Clinical Significance of Combined Weight-Bearing and Non-Weight-Bearing Positions and MRI Examination in Evaluating Genu Varus

Objective

To siscuss the clinical significance of the early diagnosis of knee varus and knee osteoarthritis with the combination of negative position and non‐negative position and radiography.

Methods

One hundred and eighty patients whose femorotibial angles <182° (genu varus positive) measured by X‐ray at the weight‐bearing position and femorotibial angles ≥182° (genu varus negative) measured by X‐ray at the non‐weight‐bearing position were selected as the sample group from those patients who received knee joint Magnetic resonance imaging (MRI) examination from July 2015 to July 2017. One hundred and eighty patients whose femorotibial angles ≥182° (genu varus negative) measured at both the weight‐bearing position and the non‐weight‐bearing position were selected as the control group. Femorotibial angles of both groups were respectively measured, to respectively compare and analyze the effect of non‐weight‐bearing false‐negative genu varus on the occurrence and severity of injury of medial meniscus and femorotibial articular cartilage. The two groups of patients had no previous history of knee surgery, and no lower limb fracture, inflammation, tumor, metabolic bone disease, or congenital disease.

Results

The weight‐bearing tibiofemoral angles of the non‐weight‐bearing false‐negative genu varus group and the negative genu varus group (180.998° ± 0.589°) were lower than the non‐weight‐bearing tibiofemoral angles (182.501° ± 0.290°), and they were positively correlated (t = −15.048, P < 0.01). The non‐weight‐bearing knee varus medial meniscus incidence of false‐ negative group. Medial meniscus injury that occurred in the sample group were 86.7% (156/180) in the anterior horn, 91.7% (165/180) in the body, 88.3% (159/180) in the posterior horn. Medial meniscus injury that occurred in the control group were 46.7% (84 /180) in the anterior horn, 40.6.3% (73/180) in the body, 43.3% (78/180) in the posterior horn. The incidence of degenerative groups, the differences were statistically significant. The incidence and severity of injury were as follows: medial meniscus anterior horn (χ² = 41.966, P = 0.000), body (χ² = 104.94, P = 0.000), posterior horn (χ² = 81.025, P = 0.000). The incidence and severity of medial meniscus injury in the non‐weight‐bearing knee varus false negative group was higher than in the control group. The non‐weight‐bearing knee varus false‐negative group medial tibiofemoral articular cartilage degeneration rate was 95.0% (171/180); in the control group, medial tibiofemoral articular cartilage degeneration was 65.1% (117/180). Two medial tibiofemoral articular cartilage degeneration incidence were statistically significant. The incidence and severity of injury were as follows: medial tibiofemoral articular cartilage (χ² = 50.625, P = 0.000). The incidence and severity of medial tibiofemoral articular cartilage injury in the non‐weight‐bearing knee varus false negative group was higher than in the control group.

Conclusion

The combined weight‐bearing position and non‐weight‐bearing position imaging examination for diagnosing the non‐weight‐bearing false‐negative genu varus patients at an early date is of significant importance to the early diagnosis and treatment of knee osteoarthritis.

The role of rare breast cancers in the false negative strain elastography results

PURPOSE

Elastography was primarily used as an adjunctive method along with ultrasonography in differentiation between benign from malignant lesions. Occasionally, overlaps can occur which are caused by some rare invasive breast cancers. Our aim is to analyze the role of rare breast cancers in false negative strain elastography results and to assess the relation among false negative results and tumor size, lesion distance to skin, and tumor grade.

METHODS

Patients with BI-RADS 5 category underwent strain elastography and core biopsy. All those with confirmed invasive breast cancer were included. For each rare breast cancer, four usual invasive breast cancer cases were taken as a control group. The cut-off value of strain ratio was considered as 2.3. The true positive and the false negative groups were compared in terms of histological type (rare carcinomas and the others) and the other parameters. Pearson Chi-square and Fisher's exact test were used for statistical analyses. P values < 0.05 were considered statistically significant.

RESULTS

One hundred-thirteen patients were defined as true positive (70.6%), and 47 patients were defined as false negative (29.4%). Strain ratio values of the rare breast cancers were significantly lower than those of the other breast cancers (p = 0.012). There was no statistically significant difference between the groups with respect to tumor size, distance to skin, and tumor grade (p > 0.05).

CONCLUSION

The rare breast cancers are an important cause of false negativity in elastographic evaluation of invasive breast cancers. The results should be interpreted in combination with grayscale US findings.

Which clinical, radiological, histological, and molecular parameters are associated with the absence of enhancement of known breast cancers with Contrast Enhanced Digital Mammography (CEDM)?

Background

CEDM has demonstrated a diagnostic performance similar to MRI and could have similar limitations in breast cancer (BC) detection.

Purpose

The aim of our study was to systematically analyze the characteristics of the lesions with the absence of enhancement with CEDMs, called false-negatives (FNs), in order to identify which clinical, radiological, histological and molecular parameters are associated with the absence of enhancement of known BCs with CEDMs, and which types of BC are most likely to cause FNs in CEDMs. We also tried to evaluate which parameters instead increased the probability of showing enhancement in the same context.

Materials and methods

Included in our study group were 348 women with 348 diagnosed BCs performing CEDM as preoperative staging. Two breast-imaging radiologists reviewed the CEDM exams. The absence of perceptible contrast enhancement at the index cancer site was indicative of an FN CEDM, whereas cases with appreciable enhancement were considered true positives (TPs). Dichotomic variables were analyzed with Fisher’s exact probability test or, when applicable, the chi-square test. Binary logistic regression was performed on variables shown to be significant by the univariate analysis in order to assess the relationship between predictors (independent variables) and TFNs (outcome).

Results

Enhancement was observed in 317 (91.1%) of the 348 BCs. From the 31 (8.9%) lesions which were FNs, we excluded 12 (38.7%) which showed an artifact generated by the post biopsy hematoma and 6 (19.4%) which were outside the CEDM field of vision. We thus obtained 13 (41.9%) BCs considered “True False Negatives” (TFNs), i.e. BCs which showed no enhancement despite being within the CEDM field of vision and failed to show post biopsy hematoma artifacts. We found that the TFNs frequently have a unifocal disease extension, diameter <10 mm, a lower number of luminal B HER2-subtypes, a higher number of DCIS, and an index lesion with microcalcifications.

Conclusions

The parameters we found to be associated with no enhancement of known BCs with CEDMs were: unifocal disease extension, DCIS histotype, lesion dimensions <10 mm, and index lesion with microcalcifications. The characteristics that instead increase the probability of showing enhancement were US mass, Luminal B HER2 negative molecular subtype, the presence of an invasive ductal component, and lesion dimensions ≥10 mm.

•

The variables associated with an increased risk of no enhancement were unifocal disease extension, non-classifiable molecular subtype, DCIS histotype, lesion dimensions <10 mm, index lesion represented by microcalcifications.

•

A greater probability of showing enhancement entailed the presence of an invasive ductal component, index lesion represented by ultrasound mass, Luminal B HER2 negative molecular subtype, lesion dimensions ≥10 mm, multifocal disease extension.

A COVID-19 patient with multiple negative results for PCR assays outside Wuhan, China: a case report

Background

The outbreak of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a public health emergency of major international concern. Real-time RT-PCR assays are recommended for diagnosis of COVID-19. Here we report a rare case of COVID-19 with multiple negative results for PCR assays outside Wuhan, China.

Case presentation

A 32-year old male was admitted to our hospital because of 6 days of unexplained fever on January 29, 2020. He had come from Wuhan city 10 days before admission. Five days before admission, no abnormality was noted in laboratory test, chest radiography, and nasopharyngeal swab test for the SARS-CoV-2 nucleic acid. The patient was treated with ibuprofen for alleviating fever. On admission, chest computed tomography showed multiple ground-glass opacities in right lower lung field. COVID-19 was suspected. Three times of nasopharyngeal swab specimens were collected after admission. However, none of the specimens were positive. The patient was confirmed with COVID-19 after fifth SARS-CoV-2 nucleic acid test. He was treated with lopinavir/ritonavir, recombinant human interferon alfa-2b inhalation, methylprednisolone. After 18 days of treatment, he was discharged with improved symptoms, lung lesions and negative results of nasopharyngeal swab.

Conclusion

This case reminds clinician that a patient with high clinical suspicion of COVID-19 but multiple negative RT-PCR result should not be taken out of isolation. A combination of patient’s exposure history, clinical manifestations, laboratory tests, and typical imaging findings plays a vital role in making preliminary diagnosis and guide early isolation and treatment. Repeat swab tests are helpful in diagnosis for this kind of patients.

