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Sample records for false-positive computed tomographic

  1. CT Colonography with Computer-aided Detection: Recognizing the Causes of False-Positive Reader Results

    PubMed Central

    Dachman, Abraham H.; Wroblewski, Kristen; Vannier, Michael W.; Horne, John M.

    2014-01-01

    Computed tomography (CT) colonography is a screening modality used to detect colonic polyps before they progress to colorectal cancer. Computer-aided detection (CAD) is designed to decrease errors of detection by finding and displaying polyp candidates for evaluation by the reader. CT colonography CAD false-positive results are common and have numerous causes. The relative frequency of CAD false-positive results and their effect on reader performance on the basis of a 19-reader, 100-case trial shows that the vast majority of CAD false-positive results were dismissed by readers. Many CAD false-positive results are easily disregarded, including those that result from coarse mucosa, reconstruction, peristalsis, motion, streak artifacts, diverticulum, rectal tubes, and lipomas. CAD false-positive results caused by haustral folds, extracolonic candidates, diminutive lesions (<6 mm), anal papillae, internal hemorrhoids, varices, extrinsic compression, and flexural pseudotumors are almost always recognized and disregarded. The ileocecal valve and tagged stool are common sources of CAD false-positive results associated with reader false-positive results. Nondismissable CAD soft-tissue polyp candidates larger than 6 mm are another common cause of reader false-positive results that may lead to further evaluation with follow-up CT colonography or optical colonoscopy. Strategies for correctly evaluating CAD polyp candidates are important to avoid pitfalls from common sources of CAD false-positive results. ©RSNA, 2014 PMID:25384290

  2. Computer-aided detection of lung nodules: false positive reduction using a 3D gradient field method

    NASA Astrophysics Data System (ADS)

    Ge, Zhanyu; Sahiner, Berkman; Chan, Heang-Ping; Hadjiiski, Lubomir M.; Wei, Jun; Bogot, Naama; Cascade, Philip N.; Kazerooni, Ella A.; Zhou, Chuan

    2004-05-01

    We are developing a computer-aided detection system to aid radiologists in diagnosing lung cancer in thoracic computed tomographic (CT) images. The purpose of this study was to improve the false-positive (FP) reduction stage of our algorithm by developing and incorporating a gradient field technique. This technique extracts 3D shape information from the gray-scale values within a volume of interest. The gradient field feature values are higher for spherical objects, and lower for elongated and irregularly-shaped objects. A data set of 55 thin CT scans from 40 patients was used to evaluate the usefulness of the gradient field technique. After initial nodule candidate detection and rule-based first stage FP reduction, there were 3487 FP and 65 true positive (TP) objects in our data set. Linear discriminant classifiers with and without the gradient field feature were designed for the second stage FP reduction. The accuracy of these classifiers was evaluated using the area Az under the receiver operating characteristic (ROC) curve. The Az values were 0.93 and 0.91 with and without the gradient field feature, respectively. The improvement with the gradient field feature was statistically significant (p=0.01).

  3. Computer-aided detection of breast masses on mammograms: bilateral analysis for false positive reduction

    NASA Astrophysics Data System (ADS)

    Wu, Yi-Ta; Hadjiiski, Lubomir M.; Wei, Jun; Zhou, Chuan; Sahiner, Berkman; Chan, Heang-Ping

    2006-03-01

    In this study, our purpose was to develop a false positive (FP) reduction method for computerized mass detection systems based on the analysis of bilateral mammograms. We first detect the mass candidates on each view by utilizing our unilateral computer-aided detection (CAD) system. For each detected object, the regional registration technique is used to define a region of interest (ROI) that is "symmetrical" to the object location on the contralateral mammogram. Spatial gray level dependence matrices (SGLD) texture features and morphological features are extracted from both the ROI containing the detected object on a mammogram and its corresponding ROI on the contralateral mammogram. Bilateral features are then generated from the extracted unilateral features and a final bilateral score is formed as a new feature to differentiate symmetric from asymmetric ROIs. By incorporating the unilateral features of the mass candidates and their bilateral scores, a bilateral classifier was trained to reduce the FPs. It was found that our bilateral CAD system achieved a case-based sensitivity of 70%, 80%, and 85% at 0.52, 0.83, and 1.05 FPs/image on the test data set. In comparison to the FP rates for the unilateral CAD system of 0.67, 1.11, and 1.69, respectively, at the corresponding sensitivities, the FP rates were reduced by 22%, 25%, and 37% with the bilateral symmetry information.

