos de rRT-PCR pueden deberse al momento y la eficacia de la toma de la muestra, la congelación, el almacenamiento y la descongelación, y a la inactivación térmica de la virulencia. Además, las señales retardadas de los controles internos invalidan la negatividad. Por otra parte, las muestras con escaso material biológico llevan a conclusiones negativas falsas, por lo que determinar un umbral (número mínimo de células epiteliales) contribuirá a reducirlas. Sin embargo, la mayoría de los kits detectan ADN humano, pero no fueron calibrados para cuantificar carga celular. Los ácidos ribonucleicos nucleares (ARN) virales adheridos a guantes, tubos y gorros, -entre otros elementos-, son fuente de falsos positivos. Las farmacopeas sugieren que la contaminación externa se controle en series de 100 muestras con al menos una representatividad del 10%. Si se extrapola esta aproximación al laboratorio de análisis clínicos, en lugar de uno se deberían procesar al menos 10 controles negativos contiguos a 10 positivos cada 100 pruebas. Mejorar la detección por rRT-PCR implica un aumento de al menos 20% en el costo de los reactivos, por lo que se necesitan recursos adicionales.

ABSTRACT Emerging respiratory viral infections like the severe coronavirus disease (CoVID 19) caused by novel coronavirus 2 (SARS-CoV-2) require quality results for science-based responses. The reverse transcriptase polymerase chain reaction (rRT-PCR) is considered the gold standard for detecting SARS-CoV-2 (particularly in the acute phase of infection). The aim of the present work was to analyze pitfalls during the search of viral genomes. False negative conclusions are result of sampling timing, performances of swabbing, storage, and thawing and heat-infectivity inactivation. Samples with low biologic material also lead to false negatives. Qualitative controls to detect the presence of human DNA are available in several kits but they were not calibrated for quantification of human cell loads. Moreover, negativity cannot be reported for samples with delayed signals for the internal control (due to deficiency in extraction and/or retro transcription and/or or to the presence of rRT-PCR inhibitors). The viral RNA that may have stick on gloves, on tubes, caps, etc. may produce false positives. The International Pharmacopoeias recommend for external contamination to test at least 10% of the samples. Couples of 10 negative contiguous to 10 positive controls randomly distributed should be therefore included in each series of 100 rRT-PCR tests. These improvements increase the cost of each determination (at least by 20% only for the reactants) and require additional resources.

Performance of urea-mediated dissociation in reducing false-positive of 2019-nCoV IgM test / 中华检验医学杂志

Objective@#To investigate the interference factors causing false-positive result of novel coronavirus IgM antibody (SARS-CoV-2 IgM) detected by gold immunochromatography assay (GICA) and enzyme-linked immunosorbent assay (ELISA).@*Methods@#A total of 71 serum from different pathogen infections and related chronic diseases patients were collected from the Affiliated Hospital of North Sichuan Medical College from January 25, 2020 to February 15, 2020. GICA and ELISA were used to detect 2019-nCoV IgM in 71 serum, including 5 influenza A virus (Flu A) IgM positive serum, 5 influenza B virus (Flu B) IgM positive serum, 5 Mycoplasma pneumonia (MP) IgM positive serum, 5 Legionella pneumophila (LP) IgM positive serum, 29 rheumatoid factor (RF) IgM positive serum, 5 hypertension patients serum, 5 diabetes mellitus patients serum, 6 human immunodeficiency virus (HIV) infection patients serum and 6 Corona Virus Disease 2019 (COVID-19) patients serum. The interference factors causing false positive results of the two methods were analyzed, and urea dissociation test was employed to dissociate the 2019-nCoV IgM positive serum using the best dissociation concentration. Statistical analyses were performed by SPSS, version 19.0.@*Result@#s 2019-nCoV IgM was positive in 18 cases of middle-high level RF-IgM positive serum and 6 cases of 2019-nCoV-infected serum detected by two methods, and the other 47 serum were negative. When the dissociation concentration of urea was 6 mol/L, 2019-nCoV IgM was negative in 17 cases of middle-high level RF-IgM positive serum and positive in 6 cases of 2019-nCoV-infected serum detected by GICA. When the urea dissociation concentration was 4 mol/L, dissociation time was 10 min and the avidity index<0.46 was set as negative, 2019-nCoV IgM was negative in 15 cases of middle-high level RF-IgM positive serum and positive in 6 cases of 2019-nCoV-infected serum detected by ELISA.@*Conclusion@#The middle-high level of RF-IgM could cause false positive results of SARS-CoV-2 IgM detected by GICA and ELISA, and the urea dissociation test would be helpful for reducing the probability of false-positive results of SARS-CoV-2 IgM test.