Clinical significance of anti-glycopeptidolipid-core IgA antibodies in patients newly diagnosed with Mycobacterium avium complex lung disease

BACKGROUND

Although recent studies have identified anti-glycopeptidolipid (GPL)-core IgA antibodies as a serodiagnostic test for Mycobacterium avium complex lung disease (MAC-LD), this test shows insufficient sensitivity. This study aimed to determine the clinical utility of these antibodies in assessing disease progression and the clinical characteristics of MAC-LD patients with negative antibody results.

METHODS

We retrospectively reviewed the medical records of consecutive newly diagnosed, untreated MAC-LD patients in two referral hospitals. We evaluated the association of anti-GPL-core IgA antibody results with disease progression requiring treatment and the factors associated with negative antibody results.

RESULTS

In total, 229 patients (161 females; median age, 71 years; 185 with nodular/bronchiectatic disease phenotype; 69 with cavitary lesions) were enrolled; 146 patients (64%) were anti-GPL-core IgA antibody-positive. Radiological severity scores were associated with anti-GPL-core IgA antibody titers. During the median 364-day follow-up, 114 patients (49.8%) required treatment. Multivariate Cox proportional hazards analysis showed that positive anti-GPL-core IgA antibody results, a younger age, the absence of malignancy, and the presence of cavitary lesions were associated with disease progression requiring treatment. Multivariate logistic analysis revealed that significant factors related to the negative antibody results included underlying pulmonary disease, lower radiological scores, chronic sinusitis, and macrolide monotherapy.

CONCLUSION

In addition to cavitary lesions, anti-GPL-core IgA antibody positivity was associated with disease progression requiring treatment. Physicians should carefully use anti-GPL-core IgA antibody results for the diagnosis of patients with underlying pulmonary disease, chronic sinusitis, macrolide monotherapy, and lower radiological severity.

A rare Down syndrome foetus with de novo 21q;21q rearrangements causing false negative results in non-invasive prenatal testing: a case report

BACKGROUND

Non-invasive prenatal testing (NIPT) has been established as a routine prenatal screening to assess the risk of common foetal aneuploidy disorder (trisomy 21, 18, and 13). NIPT has high sensitivity and high specificity, but false positive and false negative results still exist. False negative NIPT results involving Down syndrome are rare, but have a high clinical impact on families and society.

CASE PRESENTATION

We described a case of a foetus that tested "negative" for trisomy 21 (Z-score was 0.664) by NIPT based on the semiconductor sequencing platform (SSP). The foetal fraction of cell-free DNA was 16.9%; this percentage was much larger than the threshold of 4% for obtaining accurate NIPT results. However, postnatally, the newborn was diagnosed with Down syndrome with the 46,XY,der(21;21)(q10;q10),+ 21 karyotype.

CONCLUSIONS

We presented a case of false negative NIPT results, which may occur through biological mechanisms rather than poor quality, technical errors or negligence. It is imperative for clinical geneticists and their patients to understand that NIPT is still a screening test.

Optimized Batrachochytrium dendrobatidis DNA extraction of swab samples results in imperfect detection particularly when infection intensities are low

Accurate detection of the amphibian fungal pathogen Batrachochytrium dendrobatidis (Bd) is critical for wildlife disease research; however, false negatives in detection do occur. Here we compared different DNA extraction methods to determine the threshold for Bd detection and identify an optimal extraction method to improve detection and quantification of the pathogen. We extracted both lab-created cell suspension standards using PrepMan Ultra, Chelex resin, and 3 spin column DNA extraction kits (Qiagen DNeasy Blood and Tissue, Zymo Quick DNA miniprep, and IBI gMAX mini kit), and further compared extraction methods using field-collected samples. We found that when extracting Bd DNA from cells in lab-created culture, the spin column extraction methods and PrepMan Ultra were equivalent, while the resin method detected higher Bd DNA quantities, especially at higher loads. However, when swabs from live animals were analyzed, low Bd quantities were more than twice as likely to be detected using a spin column extraction than with the PrepMan Ultra extraction method. All tested spin column extraction methods performed similarly across both field and lab samples. Samples containing low Bd quantities yielded inconsistent detection and quantification of Bd DNA copies regardless of extraction method. To manage imperfect detection of Bd, we suggest that presence/absence analyses are more informative than attempting to quantify Bd DNA when quantities are low. Overall, we recommend that a cost-benefit analysis of target species susceptibility and epidemiology be taken into consideration when designing an experiment to determine the most appropriate DNA extraction method to be used, because sometimes detecting low Bd quantities is imperative to the study, whereas in other situations, detecting low DNA quantities is less important.

A Comprehensive Approach Is Vital for Diagnosing COVID-19: A Case of False Negative

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is spreading at a rapid pace throughout the world, and the World Health Organization (WHO) declared it as pandemic on March 11, 2020. We present a case of COVID-19 patient whose reverse transcription-polymerase chain reaction (RT-PCR) initially was false negative and later turned positive, which will stress the importance of a comprehensive approach while evaluating a patient with a differential of COVID-19. The clinicians should be aware of the sensitivity and specificities of these tests which can have grave implications on the patient and community if the diagnosis is missed just based on the laboratory tests due to the highly contagious nature of the disease.

Comparison of radial and meander-like breast ultrasound with respect to diagnostic accuracy and examination time

Purpose

To prospectively compare the diagnostic accuracy of radial breast ultrasound (r-US) to that of conventional meander-like breast ultrasound (m-US), patients of a consecutive, unselected, mixed collective were examined by both scanning methods.

Methods

Out of 1948 dual examinations, 150 revealed suspicious lesions resulting in 168 biopsies taken from 148 patients. Histology confirmed breast cancers in 36 cases. Sensitivity, specificity, accuracy, PPV, and NPV were calculated for r-US and m-US. The examination times were recorded.

Results

For m-US and r-US, sensitivity (both 88.9%), specificity (86.4% versus 89.4%), accuracy (86.9% versus 89.3%), PPV (64.0% versus 69.6%), NPV (both 98.3%), false-negative rate (both 5.6%), and rate of cancer missed by one method (both 5.6%) were similar. The mean examination time for r-US (14.8 min) was significantly (p < 0.01) shorter than for m-US (22.6 min).

Conclusion

Because the diagnostic accuracy of r-US and m-US are comparable, r-US can be considered an alternative to m-US in routine breast US with the added benefit of a significantly shorter examination time.

A broad-based approach to differentiate CIN from its mimics: The utility of in situ hybridization and immunohistochemistry

The hematoxylin and eosin slides of 100 consecutive cases diagnosed as CIN 1-2 were combined with 25 CIN 1 and 25 negative for CIN as documented by in situ HPV testing. The 150 cases were then reviewed blinded and scored as "CIN" or "negative for CIN". Each of the 50 controls was correctly scored. Of the 100 cases, 62 were diagnosed as CIN and the other 38 were scored as negative for CIN on re-review. Each of the CIN cases was positive for HPV as proven by the in situ detection of either HPV DNA or the L1 capsid protein. The 38 cases diagnosed as negative for CIN and 38 of the CIN cases were tested for HPV DNA by in situ hybridization and for a panel of biomarkers that included p16, Ki67, importin-β, exportin-5, and Mcl1 plus the L1 HPV capsid protein. Each of the 38 CIN cases was positive for HPV as well as each biomarker that localized towards the basal aspect of the lesion. Two of the 38 negative for CIN cases were positive for HPV DNA/L1 capsid protein and each of the biomarkers. The other 36 cases were negative for HPV DNA/L1 protein and each of the biomarkers showed baseline expression. Thus, 36% of the diagnoses of CIN 1-2 were incorrect and this could have been prevented with either in situ detection of the viral DNA/capsid protein or the immunohistochemistry detection of a panel of biomarkers that included p16, Ki67, importin-β, exportin-5, and Mcl1.

All tests are imperfect: Accounting for false positives and false negatives using Bayesian statistics

Tests with binary outcomes (e.g., positive versus negative) to indicate a binary state of nature (e.g., disease agent present versus absent) are common. These tests are rarely perfect: chances of a false positive and a false negative always exist. Imperfect results cannot be directly used to infer the true state of the nature; information about the method's uncertainty (i.e., the two error rates and our knowledge of the subject) must be properly accounted for before an imperfect result can be made informative. We discuss statistical methods for incorporating the uncertain information under two scenarios, based on the purpose of conducting a test: inference about the subject under test and inference about the population represented by test subjects. The results are applicable to almost all tests. The importance of properly interpreting results from imperfect tests is universal, although how to handle the uncertainty is inevitably case-specific. The statistical considerations not only will change the way we interpret test results, but also how we plan and carry out tests that are known to be imperfect. Using a numerical example, we illustrate the post-test steps necessary for making the imperfect test results meaningful.