  4. A self-paced brain computer interface system with a low false positive rate

    NASA Astrophysics Data System (ADS)

    Fatourechi, M.; Ward, R. K.; Birch, G. E.

    2008-03-01

    The performance of current EEG-based self-paced brain-computer interface (SBCI) systems is not suitable for most practical applications. In this paper, an improved SBCI that uses features extracted from three neurological phenomena (movement-related potentials, changes in the power of Mu rhythms and changes in the power of Beta rhythms) to detect an intentional control command in noisy EEG signals is proposed. The proposed system achieves a high true positive (TP) to false positive (FP) ratio. To extract features for each neurological phenomenon in every EEG signal, a method that consists of a stationary wavelet transform followed by matched filtering is developed. For each neurological phenomenon in every EEG channel, features are classified using a support vector machine classifier (SVM). For each neurological phenomenon, a multiple classifier system (MCS) then combines the outputs of the SVMs. Another MCS combines the outputs of MCSs designed for the three neurological phenomena. Various configurations for combining the outputs of these MCSs are considered. A hybrid genetic algorithm (HGA) is proposed to simultaneously select the features, the values of the classifiers' parameters and the configuration for combining MCSs that yield the near optimal performance. Analysis of the data recorded from four able-bodied subjects shows a significant performance improvement over previous SBCIs.

  5. Computer-aided detection in digital mammography: false-positive marks and their reproducibility in negative mammograms.

    PubMed

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

    2009-11-01

    There are relatively few studies reporting the frequency of false-positive computer-aided detection (CAD) marks and their reproducibility in normal cases. 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. 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. 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. 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.

  6. Bilateral analysis based false positive reduction for computer-aided mass detection

    SciTech Connect

    Wu Yita; Wei Jun; Hadjiiski, Lubomir M.; Sahiner, Berkman; Zhou Chuan; Ge Jun; Shi Jiazheng; Zhang Yiheng; Chan Heangping

    2007-08-15

    We have developed a false positive (FP) reduction method based on analysis of bilateral mammograms for computerized mass detection systems. The mass candidates on each view were first detected by our unilateral computer-aided detection (CAD) system. For each detected object, a regional registration technique was used to define a region of interest (ROI) that is ''symmetrical'' to the object location on the contralateral mammogram. Texture features derived from the spatial gray level dependence matrices and morphological features were extracted from the ROI containing the detected object on a mammogram and its corresponding ROI on the contralateral mammogram. Bilateral features were then generated from corresponding pairs of unilateral features for each object. Two linear discriminant analysis (LDA) classifiers were trained from the unilateral and the bilateral feature spaces, respectively. Finally, the scores from the unilateral LDA classifier and the bilateral LDA asymmetry classifier were fused with a third LDA whose output score was used to distinguish true mass from FPs. A data set of 341 cases of bilateral two-view mammograms was used in this study, of which 276 cases with 552 bilateral pairs contained 110 malignant and 166 benign biopsy-proven masses and 65 cases with 130 bilateral pairs were normal. The mass data set was divided into two subsets for twofold cross-validation training and testing. The normal data set was used for estimation of FP rates. It was found that our bilateral CAD system achieved a case-based sensitivity of 70%, 80%, and 85% at average FP rates of 0.35, 0.75, and 0.95 FPs/image, respectively, on the test data sets with malignant masses. In comparison to the average FP rates for the unilateral CAD system of 0.58, 1.33, and 1.63, respectively, at the corresponding sensitivities, the FP rates were reduced by 40%, 44%, and 42% with the bilateral symmetry information. The improvement was statistically significance (p<0.05) as estimated by

  7. Bilateral analysis based false positive reduction for computer-aided mass detection.

    PubMed

    Wu, Yi-Ta; Wei, Jun; Hadjiiski, Lubomir M; Sahiner, Berkman; Zhou, Chuan; Ge, Jun; Shi, Jiazheng; Zhang, Yiheng; Chan, Heang-Ping