Reasons and solutions for 'false positive results' of 2019 Novel Coronavirus-specific antibodies detection / 中华检验医学杂志

Assays of specific immunoglobulin M (IgM) and immunoglobulin G (IgG) have been supplemented in 'diagnosis and treatment guidelines of Novel Coronavirus pneumonia' (7th edition) issued by National Health Commission of the People’s Republic of China as an auxiliary evidence to diagnose Novel Coronavirus pneumonia. However, the false positive results is a major problem in the application of antibody assays. The factors causing the false positive results were analyzed and the ways were discussed to reduce the false positive results. The false positive results of antibody assays can be reduced, but they cannot be fully resolved. Antibody assays are valuable criteria for the diagnosis of suspected cases with negative nucleic acid results only if at least two dynamic tests are used.

Preliminary application of Region 4 Stork project used in newborn screening by tandem mass spectrometry / 中华检验医学杂志

Objective To investigate the feasibility of Region 4 Stork(R4S)project used for newborn screening by tandem mass spectrometry in China.Methods This retrospective study was performed among 362 822 neonates screened by tandem mass spectrometry from May 2015 to April 2016 in Zhejiang newborn screening center.Infants were grouped by screening result category: 83 true positive cases,360 554 true negative cases and 2 185 false positive cases.Raw data was uploaded into R4S website to perform postanalytical interpretive tools, then results were analyzed with interpretation rules.The comparisons of normal population percentiles were done at five selected percentiles between Zhejiang newborn screening center and R4S project with min-max normalization.Results Compared with cutoff system by using R4S project with interpretation rules,the positive predictive value increased from 3.7%to 8.3%,the specificity increased from 99.40%to 99.75%, and the false positive rate declined from 0.6% to 0.2%. The two cases of true positive hyperprolinemia were reported negative, and one case of β-ketothiolase deficiency was misdiagnosis.Totally 311 638 cases in true negative group were resolved by postanalytical interpretive tools,and the remaining 48 916 cases were excluded with interpretation rules.False positive cases were reduced to 897 cases.Results of percentiles comparison showed that levels of some markers were significantly different between zhejiang newborn screening center and R 4S project.Conclusions R4S project effectively improved the newborn screening performance, whereas leaded to a small number of misdiagnosis and missed diagnosis.Besides,many true negative cases should be excluded with interpretation rules.Optimization should be achieved based on local normal population.(Chin J Lab Med,2018,41:300-304)

Involvement of cross-reactive carbohydrate determinants-specific IgE in pollen allergy testing

BACKGROUND: Specific IgE antibodies against the low-molecular-weight carbohydrate antigen that does not bridge IgE molecules on mast cells are not associated with clinical symptoms. Cross reactivity can be determined in allergen-specific IgE detection assays when the carbohydrate structures between pollen allergens and plant derived food allergens are similar; in such cases, false positive results for grain or legume allergens can be reported for pollen allergic patients who are not sensitized to those allergens. This phenomenon arises owing to the presence of cross-reactive carbohydrate determinants (CCDs). OBJECTIVE: This study aimed to assess the impact of CCD interference on the results for pollen allergen-specific IgE antibodies in the general adult population and to perform CCD inhibition tests evaluating the involvement of CCD on samples positive to pollen allergens. METHODS: Serum samples from 322 subjects were tested for IgE antibodies to pollens and CCD. The research subjects were given questionnaires about pollen allergic symptoms to help assess the presence of allergies. Allergen IgE antibodies for Japanese cedar, Japanese cypress, orchard grass, ragweed, MUXF, bromelain, horseradish peroxidase (HRP), and ascorbate oxidase (ASOD) were analyzed. RESULTS: It was observed that among individuals who tested positive to any of the pollen allergens, the positive ratio of CCD-specific IgE antibody was the highest for HRP (13.5%–50.0%). The results from the inhibition tests revealed that CCD was marginally present. Although IgE antibodies for cedar pollen did not react with CCD, IgE antibodies for Japanese cypress, orchard grass, and ragweed might be detected by the presence of CCD. CONCLUSION: The results of the inhibition tests revealed the obvious presence of CCD suggesting its involvement. Considering these findings, careful evaluation of patient IgE results should be performed for Japanese cypress, orchard grass, and ragweed.