ALK detection in lung cancer: identification of atypical and cryptic ALK rearrangements using an optimal algorithm

PURPOSE

IHC, FISH, and NGS are common methods of ALK evaluation in NSCLC. The purpose of this study was to investigate whether ALK false positives or false negatives occurred more often in daily routines. An approach to identify ALK fusion was then proposed.

MATERIALS AND METHODS

We analyzed 1815 cases of NSCLC, including 83 (4.6%) ALK IHC positives. Total 182 samples (62 ALK+ and 120 ALK-) were examined via FISH, RT-ddPCR, NGS, RT-qPCR and RNAscope to confirm ALK status.

RESULTS

One ALK FISH false negative was found, which harbored two genomic rearrangements involved in EML4-ALK (exon 13:exon 20) fusion. One ALK IHC false negative was confirmed depending on a rare ALK FISH-positive pattern and ALK RNAscope positive but ALK fusion was not found via NGS. In addition, an atypical ALK FISH-positive pattern was observed in an IHC-positive case with chromosome 2 inversion leading to EML4-ALK (exon 6:exon 20) fusion. EML4-ALK fusion was determined in one case with an atypical FISH patterns by RT-qPCR. Rare complicated genomic rearrangements involved in a novel ALK fusion of EML4-ALK (exon 7:exon 14) were distinguished in an ALK IHC and FISH double-positive case.

CONCLUSION

False negative of ALK IHC, FISH and NGS results were found in our cohort, but none was false ALK positive. False ALK negatives should be more concerned than false positives. ALK rearrangements with cryptic ALK fusion patterns could be identified using our algorithm. Non-squamous non-small cell lung cancer was recommended for priority detection.

Resolving the Tension Between Exploration and Confirmation in Preclinical Biomedical Research

Confirmation through competent replication is a founding principle of modern science. However, biomedical researchers are rewarded for innovation, and not for confirmation, and confirmatory research is often stigmatized as unoriginal and as a consequence faces barriers to publication. As a result, the current biomedical literature is dominated by exploration, which to complicate matters further is often disguised as confirmation. Only recently scientists and the public have begun to realize that high-profile research results in biomedicine can often not be replicated. Consequently, confirmation has become central stage in the quest to safeguard the robustness of research findings. Research which is pushing the boundaries of or challenges what is currently known must necessarily result in a plethora of false positive results. Thus, since discovery, the driving force of scientific progress, is unavoidably linked to high false positive rates and cannot support confirmatory inference, dedicated confirmatory investigation is needed for pivotal results. In this chapter I will argue that the tension between the two modes of research, exploration and confirmation, can be resolved if we conceptually and practically separate them. I will discuss the idiosyncrasies of exploratory and confirmatory studies, with a focus on the specific features of their design, analysis, and interpretation.

Clinical application of QuantiFERON-TB Gold in-tube in the diagnosis and treatment of tuberculosis

At present, although it has made great progress in the diagnosis and treatment of tuberculosis, tuberculosis is still an important cause of morbidity and mortality. There were approximately 8.6 million new cases of tuberculosis in 2012, and approximately 1.3 million people died from tuberculosis. Early diagnosis and timely treatment are essential for controlling the spread of tuberculosis infection and reducing mortality. Conventional methods of Mycobacterium tuberculosis detection such as acid-fast staining microscopy and tuberculin skin test are widely used, but with low sensitivity or specificity. In recent years, a newly developed quantitative test, γ-interferon release test (IGRA), has been recognized and widely applied to the early diagnosis and monitoring of tuberculosis. QuantiFERON-TB Gold in-tube (QFT-GIT) is one of the mature IGRA methods. This paper summarizes the researches on QFT-GIT in recent years and introduces its principles, methodology, clinical application, and factors of uncertain results for the diagnosis and treatment of tuberculosis.

Sagittal diffusion-weighted imaging in preventing the false-negative diagnosis of acute brainstem infarction: Confirmation of the benefit by anatomical characterization of false-negative lesions

Background:

In some cases of acute brainstem infarction (BI), standard axial diffusion-weighted imaging (DWI) does not show a lesion, leading to false-negative (FN) diagnoses. It is important to recognize acute BI accurately and promptly to initiate therapy as soon as possible.

Methods:

Of the 171 patients with acute cerebral infarctions in our institution who were examined, 16 were diagnosed with true-positive BI (TP-BI) and six with FN-BI. We evaluated the effectiveness of sagittal DWI in accurately diagnosing acute BI and sought to find the cause of its effectiveness by the anatomical characterization of FN-BIs.

Results:

Considering the direction of the brainstem perforating arteries, we supposed that sagittal DWI might more effectively detect BIs than axial DWI. We found that sagittal DWI detected all FN-BIs more clearly than axial DWI. The mean time between the onset of symptoms and initial DWI was significantly longer in the TP group (17.6 ± 5.5 h) than in the FN group (5.0 ± 1.2 h; P < 0.0001). The lesion volumes were much smaller in FN-BIs (259 ± 82 mm³) than in TP-BIs (2779 ± 767 mm³; P = 0.0007). FN-BIs had a significant inverse correlation with the ventrodorsal length of infarcts (FN 3.5 ± 1.1 mm, TP 11.4 ± 3.6 mm; P < 0.0004) and no correlation with other size parameters such as rostrocaudal thickness and lateral width.

Conclusion:

Anatomical characterization clearly confirmed that the addition of sagittal DWI to the initial axial DWI in suspected cases of BI ensures its accurate diagnosis and improves the patient’s prognosis.

New software for automated cilia detection in cells (ACDC)

Background

Primary cilia frequency and length are key metrics in studies of ciliogenesis and ciliopathies. Typically, quantitative cilia analysis is done manually, which is very time-consuming. While some open-source and commercial image analysis software applications can segment input data, they still require the user to optimize many parameters, suffer from user bias, and often lack rigorous performance quality assessment (e.g., false positives and false negatives). Further, optimal parameter combinations vary in detection accuracy depending on cilia reporter, cell type, and imaging modality. A good automated solution would analyze images quickly, robustly, and adaptably—across different experimental data sets—without significantly compromising the accuracy of manual analysis.

Methods

To solve this problem, we developed a new software for automated cilia detection in cells (ACDC). The software operates through four main steps: image importation, pre-processing, detection auto-optimization, and analysis. From a data set, a representative image with manually selected cilia (i.e., Ground Truth) is used for detection auto-optimization based on four parameters: signal-to-noise ratio, length, directional score, and intensity standard deviation. Millions of parameter combinations are automatically evaluated and optimized according to an accuracy ‘F1’ score, based on the amount of false positives and false negatives. Afterwards, the optimized parameter combination is used for automated detection and analysis of the entire data set.

Results

The ACDC software accurately and adaptably detected nuclei and primary cilia across different cell types (NIH3T3, RPE1), cilia reporters (AcTub, Smo-GFP, Arl13b), and image magnifications (60×, 40×). We found that false-positive and false-negative rates for Arl13b-stained cilia were 1–6%, yielding high F1 scores of 0.96–0.97 (max. = 1.00). The software detected significant differences in mean cilia length between control and cytochalasin D-treated cell populations and could monitor dynamic changes in cilia length from movie recordings. Automated analysis offered up to a 96-fold speed enhancement compared to manual analysis, requiring around 5 s/image, or nearly 18,000 cilia analyzed/hour.

Conclusion

The ACDC software is a solution for robust automated analysis of microscopic images of ciliated cells. The software is extremely adaptable, accurate, and offers immense time-savings compared to traditional manual analysis.

Electronic supplementary material

The online version of this article (10.1186/s13630-019-0061-z) contains supplementary material, which is available to authorized users.

Survey of medical malpractice cases and settlements with pathology or laboratory standard of care issues

Medicolegal liability is an issue of concern for all physicians, including pathologists. Identification of the key clinical issues that tend to lead to medical malpractice litigation, as well as the settlement values for such claims, can be useful for prospective risk management. This review analyzes medical malpractice claims filed in state and federal courts as published in legal databases. Additionally, this review also analyzes the reported settlement values for such claims.

Nonspecific Binding in Immunoassays for Autoantibodies

Immunoassays are invaluable for detection and quantification of numerous analytes, including autoantibodies. However, human sera often yield high nonspecific binding in such assays, and this may result in false positive or sometimes false negative results. The causes of nonspecific binding are numerous and it correlates with inflammatory parameters. Since the results of autoantibody testing are used for diagnosis and treatment of autoimmune diseases, it is mandatory to be aware of all possible causes of nonspecific binding for each individual assay and to correct for it whenever possible. General guidelines for this are described in this chapter.

