WorldWideScience

Sample records for imaging false-positive study

  1. In-111-labeled leukocyte imaging: false-positive study due to acute gastrointestinal bleeding

    International Nuclear Information System (INIS)

    Fisher, M.F.; Rudd, T.G.

    1983-01-01

    A case is reported in which In-111-labeled leukocytes accumulated in the left colon on a 24-hr delayed image. This was found to be secondary to an upper gastrointestinal bleed in progress at the time of injection of the radiolabeled leukocytes

  2. False positive paediatric labelled white blood cell study

    International Nuclear Information System (INIS)

    Beveridge, N.; Bennett, E.; Thomas, P.

    2002-01-01

    Full text: An eight-month-old female presented for a technetium labelled white blood cell study (LWBC) to exclude an intra-abdominal abscess. Born premature, the child had surgery to repair a perforated bowel and had repeated presentations with diarrhoea, fevers, a tender right upper quadrant and a raised leucocyte count. Multiple imaging modalities failed to demonstrate recurrent bowel perforation, ischaemia or an intra-abdominal mass. A LWBC study was performed with whole body imaging at 1 and 5 hours post re-injection of the radiolabelled blood. No abnormal uptake was visualised in the abdomen but abnormal white cell accumulation was noted in the right hind foot and the length of the right lower leg. This activity appeared to lie along the course of the right tibia. Plain X-ray demonstrated no evidence of tibial osteomyelitis. Concern that the LWBC may be falsely negative in a patient on antibiotics, a gallium scan was immediately performed to re-examine the abdomen. The whole body gallium images demonstrated normal physiological uptake in the abdomen and no evidence of infection in the right leg. The patient had no clinical features to support right leg pathology. The abnormal LWBC localisation in the right lower leg/foot was therefore falsely positive. The most likely explanation is increased activation of the autologous LWBC by 'rough' handling during difficult venesection and re-injection through small veins and needles/cannulas. The slow flow through the veins draining the foot injection site would contribute to margination in these vessel walls. This is a potential cause for false positive LWBC studies- with significant implications for patient care. Copyright (2002) The Australian and New Zealand Society of Nuclear Medicine Inc

  3. Reduction of false-positive recalls using a computerized mammographic image feature analysis scheme

    Science.gov (United States)

    Tan, Maxine; Pu, Jiantao; Zheng, Bin

    2014-08-01

    The high false-positive recall rate is one of the major dilemmas that significantly reduce the efficacy of screening mammography, which harms a large fraction of women and increases healthcare cost. This study aims to investigate the feasibility of helping reduce false-positive recalls by developing a new computer-aided diagnosis (CAD) scheme based on the analysis of global mammographic texture and density features computed from four-view images. Our database includes full-field digital mammography (FFDM) images acquired from 1052 recalled women (669 positive for cancer and 383 benign). Each case has four images: two craniocaudal (CC) and two mediolateral oblique (MLO) views. Our CAD scheme first computed global texture features related to the mammographic density distribution on the segmented breast regions of four images. Second, the computed features were given to two artificial neural network (ANN) classifiers that were separately trained and tested in a ten-fold cross-validation scheme on CC and MLO view images, respectively. Finally, two ANN classification scores were combined using a new adaptive scoring fusion method that automatically determined the optimal weights to assign to both views. CAD performance was tested using the area under a receiver operating characteristic curve (AUC). The AUC = 0.793  ±  0.026 was obtained for this four-view CAD scheme, which was significantly higher at the 5% significance level than the AUCs achieved when using only CC (p = 0.025) or MLO (p = 0.0004) view images, respectively. This study demonstrates that a quantitative assessment of global mammographic image texture and density features could provide useful and/or supplementary information to classify between malignant and benign cases among the recalled cases, which may eventually help reduce the false-positive recall rate in screening mammography.

  4. Image Watermarking Scheme for Specifying False Positive Probability and Bit-pattern Embedding

    Science.gov (United States)

    Sayama, Kohei; Nakamoto, Masayoshi; Muneyasu, Mitsuji; Ohno, Shuichi

    This paper treats a discrete wavelet transform(DWT)-based image watermarking with considering the false positive probability and bit-pattern embedding. We propose an iterative embedding algorithm of watermarking signals which are K sets pseudo-random numbers generated by a secret key. In the detection, K correlations between the watermarked DWT coefficients and watermark signals are computed by using the secret key. L correlations are made available for the judgment of the watermark presence with specified false positive probability, and the other K-L correlations are corresponding to the bit-pattern signal. In the experiment, we show the detection results with specified false positive probability and the bit-pattern recovery, and the comparison of the proposed method against JPEG compression, scaling down and cropping.

  5. Study of false positives in 5-ALA induced photodynamic diagnosis of bladder carcinoma

    Science.gov (United States)

    Draga, Ronald O. P.; Grimbergen, Matthijs C. M.; Kok, Esther T.; Jonges, Trudy G. N.; Bosch, J. L. H. R.

    2009-02-01

    Photodynamic diagnosis (PDD) is a technique that enhances the detection of tumors during cystoscopy using a photosensitizer which accumulates primarily in cancerous cells and will fluoresce when illuminated by violetblue light. A disadvantage of PDD is the relatively low specificity. In this retrospective study we aimed to identify predictors for false positive findings in PDD. Factors such as gender, age, recent transurethral resection of bladder tumors (TURBT), previous intravesical therapy (IVT) and urinary tract infections (UTIs) were examined for association with the false positive rates in a multivariate analysis. Data of 366 procedures and 200 patients were collected. Patients were instilled with 5-aminolevulinic acid (5-ALA) intravesically and 1253 biopsies were taken from tumors and suspicious lesions. Female gender and TURBT are independent predictors of false positives in PDD. However, previous intravesical therapy with Bacille Calmette-Guérin is also an important predictor of false positives. The false positive rate decreases during the first 9-12 weeks after the latest TURBT and the latest intravesical chemotherapy. Although shortly after IVT and TURBT false positives increase, PDD improves the diagnostic sensitivity and results in more adequate treatment strategies in a significant number of patients.

  6. False positive seroreactivity to brucellosis in tuberculosis patients: a prevalence study

    Directory of Open Access Journals (Sweden)

    Mojtaba Varshochi

    2011-03-01

    Full Text Available Mojtaba Varshochi1,2, Jafar Majidi2, Marjan Amini1, Kamyar Ghabili3, Mohammadali M Shoja31Department of Infectious Disease, Tabriz University of Medical Sciences, Tabriz, Iran; 2Infectious Disease and Tropical Medicine Research Center, Tabriz University of Medical Sciences, Tabriz, Iran; 3Tuberculosis and Lung Disease Research Center, Tabriz University of Medical Sciences, Tabriz, IranBackground: The rising worldwide incidence of tuberculosis (TB increases the demand for knowledge about its potential seroreactivity with other microbial agents. A few reports and the authors’ experiences indicate that tuberculosis may result in a false-positive brucellosis serology. This may cause a diagnostic challenge because of the close clinical resemblance of these two infections.Objective: The aim of the present prevalence study was to elucidate brucellosis seroreactivity in patients with active TB.Methods: Ninety-eight patients with newly diagnosed and active TB were studied using an enzyme-linked immunosorbent assay (ELISA and Wright’s and Coombs–Wright’s tests. Seventy-five healthy individuals were used as controls. The patients showed signs of recovery after starting a standard anti-TB regimen and had no clinical evidence of brucellosis at a subsequent 6-month follow-up. The data were analyzed statistically by Fisher’s exact test using SPSS 11.0.Results: We found that 9.2% of TB patients versus 1.3% of healthy controls had positive results on the anti-Brucella IgG ELISA (P = 0.04. Five TB patients were found to have agglutination on Wright’s tests, while none of the controls showed agglutination.Conclusion: Active TB patients may have some seroreactivity with Brucella antigens, and Brucella IgG ELISA may give a false positive in these patients. Clinicians should consider false positive brucellosis seroreactivity in patients with active TB.Keywords: false positive serology, ELISA, diagnosis

  7. Mammography Clinical Image Quality and the False Positive Rate in a Canadian Breast Cancer Screening Program.

    Science.gov (United States)

    Guertin, Marie-Hélène; Théberge, Isabelle; Zomahoun, Hervé Tchala Vignon; Dufresne, Michel-Pierre; Pelletier, Éric; Brisson, Jacques

    2018-05-01

    The study sought to determine if mammography quality is associated with the false positive (FP) rate in the Quebec breast cancer screening program in 2004 and 2005. Mammography quality of a random sample of screen-film mammograms was evaluated by an expert radiologist following the criteria of the Canadian Association of Radiologists. For each screening examination, scores ranging from 1 (poor quality) to 5 (excellent quality) were attributed for positioning, compression, contrast, exposure level, sharpness, and artifacts. A final overall quality score (lower or higher) was also given. Poisson regression models with robust estimation of variance and adjusted for potential confounding factors were used to assess associations of mammography quality with the FP rate. Among 1,209 women without cancer, there were 104 (8.6%) FPs. Lower overall mammography quality is associated with an increase in the FP rate (risk ratio [RR], 1.4; 95% confidence interval [CI], 1.0-2.1; P = .07) but this increase was not statistically significant. Artifacts were associated with an increase in the FP rate (RR, 2.1; 95% CI, 1.3-3.3; P = .01) whereas lower quality of exposure level was related to a reduction of the FP rate (RR, 0.4; 95% CI, 0.1-1.0; P = .01). Lower quality scores for all other quality attributes were related to a nonstatistically significant increase in the FP rate of 10%-30%. Artifacts can have a substantial effect on the FP rate. The effect of overall mammography quality on the FP rate may also be substantial and needs to be clarified. Copyright © 2017 Canadian Association of Radiologists. Published by Elsevier Inc. All rights reserved.

  8. False Positives in Exoplanet Detection

    Science.gov (United States)

    Leuquire, Jacob; Kasper, David; Jang-Condell, Hannah; Kar, Aman; Sorber, Rebecca; Suhaimi, Afiq; KELT (Kilodegree Extremely Little Telescope)

    2018-06-01

    Our team at the University of Wyoming uses a 0.6 m telescope at RBO (Red Buttes Observatory) to help confirm results on potential exoplanet candidates from low resolution, wide field surveys shared by the KELT (Kilodegree Extremely Little Telescope) team. False positives are common in this work. We carry out transit photometry, and this method comes with special types of false positives. The most common false positive seen at the confirmation level is an EB (eclipsing binary). Low resolution images are great in detecting multiple sources for photometric dips in light curves, but they lack the precision to decipher single targets at an accurate level. For example, target star KC18C030621 needed RBO’s photometric precision to determine there was a nearby EB causing exoplanet type light curves. Identifying false positives with our telescope is important work because it helps eliminate the waste of time taken by more expensive telescopes trying to rule out negative candidate stars. It also furthers the identification of other types of photometric events, like eclipsing binaries, so they can be studied on their own.

  9. Pathways to false-positive diagnoses using molecular genetic detection methods; Phytophthora cinnamomi a case study.

    Science.gov (United States)

    Kunadiya, Manisha; White, Diane; Dunstan, William A; Hardy, Giles E St J; Andjic, Vera; Burgess, Treena I

    2017-04-01

    Phytophthora cinnamomi is one of the world's most invasive plant pathogens affecting ornamental plants, horticultural crops and natural ecosystems. Accurate diagnosis is very important to determine the presence or absence of this pathogen in diseased and asymptomatic plants. In previous studies, P. cinnamomi species-specific primers were designed and tested using various polymerase chain reaction (PCR) techniques including conventional PCR, nested PCR and quantitative real-time PCR. In all cases, the primers were stated to be highly specific and sensitive to P. cinnamomi. However, few of these studies tested their primers against closely related Phytophthora species (Phytophthora clade 7). In this study, we tested these purported P. cinnamomi-specific primer sets against 11 other species from clade 7 and determined their specificity; of the eight tested primer sets only three were specific to P. cinnamomi. This study demonstrated the importance of testing primers against closely related species within the same clade, and not just other species within the same genus. The findings of this study are relevant to all species-specific microbial diagnosis. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  10. False Position, Double False Position and Cramer's Rule

    Science.gov (United States)

    Boman, Eugene

    2009-01-01

    We state and prove the methods of False Position (Regula Falsa) and Double False Position (Regula Duorum Falsorum). The history of both is traced from ancient Egypt and China through the work of Fibonacci, ending with a connection between Double False Position and Cramer's Rule.

  11. Uptake of 131-I in maxillary bones mimicking salivary glands. False- positive images in patients with differentiated thyroid carcinoma (DTC )

    International Nuclear Information System (INIS)

    Degrossi, Osvaldo J.; Degrossi, E.B.; Levi de Cabrejas, Mariana

    2008-01-01

    In the whole body scans (WBS) with 131-I in the follow-up or treatment of patients bearing DTC it is observed frequently fixation areas of the tracer apparently in relation with salivary glands. These areas generally belong to the salivary glands and are present during the first 48/72 hours, but others are kept during more than 3 weeks. These latter ones were considered as possible uptake in ectopic thyroid cells in the mouth floor, iodized proteins, retention of salivary glands and other assertions. Valdivieso et al. (Cong. Arg. Biol. Med. Nuclear, 1996) and Gutierrez et al. (SLAT,Chile, 1997) considered that the fixation took place also in maxillary bones probably in areas in relation with dental illness (inflammation, pulpitis, dental caries, perionditis, periapical granuloma, periapical cyst and resorption of surrounding bone seen radiologically as periapical radiolucency). This presumption was sustained for two publications (Clin. Nucl. Med. 1998;23. 747-749, and Clin. Nucl. Med. 2000; 23; 314-315). This end the review of 638 131-I WBS carried out between January 1st, 2002 and December 31st of 2007 in 502 patients that were studied for ablation, treatment of metastasis or relapses or follow up. In 31,5% of the patients were observed areas of activity in maxilla. The intensity of concentration of the tracer was 0.3 to 1.2 % of the activity administered. In 10 patients was determinate the effective T 1/2 and in 5 a panoramic Rx of the maxilla and a bone scintigraphy with 99m-Tc-MDP; there were correlation between both images, the 131-I one an the 99m-Tc-MDP with radiology. The effective T 1/2 mean value was 6,87 days ± 0,94 (S.D.) very close to the physical T 1/2 of the radioiodine tracer indicating a strongly labeled molecule. In 6 patients treated with high activities of radioiodine (5,55 to 11,1 MBq - 150 to 300 mCi) actinic lesions were observed in mouth and lingual mucous membrane, including ulcers. The intensity of the images and of the lesions correlate

  12. False Positive Stress Testing: Does Endothelial Vascular Dysfunction Contribute to ST-Segment Depression in Women? A Pilot Study.

    Science.gov (United States)

    Sharma, Shilpa; Mehta, Puja K; Arsanjani, Reza; Sedlak, Tara; Hobel, Zachary; Shufelt, Chrisandra; Jones, Erika; Kligfield, Paul; Mortara, David; Laks, Michael; Diniz, Marcio; Bairey Merz, C Noel

    2018-06-19

    The utility of exercise-induced ST-segment depression for diagnosing ischemic heart disease (IHD) in women is unclear. Based on evidence that IHD pathophysiology in women involves coronary vascular dysfunction, we hypothesized that coronary vascular dysfunction contributes to exercise electrocardiography (Ex-ECG) ST-depression in the absence of obstructive CAD, so-called "false positive" results. We tested our hypothesis in a pilot study evaluating the relationship between peripheral vascular endothelial function and Ex-ECG. Twenty-nine asymptomatic women without cardiac risk factors underwent maximal Bruce protocol exercise treadmill testing and peripheral endothelial function assessment using peripheral arterial tonometry (Itamar EndoPAT 2000) to measure reactive hyperemia index (RHI). The relationship between RHI and Ex-ECG ST-segment depression was evaluated using logistic regression and differences in subgroups using two-tailed t-tests. Mean age was 54 ± 7 years, body mass index 25 ± 4 kg/m 2 , and RHI 2.51 ± 0.66. Three women (10%) had RHI less than 1.68, consistent with abnormal peripheral endothelial function, while 18 women (62%) met criteria for a positive Ex-ECG based on ST-segment depression in contiguous leads. Women with and without ST-segment depression had similar baseline and exercise vital signs, metabolic equivalents (METS) achieved, and RHI (all p>0.05). RHI did not predict ST-segment depression. Our pilot study demonstrates a high prevalence of exercise-induced ST-segment depression in asymptomatic, middle-aged, overweight women. Peripheral vascular endothelial dysfunction did not predict Ex-ECG ST-segment depression. Further work is needed to investigate the utility of vascular endothelial testing and Ex-ECG for IHD diagnostic and management purposes in women. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  13. Automated detection of pulmonary nodules in PET/CT images: Ensemble false-positive reduction using a convolutional neural network technique

    Energy Technology Data Exchange (ETDEWEB)

    Teramoto, Atsushi, E-mail: teramoto@fujita-hu.ac.jp [Faculty of Radiological Technology, School of Health Sciences, Fujita Health University, 1-98 Dengakugakubo, Kutsukake, Toyoake, Aichi 470-1192 (Japan); Fujita, Hiroshi [Department of Intelligent Image Information, Division of Regeneration and Advanced Medical Sciences, Graduate School of Medicine, Gifu University, 1-1 Yanagido, Gifu 501-1194 (Japan); Yamamuro, Osamu; Tamaki, Tsuneo [East Nagoya Imaging Diagnosis Center, 3-4-26 Jiyugaoka, Chikusa-ku, Nagoya, Aichi 464-0044 (Japan)

    2016-06-15

    Purpose: Automated detection of solitary pulmonary nodules using positron emission tomography (PET) and computed tomography (CT) images shows good sensitivity; however, it is difficult to detect nodules in contact with normal organs, and additional efforts are needed so that the number of false positives (FPs) can be further reduced. In this paper, the authors propose an improved FP-reduction method for the detection of pulmonary nodules in PET/CT images by means of convolutional neural networks (CNNs). Methods: The overall scheme detects pulmonary nodules using both CT and PET images. In the CT images, a massive region is first detected using an active contour filter, which is a type of contrast enhancement filter that has a deformable kernel shape. Subsequently, high-uptake regions detected by the PET images are merged with the regions detected by the CT images. FP candidates are eliminated using an ensemble method; it consists of two feature extractions, one by shape/metabolic feature analysis and the other by a CNN, followed by a two-step classifier, one step being rule based and the other being based on support vector machines. Results: The authors evaluated the detection performance using 104 PET/CT images collected by a cancer-screening program. The sensitivity in detecting candidates at an initial stage was 97.2%, with 72.8 FPs/case. After performing the proposed FP-reduction method, the sensitivity of detection was 90.1%, with 4.9 FPs/case; the proposed method eliminated approximately half the FPs existing in the previous study. Conclusions: An improved FP-reduction scheme using CNN technique has been developed for the detection of pulmonary nodules in PET/CT images. The authors’ ensemble FP-reduction method eliminated 93% of the FPs; their proposed method using CNN technique eliminates approximately half the FPs existing in the previous study. These results indicate that their method may be useful in the computer-aided detection of pulmonary nodules

  14. Automated detection of pulmonary nodules in PET/CT images: Ensemble false-positive reduction using a convolutional neural network technique

    International Nuclear Information System (INIS)

    Teramoto, Atsushi; Fujita, Hiroshi; Yamamuro, Osamu; Tamaki, Tsuneo

    2016-01-01

    Purpose: Automated detection of solitary pulmonary nodules using positron emission tomography (PET) and computed tomography (CT) images shows good sensitivity; however, it is difficult to detect nodules in contact with normal organs, and additional efforts are needed so that the number of false positives (FPs) can be further reduced. In this paper, the authors propose an improved FP-reduction method for the detection of pulmonary nodules in PET/CT images by means of convolutional neural networks (CNNs). Methods: The overall scheme detects pulmonary nodules using both CT and PET images. In the CT images, a massive region is first detected using an active contour filter, which is a type of contrast enhancement filter that has a deformable kernel shape. Subsequently, high-uptake regions detected by the PET images are merged with the regions detected by the CT images. FP candidates are eliminated using an ensemble method; it consists of two feature extractions, one by shape/metabolic feature analysis and the other by a CNN, followed by a two-step classifier, one step being rule based and the other being based on support vector machines. Results: The authors evaluated the detection performance using 104 PET/CT images collected by a cancer-screening program. The sensitivity in detecting candidates at an initial stage was 97.2%, with 72.8 FPs/case. After performing the proposed FP-reduction method, the sensitivity of detection was 90.1%, with 4.9 FPs/case; the proposed method eliminated approximately half the FPs existing in the previous study. Conclusions: An improved FP-reduction scheme using CNN technique has been developed for the detection of pulmonary nodules in PET/CT images. The authors’ ensemble FP-reduction method eliminated 93% of the FPs; their proposed method using CNN technique eliminates approximately half the FPs existing in the previous study. These results indicate that their method may be useful in the computer-aided detection of pulmonary nodules

  15. An analysis of true- and false-positive results of vocal fold uptake in positron emission tomography-computed tomography imaging.

    Science.gov (United States)

    Seymour, N; Burkill, G; Harries, M

    2018-03-01

    Positron emission tomography-computed tomography with fluorine-18 fluorodeoxy-D-glucose has a major role in the investigation of head and neck cancers. Fluorine-18 fluorodeoxy-D-glucose is not a tumour-specific tracer and can also accumulate in benign pathology. Therefore, positron emission tomography-computed tomography scan interpretation difficulties are common in the head and neck, which can produce false-positive results. This study aimed to investigate patients detected as having abnormal vocal fold uptake on fluorine-18 fluorodeoxy-D-glucose positron emission tomography-computed tomography. Positron emission tomography-computed tomography scans were identified over a 15-month period where reports contained evidence of unilateral vocal fold uptake or vocal fold pathology. Patients' notes and laryngoscopy results were analysed. Forty-six patients were identified as having abnormal vocal fold uptake on positron emission tomography-computed tomography. Twenty-three patients underwent positron emission tomography-computed tomography and flexible laryngoscopy: 61 per cent of patients had true-positive positron emission tomography-computed tomography scans and 39 per cent had false-positive scan results. Most patients referred to ENT for abnormal findings on positron emission tomography-computed tomography scans had true-positive findings. Asymmetrical fluorine-18 fluorodeoxy-D-glucose uptake should raise suspicion of vocal fold pathology, accepting a false-positive rate of approximately 40 per cent.

  16. The false positive exercise test

    International Nuclear Information System (INIS)

    Moritani, Kohshiro; Matsuda, Yasuo; Ozaki, Masaharu; Ogawa, Hiroshi; Ichiyama, Masaji; Matsuda, Masako; Kusukawa, Reizo

    1986-01-01

    Exercise tests with sublingual nitroglycerin were performed on 7 patients with true positive and 8 patients with false positive exercise test results. Four of 7 patients with true positive changes and 8 patients with false positive changes underwent exercise cardiac scintigraphy. Scintigrams showed perfusion defects in 4 patients with true positive outcomes, and no perfusion defect in 8 patients with false positive outcomes. Exercise tests with sublingual nitroglycerin were performed with the same load as that without nitroglycerin. In all 7 patients with true positive exercise test results, ST segment depression observed in the control exercise test was not observed in the nitroglycerin exercise test. In the false positive patients, ST segment depression observed in the control exercise test remained unchanged in 7 of 8 patients receiving nitroglycerin. Exercise tests with sublingual nitroglycerin as well as exercise cardiac scintigraphy are valuable tods in differentiating false positive from true positive patients. Furthermore, these data suggest that ST segment depression in the false positive patients may not be related to myocardial ischemia. (author)

  17. Biological false-positive venereal disease research laboratory test in cerebrospinal fluid in the diagnosis of neurosyphilis - a case-control study.

    Science.gov (United States)

    Zheng, S; Lin, R J; Chan, Y H; Ngan, C C L

    2018-03-01

    There is no clear consensus on the diagnosis of neurosyphilis. The Venereal Disease Research Laboratory (VDRL) test from cerebrospinal fluid (CSF) has traditionally been considered the gold standard for diagnosing neurosyphilis but is widely known to be insensitive. In this study, we compared the clinical and laboratory characteristics of true-positive VDRL-CSF cases with biological false-positive VDRL-CSF cases. We retrospectively identified cases of true and false-positive VDRL-CSF across a 3-year period received by the Immunology and Serology Laboratory, Singapore General Hospital. A biological false-positive VDRL-CSF is defined as a reactive VDRL-CSF with a non-reactive Treponema pallidum particle agglutination (TPPA)-CSF and/or negative Line Immuno Assay (LIA)-CSF IgG. A true-positive VDRL-CSF is a reactive VDRL-CSF with a concordant reactive TPPA-CSF and/or positive LIA-CSF IgG. During the study period, a total of 1254 specimens underwent VDRL-CSF examination. Amongst these, 60 specimens from 53 patients tested positive for VDRL-CSF. Of the 53 patients, 42 (79.2%) were true-positive cases and 11 (20.8%) were false-positive cases. In our setting, a positive non-treponemal serology has 97.6% sensitivity, 100% specificity, 100% positive predictive value and 91.7% negative predictive value for a true-positive VDRL-CSF based on our laboratory definition. HIV seropositivity was an independent predictor of a true-positive VDRL-CSF. Biological false-positive VDRL-CSF is common in a setting where patients are tested without first establishing a serological diagnosis of syphilis. Serological testing should be performed prior to CSF evaluation for neurosyphilis. © 2017 European Academy of Dermatology and Venereology.

  18. Gastrointestinal bleeding: an accessory spleen causing a false-positive Tc-99m-sulfur colloid study

    International Nuclear Information System (INIS)

    Heyman, S.; Sunaryo, F.P.; Ziegler, M.M.

    1982-01-01

    A Tc-99m-sulfur colloid abdominal scan was performed on a 12-year-old girl to localize the site of gastrointestinal bleeding. The study was normal. When bleeding recurred two weeks later, a repeat study revealed a focal abnormality in the upper abdomen. This was thought to be compatible with a small bleed. However, at surgery an accessory spleen was found, accounting for the abnormal scan

  19. An investigation of false positive dosimetry results

    International Nuclear Information System (INIS)

    Lewandowski, M.A.; Davis, S.A.; Goff, T.E.; Wu, C.F.

    1996-01-01

    The Waste Isolation Pilot Plant (WIPP) is a facility designed for the demonstration of the safe disposal of transuranic waste. Currently, the radiation source term is confined to sealed calibration and check sources since WIPP has not received waste for disposal. For several years the WIPP Dosimetry Group has operated a Harshaw Model 8800C reader to analyze Harshaw 8801-7776 thermoluminescent cards (3 TLD-700 and 1 TLD-600) with 8805 holder. The frequency of false positive results for quarterly dosimeter exchanges is higher than desired by the Dosimetry Group management. Initial observations suggested that exposure to intense ambient sunlight may be responsible for the majority of the false positive readings for element 3. A study was designed to investigate the possibility of light leaking through the holder and inducing a signal in element 3. This paper discusses the methods and results obtained, with special emphasis placed on recommendations to reduce the frequency of light-induced false positive readings

  20. Image findings of a false positive radioactive iodine-131 uptake mimicking metastasis in pulmonary aspergillosis identified on single photon emission computed tomography-computed tomography

    Directory of Open Access Journals (Sweden)

    Kamaleshwaran Koramadai Karuppusamy

    2015-01-01

    Full Text Available High doses of iodine-131 are commonly used in patients with differentiated thyroid cancer after total or subtotal thyroidectomy, in order to ablate the remaining cancer or normal thyroid tissue. Multiple different false-positive scans can occur in the absence of residual thyroid tissue or metastases. The authors present a case of abnormal uptake of radioactive iodine in the aspergilloma, potentially masquerading as pulmonary metastases.

  1. Female False Positive Exercise Stress ECG Testing - Fact Verses Fiction.

    Science.gov (United States)

    Fitzgerald, Benjamin T; Scalia, William M; Scalia, Gregory M

    2018-03-07

    Exercise stress testing is a well validated cardiovascular investigation. Accuracy for treadmill stress electrocardiograph (ECG) testing has been documented at 60%. False positive stress ECGs (exercise ECG changes with non-obstructive disease on anatomical testing) are common, especially in women, limiting the effectiveness of the test. This study investigates the incidence and predictors of false positive stress ECG findings, referenced against stress echocardiography (SE) as a standard. Stress echocardiography was performed using the Bruce treadmill protocol. False positive stress ECG tests were defined as greater than 1mm of ST depression on ECG during exertion, without pain, with a normal SE. Potential causes for false positive tests were recorded before the test. Three thousand consecutive negative stress echocardiograms (1036 females, 34.5%) were analysed (age 59+/-14 years. False positive (F+) stress ECGs were documented in 565/3000 tests (18.8%). F+ stress ECGs were equally prevalent in females (194/1036, 18.7%) and males (371/1964, 18.9%, p=0.85 for the difference). Potential causes (hypertension, left ventricular hypertrophy, known coronary disease, arrhythmia, diabetes mellitus, valvular heart disease) were recorded in 36/194 (18.6%) of the female F+ ECG tests and 249/371 (68.2%) of the male F+ ECG tests (preinforce the value of stress imaging, particularly in women. Copyright © 2018 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). All rights reserved.

  2. False-positive uptake on 2-[18F]-fluoro-2-deoxy-D-glucose (FDG) positron-emission tomography/computed tomography (PET/CT) in oncological imaging

    International Nuclear Information System (INIS)

    Culverwell, A.D.; Scarsbrook, A.F.; Chowdhury, F.U.

    2011-01-01

    With the increasing utilization of integrated positron-emission tomography/computed tomography (PET/CT) using the glucose analogue 2-[ 18 F]-fluoro-2-deoxy-D-glucose (FDG) in oncological imaging, it is important for radiologists and nuclear medicine physicians to be aware that FDG uptake is not specific for malignancy, as many different physiological variants and benign pathological conditions can also exhibit increased glucose metabolism. Such false-positive FDG uptake often arises outside the area of primary interest and may mimic malignant disease, thereby confounding accurate interpretation of PET/CT studies. With the use of illustrative clinical cases, this article will provide a systematic overview of potential interpretative pitfalls and illustrate how such unexpected findings can be appropriately evaluated.

  3. False-positive image of portal thrombosis with MRI: portal hypertension as a pitfall. Observation in a Budd-Chiari syndrome

    International Nuclear Information System (INIS)

    Davy-Miallou, C.; Bousquet, J.C.; Bellin, M.F.; Guinet, C.; Grellet, J.

    1990-01-01

    This observation illustrates how difficult it is to interpret the intravascular signal observed with MRI in cases of portal hypertension. A signal occupying the entire lumen of the portal trunk and branches can be seen, which is constantly observed in the axial as well as coronal planes in the 3 series studied. It is hypointense relative to the liver on T1-weighted images, hyperintense on T2-weighted images: this appearance therefore perfectly mimicks portal thrombosis. Ultrasound combined with pulsed Doppler demonstrates the stagnant blood within the patent portal system. This kind of artifact, which is produced by a very slow flow or even by the standstill of flow, is much more difficult to recognize than the common flow artifacts; the criteria put forward by various authors to distinguish between artifacts and thrombosis are of no avail in this case. Examinations must able to confirm or rule out portal thrombosis in the case of portal hypertension with deceleration of flow. In practice, ultrasound studies, combined with pulsed Doppler in the best cases, is therefore indicated as a first-intension technique [fr

  4. Likelihood of early detection of breast cancer in relation to false-positive risk in life-time mammographic screening: population-based cohort study.

    Science.gov (United States)

    Otten, J D M; Fracheboud, J; den Heeten, G J; Otto, S J; Holland, R; de Koning, H J; Broeders, M J M; Verbeek, A L M

    2013-10-01

    Women require balanced, high-quality information when making an informed decision on screening benefits and harms before attending biennial mammographic screening. The cumulative risk of a false-positive recall and/or (small) screen-detected or interval cancer over 13 consecutive screening examinations for women aged 50 from the start of screening were estimated using data from the Nijmegen programme, the Netherlands. Women who underwent 13 successive screens in the period 1975-1976 had a 5.3% cumulative chance of a screen-detected cancer, with a 4.2% risk of at least one false-positive recall. The risk of being diagnosed with interval cancer was 3.7%. Two decades later, these estimates were 6.9%, 7.3% and 2.9%, respectively. The chance of detection of a small, favourable invasive breast cancer, anticipating a normal life-expectancy, rose from 2.3% to 3.7%. Extrapolation to digital screening mammography indicates that the proportion of false-positive results will rise to 16%. Dutch women about to participate in the screening programme can be reassured that the chance of false-positive recall in the Netherlands is relatively low. A new screening policy and improved mammography have increased the detection of an early screening carcinoma and lowering the risk of interval carcinoma.

  5. Diagnostic Invasiveness and Psychosocial Consequences of False-Positive Mammography

    DEFF Research Database (Denmark)

    Heleno, Bruno M.; Siersma, Volkert Dirk; Brodersen, John

    2015-01-01

    PURPOSE: We undertook a study to assess whether women with false-positivemammography have worse psychosocial consequences if managed with aworkup that involves a biopsy (invasive group) than if managed with only additional imaging (noninvasive group). METHODS: We performed subgroup analysis...... of a cohort study of 454 womenwith abnormal screening mammography and 908 matched control women withnormal results. Using a condition-specific questionnaire (Consequences of Screening in Breast Cancer), we assessed 12 psychosocial consequences at 5 time points (0, 1, 6, 18, and 36 months after final diagnosis......) and compared the 2 groups of women with false-positives (invasive and noninvasive management groups). RESULTS: Among the 252 women with false-positive mammography eligible forthis study, psychosocial consequences were similar for those managed invasivelyand those managed noninvasively during the 36 months...

  6. Diffusion-weighted imaging (b value = 1500 s/mm(2)) is useful to decrease false-positive breast cancer cases due to fibrocystic changes.

    Science.gov (United States)

    Ochi, Miho; Kuroiwa, Toshiro; Sunami, Shunya; Murakami, Junji; Miyahara, Shinichiro; Nagaie, Takashi; Oya, Masafumi; Yabuuchi, Hidetake; Hatakenaka, Masamitsu

    2013-04-01

    We aimed to evaluate the application of apparent diffusion coefficient (ADC) values calculated from diffusion-weighted imaging (DWI) (b value = 1500 s/mm(2)) in the breast imaging reporting and data system (BI-RADS). For 104 cases of breast lesions with definitive histology diagnosis (45 benign cases, 59 malignant cases) in which breast magnetic resonance imaging was performed, ADC values were compared between benign and malignant cases, between ductal carcinoma in situ (DCIS) and fibrocystic changes, and between DCIS and ductal hyperplasia (one type of fibrocystic change). Diagnostic accuracy was compared for a total of 101 images and for 34 images including only nine DCIS and 25 fibrocystic changes between BI-RADS alone (with categories 4a, 4b, and 5 defined as malignancies) and BI-RADS plus ADC. There were significant differences in mean ADC values between malignant and benign cases (p fibrocystic changes (p fibrocystic changes (40.9% for BI-RADS alone, 64.3% for BI-RADS plus ADC), resulting in a significant improvement in diagnostic accuracy with the addition of ADC. Adding ADC values calculated from DWI (b value = 1500 s/mm(2)) to BI-RADS is a useful way to improve differential diagnostic accuracy for malignant tumors and benign lesions, especially for DCIS versus fibrocystic changes, except in cases of ductal hyperplasia.

  7. False positive acetaminophen concentrations in icteric serum

    Directory of Open Access Journals (Sweden)

    L. de Jong

    2016-04-01

    Full Text Available Introduction: Serum concentrations of acetaminophen are measured to predict the risk of hepatotoxicity in cases of acetaminophen overdose and to identify acetaminophen use in patients with acute liver injury without a known cause. The acetaminophen concentration determines if treatment with N-acetyl cysteine, the antidote for acetaminophen poisoning, is warranted. Description: A 49-year-old woman was admitted to our hospital with a hepatic encephalopathy and a total serum bilirubin concentration of 442 µmol/l. The acetaminophen concentration of 11.5 mg/l was measured with an enzymatic-colorimetric assay, thus treatment with N-acetyl cysteine was started. Interestingly, the acetaminophen concentration remained unchanged (11.5–12.3 mg/l during a period of 4 consecutive days. In contrast, the acetaminophen concentration measured by HPLC, a chromatographic technique, remained undetectable Discussion: In the presented case, elevated bilirubin was the most likely candidate to interfere with acetaminophen assay causing false positive results. Bilirubin has intense absorbance in the ultraviolet and visible regions of the electromagnetic spectrum and for that reason it causes interference in an enzymatic-colorimetric assay. Conclusion: False positive acetaminophen laboratory test results may be found in icteric serum, when enzymatic-colorimetric assays are used for determination of an acetaminophen concentration. Questionable acetaminophen results in icteric serum should be confirmed by a non-enzymatic method, by means of ultrafiltration of the serum, or by dilution studies. Keywords: Acetaminophen, Enzymatic-colorimetric assays, HPLC, Bilirubin, Interference, Paracetamol, Liver failure, Jaundice

  8. Consequences of a false-positive mammography result

    DEFF Research Database (Denmark)

    von Euler-Chelpin, My; Bæksted, Christina; Vejborg, Ilse

    2016-01-01

    group used anxiolytic and antidepressant drugs. There was no difference in use of beta blockers. Hormone therapy was used more frequently by the false-positive, 36.6% versus 28.7%. The proportion of women using anxiolytic and antidepressant drugs increased with 19% from the before to the after period...... in the false-positive group, and with 16% in the normal group, resulting in an RRR of 1.02 (95% CI 0.92-1.14). RRR was 1.03 for beta blockers, 0.97 for hormone therapy. Conclusion(s): Drugs used to mitigate mood disorders were used more frequently by women with false-positive than by women with normal......Background: Previous research showed women experiencing false-positive mammograms to have greater anxiety about breast cancer than women with normal mammograms. To elucidate psychological effects of false-positive mammograms, we studied impact on drug intake.  Methods: We calculated the ratio...

  9. False-positive 111In-pentetreotide Uptake in Gastritis

    International Nuclear Information System (INIS)

    Usmani, Sharjeel; Alshammari, Alshaima

    2013-01-01

    111 In-pentetreotide [ 111 In-octreoscan] is the most widely used radiolabeled somatostatin analog for evaluating neuroendocrine tumor overexpression of somatostatin receptors. False-positives studies of somatostatin receptor scintigraphy have been reported and often the cause is unexplained but assumed to be due to high number of somatostatin receptors in other pathologies. Causes of false-positives include visualization of the gallbladder, nasal mucosa and pulmonary hilar areas in respiratory infections, thyroid abnormalities, accessory spleens, recent Cerebrovascular accidents (CVA's) and activity at the site of a recent surgical incision. In infection or inflammation the cause of false-positive uptake is probably the result of tracer binding by somatostatin receptors on the inflammatory leukocytes. In this case report, we report, a 44-year-old male patient with false-positive 111 In-pentetreotide uptake due to gastritis

  10. Improved first-trimester Down syndrome screening performance by lowering the false-positive rate: a prospective study of 9941 low-risk women

    DEFF Research Database (Denmark)

    Wøjdemann, K R; Shalmi, A C; Christiansen, M

    2005-01-01

    OBJECTIVE: To determine the performance of screening for Down syndrome (DS) and other major chromosomal abnormalities using nuchal translucency (NT), free beta-human chorionic gonadotropin (beta-hCG) and pregnancy-associated plasma protein-A (PAPP-A) in a prospective study of a non...

  11. PET Study with false positive {sup 68}Ga-Dotatate caused by the presence of an accessory spleen; Estudio PET con {sup 68}Ga-Dotatate falso positivo causado por la presencia de un bazo accesorio

    Energy Technology Data Exchange (ETDEWEB)

    Massardo, Teresa [Centro PET de Imagenes Moleculares, Hospital Militar de Santiago / Seccion Medicina Nuclear, Departamento Medicina, Hospital Clinico Universidad de Chile. Santiago (Chile); Jofre, Josefina; Sierralta, M. Paulina; Canessa, Jose [Centro PET de Imagenes Moleculares, Hospital Militar de Santiago. Santiago (Chile)

    2013-05-31

    Neuroendocrine tumors with somatostatin receptor expression are suitable for imaging with somatostatin analogues. {sup 68}Ga-labeled peptides are useful for the diagnosis, staging and assessment of therapeutic response of these tumors. However, for a correct interpretation it is necessary to know the normal biodistribution of somatostatin receptors in the body. Asymmetric adrenal uptake may be a normal variant to cause confusion, or an accessory or ectopic spleen can lead to a false positive result. We report a case of asymmetric adrenal uptake which was correctly considered as a normal variant, but an accessory spleen caused the false impression of being a metastasis from a previously resected primary carcinoid tumor.

  12. Accounting for False Positive HIV Tests: Is Visceral Leishmaniasis Responsible?

    Science.gov (United States)

    Shanks, Leslie; Ritmeijer, Koert; Piriou, Erwan; Siddiqui, M Ruby; Kliescikova, Jarmila; Pearce, Neil; Ariti, Cono; Muluneh, Libsework; Masiga, Johnson; Abebe, Almaz

    2015-01-01

    Co-infection with HIV and visceral leishmaniasis is an important consideration in treatment of either disease in endemic areas. Diagnosis of HIV in resource-limited settings relies on rapid diagnostic tests used together in an algorithm. A limitation of the HIV diagnostic algorithm is that it is vulnerable to falsely positive reactions due to cross reactivity. It has been postulated that visceral leishmaniasis (VL) infection can increase this risk of false positive HIV results. This cross sectional study compared the risk of false positive HIV results in VL patients with non-VL individuals. Participants were recruited from 2 sites in Ethiopia. The Ethiopian algorithm of a tiebreaker using 3 rapid diagnostic tests (RDTs) was used to test for HIV. The gold standard test was the Western Blot, with indeterminate results resolved by PCR testing. Every RDT screen positive individual was included for testing with the gold standard along with 10% of all negatives. The final analysis included 89 VL and 405 non-VL patients. HIV prevalence was found to be 12.8% (47/ 367) in the VL group compared to 7.9% (200/2526) in the non-VL group. The RDT algorithm in the VL group yielded 47 positives, 4 false positives, and 38 negatives. The same algorithm for those without VL had 200 positives, 14 false positives, and 191 negatives. Specificity and positive predictive value for the group with VL was less than the non-VL group; however, the difference was not found to be significant (p = 0.52 and p = 0.76, respectively). The test algorithm yielded a high number of HIV false positive results. However, we were unable to demonstrate a significant difference between groups with and without VL disease. This suggests that the presence of endemic visceral leishmaniasis alone cannot account for the high number of false positive HIV results in our study.

  13. Accounting for False Positive HIV Tests: Is Visceral Leishmaniasis Responsible?

    Directory of Open Access Journals (Sweden)

    Leslie Shanks

    Full Text Available Co-infection with HIV and visceral leishmaniasis is an important consideration in treatment of either disease in endemic areas. Diagnosis of HIV in resource-limited settings relies on rapid diagnostic tests used together in an algorithm. A limitation of the HIV diagnostic algorithm is that it is vulnerable to falsely positive reactions due to cross reactivity. It has been postulated that visceral leishmaniasis (VL infection can increase this risk of false positive HIV results. This cross sectional study compared the risk of false positive HIV results in VL patients with non-VL individuals.Participants were recruited from 2 sites in Ethiopia. The Ethiopian algorithm of a tiebreaker using 3 rapid diagnostic tests (RDTs was used to test for HIV. The gold standard test was the Western Blot, with indeterminate results resolved by PCR testing. Every RDT screen positive individual was included for testing with the gold standard along with 10% of all negatives. The final analysis included 89 VL and 405 non-VL patients. HIV prevalence was found to be 12.8% (47/ 367 in the VL group compared to 7.9% (200/2526 in the non-VL group. The RDT algorithm in the VL group yielded 47 positives, 4 false positives, and 38 negatives. The same algorithm for those without VL had 200 positives, 14 false positives, and 191 negatives. Specificity and positive predictive value for the group with VL was less than the non-VL group; however, the difference was not found to be significant (p = 0.52 and p = 0.76, respectively.The test algorithm yielded a high number of HIV false positive results. However, we were unable to demonstrate a significant difference between groups with and without VL disease. This suggests that the presence of endemic visceral leishmaniasis alone cannot account for the high number of false positive HIV results in our study.

  14. Implications of false-positive results for future cancer screenings.

    Science.gov (United States)

    Taksler, Glen B; Keating, Nancy L; Rothberg, Michael B

    2018-06-01

    False-positive cancer screening results may affect a patient's willingness to obtain future screening. The authors conducted logistic regression analysis of 450,484 person-years of electronic medical records (2006-2015) in 92,405 individuals aged 50 to 75 years. Exposures were false-positive breast, prostate, or colorectal cancer screening test results (repeat breast imaging or negative breast biopsy ≤3 months after screening mammography, repeat prostate-specific antigen [PSA] test ≤3 months after PSA test result ≥4.0 ng/mL or negative prostate biopsy ≤3 months after any PSA result, or negative colonoscopy [without biopsy/polypectomy] ≤6 months after a positive fecal occult blood test). Outcomes were up-to-date status with breast or colorectal cancer screening. Covariates included prior screening history, clinical information (eg, family history, obesity, and smoking status), comorbidity, and demographics. Women were more likely to be up to date with breast cancer screening if they previously had false-positive mammography findings (adjusted odds ratio [AOR], 1.43 [95% confidence interval, 1.34-1.51] without breast biopsy and AOR, 2.02 [95% confidence interval, 1.56-2.62] with breast biopsy; both Pfalse-positive PSA testing were more likely to be up to date with colorectal cancer screening (AOR, 1.22 [P = .039] without prostate imaging/biopsy and AOR, 1.60 [P = .028] with imaging/biopsy). Results were stronger for individuals with more false-positive results (all P≤.005). However, women with previous false-positive colorectal cancer fecal occult blood test screening results were found to be less likely to be up to date with breast cancer screening (AOR, 0.73; Pfalse-positive breast or prostate cancer screening test were more likely to engage in future screening. Cancer 2018;124:2390-8. © 2018 American Cancer Society. © 2018 American Cancer Society.

  15. Evaluation of false positivity and cross reactivity in the investigation ...

    African Journals Online (AJOL)

    This study evaluated the causes of false positive Human Immunodeficiency Virus test results (F+HIV), cross reactivity of HIV antibodies with other non HIV antibodies, and efficiency of the serial and parallel testing algorithms. 100 blood samples randomly collected from clients attending the Heart to Heart HIV counseling and ...

  16. False-positive results in pharmacoepidemiology and pharmacovigilance.

    Science.gov (United States)

    Bezin, Julien; Bosco-Levy, Pauline; Pariente, Antoine

    2017-09-01

    False-positive constitute an important issue in scientific research. In the domain of drug evaluation, it affects all phases of drug development and assessment, from the very early preclinical studies to the late post-marketing evaluations. The core concern associated with this false-positive is the lack of replicability of the results. Aside from fraud or misconducts, false-positive is often envisioned from the statistical angle, which considers them as a price to pay for type I error in statistical testing, and its inflation in the context of multiple testing. If envisioning this problematic in the context of pharmacoepidemiology and pharmacovigilance however, that both evaluate drugs in an observational settings, information brought by statistical testing and the significance of such should only be considered as additional to the estimates provided and their confidence interval, in a context where differences have to be a clinically meaningful upon everything, and the results appear robust to the biases likely to have affected the studies. In the following article, we consequently illustrate these biases and their consequences in generating false-positive results, through studies and associations between drug use and health outcomes that have been widely disputed. Copyright © 2017 Société française de pharmacologie et de thérapeutique. Published by Elsevier Masson SAS. All rights reserved.

  17. Performance quantification of clustering algorithms for false positive removal in fMRI by ROC curves

    Directory of Open Access Journals (Sweden)

    André Salles Cunha Peres

    Full Text Available Abstract Introduction Functional magnetic resonance imaging (fMRI is a non-invasive technique that allows the detection of specific cerebral functions in humans based on hemodynamic changes. The contrast changes are about 5%, making visual inspection impossible. Thus, statistic strategies are applied to infer which brain region is engaged in a task. However, the traditional methods like general linear model and cross-correlation utilize voxel-wise calculation, introducing a lot of false-positive data. So, in this work we tested post-processing cluster algorithms to diminish the false-positives. Methods In this study, three clustering algorithms (the hierarchical cluster, k-means and self-organizing maps were tested and compared for false-positive removal in the post-processing of cross-correlation analyses. Results Our results showed that the hierarchical cluster presented the best performance to remove the false positives in fMRI, being 2.3 times more accurate than k-means, and 1.9 times more accurate than self-organizing maps. Conclusion The hierarchical cluster presented the best performance in false-positive removal because it uses the inconsistency coefficient threshold, while k-means and self-organizing maps utilize a priori cluster number (centroids and neurons number; thus, the hierarchical cluster avoids clustering scattered voxels, as the inconsistency coefficient threshold allows only the voxels to be clustered that are at a minimum distance to some cluster.

  18. Diagnosing periprosthetic infection: false-positive intraoperative Gram stains.

    Science.gov (United States)

    Oethinger, Margret; Warner, Debra K; Schindler, Susan A; Kobayashi, Hideo; Bauer, Thomas W

    2011-04-01

    Intraoperative Gram stains have a reported low sensitivity but high specificity when used to help diagnose periprosthetic infections. In early 2008, we recognized an unexpectedly high frequency of apparent false-positive Gram stains from revision arthroplasties. The purpose of this report is to describe the cause of these false-positive test results. We calculated the sensitivity and specificity of all intraoperative Gram stains submitted from revision arthroplasty cases during a 3-month interval using microbiologic cultures of the same samples as the gold standard. Methods of specimen harvesting, handling, transport, distribution, specimen processing including tissue grinding/macerating, Gram staining, and interpretation were studied. After a test modification, results of specimens were prospectively collected for a second 3-month interval, and the sensitivity and specificity of intraoperative Gram stains were calculated. The retrospective review of 269 Gram stains submitted from revision arthroplasties indicated historic sensitivity and specificity values of 23% and 92%, respectively. Systematic analysis of all steps of the procedure identified Gram-stained but nonviable bacteria in commercial broth reagents used as diluents for maceration of periprosthetic membranes before Gram staining and culture. Polymerase chain reaction and sequencing showed mixed bacterial DNA. Evaluation of 390 specimens after initiating standardized Millipore filtering of diluent fluid revealed a reduced number of positive Gram stains, yielding 9% sensitivity and 99% specificity. Clusters of false-positive Gram stains have been reported in other clinical conditions. They are apparently rare related to diagnosing periprosthetic infections but have severe consequences if used to guide treatment. Even occasional false-positive Gram stains should prompt review of laboratory methods. Our observations implicate dead bacteria in microbiologic reagents as potential sources of false-positive Gram

  19. Consensus-based identification of factors related to false-positives in ultrasound scanning of synovitis and tenosynovitis.

    Science.gov (United States)

    Ikeda, Kei; Narita, Akihiro; Ogasawara, Michihiro; Ohno, Shigeru; Kawahito, Yutaka; Kawakami, Atsushi; Ito, Hiromu; Matsushita, Isao; Suzuki, Takeshi; Misaki, Kenta; Ogura, Takehisa; Kamishima, Tamotsu; Seto, Yohei; Nakahara, Ryuichi; Kaneko, Atsushi; Nakamura, Takayuki; Henmi, Mihoko; Fukae, Jun; Nishida, Keiichiro; Sumida, Takayuki; Koike, Takao

    2016-01-01

    We aimed to identify causes of false-positives in ultrasound scanning of synovial/tenosynovial/bursal inflammation and provide corresponding imaging examples. We first performed systematic literature review to identify previously reported causes of false-positives. We next determined causes of false-positives and corresponding example images for educational material through Delphi exercises and discussion by 15 experts who were an instructor and/or a lecturer in the 2013 advanced course for musculoskeletal ultrasound organized by Japan College of Rheumatology Committee for the Standardization of Musculoskeletal Ultrasonography. Systematic literature review identified 11 articles relevant to sonographic false-positives of synovial/tenosynovial inflammation. Based on these studies, 21 candidate causes of false-positives were identified in the consensus meeting. Of these items, 11 achieved a predefined consensus (≥ 80%) in Delphi exercise and were classified as follows: (I) Gray-scale assessment [(A) non-specific synovial findings and (B) normal anatomical structures which can mimic synovial lesions due to either their low echogenicity or anisotropy]; (II) Doppler assessment [(A) Intra-articular normal vessels and (B) reverberation)]. Twenty-four corresponding examples with 49 still and 23 video images also achieved consensus. Our study provides a set of representative images that can help sonographers to understand false-positives in ultrasound scanning of synovitis and tenosynovitis.

  20. Detecting false positive sequence homology: a machine learning approach.

    Science.gov (United States)

    Fujimoto, M Stanley; Suvorov, Anton; Jensen, Nicholas O; Clement, Mark J; Bybee, Seth M

    2016-02-24

    Accurate detection of homologous relationships of biological sequences (DNA or amino acid) amongst organisms is an important and often difficult task that is essential to various evolutionary studies, ranging from building phylogenies to predicting functional gene annotations. There are many existing heuristic tools, most commonly based on bidirectional BLAST searches that are used to identify homologous genes and combine them into two fundamentally distinct classes: orthologs and paralogs. Due to only using heuristic filtering based on significance score cutoffs and having no cluster post-processing tools available, these methods can often produce multiple clusters constituting unrelated (non-homologous) sequences. Therefore sequencing data extracted from incomplete genome/transcriptome assemblies originated from low coverage sequencing or produced by de novo processes without a reference genome are susceptible to high false positive rates of homology detection. In this paper we develop biologically informative features that can be extracted from multiple sequence alignments of putative homologous genes (orthologs and paralogs) and further utilized in context of guided experimentation to verify false positive outcomes. We demonstrate that our machine learning method trained on both known homology clusters obtained from OrthoDB and randomly generated sequence alignments (non-homologs), successfully determines apparent false positives inferred by heuristic algorithms especially among proteomes recovered from low-coverage RNA-seq data. Almost ~42 % and ~25 % of predicted putative homologies by InParanoid and HaMStR respectively were classified as false positives on experimental data set. Our process increases the quality of output from other clustering algorithms by providing a novel post-processing method that is both fast and efficient at removing low quality clusters of putative homologous genes recovered by heuristic-based approaches.

  1. False Positive and False Negative Effects on Network Attacks

    Science.gov (United States)

    Shang, Yilun

    2018-01-01

    Robustness against attacks serves as evidence for complex network structures and failure mechanisms that lie behind them. Most often, due to detection capability limitation or good disguises, attacks on networks are subject to false positives and false negatives, meaning that functional nodes may be falsely regarded as compromised by the attacker and vice versa. In this work, we initiate a study of false positive/negative effects on network robustness against three fundamental types of attack strategies, namely, random attacks (RA), localized attacks (LA), and targeted attack (TA). By developing a general mathematical framework based upon the percolation model, we investigate analytically and by numerical simulations of attack robustness with false positive/negative rate (FPR/FNR) on three benchmark models including Erdős-Rényi (ER) networks, random regular (RR) networks, and scale-free (SF) networks. We show that ER networks are equivalently robust against RA and LA only when FPR equals zero or the initial network is intact. We find several interesting crossovers in RR and SF networks when FPR is taken into consideration. By defining the cost of attack, we observe diminishing marginal attack efficiency for RA, LA, and TA. Our finding highlights the potential risk of underestimating or ignoring FPR in understanding attack robustness. The results may provide insights into ways of enhancing robustness of network architecture and improve the level of protection of critical infrastructures.

  2. Adrenocortical Carcinoma: False Positive in an I-123 Metaiodobenzylguanidine Scan

    Energy Technology Data Exchange (ETDEWEB)

    Rey, Cristina Rodriguez; Candil, Aida Ortega; Galvan, Eliseo Vano; Martin, Maria Nieves Cabrera; Delgado, Jose Luis Carreras [Clinico San Carlos Hospital, Madrid (Spain)

    2016-06-15

    A 55-year-old man with a personal his history of left pheochromocytoma 2 years previously presented with an abdominal ultrasound showed a large left upper quadrant solid mass (calipers), with heterogeneous echogenicity and central cystic degeneration areas or necrosis. F-18 Fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT was performed as ACC was suspected. ACC is an uncommon malignant neoplasm of unknown cause; however, smoking and oral contraceptives may be risk factors. Patients usually present with advanced-stage disease and have poor prognosis, with a 2-year recurrence rate that ranges form 73 to 86 %. An MIBG scan was performed after injection of 185 MBq of I-123 MIBG intravenously. Single photon emission tomography (SPECT)/CT scan showed abnormal isotope accumulation in the tumor region. The patient underwent total resection of the tumor. The histology was of ACC, with areas of necrosis and cystic areas, so the result of the MIBG scan was a false positive. Authors divided false-positive MIBG studies into three categories. The first category is neuroendocrine lesions other than pheochromocytomas (tumors of the APUD series). the second category consists in adrenal lesions other than pheochromocytomas (adenomas, ACC) the reasons for this abnormal uptake are unclear. The third category consists of tracer uptake adjacent to the adrenal due to abnormalities in the route of excretion.

  3. [EXPERIENCE OF STUDY AND POSSIBLE WAYS OF ELIMINATION OF FALSE POSITIVE AND FALSE NEGATIVE RESULTS DURING EXECUTION OF POLYMERASE CHAIN REACTION ON AN EXAMPLE OF JUNIN VIRUS RNA DETECTION].

    Science.gov (United States)

    Sizikova, T E; Lebedev, V N; Pantyukhov, V B; Borisevich, S V; Merkulov, V A

    2015-01-01

    Experience of study and possible ways of elimination of false positive and false negative results during execution of polymerase chain reaction on an example of Junin virus RNA detection. MATERIALSS AND METHODS: Junin virus--causative agent of Argentine hemorrhagic fever (AHF) strain XJpR37/5787 was obtained from the State collection of pathogenicity group I causative agents of the 48th Central Research Institute. Reagent kit for detection of Junin virus RNA by RT-PCR was developed in the Institute and consists of 4 sets: for isolation of RNA, execution of reverse-transcription reaction, execution of PCR and electrophoretic detection of PCR products. RT-PCR was carried out by a standard technique. Continuous cell cultures of African green monkey Vero B, GMK-AH-1(D) were obtained from the museum of cell culture department of the Centre. An experimental study of the effect of various factors of impact on the sample under investigation ("thawing-freezing", presence of formaldehyde, heparin) on the obtaining of false negative results during Junin virus RNA detection by using RT-PCR was studied. Addition of 0.01% heparin to the samples was shown to completely inhibit PCR. Addition of 0.05% formaldehyde significantly reduces sensitivity of the method. A possibility of reduction of analysis timeframe from 15 to 5 days was shown during detection of the causative agent in samples with low concentration of the latter by growing the samples and subsequent analysis of the material obtained by using RT-PCR. During detection of causative agent by using RT-PCR false negative results could appear in the presence of formaldehyde and heparin in the sample. A possibility of elimination of false negative PCR results due to concentration of the causative agent in the sample under investigation at a level below sensitivity threshold was shown on the example of Junin virus RNA detection by using growing of the pathogen in appropriate accumulation system with subsequent analysis of the

  4. Addressing False Positives in Early Reading Assessment Using Intervention Response Data

    Science.gov (United States)

    McAlenney, Athena Lentini; Coyne, Michael D.

    2015-01-01

    The current study examined a solution to high false positive reading risk classification rates in early kindergarten by investigating a method of identifying students with possible false positive risk classifications and returning them to general classroom instruction. Researchers assessed kindergarten students (N = 105) identified as at risk who…

  5. Characterisation of false-positive observations in botanical surveys

    Directory of Open Access Journals (Sweden)

    Quentin J. Groom

    2017-05-01

    Full Text Available Errors in botanical surveying are a common problem. The presence of a species is easily overlooked, leading to false-absences; while misidentifications and other mistakes lead to false-positive observations. While it is common knowledge that these errors occur, there are few data that can be used to quantify and describe these errors. Here we characterise false-positive errors for a controlled set of surveys conducted as part of a field identification test of botanical skill. Surveys were conducted at sites with a verified list of vascular plant species. The candidates were asked to list all the species they could identify in a defined botanically rich area. They were told beforehand that their final score would be the sum of the correct species they listed, but false-positive errors counted against their overall grade. The number of errors varied considerably between people, some people create a high proportion of false-positive errors, but these are scattered across all skill levels. Therefore, a person’s ability to correctly identify a large number of species is not a safeguard against the generation of false-positive errors. There was no phylogenetic pattern to falsely observed species; however, rare species are more likely to be false-positive as are species from species rich genera. Raising the threshold for the acceptance of an observation reduced false-positive observations dramatically, but at the expense of more false negative errors. False-positive errors are higher in field surveying of plants than many people may appreciate. Greater stringency is required before accepting species as present at a site, particularly for rare species. Combining multiple surveys resolves the problem, but requires a considerable increase in effort to achieve the same sensitivity as a single survey. Therefore, other methods should be used to raise the threshold for the acceptance of a species. For example, digital data input systems that can verify

  6. False-positive head-impulse test in cerebellar ataxia

    Directory of Open Access Journals (Sweden)

    Olympia eKremmyda

    2012-11-01

    Full Text Available Abstract:The objective of this study was to compare the findings of the bedside head impulse test (HIT, passive head rotation gain, and caloric irrigation in patients with cerebellar ataxia (CA. In 16 patients with CA and bilaterally pathological bedside HIT, VOR gains were measured during HIT and passive head rotation by scleral search coil technique. Eight of the patients had pathologically reduced caloric responsiveness, while the other eight had normal caloric responses. Those with normal calorics showed a slightly reduced HIT gain (mean±SD: 0.73±0.15. In those with pathological calorics, gains 80ms and 100 ms after the HIT as well as the passive rotation VOR gains were significantly lower. The corrective saccade after head turn occurred earlier in patients with pathological calorics (111±62 ms after onset of the HIT than in those with normal calorics. (191±17 ms, p=0.0064 We indentified two groups of patients with CA: those with an isolated moderate HIT deficit only, probably due to floccular dysfunction, and those with combined HIT, passive rotation and caloric deficit, probably due to a peripheral vestibular deficit. From a clinical point of view, these results show that the bedside HIT alone can be false positive for establishing a diagnosis of a bilateral peripheral vestibular deficit in patients with CA.

  7. Improving computer-aided detection assistance in breast cancer screening by removal of obviously false-positive findings

    NARCIS (Netherlands)

    Mordang, Jan-Jurre; Gubern-Merida, Albert; Bria, Alessandro; Tortorella, Francesco; den Heeten, Gerard; Karssemeijer, Nico

    2017-01-01

    Purpose: Computer-aided detection (CADe) systems for mammography screening still mark many false positives. This can cause radiologists to lose confidence in CADe, especially when many false positives are obviously not suspicious to them. In this study, we focus on obvious false positives generated

  8. Improving computer-aided detection assistance in breast cancer screening by removal of obviously false-positive findings

    NARCIS (Netherlands)

    Mordang, J.J.; Gubern Merida, A.; Bria, A.; Tortorella, F.; Heeten, G.; Karssemeijer, N.

    2017-01-01

    PURPOSE: Computer-aided detection (CADe) systems for mammography screening still mark many false positives. This can cause radiologists to lose confidence in CADe, especially when many false positives are obviously not suspicious to them. In this study, we focus on obvious false positives generated

  9. APHRODITE: an Anomaly-based Architecture for False Positive Reduction

    NARCIS (Netherlands)

    Bolzoni, D.; Etalle, Sandro

    We present APHRODITE, an architecture designed to reduce false positives in network intrusion detection systems. APHRODITE works by detecting anomalies in the output traffic, and by correlating them with the alerts raised by the NIDS working on the input traffic. Benchmarks show a substantial

  10. A Demonstration of Regression False Positive Selection in Data Mining

    Science.gov (United States)

    Pinder, Jonathan P.

    2014-01-01

    Business analytics courses, such as marketing research, data mining, forecasting, and advanced financial modeling, have substantial predictive modeling components. The predictive modeling in these courses requires students to estimate and test many linear regressions. As a result, false positive variable selection ("type I errors") is…

  11. False-positive Human Papillomavirus DNA tests in cervical screening

    DEFF Research Database (Denmark)

    Rebolj, Matejka; Pribac, Igor; Lynge, Elsebeth

    2011-01-01

    Based on data from randomised controlled trials (RCT) on primary cervical screening, it has been reported that the problem of more frequent false-positive tests in Human Papillomavirus (HPV) DNA screening compared to cytology could be overcome. However, these reports predominantly operated...

  12. Epidemiology, public health, and the rhetoric of false positives

    DEFF Research Database (Denmark)

    Blair, Aaron; Saracci, Rodolfo; Vineis, Paolo

    2009-01-01

    BACKGROUND: As an observational science, epidemiology is regarded by some researchers as inherently flawed and open to false results. In a recent paper, Boffetta et al. [Boffetta P, McLaughlin JK, LaVecchia C, Tarone RE, Lipworth L, Blot WJ. False-positive results in cancer epidemiology: a plea f...

  13. False-positive reduction in CAD mass detection using a competitive classification strategy

    International Nuclear Information System (INIS)

    Li Lihua; Zheng Yang; Zhang Lei; Clark, Robert A.

    2001-01-01

    High false-positive (FP) rate remains to be one of the major problems to be solved in CAD study because too many false-positively cued signals will potentially degrade the performance of detecting true-positive regions and increase the call-back rate in CAD environment. In this paper, we proposed a novel classification method for FP reduction, where the conventional 'hard' decision classifier is cascaded with a 'soft' decision classification with the objective to reduce false-positives in the cases with multiple FPs retained after the 'hard' decision classification. The 'soft' classification takes a competitive classification strategy in which only the 'best' ones are selected from the pre-classified suspicious regions as the true mass in each case. A neural network structure is designed to implement the proposed competitive classification. Comparative studies of FP reduction on a database of 79 images by a 'hard' decision classification and a combined 'hard'-'soft' classification method demonstrated the efficiency of the proposed classification strategy. For example, for the high FP sub-database which has only 31.7% of total images but accounts for 63.5% of whole FPs generated in single 'hard' classification, the FPs can be reduced for 56% (from 8.36 to 3.72 per image) by using the proposed method at the cost of 1% TP loss (from 69% to 68%) in whole database, while it can only be reduced for 27% (from 8.36 to 6.08 per image) by simply increasing the threshold of 'hard' classifier with a cost of TP loss as high as 14% (from 69% to 55%). On the average in whole database, the FP reduction by hybrid 'hard'-'soft' classification is 1.58 per image as compared to 1.11 by 'hard' classification at the TP costs described above. Because the cases with high dense tissue are of higher risk of cancer incidence and false-negative detection in mammogram screening, and usually generate more FPs in CAD detection, the method proposed in this paper will be very helpful in improving

  14. Increased risk of breast cancer in women with false-positive test

    DEFF Research Database (Denmark)

    von Euler-Chelpin, My; Kuchiki, Megumi; Vejborg, Ilse

    2014-01-01

    of misclassification, i.e. women who were actually false-negatives instead of false-positives. METHOD: We used data from the Copenhagen Mammography Screening Programme, Denmark. The study population was the 295 women, out of 4743 recalled women from a total of 58,003 participants, with a false-positive test during...... the women with misclassified tests had been excluded, there was an excess risk of breast cancer of 27% (RR=1.27, 95% confidence interval (CI), 1.11-1.46) among the women with a false-positive test compared to women with only negative tests. Women with a false-positive test determined at assessment had...... an excess risk of 27%, while false-positives determined at surgery had an excess risk of 30%. CONCLUSIONS: The results indicate that the increased risk is not explained only by misclassification. The excess risk remains for false-positives determined at assessment as well as at surgery, which favours some...

  15. THE XO PLANETARY SURVEY PROJECT: ASTROPHYSICAL FALSE POSITIVES

    International Nuclear Information System (INIS)

    Poleski, Radosaw; McCullough, Peter R.; Valenti, Jeff A.; Burke, Christopher J.; Machalek, Pavel; Janes, Kenneth

    2010-01-01

    Searches for planetary transits find many astrophysical false positives as a by-product. There are four main types analyzed in the literature: a grazing-incidence eclipsing binary (EB) star, an EB star with a small radius companion star, a blend of one or more stars with an unrelated EB star, and a physical triple star system. We present a list of 69 astrophysical false positives that had been identified as candidates of transiting planets of the on-going XO survey. This list may be useful in order to avoid redundant observation and characterization of these particular candidates that have been independently identified by other wide-field searches for transiting planets. The list may be useful for those modeling the yield of the XO survey and surveys similar to it. Subsequent observations of some of the listed stars may improve mass-radius relations, especially for low-mass stars. From the candidates exhibiting eclipses, we report three new spectroscopic double-line binaries and give mass function estimations for 15 single-line spectroscopic binaries.

  16. Interval Breast Cancer Rates and Histopathologic Tumor Characteristics after False-Positive Findings at Mammography in a Population-based Screening Program.

    Science.gov (United States)

    Hofvind, Solveig; Sagstad, Silje; Sebuødegård, Sofie; Chen, Ying; Roman, Marta; Lee, Christoph I

    2018-04-01

    Purpose To compare rates and tumor characteristics of interval breast cancers (IBCs) detected after a negative versus false-positive screening among women participating in the Norwegian Breast Cancer Screening Program. Materials and Methods The Cancer Registry Regulation approved this retrospective study. Information about 423 445 women aged 49-71 years who underwent 789 481 full-field digital mammographic screening examinations during 2004-2012 was extracted from the Cancer Registry of Norway. Rates and odds ratios of IBC among women with a negative (the reference group) versus a false-positive screening were estimated by using logistic regression models adjusted for age at diagnosis and county of residence. Results A total of 1302 IBCs were diagnosed after 789 481 screening examinations, of which 7.0% (91 of 1302) were detected among women with a false-positive screening as the most recent breast imaging examination before detection. By using negative screening as the reference, adjusted odds ratios of IBCs were 3.3 (95% confidence interval [CI]: 2.6, 4.2) and 2.8 (95% CI: 1.8, 4.4) for women with a false-positive screening without and with needle biopsy, respectively. Women with a previous negative screening had a significantly lower proportion of tumors that were 10 mm or less (14.3% [150 of 1049] vs 50.0% [seven of 14], respectively; P false-positive screening with benign biopsy. A retrospective review of the screening mammographic examinations identified 42.9% (39 of 91) of the false-positive cases to be the same lesion as the IBC. Conclusion By using a negative screening as the reference, a false-positive screening examination increased the risk of an IBC three-fold. The tumor characteristics of IBC after a negative screening were less favorable compared with those detected after a previous false-positive screening. © RSNA, 2017 Online supplemental material is available for this article.

  17. Protein complex prediction via dense subgraphs and false positive analysis.

    Directory of Open Access Journals (Sweden)

    Cecilia Hernandez

    Full Text Available Many proteins work together with others in groups called complexes in order to achieve a specific function. Discovering protein complexes is important for understanding biological processes and predict protein functions in living organisms. Large-scale and throughput techniques have made possible to compile protein-protein interaction networks (PPI networks, which have been used in several computational approaches for detecting protein complexes. Those predictions might guide future biologic experimental research. Some approaches are topology-based, where highly connected proteins are predicted to be complexes; some propose different clustering algorithms using partitioning, overlaps among clusters for networks modeled with unweighted or weighted graphs; and others use density of clusters and information based on protein functionality. However, some schemes still require much processing time or the quality of their results can be improved. Furthermore, most of the results obtained with computational tools are not accompanied by an analysis of false positives. We propose an effective and efficient mining algorithm for discovering highly connected subgraphs, which is our base for defining protein complexes. Our representation is based on transforming the PPI network into a directed acyclic graph that reduces the number of represented edges and the search space for discovering subgraphs. Our approach considers weighted and unweighted PPI networks. We compare our best alternative using PPI networks from Saccharomyces cerevisiae (yeast and Homo sapiens (human with state-of-the-art approaches in terms of clustering, biological metrics and execution times, as well as three gold standards for yeast and two for human. Furthermore, we analyze false positive predicted complexes searching the PDBe (Protein Data Bank in Europe database in order to identify matching protein complexes that have been purified and structurally characterized. Our analysis shows

  18. The problem of false positives and false negatives in violent video game experiments.

    Science.gov (United States)

    Ferguson, Christopher J

    The problem of false positives and negatives has received considerable attention in behavioral research in recent years. The current paper uses video game violence research as an example of how such issues may develop in a field. Despite decades of research, evidence on whether violent video games (VVGs) contribute to aggression in players has remained mixed. Concerns have been raised in recent years that experiments regarding VVGs may suffer from both "false positives" and "false negatives." The current paper examines this issue in three sets of video game experiments, two sets of video game experiments on aggression and prosocial behaviors identified in meta-analysis, and a third group of recent null studies. Results indicated that studies of VVGs and aggression appear to be particularly prone to false positive results. Studies of VVGs and prosocial behavior, by contrast are heterogeneous and did not demonstrate any indication of false positive results. However, their heterogeneous nature made it difficult to base solid conclusions on them. By contrast, evidence for false negatives in null studies was limited, and little evidence emerged that null studies lacked power in comparison those highlighted in past meta-analyses as evidence for effects. These results are considered in light of issues related to false positives and negatives in behavioral science more broadly. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. The OGCleaner: filtering false-positive homology clusters.

    Science.gov (United States)

    Fujimoto, M Stanley; Suvorov, Anton; Jensen, Nicholas O; Clement, Mark J; Snell, Quinn; Bybee, Seth M

    2017-01-01

    Detecting homologous sequences in organisms is an essential step in protein structure and function prediction, gene annotation and phylogenetic tree construction. Heuristic methods are often employed for quality control of putative homology clusters. These heuristics, however, usually only apply to pairwise sequence comparison and do not examine clusters as a whole. We present the Orthology Group Cleaner (the OGCleaner), a tool designed for filtering putative orthology groups as homology or non-homology clusters by considering all sequences in a cluster. The OGCleaner relies on high-quality orthologous groups identified in OrthoDB to train machine learning algorithms that are able to distinguish between true-positive and false-positive homology groups. This package aims to improve the quality of phylogenetic tree construction especially in instances of lower-quality transcriptome assemblies. https://github.com/byucsl/ogcleaner CONTACT: sfujimoto@gmail.comSupplementary information: Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  20. Reduction of lymph tissue false positives in pulmonary embolism detection

    Science.gov (United States)

    Ghanem, Bernard; Liang, Jianming; Bi, Jinbo; Salganicoff, Marcos; Krishnan, Arun

    2008-03-01

    Pulmonary embolism (PE) is a serious medical condition, characterized by the partial/complete blockage of an artery within the lungs. We have previously developed a fast yet effective approach for computer aided detection of PE in computed topographic pulmonary angiography (CTPA),1 which is capable of detecting both acute and chronic PEs, achieving a benchmark performance of 78% sensitivity at 4 false positives (FPs) per volume. By reviewing the FPs generated by this system, we found the most dominant type of FP, roughly one third of all FPs, to be lymph/connective tissue. In this paper, we propose a novel approach that specifically aims at reducing this FP type. Our idea is to explicitly exploit the anatomical context configuration of PE and lymph tissue in the lungs: a lymph FP connects to the airway and is located outside the artery, while a true PE should not connect to the airway and must be inside the artery. To realize this idea, given a detected candidate (i.e. a cluster of suspicious voxels), we compute a set of contextual features, including its distance to the airway based on local distance transform and its relative position to the artery based on fast tensor voting and Hessian "vesselness" scores. Our tests on unseen cases show that these features can reduce the lymph FPs by 59%, while improving the overall sensitivity by 3.4%.