Understanding one-way ANOVA using conceptual figures / 대한마취과학회지

Analysis of variance (ANOVA) is one of the most frequently used statistical methods in medical research. The need for ANOVA arises from the error of alpha level inflation, which increases Type 1 error probability (false positive) and is caused by multiple comparisons. ANOVA uses the statistic F, which is the ratio of between and within group variances. The main interest of analysis is focused on the differences of group means; however, ANOVA focuses on the difference of variances. The illustrated figures would serve as a suitable guide to understand how ANOVA determines the mean difference problems by using between and within group variance differences.

Factors accounting for HIV antibody test false positive results in patients with rheumatoid arthritis / 中华检验医学杂志

Objective To investigate if immunological factors associated with the false HIV screening test results in RA.Methods Subjects who attended the Rheumatology Outpatient Clinic -Internal Medicine Unit of Guanghua Integrative Hospital , from October 2013 to October 2014, who met the American College of Rheumatology /European League Against Rheumatism Criteria for RA were recruited for the study . 100 subjects with RA were recruited.Each patient underwent clinical examination and blood sampling for assessment of serum HIV screening test and Rheumatoid factors ( RF-IgA, -IgG, -IgM) and anti-cyclic citrullinated protein antibodies (anti-CCP) were purified from the plasma and detected by ELISA , Samples were collected and processed using standard protocols and were stored in the same freezer before analysis . RA patients were divided into two groups based on the titters of RF and anti -CCP:RF 300 U/ml /anti-CCP >500 U/ml group.HIV screening tests were determined by three methods: ELISA、Immuno-colloidal Golden Method and ECLIA.The positive results were confirmed by the Changning Centers for Disease Control , Shanghai through western -blotting test.Results 100 samples detected by ELISA and Immuno-colloidal Golden Method were given negative results , 16 positive results existed in ECLIA group.There were1,12,3 positive cases in RF-IgM 300 U/ml group(2.7%,32.4%,13.6%;P 500 RU/ml groups there were 2 and 4 positive results(4.7%,24.6%;P <0.01).Conclusions Different HIV screening test methods would give different results , according to operation requirement using second method to determine the HIV screening result.HIV False-positivity was associated with the titers of anti -CCP and RF in RA.

False positive results analysis of the cervical liquid-based preparation screening / 中国基层医药

Objective To analyze and summarize the cause of false positive results of the cervical liquid-based preparation screening,to improve the accuracy of cervical cytology diagnosis.Methods 20 353 cases were col-lected.The cytological diagnosis was statistically analyzed.Test positive results contrast analysis of the histologic diag-nosis was conducted.Cytological diagnosis of positive and histology diagnosis of non -neoplastic to review the original cytology.Results The incidence of 637 cases of cytology screening for positive.Among the 388 cases with histologic control,228 cases of histological diagnosis of abnormal change.Include:low -grade squamous intraepithelial lesion (LSIL),high -grade squamous intraepithelial lesion (HSIL),cervical squamous cell carcinoma (SCC),cervical ade-nocarcinoma(ACC),endometrioid carcinoma,malignamt melanoma.The other 160 cases did not check out the abnor-mal lesions.Conclusion Incidence of false positive results in 160 cases,accounting for 41.2%.It almost focused on atypical squamous cells of undetermined significance (ASC -US)and LSIL for a variety of reasons.Standardized work process should be taken to strengthen the training of the doctors,summarize continuously improve,as far as possi-ble to avoid false positive diagnosis.