    2007-08-01

    We have developed a false positive (FP) reduction method based on analysis of bilateral mammograms for computerized mass detection systems. The mass candidates on each view were first detected by our unilateral computer-aided detection (CAD) system. For each detected object, a regional registration technique was used to define a region of interest (ROI) that is "symmetrical" to the object location on the contralateral mammogram. Texture features derived from the spatial gray level dependence matrices and morphological features were extracted from the ROI containing the detected object on a mammogram and its corresponding ROI on the contralateral mammogram. Bilateral features were then generated from corresponding pairs of unilateral features for each object. Two linear discriminant analysis (LDA) classifiers were trained from the unilateral and the bilateral feature spaces, respectively. Finally, the scores from the unilateral LDA classifier and the bilateral LDA asymmetry classifier were fused with a third LDA whose output score was used to distinguish true mass from FPs. A data set of 341 cases of bilateral two-view mammograms was used in this study, of which 276 cases with 552 bilateral pairs contained 110 malignant and 166 benign biopsy-proven masses and 65 cases with 130 bilateral pairs were normal. The mass data set was divided into two subsets for twofold cross-validation training and testing. The normal data set was used for estimation of FP rates. It was found that our bilateral CAD system achieved a case-based sensitivity of 70%, 80%, and 85% at average FP rates of 0.35, 0.75, and 0.95 FPs/image, respectively, on the test data sets with malignant masses. In comparison to the average FP rates for the unilateral CAD system of 0.58, 1.33, and 1.63, respectively, at the corresponding sensitivities, the FP rates were reduced by 40%, 44%, and 42% with the bilateral symmetry information. The improvement was statistically significance (p < 0.05) as estimated by

  8. Leiomyosarcoma: computed tomographic findings

    SciTech Connect

    McLeod, A.J.; Zornoza, J.; Shirkhoda, A.

    1984-07-01

    The computed tomographic (CT) findings in 118 patients with the diagnosis of leiomyosarcoma were reviewed. The tumor masses visualized in these patients were often quite large; extensive necrotic or cystic change was a frequent finding. Calcification was not observed in these tumors. The liver was the most common site of metastasis in these patients, with marked necrosis of the liver lesions a common finding. Other manifestations of tumor spread included pulmonary metastases, mesenteric or omental metastases, retroperitoneal lymphadenopathy, soft-tissue metastases, bone metastases, splenic metastases, and ascites. Although the CT appearance of leiomyosarcoma is not specific, these findings, when present, suggest consideration of this diagnosis.

  9. Application of computer-extracted breast tissue texture features in predicting false-positive recalls from screening mammography

    NASA Astrophysics Data System (ADS)

    Ray, Shonket; Choi, Jae Y.; Keller, Brad M.; Chen, Jinbo; Conant, Emily F.; Kontos, Despina

    2014-03-01

    Mammographic texture features have been shown to have value in breast cancer risk assessment. Previous models have also been developed that use computer-extracted mammographic features of breast tissue complexity to predict the risk of false-positive (FP) recall from breast cancer screening with digital mammography. This work details a novel locallyadaptive parenchymal texture analysis algorithm that identifies and extracts mammographic features of local parenchymal tissue complexity potentially relevant for false-positive biopsy prediction. This algorithm has two important aspects: (1) the adaptive nature of automatically determining an optimal number of region-of-interests (ROIs) in the image and each ROI's corresponding size based on the parenchymal tissue distribution over the whole breast region and (2) characterizing both the local and global mammographic appearances of the parenchymal tissue that could provide more discriminative information for FP biopsy risk prediction. Preliminary results show that this locallyadaptive texture analysis algorithm, in conjunction with logistic regression, can predict the likelihood of false-positive biopsy with an ROC performance value of AUC=0.92 (p<0.001) with a 95% confidence interval [0.77, 0.94]. Significant texture feature predictors (p<0.05) included contrast, sum variance and difference average. Sensitivity for false-positives was 51% at the 100% cancer detection operating point. Although preliminary, clinical implications of using prediction models incorporating these texture features may include the future development of better tools and guidelines regarding personalized breast cancer screening recommendations. Further studies are warranted to prospectively validate our findings in larger screening populations and evaluate their clinical utility.

  10. False-positive reduction using Hessian features in computer-aided detection of pulmonary nodules on thoracic CT images

    NASA Astrophysics Data System (ADS)

    Sahiner, Berkman; Ge, Zhanyu; Chan, Heang-Ping; Hadjiiski, Lubomir M.; Bogot, Naama; Cascade, Philip N.; Kazerooni, Ella A.