  1. Newly formed skeletal muscle fibers are prone to false positive immunostaining by rabbit antibodies

    DEFF Research Database (Denmark)

    Andersen, Ditte C; Kliem, Anette; Schrøder, Henrik Daa

    2011-01-01

    rely on controls that reveal non-specific binding by the secondary antibody and neglect that the primary rabbit antibody itself may cause false positive staining of the muscle. We suggest that reliable immuno-based protein detection in newly formed muscle fibers at least requires a nonsense rabbit......Reports on muscle biology and regeneration often implicate immuno(cyto/histo)chemical protein characterization using rabbit polyclonal antibodies. In this study we demonstrate that newly formed myofibers are especially prone to false positive staining by rabbit antibodies and this unwanted staining...

  2. The problem of false-positive human papillomavirus DNA tests in cervical screening

    DEFF Research Database (Denmark)

    Rebolj, Matejka; Pribac, Igor; Frederiksen, Maria Eiholm

    2013-01-01

    Human Papillomavirus (HPV) testing has been extensively studied in randomized controlled trials of primary cervical screening. Based on encouraging results concerning its high detection rates and a high negative predictive value for high-grade cervical intraepithelial neoplasia (CIN), HPV testing...... will probably replace cytology in future primary cervical screening. However, HPV testing is associated with more frequent false-positive tests compared to cytology. False-positive tests are defined as positive screening tests which are not subsequently confirmed with high-grade CIN. Several authors have...

  3. Reducing false positives of microcalcification detection systems by removal of breast arterial calcifications.

    Science.gov (United States)

    Mordang, Jan-Jurre; Gubern-Mérida, Albert; den Heeten, Gerard; Karssemeijer, Nico

    2016-04-01

    In the past decades, computer-aided detection (CADe) systems have been developed to aid screening radiologists in the detection of malignant microcalcifications. These systems are useful to avoid perceptual oversights and can increase the radiologists' detection rate. However, due to the high number of false positives marked by these CADe systems, they are not yet suitable as an independent reader. Breast arterial calcifications (BACs) are one of the most frequent false positives marked by CADe systems. In this study, a method is proposed for the elimination of BACs as positive findings. Removal of these false positives will increase the performance of the CADe system in finding malignant microcalcifications. A multistage method is proposed for the removal of BAC findings. The first stage consists of a microcalcification candidate selection, segmentation and grouping of the microcalcifications, and classification to remove obvious false positives. In the second stage, a case-based selection is applied where cases are selected which contain BACs. In the final stage, BACs are removed from the selected cases. The BACs removal stage consists of a GentleBoost classifier trained on microcalcification features describing their shape, topology, and texture. Additionally, novel features are introduced to discriminate BACs from other positive findings. The CADe system was evaluated with and without BACs removal. Here, both systems were applied on a validation set containing 1088 cases of which 95 cases contained malignant microcalcifications. After bootstrapping, free-response receiver operating characteristics and receiver operating characteristics analyses were carried out. Performance between the two systems was compared at 0.98 and 0.95 specificity. At a specificity of 0.98, the sensitivity increased from 37% to 52% and the sensitivity increased from 62% up to 76% at a specificity of 0.95. Partial areas under the curve in the specificity range of 0.8-1.0 were

  4. Parental knowledge reduces long term anxiety induced by false-positive test results after newborn screening for cystic fibrosis

    NARCIS (Netherlands)

    Vernooij-van Langen, A.M.M.; Pal, S.M. van der; Reijntjens, A.J.T.; Loeber, J.G.; Dompeling, E.; Dankert-Roelse, J.E.

    2014-01-01

    Background: False-positive screening results in newborn screening for cystic fibrosis may lead to parental stress, family relationship problems and a changed perception of the child's health. Aim of the study: To evaluate whether parental anxiety induced by a false positive screening result

  5. A deep 3D residual CNN for false-positive reduction in pulmonary nodule detection.

    Science.gov (United States)

    Jin, Hongsheng; Li, Zongyao; Tong, Ruofeng; Lin, Lanfen

    2018-05-01

    The automatic detection of pulmonary nodules using CT scans improves the efficiency of lung cancer diagnosis, and false-positive reduction plays a significant role in the detection. In this paper, we focus on the false-positive reduction task and propose an effective method for this task. We construct a deep 3D residual CNN (convolution neural network) to reduce false-positive nodules from candidate nodules. The proposed network is much deeper than the traditional 3D CNNs used in medical image processing. Specifically, in the network, we design a spatial pooling and cropping (SPC) layer to extract multilevel contextual information of CT data. Moreover, we employ an online hard sample selection strategy in the training process to make the network better fit hard samples (e.g., nodules with irregular shapes). Our method is evaluated on 888 CT scans from the dataset of the LUNA16 Challenge. The free-response receiver operating characteristic (FROC) curve shows that the proposed method achieves a high detection performance. Our experiments confirm that our method is robust and that the SPC layer helps increase the prediction accuracy. Additionally, the proposed method can easily be extended to other 3D object detection tasks in medical image processing. © 2018 American Association of Physicists in Medicine.

  6. Analysis of false positive and false negative cytological diagnosis of breast lesions

    International Nuclear Information System (INIS)

    Jamal, Awtif A.; Mansoor, I.

    2001-01-01

    To study the reasons for interpretive errors in false negative and false positive diagnosis of breast carcinoma on fine needle aspiration cytology material. We reviewed only those cases in which cytohistological discrepancies were found, where the cytologic material was abnormal and to some extent misinterpreted or both. There was only one false negative case (false negative fraction 0.32%) proved histologically as ductal carcinoma and four false positive cases (false positive fraction 1.2%); 2 fibroadenoma; 1 fibrocystic disease; and 1 stromal fibrosis. Smears of the two false positive fibroadenoma cases showed very high cellularity, overcrowded clusters and frequent stripped nuclei. The fibrocystic case showed tight clusters of apocrine cells and sheets of loosely aggregated macrophages that were over interpreted. Smears of the false negative ductal carcinoma was hypocellular overall, and the cells showed minimal nuclear pleomorphism. Overcrowded clusters and hypercellular smears should be carefully assessed for uniformity of cells and detailed nuclear and cytomorphological features. If the full-blown malignant cytomorphological changes are not visible, a diagnosis of suspicious or inconclusive should be made and frozen section recommended before surgery. Hypocellularity and relatively nuclear monomorphism are the reasons for failure to diagnose malignant breast lesions. Careful attention should be paid to extreme nuclear monomorphism and absence of naked bipolar cells. A cytologically atypical or suspicious diagnosis together with positive radiological and clinical findings should suggest a diagnosis of malignancy. (author)

  7. Computer-Aided Detection in Digital Mammography: False-Positive Marks and Their Reproducibility in Negative Mammograms

    International Nuclear Information System (INIS)

    Kim, Seung Ja; Moon, Woo Kyung; Cho, Nariya; Chang, Jung Min; Seong, Min Hyun

    2009-01-01

    Background: There are relatively few studies reporting the frequency of false-positive computer-aided detection (CAD) marks and their reproducibility in normal cases. Purpose: To evaluate retrospectively the false-positive mark rate of a CAD system and the reproducibility of false-positive marks in two sets of negative digital mammograms. Material and Methods: Two sets of negative digital mammograms were obtained in 360 women (mean age 57 years, range 30-76 years) with an approximate interval of 1 year (mean time 343.7 days), and a CAD system was applied. False-positive CAD marks and the reproducibility were determined. Results: Of the 360 patients, 252 (70.0%) and 240 (66.7%) patients had 1-7 CAD marks on the initial and second mammograms, respectively. The false-positive CAD mark rate was 1.5 (1.1 for masses and 0.4 for calcifications) and 1.4 (1.0 for masses and 0.4 for calcifications) per examination in the initial and second mammograms, respectively. The reproducibility of the false-positive CAD marks was 12.0% for both mass (81/680) and microcalcification (33/278) marks. Conclusion: False-positive CAD marks were seen in approximately 70% of normal cases. However, the reproducibility was very low. Radiologists must be familiar with the findings of false-positive CAD marks, since they are very common and can increase the recall rate in screening

  8. Benign oral pathology as a cause of false positive 131I uptake in thyroid carcinoma

    International Nuclear Information System (INIS)

    Mansberg, R.; Wadhwa, S.S.; Fernandes, V.B.

    1997-01-01

    Full text: We present three thyroidectomised patients with a history of thyroid carcinoma who had non-metastatic 131 I uptake due to benign oral pathology. A salivary gland study suggested impaired function but no obstruction was demonstrated on a sialogram. The symptoms resolved on antibiotic therapy and a subsequent 131 I study was normal. A subsequent thallium study demonstrated physiological tracer distribution. A 35-year-old female with papillary cell carcinoma of the thyroid demonstrated a focus of uptake on the right hemi-mandible following both a diagnostic and a therapeutic dose of 131 I. This area was tender and an OPG confirmed an area of liquefaction at this site. A 53-year-old female with medullary cell carcinoma of the thyroid demonstrated a focus of uptake in the right side of the maxilla following a diagnostic administration of 131 I. An OPG confirmed an area of liquefaction around the apex of the right upper centre. These three cases illustrate salivary gland and dental inflammation as causes of false positive 131 I uptake. It is important to differentiate non-metastatic 131 I uptake from that due to functioning metastatic thyroid carcinoma in order to avoid inappropriate treatment with large additional doses of 131 I. As in these patients, clinical assessment and the use of anatomical imaging or other isotopes such as thallium or technetium can be helpful in ruling out a mistaken diagnosis of metastasis

  9. Reducing false positives of microcalcification detection systems by removal of breast arterial calcifications

    International Nuclear Information System (INIS)

    Mordang, Jan-Jurre; Gubern-Mérida, Albert; Karssemeijer, Nico; Heeten, Gerard den

    2016-01-01

    Purpose: In the past decades, computer-aided detection (CADe) systems have been developed to aid screening radiologists in the detection of malignant microcalcifications. These systems are useful to avoid perceptual oversights and can increase the radiologists’ detection rate. However, due to the high number of false positives marked by these CADe systems, they are not yet suitable as an independent reader. Breast arterial calcifications (BACs) are one of the most frequent false positives marked by CADe systems. In this study, a method is proposed for the elimination of BACs as positive findings. Removal of these false positives will increase the performance of the CADe system in finding malignant microcalcifications. Methods: A multistage method is proposed for the removal of BAC findings. The first stage consists of a microcalcification candidate selection, segmentation and grouping of the microcalcifications, and classification to remove obvious false positives. In the second stage, a case-based selection is applied where cases are selected which contain BACs. In the final stage, BACs are removed from the selected cases. The BACs removal stage consists of a GentleBoost classifier trained on microcalcification features describing their shape, topology, and texture. Additionally, novel features are introduced to discriminate BACs from other positive findings. Results: The CADe system was evaluated with and without BACs removal. Here, both systems were applied on a validation set containing 1088 cases of which 95 cases contained malignant microcalcifications. After bootstrapping, free-response receiver operating characteristics and receiver operating characteristics analyses were carried out. Performance between the two systems was compared at 0.98 and 0.95 specificity. At a specificity of 0.98, the sensitivity increased from 37% to 52% and the sensitivity increased from 62% up to 76% at a specificity of 0.95. Partial areas under the curve in the specificity

  10. Reducing false positives of microcalcification detection systems by removal of breast arterial calcifications

    Energy Technology Data Exchange (ETDEWEB)

    Mordang, Jan-Jurre, E-mail: Jan-Jurre.Mordang@radboudumc.nl; Gubern-Mérida, Albert; Karssemeijer, Nico [Diagnostic Image Analysis Group, Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen 6525 GA (Netherlands); Heeten, Gerard den [The National Training Centre for Breast Cancer Screening, Nijmegen 6503 GJ, The Netherlands and Department of Radiology, Amsterdam Medical Center, Amsterdam 1100 DD (Netherlands)

    2016-04-15

    Purpose: In the past decades, computer-aided detection (CADe) systems have been developed to aid screening radiologists in the detection of malignant microcalcifications. These systems are useful to avoid perceptual oversights and can increase the radiologists’ detection rate. However, due to the high number of false positives marked by these CADe systems, they are not yet suitable as an independent reader. Breast arterial calcifications (BACs) are one of the most frequent false positives marked by CADe systems. In this study, a method is proposed for the elimination of BACs as positive findings. Removal of these false positives will increase the performance of the CADe system in finding malignant microcalcifications. Methods: A multistage method is proposed for the removal of BAC findings. The first stage consists of a microcalcification candidate selection, segmentation and grouping of the microcalcifications, and classification to remove obvious false positives. In the second stage, a case-based selection is applied where cases are selected which contain BACs. In the final stage, BACs are removed from the selected cases. The BACs removal stage consists of a GentleBoost classifier trained on microcalcification features describing their shape, topology, and texture. Additionally, novel features are introduced to discriminate BACs from other positive findings. Results: The CADe system was evaluated with and without BACs removal. Here, both systems were applied on a validation set containing 1088 cases of which 95 cases contained malignant microcalcifications. After bootstrapping, free-response receiver operating characteristics and receiver operating characteristics analyses were carried out. Performance between the two systems was compared at 0.98 and 0.95 specificity. At a specificity of 0.98, the sensitivity increased from 37% to 52% and the sensitivity increased from 62% up to 76% at a specificity of 0.95. Partial areas under the curve in the specificity

  11. False-Positive Rate of AKI Using Consensus Creatinine-Based Criteria.

    Science.gov (United States)

    Lin, Jennie; Fernandez, Hilda; Shashaty, Michael G S; Negoianu, Dan; Testani, Jeffrey M; Berns, Jeffrey S; Parikh, Chirag R; Wilson, F Perry

    2015-10-07

    Use of small changes in serum creatinine to diagnose AKI allows for earlier detection but may increase diagnostic false-positive rates because of inherent laboratory and biologic variabilities of creatinine. We examined serum creatinine measurement characteristics in a prospective observational clinical reference cohort of 2267 adult patients with AKI by Kidney Disease Improving Global Outcomes creatinine criteria and used these data to create a simulation cohort to model AKI false-positive rates. We simulated up to seven successive blood draws on an equal population of hypothetical patients with unchanging true serum creatinine values. Error terms generated from laboratory and biologic variabilities were added to each simulated patient's true serum creatinine value to obtain the simulated measured serum creatinine for each blood draw. We determined the proportion of patients who would be erroneously diagnosed with AKI by Kidney Disease Improving Global Outcomes creatinine criteria. Within the clinical cohort, 75.0% of patients received four serum creatinine draws within at least one 48-hour period during hospitalization. After four simulated creatinine measurements that accounted for laboratory variability calculated from assay characteristics and 4.4% of biologic variability determined from the clinical cohort and publicly available data, the overall false-positive rate for AKI diagnosis was 8.0% (interquartile range =7.9%-8.1%), whereas patients with true serum creatinine ≥1.5 mg/dl (representing 21% of the clinical cohort) had a false-positive AKI diagnosis rate of 30.5% (interquartile range =30.1%-30.9%) versus 2.0% (interquartile range =1.9%-2.1%) in patients with true serum creatinine values false-positive rates caused by inherent variability of serum creatinine at higher baseline values, potentially misclassifying patients with CKD in AKI studies. Copyright © 2015 by the American Society of Nephrology.

  12. The uterine blush. A potential false-positive in Meckel's scan interpretation

    International Nuclear Information System (INIS)

    Fink-Bennett, D.

    1982-01-01

    To determine the presence, prevalence, and clinical importance of /sup 99m/Tc pertechnetate uterine uptake, this retrospective analysis of 71 Meckel's scans was undertaken. Specifically, each study was evaluated for the presence of a focal accumulation of radiotracer cephalad to the bladder. Patients received an intravenous dose of 150 microCi/kg of /sup 99m/Tc pertechnetate. Each study consisted of 15 one minute anterior serial gamma camera images, and a 15, 30, and 60 minute anterior, right lateral and posterior scintiscan. Menstrual histories were obtained from all patients except two. No males (33/33), nor premenstrual (13/13), menopausal (4/4) or posthysterectomy (2/2) patients revealed a uterine blush. Eleven of 15 patients (73%) with regular menses demonstrated a uterine blush. They were in the menstrual or secretory phases of their cycle. Four demonstrated no uterine uptake, had regular periods, but were in the proliferative phase of their cycle. Two with irregular periods, and one with no recorded menstrual history, manifested the blush. Radiotracer should be expected in the uterus during the menstrual and secretory phases of the menstrual cycle. It is a manifestation of a normal physiologic phenomenon, and must be recognized to prevent false-positive Meckel's scan interpretations

  13. The uterine blush. A potential false-positive in Meckel's scan interpretation

    Energy Technology Data Exchange (ETDEWEB)

    Fink-Bennett, D.

    1982-10-01

    To determine the presence, prevalence, and clinical importance of /sup 99m/Tc pertechnetate uterine uptake, this retrospective analysis of 71 Meckel's scans was undertaken. Specifically, each study was evaluated for the presence of a focal accumulation of radiotracer cephalad to the bladder. Patients received an intravenous dose of 150 microCi/kg of /sup 99m/Tc pertechnetate. Each study consisted of 15 one minute anterior serial gamma camera images, and a 15, 30, and 60 minute anterior, right lateral and posterior scintiscan. Menstrual histories were obtained from all patients except two. No males (33/33), nor premenstrual (13/13), menopausal (4/4) or posthysterectomy (2/2) patients revealed a uterine blush. Eleven of 15 patients (73%) with regular menses demonstrated a uterine blush. They were in the menstrual or secretory phases of their cycle. Four demonstrated no uterine uptake, had regular periods, but were in the proliferative phase of their cycle. Two with irregular periods, and one with no recorded menstrual history, manifested the blush. Radiotracer should be expected in the uterus during the menstrual and secretory phases of the menstrual cycle. It is a manifestation of a normal physiologic phenomenon, and must be recognized to prevent false-positive Meckel's scan interpretations.

  14. Multilevel Contextual 3-D CNNs for False Positive Reduction in Pulmonary Nodule Detection.

    Science.gov (United States)

    Dou, Qi; Chen, Hao; Yu, Lequan; Qin, Jing; Heng, Pheng-Ann

    2017-07-01

    False positive reduction is one of the most crucial components in an automated pulmonary nodule detection system, which plays an important role in lung cancer diagnosis and early treatment. The objective of this paper is to effectively address the challenges in this task and therefore to accurately discriminate the true nodules from a large number of candidates. We propose a novel method employing three-dimensional (3-D) convolutional neural networks (CNNs) for false positive reduction in automated pulmonary nodule detection from volumetric computed tomography (CT) scans. Compared with its 2-D counterparts, the 3-D CNNs can encode richer spatial information and extract more representative features via their hierarchical architecture trained with 3-D samples. More importantly, we further propose a simple yet effective strategy to encode multilevel contextual information to meet the challenges coming with the large variations and hard mimics of pulmonary nodules. The proposed framework has been extensively validated in the LUNA16 challenge held in conjunction with ISBI 2016, where we achieved the highest competition performance metric (CPM) score in the false positive reduction track. Experimental results demonstrated the importance and effectiveness of integrating multilevel contextual information into 3-D CNN framework for automated pulmonary nodule detection in volumetric CT data. While our method is tailored for pulmonary nodule detection, the proposed framework is general and can be easily extended to many other 3-D object detection tasks from volumetric medical images, where the targeting objects have large variations and are accompanied by a number of hard mimics.

  15. False positive and false negative FDG-PET scans in various thoracic diseases

    International Nuclear Information System (INIS)

    Chang, Jung Min; Lee, Hyun Ju; Goo, Jin Mo; Lee, Ho Young; Lee, Jong Jin; Chung, June Key; Im, Jung Gi

    2006-01-01

    Fluorodeoxygucose (FDG)-positron emission tomography (PET) is being used more and more to differentiate benign form malignant focal lesions and it has been shown to be more efficacious than conventional chest computed tomography (CT). However, FDG is not a cancer-specific agent, and false positive findings in benign diseases have been reported. Infectious diseases (mycobacterial, fungal, bacterial infection), sarcoidosis, radiation pneumonitis and post-operative surgical conditions have shown intense uptake on PET scan. On the other hand, tumors with low glycolytic activity such as adenomas, bronchioloalveolar carcinomas, carcinoid tumors, low grade lymphomas and small sized tumors have revealed false negative findings on PET scan, Furthermore, in diseases located near the physiologic uptake sites (heart, bladder, kidney, and liver), FDG-PET should be complemented with other imaging modalities to confirm results and to minimize false negative findings. Familiarity with these false positive and negative findings will help radiologists interpret PET scans more accurately and also will help to determine the significance of the findings. In this review, we illustrate false positive and negative findings of PET scan in a variety of diseases

  16. Coincidence of scintigraphic false positive and false negative findings in parathyroid and thyroid adenomas (case report)

    Energy Technology Data Exchange (ETDEWEB)

    Mana, O.; Zatta, G.; Boccolari, S.; Barbesti, S.; Tarolo, G.L.

    1987-04-01

    The subtractive double tracer scintigraphy with /sup 201/Tl and /sup 99m/Tc is a useful technique in studying parathyroid nodules; nevertheless, this method can give misleading informations especially in presence of thyroid nodules with false positive and false negative findings. In this case report the technique was applied in studying a patient with three nodules (two thyroid adenomas and one parathyroid adenoma), where both scintigraphic and echographic methods provided misleading informations. The selective uptake of /sup 201/Tl in the upper region of the right thyroid lobe gave a false positive finding, while the increased uptake of /sup 99m/Tc in a hyperfunctioning thyroid adenoma of left lobe masked the parathyroid adenoma laying below, giving a false negative finding.

  17. False positive indium-111 white blood cell scan in a closed clavicle fracture

    International Nuclear Information System (INIS)

    Friedman, R.J.; Gordon, L.

    1988-01-01

    Aggressive treatment of the multiply injured patient often requires early fixation of many fractures, some of which may be open. Often, patients develop postoperative fevers requiring a thorough workup to rule out infection. Recently, indium-111 white blood cell (WBC) imaging has become a valuable adjunct in the diagnosis of acute infection. The patient described had a simple, closed clavicle fracture with markedly increased activity on an indium-111 WBC scan obtained for fever workup. This subsequently proved to be a normal, healing, noninfected fracture by other diagnostic techniques. Noninfected, simple closed fractures should be added to the list of causes for a false-positive indium-111 WBC scan

  18. Proteins interacting with cloning scars: a source of false positive protein-protein interactions.

    Science.gov (United States)

    Banks, Charles A S; Boanca, Gina; Lee, Zachary T; Florens, Laurence; Washburn, Michael P

    2015-02-23

    A common approach for exploring the interactome, the network of protein-protein interactions in cells, uses a commercially available ORF library to express affinity tagged bait proteins; these can be expressed in cells and endogenous cellular proteins that copurify with the bait can be identified as putative interacting proteins using mass spectrometry. Control experiments can be used to limit false-positive results, but in many cases, there are still a surprising number of prey proteins that appear to copurify specifically with the bait. Here, we have identified one source of false-positive interactions in such studies. We have found that a combination of: 1) the variable sequence of the C-terminus of the bait with 2) a C-terminal valine "cloning scar" present in a commercially available ORF library, can in some cases create a peptide motif that results in the aberrant co-purification of endogenous cellular proteins. Control experiments may not identify false positives resulting from such artificial motifs, as aberrant binding depends on sequences that vary from one bait to another. It is possible that such cryptic protein binding might occur in other systems using affinity tagged proteins; this study highlights the importance of conducting careful follow-up studies where novel protein-protein interactions are suspected.

  19. Analyzing false positives of four questions in the Force Concept Inventory

    Science.gov (United States)

    Yasuda, Jun-ichiro; Mae, Naohiro; Hull, Michael M.; Taniguchi, Masa-aki

    2018-06-01

    In this study, we analyze the systematic error from false positives of the Force Concept Inventory (FCI). We compare the systematic errors of question 6 (Q.6), Q.7, and Q.16, for which clearly erroneous reasoning has been found, with Q.5, for which clearly erroneous reasoning has not been found. We determine whether or not a correct response to a given FCI question is a false positive using subquestions. In addition to the 30 original questions, subquestions were introduced for Q.5, Q.6, Q.7, and Q.16. This modified version of the FCI was administered to 1145 university students in Japan from 2015 to 2017. In this paper, we discuss our finding that the systematic errors of Q.6, Q.7, and Q.16 are much larger than that of Q.5 for students with mid-level FCI scores. Furthermore, we find that, averaged over the data sample, the sum of the false positives from Q.5, Q.6, Q.7, and Q.16 is about 10% of the FCI score of a midlevel student.

  20. ST-Segment Depression in Hyperventilation Indicates a False Positive Exercise Test in Patients with Mitral Valve Prolapse

    Directory of Open Access Journals (Sweden)

    Andreas P. Michaelides

    2010-01-01

    Full Text Available Objectives. Mitral valve prolapse (MVP is a known cause for false positive exercise test (ET. The purpose of this study was to establish additional electrocardiographic criteria to distinguish the false positive exercise results in patients with MVP. Methods. We studied 218 consecutive patients ( years, 103 males with MVP (according to echocardiographic study, and positive treadmill ET was performed due to multiple cardiovascular risk factors or angina-like symptoms. A coronary angiography was performed to detect coronary artery disease (CAD. Results. From 218 patients, 90 (group A presented with normal coronary arteries according to the angiography (false positive ET while the rest 128 (group B presented with CAD. ST-segment depression in hyperventilation phase was present in 54 patients of group A (60% while only in 14 patients of group B (11%, . Conclusions. Presence of ST-segment depression in hyperventilation phase favors a false positive ET in patients with MVP.

  1. Data from Paper “False-Positive Psychology: Undisclosed Flexibility in Data Collection and Analysis Allows Presenting Anything as Significant”

    Directory of Open Access Journals (Sweden)

    Joseph P Simmons

    2014-02-01

    Full Text Available The data includes measures collected for the two experiments reported in “False-Positive Psychology” [1] where listening to a randomly assigned song made people feel younger (Study 1 or actually be younger (Study 2. These data are useful because they illustrate inflations of false positive rates due to flexibility in data collection, analysis, and reporting of results. Data are useful for educational purposes.

  2. Risk of breast cancer after false-positive test results in screening mammography

    DEFF Research Database (Denmark)

    von Euler-Chelpin, My Catarina; Risør, Louise Madeleine; Thorsted, Brian Larsen

    2012-01-01

    Screening for disease in healthy people inevitably leads to some false-positive tests in disease-free individuals. Normally, women with false-positive screening tests for breast cancer are referred back to routine screening. However, the long-term outcome for women with false-positive tests...

  3. False positive reduction in protein-protein interaction predictions using gene ontology annotations

    Directory of Open Access Journals (Sweden)

    Lin Yen-Han

    2007-07-01

    Full Text Available Abstract Background Many crucial cellular operations such as metabolism, signalling, and regulations are based on protein-protein interactions. However, the lack of robust protein-protein interaction information is a challenge. One reason for the lack of solid protein-protein interaction information is poor agreement between experimental findings and computational sets that, in turn, comes from huge false positive predictions in computational approaches. Reduction of false positive predictions and enhancing true positive fraction of computationally predicted protein-protein interaction datasets based on highly confident experimental results has not been adequately investigated. Results Gene Ontology (GO annotations were used to reduce false positive protein-protein interactions (PPI pairs resulting from computational predictions. Using experimentally obtained PPI pairs as a training dataset, eight top-ranking keywords were extracted from GO molecular function annotations. The sensitivity of these keywords is 64.21% in the yeast experimental dataset and 80.83% in the worm experimental dataset. The specificities, a measure of recovery power, of these keywords applied to four predicted PPI datasets for each studied organisms, are 48.32% and 46.49% (by average of four datasets in yeast and worm, respectively. Based on eight top-ranking keywords and co-localization of interacting proteins a set of two knowledge rules were deduced and applied to remove false positive protein pairs. The 'strength', a measure of improvement provided by the rules was defined based on the signal-to-noise ratio and implemented to measure the applicability of knowledge rules applying to the predicted PPI datasets. Depending on the employed PPI-predicting methods, the strength varies between two and ten-fold of randomly removing protein pairs from the datasets. Conclusion Gene Ontology annotations along with the deduced knowledge rules could be implemented to partially

  4. [Evaluation of performance and false positivity of Mediace RPR test that uses a chemistry autoanalyzer].

    Science.gov (United States)

    Noh, Jaekwang; Ko, Hak Hyun; Yun, Yeomin; Choi, Young Sook; Lee, Sang Gon; Shin, Sue; Han, Kyou Sup; Song, Eun Young

    2008-08-01

    We evaluated the performance and false positive rate of Mediace RPR test (Sekisui, Japan), a newly introduced nontreponemal test using a chemistry autoanalyzer. The sensitivity of Mediace RPR test was analyzed using sera from 50 patients with syphilis in different stages (8 primary, 7 secondary, and 35 latent), 14 sera positive with fluorescent treponemal antibody absorption (FTA-ABS) IgM, and 74 sera positive with conventional rapid plasma regain (RPR) card test (Asan, Korea) and also positive with Treponema pallidum hemagglutination (TPHA) test or FTA-ABS IgG test. The specificity was analyzed on 108 healthy blood donors. We also performed RPR card test on 302 sera that had been tested positive with Mediace RPR test and also performed TPHA or FTA-ABS IgG test to analyze the false positive rate of Mediace RPR test. A cutoff value of 0.5 R.U. (RPR unit) was used for Mediace RPR test. Mediace RPR test on syphilitic sera of different stages (primary, secondary, and latent stages) and FTA-ABS IgM positive sera showed a sensitivity of 100%, 100%, 82.9% and 100%, respectively. Among the 74 sera positive with conventional RPR card test and TPHA or FTA-ABS IgG test, 55 were positive with Mediace test. The specificity of Mediace RPR test on blood donors was 97.2%. Among the 302 sera positive with Mediace RPR test, 137 sera (45.4%) were negative by RPR card and TPHA/FTA-ABS IgG tests. Although the sensitivities of Mediace RPR were good for primary and secondary syphilis, due to its high negative rate of Mediace RPR over the conventional RPR positive samples, further studies are necessary whether it can replace conventional nontreponemal test for screening purpose. Moreover, in view of the high false positive rate, positive results by Mediace RPR test should be confirmed with treponemal tests.

  5. Reduction of false positives in the detection of architectural distortion in mammograms by using a geometrically constrained phase portrait model

    International Nuclear Information System (INIS)

    Ayres, Fabio J.; Rangayyan, Rangaraj M.

    2007-01-01

    Objective One of the commonly missed signs of breast cancer is architectural distortion. We have developed techniques for the detection of architectural distortion in mammograms, based on the analysis of oriented texture through the application of Gabor filters and a linear phase portrait model. In this paper, we propose constraining the shape of the general phase portrait model as a means to reduce the false-positive rate in the detection of architectural distortion. Material and methods The methods were tested with one set of 19 cases of architectural distortion and 41 normal mammograms, and with another set of 37 cases of architectural distortion. Results Sensitivity rates of 84% with 4.5 false positives per image and 81% with 10 false positives per image were obtained for the two sets of images. Conclusion The adoption of a constrained phase portrait model with a symmetric matrix and the incorporation of its condition number in the analysis resulted in a reduction in the false-positive rate in the detection of architectural distortion. The proposed techniques, dedicated for the detection and localization of architectural distortion, should lead to efficient detection of early signs of breast cancer. (orig.)

  6. False-Positive TDxFLx urine Amphetamine/Metamphetamine II assay from Ofloxacin

    International Nuclear Information System (INIS)

    Nomier, Mahmoud A.; Al-Huseini, Hani K.

    2004-01-01

    Immunoassays are widely used in testing urine for illicit drugs. Ofloaxcin and a number of other quinolones were found to induce false-positive opiates (OP) urine immunoassays. This can result in misleading conclusions in the concept of drug abuse The aim of present study was to evaluate the effects of ofloxacin in theraputic doses on the induction of false-positive urine immunoassays for common drugs of abuse in healthy male volunteers. The study was conducted on 6 healthy male volunteers, aging between 35-45 years. Two doses of 400 mg ofloxacin each, were given orally to each volunteer at 12 hours interval and urine samples were collected before ofloaxcin administration and 5-7.5 hours after the second dose. Urine samples were subjected for OP, amphetamine/methamphetamine II (AM/MA II), cocaine and cannabinoids assays on TDxFLx analyzer. Ofloxacin produced significant increase (P cutoff) for AM/MA II assays, were found in all volunteers after ofloaxcin administration. The study recomends strongly the confirmation of positive urine immunoassay results for drugs of abuseby a more specific methodology e.g. gas chromatography/ mass spectroscopy (GC/MS). (author)

  7. False positive of the scintigraphy with octreoscan: a diagnosis of elimination; Faux positif de la scintigraphie a l'octreoscan: un diagnostic d'elimination

    Energy Technology Data Exchange (ETDEWEB)

    Charrier, N.; Brenot-Rossi, I.; Chuto, G.; Giovannini, M.; Delpero, J.R. [Institut Paoli-Calmettes, Marseille, (France)

    2009-05-15

    The imaging of receptors with somatostatin analogs by the pentetreotide-indium 111 (octreoscan) allows the detection of endocrine tumors essentially according to the density of S.S.T.2 receptors at the tumor level. The sensitivity of octreoscan for the detection of intestine endocrine tumors is included between 80 and 100% in the different studies. The clinical case presented here enlightens a case of false positive.We concluded to a physiological elimination of pentetreotide-indium 111 with intra pancreatic biliary stasis (perhaps a dysfunction of sphincter of ampulla of bile duct) and to the lack of tumor centre. It is here a diagnosis of elimination, supported by the different results of examination. all normal. This case of false positive induced expensive and traumatic explorations for the patient. (N.C.)

  8. A high false positive rate for Kepler planetary candidates of giant stars using asterodensity profiling

    International Nuclear Information System (INIS)

    Sliski, David H.; Kipping, David M.

    2014-01-01

    Asterodensity profiling (AP) is a relatively new technique for studying transit light curves. By comparing the mean stellar density derived from the transit light curve to that found through an independent method, AP provides information on several useful properties such as orbital eccentricity and blended light. We present an AP survey of 41 Kepler Objects of Interest (KOIs), with a single transiting candidate, for which the target star's mean stellar density has been measured using asteroseismology. The ensemble distribution of the AP measurements for the 31 dwarf stars in our sample shows excellent agreement with the spread expected if the KOIs were genuine and have realistic eccentricities. In contrast, the same test for the 10 giants in our sample reveals significant incompatibility at >4σ confidence. While extreme eccentricities could be invoked, this hypothesis requires four of the KOIs to contact their host star at periastron passage, including the recently claimed confirmation of Kepler-91b. After carefully examining several hypotheses, we conclude that the most plausible explanation is that the transiting objects orbit a different star to that measured with asteroseismology—cases we define as false-positives. Based on the AP distribution, we estimate a false-positive rate (FPR) for Kepler's giant stars with a single transiting object of FPR ≅ 70% ± 30%.

  9. Potential for false positive HIV test results with the serial rapid HIV testing algorithm

    Directory of Open Access Journals (Sweden)

    Baveewo Steven

    2012-03-01

    Full Text Available Abstract Background Rapid HIV tests provide same-day results and are widely used in HIV testing programs in areas with limited personnel and laboratory infrastructure. The Uganda Ministry of Health currently recommends the serial rapid testing algorithm with Determine, STAT-PAK, and Uni-Gold for diagnosis of HIV infection. Using this algorithm, individuals who test positive on Determine, negative to STAT-PAK and positive to Uni-Gold are reported as HIV positive. We conducted further testing on this subgroup of samples using qualitative DNA PCR to assess the potential for false positive tests in this situation. Results Of the 3388 individuals who were tested, 984 were HIV positive on two consecutive tests, and 29 were considered positive by a tiebreaker (positive on Determine, negative on STAT-PAK, and positive on Uni-Gold. However, when the 29 samples were further tested using qualitative DNA PCR, 14 (48.2% were HIV negative. Conclusion Although this study was not primarily designed to assess the validity of rapid HIV tests and thus only a subset of the samples were retested, the findings show a potential for false positive HIV results in the subset of individuals who test positive when a tiebreaker test is used in serial testing. These findings highlight a need for confirmatory testing for this category of individuals.

  10. Potential for false positive HIV test results with the serial rapid HIV testing algorithm.

    Science.gov (United States)

    Baveewo, Steven; Kamya, Moses R; Mayanja-Kizza, Harriet; Fatch, Robin; Bangsberg, David R; Coates, Thomas; Hahn, Judith A; Wanyenze, Rhoda K

    2012-03-19

    Rapid HIV tests provide same-day results and are widely used in HIV testing programs in areas with limited personnel and laboratory infrastructure. The Uganda Ministry of Health currently recommends the serial rapid testing algorithm with Determine, STAT-PAK, and Uni-Gold for diagnosis of HIV infection. Using this algorithm, individuals who test positive on Determine, negative to STAT-PAK and positive to Uni-Gold are reported as HIV positive. We conducted further testing on this subgroup of samples using qualitative DNA PCR to assess the potential for false positive tests in this situation. Of the 3388 individuals who were tested, 984 were HIV positive on two consecutive tests, and 29 were considered positive by a tiebreaker (positive on Determine, negative on STAT-PAK, and positive on Uni-Gold). However, when the 29 samples were further tested using qualitative DNA PCR, 14 (48.2%) were HIV negative. Although this study was not primarily designed to assess the validity of rapid HIV tests and thus only a subset of the samples were retested, the findings show a potential for false positive HIV results in the subset of individuals who test positive when a tiebreaker test is used in serial testing. These findings highlight a need for confirmatory testing for this category of individuals.

  11. A FALSE POSITIVE FOR OCEAN GLINT ON EXOPLANETS: THE LATITUDE-ALBEDO EFFECT

    International Nuclear Information System (INIS)

    Cowan, Nicolas B.; Abbot, Dorian S.; Voigt, Aiko

    2012-01-01

    Identifying liquid water on the surface of planets is a high priority, as this traditionally defines habitability. One proposed signature of oceans is specular reflection ('glint'), which increases the apparent albedo of a planet at crescent phases. We post-process a global climate model of an Earth-like planet to simulate reflected light curves. Significantly, we obtain glint-like phase variations even though we do not include specular reflection in our model. This false positive is the product of two generic properties: (1) for modest obliquities, a planet's poles receive less orbit-averaged stellar flux than its equator, so the poles are more likely to be covered in highly reflective snow and ice; and (2) we show that reflected light from a modest-obliquity planet at crescent phases probes higher latitudes than at gibbous phases, therefore a planet's apparent albedo will naturally increase at crescent phase. We suggest that this 'latitude-albedo effect' will operate even for large obliquities: in that case the equator receives less orbit-averaged flux than the poles, and the equator is preferentially sampled at crescent phase. Using rotational and orbital color variations to map the surfaces of directly imaged planets and estimate their obliquity will therefore be a necessary pre-condition for properly interpreting their reflected phase variations. The latitude-albedo effect is a particularly convincing glint false positive for zero-obliquity planets, and such worlds are not amenable to latitudinal mapping. This effect severely limits the utility of specular reflection for detecting oceans on exoplanets.

  12. PRE-SPECTROSCOPIC FALSE-POSITIVE ELIMINATION OF KEPLER PLANET CANDIDATES

    International Nuclear Information System (INIS)

    Batalha, Natalie M.; Rowe, Jason F.; Borucki, William J.; Koch, David G.; Lissauer, Jack J.; Gilliland, Ronald L.; Jenkins, Jon J.; Caldwell, Douglas; Dunham, Edward W.; Gautier, Thomas N.; Howell, Steve B.; Latham, David W.; Marcy, Geoff W.; Prsa, Andrej

    2010-01-01

    Ten days of commissioning data (Quarter 0) and 33 days of science data (Quarter 1) yield instrumental flux time series of ∼150,000 stars that were combed for transit events, termed threshold crossing events(TCE), each having a total detection statistic above 7.1σ. TCE light curves are modeled as star+planet systems. Those returning a companion radius smaller than 2R J are assigned a Kepler Object of Interest (KOI) number. The raw flux, pixel flux, and flux-weighted centroids of every KOI are scrutinized to assess the likelihood of being an astrophysical false positive versus the likelihood of being a planetary companion. This vetting using Kepler data is referred to as data validation (DV). Herein, we describe the DV metrics and graphics used to identify viable planet candidates amongst the KOIs. Light curve modeling tests for (1) the difference in depth of the odd- versus even-numbered transits, (2) evidence of ellipsoidal variations, and (3) evidence of a secondary eclipse event at phase = 0.5. Flux-weighted centroids are used to test for signals correlated with transit events with a magnitude and direction indicative of a background eclipsing binary. Centroid time series are complimented by analysis of images taken in-transit versus out-of-transit, the difference often revealing the pixel contributing the most to the flux change during transit. Examples are shown to illustrate each test. Candidates passing DV are submitted to ground-based observers for further false-positive elimination or confirmation/characterization.

  13. Commercial radioimmunoassay for beta subunit of human chorionic gonadotropin: falsely positive determinations due to elevated serum luteinizing hormone

    International Nuclear Information System (INIS)

    Fowler, J.E. Jr.; Platoff, G.E.; Kubrock, C.A.; Stuzman, R.E.

    1982-01-01

    Among 17 men who had received seemingly curative treatment for unilateral non-seminomatous germ cell tumors for the testis and who had consistently normal serum human chorionic gonadotropin (HCG) levels at a reference laboratory, 7 (41%) had at least one falsely positive commercial serum HCG determination. To investigate the cause of these falsely positive determinations the authors measured the cross reactivity of luteinizing hormone (LH) and follicle stimulating hormone (FSH) standards in the commercial HCG assay, and studied the relationships between commercial HCG levels and serum LH levels, serum FSH levels and gonadal status in men with and without normal gonadal function. The falsely positive HCG determinations appeared to be due to elevated serum LH levels and cross reactivity of LH in the commercial HCG assay because: 1) there was substantial cross reactivity of the LH standards in the commercial assay, 2) the serum LH was elevated in four of six men with solitary testes, 3) there was a striking correlation between elevated serum LH levels and falsely elevated commercial HCG levels in ten men with solitary or absent testes, and 4) there were no falsely positive HCG determinations in 13 normal men but there were falsely positive HCG determinations in seven of ten anorchid men

  14. Accurate decisions in an uncertain world: collective cognition increases true positives while decreasing false positives

    NARCIS (Netherlands)

    Wolf, M.; Kurvers, R.H.J.M.; Ward, A.J.W.; Krause, S.; Krause, J.

    2013-01-01

    In a wide range of contexts, including predator avoidance, medical decision-making and security screening, decision accuracy is fundamentally constrained by the trade-off between true and false positives. Increased true positives are possible only at the cost of increased false positives;

  15. Participation behaviour following a false positive test in the Copenhagen mammography screening programme

    DEFF Research Database (Denmark)

    Andersen, Sune Bangsbøll; Vejborg, Ilse; von Euler-Chelpin, My

    2008-01-01

    women experiencing a negative screening test, regardless of whether the false positive statement was given following assessment or following surgery. The benign to malignant biopsy ratio, comparing the type B false positives to the true positives, was by the fifth round well below the desirable level...

  16. False-positive results in mammographic screening for breast cancer in Europe

    DEFF Research Database (Denmark)

    Hofvind, Solveig; Ponti, Antonio; Patnick, Julietta

    2012-01-01

    To estimate the cumulative risk of a false-positive screening result in European mammographic screening programmes, and examine the rates and procedures of further assessment.......To estimate the cumulative risk of a false-positive screening result in European mammographic screening programmes, and examine the rates and procedures of further assessment....

  17. False-positive findings in Cochrane meta-analyses with and without application of trial sequential analysis

    DEFF Research Database (Denmark)

    Imberger, Georgina; Thorlund, Kristian; Gluud, Christian

    2016-01-01

    outcome, a negative result and sufficient power. We defined a negative result as one where the 95% CI for the effect included 1.00, a positive result as one where the 95% CI did not include 1.00, and sufficient power as the required information size for 80% power, 5% type 1 error, relative risk reduction...... of 10% or number needed to treat of 100, and control event proportion and heterogeneity taken from the included studies. We re-conducted the meta-analyses, using conventional cumulative techniques, to measure how many false positives would have occurred if these meta-analyses had been updated after each...... new trial. For each false positive, we performed TSA, using three different approaches. RESULTS: We screened 4736 systematic reviews to find 100 meta-analyses that fulfilled our inclusion criteria. Using conventional cumulative meta-analysis, false positives were present in seven of the meta...

  18. On minimizing assignment errors and the trade-off between false positives and negatives in parentage analysis

    KAUST Repository

    Harrison, Hugo B.

    2013-11-04

    Genetic parentage analyses provide a practical means with which to identify parent-offspring relationships in the wild. In Harrison et al.\\'s study (2013a), we compare three methods of parentage analysis and showed that the number and diversity of microsatellite loci were the most important factors defining the accuracy of assignments. Our simulations revealed that an exclusion-Bayes theorem method was more susceptible to false-positive and false-negative assignments than other methods tested. Here, we analyse and discuss the trade-off between type I and type II errors in parentage analyses. We show that controlling for false-positive assignments, without reporting type II errors, can be misleading. Our findings illustrate the need to estimate and report both the rate of false-positive and false-negative assignments in parentage analyses. © 2013 John Wiley & Sons Ltd.

  19. On minimizing assignment errors and the trade-off between false positives and negatives in parentage analysis

    KAUST Repository

    Harrison, Hugo B.; Saenz Agudelo, Pablo; Planes, Serge; Jones, Geoffrey P.; Berumen, Michael L.

    2013-01-01

    Genetic parentage analyses provide a practical means with which to identify parent-offspring relationships in the wild. In Harrison et al.'s study (2013a), we compare three methods of parentage analysis and showed that the number and diversity of microsatellite loci were the most important factors defining the accuracy of assignments. Our simulations revealed that an exclusion-Bayes theorem method was more susceptible to false-positive and false-negative assignments than other methods tested. Here, we analyse and discuss the trade-off between type I and type II errors in parentage analyses. We show that controlling for false-positive assignments, without reporting type II errors, can be misleading. Our findings illustrate the need to estimate and report both the rate of false-positive and false-negative assignments in parentage analyses. © 2013 John Wiley & Sons Ltd.

  20. Decisions to shoot in a weapon identification task: The influence of cultural stereotypes and perceived threat on false positive errors.

    Science.gov (United States)

    Fleming, Kevin K; Bandy, Carole L; Kimble, Matthew O

    2010-01-01

    The decision to shoot a gun engages executive control processes that can be biased by cultural stereotypes and perceived threat. The neural locus of the decision to shoot is likely to be found in the anterior cingulate cortex (ACC), where cognition and affect converge. Male military cadets at Norwich University (N=37) performed a weapon identification task in which they made rapid decisions to shoot when images of guns appeared briefly on a computer screen. Reaction times, error rates, and electroencephalogram (EEG) activity were recorded. Cadets reacted more quickly and accurately when guns were primed by images of Middle-Eastern males wearing traditional clothing. However, cadets also made more false positive errors when tools were primed by these images. Error-related negativity (ERN) was measured for each response. Deeper ERNs were found in the medial-frontal cortex following false positive responses. Cadets who made fewer errors also produced deeper ERNs, indicating stronger executive control. Pupil size was used to measure autonomic arousal related to perceived threat. Images of Middle-Eastern males in traditional clothing produced larger pupil sizes. An image of Osama bin Laden induced the largest pupil size, as would be predicted for the exemplar of Middle East terrorism. Cadets who showed greater increases in pupil size also made more false positive errors. Regression analyses were performed to evaluate predictions based on current models of perceived threat, stereotype activation, and cognitive control. Measures of pupil size (perceived threat) and ERN (cognitive control) explained significant proportions of the variance in false positive errors to Middle-Eastern males in traditional clothing, while measures of reaction time, signal detection response bias, and stimulus discriminability explained most of the remaining variance.

  1. False positive rate of carbon monoxide saturation by pulse oximetry of emergency department patients.

    Science.gov (United States)

    Weaver, Lindell K; Churchill, Susan K; Deru, Kayla; Cooney, Darryl

    2013-02-01

    Symptoms of carbon monoxide (CO) poisoning are non-specific. Diagnosis requires suspicion of exposure, confirmed by measuring ambient CO levels or carboxyhemoglobin (COHb). An FDA-approved pulse oximeter (Rad-57) can measure CO saturation (S(pCO)). The device accuracy has implications for clinical decision-making. From April 1 to August 15, 2008, study personnel measured S(pCO) and documented demographic factors at time of clinical blood draw, in a convenience sample of 1,363 subjects presenting to the emergency department at Intermountain Medical Center, Murray, Utah. The technician then assayed COHb. COHb and S(pCO) values were compared by subject; false positive or negative values were defined as S(pCO) at least 3 percentage points greater or less than COHb level, reported by the manufacturer to be ± 1 SD in performance. In 1,363 subjects, 613 (45%) were male, 1,141 (84%) were light-skinned, 14 in shock, 4 with CO poisoning, and 122 (9%) met the criteria for a false positive value (range 3-19 percentage points), while 247 (18%) met the criteria for a false negative value (-13 to -3 percentage points). Risks for a false positive S(pCO) reading included being female and having a lower perfusion index. Methemoglobin, body temperature, and blood pressure also appear to influence the S(pCO) accuracy. There was variability among monitors, possibly related to technician technique, as rotation of monitors among technicians was not enforced. While the Rad-57 pulse oximeter functioned within the manufacturer's specifications, clinicians using the Rad-57 should expect some S(pCO) readings to be significantly higher or lower than COHb measurements, and should not use S(pCO) to direct triage or patient management. An elevated S(pCO) could broaden the diagnosis of CO poisoning in patients with non-specific symptoms. However, a negative S(pCO) level in patients suspected of having CO poisoning should never rule out CO poisoning, and should always be confirmed by COHb. © 2013

  2. The probability of false positives in zero-dimensional analyses of one-dimensional kinematic, force and EMG trajectories.

    Science.gov (United States)

    Pataky, Todd C; Vanrenterghem, Jos; Robinson, Mark A

    2016-06-14

    A false positive is the mistake of inferring an effect when none exists, and although α controls the false positive (Type I error) rate in classical hypothesis testing, a given α value is accurate only if the underlying model of randomness appropriately reflects experimentally observed variance. Hypotheses pertaining to one-dimensional (1D) (e.g. time-varying) biomechanical trajectories are most often tested using a traditional zero-dimensional (0D) Gaussian model of randomness, but variance in these datasets is clearly 1D. The purpose of this study was to determine the likelihood that analyzing smooth 1D data with a 0D model of variance will produce false positives. We first used random field theory (RFT) to predict the probability of false positives in 0D analyses. We then validated RFT predictions via numerical simulations of smooth Gaussian 1D trajectories. Results showed that, across a range of public kinematic, force/moment and EMG datasets, the median false positive rate was 0.382 and not the assumed α=0.05, even for a simple two-sample t test involving N=10 trajectories per group. The median false positive rate for experiments involving three-component vector trajectories was p=0.764. This rate increased to p=0.945 for two three-component vector trajectories, and to p=0.999 for six three-component vectors. This implies that experiments involving vector trajectories have a high probability of yielding 0D statistical significance when there is, in fact, no 1D effect. Either (a) explicit a priori identification of 0D variables or (b) adoption of 1D methods can more tightly control α. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. PIPIDA scintigraphy for cholecystitis: false positives in alcoholism and total parenteral nutrition

    International Nuclear Information System (INIS)

    Shuman, W.P.; Gibbs, P.; Rudd, T.G.; Mack, L.A.

    1982-01-01

    A review of gallbladder scintigraphy in patients with potentially compromised hepatobiliary function revealed two groups in whom cholecystitis might be mistakenly diagnosed. In 200 consecutive hospitalized patients studied with technetium-99m-PIPIDA for acute cholecystitis or cholestasis, there were 41 alcoholics and 17 patients on total parenteral nutrition. In 60% of the alcoholics and 92% of those on parenteral nutrition, absent or delayed visualization of the gallbladder occurred without physical or clinical evidence of cholecystitis. A cholecystagogue, sincalide, did not prevent the false-positive features which presumably are due to altered bile flow kinetics related to alcoholism and parenteral nutrition. Four patients on parenteral nutrition undergoing cholecystectomy for suspected cholecystitis had normal gallbladders filled with jellylike viscous thick bile. A positive (nonvisualized or delayed visualized) gallbladder PIPIDA scintigram in these two populations should not be interpreted as indicating a need for cholecystectomy

  4. Risk of breast cancer after false-positive results in mammographic screening

    DEFF Research Database (Denmark)

    Roman, Marta; Castells, Xavier; Hofvind, Solveig

    2016-01-01

    risk (RR) of screen-detected cancer for women with false-positive versus negative results. We analyzed information from 1,935,093 women 50–69 years who underwent 6,094,515 screening exams. During an average 5.8 years of follow-up, 230,609 (11.9%) women received a false-positive result and 27,849 (1......Women with false-positive results are commonly referred back to routine screening. Questions remain regarding their long-term outcome of breast cancer. We assessed the risk of screen-detected breast cancer in women with false-positive results. We conducted a joint analysis using individual level.......4%) were diagnosed with screen-detected cancer. The adjusted RR of screen-detected cancer after a false-positive result was 2.01 (95% CI: 1.93–2.09). Women who tested false-positive at first screen had a RR of 1.86 (95% CI: 1.77–1.96), whereas those who tested false-positive at third screening had a RR...

  5. Factors associated with false-positive self-reported adherence to antihypertensive drugs.

    Science.gov (United States)

    Tedla, Y G; Bautista, L E

    2017-05-01

    Self-reported medication adherence is known to overestimate true adherence. However, little is known about patient factors that may contribute to the upward bias in self-reported medication adherence. The objective of this study is to examine whether demographic, behavioral, medication and mood factors are associated with being a false-positive self-reported adherer (FPA) to antihypertensive drug treatment. We studied 175 patients (mean age: 50 years; 57% men) from primary-care clinics starting antihypertensive drug treatment. Self-reported adherence (SRA) was measured with the Medication Adherence Report Scale (MARS) and by the number of drug doses missed in the previous week/month, and compared with pill count adherence ratio (PCAR) as gold standard. Data on adherence, demographic, behavioral, medication and mood factors were collected at baseline and every 3 months up to 1 year. FPA was defined as being a non-adherer by PCAR and an adherer by self-report. Mixed effect logistic regression was used for the analysis. Twenty percent of participants were FPA. Anxiety increased (odds ratio (OR): 3.00; P=0.01), whereas smoking (OR: 0.40; P=0.03) and drug side effects (OR: 0.46, P=0.03) decreased the probability for FPA by MARS. Education below high-school completion increased the probability of being an FPA as measured by missing doses in the last month (OR: 1.66; P=0.04) and last week (OR: 1.88; P=0.02). The validity of SRA varies significantly according to drug side effects, behavioral factors and patient's mood. Careful consideration should be given to the use of self-reported measures of adherence among patients likely to be false-positive adherers.

  6. Inflammatory disorders mimicking periprosthetic joint infections may result in false positive α-defensin.

    Science.gov (United States)

    Plate, Andreas; Stadler, Laura; Sutter, Reto; Anagnostopoulos, Alexia; Frustaci, Dario; Zbinden, Reinhard; Fucentese, Sandro F; Zinkernagel, Annelies S; Zingg, Patrick O; Achermann, Yvonne

    2018-02-26

    The antimicrobial peptide α-defensin has recently been introduced as potential "single" biomarker with a high sensitivity and specificity for the preoperative diagnosis of periprosthetic joint infections (PJIs). However, most studies assessed the benefits of the test with exclusion of patients with rheumatic diseases. We aimed to evaluate the α-defensin test in a cohort study without exclusion of cases with inflammatory diseases. Between June 2016 and June 2017, we prospectively included cases with a suspected PJI and an available lateral flow test α-defensin (Synovasure®) in synovial fluid. We compared the test result to the diagnostic criteria for PJIs published by an International Consensus Group in 2013. We included 109 cases (49 hips, 60 knees) in which preoperative α-defensin tests had been performed. Thereof, 20 PJIs (16 hips, 4 knees) were diagnosed. Preoperative α-defensin tests were positive in 25 cases (22.9%) with a test sensitivity and specificity of 90% and 92.1% (95% confidence interval [CI], 68.3 - 98.8% and 84.5 - 96.8%, respectively), and a high negative predictive value of 97.6% (95% CI, 91.7 - 99.4%). We interpreted seven α-defensin tests as false positive, mainly in cases with inflammatory rheumatic diseases, including crystal deposition diseases. A negative synovial α-defensin test can reliably rule out a PJI. However, the test can be false positive in conjunction with an underlying non-infectious inflammatory disease. We therefore propose to use the α-defensin test only in addition to MSIS criteria and assessment for crystals in synovial aspirates. Copyright © 2018. Published by Elsevier Ltd.

  7. Prenatal ultrasound screening: false positive soft markers may alter maternal representations and mother-infant interaction.

    Directory of Open Access Journals (Sweden)

    Sylvie Viaux-Savelon

    Full Text Available In up to 5% of pregnancies, ultrasound screening detects a "soft marker" (SM that places the foetus at risk for a severe abnormality. In most cases, prenatal diagnostic work-up rules out a severe defect. We aimed to study the effects of false positive SM on maternal emotional status, maternal representations of the infant, and mother-infant interaction.Utilizing an extreme-case prospective case control design, we selected from a group of 244 women undergoing ultrasound, 19 pregnant women whose foetus had a positive SM screening and a reassuring diagnostic work up, and 19 controls without SM matched for age and education. In the third trimester of pregnancy, within one week after delivery, and 2 months postpartum, we assessed anxiety, depression, and maternal representations. Mother-infant interactions were videotaped during feeding within one week after delivery and again at 2 months postpartum and coded blindly using the Coding Interactive Behavior (CIB scales. Anxiety and depression scores were significantly higher at all assessment points in the SM group. Maternal representations were also different between SM and control groups at all study time. Perturbations to early mother-infant interactions were observed in the SM group. These dyads showed greater dysregulation, lower maternal sensitivity, higher maternal intrusive behaviour and higher infant avoidance. Multivariate analysis showed that maternal representation and depression at third trimester predicted mother-infant interaction.False positive ultrasound screenings for SM are not benign and negatively affect the developing maternal-infant attachment. Medical efforts should be directed to minimize as much as possible such false diagnoses, and to limit their psychological adverse consequences.

  8. Buffer substitution in malaria rapid diagnostic tests causes false-positive results

    Directory of Open Access Journals (Sweden)

    Van den Ende Jef

    2010-07-01

    Full Text Available Abstract Background Malaria rapid diagnostic tests (RDTs are kits that generally include 20 to 25 test strips or cassettes, but only a single buffer vial. In field settings, laboratory staff occasionally uses saline, distilled water (liquids for parenteral drugs dilution or tap water as substitutes for the RDT kit's buffer to compensate for the loss of a diluent bottle. The present study assessed the effect of buffer substitution on the RDT results. Methods Twenty-seven RDT brands were run with EDTA-blood samples of five malaria-free subjects, who were negative for rheumatoid factor and antinuclear antibodies. Saline, distilled water and tap water were used as substitute liquids. RDTs were also run with distilled water, without adding blood. Results were compared to those obtained with the RDT kit's buffer and Plasmodium positive samples. Results Only eight cassettes (in four RDT brands showed no control line and were considered invalid. Visible test lines occurred for at least one malaria-free sample and one of the substitutes in 20/27 (74% RDT brands (saline: n = 16; distilled water: n = 17; and tap water: n = 20, and in 15 RDTs which were run with distilled water only. They occurred for all Plasmodium antigens and RDT formats (two-, three- and four-band RDTs. Clearance of the background of the strip was excellent except for saline. The aspects (colour, intensity and crispness of the control and the false-positive test lines were similar to those obtained with the RDT kits' buffer and Plasmodium positive samples. Conclusion Replacement of the RDT kit's dedicated buffer by saline, distilled water and tap water can cause false-positive test results.

  9. Automated detection of masses on whole breast volume ultrasound scanner: false positive reduction using deep convolutional neural network

    Science.gov (United States)

    Hiramatsu, Yuya; Muramatsu, Chisako; Kobayashi, Hironobu; Hara, Takeshi; Fujita, Hiroshi

    2017-03-01

    Breast cancer screening with mammography and ultrasonography is expected to improve sensitivity compared with mammography alone, especially for women with dense breast. An automated breast volume scanner (ABVS) provides the operator-independent whole breast data which facilitate double reading and comparison with past exams, contralateral breast, and multimodality images. However, large volumetric data in screening practice increase radiologists' workload. Therefore, our goal is to develop a computer-aided detection scheme of breast masses in ABVS data for assisting radiologists' diagnosis and comparison with mammographic findings. In this study, false positive (FP) reduction scheme using deep convolutional neural network (DCNN) was investigated. For training DCNN, true positive and FP samples were obtained from the result of our initial mass detection scheme using the vector convergence filter. Regions of interest including the detected regions were extracted from the multiplanar reconstraction slices. We investigated methods to select effective FP samples for training the DCNN. Based on the free response receiver operating characteristic analysis, simple random sampling from the entire candidates was most effective in this study. Using DCNN, the number of FPs could be reduced by 60%, while retaining 90% of true masses. The result indicates the potential usefulness of DCNN for FP reduction in automated mass detection on ABVS images.

  10. Comparison of cumulative false-positive risk of screening mammography in the United States and Denmark

    DEFF Research Database (Denmark)

    Jacobsen, Katja Kemp

    2015-01-01

    INTRODUCTION: In the United States (US), about one-half of women screened with annual mammography have at least one false-positive test after ten screens. The estimate for European women screened ten times biennially is much lower. We evaluate to what extent screening interval, mammogram type......=400,204), between 1991-2012 and 1993-2013, respectively. Model-based cumulative false-positive risks were computed for the entire sample, using two statistical methods (Hubbard Njor) previously used to estimate false-positive risks in the US and Europe. RESULTS: Empirical cumulative risk of at least...... one false-positive test after eight (annual or biennial) screens was 41.9% in BCSC, 16.1% in Copenhagen, and 7.4% in Funen. Variation in screening interval and mammogram type did not explain the differences by country. Using the Hubbard method, the model-based cumulative risks after eight screens...

  11. Look Again: An Investigation of False Positive Detections in Combat Models

    National Research Council Canada - National Science Library

    Wainwright, Ryan K

    2008-01-01

    .... Existing combat models tend to overlook or downplay false positive detections. Signal Detection Theory provides the framework for analysis of an observer's hits, misses, correct rejections, and false alarms...

  12. Risk of breast cancer after false-positive results in mammographic screening.

    Science.gov (United States)

    Román, Marta; Castells, Xavier; Hofvind, Solveig; von Euler-Chelpin, My

    2016-06-01

    Women with false-positive results are commonly referred back to routine screening. Questions remain regarding their long-term outcome of breast cancer. We assessed the risk of screen-detected breast cancer in women with false-positive results. We conducted a joint analysis using individual level data from the population-based screening programs in Copenhagen and Funen in Denmark, Norway, and Spain. Overall, 150,383 screened women from Denmark (1991-2008), 612,138 from Norway (1996-2010), and 1,172,572 from Spain (1990-2006) were included. Poisson regression was used to estimate the relative risk (RR) of screen-detected cancer for women with false-positive versus negative results. We analyzed information from 1,935,093 women 50-69 years who underwent 6,094,515 screening exams. During an average 5.8 years of follow-up, 230,609 (11.9%) women received a false-positive result and 27,849 (1.4%) were diagnosed with screen-detected cancer. The adjusted RR of screen-detected cancer after a false-positive result was 2.01 (95% CI: 1.93-2.09). Women who tested false-positive at first screen had a RR of 1.86 (95% CI: 1.77-1.96), whereas those who tested false-positive at third screening had a RR of 2.42 (95% CI: 2.21-2.64). The RR of breast cancer at the screening test after the false-positive result was 3.95 (95% CI: 3.71-4.21), whereas it decreased to 1.25 (95% CI: 1.17-1.34) three or more screens after the false-positive result. Women with false-positive results had a twofold risk of screen-detected breast cancer compared to women with negative tests. The risk remained significantly higher three or more screens after the false-positive result. The increased risk should be considered when discussing stratified screening strategies. © 2016 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.

  13. False Positive Radioiodinated Metaiodobenzylguanidine (123I-MIBG Uptake in Undifferentiated Adrenal Malignant Tumor

    Directory of Open Access Journals (Sweden)

    Hee Soo Jung

    2015-01-01

    Full Text Available 123I-Metaiodobenzylguanidine (123I-MIBG scintigraphy is a widely used functional imaging tool with a high degree of sensitivity and specificity in diagnosis of pheochromocytoma. However, rare cases of false positive reactions have been reported. A 67-year-old male patient was admitted with epigastric pain. Abdominal computed tomography (CT revealed a heterogeneous left adrenal mass 6 cm in diameter; following hormone testing, 123I-MIBG scintigraphy was performed to determine the presence of pheochromocytoma, which confirmed eccentric uptake by a large left adrenal gland mass. Chest CT and PET-CT confirmed metastatic lymphadenopathy; therefore, endobronchial ultrasound transbronchial needle aspiration was performed. Metastatic carcinoma of unknown origin was suspected from a lymph node biopsy, and surgical resection was performed for definitive diagnosis and correction of excess hormonal secretion. A final diagnosis of undifferentiated adrenal malignant tumor was rendered, instead of histologically malignant pheochromocytoma, despite the uptake of 123I-MIBG demonstrated by scintigraphy.

  14. Psychological effects of false-positive results in expanded newborn screening in China.

    Directory of Open Access Journals (Sweden)

    Wen-Jun Tu

    Full Text Available OBJECTIVES: As more families participate expanded newborn screening for metabolic disorders in China, the overall number of false positives increases. Our goal was to assess the potential impact on parental stress, perceptions of the child's health, and family relationships. METHODS: Parents of 49 infants with false-positive screening results for metabolic disorders in the expanded newborn screening panel were compared with parents of 42 children with normal screening results. Parents first completed structured interview using likert scales, closed and open questions. Parents also completed the parenting stress index. RESULTS: A total of 88 mothers and 41 fathers were interviewed. More mothers in the false-positive group reported that their children required extra parental care (21%, compared with 5% of mothers in the normal-screened group (P<0.001. 39% of mothers in the false-positive group reported that they worry about their child's future development, compared with 10% of mothers in the normal-screened group (P<0.001. Fathers in the false-positive group did not differ from fathers in the normal-screened group in reporting worry about their child's extra care requirements, and their child's future development. Children with false-positive results compared with children with normal results were triple as likely to experience hospitalization (27%vs 9%, respectively; P<0.001. CONCLUSIONS: The results showing false-positive screening results may affect parental stress and the parent-child relationship. Parental stress and anxiety can be reduced with improved education and communication to parents about false-positive results.

  15. Prospective assessment of the false positive rate of the Australian snake venom detection kit in healthy human samples.

    Science.gov (United States)

    Nimorakiotakis, Vasilios Bill; Winkel, Kenneth D

    2016-03-01

    The Snake Venom Detection Kit (SVDK; bioCSL Pty Ltd, Australia) distinguishes venom from the five most medically significant snake immunotypes found in Australia. This study assesses the rate of false positives that, by definition, refers to a positive assay finding in a sample from someone who has not been bitten by a venomous snake. Control unbroken skin swabs, simulated bite swabs and urine specimens were collected from 61 healthy adult volunteers [33 males and 28 females] for assessment. In all controls, simulated bite site and urine samples [a total of 183 tests], the positive control well reacted strongly within one minute and no test wells reacted during the ten minute incubation period. However, in two urine tests, the negative control well gave a positive reaction (indicating an uninterpretable test). A 95% confidence interval for the false positive rate, on a per-patient rate, derived from the findings of this study, would extend from 0% to 6% and, on a per-test basis, it would be 0-2%. It appears to be a very low incidence (0-6%) of intrinsic true false positives for the SVDK. The clinical impresssion of a high SVDK false positive rate may be mostly related to operator error. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

  16. Accurate decisions in an uncertain world: collective cognition increases true positives while decreasing false positives.

    Science.gov (United States)

    Wolf, Max; Kurvers, Ralf H J M; Ward, Ashley J W; Krause, Stefan; Krause, Jens

    2013-04-07

    In a wide range of contexts, including predator avoidance, medical decision-making and security screening, decision accuracy is fundamentally constrained by the trade-off between true and false positives. Increased true positives are possible only at the cost of increased false positives; conversely, decreased false positives are associated with decreased true positives. We use an integrated theoretical and experimental approach to show that a group of decision-makers can overcome this basic limitation. Using a mathematical model, we show that a simple quorum decision rule enables individuals in groups to simultaneously increase true positives and decrease false positives. The results from a predator-detection experiment that we performed with humans are in line with these predictions: (i) after observing the choices of the other group members, individuals both increase true positives and decrease false positives, (ii) this effect gets stronger as group size increases, (iii) individuals use a quorum threshold set between the average true- and false-positive rates of the other group members, and (iv) individuals adjust their quorum adaptively to the performance of the group. Our results have broad implications for our understanding of the ecology and evolution of group-living animals and lend themselves for applications in the human domain such as the design of improved screening methods in medical, forensic, security and business applications.

  17. Distinguishing Binders from False Positives by Free Energy Calculations: Fragment Screening Against the Flap Site of HIV Protease

    Science.gov (United States)

    2015-01-01

    Molecular docking is a powerful tool used in drug discovery and structural biology for predicting the structures of ligand–receptor complexes. However, the accuracy of docking calculations can be limited by factors such as the neglect of protein reorganization in the scoring function; as a result, ligand screening can produce a high rate of false positive hits. Although absolute binding free energy methods still have difficulty in accurately rank-ordering binders, we believe that they can be fruitfully employed to distinguish binders from nonbinders and reduce the false positive rate. Here we study a set of ligands that dock favorably to a newly discovered, potentially allosteric site on the flap of HIV-1 protease. Fragment binding to this site stabilizes a closed form of protease, which could be exploited for the design of allosteric inhibitors. Twenty-three top-ranked protein–ligand complexes from AutoDock were subject to the free energy screening using two methods, the recently developed binding energy analysis method (BEDAM) and the standard double decoupling method (DDM). Free energy calculations correctly identified most of the false positives (≥83%) and recovered all the confirmed binders. The results show a gap averaging ≥3.7 kcal/mol, separating the binders and the false positives. We present a formula that decomposes the binding free energy into contributions from the receptor conformational macrostates, which provides insights into the roles of different binding modes. Our binding free energy component analysis further suggests that improving the treatment for the desolvation penalty associated with the unfulfilled polar groups could reduce the rate of false positive hits in docking. The current study demonstrates that the combination of docking with free energy methods can be very useful for more accurate ligand screening against valuable drug targets. PMID:25189630

  18. Evaluation of positive and false-positive results in syphilis screening of blood donors in Rio de Janeiro, Brazil.

    Science.gov (United States)

    Sandes, V S; Silva, S G C; Motta, I J F; Velarde, L G C; de Castilho, S R

    2017-06-01

    We propose to analyse the positive and false-positive results of treponemal and nontreponemal tests in blood donors from Brazil and to evaluate possible factors associated with the results of treponemal tests. Treponemal tests have been used widely for syphilis screening in blood banks. The introduction of these tests in donor screening has caused an impact and a loss of donors who need to be assessed. This was a retrospective cross-sectional study of syphilis screening and confirmatory test results of blood donors that were obtained before and after adopting a chemiluminescent immunoassay (CLIA). A comparative analysis was performed using a second sample drawn from positive donors. The possible factors associated with CLIA-positive or CLIA-false-positive results were investigated in a subgroup. Statistical tests were used to compare the proportions and adjusted estimates of association. The reactivity rate increased from 1·01% (N = 28 158) to 2·66% (N = 25 577) after introducing the new test. Among Venereal Disease Research Laboratory (VDRL)- and CLIA-confirmed results, the false-positive rates were 40·5% (N = 180) and 37·4% (N = 359), respectively (P = 0·5266). Older donors (OR = 1·04; P = 0·0010) and donors with lower education levels (OR = 6·59; P = 0·0029) were associated with a higher risk of positivity for syphilis. CLIA represents an improvement in blood bank serological screening. However, its use in a healthy population appears to result in high rates of false positives. Identifying which characteristics can predict false positives, however, remains a challenge. © 2017 British Blood Transfusion Society.

  19. Detecting and avoiding likely false-positive findings - a practical guide.

    Science.gov (United States)

    Forstmeier, Wolfgang; Wagenmakers, Eric-Jan; Parker, Timothy H

    2017-11-01

    Recently there has been a growing concern that many published research findings do not hold up in attempts to replicate them. We argue that this problem may originate from a culture of 'you can publish if you found a significant effect'. This culture creates a systematic bias against the null hypothesis which renders meta-analyses questionable and may even lead to a situation where hypotheses become difficult to falsify. In order to pinpoint the sources of error and possible solutions, we review current scientific practices with regard to their effect on the probability of drawing a false-positive conclusion. We explain why the proportion of published false-positive findings is expected to increase with (i) decreasing sample size, (ii) increasing pursuit of novelty, (iii) various forms of multiple testing and researcher flexibility, and (iv) incorrect P-values, especially due to unaccounted pseudoreplication, i.e. the non-independence of data points (clustered data). We provide examples showing how statistical pitfalls and psychological traps lead to conclusions that are biased and unreliable, and we show how these mistakes can be avoided. Ultimately, we hope to contribute to a culture of 'you can publish if your study is rigorous'. To this end, we highlight promising strategies towards making science more objective. Specifically, we enthusiastically encourage scientists to preregister their studies (including a priori hypotheses and complete analysis plans), to blind observers to treatment groups during data collection and analysis, and unconditionally to report all results. Also, we advocate reallocating some efforts away from seeking novelty and discovery and towards replicating important research findings of one's own and of others for the benefit of the scientific community as a whole. We believe these efforts will be aided by a shift in evaluation criteria away from the current system which values metrics of 'impact' almost exclusively and towards a system

  20. Reducing false-positive incidental findings with ensemble genotyping and logistic regression based variant filtering methods.