Effect of Tube Current on the Pseudo-enhancement of Renal Cyst / 中国医学影像学杂志

PurposeTo evaluate the effect of tube current on the pseudo-enhancement of renal cyst by simulating the phantom model of simple renal cyst.Materials and Methods 10% glucose and iodine solution with a certain concentration was used to simulate the renal parenchymal background concentration in plain scan, moderate enhancement and maximum enhancement respectively. The diameters of the cysts were 6 mm, 10 mm and 15 mm, respectively, and the cysts were divided into three groups according to different tube current: 119 mAs (group A), 178 mAs (group B) and 297 mAs (group C) while the tube voltage were all 120 kV. Whether pseudo-enhancement exists in cyst under different conditions was determined using an increase of CT value of 10 HU as the critical value. Results In group A, there was pseudo enhancement at the 240 HU background, and it was most significant with the diameter of 6 mm, which was 21 HU. In group B, pseudo-enhancement occurred in cysts with diameter of both 10 mm and 6 mm under the background of 180 HU and 240 HU, moreover, the biggest difference was 20.4 HU and it occurred in cyst with diameter of 6 mm under the background of 240 HU. In group C, pseudo-enhancement only occurred in cyst with diameter of 6 mm under the condition of 125 HU and 240 HU background concentration. Background concentration (F=17.587, P<0.01) and cyst diameter (F=4.214,P<0.05) had greater impact on cyst pseudo-enhancement, the higher the background concentration and smaller the diameter, more significantly the pseudo-enhancement would occur. With the increase of the tube current, the CT volume dose index increased, and the pseudo enhancement value was smaller, but there was no obvious regularity of pseudo-enhancement occurrence rate in cysts with different background concentration and diameter in each group.Conclusion The increase of tube current cannot completely eliminate cyst pseudo-enhancement. High background concentration and small diameter cyst are important factors in pseudo-enhancement. However, increasing the tube current can reduce the probability of occurrence of pseudo-enhancement to some extent. For those with heavier body weight, it might be necessary to increase the tube current to improve image quality and reduce the occurrence of renal cyst pseudo-enhancement.

Controlled medial branch anesthetic block in the diagnosis of chronic lumbar facet joint pain: the value of a three-month follow-up

OBJECTIVES: To verify the incidence of facetary and low back pain after a controlled medial branch anesthetic block in a three-month follow-up and to verify the correlation between the positive results and the demographic variables. METHODS: Patients with chronic lumbar pain underwent a sham blockade (with a saline injection) and then a controlled medial branch block. Their symptoms were evaluated before and after the sham injection and after the real controlled medial branch block; the symptoms were reevaluated after one day and one week, as well as after one, two and three months using the visual analog scale. We searched for an association between the positive results and the demographic characteristics of the patients. RESULTS: A total of 104 controlled medial branch blocks were performed and 54 patients (52%) demonstrated >50% improvements in pain after the blockade. After three months, lumbar pain returned in only 18 individuals, with visual analogue scale scores >4. Therefore, these patients were diagnosed with chronic facet low back pain. The three-months of follow-up after the controlled medial branch block excluded 36 patients (67%) with false positive results. The results of the controlled medial branch block were not correlated to sex, age, pain duration or work disability but were correlated with patient age (p<0.05). CONCLUSION: Patient diagnosis with a controlled medial branch block proved to be effective but was not associated with any demographic variables. A three-month follow-up is required to avoid a high number of false positives. .