An enrichment method to increase cell-free fetal DNA fraction and significantly reduce false negatives and test failures for non-invasive prenatal screening: a feasibility study

Background

Noninvasive prenatal screening (NIPS) based on cell-free fetal DNA (cffDNA) has rapidly been applied into clinic. However, the reliability of this method largely depends on the concentration of cffDNA in the maternal plasma. The chance of test failure results or false negative results would increase when cffDNA fraction is low. In this study, we set out to develop a method to enrich the cffDNA for NIPS based on the size difference between cell-free DNA (cfDNA) of fetal origin and maternal origin, and to evaluate whether the new NIPS method can improve the test quality.

Methods

We utilized 10,000 previous NIPS data to optimize a size-selection strategy for enrichment. Then, we retrospectively performed our new NIPS method with cffDNA enrichment on the 1415 NIPS samples, including 1404 routine cases and 11 false negative cases, and compared the results to the original NIPS results.

Results

The 10,000 NIPS data revealed the fetal fraction in short cfDNA fragments (< 160 bp) is significantly higher. By using our new NIPS strategy on the 1404 routine cases, the fetal fraction increased from 11.3 ± 4.2 to 22.6 ± 6.6%, and the new method performed a significant decrease of test-failure rate (0.1% vs 0.7%, P < 0.01). Moreover, in 45.5% (5/11) of the false negative cases, fetal trisomies were successfully detected by our new NIPS method.

Conclusions

We developed an effective method to enrich cffDNA for NIPS, which shows an increased success rate and a reduced chance of false negative comparing to the ordinary NIPS method.

Electronic supplementary material

The online version of this article (10.1186/s12967-019-1871-x) contains supplementary material, which is available to authorized users.

Indications and Interpretation of Common Laboratory Assays in the Emergency Department

Laboratory assays are commonly used to help clinicians more accurately gauge the risk a child has for a certain condition. This article reviews commonly obtained laboratory tests (complete blood cell counts, metabolic panels, blood gases, and urine assays) and discusses the data supporting obtaining these tests and reasons for spuriously positive or negative results.

Predictors for false-negative QuantiFERON-TB Gold assay results in patients with extrapulmonary tuberculosis

BACKGROUNDS

Extrapulmonary tuberculosis (EPTB) is a heterogeneous disease, and diagnosis is sometimes difficult. We investigated the diagnostic performance of the QuantiFERON-TB Gold assay (QFT-GIT) according to sites of EPTB and predictors for false-negative QFT-GIT results.

METHODS

A total of 2176 patients were registered with active TB from January 2012 to December 2016 in Seoul St. Mary's Hospital, a 1200-bed tertiary teaching hospital in Seoul, Korea. We retrospectively reviewed the medical records of 163 EPTB patients who underwent QFT-GIT.

RESULTS

False negative QFT-GIT results were found in 28.8% (95% CI 0.22-0.36) of patients with EPTB. In the proven TB group, negative QFT-GIT results were found in 28.6% (95% CI 0.04-0.71) of pleural, 8.3% 0.002-0.38of lymph node, 8.3% (95% CI 0.002-0.38) of skeletal and 5.8% (95% CI 0.001-0.28) of gastrointestinal TB cases. Among probable TB cases, QFT-GIT negative results were identified in 46.2% (95% CI 0.19-0.75) of skeletal, 33.3% (95% CI 10-0.65) of pericardial, 30.8% (95% CI 0.09-0.61) of pleural and 17.2% (95% CI 0.10-0.56) of gastrointestinal TB cases. In the possible TB cases, central nervous system TB (n = 21) was most frequent, and 66.7% (95% CI 0.43-0.85) of those showed QFT-GIT negative results. By multivariate analysis, possible TB was independently associated with false-negative QFT-GIT results (OR 4.92, 95% CI 1.51-16.06, p = 0.008).

CONCLUSIONS

Prudent interpretation of QFT-GIT results might be needed according to anatomic site of involvement and diagnostic criteria in patients with high suspicion of EPTB.

Improving network inference: The impact of false positive and false negative conclusions about the presence or absence of links

BACKGROUND

A reliable inference of networks from data is of key interest in the Neurosciences. Several methods have been suggested in the literature to reliably determine links in a network. To decide about the presence of links, these techniques rely on statistical inference, typically controlling the number of false positives, paying little attention to false negatives.

NEW METHOD

In this paper, by means of a comprehensive simulation study, we analyse the influence of false positive and false negative conclusions about the presence or absence of links in a network on the network topology. We show that different values to balance false positive and false negative conclusions about links should be used in order to reliably estimate network characteristics. We propose to run careful simulation studies prior to making potentially erroneous conclusion about the network topology.

RESULTS

Our analysis shows that optimal values to balance false positive and false negative conclusions about links depend on the network topology and characteristic of interest.

COMPARISON WITH EXISTING METHODS

Existing methods rely on a choice of the rate for false positive conclusions. They aim to be sure about individual links rather than the entire network. The rate of false negative conclusions is typically not investigated.

CONCLUSIONS

Our investigation shows that the balance of false positive and false negative conclusions about links in a network has to be tuned for any network topology that is to be estimated. Moreover, within the same network topology, the results are qualitatively the same for each network characteristic, but the actual values leading to reliable estimates of the characteristics are different.

Comparison of GLUT-1, SGLT-1, and SGLT-2 expression in false-negative and true-positive lymph nodes during the 18F-FDG PET/CT mediastinal nodal staging of non-small cell lung cancer

INTRODUCTION

Although positron emission tomography (PET) with 2-deoxy-2-[fluorine-18]fluoro-d-glucose integrated with computed tomography (CT), (¹⁸F-FDG PET/CT), has recently improved the mediastinal nodal staging of non-small cell lung cancer (NSCLC), this method can show false negativity. We immunohistochemically investigated the expression of glucose transporters (GLUT-1, SGLT-1, and SGLT-2) in false negative and true positive mediastinal nodes via ¹⁸F-FDG PET/CT.

METHODS

We investigated patients with clinically-diagnosed N0/pathological N2 diseases and patients with clinically-diagnosed N2/pathological N2 disease. The patients who were included in this study were evaluated using ¹⁸F-FDG PET/CT followed by surgical resection between January 2004 and December 2015. The expression of GLUT-1, SGLT-1, and SGLT-2 in the metastatic mediastinal lymph nodes, and clinicopathological variables such as primary tumor size, lymph node size, histological type, and SUV_max of the primary lesion, were compared between false negative nodes and true positive nodes.

RESULTS

The total number of PET false negative metastatic mediastinal lymph nodes was 22 in the 17 patients who were clinical N0/pathological N2, and the number of PET true positives was 15 in the 11 patients who were clinical N2/pathological N2. GLUT-1 expression was positive in five false negative nodes and 10 true positive nodes. SGLT-2 expression was positive in 12 false negative nodes and one true positive node, whereas both false negative and true positive nodes showed no SGLT-1 staining. Univariate analysis showed that the reduced expression of GLUT-1 (P = 0.015), and overexpression of SGLT-2 (P = 0.004) were the significant causative factors for false negative nodes. Multivariate analysis also showed that the reduced expression of GLUT-1 (P = 0.012) and overexpression of SGLT-2 (P = 0.006) were the significant causative factors for false negative nodes.

CONCLUSION

It suggests that the reduced expression of GLUT-1 and overexpression of SGLT-2 are associated with false-negative lymph node metastases in NSCLC.

Prime detection of Dirofilaria immitis: understanding the influence of blocked antigen on heartworm test performance

Detection of circulating antigen of Dirofilaria immitis has been a mainstay of identifying heartworm infection in clinical practice for the past three decades. Several validated commercial antigen tests have very good sensitivity, specificity, and positive predictive values, especially when used in patients for which heartworm infection is likely. In some dogs and cats infected with heartworm, antigen may not be available for detection although present in the patient sample; heat pretreatment of these samples reveals the antigen, changing the false negative to positive. This phenomenon was documented in the literature in the 1980s but subsequently overlooked by the heartworm research community for many years. In this review, we provide a summary of the current understanding of the role of heat reversal in diagnosing heartworm infection. This additional diagnostic step is most important for patients in which heartworm infection is likely, such as dogs or cats in an endemic area with an inconsistent history of heartworm preventive use, or dogs with a prior diagnosis of heartworm infection that were recently treated. To illustrate the concept, we share a summary of results from canine samples tested at the state veterinary diagnostic laboratory in Oklahoma, USA in 2017 by modified Knott test and by commercial antigen test before and after heat treatment of samples; in this sample set, heat treatment changed all D. immitis microfilaria-positive but antigen-negative samples to antigen-positive. Pet dogs with a history of consistent preventive use are unlikely to become positive with heat pretreatment; for that reason, routine pretreatment of all samples tested in a veterinary practice is not recommended. We also review known causes of false negative and false positive results on heartworm antigen tests that, although uncommon, can complicate accurate diagnosis in individual patients. Together, this review provides a primer to aid understanding of strategies that can enhance accurate diagnosis of heartworm infection in veterinary practice and clinical research.