    2005-04-01

    We are developing a computer-aided detection (CAD) system for lung nodules in thoracic CT volumes. During false positive (FP) reduction, the image structures around the identified nodule candidates play an important role in differentiating nodules from vessels. In our previous work, we exploited shape and first-order derivative information of the images by extracting ellipsoid and gradient field features. The purpose of this study was to explore the object shape information using second-order derivatives and the Hessian matrix to further improve the performance of our detection system. Eight features related to the eigenvalues of the Hessian matrix were extracted from a volume of interest containing the object, and were combined with ellipsoid and gradient field features to discriminate nodules from FPs. A data set of 82 CT scans from 56 patients was used to evaluate the usefulness of the FP reduction technique. The classification accuracy was assessed using the area Az under the receiving operating characteristic curve and the number of FPs per section at 80% sensitivity. In the combined feature space, we obtained a test Az of 0.97 +/- 0.01, and 0.27 FPs/section at 80% sensitivity. Our results indicate that combining the Hessian, ellipsoid and gradient field features can significantly improve the performance of our FP reduction stage.

  11. Simplified false-positive reduction in computer-aided detection scheme of clustered microcalcifications in digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Jeong, Ji-Wook; Chae, Seung-Hoon; Lee, Sooyeul; Chae, Eun Young; Kim, Hak Hee; Choi, Young-Wook

    2015-03-01

    A computer-aided detection (CADe) system for clustered microcalcifications (MCs) in reconstructed digital breast tomosynthesis (DBT) volumes was suggested. The system consisted of prescreening, MC detecting, clustering, and falsepositive reduction steps. In the prescreening stage, the MC-like objects were enhanced by a multiscale-based 3D calcification response function. A connected component segmentation method was used to detect cluster seed objects, which were considered as potential clustering centers of MCs. Starting with each cluster seed object as the initial cluster center, a cluster candidate was formed by including nearby MC candidates within a 3D neighborhood of the cluster seed object satisfying the clustering criteria during the clustering step. The size and number of the clustered MCs in a cluster seed candidate were used to reduce the number of FPs. A bounding cube for each MCC was generated for each accepted seed candidates. Then, the overlapping cubes were combined and examined according to the FP reduction criteria. After FP reduction step, we obtained the average number of FPs of 2.47 per DBT volume with sensitivity of 83.3%. Our study indicates the simplified false-positive reduction approach applied to the detection of clustered MCs in DBT is promising as an efficient CADe system.

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

    SciTech Connect

    Masotti, Matteo; Lanconelli, Nico; Campanini, Renato

    2009-02-15

    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

  13. False-positive reduction in computer-aided diagnostic scheme for detecting nodules in chest radiographs by means of massive training artificial neural network.

    PubMed

    Suzuki, Kenji; Shiraishi, Junji; Abe, Hiroyuki; MacMahon, Heber; Doi, Kunio

    2005-02-01

    We developed a technique that uses a multiple massive-training artificial neural network (multi-MTANN) to reduce the number of false-positive results in a computer-aided diagnostic (CAD) scheme for detecting nodules in chest radiographs. Our database consisted of 91 solitary pulmonary nodules, including 64 malignant nodules and 27 benign nodules, in 91 chest radiographs. With our current CAD scheme based on a difference-image technique and linear discriminant analysis, we achieved a sensitivity of 82.4%, with 4.5 false positives per image. We developed the multi-MTANN for further reduction of the false positive rate. An MTANN is a highly nonlinear filter that can be trained with input images and corresponding teaching images. To reduce the effects of background levels in chest radiographs, we applied a background-trend-correction technique, followed by contrast normalization, to the input images for the MTANN. For enhancement of nodules, the teaching image was designed to contain the distribution for a "likelihood of being a nodule." Six MTANNs in the multi-MTANN were trained by using typical nodules and six different types of non-nodules (false positives). Use of the trained multi-MTANN eliminated 68.3% of false-positive findings with a reduction of one true-positive result. The false-positive rate of our original CAD scheme was improved from 4.5 to 1.4 false positives per image, at an overall sensitivity of 81.3%. Use of a multi-MTANN substantially reduced the false-positive rate of our CAD scheme for lung nodule detection on chest radiographs, while maintaining a level of sensitivity.

  14. Ovarian metastases: Computed tomographic appearances

    SciTech Connect

    Megibow, A.J.; Hulnick, D.H.; Bosniak, M.A.; Balthazar, E.J.