Cut-Off Value and Factors Associated with a False Positive D-Dimer Result for Venous Thromboembolism in Koreans / 대한내과학회지

BACKGROUND/AIMS: The D-dimer value is a simple blood test used to evaluate venous thromboembolism (VTE). However, due to its low specificity, another test is needed for a definite diagnosis, such as a radiographic test. We evaluate the factors associated with a false positive D-dimer test and propose a new cut-off value for detecting VTE more effectively in Koreans. METHODS: This was a retrospective, observational study. From January 2009 to December 2009, 2,047 patients (988 men, 63 +/- 15 years) had the D-dimer value checked to evaluate VTE. The main outcome of interest was a positive D-dimer test. Odds ratio and 95% confidence intervals were determined using logistic regression analysis. The new D-dimer cut-off was evaluated using receiver operating characteristics (ROC) curves. RESULTS: The result was positive in 1,093 patients (53%), for a false positive percentage for VTE of 95% and a false negative percentage for VTE of 1%. Significant false positive predictors for a positive D-dimer were increasing age, trauma, postoperative, acute infection, tuberculosis, stroke, malignancy, chronic renal failure, acute coronary syndrome, heart failure, and lung disease. The discriminative value of the D-dimer test was assessed using ROC curve analysis. A D-dimer value of 0.68 mg/L on admission was the best cut-off value for predicting the development of VTE with a sensitivity of 95% and specificity of 57%. CONCLUSIONS: Many factors affect the D-dimer value and we must consider these factors before using the D-dimer value to evaluate VTE. A D-dimer value of 0.68 mg/L appears to be a good cut-off value for evaluating VTE more effectively in Koreans.

Etiologies and Predictors of ST-Segment Elevation Myocardial Infarction

BACKGROUND AND OBJECTIVES: Rapid diagnosis of ST-segment elevation myocardial infarction (STEMI) is essential for the appropriate management of patients. We investigated the prevalence, etiologies and predictors of false-positive diagnosis of STEMI and subsequent inappropriate catheterization laboratory activation in patients with presumptive diagnosis of STEMI. SUBJECTS AND METHODS: Four hundred fifty-five consecutive patients (62+/-13 years, 345 males) with presumptive diagnosis of STEMI between August 2008 and November 2010 were included. RESULTS: A false-positive diagnosis of STEMI was made in 34 patients (7.5%) with no indication of coronary artery lesion. Common causes for the false-positive diagnosis were coronary spasm in 10 patients, left ventricular hypertrophy in 5 patients, myocarditis in 4 patients, early repolarization in 3 patients, and previous myocardial infarction and stress-induced cardiomyopathy in 2 patients each. In multivariate logistic regression analysis, symptom-to-door time >12 hours {odds ratio (OR) 4.995, 95% confidence interval (CI) 1.384-18.030, p=0.014}, presenting symptom other than chest pain (OR 7.709, 95% CI 1.255-39.922, p=0.027), absence of Q wave (OR 9.082, CI 2.631-31.351, p<0.001) and absence of reciprocal changes on electrocardiography (ECG) (OR 17.987, CI 5.295-61.106, p<0.001) were independent predictors of false-positive diagnosis of STEMI. CONCLUSION: In patients whom STEMI was planned for primary coronary intervention, the false-positive diagnosis of STEMI was not rare. Correct interpretation of ECGs and consideration of ST-segment elevation in conditions other than STEMI may reduce inappropriate catheterization laboratory activation.

A Case of Duodenal Leiomyoma Showing False Positive Fluorine-18-fluorodeoxyglucose Positron-Emission Tomography

Duodenal leiomyomas are rare benign tumors of mesenchymal origin. Generally, Fluorodeoxyglucose (FDG)-PET would have a negative finding in leiomyomas. A 52-year-old man was referred to our hospital with melena. Gastroendoscopy revealed the presence of a huge submucosal tumor with ulceration at the duodenum bulb. Subsequent CT demonstrated a poorly enhanced oval mass adjoining the duodenal bulb. FDG-PET scan demonstrated an excessive accumulation of FDG in the lesion. A definitive diagnosis of duodenal leiomyoma was made on the basis of the pathologic finding of his surgical specimen. We report in this first case that duodenal leiomyma may show a potential pitfall of giving a positive FDG-PET result. Through this case, we would like to caution clinicians against PET-dependent evaluations of malignant potential of duodenal submucosal tumors.

Detection of Bartonella henselae in defibrinated sheep blood used for culture media supplementation

Bartonella henselae was detected in defibrinated sheep blood employed in supplementing a selective bacteria culture medium by nested PCR. We recommended that highly sensitive technical tests be run to ensure a sterile culture medium for Bartonella spp. isolation, since infected blood samples used in preparation could lead to false-positive results.