Bladder cancer diagnosis with CT urography: test characteristics and reasons for false-positive and false-negative results

PURPOSE

To determine test characteristics of CT urography for detecting bladder cancer in patients with hematuria and those undergoing surveillance, and to analyze reasons for false-positive and false-negative results.

METHODS

A HIPAA-compliant, IRB-approved retrospective review of reports from 1623 CT urograms between 10/2010 and 12/31/2013 was performed. 710 examinations for hematuria or bladder cancer history were compared to cystoscopy performed within 6 months. Reference standard was surgical pathology or 1-year minimum clinical follow-up. False-positive and false-negative examinations were reviewed to determine reasons for errors.

RESULTS

Ninety-five bladder cancers were detected. CT urography accuracy: was 91.5% (650/710), sensitivity 86.3% (82/95), specificity 92.4% (568/615), positive predictive value 63.6% (82/129), and negative predictive value was 97.8% (568/581). Of 43 false positives, the majority of interpretation errors were due to benign prostatic hyperplasia (n = 12), trabeculated bladder (n = 9), and treatment changes (n = 8). Other causes include blood clots, mistaken normal anatomy, infectious/inflammatory changes, or had no cystoscopic correlate. Of 13 false negatives, 11 were due to technique, one to a large urinary residual, one to artifact. There were no errors in perception.

CONCLUSION

CT urography is an accurate test for diagnosing bladder cancer; however, in protocols relying predominantly on excretory phase images, overall sensitivity remains insufficient to obviate cystoscopy. Awareness of bladder cancer mimics may reduce false-positive results. Improvements in CTU technique may reduce false-negative results.

Fundamentals of Counting Statistics in Digital PCR: I Just Measured Two Target Copies-What Does It Mean?

Current commercially available digital PCR (dPCR) systems and assays are capable of detecting individual target molecules with considerable reliability. As tests are developed and validated for use on clinical samples, the need to understand and develop robust statistical analysis routines increases. This chapter covers the fundamental processes and limitations of detecting and reporting on single molecule detection. We cover the basics of quantification of targets and sources of imprecision. We describe the basic test concepts: sensitivity, specificity, limit of blank, limit of detection, and limit of quantification in the context of dPCR. We provide basic guidelines how to determine those, how to choose and interpret the operating point, and what factors may influence overall test performance in practice.

A case of placental trisomy 18 mosaicism causing a false negative NIPT result

Background

The non-invasive prenatal testing that evaluates circulating cell free DNA, and has been established as an additional pregnancy test for detecting the common fetal trisomies 21, 18 and 13 is rapidly revolutionizing prenatal screening as a result of its increased sensitivity and specificity. However, false positive and false negative results still exist.

Case presentation

We presented a case in which the non-invasive prenatal testing results were normal at 15 gestational age (GA), but an ultrasound examination at 30GA showed that the fetus had heart abnormalities, and the third trimester ultrasound at 33GA noted multiple anomalies including a 3.0 mm ventricular septal defect. Along with cordocentesis at 33GA, the cord blood sample cytogenetics analysis showed a mos 47,XN,+18[61]/46,XN[39] T18 karyotype. Six placental biopsies confirmed that the chromosome 18 placenta chimerism ratio had changed from 33% to 72%. Ultimately, the pregnancy was interrupted at 34GA.

Conclusions

We presented this case to highlight the need to clearly explain false positive or false negative results to patients. We believe that this information will also influence the development of future diagnostic test methodologies.

Variability and Error in Cardiac Troponin Testing: An ACLPS Critical Review

OBJECTIVES

To provide a comprehensive overview of the complexities associated with cardiac troponin (cTn) testing. An emphasis is placed on the sources of error, organized into the preanalytical, analytical, and postanalytical phases of the testing pathway. Controversial areas are also explored.

METHODS

A case scenario and review of the relevant literature describing laboratory considerations involving cTn testing are described.

RESULTS

Advanced comprehension of the specific assay used in a given laboratory is necessary for optimal reporting, utilization, and quality monitoring of cTn.

CONCLUSIONS

cTn assays are reliable diagnostic tests for acute myocardial infarction, but understanding their limitations is required for appropriate result interpretation.

Characterization of invisible breast cancers in digital mammography and tomosynthesis: radio-pathological correlation

OBJECTIVE

To review the radio-pathologic features of symptomatic breast cancers not detected at digital mammography (DM) and digital breast tomosynthesis (DBT).

MATERIAL AND METHODS

Retrospective analysis of 169 lesions from symptomatic patients with breast cancer that were studied with DM, DBT, ultrasound (US) and magnetic resonance (MR). We identified occult lesions (true false negatives) in DM and DBT. Clinical data, density, US and MR findings were analyzed as well as histopathological results.

RESULTS

We identified seven occult lesions in DM and DBT. 57% (4/7) of the lesions were identified in high-density breasts (type c and d), and the rest of them in breasts of density type b. Six carcinomas were identified at US and MR (BI-RADS 4 masses); the remaining lesion was only identified at MR. The tumor size was larger than 3cm at MRI in 57% of the lesions. All tumors were ductal infiltrating carcinomas, six of them with high stromal proportion. According to molecular classification, we found only one triple-negative breast cancer, the other lesions were luminal-type. We analyzed the tumor margins of two resected carcinomas that were not treated with neoadjuvant chemotherapy, both lesions presented margins that displaced the adjacent parenchyma without infiltrating it.

CONCLUSION

Occult breast carcinomas in DM and DBT accounted for 4% of lesions detected in patients with symptoms. They were mostly masses, all of them presented the diagnosis of infiltrating ductal carcinoma (with predominance of the luminal immunophenotype) and were detected in breasts of density type b, c and d.

Risk Factors for a False-Negative Result of Sentinel Node Biopsy in Patients with Clinically Node-Negative Breast Cancer

Purpose

Although sentinel lymph node biopsy (SLNB) can accurately represent the axillary lymph node (ALN) status, the false-negative rate (FNR) of SLNB is the main concern in the patients who receive SLNB alone instead of ALN dissection (ALND).

Materials and Methods

We analyzed 1,886 patientswho underwent ALND after negative results of SLNB,retrospectively. A logistic regression analysis was used to identify risk factors associated with a falsenegative (FN) result. Cox regression model was used to estimate the hazard ratio of factors affecting disease-free survival (DFS).

Results

Tumor located in the upper outer portion of the breast, lymphovascular invasion, suspicious node in imaging assessment and less than three sentinel lymph nodes (SLNs) were significant independent risk factors for FN in SLNB conferring an adjusted odds ratio of 2.10 (95% confidence interval [CI], 1.30 to 3.39), 2.69 (95% CI, 1.47 to 4.91), 2.59 (95% CI, 1.62 to 4.14), and 2.39 (95% CI, 1.45 to 3.95), respectively. The prognostic factors affecting DFS were tumor size larger than 2 cm (hazard ratio [HR], 1.86; 95% CI, 1.17 to 2.96) and FN of SLNB (HR, 2.51; 95% CI, 1.42 to 4.42) in SLN-negative group (FN and true-negative), but in ALN-positive group (FN and true-positive), FN of SLNB (HR, 0.64; 95% CI, 0.33 to 1.25) did not affect DFS.

Conclusion

In patients with risk factors for a FN such as suspicious node in imaging assessment, upper outer breast cancer, less than three harvested nodes, we need attention to find another metastatic focus in non-SLNs during the operation. It may contribute to provide an exact prognosis and optimizing adjuvant treatments.

A newborn case with carnitine palmitoyltransferase II deficiency initially judged as unaffected by acylcarnitine analysis soon after birth

Carnitine palmitoyltransferase II (CPT-2) deficiency, an autosomal recessive disorder of fatty acid oxidation, can be detected by newborn screening using tandem mass spectrometry (TMS).

Our case was a boy born at 38 weeks and 6 days of gestation via normal vaginal delivery; his elder sister was affected with CPT-2 deficiency. Acylcarnitine (AC) was analyzed in both dried blood spots (DBS) and serum 2 h after birth to determine whether the boy was also affected. His C16 and C18:1 AC levels in DBS were in the normal range, while his serum long-chain AC levels were marginally increased but lower than those of his sister. After the samples were taken, he was treated with glucose infusion to prevent any catabolism for 2 days. On day 4, the long-chain AC levels in both DBS and serum obtained were higher than those on day 0 and were equivalent to those of his sister. Genetic testing confirmed the presence of the same mutation found in his sister, a homozygous F383Y mutation in the CPT2 gene, thus leading to the diagnosis of CPT-2 deficiency.

The sample for TMS should be taken between days 1 and 7. If the sample is not obtained at an appropriate time, correct diagnosis may not be made, as in our case. Although early diagnosis is required, samples taken within 24 h after birth should not be used for TMS.