    Science.gov (United States)

    Hwang, Kyu-Baek; Lee, In-Hee; Park, Jin-Ho; Hambuch, Tina; Choe, Yongjoon; Kim, MinHyeok; Lee, Kyungjoon; Song, Taemin; Neu, Matthew B; Gupta, Neha; Kohane, Isaac S; Green, Robert C; Kong, Sek Won

    2014-08-01

    As whole genome sequencing (WGS) uncovers variants associated with rare and common diseases, an immediate challenge is to minimize false-positive findings due to sequencing and variant calling errors. False positives can be reduced by combining results from orthogonal sequencing methods, but costly. Here, we present variant filtering approaches using logistic regression (LR) and ensemble genotyping to minimize false positives without sacrificing sensitivity. We evaluated the methods using paired WGS datasets of an extended family prepared using two sequencing platforms and a validated set of variants in NA12878. Using LR or ensemble genotyping based filtering, false-negative rates were significantly reduced by 1.1- to 17.8-fold at the same levels of false discovery rates (5.4% for heterozygous and 4.5% for homozygous single nucleotide variants (SNVs); 30.0% for heterozygous and 18.7% for homozygous insertions; 25.2% for heterozygous and 16.6% for homozygous deletions) compared to the filtering based on genotype quality scores. Moreover, ensemble genotyping excluded > 98% (105,080 of 107,167) of false positives while retaining > 95% (897 of 937) of true positives in de novo mutation (DNM) discovery in NA12878, and performed better than a consensus method using two sequencing platforms. Our proposed methods were effective in prioritizing phenotype-associated variants, and an ensemble genotyping would be essential to minimize false-positive DNM candidates. © 2014 WILEY PERIODICALS, INC.

  1. Skin irritation, false positives and the local lymph node assay: a guideline issue?

    Science.gov (United States)

    Basketter, David A; Kimber, Ian

    2011-10-01

    Since the formal validation and regulatory acceptance of the local lymph node assay (LLNA) there have been commentaries suggesting that the irritant properties of substances can give rise to false positives. As toxicology aspires to progress rapidly towards the age of in vitro alternatives, it is of increasing importance that issues relating to assay selectivity and performance are understood fully, and that true false positive responses are distinguished clearly from those that are simply unpalatable. In the present review, we have focused on whether skin irritation per se is actually a direct cause of true false positive results in the LLNA. The body of published work has been examined critically and considered in relation to our current understanding of the mechanisms of skin irritation and skin sensitisation. From these analyses it is very clear that, of itself, skin irritation is not a cause of false positive results. The corollary is, therefore, that limiting test concentrations in the LLNA for the purpose of avoiding skin irritation may lead, unintentionally, to false negatives. Where a substance is a true false positive in the LLNA, the classic example being sodium lauryl sulphate, explanations for that positivity will have to reach beyond the seductive, but incorrect, recourse to its skin irritation potential. Copyright © 2011 Elsevier Inc. All rights reserved.

  2. Algorithm of reducing the false positives in IDS based on correlation Analysis

    Science.gov (United States)

    Liu, Jianyi; Li, Sida; Zhang, Ru

    2018-03-01

    This paper proposes an algorithm of reducing the false positives in IDS based on correlation Analysis. Firstly, the algorithm analyzes the distinguishing characteristics of false positives and real alarms, and preliminary screen the false positives; then use the method of attribute similarity clustering to the alarms and further reduces the amount of alarms; finally, according to the characteristics of multi-step attack, associated it by the causal relationship. The paper also proposed a reverse causation algorithm based on the attack association method proposed by the predecessors, turning alarm information into a complete attack path. Experiments show that the algorithm simplifies the number of alarms, improve the efficiency of alarm processing, and contribute to attack purposes identification and alarm accuracy improvement.

  3. Categorizing Mistaken False Positives in Regulation of Human and Environmental Health

    DEFF Research Database (Denmark)

    Hansen, Steffen Foss; Krayer von Krauss, Martin Paul; Tickner, J.A.

    2007-01-01

    One of the concerns often voiced by critics of the precautionary principle is that a widespread regulatory application of the principle will lead to a large number of false positives (i.e., over-regulation of minor risks and regulation of nonexisting risks). The present article proposes a general......," including: real risks, "The jury is still out," nonregulated proclaimed risks, "Too narrow a definition of risk," and risk-risk tradeoffs. These categories are defined and examples are presented in order to illustrate their key characteristics. On the basis of our analysis, we were able to identify only...... four cases that could be defined as regulatory false positives in the light of today's knowledge and recognized uncertainty: the Southern Corn Leaf Blight, the Swine Flu, Saccharin, and Food Irradiation in relation to consumer health. We conclude that concerns about false positives do not represent...

  4. The cumulative risk of false-positive screening results across screening centres in the Norwegian Breast Cancer Screening Program

    Energy Technology Data Exchange (ETDEWEB)

    Roman, M., E-mail: Marta.Roman@kreftregisteret.no [Cancer Registry of Norway, Oslo (Norway); Department of Women and Children’s Health, Oslo University Hospital, Oslo (Norway); Skaane, P., E-mail: PERSK@ous-hf.no [Department of Radiology, Oslo University Hospital Ullevaal, University of Oslo, Oslo (Norway); Hofvind, S., E-mail: Solveig.Hofvind@kreftregisteret.no [Cancer Registry of Norway, Oslo (Norway); Oslo and Akershus University College of Applied Sciences, Faculty of Health Science, Oslo (Norway)

    2014-09-15

    Highlights: • We found variation in early performance measures across screening centres. • Radiologists’ performance may play a key role in the variability. • Potential to improve the effectiveness of breast cancer screening programs. • Continuous surveillance of screening centres and radiologists is essential. - Abstract: Background: Recall for assessment in mammographic screening entails an inevitable number of false-positive screening results. This study aimed to investigate the variation in the cumulative risk of a false positive screening result and the positive predictive value across the screening centres in the Norwegian Breast Cancer Screening Program. Methods: We studied 618,636 women aged 50–69 years who underwent 2,090,575 screening exams (1996–2010. Recall rate, positive predictive value, rate of screen-detected cancer, and the cumulative risk of a false positive screening result, without and with invasive procedures across the screening centres were calculated. Generalized linear models were used to estimate the probability of a false positive screening result and to compute the cumulative false-positive risk for up to ten biennial screening examinations. Results: The cumulative risk of a false-positive screening exam varied from 10.7% (95% CI: 9.4–12.0%) to 41.5% (95% CI: 34.1–48.9%) across screening centres, with a highest to lowest ratio of 3.9 (95% CI: 3.7–4.0). The highest to lowest ratio for the cumulative risk of undergoing an invasive procedure with a benign outcome was 4.3 (95% CI: 4.0–4.6). The positive predictive value of recall varied between 12.0% (95% CI: 11.0–12.9%) and 19.9% (95% CI: 18.3–21.5%), with a highest to lowest ratio of 1.7 (95% CI: 1.5–1.9). Conclusions: A substantial variation in the performance measures across the screening centres in the Norwegian Breast Cancer Screening Program was identified, despite of similar administration, procedures, and quality assurance requirements. Differences in the

  5. The cumulative risk of false-positive screening results across screening centres in the Norwegian Breast Cancer Screening Program

    International Nuclear Information System (INIS)

    Roman, M.; Skaane, P.; Hofvind, S.

    2014-01-01

    Highlights: • We found variation in early performance measures across screening centres. • Radiologists’ performance may play a key role in the variability. • Potential to improve the effectiveness of breast cancer screening programs. • Continuous surveillance of screening centres and radiologists is essential. - Abstract: Background: Recall for assessment in mammographic screening entails an inevitable number of false-positive screening results. This study aimed to investigate the variation in the cumulative risk of a false positive screening result and the positive predictive value across the screening centres in the Norwegian Breast Cancer Screening Program. Methods: We studied 618,636 women aged 50–69 years who underwent 2,090,575 screening exams (1996–2010. Recall rate, positive predictive value, rate of screen-detected cancer, and the cumulative risk of a false positive screening result, without and with invasive procedures across the screening centres were calculated. Generalized linear models were used to estimate the probability of a false positive screening result and to compute the cumulative false-positive risk for up to ten biennial screening examinations. Results: The cumulative risk of a false-positive screening exam varied from 10.7% (95% CI: 9.4–12.0%) to 41.5% (95% CI: 34.1–48.9%) across screening centres, with a highest to lowest ratio of 3.9 (95% CI: 3.7–4.0). The highest to lowest ratio for the cumulative risk of undergoing an invasive procedure with a benign outcome was 4.3 (95% CI: 4.0–4.6). The positive predictive value of recall varied between 12.0% (95% CI: 11.0–12.9%) and 19.9% (95% CI: 18.3–21.5%), with a highest to lowest ratio of 1.7 (95% CI: 1.5–1.9). Conclusions: A substantial variation in the performance measures across the screening centres in the Norwegian Breast Cancer Screening Program was identified, despite of similar administration, procedures, and quality assurance requirements. Differences in the

  6. Massive training artificial neural network (MTANN) for reduction of false positives in computerized detection of lung nodules in low-dose computed tomography

    International Nuclear Information System (INIS)

    Suzuki, Kenji; Armato, Samuel G. III; Li, Feng; Sone, Shusuke; Doi, Kunio

    2003-01-01

    In this study, we investigated a pattern-recognition technique based on an artificial neural network (ANN), which is called a massive training artificial neural network (MTANN), for reduction of false positives in computerized detection of lung nodules in low-dose computed tomography (CT) images. The MTANN consists of a modified multilayer ANN, which is capable of operating on image data directly. The MTANN is trained by use of a large number of subregions extracted from input images together with the teacher images containing the distribution for the 'likelihood of being a nodule'. The output image is obtained by scanning an input image with the MTANN. The distinction between a nodule and a non-nodule is made by use of a score which is defined from the output image of the trained MTANN. In order to eliminate various types of non-nodules, we extended the capability of a single MTANN, and developed a multiple MTANN (Multi-MTANN). The Multi-MTANN consists of plural MTANNs that are arranged in parallel. Each MTANN is trained by using the same nodules, but with a different type of non-nodule. Each MTANN acts as an expert for a specific type of non-nodule, e.g., five different MTANNs were trained to distinguish nodules from various-sized vessels; four other MTANNs were applied to eliminate some other opacities. The outputs of the MTANNs were combined by using the logical AND operation such that each of the trained MTANNs eliminated none of the nodules, but removed the specific type of non-nodule with which the MTANN was trained, and thus removed various types of non-nodules. The Multi-MTANN consisting of nine MTANNs was trained with 10 typical nodules and 10 non-nodules representing each of nine different non-nodule types (90 training non-nodules overall) in a training set. The trained Multi-MTANN was applied to the reduction of false positives reported by our current computerized scheme for lung nodule detection based on a database of 63 low-dose CT scans (1765

  7. Hemorrhoids detected at colonoscopy: an infrequent cause of false-positive fecal immunochemical test results.

    NARCIS (Netherlands)

    Turenhout, S.T. van; Oort, F.A.; Terhaar sive Droste, J.S.; Coupe, V.M.; Hulst, R.W. van der; Loffeld, R.J.; Scholten, P.; Depla, A.C.; Bouman, A.A.; Meijer, G.A.; Mulder, C.J.; Rossum, L.G.M. van

    2012-01-01

    BACKGROUND: Colorectal cancer screening by fecal immunochemical tests (FITs) is hampered by frequent false-positive (FP) results and thereby the risk of complications and strain on colonoscopy capacity. Hemorrhoids might be a plausible cause of FP results. OBJECTIVE: To determine the contribution of

  8. IS HCI THAT IS USED AS A PRESERVATIVE CREATING FALSE POSITIVES FOR TBA IN GROUND WATER

    Science.gov (United States)

    Will hydrochloric acid produce false positives for TBA? Yes, if you heat the sample to get a lower detection limit for TBA. Conventional purge and trap methods at ambient temperature have a reporting limit for TBA between 50 and 100 g/liter. This is higher than the provisiona...

  9. False-positive buprenorphine EIA urine toxicology results due to high dose morphine: a case report.

    Science.gov (United States)

    Tenore, Peter L

    2012-01-01

    In monitoring a patient with chronic pain who was taking high-dose morphine and oxycodone with weekly urine enzymatic immunoassay (EIA) toxicology testing, the authors noted consistent positives for buprenorphine. The patient was not taking buprenorphine, and gas chromatography/mass spectroscopy (GCMS) testing on multiple samples revealed no buprenorphine, indicating a case of false-positive buprenorphine EIAs in a high-dose opiate case. The authors discontinued oxycodone for a period of time and then discontinued morphine. Urine monitoring with EIAs and GCMS revealed false-positive buprenorphine EIAs, which remained only when the patient was taking morphine. When taking only oxycodone and no morphine, urine samples became buprenorphine negative. When morphine was reintroduced, false-positive buprenorphine results resumed. Medical practitioners should be aware that high-dose morphine (with morphine urine levels turning positive within the 15,000 to 28,000 mg/mL range) may produce false-positive buprenorphine EIAs with standard urine EIA toxicology testing.

  10. False-positive findings in mammography screening induces short-term distress - breast cancer-specific concern prevails longer

    DEFF Research Database (Denmark)

    Aro, A R; Pilvikki Absetz, S; van Elderen, T M

    2000-01-01

    The aim of this study was to examine psychological distress in a mammography screening process as a consequence of screening after adjusting for background, personality and prescreening distress. Subjects, aged 50 years, were invitees at their first screening. There were three groups; normal find...... perceived breast cancer risk and susceptibility. Distress related to screening and false-positive findings seems to be moderate, but prevailing cancer-specific concerns call for improvements in screening programmes....

  11. Restricted Boltzmann machines based oversampling and semi-supervised learning for false positive reduction in breast CAD.

    Science.gov (United States)

    Cao, Peng; Liu, Xiaoli; Bao, Hang; Yang, Jinzhu; Zhao, Dazhe

    2015-01-01

    The false-positive reduction (FPR) is a crucial step in the computer aided detection system for the breast. The issues of imbalanced data distribution and the limitation of labeled samples complicate the classification procedure. To overcome these challenges, we propose oversampling and semi-supervised learning methods based on the restricted Boltzmann machines (RBMs) to solve the classification of imbalanced data with a few labeled samples. To evaluate the proposed method, we conducted a comprehensive performance study and compared its results with the commonly used techniques. Experiments on benchmark dataset of DDSM demonstrate the effectiveness of the RBMs based oversampling and semi-supervised learning method in terms of geometric mean (G-mean) for false positive reduction in Breast CAD.

  12. Multi-scale textural feature extraction and particle swarm optimization based model selection for false positive reduction in mammography.

    Science.gov (United States)

    Zyout, Imad; Czajkowska, Joanna; Grzegorzek, Marcin

    2015-12-01

    The high number of false positives and the resulting number of avoidable breast biopsies are the major problems faced by current mammography Computer Aided Detection (CAD) systems. False positive reduction is not only a requirement for mass but also for calcification CAD systems which are currently deployed for clinical use. This paper tackles two problems related to reducing the number of false positives in the detection of all lesions and masses, respectively. Firstly, textural patterns of breast tissue have been analyzed using several multi-scale textural descriptors based on wavelet and gray level co-occurrence matrix. The second problem addressed in this paper is the parameter selection and performance optimization. For this, we adopt a model selection procedure based on Particle Swarm Optimization (PSO) for selecting the most discriminative textural features and for strengthening the generalization capacity of the supervised learning stage based on a Support Vector Machine (SVM) classifier. For evaluating the proposed methods, two sets of suspicious mammogram regions have been used. The first one, obtained from Digital Database for Screening Mammography (DDSM), contains 1494 regions (1000 normal and 494 abnormal samples). The second set of suspicious regions was obtained from database of Mammographic Image Analysis Society (mini-MIAS) and contains 315 (207 normal and 108 abnormal) samples. Results from both datasets demonstrate the efficiency of using PSO based model selection for optimizing both classifier hyper-parameters and parameters, respectively. Furthermore, the obtained results indicate the promising performance of the proposed textural features and more specifically, those based on co-occurrence matrix of wavelet image representation technique. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Are Hemorrhoids Associated with False-Positive Fecal Immunochemical Test Results?

    Science.gov (United States)

    Kim, Nam Hee; Park, Jung Ho; Park, Dong Il; Sohn, Chong Il; Choi, Kyuyong; Jung, Yoon Suk

    2017-01-01

    False-positive (FP) results of fecal immunochemical tests (FITs) conducted in colorectal cancer (CRC) screening could lead to performing unnecessary colonoscopies. Hemorrhoids are a possible cause of FP FIT results; however, studies on this topic are extremely rare. We investigated whether hemorrhoids are associated with FP FIT results. A retrospective study was conducted at a university hospital in Korea from June 2013 to May 2015. Of the 34547 individuals who underwent FITs, 3946 aged ≥50 years who underwent colonoscopies were analyzed. Logistic regression analysis was performed to determine factors associated with FP FIT results. Among 3946 participants, 704 (17.8%) showed positive FIT results and 1303 (33.0%) had hemorrhoids. Of the 704 participants with positive FIT results, 165 had advanced colorectal neoplasia (ACRN) and 539 had no ACRN (FP results). Of the 1303 participants with hemorrhoids, 291 showed FP results, of whom 81 showed FP results because of hemorrhoids only. Participants with hemorrhoids had a higher rate of FP results than those without hemorrhoids (291/1176, 24.7% vs. 248/2361, 10.5%; phemorrhoids as the only abnormality had a higher rate of FP results than those experiencing no such abnormalities (81/531, 15.3% vs. 38/1173, 3.2%; phemorrhoids was identified as an independent predictor of FP results (adjusted odds ratio, 2.76; 95% confidence interval, 2.24-3.40; pHemorrhoids are significantly associated with FP FIT results. Their presence seemed to be a non-negligible contributor of FP results in FIT-based CRC screening programs.

  14. Breast cancer risk is increased in the years following false-positive breast cancer screening.

    Science.gov (United States)

    Goossens, Mathijs C; De Brabander, Isabel; De Greve, Jacques; Vaes, Evelien; Van Ongeval, Chantal; Van Herck, Koen; Kellen, Eliane

    2017-09-01

    A small number of studies have investigated breast cancer (BC) risk among women with a history of false-positive recall (FPR) in BC screening, but none of them has used time-to-event analysis while at the same time quantifying the effect of false-negative diagnostic assessment (FNDA). FNDA occurs when screening detects BC, but this BC is missed on diagnostic assessment (DA). As a result of FNDA, screenings that detected cancer are incorrectly classified as FPR. Our study linked data recorded in the Flemish BC screening program (women aged 50-69 years) to data from the national cancer registry. We used Cox proportional hazards models on a retrospective cohort of 298 738 women to assess the association between FPR and subsequent BC, while adjusting for potential confounders. The mean follow-up was 6.9 years. Compared with women without recall, women with a history of FPR were at an increased risk of developing BC [hazard ratio=2.10 (95% confidence interval: 1.92-2.31)]. However, 22% of BC after FPR was due to FNDA. The hazard ratio dropped to 1.69 (95% confidence interval: 1.52-1.87) when FNDA was excluded. Women with FPR have a subsequently increased BC risk compared with women without recall. The risk is higher for women who have a FPR BI-RADS 4 or 5 compared with FPR BI-RADS 3. There is room for improvement of diagnostic assessment: 41% of the excess risk is explained by FNDA after baseline screening.

  15. An audit to investigate the impact of false positive breast screening results and diagnostic work-up on re-engagement with subsequent routine screening

    International Nuclear Information System (INIS)

    Nightingale, Julie M.; Borgen, Rita; Porter-Bennett, Lisa; Szczepura, Katy

    2015-01-01

    Introduction: Women attending breast screening may have suspicious mammographic findings that are subsequently found at assessment clinic to be normal (false positive, FP). A false positive diagnosis is not harmless, with short and long term negative psychosocial consequences reported. Women are at increased relative risk of breast cancer therefore their attendance at subsequent screening is essential. Aims: To assess the impact of FP breast screening diagnosis and diagnostic work-up on re-attendance rates across four consecutive screening rounds at a typical breast screening centre. Method: Diagnostic interventions and screening re-attendance rates at one prior and two consecutive rounds were analysed for women receiving an FP diagnosis between 2004 and 2006. Results: 397 women (5.57%) were referred for further assessment, including 228 (57.43%) false positives. 34 eligible women failed to re-attend routine screening (+3 years), with 17 failing to re-attend subsequently (+6 years). 70.6% (24/34) of non-attenders had attended at least two screening rounds prior to FP assessment. 75% of FP women had an imaging-only assessment with 17.5% (30/171) failing to re-attend, and 25% received a biopsy, with 7% (4/57) failing to re-attend subsequently. Conclusion: This study is unique as it follows FP women through four consecutive screening rounds. FP non-attendance rates were considerably lower compared to the general screening population, with diagnostic work-up having limited influence. FP non-attendance may appear insignificant in comparison to total screened population, but these women are at greater risk of subsequent cancer so should be actively encouraged to re-engage with the screening programme

  16. A false-positive detection bias as a function of state and trait schizotypy in interaction with intelligence

    Directory of Open Access Journals (Sweden)

    Phillip eGrant

    2014-09-01

    Full Text Available Hallucinatory experiences are by far not limited to patients with clinical psychosis. A number of internal and external factors may bring about such experiences in healthy individuals, whereby the personality trait of (positive schizotypy is a major mediator of individual differences. Psychotic experiences are defined as associating abnormal meaning to real but objectively irrelevant perceptions. Especially the ambiguity of a stimulus correlates positively with the likelihood of abnormal interpretation, and intelligence is believed to have an important influence and act as protective against clinical psychosis in highly schizotypic individuals.In this study we presented 131 healthy participants with 216 15-letter strings containing either a word, a non-word or only random letters and asked them to report, whether or not they believed to have seen a word. The aim was to replicate findings that participants with high values in positive schizotypy on the trait-level make more false-positive errors and assess the role of stimulus-ambiguity and verbal intelligence. Additionally, we wanted to examine whether the same effect could be shown for indices of state schizotypy.Our results support findings that both state and trait positive schizotypy explain significant variance in seeing things that are not there and that the properties of individual stimuli have additional strong effects on the false-positive hit rates. Finally, we found that verbal intelligence and positive schizotypy interact with stimulus-ambiguity in the production of false-positive perceptions.

  17. A false-positive detection bias as a function of state and trait schizotypy in interaction with intelligence.

    Science.gov (United States)

    Grant, Phillip; Balser, Mona; Munk, Aisha Judith Leila; Linder, Jens; Hennig, Juergen

    2014-01-01

    Hallucinatory experiences are by far not limited to patients with clinical psychosis. A number of internal and external factors may bring about such experiences in healthy individuals, whereby the personality trait of (positive) schizotypy is a major mediator of individual differences. Psychotic experiences are defined as associating abnormal meaning to real but objectively irrelevant perceptions. Especially, the ambiguity of a stimulus correlates positively with the likelihood of abnormal interpretation, and intelligence is believed to have an important influence and act as protective against clinical psychosis in highly schizotypic individuals. In this study, we presented 131 healthy participants with 216 15-letter strings containing either a word, a non-word, or only random letters and asked them to report, whether or not they believed to have seen a word. The aim was to replicate findings that participants with high values in positive schizotypy on the trait-level make more false-positive errors and assess the role of stimulus-ambiguity and verbal intelligence. Additionally, we wanted to examine whether the same effect could be shown for indices of state schizotypy. Our results support findings that both state and trait positive schizotypy explain significant variance in "seeing things that are not there" and that the properties of individual stimuli have additional strong effects on the false-positive hit rates. Finally, we found that verbal intelligence and positive schizotypy interact with stimulus-ambiguity in the production of false-positive perceptions.

  18. Using ELISPOT to expose false positive skin test conversion in tuberculosis contacts.

    Directory of Open Access Journals (Sweden)

    Philip C Hill

    2007-01-01

    Full Text Available Repeat tuberculin skin tests may be false positive due to boosting of waned immunity to past mycobacterial exposure. We evaluated whether an ELISPOT test could identify tuberculosis (TB contacts with boosting of immunity to non-tuberculous mycobacterial exposure.We conducted tuberculin and ELISPOT tests in 1665 TB contacts: 799 were tuberculin test negative and were offered a repeat test after three months. Those with tuberculin test conversion had an ELISPOT, chest X-ray and sputum analysis if appropriate. We compared converters with non-converters, assessed the probability of each of four combinations of ELISPOT results over the two time points and estimated boosting with adjustment for ELISPOT sensitivity and specificity. 704 (72% contacts had a repeat tuberculin test; 176 (25% had test conversion, which increased with exposure to a case (p = 0.002, increasing age (p = 0.0006 and BCG scar (p = 0.06. 114 tuberculin test converters had ELISPOT results: 16(14% were recruitment positive/follow-up positive, 9 (8% positive/negative, 34 (30% negative/positive, and 55 (48% were negative/negative. There was a significant non-linear effect of age for ELISPOT results in skin test converters (p = 0.038. Estimates of boosting ranged from 32%-41% of skin test converters with increasing age. Three converters were diagnosed with TB, two had ELISPOT results: both were positive, including one at recruitment.We estimate that approximately one third of tuberculin skin test conversion in Gambian TB case contacts is due to boosting of immunity to non-tuberculous mycobacterial exposure. Further longitudinal studies are required to confirm whether ELISPOT can reliably identify case contacts with tuberculin test conversion that would benefit most from prophylactic treatment.

  19. Mouse obesity network reconstruction with a variational Bayes algorithm to employ aggressive false positive control

    Directory of Open Access Journals (Sweden)

    Logsdon Benjamin A

    2012-04-01

    Full Text Available Abstract Background We propose a novel variational Bayes network reconstruction algorithm to extract the most relevant disease factors from high-throughput genomic data-sets. Our algorithm is the only scalable method for regularized network recovery that employs Bayesian model averaging and that can internally estimate an appropriate level of sparsity to ensure few false positives enter the model without the need for cross-validation or a model selection criterion. We use our algorithm to characterize the effect of genetic markers and liver gene expression traits on mouse obesity related phenotypes, including weight, cholesterol, glucose, and free fatty acid levels, in an experiment previously used for discovery and validation of network connections: an F2 intercross between the C57BL/6 J and C3H/HeJ mouse strains, where apolipoprotein E is null on the background. Results We identified eleven genes, Gch1, Zfp69, Dlgap1, Gna14, Yy1, Gabarapl1, Folr2, Fdft1, Cnr2, Slc24a3, and Ccl19, and a quantitative trait locus directly connected to weight, glucose, cholesterol, or free fatty acid levels in our network. None of these genes were identified by other network analyses of this mouse intercross data-set, but all have been previously associated with obesity or related pathologies in independent studies. In addition, through both simulations and data analysis we demonstrate that our algorithm achieves superior performance in terms of power and type I error control than other network recovery algorithms that use the lasso and have bounds on type I error control. Conclusions Our final network contains 118 previously associated and novel genes affecting weight, cholesterol, glucose, and free fatty acid levels that are excellent obesity risk candidates.

  20. Assessment of potential false positives via orbitrap-based untargeted lipidomics from rat tissues.

    Science.gov (United States)

    Xu, Lina; Wang, Xueying; Jiao, Yupei; Liu, Xiaohui

    2018-02-01

    Untargeted lipidomics is increasingly popular due to the broad coverage of lipid species. Data dependent MS/MS acquisition is commonly used in order to acquire sufficient information for confident lipid assignment. However, although lipids are identified based on MS/MS confirmation, a number of false positives are still observed. Here, we discuss several causes of introducing lipid false identifications in untargeted analysis. Phosphotidylcholines and cholesteryl esters generate in-source fragmentation to produce dimethylated phosphotidylethanolamine and free cholesterol. Dimerization of fatty acid results in false identification of fatty acid ester of hydroxyl fatty acid. Realizing these false positives is able to improve confidence of results acquired from untargeted analysis. Besides, thresholds are established for lipids identified using LipidSearch v4.1.16 software to reduce unreliable results. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Waiting time and the psychosocial consequences of false-positive mammography

    DEFF Research Database (Denmark)

    Heleno, Bruno M.; Siersma, Volkert; Brodersen, John

    2015-01-01

    Background: There is wide variation in the psychosocial response to false-positive mammography. We aimed to assess whether women having to wait longer to exclude cancer had increased psychosocial consequences that persisted after cancer was ruled out. Findings: We selected women with false......-positive mammography (n = 272), screened for breast cancer in Copenhagen and Funen (Denmark) over a 1-year period. We measured psychosocial consequences immediately before women attended their recall visit and 1, 6, 18 and 36 months after women received their final diagnosis. After women were told that cancer had been...... ruled out, adverse psychosocial consequences decreased with time. We found no statistically significant differences between women who had cancer ruled out immediately at the recall visit (waiting time of 0) and women who had to wait longer before cancer was ruled out (waiting times 1-30, 30...

  2. Long-term psychosocial consequences of false-positive screening mammography

    DEFF Research Database (Denmark)

    Brodersen, John; Siersma, Volkert Dirk

    2013-01-01

    Cancer screening programs have the potential of intended beneficial effects, but they also inevitably have unintended harmful effects. In the case of screening mammography, the most frequent harm is a false-positive result. Prior efforts to measure their psychosocial consequences have been limite...... by short-term follow-up, the use of generic survey instruments, and the lack of a relevant benchmark-women with breast cancer....

  3. Cross-reactive Carbohydrate Determinant Contributes to the False Positive IgE Antibody to Peanut

    Directory of Open Access Journals (Sweden)

    Komei Ito

    2005-01-01

    Conclusions: Social education about the features of peanut allergy is needed in Japan. Anti-CCD IgE antibody was suggested to be one of the mechanisms contributing to the false positive detection of peanut IgE. Detection of anti-HRP or anti-bromelain IgE can be a useful tool to recognize the presence of anti-CCD antibodies.

  4. Sherlock Holmes and child psychopathology assessment approaches: the case of the false-positive.

    Science.gov (United States)

    Jensen, P S; Watanabe, H

    1999-02-01

    To explore the relative value of various methods of assessing childhood psychopathology, the authors compared 4 groups of children: those who met criteria for one or more DSM diagnoses and scored high on parent symptom checklists, those who met psychopathology criteria on either one of these two assessment approaches alone, and those who met no psychopathology assessment criterion. Parents of 201 children completed the Child Behavior Checklist (CBCL), after which children and parents were administered the Diagnostic Interview Schedule for Children (version 2.1). Children and parents also completed other survey measures and symptom report inventories. The 4 groups of children were compared against "external validators" to examine the merits of "false-positive" and "false-negative" cases. True-positive cases (those that met DSM criteria and scored high on the CBCL) differed significantly from the true-negative cases on most external validators. "False-positive" and "false-negative" cases had intermediate levels of most risk factors and external validators. "False-positive" cases were not normal per se because they scored significantly above the true-negative group on a number of risk factors and external validators. A similar but less marked pattern was noted for "false-negatives." Findings call into question whether cases with high symptom checklist scores despite no formal diagnoses should be considered "false-positive." Pending the availability of robust markers for mental illness, researchers and clinicians must resist the tendency to reify diagnostic categories or to engage in arcane debates about the superiority of one assessment approach over another.

  5. Shape based automated detection of pulmonary nodules with surface feature based false positive reduction

    International Nuclear Information System (INIS)

    Nomura, Y.; Itoh, H.; Masutani, Y.; Ohtomo, K.; Maeda, E.; Yoshikawa, T.; Hayashi, N.

    2007-01-01

    We proposed a shape based automated detection of pulmonary nodules with surface feature based false positive (FP) reduction. In the proposed system, the FP existing in internal of vessel bifurcation is removed using extracted surface of vessels and nodules. From the validation with 16 chest CT scans, we find that the proposed CAD system achieves 18.7 FPs/scan at 90% sensitivity, and 7.8 FPs/scan at 80% sensitivity. (orig.)

  6. Evaluation of inadequate, indeterminate, false-negative and false-positive cases in cytological examination for breast cancer according to histological type

    Directory of Open Access Journals (Sweden)

    Yamaguchi Rin

    2012-05-01

    Full Text Available Abstract Background We previously investigated the current status of breast cytology cancer screening at seven institutes in our area of southern Fukuoka Prefecture, and found some differences in diagnostic accuracy among the institutions. In the present study, we evaluated the cases involved and noted possible reasons for their original cytological classification as inadequate, indeterminate, false-negative and false-positive according to histological type. Methods We evaluated the histological findings in 5693 individuals who underwent cytological examination for breast cancer (including inadequate, indeterminate, false-negative and false-positive cases, to determine the most common histological types and/or features in these settings and the usefulness/limitations of cytological examination for the diagnosis of breast cancer. Results Among 1152 cytologically inadequate cases, histology revealed that 75/173 (43.6% cases were benign, including mastopathy (fibrocystic disease in 38.6%, fibroadenoma in 24.0% and papilloma in 5.3%. Ninety-five of 173 (54.9% cases were histologically malignant, with scirrhous growing type, invasive ductal carcinoma (SIDC being significantly more frequent (49.5% than papillotubular growing type (Papi-tub (P P = 0.0001 and ductal carcinoma in situ (DCIS (P = 0.0001. Among 458 indeterminate cases, 54/139 (38.8% were histologically benign (mastopathy, 30.0%; fibroadenoma, 27.8%; papilloma, 26.0% and 73/139 (52.5% were malignant, with SIDC being the most frequent malignant tumor (37.0%. Among 52 false-negative cases, SIDC was significantly more frequent (42.3% than DCIS (P = 0.0049 and Papi-tub (P = 0.001. There were three false-positive cases, with one each of fibroadenoma, epidermal cyst and papilloma. Conclusions The inadequate, indeterminate, false-negative and false-positive cases showed similar histological types, notably SIDC for malignant tumors, and mastopathy, fibroadenoma and papilloma for

  7. Clinical evaluation of false-positive scintigraphic lesions of the left lobe in portal hypertension

    International Nuclear Information System (INIS)

    Takayasu, Kenichi; Moriyama, Noriyuki; Suzuki, Masao; Yamada, Tatsuya; Fukutake, Toshio.

    1982-01-01

    sup(99m)Tc-phytate liver scan and percutaneous transhepatic portography (PTP) were performed in 33 patients with portal hypertension due to various hepatic diseases. A defect or space occupying lesion in the left lobe on the scan in these patients was analysed with reference to portographic changes of the pars umbilicus of the left portal vein and the following results were obtained. 1) A false-positive defect on the scintigram was found in 6 (18.2%) of 33 patients, and portal vein pressure (PVP) was above 200 mmH 2 O in all 6 which constituted 21.4% of 28 with PVP above 200 mmH 2 O. 2) In five out of 6 patients with false-positive scan findings, the pars umbilicus was dilated to more than 25 x 15 mm in size, and it was huge and tortuous in 3 of them. 3) The mean PVP in the group with a false-positive scan tended to be higher than that in patients with no abnormalities on the scintigram. It was concluded that in reading of liver scintigrams in patients with portal hypertension, a dilated pars umbilicus and huge para-umbilical vein should be considered. (author)

  8. False Positive Findings on I-131 WBS and SPECT/CT in Patients with History of Thyroid Cancer: Case Series

    Directory of Open Access Journals (Sweden)

    Zeina C. Hannoush

    2017-01-01

    Full Text Available Introduction. Although whole body scan (WBS with I-131 is a highly sensitive tool for detecting normal thyroid tissue and metastasis of differentiated thyroid cancer (DTC, it is not specific. Additional information, provided by single photon emission computed tomography combined with X-ray computed tomography (SPECT/CT and by the serum thyroglobulin level, is extremely useful for the interpretation of findings. Case Presentation. We report four cases of false positive WBS in patients with DTC: ovarian uptake corresponding to an endometrioma, scrotal uptake due to a spermatocele, rib-cage uptake due to an old fracture, and hepatic and renal uptake secondary to a granuloma and simple cyst, respectively. Conclusions. Trapping, organification, and storage of iodine are more prominent in thyroid tissue but not specific. Physiologic sodium-iodine symporter expression in other tissues explains some, but not all, of the WBS false positive cases. Other proposed etiologies are accumulation of radioiodine in inflamed organs, metabolism of radiodinated thyroid hormone, presence of radioiodine in body fluids, and contamination. In our cases nonthyroidal pathologies were suspected since the imaging findings were not corroborated by an elevated thyroglobulin level, which is considered a reliable tumor marker for most well-differentiated thyroid cancers. Clinicians should be aware of the potential pitfalls of WBS in DTC to avoid incorrect management.

  9. Heterophilic antibodies interfering with radioimmunoassay. A false-positive pregnancy test

    Energy Technology Data Exchange (ETDEWEB)

    Vladutiu, A.O.; Sulewski, J.M.; Pudlak, K.A.; Stull, C.G.

    1982-11-19

    A young woman with amenorrhea had a consistently positive pregnancy test result (serum radioimmunoassay measurement of ..beta..-human chorionic gonadotropin hormone). No fetal or placental tissue was found after uterine curettage and exploratory laparotomy. The false-positive pregnancy test result was due to heterophilic antibovine and antigoat antibodies in the patient's serum. These antibodies interfered with radioimmunoassays using goat antibodies. This case shows that serum heterophilic antibodies can interfere with immunoassays and result in unnecessary diagnostic procedures and/or unnecessary treatment.

  10. Heterophilic antibodies interfering with radioimmunoassay. A false-positive pregnancy test

    International Nuclear Information System (INIS)

    Vladutiu, A.O.; Sulewski, J.M.; Pudlak, K.A.; Stull, C.G.

    1982-01-01

    A young woman with amenorrhea had a consistently positive pregnancy test result (serum radioimmunoassay measurement of #betta#-human chorionic gonadotropin hormone). No fetal or placental tissue was found after uterine curettage and exploratory laparotomy. The false-positive pregnancy test result was due to heterophilic antibovine and antigoat antibodies in the patient's serum. These antibodies interfered with radioimmunoassays using goat antibodies. This case shows that serum heterophilic antibodies can interfere with immunoassays and result in unnecessary diagnostic procedures and/or unnecessary treatment

  11. Suture Granuloma Showing False-Positive Findings on FDG-PET

    Directory of Open Access Journals (Sweden)

    Kohei Takahara

    2013-01-01

    Full Text Available We report a case of a 33-year-old male with a mixed germ-cell testicular tumor. Postoperative follow-up FDG-PET revealed concentration of FDG in the left inguinal area which is not tumor metastasis or local recurrence but suture reactivity granuloma. In this paper, we reviewed suture granulomas associated with false-positive findings on FDG-PET after surgery. If FDG-PET will be used more frequently in the future, it will be necessary to refrain from using silk thread in order to prevent any unnecessary surgery.

  12. Usefulness of exercise ECG test with nitroglycerin and exercise cardiac scintigraphy in patients with false positive exercise ECG test

    International Nuclear Information System (INIS)

    Moritani, Kohshiro

    1984-01-01

    The purpose of this study is to evaluate the clinical usefulness of exercise (Ex) ECG test with sublingual nitroglycerin (NTG) and Ex cardiac scintigraphy in differentiating false positive responses from true positive responses of Ex ECG test. We examined 7 pts (age : 46+-7 years) with true positive Ex ECG test (TP) and 8 pts (age : 55+-10 years) with false positive Ex ECG test (FP). TP had significant coronary artery disease and FP did not. Ex test was done by multistage ergometer test. In 5 pts of TP and all pts of FP, Ex cardiac scintigraphy was performed. In TP, Ex cardiac scintigraphy revealed reversible perfusion deficit, but not in FP. NTG was administered 3 minutes before Ex test was started. Ex test with NTG was terminated at the same load as Ex test without NTG. Pressure-rate products at the end point of Ex test did not show significant difference between Ex test without NTG and that with NTG (TP: 203x10 2 , 213x10 2 , FP: 196x10 2 , 206x10 2 , respectively). In 7 pts of FP, ST depression in Ex test without NTG was not improved in Ex test with NTG. On the other hand, in all pts of TP, ST depression seen in Ex test without NTG, was not observed in Ex test with NTG. It may be concluded that Ex cardiac scintigraphy is diagnostic for differentiation of false positive responses from true positive responses of Ex ECG test, as well as Ex ECG test with NTG is. (author)

  13. Robust Correlation Analyses: False Positive and Power Validation Using a New Open Source Matlab Toolbox

    Science.gov (United States)

    Pernet, Cyril R.; Wilcox, Rand; Rousselet, Guillaume A.

    2012-01-01

    Pearson’s correlation measures the strength of the association between two variables. The technique is, however, restricted to linear associations and is overly sensitive to outliers. Indeed, a single outlier can result in a highly inaccurate summary of the data. Yet, it remains the most commonly used measure of association in psychology research. Here we describe a free Matlab(R) based toolbox (http://sourceforge.net/projects/robustcorrtool/) that computes robust measures of association between two or more random variables: the percentage-bend correlation and skipped-correlations. After illustrating how to use the toolbox, we show that robust methods, where outliers are down weighted or removed and accounted for in significance testing, provide better estimates of the true association with accurate false positive control and without loss of power. The different correlation methods were tested with normal data and normal data contaminated with marginal or bivariate outliers. We report estimates of effect size, false positive rate and power, and advise on which technique to use depending on the data at hand. PMID:23335907

  14. Robust correlation analyses: false positive and power validation using a new open source matlab toolbox.

    Science.gov (United States)

    Pernet, Cyril R; Wilcox, Rand; Rousselet, Guillaume A

    2012-01-01

    Pearson's correlation measures the strength of the association between two variables. The technique is, however, restricted to linear associations and is overly sensitive to outliers. Indeed, a single outlier can result in a highly inaccurate summary of the data. Yet, it remains the most commonly used measure of association in psychology research. Here we describe a free Matlab((R)) based toolbox (http://sourceforge.net/projects/robustcorrtool/) that computes robust measures of association between two or more random variables: the percentage-bend correlation and skipped-correlations. After illustrating how to use the toolbox, we show that robust methods, where outliers are down weighted or removed and accounted for in significance testing, provide better estimates of the true association with accurate false positive control and without loss of power. The different correlation methods were tested with normal data and normal data contaminated with marginal or bivariate outliers. We report estimates of effect size, false positive rate and power, and advise on which technique to use depending on the data at hand.

  15. 'False-positive' and 'false-negative' test results in clinical urine drug testing.

    Science.gov (United States)

    Reisfield, Gary M; Goldberger, Bruce A; Bertholf, Roger L

    2009-08-01

    The terms 'false-positive' and 'false-negative' are widely used in discussions of urine drug test (UDT) results. These terms are inadequate because they are used in different ways by physicians and laboratory professionals and they are too narrow to encompass the larger universe of potentially misleading, inappropriate and unexpected drug test results. This larger universe, while not solely comprised of technically 'true' or 'false' positive or negative test results, presents comparable interpretive challenges with corresponding clinical implications. In this review, we propose the terms 'potentially inappropriate' positive or negative test results in reference to UDT results that are ambiguous or unexpected and subject to misinterpretation. Causes of potentially inappropriate positive UDT results include in vivo metabolic conversions of a drug, exposure to nonillicit sources of a drug and laboratory error. Causes of potentially inappropriate negative UDT results include limited assay specificity, absence of drug in the urine, presence of drug in the urine, but below established assay cutoff, specimen manipulation and laboratory error. Clinical UDT interpretation is a complicated task requiring knowledge of recent prescription, over-the-counter and herbal drug administration, drug metabolism and analytical sensitivities and specificities.

  16. False-positive results after environmental pinworm PCR testing due to Rhabditid nematodes in Corncob bedding.

    Science.gov (United States)

    Leblanc, Mathias; Berry, Kristina; Graciano, Sandy; Becker, Brandon; Reuter, Jon D

    2014-11-01

    Modern rodent colonies are housed in individually ventilated cages to protect the animals from contamination with adventitious pathogens. Standard health monitoring through soiled-bedding sentinels does not always detect infections, especially in the context of low pathogen prevalence. Recently proposed alternatives include analyzing environmental samples from the cages or rack exhaust by PCR to improve the detection of rodent pathogens but optimal sampling strategies have not yet been established for different microorganisms. Although generally very sensitive and specific, these molecular assays are not foolproof and subject to false-positive and -negative results and should always be interpreted cautiously with an overall understanding of the intrinsic controls and all the variables that may affect the results. Here, we report a limited Aspiculuris tetraptera outbreak in a mouse barrier facility that was detected by fecal PCR in sentinels and confirmed by fecal flotation and direct cecal examination of both sentinels and colony animals. The outbreak led to a widespread survey of all facilities for pinworms by using environmental PCR from ventilated rack exhaust plenums. Environmental PCR suggested an unexpected widespread contamination of all ventilated racks holding nonautoclaved cages, but results could not be confirmed in sentinel or colony animals by fecal flotation, cecal and colonic examination, or cage PCR testing. After additional investigation, the unexpected environmental PCR results were confirmed as false-positive findings due to the nonspecificity of the assay, leading to the amplification of rhabditid nematodes, which are not infectious in rodents but which contaminated the corncob bedding.

  17. Benign thyroid and neck lesions mimicking malignancy with false positive findings on positron emission tomography-computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Ye Ri; Kim, Shin Young; Lee, Sang Mi [Soonchunhyang University Cheonan Hospital, Cheonan (Korea, Republic of); Lee, Deuk Young [Dept. of Surgery, Younsei Angelot Women' s Clinic, Cheonan (Korea, Republic of)

    2017-02-15

    The increasing use of positron emission tomography-computed tomography (PET/CT) has led to the frequent detection of incidental thyroid and neck lesions with increased 18F-deoxyglucose (FDG) uptake. Although lesions with increased FDG uptake are commonly assumed to be malignant, benign lesions may also exhibit increased uptake. The purpose of this pictorial essay is to demonstrate that benign thyroid and neck lesions can produce false-positive findings on PET/CT, and to identify various difficulties in interpretation. It is crucial to be aware that differentiating between benign and malignant lesions is difficult in a considerable proportion of cases, when relying only on PET/CT findings. Correlation of PET/CT findings with additional imaging modalities is essential to avoid misdiagnosis.

  18. Malaria rapid diagnostic tests: Plasmodium falciparum infections with high parasite densities may generate false positive Plasmodium vivax pLDH lines

    Directory of Open Access Journals (Sweden)

    van Esbroeck Marjan

    2010-07-01

    Full Text Available Abstract Background Most malaria rapid diagnostic tests (RDTs detect Plasmodium falciparum and an antigen common to the four species. Plasmodium vivax-specific RDTs target P. vivax-specific parasite lactate dehydrogenase (Pv-pLDH. Previous observations of false positive Pv-pLDH test lines in P. falciparum samples incited to the present study, which assessed P. vivax-specific RDTs for the occurrence of false positive Pv-pLDH lines in P. falciparum samples. Methods Nine P. vivax-specific RDTs were tested with 85 P. falciparum samples of high (≥2% parasite density. Mixed P. falciparum/P. vivax infections were ruled out by real-time PCR. The RDTs included two-band (detecting Pv-pLDH, three-band (detecting P. falciparum-antigen and Pv-pLDH and four-band RDTs (detecting P. falciparum, Pv-pLDH and pan-pLDH. Results False positive Pv-pLDH lines were observed in 6/9 RDTs (including two- three- and four-band RDTs. They occurred in the individual RDT brands at frequencies ranging from 8.2% to 29.1%. For 19/85 samples, at least two RDT brands generated a false positive Pv-pLDH line. Sixteen of 85 (18.8% false positive lines were of medium or strong line intensity. There was no significant relation between false positive results and parasite density or geographic origin of the samples. Conclusion False positive Pv-pLDH lines in P. falciparum samples with high parasite density occurred in 6/9 P. vivax-specific RDTs. This is of concern as P. falciparum and P. vivax are co-circulating in many regions. The diagnosis of life-threatening P. falciparum malaria may be missed (two-band Pv-pLDH RDT, or the patient may be treated incorrectly with primaquine (three- or four-band RDTs.

  19. Improved accuracy of cell surface shaving proteomics in Staphylococcus aureus using a false-positive control

    DEFF Research Database (Denmark)

    Solis, Nestor; Larsen, Martin Røssel; Cordwell, Stuart J

    2010-01-01

    Proteolytic treatment of intact bacterial cells is an ideal means for identifying surface-exposed peptide epitopes and has potential for the discovery of novel vaccine targets. Cell stability during such treatment, however, may become compromised and result in the release of intracellular proteins...... that complicate the final analysis. Staphylococcus aureus is a major human pathogen, causing community and hospital-acquired infections, and is a serious healthcare concern due to the increasing prevalence of multiple antibiotic resistances amongst clinical isolates. We employed a cell surface "shaving" technique...... to trypsin and three identified in the control. The use of a subtracted false-positive strategy improved enrichment of surface-exposed peptides in the trypsin data set to approximately 80% (124/155 peptides). Predominant surface proteins were those associated with methicillin resistance-surface protein SACOL...

  20. False-positive ethyl glucuronide immunoassay screening caused by a propyl alcohol-based hand sanitizer.

    Science.gov (United States)

    Arndt, Torsten; Grüner, Joachim; Schröfel, Stefanie; Stemmerich, Karsten

    2012-11-30

    Urine ethyl glucuronide (EtG) is considered as a specific marker of recent ethanol consumption. We describe false-positive DRI(®) EIA EtG enzyme immunoassay results caused by propyl glucuronides in urine after using a propanol-based hand sanitizer. EtG screening was done with the DRI(®) EIA EtG assay (Microgenics), using a cut-off of 0.5 mg/L as recommended by the manufacturer and of 0.1 mg/L as demanded by the German Regulations for Reissuing Drivers Licenses. Confirmatory EtG analysis was done with the ClinMass(®) EtG LC-MS/MS testkit (Recipe), extended by the mass transitions 235.1→75.1, 235.1→85.1, and 235.1→113.1 for the detection of the 1- and 2-propyl glucuronides. Self-experiments were done by staff members of our lab (n=7), using 3 mL Sterillium(®) Classic Pure (30 g/100 g 1-propanol and 45 g/100 g 2-propanol) for hand sanitation every quarter of an hour for 8 h according to DIN EN 1500:2011-05 with and without an exhauster and by passive inhalation of the sanitizer vapor. Spot urine samples were taken immediately before and up to 24 h after the first sanitizer use. False-positive immunoassay results of up to 4 mg/L or 2.3 mg/g creatinine were obtained after normal use of the sanitizer and also after passive inhalation of the sanitizer vapor (up to 0.89 mg/L or 0.61 mg/g). Immunoassay results were positive even after 4-fold use of the sanitizer (up to 0.14 mg/L or 0.38 mg/g) and up to 6 h after the last sanitizer contact (maximum 0.63 mg/L and 0.33 mg/g for sanitizer users and 0.25 mg/g after passive inhalation). Spiking of EtG-free urine with 1-propyl glucuronide (Athena Environmental Sciences) between 0.05 and 10 mg/L clearly demonstrated a cross reaction of the immunoassay of approx. 10% as compared to EtG. LC-MS/MS of urines with a positive immunoassay EtG result did not show EtG signals, but distinct signals of 1-propyl glucuronide (n-propyl glucuronide) and 2-propyl glucuronide (iso-propyl glucuronide). An exhauster effectively prevented

  1. Empirical methods for controlling false positives and estimating confidence in ChIP-Seq peaks

    Directory of Open Access Journals (Sweden)

    Courdy Samir J

    2008-12-01

    Full Text Available Abstract Background High throughput signature sequencing holds many promises, one of which is the ready identification of in vivo transcription factor binding sites, histone modifications, changes in chromatin structure and patterns of DNA methylation across entire genomes. In these experiments, chromatin immunoprecipitation is used to enrich for particular DNA sequences of interest and signature sequencing is used to map the regions to the genome (ChIP-Seq. Elucidation of these sites of DNA-protein binding/modification are proving instrumental in reconstructing networks of gene regulation and chromatin remodelling that direct development, response to cellular perturbation, and neoplastic transformation. Results Here we present a package of algorithms and software that makes use of control input data to reduce false positives and estimate confidence in ChIP-Seq peaks. Several different methods were compared using two simulated spike-in datasets. Use of control input data and a normalized difference score were found to more than double the recovery of ChIP-Seq peaks at a 5% false discovery rate (FDR. Moreover, both a binomial p-value/q-value and an empirical FDR were found to predict the true FDR within 2–3 fold and are more reliable estimators of confidence than a global Poisson p-value. These methods were then used to reanalyze Johnson et al.'s neuron-restrictive silencer factor (NRSF ChIP-Seq data without relying on extensive qPCR validated NRSF sites and the presence of NRSF binding motifs for setting thresholds. Conclusion The methods developed and tested here show considerable promise for reducing false positives and estimating confidence in ChIP-Seq data without any prior knowledge of the chIP target. They are part of a larger open source package freely available from http://useq.sourceforge.net/.

  2. LOW FALSE POSITIVE RATE OF KEPLER CANDIDATES ESTIMATED FROM A COMBINATION OF SPITZER AND FOLLOW-UP OBSERVATIONS

    International Nuclear Information System (INIS)

    Désert, Jean-Michel; Brown, Timothy M.; Charbonneau, David; Torres, Guillermo; Fressin, François; Ballard, Sarah; Latham, David W.; Bryson, Stephen T.; Borucki, William J.; Knutson, Heather A.; Batalha, Natalie M.; Deming, Drake; Ford, Eric B.; Fortney, Jonathan J.; Gilliland, Ronald L.; Seager, Sara

    2015-01-01

    NASA’s Kepler mission has provided several thousand transiting planet candidates during the 4 yr of its nominal mission, yet only a small subset of these candidates have been confirmed as true planets. Therefore, the most fundamental question about these candidates is the fraction of bona fide planets. Estimating the rate of false positives of the overall Kepler sample is necessary to derive the planet occurrence rate. We present the results from two large observational campaigns that were conducted with the Spitzer Space Telescope during the the Kepler mission. These observations are dedicated to estimating the false positive rate (FPR) among the Kepler candidates. We select a sub-sample of 51 candidates, spanning wide ranges in stellar, orbital, and planetary parameter space, and we observe their transits with Spitzer at 4.5 μm. We use these observations to measures the candidate’s transit depths and infrared magnitudes. An authentic planet produces an achromatic transit depth (neglecting the modest effect of limb darkening). Conversely a bandpass-dependent depth alerts us to the potential presence of a blending star that could be the source of the observed eclipse: a false positive scenario. For most of the candidates (85%), the transit depths measured with Kepler are consistent with the transit depths measured with Spitzer as expected for planetary objects, while we find that the most discrepant measurements are due to the presence of unresolved stars that dilute the photometry. The Spitzer constraints on their own yield FPRs between 5% and depending on the Kepler Objects of Interest. By considering the population of the Kepler field stars, and by combining follow-up observations (imaging) when available, we find that the overall FPR of our sample is low. The measured upper limit on the FPR of our sample is 8.8% at a confidence level of 3σ. This observational result, which uses the achromatic property of planetary transit signals that is not investigated

  3. LOW FALSE POSITIVE RATE OF KEPLER CANDIDATES ESTIMATED FROM A COMBINATION OF SPITZER AND FOLLOW-UP OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Désert, Jean-Michel; Brown, Timothy M. [CASA, Department of Astrophysical and Planetary Sciences, University of Colorado, 389-UCB, Boulder, CO 80309 (United States); Charbonneau, David; Torres, Guillermo; Fressin, François; Ballard, Sarah; Latham, David W. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Bryson, Stephen T.; Borucki, William J. [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Knutson, Heather A. [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States); Batalha, Natalie M. [San Jose State University, San Jose, CA 95192 (United States); Deming, Drake [Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States); Ford, Eric B. [University of Florida, Gainesville, FL 32611 (United States); Fortney, Jonathan J. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Gilliland, Ronald L. [Center for Exoplanets and Habitable Worlds, The Pennsylvania State University, University Park, PA 16802 (United States); Seager, Sara, E-mail: desert@colorado.edu [Massachusetts Institute of Technology, Cambridge, MA 02159 (United States)

    2015-05-01

    NASA’s Kepler mission has provided several thousand transiting planet candidates during the 4 yr of its nominal mission, yet only a small subset of these candidates have been confirmed as true planets. Therefore, the most fundamental question about these candidates is the fraction of bona fide planets. Estimating the rate of false positives of the overall Kepler sample is necessary to derive the planet occurrence rate. We present the results from two large observational campaigns that were conducted with the Spitzer Space Telescope during the the Kepler mission. These observations are dedicated to estimating the false positive rate (FPR) among the Kepler candidates. We select a sub-sample of 51 candidates, spanning wide ranges in stellar, orbital, and planetary parameter space, and we observe their transits with Spitzer at 4.5 μm. We use these observations to measures the candidate’s transit depths and infrared magnitudes. An authentic planet produces an achromatic transit depth (neglecting the modest effect of limb darkening). Conversely a bandpass-dependent depth alerts us to the potential presence of a blending star that could be the source of the observed eclipse: a false positive scenario. For most of the candidates (85%), the transit depths measured with Kepler are consistent with the transit depths measured with Spitzer as expected for planetary objects, while we find that the most discrepant measurements are due to the presence of unresolved stars that dilute the photometry. The Spitzer constraints on their own yield FPRs between 5% and depending on the Kepler Objects of Interest. By considering the population of the Kepler field stars, and by combining follow-up observations (imaging) when available, we find that the overall FPR of our sample is low. The measured upper limit on the FPR of our sample is 8.8% at a confidence level of 3σ. This observational result, which uses the achromatic property of planetary transit signals that is not investigated

  4. Impact of intermediate mammography assessment on the likelihood of false-positive results in breast cancer screening programmes

    Energy Technology Data Exchange (ETDEWEB)

    Ascunce, Nieves [Public Health Institute, CIBERESP, Navarra Breast Cancer Screening Programme, Pamplona (Spain); Instituto de Salud Publica, Navarra Breast Cancer Screening Programme, Pamplona (Spain); Ederra, Maria; Delfrade, Josu; Erdozain, Nieves [Public Health Institute, CIBERESP, Navarra Breast Cancer Screening Programme, Pamplona (Spain); Baroja, Araceli [Fundacion Rioja Salud, Logrono (Spain); Zubizarreta, Raquel [Public Health and Planning Directorate, Health Office, Galician Breast Cancer Screening Programme, Galicia (Spain); Salas, Dolores [General Directorate Public Health and Centre for Public Health Research (CSISP), Valencia (Spain); Castells, Xavier [Mar Teaching Hospital, CIBERESP, Department of Clinical Epidemiology, Barcelona (Spain)

    2012-02-15

    Breast cancer screening is offered to 100% of the target population in Spain and intermediate mammograms (IMs) are sometimes indicated. This study was aimed at analysing the frequency of IMs, the factors determining their recommendation, and their impact on the risk of false-positive results and the detection rate. Data from 3,471,307 mammograms from Spanish breast cancer screening programmes were included. 3.36% of the mammograms were IMs. The factors associated with the use of IMs were age, initial screening, previous invasive tests, a familial history of breast cancer and use of hormone replacement therapy. In screening episodes with an IM, the probability of a false-positive result was 13.74% (95% CI: 13.43-14.05), almost double that in episodes without IMs (6.02%, 95% CI 5.99-6.05). In young women with previous invasive procedures, a familial history of breast cancer or hormone replacement therapy use who were undergoing their initial screen, this probability was lower when IMs were performed. IMs always increased the detection rate. The factors prompting IMs should be characterised so that radiologists can systematise their recommendations according to the presence of the factors maximising the benefits and minimising the adverse effects of this procedure. (orig.)

  5. Occurrence of false positive results for the detection of carbapenemases in carbapenemase-negative Escherichia coli and Klebsiella pneumoniae isolates.

    Directory of Open Access Journals (Sweden)

    Peng Wang

    Full Text Available Adequate detection of the production of carbapenemase in Enterobacteriaceae isolates is crucial for infection control measures and the appropriate choice of antimicrobial therapy. In this study, we investigated the frequency of false positive results for the detection of carbapenemases in carbapenemase-negative Escherichia coli and Klebsiella pneumoniae clinical isolates by the modified Hodge test (MHT. Three hundred and one E. coli and K. pneumoniae clinical isolates were investigated. All produced extended spectrum β-lactamases (ESBLs but were susceptible to carbapenems. Antimicrobial susceptibility testing was performed by the disk diffusion and agar dilution methods. The MHT was performed using the standard inoculum of test organisms recommended by the CLSI. Genes that encoded ESBLs and carbapenemases were identified by PCR and DNA sequencing. Among the 301 clinical isolates, none of the isolates conformed to the criteria for carbapenemase screening recommended by the CLSI. The susceptibility rates for imipenem, meropenem, and ertapenem all were 100.0%, 100.0%, and 100.0%, respectively. Of the 301 E. coli and K. pneumoniae isolates, none produced carbapenemase. The MHT gave a positive result for 3.3% (10/301 of the isolates. False positive results can occur when the MHT is used to detect carbapenemase in ESBL-producing isolates and clinical laboratories must be aware of this fact.

  6. Impact of intermediate mammography assessment on the likelihood of false-positive results in breast cancer screening programmes

    International Nuclear Information System (INIS)

    Ascunce, Nieves; Ederra, Maria; Delfrade, Josu; Erdozain, Nieves; Baroja, Araceli; Zubizarreta, Raquel; Salas, Dolores; Castells, Xavier

    2012-01-01

    Breast cancer screening is offered to 100% of the target population in Spain and intermediate mammograms (IMs) are sometimes indicated. This study was aimed at analysing the frequency of IMs, the factors determining their recommendation, and their impact on the risk of false-positive results and the detection rate. Data from 3,471,307 mammograms from Spanish breast cancer screening programmes were included. 3.36% of the mammograms were IMs. The factors associated with the use of IMs were age, initial screening, previous invasive tests, a familial history of breast cancer and use of hormone replacement therapy. In screening episodes with an IM, the probability of a false-positive result was 13.74% (95% CI: 13.43-14.05), almost double that in episodes without IMs (6.02%, 95% CI 5.99-6.05). In young women with previous invasive procedures, a familial history of breast cancer or hormone replacement therapy use who were undergoing their initial screen, this probability was lower when IMs were performed. IMs always increased the detection rate. The factors prompting IMs should be characterised so that radiologists can systematise their recommendations according to the presence of the factors maximising the benefits and minimising the adverse effects of this procedure. (orig.)

  7. When are false-positive and false-negative 18F'FDG PET scans really false?

    International Nuclear Information System (INIS)

    Binns, D.S.; Hicks, R.J.; Fawcett, M.E.

    1999-01-01

    Full text: A 61-year-old male presented with locally advanced squamous cell carcinoma of the base of tongue. In the absence of wider metastatic disease on conventional staging, he was enrolled in a phase I, dose escalation chemoradiotherapy trial. In this study, therapeutic response to radiotherapy combined with cisplatin and a chemotherapeutic agent which specifically targets hypoxic cells (tirapazamine) was evaluated with serial 18 F-FDG PET scans. Baseline 18 F-FDG PET confirmed locally advanced disease, although a previously undetected lower cervical lymph node was identified and included in the radiotherapy portal. Whole-body PET revealed a small metabolically active area adjacent to the right hemidiaphragm. Respiratory gated, high-resolution helical CT failed to find structural evidence of disease and, as a result, the patient was enrolled in the 7 week therapy regime on the assumption that the PET finding was a false-positive result. Repeat 18 F-FDG PET scans at the middle, end and 12 weeks post-treatment showed excellent therapeutic response in the head and neck which was discordant with clinical and CT findings, and resolution of the metabolically active chest lesion. Despite the negative PET scan, persistent clinical and CT evidence of a residual tumour mass suggested a false-negative result and resulted in a neck lymph node dissection. This showed no evidence of malignant cells. Five months following treatment, the patient presented with pleural effusion at the base on the right lung. Subsequent CT scanning showed a small pleural lesion at the site of initial 18 F-FDG uptake. Biopsy confirmed metastatic disease. The apparent transient resolution of 18 F-FDG uptake in the pleural lesion with treatment presumably reflected a combination of reduced metabolic activity and size due to the partial, but not complete, cytotoxic effects of cisplatin. In conclusion, this case emphasizes the importance of pathological review and clinical follow-up in reconciling

  8. Upward creep of the heart: A frequent source of false-positive reversible defects during thallium-201 stress-redistribution SPECT

    International Nuclear Information System (INIS)

    Friedman, J.; Van Train, K.; Maddahi, J.; Rozanski, A.; Prigent, F.; Bietendorf, J.; Waxman, A.; Berman, D.S.

    1989-01-01

    A new cause of artifactual 201 Tl defects on single photon emission computed tomography (SPECT) termed upward creep of the heart is described. In 102 consecutive patients undergoing 201 Tl SPECT, 30 (29%) demonstrated upward creep defined by an upward movement of the heart of greater than or equal to 2 pixels during acquisition. In 45 consecutive patients with a less than 5% likelihood of coronary artery disease, 17 (38%) had upward creep. Of these nine had reversible 201 Tl defects localized to the inferior and basal inferoseptal walls, while none of the 28 without upward creep had defects. The 17 low likelihood patients with upward creep had longer exercise duration and higher peak heart rate than those without upward creep. In five additional low likelihood patients with upward creep in whom imaging was immediately repeated, the upward creep pattern disappeared on the repeated images. After we changed our test protocol to begin imaging 15 min postexercise, only five (14%) of 36 low likelihood patients tested demonstrated upward creep. Upward creep is probably related to a transient increase in mean total lung volume early following exhaustive exercise, resulting in a mean lower position of the diaphragm (and thus the heart) at the beginning of imaging. The frequency of this source of false-positive 201 Tl studies can be reduced by delaying SPECT acquisition until 15 min postexercise

  9. Computer-aided mass detection in mammography: False positive reduction via gray-scale invariant ranklet texture features

    International Nuclear Information System (INIS)

    Masotti, Matteo; Lanconelli, Nico; Campanini, Renato

    2009-01-01

    In this work, gray-scale invariant ranklet texture features are proposed for false positive reduction (FPR) in computer-aided detection (CAD) of breast masses. Two main considerations are at the basis of this proposal. First, false positive (FP) marks surviving our previous CAD system seem to be characterized by specific texture properties that can be used to discriminate them from masses. Second, our previous CAD system achieves invariance to linear/nonlinear monotonic gray-scale transformations by encoding regions of interest into ranklet images through the ranklet transform, an image transformation similar to the wavelet transform, yet dealing with pixels' ranks rather than with their gray-scale values. Therefore, the new FPR approach proposed herein defines a set of texture features which are calculated directly from the ranklet images corresponding to the regions of interest surviving our previous CAD system, hence, ranklet texture features; then, a support vector machine (SVM) classifier is used for discrimination. As a result of this approach, texture-based information is used to discriminate FP marks surviving our previous CAD system; at the same time, invariance to linear/nonlinear monotonic gray-scale transformations of the new CAD system is guaranteed, as ranklet texture features are calculated from ranklet images that have this property themselves by construction. To emphasize the gray-scale invariance of both the previous and new CAD systems, training and testing are carried out without any in-between parameters' adjustment on mammograms having different gray-scale dynamics; in particular, training is carried out on analog digitized mammograms taken from a publicly available digital database, whereas testing is performed on full-field digital mammograms taken from an in-house database. Free-response receiver operating characteristic (FROC) curve analysis of the two CAD systems demonstrates that the new approach achieves a higher reduction of FP marks

  10. Risk factors for false positive and for false negative test results in screening with fecal occult blood testing

    NARCIS (Netherlands)

    Stegeman, Inge; de Wijkerslooth, Thomas R.; Stoop, Esther M.; van Leerdam, Monique; van Ballegooijen, M.; Kraaijenhagen, Roderik A.; Fockens, Paul; Kuipers, Ernst J.; Dekker, Evelien; Bossuyt, Patrick M.

    2013-01-01

    Differences in the risk of a false negative or a false positive fecal immunochemical test (FIT) across subgroups may affect optimal screening strategies. We evaluate whether subgroups are at increased risk of a false positive or a false negative FIT result, whether such variability in risk is

  11. False-positive I-131 scan by contaminated muffler in a patient with thyroid carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Han Kyung; Kim, Min Woo; Jeong, Hwan Jeong; Sohn, Myung Hee [Chonbuk National University Hospital, Chonju (Korea, Republic of)

    2006-02-15

    A 39-year-old female patient who had undergone a total thyroidectomy for a papillary thyroid carcinoma underwent a whole body scan with I-131. The I-131 scan was performed 72 hours after administering 185 MBq (5 mGi) of an I-131 solution. The anterior image of head, neck, and upper chest showed multiple areas of increased uptake in the mediastinal area considering of functional metastasis. However, radioactivity was not evident in the image taken after removing her clothes and muffler. The image obtained after placing the muffler on the pallet showed that the radioactivity was still present. It is well known that artifacts on an I-131 scan can be produced by styling hair sputum, drooling during sleep, chewing gum, and paper or a cloth handkerchief that is contaminated with the radioactive iodine from either perspiration or saliva. This activity might be mistaken for a functional metastasis. Therefore, it is essential that an image be obtained after removing the patient's clothes. In this study, artifacts due to a contaminated muffler on the I-131 scan were found. These mimicked a functional metastasis of the mediastinal area in a patient with a papillary thyroid carcinoma.

  12. Evaluation of inadequate, indeterminate, false-negative and false-positive cases in cytological examination for breast cancer according to histological type

    Science.gov (United States)

    2012-01-01

    Background We previously investigated the current status of breast cytology cancer screening at seven institutes in our area of southern Fukuoka Prefecture, and found some differences in diagnostic accuracy among the institutions. In the present study, we evaluated the cases involved and noted possible reasons for their original cytological classification as inadequate, indeterminate, false-negative and false-positive according to histological type. Methods We evaluated the histological findings in 5693 individuals who underwent cytological examination for breast cancer (including inadequate, indeterminate, false-negative and false-positive cases), to determine the most common histological types and/or features in these settings and the usefulness/limitations of cytological examination for the diagnosis of breast cancer. Results Among 1152 cytologically inadequate cases, histology revealed that 75/173 (43.6%) cases were benign, including mastopathy (fibrocystic disease) in 38.6%, fibroadenoma in 24.0% and papilloma in 5.3%. Ninety-five of 173 (54.9%) cases were histologically malignant, with scirrhous growing type, invasive ductal carcinoma (SIDC) being significantly more frequent (49.5%) than papillotubular growing type (Papi-tub) (P breast disease. In particular, several inadequate, indeterminate and false-negative cases with samples collected by aspiration were diagnosed as SIDC. These findings should encourage the use of needle biopsy rather than aspiration when this histological type is identified on imaging. Namely, good communication between clinicians and pathological staff, and triple assessment (i.e., clinical, pathological and radiological assessment), are important for accurate diagnosis of aspiration samples. Virtual slides The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/7349809170055423 PMID:22607447

  13. False positive results using calcitonin as a screening method for medullary thyroid carcinoma

    Directory of Open Access Journals (Sweden)

    Rafael Loch Batista

    2013-01-01

    Full Text Available The role of serum calcitonin as part of the evaluation of thyroid nodules has been widely discussed in literature. However there still is no consensus of measurement of calcitonin in the initial evaluation of a patient with thyroid nodule. Problems concerning cost-benefit, lab methods, false positive and low prevalence of medullary thyroid carcinoma (MTC are factors that limit this approach. We have illustrated two cases where serum calcitonin was used in the evaluation of thyroid nodule and rates proved to be high. A stimulation test was performed, using calcium as secretagogue, and calcitonin hyper-stimulation was confirmed, but anatomopathologic examination did not evidence medullar neoplasia. Anatomopathologic diagnosis detected Hashimoto thyroiditis in one case and adenomatous goiter plus an occult papillary thyroid carcinoma in the other one. Recommendation for routine use of serum calcitonin in the initial diagnostic evaluation of a thyroid nodule, followed by a confirming stimulation test if basal serum calcitonin is showed to be high, is the most currently recommended approach, but questions concerning cost-benefit and possibility of diagnosis error make the validity of this recommendation discussible.

  14. Reporting instructions significantly impact false positive rates when reading chest radiographs

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, John W.; Brennan, Patrick C.; Mello-Thoms, Claudia; Lewis, Sarah J. [The University of Sydney, Medical Image Optimisation and Perception Group, Discipline of Medical Radiation Sciences, Faculty of Health Sciences, Lidcombe, NSW (Australia)

    2016-10-15

    To determine the impact of specific reporting tasks on the performance of radiologists when reading chest radiographs. Ten experienced radiologists read a set of 40 postero-anterior (PA) chest radiographs: 21 nodule free and 19 with a proven solitary nodule. There were two reporting conditions: an unframed task (UFT) to report any abnormality and a framed task (FT) reporting only lung nodule/s. Jackknife free-response operating characteristic (JAFROC) figure of merit (FOM), specificity, location sensitivity and number of true positive (TP), false positive (FP), true negative (TN) and false negative (FN) decisions were used for analysis. JAFROC FOM for tasks showed a significant reduction in performance for framed tasks (P = 0.006) and an associated decrease in specificity (P = 0.011) but no alteration to the location sensitivity score. There was a significant increase in number of FP decisions made during framed versus unframed tasks for nodule-containing (P = 0.005) and nodule-free (P = 0.011) chest radiographs. No significant differences in TP were recorded. Radiologists report more FP decisions when given specific reporting instructions to search for nodules on chest radiographs. The relevance of clinical history supplied to radiologists is called into question and may induce a negative effect. (orig.)