    1985-07-01

    Computed tomographic scans of 34 patients with ovarian metastases were reviewed to assess the radiographic appearances and to correlate these with the primary neoplasms. Primary neoplasms were located in the colon (20 patients), breast (six), stomach (five), small bowel (one), bladder (one), and Wilms tumor of the kidney (one). The radiographic appearance of the metastatic lesions could be described as predominantly cystic (14 lesions), mixed (12 lesions), or solid (seven lesions). The cystic and mixed lesions tended to be larger in overall diameter than the solid. The metastases from gastric carcinoma appeared solid in four of five cases. The metastases from the other neoplasms had variable appearances simulating primary ovarian carcinoma.

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

    PubMed Central

    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 18F-fluorodeoxyglucose positron emission tomography/computed tomography. PMID:26097425

  16. Computer-aided marginal artery detection on computed tomographic colonography

    NASA Astrophysics Data System (ADS)

    Wei, Zhuoshi; Yao, Jianhua; Wang, Shijun; Liu, Jiamin; Summers, Ronald M.

    2012-03-01

    Computed tomographic colonography (CTC) is a minimally invasive technique for colonic polyps and cancer screening. The marginal artery of the colon, also known as the marginal artery of Drummond, is the blood vessel that connects the inferior mesenteric artery with the superior mesenteric artery. The marginal artery runs parallel to the colon for its entire length, providing the blood supply to the colon. Detecting the marginal artery may benefit computer-aided detection (CAD) of colonic polyp. It can be used to identify teniae coli based on their anatomic spatial relationship. It can also serve as an alternative marker for colon localization, in case of colon collapse and inability to directly compute the endoluminal centerline. This paper proposes an automatic method for marginal artery detection on CTC. To the best of our knowledge, this is the first work presented for this purpose. Our method includes two stages. The first stage extracts the blood vessels in the abdominal region. The eigenvalue of Hessian matrix is used to detect line-like structures in the images. The second stage is to reduce the false positives in the first step. We used two different masks to exclude the false positive vessel regions. One is a dilated colon mask which is obtained by colon segmentation. The other is an eroded visceral fat mask which is obtained by fat segmentation in the abdominal region. We tested our method on a CTC dataset with 6 cases. Using ratio-of-overlap with manual labeling of the marginal artery as the standard-of-reference, our method yielded true positive, false positive and false negative fractions of 89%, 33%, 11%, respectively.

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

    ERIC Educational Resources Information Center

    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.

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

    ERIC Educational Resources Information Center

    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.

  19. The Kepler False Positive Table

    NASA Astrophysics Data System (ADS)

    Bryson, Steve; Kepler False Positive Working Group

    2015-01-01

    The Kepler Space Telescope has detected thousands of candidate exoplanets by observing transit signals in a sample of more than 190,000 stars. Many of these transit signals are false positives, defined as a transit-like signal that is not due to a planet orbiting the target star (or a bound companion if the target is a multiple-star system). Astrophysical causes of false positives include background eclipsing binaries, planetary transits not associated with the target star, and non-planetary eclipses of the target star by stellar companions. The fraction of Kepler planet candidates that are false positives ranges from about 10% at high Galactic latitudes to 40% at low Galactic latitudes. Creating a high-reliability planet candidate catalog for statistical studies such as occurrence rate calculations requires removing clearly identified false positives.The Kepler Object of Interest (KOI) catalog at the NExScI NASA Exoplanet Archive flags false positives, and will soon provide a high-level classification of false positives, but lacks detailed description of why a KOI was determined to be a false positive. The Kepler False Positive Working Group (FPWG) examines each false positive in detail to certify that it is correctly identified as a false positive, and determines the primary reason(s) a KOI is classified as a false positive. The work of the FPWG will be published as the Kepler False Positive Table, hosted at the NExScI NASA Exoplanet Archive.The Kepler False Positive Table provides detailed information on the evidence for background binaries, transits caused by stellar companions, and false alarms. In addition to providing insight into the Kepler false positive population, the false positive table gives information about the background binary population and other areas of astrophysical interest. Because a planet around a star not associated with the target star is considered a false positive, the false positive table likely contains further planet candidates

  20. Kepler Certified False Positive Table

    NASA Technical Reports Server (NTRS)

    Bryson, Stephen T.; Batalha, Natalie Marie; Colon, Knicole Dawn; Coughlin, Jeffrey Langer; Haas, Michael R.; Henze, Chris; Huber, Daniel; Morton, Tim; Rowe, Jason Frank; Mullally, Susan Elizabeth; hide