Shear wave elastography in the diagnosis of breast non-mass lesions: factors associated with false negative and false positive results. Eur Radiol. 2017;27:3788-3798. [PMID: 28168373 DOI: 10.1007/s00330-017-4763-6]

OBJECTIVE

To investigate factors related to false shear wave elastography (SWE) results for breast non-mass lesions (NMLs) detected by B-mode US.

METHODS

This retrospective study enrolled 152 NMLs detected by B-mode US and later pathologically confirmed (79 malignant, 73 benign). All lesions underwent B-mode US and SWE. Quantitative (mean elasticity [E _mean]) and qualitative (maximum stiffness colour) SWE parameters were assessed, and 'E _mean > 85.1 kPa' or 'stiff colour (green to red)' determined malignancy. Final SWE results were matched to pathology results. Multivariate logistic regression analysis identified factors associated with false SWE results for diagnosis of breast NMLs.

RESULTS

Associated calcifications (E _mean: odds ratio [OR] = 7.60, P < 0.01; maximum stiffness colour: OR = 6.30, P = 0.02), in situ cancer compared to invasive cancer (maximum stiffness colour: OR = 5.29, P = 0.02), and lesion size (E _mean: OR = 0.90, P < 0.01; maximum stiffness colour: OR = 0.91, P = 0.01) were significantly associated with false negative SWE results for malignant NMLs. Distance from the nipple (E _mean: OR = 0.84, P = 0.03; maximum stiffness colour: OR = 0.93, P = 0.04) was significantly associated with false positive SWE results for benign NMLs.

CONCLUSIONS

Presence of associated calcifications, absence of the invasive component, and smaller lesion size for malignant NMLs and shorter distance from the nipple for benign NMLs are factors significantly associated with false SWE results.

KEY POINTS

• Calcification and size are associated with false negative SWE in malignant NMLs. • In situ cancer is associated with false negative SWE in malignant NMLs. • Distance from the nipple is associated with false positive SWE in benign NMLs. • These factors need consideration when performing SWE on breast NMLs.

False-positive results in diagnostic immunohistochemistry are related to horseradish peroxidase conjugates in commercially available assays

False-positive results in diagnostic immunopathology can lead to unnecessary treatments. The purpose of this study was to do a side-by-side comparison of 10 different antibodies commonly used in the clinical laboratory altering only the horseradish peroxidase (HRP) conjugate. The automated Leica BOND-MAX platform was used to study serial sections from 203 tissues including controls compared in a blinded fashion using the HRP conjugates from Leica (Refine HRP), Ventana Medical Systems (Ultraview HRP), and Enzo Life Sciences (Polyview HRP). False-positive results, defined as signal from cases known to not contain the target, were noted in 23 (13%) of 171 cases with the Leica HRP, 62 (36%) of 171 cases with the Ventana HRP, and no cases with the Enzo HRP. Each data set was performed simultaneously allocating 1 tray for each of the 3 different HRP conjugates. HER2/neu analysis from triple-negative breast cancers were scored as positive by immunohistochemistry in 6 (24%) of 25 cases using either the Refine or Ultraview HRP and in 0 of 25 cases with the Enzo conjugate. It is concluded that false-positive results in a wide spectrum of diagnostic immunopathology tests can occur from 13% to 36% of cases with commonly used commercial assays based on the HRP conjugate.

False Negative Results in Clostridium difficile Testing

Background

Accurate diagnosis of Clostridium difficile infection (CDI) is paramount for patient management. The wrong diagnosis places patients at risk, delays treatment, and/ or contributes to transmission of infection in the healthcare setting. Although amplification of the toxin B gene by polymerase chain reaction (PCR) is a sensitive method for detecting toxigenic C. difficile, false negative results still occur and could impact the diagnosis and treatment of this infection.

Methods

This study investigated 48 patients that tested negative for toxigenic C. difficile via GeneXpert C. difficile epi test, while simultaneously testing positive for toxigenic C. difficile via stool culture. Fifty discrepant samples were collected over a 15-month period and all C. difficile isolates were characterized by ribotype. Patient charts were reviewed to assess whether discrepant results impacted the treatment course or clinical outcome of affected patients.

Results

Fifty samples of a total of 2308 samples tested in an acute healthcare facility over a 15-month period had negative PCR and positive stool culture for toxigenic C. difficile. C. difficile isolated from the discrepant samples resulted in diverse ribotyping patterns suggesting they were derived from different strains. The samples belonged to patients who were distributed evenly between age groups and wards in the hospital. In the majority of cases, the false negative C. difficile test results did not seem to impact the clinical outcome in these patients.

Conclusions

The PCR limit of detection may impact the results of molecular methods for C. difficile detection. Both clinical and analytical sensitivity of C. difficile tests should be considered when deciding which diagnostic assay to use, and clinical correlates should be examined carefully before excluding CDI as a cause of disease.

What Is a False Negative Sentinel Node Biopsy: Definition, Reasons and Ways to Minimize It?

Sentinel node biopsy helps in assessing the involvement of axillary lymph node without the morbidity of full axillary lymph node dissection, namely arm and shoulder pain, paraesthesia and lymphoedema. The various methods described in the literature identify the sentinel lymph nodes in approximately 96 % of cases and associated with a false negativity rate of 5 to 10 %. A false negative sentinel node is defined as the proportion of cases in whom sentinel node biopsy is reported as negative, but the rest of axillary lymph node(s) harbours cancer cells. The possible causes of a false negative sentinel lymph node may be because of blocked lymphatics either by cancer cells or following fibrosis of previous surgery/radiotherapy, and an alternative pathway opens draining the blue dye or isotope to another uninvolved node. The other reasons may be two lymphatic pathways for a tumour area, the one opening to a superficial node and the other in deep nodes. Sometimes, lymphatics do not relay into a node but traverse it going to a higher node. In some patients, the microscopic focus of metastasis inside a lymph node is so small-micrometastasis (i.e. between 0.2 and 2 mm) or isolated tumour cells (i.e. less than 0.2 mm) that is missed by the pathologist. The purpose of this review is to clear some fears lurking in the mind of most surgeons about the false negative sentinel lymph node (FNSLN).

Chest Pain with Normal Thallium-201 Myocardial Perfusion Image - Is It Really Normal?

BACKGROUND

Thallium-201 myocardial perfusion image (MPI) is commonly used to detect coronary artery disease in patients with chest pain. Although a normal thallium-201 MPI result is generally considered to be a good prognosis and further coronary angiogram is not recommended, there are still a few patients who suffer from unexpected acute coronary events. The aim of this study was to investigate the clinical prognosis in patients with normal thallium-201 MPI.

METHODS

From January 2006 to August 2012, a total 22,003 patients undergoing thallium-201 MPI in one tertiary center were screened. Of these, 8092 patients had normal results and were investigated retrospectively. During follow-up, 54 patients underwent coronary angiogram because of refractory typical angina pectoris or unexpected acute coronary events. These 54 patients were divided into 2 groups: group I consisted of 26 (48.1%) patients with angiography-proven significant coronary artery stenosis, and group II consisted of 28 (51.9%) patients without significant stenosis.

RESULTS

Patients in group I had a higher prevalence of prior coronary stenting and electrocardiographic features of ST depression compared with patients in group II. The multivariate analysis demonstrated that both prior coronary stenting and ST depression were risk predictors of unexpected acute coronary events in the patients with normal thallium-201 MPI [odds ratio (OR), 5.93; 95% confidence interval (CI): 1.03-34.06, p = 0.05 and OR, 7.10; 95% CI: 1.28-39.51, p = 0.03,respectively].

CONCLUSIONS

Although there is a low incidence of unexpected acute coronary events in patients with chest pain and normal thallium-201 MPI, physicians should be aware of the potentials risk in certain patients in this specific population.

A reliable method for avoiding false negative results with Luminex single antigen beads; evidence of the prozone effect

Luminex single antigen bead (SAB) assays have become an essential tool in monitoring the status of antibody to the Human Leucocyte Antigen (HLA) of patients both before and after transplantation. In addition SAB data is used to aid risk stratification to assess immunological risk of humoral rejection in solid organ transplantation (CTAG/BTAG guidelines) [1]. Increasingly laboratories are reporting false negative results at high antibody titre due to a prozone effect. Here we report a case study where the prozone effect led to a false negative antibody result that could have resulted in adverse outcome. We describe a method to reliably remove the prozone effect through heat inactivation and the addition of Ethylenediaminetetraacetic acid (EDTA) to the Luminex wash buffer.

Characterizing urinary hCGβcf patterns during pregnancy

OBJECTIVE

Elevated concentrations of hCG beta core fragment (hCGβcf) are known to cause false-negative results in qualitative urine pregnancy test devices, but the pattern of urinary hCGβcf during normal pregnancy has not been well characterized. Here, we evaluate the relationship between urine hCG, hCGβcf, and hCG free β subunit (hCGβ) during pregnancy.