False-Positive Hypermetabolic Lesions on Post-Treatment PET-CT after Influenza Vaccination

We report a case of a 59-year-old man with testicular germ cell tumor who showed new hypermetabolic lesions at the left axillary lymph nodes on a post-treatment positron emission tomography-computed tomography (PET-CT) scan. The hypermetabolic lesions were found to be caused by an influenza vaccination 10 days prior to the PET-CT scan and disappeared without additional treatment. To date, he is alive with complete remission.

Interference of alkaline phosphatase on clinical cardiac troponin Ⅰ assay / 中华检验医学杂志

Objective To evaluate the interference of ALP on cTnI assays. Methods One normal mixed plasma sample and 2 abnormal mixed plasma samples with different cTnI levels were prepared, and then divided them into 8 groups respectively. One group was randomly chosen as control while different amounts of ALP were added into the other seven groups. The concentrations of cTnI and ALP in each plasma portion were detected by ACCESS2 (Beckman-Coulter, Inc ) and AXSYM (Abbott Laboratories )separately. The results of the seven tested groups were then compared with those of the control, so as to evaluate whether ALP could interfere with the cTnI assay. Results When the chemiluminescent Access cTnI assay was carried out for detection of normal plasma, the concentration of ALP was up to 3 716 U/L and did not interfere with the test results of cTnI [(0. 04 ±0.01) μg/L] compared with those of the control portion [(0. 04 ± 0. 01 ) μg/L] (t = 0. 40, P ＞ 0. 05 ). Once the concentration of ALP went beyond 917 U/L, the AXSYM cTnI assay results [( 0.08 ± 0. 01 ) μg/L] were higher than those of the normal control ( t =-4. 89, P＜0. 01 ); When the concentration of ALP was up to 3 534 U/L, the test results of abnormal plasma cTnI detected by the Access assay [( 13.41 ±0. 17) μg/L] did not show significant differences from those of the control [(13.48±0.16) μg/L] (t=0. 52,P＞0.05).Conclusions High concentration ofALP did not interfere with the Access cTnI assay or lead to false positive results. However, the high level of ALP( ＞ 917 U/L) could interfere with the AXSYM cTnI assay and cause a false positive result.

Redution of false positivities of IgM antibodies against hepatitis E virus by a truncated immunodominant polypepfide of HEY open reading frame 2 / 中华检验医学杂志

Objective To exclude false positivities in detection of IgM antibodies against hepatitis E vires of genotype 4 (HEV-4) using a truncated immunodominant polypeptide of HEV open reading frames (ORF2). Methods The recombinant ORF2 immunodominant polypeptide corresponding to amino acids (AA) 459-607 and a truncated polypeptide corresponding to AA 472-607 were separately applied to coat ELISA plates. Anti-HEV IgM from 35 serum samples with HEV RNA positive, 69 serum samples from healthy individuals and 117 clinically suspicious HEV RNA positive serum samples was detected by an indirect ELISA and was confirmed by western blot in protein level and RT-PCR detecting in RNA level. Results Western blot analysis showed that the sera from HEV patients reacted with the dimmer of peptide 459-607, but they didn't react with the monomer and peptide 472-607. The ELISA showed that all 35 serum HEV RNA positive samples reacted with peptide 459-607 but not with peptide 472-607 and none of the 69 serum samples from healthy individuals reacted with either polypeptide. Among 117 chnically suspicious HEV RNA serum samples, 5 samples reacted simultaneously with both polypeptides. But the difference between 450 nm absorbance (A450) value was less than 0. 5. Western blot analysis demonstrated that all the 5 serum samples were anti-HEV IgM- negative. The 5 serum samples was detected negative by RT-PCR, indicating that the false pesitivities were caused by non-specific absorption. Conclusions ORF2 peptide 459-607 may be used to detect anti-HEV lgM efficiently. The false positivities caused by non-specific absorption can be largely excluded according to the difference between 45Ohm absorbance (A450) value when serum reacts with both polypeptides.