  15. False positive localisation of C-11 methionine in a colloid nodule

    International Nuclear Information System (INIS)

    Mahajan, Sonia; Tripathi, Madhavi; Jaimini, Abhinav; Dinesh, Anant

    2011-01-01

    A 45-year-old female diagnosed with carcinoma of the left breast on histopathological examination underwent both 18 F-flourodeoxyglucose (FDG) and 11C-methionine (MET) positron emission tomography/computed tomography (PET/CT) as part of a protocol comparing the utility of these tracers for predicting a response to neoadjuvant chemotherapy in breast carcinoma. Abnormal FDG and MET accumulation was noted in the left breast primary, left axillary lymph nodes, and also in a well-defined nodule present in the left lobe of the thyroid gland. Keeping in mind the possibility of thyroid neoplasm/metastasis, the patient was referred for fine needle aspiration cytology (FNAC) from the thyroid nodule that revealed features of a simple colloid nodule. Focal thyroid lesions incidentally found on 18 F-FDG PET/CT have a high risk of thyroid malignancy. Non-specific accumulation of FDG in thyroid adenomas is also known. This case highlights a potential cause for false positive on C-11 MET PET/CT in colloid adenomas, which should be kept in mind while using this tracer for oncological indications

  16. THE POSSIBLE MOON OF KEPLER-90g IS A FALSE POSITIVE

    Energy Technology Data Exchange (ETDEWEB)

    Kipping, D. M.; Torres, G.; Buchhave, L. A. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Huang, X.; Bakos, G. Á. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 05844 (United States); Nesvorný, D. [Department of Space Studies, Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, CO 80302 (United States); Schmitt, A. R., E-mail: dkipping@cfa.harvard.edu

    2015-01-20

    The discovery of an exomoon would provide deep insights into planet formation and the habitability of planetary systems, with transiting examples being particularly sought after. Of the hundreds of Kepler planets now discovered, the seven-planet system Kepler-90 is unusual for exhibiting an unidentified transit-like signal in close proximity to one of the transits of the long-period gas-giant Kepler-90g, as noted by Cabrera et al. As part of the ''Hunt for Exomoons with Kepler'' project, we investigate this possible exomoon signal and find it passes all conventional photometric, dynamical, and centroid diagnostic tests. However, pixel-level light curves indicate that the moon-like signal occurs on nearly all of the target's pixels, which we confirm using a novel way of examining pixel-level data which we dub the ''transit centroid''. This test reveals that the possible exomoon to Kepler-90g is likely a false positive, perhaps due to a cosmic ray induced sudden pixel sensitivity dropout. This work highlights the extreme care required for seeking non-periodic low-amplitude transit signals, such as exomoons.

  17. Reporting instructions significantly impact false positive rates when reading chest radiographs

    International Nuclear Information System (INIS)

    Robinson, John W.; Brennan, Patrick C.; Mello-Thoms, Claudia; Lewis, Sarah J.

    2016-01-01

    To determine the impact of specific reporting tasks on the performance of radiologists when reading chest radiographs. Ten experienced radiologists read a set of 40 postero-anterior (PA) chest radiographs: 21 nodule free and 19 with a proven solitary nodule. There were two reporting conditions: an unframed task (UFT) to report any abnormality and a framed task (FT) reporting only lung nodule/s. Jackknife free-response operating characteristic (JAFROC) figure of merit (FOM), specificity, location sensitivity and number of true positive (TP), false positive (FP), true negative (TN) and false negative (FN) decisions were used for analysis. JAFROC FOM for tasks showed a significant reduction in performance for framed tasks (P = 0.006) and an associated decrease in specificity (P = 0.011) but no alteration to the location sensitivity score. There was a significant increase in number of FP decisions made during framed versus unframed tasks for nodule-containing (P = 0.005) and nodule-free (P = 0.011) chest radiographs. No significant differences in TP were recorded. Radiologists report more FP decisions when given specific reporting instructions to search for nodules on chest radiographs. The relevance of clinical history supplied to radiologists is called into question and may induce a negative effect. (orig.)

  18. Avoiding false positive antigen detection by flow cytometry on blood cell derived microparticles: the importance of an appropriate negative control.

    Directory of Open Access Journals (Sweden)

    Emerence Crompot

    Full Text Available Microparticles (MPs, also called microvesicles (MVs are plasma membrane-derived fragments with sizes ranging from 0.1 to 1μm. Characterization of these MPs is often performed by flow cytometry but there is no consensus on the appropriate negative control to use that can lead to false positive results.We analyzed MPs from platelets, B-cells, T-cells, NK-cells, monocytes, and chronic lymphocytic leukemia (CLL B-cells. Cells were purified by positive magnetic-separation and cultured for 48h. Cells and MPs were characterized using the following monoclonal antibodies (CD19,20 for B-cells, CD3,8,5,27 for T-cells, CD16,56 for NK-cells, CD14,11c for monocytes, CD41,61 for platelets. Isolated MPs were stained with annexin-V-FITC and gated between 300nm and 900nm. The latex bead technique was then performed for easy detection of MPs. Samples were analyzed by Transmission (TEM and Scanning Electron microscopy (SEM.Annexin-V positive events within a gate of 300-900nm were detected and defined as MPs. Our results confirmed that the characteristic antigens CD41/CD61 were found on platelet-derived-MPs validating our technique. However, for MPs derived from other cell types, we were unable to detect any antigen, although they were clearly expressed on the MP-producing cells in the contrary of several data published in the literature. Using the latex bead technique, we confirmed detection of CD41,61. However, the apparent expression of other antigens (already deemed positive in several studies was determined to be false positive, indicated by negative controls (same labeling was used on MPs from different origins.We observed that mother cell antigens were not always detected on corresponding MPs by direct flow cytometry or latex bead cytometry. Our data highlighted that false positive results could be generated due to antibody aspecificity and that phenotypic characterization of MPs is a difficult field requiring the use of several negative controls.

  19. Trial sequential analysis reveals insufficient information size and potentially false positive results in many meta-analyses

    DEFF Research Database (Denmark)

    Brok, J.; Thorlund, K.; Gluud, C.

    2008-01-01

    in 80% (insufficient information size). TSA(15%) and TSA(LBHIS) found that 95% and 91% had absence of evidence. The remaining nonsignificant meta-analyses had evidence of lack of effect. CONCLUSION: TSA reveals insufficient information size and potentially false positive results in many meta......OBJECTIVES: To evaluate meta-analyses with trial sequential analysis (TSA). TSA adjusts for random error risk and provides the required number of participants (information size) in a meta-analysis. Meta-analyses not reaching information size are analyzed with trial sequential monitoring boundaries...... analogous to interim monitoring boundaries in a single trial. STUDY DESIGN AND SETTING: We applied TSA on meta-analyses performed in Cochrane Neonatal reviews. We calculated information sizes and monitoring boundaries with three different anticipated intervention effects of 30% relative risk reduction (TSA...

  20. Effect of radiologist experience on the risk of false-positive results in breast cancer screening programs

    International Nuclear Information System (INIS)

    Zubizarreta Alberdi, Raquel; Llanes, Ana B.F.; Ortega, Raquel Almazan; Exposito, Ruben Roman; Collado, Jose M.V.; Oliveres, Xavier Castells; Queiro Verdes, Teresa; Natal Ramos, Carmen; Sanz, Maria Ederra; Salas Trejo, Dolores

    2011-01-01

    To evaluate the effect of radiologist experience on the risk of false-positive results in population-based breast cancer screening programmes. We evaluated 1,440,384 single-read screening mammograms, corresponding to 471,112 women aged 45-69 years participating in four Spanish programmes between 1990 and 2006. The mammograms were interpreted by 72 radiologists. The overall percentage of false-positive results was 5.85% and that for false-positives resulting in an invasive procedure was 0.38%. Both the risk of false-positives overall and of false-positives leading to an invasive procedure significantly decreased (p 14,999 mammograms with respect to the reference category (<500). The risk of both categories of false-positives was also significantly reduced (p < 0.001) as radiologists' years of experience increased: OR 0.96 and OR 0.84, respectively, for 1 year's experience and OR 0.72 and OR 0.73, respectively, for more than 4 years' experience with regard to the category of <1 year's experience. Radiologist experience is a determining factor in the risk of a false-positive result in breast cancer screening. (orig.)

  1. Unusual False Positive Radioiodine Uptake on 131I Whole Body Scintigraphy in Three Unrelated Organs with Different Pathologies in Patients of Differentiated Thyroid Carcinoma: A Case Series

    International Nuclear Information System (INIS)

    Ranade, Rohit; Pawar, Shwetal; Mahajan, Abhishek; Basu, Sandip

    2016-01-01

    Three cases with unusual false positive radioiodine uptake in three different organs and pathologies (infective old fibrotic lesion in the lung, simple liver cyst, and benign breast lesion) on iodine-131 ( 131 I) whole body scintigraphy. Clinicoradiological correlation was undertaken in all three cases and the pathologies were ascertained. In all the three cases, single-photon emission computerized tomography-computed tomography (SPECT-CT) and ancillary imaging modalities were employed and were helpful in arriving at the final diagnosis

  2. Shear-wave elastography in the diagnosis of solid breast masses: what leads to false-negative or false-positive results?

    Science.gov (United States)

    Yoon, Jung Hyun; Jung, Hae Kyoung; Lee, Jong Tae; Ko, Kyung Hee

    2013-09-01

    To investigate the factors that have an effect on false-positive or false-negative shear-wave elastography (SWE) results in solid breast masses. From June to December 2012, 222 breast lesions of 199 consecutive women (mean age: 45.3 ± 10.1 years; range, 21 to 88 years) who had been scheduled for biopsy or surgical excision were included. Greyscale ultrasound and SWE were performed in all women before biopsy. Final ultrasound assessments and SWE parameters (pattern classification and maximum elasticity) were recorded and compared with histopathology results. Patient and lesion factors in the 'true' and 'false' groups were compared. Of the 222 masses, 175 (78.8 %) were benign, and 47 (21.2 %) were malignant. False-positive rates of benign masses were significantly higher than false-negative rates of malignancy in SWE patterns, 36.6 % to 6.4 % (P masses, factors showing significance among false SWE features were lesion size, breast thickness and lesion depth (all P breast masses had SWE images of good quality. False SWE features were more significantly seen in benign masses. Lesion size, breast thickness and lesion depth have significance in producing false results, and this needs consideration in SWE image acquisition. • Shear-wave elastography (SWE) is widely used during breast imaging • At SWE, false-positive rates were significantly higher than false-negative rates • Larger size, breast thickness, depth and fair quality influences false-positive SWE features • Smaller size, larger breast thickness and depth influences false-negative SWE features.

  3. Early Disseminated Lyme Disease Causing False-Positive Serology for Primary Epstein-Barr Virus Infection: Report of 2 Cases.

    Science.gov (United States)

    Pavletic, Adriana J; Marques, Adriana R

    2017-07-15

    False-positive serology for Lyme disease was reported in patients with acute infectious mononucleosis. Here we describe 2 patients with early disseminated Lyme disease who were misdiagnosed with infectious mononucleosis based on false-positive tests for primary Epstein-Barr virus infection. Published by Oxford University Press for the Infectious Diseases Society of America 2017. This work is written by (a) US Government employee(s) and is in the public domain in the US.

  4. False-positive indium-111 labeled leukocyte scintigram in a patient with a painful hip prosthesis

    International Nuclear Information System (INIS)

    Feldman, N.; Makler, P.T. Jr.; Alavi, A.

    1986-01-01

    A Tronzo hip prosthesis is designed to elicit an inflammatory reaction in order to promote prosthesis stability. A three-phased bone scan and Ga-67 imaging in conjunction with physical examination and laboratory findings failed to demonstrate evidence for osteomyelitis in a patient with a painful hip prosthesis, in whom images obtained with In-111-labeled leukocytes were positive. This observation demonstrated that the interpretation of the latter technique in demonstrating inflammation can cause a false impression of an infectious process

  5. Effect of radiologist experience on the risk of false-positive results in breast cancer screening programs

    Energy Technology Data Exchange (ETDEWEB)

    Zubizarreta Alberdi, Raquel [Galician Breast Cancer Screening Programme, Public Health and Planning Directorate, Health Office, Galicia (Spain); Edificio Administrativo da Conselleria de Sanidade, Servicio de Programas Poboacionais de Cribado, Direccion Xeral de Saude Publica e Planificacion, Santiago de Compostela, Galicia (Spain); Llanes, Ana B.F.; Ortega, Raquel Almazan [Galician Breast Cancer Screening Programme, Public Health and Planning Directorate, Health Office, Galicia (Spain); Exposito, Ruben Roman; Collado, Jose M.V.; Oliveres, Xavier Castells [Department of Epidemiology and Evaluation, Institut Municipal d' Investigacio Medica-Parc de Salut Mar. CIBERESP, Barcelona (Spain); Queiro Verdes, Teresa [Galician Agency for Health Technology Assessment, Public Health and Planning Directorate, Health Office, Galicia (Spain); Natal Ramos, Carmen [Principality of Asturias Breast Cancer Screening Programme, Principality of Asturias (Spain); Sanz, Maria Ederra [Public Health Institute, Navarra Breast Cancer Screening Programme, Pamplona (Spain); Salas Trejo, Dolores [General Directorate Public Health and Centre for Public Health Research (CSISP), Valencia Breast Cancer Screening Programme, Valencia (Spain)

    2011-10-15

    To evaluate the effect of radiologist experience on the risk of false-positive results in population-based breast cancer screening programmes. We evaluated 1,440,384 single-read screening mammograms, corresponding to 471,112 women aged 45-69 years participating in four Spanish programmes between 1990 and 2006. The mammograms were interpreted by 72 radiologists. The overall percentage of false-positive results was 5.85% and that for false-positives resulting in an invasive procedure was 0.38%. Both the risk of false-positives overall and of false-positives leading to an invasive procedure significantly decreased (p < 0.001) with greater reading volume in the previous year: OR 0.77 and OR 0.78, respectively, for a reading volume 500-1,999 mammograms and OR 0.59 and OR 0.60 for a reading volume of >14,999 mammograms with respect to the reference category (<500). The risk of both categories of false-positives was also significantly reduced (p < 0.001) as radiologists' years of experience increased: OR 0.96 and OR 0.84, respectively, for 1 year's experience and OR 0.72 and OR 0.73, respectively, for more than 4 years' experience with regard to the category of <1 year's experience. Radiologist experience is a determining factor in the risk of a false-positive result in breast cancer screening. (orig.)

  6. False-positive breast screening due to fat necrosis following mammography

    International Nuclear Information System (INIS)

    Cawson, Jennifer N.; Malara, Frank A.

    2004-01-01

    Traumatic fat necrosis can result in a spectrum of imaging appearances that range from characteristically benign to those indistinguishable from malignancy. In such cases, biopsy might be required for diagnosis. The present case demonstrates a suspicious mammographic mass lesion appearing following a haematoma caused by a previous screening mammogram Copyright (2004) Blackwell Publishing Asia Pty Ltd

  7. False-positive findings in mammography screening induces short-term distress - breast cancer-specific concern prevails longer

    DEFF Research Database (Denmark)

    Aro, A R; Pilvikki Absetz, S; van Elderen, T M

    2000-01-01

    -ups at 2 and 12 months postscreening. At 2 months, there was a moderate multivariate effect of group on distress; and intrusive thinking and worry about breast cancer, in particular, were most frequent amongst the false positives. Intrusive thinking still prevailed at 12 months, in addition to a higher...... findings (n=1407), false-positive findings (n=492) and referents from outside the screening programme (n=1718, age 48-49 years). Distress was measured as illness worry, anxiety, depression, cancer beliefs and early detection behaviour. Measurements were one month before screening invitation with follow...... perceived breast cancer risk and susceptibility. Distress related to screening and false-positive findings seems to be moderate, but prevailing cancer-specific concerns call for improvements in screening programmes....

  8. The risk factor of false-negative and false-positive for T-SPOT.TB in active tuberculosis.

    Science.gov (United States)

    Di, Li; Li, Yan

    2018-02-01

    T-SPOT.TB is a promising diagnosis tool to identify both pulmonary tuberculosis and extrapulmonary tuberculosis, as well as latent tuberculosis; however, the factors that affect the results of T-SPOT.TB remains unclear. In this study, we aim to figure out the risk factor of T-SPOT.TB for active TB. A total of 349 patients were recruited between January 1st, 2016 and January 22st, 2017 at Renmin Hospital of Wuhan University, including 98 subjects with TB and 251 subjects with non-TB disease, and received T-SPOT.TB (Oxford Immunotec Ltd). Statistics were analyzed by SPSS 19.0 using logistic regression. The overall specificity and sensitivity of the T-SPOT.TB was 92.83% (233/251; 95%CI 0.8872-0.9557) and 83.67% (82/98; 95%CI 0.7454-0.9010), respectively. Patients with tuberculous meningitis were more likely to have false-negative results (OR 17.4, 95%CI 3.068-98.671; P.05). Tuberculous meningitis was a risk factor of false-negative for T-SPOT.TB, while cured TB was a risk factor of false-positive. © 2017 Wiley Periodicals, Inc.

  9. Interpreting the results of the Semmes-Weinstein monofilament test: accounting for false-positive answers in the international consensus on the diabetic foot protocol by a new model.

    Science.gov (United States)

    Slater, Robert A; Koren, Shlomit; Ramot, Yoram; Buchs, Andreas; Rapoport, Micha J

    2014-01-01

    The Semmes-Weinstein monofilament is the most widely used test to diagnose the loss of protective sensation. The commonly used protocol of the International Consensus on the Diabetic Foot includes a 'sham' application that allows for false-positive answers. We sought to study the heretofore unexamined significance of false-positive answers. Forty-five patients with diabetes and a history of pedal ulceration (Group I) and 81 patients with diabetes but no history of ulceration (Group II) were studied. The three original sites of the International Consensus on the Diabetic Foot at the hallux, 1st metatarsal and 5th metatarsal areas were used. At each location, the test was performed three times: 2 actual and 1 "sham" applications. Scores were graded from 0 to 3 based upon correct responses. Determination of loss of protective sensation was performed with and without calculating a false-positive answer as a minus 1 score. False-positive responses were found in a significant percentage of patients with and without history of ulceration. Introducing false-positive results as minus 1 into the test outcome significantly increased the number of patients diagnosed with loss of protective sensation in both groups. False-positive answers can significantly affect Semmes-Weinstein monofilament test results and the diagnosis of LOPS. A model that accounts for false-positive answers is offered. Copyright © 2013 John Wiley & Sons, Ltd.

  10. False-Positive Rate Determination of Protein Target Discovery using a Covalent Modification- and Mass Spectrometry-Based Proteomics Platform

    Science.gov (United States)

    Strickland, Erin C.; Geer, M. Ariel; Hong, Jiyong; Fitzgerald, Michael C.

    2014-01-01

    Detection and quantitation of protein-ligand binding interactions is important in many areas of biological research. Stability of proteins from rates of oxidation (SPROX) is an energetics-based technique for identifying the proteins targets of ligands in complex biological mixtures. Knowing the false-positive rate of protein target discovery in proteome-wide SPROX experiments is important for the correct interpretation of results. Reported here are the results of a control SPROX experiment in which chemical denaturation data is obtained on the proteins in two samples that originated from the same yeast lysate, as would be done in a typical SPROX experiment except that one sample would be spiked with the test ligand. False-positive rates of 1.2-2.2 % and analysis of the isobaric mass tag (e.g., iTRAQ®) reporter ions used for peptide quantitation. Our results also suggest that technical replicates can be used to effectively eliminate such false positives that result from this random error, as is demonstrated in a SPROX experiment to identify yeast protein targets of the drug, manassantin A. The impact of ion purity in the tandem mass spectral analyses and of background oxidation on the false-positive rate of protein target discovery using SPROX is also discussed.

  11. False-positive cryptococcal antigen test associated with use of BBL Port-a-Cul transport vials.

    Science.gov (United States)

    Wilson, Deborah A; Sholtis, Mary; Parshall, Sharon; Hall, Gerri S; Procop, Gary W

    2011-02-01

    A total of 52 residual CSF and serum specimens, which were originally negative with the Cryptococcal Antigen Latex Agglutination System (CALAS), were shown to become falsely positive after placement in BBL Port-A-Cul anaerobic transport vials. This transport device, although excellent for specimen transportation for subsequent culture, should not be used if cryptococcal antigen testing is needed.

  12. False-Positive Cryptococcal Antigen Test Associated with Use of BBL Port-A-Cul Transport Vials▿

    Science.gov (United States)

    Wilson, Deborah A.; Sholtis, Mary; Parshall, Sharon; Hall, Gerri S.; Procop, Gary W.

    2011-01-01

    A total of 52 residual CSF and serum specimens, which were originally negative with the Cryptococcal Antigen Latex Agglutination System (CALAS), were shown to become falsely positive after placement in BBL Port-A-Cul anaerobic transport vials. This transport device, although excellent for specimen transportation for subsequent culture, should not be used if cryptococcal antigen testing is needed. PMID:21159939

  13. A False Positive I-131 Metastatic Survey Caused by Radioactive Iodine Uptake by a Benign Thymic Cyst

    Directory of Open Access Journals (Sweden)

    Avneet K. Singh

    2017-01-01

    Full Text Available Thyroid carcinoma is the most common endocrine malignancy in the United States with increasing incidence and diagnosis but stable mortality. Differentiated thyroid cancer rarely presents with distant metastases and is associated with a low risk of morbidity and mortality. Despite this, current protocols recommend remnant ablation with radioactive iodine and evaluation for local and distant metastasis in some patients with higher risk disease. There are several case reports of false positive results of metastatic surveys that are either normal physiologic variants or other pathological findings. Most false positive findings are associated with tissue that has physiologic increased uptake of I-131, such as breast tissue or lung tissue; pathological findings such as thymic cysts are also known to have increased uptake. Our case describes a rare finding of a thymic cyst found on a false positive I-131 metastatic survey. The patient was taken for surgical excision and the final pathology was a benign thymic cyst. Given that pulmonary metastases of differentiated thyroid cancer are rare, thymic cysts, though also rare, must be part of the differential diagnosis for false positive findings on an I-131 survey.

  14. Selective activation around the left occipito-temporal sulcus for words relative to pictures: individual variability or false positives?

    Science.gov (United States)

    Wright, Nicholas D; Mechelli, Andrea; Noppeney, Uta; Veltman, Dick J; Rombouts, Serge A R B; Glensman, Janice; Haynes, John-Dylan; Price, Cathy J

    2008-08-01

    We used high-resolution fMRI to investigate claims that learning to read results in greater left occipito-temporal (OT) activation for written words relative to pictures of objects. In the first experiment, 9/16 subjects performing a one-back task showed activation in > or =1 left OT voxel for words relative to pictures (P or =1 left OT voxel for words relative to pictures. However, at this low statistical threshold false positives need to be excluded. The semantic decision paradigm was therefore repeated, within subject, in two different scanners (1.5 and 3 T). Both scanners consistently localised left OT activation for words relative to fixation and pictures relative to words, but there were no consistent effects for words relative to pictures. Finally, in a third experiment, we minimised the voxel size (1.5 x 1.5 x 1.5 mm(3)) and demonstrated a striking concordance between the voxels activated for words and pictures, irrespective of task (naming vs. one-back) or script (English vs. Hebrew). In summary, although we detected differential activation for words relative to pictures, these effects: (i) do not withstand statistical rigour; (ii) do not replicate within or between subjects; and (iii) are observed in voxels that also respond to pictures of objects. Our findings have implications for the role of left OT activation during reading. More generally, they show that studies using low statistical thresholds in single subject analyses should correct the statistical threshold for the number of comparisons made or replicate effects within subject. (c) 2007 Wiley-Liss, Inc.

  15. Ethnic hair care products may increase false positives in hair drug testing.

    Science.gov (United States)

    Kidwell, David A; Smith, Frederick P; Shepherd, Arica R

    2015-12-01

    The question of why different races appear more susceptible to hair contamination by external drugs remains controversial. This research studied susceptibility of head hair to external cocaine and methamphetamine when hair products have been applied. Three different chemical classes of ethnic hair products were applied to Caucasian, Asian, and African hair. Some products increased the methamphetamine and cocaine concentrations in all hair types. A unique finding of this research is that certain ethnic hair products can replace moisture as a diffusion medium, thereby increasing the susceptibility to contamination over 100-fold compared to petroleum-based products. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  16. Way forward in case of a false positive in vitro genotoxicity result for a cosmetic substance?

    Science.gov (United States)

    Doktorova, Tatyana Y; Ates, Gamze; Vinken, Mathieu; Vanhaecke, Tamara; Rogiers, Vera

    2014-02-01

    The currently used regulatory in vitro mutagenicity/genotoxicity test battery has a high sensitivity for detecting genotoxicants, but it suffers from a large number of irrelevant positive results (i.e. low specificity) thereby imposing the need for additional follow-up by in vitro and/or in vivo genotoxicity tests. This could have a major impact on the cosmetic industry in Europe, seen the imposed animal testing and marketing bans on cosmetics and their ingredients. Afflicted, but safe substances could therefore be lost. Using the example of triclosan, a cosmetic preservative, we describe here the potential applicability of a human toxicogenomics-based in vitro assay as a potential mechanistically based follow-up test for positive in vitro genotoxicity results. Triclosan shows a positive in vitro chromosomal aberration test, but is negative during in vivo follow-up tests. Toxicogenomics analysis unequivocally shows that triclosan is identified as a compound acting through non-DNA reactive mechanisms. This proof-of-principle study illustrates the potential of genome-wide transcriptomics data in combination with in vitro experimentation as a possible weight-of-evidence follow-up approach for de-risking a positive outcome in a standard mutagenicity/genotoxicity battery. As such a substantial number of cosmetic compounds wrongly identified as genotoxicants could be saved for the future. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. [False positive serum des-gamma-carboxy prothrombin after resection of hepatocellular carcinoma].

    Science.gov (United States)

    Hiramatsu, Kumiko; Tanaka, Yasuhito; Takagi, Kazumi; Iida, Takayasu; Takasaka, Yoshimitsu; Mizokami, Masashi

    2007-04-01

    Measurements of serum concentrations of des-gamma-carboxy-prothrombin (PIVKA-II) are widely used for diagnosing hepatocellular carcinoma (HCC). Recently, when we evaluated the correlation of PIVKA-II between two commercially available PIVKA-II immunoassay kits (Lumipulse f vs. Picolumi) to introduce it in our hospital, false high values of PIVKA-II were observed in Lumipulse assay. Four(4%) of 100 serum samples showed false high values, and all of them were obtained from patients less than 2 month after curative resection of HCC. Examining additional 7 patients with HCC resection, serum samples from the 5 patients had the same trend. To elucidate the non-specific reaction by Lumipulse assay which utilized alkaline phosphatase (ALP) enzymatic reaction, inhibition assays by various absorbents such as inactive ALP and IgM antibodies were performed. Excess of inactive ALP reduced the high values of PIVKA-II. Note that anti-bleeding sheets (fibrinogen combined drug), which included bovine thrombin, were directly attached on liver of all patients with HCC resection in this study. As the sheets also contaminate ALP and probably produce IgM antibodies to ALP, the IgM may cross-react with anti-PIVKA-II antibodies directly. Taken together, it was suggested that produced antibodies against ALP derived from anti-bleeding sheets led false high values of PIVKA-II in the patients with HCC resection.

  18. Internal Impingement of the Shoulder: A Risk of False Positive Test Outcomes in External Impingement Tests?

    Directory of Open Access Journals (Sweden)

    Tim Leschinger

    2017-01-01

    Full Text Available Background. External impingement tests are considered as being particularly reliable for identifying subacromial and coracoid shoulder impingement mechanisms. The purpose of the present study was to evaluate if these tests are likely to provoke an internal shoulder impingement mechanism which, in cases of a pathologic condition, can lead to a positive test result. Method. In 37 subjects, the mechanical contact between the glenoid rim and the rotator cuff (RC was measured quantitatively and qualitatively in external impingement test positions using an open MRI system. Results. Mechanical contact of the supraspinatus with the posterosuperior glenoid was present in 30 subjects in the Neer test. In the Hawkins test, the subscapularis was in contact with the anterosuperior glenoid in 33 subjects and the supraspinatus in 18. In the horizontal impingement test, anterosuperior contact of the supraspinatus with the glenoid was identified in 35 subjects. Conclusion. The Neer, Hawkins, and horizontal impingement tests are likely to provoke the mechanism of an internal shoulder impingement. A posterosuperior internal impingement mechanism is being provoked predominately in the Neer test. The Hawkins test narrows the distance between the insertions of the subscapularis and supraspinatus and the anterosuperior labrum, which leads to an anterosuperior impingement mechanism.

  19. False-Positive Rate of AKI Using Consensus Creatinine–Based Criteria

    Science.gov (United States)

    Lin, Jennie; Fernandez, Hilda; Shashaty, Michael G.S.; Negoianu, Dan; Testani, Jeffrey M.; Berns, Jeffrey S.; Parikh, Chirag R.

    2015-01-01

    Background and objectives Use of small changes in serum creatinine to diagnose AKI allows for earlier detection but may increase diagnostic false–positive rates because of inherent laboratory and biologic variabilities of creatinine. Design, setting, participants, & measurements We examined serum creatinine measurement characteristics in a prospective observational clinical reference cohort of 2267 adult patients with AKI by Kidney Disease Improving Global Outcomes creatinine criteria and used these data to create a simulation cohort to model AKI false–positive rates. We simulated up to seven successive blood draws on an equal population of hypothetical patients with unchanging true serum creatinine values. Error terms generated from laboratory and biologic variabilities were added to each simulated patient’s true serum creatinine value to obtain the simulated measured serum creatinine for each blood draw. We determined the proportion of patients who would be erroneously diagnosed with AKI by Kidney Disease Improving Global Outcomes creatinine criteria. Results Within the clinical cohort, 75.0% of patients received four serum creatinine draws within at least one 48-hour period during hospitalization. After four simulated creatinine measurements that accounted for laboratory variability calculated from assay characteristics and 4.4% of biologic variability determined from the clinical cohort and publicly available data, the overall false–positive rate for AKI diagnosis was 8.0% (interquartile range =7.9%–8.1%), whereas patients with true serum creatinine ≥1.5 mg/dl (representing 21% of the clinical cohort) had a false–positive AKI diagnosis rate of 30.5% (interquartile range =30.1%–30.9%) versus 2.0% (interquartile range =1.9%–2.1%) in patients with true serum creatinine values false–positive rates caused by inherent variability of serum creatinine at higher baseline values, potentially misclassifying patients with CKD in AKI studies. PMID

  20. False positive results occurring in a radioimmunoassay for hepatitis A IgM antibody of the IgM class

    Energy Technology Data Exchange (ETDEWEB)

    Bucens, M R; Pietroboni, G R; Harnett, G B [Virus Lab., Combined Microbiology Service, Queen Elizabeth II Medical Centre, Perth, Western Australia

    1983-12-01

    The diagnosis of hepatitis A infection is usually based on the presence of hepatitis A specific IgM in a single serum sample. The fortuitous observation in one patient that this reactivity was apparently still present 19 mth after her original illness led to the discovery that the ABBOTT HAVAB-M kit method may produce false positive results. A series of patients who had previously had hepatitis A was retested and false positive results were found in 6% of this group. Control groups consisted of patients with other acute and chronic liver disorders and other acute viral diseases. No reactivity was detected in the control sera. Sucrose gradient fractionation revealed that the factor responsible for the false positive results was associated only with serum fractions containing IgA and IgG and that it could be removed by absorption of sera with staphylococcal protein A but not by absorption with streptococcus AR1 or by 2-mercaptoethanol treatment. It was concluded that following hepatitis A infection some patients produce a rheumatoid factor-like substance (not of IgM class) which is cleared from the serum in 2-3 yr. The presence of this factor may lead to a misdiagnosis in patients presenting with jaundice.

  1. One Hundred False-Positive Amphetamine Specimens Characterized by Liquid Chromatography Time-of-Flight Mass Spectrometry.

    Science.gov (United States)

    Marin, Stephanie J; Doyle, Kelly; Chang, Annie; Concheiro-Guisan, Marta; Huestis, Marilyn A; Johnson-Davis, Kamisha L

    2016-01-01

    Some amphetamine (AMP) and ecstacy (MDMA) urine immunoassay (IA) kits are prone to false-positive results due to poor specificity of the antibody. We employed two techniques, high-resolution mass spectrometry (HRMS) and an in silico structure search, to identify compounds likely to cause false-positive results. Hundred false-positive IA specimens for AMP and/or MDMA were analyzed by an Agilent 6230 time-of-flight (TOF) mass spectrometer. Separately, SciFinder (Chemical Abstracts) was used as an in silico structure search to generate a library of compounds that are known to cross-react with AMP/MDMA IAs. Chemical formulas and exact masses of 145 structures were then compared against masses identified by TOF. Compounds known to have cross-reactivity with the IAs were identified in the structure-based search. The chemical formulas and exact masses of 145 structures (of 20 chemical formulas) were compared against masses identified by TOF. Urine analysis by HRMS correlates accurate mass with chemical formulae, but provides little information regarding compound structure. Structural data of targeted antigens can be utilized to correlate HRMS-derived chemical formulas with structural analogs. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  2. False positive or negative results of shear-wave elastography in differentiating benign from malignant breast masses: analysis of clinical and ultrasonographic characteristics.

    Science.gov (United States)

    Kim, Mi Young; Choi, Nami; Yang, Jung-Hyun; Yoo, Young Bum; Park, Kyoung Sik

    2015-10-01

    Shear-wave elastography (SWE) has the potential to improve diagnostic performance of conventional ultrasound (US) in differentiating benign from malignant breast masses. To investigate false positive or negative results of SWE in differentiating benign from malignant breast masses and to analyze clinical and imaging characteristics of the masses with false SWE findings. From May to October 2013, 166 breast lesions of 164 consecutive women (mean age, 45.3 ± 10.1 years) who had been scheduled for biopsy were included. Conventional US and SWE were performed in all women before biopsy. Clinical, ultrasonographic morphologic features and SWE parameters (pattern classification and standard deviation [SD]) were recorded and compared with the histopathology results. Patient and lesion factors in the "true" and "false" groups were compared. Of the 166 masses, 118 (71.1%) were benign and 48 (28.9%) were malignant. False SWE features were more frequently observed in benign masses. False positive rates of benign masses and false negative rates of malignancy were 53% and 8.2%, respectively, using SWE pattern analysis and were 22.4% and 10.3%, respectively, using SD values. A lesion boundary of the masses on US (P = 0.039) and younger patient age (P = 0.047) were significantly associated with false SWE findings. These clinical and ultrasonographic features need to be carefully evaluated in performance and interpretation of SWE examinations. © The Foundation Acta Radiologica 2014.

  3. Proportion of false-positive lesions at interim and end-of-treatment FDG-PET in lymphoma as determined by histology: Systematic review and meta-analysis

    Energy Technology Data Exchange (ETDEWEB)

    Adams, Hugo J.A., E-mail: h.j.a.adams@gmail.com; Kwee, Thomas C.

    2016-11-15

    Purpose: To systematically review and meta-analyze the proportion of false-positive lesions at interim and end-of-treatment {sup 18}F-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) in lymphoma using biopsy as reference standard. Materials and methods: Medline was searched for original studies. Methodological quality of included studies was evaluated, and results were meta-analytically summarized using random effects (in case of interstudy heterogeneity [I{sup 2} ≤ 50%]) or fixed effects (in case of no interstudy heterogeneity [I{sup 2} > 50%]). Results: Eleven studies, comprising 139 patients who underwent biopsy of an FDG-avid lesion during or after completion of antilymphoma treatment, were included. Overall methodological quality was moderate. The proportion of false-positive results among all biopsied FDG-avid lesions at PET performed during of after completion of treatment ranged between 7.7% and 90.5% (the vast majority was due to inflammatory changes), with a weighted summary proportion (random effects, I{sup 2} = 75.7%) of 55.7% (95% confidence interval [CI]: 32.6–76.6%). There were no available studies on interim FDG-PET in Hodgkin lymphoma. The pooled summary false-positive proportions were 83.0% (95% CI: 72.0%–90.2%) for interim FDG-PET in non-Hodgkin lymphoma (fixed effects, I{sup 2} = 27.7%), 23.1% (95% CI: 4.7%–64.5%) for end-of-treatment FDG-PET in Hodgkin lymphoma (random effects; I{sup 2} = 67.1%), and 31.5% (95% CI: 3.9%–83.9%) for end-of-treatment FDG-PET in non-Hodgkin lymphoma (random effects, I{sup 2} = 68.3%). Conclusion: Both interim and end-of-treatment FDG-PET scans in patients with lymphoma suffer from a very high number of false-positive FDG-avid lesions. This finding, in combination with the previously reported high number of false-negative FGD-PET scans for residual disease detection, suggests that the role of interim and end-of-treatment FDG-PET should be reconsidered.

  4. Evaluation of false positive responses by mass spectrometry and ion mobility spectrometry for the detection of trace explosives in complex samples

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, C.L., E-mail: clcrawf@sandia.gov; Hill, H.H.

    2013-09-17

    Graphical abstract: -- Highlights: •First study to use (−)SESI-IM-TOFMS to analyze complex mixtures of personal care products. •The study demonstrated, by identifying mobility and mass interferents with explosive signatures, which, if used separately, neither IMS nor MS alone would prevent every false positive for explosives when detected in the presence of a complex sample matrix. •Ingredients in common household cleaning products were shown to either enhance or suppress the ionization of explosives in a SESI-IM-TOFMS analysis. •Mobility separation provided real-time separation of ion species that indicated overlapping isotope peak patterns -- Abstract: Secondary electrospray ionization-ion mobility-time of flight mass spectrometry (SESI-IM-TOFMS) was used to evaluate common household products and food ingredients for any mass or mobility responses that produced false positives for explosives. These products contained ingredients which shared the same mass and mobility drift time ranges as the analyte ions for common explosives. The results of this study showed that the vast array of compounds in these products can cause either mass or mobility false positive responses. This work also found that two ingredients caused either enhanced or reduced ionization of the target analytes. Another result showed that an IMS can provide real-time separation of ion species that impede accurate mass identifications due to overlapping isotope peak patterns. The final result of this study showed that, when mass and mobility values were used to identify an ion, no false responses were found for the target explosives. The wider implication of these results is that the possibility exists for even greater occurrences of false responses from complex mixtures found in common products. Neither IMS nor MS alone can provide 100% assurance from false responses. IMS, due to its low cost, ease of operation, rugged reliability, high sensitivity and tunable selectivity, will remain

  5. False-positive axillary lymph node on F-18 FDG PET/CT due to moxibustion therapy

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Shin Young; Lee, Sang Woo; Ahn, Byeong Cheol; Lee, Jae Tae [Kyungpook National University Hospital, Daegu (Korea, Republic of); Seo, Ji Hyoung [Inje University Haeundae Paik Hospital, Busan (Korea, Republic of)

    2010-12-15

    A 30-year-old female was diagnosed with papillary thyroid cancer and underwent total thyroidectomy and high-dose radioiodine ablation. F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for recurrence detection of thyroid carcinoma was performed at 3 years after total thyroidectomy. Moxibustion is a traditional Chinese medicine therapy using moxa or the mugwort herb. Moxibustion is the burning of a small, thimble-sized, smoldering plug of dried leaves such as moxa or mugwort on the skin at an acupuncture point. Acupuncture and moxibustion induce hyperemia and a local inflammatory reaction. Complications associated with moxibustion such as skin bums or infection of the site have been reported previously. False-positive FDG uptake in PET may result from inflammation, infection, and variations in physiological uptake. In the present case, the hypermetabolic axillary lymph node disappeared without any treatment. Well-known of false-positive FDG uptake in axillary lymph noes such as arthritis of the upper extremity, extravasation of injected FDG, and vaccination were not found. Thus, left axillary lymph node uptake was

  6. False-positive axillary lymph node on F-18 FDG PET/CT due to moxibustion therapy

    International Nuclear Information System (INIS)

    Jeong, Shin Young; Lee, Sang Woo; Ahn, Byeong Cheol; Lee, Jae Tae; Seo, Ji Hyoung

    2010-01-01

    A 30-year-old female was diagnosed with papillary thyroid cancer and underwent total thyroidectomy and high-dose radioiodine ablation. F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for recurrence detection of thyroid carcinoma was performed at 3 years after total thyroidectomy. Moxibustion is a traditional Chinese medicine therapy using moxa or the mugwort herb. Moxibustion is the burning of a small, thimble-sized, smoldering plug of dried leaves such as moxa or mugwort on the skin at an acupuncture point. Acupuncture and moxibustion induce hyperemia and a local inflammatory reaction. Complications associated with moxibustion such as skin bums or infection of the site have been reported previously. False-positive FDG uptake in PET may result from inflammation, infection, and variations in physiological uptake. In the present case, the hypermetabolic axillary lymph node disappeared without any treatment. Well-known of false-positive FDG uptake in axillary lymph noes such as arthritis of the upper extremity, extravasation of injected FDG, and vaccination were not found. Thus, left axillary lymph node uptake was

  7. [False positive results or what's the probability that a significant P-value indicates a true effect?

    Science.gov (United States)

    Cucherat, Michel; Laporte, Silvy

    2017-09-01

    The use of statistical test is central in the clinical trial. At the statistical level, obtaining a Pinformation about the plausibility of the existence of treatment effect. With "Pfalse positive is very high. This is the case if the power is low, if there is an inflation of the alpha risk or if the result is exploratory or chance discoveries. This possibility is important to take into consideration when interpreting the results of clinical trials in order to avoid pushing ahead significant results in appearance, but which are likely to be actually false positive results. Copyright © 2017 Société française de pharmacologie et de thérapeutique. Published by Elsevier Masson SAS. All rights reserved.

  8. False-positive liver scans due to portal hypertension: correlation with percutaneous transhepatic portograms in 33 patients

    International Nuclear Information System (INIS)

    Takayasu, K.; Moriyama, N.; Suzuki, M.; Yamada, T.; Fukutake, T.; Shima, Y.; Kobayashi, C.; Musha, H.; Okuda, K.

    1983-01-01

    Tc-99m-phytate scanning of the liver and percutaneous transhepatic catheterization of the portal vein were performed in 33 patients--26 with cirrhosis, 3 with chronic active hepatitis, 2 with idiopathic portal hypertension, and 2 with unresolved acute hepatitis. A discrete defect in the porta hepatis area was seen in 6 of 28 patients who had portal vein pressure above 200 mm H2O. In 5 of the 6 patients with a false-positive scan, the umbilical portion of the left portal vein branch was dilated (larger than 25 x 20 mm) on the portogram, with or without a patent paraumbilical vein. The anatomical basis of this phenomenon is discussed, and it is suggested that this area be given special attention

  9. Minimotif Miner 3.0: database expansion and significantly improved reduction of false-positive predictions from consensus sequences.

    Science.gov (United States)

    Mi, Tian; Merlin, Jerlin Camilus; Deverasetty, Sandeep; Gryk, Michael R; Bill, Travis J; Brooks, Andrew W; Lee, Logan Y; Rathnayake, Viraj; Ross, Christian A; Sargeant, David P; Strong, Christy L; Watts, Paula; Rajasekaran, Sanguthevar; Schiller, Martin R

    2012-01-01

    Minimotif Miner (MnM available at http://minimotifminer.org or http://mnm.engr.uconn.edu) is an online database for identifying new minimotifs in protein queries. Minimotifs are short contiguous peptide sequences that have a known function in at least one protein. Here we report the third release of the MnM database which has now grown 60-fold to approximately 300,000 minimotifs. Since short minimotifs are by their nature not very complex we also summarize a new set of false-positive filters and linear regression scoring that vastly enhance minimotif prediction accuracy on a test data set. This online database can be used to predict new functions in proteins and causes of disease.

  10. Systematic hybrid LOH: a new method to reduce false positives and negatives during screening of yeast gene deletion libraries

    DEFF Research Database (Denmark)

    Alvaro, D.; Sunjevaric, I.; Reid, R. J.

    2006-01-01

    We have developed a new method, systematic hybrid loss of heterozygosity, to facilitate genomic screens utilizing the yeast gene deletion library. Screening is performed using hybrid diploid strains produced through mating the library haploids with strains from a different genetic background......, to minimize the contribution of unpredicted recessive genetic factors present in the individual library strains. We utilize a set of strains where each contains a conditional centromere construct on one of the 16 yeast chromosomes that allows the destabilization and selectable loss of that chromosome. After...... complementation of any spurious recessive mutations in the library strain, facilitating attribution of the observed phenotype to the documented gene deletion and dramatically reducing false positive results commonly obtained in library screens. The systematic hybrid LOH method can be applied to virtually any...

  11. False-positive result when a diphenylcarbazide spot test is used on trivalent chromium-passivated zinc surfaces

    DEFF Research Database (Denmark)

    Reveko, Valeriia; Lampert, Felix; Din, Rameez Ud

    2018-01-01

    chromium passivation on zinc; however, subsequent analysis by XPS could not confirm the presence of chromium in a hexavalent state. Conclusions Unintended oxidation of DPC induced by atmospheric corrosion is suggested as a possible reason for the false-positive reaction of the DPC test on a trivalent......A colorimetric 1,5-diphenylcarbazide (DPC)-based spot test can be used to identify hexavalent chromium on various metallic and leather surfaces. DPC testing on trivalent chromium-passivated zinc surfaces has unexpectedly given positive results in some cases, apparently indicating the presence...... of hexavalent chromium; however, the presence of hexavalent chromium has never been confirmed with more sensitive and accurate test methods. Objectives To examine the presence of hexavalent chromium on trivalent chromium-passivated zinc surfaces with a DPC-based spot test. Methods A colorimetric DPC spot test...

  12. Evaluation of Patients with an Apparent False Positive Stool DNA Test: The Role of Repeat Stool DNA Testing.

    Science.gov (United States)

    Cooper, Gregory S; Markowitz, Sanford D; Chen, Zhengyi; Tuck, Missy; Willis, Joseph E; Berger, Barry M; Brenner, Dean E; Li, Li

    2018-03-07

    There is uncertainty as to the appropriate follow-up of patients who test positive on multimarker stool DNA (sDNA) testing and have a colonoscopy without neoplasia. To determine the prevalence of missed colonic or occult upper gastrointestinal neoplasia in patients with an apparent false positive sDNA. We prospectively identified 30 patients who tested positive with a commercially available sDNA followed by colonoscopy without neoplastic lesions. Patients were invited to undergo repeat sDNA at 11-29 months after the initial test followed by repeat colonoscopy and upper endoscopy. We determined the presence of neoplastic lesions on repeat evaluation stratified by results of repeat sDNA. Twelve patients were restudied. Seven patients had a negative second sDNA test and a normal second colonoscopy and upper endoscopy. In contrast, 5 of 12 subjects had a persistently positive second sDNA test, and 3 had positive findings, including a 3-cm sessile transverse colon adenoma with high-grade dysplasia, a 2-cm right colon sessile serrated adenoma with dysplasia, and a nonadvanced colon adenoma (p = 0.045). These corresponded to a positive predictive value of 0.60 (95% CI 0.17-1.00) and a negative predictive value of 1.00 (95% CI 1.00-1.00) for the second sDNA test. In addition, the medical records of all 30 subjects with apparent false positive testing were reviewed and no documented cases of malignant tumors were recorded. Repeat positive sDNA testing may identify a subset of patients with missed or occult colorectal neoplasia after negative colonoscopy for an initially positive sDNA. High-quality colonoscopy with careful attention to the right colon in patients with positive sDNA is critically important and may avoid false negative colonoscopy.

  13. Significance of FDG-PET in Identification of Diseases of the Appendix – Based on Experience of Two Cases Falsely Positive for FDG Accumulation

    Directory of Open Access Journals (Sweden)

    Shimpei Ogawa

    2009-04-01

    Full Text Available A discussion of the significance of F-fluorodeoxyglucose positron emission tomography (FDG-PET in the identification of diseases of the appendix is presented based on two cases falsely positive for FDG accumulation. Both cases were palpable for a tumor in the lower right abdominal region and a prominently enlarged appendix was depicted by CT. Although the patients underwent ileocecal resection based on a strong suspicion of appendiceal cancer rather than appendicitis since abnormal accumulation exhibiting maximum standard uptake values (SUVs of 7.27 and 17.11, respectively, was observed at the same site in FDG-PET examination and since there no malignant findings observed histologically, the patients were diagnosed with appendicitis. Although FDG specifically accumulates not only in malignant tumors, but also in diseases such as acute or chronic inflammation, abscesses and lymphadenitis, and identification based on SUVs has been reported to be used as a method of identification, the two cases reported here were both false-positive cases exhibiting high maximum SUVs. At the present time, although the significance of FDG-PET in the identification of diseases of the appendix is somewhat low and there are limitations on its application, various research is currently being conducted with the aim of improving diagnostic accuracy, and it is hoped that additional studies will be conducted in the future.

  14. Easy fix for clinical laboratories for the false-positive defect with the Abbott AxSym total beta-hCG test.

    Science.gov (United States)

    Cole, Laurence A; Khanlian, Sarah A

    2004-05-01

    False-positive hCG results can lead to erroneous diagnoses and needless chemotherapy and surgery. In the last 2 years, eight publications described cases involving false-positive hCG tests; all eight involved the AxSym test. We investigated the source of this abundance of cases and a simple fix that may be used by clinical laboratories. False-positive hCG was primarily identified by absence of hCG in urine and varying or negative hCG results in alternative tests. Seventeen false-positive serum samples in the AxSym test were evaluated undiluted and at twofold dilution with diluent containing excess goat serum or immunoglobulin. We identified 58 patients with false-positive hCG, 47 of 58 due to the Abbott AxSym total hCGbeta test (81%). Sixteen of 17 of these "false-positive" results (mean 100 mIU/ml) became undetectable when tested again after twofold dilution. A simple twofold dilution with this diluent containing excess goat serum or immunoglobulin completely protected 16 of 17 samples from patients having false-positive results. It is recommended that laboratories using this test use twofold dilution as a minimum to prevent false-positive results.

  15. Generating false negatives and false positives for As and Mo concentrations in groundwater due to well installation.

    Science.gov (United States)

    Wallis, Ilka; Pichler, Thomas

    2018-08-01

    Groundwater monitoring relies on the acquisition of 'representative' groundwater samples, which should reflect the ambient water quality at a given location. However, drilling of a monitoring well for sample acquisition has the potential to perturb groundwater conditions to a point that may prove to be detrimental to the monitoring objective. Following installation of 20 monitoring wells in close geographic proximity in central Florida, opposing concentration trends for As and Mo were observed. In the first year after well installation As and Mo concentrations increased in some wells by a factor of 2, while in others As and Mo concentrations decreased by a factor of up to 100. Given this relatively short period of time, a natural change in groundwater composition of such magnitude is not expected, leaving well installation itself as the likely cause for the observed concentration changes. Hence, initial concentrations were identified as 'false negatives' if concentrations increased with time or as 'false positives' if concentrations decreased. False negatives were observed if concentrations were already high, i.e., the As or Mo were present at the time of drilling. False positives were observed if concentrations were relatively lower, i.e., As or Mo were present at low concentrations of approximately 1 to 2μg/L before drilling, but then released from the aquifer matrix as a result of drilling. Generally, As and Mo were present in the aquifer matrix in either pyrite or organic matter, both of which are susceptible to dissolution if redox conditions change due to the addition of oxygen. Thus, introduction of an oxidant into an anoxic aquifer through use of an oxygen saturated drilling fluid served as the conceptual model for the trends where concentrations decreased with time. Mixing between drilling fluid and groundwater (i.e., dilution) was used as the conceptual model for scenarios where increasing trends were observed. Conceptual models were successfully tested

  16. Limited agreement of independent RNAi screens for virus-required host genes owes more to false-negative than false-positive factors.

    Directory of Open Access Journals (Sweden)

    Linhui Hao

    Full Text Available Systematic, genome-wide RNA interference (RNAi analysis is a powerful approach to identify gene functions that support or modulate selected biological processes. An emerging challenge shared with some other genome-wide approaches is that independent RNAi studies often show limited agreement in their lists of implicated genes. To better understand this, we analyzed four genome-wide RNAi studies that identified host genes involved in influenza virus replication. These studies collectively identified and validated the roles of 614 cell genes, but pair-wise overlap among the four gene lists was only 3% to 15% (average 6.7%. However, a number of functional categories were overrepresented in multiple studies. The pair-wise overlap of these enriched-category lists was high, ∼19%, implying more agreement among studies than apparent at the gene level. Probing this further, we found that the gene lists implicated by independent studies were highly connected in interacting networks by independent functional measures such as protein-protein interactions, at rates significantly higher than predicted by chance. We also developed a general, model-based approach to gauge the effects of false-positive and false-negative factors and to estimate, from a limited number of studies, the total number of genes involved in a process. For influenza virus replication, this novel statistical approach estimates the total number of cell genes involved to be ∼2,800. This and multiple other aspects of our experimental and computational results imply that, when following good quality control practices, the low overlap between studies is primarily due to false negatives rather than false-positive gene identifications. These results and methods have implications for and applications to multiple forms of genome-wide analysis.

  17. Usefulness of pulse-wave doppler tissue sampling and dobutamine stress echocardiography for identification of false positive inferior wall defects in SPECT

    International Nuclear Information System (INIS)

    Altinmakas, S.; Dagdeviren, B.; Turkmen, M.; Gursurer, M.; Say, B.; Tezel, T.; Ersek, B.

    2000-01-01

    False positive inferior wall perfusion defects restrict the accuracy of SPECT in diagnosis of coronary artery disease (CAD). Pulse-Wave Tissue Doppler (PWTD) has been recently proposed to assess regional wall motion velocities. The objectives of this study were to evaluate the presence of CAD by using PWTD during dobutamine stress echocardiography (DSE) in patients with an inferior perfusion defect detected by SPECT and compare PWTD parameters of normal cases with patients who had inferior perfusion defect and CAD. Sixty-five patients (mean age 58±8 years, 30 men) with a normal LV systolic function at rest according to echocardiographic evaluation with an inferior ischemia determined by SPECT and a control group (CG) of 34 normal cases (mean age 56±7 years, 16 men) were included in this study. All patients underwent a standard DSE (up to 40 μg/kg/min with additional atropine during sub-maximum heart rate responses). Pulse-wave Doppler tissue sampling of inferior wall was performed in the apical 2-chamber view at rest and stress. The coronary angiography was performed within 24 hours. The results were evaluated for the prediction of significant right coronary artery (RCA) and/or left circumflex coronary artery (CX) with narrowing (≥50% diameter stenosis, assessed by quantitative coronary angiography). It was observed that the peak stress mean E/A ratio was lower in patients with CAD when compared to patients without CAD (0.78±0.2 versus 1.29±0.11 p<0.0001). Also the peak stress E/A ratio of normal cases was significantly higher than patients who had CAD (1.19±0.3 versus 0.78±0.2 p<0.0001). When the cut off point for the E/A ratio was determined as 1, the sensitivity and specificity of dobutamine stress PWTD E/A were 89% and 86%, respectively. The peak stress E/A ratio was higher than 1 in all patients with a false positive perfusion defect. Systolic S velocity increase during DSE was significantly lower in patients with CAD (54%±17 versus 99%±24 p=0

  18. Feature-guided analysis for reduction of false positives in CAD of polyps for computed tomographic colonography

    International Nuclear Information System (INIS)

    Naeppi, Janne; Yoshida, Hiroyuki

    2003-01-01

    We evaluated the effect of our novel technique of feature-guided analysis of polyps on the reduction of false-positive (FP) findings generated by our computer-aided diagnosis (CAD) scheme for the detection of polyps from computed tomography colonographic data sets. The detection performance obtained by use of feature-guided analysis in the segmentation and feature analysis of polyp candidates was compared with that obtained by use of our previously employed fuzzy clustering technique. We also evaluated the effect of a feature called modified gradient concentration (MGC) on the detection performance. A total of 144 data sets, representing prone and supine views of 72 patients that included 14 patients with 21 colorectal polyps 5-25 mm in diameter, were used in the evaluation. At a 100% by-patient (95% by-polyp) detection sensitivity, the FP rate of our CAD scheme with feature-guided analysis based on round-robin evaluation was 1.3 (1.5) FP detections per patient. This corresponds to a 70-75 % reduction in the number of FPs obtained by use of fuzzy clustering at the same sensitivity levels. Application of the MGC feature instead of our previously used gradient concentration feature did not improve the detection result. The results indicate that feature-guided analysis is useful for achieving high sensitivity and a low FP rate in our CAD scheme

  19. Public health consequences of a false-positive laboratory test result for Brucella--Florida, Georgia, and Michigan, 2005.

    Science.gov (United States)

    2008-06-06

    Human brucellosis, a nationally notifiable disease, is uncommon in the United States. Most human cases have occurred in returned travelers or immigrants from regions where brucellosis is endemic, or were acquired domestically from eating illegally imported, unpasteurized fresh cheeses. In January 2005, a woman aged 35 years who lived in Nassau County, Florida, received a diagnosis of brucellosis, based on results of a Brucella immunoglobulin M (IgM) enzyme immunoassay (EIA) performed in a commercial laboratory using analyte specific reagents (ASRs); this diagnosis prompted an investigation of dairy products in two other states. Subsequent confirmatory antibody testing by Brucella microagglutination test (BMAT) performed at CDC on the patient's serum was negative. The case did not meet the CDC/Council of State and Territorial Epidemiologists' (CSTE) definition for a probable or confirmed brucellosis case, and the initial EIA result was determined to be a false positive. This report summarizes the case history, laboratory findings, and public health investigations. CDC recommends that Brucella serology testing only be performed using tests cleared or approved by the Food and Drug Administration (FDA) or validated under the Clinical Laboratory Improvement Amendments (CLIA) and shown to reliably detect the presence of Brucella infection. Results from these tests should be considered supportive evidence for recent infection only and interpreted in the context of a clinically compatible illness and exposure history. EIA is not considered a confirmatory Brucella antibody test; positive screening test results should be confirmed by Brucella-specific agglutination (i.e., BMAT or standard tube agglutination test) methods.

  20. Risk stratification of women with false-positive test results in mammography screening based on mammographic morphology and density

    DEFF Research Database (Denmark)

    Winkel, Rikke Rass; von Euler-Chelpin, My Catarina; Lynge, Elsebeth

    2017-01-01

    a case-control study nested in the population-based screening programme in Copenhagen, Denmark. We included 288 cases and 288 controls based on a cohort of 4743 women with at least one FP-test result in 1991–2005 who were followed up until 17 April 2008. Film-based mammograms were assessed using...... the Breast Imaging-Reporting and Data System (BI-RADS) density classification, the Tabár classification, and two automated techniques quantifying percentage mammographic density (PMD) and mammographic texture (MTR), respectively. The association with breast cancer was estimated using binary logistic...

  1. The Dutch Brucella abortus monitoring programme for cattle: the impact of false-positive serological reactions and comparison of serological tests.

    Science.gov (United States)

    Emmerzaal, A; de Wit, J J; Dijkstra, Th; Bakker, D; van Zijderveld, F G

    2002-02-01

    The Dutch national Brucella abortus eradication programme for cattle started in 1959. Sporadic cases occurred yearly until 1995; the last infected herd was culled in 1996. In August 1999 the Netherlands was declared officially free of bovine brucellosis by the European Union. Before 1999, the programme to monitor the official Brucella-free status of bovine herds was primarily based on periodical testing of dairy herds with the milk ring test (MRT) and serological testing of all animals older than 1 year of age from non-dairy herds, using the micro-agglutination test (MAT) as screening test. In addition, serum samples of cattle that aborted were tested with the MAT. The high number of false positive reactions in both tests and the serum agglutination test (SAT) and complement fixation test (CFT) used for confirmation seemed to result in unnecessary blockade of herds, subsequent testing and slaughter of animals. For this reason, a validation study was performed in which three indirect enzyme-linked immunosorbent assays (ELISAs), the CFT and the SAT were compared using a panel of sera from brucellosis-free cattle, sera from experimentally infected cattle, and sera from cattle experimentally infected with bacteria which are known to induce cross-reactive antibodies (Pasteurella, Salmonella, Yersinia, and Escherichia). Moreover, four ELISAs and the MRT were compared using a panel of 1000 bulk milk samples from Brucella-free herds and 12 milk samples from Brucella abortus- infected cattle. It is concluded that the ELISA obtained from ID-Lelystad is the most suitable test to monitor the brucelosis free status of herds because it gives rise to fewer false-positive reactions than the SAT.

  2. Classification of radiological errors in chest radiographs, using support vector machine on the spatial frequency features of false- negative and false-positive regions

    Science.gov (United States)

    Pietrzyk, Mariusz W.; Donovan, Tim; Brennan, Patrick C.; Dix, Alan; Manning, David J.

    2011-03-01

    Aim: To optimize automated classification of radiological errors during lung nodule detection from chest radiographs (CxR) using a support vector machine (SVM) run on the spatial frequency features extracted from the local background of selected regions. Background: The majority of the unreported pulmonary nodules are visually detected but not recognized; shown by the prolonged dwell time values at false-negative regions. Similarly, overestimated nodule locations are capturing substantial amounts of foveal attention. Spatial frequency properties of selected local backgrounds are correlated with human observer responses either in terms of accuracy in indicating abnormality position or in the precision of visual sampling the medical images. Methods: Seven radiologists participated in the eye tracking experiments conducted under conditions of pulmonary nodule detection from a set of 20 postero-anterior CxR. The most dwelled locations have been identified and subjected to spatial frequency (SF) analysis. The image-based features of selected ROI were extracted with un-decimated Wavelet Packet Transform. An analysis of variance was run to select SF features and a SVM schema was implemented to classify False-Negative and False-Positive from all ROI. Results: A relative high overall accuracy was obtained for each individually developed Wavelet-SVM algorithm, with over 90% average correct ratio for errors recognition from all prolonged dwell locations. Conclusion: The preliminary results show that combined eye-tracking and image-based features can be used for automated detection of radiological error with SVM. The work is still in progress and not all analytical procedures have been completed, which might have an effect on the specificity of the algorithm.

  3. Retroperitoneal Endometriosis: A Possible Cause of False Positive Finding at 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography

    International Nuclear Information System (INIS)

    Maffione, Anna Margherita; Panzavolta, Riccardo; Lisato, Laura Camilla; Ballotta, Maria; D'Isanto, Mariangela Zanforlini; Rubello, Domenico

    2015-01-01

    Endometriosis is a frequent and clinically relevant problem in young women. Laparoscopy is still the gold standard for the diagnosis of endometriosis, but frequently both morphologic and functional imaging techniques are involved in the diagnostic course before achieving a conclusive diagnosis. We present a case of a patient affected by infiltrating retroperitoneal endometriosis falsely interpreted as a malignant mass by contrast-enhanced magnetic resonance imaging and 18 F-fluorodeoxyglucose positron emission tomography/computed tomography

  4. Toward the breast screening balance sheet: cumulative risk of false positives for annual versus biennial mammograms commencing at age 40 or 50.

    Science.gov (United States)

    Winch, Caleb J; Sherman, Kerry A; Boyages, John

    2015-01-01

    This study aimed to: (1) Estimate cumulative risk of recall from breast screening where no cancer is detected (a harm) in Australia; (2) Compare women screened annually versus biennially, commencing age 40 versus 50; and (3) Compare with international findings. At the no-cost metropolitan program studied, women attended biennial screening, but were offered annual screening if regarded at elevated risk for breast cancer. The cumulative risk of at least one recall was estimated using discrete-time survival analysis. Cancer detection statistics were computed. In total, 801,636 mammograms were undertaken in 231,824 women. Over 10 years, cumulative risk of recall was 13.3 % (95 % CI 12.7-13.8) for those screened biennially, and 19.9 % (CI 16.6-23.2) for those screened annually from age 50-51. Cumulative risk of complex false positive involving a biopsy was 3.1 % (CI 2.9-3.4) and 5.0 % (CI 3.4-6.6), respectively. From age 40-41, the risk of recall was 15.1 % (CI 14.3-16.0) and 22.5 % (CI 17.9-27.1) for biennial and annual screening, respectively. Corresponding rates of complex false positive were 3.3 % (CI 2.9-3.8) and 6.3 % (CI 3.4-9.1). Over 10 mammograms, invasive cancer was detected in 3.4 % (CI 3.3-3.5) and ductal carcinoma in situ in 0.7 % (CI 0.6-0.7) of women, with a non-significant trend toward a larger proportion of Tis and T1N0 cancers in women screened annually (74.5 %) versus biennially (70.1 %), χ (2) = 2.77, p = 0.10. Cancer detection was comparable to international findings. Recall risk was equal to European estimates for women screening from 50 and lower for screening from 40. Recall risk was half of United States' rates across start age and rescreening interval categories. Future benefit/harm balance sheets may be useful for communicating these findings to women.

  5. A False Positive {sup 18}F-FDG PET/CT Scan Caused by Breast Silicone Injection

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chao Jung; Lee, Bi Fang; Yao, Wei Jen; Wu, Pei Shan; Chen, Wen Chung; Peng, Shu Lin; Chiu, Nan Tsing [Cheng Kung University Medical College and Hospital, Tainan (Turkmenistan)

    2009-04-15

    We present here the case of a 40-year-old woman with a greater than 10 year prior history of bilateral breast silicone injection and saline bag implantation. Bilateral palpable breast nodules were observed, but the ultrasound scan was suboptimal and the magnetic resonance imaging showed no gadolinium enhanced tumor. The {sup 18}F-FDG PET/CT scan showed a hypermetabolic nodule in the left breast with a 30% increase of {sup 18}F-FDG uptake on the delayed imaging, and this mimicked breast cancer. She underwent a left partial mastectomy and the pathology demonstrated a siliconoma.

  6. Decisions to Shoot in a Weapon Identification Task: The Influence of Cultural Stereotypes and Perceived Threat on False Positive Errors

    OpenAIRE

    Fleming, Kevin K.; Bandy, Carole L.; Kimble, Matthew O.

    2009-01-01

    The decision to shoot engages executive control processes that can be biased by cultural stereotypes and perceived threat. The neural locus of the decision to shoot is likely to be found in the anterior cingulate cortex (ACC) where cognition and affect converge. Male military cadets at Norwich University (N=37) performed a weapon identification task in which they made rapid decisions to shoot when images of guns appeared briefly on a computer screen. Reaction times, error rates, and EEG activ...

  7. Small intestinal bacterial overgrowth as an uncommon cause of false positive lactose hydrogen breath test among patients with diarrhea-predominant irritable bowel syndrome in Asia.

    Science.gov (United States)

    Wang, Yilin; Xiong, Lishou; Gong, Xiaorong; Li, Weimin; Zhang, Xiangsong; Chen, Minhu

    2015-06-01

    It has been reported that small intestinal bacterial overgrowth (SIBO) may lead to false positive diagnoses of lactose malabsorption (LM) in irritable bowel syndrome patients. The aim of this study was to determine the influence of SIBO on lactose hydrogen breath test (HBT) results in these patients. Diarrhea-predominant irritable bowel syndrome patients with abnormal lactose HBTs ingested a test meal containing (99m) Tc and lactose. The location of the test meal and the breath levels of hydrogen were recorded simultaneously by scintigraphic scanning and lactose HBT, respectively. The increase in hydrogen concentration was not considered to be caused by SIBO if ≥ 10% of (99m) Tc accumulated in the cecal region at the time or before of abnormal lactose HBT. LM was present in 84% (31/37) of irritable bowel syndrome patients. Twenty of these patients agreed to measurement of oro-cecal transit time. Only three patients (15%) with abnormal lactose HBT might have had SIBO. The median oro-cecal transit time between LM and lactose intolerance patients were 75 min and 45 min, respectively (Z=2.545, P=0.011). Most of irritable bowel syndrome patients with an abnormal lactose HBT had LM. SIBO had little impact on the interpretation of lactose HBTs. The patients with lactose intolerance had faster small intestinal transit than LM patients. © 2014 Journal of Gastroenterology and Hepatology Foundation and Wiley Publishing Asia Pty Ltd.

  8. Specificity and false positive rates of the Test of Memory Malingering, Rey 15-item Test, and Rey Word Recognition Test among forensic inpatients with intellectual disabilities.

    Science.gov (United States)

    Love, Christopher M; Glassmire, David M; Zanolini, Shanna Jordan; Wolf, Amanda

    2014-10-01

    This study evaluated the specificity and false positive (FP) rates of the Rey 15-Item Test (FIT), Word Recognition Test (WRT), and Test of Memory Malingering (TOMM) in a sample of 21 forensic inpatients with mild intellectual disability (ID). The FIT demonstrated an FP rate of 23.8% with the standard quantitative cutoff score. Certain qualitative error types on the FIT showed promise and had low FP rates. The WRT obtained an FP rate of 0.0% with previously reported cutoff scores. Finally, the TOMM demonstrated low FP rates of 4.8% and 0.0% on Trial 2 and the Retention Trial, respectively, when applying the standard cutoff score. FP rates are reported for a range of cutoff scores and compared with published research on individuals diagnosed with ID. Results indicated that although the quantitative variables on the FIT had unacceptably high FP rates, the TOMM and WRT had low FP rates, increasing the confidence clinicians can place in scores reflecting poor effort on these measures during ID evaluations. © The Author(s) 2014.

  9. Combination of RNA- and exome-sequencing efficiently eliminates false-positive somatic point mutations and indels – exemplified by cases of CN-AML

    DEFF Research Database (Denmark)

    Herborg, Laura Laine; Hansen, Marcus Celik; Roug, Anne Stidsholt

    Thorough annotation as a means of detecting highly relevant mutations, and aberrated genes, is becoming more feasible as the evidence of biological pathways underlying malignant transformation compiles. However, there is a continuous risk of misinterpretating both true and false positive observat......Thorough annotation as a means of detecting highly relevant mutations, and aberrated genes, is becoming more feasible as the evidence of biological pathways underlying malignant transformation compiles. However, there is a continuous risk of misinterpretating both true and false positive...... in the workflow, not only provides information on malignant expression profiles excluded here, but importantly help to capture the, often very few somatic mutations of myeloid leukaemia....

  10. Myositis ossificans: a false positive of malignancy in PET - CT F.D.G. and in osseous scintigraphy with HMDP 99Tc

    International Nuclear Information System (INIS)

    Hassler, S.; Bourahla, K.

    2010-01-01

    Myositis ossificans is a difficult differential diagnosis and a false positive for malignancy in both 99m Tc H.M.D.P. (hydroxy-methylene diphosphonate) scintigraphy and in exploration PET-F.D.G. This hypothesis should be mentioned in case of young patients, despite the unusual scintigraphic appearance in a benign process. (N.C.)

  11. Different percentages of false-positive results obtained using five methods for the calculation of reference change values based on simulated normal and ln-normal distributions of data

    DEFF Research Database (Denmark)

    Lund, Flemming; Petersen, Per Hyltoft; Fraser, Callum G

    2016-01-01

    a homeostatic set point that follows a normal (Gaussian) distribution. This set point (or baseline in steady-state) should be estimated from a set of previous samples, but, in practice, decisions based on reference change value are often based on only two consecutive results. The original reference change value......-positive results. The aim of this study was to investigate false-positive results using five different published methods for calculation of reference change value. METHODS: The five reference change value methods were examined using normally and ln-normally distributed simulated data. RESULTS: One method performed...... best in approaching the theoretical false-positive percentages on normally distributed data and another method performed best on ln-normally distributed data. The commonly used reference change value method based on two results (without use of estimated set point) performed worst both on normally...

  12. Placing symptoms in context: the role of contextual criteria in reducing false positives in Diagnostic and Statistical Manual of Mental Disorders diagnoses.

    Science.gov (United States)

    Wakefield, Jerome C; First, Michael B

    2012-02-01

    The Diagnostic and Statistical Manual of Mental Disorders (DSM) definition of mental disorder requires that symptoms be caused by a dysfunction in the individual; when dysfunction is absent, symptoms represent normal-range distress or eccentricity and, if diagnosed as a mental disorder, are false positives. We hypothesized that because of psychiatry's lack of direct laboratory tests to distinguish dysfunction from normal-range distress, the context in which symptoms occur (eg, lack of imminent danger in a panic attack) is often essential to determining whether symptoms are caused by a dysfunction. If this is right, then the DSM diagnostic criteria should include many contextual criteria added to symptom syndromes to prevent dysfunction false positives. Despite their potential importance, such contextual criteria have not been previously reviewed. We, thus, systematically reviewed DSM categories to establish the extent of such uses of contextual criteria and created a typology of such uses. Of 111 sampled categories, 68 (61%) used context to prevent dysfunction false positives. Contextual criteria fell into 7 types: (1) exclusion of specific false-positive scenarios; (2) requiring that patients experience preconditions for normal responses (eg, requiring that individuals experience adequate sexual stimulation before being diagnosed with sexual dysfunctions); (3) requiring that symptoms be disproportionate relative to circumstances; (4) for childhood disorders, requiring that symptoms be developmentally inappropriate; (5) requiring that symptoms occur in multiple contexts; (6) requiring a substantial discrepancy between beliefs and reality; and (7) a residual category. Most DSM categories include contextual criteria to eliminate false-positive diagnoses and increase validity of descriptive criteria. Future revisions should systematically evaluate each category's need for contextual criteria. Copyright © 2012 Elsevier Inc. All rights reserved.

  13. Curved planar reformation and optimal path tracing (CROP) method for false positive reduction in computer-aided detection of pulmonary embolism in CTPA

    Science.gov (United States)

    Zhou, Chuan; Chan, Heang-Ping; Guo, Yanhui; Wei, Jun; Chughtai, Aamer; Hadjiiski, Lubomir M.; Sundaram, Baskaran; Patel, Smita; Kuriakose, Jean W.; Kazerooni, Ella A.

    2013-03-01

    The curved planar reformation (CPR) method re-samples the vascular structures along the vessel centerline to generate longitudinal cross-section views. The CPR technique has been commonly used in coronary CTA workstation to facilitate radiologists' visual assessment of coronary diseases, but has not yet been used for pulmonary vessel analysis in CTPA due to the complicated tree structures and the vast network of pulmonary vasculature. In this study, a new curved planar reformation and optimal path tracing (CROP) method was developed to facilitate feature extraction and false positive (FP) reduction and improve our PE detection system. PE candidates are first identified in the segmented pulmonary vessels at prescreening. Based on Dijkstra's algorithm, the optimal path (OP) is traced from the pulmonary trunk bifurcation point to each PE candidate. The traced vessel is then straightened and a reformatted volume is generated using CPR. Eleven new features that characterize the intensity, gradient, and topology are extracted from the PE candidate in the CPR volume and combined with the previously developed 9 features to form a new feature space for FP classification. With IRB approval, CTPA of 59 PE cases were retrospectively collected from our patient files (UM set) and 69 PE cases from the PIOPED II data set with access permission. 595 and 800 PEs were manually marked by experienced radiologists as reference standard for the UM and PIOPED set, respectively. At a test sensitivity of 80%, the average FP rate was improved from 18.9 to 11.9 FPs/case with the new method for the PIOPED set when the UM set was used for training. The FP rate was improved from 22.6 to 14.2 FPs/case for the UM set when the PIOPED set was used for training. The improvement in the free response receiver operating characteristic (FROC) curves was statistically significant (p<0.05) by JAFROC analysis, indicating that the new features extracted from the CROP method are useful for FP reduction.