DESIGN AND METHODS

Banked second trimester urine specimens from 100 pregnant women were screened for high concentrations of hCGβcf using a qualitative point-of-care device known to demonstrate false-negative results in the presence of elevated hCGβcf concentrations. Additional first and third trimester specimens from the same pregnancy were obtained from 10 women who generated negative/faint positive results, 5 women who generated intermediate positive results, and 10 women who generated strong positive results on the point-of-care device. Intact hCG, hCGβcf, hCGβ, and specific gravity were quantified in these 75 specimens.

RESULTS

Urinary hCGβcf concentrations were greater than intact hCG concentrations at all times. A strong correlation (r(2)=0.70) was observed between urine intact hCG and hCGβcf concentrations. A poor correlation was observed between specific gravity and intact hCG (r(2)=0.32), hCGβ (r(2)=0.32), and hCGβcf (r(2)=0.32). The highest hCGβcf concentrations were observed between 10 and 16weeks gestation but individual women demonstrated very different patterns of hCGβcf excretion.

CONCLUSIONS

Urine specimens with elevated hCGβcf are frequently encountered during pregnancy but hCGβcf excretion patterns are unpredictable. Manufacturers and clinicians must appreciate that hCGβcf is the major immunoreactive component in urine during pregnancy and must design and interpret qualitative urine hCG test results accordingly.

Predictors of disagreement between prospectively ECG-triggered dual-source coronary computed tomography angiography and conventional coronary angiography

AIMS

To identify causes of misinterpretation in second generation, dual-source coronary computed tomography angiography (CCTA).

METHODS

A retrospective re-interpretation was performed on 100 consecutive CCTA studies, previously performed with a 2×128 slice dual-source CT. Results were compared with coronary angiography (CA). CCTA and CA images were interpreted by 2 independent readers. At CCTA vessel diameter, image quality, plaque characteristics and localization (bifurcation vs. non) were described for all segments. Finally, aortic contrast-to-noise ratio (CNR) and the total Agatston calcium score were quantified. Agreement between CCTA and CA was assessed with the Kappa statistic after categorizing the stenosis severity at significant (≥50%) and critical (≥70%) cut-offs, and independent predictors of disagreement were determined by multivariable logistic regression, including patient characteristics such as body mass index (BMI), heart rate (HR), age and gender.

RESULTS

Per-segment sensitivity and specificity at ≥50% and ≥70% stenosis was of 83-95%, and 73-97%, respectively. There was a substantial agreement between CCTA and CA (kappa-50%=0.78, SE=0.03; kappa-70%=0.72, SE=0.03). Worse motion-related quality score, smaller vessel diameter, calcification within the segment of interest and LAD location were independent predictors of disagreement at 50% stenosis. The same factors, excluded LAD location, in addition to bifurcation-location of the coronary lesion predicted misdiagnosis at 70% stenosis. HR per se and BMI did not predict disagreement.

CONCLUSION

According to the literature a substantial agreement between CCTA and CA was found. However, discrepancies exist and are mainly related with motion-related degradation of image quality, specific vessel anatomy and plaque characteristics. Awareness of such potential limitations may help guiding interpretation of CCTA.

Sentinel Lymph Node Biopsy After Neoadjuvant Chemotherapy in Patients With an Initial Diagnosis of Cytology-Proven Lymph Node-Positive Breast Cancer

BACKGROUND

Sentinel lymph node biopsy (SNB) is the standard treatment of node-negative breast cancer; however, whether SNB should be performed for patients with node-positive disease before neoadjuvant chemotherapy (NAC) is controversial. We evaluated the accuracy of SNB after NAC in patients with breast cancer with nodal metastasis before chemotherapy to determine the false-negative rate (FNR) and detection rate for SNB.

PATIENTS AND METHODS

In the present multicenter prospective study performed from September 2011 to April 2013, 143 patients with breast cancer and positive axillary nodes, proved by fine needle aspiration cytology at the initial diagnosis (stage T1-T3N1M0), were enrolled. All patients underwent breast surgery with SNB and complete axillary lymph node dissection.

RESULTS

After NAC, the pathologic complete nodal response rate was 52.4%. The sentinel lymph node could be identified in 130 cases (90.9%); the FNR was 16.0% (13 of 81). The FNR of each clinical subtype was 42.1% (8 of 19) for the estrogen receptor-positive and human epithelial growth factor 2 (HER2)-negative (luminal type), 16.7% (2 of 12) for ER-positive and HER2-positive (luminal-HER2 type), 3.2% (1 of 31) for HER2-positive (HER2-enriched type), and 10.5% (2 of 19) for ER-negative and HER2-negative (triple-negative breast cancer; P = .003). The FNR was significantly greater in the luminal than in the nonluminal type (odds ratio, 9.91; 95% confidence interval, 6.77-14.52).

CONCLUSION

SNB after NAC in patients with initially node-positive breast cancer was technically feasible but should not be recommended for the luminal subtype. However, the tumor subtype can guide patient selection, and axillary lymph node dissection could be omitted for the luminal-HER2, HER2-enriched, and triple-negative breast cancer subtypes.

Limitations of recreational camera traps for wildlife management and conservation research: a practitioner's perspective

The availability of affordable 'recreational' camera traps has dramatically increased over the last decade. We present survey results which show that many conservation practitioners use cheaper 'recreational' units for research rather than more expensive 'professional' equipment. We present our perspective of using two popular models of 'recreational' camera trap for ecological field-based studies. The models used (for >2 years) presented us with a range of practical problems at all stages of their use including deployment, operation, and data management, which collectively crippled data collection and limited opportunities for quantification of key issues arising. Our experiences demonstrate that prospective users need to have a sufficient understanding of the limitations camera trap technology poses, dimensions we communicate here. While the merits of different camera traps will be study specific, the performance of more expensive 'professional' models may prove more cost-effective in the long-term when using camera traps for research.

Application of internal standard method in recombinant luminescent bacteria test

Mercury and its organic compounds have been of severe concern worldwide due to their damage to the ecosystem and human health. The development of effective and affordable technology to monitor and signal the presence of bioavailable mercury is an urgent need. The Mer gene is a mercury-responsive resistant gene, and a mercury-sensing recombinant luminescent bacterium using the Mer gene was constructed in this study. The mer operon from marine Pseudomonas putida strain SP1 was amplified and fused with prompterless luxCDABE in the pUCD615 plasmid within Escherichia coli cells, resulting in pTHE30-E. coli. The recombinant strain showed high sensitivity and specificity. The detection limit of Hg(2+) was 5nmol/L, and distinct luminescence could be detected in 30min. Cd(2+), Cu(2+), Zn(2+), Ca(2+), Pb(2+), Mg(2+), Mn(2+), and Al(3+) did not interfere with the detection over a range of 10(-5)-1mM. Application of recombinant luminescent bacteria testing in environmental samples has been a controversial issue: especially for metal-sensing recombinant strains, false negatives caused by high cytotoxicity are one of the most important issues when applying recombinant luminescent bacteria in biomonitoring of heavy metals. In this study, by establishing an internal standard approach, the false negative problem was overcome; furthermore, the method can also help to estimate the suspected mercury concentration, which ensures high detection sensitivity of bioavailable Hg(2+).

Reliability of frontal sinus by cone beam-computed tomography (CBCT) for individual identification

Analysis of the frontal sinus is an important tool in personal identification. Cone beam-computed tomography (CBCT) is also progressively replacing conventional radiography and multi-slice computed tomography (MSCT) in human identification. The aim of this study is to develop a reproducible technique and measurements from 3D reconstructions obtained with CBCT, for use in human identification. CBCT from 150 patients (91 female, 59 male), aged between 15 and 78 years, was analysed with the specific software program MIMICS 11.11 (Materialise N.V., Leuven, Belgium). Corresponding 3D volumes were generated and maximal dimensions along 3 directions (x, y, z), X M, Y M, Z M (in mm), total volume area (in mm(3)), V t, and total surface (in mm(2)), S t, were calculated. Correlation analysis showed that sinus surfaces were strongly correlated with their volume (r = 0.976). Frontal sinuses were separate in 21 subjects (14 %), fused in 67 (44.6 %) and found on only one side (unilateral) in 9 (6 %). A Prominent Middle of Fused Sinus (PMS) was found in 53 subjects (35.3 %). The intra- (0.963-0.999) and inter-observer variability (0.973-0.999) showed a great agreement and a substantial homogeneity of evaluation.