    2017-01-01

    This document describes the Kepler Certied False Positive table hosted at the Exoplanet Archive1, herein referred to as the CFP table. This table is the result of detailed examination by the Kepler False Positive Working Group (FPWG) of declared false positives in the Kepler Object of Interest (KOI) tables (see, for example, Batalha et al. (2012); Burke et al.(2014); Rowe et al. (2015); Mullally et al. (2015); Coughlin et al. (2015b)) at the Exoplanet Archive. A KOI is considered a false positive if it is not due to a planet orbiting the KOI's target star. The CFP table contains all KOIs in the Exoplanet Archive cumulative KOI table. The purpose of the CFP table is to provide a list of certified false positive KOIs. A KOI is certified as a false positive when, in the judgement of the FPWG, there is no plausible planetary interpretation of the observational evidence, which we summarize by saying that the evidence for a false positive is compelling. This certification process involves detailed examination using all available data for each KOI, establishing a high-reliability ground truth set. The CFP table can be used to estimate the reliability of, for example, the KOI tables which are created using only Kepler photometric data, so the disposition of individual KOIs may differ in the KOI and CFP tables. Follow-up observers may find the CFP table useful to avoid observing false positives.

  1. Filter-based feature selection and support vector machine for false positive reduction in computer-aided mass detection in mammograms

    NASA Astrophysics Data System (ADS)

    Nguyen, V. D.; Nguyen, D. T.; Nguyen, T. D.; Phan, V. A.; Truong, Q. D.

    2015-02-01

    In this paper, a method for reducing false positive in computer-aided mass detection in screening mammograms is proposed. A set of 32 features, including First Order Statistics (FOS) features, Gray-Level Occurrence Matrix (GLCM) features, Block Difference Inverse Probability (BDIP) features, and Block Variation of Local Correlation coefficients (BVLC) are extracted from detected Regions-Of-Interest (ROIs). An optimal subset of 8 features is selected from the full feature set by mean of a filter-based Sequential Backward Selection (SBS). Then, Support Vector Machine (SVM) is utilized to classify the ROIs into massive regions or normal regions. The method's performance is evaluated using the area under the Receiver Operating Characteristic (ROC) curve (AUC or AZ). On a dataset consisting about 2700 ROIs detected from mini-MIAS database of mammograms, the proposed method achieves AZ=0.938.

  2. High Energy Computed Tomographic Inspection of Munitions

    DTIC Science & Technology

    2016-11-01

    UNCLASSIFIED UNCLASSIFIED AD-E403 815 Technical Report AREIS-TR-16006 HIGH ENERGY COMPUTED TOMOGRAPHIC INSPECTION OF MUNITIONS...REPORT DATE (DD-MM-YYYY) November 2016 2. REPORT TYPE Final 3. DATES COVERED (From – To) 4. TITLE AND SUBTITLE HIGH ENERGY COMPUTED...otherwise be accomplished by other nondestructive testing methods. 15. SUBJECT TERMS Radiography High energy Computed tomography (CT

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

    PubMed

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

    2003-07-01

    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

  4. False positives in cancer epidemiology.

    PubMed

    McLaughlin, Joseph K; Tarone, Robert E

    2013-01-01

    A recent attempt to estimate the false-positive rate for cancer epidemiology studies is based on agents in International Agency for Research on Cancer (IARC) category 3 (agent not classifiable as to its carcinogenicity to humans) in the IARC Monographs Program. The estimation method is critiqued regarding biases caused by its reliance on the IARC classification criteria for assessing carcinogenic potential. The privileged position given to epidemiologic studies by the IARC criteria ensures that the percentage of positive epidemiologic studies for an agent will depend strongly on the IARC category to which the agent is assigned. Because IARC category 3 is composed of agents with the lowest-assessed carcinogenic potential to which the estimation approach in question could be applied, a spuriously low estimated false-positive rate was necessarily the outcome of this approach. Tendentious estimation approaches like that employed will by necessity produce spuriously low and misleading false positive rates. The recently reported estimates of the false-positive rate in cancer epidemiology are seriously biased and contribute nothing substantive to the literature on the very real problems related to false-positive findings in epidemiology.