  14. Pheochromocytoma as a frequent false-positive in adrenal washout CT. A systematic review and meta-analysis

    Energy Technology Data Exchange (ETDEWEB)

    Woo, Sungmin; Kim, Sang Youn [Seoul National University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Suh, Chong Hyun [University of Ulsan College of Medicine, Asan Medical Center, Department of Radiology and Research Institute of Radiology, Seoul (Korea, Republic of); Namwon Medical Center, Department of Radiology, Namwon-si, Jeollabuk-do (Korea, Republic of); Cho, Jeong Yeon; Kim, Seung Hyup [Seoul National University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Seoul National University Medical Research Center, Institute of Radiation Medicine and Kidney Research Institute, Seoul (Korea, Republic of)

    2018-03-15

    To evaluate the proportion of pheochromocytomas meeting the criteria for adenoma on adrenal washout CT and the diagnostic performance of adrenal washout CT for differentiating adenoma from pheochromocytoma. MEDLINE and EMBASE were searched to 28 March 2017. We included studies that used adrenal washout CT for characterisation of pheochromocytomas. Two independent reviewers assessed the methodological quality using Quality Assessment of Diagnostic Accuracy Studies-2. Proportions were pooled using an inverse variance method for calculating weights (random-effects). Sensitivity and specificity were pooled using hierarchical logistic regression modelling and plotted in a hierarchical summary receiver-operating-characteristics (HSROC) plot. Ten studies (114 pheochromocytomas) were included. The pooled proportion of pheochromocytomas meeting the criteria for adenomas was 35 % (95 % CI 20-51). For eight studies providing information on diagnostic performance, the pooled sensitivity and specificity for differentiating adenoma from pheochromocytoma were 0.97 (95 % CI 0.93-0.99) and 0.67 (95 % CI 0.44-0.84), respectively. The area under the HSROC curve was 0.97 (95 % CI 0.95-0.98). There was a non-negligible proportion of pheochromocytomas meeting the criteria for adenoma on adrenal washout CT. Although overall diagnostic performance was excellent for differentiating adenoma from pheochromocytoma, specificity was relatively low. (orig.)

  15. ADAM 12 may be used to reduce the false positive rate of first trimester combined screening for Down syndrome

    DEFF Research Database (Denmark)

    Christiansen, Michael; Pihl, Kasper; Hedley, Paula L.

    2010-01-01

    BACKGROUND: ADAM12 has been shown to be an efficient maternal serum marker for Down syndrome (DS) in the first trimester; but recent studies, using a second generation assay, have not confirmed these findings. We examined the efficiency of a second generation assay for ADAM12. MATERIALS AND METHODS...

  16. Pheochromocytoma as a frequent false-positive in adrenal washout CT. A systematic review and meta-analysis

    International Nuclear Information System (INIS)

    Woo, Sungmin; Kim, Sang Youn; Suh, Chong Hyun; Cho, Jeong Yeon; Kim, Seung Hyup

    2018-01-01

    To evaluate the proportion of pheochromocytomas meeting the criteria for adenoma on adrenal washout CT and the diagnostic performance of adrenal washout CT for differentiating adenoma from pheochromocytoma. MEDLINE and EMBASE were searched to 28 March 2017. We included studies that used adrenal washout CT for characterisation of pheochromocytomas. Two independent reviewers assessed the methodological quality using Quality Assessment of Diagnostic Accuracy Studies-2. Proportions were pooled using an inverse variance method for calculating weights (random-effects). Sensitivity and specificity were pooled using hierarchical logistic regression modelling and plotted in a hierarchical summary receiver-operating-characteristics (HSROC) plot. Ten studies (114 pheochromocytomas) were included. The pooled proportion of pheochromocytomas meeting the criteria for adenomas was 35 % (95 % CI 20-51). For eight studies providing information on diagnostic performance, the pooled sensitivity and specificity for differentiating adenoma from pheochromocytoma were 0.97 (95 % CI 0.93-0.99) and 0.67 (95 % CI 0.44-0.84), respectively. The area under the HSROC curve was 0.97 (95 % CI 0.95-0.98). There was a non-negligible proportion of pheochromocytomas meeting the criteria for adenoma on adrenal washout CT. Although overall diagnostic performance was excellent for differentiating adenoma from pheochromocytoma, specificity was relatively low. (orig.)

  17. Small Intestinal Bacterial Overgrowth May Increase the Likelihood of Lactose and Sorbitol but not Fructose Intolerance False Positive Diagnosis.

    Science.gov (United States)

    Perets, Tsachi Tsadok; Hamouda, Dalal; Layfer, Olga; Ashorov, Olga; Boltin, Doron; Levy, Sigal; Niv, Yaron; Dickman, Ram

    2017-08-01

    Small intestinal bacterial overgrowth (SIBO) is defined as a bacterial count of more than 10 5 colony-forming units per milliliter in duodenal aspirate. It shares many symptoms with carbohydrate intolerance, which makes the clinical distinction of the disorders difficult. The aim of the study was to examine the relationship between a positive carbohydrate breath test and the presence of SIBO suggested by a positive lactulose hydrogen breath test. The electronic database of the gastroenterology laboratory of a tertiary medical center was searched for all patients clinically tested for SIBO in 2012-2013 for whom previous results for lactose, fructose, and/or sorbitol breath test were available. The correlation between positive findings for carbohydrate intolerance and for SIBO was statistically analyzed. The study group included 349 patients, 231 female and 118 male, of mean age 53±19 years. All had symptoms of abdominal bloating and gas. There was a statistically significant difference in rates of a positive breath test for lactose and sorbitol at ≤90 minutes between patients who were positive and negative for SIBO [χ 2 (1)=12.8, p <0.01 and χ 2 (1)=9.5, p <0.01 respectively]. Findings for fructose were not significant. There was no effect of age or gender. SIBO may represent an important reversible cause of carbohydrate intolerance. It may be especially prudent to exclude SIBO patients with an early peak (≤90 minutes) in H 2 excretion. © 2017 by the Association of Clinical Scientists, Inc.

  18. Formalin fixation increases deamination mutation signature but should not lead to false positive mutations in clinical practice.

    Directory of Open Access Journals (Sweden)

    Leah M Prentice

    Full Text Available Genomic analysis of cancer tissues is an essential aspect of personalized oncology treatment. Though it has been suggested that formalin fixation of patient tissues may be suboptimal for molecular studies, this tissue processing approach remains the industry standard. Therefore clinical molecular laboratories must be able to work with formalin fixed, paraffin embedded (FFPE material. This study examines the effects of pre-analytic variables introduced by routine pathology processing on specimens used for clinical reports produced by next-generation sequencing technology. Tissue resected from three colorectal cancer patients was subjected to 2, 15, 24, and 48 hour fixation times in neutral buffered formalin. DNA was extracted from all tissues twice, once with uracil-N-glycosylase (UNG treatment to counter deamination effects, and once without. Of note, deamination events at methylated cytosine, as found at CpG sites, remains unaffected by UNG. After extraction a two-step PCR targeted sequencing method was performed using the Illumina MiSeq and the data was analyzed via a custom-built bioinformatics pipeline, including filtration of reads with mapping quality T/A mutations that is not represented in DNA treated with UNG. This suggests these errors may be due to deamination events triggered by a longer fixation time. However the allelic frequency of these events remained below the limit of detection for reportable mutations in this assay (<2%. We do however recommend that suspected intratumoral heterogeneity events be verified by re-sequencing the same FFPE block.

  19. [Tropheryma whipplei and Whipple disease: false positive PCR detections of Tropheryma whipplei in diagnostic samples are rare].

    Science.gov (United States)

    Le Scanff, J; Gaultier, J B; Durand, D Vital; Durieu, I; Celard, M; Benito, Y; Vandenesch, F; Rousset, H

    2008-11-01

    PCR can be used to detect T. whipplei (Tw) in samples from variable tissue types and body fluids. We report clinical, evolutive characteristics and final diagnosis in patients with positive Tw PCR assay. Retrospective study of Tw PCR realized since 10years in a microbiology laboratory. Twenty-five Tw PCR assays were positive among 200 realized. Diagnosis was not confirmed in six cases. One patient was missing for follow up. Eighteen patients presented with Whipple's disease. Among these 18 patients, 14 had a classic Whipple's disease, three patients presented an endocarditis and one patient isolated neurological manifestations. Ten patients presented fever, seven a weight loss and 12 joint involvement. Four patients presented cutaneous manifestations, only six had gastrointestinal symptoms. Neurological involvement was reported in five cases, pulmonary symptoms in four cases, cardiac involvement in six cases and ocular signs in two cases. Anemia was reported in four patients and elevated levels of acute-phase reactants in 14 cases. Positive predictive value of Tw PCR for Whipple's disease diagnosis was 75%. Thirteen patients had a good evolution with antibiotics. Three patients presented recurrence and two cases with cardiovascular involvement died. Whipple's disease is rare but often mentioned in internist experience. The diagnosis should be every time confirmed. Tw PCR assay is an important diagnostic tool but is not sufficient to establish the diagnosis and must be interpreted with histopathology and immunohistochemical testing results.

  20. ABIOTIC O2 LEVELS ON PLANETS AROUND F, G, K, AND M STARS: POSSIBLE FALSE POSITIVES FOR LIFE?

    International Nuclear Information System (INIS)

    Harman, C. E.; Kasting, J. F.; Schwieterman, E. W.; Schottelkotte, J. C.

    2015-01-01

    In the search for life on Earth-like planets around other stars, the first (and likely only) information will come from the spectroscopic characterization of the planet's atmosphere. Of the countless number of chemical species terrestrial life produces, only a few have the distinct spectral features and the necessary atmospheric abundance to be detectable. The easiest of these species to observe in Earth's atmosphere is O 2 (and its photochemical byproduct, O 3 ). However, O 2 can also be produced abiotically by photolysis of CO 2 , followed by recombination of O atoms with each other. CO is produced in stoichiometric proportions. Whether O 2 and CO can accumulate to appreciable concentrations depends on the ratio of far-ultraviolet (FUV) to near-ultraviolet (NUV) radiation coming from the planet's parent star and on what happens to these gases when they dissolve in a planet's oceans. Using a one-dimensional photochemical model, we demonstrate that O 2 derived from CO 2 photolysis should not accumulate to measurable concentrations on planets around F- and G-type stars. K-star, and especially M-star planets, however, may build up O 2 because of the low NUV flux from their parent stars, in agreement with some previous studies. On such planets, a “false positive” for life is possible if recombination of dissolved CO and O 2 in the oceans is slow and if other O 2 sinks (e.g., reduced volcanic gases or dissolved ferrous iron) are small. O 3 , on the other hand, could be detectable at UV wavelengths (λ < 300 nm) for a much broader range of boundary conditions and stellar types

  1. ABIOTIC O{sub 2} LEVELS ON PLANETS AROUND F, G, K, AND M STARS: POSSIBLE FALSE POSITIVES FOR LIFE?

    Energy Technology Data Exchange (ETDEWEB)

    Harman, C. E.; Kasting, J. F. [Geosciences Department, Pennsylvania State University, University Park, PA 16802 (United States); Schwieterman, E. W. [NASA Astrobiology Institute—Virtual Planetary Laboratory (United States); Schottelkotte, J. C., E-mail: ceharmanjr@psu.edu [Astronomy Department, Pennsylvania State University, University Park, PA 16802 (United States)

    2015-10-20

    In the search for life on Earth-like planets around other stars, the first (and likely only) information will come from the spectroscopic characterization of the planet's atmosphere. Of the countless number of chemical species terrestrial life produces, only a few have the distinct spectral features and the necessary atmospheric abundance to be detectable. The easiest of these species to observe in Earth's atmosphere is O{sub 2} (and its photochemical byproduct, O{sub 3}). However, O{sub 2} can also be produced abiotically by photolysis of CO{sub 2}, followed by recombination of O atoms with each other. CO is produced in stoichiometric proportions. Whether O{sub 2} and CO can accumulate to appreciable concentrations depends on the ratio of far-ultraviolet (FUV) to near-ultraviolet (NUV) radiation coming from the planet's parent star and on what happens to these gases when they dissolve in a planet's oceans. Using a one-dimensional photochemical model, we demonstrate that O{sub 2} derived from CO{sub 2} photolysis should not accumulate to measurable concentrations on planets around F- and G-type stars. K-star, and especially M-star planets, however, may build up O{sub 2} because of the low NUV flux from their parent stars, in agreement with some previous studies. On such planets, a “false positive” for life is possible if recombination of dissolved CO and O{sub 2} in the oceans is slow and if other O{sub 2} sinks (e.g., reduced volcanic gases or dissolved ferrous iron) are small. O{sub 3}, on the other hand, could be detectable at UV wavelengths (λ < 300 nm) for a much broader range of boundary conditions and stellar types.

  2. High prevalence of human anti-bovine IgG antibodies as the major cause of false positive reactions in two-site immunoassays based on monoclonal antibodies

    DEFF Research Database (Denmark)

    Andersen, Ditte C; Koch, Claus; Jensen, Charlotte H

    2004-01-01

    were purified by protein G affinity chromatography from culture supernatant containing 10% (v/v) fetal calf serum (FCS). Human anti-animal IgG (bovine, mouse, horse, and swine) antibodies and human anti-bovine serum albumin antibodies were measured using an ELISA design, with direct bridging...... of the solid phase and biotinylated antigens. The false positive reactions were abolished by addition of 1% (v/v) bovine serum to the dilution buffer (DB). Human anti-bovine IgG antibodies (HABIA) were detected in 99 out of 104 sera from blood donors (50 females; 54 males). HABIA levels in male sera (n = 54......) were positively correlated to the false positive signals in the PP14 ELISA (r = 0.923; p detected in the donor sera, but levels and frequencies were lower compared to that of HABIA. Furthermore, HABIA were...

  3. False-positive positron emission tomography appearance with 18F-fluorodeoxyglucose after definitive radiotherapy for cancer of the mobile tongue.

    Science.gov (United States)

    Ariji, Y; Fuwa, N; Kodaira, T; Tachibana, H; Nakamura, T; Satoh, Y; Ariji, E

    2009-01-01

    (18)F-fluorodeoxyglucose-positron emission tomography (FDG-PET) is an effective tool for evaluating the results of radiotherapy. However, some false-positive appearances caused by physiological or pathological accumulation are reported. We report on three patients who showed a high accumulation of FDG in the lingual muscles but had no recurrent tumour after definitive radiotherapy for the mobile tongue. All patients had squamous cell carcinoma of the tongue and received interstitial radiotherapy with small sources. High uptake was seen in the lingual muscles without recurrence or inflammation, based on physical and MR examinations. This false-positive appearance is thought to relate to ill-balanced high activity of the lingual muscles after definitive radiotherapy.

  4. Evaluation of HIV testing algorithms in Ethiopia: the role of the tie-breaker algorithm and weakly reacting test lines in contributing to a high rate of false positive HIV diagnoses.

    Science.gov (United States)

    Shanks, Leslie; Siddiqui, M Ruby; Kliescikova, Jarmila; Pearce, Neil; Ariti, Cono; Muluneh, Libsework; Pirou, Erwan; Ritmeijer, Koert; Masiga, Johnson; Abebe, Almaz

    2015-02-03

    In Ethiopia a tiebreaker algorithm using 3 rapid diagnostic tests (RDTs) in series is used to diagnose HIV. Discordant results between the first 2 RDTs are resolved by a third 'tiebreaker' RDT. Médecins Sans Frontières uses an alternate serial algorithm of 2 RDTs followed by a confirmation test for all double positive RDT results. The primary objective was to compare the performance of the tiebreaker algorithm with a serial algorithm, and to evaluate the addition of a confirmation test to both algorithms. A secondary objective looked at the positive predictive value (PPV) of weakly reactive test lines. The study was conducted in two HIV testing sites in Ethiopia. Study participants were recruited sequentially until 200 positive samples were reached. Each sample was re-tested in the laboratory on the 3 RDTs and on a simple to use confirmation test, the Orgenics Immunocomb Combfirm® (OIC). The gold standard test was the Western Blot, with indeterminate results resolved by PCR testing. 2620 subjects were included with a HIV prevalence of 7.7%. Each of the 3 RDTs had an individual specificity of at least 99%. The serial algorithm with 2 RDTs had a single false positive result (1 out of 204) to give a PPV of 99.5% (95% CI 97.3%-100%). The tiebreaker algorithm resulted in 16 false positive results (PPV 92.7%, 95% CI: 88.4%-95.8%). Adding the OIC confirmation test to either algorithm eliminated the false positives. All the false positives had at least one weakly reactive test line in the algorithm. The PPV of weakly reacting RDTs was significantly lower than those with strongly positive test lines. The risk of false positive HIV diagnosis in a tiebreaker algorithm is significant. We recommend abandoning the tie-breaker algorithm in favour of WHO recommended serial or parallel algorithms, interpreting weakly reactive test lines as indeterminate results requiring further testing except in the setting of blood transfusion, and most importantly, adding a confirmation test

  5. Efficient detection of human circulating tumor cells without significant production of false-positive cells by a novel conditionally replicating adenovirus

    Directory of Open Access Journals (Sweden)

    Fuminori Sakurai

    2016-01-01

    Full Text Available Circulating tumor cells (CTCs are promising biomarkers in several cancers, and thus methods and apparatuses for their detection and quantification in the blood have been actively pursued. A novel CTC detection system using a green fluorescence protein (GFP–expressing conditionally replicating adenovirus (Ad (rAd-GFP was recently developed; however, there is concern about the production of false-positive cells (GFP-positive normal blood cells when using rAd-GFP, particularly at high titers. In addition, CTCs lacking or expressing low levels of coxsackievirus–adenovirus receptor (CAR cannot be detected by rAd-GFP, because rAd-GFP is constructed based on Ad serotype 5, which recognizes CAR. In order to suppress the production of false-positive cells, sequences perfectly complementary to blood cell–specific microRNA, miR-142-3p, were incorporated into the 3′-untranslated region of the E1B and GFP genes. In addition, the fiber protein was replaced with that of Ad serotype 35, which recognizes human CD46, creating rAdF35-142T-GFP. rAdF35-142T-GFP efficiently labeled not only CAR-positive tumor cells but also CAR-negative tumor cells with GFP. The numbers of false-positive cells were dramatically lower for rAdF35-142T-GFP than for rAd-GFP. CTCs in the blood of cancer patients were detected by rAdF35-142T-GFP with a large reduction in false-positive cells.

  6. Clinical evaluation of false-positive scintigraphic lesions of the left lobe in portal hypertension. Comparison with portographic findings of the pars umbilicus of the portal vein

    Energy Technology Data Exchange (ETDEWEB)

    Takayasu, Kenichi; Moriyama, Noriyuki; Suzuki, Masao; Yamada, Tatsuya [National Cancer Center, Tokyo (Japan). Hospital; Fukutake, Toshio

    1982-09-01

    sup(99m)Tc-phytate liver scan and percutaneous transhepatic portography (PTP) were performed in 33 patients with portal hypertension due to various hepatic diseases. A defect or space occupying lesion in the left lobe on the scan in these patients was analysed with reference to portographic changes of the pars umbilicus of the left portal vein and the following results were obtained. 1) A false-positive defect on the scintigram was found in 6 (18.2%) of 33 patients, and portal vein pressure (PVP) was above 200 mmH/sub 2/O in all 6 which constituted 21.4% of 28 with PVP above 200 mmH/sub 2/O. 2) In five out of 6 patients with false-positive scan findings, the pars umbilicus was dilated to more than 25 x 15 mm in size, and it was huge and tortuous in 3 of them. 3) The mean PVP in the group with a false-positive scan tended to be higher than that in patients with no abnormalities on the scintigram. It was concluded that in reading of liver scintigrams in patients with portal hypertension, a dilated pars umbilicus and huge para-umbilical vein should be considered.

  7. A mode of error: Immunoglobulin binding protein (a subset of anti-citrullinated proteins can cause false positive tuberculosis test results in rheumatoid arthritis

    Directory of Open Access Journals (Sweden)

    Maria Greenwald

    2017-12-01

    Full Text Available Citrullinated Immunoglobulin Binding Protein (BiP is a newly described autoimmune target in rheumatoid arthritis (RA, one of many cyclic citrullinated peptides(CCP or ACPA. BiP is over-expressed in RA patients causing T cell expansion and increased interferon levels during incubation for the QuantiFERON-Gold tuberculosis test (QFT-G TB. The QFT-G TB has never been validated where interferon is increased by underlying disease, as for example RA.Of ACPA-positive RA patients (n = 126, we found a 13% false-positive TB test rate by QFT-G TB. Despite subsequent biologic therapy for 3 years of all 126 RA patients, none showed evidence of TB without INH. Most of the false-positive RA patients after treatment with biologic therapy reverted to a negative QFT-G test. False TB tests correlated with ACPA level (p < 0.02.Three healthy women without arthritis or TB exposure had negative QFT-G TB. In vitro, all three tested positive every time for TB correlating to the dose of BiP or anti-BiP added, at 2 ug/ml, 5 ug/ml, 10 ug/ml, and 20 ug/ml.BiP naturally found in the majority of ACPA-positive RA patients can result in a false positive QFT-G TB. Subsequent undertreatment of RA, if biologic therapy is withheld, and overtreatment of presumed latent TB may harm patients. Keywords: Tuberculosis, IGRA, Rheumatoid arthritis, Interferon, Anti-citrullinated peptide antibody (ACPA, Immunoglobulin binding protein (BiP

  8. False-positive radioactive iodine uptake mimicking miliary lung metastases in a patient affected by papillary thyroid cancer and IgA deficiency

    Energy Technology Data Exchange (ETDEWEB)

    Demidowich, Andrew Paul; Reynolds, James C. [National Institutes of Health, Bethesda (United States); Kundu, Amartya [Dept. of MedicineUniversity of Massachusetts Medical School, Worcester (United States); Celi, Francesco S. [Div. of Endocrinology and MetabolismVirginia Commonwealth UniversityRichmond (United States)

    2016-09-15

    A 42-year-old female with immunoglobulin A deficiency and recurrent sinopulmonary infections underwent thyroidectomy for papillary thyroid cancer (PTC). Follow-up {sup 123}I scintigraphy demonstrated diffuse pulmonary uptake, suggesting metastatic disease. However, subsequent pathologic, biochemical and radiographic testing proved that she was in fact disease free, and the initial {sup 123}I pulmonary uptake was identified as a false positive. Inflammatory conditions may rarely cause iodine uptake in non-thyroidal tissues due to local retention, organification, and/or immunologic utilization. To avoid exposing patients to unnecessary treatments, it is critical for clinicians to recognize that comorbid pulmonary conditions may mimic metastatic PTC on radioiodine scintigraphy.

  9. A Nested PCR Assay to Avoid False Positive Detection of the Microsporidian Enterocytozoon hepatopenaei (EHP) in Environmental Samples in Shrimp Farms

    Science.gov (United States)

    Jaroenlak, Pattana; Sanguanrut, Piyachat; Williams, Bryony A. P.; Stentiford, Grant D.; Flegel, Timothy W.; Sritunyalucksana, Kallaya

    2016-01-01

    Hepatopancreatic microsporidiosis (HPM) caused by Enterocytozoon hepatopenaei (EHP) is an important disease of cultivated shrimp. Heavy infections may lead to retarded growth and unprofitable harvests. Existing PCR detection methods target the EHP small subunit ribosomal RNA (SSU rRNA) gene (SSU-PCR). However, we discovered that they can give false positive test results due to cross reactivity of the SSU-PCR primers with DNA from closely related microsporidia that infect other aquatic organisms. This is problematic for investigating and monitoring EHP infection pathways. To overcome this problem, a sensitive and specific nested PCR method was developed for detection of the spore wall protein (SWP) gene of EHP (SWP-PCR). The new SWP-PCR method did not produce false positive results from closely related microsporidia. The first PCR step of the SWP-PCR method was 100 times (104 plasmid copies per reaction vial) more sensitive than that of the existing SSU-PCR method (106 copies) but sensitivity was equal for both in the nested step (10 copies). Since the hepatopancreas of cultivated shrimp is not currently known to be infected with microsporidia other than EHP, the SSU-PCR methods are still valid for analyzing hepatopancreatic samples despite the lower sensitivity than the SWP-PCR method. However, due to its greater specificity and sensitivity, we recommend that the SWP-PCR method be used to screen for EHP in feces, feed and environmental samples for potential EHP carriers. PMID:27832178

  10. A Nested PCR Assay to Avoid False Positive Detection of the Microsporidian Enterocytozoon hepatopenaei (EHP) in Environmental Samples in Shrimp Farms.

    Science.gov (United States)

    Jaroenlak, Pattana; Sanguanrut, Piyachat; Williams, Bryony A P; Stentiford, Grant D; Flegel, Timothy W; Sritunyalucksana, Kallaya; Itsathitphaisarn, Ornchuma

    2016-01-01

    Hepatopancreatic microsporidiosis (HPM) caused by Enterocytozoon hepatopenaei (EHP) is an important disease of cultivated shrimp. Heavy infections may lead to retarded growth and unprofitable harvests. Existing PCR detection methods target the EHP small subunit ribosomal RNA (SSU rRNA) gene (SSU-PCR). However, we discovered that they can give false positive test results due to cross reactivity of the SSU-PCR primers with DNA from closely related microsporidia that infect other aquatic organisms. This is problematic for investigating and monitoring EHP infection pathways. To overcome this problem, a sensitive and specific nested PCR method was developed for detection of the spore wall protein (SWP) gene of EHP (SWP-PCR). The new SWP-PCR method did not produce false positive results from closely related microsporidia. The first PCR step of the SWP-PCR method was 100 times (104 plasmid copies per reaction vial) more sensitive than that of the existing SSU-PCR method (106 copies) but sensitivity was equal for both in the nested step (10 copies). Since the hepatopancreas of cultivated shrimp is not currently known to be infected with microsporidia other than EHP, the SSU-PCR methods are still valid for analyzing hepatopancreatic samples despite the lower sensitivity than the SWP-PCR method. However, due to its greater specificity and sensitivity, we recommend that the SWP-PCR method be used to screen for EHP in feces, feed and environmental samples for potential EHP carriers.

  11. The Relations Between False Positive and Negative Screens and Smoking Cessation and Relapse in the National Lung Screening Trial: Implications for Public Health.

    Science.gov (United States)

    Clark, Melissa A; Gorelick, Jeremy J; Sicks, JoRean D; Park, Elyse R; Graham, Amanda L; Abrams, David B; Gareen, Ilana F

    2016-01-01

    Lung screening is an opportunity for smoking cessation and relapse prevention, but smoking behaviors may differ across screening results. Changes in smoking were evaluated among 18 840 current and former smokers aged 55-74 scheduled to receive three annual lung screenings. Participants were randomized to low-dose computed tomography or single-view chest radiography in the American College of Radiology/National Lung Screening Trial. Outcome measures included point and sustained (6-month) abstinence and motivation to quit among smokers; and relapse among smokers who quit during follow-up, recent quitters (quit < 6 months), and long-term former smokers (quit ≥ 6 months). During five years of follow-up, annual point prevalence quit rates ranged from 11.6%-13.4%; 48% of current smokers reported a quit attempt and 7% of long-term former smokers relapsed. Any false positive screening result was associated with subsequent increased point (multivariable hazard ratio HR = 1.23, 95% CI = 1.13, 1.35) and sustained (HR = 1.28, 95% CI = 1.15, 1.43) abstinence among smokers. Recent quitters with ≥1 false positive screen were less likely to relapse (HR = 0.72, 95% CI = 0.54, 0.96). Screening result was not associated with relapse among long-term former smokers or among baseline smokers who quit during follow-up. A false positive screen was associated with increased smoking cessation and less relapse among recent quitters. Consistently negative screens were not associated with greater relapse among long-term former smokers. Given the Affordable Care Act requires most health plans to cover smoking cessation and lung screening, the impact and cost-effectiveness of lung screening could be further enhanced with the addition of smoking cessation interventions. © The Author 2015. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  12. False-positive 18F-fluorodeoxyglucose positron emission tomography/computed tomography in a patient with metallic implants following chondrosarcoma resection.

    Science.gov (United States)

    Zhou, P U; Tang, Jinliang; Zhang, Dong; Li, Guanghui

    2016-05-01

    Positron emission tomography (PET) with fluorine-18-labeled fluorodeoxyglucose ( 18 F-FDG) has been used for the staging and evaluation of recurrence in cancer patients. We herein report a false-positive result of 18 F-FDG PET/computed tomography (CT) scan in a patient following chondrosarcoma resection and metallic implanting. A 35-year-old male patient with chondrosarcoma of the left iliac bone underwent radical resection, metal brace implanting and radiotherapy. A high uptake of 18 F-FDG was observed in the metallic implants and adjacent tissue during PET/CT scanning in the 5th year of follow-up. Tissue biopsy and follow-up examination identified no tumor recurrence or infection at these sites, suggesting that the results of 18 F-FDG PET/CT must be interpreted with caution in cancer patients with metallic implants.

  13. Chemical applicability domain of the Local Lymph Node Assay (LLNA) for skin sensitisation potency. Part 3. Apparent discrepancies between LLNA and GPMT sensitisation potential: False positives or differences in sensitivity?

    Science.gov (United States)

    Roberts, David W; Schultz, Terry W; Api, Anne Marie

    2016-10-01

    The Local Lymph Node Assay (LLNA) is the gold standard regulatory toxicology test for skin sensitisation along with the guinea pig maximisation test (GPMT). Compared with the GPMT, LLNA uses fewer animals, it is quantitative, and it gives a numerical prediction of potency. However several concerns have been raised with this assay, mainly related to false positives and false negatives. Over the years, many authors, including the developers of the assay, have presented cases where there have been discrepancies between the GMPT and LLNA results. Several theories have been put forward for these discrepancies, the main one being the "over-sensitivity" of the GPMT. This paper analyses the data from a systematic study, published in three papers from 2008 to 2011, covering several classes of chemicals, in particular unsaturated fatty acids, sugar surfactants and ethoxylated alcohols, with many cases of chemicals testing positive in the LLNA being negative in the GPMT. Based on consideration of reaction chemistry and structural alerts, it is concluded that these discrepancies are not LLNA false positives, but can be rationalised in terms of the different protocols of the assays. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Recent lung imaging studies

    International Nuclear Information System (INIS)

    Taplin, G.V.; Chopra, S.K.

    1976-01-01

    Radionuclide lung imaging procedures have been available for 11 years but only the perfusion examination has been used extensively and mainly for the diagnosis of pulmonary embolism (P.E.). Its ability to reveal localized ischemia makes it a valuable test of regional lung function as well as a useful diagnostic aid in P.E. Although it had been recognized for several years that chronic obstructive pulmonary disease (COPD) can cause lung perfusion defects which may simulate pulmonary embolism, relatively little use has been made of either the radioxenon or the radioaerosol inhalation lung imaging procedures until the last few years as a means of distinguishing P.E. from COPD. In this review emphasis is placed on our recent experience with both of these inhalation procedures in comparison with pulmonary function tests and roentgenography for the early detection of COPD in population studies. Equal emphasis is given to simultaneous aerosol ventilation-perfusion (V/P) imaging for a functional diagnosis of P.E. Two new developments in regional lung diffusion imaging, performed after the inhalation of radioactive gases and/or rapidly absorbed radioaerosols are described. The experimental basis for their potential clinical application in pulmonary embolism detection is presented

  15. 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).

    Science.gov (United States)

    Miles, Anne; Rodrigues, Vania; Sevdalis, Nick

    2013-11-01

    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. 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. 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. 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. 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. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  16. Next-generation sequencing indicates false-positive MRD results and better predicts prognosis after SCT in patients with childhood ALL.

    Science.gov (United States)

    Kotrova, M; van der Velden, V H J; van Dongen, J J M; Formankova, R; Sedlacek, P; Brüggemann, M; Zuna, J; Stary, J; Trka, J; Fronkova, E

    2017-07-01

    Minimal residual disease (MRD) monitoring via quantitative PCR (qPCR) detection of Ag receptor gene rearrangements has been the most sensitive method for predicting prognosis and making post-transplant treatment decisions for patients with ALL. Despite the broad clinical usefulness and standardization of this method, we and others have repeatedly reported the possibility of false-positive MRD results caused by massive B-lymphocyte regeneration after stem cell transplantation (SCT). Next-generation sequencing (NGS) enables precise and sensitive detection of multiple Ag receptor rearrangements, thus providing a more specific readout compared to qPCR. We investigated two cohorts of children with ALL who underwent SCT (30 patients and 228 samples). The first cohort consisted of 17 patients who remained in long-term CR after SCT despite having low MRD positivity (SCT monitoring using qPCR. Only one of 27 qPCR-positive samples was confirmed to be positive by NGS. Conversely, 10 of 15 samples with low qPCR-detected MRD positivity from 13 patients who subsequently relapsed were also confirmed to be positive by NGS (P=0.002). These data show that NGS has a better specificity in post-SCT ALL management and indicate that treatment interventions aimed at reverting impending relapse should not be based on qPCR only.

  17. Avian metapneumovirus RT-nested-PCR: a novel false positive reducing inactivated control virus with potential applications to other RNA viruses and real time methods.

    Science.gov (United States)

    Falchieri, Marco; Brown, Paul A; Catelli, Elena; Naylor, Clive J

    2012-12-01

    Using reverse genetics, an avian metapneumovirus (AMPV) was modified for use as a positive control for validating all stages of a popular established RT-nested PCR, used in the detection of the two major AMPV subtypes (A and B). Resultant amplicons were of increased size and clearly distinguishable from those arising from unmodified virus, thus allowing false positive bands, due to control virus contamination of test samples, to be identified readily. Absorption of the control virus onto filter paper and subsequent microwave irradiation removed all infectivity while its function as an efficient RT-nested-PCR template was unaffected. Identical amplicons were produced after storage for one year. The modified virus is likely to have application as an internal standard as well as in real time methods. Additions to AMPV of RNA from other RNA viruses, including hazardous examples such HIV and influenza, are likely to yield similar safe RT-PCR controls. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. Detection of Yersinia enterocolitica serotype O:9 in the faeces of cattle with false positive reactions in serological tests for brucellosis in Ireland.

    Science.gov (United States)

    O'Grady, Don; Kenny, Kevin; Power, Seamus; Egan, John; Ryan, Fergus

    2016-10-01

    Intestinal infection by Yersinia enterocolitica serotype O:9 (YeO9) in cattle has been linked to false positive serological reactivity (FPSR) in diagnostic tests for brucellosis. Although eradicated in Ireland, brucellosis monitoring still identifies seropositive animals, usually one or two (termed singletons) per herd, which are classed as FPSR. To investigate a link between FPSR and YeO9, faeces and blood were collected from singleton FPSR cattle, and from companion animals, in eight selected herds with more than one FPSR animal, for YeO9 culture and Brucella serology. YeO9 was isolated from 76/474 (16%) FPSR singletons in 309 herds, but not from any of 621 animals in 122 control non-FPSR herds. In the FPSR herds 52/187 (27.8%) animals were culture positive, and 17% of the isolates were from seronegative animals. Seropositive animals were more likely to have a rising antibody titre when culture positive. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. False Positive 18F-FDG Uptake in Mediastinal Lymph Nodes Detected with Positron Emission Tomography in Breast Cancer: A Case Report

    Directory of Open Access Journals (Sweden)

    Gamze Uğurluer

    2013-01-01

    Full Text Available Breast cancer is the most frequently diagnosed cancer among females. It is accepted that lymph node involvement with metastatic tumor and the presence of distant metastasis are the most important prognostic factors. Accurate staging is important in determining prognosis and appropriate treatment. Positron emission tomography with computed tomography detects malignancies using 2-[18F]-fluoro-2-deoxy-d-glucose (18F-FDG PET CT with high accuracy and they contribute to decisions regarding diagnosis, staging, recurrence, and treatment response. Here, we report a case of false positive metastatic mediastinal lymph nodes that were diagnosed by 18F-FDG PET CT in a 40-year-old breast cancer patient who had undergone preoperative evaluation. Right paratracheal, prevascular, aorticopulmonary, precarinal, subcarinal, hilar, and subhilar multiple conglomerated mediastinal lymph nodes were revealed in addition to left breast mass and axillary lymph nodes. Mediastinoscopy was performed with biopsy and pathology was reported as granulomatous lymphadenitis. In conclusion, any abnormal FDG accumulation in unusual lymph nodes must be evaluated carefully and confirmed histopathologically.

  20. Massive-training artificial neural network (MTANN) for reduction of false positives in computer-aided detection of polyps: Suppression of rectal tubes

    International Nuclear Information System (INIS)

    Suzuki, Kenji; Yoshida, Hiroyuki; Naeppi, Janne; Dachman, Abraham H.

    2006-01-01

    One of the limitations of the current computer-aided detection (CAD) of polyps in CT colonography (CTC) is a relatively large number of false-positive (FP) detections. Rectal tubes (RTs) are one of the typical sources of FPs because a portion of a RT, especially a portion of a bulbous tip, often exhibits a cap-like shape that closely mimics the appearance of a small polyp. Radiologists can easily recognize and dismiss RT-induced FPs; thus, they may lose their confidence in CAD as an effective tool if the CAD scheme generates such ''obvious'' FPs due to RTs consistently. In addition, RT-induced FPs may distract radiologists from less common true positives in the rectum. Therefore, removal RT-induced FPs as well as other types of FPs is desirable while maintaining a high sensitivity in the detection of polyps. We developed a three-dimensional (3D) massive-training artificial neural network (MTANN) for distinction between polyps and RTs in 3D CTC volumetric data. The 3D MTANN is a supervised volume-processing technique which is trained with input CTC volumes and the corresponding ''teaching'' volumes. The teaching volume for a polyp contains a 3D Gaussian distribution, and that for a RT contains zeros for enhancement of polyps and suppression of RTs, respectively. For distinction between polyps and nonpolyps including RTs, a 3D scoring method based on a 3D Gaussian weighting function is applied to the output of the trained 3D MTANN. Our database consisted of CTC examinations of 73 patients, scanned in both supine and prone positions (146 CTC data sets in total), with optical colonoscopy as a reference standard for the presence of polyps. Fifteen patients had 28 polyps, 15 of which were 5-9 mm and 13 were 10-25 mm in size. These CTC cases were subjected to our previously reported CAD scheme that included centerline-based segmentation of the colon, shape-based detection of polyps, and reduction of FPs by use of a Bayesian neural network based on geometric and texture

  1. Contamination in the Kepler field. Identification of 685 KOIs as false positives via ephemeris matching based ON Q1-Q12 data

    Energy Technology Data Exchange (ETDEWEB)

    Coughlin, Jeffrey L.; Thompson, Susan E.; Burke, Christopher J.; Caldwell, Douglas A.; Jenkins, Jon M.; Mullally, Fergal R.; Rowe, Jason F. [SETI Institute, 189 Bernardo Avenue, Mountain View, CA 94043 (United States); Bryson, Stephen T.; Haas, Michael R.; Howell, Steve B. [NASA Ames Research Center, M/S 244-30, Moffett Field, CA 94035 (United States); Christiansen, Jessie L. [NASA Exoplanet Science Institute, California Institute of Technology, Pasadena CA 91125 (United States); Kolodziejczak, Jeffery J., E-mail: jeffrey.l.coughlin@nasa.gov [NASA Marshall Space Flight Center, Huntsville, AL 35812 (United States)

    2014-05-01

    The Kepler mission has to date found almost 6000 planetary transit-like signals, utilizing three years of data for over 170,000 stars at extremely high photometric precision. Due to its design, contamination from eclipsing binaries, variable stars, and other transiting planets results in a significant number of these signals being false positives (FPs). This directly affects the determination of the occurrence rate of Earth-like planets in our Galaxy, as well as other planet population statistics. In order to detect as many of these FPs as possible, we perform ephemeris matching among all transiting planet, eclipsing binary, and variable star sources. We find that 685 Kepler Objects of Interest (KOIs)—12% of all those analyzed—are FPs as a result of contamination, due to 409 unique parent sources. Of these, 118 have not previously been identified by other methods. We estimate that ∼35% of KOIs are FPs due to contamination, when performing a first-order correction for observational bias. Comparing single-planet candidate KOIs to multi-planet candidate KOIs, we find an observed FP fraction due to contamination of 16% and 2.4% respectively, bolstering the existing evidence that multi-planet KOIs are significantly less likely to be FPs. We also analyze the parameter distributions of the ephemeris matches and derive a simple model for the most common type of contamination in the Kepler field. We find that the ephemeris matching technique is able to identify low signal-to-noise FPs that are difficult to identify with other vetting techniques. We expect FP KOIs to become more frequent when analyzing more quarters of Kepler data, and note that many of them will not be able to be identified based on Kepler data alone.

  2. Caprine and ovine Greek dairy products: The official German method generates false-positive results due to κ-casein gene polymorphism.

    Science.gov (United States)

    Tsartsianidou, V; Triantafillidou, D; Karaiskou, N; Tarantili, P; Triantafillidis, G; Georgakis, E; Triantafyllidis, A

    2017-05-01

    Caseins are widely used for species identification of dairy products. Isoelectric focusing (IEF) of para-κ-casein peptide is used as the official German method for the differentiation between caprine (isoform A) and ovine (isoform B) dairy products, based on their different isoelectric points. The discrimination between Greek goat and ewe dairy products using IEF has, however, been shown to be problematic because of the existence of the ewe isoform in milk from Greek indigenous dairy goats. This could be due to nucleotide polymorphisms within the goat κ-casein gene of Greek indigenous breeds, which alter the isoelectric point of the para-κ-casein peptide and lead to false positive results. Previous DNA analysis of the goat κ-casein gene has shown high levels of polymorphism; however, no such information is available for Greek indigenous dairy goats. Therefore, 87 indigenous dairy goats were sequenced at exon IV of κ-casein gene. In total, 9 polymorphic sites were detected. Three nonsynonymous point mutations were identified, which change the isoelectric point of the goat para-κ-casein peptide so that it appears identical to that of the ewe peptide. Ten composite genotypes were reconstructed and 6 of them included the problematic point mutations. For the verification of genetic results, IEF was carried out. Both goat and ewe patterns appeared in the problematic genotypes. The frequency of these genotypes could be characterized as moderate (0.23) to high (0.60) within Greek indigenous breeds. However, this is not an issue restricted to Greece, as such genotypes have been detected in various non-Greek goat breeds. In conclusion, IEF based on the official German method is certainly inappropriate for ovine and caprine discrimination concerning Greek dairy goat products, and consequently a new method should be established. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  3. Raising Awareness of False Positive Newborn Screening Results Arising from Pivalate-Containing Creams and Antibiotics in Europe When Screening for Isovaleric Acidaemia

    Directory of Open Access Journals (Sweden)

    James R. Bonham

    2018-02-01

    Full Text Available While the early and asymptomatic recognition of treatable conditions offered by newborn screening confers clear health benefits for the affected child, the clinical referral of patients with screen positive results can cause significant harm for some families. The use of pivalate-containing antibiotics and more recently the inclusion of neopentanoate as a component within moisturising creams used as nipple balms by nursing mothers can result in a significant number of false positive results when screening for isovaleric acidaemia (IVA by measuring C5 acylcarnitine. A recent survey conducted within centres from nine countries indicated that this form of contamination had been or was a significant confounding factor in the detection of IVA in seven of the nine who responded. In three of these seven the prominent cause was believed to derive from the use of moisturising creams and in another three from antibiotics containing pivalate; one country reported that the cause was mixed. As a result, four of these seven centres routinely perform second tier testing to resolve C5 isobars when an initial C5 result is elevated, and a fifth is considering making this change within their national programme. The use of creams containing neopentanoate by nursing mothers and evolving patterns in the prescription of pivalate-containing antibiotics during pregnancy require those involved in the design and operation of newborn screening programmes used to detect IVA and the doctors who receive clinical referrals from these programmes to maintain an awareness of the potential impact of this form of interference on patient results.

  4. Abiotic production of nitrous oxide by lightning. Implications for a false positive identification of life on Earth-Like Planets around quiescent M Dwarfs

    Science.gov (United States)

    Navarro, Karina F.; Navarro-Gonzalez, Rafael; McKay, Christopher P.

    _{2} dominated primitive Earth-like atmospheres. However, during the rise in atmospheric O _{2} at the start of the Proterozoic, the ocean became stratified (anoxic at the bottom and oxygenic at the surface). During this period, the emissions of N _{2}O were probably higher than today associated with a stronger microbial activity in the early anoxic ocean layer (Grenfell et al., 2011). Under this scenario, the predicted N _{2}O concentration would be about 3920 ppb, considering 10% the current atmospheric O _{2} concentrations, 100 times higher the current microbial N _{2}O flux, and a fainter Sun (94.3%) (Grenfell et al., 2011). This concentration would be still undetectable (Grenfell et al., 2011). A completely different scenario could be expected in Earth-like planets orbiting M dwarfs, which are the most abundant stars in the galaxy, representing about 75% of the total stellar population. M stars exhibit a large range in activity levels from very low levels of chromospheric and coronal activity, the so-called “quiescent” to high levels, the so-called “active" states. Photochemical models predict that the N _{2}O concentration would only increase to about 1,000 ppb for the current Earth orbiting an active M star, but surprisingly up to about 1,000 ppm for the current Earth orbiting a quiescent M star (Segura et al., 2005). Therefore, N _{2}O becomes a promising biomarker. Under this scenario it is important to constrain the abiotic sources of N _{2}O under different atmospheric conditions to avoid a false positive identification of life. Here we report an experimental study of the effects of lightning discharges on the nitrogen fixation rate during the evolution of the Earth’s early atmosphere from 10 to 1 percent of carbon dioxide in molecular nitrogen. We extended our study from no methane up to 1,000 ppm CH _{4}, which would be applicable to the postbiotic Earth (Tian et al., 2011). Lightning was simulated in the laboratory by a plasma generated with a

  5. SU-G-BRB-03: Assessing the Sensitivity and False Positive Rate of the Integrated Quality Monitor (IQM) Large Area Ion Chamber to MLC Positioning Errors

    Energy Technology Data Exchange (ETDEWEB)

    Boehnke, E McKenzie; DeMarco, J; Steers, J; Fraass, B [Cedars-Sinai Medical Center, Los Angeles, CA (United States)

    2016-06-15

    Purpose: To examine both the IQM’s sensitivity and false positive rate to varying MLC errors. By balancing these two characteristics, an optimal tolerance value can be derived. Methods: An un-modified SBRT Liver IMRT plan containing 7 fields was randomly selected as a representative clinical case. The active MLC positions for all fields were perturbed randomly from a square distribution of varying width (±1mm to ±5mm). These unmodified and modified plans were measured multiple times each by the IQM (a large area ion chamber mounted to a TrueBeam linac head). Measurements were analyzed relative to the initial, unmodified measurement. IQM readings are analyzed as a function of control points. In order to examine sensitivity to errors along a field’s delivery, each measured field was divided into 5 groups of control points, and the maximum error in each group was recorded. Since the plans have known errors, we compared how well the IQM is able to differentiate between unmodified and error plans. ROC curves and logistic regression were used to analyze this, independent of thresholds. Results: A likelihood-ratio Chi-square test showed that the IQM could significantly predict whether a plan had MLC errors, with the exception of the beginning and ending control points. Upon further examination, we determined there was ramp-up occurring at the beginning of delivery. Once the linac AFC was tuned, the subsequent measurements (relative to a new baseline) showed significant (p <0.005) abilities to predict MLC errors. Using the area under the curve, we show the IQM’s ability to detect errors increases with increasing MLC error (Spearman’s Rho=0.8056, p<0.0001). The optimal IQM count thresholds from the ROC curves are ±3%, ±2%, and ±7% for the beginning, middle 3, and end segments, respectively. Conclusion: The IQM has proven to be able to detect not only MLC errors, but also differences in beam tuning (ramp-up). Partially supported by the Susan Scott Foundation.

  6. Gallium and imaging studies

    International Nuclear Information System (INIS)

    Vogel, H.C.

    1982-01-01

    The indications for the use of 67 Gallium imaging studies of the lungs are discussed. In spite of localization of 67 Ga in a large variety of neoplastic and inflammatory tissues, there is only limited application of the lung study in the differential diagnosis of pulmonary diseases. The chest radiograph will continue to be the principal tool for evaluation of pulmonary diseases. The 67 Ga-citrate scan serves as a study complementary to the chest radiograph, as it indicates the localization, extent and degree of activity of lung disease with greater accuracy than radiography. Gallium-67 scanning may be used in the evaluation of patients with lymphoreticular neoplasms, especially Hodgkin-disease and malignant lymphoma both during initial staging and in evaluation of the response to therapy. The 67 Ga-citrate scan is useful in the pre-operative evaluation of patients with lung cancer. Hilar and mediastinal lymphadenopathy are accurately revealed. The lung study is non-invasive and complementary to mediastinoscopy by showing from which glands a biopsy might be taken. Unsuspected extrathoracic secondaries may be shown up, as well as pulmonary metastases from malignancies elsewhere, although the metastases must be at least 1,5 cm in size. The 67 Ga lung scan is valuable in the evaluation of pulmonary infiltrates of suspicious infective etiology, the differentiation between pulmonary infection and pneumonia in selected cases, follow-up of sarcoid patients on corticosteroid therapy, evaluation of inflammatory activity of idiopathic pulmonary fibrosis and the early detection of neo-plastic or inflammatory diseases before the chest radiograph reveals abnormality, e.g. in diffuse carcinomatosis or Pneumocystis carinii-infection. The sensitivity of tumors to radiation or chemotherapy may be shown

  7. Can cadaverous pollution from environmental lead misguide to false positive results in the histochemical determination of gunshot residues? Study on cadaveric skin samples.

    Science.gov (United States)

    Boracchi, Michele; Andreola, Salvatore; Collini, Federica; Gentile, Guendalina; Maciocco, Francesca; Maghin, Francesca; Zoja, Riccardo

    2017-08-01

    Histochemical determination of lead in gunshot residues (GSR) raises the question of possible environmental contamination by heavy metals. Authors assess the specificity of the Sodium Rhodizonate Test in the search of lead derived from environmental pollution. Sodium Rhodizonate Test and 5% HCl Sodium Rhodizonate test were applied to skin samples taken from two groups of victims, whose cause of death was not related to gunshot wounds: group A included 25 corpses found in open spaces after a long time; group B included 16 corpses exhumed after a period of 11 years. The use of these histochemical tests to skin samples from these two groups did not show metal debris histochemically similar to the lead present in GSR. These tests were confirmed to be specific in highlighting the GSR coming from gunshot, without being affected by the potential environmental contamination of the heavy metal pollutants, coming from air or soil. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Image Transmission Studies

    Science.gov (United States)

    Blaine, G. James; Hill, Rexford L.; Rueter, Allen P.; Senol, Evren; Studt, James W.

    1988-06-01

    Radiological PACS image sizes and desired retrieval response times demand high-bandwidth communication networks. Local area network technology at speeds higher that 10 Megabits/second (IEEE 802.3) have not achieved standardization nor production volume. Our current PACS experiments are based on a three-level subnet approach using 10 Mb/s Ethernet channels. An Ethernet channel is shown to support image transfers at an average throughput of 3 Mb/s. Preliminary measurements and simulation results suggest that traffic from as many as two-to-three archives can be supported on the same channel.

  9. Image transmission studies

    International Nuclear Information System (INIS)

    Blaine, G.J.; Hill, R.L.; Rueter, A.P.; Senol, E.; Studt, J.W.

    1988-01-01

    This paper discusses radiological PACS image sizes and desired retrieval response time that demand high-bandwidth communication networks. Local area network technology at speeds higher that 10 Megabits/second (IEEE 802.3) have not achieved standardization nor production volume. The authors describe current PACS experiments based on a three-level subnet approach using 10 Mb/s Ethernet channels. An Ethernet channel is shown to support image transfers at an average throughput of 3 Mb/s. Preliminary measurements and simulation results suggest that traffic from as many as two-to-three archives can be supported on the same channel

  10. Vertebral metastases from neuroendocrine tumours: How to avoid false positives on 68Ga-DOTA-TOC PET using CT pattern analysis?

    Science.gov (United States)

    Gauthé, Mathieu; Testart Dardel, Nathalie; Ruiz Santiago, Fernando; Ohnona, Jessica; Nataf, Valérie; Montravers, Françoise; Talbot, Jean-Noël

    2018-03-12

    To develop criteria to improve discrimination between vertebral metastases from neuroendocrine tumours (NETs) and benign bone lesions on PET combined with CT using DOTA-D-Phe 1 -Tyr 3 -octreotide labelled with gallium-68 ( 68 Ga-DOTA-TOC). In 535 NET patients, 68 Ga-DOTA-TOC PET/CT examinations were reviewed retrospectively for vertebral CT lesions and/or PET foci. For each vertebral PET abnormality, appearance on CT, biological volume (BV), standardized uptake value (SUV max ) and ratios to those of reference organs were determined. All vertebral abnormalities were characterized as a metastasis, a typical vertebral haemangioma (VH) or other benign lesion. In 79 patients (14.8 %), we found 107 metastases, 34 VHs and 31 other benign lesions in the spine. The optimal cut-off values to differentiate metastases from benign lesions were BV ≥0.72 cm 3 , SUVmax ≥2, SUVmax ratio to a reference vertebra ≥2.1, to liver ≥0.28 and to spleen ≥0.14. They corresponded to lesion-based 68 Ga-DOTA-TOC PET/CT sensitivity of 87 %, 98 %, 97 %, 99 % and 94 %, and specificity of 55 %, 100 %, 90 %, 97 %, 100 %, respectively. The high sensitivity of 68 Ga-DOTA-TOC-PET/CT in detecting NET vertebral metastases was confirmed; this study showed that specificity could be improved by combining CT features and quantifying 68 Ga-DOTA-TOC uptake. • Bone metastases in neuroendocrine tumours correlate with prognosis. • Benign bone lesions may mimic metastases on 68 Ga-DOTA-TOC PET/CT imaging. • The specific polka-dot CT pattern may be missing in some vertebral haemangiomas. • Lesion atypical for haemangiomas can be better characterized by quantifying 68 Ga-DOTA-TOC uptake.

  11. False positive {sup 18}F-FDG PET in an ischial chondroblastoma; an analysis of glucose transporter 1 and hexokinase II expression

    Energy Technology Data Exchange (ETDEWEB)

    Hamada, Kenichiro [Osaka University Graduate School of Medicine, Department of Nuclear Medicine and Tracer Kinetics, Osaka (Japan); Osaka University Graduate School of Medicine, Department of Orthopaedics, Osaka (Japan); Ueda, Takafumi; Tamai, Noriyuki; Myoui, Akira; Yoshikawa, Hideki [Osaka University Graduate School of Medicine, Department of Orthopaedics, Osaka (Japan); Tomita, Yasuhiko; Aozasa, Katsuyuki [Osaka University Graduate School of Medicine, Pathology, Osaka (Japan); Higuchi, Ichiro; Hatazawa, Jun [Osaka University Graduate School of Medicine, Department of Nuclear Medicine and Tracer Kinetics, Osaka (Japan); Inoue, Atsuo [Osaka University Graduate School of Medicine, Radiology, Osaka (Japan)

    2006-05-15

    We report a rare case of chondroblastoma arising from the ischium which showed an increased {sup 18}F-FDG uptake. Chondroblastoma is an uncommon lesion and usually involves the epiphysis of long bones. However, in this case, the tumor appeared as a well-defined osteolytic lesion in the ischium on radiographs. MR imaging demonstrated two components in the tumor: a solid one and a multilobular cystic component. {sup 18}F-FDG PET imaging revealed an increased uptake in the ischium. The {sup 18}F-FDG uptake resembled the results observed in malignant bone tumors. A histological diagnosis of chondroblastoma was obtained from tissue of an open biopsy. An immunohistochemical analysis demonstrated weak expression of both Glut-1 and HK-II. These findings suggest that Glut-1 and HK-II expression are not strongly related to FDG uptake in chondroblastoma. (orig.)

  12. The diagnosis of nonclassic congenital adrenal hyperplasia due to 21-hydroxylase deficiency, based on serum basal or post-ACTH stimulation 17-hydroxyprogesterone, can lead to false-positive diagnosis.

    Science.gov (United States)

    Ambroziak, Urszula; Kępczyńska-Nyk, Anna; Kuryłowicz, Alina; Małunowicz, Ewa Maria; Wójcicka, Anna; Miśkiewicz, Piotr; Macech, Magdalena

    2016-01-01

    As nonclassic congenital adrenal hyperplasia (NCCAH) needs to be taken into account in women with hyperandrogenism, we aimed to assess whether the recommended level of poststimulated 17OHP ≥30 nmol/l confirms NCCAH. Forty, consecutive women with biochemical and/or clinical hyperandrogenism (aged 25·4, 18-38) suspected of having NCCAH were recruited to the study. In patients with 17OHP level between 5·1 and 29·9 nmol/l an ACTH stimulation test was performed. In patients with basal or poststimulated 17OHP ≥30 nmol/l, twenty-four-hour urinary steroid profile (USP) analysis was performed and CYP21A2 mutation was assessed. In selected patients with poststimulated 17OHP basal or poststimulated 17OHP ≥30 nmol/l (group A) and with poststimulated 17OHP basal or poststimulated 17OHP ≥30 nmol/l was found in 21, but NCCAH was confirmed by USP followed by genetic testing only in 5 (24%). Four patients were diagnosed as heterozygotes, and in twelve, no CYP21A2 mutation was detected. The diagnosis of NCCAH based only on serum 17OHP measurements (basal or poststimulated) may lead to false-positive diagnosis when performed by immunoassay with a cut-off value of ≥30 nmol/l. The definitive diagnosis can be established based on USP and/or genetic testing. © 2015 John Wiley & Sons Ltd.

  13. Computer-aided detection of brain metastasis on 3D MR imaging: Observer performance study.

    Directory of Open Access Journals (Sweden)

    Leonard Sunwoo

    Full Text Available To assess the effect of computer-aided detection (CAD of brain metastasis (BM on radiologists' diagnostic performance in interpreting three-dimensional brain magnetic resonance (MR imaging using follow-up imaging and consensus as the reference standard.The institutional review board approved this retrospective study. The study cohort consisted of 110 consecutive patients with BM and 30 patients without BM. The training data set included MR images of 80 patients with 450 BM nodules. The test set included MR images of 30 patients with 134 BM nodules and 30 patients without BM. We developed a CAD system for BM detection using template-matching and K-means clustering algorithms for candidate detection and an artificial neural network for false-positive reduction. Four reviewers (two neuroradiologists and two radiology residents interpreted the test set images before and after the use of CAD in a sequential manner. The sensitivity, false positive (FP per case, and reading time were analyzed. A jackknife free-response receiver operating characteristic (JAFROC method was used to determine the improvement in the diagnostic accuracy.The sensitivity of CAD was 87.3% with an FP per case of 302.4. CAD significantly improved the diagnostic performance of the four reviewers with a figure-of-merit (FOM of 0.874 (without CAD vs. 0.898 (with CAD according to JAFROC analysis (p < 0.01. Statistically significant improvement was noted only for less-experienced reviewers (FOM without vs. with CAD, 0.834 vs. 0.877, p < 0.01. The additional time required to review the CAD results was approximately 72 sec (40% of the total review time.CAD as a second reader helps radiologists improve their diagnostic performance in the detection of BM on MR imaging, particularly for less-experienced reviewers.

  14. Computer-aided detection of brain metastasis on 3D MR imaging: Observer performance study.

    Science.gov (United States)

    Sunwoo, Leonard; Kim, Young Jae; Choi, Seung Hong; Kim, Kwang-Gi; Kang, Ji Hee; Kang, Yeonah; Bae, Yun Jung; Yoo, Roh-Eul; Kim, Jihang; Lee, Kyong Joon; Lee, Seung Hyun; Choi, Byung Se; Jung, Cheolkyu; Sohn, Chul-Ho; Kim, Jae Hyoung

    2017-01-01

    To assess the effect of computer-aided detection (CAD) of brain metastasis (BM) on radiologists' diagnostic performance in interpreting three-dimensional brain magnetic resonance (MR) imaging using follow-up imaging and consensus as the reference standard. The institutional review board approved this retrospective study. The study cohort consisted of 110 consecutive patients with BM and 30 patients without BM. The training data set included MR images of 80 patients with 450 BM nodules. The test set included MR images of 30 patients with 134 BM nodules and 30 patients without BM. We developed a CAD system for BM detection using template-matching and K-means clustering algorithms for candidate detection and an artificial neural network for false-positive reduction. Four reviewers (two neuroradiologists and two radiology residents) interpreted the test set images before and after the use of CAD in a sequential manner. The sensitivity, false positive (FP) per case, and reading time were analyzed. A jackknife free-response receiver operating characteristic (JAFROC) method was used to determine the improvement in the diagnostic accuracy. The sensitivity of CAD was 87.3% with an FP per case of 302.4. CAD significantly improved the diagnostic performance of the four reviewers with a figure-of-merit (FOM) of 0.874 (without CAD) vs. 0.898 (with CAD) according to JAFROC analysis (p reviewers (FOM without vs. with CAD, 0.834 vs. 0.877, p review the CAD results was approximately 72 sec (40% of the total review time). CAD as a second reader helps radiologists improve their diagnostic performance in the detection of BM on MR imaging, particularly for less-experienced reviewers.

  15. A cause of false positive of the whole body scanning with iodine 131: obstructive hydronephrosis; Une cause de faux-positif du balayage corps entier a l'iode 131: l'hydronephrose obstructive

    Energy Technology Data Exchange (ETDEWEB)

    Sellem, A.; Elbez, I.; Rejeb, O.; Elkadri, N.; Hammami, H. [Service de medecine nucleaire, hopital Militaire, Tunis, (Tunisia)

    2009-05-15

    The objective is to report the case of a differentiated carcinoma of the thyroid with a false positive aspect to the whole-body scanning with iodine 131 in relation with an accumulation of the tracer at the level of an obstructive appearance hydronephrosis. (N.C.)

  16. MARVELS-1: A FACE-ON DOUBLE-LINED BINARY STAR MASQUERADING AS A RESONANT PLANETARY SYSTEM AND CONSIDERATION OF RARE FALSE POSITIVES IN RADIAL VELOCITY PLANET SEARCHES

    International Nuclear Information System (INIS)

    Wright, Jason T.; Roy, Arpita; Mahadevan, Suvrath; Wang, Sharon X.; Fleming, Scott W.; Ford, Eric B.; Payne, Matt; Lee, Brian L.; Ge, Jian; Wang, Ji; Crepp, Justin R.; Gaudi, B. Scott; Eastman, Jason; Pepper, Joshua; Cargile, Phillip; Stassun, Keivan G.; Ghezzi, Luan; González-Hernández, Jonay I.; Wisniewski, John; Dutra-Ferreira, Leticia

    2013-01-01

    We have analyzed new and previously published radial velocity (RV) observations of MARVELS-1, known to have an ostensibly substellar companion in a ∼6 day orbit. We find significant (∼100 m s –1 ) residuals to the best-fit model for the companion, and these residuals are naïvely consistent with an interior giant planet with a P = 1.965 days in a nearly perfect 3:1 period commensurability (|P b /P c – 3| –4 ). We have performed several tests for the reality of such a companion, including a dynamical analysis, a search for photometric variability, and a hunt for contaminating stellar spectra. We find many reasons to be critical of a planetary interpretation, including the fact that most of the three-body dynamical solutions are unstable. We find no evidence for transits, and no evidence of stellar photometric variability. We have discovered two apparent companions to MARVELS-1 with adaptive optics imaging at Keck; both are M dwarfs, one is likely bound, and the other is likely a foreground object. We explore false-alarm scenarios inspired by various curiosities in the data. Ultimately, a line profile and bisector analysis lead us to conclude that the ∼100 m s –1 residuals are an artifact of spectral contamination from a stellar companion contributing ∼15%-30% of the optical light in the system. We conclude that origin of this contamination is the previously detected RV companion to MARVELS-1, which is not, as previously reported, a brown dwarf, but in fact a G dwarf in a face-on orbit.

  17. Imaging study on acupuncture points

    Science.gov (United States)

    Yan, X. H.; Zhang, X. Y.; Liu, C. L.; Dang, R. S.; Ando, M.; Sugiyama, H.; Chen, H. S.; Ding, G. H.

    2009-09-01

    The topographic structures of acupuncture points were investigated by using the synchrotron radiation based Dark Field Image (DFI) method. Four following acupuncture points were studied: Sanyinjiao, Neiguan, Zusanli and Tianshu. We have found that at acupuncture point regions there exists the accumulation of micro-vessels. The images taken in the surrounding tissue out of the acupuncture points do not show such kind of structure. It is the first time to reveal directly the specific structure of acupuncture points by X-ray imaging.

  18. Imaging study on acupuncture points

    International Nuclear Information System (INIS)

    Yan, X H; Zhang, X Y; Liu, C L; Dang, R S; Ando, M; Sugiyama, H; Chen, H S; Ding, G H

    2009-01-01

    The topographic structures of acupuncture points were investigated by using the synchrotron radiation based Dark Field Image (DFI) method. Four following acupuncture points were studied: Sanyinjiao, Neiguan, Zusanli and Tianshu. We have found that at acupuncture point regions there exists the accumulation of micro-vessels. The images taken in the surrounding tissue out of the acupuncture points do not show such kind of structure. It is the first time to reveal directly the specific structure of acupuncture points by X-ray imaging.

  19. Positron imaging studies

    International Nuclear Information System (INIS)

    Budinger, T.F.; Ganz, E.; Moyer, B.R.; Yano, Y.; Mathis, C.A.; Friedland, R.P.

    1982-01-01

    Several methods for the noninvasive evaluation of the metabolism and blood perfusion of brain and heart are reviewed. Heart muscle perfusion can be followed by measuring the accumulation of rubidium-82 simultaneously with the measurement of the arterial input. Deoxyglucose labelled with fluorine-18 was used to study the role of insulin in deoxyglucose accumulation

  20. The Lifetime Economic Burden of Inaccurate HER2 Testing: Estimating the Costs of False-Positive and False-Negative HER2 Test Results in US Patients with Early-Stage Breast Cancer.

    Science.gov (United States)

    Garrison, Louis P; Babigumira, Joseph B; Masaquel, Anthony; Wang, Bruce C M; Lalla, Deepa; Brammer, Melissa

    2015-06-01

    Patients with breast cancer whose tumors test positive for human epidermal growth factor receptor 2 (HER2) are treated with HER2-targeted therapies such as trastuzumab, but limitations with HER2 testing may lead to false-positive (FP) or false-negative (FN) results. To develop a US-level model to estimate the effect of tumor misclassification on health care costs and patient quality-adjusted life-years (QALYs). Decision analysis was used to estimate the number of patients with early-stage breast cancer (EBC) whose HER2 status was misclassified in 2012. FP results were assumed to generate unnecessary trastuzumab costs and unnecessary cases of trastuzumab-related cardiotoxicity. FN results were assumed to save money on trastuzumab, but with a loss of QALYs and greater risk of disease recurrence and its associated costs. QALYs were valued at $100,000 under a net monetary benefit approach. Among 226,870 women diagnosed with EBC in 2012, 3.12% (n = 7,070) and 2.18% (n = 4,955) were estimated to have had FP and FN test results, respectively. Approximately 8400 QALYs (discounted, lifetime) were lost among women not receiving trastuzumab because of FN results. The estimated incremental per-patient lifetime burden of FP or FN results was $58,900 and $116,000, respectively. The implied incremental losses to society were $417 million and $575 million, respectively. HER2 tests result in misclassification and nonoptimal treatment of approximately 12,025 US patients with EBC annually. The total economic societal loss of nearly $1 billion suggests that improvements in HER2 testing accuracy are needed and that further clinical and economic studies are warranted. Copyright © 2015 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

  1. The Influence of Feedback of Diagnosis and Executive Function Skills on Rates of False Positive and False Negative Outcomes for ADHD

    Science.gov (United States)

    Bender, Stacy L.; Privitera, Gregory J.

    2016-01-01

    This study examined executive function (EF) skills and self-reported symptoms of ADHD. EF skills were measured to determine whether skills were different between groups that reported clinical levels of ADHD symptoms (clinical group) and nonclinical levels of ADHD symptoms (nonclinical group). EF skills in the nonclinical group were also…

  2. O método da falsa posição na história e na educação matemática The false position method in history and in mathematics education

    Directory of Open Access Journals (Sweden)

    Cleide Farias de Medeiros

    2004-12-01

    procedure for solving linear equations. Although one conclusion is that in its simpler form this method does not constitute any substitute for the modern symbolic algebraic resolution of equations and linear systems, it certainly represents a valuable springboard to reach a more formalised study. Particularly, the false position method is a very useful pedagogical tool in mathematics education, mainly when it is interwoven with its initial concrete approaches and its associations with geometry and analytical geometry.

  3. Heat treatment and false-positive heartworm antigen testing in ex vivo parasites and dogs naturally infected by Dirofilaria repens and Angiostrongylus vasorum

    Directory of Open Access Journals (Sweden)

    Luigi Venco

    2017-11-01

    Full Text Available Abstract Background Heartworm antigen testing is considered sensitive and specific. Currently available tests are reported as detecting a glycoprotein found predominantly in the reproductive tract of the female worm and can reach specificity close to 100%. Main concerns regard sensitivity in the case of light infections, the presence of immature females or cases of all-male infections. Research and development have been aimed at increasing sensitivity. Recently, heat treatment of serum prior to antigen testing has been shown to result in an increase in positive antigen test results, presumably due to disruption of natural antigen–antibody complexes. Cross-reactions in dogs with both natural and experimental infections with Angiostrongylus vasorum and Spirocerca lupi have been reported, but cross-reactions with other helminths have not been extensively studied. In order to evaluate potential cross-reactivity with other canine and feline parasites, two studies were performed. Study 1: Live adults of Dirofilaria immitis, Dirofilaria repens, Toxocara canis, Toxocara cati, Dipylidium caninum, Taenia taeniaeformis and Mesocestoides spp. larvae were washed and incubated in tubes with saline solution. All worms were alive at the time of removal from the saline. Saline solutions containing excretory/secretory antigens were then tested for heartworm with six different, commercially available antigen tests. All results were evaluated blind by three of the authors. Study 2: Sera from dogs with natural infections by A. vasorum or D. repens, living in areas free of heartworm disease, were tested with the same tests before and after heat treatment (103 °C for 10 min. Results Results suggest that antigens detected by currently available tests are not specific for D. immitis. They may give positive results through detection of different parasites’ antigens that are normally not released into the bloodstream or released in a low amount and/or bound to

  4. False-positive defects in technetium-99m sestamibi myocardial single-photon emission tomography in healthy athletes with left ventricular hypertrophy

    International Nuclear Information System (INIS)

    Bartram, P.; Hanel, B.; Gustafsson, F.; Mortensen, J.; Hesse, B.; Toft, J.; Ali, S.

    1998-01-01

    Exercise ECG and myocardial single-photon emission tomography (SPET) are fundamental in the non-invasive evaluation of patients suspected of having coronary artery disease (CAD). The purpose of the present study was to investigate the influence of physiological left ventricular hypertrophy (LVH) on myocardial sestamibi SPET in healthy young and old athletes. Eighteen young male elite athletes (ten rowers, five power/weight lifters and three triathletes) and 14 well-trained elderly rowers were studied. All underwent a bicycle test as part of a 2-day sestamibi SPET protocol. Attenuation correction was not performed. The studies were evaluated visually and quantitatively analysed by the CEqual program with its reference files and with a file from a local non-athletic age-matched population. Echocardiographic LVH was an inclusion criterion in the young athletes. Exercise ECG was normal in all subjects. In at least three of the young athletes a reversible defect was observed by visual analysis. On quantitative analysis one-third of the young athletes had ''significant'' (>10 pixels) defects compared with both the local reference base and the CEqual reference population. Nearly all defects were found in the anterior or inferior wall. The remaining subjects, including all old rowers, had normal SPET findings. Anterior and inferior wall defects are so common in healthy athletes with physiological LVH that the specificity of myocardial SPET, in contrast to exercise ECG, seems to be too low for evaluation of chest pain in this group. The mechanism of anterior and inferior defects may be related to hot spots (papillary muscles?) in the lateral wall. The specificity of SPET is maintained in athletes without LVH. (orig.)

  5. Assessment of skin sensitization under REACH: A case report on vehicle choice in the LLNA and its crucial role preventing false positive results.

    Science.gov (United States)

    Watzek, Nico; Berger, Franz; Kolle, Susanne Noreen; Kaufmann, Tanja; Becker, Matthias; van Ravenzwaay, Bennard

    2017-04-01

    In the EU, chemicals with a production or import volume in quantities of one metric ton per year or more have to be tested for skin sensitizing properties under the REACH regulation. The murine Local Lymph Node Assay (LLNA) and its modifications are widely used to fulfil the data requirement, as it is currently considered the first-choice method for in vivo testing to cover this endpoint. This manuscript describes a case study highlighting the importance of understanding the chemistry of the test material during testing for 'skin sensitization' of MCDA (mixture of 2,4- and 2,6-diamino-methylcyclohexane) with particular focus on the vehicle used. While the BrdU-ELISA modification of the LLNA using acetone/olive oil (AOO) as vehicle revealed expectable positive results. However, the concentration control analysis unexpectedly revealed an instability of MCDA in the vehicle AOO. Further studies on the reactivity showed MCDA to rapidly react with AOO under formation of various imine structures, which might have caused the positive LLNA result. The repetition of the LLNA using propylene glycol (PG) as vehicle did not confirm the positive results of the LLNA using AOO. Finally, a classification of MCDA as skin sensitizer according to the Globally Harmonized System (GHS) was not justified. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. A High-Throughput Mass Spectrometry Assay Coupled with Redox Activity Testing Reduces Artifacts and False Positives in Lysine Demethylase Screening.

    Science.gov (United States)

    Wigle, Tim J; Swinger, Kerren K; Campbell, John E; Scholle, Michael D; Sherrill, John; Admirand, Elizabeth A; Boriack-Sjodin, P Ann; Kuntz, Kevin W; Chesworth, Richard; Moyer, Mikel P; Scott, Margaret Porter; Copeland, Robert A

    2015-07-01

    Demethylation of histones by lysine demethylases (KDMs) plays a critical role in controlling gene transcription. Aberrant demethylation may play a causal role in diseases such as cancer. Despite the biological significance of these enzymes, there are limited assay technologies for study of KDMs and few quality chemical probes available to interrogate their biology. In this report, we demonstrate the utility of self-assembled monolayer desorption/ionization (SAMDI) mass spectrometry for the investigation of quantitative KDM enzyme kinetics and for high-throughput screening for KDM inhibitors. SAMDI can be performed in 384-well format and rapidly allows reaction components to be purified prior to injection into a mass spectrometer, without a throughput-limiting liquid chromatography step. We developed sensitive and robust assays for KDM1A (LSD1, AOF2) and KDM4C (JMJD2C, GASC1) and screened 13,824 compounds against each enzyme. Hits were rapidly triaged using a redox assay to identify compounds that interfered with the catalytic oxidation chemistry used by the KDMs for the demethylation reaction. We find that overall this high-throughput mass spectrometry platform coupled with the elimination of redox active compounds leads to a hit rate that is manageable for follow-up work. © 2015 Society for Laboratory Automation and Screening.