Evaluation of a semi-quantitative pregnancy device for susceptibility to interference caused by hCGβcf

OBJECTIVE

Previous work has documented the ability of the Clearblue Advanced Test with Weeks Estimator, a new over-the-counter (OTC) urine hCG device, to accurately estimate weeks since ovulation in early pregnancy. In this study, the performance of this device in more advanced pregnancy was assessed.

METHODS

The Clearblue Advanced Test with Weeks Estimator device was used to test solutions containing purified intact hCG and hCGβcf at concentrations consistent with early, middle and late pregnancy. Urine samples from three normal pregnant patients 9-13 weeks of gestation and from a patient 12 weeks of gestation known to generate false negative results on qualitative urine test devices due to excess hCGβcf were also evaluated.

RESULTS

The Clearblue Weeks Estimator device gave expected results using solutions containing purified intact hCG and hCGβcf at concentrations observed throughout pregnancy. The device generated expected results using urine from three of four patients tested between 9 and 13 weeks of gestation. However, when urine from a patient with elevated concentrations of hCGβcf was used, the device correctly indicated pregnancy although the estimate for the date was incorrect.

CONCLUSION

This device gave expected "pregnant" results using all samples tested. However, the "Weeks Estimator" should be interpreted with caution when used by patients after seven weeks of pregnancy.

Simple solutions to false results with plate/slide agglutination tests in diagnosis of infectious diseases of man and animals

We have developed a new Superagglutination test for serodiagnosis of infectious diseases. It differs from conventional plate/slide agglutination tests (PAT/SAT) by three additional steps: prior staining of serum antibody by adding a dye and addition of diluted biotinylated antiglobulin and avidin in sequence after mixing the antigen with the test serum. The new steps circumvent the problems of false positive and false negative results of PAT/SAT. In serodiagnosis of brucellosis, Superagglutination test had higher positive predictive value and specificity than Rose Bengal Plate Test (RBPT) and Standard Tube Agglutination Test (STAT) and higher negative predictive value and sensitivity than RBPT, STAT, ELISA and Complement Fixation Test (CFT).•Superagglutination is a simple, accurate and economic screening test for infections.•More specificity, sensitivity, positive & negative predictive value than RBPT, STAT.•More sensitivity, negative predictive value than ELISA and Complement Fixation Test.

Analytical sensitivity of four commonly used hCG point of care devices

BACKGROUND

Point of care (POC) hCG assays are often used to rule-out pregnancy and therefore diagnostic sensitivity, especially at low concentrations of hCG, is important. There are very few studies in the literature that seek to verify the claimed analytical sensitivity of hCG POC devices.

METHODS

The analytical sensitivity of four commonly used hCG POC devices (Alere hCG Combo Cassette, ICON 20 hCG, OSOM hCG Combo Test, and Sure-Vue Serum/Urine hCG-STAT) was challenged using urine samples (n=50) selected based on quantitative hCG concentrations. The majority of these specimens (n=40) had an hCG concentration between 20 and 200 U/L. Each specimen/device combination was reviewed by three individuals. Statistical calculations were performed using Stata 12.

RESULTS

The analytical sensitivity of the OSOM was significantly lower inferior than that of the other POC devices. There was no significant difference in the sensitivity of the Alere, ICON 20 and Sure-Vue devices. There was no significant difference in the individual interpretation of the hCG POC results.

CONCLUSIONS

All hCG POC devices evaluated in this study were susceptible to false negative results at low concentrations of urine hCG. Laboratorians and clinicians should be aware that there are limitations when using urine hCG POC devices to rule out early pregnancy.

Determinants of false-negative results in non-small-cell lung cancer staging by endobronchial ultrasound-guided needle aspiration

OBJECTIVES

False-negative results of endobronchial ultrasound-guided transbronchial needle aspiration in non-small-cell lung cancer staging have shown significant variability in previous studies. The aim of this study was to identify procedure- and tumour-related determinants of endobronchial ultrasound-guided transbronchial needle aspiration false-negative results.

METHODS

We conducted a prospective study that included non-small-cell lung cancer patients staged as N0/N1 by endobronchial ultrasound-guided transbronchial needle aspiration and undergoing therapeutic surgery. The frequency of false-negative results in the mediastinum was calculated. Procedure-related, first, and tumour-related, second, determinants of false-negative results in stations reachable and non-reachable by endobronchial ultrasound were determined by multivariate logistic regression.

RESULTS

False-negative endobronchial ultrasound-guided transbronchial needle aspiration results were identified in 23 of 165 enrolled patients (13.9%), mainly in stations reachable by endobronchial ultrasound (17 cases, 10.3%). False-negative results were related to the extensiveness of endobronchial ultrasound sampling: their prevalence was low (2.4%) when sampling of three mediastinal stations was satisfactory, but rose above 10% when this requirement was not fulfilled (P = 0.043). In the multivariate analysis, abnormal mediastinum on computer tomography/positron emission tomography [odds ratio (OR) 7.77, 95% confidence interval (CI) 2.19-27.51, P = 0.001] and extensiveness of satisfactory sampling of mediastinal stations (OR 0.37, 95% CI 0.16-0.89, P = 0.026) were statistically significant risk factors for false-negative results in stations reachable by endobronchial ultrasound. False-negative results in non-reachable nodes were associated with a left-sided location of the tumour (OR 10.11, 95% CI 1.17-87.52, P = 0.036).

CONCLUSIONS

The presence of false-negative ultrasound-guided transbronchial needle aspiration results were observed in nearly 15% of non-small-cell lung cancer patients but in only 3% when satisfactory samples were obtained from three mediastinal stations. False-negative results in stations reachable by endobronchial ultrasound were associated with the extensiveness of sampling, and in stations out of reach of endobronchial ultrasound with left-sided tumours. These results suggest that satisfactory sampling of at least three mediastinal stations by EBUS-TBNA may be a quality criterion to be recommended for EBUS-TBNA staging.

Innovative modifications to Rose Bengal plate test enhance its specificity, sensitivity and predictive value in the diagnosis of brucellosis

Current agglutination tests occasionally yield false results. Superagglutination test reduced false results, had higher sensitivity (95.88%) and negative predictive value (95.83%) than Rose Bengal plate test (RBPT), Standard Tube Agglutination test (STAT), ELISA, and Complement Fixation test and specificity (89.32%) and positive predictive value (89.42%) higher than RBPT and STAT.

The effect of information about false negative and false positive rates on people's attitudes towards colorectal cancer screening using faecal occult blood testing (FOBt)

OBJECTIVE

To examine the impact of numeric risk information about false negative (FN) and false positive (FP) rates in faecal occult blood testing (FOBt) on attitudes towards screening.

METHODS

95 people aged 45-59, living in England, read 6 hypothetical vignettes presented online about the use of FOB testing to detect bowel cancer, in which information about FN and FP rates was systematically varied.

RESULTS

Both verbal and numeric FN risk information reduced people's interest in screening compared with no FN information. Numeric FN risk information reduced people's perceptions of screening effectiveness and lowered perceived trust in the results of screening compared with both verbal FN information and no FN information. FP information did not affect attitudes towards FOB testing. There was limited evidence that FN information reduced interest and perceptions of screening effectiveness more in educated groups.

CONCLUSION

Numeric FN risk information decreased people's perceptions of screening effectiveness and trust in the results of screening but did not affect people's interest in screening anymore than verbal FN risk information.

PRACTICE IMPLICATIONS

Numeric FN information could be added to patient information without affecting interest in screening, although this needs to be replicated in a larger, more representative sample.

Novel spot tests for detecting the presence of zinc sulfate in urine, a newly introduced urinary adulterant to invalidate drugs of abuse testing

OBJECTIVES

To find a suitable method for detecting zinc sulfate in adulterated urine.

METHODS

Two rapid spot tests to detect the presence of zinc sulfate in urine were developed.

RESULTS

Addition of 3 to 4 drops of 1N sodium hydroxide solution to approximately 1 mL of urine containing zinc sulfate led to the formation of a white precipitate, which was soluble in excess sodium hydroxide. In the second spot test, addition of 3 to 4 drops of 1% sodium chromate solution to 1 mL of urine containing zinc sulfate followed by the addition of 4 to 5 drops of 1N sodium hydroxide led to formation of a yellow precipitate (zinc chromate). Detection limit of these visual spot tests was 10 mg/mL of zinc sulfate in urine. Twenty drug-free urine specimens and urine containing high amounts of sugar or reducing substances were tested with no false-positive spot test results observed. However, if lead is present in high amounts in urine, it may cause false-positive spot test results. When aliquots of urine controls for drugs of abuse testing were supplemented with different amounts of zinc sulfate, false-negative drug test results were observed except for amphetamine. Zinc sulfate also falsely reduced measured urine alcohol level in urine.

CONCLUSIONS

Zinc sulfate can invalidate urine drug and alcohol testing but can be detected using the novel spot tests developed.