  7. A prospective study of computed tomography, ultrasound, and gallium imaging in patients with fever

    International Nuclear Information System (INIS)

    McNeil, B.J.; Sanders, R.; Alderson, P.O.; Hessel, S.J.; Finberg, H.; Siegelman, S.S.; Adams, D.F.; Abrams, H.L.

    1981-01-01

    Computed tomography, ultrasound, and 67 Ga-citrate imaging were analyzed prospectively in patients thought to have a focal source of sepsis. They were divided into three groups: (a) postoperative, fever greater than or equal to 38.3 degrees C; (b) fever greater than or equal to 38.3 degrees C for less than four weeks, unrelated to surgery; and (c) any fever present for more than four weeks. ROC curves showed no significant difference in the ability of the three modalities to differentiate focal from nonfocal sources of sepsis. If any two examinations were used and either study was abnormal, the sensitivity increased from about 60% to nearly 90% while the false-positive rate increased from about 15% to 25%. When focal disease was diagnosed only if two examinations were abnormal, the false-positive ratio dropped to nearly zero but the sensitivity fell to below 40%. The authors concluded tha all three modalities have a similar ability to detect sepsis and that sensitivity can be increased by using any two of them

  8. HAMS: High-Affinity Mass Spectrometry Screening. A High-Throughput Screening Method for Identifying the Tightest-Binding Lead Compounds for Target Proteins with No False Positive Identifications.

    Science.gov (United States)

    Imaduwage, Kasun P; Go, Eden P; Zhu, Zhikai; Desaire, Heather

    2016-11-01

    A major challenge in drug discovery is the identification of high affinity lead compounds that bind a particular target protein; these leads are typically identified by high throughput screens. Mass spectrometry has become a detection method of choice in drug screening assays because the target and the ligand need not be modified. Label-free assays are advantageous because they can be developed more rapidly than assays requiring labels, and they eliminate the risk of the label interfering with the binding event. However, in commonly used MS-based screening methods, detection of false positives is a major challenge. Here, we describe a detection strategy designed to eliminate false positives. In this approach, the protein and the ligands are incubated together, and the non-binders are separated for detection. Hits (protein binders) are not detectable by MS after incubation with the protein, but readily identifiable by MS when the target protein is not present in the incubation media. The assay was demonstrated using three different proteins and hundreds of non-inhibitors; no false positive hits were identified in any experiment. The assay can be tuned to select for ligands of a particular binding affinity by varying the quantity of protein used and the immobilization method. As examples, the method selectively detected inhibitors that have K i values of 0.2 μM, 50 pM, and 700 pM. These findings demonstrate that the approach described here compares favorably with traditional MS-based screening methods. Graphical Abstract ᅟ.

  9. A very low geno2pheno false positive rate is associated with poor viro-immunological response in drug-naïve patients starting a first-line HAART.

    Science.gov (United States)

    Armenia, Daniele; Soulie, Cathia; Di Carlo, Domenico; Fabeni, Lavinia; Gori, Caterina; Forbici, Federica; Svicher, Valentina; Bertoli, Ada; Sarmati, Loredana; Giuliani, Massimo; Latini, Alessandra; Boumis, Evangelo; Zaccarelli, Mauro; Bellagamba, Rita; Andreoni, Massimo; Marcelin, Anne-Geneviève; Calvez, Vincent; Antinori, Andrea; Ceccherini-Silberstein, Francesca; Perno, Carlo-Federico; Santoro, Maria Mercedes

    2014-01-01

    We previously found that a very low geno2pheno false positive rate (FPR ≤ 2%) defines a viral population associated with low CD4 cell count and the highest amount of X4-quasispecies. In this study, we aimed at evaluating whether FPR ≤ 2% might impact on the viro-immunological response in HIV-1 infected patients starting a first-line HAART. The analysis was performed on 305 HIV-1 B subtype infected drug-naïve patients who started their first-line HAART. Baseline FPR (%) values were stratified according to the following ranges: ≤ 2; 2-5; 5-10; 10-20; 20-60; >60. The impact of genotypically-inferred tropism on the time to achieve immunological reconstitution (a CD4 cell count gain from HAART initiation ≥ 150 cells/mm(3)) and on the time to achieve virological success (the first HIV-RNA measurement immunological reconstitution was overall 75.5%, and it was significantly lower for FPR ≤ 2 (54.1%) in comparison to other FPR ranks (78.8%, FPR 2-5; 77.5%, FPR 5-10; 71.7%, FPR 10-20; 81.8%, FPR 20-60; 75.1%, FPR >60; p = 0.008). The overall proportion of patients achieving virological success was 95.5% by 12 months of therapy. Multivariable Cox analyses showed that patients having pre-HAART FPR ≤ 2% had a significant lower relative adjusted hazard [95% C.I.] both to achieve immunological reconstitution (0.37 [0.20-0.71], p = 0.003) and to achieve virological success (0.50 [0.26-0.94], p = 0.031) than those with pre-HAART FPR >60%. Beyond the genotypically-inferred tropism determination, FPR ≤ 2% predicts both a poor immunological reconstitution and a lower virological response in drug-naïve patients who started their first-line therapy. This parameter could be useful to identify patients potentially with less chance of achieving adequate immunological reconstitution and virological undetectability.

  10. A functional magnetic resonance imaging study

    Indian Academy of Sciences (India)

    MADU

    systems and ultra fast imaging techniques, such as echo planar imaging (EPI ) ... is used to understand brain organization, assessing of neurological status, and ..... J C 1998 Functional MRI studies of motor recovery after stroke;. NeuroImage 7 ...

  11. Modeling Kepler Transit Light Curves as False Positives: Rejection of Blend Scenarios for Kepler-9, and Validation of Kepler-9 d, a Super-Earth-Size Planet in a Multiple System

    Science.gov (United States)

    Torres, Guillermo; Fressin, Francois; Batalha, Natalie M.; Borucki, William J.; Brown, Timothy M.; Bryson, Stephen T.; Buchhave, Lars A.; Charbonneau, David; Ciardi, David R.; Dunham, Edward W.; hide

    2011-01-01

    Light curves from the Kepler Mission contain valuable information on the nature of the phenomena producing the transit-like signals. To assist in exploring the possibility that they are due to an astrophysical false positive we describe a procedure (BLENDER) to model the photometry in terms of a blend rather than a planet orbiting a star. A blend may consist of a background or foreground eclipsing binary (or star-planet pair) whose eclipses are attenuated by the light of the candidate and possibly other stars within the photometric aperture. We apply BLENDER to the case of Kepler-9 (KIC 3323887), a target harboring two previously confirmed Saturn-size planets (Kepler-9 b and Kepler-9 c) showing transit timing variations, and an additional shallower signal with a 1.59 day period suggesting the presence of a super-Earth-size planet. Using BLENDER together with constraints from other follow-up observations we are able to rule out all blends for the two deeper signals and provide independent validation of their planetary nature. For the shallower signal, we rule out a large fraction of the false positives that might mimic the transits. The false alarm rate for remaining blends depends in part (and inversely) on the unknown frequency of small-size planets. Based on several realistic estimates of this frequency, we conclude with very high confidence that this small signal is due to a super-Earth-size planet (Kepler-9 d) in a multiple system, rather than a false positive. The radius is determined to be 1.64(exp)(sub-14),R, and current spectroscopic observations are as yet insufficient to establish its mass.

  12. Automatic Detection of Lung and Liver Lesions in 3-D Positron Emission Tomography Images: A Pilot Study

    Science.gov (United States)

    Lartizien, Carole; Marache-Francisco, Simon; Prost, Rémy

    2012-02-01

    Positron emission tomography (PET) using fluorine-18 deoxyglucose (18F-FDG) has become an increasingly recommended tool in clinical whole-body oncology imaging for the detection, diagnosis, and follow-up of many cancers. One way to improve the diagnostic utility of PET oncology imaging is to assist physicians facing difficult cases of residual or low-contrast lesions. This study aimed at evaluating different schemes of computer-aided detection (CADe) systems for the guided detection and localization of small and low-contrast lesions in PET. These systems are based on two supervised classifiers, linear discriminant analysis (LDA) and the nonlinear support vector machine (SVM). The image feature sets that serve as input data consisted of the coefficients of an undecimated wavelet transform. An optimization study was conducted to select the best combination of parameters for both the SVM and the LDA. Different false-positive reduction (FPR) methods were evaluated to reduce the number of false-positive detections per image (FPI). This includes the removal of small detected clusters and the combination of the LDA and SVM detection maps. The different CAD schemes were trained and evaluated based on a simulated whole-body PET image database containing 250 abnormal cases with 1230 lesions and 250 normal cases with no lesion. The detection performance was measured on a separate series of 25 testing images with 131 lesions. The combination of the LDA and SVM score maps was shown to produce very encouraging detection performance for both the lung lesions, with 91% sensitivity and 18 FPIs, and the liver lesions, with 94% sensitivity and 10 FPIs. Comparison with human performance indicated that the different CAD schemes significantly outperformed human detection sensitivities, especially regarding the low-contrast lesions.

  13. False positive reaction due to endogenous biotin activity in glandular epithelium of decidua Reação falso positiva em epitélio glandular da decídua devido a atividade endógena de biotina

    Directory of Open Access Journals (Sweden)

    Liliana Cruz Spano

    2005-06-01

    Full Text Available Biotin-labeled probe was used in an in situ hybridisation assay to localize virus infection in formalin-fixed, paraffin embedded tissues taken from eleven abortion cases. Probes for human cytomegalovirus (HCMV, human Parvovirus B19 (B19 and human adenovirus type 2 (HAd2, were labeled with biotin-11-dUTP by nick-translation reaction. Streptavidin-alkaline-phosphatase (SAP was used to detect biotin, followed by 4-nitroblue tetrazolium/5-bromo-4-chloro-3-indolyl phosphate (NBT/BCIP solution. Positive reaction was observed in nucleus of glandular ephitelium cells of decidua either in positive or in negative control at first and second gestational trimester. The reaction was not inhibited with blocking solution for alkaline phosphatase endogenous activity and it persisted even with probes omission. The use of adequate negative control permitted to reveal the presence of nuclear biotin in glandular epithelium of decidua, responsible for false positivity in detection systems involving streptavidin biotin system (StrepABC. The stained cells resembled to cytophatic effect due to herpesvirus, which could induce further misinterpretation. The results obtained in this study strongly recommend that DNA detection by in situ hybridisation reaction in gestational endometrium should be done without using StrepABC system.Sondas marcadas com biotina foram utilizadas neste trabalho para detecção de infecção viral por hibridização in situ em tecidos fixados com formalina e embebidos em parafina de 11 casos obtidos de abortamento. Sondas para citomegalovírus humano (HCMV, parvovírus B19 humano (B19 e adenovírus humano tipo 2 (HAd2, foram marcadas com biotina-11-dUTP através da reação de nick-translation. Estreptavidina conjugada com fosfatase alcalina (SAP seguida por solução de 4-nitro-azul de tetrazolio/5-bromo-4-cloro-3-indolil fosfato (NBT/BCIP foram utilizadas para detecção da biotina após a reação de hibridização. Reação positiva foi

  14. NMR imaging studies of coal

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Z.R.; Zhang, P.Z.; Ding, G.L.; Li, L.Y.; Ye, C.H. [University of Science and Technology, Beijing (China). Dept. of Chemistry

    1996-06-01

    The permeation transportation and swelling behavior of solvents into coal are investigated by NMR imaging using pyridine-d{sub 5} and acetone-d{sub 6}. Images of coal swollen with deuterated solvents illuminate proton distributions of mobile phases within the coal macromolecular networks. More information about the chemical and physical structure of coal can be obtained using NMR imaging techniques.

  15. Coinfection of hepatitis A virus genotype IA and IIIA complicated with autoimmune hemolytic anemia, prolonged cholestasis, and false-positive immunoglobulin M anti-hepatitis E virus: a case report.

    Science.gov (United States)

    Kim, Hee Sup; Jeong, Sook Hyang; Jang, Je Hyuck; Myung, Hyung Joon; Kim, Jin Wook; Bang, Soo Mee; Song, Sang Hoon; Kim, Haeryoung; Yun, Hae Sun

    2011-12-01

    A 37-year-old male presented with fever and jaundice was diagnosed as hepatitis A complicated with progressive cholestasis and severe autoimmune hemolytic anemia. He was treated with high-dose prednisolone (1.5 mg/kg), and eventually recovered. His initial serum contained genotype IA hepatitis A virus (HAV), which was subsequently replaced by genotype IIIA HAV. Moreover, at the time of development of hemolytic anemia, he became positive for immunoglobulin M (IgM) anti-hepatitis E virus (HEV). We detected HAV antigens in the liver biopsy specimen, while we detected neither HEV antigen in the liver nor HEV RNA in his serum. This is the first report of hepatitis A coinfected with two different genotypes manifesting with autoimmune hemolytic anemia, prolonged cholestasis, and false-positive IgM anti-HEV.

  16. Diffusion-weighted and T2-weighted MR imaging for colorectal liver metastases detection in a rat model at 7 T: a comparative study using histological examination as reference

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, Mathilde; Ronot, Maxime; Vilgrain, Valerie; Beers, Bernard E. van [University Paris Diderot, Sorbonne Paris Cite, INSERM UMR 773, University Hospitals Paris Nord Val de Seine, Beaujon, Assistance Publique- Hopitaux de Paris, Laboratory of Physiological and Molecular Imaging of the Abdomen (IPMA) and Department of Radiology, Clichy Cedex (France); Maggiori, Leon; Panis, Yves [University Paris Diderot, Sorbonne Paris Cite, INSERM UMR 773, University Hospitals Paris Nord Val de Seine, Beaujon, Assistance Publique-Hopitaux de Paris, Department of Colorectal Surgery, Clichy (France); Paradis, Valerie [University Paris Diderot, Sorbonne Paris Cite, INSERM UMR 773, University Hospitals Paris Nord Val de Seine, Beaujon, Assistance Publique-Hopitaux de Paris, Department of Pathology, Clichy (France)

    2013-08-15

    To compare diffusion-weighted (DW) and T2-weighted MR imaging in detecting colorectal liver metastases in a rat model, using histological examination as a reference method. Eighteen rats had four liver injections of colon cancer cells. MR examinations at 7 T included FSE-T2-weighted imaging and SE-DW MR imaging (b = 0, 20 and 150 s/mm{sup 2}) and were analysed by two independent readers. Histological examination was performed on 0.4-mm slices. McNemar's test was used to compare the sensitivities and the Wilcoxon matched pairs test to compare the average number of false-positives per rat. One hundred and sixty-six liver metastases were identified on histological examination. The sensitivity in detecting liver metastases was significantly higher on DW MR than on T2-weighted images (99/166 (60 %) (reader 1) and 92/166 (55 %) (reader 2) versus 77/166 (46 %), P {<=} 0.001), without an increase in false-positives per rat (P = 0.773/P = 0.850). After stratification according to metastasis diameter, DW MR imaging had a significantly higher sensitivity than T2-weighted imaging only for metastases with a diameter (0.6-1.2 mm) similar to that of the spatial resolution of MR imaging in the current study. This MR study with histological correlations shows the higher sensitivity of DW relative to T2-weighted imaging at 7 T for detecting liver metastases, especially small ones. (orig.)

  17. PRELIMINARY STUDY FOR THE IMPLEMENTATION OFAN IMAGE ANALYSIS ALGORITHM TO DETECT DAIRY COW PRESENCE AT THE FEED BARRIER

    Directory of Open Access Journals (Sweden)

    Simona M.C. Porto

    2012-06-01

    Full Text Available The objective of this study was to investigate the applicability of the Viola-Jones algorithm for continuous detection of the feeding behaviour of dairy cows housed in an open free-stall barn. A methodology was proposed in order to train, test and validate the classifier. A lower number of positive and negative images than those used by Viola and Jones were required during the training. The testing produced the following results: hit rate of about 97.85%, missed rate of about 2.15%, and false positive rate of about 0.67%. The validation was carried out by an accuracy assessment procedure which required the time-consuming work of an operator who labelled the true position of the cows within the barn and their behaviours. The accuracy assessment revealed that among the 715 frames about 90.63% contained only true positives, whereas about 9.37% were affected by underestimation, i.e., contained also one or two false negatives. False positives occurred only in 2.93% of the analyzed frames. Though a moderate mismatch between the testing and the validation performances was registered, the results obtained revealed the adequacy of the Viola-Jones algorithm for detecting the feeding behaviour of dairy cows housed in open free-stall barns. This, in turn, opens up opportunities for an automatic analysis of cow behaviour.

  18. Image registration in gastric emptying studies

    International Nuclear Information System (INIS)

    Shuter, B.; Cooper, R.G.

    1998-01-01

    Full text: We have previously shown that image registration, based upon a two-dimensional cross-correlation (CC) of logarithmic Laplacian images (LLI), corrected motion in biliary studies in up to 90% of cases with minimal artifact. We have now applied the same technique to gastric emptying studies (GES). GES were acquired on an LFOV gamma camera over a two-hour period as 20-26 pairs of anterior-posterior frames (30 second duration and 64 x 64 matrix) for both solid and liquid components. All images were manually registered so that the solid contents of the stomach lay within an operator-drawn ROI. The anterior images of the solid component for 30 randomly selected patients were subjected to further image registration using CC of LLI, CC of raw images (Rl) (a common approach to image registration) and CC of Laplacian images (Ll). All images were aligned to the third image of the study, on which an ROI was drawn to outline the stomach. The number of images in which stomach counts appeared outside this ROI were tallied, in the original and all re-registered studies. Maximum displacements in X/Y position between images of studies registered by the LLI and Rl methods were also computed to directly compare positional accuracy. Stomachs partially exceeded the limits of the ROI in 27, 9, 53 and 54 frames (total of 710) in the original, LLI, Rl and Ll studies respectively. There were 4, 1, 6 and 7 studies with misregistered stomachs on more than 2 frames. Frames in seven Rl studies differed from the LLI studies in ) X/Y position by 3 pixels or more. Cross-correlation using LLI was the only method which improved upon the original manual registration. The Rl and Ll methods increased the number of misregistered frames. We conclude that in gastric emptying studies, as in biliary studies, object tracking by CC of LLI is the method of choice for image registration

  19. Fijación de radioyodo en huesos maxilares simulando metástasis en pacientes con Carcinoma Diferenciado de Tiroides (CDT): False- Positive images in patients with Differentiated Thyroid Carcinoma. (DTC)

    OpenAIRE

    Degrossi, O. J.; Gutiérrez, S.; Fadel, A.; Degrossi, E. B.; Valdivieso, M. C.; Balbuena, R. L.; Alak, M. del C.; de Cabrejas, M.

    2008-01-01

    En estudios centellográficos con 131I (CCT) para seguimiento, postablación o tratamiento de pacientes portadores de carcinoma diferenciado de tiroides (CDT) se observan frecuentemente en tiempos precoces áreas de captación del radiotrazador en macizo facial. Estas áreas corresponden, generalmente, a glándulas salivares y extremo anterior de mucosa nasal y se mantienen durante las primeras 48 horas y no son observadas generalmente a las 72 horas. Pero con menor frecuencia se presentan otras qu...

  20. Microwave Imaging of Human Forearms: Pilot Study and Image Enhancement

    Directory of Open Access Journals (Sweden)

    Colin Gilmore

    2013-01-01

    Full Text Available We present a pilot study using a microwave tomography system in which we image the forearms of 5 adult male and female volunteers between the ages of 30 and 48. Microwave scattering data were collected at 0.8 to 1.2 GHz with 24 transmitting and receiving antennas located in a matching fluid of deionized water and table salt. Inversion of the microwave data was performed with a balanced version of the multiplicative-regularized contrast source inversion algorithm formulated using the finite-element method (FEM-CSI. T1-weighted MRI images of each volunteer’s forearm were also collected in the same plane as the microwave scattering experiment. Initial “blind” imaging results from the utilized inversion algorithm show that the image quality is dependent on the thickness of the arm’s peripheral adipose tissue layer; thicker layers of adipose tissue lead to poorer overall image quality. Due to the exible nature of the FEM-CSI algorithm used, prior information can be readily incorporated into the microwave imaging inversion process. We show that by introducing prior information into the FEM-CSI algorithm the internal anatomical features of all the arms are resolved, significantly improving the images. The prior information was estimated manually from the blind inversions using an ad hoc procedure.

  1. Mapping of the image quality in myocardial scintigraphy: A national study; Kartlaeggning av bildkvalitet vid myokardscintigrafi: en nationell studie

    Energy Technology Data Exchange (ETDEWEB)

    Ohlson, Maria; Gustafsson, Agnetha (Radiofysikavd., Universitetssjukhuset, Linkoeping (SE)); Gretarsdottir, Jakobina (Diagnostik, Sahlgrenska Universitetssjukhuset, Goeteborg (SE)); Olsson, Eva (Fysiologiska kliniken, Universitetssjukhuset, Linkoeping (SE)); Johansson, Lena (Klinisk Fysiologi, Sahlgrenska Universitetssjukhuset, Goeteborg (SE))

    2008-04-15

    The aim of this study was to make a survey over the physical parameters and how they affect the image quality and the final diagnosis for myocardial perfusion SPECT in Sweden. Another aim was to evaluate the need for standardized acquisition and processing protocols for myocardial perfusion SPECT. All thirty nuclear medicine departments in Sweden that perform myocardial perfusion SPECT participated in the study. A thorax heart phantom was used to simulate two patients. All studies were acquired and processed with the parameters used clinically in each hospital respectively. A quantitative and a qualitative evaluation were performed. At each hospital, the local nuclear medicine physician interpreted the images as if they were true patient images. There are great differences in the acquiring and processing parameters used in myocardial perfusion SPECT studies in Sweden. The image quality varies greatly for the different hospital but was approved for the majority of the hospitals. Images from two hospitals were considered to be too poor to be diagnosed. The interpretations of the local nuclear medicine physicians differ but the majority has reported an adequate diagnosis. One third of the hospitals have reported false positive defects. All steps in the chain from the acquisition to the evaluation of the medicine physician must be performed with high quality. The determinative factors are the noise reduction filter, the orientation of the slices in the heart and the judgement of the local medicine physician. The acquiring and processing parameters proposed by EANM should be used. The hospitals are also recommended to investigate in the time and resources available, in order to educate all staff involved in the evaluation of myocardial studies

  2. Mapping of the image quality in myocardial scintigraphy: A national study

    International Nuclear Information System (INIS)

    Ohlson, Maria; Gustafsson, Agnetha; Gretarsdottir, Jakobina; Olsson, Eva; Johansson, Lena

    2008-04-01

    The aim of this study was to make a survey over the physical parameters and how they affect the image quality and the final diagnosis for myocardial perfusion SPECT in Sweden. Another aim was to evaluate the need for standardized acquisition and processing protocols for myocardial perfusion SPECT. All thirty nuclear medicine departments in Sweden that perform myocardial perfusion SPECT participated in the study. A thorax heart phantom was used to simulate two patients. All studies were acquired and processed with the parameters used clinically in each hospital respectively. A quantitative and a qualitative evaluation were performed. At each hospital, the local nuclear medicine physician interpreted the images as if they were true patient images. There are great differences in the acquiring and processing parameters used in myocardial perfusion SPECT studies in Sweden. The image quality varies greatly for the different hospital but was approved for the majority of the hospitals. Images from two hospitals were considered to be too poor to be diagnosed. The interpretations of the local nuclear medicine physicians differ but the majority has reported an adequate diagnosis. One third of the hospitals have reported false positive defects. All steps in the chain from the acquisition to the evaluation of the medicine physician must be performed with high quality. The determinative factors are the noise reduction filter, the orientation of the slices in the heart and the judgement of the local medicine physician. The acquiring and processing parameters proposed by EANM should be used. The hospitals are also recommended to investigate in the time and resources available, in order to educate all staff involved in the evaluation of myocardial studies

  3. Cone-beam volume CT breast imaging: Feasibility study

    International Nuclear Information System (INIS)

    Chen Biao; Ning Ruola

    2002-01-01

    X-ray projection mammography, using a film/screen combination, or digital techniques, has proven to be the most effective imaging modality currently available for early detection of breast cancer. However, the inherent superimposition of structures makes a small carcinoma (a few millimeters in size) difficult to detect when it is occult or in dense breasts, leading to a high false-positive biopsy rate. Cone-beam x-ray-projection-based volume imaging using flat panel detectors (FPDs) may allow obtaining three-dimensional breast images, resulting in more accurate diagnosis of structures and patterns of lesions while eliminating the hard compression of breasts. This article presents a novel cone-beam volume computed tomographic breast imaging (CBVCTBI) technique based on the above techniques. Through a variety of computer simulations, the key issues of the system and imaging techniques were addressed, including the x-ray imaging geometry and corresponding reconstruction algorithms, x-ray characteristics of breast tissue and lesions, x-ray setting techniques, the absorbed dose estimation, and the quantitative effect of x-ray scattering on image quality. The preliminary simulation results support the proposed CVBCTBI modality for breast imaging in respect to its feasibility and practicability. The absorbed dose level is comparable to that of current mammography and will not be a prominent problem for this imaging technique. Compared to conventional mammography, the proposed imaging technique with isotropic spatial resolution will potentially provide significantly better low-contrast detectability of breast tumors and more accurate location of breast lesions

  4. Cone-beam volume CT mammographic imaging: feasibility study

    Science.gov (United States)

    Chen, Biao; Ning, Ruola

    2001-06-01

    X-ray projection mammography, using a film/screen combination or digital techniques, has proven to be the most effective imaging modality for early detection of breast cancer currently available. However, the inherent superimposition of structures makes small carcinoma (a few millimeters in size) difficult to detect in the occultation case or in dense breasts, resulting in a high false positive biopsy rate. The cone-beam x-ray projection based volume imaging using flat panel detectors (FPDs) makes it possible to obtain three-dimensional breast images. This may benefit diagnosis of the structure and pattern of the lesion while eliminating hard compression of the breast. This paper presents a novel cone-beam volume CT mammographic imaging protocol based on the above techniques. Through computer simulation, the key issues of the system and imaging techniques, including the x-ray imaging geometry and corresponding reconstruction algorithms, x-ray characteristics of breast tissues, x-ray setting techniques, the absorbed dose estimation and the quantitative effect of x-ray scattering on image quality, are addressed. The preliminary simulation results support the proposed cone-beam volume CT mammographic imaging modality in respect to feasibility and practicability for mammography. The absorbed dose level is comparable to that of current two-view mammography and would not be a prominent problem for this imaging protocol. Compared to traditional mammography, the proposed imaging protocol with isotropic spatial resolution will potentially provide significantly better low contrast detectability of breast tumors and more accurate location of breast lesions.

  5. Imaging studies of crystalline arthritides

    Directory of Open Access Journals (Sweden)

    G. Garlaschi

    2012-01-01

    Full Text Available Gout, calcium pyrophosphate dihydrate (CPPD deposition disease, and calcium hydroxyapatite deposition disease (HADD are the three most common crystal-induced arthropathies. Multimodality imaging may help in their diagnosis, and is useful for a precise and comprehensive assessment and grading of the related osteoarticular damage. Plain film radiography, due to its low cost and wide availability, is the first imaging technique to be used in crystal deposition diseases, providing well-known and specific findings for CPPD deposition disease and HADD, while it may undergrade the early osteoarticular lesions in gouty patients. Ultrasonography (US is a radiation-free approach that accurately depicts crystal deposits in cartilage, peri- and intra-articular soft tissues, but it does not give a panoramic view of the affected joints. Cross-sectional imaging techniques can examine crystal deposits in the spine and axial joints. CT has the potential to distinguish monosodium urate (MSU crystals from calcium containing crystals, due to their different attenuation values. MRI may demonstrate synovitis, erosions and bone marrow edema in gouty patients and it may differentiate tophi from other soft tissue nodules due to its high contrast resolution and power of tissue characterization.

  6. Increased accuracy of single photon emission computed tomography (SPECT myocardial perfusion scintigraphy using iterative reconstruction of images

    Directory of Open Access Journals (Sweden)

    Stević Miloš

    2016-01-01

    Full Text Available Background/Aim. Filtered back projection (FBP is a common way of processing myocardial perfusion imaging (MPI studies. There are artifacts in FBP which can cause falsepositive results. Iterative reconstruction (IR is developed to reduce false positive findings in MPI studies. The aim of this study was to evaluate the difference in the number of false positive findings in MPI studies, between FBP and IR processing. Methods. We examined 107 patients with angina pectoris with MPI and coronary angiography (CAG, 77 man and 30 woman, aged 32−82. MPI studies were processed with FBP and with IR. Positive finding at MPI was visualization of the perfusion defect. Positive finding at CAG was stenosis of coronary artery. Perfusion defect at MPI without coronary artery stenosis at CAG was considered like false positive. The results were statistically analyzed with bivariate correlation, and with one sample t-test. Results. There were 20.6% normal, and 79.4% pathologic findings at FBP, 30.8% normal and 69.2% pathologic with IR and 37.4% normal and 62.6% pathologic at CAG. FBP produced 19 false-positive findings, at IR 11 false positive findings. The correlation between FBP and CAG was 0.658 (p < 0.01 and between IR and CAG 0.784 (p < 0.01. The number of false positive findings at MPI with IR was significantly lower than at FBP (p < 0.01. Conclusion. Our study shows that IR processing MPI scintigraphy has less number of false positive findings, therefore it is our choice for processing MPI studies.

  7. CAD in breast imaging. Application in mammography and MR mammography

    International Nuclear Information System (INIS)

    Obenauer, S.; Hermann, K.P.

    2012-01-01

    Computer aided diagnosis systems (CAD-systems) are evaluated in different parts of diagnostic imaging. In breast imaging double reading which is time- and cost spending is necessary. Therefore a lot of studies evaluated the use of CAD-systems in mammography. However the rate of false-positives is too high to implement CAD-systems as double reader in routine work. In the future, improvements in this technique could perhaps change the performance of CAD-systems. (orig.)

  8. Automated image registration for FDOPA PET studies

    International Nuclear Information System (INIS)

    Kang-Ping Lin; Sung-Cheng Huang, Dan-Chu Yu; Melega, W.; Barrio, J.R.; Phelps, M.E.

    1996-01-01

    In this study, various image registration methods are investigated for their suitability for registration of L-6-[18F]-fluoro-DOPA (FDOPA) PET images. Five different optimization criteria including sum of absolute difference (SAD), mean square difference (MSD), cross-correlation coefficient (CC), standard deviation of pixel ratio (SDPR), and stochastic sign change (SSC) were implemented and Powell's algorithm was used to optimize the criteria. The optimization criteria were calculated either unidirectionally (i.e. only evaluating the criteria for comparing the resliced image 1 with the original image 2) or bidirectionally (i.e. averaging the criteria for comparing the resliced image 1 with the original image 2 and those for the sliced image 2 with the original image 1). Monkey FDOPA images taken at various known orientations were used to evaluate the accuracy of different methods. A set of human FDOPA dynamic images was used to investigate the ability of the methods for correcting subject movement. It was found that a large improvement in performance resulted when bidirectional rather than unidirectional criteria were used. Overall, the SAD, MSD and SDPR methods were found to be comparable in performance and were suitable for registering FDOPA images. The MSD method gave more adequate results for frame-to-frame image registration for correcting subject movement during a dynamic FDOPA study. The utility of the registration method is further demonstrated by registering FDOPA images in monkeys before and after amphetamine injection to reveal more clearly the changes in spatial distribution of FDOPA due to the drug intervention. (author)

  9. Reflex sympathetic dystrophy syndrome: MR imaging study

    International Nuclear Information System (INIS)

    Masciocchi, C.; Fascetti, E.; Bonanni, G.; Calvisi, V.; Buoni, C.; Passariello, R.

    1987-01-01

    Reflex sympathetic dystrophy syndrome (RSDS) is characterized by pain, swelling, and limitation of motion. The etiology and pathophysiology mechanism have not yet been identified. We considered eight patients with clinical signs of RSDS, in five cases located at the knee joint and in three cases in the hip. In all cases conventional radiography and radionuclide bone scanning were performed before MR imaging. Conventional radiography was negative in three cases while scintigraphy demonstrated the lesion in all patients. MR imaging showed an area of low intensity signal on T1-weighted scans and an increased signal intensity on T2-weighted images. This area is located at the bone marrow and its regular and homogeneous. This specific finding on MR images is due to reflect edema by hyperemia of the bone marrow. The MR imaging diagnosis was confirmed on clinical and radiological follow-up. MR imaging can have a role in the differential diagnosis when other studies are nondiagnostic or nonspecific for RSDS

  10. Neuromyelitis optica: a diffusional kurtosis imaging study.

    Science.gov (United States)

    Doring, T M; Lopes, F C R; Kubo, T T A; Tukamoto, G; Kimura, M C; Strecker, R M; Domingues, R C; Gasparetto, E L

    2014-12-01

    Conventional MR imaging typically yields normal images of the brain or indicates lesions in areas of high aquaporin expression in patients with neuromyelitis optica. Diffusional kurtosis imaging was applied in patients with neuromyelitis optica to determine whether this technique could detect alterations in diffusion and diffusional kurtosis parameters in normal-appearing white matter and to explore the relationship between diffusional kurtosis imaging and DTI parameters. Thirteen patients with neuromyelitis optica and 13 healthy controls underwent MR imaging of the brain with conventional and diffusional kurtosis imaging sequences. Tract-based spatial statistics and region-of-interest-based analyses were conducted to identify differences between patients with neuromyelitis optica and controls through conventional DTI and diffusional kurtosis imaging parameters. The parameters were correlated to determine the potential relationship between them. Compared with healthy controls, several diffusional kurtosis imaging and DTI parameters were altered in various fiber tracts of patients with neuromyelitis optica (P optica. We found a negative correlation between diffusional kurtosis imaging (radial kurtosis, axial kurtosis, mean kurtosis) and the corresponding DTI parameters (radial diffusivity, axial diffusivity, mean diffusivity). Positive correlations were found for radial kurtosis and mean kurtosis with fractional anisotropy. This study demonstrated differences in conventional diffusion and diffusional kurtosis parameters, especially radial kurtosis, in the normal-appearing white matter of patients with neuromyelitis optica compared with healthy controls. Larger studies of patients with neuromyelitis optica should be performed to assess the potential clinical impact of these findings. © 2014 by American Journal of Neuroradiology.

  11. Somatostatin receptor scintigraphy and magnetic resonance imaging in recurrent medullary thyroid carcinoma: A comparative study

    International Nuclear Information System (INIS)

    Doerr, U.; Wuerstlin, S.; Frank-Raue, K.; Raue, F.; Hehrmann, R.; Iser, G.; Scholz, M.; Guhl, L.; Buhr, H.J.; Bihl, H.

    1993-01-01

    In a prospective study, 18 patients with recurrent medullary thyroid carcinoma (MTC) underwent magnetic resonance imaging (MRI) of the neck and mediastinum and somatostatin receptor scintigraphy (SRS) with 111 In-labeled pentetreotide. In nine patients with macroscopic MTC, 17 corresponding lesions were found on MRI and SRS; in addition, 13 suspicious lesions were seen on SRS only. Histological confirmation was available for 19 metastatic lesions, showing MRI to be true positive in 13 metastases, SRS in 18. In minimal residual disease (n=10), MRI and SRS were compared with the histological findings in three patients and with selective venous catheterization (SVC) in seven patients. Corresponding findings on MRI and SVC were seen in one of seven, whereas SRS and SVC showed concordant localization of tumor recurrence in five of seven. Histological examination demonstrated MTC tissue in one of three cases; MRI and SRS were false positive in one of three cases, while in the others the interpretation remained uncertain. In conclusion, SRS is a promising imaging modality for localization of MTC recurrence. MRI provides better spatial resolution and thus facilitates the planning of surgery for macroscopic metastases. In minimal residual disease, SRS turned out to be superior in detecting occult MTC recurrence, confirming SVC findings. (orig.)

  12. Image processing of angiograms: A pilot study

    Science.gov (United States)

    Larsen, L. E.; Evans, R. A.; Roehm, J. O., Jr.

    1974-01-01

    The technology transfer application this report describes is the result of a pilot study of image-processing methods applied to the image enhancement, coding, and analysis of arteriograms. Angiography is a subspecialty of radiology that employs the introduction of media with high X-ray absorption into arteries in order to study vessel pathology as well as to infer disease of the organs supplied by the vessel in question.

  13. Study on Processing Method of Image Shadow

    Directory of Open Access Journals (Sweden)

    Wang Bo

    2014-07-01

    Full Text Available In order to effectively remove disturbance of shadow and enhance robustness of information processing of computer visual image, this paper makes study on inspection and removal of image shadow. It makes study the continual removal algorithm of shadow based on integration, the illumination surface and texture, it respectively introduces their work principles and realization method, it can effectively carrying processing for shadow by test.

  14. Display of nuclear medicine imaging studies

    International Nuclear Information System (INIS)

    Singh, B.; Kataria, S.K.; Samuel, A.M.

    2002-08-01

    Nuclear medicine imaging studies involve evaluation of a large amount of image data. Digital signal processing techniques have introduced processing algorithms that increase the information content of the display. Nuclear medicine imaging studies require interactive selection of suitable form of display and pre-display processing. Static imaging study requires pre-display processing to detect focal defects. Point operations (histogram modification) along with zoom and capability to display more than one image in one screen is essential. This album mode of display is also applicable to dynamic, MUGA and SPECT data. Isometric display or 3-D graph of the image data is helpful in some cases e.g. point spread function, flood field data. Cine display is used on a sequence of images e.g. dynamic, MUGA and SPECT imaging studies -to assess the spatial movement of tracer with time. Following methods are used at the investigator's discretion for inspection of the 3-D object. 1) Display of orthogonal projections, 2) Display of album of user selected coronal/ sagital/ transverse orthogonal slices, 3) Display of three orthogonal slices through user selected point, 4) Display of a set of orthogonal slices generated in the user-selected volume, 5) Generation and display of 3-D shaded surface. 6) Generation of volume data and display along with the 3-D shaded surface, 7) Side by side display orthogonal slices of two 3-D objects. Displaying a set of two-dimensional slices of a 3-D reconstructed object through shows all the defects but lacks the 3-D perspective. Display of shaded surface lacks the ability to show the embedded defects. Volume display -combining the 3-D surface and gray level volume data is perhaps the best form of display. This report describes these forms of display along with the theory. (author)

  15. Quantifying the impact of respiratory-gated 4D CT acquisition on thoracic image quality: A digital phantom study

    International Nuclear Information System (INIS)

    Bernatowicz, K.; Knopf, A.; Lomax, A.; Keall, P.; Kipritidis, J.; Mishra, P.

    2015-01-01

    Purpose: Prospective respiratory-gated 4D CT has been shown to reduce tumor image artifacts by up to 50% compared to conventional 4D CT. However, to date no studies have quantified the impact of gated 4D CT on normal lung tissue imaging, which is important in performing dose calculations based on accurate estimates of lung volume and structure. To determine the impact of gated 4D CT on thoracic image quality, the authors developed a novel simulation framework incorporating a realistic deformable digital phantom driven by patient tumor motion patterns. Based on this framework, the authors test the hypothesis that respiratory-gated 4D CT can significantly reduce lung imaging artifacts. Methods: Our simulation framework synchronizes the 4D extended cardiac torso (XCAT) phantom with tumor motion data in a quasi real-time fashion, allowing simulation of three 4D CT acquisition modes featuring different levels of respiratory feedback: (i) “conventional” 4D CT that uses a constant imaging and couch-shift frequency, (ii) “beam paused” 4D CT that interrupts imaging to avoid oversampling at a given couch position and respiratory phase, and (iii) “respiratory-gated” 4D CT that triggers acquisition only when the respiratory motion fulfills phase-specific displacement gating windows based on prescan breathing data. Our framework generates a set of ground truth comparators, representing the average XCAT anatomy during beam-on for each of ten respiratory phase bins. Based on this framework, the authors simulated conventional, beam-paused, and respiratory-gated 4D CT images using tumor motion patterns from seven lung cancer patients across 13 treatment fractions, with a simulated 5.5 cm 3 spherical lesion. Normal lung tissue image quality was quantified by comparing simulated and ground truth images in terms of overall mean square error (MSE) intensity difference, threshold-based lung volume error, and fractional false positive/false negative rates. Results: Averaged

  16. Quantifying the impact of respiratory-gated 4D CT acquisition on thoracic image quality: A digital phantom study

    Energy Technology Data Exchange (ETDEWEB)

    Bernatowicz, K., E-mail: kingab@student.ethz.ch; Knopf, A.; Lomax, A. [Center for Proton Therapy, Paul Scherrer Institute, Villigen PSI 5232, Switzerland and Department of Physics, ETH Zürich, Zürich 8092 (Switzerland); Keall, P.; Kipritidis, J., E-mail: john.kipritidis@sydney.edu.au [Radiation Physics Laboratory, Sydney Medical School, University of Sydney, Sydney, NSW 2006 (Australia); Mishra, P. [Brigham and Womens Hospital, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts 02115 (United States)

    2015-01-15

    Purpose: Prospective respiratory-gated 4D CT has been shown to reduce tumor image artifacts by up to 50% compared to conventional 4D CT. However, to date no studies have quantified the impact of gated 4D CT on normal lung tissue imaging, which is important in performing dose calculations based on accurate estimates of lung volume and structure. To determine the impact of gated 4D CT on thoracic image quality, the authors developed a novel simulation framework incorporating a realistic deformable digital phantom driven by patient tumor motion patterns. Based on this framework, the authors test the hypothesis that respiratory-gated 4D CT can significantly reduce lung imaging artifacts. Methods: Our simulation framework synchronizes the 4D extended cardiac torso (XCAT) phantom with tumor motion data in a quasi real-time fashion, allowing simulation of three 4D CT acquisition modes featuring different levels of respiratory feedback: (i) “conventional” 4D CT that uses a constant imaging and couch-shift frequency, (ii) “beam paused” 4D CT that interrupts imaging to avoid oversampling at a given couch position and respiratory phase, and (iii) “respiratory-gated” 4D CT that triggers acquisition only when the respiratory motion fulfills phase-specific displacement gating windows based on prescan breathing data. Our framework generates a set of ground truth comparators, representing the average XCAT anatomy during beam-on for each of ten respiratory phase bins. Based on this framework, the authors simulated conventional, beam-paused, and respiratory-gated 4D CT images using tumor motion patterns from seven lung cancer patients across 13 treatment fractions, with a simulated 5.5 cm{sup 3} spherical lesion. Normal lung tissue image quality was quantified by comparing simulated and ground truth images in terms of overall mean square error (MSE) intensity difference, threshold-based lung volume error, and fractional false positive/false negative rates. Results

  17. Localization diagnosis of hyperfunctional parathyroid gland using 99Tcm-MIBI and 99TcmO4- imaging

    International Nuclear Information System (INIS)

    Zhang Fenru; Deng Huixing; Duan Xiaoyi; Xue Jianjun; Gao Rui

    2010-01-01

    Objective: To study the localization diagnosis value of nuclide imaging by 99 Tc m -MIBI double phase parathyroid combined with 99 Tc m O 4 - thyroid imaging in patients with hyperparathyroidism (HPT). Methods: Patients with primary HPT were 36 cases. Control groups were 10 cases with thyroid disease. Early phase imaging was performed in 15 minute after injecting imaging agent 99 Tc m -MIBI. Delay phase imaging was performed in 2 hours. 36 HPT patients and 10 cases control groups were also performed 99 Tc m O 4 - thyroid imaging 24 hours later. The two kinds of imaging were compared with each other, were analyzed, and were underwent imaging subtracted by eyes and imaging results judgment. Results: In 36 cases of HPT patients, 34 cases showed positive result imaging with 99 Tc m -MIBI/ 99 Tc m O 4 - imaging. 2 cases showed false negative result. Positive rate was 94.44 % with 99 Tc m -MIBI/ 99 Tc m O 4 - imaging. The positive result imaging showed abnormal increased uptake of 99 Tc m -MIBI. In 36 cases of HPT patients, 12 cases showed positive result with single 99 Tc m -MIBI imaging. 4 cases showed false negative imaging. 20 cases showed ambiguous positive results. Positive rate was 88.89% (55.56% was ambiguous positive results) with single 99 Tc m -MIBI imaging. In 10 cases control groups, 3 cases showed false positive results with single 99 Tc m -MIBI imaging. 1 case showed ambiguous false positive results. No case showed false positive result with 99 Tc m -MIBI/ 99 Tc m O 4 - imaging. Conclusion: 99 Tc m -MIBI parathyroid double phase imaging combined with 99 Tc m O 4 - thyroid imaging have important value for diagnoses and localization of hyperparathyroidism. 99 Tc m -MIBI/ 99 Tc m O 4 - imaging have higher positive rate and higher specificity than single 99 Tc m -MIBI imaging for diagnoses and localization of hyperfunction parathyroid gland. (authors)

  18. An accurate test for acute appendicitis: In-111 WBC imaging

    International Nuclear Information System (INIS)

    Navarro, D.A.; Weber, P.M.; Kang, I.Y.; dosRemedios, L.V.; Jasko, I.A.

    1985-01-01

    The decision to operate when acute appendicitis (APPY) is suspected is often difficult. Surgeons accept up to a 20% false positive rate to avoid any delay that may result in appendiceal rupture and peritonitis. The authors have successfully improved early diagnostic accuracy by using abdominal imaging beginning 2 hours after injecting In-111 labeled WBC. Patients with clear-cut (APPY) had laparotomy and were not studied. Those who were to be observed in the ER for possible (APPY) had their leukocytes harvested, labeled with In-111 oxine, and reinjected. Abnormal localized activity in the right lower quadrant (RLQ) imaged at 2 hours was graded relative to bone marrow activity (8M): 0, 1+ BM. When available the surgical specimen was imaged for In-111 activity. Of 31 patients studied there were 13 with positive scans for (APPY) all surgically confirmed. There were 4 additional abnormal studies all demonstrating known diagnostic patterns, 2 of pertonitis and 2 of colitis. There were 14 negative studies in 8 of whom the clinical course was benign; the remaining 6 had laparotomy with 3 having (APPY) and 3 not. Thus there were no false positives and 3 false negatives. One case negative at 2 hours had appendiceal activity later. The 3 cases with 3+ activity all had apendiceal abscesses. This new application of In-111 oxine WBC imaging is safe, simple, sensitive and specific. It shortens the time to surgical intervention and should reduce the surgical false positive rate

  19. Diagnostic usefulness of endorectal magnetic resonance imaging with dynamic contrast-enhancement in patients with localized prostate cancer. Mapping studies with biopsy specimens

    International Nuclear Information System (INIS)

    Tanaka, Nobumichi; Samma, Shoji; Joko, Masanori; Akiyama, Tatsuya; Takewa, Megumi; Kitano, Satoru; Okajima, Eigoro

    1999-01-01

    New diagnostic criteria for dynamic magnetic resonance (MR) imaging in prostate cancer are presented. The diagnostic usefulness of endorectal MR imaging with dynamic contrast-enhancement in localized prostate cancer and the validity of these criteria were evaluated. Eighteen untreated patients who were suspected of localized prostate cancer were included in the study. They received endorectal dynamic MR imaging before systematic sextant needle biopsy. First, a mapping study with the findings of MR images and histopathology of biopsy specimens was performed in eight patients out of 18 to compare the difference in T2-weighted images with the endorectal coil and the body coil in the same individuals. Second, another mapping study was performed in all 18 patients by analyzing the findings of endorectal dynamic MR images. For the diagnosis of prostate cancer in MR imaging, we offered diagnostic criteria from our experience in addition to those in plain T2-weighted images from the literature. The overall diagnostic rates of endorectal dynamic MR imaging were 88.9% in accuracy, 100% in sensitivity, and 81.8% in specificity. In the comparison of the endorectal and body coils in T2-weighted images in eight patients, there was no difference in the diagnostic rates except for one more histopathologic false positive portion in endorectal MR imaging. In the second mapping study in 18 patients, the diagnostic rates were 92.6% in accuracy, 88.9% in sensitivity and 93.3% in specificity. Endorectal dynamic imaging raised the diagnostic sensitivity from 77.8 to 88.9%. The data demonstrated the validity of this diagnostic criteria and the diagnostic usefulness of endorectal dynamic MR imaging in localized prostate cancer. (author)

  20. Should single-phase radionuclide bone imaging be used in suspected osteomyelitis

    International Nuclear Information System (INIS)

    Fihn, S.D.; Larson, E.B.; Nelp, W.B.; Rudd, T.G.; Gerber, F.H.

    1984-01-01

    The records of 69 patients who had 86 delayed, static radionuclide bone images for suspected osteomyelitis were studied to determine the effects of this procedure on diagnosis and treatment. Sensitivity, specificity, and positive predictive value were lower than reported in several other studies. When osteomyelitis was unlikely, imaging was either negative or falsely positive and rarely affected treatment. In 46 cases where osteomyelitis was more likely, imaging potentially changed therapy in 19 but was unhelpful or misleading in 15. Static-phase images with ''definite'' interpretations, particularly when negative, are specific, but ''equivocal'' studies may lead to diagnostic and therapeutic errors. When ostemyelitis is improbable, imaging rarely changes diagnosis or therapy

  1. Brain imaging studies of sleep disorder

    International Nuclear Information System (INIS)

    Nakamura, Masaki; Inoue, Yuichi

    2014-01-01

    Brain imaging studies of narcolepsy (NA)/cataplexy (CA), a typical sleep disorder, are summarized together with techniques of functional and structural imaging means. single photon emission CT (SPECT) is based on the distribution of tracers labeled by single photon emitters like 99m Tc and 123 I for seeing the blood flow and receptors. PET using positron emitters like 15 O and 18 F for blood flow and for glucose metabolism, respectively, is of higher resolution and more quantitative than SPECT. Functional MRI (fMRI) depicts the cerebral activity through signal difference by blood oxygenation level dependence (BOLD) effect, and MR spectroscopy (MRS) depicts and quantifies biomaterials through the difference of their nuclear chemical shifts in the magnetic field. Morphologic imaging studies involve the measurement of the volume of the region of interest by comparison with the reference region such as the whole brain volume. Voxel-based morphometry (VBM) has changed to its more advanced surface-based analysis (SBA) of T1-enhanced image. Diffusion tensor imaging (DTI) is based on the tissue water diffusion. Functional SPECT/PET studies have suggested the decrease of blood flow and metabolic activity in the hypothalamus (HT) and other related regions at the conscious resting state, and locally increased blood flow in cingulate gyrus (CG) and amygdaloid complex (AC) at affective CA/PA seizure. fMRI has suggested the hypoactivity of HT and hyperactivity of AC at the seizure. VBM-based studies have not given the consistent results, but DTI studies have suggested an important participation of AC at the seizure. (T.T.)

  2. A high resolution chromosome image processor for study purposes, NIRS-1000:CHROMO STUDY, and algorithm developing to classify radiation induced aberrations.

    Science.gov (United States)

    Yamamoto, M; Hayata, I; Furuta, S

    1992-03-01

    Since 1989 we have promoted a project to develop an automated scoring system of radiation induced chromosome aberrations. As a first step, a high resolution image processing system for study purposes, NIRS-1000:CHROMO STUDY, has been developed. It is composed of: (1) CHROMO MARKER whose main purpose is to mark on images to make image data base, (2) CHROMO ALGO whose purpose is algorithm development, and (3) METAPHASE RANKER whose purposes are metaphase finding and ranking with a high power objective lens. However, METAPHASE RANKER is presently under development. The system utilizes a high definition video system so as to realize the best spatial resolution that is achievable with an optical microscope using an objective lens (x 100, numerical aperture 1.4). The video camera has 1024 effective scan lines to realize 0.1 microns sampling on a specimen. The system resolution achieved on the hard copy is less than 0.3 microns on a specimen. A preliminary algorithm has been developed to classify the aberrations on the system using projection information of gray level. The preliminary test results on excellent 10 metaphases show that the correct classification ratio is 92.7%, that the detection rate of the aberrations is 83.3% and that the false positive rate is 6.1%.

  3. Comparative study of image restoration techniques in forensic image processing

    Science.gov (United States)

    Bijhold, Jurrien; Kuijper, Arjan; Westhuis, Jaap-Harm

    1997-02-01

    In this work we investigated the forensic applicability of some state-of-the-art image restoration techniques for digitized video-images and photographs: classical Wiener filtering, constrained maximum entropy, and some variants of constrained minimum total variation. Basic concepts and experimental results are discussed. Because all methods appeared to produce different results, a discussion is given of which method is the most suitable, depending on the image objects that are questioned, prior knowledge and type of blur and noise. Constrained minimum total variation methods produced the best results for test images with simulated noise and blur. In cases where images are the most substantial part of the evidence, constrained maximum entropy might be more suitable, because its theoretical basis predicts a restoration result that shows the most likely pixel values, given all the prior knowledge used during restoration.

  4. A comparative study of 99Tcm (V)-DMSA imaging with histopathological examination in ovarian neoplasms

    International Nuclear Information System (INIS)

    Zhao Xinming; Wang Jianfang; Xu Fang; Yin Jie; Wei Lanxiu; Sun Li

    1999-01-01

    Objective: To assess the clinical value of 99 Tc m (V)-Dmsa imaging in detecting the ovarian and the pelvic cavity neoplasms. Methods: 99 Tc m (V)-DMSA imaging was performed on 24 patients with diagnosed ovarian neoplasms which were pathologically confirmed after operation. Results: 14 of the 15 patients with malignant ovarian tumors had positive 99 Tc m (V)-DMSA scintigraphy. However, 7 of 9 cases with benign ovarian tumors had negative 99 Tc m (V)-DMSA scintigraphy. The sensitivity, specificity, positive predictive value, negative predictive value, false positive rate, false negative rate, and accuracy of 99 Tc m (V)-DMSA imaging for detecting malignant ovarian tumors were 93.33%, 77.78%, 87.50%, 87.50%, 14.29%, 6.67% and 87.50%, respectively. Conclusions: 99 Tc m (V)-DMSA imaging is of important value in detecting malignant and benign ovarian and pelvic tumors

  5. Scatterometry or imaging overlay: a comparative study

    Science.gov (United States)

    Hsu, Simon C. C.; Pai, Yuan Chi; Chen, Charlie; Yu, Chun Chi; Hsing, Henry; Wu, Hsing-Chien; Kuo, Kelly T. L.; Amir, Nuriel

    2015-03-01

    Most fabrication facilities today use imaging overlay measurement methods, as it has been the industry's reliable workhorse for decades. In the last few years, third-generation Scatterometry Overlay (SCOL™) or Diffraction Based Overlay (DBO-1) technology was developed, along another DBO technology (DBO-2). This development led to the question of where the DBO technology should be implemented for overlay measurements. Scatterometry has been adopted for high volume production in only few cases, always with imaging as a backup, but scatterometry overlay is considered by many as the technology of the future. In this paper we compare imaging overlay and DBO technologies by means of measurements and simulations. We outline issues and sensitivities for both technologies, providing guidelines for the best implementation of each. For several of the presented cases, data from two different DBO technologies are compared as well, the first with Pupil data access (DBO-1) and the other without pupil data access (DBO-2). Key indicators of overlay measurement quality include: layer coverage, accuracy, TMU, process robustness and robustness to process changes. Measurement data from real cases across the industry are compared and the conclusions are also backed by simulations. Accuracy is benchmarked with reference OVL, and self-consistency, showing good results for Imaging and DBO-1 technology. Process sensitivity and metrology robustness are mostly simulated with MTD (Metrology Target Designer) comparing the same process variations for both technologies. The experimental data presented in this study was done on ten advanced node layers and three production node layers, for all phases of the IC fabrication process (FEOL, MEOL and BEOL). The metrology tool used for most of the study is KLA-Tencor's Archer 500LCM system (scatterometry-based and imaging-based measurement technologies on the same tool) another type of tool is used for DBO-2 measurements. Finally, we conclude that

  6. Myositis ossificans: a false positive of malignancy in PET - CT F.D.G. and in osseous scintigraphy with HMDP {sup 99}Tc;La myosite ossifiante: un faux positif de malignite en TEP-TDM FDG et en scintigraphie osseuse au HMDP Tc99

    Energy Technology Data Exchange (ETDEWEB)

    Hassler, S.; Bourahla, K. [CLCC Paul-Strauss, Service de medecine nucleaire, 67 - Strasbourg (France)

    2010-05-15

    Myositis ossificans is a difficult differential diagnosis and a false positive for malignancy in both {sup 99m}Tc H.M.D.P. (hydroxy-methylene diphosphonate) scintigraphy and in exploration PET-F.D.G. This hypothesis should be mentioned in case of young patients, despite the unusual scintigraphic appearance in a benign process. (N.C.)

  7. Indium-111 chloride imaging in the detection of infected prostheses

    International Nuclear Information System (INIS)

    Sayle, B.A.; Fawcett, H.D.; Wilkey, D.J.; Cierny, G. III; Mader, J.T.

    1985-01-01

    Thirty-three patients with painful joint prostheses and a suspicion of infection were imaged with [ 111 In]chloride. A final diagnosis was established by culture in 19. Of these, 12 were categorized as true positives and three as true negatives. There were two false-positive studies, occurring in patients with knee prostheses. In both, the culture was obtained by aspiration. The sensitivity was 86%, specificity 60%, and accuracy 79%. Seventeen of the proven cases had bone imaging prior to [ 111 In]chloride imaging. All 17 static images were positive and were not helpful in differentiating loosening from infection. Using increased uptake on the blood-pool image as a criteria for infection, the sensitivity was 89%, but the specificity was 0. Adding flow studies made little difference in interpreting the blood-pool images. This study shows that [ 111 In]chloride imaging is more accurate in evaluating infection in prosthesis than bone imaging

  8. Low contrast detectability for color patterns variation of display images

    International Nuclear Information System (INIS)

    Ogura, Akio

    1998-01-01

    In recent years, the radionuclide images are acquired in digital form and displayed with false colors for signal intensity. This color scales for signal intensity have various patterns. In this study, low contrast detectability was compared the performance of gray scale cording with three color scales: the hot color scale, prism color scale and stripe color scale. SPECT images of brain phantom were displayed using four color patterns. These printed images and display images were evaluated with ROC analysis. Display images were indicated higher detectability than printed images. The hot scale and gray scale images indicated better Az of ROC than prism scale images because the prism scale images showed higher false positive rate. (author)

  9. Study of check image using computed radiography

    International Nuclear Information System (INIS)

    Sato, Hiroshi

    2002-01-01

    There are two image forming methods both a check image and a portal image in the linacogram. It has been established the image forming method in the check image using computed radiography (CR). On the other hand, it is not established the image forming method in the portal image using CR yet. Usually, in the electric portal imaging device (EPID) is mainly used just before radiotherapy start. The usefulness of the portal image forming method by CR using in place of EPID is possible to confirm the precision for determining to specific position at the irradiate part and to the irradiate method for the human organs. There are some technical problems that, since in the early time, the linac graphy (LG) image have low resolution power. In order to improve to the resolution power in LG image, CR image technologies have been introduced to the check image forming method. Heavy metallic sheet (HMS) is used to the front side of CR-IP cassette, and high contactness sponge is used to the back side of the cassette. Improved contactness between HMS and imaging plate (IP) by means of the high contactness sponge contributed to improve the resolution power in the check images. A lot of paper which is connected with these information have been reported. Imaging plate ST-III should be used to maintain high sensitivity in the check film image forming method. The same image forming method in the check image established by CR has been introduced into the portal image forming method in order to improve the resolution power. However, as a result, it couldn't acquired high resolution image forming in the portal images because of the combination of ST-III and radiotherapy dose. After several trials, it has been recognized that HR-V imaging plate for mammography is the most useful application to maintain high resolution power in the portal images. Also, it is possible to modify the image quality by changing GS parameter which is one of image processing parameters in CR. Furthermore, in case

  10. MRI quality control: six imagers studied using eleven unified image quality parameters

    International Nuclear Information System (INIS)

    Ihalainen, T.; Sipilae, O.; Savolainen, S.

    2004-01-01

    Quality control of the magnetic resonance imagers of different vendors in the clinical environment is non-harmonised, and comparing the performance is difficult. The purpose of this study was to develop and apply a harmonised long-term quality control protocol for the six imagers in our organisation in order to assure that they fulfil the same basic image quality requirements. The same Eurospin phantom set and identical imaging parameters were used with each imager. Values of 11 comparable parameters describing the image quality were measured. Automatic image analysis software was developed to objectively analyse the images. The results proved that the imagers were operating at a performance level adequate for clinical imaging. Some deficiencies were detected in image uniformity and geometry. The automated analysis of the Eurospin phantom images was successful. The measurements were successfully repeated after 2 weeks on one imager and after half a year on all imagers. As an objective way of examining the image quality, this kind of comparable and objective quality control of different imagers is considered as an essential step towards harmonisation of the clinical MRI studies through a large hospital organisation. (orig.)

  11. The influence of the noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) resection diagnosis on the false-positive thyroid cytology rate relates to quality assurance thresholds and the application of NIFTP criteria.

    Science.gov (United States)

    Ohori, N Paul; Wolfe, Jenna; Carty, Sally E; Yip, Linwah; LeBeau, Shane O; Berg, Aaron N; Schoedel, Karen E; Nikiforov, Yuri E; Seethala, Raja R

    2017-09-01

    Noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) is a newly defined entity and recent studies have suggested a decrease of a few percentage points in the rate of malignancy (ROM) for the positive-for-malignancy (PFM) cytology category as a result of NIFTP implementation. However, the distinction between a diagnosis of PFM and one of suspicious for malignancy (SFM) may depend on a variety of factors. In the current study, the authors investigated the ROM for the PFM and SFM diagnoses before and after histologic NIFTP reclassification. Cytology cases with PFM and SFM diagnoses and subsequent surgical resection specimens were searched in the files of the study institution from September 2008 to September 2016. The surgical pathology cases of noninvasive encapsulated follicular variant of papillary thyroid carcinoma were reexamined to determine whether they qualified for NIFTP. The distinct ROMs for the PFM and SFM cases were calculated accordingly. The authors' search identified 338 cases of PFM and 139 cases of SFM with a resection outcome. Before NIFTP reclassification, the PFM cases had a ROM of 99.4%; after NIFTP reclassification, the ROM was 99.1% (P = .6861). The ROM of the SFM cases decreased from 75.5% to 66.9% with NIFTP reclassification (P = .1402). One case in the PFM group and 6 cases in the SFM group could not be verified due to insufficient sampling. In the current large series, NIFTP reclassification did not appear to significantly alter the high ROM for the PFM diagnosis. The authors attribute this finding to a strict quality assurance policy, an emphasis on key cytologic criteria, and systematic application of the NIFTP criteria to follicular-patterned lesions. Cancer Cytopathol 2017;125:692-700. © 2017 American Cancer Society. © 2017 American Cancer Society.

  12. Visibility of Different Intraorbital Foreign Bodies Using Plain Radiography, Computed Tomography, Magnetic Resonance Imaging, and Cone-Beam Computed Tomography: An In Vitro Study.

    Science.gov (United States)

    Javadrashid, Reza; Golamian, Masoud; Shahrzad, Maryam; Hajalioghli, Parisa; Shahmorady, Zahra; Fouladi, Daniel F; Sadrarhami, Shohreh; Akhoundzadeh, Leila

    2017-05-01

    The study sought to compare the usefulness of 4 imaging modalities in visualizing various intraorbital foreign bodies (IOFBs) in different sizes. Six different materials including metal, wood, plastic, stone, glass. and graphite were cut in cylindrical shapes in 4 sizes (dimensions: 0.5, 1, 2, and 3 mm) and placed intraorbitally in the extraocular space of fresh sheep's head. Four skilled radiologists rated the visibility of the objects individually using plain radiography, spiral computed tomography (CT), magnetic resonance imaging (MRI), and cone-beam computed tomography (CBCT) in accordance with a previously described grading system. Excluding wood, all embedded foreign bodies were best visualized in CT and CBCT images with almost equal accuracies. Wood could only be detected using MRI, and then only when fragments were more than 2 mm in size. There were 3 false-positive MRI reports, suggesting air bubbles as wood IOFBs. Because of lower cost and using less radiation in comparison with conventional CT, CBCT can be used as the initial imaging technique in cases with suspected IOFBs. Optimal imaging technique for wood IOFBs is yet to be defined. Copyright © 2016 Canadian Association of Radiologists. Published by Elsevier Inc. All rights reserved.

  13. Magnetic resonance imaging of the lumbar spine: determining clinical impact and potential harm from overuse.

    Science.gov (United States)

    Wnuk, Nathan M; Alkasab, Tarik K; Rosenthal, Daniel I

    2018-04-18

    Lumbar spine MRI is frequently said to be "overused" in the evaluation of low-back pain, yet data concerning the extent of overuse and on potential harmful effects are lacking. To determine the proportion of examinations with a detectable impact on patient care (actionable outcomes). Retrospective cohort study PATIENT SAMPLE: 5,365 outpatient lumbar spine MR examinations OUTCOME MEASURES: Actionable outcomes included: 1) findings leading to an intervention making use of anatomical information such as surgery; 2) new diagnoses of cancer, infection, or fracture; or 3) following known lumbar spine pathology. Potential harm was assessed by identifying examinations where suspicion of cancer or infection was raised but no positive diagnosis made. A medical record aggregation/search system was used to identify lumbar spine MR examinations with positive outcome measures. Patient notes were examined to verify outcomes. A random sample was manually inspected to identify missed positive outcomes. The proportion of actionable lumbar spine MRIs was 13%, although 93% were appropriate according to American College of Radiology guidelines. Of 36 suspected cases of cancer/infection 81% were false positives. Further investigations were ordered on 59% of suspicious exams, 86% of which were false positives. The proportion of lumbar spine MR examinations that inform management is small. The false positive rate and proportion of false positives involving further investigation is high. Further study to improve the efficiency of imaging is warranted. Copyright © 2018 Elsevier Inc. All rights reserved.

  14. Re-thinking the store image study approach

    DEFF Research Database (Denmark)

    Hansen, Kåre

    2001-01-01

    Store image has traditionally been of interest in the Western markets. Studies of store image have also assessed the image of one or a few competing stores. This paper develops an approach to capture store images of an entire retail sector, an issue of importance when enter-ing the new emerging...

  15. Automated microaneurysm detection method based on double ring filter in retinal fundus images

    Science.gov (United States)

    Mizutani, Atsushi; Muramatsu, Chisako; Hatanaka, Yuji; Suemori, Shinsuke; Hara, Takeshi; Fujita, Hiroshi

    2009-02-01

    The presence of microaneurysms in the eye is one of the early signs of diabetic retinopathy, which is one of the leading causes of vision loss. We have been investigating a computerized method for the detection of microaneurysms on retinal fundus images, which were obtained from the Retinopathy Online Challenge (ROC) database. The ROC provides 50 training cases, in which "gold standard" locations of microaneurysms are provided, and 50 test cases without the gold standard locations. In this study, the computerized scheme was developed by using the training cases. Although the results for the test cases are also included, this paper mainly discusses the results for the training cases because the "gold standard" for the test cases is not known. After image preprocessing, candidate regions for microaneurysms were detected using a double-ring filter. Any potential false positives located in the regions corresponding to blood vessels were removed by automatic extraction of blood vessels from the images. Twelve image features were determined, and the candidate lesions were classified into microaneurysms or false positives using the rule-based method and an artificial neural network. The true positive fraction of the proposed method was 0.45 at 27 false positives per image. Forty-two percent of microaneurysms in the 50 training cases were considered invisible by the consensus of two co-investigators. When the method was evaluated for visible microaneurysms, the sensitivity for detecting microaneurysms was 65% at 27 false positives per image. Our computerized detection scheme could be improved for helping ophthalmologists in the early diagnosis of diabetic retinopathy.

  16. Imaging studies for failed back surgery syndrome

    International Nuclear Information System (INIS)

    Cosnard, G.; Cordoliani, Y.S.; Sarrazin, J.L.; Soulie, D.

    1995-01-01

    In patients with failed back surgery syndrome, magnetic resonance imaging (MRI) can be the best first-line imaging study because it simplifies the diagnosis. This update is based on over 600 cases. MRI shows the scar tissue at the surgical site, persistent evidence of disk herniation for several weeks after surgery, and evidence of local and regional edema in one-fourth of cases. The edema is most marked between two months and two years after the operation and can misleadingly suggest discitis. MRI is the best investigation for detecting recurrent herniation at the same vertebral level or another level. Herniated disk material is seen as a mass that does not enhance after gadolinium, in contrast to the vascularized scar tissue. Free fragments are often clearly visible within the scar tissue. Fragments that migrate to the epidural space can give rise to granulomatous reactions. Scar tissue can be seen in the epidural space and within the disk; it can show enhancement after gadolinium for several years. The scar can be atrophic or hypertrophic and can encase or impinge on the dural sac and nerve roots. Pathological fibrosis cannot be differentiated from ordinary scar tissue. Arachnoiditis causing adherence of the nerve roots to the dura mater or to each other occurs in 5 % to 10 % of cases. Nerve root enhancement after gadolinium is seen in three-fourths of cases. Bone lesions are common, especially some time after surgery; they are usually accompanied with other lesions. Hematomas are seen in less than 10 % of cases. Infections are similarly rare (0.25 % each for discitis and epiduritis). The diagnosis of discitis is difficult and requires percutaneous biopsy of the disk, especially when MRI shows fluid within the disk, with decreased signal intensity on T2 images, and non enhancement after intravenous gadolinium. (authors). 19 refs., 7 figs

  17. Animal imaging studies of potential brain damage

    Science.gov (United States)

    Gatley, S. J.; Vazquez, M. E.; Rice, O.

    To date, animal studies have not been able to predict the likelihood of problems in human neurological health due to HZE particle exposure during space missions outside the Earth's magnetosphere. In ongoing studies in mice, we have demonstrated that cocaine stimulated locomotor activity is reduced by a moderate dose (120 cGy) of 1 GeV 56Fe particles. We postulate that imaging experiments in animals may provide more sensitive and earlier indicators of damage due to HZE particles than behavioral tests. Since the small size of the mouse brain is not well suited to the spatial resolution offered by microPET, we are now repeating some of our studies in a rat model. We anticipate that this will enable us to identify imaging correlates of behavioral endpoints. A specific hypothesis of our studies is that changes in the metabolic rate for glucose in striatum of animals will be correlated with alterations in locomotor activity. We will also evaluate whether the neuroprotective drug L-deprenyl reduces the effect of radiation on locomotor activity. In addition, we will conduct microPET studies of brain monoamine oxidase A and monoamine oxidase B in rats before and at various times after irradiation with HZE particles. The hypothesis is that monoamine oxidase A, which is located in nerve terminals, will be unchanged or decreased after irradiation, while monoamine oxidase B, which is located in glial cells, will be increased after irradiation. Neurochemical effects that could be measured using PET could in principle be applied in astronauts, in terms of detecting and monitoring subtle neurological damage that might have occurred during long space missions. More speculative uses of PET are in screening candidates for prolonged space missions (for example, for adequate reserve in critical brain circuits) and in optimizing medications to treat impairments after missions.

  18. Feasibility study of superharmonic imaging using chirps

    NARCIS (Netherlands)

    Van Neer, P.; Danilouchkine, M.G.; Matte, G.; Voormolen, M.M.; Verweij, M.D.; De Jong, N.

    2010-01-01

    Superharmonic imaging (SHI) targets a combination of the 3rd to 5th harmonics. It was proven to have certain advantages in comparison with the established imaging standards in medical utrasound. SHI enhances the spatial resolution and improves the quality of echographic images, mainly by eliminating

  19. Towards "Zero" False Positive in Structural Health Monitoring

    National Research Council Canada - National Science Library

    Chiu, Wing K; Chang, F. K; Tian, Daniel T

    2007-01-01

    Structural Health Monitoring (SHM) is one aspect of a revolution based on the use of Smart Materials and Structures technologies that have the potential to provide major gains in structural performance and cost-efficient life management...

  20. Detection of Biological False Positive Syphilis Serum Reactions ...

    African Journals Online (AJOL)

    A comparative evaluation of reagin tests (Wassermann, VDRL, RPR) and fluorescent treponema antibody absorption tests (FTA-ABS) performed on blood specimens from 5 271 persons (2 493 pregnant women, 1 130 apparently healthy prospective employees, 1 345 newborn babies and 303 leprosy patients) showed that ...

  1. Efficacy of 67 gallium ECT imaging in lymphoma, infection, and lung carcinoma: A comparison with planar imaging

    International Nuclear Information System (INIS)

    Harwood, S.J.; Anderson, M.W.; Klein, R.C.; Friedman, B.I.; Carroll, R.G.

    1984-01-01

    Emission computed tomography (ECT) studies were performed on a GE 400 A/T camera and ADAC computers (system 3 and system 3300). Thirty-three sets of ECT and planar images were obtained in 20 patients over a six month period. Imaging was performed 48 hours after the intravenous administration of 5 mc of Gallium 67 citrate. No bowel preparation was employed. Comparison is made of the initial nuclear medicine report derived from planar and ECT imaging aided by clinical knowledge versus the consensus opinion of two nuclear medicine physicians reading the planar images along with minimal clinical information. The lymphoma series consists of 18 scans in 10 patients. There were 5 scans in which a false negative planar interpretation was changed to a true positive ECT interpretation. Sensitivity of planar imaging for lymphoma was 58% which rose to 100% with addition of ECT information. There were no false positives by either technique. There were 5 sets of scans in 5 lung carcinoma patients. Sensitivity of the planar images was 60% because of 2 false negative results. Sensitivity of the ECT technique was 100%. There were no false positives. The infection series consists of 10 scans in 5 patients. Sensitivity of ECT was 100%, sensitivity of planar was 66%. There was 1 false positive planar. For the total series the accuracy of planar imaging was 69% and the predictive value of a negative planar interpretation was 44%. Corresponding values for ECT imaging were 100%. The authors' experience demonstrates significant increase in sensitivity without loss of specificity resulting from the use of Emission Computed Tomography in both chest and abdomen in patients with lymphoma, infection, and lung cancer

  2. MR imaging of recurrent hyperparathyroidism in comparison with other imaging modalities

    International Nuclear Information System (INIS)

    Auffermann, W.; Thurnher, S.; Okerland, M.; Levin, K.; Gooding, G.W.; Clark, O.H.; Higgins, C.B.

    1987-01-01

    Thirty patients with recurrent hyperparathyroidism were evaluated with MR imaging, performed using a saddle-shaped surface coil producing 5-mm sections with T1 and T2 weighting. Twenty-six and 22 of these patients also underwent T1-201 scintigraphy and high-resolution US, respectively. MR imaging accurately localized abnormal parathyroid glands in 75% evaluated prospectively and 86% retrospectively. Scintigraphy localized 64% prospectively and 72% retrospectively. US demonstrated 57% prospectively and 67% retrospectively. MR imaging showed three of four mediastinal adenomas evaluated prospectively retrospectively. There were two false-positive studies with MR imaging, two with scintigraphy, and one with US. Thus, MR imaging was the most effective imaging modality for parathyroid localization in recurrent hyperparathyroidism

  3. PET IMAGING STUDIES IN DRUG ABUSE RESEARCH.

    Energy Technology Data Exchange (ETDEWEB)

    Fowler, J.S.; Volkow, N.D.; Ding, Y.S.; Logan, J.; Wang, G.J.

    2001-01-29

    . This will be followed by highlights of PET studies of the acute effects of the psychostimulant drugs cocaine and methylphenidate (ritalin) and studies of the chronic effects of cocaine and of tobacco smoke on the human brain. This chapter concludes with the description of a study which uses brain imaging coupled with a specific pharmacological challenge to address the age-old question of why some people who experiment with drugs become addicted while others do not.

  4. Detection of lymph node metastases with ultrasmall superparamagnetic iron oxide (USPIO)-enhanced magnetic resonance imaging in oesophageal cancer: a feasibility study

    Science.gov (United States)

    van der Jagt, E.J.; van Westreenen, H.L.; van Dullemen, H.M.; Kappert, P.; Groen, H.; Sietsma, J.; Oudkerk, M.; Plukker, J.Th.M.; van Dam, G.M.

    2009-01-01

    Abstract Aim: In this feasibility study we investigated whether magnetic resonance imaging (MRI) with ultrasmall superparamagnetic iron oxide (USPIO) can be used to identify regional and distant lymph nodes, including mediastinal and celiac lymph node metastases in patients with oesophageal cancer. Patients and methods: Ten patients with a potentially curative resectable cancer of the oesophagus were eligible for this study. All patients included in the study had positive lymph nodes on conventional staging (including endoscopic ultrasound, computed tomography and fluorodeoxyglucose-positron emission tomography). Nine patients underwent MRI + USPIO before surgery. Results were restricted to those patients who had both MRI + USPIO and histological examination. Results were compared with conventional staging and histopathologic findings. Results: One patient was excluded due to expired study time. Five out of 9 patients underwent an exploration; in 1 patient prior to surgery MRI + USPIO diagnosed liver metastases and in 3 patients an oesophageal resection was performed. USPIO uptake in mediastinal lymph nodes was seen in 6 out of 9 patients; in 3 patients non-malignant nodes were not visible. In total, 9 lymph node stations (of 6 patients) were separately analysed; 7 lymph node stations were assessed as positive (N1) on MRI+USPIO compared with 9 by conventional staging. According to histology findings, there was one false-positive and one false-negative result in MRI + USPIO. Also, conventional staging modalities had one false-positive and one false-negative result. MRI + USPIO had surplus value in one patient. Not all lymph node stations could be compared due to unforeseen explorations. No adverse effects occurred after USPIO infusion. Conclusion: MRI+USPIO identified the majority of mediastinal and celiac (suspect) lymph nodes in 9 patients with oesophageal cancer. MRI+USPIO could have an additional value in loco-regional staging; however, more

  5. Perivesical varices and portal hypertension: imaging study

    International Nuclear Information System (INIS)

    Mallorquin Jimenez, F.; Medina Benitez, A.; Lopez Machado, E.; Pardo Moreno, M.D.; Garrido Moreno, C.; Pastor Rull, J.

    1995-01-01

    Nine patients with portal hypertension syndrome and Perivesical varices are studied retrospectively by means of imaging techniques including ultrasound, duplex Doppler, color Doppler, CT and angiography. All the patients presented portal thrombosis and thickening of the bladder wall. These collaterals either represent a shunting of hepato pedal flow or correspond to blood stasis associated with said syndrome. Ultrasound, whether involving duplex Doppler or color Doppler techniques, is highly useful to detect the presence of Perivesical varices which appear as tubular or rounded hypo echogenic areas in the bladder wall. Given the association of this entity with bladder wall thickening, it should be taken into account in any clinical situation involving said change, especially in patients with portal hypertension; moreover knowledge of its presence is of great importance when the possibility of creating shunts by means of interventional or surgical vascular procedures or other types of abdominal procedures are being considered because of the risk of bleeding. (Author)

  6. Gen-2 Hand-Held Optical Imager towards Cancer Imaging: Reflectance and Transillumination Phantom Studies

    Directory of Open Access Journals (Sweden)

    Anuradha Godavarty

    2012-02-01

    Full Text Available Hand-held near-infrared (NIR optical imagers are developed by various researchers towards non-invasive clinical breast imaging. Unlike these existing imagers that can perform only reflectance imaging, a generation-2 (Gen-2 hand-held optical imager has been recently developed to perform both reflectance and transillumination imaging. The unique forked design of the hand-held probe head(s allows for reflectance imaging (as in ultrasound and transillumination or compressed imaging (as in X-ray mammography. Phantom studies were performed to demonstrate two-dimensional (2D target detection via reflectance and transillumination imaging at various target depths (1–5 cm deep and using simultaneous multiple point illumination approach. It was observed that 0.45 cc targets were detected up to 5 cm deep during transillumination, but limited to 2.5 cm deep during reflectance imaging. Additionally, implementing appropriate data post-processing techniques along with a polynomial fitting approach, to plot 2D surface contours of the detected signal, yields distinct target detectability and localization. The ability of the gen-2 imager to perform both reflectance and transillumination imaging allows its direct comparison to ultrasound and X-ray mammography results, respectively, in future clinical breast imaging studies.

  7. Applying a CAD-generated imaging marker to assess short-term breast cancer risk

    Science.gov (United States)

    Mirniaharikandehei, Seyedehnafiseh; Zarafshani, Ali; Heidari, Morteza; Wang, Yunzhi; Aghaei, Faranak; Zheng, Bin

    2018-02-01

    Although whether using computer-aided detection (CAD) helps improve radiologists' performance in reading and interpreting mammograms is controversy due to higher false-positive detection rates, objective of this study is to investigate and test a new hypothesis that CAD-generated false-positives, in particular, the bilateral summation of false-positives, is a potential imaging marker associated with short-term breast cancer risk. An image dataset involving negative screening mammograms acquired from 1,044 women was retrospectively assembled. Each case involves 4 images of craniocaudal (CC) and mediolateral oblique (MLO) view of the left and right breasts. In the next subsequent mammography screening, 402 cases were positive for cancer detected and 642 remained negative. A CAD scheme was applied to process all "prior" negative mammograms. Some features from CAD scheme were extracted, which include detection seeds, the total number of false-positive regions, an average of detection scores and the sum of detection scores in CC and MLO view images. Then the features computed from two bilateral images of left and right breasts from either CC or MLO view were combined. In order to predict the likelihood of each testing case being positive in the next subsequent screening, two logistic regression models were trained and tested using a leave-one-case-out based cross-validation method. Data analysis demonstrated the maximum prediction accuracy with an area under a ROC curve of AUC=0.65+/-0.017 and the maximum adjusted odds ratio of 4.49 with a 95% confidence interval of [2.95, 6.83]. The results also illustrated an increasing trend in the adjusted odds ratio and risk prediction scores (pbreast cancer risk.

  8. Radiation: Rational use of diagnostic imaging studies in pediatrics

    International Nuclear Information System (INIS)

    Gentile, Fernando

    2008-01-01

    The objectives of this paper are to recognize the biological effects of radiation; explain the action of ionizing radiation on the cell; list the main sources of ionizing radiation; to indicate imaging studies considering the danger of radiation; select the method of imaging saving radiation; rational use of imaging studies without repeating exams. [es

  9. In-111 WBC imaging in musculoskeletal sepsis

    International Nuclear Information System (INIS)

    Thompson, L.; Ouzounian, T.J.; Webber, M.M.; Amstutz, H.C.

    1984-01-01

    This study evaluated the accuracy and utility of the In-111 labeled WBC imaging in a series of patients who were suspected of having musculoskeletal sepsis. The labeling of the WBCs was patterned after a method previously described, in which the WBCs are labeled with In-111 oxine in plasma. The WBCs from 100 ml of blood are separated and incubated with In-111 oxine complex, and then 500 μCi. of the labeled cells were reinjected into the patient. Images of the areas in question were obtained at 24 hrs. In some instances, 48 hour images were also obtained. Images were interpreted using consistent criteria. Forty imaging procedures were done on 39 patients. These included 39 total joint protheses, and 17 other images to evaluate possible osteomyelitis, septic arthritis or deep abscesses. Of these studies, 15 were positive, and 42 negative. The findings were then correlated with operative culture and pathology in 21, aspiration cultures and gram stains in 14, and with clinical findings in the remaining 21. This correlation showed 41 true negatives, 12 true positives, 1 false negative, and 2 false positives. The sensitivity was 92.9% and the specificity was 95.2%l. The false negative occurred in a patient on chronic suppressive antibiotic therapy for an infected total hip replacement. The false positive images occurred in a patient with active rheumatoid arthritis and in a patient imaged one month post operative placement of the prosthesis. These images were very useful in several septic patients who had many possible sites of infection. The authors conclude that In-III imaging is an accurate and useful non-invasive method of evaluating musculoskeletal sepsis

  10. Imaging studies in chronic low back pain

    International Nuclear Information System (INIS)

    Alcalay, M.; Bourgeois, P.; Lazennec, J.Y.; Roger, B.; Dehais, J.; Dousse, V.; Laredo, J.D.; Morvan, G.; Ristori, J.M.

    1994-01-01

    Imaging brings to difficult problems in chronic low back pain incomplete data showing that it will need a lot of time to find therapeutic solutions. Some comparisons are made between tomodensitometry, nuclear magnetic imaging, the disco-scanner, these technologies allow to find small lesions but the problem is complete when it is not possible to find anything with persistent pains. 125 refs

  11. Study of Three-Dimensional Image Brightness Loss in Stereoscopy

    Directory of Open Access Journals (Sweden)

    Hsing-Cheng Yu

    2015-10-01

    Full Text Available When viewing three-dimensional (3D images, whether in cinemas or on stereoscopic televisions, viewers experience the same problem of image brightness loss. This study aims to investigate image brightness loss in 3D displays, with the primary aim being to quantify the image brightness degradation in the 3D mode. A further aim is to determine the image brightness relationship to the corresponding two-dimensional (2D images in order to adjust the 3D-image brightness values. In addition, the photographic principle is used in this study to measure metering values by capturing 2D and 3D images on television screens. By analyzing these images with statistical product and service solutions (SPSS software, the image brightness values can be estimated using the statistical regression model, which can also indicate the impact of various environmental factors or hardware on the image brightness. In analysis of the experimental results, comparison of the image brightness between 2D and 3D images indicates 60.8% degradation in the 3D image brightness amplitude. The experimental values, from 52.4% to 69.2%, are within the 95% confidence interval

  12. Study about Illness: Through the Narrative of "Illness Image"

    OpenAIRE

    岩城, 晶子

    2013-01-01

    In this research, the meaning of the illness was studied from the perpective of Image. From listening to the narrative about two types of Illness Image, i.e., "my illness" and "A's illness, " we found that there was a characteristic that the Illness Image was similar to the real image. In addition, there were several differences between 2 images, which indicated that distance between the narrator and these images had an influence. From the syudy of two cases, it was indicated that Illness Ima...

  13. Acute spinal epidural hematoma: MR imaging study

    International Nuclear Information System (INIS)

    Xu Wenjian; Xu Aide

    2003-01-01

    Objective: To study the pathogenesis of acute spinal epidural hematomas (ASEHs), MRI features, and its value on diagnosis and differential diagnosis. Methods: Fifteen patients with ASEHs (8 males, 7 females, mean age 37.8 years) were reviewed. Seven of the patients were secondary to spinal injuries (5 spinal trauma, 1 post-spinal operation, and 1 post-lumbar puncture) and 8 were spontaneous. Eleven patients were confirmed by operation. MRI was performed in all patients in sagittal SE T 1 WI and SE or FSE T 2 WI, 12 in axial FSE T 2 WI, 8 in axial SE T 1 WI, and 4 in contrast-enhanced SE T 1 WI. Results: Fifteen ASEHs involved 18 spinal segments, 6 of the segments (6/18) in cervical spine, 9 segments (9/18) in thoracic spine, and 3 segments (3/18) in lumbar spine. The hematomas located at pre-epidural space in 7 segments (7/18) and at posterolateral epidural space in 11 segments (11/18). The craniocaudal extent of the hematomas varied from 1 to 13 vertebral levels (average 4.87 vertebral level). There were low signal intensity lines between hematomas and spinal cord in all of the cases on T 1 WI. The low signal intensity line between hematoma and subarachnoid space was demonstrated in 8 cases (8/12) and 4 cases (4/15) on axial T 2 WI and sagittal T 2 WI, respectively. The figure of hematomas was biconvex on axial imaging in all of the cases, and long lentiform on sagittal imaging in 13 cases (13/15). The hematomas showed variable signal intensity. On T 1 WI, 5 showed isointensity to cord, 6 with hyperintensity, and 4 with inhomogeneous iso-hyperintensity. On T 2 WI, 5 showed hypointensity, 10 with inhomogeneous hypo-hyperintensity. There was no special MR manifestation after contrast administration. Conclusion: ASEHs is a rare disorder, and MRI features are characteristic for the diagnosis and differential diagnosis

  14. Terahertz pulsed imaging study of dental caries

    Science.gov (United States)

    Karagoz, Burcu; Altan, Hakan; Kamburoglu, Kıvanç

    2015-07-01

    Current diagnostic techniques in dentistry rely predominantly on X-rays to monitor dental caries. Terahertz Pulsed Imaging (TPI) has great potential for medical applications since it is a nondestructive imaging method. It does not cause any ionization hazard on biological samples due to low energy of THz radiation. Even though it is strongly absorbed by water which exhibits very unique chemical and physical properties that contribute to strong interaction with THz radiation, teeth can still be investigated in three dimensions. Recent investigations suggest that this method can be used in the early identification of dental diseases and imperfections in the tooth structure without the hazards of using techniques which rely on x-rays. We constructed a continuous wave (CW) and time-domain reflection mode raster scan THz imaging system that enables us to investigate various teeth samples in two or three dimensions. The samples comprised of either slices of individual tooth samples or rows of teeth embedded in wax, and the imaging was done by scanning the sample across the focus of the THz beam. 2D images were generated by acquiring the intensity of the THz radiation at each pixel, while 3D images were generated by collecting the amplitude of the reflected signal at each pixel. After analyzing the measurements in both the spatial and frequency domains, the results suggest that the THz pulse is sensitive to variations in the structure of the samples that suggest that this method can be useful in detecting the presence of caries.

  15. False-Positive Results in a Recombinant Severe Acute Respiratory Syndrome-Associated Coronavirus (SARS-CoV) Nucleocapsid Enzyme-Linked Immunosorbent Assay Due to HCoV-OC43 and HCoV-229E Rectified by Western Blotting with Recombinant SARS-CoV Spike Polypeptide

    OpenAIRE

    Woo, Patrick C. Y.; Lau, Susanna K. P.; Wong, Beatrice H. L.; Chan, Kwok-Hung; Hui, Wai-Ting; Kwan, Grace S. W.; Peiris, J. S. Malik; Couch, Robert B.; Yuen, Kwok-Yung

    2004-01-01

    Using paired serum samples obtained from patients with illness associated with increases in anti-human coronavirus OC43 (HCoV-OC43) or anti-HCoV-229E antibodies, we examined the possibility of false-positive results detected in a recombinant severe acute respiratory syndrome (SARS)-associated coronavirus (SARS-CoV) nucleocapsid protein immunoglobulin G enzyme-linked immunosorbent assay (ELISA). Three of the 21 and 1 of the 7 convalescent-phase serum samples from persons with increases in anti...

  16. Role of chelates in magnetic resonance imaging studies

    Directory of Open Access Journals (Sweden)

    Tripathi Laxmi

    2009-01-01

    Full Text Available Imaging studies are tests performed with a variety of techniques that produce pictures of the inside of a patient′s body. Magnetic resonance imaging (MRI is an imaging technique based on the principles of nuclear magnetic resonance. MRI uses a powerful magnetic field, radio waves, and a computer to produce detailed pictures of organs, soft tissues, bone, and virtually all other internal body structures. Chelates have a wide application in such imaging techniques. Chelates in imaging studies are used alone as radioactive agents or conjugated to monoclonal antibodies or to DNA as radioactive agents. Technetium chelates and gadolinium chelates are being widely used as magnetic resonance contrast media.

  17. TREE STEM RECONSTRUCTION USING VERTICAL FISHEYE IMAGES: A PRELIMINARY STUDY

    Directory of Open Access Journals (Sweden)

    A. Berveglieri

    2016-06-01

    Full Text Available A preliminary study was conducted to assess a tree stem reconstruction technique with panoramic images taken with fisheye lenses. The concept is similar to the Structure from Motion (SfM technique, but the acquisition and data preparation rely on fisheye cameras to generate a vertical image sequence with height variations of the camera station. Each vertical image is rectified to four vertical planes, producing horizontal lateral views. The stems in the lateral view are rectified to the same scale in the image sequence to facilitate image matching. Using bundle adjustment, the stems are reconstructed, enabling later measurement and extraction of several attributes. The 3D reconstruction was performed with the proposed technique and compared with SfM. The preliminary results showed that the stems were correctly reconstructed by using the lateral virtual images generated from the vertical fisheye images and with the advantage of using fewer images and taken from one single station.

  18. Reevaluation of JPEG image compression to digitalized gastrointestinal endoscopic color images: a pilot study

    Science.gov (United States)

    Kim, Christopher Y.

    1999-05-01

    Endoscopic images p lay an important role in describing many gastrointestinal (GI) disorders. The field of radiology has been on the leading edge of creating, archiving and transmitting digital images. With the advent of digital videoendoscopy, endoscopists now have the ability to generate images for storage and transmission. X-rays can be compressed 30-40X without appreciable decline in quality. We reported results of a pilot study using JPEG compression of 24-bit color endoscopic images. For that study, the result indicated that adequate compression ratios vary according to the lesion and that images could be compressed to between 31- and 99-fold smaller than the original size without an appreciable decline in quality. The purpose of this study was to expand upon the methodology of the previous sty with an eye towards application for the WWW, a medium which would expand both clinical and educational purposes of color medical imags. The results indicate that endoscopists are able to tolerate very significant compression of endoscopic images without loss of clinical image quality. This finding suggests that even 1 MB color images can be compressed to well under 30KB, which is considered a maximal tolerable image size for downloading on the WWW.

  19. Adding attenuation corrected images in myocardial perfusion imaging reduces the need for a rest study

    International Nuclear Information System (INIS)

    Trägårdh, Elin; Valind, Sven; Edenbrandt, Lars

    2013-01-01

    The American Society of Nuclear Cardiology and the Society of Nuclear Medicine conclude that incorporation of attenuation corrected (AC) images in myocardial perfusion scintigraphy (MPS) will improve diagnostic accuracy. The aim was to investigate the value of adding AC stress-only images for the decision whether a rest study is necessary or not. 1,261 patients admitted to 99m Tc MPS were studied. The stress studies were interpreted by two physicians who judged each study as “no rest study necessary” or “rest study necessary”, by evaluating NC stress-only and NC + AC stress-only images. When there was disagreement between the two physicians, a third physician evaluated the studies. Thus, agreement between 2 out of 3 physicians was evaluated. The physicians assessed 214 more NC + AC images than NC images as “no rest study necessary” (17% of the study population). The number of no-rest-study-required was significantly higher for NC + AC studies compared to NC studies (859 vs 645 cases (p < 0.0001). In the final report according to clinical routine, ischemia or infarction was reported in 23 patients, assessed as “no rest study necessary” (22 NC + AC cases; 8 NC cases), (no statistically significant difference). In 11 of these, the final report stated “suspected/possible ischemia or infarction in a small area”. Adding AC stress-only images to NC stress-only images reduce the number of unnecessary rest studies substantially

  20. Validation of Diagnostic Imaging Based on Repeat Examinations. An Image Interpretation Model

    International Nuclear Information System (INIS)

    Isberg, B.; Jorulf, H.; Thorstensen, Oe.

    2004-01-01

    Purpose: To develop an interpretation model, based on repeatedly acquired images, aimed at improving assessments of technical efficacy and diagnostic accuracy in the detection of small lesions. Material and Methods: A theoretical model is proposed. The studied population consists of subjects that develop focal lesions which increase in size in organs of interest during the study period. The imaging modality produces images that can be re-interpreted with high precision, e.g. conventional radiography, computed tomography, and magnetic resonance imaging. At least four repeat examinations are carried out. Results: The interpretation is performed in four or five steps: 1. Independent readers interpret the examinations chronologically without access to previous or subsequent films. 2. Lesions found on images at the last examination are included in the analysis, with interpretation in consensus. 3. By concurrent back-reading in consensus, the lesions are identified on previous images until they are so small that even in retrospect they are undetectable. The earliest examination at which included lesions appear is recorded, and the lesions are verified by their growth (imaging reference standard). Lesion size and other characteristics may be recorded. 4. Records made at step 1 are corrected to those of steps 2 and 3. False positives are recorded. 5. (Optional) Lesion type is confirmed by another diagnostic test. Conclusion: Applied on subjects with progressive disease, the proposed image interpretation model may improve assessments of technical efficacy and diagnostic accuracy in the detection of small focal lesions. The model may provide an accurate imaging reference standard as well as repeated detection rates and false-positive rates for tested imaging modalities. However, potential review bias necessitates a strict protocol

  1. Study on the usefulness of whole body SPECT coronal image, MIP image in 67Ga scintigraphy

    International Nuclear Information System (INIS)

    Kawamura, Seiji

    2002-01-01

    In this study, we examined the usefulness of whole body coronal images and whole body cine display MIP images (CMIP) upon which image processing was carried out after whole body SPECT in comparison to the usefulness of whole body images (WB/SC) compensated by scattered radiation in tumor/inflammation scintigraphy with 67 Ga-citrate ( 67 Ga). Image interpretation was performed for the 120 patients with confirmed diagnoses, and the accuracy of their diagnoses was studied by three nuclear medical physicians and two clinical radiological technologists by means of sensitivity, specificity and ROC analysis. The resultant data show that sensitivity, specificity, accuracy and the area under the ROC curve Az in the WB/SC were approximately 65%, 86%, 74% and 0.724, respectively, whereas sensitivity, specificity, accuracy and Az of the image reading system in which CMIP is combined with whole body coronal images reconstructed by the OS-EM method were approximately 93%, 95%, 94% and 0.860, respectively. Furthermore, coronal images reconstructed by the OS-EM method tended to be superior to those produced by the FBP method in both diagnostic accuracy and ROC analysis. In conclusion, the image reading system in which CMIP is combined with whole body coronal images reconstructed by the OS-EM method was shown to be superior in diagnostic accuracy and ROC analysis. Our data suggest that whole body SPECT is an excellent technique as an alternative to WB/SC. (author)

  2. Behaviors study of image registration algorithms in image guided radiation therapy

    International Nuclear Information System (INIS)

    Zou Lian; Hou Qing

    2008-01-01

    Objective: Study the behaviors of image registration algorithms, and analyze the elements which influence the performance of image registrations. Methods: Pre-known corresponding coordinates were appointed for reference image and moving image, and then the influence of region of interest (ROI) selection, transformation function initial parameters and coupled parameter spaces on registration results were studied with a software platform developed in home. Results: Region of interest selection had a manifest influence on registration performance. An improperly chosen ROI resulted in a bad registration. Transformation function initial parameters selection based on pre-known information could improve the accuracy of image registration. Coupled parameter spaces would enhance the dependence of image registration algorithm on ROI selection. Conclusions: It is necessary for clinic IGRT to obtain a ROI selection strategy (depending on specific commercial software) correlated to tumor sites. Three suggestions for image registration technique developers are automatic selection of the initial parameters of transformation function based on pre-known information, developing specific image registration algorithm for specific image feature, and assembling real-time image registration algorithms according to tumor sites selected by software user. (authors)

  3. A study of whether automated Diabetic Retinopathy Image Assessment could replace manual grading steps in the English National Screening Programme.

    Science.gov (United States)

    Kapetanakis, Venediktos V; Rudnicka, Alicja R; Liew, Gerald; Owen, Christopher G; Lee, Aaron; Louw, Vern; Bolter, Louis; Anderson, John; Egan, Catherine; Salas-Vega, Sebastian; Rudisill, Caroline; Taylor, Paul; Tufail, Adnan

    2015-09-01

    Diabetic retinopathy screening in England involves labour intensive manual grading of digital retinal images. We present the plan for an observational retrospective study of whether automated systems could replace one or more steps of human grading. Patients aged 12 or older who attended the Diabetes Eye Screening programme, Homerton University Hospital (London) between 1 June 2012 and 4 November 2013 had macular and disc-centred retinal images taken. All screening episodes were manually graded and will additionally be graded by three automated systems. Each system will process all screening episodes, and screening performance (sensitivity, false positive rate, likelihood ratios) and diagnostic accuracy (95% confidence intervals of screening performance measures) will be quantified. A sub-set of gradings will be validated by an approved Reading Centre. Additional analyses will explore the effect of altering thresholds for disease detection within each automated system on screening performance. 2,782/20,258 diabetes patients were referred to ophthalmologists for further examination. Prevalence of maculopathy (M1), pre-proliferative retinopathy (R2), and proliferative retinopathy (R3) were 7.9%, 3.1% and 1.2%, respectively; 4749 (23%) patients were diagnosed with background retinopathy (R1); 1.5% were considered ungradable by human graders. Retinopathy prevalence was similar to other English diabetic screening programmes, so findings should be generalizable. The study population size will allow the detection of differences in screening performance between the human and automated grading systems as small as 2%. The project will compare performance and economic costs of manual versus automated systems. © The Author(s) 2015.

  4. Color feature extraction of HER2 Score 2+ overexpression on breast cancer using Image Processing

    Directory of Open Access Journals (Sweden)

    Muhimmah Izzati

    2018-01-01

    Full Text Available One of the major challenges in the development of early diagnosis to assess HER2 status is recognized in the form of Gold Standard. The accuracy, validity and refraction of the Gold Standard HER2 methods are widely used in laboratory (Perez, et al., 2014. Method determining the status of HER2 (human epidermal growth factor receptor 2 is affected by reproductive problems and not reliable in predicting the benefit from anti-HER2 therapy (Nuciforo, et al., 2016. We extracted color features by methods adopting Statistics-based segmentation using a continuous-scale naïve Bayes approach. In this study, there were three parts of the main groups, namely image acquisition, image segmentation, and image testing. The stages of image acquisition consisted of image data collection and color deconvolution. The stages of image segmentation consisted of color features, classifier training, classifier prediction, and skeletonization. The stages of image testing were image testing, expert validation, and expert validation results. Area segmentation of the membrane is false positive and false negative. False positive and false negative from area are called the area of system failure. The failure of the system can be validated by experts that the results of segmentation region is not membrane HER2 (noise and the segmentation of the cytoplasm region. The average from 40 data of HER2 score 2+ membrane images show that 75.13% of the area is successfully recognized by the system.

  5. Imaging biomarker roadmap for cancer studies

    NARCIS (Netherlands)

    O'Connor, James P. B.; Aboagye, Eric O.; Adams, Judith E.; Aerts, Hugo J. W. L.; Barrington, Sally F.; Beer, Ambros J.; Boellaard, Ronald; Bohndiek, Sarah E.; Brady, Michael; Brown, Gina; Buckley, David L.; Chenevert, Thomas L.; Clarke, Laurence P.; Collette, Sandra; Cook, Gary J.; Desouza, Nandita M.; Dickson, John C.; Dive, Caroline; Evelhoch, Jeffrey L.; Faivre-Finn, Corinne; Gallagher, Ferdia A.; Gilbert, Fiona J.; Gillies, Robert J.; Goh, Vicky; Griffiths, J. R.; Groves, Ashley M.; Halligan, Steve; Harris, Adrian L.; Hawkes, David J.; Hoekstra, Otto S.; Huang, Erich P.; Hutton, Brian F.; Jackson, Edward F.; Jayson, Gordon C.; Jones, Andrew; Koh, Dow-Mu; Lacombe, Denis; Lambin, Philippe; Lassau, Nathalie; Leach, Martin O.; Lee, Ting-Yim; Leen, Edward L.; Lewis, Jason S.; Liu, Yan; Lythgoe, Mark F.; Manoharan, Prakash; Maxwell, Ross J.; Miles, Kenneth A.; Morgan, Bruno; Morris, Steve; Ng, Tony; Padhani, Anwar R.; Parker, Geoff J. M.; Partridge, Mike; Pathak, Arvind P.; Peet, Andrew C.; Punwani, Shonit; Reynolds, Andrew R.; Robinson, Simon P.; Shankar, Lalitha K.; Sharma, Ricky A.; Soloviev, Dmitry; Stroobants, Sigrid G.; Sullivan, Daniel C.; Taylor, Stuart A.; Tofts, Paul S.; Tozer, Gillian M.; van Herk, Marcel B.; Walker-Samuel, Simon; Wason, James; Williams, Kaye J.; Workman, Paul; Yankeelov, Thomas E.; Brindle, Kevin M.; McShane, Lisa M.; Jackson, Alan; Waterton, John C.

    Imaging biomarkers (IBs) are integral to the routine management of patients with cancer. IBs used daily in oncology include clinical TNM stage, objective response and left ventricular ejection fraction. Other CT, MRI, PET and ultrasonography biomarkers are used extensively in cancer research and

  6. Study of scattering in bi-dimensional neutron radiographic images

    International Nuclear Information System (INIS)

    Oliveira, K.A.M. de; Crispim, V.R.; Silva, F.C.

    2009-01-01

    The effect of neutron scattering frequently causes distortions in neutron radiographic images and, thus, reduces the quality. In this project, a type of filter, comprised of cadmium (a neutron absorber), was used in the form of a grid to correct this effect. This device generated image data in the discrete shadow bands of the absorber, components relative to neutron scattering on the test object and surroundings. Scattering image data processing, together with the original neutron radiographic image, resulted in a corrected image with improved edge delineation and, thus, greater definition in the neutron radiographic image of the test object. The objective of this study is to propose a theoretical/experimental methodology that is capable of eliminating the components relative to neutron scattering in neutron radiographic images, coming from the material that composes the test object and the materials that compose the surrounding area. (author)

  7. Comparative study of ultrasound imaging, computed tomography and magnetic resonance imaging in gynecology

    International Nuclear Information System (INIS)

    Ishii, Kenji; Kobayashi, Hisaaki; Hoshihara, Takayuki; Kobayashi, Mitsunao; Suda, Yoshio; Takenaka, Eiichi; Sasa, Hidenori.

    1989-01-01

    We studied 18 patients who were operated at the National Defense Medical College Hospital and confirmed by pathological diagnosis. We compared ultrasound imaging, computed tomography (CT) and magnetic resonance imaging (MRI) of the patients. MRI was useful to diagnose enlargement of the uterine cavity and a small amount of ascites and to understand orientation of the pelvic organs. Ultrasound imaging is the most useful examination to diagnose gynecological diseases. But when it is difficult to diagnose by ultrasound imaging alone, we should employ either CT or MRI, or preferably both. (author)

  8. Study of TCP densification via image analysis

    International Nuclear Information System (INIS)

    Silva, R.C.; Alencastro, F.S.; Oliveira, R.N.; Soares, G.A.

    2011-01-01

    Among ceramic materials that mimic human bone, β-type tri-calcium phosphate (β-TCP) has shown appropriate chemical stability and superior resorption rate when compared to hydroxyapatite. In order to increase its mechanical strength, the material is sintered, under controlled time and temperature conditions, to obtain densification without phase change. In the present work, tablets were produced via uniaxial compression and then sintered at 1150°C for 2h. The analysis via XRD and FTIR showed that the sintered tablets were composed only by β-TCP. The SEM images were used for quantification of grain size and volume fraction of pores, via digital image analysis. The tablets showed small pore fraction (between 0,67% and 6,38%) and homogeneous grain size distribution (∼2μm). Therefore, the analysis method seems viable to quantify porosity and grain size. (author)

  9. Clinical findings versus imaging studies in the diagnosis of infantile ...

    African Journals Online (AJOL)

    Background: Infantile hypertrophic pyloric stenosis is the most common surgical cause of vomiting in early infancy and can be diagnosed clinically or by imaging studies. Objectives: The aim of this study was to assess the accuracy of clinical examination compared with ultrasound and upper gastrointestinal contrast imaging ...

  10. An Exploratory Study of Residents’ Perception of Place Image

    Science.gov (United States)

    Stylidis, Dimitrios; Sit, Jason; Biran, Avital

    2014-01-01

    Studies on place image have predominantly focused on the tourists’ destination image and have given limited attention to other stakeholders’ perspectives. This study aims to address this gap by focusing on the notion of residents’ place image, whereby it reviews existing literature on residents’ place image in terms of whether common attributes can be identified, and examines the role of community-focused attributes in its measurement. Data collected from a sample of 481 Kavala residents (Greece) were subjected to exploratory and confirmatory factor analysis. The study reveals that the existing measurement tools have typically emphasized destination-focused attributes and neglected community-focused attributes. This study contributes to the residents’ place image research by proposing a more holistic measurement, which consisted of four dimensions: physical appearance, community services, social environment, and entertainment opportunities. The study also offers practical insights for developing and promoting a tourist place while simultaneously enhancing its residents’ quality of life. PMID:29708109

  11. A Cognitive Semiotic Study of Students' Reading a Textless Image versus a Verbal Image

    Directory of Open Access Journals (Sweden)

    Roaa Hasan Ali

    2016-10-01

    Full Text Available This study explores fourth year college students'   content   retrieval from reading textless versus verbal images. Furthermore, it examines  the extent to which the respondents comprehend and understand them .The procedures include selecting an image from the internet, designing a written test with its rubrics and exposing it to jury members to ascertain its face validity. The data of this study were analyzed according to the adopted of Peirce's model (1931 of ' icon, index and symbol'. The researchers find out that most of the results were in favor of the verbal images, captions restrict readers' creativity to infer any additional message. Keywords: Content retrieval, Textless images, Verbal images

  12. Image-Processing Scheme to Detect Superficial Fungal Infections of the Skin

    Directory of Open Access Journals (Sweden)

    Ulf Mäder

    2015-01-01

    Full Text Available The incidence of superficial fungal infections is assumed to be 20 to 25% of the global human population. Fluorescence microscopy of extracted skin samples is frequently used for a swift assessment of infections. To support the dermatologist, an image-analysis scheme has been developed that evaluates digital microscopic images to detect fungal hyphae. The aim of the study was to increase diagnostic quality and to shorten the time-to-diagnosis. The analysis, consisting of preprocessing, segmentation, parameterization, and classification of identified structures, was performed on digital microscopic images. A test dataset of hyphae and false-positive objects was created to evaluate the algorithm. Additionally, the performance for real clinical images was investigated using 415 images. The results show that the sensitivity for hyphae is 94% and 89% for singular and clustered hyphae, respectively. The mean exclusion rate is 91% for the false-positive objects. The sensitivity for clinical images was 83% and the specificity was 79%. Although the performance is lower for the clinical images than for the test dataset, a reliable and fast diagnosis can be achieved since it is not crucial to detect every hypha to conclude that a sample consisting of several images is infected. The proposed analysis therefore enables a high diagnostic quality and a fast sample assessment to be achieved.

  13. Challenges in clinical studies with multiple imaging probes

    International Nuclear Information System (INIS)

    Krohn, Kenneth A.; O'Sullivan, Finbarr; Crowley, John; Eary, Janet F.; Linden, Hannah M.; Link, Jeanne M.; Mankoff, David A.; Muzi, Mark; Rajendran, Joseph G.; Spence, Alexander M.; Swanson, Kristin R.

    2007-01-01

    This article addresses two related issues: (a) When a new imaging agent is proposed, how does the imager integrate it with other biomarkers, either sampled or imaged? (b) When we have multiple imaging agents, is the information additive or duplicative and how is this objectively determined? Molecular biology is leading to new treatment options with reduced normal tissue toxicity, and imaging should have a role in objectively evaluating new treatments. There are two roles for molecular characterization of disease. Molecular imaging measurements before therapy help predict the aggressiveness of disease and identify therapeutic targets and, therefore, help choose the optimal therapy for an individual. Measurements of specific biochemical processes made during or after therapy should be sensitive measures of tumor response. The rules of evidence are not fully developed for the prognostic role of imaging biomarkers, but the potential of molecular imaging provides compelling motivation to push forward with convincing validation studies. New imaging procedures need to be characterized for their effectiveness under realistic clinical conditions to improve the management of patients and achieve a better outcome. The purpose of this article is to promote a critical discussion within the molecular imaging community because our future value to the overall biomedical community will be in supporting better treatment outcomes rather than in detection

  14. Fluorescence Imaging Study of Impinging Underexpanded Jets

    Science.gov (United States)

    Inman, Jennifer A.; Danehy, Paul M.; Nowak, Robert J.; Alderfer, David W.

    2008-01-01

    An experiment was designed to create a simplified simulation of the flow through a hole in the surface of a hypersonic aerospace vehicle and the subsequent impingement of the flow on internal structures. In addition to planar laser-induced fluorescence (PLIF) flow visualization, pressure measurements were recorded on the surface of an impingement target. The PLIF images themselves provide quantitative spatial information about structure of the impinging jets. The images also help in the interpretation of impingement surface pressure profiles by highlighting the flow structures corresponding to distinctive features of these pressure profiles. The shape of the pressure distribution along the impingement surface was found to be double-peaked in cases with a sufficiently high jet-exit-to-ambient pressure ratio so as to have a Mach disk, as well as in cases where a flow feature called a recirculation bubble formed at the impingement surface. The formation of a recirculation bubble was in turn found to depend very sensitively upon the jet-exit-to-ambient pressure ratio. The pressure measured at the surface was typically less than half the nozzle plenum pressure at low jet pressure ratios and decreased with increasing jet pressure ratios. Angled impingement cases showed that impingement at a 60deg angle resulted in up to a factor of three increase in maximum pressure at the plate compared to normal incidence.

  15. Performance study of double SOI image sensors

    Science.gov (United States)

    Miyoshi, T.; Arai, Y.; Fujita, Y.; Hamasaki, R.; Hara, K.; Ikegami, Y.; Kurachi, I.; Nishimura, R.; Ono, S.; Tauchi, K.; Tsuboyama, T.; Yamada, M.

    2018-02-01

    Double silicon-on-insulator (DSOI) sensors composed of two thin silicon layers and one thick silicon layer have been developed since 2011. The thick substrate consists of high resistivity silicon with p-n junctions while the thin layers are used as SOI-CMOS circuitry and as shielding to reduce the back-gate effect and crosstalk between the sensor and the circuitry. In 2014, a high-resolution integration-type pixel sensor, INTPIX8, was developed based on the DSOI concept. This device is fabricated using a Czochralski p-type (Cz-p) substrate in contrast to a single SOI (SSOI) device having a single thin silicon layer and a Float Zone p-type (FZ-p) substrate. In the present work, X-ray spectra of both DSOI and SSOI sensors were obtained using an Am-241 radiation source at four gain settings. The gain of the DSOI sensor was found to be approximately three times that of the SSOI device because the coupling capacitance is reduced by the DSOI structure. An X-ray imaging demonstration was also performed and high spatial resolution X-ray images were obtained.

  16. MR imaging studies of multiple myeloma in the vertebral column

    International Nuclear Information System (INIS)

    Albert, S.; Leeds, N.E.

    1990-01-01

    This paper studies the sensitivity and characteristics of MR imaging in the diagnosis of myeloma in the vertebral column. The cervical, thoracic, and lumbar spines of 12 patients with known multiple myeloma were imaged with small flip angle, fast gradient-echo, proton-density (FPD) as well as spin-echo T1-weighted, T2-weighted, and intermediate (SE 2,000/20-30) imaging. The FPD images were acquired with pulse sequence gradient recalled acquisition in a steady state at a magnetic field strength of 1.5T with use of a license-plate and a circular surface coil

  17. Study on edge-extraction of remote sensing image

    International Nuclear Information System (INIS)

    Wen Jianguang; Xiao Qing; Xu Huiping

    2005-01-01

    Image edge-extraction is an important step in image processing and recognition, and also a hot spot in science study. In this paper, based on primary methods of the remote sensing image edge-extraction, authors, for the first time, have proposed several elements which should be considered before processing. Then, the qualities of several methods in remote sensing image edge-extraction are systematically summarized. At last, taking Near Nasca area (Peru) as an example the edge-extraction of Magmatic Range is analysed. (authors)

  18. Muscle magnetic resonance imaging sensitivity does not decrease in chronic, mild, or proximal lower limb neuropathies.

    Science.gov (United States)

    Deroide, Nicolas; Bousson, Valérie; Daguet, Edouard; Dumurgier, Julien; Tin, Sophie Ng Wing; Hannouche, Didier; Richette, Pascal; Beaudreuil, Johann; Lioté, Frédéric; Lévy, Bernard; Vicaut, Eric; Laredo, Jean Denis; Kubis, Nathalie

    2012-05-01

    Muscle magnetic resonance imaging (MRI) is an innovative tool for exploring focal neuropathies. However, its usefulness in mild, proximal, or chronic lesions, when electromyography (EMG), the current "gold standard" sensitivity is inadequate, has yet to be studied. Clinical, MRI, and EMG examinations were performed in 113 muscles of 17 consecutive patients with clinically diagnosed lower limb focal neuropathies. The sensitivity and specificity of MRI and EMG were evaluated in relation to disease duration, severity, and anatomical location. Muscle MRI was highly sensitive for the detection of denervated muscle, and, unlike EMG, its sensitivity did not decrease regardless of the anatomical location, duration, or severity of the neuropathy. Five MRI false positives were noted, including three in the thigh muscles. Muscle MRI is an alternative tool to EMG in proximal, mild, or chronic clinical diagnoses of lower limb focal neuropathies. However, it also seems prone to false-positive results, particularly in proximal muscles. Copyright © 2012 Wiley Periodicals, Inc.

  19. A study of spinal cord tumors by magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Gushiken, Isao; Nishihira, Takeshi; Nakasone, Tomohiro [Ryukyu Univ., Nishihara, Okinawa (Japan). School of Medicine; Takara, Hiroaki; Oshiro, Yutaka; Oshiro, Takashi; Isa, Makoto; Kinjo, Yukio; Ibaraki, Kunio

    1989-10-01

    We studied 17 cases of spinal cord tumors using magnetic resonance imaging. According to the intensity of image and histological feature of spinal cord tumors, we identified two groups in T2 weighted imaging. One was a hypointensity group showing cystic or vascular tumors, and the other was hyperintensity group of solid tumors. Preoperative images of swelling, narrowing, deviation of the spinal cord were remained after the operations. Grafted free fatty tissue for the prevention of adhesion was recognized well also after the operation. Postoperative imagings sometime showed pseudo-deviation of the spinal cord which was easy to be mistaken as the remains of tumors and narrowing of the spinal cord. In conclusion, the magnetic resonance imaging makes very early detection of spinal cord tumors possible, and it is valuable for a diagnosis of the spinal cord tumor associated with brain tumor. (author).

  20. SP-ECT imaging and its physical study

    International Nuclear Information System (INIS)

    Kinoshita, Fujimi

    1983-01-01

    Recently, more than a hundred hospitals are provided with SPECT system for clinical examination in Japan. However, a standardization of measuring method and performance test of the systems is ont yet made. We have been studying some basic problems of SPECT system with special phantoms originaly designed by ourselves. We got a conclusion that a standardized phantom is necessary for comparing performances between SPECT systems. In clinical experiences with 3,332 cases, we think that SPECT image combined with conventional image presents much more informations for accurate diagnosis, especially in brain, bone and tumor imagings. Synthesized image of SPECT and XCT, double tracer image and transmission image are useful to visualize the body contour and the clinical diagnosis. (author)

  1. A study of spinal cord tumors by magnetic resonance imaging

    International Nuclear Information System (INIS)

    Gushiken, Isao; Nishihira, Takeshi; Nakasone, Tomohiro; Takara, Hiroaki; Oshiro, Yutaka; Oshiro, Takashi; Isa, Makoto; Kinjo, Yukio; Ibaraki, Kunio.

    1989-01-01

    We studied 17 cases of spinal cord tumors using magnetic resonance imaging. According to the intensity of image and histological feature of spinal cord tumors, we identified two groups in T2 weighted imaging. One was a hypointensity group showing cystic or vascular tumors, and the other was hyperintensity group of solid tumors. Preoperative images of swelling, narrowing, deviation of the spinal cord were remained after the operations. Grafted free fatty tissue for the prevention of adhesion was recognized well also after the operation. Postoperative imagings sometime showed pseudo-deviation of the spinal cord which was easy to be mistaken as the remains of tumors and narrowing of the spinal cord. In conclusion, the magnetic resonance imaging makes very early detection of spinal cord tumors possible, and it is valuable for a diagnosis of the spinal cord tumor associated with brain tumor. (author)

  2. Comparative imaging study on monkeys with hemi-parkinsonism

    International Nuclear Information System (INIS)

    Wang Wei; Yu Xiaoping; Mao Jun; Liu Sheng; Wang Xiaoyi; Peng Guangchun; Wang Ruiwen

    2003-01-01

    Objective: To study the imaging appearance of experimental Parkinson's disease (PD) and to evaluate the different medical imaging exams on PD. Methods: CT, MRI, SPECT (dopamine transporter imaging and regional cerebral blood flow imaging, DAT imaging and rCBF imaging), and PET (glucose metabolism imaging) were performed on 8 monkeys before and after the infusion of MPTP into unilateral internal carotid artery to develop hemi-Parkinsonism models. Results: Hemi-Parkinsonism models were successfully induced on all 8 monkeys. On DAT imaging, the uptake values of the lesioned striatums decreased obviously after the MPTP treatment and were lower than that of the contralateral ones. The glucose metabolic rates of the lesioned striatums and thalamus in PD models were lower, compared to that of the healthy monkeys and that of the contralateral sides of themselves. Neither DAT nor glucose metabolism abnormalities was found on both the contralateral sides of the healthy and PD monkeys. On MRI images before MPTP treatment, only 4 of 8 PD models showed hypointense in bilateral globus pallidus. No abnormal MRI findings occurred in the first 2 months after injection of MPTP. At tile third month, hypointense appeared in globus pallidus of three monkeys. Enlarged hyposignal region in globus pallidus were found in three models. Of the above 6 monkeys, two appeared hypointense in putamina. Substantia nigra demonstrated no abnormalities before and after MPTP treatment. All rCBF and CT images were normal. Conclusion: The decreased density of DAT and decreased glucose metabolism on experimental PD can be showed early by DAT imaging and glucose metabolism imaging, MRI can show abnormal signal in the basal ganglia of PD but it is later than DAT and glucose metabolism imaging. CT and rCBF find no abnormality on PD

  3. FAIR imaging of the liver. A preliminary study

    International Nuclear Information System (INIS)

    Kiryu, Shigeru; Machida, Toru; Noda, Masanobu

    1998-01-01

    Flow-sensitive alternating inversion recovery (FAIR) technique has recently been introduced for perfusion or functional MR studies of the brain. In the imaging of liver neoplasms, the evaluation of tumor vascularity is important for diagnosis, and therefore the FAIR technique may potentially complement liver MR imaging. The purpose of this study was to evaluate the usefulness of a FAIR sequence in MR imaging of the liver and to compare it with arterial-phase images of dynamic MR imaging. One volunteer and six patients with focal hepatic lesions (one with hepatocellular carcinoma (HCC), three with metastasis, and two with cavernous hemangioma) underwent FAIR. Short TI (600 ms) and long TI (1200 ms) images were obtained during breath-hold. In normal volunteers, the vessels generated remarkably bright signal in both short and long TI. Signal intensity of liver parenchyma was low in short TI, and became stronger in long TI. Two HCC (in one patient) (100%), one hemangioma (50%), and three metastases (100%) were well delineated as bright lesions. One HCC produced peripheral high intensity in short-TI FAIR image, and this finding was consistent with the result of dynamic MR study. Another HCC, which showed no clear enhancement in the arterial-phase dynamic MRI, was visualized only in long-TI FAIR. One hemangioma, which was clearly seen in FAIR image, showed rapid and strong enhancement on dynamic MRI. It is concluded that FAIR is a promising technique for evaluation of vascularity of hepatic tumors without using contrast materials. (author)

  4. Usefulness of breast-specific gamma imaging as an adjunct modality in breast cancer patients with dense breast. A comparative study with MRI

    International Nuclear Information System (INIS)

    Kim, Bom Sahn

    2012-01-01

    The aim of this study was to evaluate the adjunctive benefits of breast-specific gamma imaging (BSGI) versus magnetic resonance imaging (MRI) in breast cancer patients with dense breasts. This study included a total of 66 patients (44.1±8.2 years) with dense breasts (breast density >50%) and already biopsy-confirmed breast cancer. All of the patients underwent BSGI and MRI as part of an adjunct modality before the initial therapy. Of 66 patients, the 97 undetermined breast lesions were newly detected and correlated with the biopsy results. Twenty-six of the 97 breast lesions proved to be malignant tumors (invasive ductal cancer, n=16; ductal carcinoma in situ, n=6; mixed or other malignancies, n=4); the remaining 71 lesions were diagnosed as benign tumors. The sensitivity and specificity of BSGI were 88.8% (confidence interval (CI), 69.8-97.6%) and 90.1% (CI, 80.7-95.9%), respectively, while the sensitivity and specificity of MRI were 92.3% (CI, 74.9-99.1%) and 39.4% (CI, 28.0-51.7%), respectively (p<0.0001). MRI detected 43 false-positive breast lesions, 37 (86.0%) of which were correctly diagnosed as benign lesions using BSGI. In 12 malignant lesions <1 cm, the sensitivities of BSGI and MR imaging were 83.3% (CI, 51.6-97.9%) and 91.7% (CI, 61.5-99.8%), respectively. BSGI showed an equivocal sensitivity and a high specificity compared to MRI in the diagnosis of breast lesions. In addition, BSGI had a good sensitivity in discriminating breast cancers ≤1 cm. The results of this study suggest that BSGI could play a crucial role as an adjunctive imaging modality which can be used to evaluate breast cancer patients with dense breasts. (author)

  5. Phantom studies on the artifacts of barium on 18F-FDG DHC/CT images induced by X-ray attenuation correction

    International Nuclear Information System (INIS)

    Wang Wei; Zhu Jiarui; Wang Xinqiang; Zhao Wenrui; Chuan Ling; Xu Genxiang; Gao Chunhua; Fang Tingzheng

    2007-01-01

    Objective: Attenuation correction (AC) based on X-ray transmission map may result in false positive readings or artifacts on PET images, some of them due to the internal residue of high density contrast media used in diagnostic X-ray imaging. The aim of this study was to experimentally estimate the impacts of different concentrations and volumes of barium contrast on X-CT AC (CTAC) for dual-head coincidence (DHC/CT) images. Methods: A cylindrical phantom containing 18 F solution (3.7 kBq/ml), in which plastic fingertips enclosed with different concentrations (0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 1.0, 2.0, 3.0 kg/L)and volumes(0.5, 1.0, 1.5, 2.0, 2.5 ml) of BaSO 4 contrast media were inserted, was used to modulate routine 18 F-fluorodeoxyglucose (FDG) imaging study on a DHC/CT scanner (GE Discovery VH). Sequential 18 F emission and X-CT transmission acquisitions followed by data processing and reconstruction were carried out in clinical settings. For comparison, both visual and quantitative analyses were performed on CTAC and non-AC (NAC) images of the phantom. Results: In NAC images, the radioactivity distribution within the whole phantom was non-uniform with lower counts in the center; the plastic fingertips were all seen as 'cold spots' with much lower counts in the contrast region than in their surrounding areas. On the contrary, in CTAC images, the radioactivity distribution within the whole phantom was almost uniform; while most plastic fingertips with media concentration ≥0.1 kg/L and volume >0.5 ml were all depicted as 'hot spots' with higher counts than in surrounding areas. Conclusions: Barium contrast with relative high concentration or large volume can induce artifacts on CTAC DHC/CT images. In clinical setting, proper interpretation of CTAC DHC/CT images should refer to NAC DHC/CT images to exclude any artifacts related to the contrast media residues. (authors)

  6. Can imaging criteria distinguish enchondroma from grade 1 chondrosarcoma?

    Science.gov (United States)

    Crim, Julia; Schmidt, Robert; Layfield, Lester; Hanrahan, Christopher; Manaster, Betty Jean

    2015-11-01

    To minimize systematic bias and optimize agreement on imaging criteria in order to better define the accuracy of imaging criteria in the diagnosis of grade 1 chondrosarcoma. Study was IRB-approved and HIPAA compliant; informed consent was waived. Records were reviewed and disclosed 53 cases (38 women, 15 men ages 21-76) which were diagnosed as enchondroma or grade 1 chondrosarcoma and had available radiographs, contrast-enhanced MRI, and definitive diagnosis by histology or 5-year follow-up. 2 MSK radiologists read the studies independently after a session where they agreed on criteria for malignancy. Interobserver variability was determined as raw variability and with the kappa statistic. Accuracy was determined compared to final diagnosis. Reliability of imaging features of chondrosarcoma was determined using regression analysis. The correct diagnosis of enchondroma was made on radiographs in 43 (67.2%) of readings, and on MRI in 37/64 (57.8%). The correct diagnosis of chondrosarcoma was made on radiographs in 5/24 (20.8%) of readings, and on MRI in 14/24 (57.8%). A diagnosis of borderline lesion was made in 19/64 (29.7%) of enchondromas on radiographs and 18/64 (28.1%) on MRI. The false positive rate of radiographs for chondrosarcoma was 2/64 (3.1%) and the false positive rate of MRI was 9/64 (14.1%). There was substantial interobserver variability. Cortical thickening and bone expansion were rare but specific signs of chondrosarcoma. Both radiographs and MRI have limitations in the evaluation of low-grade cartilage lesions. MRI has an increased rate of both true-positive and false-positive diagnosis compared to radiographs. Differences in the findings of this study compared to previous literature may reflect the influence of systematic biases. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  7. Musculoskeletal Imaging Findings of Hematologic Malignancies.

    Science.gov (United States)

    Navarro, Shannon M; Matcuk, George R; Patel, Dakshesh B; Skalski, Matthew; White, Eric A; Tomasian, Anderanik; Schein, Aaron J

    2017-01-01

    Hematologic malignancies comprise a set of prevalent yet clinically diverse diseases that can affect every organ system. Because blood components originate in bone marrow, it is no surprise that bone marrow is a common location for both primary and metastatic hematologic neoplasms. Findings of hematologic malignancy can be seen with most imaging modalities including radiography, computed tomography (CT), technetium 99m ( 99m Tc) methylene diphosphonate (MDP) bone scanning, fluorine 18 ( 18 F) fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT, and magnetic resonance (MR) imaging. Because of the diversity of imaging appearances and clinical behavior of this spectrum of disease, diagnosis can be challenging, and profound understanding of the underlying pathophysiologic changes and current treatment modalities can be daunting. The appearance of normal bone marrow at MR imaging and FDG PET/CT is also varied due to dynamic compositional changes with normal aging and in response to hematologic demand or treatment, which can lead to false-positive interpretation of imaging studies. In this article, the authors review the normal maturation and imaging appearance of bone marrow. Focusing on lymphoma, leukemia, and multiple myeloma, they present the spectrum of imaging findings of hematologic malignancy affecting the musculoskeletal system and the current imaging tools available to the radiologist. They discuss the imaging findings of posttreatment bone marrow and review commonly used staging systems and consensus recommendations for appropriate imaging for staging, management, and assessment of clinical remission. © RSNA, 2017.

  8. Establishment of frame image in dynamic function renal studies

    International Nuclear Information System (INIS)

    Guedes, Germano P.; Brunetto, Sergio Q.

    1996-01-01

    Statistical procedures applied to a set of images of renal function study are described to define a region of interest (ROI) on the kidneys's contours. The kidneys geometry is considered to adapt to the emitting area in every frames

  9. An exploratory study of the relationship between store image, trust ...

    African Journals Online (AJOL)

    2011-08-26

    Aug 26, 2011 ... results, this study shows that compared to corporate-owned stores, ..... 'Exploring store image, customer satisfaction and customer ... strategy: Dimensions, antecedents, and performance outcomes', Journal of Marketing,.

  10. Functional MRI studies of human vision on a clinical imager

    International Nuclear Information System (INIS)

    George, J.S.; Lewine, J.D.; Aine, C.J.; van Hulsteyn, D.; Wood, C.C.; Sanders, J.; Maclin, E.; Belliveau, J.W.; Caprihan, A.

    1992-01-01

    During the past decade, Magnetic Resonance Imaging (MRI) has become the method of choice for imaging the anatomy of the human brain. Recently, Belliveau and colleagues have reported the use of echo planar magnetic resonance imaging (EPI) to image patterns of neural activity. Here, we report functional MR imaging in response to visual stimulation without the use of contrast agents, and without the extensive hardware modifications required for EPI. Regions of activity were observed near the expected locations of V1, V2 and possibly V3 and another active region was observed near the parietal-occipital sulcus on the superior surface of the cerebrum. These locations are consistent with sources observed in neuromagnetic studies of the human visual response

  11. A study on secondary images in panoramic radiograph

    International Nuclear Information System (INIS)

    Cho, Dai Hee; Kim, Han Pyong

    1984-01-01

    This study was performed to observe the secondary images and to analyse the relationships between the primary and secondary images in panoramic radiograph. Using the Morita's Panex-EC panoramic x-ray machine and the human dry skull, the author analysed 17 radiographs which were selected from 65 radiographs of the dry skull that attached the radiopaque materials, and the attached regions of the radiopaque materials were the normal anatomical structures which were important and selected as a region for the evaluation of the secondary images effectively. The results were as follows; 1. The cervical vertebrae showed three images. The midline image was the most distorted and less clear, and bilateral images were slightly superimposed over the posterior border of the mandibular ramus. 2. In mandible, the secondary image of the posterior border of the ramus was superimposed on the opposite ramus region, and this image was elongated from the anterior border of the ramus to the lateral side of the posterior border of the ramus. The secondary image of the condyle was observed on the upper area of the coronoid process, the sigmoid notch and the condyle in opposite side. 3. In maxilla, the posterior region of the hard palate showed the secondary image on the lower part of the nasal cavity and the medial wall of the maxillary sinus. 4. The primary images of the occipital condyle and the mastoid process appeared on the same region, and only the secondary image of the occipital condyle was observed symmetrically on the opposite side with similar shape to the primary one. 5. In the cranial base, the anatomical structures of the midsagittal portions like a inferior border of the frontal sinus, sella turcica, inferior border of the sphenoid sinus and inferior border of the posterior part of the occipital bone showed the similar shape between the primary and secondary images symmetrically. 6. The petrous portion of the temporal bone showed the secondary image of the lateral side of

  12. Software Image J to study soil pore distribution

    Directory of Open Access Journals (Sweden)

    Sabrina Passoni

    2014-04-01

    Full Text Available In the soil science, a direct method that allows the study of soil pore distribution is the bi-dimensional (2D digital image analysis. Such technique provides quantitative results of soil pore shape, number and size. The use of specific softwares for the treatment and processing of images allows a fast and efficient method to quantify the soil porous system. However, due to the high cost of commercial softwares, public ones can be an interesting alternative for soil structure analysis. The objective of this work was to evaluate the quality of data provided by the Image J software (public domain used to characterize the voids of two soils, characterized as Geric Ferralsol and Rhodic Ferralsol, from the southeast region of Brazil. The pore distribution analysis technique from impregnated soil blocks was utilized for this purpose. The 2D image acquisition was carried out by using a CCD camera coupled to a conventional optical microscope. After acquisition and treatment of images, they were processed and analyzed by the software Noesis Visilog 5.4® (chosen as the reference program and ImageJ. The parameters chosen to characterize the soil voids were: shape, number and pore size distribution. For both soils, the results obtained for the image total porosity (%, the total number of pores and the pore size distribution showed that the Image J is a suitable software to be applied in the characterization of the soil sample voids impregnated with resin.

  13. Fluorescence Imaging Study of Transition in Underexpanded Free Jets

    Science.gov (United States)

    Wilkes, Jennifer A.; Danehy, Paul M.; Nowak, Robert J.

    2005-01-01

    Planar laser-induced fluorescence (PLIF) is demonstrated to be a valuable tool for studying the onset of transition to turbulence. For this study, we have used PLIF of nitric oxide (NO) to image underexpanded axisymmetric free jets issuing into a low-pressure chamber through a smooth converging nozzle with a sonic orifice. Flows were studied over a range of Reynolds numbers and nozzle-exit-to-ambient pressure ratios with the aim of empirically determining criteria governing the onset of turbulence. We have developed an image processing technique, involving calculation of the standard deviation of the intensity in PLIF images, in order to aid in the identification of turbulence. We have used the resulting images to identify laminar, transitional and turbulent flow regimes. Jet scaling parameters were used to define a rescaled Reynolds number that incorporates the influence of a varying pressure ratio. An empirical correlation was found between transition length and this rescaled Reynolds number for highly underexpanded jets.

  14. Study of fish response using particle image velocimetry and high-speed, high-resolution imaging

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Z. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Richmond, M. C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Mueller, R. P. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Gruensch, G. R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2004-10-01

    Fish swimming has fascinated both engineers and fish biologists for decades. Digital particle image velocimetry (DPIV) and high-speed, high-resolution digital imaging are recently developed analysis tools that can help engineers and biologists better understand how fish respond to turbulent environments. This report details studies to evaluate DPIV. The studies included a review of existing literature on DPIV, preliminary studies to test the feasibility of using DPIV conducted at our Flow Biology Laboratory in Richland, Washington September through December 2003, and applications of high-speed, high-resolution digital imaging with advanced motion analysis to investigations of fish injury mechanisms in turbulent shear flows and bead trajectories in laboratory physical models. Several conclusions were drawn based on these studies, which are summarized as recommendations for proposed research at the end of this report.

  15. Diagnostic performance of MR imaging in the assessment of subchondral fractures in avascular necrosis of the femoral head

    Energy Technology Data Exchange (ETDEWEB)

    Yeh, Lee-Ren [E-Da Hospital and I-Shou University, Department of Radiology, Kaohsiung County (China); Chen, Clement K.H.; Pan, Huay-Ben; Yang, Chien-Fang [Kaohsiung Veterans General Hospital, Department of Radiology, Kaohsiung (China); National Yang-Ming University, School of Medicine, Taipei (China); Huang, Yi-Luan [Kaohsiung Veterans General Hospital, Department of Radiology, Kaohsiung (China)

    2009-06-15

    A prospective study was conducted to determine the accuracy of routine magnetic resonance (MR) imaging in correctly identifying subchondral fracture in avascular necrosis of the femoral head without apparent focal collapse on standard radiographs. Spiral computed tomography (CT) with coronal and sagittal reformations and routine MR imaging with spin-echo T1WI and fat-suppressed spin-echo T2WI coronal, axial, and sagittal images were performed in 28 hips of 25 patients (M/F = 20:5; age 16-76 years) suffering from early-stage avascular necrosis of the femoral head on standard radiographs. The MR images were reviewed by a musculoskeletal radiologist and a general radiologist in blinded fashion. Using CT as the standard of reference, the accuracy of MR imaging in diagnosing subchondral fractures in avascular necrosis was evaluated. When the diagnoses of the two readers were compared with each other, only 16 of the 28 diagnoses (57.5%) agreed. Seventeen of the 28 MR imaging readings (60.7%) made by the musculoskeletal radiologist and 15 of the 28 (53.5%) made by the general radiologist agreed with those of the CT standard. False-positive diagnosis (that is, diagnosis of fracture when no fracture could be seen on CT) was more common than false-negative diagnosis. The accuracy of routine MR imaging in the evaluation of subchondral fracture is not satisfactory. False-positive diagnosis is not uncommon. Interpretation of routine MR imaging readout should be guarded. (orig.)

  16. Diagnostic performance of MR imaging in the assessment of subchondral fractures in avascular necrosis of the femoral head

    International Nuclear Information System (INIS)

    Yeh, Lee-Ren; Chen, Clement K.H.; Pan, Huay-Ben; Yang, Chien-Fang; Huang, Yi-Luan

    2009-01-01

    A prospective study was conducted to determine the accuracy of routine magnetic resonance (MR) imaging in correctly identifying subchondral fracture in avascular necrosis of the femoral head without apparent focal collapse on standard radiographs. Spiral computed tomography (CT) with coronal and sagittal reformations and routine MR imaging with spin-echo T1WI and fat-suppressed spin-echo T2WI coronal, axial, and sagittal images were performed in 28 hips of 25 patients (M/F = 20:5; age 16-76 years) suffering from early-stage avascular necrosis of the femoral head on standard radiographs. The MR images were reviewed by a musculoskeletal radiologist and a general radiologist in blinded fashion. Using CT as the standard of reference, the accuracy of MR imaging in diagnosing subchondral fractures in avascular necrosis was evaluated. When the diagnoses of the two readers were compared with each other, only 16 of the 28 diagnoses (57.5%) agreed. Seventeen of the 28 MR imaging readings (60.7%) made by the musculoskeletal radiologist and 15 of the 28 (53.5%) made by the general radiologist agreed with those of the CT standard. False-positive diagnosis (that is, diagnosis of fracture when no fracture could be seen on CT) was more common than false-negative diagnosis. The accuracy of routine MR imaging in the evaluation of subchondral fracture is not satisfactory. False-positive diagnosis is not uncommon. Interpretation of routine MR imaging readout should be guarded. (orig.)

  17. A Study on the Improvement of Digital Periapical Images using Image Interpolation Methods

    International Nuclear Information System (INIS)

    Song, Nam Kyu; Koh, Kwang Joon

    1998-01-01

    Image resampling is of particular interest in digital radiology. When resampling an image to a new set of coordinate, there appears blocking artifacts and image changes. To enhance image quality, interpolation algorithms have been used. Resampling is used to increase the number of points in an image to improve its appearance for display. The process of interpolation is fitting a continuous function to the discrete points in the digital image. The purpose of this study was to determine the effects of the seven interpolation functions when image resampling in digital periapical images. The images were obtained by Digora, CDR and scanning of Ektaspeed plus periapical radiograms on the dry skull and human subject. The subjects were exposed to intraoral X-ray machine at 60 kVp and 70 kVp with exposure time varying between 0.01 and 0.50 second. To determine which interpolation method would provide the better image, seven functions were compared ; (1) nearest neighbor (2) linear (3) non-linear (4) facet model (5) cubic convolution (6) cubic spline (7) gray segment expansion. And resampled images were compared in terms of SNR (Signal to Noise Ratio) and MTF (Modulation Transfer Function) coefficient value. The obtained results were as follows ; 1. The highest SNR value (75.96 dB) was obtained with cubic convolution method and the lowest SNR value (72.44 dB) was obtained with facet model method among seven interpolation methods. 2. There were significant differences of SNR values among CDR, Digora and film scan (P 0.05). 4. There were significant differences of MTF coefficient values between linear interpolation method and the other six interpolation methods (P<0.05). 5. The speed of computation time was the fastest with nearest neighbor method and the slowest with non-linear method. 6. The better image was obtained with cubic convolution, cubic spline and gray segment method in ROC analysis. 7. The better sharpness of edge was obtained with gray segment expansion method

  18. Hand osteoarthritis: Clinical and imaging study

    African Journals Online (AJOL)

    Abir Naguib

    2011-09-09

    Sep 9, 2011 ... Methods: This study was carried out on thirty patients with primary hand OA, and fifteen healthy subjects .... history about their hand condition including morning stiffness, ..... They found the US method of direct visualiza-.

  19. Study of CT image texture using deep learning techniques

    Science.gov (United States)

    Dutta, Sandeep; Fan, Jiahua; Chevalier, David

    2018-03-01

    For CT imaging, reduction of radiation dose while improving or maintaining image quality (IQ) is currently a very active research and development topic. Iterative Reconstruction (IR) approaches have been suggested to be able to offer better IQ to dose ratio compared to the conventional Filtered Back Projection (FBP) reconstruction. However, it has been widely reported that often CT image texture from IR is different compared to that from FBP. Researchers have proposed different figure of metrics to quantitate the texture from different reconstruction methods. But there is still a lack of practical and robust method in the field for texture description. This work applied deep learning method for CT image texture study. Multiple dose scans of a 20cm diameter cylindrical water phantom was performed on Revolution CT scanner (GE Healthcare, Waukesha) and the images were reconstructed with FBP and four different IR reconstruction settings. The training images generated were randomly allotted (80:20) to a training and validation set. An independent test set of 256-512 images/class were collected with the same scan and reconstruction settings. Multiple deep learning (DL) networks with Convolution, RELU activation, max-pooling, fully-connected, global average pooling and softmax activation layers were investigated. Impact of different image patch size for training was investigated. Original pixel data as well as normalized image data were evaluated. DL models were reliably able to classify CT image texture with accuracy up to 99%. Results show that the deep learning techniques suggest that CT IR techniques may help lower the radiation dose compared to FBP.

  20. Studies of the body image in various psychological approaches

    Directory of Open Access Journals (Sweden)

    Natalia A. Kaminskaya

    2015-09-01

    Full Text Available The paper aims to systematize modern concepts of body image and body scheme. For the analysis of theoretical models the following criteria were allocated: explication of the mechanism underlying the formation and restructuring of body image, development of certain aspects of body image which are explained by the presented concepts. Separately the issue of the difference between the body scheme and the body image is discussed that seems relevant in connection with the specific features of the neural mechanisms of body image. In the study of the phenomenological level of bodily experience the assumption that the body scheme is fragmented and has no hierarchical structure is considered. Significant differences in viewing basic mechanisms of developing the body image associated with attention to various bodily phenomena are showed. Psychodynamic, cognitive, socio-cultural, feminist and interdisciplinary approaches are analyzed, which permitted to identify mechanisms of integration-differentiation, cognitive generalization and internalization-introjection. The analysis suggests the consideration of the body image in the context of issues on the appropriation of the body. If person is considered as a tool for shaping and maintening integration of mental processes, the patterns of interconnected and interdependent changes in the processes that occur in the construction of the image of the external situation and the body image acquires a special psychological meaning. It becomes necessary to allocate correctly the structure of the integrating object in which the subject is involved during the normal course of life, and in exceptional cases, i.e. in the presence of physical defects, the sudden change of appearance, etc. These development objects determine specific form of body image and its possible distortions.

  1. Fuel assembly assessment from CVD image analysis: A feasibility study

    International Nuclear Information System (INIS)

    Lindsay, C.S.; Lindblad, T.

    1997-05-01

    The Swedish Nuclear Inspectorate commissioned a feasibility study of automatic assessment of fuel assemblies from images obtained with the digital Cerenkov viewing device currently in development. The goal is to assist the IAEA inspectors in evaluating the fuel since they typically have only a few seconds to inspect an assembly. We report results here in two main areas: Investigation of basic image processing and recognition techniques needed to enhance the images and find the assembly in the image; Study of the properties of the distributions of light from the assemblies to determine whether they provide unique signatures for different burn-up and cooling times for real fuel or indicate presence of non-fuel. 8 refs, 27 figs

  2. Classified study and clinical value of the phase imaging features

    International Nuclear Information System (INIS)

    Dang Yaping; Ma Aiqun; Zheng Xiaopu; Yang Aimin; Xiao Jiang; Gao Xinyao

    2000-01-01

    445 patients with various heart diseases were examined by the gated cardiac blood pool imaging, and the phase was classified. The relationship between the seven types with left ventricular function index, clinical heart function, different heart diseases as well as electrocardiograph was studied. The results showed that the phase image classification could match with the clinical heart function. It can visually, directly and accurately indicate clinical heart function and can be used to identify diagnosis of heart disease

  3. Study of Brand Awareness and BrandImage of Starbucks

    OpenAIRE

    Rizwan, Muhammad; xian, Qin

    2008-01-01

    Abstract Date: September 1, 2008 Course: EFO705 Master Thesis International Marketing Tutor: Peter Dalin Authors: Muhammad Rizwan Qin Xian Title: Study of Brand Awareness and Brand Image of Starbucks Problem: To investigate to what extent the Swedish youths have brand awareness about the brand of Starbucks and what kind of brand perception of Starbucks as reflected by the brand association held in target customers’ memories (brand image). Purpos...

  4. A study of television imaging system for fast neutron radiography

    International Nuclear Information System (INIS)

    Yoshii, Koji

    1992-01-01

    The neutron radiography with fast neutron beam is a very useful imaging technique for thicker objects, especially those composed of hydrogen-rich materials which are sometimes difficult to image by thermal neutron radiography. The fast neutron radiography has not been studied so much as the thermal neutron radiography. The fast neutron radiography has been studied at the fast neutron source reactor 'Yayoi' of the University of Tokyo built in Tokai-mura. The average neutron energy of the Yayoi is about 1 MeV, and the peak neutron flux at the core center is 0.8 x 10 12 at the maximum operating power of 2 kW. In the experiment on fast neutron radiography, a CR39 nuclear track detector has been used successfully. But in the Yayoi radiography procedure, about 24 hours were required for obtaining an imaging result. To get a prompt imaging result and a real-time imaging result, it is necessary to develop a fast neutron television system, and in this paper, a new fast neutron TV system is proposed. The main difference is the converter material sensitive to fast neutrons. The study on the fast neutron TV system was carried out by using the Baby Cyclotron of Japan Steel Works, and the good images were realized. (K.I.)

  5. Feasibility study of CT perfusion imaging for prostate carcinoma

    International Nuclear Information System (INIS)

    Cullu, Nesat; Kantarci, Mecit; Ogul, Hayri; Pirimoglu, Berhan; Karaca, Leyla; Kizrak, Yesim; Adanur, Senol; Koc, Erdem; Polat, Ozkan; Okur, Aylin

    2014-01-01

    The aim of this feasibility study was to obtain initial data with which to assess the efficiency of perfusion CT imaging (CTpI) and to compare this with magnetic resonance imaging (MRI) in the diagnosis of prostate carcinoma. This prospective study involved 25 patients with prostate carcinoma undergoing MRI and CTpI. All analyses were performed on T2-weighted images (T2WI), apparent diffusion coefficient (ADC) maps, diffusion-weighted images (DWI) and CTp images. We compared the performance of T2WI combined with DWI and CTp alone. The study was approved by the local ethics committee, and written informed consent was obtained from all patients. Tumours were present in 87 areas according to the histopathological results. The diagnostic performance of the T2WI+DWI+CTpI combination was significantly better than that of T2WI alone for prostate carcinoma (P < 0.001). The diagnostic value of CTpI was similar to that of T2WI+DWI in combination. There were statistically significant differences in the blood flow and permeability surface values between prostate carcinoma and background prostate on CTp images. CTp may be a valuable tool for detecting prostate carcinoma and may be preferred in cases where MRI is contraindicated. If this technique is combined with T2WI and DWI, its diagnostic value is enhanced. (orig.)

  6. Multidisciplinary team review of best practices for collection and handling of blood cultures to determine effective interventions for increasing the yield of true-positive bacteremias, reducing contamination, and eliminating false-positive central line-associated bloodstream infections.

    Science.gov (United States)

    Garcia, Robert A; Spitzer, Eric D; Beaudry, Josephine; Beck, Cindy; Diblasi, Regina; Gilleeny-Blabac, Michelle; Haugaard, Carol; Heuschneider, Stacy; Kranz, Barbara P; McLean, Karen; Morales, Katherine L; Owens, Susan; Paciella, Mary E; Torregrosa, Edwin

    2015-11-01

    A literature search was conducted using keywords for articles published in English from January 1990 to March 2015. Using criteria related to blood culture collection and handling, the search yielded 101 articles. References used also included Microbiology Laboratory standards, guidelines, and textbook information. The literature identified diverse and complex issues surrounding blood culture practices, including the impact of false-positive results, laboratory definition of contamination, effect on central line-associated bloodstream infection (CLABSI) reporting, indications for collecting blood cultures, drawing from venipuncture sites versus intravascular catheters, selection of antiseptics, use of needleless connectors, inoculation of blood culture bottles, and optimizing program management in emergency departments, education, and implementation of bundled practice initiatives. Hospitals should optimize best practice in the collection, handling, and management of blood culture specimens, an often overlooked but essential component in providing optimal care of patients in all settings and populations, reducing financial burdens, and increasing the accuracy of reportable CLABSI. Although universal concepts exist in blood culture practices, some issues require further research to determine benefit. Institutions undertaking a review of their blood culture programs are encouraged to use a checklist that addresses elements that encompass the research contained in this review. Copyright © 2015 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

  7. 2-Hydroxyglutarate Detection by Short Echo Time Magnetic Resonance Spectroscopy in Routine Imaging Study of Brain Glioma at 3.0 T.

    Science.gov (United States)

    Crisi, Girolamo; Filice, Silvano; Michiara, Maria; Crafa, Pellegrino; Lana, Silvia

    The objective of this study was to assess the effective performance of short echo time magnetic resonance spectroscopy (short TE MRS) for 2HG detection as biomarker of isocitrate dehydrogenase (IDH) status in all grade glioma (GL). A total of 82 GL patients were prospectively investigated by short TE MRS at 3.0 T as part of a multimodal magnetic resonance imaging study protocol. Spectral analysis was performed using linear combination model. Tumor specimens were diagnosed as IDH mutant or wild type according to the 2016 World Health Organization (WHO) classification of brain tumors. Spectra were analyzed for the presence of 2HG. The performance of short TE MRS was evaluated in terms of sensitivity, specificity, and positive and negative likelihood ratio on the overall sample and on GL WHO grades II and III and glioblastoma separately. The specificity and sensitivity estimated on the overall sample were 88% and 77%, respectively. In GL WHO grades II and III, 100% specificity and 75% sensitivity were estimated. We reiterate the feasibility to identify IDH status of brain GL using short TE MRS at 3.0 T. The method can correctly detect 2HG as expression of IDH mutation in WHO grades II and III GL with a 100% specificity but a 75% sensitivity. In the evaluation of glioblastoma, short TE MRS performs poorly having a 17% false positive rate.

  8. Multimodality Imaging Probe for Positron Emission Tomography and Fluorescence Imaging Studies

    Directory of Open Access Journals (Sweden)

    Suresh K. Pandey

    2014-05-01

    Full Text Available Our goal is to develop multimodality imaging agents for use in cell tracking studies by positron emission tomography (PET and optical imaging (OI. For this purpose, bovine serum albumin (BSA was complexed with biotin (histologic studies, 5(6- carboxyfluorescein, succinimidyl ester (FAM SE (OI studies, and diethylenetriamine pentaacetic acid (DTPA for chelating gallium 68 (PET studies. For synthesis of BSA-biotin-FAM-DTPA, BSA was coupled to (+-biotin N-hydroxysuccinimide ester (biotin-NHSI. BSA- biotin was treated with DTPA-anhydride and biotin-BSA-DTPA was reacted with FAM. The biotin-BSA-DTPA-FAM was reacted with gallium chloride 3 to 5 mCi eluted from the generator using 0.1 N HCl and was passed through basic resin (AG 11 A8 and 150 mCi (100 μL, pH 7–8 was incubated with 0.1 mg of FAM conjugate (100 μL at room temperature for 15 minutes to give 66Ga-BSA-biotin-DTPA-FAM. A shaved C57 black mouse was injected with FAM conjugate (50 μL at one flank and FAM-68Ga (50 μL, 30 mCi at the other. Immediately after injection, the mouse was placed in a fluorescence imaging system (Kodak In-Vivo F, Bruker Biospin Co., Woodbridge, CT and imaged (Λex: 465 nm, Λem: 535 nm, time: 8 seconds, Xenon Light Source, Kodak. The same mouse was then placed under an Inveon microPET scanner (Siemens Medical Solutions, Knoxville, TN injected (intravenously with 25 μCi of 18F and after a half-hour (to allow sufficient bone uptake was imaged for 30 minutes. Molecular weight determined using matrix-associated laser desorption ionization (MALDI for the BSA sample was 66,485 Da and for biotin-BSA was 67,116 Da, indicating two biotin moieties per BSA molecule; for biotin-BSA-DTPA was 81,584 Da, indicating an average of 30 DTPA moieties per BSA molecule; and for FAM conjugate was 82,383 Da, indicating an average of 1.7 fluorescent moieties per BSA molecule. Fluorescence imaging clearly showed localization of FAM conjugate and FAM-68Ga at respective flanks of the mouse

  9. Imaging study of the painful heel syndrome

    International Nuclear Information System (INIS)

    Williams, P.L.; Smibert, J.G.; Cox, R.; Mitchell, R.; Klenerman, L.

    1987-01-01

    A total of 45 patients with the painful heel syndrome without evidence of an associated inflammatory arthritis, seven of whom had pain in both heels, were studied using technetium-99 isotope bone scans and lateral and 45 degrees medial oblique radiographs of both feet. Of the 52 painful heels 31 (59.6%) showed increased uptake of tracer at the calcaneum. Patients with scans showing increased uptake tended to have more severe heel pain and responded more frequently to a local hydrocortisone injection. On plain x-ray, 39 of 52 painful heels (75%) and 24 of the 38 opposite nonpainful heels (63%) showed plantar spurs, compared with five of 63 (7.9%) heels in 59 age- and sex-matched controls. No evidence of stress fractures was seen

  10. Detecting deep venous thrombosis with limited flip angle gradient refocused MR imaging

    International Nuclear Information System (INIS)

    Spritzer, C.E.; Sussman, S.K.; Herfkens, R.J.; Blinder, R.A.; Saeed, M.; Vogler, J.A.; Baker, M.E.

    1987-01-01

    This study was undertaken to determine if limited flip angle gradient refocused MR pulse sequences (GRASS) could be used to accurately diagnose deep venous thrombosis (DVT). Sixteen patients (17 extremities) with possible DVT were prospectively evaluated with MR imaging and venography. Typical imaging parameters included a 16-msec echo time, 33-msec repetition time, 30 0 flip angle, and section thickness of 2 nex. MR imaging correctly disclosed the presence (nine cases) or absence (eight cases) of DVT. In one study, GRASS images overestimated the extent of clot due to slow venous blood flow. Subsequently the flip angle was varied to distinguish between venous thrombus and slow flow. When this technique was used, no false-positive studies occurred in the remaining patients. MR gradient refocused imaging appears to be an accurate aid for the diagnosis of DVT

  11. A Study of Residual Image in Charged-Coupled Device

    Directory of Open Access Journals (Sweden)

    Ho Jin

    2005-12-01

    Full Text Available For an image sensor CCD, electrons can be trapped at the front-side Si-SiO_2 surface interface in a case of exceeding the full well by bright source. Residual images can be made by the electrons remaining in the interface. These residual images are seen in the front-side-illuminated CCDs especially. It is not easy to find a quantitative analysis for this phenomenon in the domestic reports, although it is able to contaminate observation data. In this study, we find residual images in dark frames which were obtained from the front-side-illuminated CCD at Mt. Lemmon Optical Astronomy Observatory (LOAO, and analyze the effect to contaminated observation data by residual charges.

  12. A Time of Flight Fast Neutron Imaging System Design Study

    Science.gov (United States)

    Canion, Bonnie; Glenn, Andrew; Sheets, Steven; Wurtz, Ron; Nakae, Les; Hausladen, Paul; McConchie, Seth; Blackston, Matthew; Fabris, Lorenzo; Newby, Jason

    2017-09-01

    LLNL and ORNL are designing an active/passive fast neutron imaging system that is flexible to non-ideal detector positioning. It is often not possible to move an inspection object in fieldable imager applications such as safeguards, arms control treaty verification, and emergency response. Particularly, we are interested in scenarios which inspectors do not have access to all sides of an inspection object, due to interfering objects or walls. This paper will present the results of a simulation-based design parameter study, that will determine the optimum system design parameters for a fieldable system to perform time-of-flight based imaging analysis. The imaging analysis is based on the use of an associated particle imaging deuterium-tritium (API DT) neutron generator to get the time-of-flight of radiation induced within an inspection object. This design study will investigate the optimum design parameters for such a system (e.g. detector size, ideal placement, etc.), as well as the upper and lower feasible design parameters that the system can expect to provide results within a reasonable amount of time (e.g. minimum/maximum detector efficiency, detector standoff, etc.). Ideally the final prototype from this project will be capable of using full-access techniques, such as transmission imaging, when the measurement circumstances allow, but with the additional capability of producing results at reduced accessibility.

  13. Localizing studies in patients with persistent or recurrent hyperparathyroidism

    International Nuclear Information System (INIS)

    Levin, K.E.; Gooding, G.A.; Okerlund, M.

    1987-01-01

    Preoperative localizing studies are essential for patients with persistent or recurrent hyperparathyroidism requiring reoperation, because of loss of normal tissue planes and because the hyperfunctioning parathyroid tissue that remains is more likely to be situated in an ectopic position. The value of noninvasive and invasive localizing techniques was evaluated in 59 consecutive patients undergoing reoperation for persistent (40 patients) or recurrent (19 patients) hyperparathyroidism. Magnetic resonance imaging was performed in 17 patients; 11 results (65%) were positive, 3 (18%) were negative, and 3 (18%) were false-positive. Ultrasonography was performed in 52 patients; 29 (56%) were positive, 16 (31%) were negative, and 7 (13%) were false-positive. Computed tomography was performed on 41 patients; 19 (46%) were positive, 16 (39%) were negative, and 6 (15%) were false-positive. Thallium chloride 201-technetium 99m pertechnetate scans were used in 39 patients; 19 (49%) were positive, 11 (28%) were negative, and 9 (13%) were false-positive. One or more of these noninvasive tests was positive in 78% of the cases. Highly selective venous catheterization with measurement of immunoreactive parathyroid hormone concentration localized the abnormal parathyroid gland in 20 of 28 patients (71%) overall and in 8 of the 14 patients (57%) whose tumors were not identified by the noninvasive techniques. Since false-positive results were common, a combination of localizing studies was helpful in identifying the abnormal gland. Fifty-three of the 59 patients (90%) were successfully treated at the initial reoperation and three were successfully treated at a second reoperation. Advances in parathyroid localization have contributed to the improved surgical results in patients with persistent or recurrent hyperparathyroidism

  14. Studying depression using imaging and machine learning methods

    Directory of Open Access Journals (Sweden)

    Meenal J. Patel

    2016-01-01

    Full Text Available Depression is a complex clinical entity that can pose challenges for clinicians regarding both accurate diagnosis and effective timely treatment. These challenges have prompted the development of multiple machine learning methods to help improve the management of this disease. These methods utilize anatomical and physiological data acquired from neuroimaging to create models that can identify depressed patients vs. non-depressed patients and predict treatment outcomes. This article (1 presents a background on depression, imaging, and machine learning methodologies; (2 reviews methodologies of past studies that have used imaging and machine learning to study depression; and (3 suggests directions for future depression-related studies.

  15. Studying depression using imaging and machine learning methods.

    Science.gov (United States)

    Patel, Meenal J; Khalaf, Alexander; Aizenstein, Howard J

    2016-01-01

    Depression is a complex clinical entity that can pose challenges for clinicians regarding both accurate diagnosis and effective timely treatment. These challenges have prompted the development of multiple machine learning methods to help improve the management of this disease. These methods utilize anatomical and physiological data acquired from neuroimaging to create models that can identify depressed patients vs. non-depressed patients and predict treatment outcomes. This article (1) presents a background on depression, imaging, and machine learning methodologies; (2) reviews methodologies of past studies that have used imaging and machine learning to study depression; and (3) suggests directions for future depression-related studies.

  16. An observational study to assess if automated diabetic retinopathy image assessment software can replace one or more steps of manual imaging grading and to determine their cost-effectiveness.

    Science.gov (United States)

    Tufail, Adnan; Kapetanakis, Venediktos V; Salas-Vega, Sebastian; Egan, Catherine; Rudisill, Caroline; Owen, Christopher G; Lee, Aaron; Louw, Vern; Anderson, John; Liew, Gerald; Bolter, Louis; Bailey, Clare; Sadda, SriniVas; Taylor, Paul; Rudnicka, Alicja R

    2016-12-01

    Diabetic retinopathy screening in England involves labour-intensive manual grading of retinal images. Automated retinal image analysis systems (ARIASs) may offer an alternative to manual grading. To determine the screening performance and cost-effectiveness of ARIASs to replace level 1 human graders or pre-screen with ARIASs in the NHS diabetic eye screening programme (DESP). To examine technical issues associated with implementation. Observational retrospective measurement comparison study with a real-time evaluation of technical issues and a decision-analytic model to evaluate cost-effectiveness. A NHS DESP. Consecutive diabetic patients who attended a routine annual NHS DESP visit. Retinal images were manually graded and processed by three ARIASs: iGradingM (version 1.1; originally Medalytix Group Ltd, Manchester, UK, but purchased by Digital Healthcare, Cambridge, UK, at the initiation of the study, purchased in turn by EMIS Health, Leeds, UK, after conclusion of the study), Retmarker (version 0.8.2, Retmarker Ltd, Coimbra, Portugal) and EyeArt (Eyenuk Inc., Woodland Hills, CA, USA). The final manual grade was used as the reference standard. Arbitration on a subset of discrepancies between manual grading and the use of an ARIAS by a reading centre masked to all grading was used to create a reference standard manual grade modified by arbitration. Screening performance (sensitivity, specificity, false-positive rate and likelihood ratios) and diagnostic accuracy [95% confidence intervals (CIs)] of ARIASs. A secondary analysis explored the influence of camera type and patients' ethnicity, age and sex on screening performance. Economic analysis estimated the cost per appropriate screening outcome identified. A total of 20,258 patients with 102,856 images were entered into the study. The sensitivity point estimates of the ARIASs were as follows: EyeArt 94.7% (95% CI 94.2% to 95.2%) for any retinopathy, 93.8% (95% CI 92.9% to 94.6%) for referable retinopathy and 99

  17. Diagnostic assessment of painless microhematuria: prospective study comparing image quality, assessibility and diagnostic certainty of multidetector-row CT and intravenous pyelography within a single examination

    International Nuclear Information System (INIS)

    Boehm, T.; John, H.; Ruedi, C.; Marincek, B.; Wildermuth, S.; Michael, M.

    2005-01-01

    Purpose: The purpose of this study is to prospectively compare intravenous pyelography (IVP) and combined unenhanced and excretory phase multidetector-row CT (MDCT) with respect to image quality, diagnostic certainty and diagnostic concordance with the final clinical diagnosis in patients with painless microhematuria. Materials and Methods: Unenhanced MDCT, IVP and excretory phase MDCT were performed in 59 consecutive patients (21 women, 38 men, mean age 56±19 years, range 23-83 years) with painless microhematuria of unknown origin during a single examination with a single contrast media application (100 ml, non-ionic iodinate contrast media). Images were assessed by two experienced urogenital radiologists in consensus for image quality, diagnostic certainty of stone detection, obstruction, parenchymal lesions and morphological distinctive features. Imaging diagnoses of MDCT and IVP were compared with the final clinical diagnoses. In case of failure to detect an relevant pathology, the final clinical diagnosis was established after a mean follow-up period of 18±6 months (10 months to 2 years). Costs and radiation exposure of IVP and MDCT were compared. Results: MDCT scan performed better than IVP in terms of image quality for all regarded variables. Image quality of MDCT was rated in all parameters as very good or good; the image quality of IVP differed in a wide range. MDCT and IVP reached a sensitivity of 100% and 50% for stone detection (n=14, p=0.008), respectively. Two bladder stones were not detected by IVU but correctly seen with MDCT. MDCT and IVP were unsatisfactory for detecting transitional cell carcinomas (n=4, 2 of 4 detected with MDCT, 0 of 4 detected with IVU). One false positive transitional cell carcinoma was detected with IVP, none with MDCT. Additional relevant pathological changes (one teratoma, one abdominal aortic aneurysma and one abscess) were detected using MDCT but missed with IVP. In 38 of 59 patients (64%) imaging and clinical follow

  18. Imaging stress effects on memory: a review of neuroimaging studies

    NARCIS (Netherlands)

    van Stegeren, A.H.

    2009-01-01

    Objective: To review and give an overview of neuroimaging studies that look at the role of stress (hormones) on memory. Method: An overview will be given of imaging studies that looked at the role of stress (hormones) on memory. Stress is here defined as the acute provocation of the sympathetic

  19. New Image Qualities in Education: A Comparative Study

    Science.gov (United States)

    Çankaya, Ibrahim

    2018-01-01

    The aim of this study is to compare Turkish and European Union Countries Educations in terms of the new image qualities such as data like access to online education, digital access, foreign languages learnt per pupil, research & development investments, human resources employed in science and technology, the study opportunities offered to…

  20. Image quality of conventional images of dual-layer SPECTRAL CT: a phantom study.

    Science.gov (United States)

    van Ommen, F; Bennink, E; Vlassenbroek, A; Dankbaar, J W; Schilham, A M R; Viergever, M A; de Jong, H W A M

    2018-05-10

    Spectral CT using a dual layer detector offers the possibility of retrospectively introducing spectral information to conventional CT images. In theory, the dual-layer technology should not come with a dose or image quality penalty for conventional images. In this study, we evaluate the influence of a dual-layer detector (IQon Spectral CT, Philips) on the image quality of conventional CT images, by comparing these images with those of a conventional but otherwise technically comparable single-layer CT scanner (Brilliance iCT, Philips), by means of phantom experiments. For both CT scanners conventional CT images were acquired using four adult scanning protocols: i) body helical, ii) body axial, iii) head helical and iv) head axial. A CATPHAN 600 phantom was scanned to conduct an assessment of image quality metrics at equivalent (CTDI) dose levels. Noise was characterized by means of noise power spectra (NPS) and standard deviation (SD) of a uniform region, and spatial resolution was evaluated with modulation transfer functions (MTF) of a tungsten wire. In addition, contrast-to-noise ratio (CNR), image uniformity, CT number linearity, slice thickness, slice spacing, and spatial linearity were measured and evaluated. Additional measurements of CNR, resolution and noise were performed in two larger phantoms. The resolution levels at 50%, 10% and 5% MTF of the iCT and IQon showed small but significant differences up to 0.25 lp/cm for body scans, and up to 0.2 lp/cm for head scans in favor of the IQon. The iCT and IQon showed perfect CT linearity for body scans, but for head scans both scanners showed an underestimation of the CT numbers of materials with a high opacity. Slice thickness was slightly overestimated for both scanners. Slice spacing was comparable and reconstructed correctly. In addition, spatial linearity was excellent for both scanners, with a maximum error of 0.11 mm. CNR was higher on the IQon compared to the iCT for both normal and larger phantoms with

  1. A longitudinal study of language learners’ images about Russia

    Directory of Open Access Journals (Sweden)

    Nikitina Larisa

    2016-05-01

    Full Text Available Several studies in the field of applied linguistics have explored images held by language learners about a target language country. However, for the most part, these studies focused on learners of modern European languages, such as German, Spanish and French and they were conducted in Western educational contexts. Besides, none of the previous investigations attempted to conduct a systematic classification of the language learners’ images. The present longitudinal study addressed these gaps in the research literature. It explored images about Russia held by Malaysian learners of the Russian language in a large university in East Malaysia. This article reports the findings of three questionnaire surveys conducted in 2004, 2007 and 2010. It was found that the images about Russia held by the participants were diverse and clustered around eight countryrelated aspects. Content of some categories of images was stable and changed little over time. Other categories were more fluid and more prone to change. The paper concludes with a discussion of pedagogical implications that can be derived from the findings.

  2. Automated image analysis in the study of collagenous colitis

    DEFF Research Database (Denmark)

    Fiehn, Anne-Marie Kanstrup; Kristensson, Martin; Engel, Ulla

    2016-01-01

    PURPOSE: The aim of this study was to develop an automated image analysis software to measure the thickness of the subepithelial collagenous band in colon biopsies with collagenous colitis (CC) and incomplete CC (CCi). The software measures the thickness of the collagenous band on microscopic...... slides stained with Van Gieson (VG). PATIENTS AND METHODS: A training set consisting of ten biopsies diagnosed as CC, CCi, and normal colon mucosa was used to develop the automated image analysis (VG app) to match the assessment by a pathologist. The study set consisted of biopsies from 75 patients...

  3. Breast cancer imaging using radiolabelled somatostatin analogues

    International Nuclear Information System (INIS)

    Dalm, Simone U.; Melis, Marleen; Emmering, Jasper; Kwekkeboom, Dik J.; Jong, Marion de

    2016-01-01

    false positives were reported. In the majority of the studies scan outcome was not associated with BC subtype.

  4. Establishment study of the in vivo imaging analysis with small animal imaging modalities for bio-durg development

    International Nuclear Information System (INIS)

    Jang, Beomsu; Park, Sanghyeon; Choi, Dae Seong; Park, Jeonghoon; Jung, Uhee; Lee, Yun Jong

    2012-01-01

    In this study, we established the image modalities (micro-PET, SPECT/CT) using the experimental animal (mouse) for the development of imaging assessment method for the bio-durg and extramural collaboration proposal. We examined the micro-SPECT/CT, PET imaging study using the Siemens Inveon micro-multimodality system (SPECT/CT) and imaging study using the Siemens Inveon micro-multimodality system (SPECT/CT) and micro-PET with 99m Tc tricarbonyl bifunctional chelators and 18 F-clotrimazole derivative. SPECT imaging studies were performed with 99m Tc tricarbonyl BFCs. PET imaging study was performed with 18 F-clotrimazole derivatives. We performed the PET image study of 18 F-clotrimazole derivatives using U87MG tumor bearing mice. Also we tested the intramural and extramural collaboration using small animal imaging modalities and prepared the draft of extramural R and D operation manual for small animal imaging modalities and the experimental animal imaging facility. These research results can be utilized as a basic image study protocols and data for the image assessment of drugs including biological drug

  5. [A computer-aided image diagnosis and study system].

    Science.gov (United States)

    Li, Zhangyong; Xie, Zhengxiang

    2004-08-01

    The revolution in information processing, particularly the digitizing of medicine, has changed the medical study, work and management. This paper reports a method to design a system for computer-aided image diagnosis and study. Combined with some good idea of graph-text system and picture archives communicate system (PACS), the system was realized and used for "prescription through computer", "managing images" and "reading images under computer and helping the diagnosis". Also typical examples were constructed in a database and used to teach the beginners. The system was developed by the visual developing tools based on object oriented programming (OOP) and was carried into operation on the Windows 9X platform. The system possesses friendly man-machine interface.

  6. Dynamic Studies of Lung Fluid Clearance with Phase Contrast Imaging

    International Nuclear Information System (INIS)

    Kitchen, Marcus J.; Williams, Ivan; Irvine, Sarah C.; Morgan, Michael J.; Paganin, David M.; Lewis, Rob A.; Pavlov, Konstantin; Hooper, Stuart B.; Wallace, Megan J.; Siu, Karen K. W.; Yagi, Naoto; Uesugi, Kentaro

    2007-01-01

    Clearance of liquid from the airways at birth is a poorly understood process, partly due to the difficulties of observing and measuring the distribution of air within the lung. Imaging dynamic processes within the lung in vivo with high contrast and spatial resolution is therefore a major challenge. However, phase contrast X-ray imaging is able to exploit inhaled air as a contrast agent, rendering the lungs of small animals visible due to the large changes in the refractive index at air/tissue interfaces. In concert with the high spatial resolution afforded by X-ray imaging systems (<100 μm), propagation-based phase contrast imaging is ideal for studying lung development. To this end we have utilized intense, monochromatic synchrotron radiation, together with a fast readout CCD camera, to study fluid clearance from the lungs of rabbit pups at birth. Local rates of fluid clearance have been measured from the dynamic sequences using a single image phase retrieval algorithm

  7. Fijación de radioyodo en huesos maxilares simulando metástasis en pacientes con Carcinoma Diferenciado de Tiroides (CDT): False- Positive images in patients with Differentiated Thyroid Carcinoma. (DTC) Uptake of 131-I in maxillary bones mimicking salivary glands

    OpenAIRE

    O. J. Degrossi; S. Gutiérrez; A. Fadel; E. B. Degrossi; M. C. Valdivieso; R. L. Balbuena; M. del C. Alak; M. de Cabrejas

    2008-01-01

    En estudios centellográficos con 131I (CCT) para seguimiento, postablación o tratamiento de pacientes portadores de carcinoma diferenciado de tiroides (CDT) se observan frecuentemente en tiempos precoces áreas de captación del radiotrazador en macizo facial. Estas áreas corresponden, generalmente, a glándulas salivares y extremo anterior de mucosa nasal y se mantienen durante las primeras 48 horas y no son observadas generalmente a las 72 horas. Pero con menor frecuencia se presentan otras qu...

  8. Modeling digital breast tomosynthesis imaging systems for optimization studies

    Science.gov (United States)

    Lau, Beverly Amy

    Digital breast tomosynthesis (DBT) is a new imaging modality for breast imaging. In tomosynthesis, multiple images of the compressed breast are acquired at different angles, and the projection view images are reconstructed to yield images of slices through the breast. One of the main problems to be addressed in the development of DBT is the optimal parameter settings to obtain images ideal for detection of cancer. Since it would be unethical to irradiate women multiple times to explore potentially optimum geometries for tomosynthesis, it is ideal to use a computer simulation to generate projection images. Existing tomosynthesis models have modeled scatter and detector without accounting for oblique angles of incidence that tomosynthesis introduces. Moreover, these models frequently use geometry-specific physical factors measured from real systems, which severely limits the robustness of their algorithms for optimization. The goal of this dissertation was to design the framework for a computer simulation of tomosynthesis that would produce images that are sensitive to changes in acquisition parameters, so an optimization study would be feasible. A computer physics simulation of the tomosynthesis system was developed. The x-ray source was modeled as a polychromatic spectrum based on published spectral data, and inverse-square law was applied. Scatter was applied using a convolution method with angle-dependent scatter point spread functions (sPSFs), followed by scaling using an angle-dependent scatter-to-primary ratio (SPR). Monte Carlo simulations were used to generate sPSFs for a 5-cm breast with a 1-cm air gap. Detector effects were included through geometric propagation of the image onto layers of the detector, which were blurred using depth-dependent detector point-spread functions (PRFs). Depth-dependent PRFs were calculated every 5-microns through a 200-micron thick CsI detector using Monte Carlo simulations. Electronic noise was added as Gaussian noise as a

  9. The brain imaging study of the organophosphorus pesticides poisoning

    International Nuclear Information System (INIS)

    Yang Yanmei; Liu Huaijun; Li Shuling; Wang Yongsheng; Huang Boyuan; Chi Cen; Shi Zhenyang; Cui Caixia; Zhou Lixia; Liu Runtian

    2004-01-01

    Objective: To summarize the CT and MR imaging findings in acute organophosphorus pesticides poisoning patients, and to improve the early diagnostic ability. Methods: The imaging of 34 patients of organophosphorus pesticides poisoning was analyzed, the poisons were all taken orally. The pesticides included methamidophos (12 cases), omethoate (15 cases), DDV (3 cases), and methylparathion (4 cases). According to the diagnosis and classification diagnosis criterion of acute organophosphorus pesticides poisoning, the patients were divided into two groups: mild or moderate grade group (24 cases) and severe grade group (10 cases). The relationship between the clinic grade and CT and MRI findings was studied. Results: in the severe grade group, 4 patients showed brain edema, presenting as sulcus and fissure flattened or disappeared, and ventricles and cisterns narrowed or closed 2-3 days after poisoning. In 3 patients 3 days to 3 months after poisoning, bilateral basal ganglion and cerebral cortex showed prolonged T 1 and T 2 signals, and high signal intensity was detected on FLAIR, and bilateral basal ganglion low density was revealed on CT. T 1 relaxation was shortened, T 2 WI and FLAIR imaging showed high signal intensity in 1 patient. The imaging of 1 patient 6 months after poisoning showed the cerebral sulcus, fissure and ventricle were enlarged. CT and MRI in the mild or moderate group were normal. By the Fisher's exact probabilities test, the imaging exhibition difference between the severe grade and mild or moderate grade patients was significant. Conclusion: The CT and MRI can reflect the brain injury after poisoning, and the imaging exhibitions were various. The imaging information can provide credible foundation for the therapy for lightening the brain edema and nourishing the brain cell

  10. Diagnostic imaging in the study of human hepatobiliary fascioliasis.

    Science.gov (United States)

    Cantisani, V; Cantisani, C; Mortelé, K; Pagliara, E; D'Onofrio, M; Fernandez, M; D'Ambrosio, U; Lombardi, V; Marigliano, C; Ricci, P

    2010-02-01

    Fascioliasis is a rare zoonotic disease caused by the trematode Fasciola hepatica. We present the typical patterns of hepatobiliary fascioliasis observed in ten patients studied with multimodality imaging. Between 2002 and 2005, ten women with fascioliasis were admitted to the Brigham and Women's Hospital, Harvard Medical School (BWH), with abdominal pain and mild fever. All imaging modalities, including ultrasound (US), computed tomography (CT), magnetic resonance (MR) imaging (n = 2) and endoscopic retrograde cholangiopancreatography (ERCP) (n = 1) were reviewed by two expert radiologists working in consensus. In all patients (10/10, 100%), US showed parenchymal heterogeneity characterised by multiple subcapsular and peribiliary hypoechoic nodular lesions that were ill-defined and coalesced into tubular or tortuous structures. In six patients (6/10, 60%), the lesions appeared hypoechoic, whereas in four patients (4/10, 40%), there was an alternation of hyperechoic and hypoechoic nodules. On CT, all patients (10/10, 100%) showed hypodense patchy lesions in subcapsular, peribiliary or periportal locations, which coalesced to form tubular structures and were more evident during the portal phase. Lesion diameter ranged from 2 cm to 7 cm. Capsular enhancement was seen in four cases on CT (4/10, 40%) and in one also at MR imaging. MR imaging, performed in two patients, confirmed the presence of the lesions, which appeared hyperintense on T2-weighted images and were characterised by mild peripheral enhancement after gadolinium administration. Four patients had gallbladder wall thickening (4/10, 40%), with parasites in the gallbladder lumen. Although rare, hepatobiliary fascioliasis should be considered in the differential diagnosis in the appropriate clinical scenario, especially in patients coming from endemic areas. The typical imaging pattern of fascioliasis is the presence of subcapsular, peribiliary or periportal nodules that are usually ill-defined and coalesce

  11. Image based 3D city modeling : Comparative study

    Directory of Open Access Journals (Sweden)

    S. P. Singh

    2014-06-01

    Full Text Available 3D city model is a digital representation of the Earth’s surface and it’s related objects such as building, tree, vegetation, and some manmade feature belonging to urban area. The demand of 3D city modeling is increasing rapidly for various engineering and non-engineering applications. Generally four main image based approaches were used for virtual 3D city models generation. In first approach, researchers were used Sketch based modeling, second method is Procedural grammar based modeling, third approach is Close range photogrammetry based modeling and fourth approach is mainly based on Computer Vision techniques. SketchUp, CityEngine, Photomodeler and Agisoft Photoscan are the main softwares to represent these approaches respectively. These softwares have different approaches & methods suitable for image based 3D city modeling. Literature study shows that till date, there is no complete such type of comparative study available to create complete 3D city model by using images. This paper gives a comparative assessment of these four image based 3D modeling approaches. This comparative study is mainly based on data acquisition methods, data processing techniques and output 3D model products. For this research work, study area is the campus of civil engineering department, Indian Institute of Technology, Roorkee (India. This 3D campus acts as a prototype for city. This study also explains various governing parameters, factors and work experiences. This research work also gives a brief introduction, strengths and weakness of these four image based techniques. Some personal comment is also given as what can do or what can’t do from these softwares. At the last, this study shows; it concluded that, each and every software has some advantages and limitations. Choice of software depends on user requirements of 3D project. For normal visualization project, SketchUp software is a good option. For 3D documentation record, Photomodeler gives good

  12. Femtosecond photodissociation dynamics of I studied by ion imaging

    DEFF Research Database (Denmark)

    Larsen, J.J.; Bjerre, N.; Mørkbak, N.J.

    1998-01-01

    on imaging is employed to analyze the fragments from timed Coulomb explosion studies of femtosecond (fs) molecular dynamics. The technique provides high detection efficiency and direct recording of the two-dimensional velocity of all ionized fragments. We illustrate the approach by studying...... agreement with quantum mechanical wave packet simulations. We discuss the perspectives for extending the studies to photochemical reactions of small polyatomic molecules...

  13. Generative Topic Modeling in Image Data Mining and Bioinformatics Studies

    Science.gov (United States)

    Chen, Xin

    2012-01-01

    Probabilistic topic models have been developed for applications in various domains such as text mining, information retrieval and computer vision and bioinformatics domain. In this thesis, we focus on developing novel probabilistic topic models for image mining and bioinformatics studies. Specifically, a probabilistic topic-connection (PTC) model…

  14. Clinical findings versus imaging studies in the diagnosis of infantile ...

    African Journals Online (AJOL)

    patients, and increased muscle diameter of more than. 14mm in 54 (90%) patients with both longitudinal and transverse images. A barium study was performed in all patients and different signs were noted (Fig. 1). Distended stomach and delayed gastric emptying were found in 55 (91.66%) cases, elongated pyloric channel ...

  15. Collaborative Initiative in Biomedical Imaging to Study Complex Diseases

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Weili [The University of North Carolina at Chapel Hill; Fiddy, Michael A. [The University of North Carolina at Charlotte

    2012-03-31

    The work reported addressed these topics: Fluorescence imaging; Optical coherence tomography; X-ray interferometer/phase imaging system; Quantitative imaging from scattered fields, Terahertz imaging and spectroscopy; and Multiphoton and Raman microscopy.

  16. a Comparative Case Study of Reflection Seismic Imaging Method

    Science.gov (United States)

    Alamooti, M.; Aydin, A.

    2017-12-01

    Seismic imaging is the most common means of gathering information about subsurface structural features. The accuracy of seismic images may be highly variable depending on the complexity of the subsurface and on how seismic data is processed. One of the crucial steps in this process, especially in layered sequences with complicated structure, is the time and/or depth migration of seismic data.The primary purpose of the migration is to increase the spatial resolution of seismic images by repositioning the recorded seismic signal back to its original point of reflection in time/space, which enhances information about complex structure. In this study, our objective is to process a seismic data set (courtesy of the University of South Carolina) to generate an image on which the Magruder fault near Allendale SC can be clearly distinguished and its attitude can be accurately depicted. The data was gathered by common mid-point method with 60 geophones equally spaced along an about 550 m long traverse over a nearly flat ground. The results obtained from the application of different migration algorithms (including finite-difference and Kirchhoff) are compared in time and depth domains to investigate the efficiency of each algorithm in reducing the processing time and improving the accuracy of seismic images in reflecting the correct position of the Magruder fault.

  17. Multimodality molecular imaging - from target description to clinical studies

    International Nuclear Information System (INIS)

    Schober, O.; Rahbar, K.; Riemann, B.

    2009-01-01

    This highlight lecture was presented at the closing session of the Annual Congress of the European Association of Nuclear Medicine (EANM) in Munich on 15 October 2008. The Congress was a great success: there were more than 4,000 participants, and 1,597 abstracts were submitted. Of these, 1,387 were accepted for oral or poster presentation, with a rejection rate of 14%. In this article a choice was made from 100 of the 500 lectures which received the highest scores by the scientific review panel. This article outlines the major findings and trends at the EANM 2008, and is only a brief summary of the large number of outstanding abstracts presented. Among the great number of oral and poster presentations covering nearly all fields of nuclear medicine some headlines have to be defined highlighting the development of nuclear medicine in the 21st century. This review focuses on the increasing impact of molecular and multimodality imaging in the field of nuclear medicine. In addition, the question may be asked as to whether the whole spectrum of nuclear medicine is nothing other than molecular imaging and therapy. Furthermore, molecular imaging will and has to go ahead to multimodality imaging. In view of this background the review was structured according to the single steps of molecular imaging, i.e. from target description to clinical studies. The following topics are addressed: targets, radiochemistry and radiopharmacy, devices and computer science, animals and preclinical evaluations, and patients and clinical evaluations. (orig.)

  18. Feasibility study of 3-T MR imaging of the skin

    Energy Technology Data Exchange (ETDEWEB)

    Aubry, Sebastien; Kastler, Bruno [CHU Jean Minjoz, Service de Radiologie A, Besancon Cedex (France); Universite de Franche-comte, Laboratoire Intervention, Imagerie, Ingenierie et Innovation en Sante, Besancon (France); Casile, Celine; Jehl, Jerome [CHU Jean Minjoz, Service de Radiologie A, Besancon Cedex (France); Humbert, Philippe [CHU Saint-Jacques, Service de Dermatologie, Besancon (France); Vidal, Chrystelle [CHU Saint-Jacques, Centre d' Investigation Clinique en Innovation technologique, Besancon (France)

    2009-07-15

    The purpose of this study was to assess the quality of 3-T magnetic resonance (MR) imaging of the skin, to describe skin anatomy at 3 T and to discuss future prospects of skin MRI. A 7-cm single-element surface receiver coil was developed for our 3-T MRI system. Thin sections were obtained with a three-dimensional FIESTA acquisition sequence and a spin-echo T1-weighted sequence (SET1). Prospective analysis was performed twice by two radiologists independently. Thirty-six healthy volunteers were included and underwent MRI on the face and the calf. Image quality was assessed regarding visibility of skin layers and quantification of artefacts. High field strength MR enables imaging of the skin with a high spatial in-plane resolution (87-180 {mu}m), the total examination lasting 15-20 min. Image quality was excellent for the calf (mean SET1 quality = 96%) with a high intra- and interobserver correlation (SET1 kappa coefficient concerning visibility of epidermis, dermis and hypodermis {>=} 0.84). Motion artefacts resulted in a small loss of quality and reproducibility for the face. In conclusion, 3-T MR allows high spatial resolution imaging of the skin and can potentially provide an accurate noninvasive means of analysing the skin. (orig.)

  19. Use of multispectral images and chemometrics in tomato seed studies

    DEFF Research Database (Denmark)

    Shrestha, Santosh; Deleuran, Lise Christina; Gislum, René

    During the production of tomato seeds, green tomatoes are normally discarded before seed extraction irrespective of their maturity stage. Studies indicate that seeds from green tomatoes may reach be able to reach full germination capacity. Thus the potential of multispectral imaging for non......-destructive discrimination of seeds based on their germination capacity was investigated. A total of 840 seeds extracted from green and red tomatoes were divided into two sets; a training set and a test set consisting of 648 and 192 seeds respectively. Each set consisted of 96 seeds from green tomatoes. The multispectral...... images of the seeds were captured and normalized canonical discriminant analysis was used to analyse the images. Germination tests were performed and seeds that subsequently germinated were recorded as viable. The viable seeds were classified with 99% and 98% accuracy for the training and test set...

  20. Evaluation of the specificity of radionuclide myocardial imaging for detecting CAD

    International Nuclear Information System (INIS)

    Liu Xiujie

    1992-01-01

    In order to evaluate the specificity of radionuclide myocardial perfusion imaging for detecting coronary artery disease (CAD), 50 patients with normal coronary arteriography and radionuclide myocardial perfusion scintigraphy were analysed. The results from 201 T1 (20 cases) and 99m Tc-MIBI (30 cases) studies showed that out of 33 patients with no organic cardiovascular disease, 29 had normal myocardial imaging, and the specificity of radionuclide myocardial imaging for detecting CAD was 87.8%. 4 normal young women had false positive myocardial imaging. Out of 17 patients with cardiovascular disease and normal coronary arteriography, 15 patients had abnormal myocardial imaging. The final clinical diagnoses of these 15 patients were: 4 patients with hypertrophic cardiomyopathy, 3 with old myocardial infarction, 2 with myocarditis, 3 with small coronary vessel disease, 1 with congestive cardiomyopathy, and 2 with other cardiac disorder. The points of differentiation between CAD and other cardiovascular disease using radionuclide techniques were discussed

  1. Direct Imaging of Stellar Surfaces: Results from the Stellar Imager (SI) Vision Mission Study

    Science.gov (United States)

    Carpenter, Kenneth; Schrijver, Carolus; Karovska, Margarita

    2006-01-01

    The Stellar Imager (SI) is a UV-Optical, Space-Based Interferometer designed to enable 0.1 milli-arcsecond (mas) spectral imaging of stellar surfaces and stellar interiors (via asteroseismology) and of the Universe in general. SI is identified as a "Flagship and Landmark Discovery Mission'' in the 2005 Sun Solar System Connection (SSSC) Roadmap and as a candidate for a "Pathways to Life Observatory'' in the Exploration of the Universe Division (EUD) Roadmap (May, 2005). The ultra-sharp images of the Stellar Imager will revolutionize our view of many dynamic astrophysical processes: The 0.1 mas resolution of this deep-space telescope will transform point sources into extended sources, and snapshots into evolving views. SI's science focuses on the role of magnetism in the Universe, particularly on magnetic activity on the surfaces of stars like the Sun. SI's prime goal is to enable long-term forecasting of solar activity and the space weather that it drives in support of the Living With a Star program in the Exploration Era. SI will also revolutionize our understanding of the formation of planetary systems, of the habitability and climatology of distant planets, and of many magneto-hydrodynamically controlled processes in the Universe. In this paper we will discuss the results of the SI Vision Mission Study, elaborating on the science goals of the SI Mission and a mission architecture that could meet those goals.

  2. Body image and gestational weight gain: a prospective study.

    Science.gov (United States)

    Hill, Briony; Skouteris, Helen; McCabe, Marita; Fuller-Tyszkiewicz, Matthew

    2013-01-01

    Approximately 50% of Australian adult women of childbearing age are overweight or obese, and, when pregnant, the majority gain excessive weight; this is also the case in the United States and other developed nations. High gestational weight gain (GWG) is the strongest predictor of maternal overweight/obesity postbirth and is also associated with an increased risk of childhood obesity. Understanding factors that contribute to excessive GWG is vital in combating obesity. The aim of the current study was to examine whether body image attitudes (eg, feeling fat, attractive, or strong and fit, and salience of weight and shape) predict GWG. Pregnant women, recruited through advertisements on pregnancy online forums and parenting magazines, completed questionnaires assessing body image, demographic variables, and GWG. The Body Attitudes Questionnaire assessed body image in early-to-middle, middle, and late pregnancy (mean of 16.8, 24.7, and 33.0 weeks' gestation, respectively). Total GWG was calculated by subtracting self-reported pre pregnancy weight from self-reported weight at 36.8 weeks' gestation. A total of 150 pregnant women responded to the study's advertisements, and 72% (n = 108) took part. After controlling for pre pregnancy body mass index (BMI), lower attractiveness in early-to-middle pregnancy was associated with higher GWG. In late pregnancy, women who had the lowest feelings of fatness had greater GWG. Body image attitudes earlier in pregnancy did not predict whether GWG recommendations were exceeded. Women of higher BMI were more likely to gain excessive weight. The findings suggest that the type and timing of pregnancy, body attitudes, and the time of pregnancy when they are noted, predict GWG. However, more research in the area is needed, including assessment of the relationship between body image concerns, GWG, and other psychosocial factors. We recommend that midwives monitor body image concerns in pregnancy to help address factors affecting GWG in at

  3. A comparative study between magnetic resonance imaging and histological findings of bone and soft tissue tumors

    International Nuclear Information System (INIS)

    Itoh, Koichi

    1995-01-01

    Diagnostic methodology for bone and soft tissue tumors has made great strides recently through the development of magnetic resonance imaging (MRI). Here we report a comparative assessment of the histological findings of bone and soft tissue tumors with MRI from 212 cases. The accuracy of a qualitative diagnosis was observed in a solitary bone cyst, enchondroma, giant cell tumor, chondrosarcoma, lipoma, hemangioma, neurinoma, and in a synovial cyst. However, the qualitative diagnosis of a malignant tumor was difficult because of the variety of the intratumoral histological changes. An enhanced-image using Gd-DTPA was useful for differentiation of the viable region in the internal area of a tumor, discrimination of the reactive zone of an edema or assessing vascularity, and for discrimination between a cyst and a solid tumor. Based on comparison with findings from the excised specimen, it was found that histological changes such as calcification, fibrosis, hemorrhaging and necrosis, and the presence or absence of a tumor capsule had been reflected accurately on MR images. However, infiltration of the tumor into the bone cortex and into the articular cartilage were found frequently to be false-positive on MRI. Although problems remained to be solved regarding the evaluation of the presence or absence of tumor infiltration into adjacent tissue, the depiction of periosteal reaction, and regarding differentiation from inflammatory disease, MRI was a very useful information source for operative planning because it could evaluate the relationship between the tumor and adjacent blood vessels or nerves, the effect of preoperative therapy, and effectively discriminate between benign and malignant tumors. (author)

  4. Experimental study of bubbly flow using image processing techniques

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Yucheng, E-mail: ycfu@vt.edu; Liu, Yang, E-mail: liu130@vt.edu

    2016-12-15

    This paper presents an experimental study of bubbly flows at relatively high void fractions using an advanced image processing method. Bubble overlapping is a common problem in such flows and the past studies often treat the overlapping bubbles as a whole, which introduces considerable measurement uncertainties. In this study, a hybrid method combining intersection point detection and watershed segmentation is used to separate the overlapping bubbles. In order to reconstruct bubbles from separated segments, a systematic procedure is developed which can preserve more features captured in the raw image compared to the simple ellipse fitting method. The distributions of void fraction, interfacial area concentration, number density and velocity are obtained from the extracted bubble information. High-speed images of air-water bubbly flows are acquired and processed for eight test runs conducted in a 30 mm × 10 mm rectangular channel. The developed image processing scheme can effectively separate overlapping bubbles and the results compare well with the measurements by the gas flow meter and double-sensor conductivity probe. The development of flows in transverse and mainstream directions are analyzed and compared with the prediction made by the one-dimensional interfacial area transport equation (IATE) and the bubble number density transport equation.

  5. Axial oblique MR imaging of the intrinsic ligaments of the wrist: initial experience

    International Nuclear Information System (INIS)

    Robinson, G.; Chung, T.; Finlay, K.; Friedman, L.

    2006-01-01

    To evaluate two separate MR sequences acquired in the axial oblique plane, parallel to the long axis of the scapholunate (SL) and lunotriquetral (LT) ligaments, to determine whether the addition of these sequences to the standard MR wrist examination improves visualization of the intrinsic ligaments, and the evaluation of their integrity. To our knowledge, this plane has not been described in the literature previously. In total we evaluated 26 patients with chronic wrist pain or instability, referred for MR imaging following assessment by an orthopedic surgeon or physiatrist. All patients underwent initial conventional tri-compartment wrist arthrography, which served as the reference standard. This was immediately followed by MR arthrography, in the standard coronal and true axial planes, as well as in the axial oblique plane. The SL and LT ligaments were initially assessed for the presence or absence of tear, using the standard coronal and true axial sequences, and subsequently re-evaluated with the addition of the axial oblique planes. A total of ten intrinsic ligament tears were identified with conventional arthrography: six SL and four LT tears. Five of the six SL tears were identified on the standard sequences. All six were diagnosed with the addition of the oblique sequences. There were three false-positive SL tears identified using standard MR imaging, and two false-positives with the addition of the oblique sequences. No LT tear was identified on standard sequences, whereas all four were confidently seen with the addition of oblique images. No false-positives of the LT ligament were recorded with either standard or axial oblique sequences. The study suggests that the addition of axial oblique MR sequences helps identify tears to the intrinsic ligaments of the wrist, particularly the LT ligament. In addition, the axial oblique images assist in localization of the tear. (orig.)

  6. Multi-institutional Validation Study of Commercially Available Deformable Image Registration Software for Thoracic Images

    International Nuclear Information System (INIS)

    Kadoya, Noriyuki; Nakajima, Yujiro; Saito, Masahide; Miyabe, Yuki; Kurooka, Masahiko; Kito, Satoshi; Fujita, Yukio; Sasaki, Motoharu; Arai, Kazuhiro; Tani, Kensuke; Yagi, Masashi; Wakita, Akihisa; Tohyama, Naoki; Jingu, Keiichi

    2016-01-01

    Purpose: To assess the accuracy of the commercially available deformable image registration (DIR) software for thoracic images at multiple institutions. Methods and Materials: Thoracic 4-dimensional (4D) CT images of 10 patients with esophageal or lung cancer were used. Datasets for these patients were provided by DIR-lab ( (dir-lab.com)) and included a coordinate list of anatomic landmarks (300 bronchial bifurcations) that had been manually identified. Deformable image registration was performed between the peak-inhale and -exhale images. Deformable image registration error was determined by calculating the difference at each landmark point between the displacement calculated by DIR software and that calculated by the landmark. Results: Eleven institutions participated in this study: 4 used RayStation (RaySearch Laboratories, Stockholm, Sweden), 5 used MIM Software (Cleveland, OH), and 3 used Velocity (Varian Medical Systems, Palo Alto, CA). The ranges of the average absolute registration errors over all cases were as follows: 0.48 to 1.51 mm (right-left), 0.53 to 2.86 mm (anterior-posterior), 0.85 to 4.46 mm (superior-inferior), and 1.26 to 6.20 mm (3-dimensional). For each DIR software package, the average 3-dimensional registration error (range) was as follows: RayStation, 3.28 mm (1.26-3.91 mm); MIM Software, 3.29 mm (2.17-3.61 mm); and Velocity, 5.01 mm (4.02-6.20 mm). These results demonstrate that there was moderate variation among institutions, although the DIR software was the same. Conclusions: We evaluated the commercially available DIR software using thoracic 4D-CT images from multiple centers. Our results demonstrated that DIR accuracy differed among institutions because it was dependent on both the DIR software and procedure. Our results could be helpful for establishing prospective clinical trials and for the widespread use of DIR software. In addition, for clinical care, we should try to find the optimal DIR procedure using thoracic 4D

  7. What Images Reveal: a Comparative Study of Science Images between Australian and Taiwanese Junior High School Textbooks

    Science.gov (United States)

    Ge, Yun-Ping; Unsworth, Len; Wang, Kuo-Hua; Chang, Huey-Por

    2017-07-01

    From a social semiotic perspective, image designs in science textbooks are inevitably influenced by the sociocultural context in which the books are produced. The learning environments of Australia and Taiwan vary greatly. Drawing on social semiotics and cognitive science, this study compares classificational images in Australian and Taiwanese junior high school science textbooks. Classificational images are important kinds of images, which can represent taxonomic relations among objects as reported by Kress and van Leeuwen (Reading images: the grammar of visual design, 2006). An analysis of the images from sample chapters in Australian and Taiwanese high school science textbooks showed that the majority of the Taiwanese images are covert taxonomies, which represent hierarchical relations implicitly. In contrast, Australian classificational images included diversified designs, but particularly types with a tree structure which depicted overt taxonomies, explicitly representing hierarchical super-ordinate and subordinate relations. Many of the Taiwanese images are reminiscent of the specimen images in eighteenth century science texts representing "what truly is", while more Australian images emphasize structural objectivity. Moreover, Australian images support cognitive functions which facilitate reading comprehension. The relationships between image designs and learning environments are discussed and implications for textbook research and design are addressed.

  8. A study of images of Projective Angles of pulmonary veins

    Energy Technology Data Exchange (ETDEWEB)

    Wang Jue [Beijing Anzhen Hospital, Beijing (China); Zhaoqi, Zhang [Beijing Anzhen Hospital, Beijing (China)], E-mail: zhaoqi5000@vip.sohu.com; Yu Wei; Miao Cuilian; Yan Zixu; Zhao Yike [Beijing Anzhen Hospital, Beijing (China)

    2009-09-15

    Aims: In images of magnetic resonance and computed tomography (CT) there are visible angles between pulmonary veins and the coronary, transversal or sagittal section of body. In this study these angles are measured and defined as Projective Angles of pulmonary veins. Several possible influential factors and characters of distribution are studied and analyzed for a better understanding of this imaging anatomic character of pulmonary veins. And it could be the anatomic base of adjusting correctly the angle of the central X-ray of the angiography of pulmonary veins undergoing the catheter ablation of atrial fibrillation (AF). Method: Images of contrast enhanced magnetic resonance angiography (CEMRA) and contrast enhanced computer tomography (CECT) of the left atrium and pulmonary veins of 137 health objects and patients with atrial fibrillation (AF) are processed with the technique of post-processing, and Projective Angles to the coronary and transversal sections are measured and analyzed statistically. Result: Project Angles of pulmonary veins are one of real and steady imaging anatomic characteristics of pulmonary veins. The statistical distribution of variables is relatively concentrated, with a fairly good representation of average value. It is possible to improve the angle of the central X-ray according to the average value in the selective angiography of pulmonary veins undergoing the catheter ablation of AF.

  9. An experimental study regarding diagnostic accuracy on image interpretation of the digital image film by using viewboxes of different luminance

    International Nuclear Information System (INIS)

    Song Shaojuan; Huang Ling; Liu Chuanya; Zhang Xiaojing

    2009-01-01

    Objective: To evaluate diagnostic accuracy of image interpretation using viewboxes at different luminance with ALVIM statistical phantom (TRG). Methods: A digital film of TRG image was obtained by exposing the phantom of TRG with Kodak DR 3000 using proper parameter. Viewboxes with three different luminance were selected from those used in daily work. The film of TRG was evaluated with these viewboxes of three different luminance by three different radiologists with experience of five, eight and sixteen years respectively. A grade scale of 5 was used to evaluate each row of signal and noise. According to the results and formula, the probabilities of true-positive [P(S/s)], false-positive [P(S/n)] and true answer (P det ) were obtained. Results: The three kinds of luminance used in viewboxes were: (3489± 256), (2231±220), (816±168) cd/m 2 . When the average luminance of viewbox was 3489 cd/m 2 , P det of 0.6,0.7,0.8 mm in bone substitute was 0.558±0.009, 0.788±0.008, 0.813±0.006, P det of 0.9, 1.0, 1.2 mm in muscle substitute was 0.663±0.010, 0.750±0.008, 0.933±0.005; When the average luminance of viewbox was 2231 cd/m 2 , P det of 0.6,0.7,0.8 mm in bone substitute was 0.525±0.013, 0.713±0.013,0.775±0.016, P det of 0.9,1.0,1.2 mm in muscle substitute was 0.613±0.019, 0.650± 0.013,0.850±0.019; When the average luminance of viewbox was 816 cd/m 2 , Pact of 0.6,0.7,0.8 mm in bone substitute was 0.475±0.022,0.550±0.018,0.688±0.020, P det of 0.9, 1.0, 1.2 mm in muscle substitute was 0.550±0.025,0.575±0.021,0.725±0.016. Viewboxes of different luminance were compared to one another by paired t-test. The results of comparison all had significant statistical differences (t=5.057 and 4.681, P<0.05). Conclusions: The image displayed by viewboxes at different luminance had significant influence on image interpretation. The higher the luminace of viewbox, the richer the information displayed, and the higher the accuracy of diagnosis. (authors)

  10. A comparative study of computerized tomograms and neuropathological findings in cerebrovascular diseases

    International Nuclear Information System (INIS)

    Tohgi, Hideo; Mochizuki, Hiroshi; Yamanouchi, Hiroshi; Iio, Masahiro; Yamada, Hideo

    1979-01-01

    The reliability of computed tomography (CT) in the diagnosis of cerebrovascular diseases was studied by comparing CT images and neuropathological findings in 38 autopsied cases. Our special concern was directed toward several factors which caused false positive and false negative results in CT: the size and location of lesions, and the interval between the onset of the disease and the time of CT studies. Infarctions smaller than 5 mm should be interpreted as such with great care, because only 32.1% of them could be detected in CT, and 81.0% of small low density areas supposed to be small infarctions in CT films proved to be false positive in postmortem examination. 41.9% of middle-sized infarctions were detected in CT and 40.9% of middle-sized low density areas were false positive. Most of false positive low density areas appeared on the surface of the cerebrum where deep sulci join, or in the white matter anterior to the anterior horn or posterior to the posterior horn of the lateral ventricles. The possibility of false positive findings became far less, when the number of slices showing low density areas increased. All of the large infarctions were detected in CT. However, immediately after stroke they did not stand out as low density areas. In such cases, the decrease of cerebral sulci due to brain edema and signs of compression in the ventricular system could be the clues to make the diagnosis of large infarctions. The diagnosis of hemorrhagic infarctions was often difficult. Cerebral bleeding could be diagnosed easily by CT in its early period. However, old hematomas which rapidly resolved and became shrunken, could hardly be identified in CT. (author)

  11. A study on assessment of bone mass from aluminum-equivalent image by digital imaging system

    International Nuclear Information System (INIS)

    Kim, Jin Soo; Kim, Jae Duck; Choi, Eui Hwan

    1997-01-01

    The purpose of this study was to evaluated the method for quantitative assessment of bone mass from aluminum-equivalent value of hydroxyapatite by using digital imaging system consisted of Power Macintosh 7200/120, 15-inch color monitor, and GT-9000 scanner with transparency unit. After aluminum-equivalent image made from correlation between aluminum thickness and grey scale, the accuracy of conversion to mass from aluminum-equivalent value was evaluated. Measured bone mass was compared with converted bone mass from aluminum-equivalent value of hydroxyapatite block by correlation formula between aluminum-equivalent value of hydroxy apatite block and hydroxyapatite mass. The results of this study were as follows : 1. Correlation between aluminum thickness and grey level for obtaining aluminum-equivalent image was high positively associated (r2=0.99). Converted masses from aluminum-equivalent value were very similar to measured masses. There was, statistically, no significant difference (P<0.05) between them. 2. Correlation between hydroxyapatite aluminum-equivalent and hydroxyapatite mass was shown to linear relation (r2 =0.95). 3. Converted masses from aluminum-equivalent value of 3 dry mandible segments were similar to measured masses. The difference between the exposure directions was not significantly different (P<0.05).

  12. Optimization for PET imaging based on phantom study and NECdensity

    International Nuclear Information System (INIS)

    Daisaki, Hiromitsu; Shimada, Naoki; Shinohara, Hiroyuki

    2012-01-01

    In consideration of the requirement for global standardization and quality control of PET imaging, the present studies gave an outline of phantom study to decide both scan and reconstruction parameters based on FDG-PET/CT procedure guideline in Japan, and optimization of scan duration based on NEC density was performed continuously. In the phantom study, scan and reconstruction parameters were decided by visual assessment and physical indexes (N 10mm , NEC phantom , Q H,10mm /N 10mm ) to visualize hot spot of 10 mm diameter with standardized uptake value (SUV)=4 explicitly. Simultaneously, Recovery Coefficient (RC) was evaluated to recognize that PET images had enough quantifiably. Scan durations were optimized by Body Mass Index (BMI) based on retrospective analysis of NEC density . Correlation between visual score in clinical FDG-PET images and NEC density fell after the optimization of scan duration. Both Inter-institution and inter-patient variability were decreased by performing the phantom study based on the procedure guideline and the optimization of scan duration based on NEC density which seem finally useful to practice highly precise examination and promote high-quality controlled study. (author)

  13. A comparative study of image low level feature extraction algorithms

    Directory of Open Access Journals (Sweden)

    M.M. El-gayar

    2013-07-01

    Full Text Available Feature extraction and matching is at the base of many computer vision problems, such as object recognition or structure from motion. Current methods for assessing the performance of popular image matching algorithms are presented and rely on costly descriptors for detection and matching. Specifically, the method assesses the type of images under which each of the algorithms reviewed herein perform to its maximum or highest efficiency. The efficiency is measured in terms of the number of matches founds by the algorithm and the number of type I and type II errors encountered when the algorithm is tested against a specific pair of images. Current comparative studies asses the performance of the algorithms based on the results obtained in different criteria such as speed, sensitivity, occlusion, and others. This study addresses the limitations of the existing comparative tools and delivers a generalized criterion to determine beforehand the level of efficiency expected from a matching algorithm given the type of images evaluated. The algorithms and the respective images used within this work are divided into two groups: feature-based and texture-based. And from this broad classification only three of the most widely used algorithms are assessed: color histogram, FAST (Features from Accelerated Segment Test, SIFT (Scale Invariant Feature Transform, PCA-SIFT (Principal Component Analysis-SIFT, F-SIFT (fast-SIFT and SURF (speeded up robust features. The performance of the Fast-SIFT (F-SIFT feature detection methods are compared for scale changes, rotation, blur, illumination changes and affine transformations. All the experiments use repeatability measurement and the number of correct matches for the evaluation measurements. SIFT presents its stability in most situations although its slow. F-SIFT is the fastest one with good performance as the same as SURF, SIFT, PCA-SIFT show its advantages in rotation and illumination changes.

  14. Comparative study of low-energy neutral atom imaging techniques

    International Nuclear Information System (INIS)

    Funsten, H.O.; McComas, D.J.; Scime, E.E.

    1994-01-01

    Low-energy neutral atom (LENA) imaging promise to be a revolutionary tool for global imaging of space plasmas. The technical challenges of LENA detection include separating them from the intense ambient UV without losing information about their incident trajectories, quantifying their trajectories, and obtaining high-sensitivity measurements. Two techniques that have been proposed for this purpose are based on fundamentally different atomic interaction mechanisms between LENAs and a solid; LENA transmission through an ultra thin foil and LENA reflection from a solid surface. Both of these methods provide LENA ionization (for subsequent removal from the UV by electrostatic deflection) and secondary electron emission (for time-of-flight start pulse generation and/or coincidence). They present a comparative study of the transmission and reflection techniques based on differences in atomic interactions with solids and surfaces. Transmission methods are shown to be superior for secondary electron emission rather than reflection methods. Furthermore, transmission methods are shown to be a sufficient for LENA imaging at LENA energies of approximately 1 keV to greater than 30 keV. A hybrid instrument using reflection from a low work function surface for LENA ionization and transmission for secondary electron emission is optimal for imaging of LENAs with energies less than approximately 1 keV

  15. Imaging Primary Lung Cancers in Mice to Study Radiation Biology

    International Nuclear Information System (INIS)

    Kirsch, David G.; Grimm, Jan; Guimaraes, Alexander R.; Wojtkiewicz, Gregory R.; Perez, Bradford A.; Santiago, Philip M.; Anthony, Nikolas K.; Forbes, Thomas; Doppke, Karen

    2010-01-01

    Purpose: To image a genetically engineered mouse model of non-small-cell lung cancer with micro-computed tomography (micro-CT) to measure tumor response to radiation therapy. Methods and Materials: The Cre-loxP system was used to generate primary lung cancers in mice with mutation in K-ras alone or in combination with p53 mutation. Mice were serially imaged by micro-CT, and tumor volumes were determined. A comparison of tumor volume by micro-CT and tumor histology was performed. Tumor response to radiation therapy (15.5 Gy) was assessed with micro-CT. Results: The tumor volume measured with free-breathing micro-CT scans was greater than the volume calculated by histology. Nevertheless, this imaging approach demonstrated that lung cancers with mutant p53 grew more rapidly than lung tumors with wild-type p53 and also showed that radiation therapy increased the doubling time of p53 mutant lung cancers fivefold. Conclusions: Micro-CT is an effective tool to noninvasively measure the growth of primary lung cancers in genetically engineered mice and assess tumor response to radiation therapy. This imaging approach will be useful to study the radiation biology of lung cancer.

  16. A phantom study of tumor contouring on PET imaging

    International Nuclear Information System (INIS)

    Chen Song; Li Xuena; Li Yaming; Yin Yafu; Li Na; Han Chunqi

    2010-01-01

    Objective: To explore an algorithm to define the threshold value for tumor contouring on 18 F-fluorodeoxyglucose (FDG) PET imaging. Methods: A National Electrical Manufacturing Association (NEMA)NU 2 1994 PET phantom with 5 spheres of different diameters were filled with 18 F-FDG. Seven different sphere-to-background ratios were obtained and the phantom was scanned by Discovery LS 4. For each sphere-to-background ratio, the maximum standardized uptake value (SUV max ) of each sphere, the SUV of the border of each sphere (SUV border ), the mean SUV of a 1 cm region of background (SUV bg ) and the diameter (D) of each sphere were measured. SPSS 13.0 software was used for curve fitting and regression analysis to obtain the threshold algorithm. The calculated thresholds were applied to delineate 29 pathologically confirmed lung cancer lesions on PET images and the obtained volumes were compared with the volumes contoured on CT images in lung window. Results: The algorithm for defining contour threshold is TH% = 33.1% + 46.8% SUV bg /SUV max + 13.9%/D (r = 0.994) by phantom studies. For 29 lung cancer lesions, the average gross tumor volumes (GTV) delineated on PET and CT are (7.36±1.62) ml and (8.31±2.05) ml, respectively (t = -1.26, P>0.05). Conclusion: The proposed threshold algorithm for tumor contouring on PET image could provide comparable GTV with CT. (authors)

  17. The experimental study of oxygen contrast MR ventilation imaging

    International Nuclear Information System (INIS)

    Yang Jian; Guo Youmin; Wu Xiaoming; Xi Nong; Wang Jianguo; Zhu Li; Lei Xiaoyan; Xie Enyi

    2003-01-01

    Objective: To study the feasibility and basic technology of the oxygen contrast MR ventilation imaging in lung. Methods: Six canine lungs were scanned by using inversion recovery pulse sequence with turbo spin echo acquisition before and after inhalation of the 100% oxygen as T 1 contrast agent, and the T 1 values were measured. The contrast-to-noise ratio (CNR) for each inversion recovery time was compared and the relationship between arterial blood oxygen pressure (PaO 2 ) and T 1 relaxation rate was observed. Subtraction technique was employed in the postprocessing of pre- and post-oxygen conditions. Results: Molecular oxygen could shorten the pulmonary T 1 value (average 13.37%, t=2.683, P 1 value of pre- and post-oxygen conditions. The relaxtivity of T 1 resulted in excellent linear correlation (r 2 =0.9974) with PaO 2 . Through the subtraction of pre- and post-oxygen image, the oxygen contrast MR ventilation -image was obtained. Conclusion: The oxygen contrast MR ventilation imaging has the feasibility and clinical potential for the assessment of regional pulmonary function

  18. AN IMAGING STUDY OF A COMPLEX SOLAR CORONAL RADIO ERUPTION

    Energy Technology Data Exchange (ETDEWEB)

    Feng, S. W.; Chen, Y.; Song, H. Q.; Wang, B.; Kong, X. L., E-mail: yaochen@sdu.edu.cn [Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, and Institute of Space Sciences, Shandong University, Weihai, Shandong 264209 (China)

    2016-08-10

    Solar coronal radio bursts are enhanced radio emission excited by energetic electrons accelerated during solar eruptions. Studying these bursts is important for investigating the origin and physical mechanism of energetic particles and further diagnosing coronal parameters. Earlier studies suffered from a lack of simultaneous high-quality imaging data of the radio burst and the eruptive structure in the inner corona. Here we present a study on a complex solar radio eruption consisting of a type II burst and three reversely drifting type III bursts, using simultaneous EUV and radio imaging data. It is found that the type II burst is closely associated with a propagating and evolving CME-driven EUV shock structure, originated initially at the northern shock flank and later transferred to the top part of the shock. This source transfer is coincident with the presence of shock decay and enhancing signatures observed at the corresponding side of the EUV front. The electron energy accelerated by the shock at the flank is estimated to be ∼0.3 c by examining the imaging data of the fast-drifting herringbone structure of the type II burst. The reverse-drifting type III sources are found to be within the ejecta and correlated with a likely reconnection event therein. The implications for further observational studies and relevant space weather forecasting techniques are discussed.

  19. A novel diagnostic aid for intra-abdominal adhesion detection in cine-MR imaging: Pilot study and initial diagnostic impressions.

    Science.gov (United States)

    Randall, David; Joosten, Frank; ten Broek, Richard; Gillott, Richard; Bardhan, Karna Dev; Strik, Chema; Prins, Wiesje; van Goor, Harry; Fenner, John

    2017-07-14

    A non-invasive diagnostic technique for abdominal adhesions is not currently available. Capture of abdominal motion due to respiration in cine-MRI has shown promise, but is difficult to interpret. This article explores the value of a complimentary diagnostic aid to facilitate the non-invasive detection of abdominal adhesions using cine-MRI. An image processing technique was developed to quantify the amount of sliding that occurs between the organs of the abdomen and the abdominal wall in sagittal cine-MRI slices. The technique produces a 'sheargram' which depicts the amount of sliding which has occurred over 1-3 respiratory cycles. A retrospective cohort of 52 patients, scanned for suspected adhesions, made 281 cine-MRI sagittal slices available for processing. The resulting sheargrams were reported by two operators and compared to expert clinical judgement of the cine-MRI scans. The sheargram matched clinical judgement in 84% of all sagittal slices and 93-96% of positive adhesions were identified on the sheargram. The sheargram displayed a slight skew towards sensitivity over specificity, with a high positive adhesion detection rate but at the expense of false positives. Good correlation between sheargram and absence/presence of inferred adhesions indicates quantification of sliding motion has potential to aid adhesion detection in cine-MRI. Advances in Knowledge: This is the first attempt to clinically evaluate a novel image processing technique quantifying the sliding motion of the abdominal contents against the abdominal wall. The results of this pilot study reveal its potential as a diagnostic aid for detection of abdominal adhesions.

  20. Detection of pulmonary nodules on lung X-ray images. Studies on multi-resolutional filter and energy subtraction images

    International Nuclear Information System (INIS)

    Sawada, Akira; Sato, Yoshinobu; Kido, Shoji; Tamura, Shinichi

    1999-01-01

    The purpose of this work is to prove the effectiveness of an energy subtraction image for the detection of pulmonary nodules and the effectiveness of multi-resolutional filter on an energy subtraction image to detect pulmonary nodules. Also we study influential factors to the accuracy of detection of pulmonary nodules from viewpoints of types of images, types of digital filters and types of evaluation methods. As one type of images, we select an energy subtraction image, which removes bones such as ribs from the conventional X-ray image by utilizing the difference of X-ray absorption ratios at different energy between bones and soft tissue. Ribs and vessels are major causes of CAD errors in detection of pulmonary nodules and many researches have tried to solve this problem. So we select conventional X-ray images and energy subtraction X-ray images as types of images, and at the same time select ∇ 2 G (Laplacian of Guassian) filter, Min-DD (Minimum Directional Difference) filter and our multi-resolutional filter as types of digital filters. Also we select two evaluation methods and prove the effectiveness of an energy subtraction image, the effectiveness of Min-DD filter on a conventional X-ray image and the effectiveness of multi-resolutional filter on an energy subtraction image. (author)

  1. A preliminary diffusional kurtosis imaging study of Parkinson disease: comparison with conventional diffusion tensor imaging

    Energy Technology Data Exchange (ETDEWEB)

    Kamagata, Koji; Kamiya, Kouhei; Suzuki, Michimasa; Hori, Masaaki; Yoshida, Mariko; Aoki, Shigeki [Juntendo University School of Medicine, Department of Radiology, Bunkyo-ku, Tokyo (Japan); Tomiyama, Hiroyuki; Hatano, Taku; Motoi, Yumiko; Hattori, Nobutaka [Juntendo University School of Medicine, Department of Neurology, Tokyo (Japan); Abe, Osamu [Nihon University School of Medicine, Department of Radiology, Tokyo (Japan); Shimoji, Keigo [National Center of Neurology and Psychiatry Hospital, Department of Radiology, Tokyo (Japan)

    2014-03-15

    Diffusional kurtosis imaging (DKI) is a more sensitive technique than conventional diffusion tensor imaging (DTI) for assessing tissue microstructure. In particular, it quantifies the microstructural integrity of white matter, even in the presence of crossing fibers. The aim of this preliminary study was to compare how DKI and DTI show white matter alterations in Parkinson disease (PD). DKI scans were obtained with a 3-T magnetic resonance imager from 12 patients with PD and 10 healthy controls matched by age and sex. Tract-based spatial statistics were used to compare the mean kurtosis (MK), mean diffusivity (MD), and fractional anisotropy (FA) maps of the PD patient group and the control group. In addition, a region-of-interest analysis was performed for the area of the posterior corona radiata and superior longitudinal fasciculus (SLF) fiber crossing. FA values in the frontal white matter were significantly lower in PD patients than in healthy controls. Reductions in MK occurred more extensively throughout the brain: in addition to frontal white matter, MK was lower in the parietal, occipital, and right temporal white matter. The MK value of the area of the posterior corona radiata and SLF fiber crossing was also lower in the PD group. DKI detects changes in the cerebral white matter of PD patients more sensitively than conventional DTI. In addition, DKI is useful for evaluating crossing fibers. By providing a sensitive index of brain pathology in PD, DKI may enable improved monitoring of disease progression. (orig.)