  5. Computed tomographic findings in bilateral adrenal tuberculosis

    SciTech Connect

    Wilms, G.E.; Baert, A.L.; Kint, E.J.; Pringot, J.H.; Goddeeris, P.G.

    1983-03-01

    The computed tomographic (CT) features of bilateral adrenal tuberculosis are reported in two cases that demonstrate two typical different clinical and morphological manifestations of the disease. The incidence and CT appearance of adrenal tuberculosis are discussed, with emphasis on differential diagnosis.

  6. Computer-aided detection of breast masses in digital breast tomosynthesis (DBT): improvement of false positive reduction by optimization of object segmentation

    NASA Astrophysics Data System (ADS)

    Wei, Jun; Chan, Heang-Ping; Sahiner, Berkman; Hadjiiski, Lubomir M.; Helvie, Mark A.; Zhou, Chuan; Lu, Yao

    2011-03-01

    DBT is a promising new imaging modality that may improve the sensitivity and specificity for breast cancer detection. However, DBT could only provide quasi-3D information with limited resolution along the depth (Z) direction because tomosynthesis only has limited angular information for reconstruction. Our purpose of this study is to develop a mass segmentation method for a computer-aided detection system in DBT. A data set of 50 two-view DBTs was collected with a GE prototype system. We reconstructed the DBTs using a simultaneous algebraic reconstruction technique (SART). Mass candidates including true and false masses were identified by 3D gradient field analysis. Two-stage 3D clustering followed by active contour segmentation was applied to a volume of interest (VOI) at each candidate location. We compared a fixed-Z approach, in which the Z dimension of the VOI was pre-determined, to an adaptive-Z approach, in which Z was determined by the object diameter (D) on the X-Y plane obtained from the first-stage clustering. We studied the effect of Z ranging from D to D+8 slices, centered at the central slice, in the second stage. Features were extracted on the individual slices of the segmented 3D object and averaged over all slices for both approaches. Linear discriminant analysis with stepwise feature selection was trained with a leave-one-case-out method to differentiate true from false masses in each feature space. With proper optimization of the adaptive-Z approach, the classification accuracy was significantly improved (p<0.0001) in comparison with the fixed-Z approach. The improved differentiation of true from false masses will be useful for false positive reduction in an automated mass detection system.

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

    PubMed

    Suzuki, Kenji; Yoshida, Hiroyuki; Näppi, Janne; Dachman, Abraham H

    2006-10-01

    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

  8. Computed tomographic evaluation of laryngoceles

    SciTech Connect

    Silverman, P.M.; Korobkin, M.

    1982-10-01

    Computed tomography (CT) of the larynx was used in three patients with laryngoceles. One of the cases is described. CT was able to define the extent of the laryngocele more precisely than either clinical examination or conventional radiographic techniques.

  9. Fast tomographic reconstruction on multicore computers.

    PubMed

    Agulleiro, J I; Fernandez, J J

    2011-02-15

    Tomo3D implements a multithreaded vectorized approach to tomographic reconstruction that takes full advantage of the computer power in modern multicore computers. Full resolution tomograms are generated at high speed on standard computers with no special system requirements. Tomo3D has the most common reconstruction methods implemented, namely weighted Back-projection (WBP) and simultaneous iterative reconstruction technique (SIRT). It proves to be competitive with current graphic processor unit solutions in terms of processing time, in the order of a few seconds with WBP or minutes with SIRT. The program is compatible with standard packages, which easily allows integration in the electron tomography workflow.

  10. Massive-training support vector regression and Gaussian process for false-positive reduction in computer-aided detection of polyps in CT colonography.

    PubMed

    Xu, Jian-Wu; Suzuki, Kenji

    2011-04-01

    A massive-training artificial neural network (MTANN) has been developed for the reduction of false positives (FPs) in computer-aided detection (CADe) of polyps in CT colonography (CTC). A major limitation of the MTANN is the long training time. To address this issue, the authors investigated the feasibility of two state-of-the-art regression models, namely, support vector regression (SVR) and Gaussian process regression (GPR) models, in the massive-training framework and developed massive-training SVR (MTSVR) and massive-training GPR (MTGPR) for the reduction of FPs in CADe of polyps. The authors applied SVR and GPR as volume-processing techniques in the distinction of polyps from FP detections in a CTC CADe scheme. Unlike artificial neural networks (ANNs), both SVR and GPR are memory-based methods that store a part of or the entire training data for testing. Therefore, their training is generally fast and they are able to improve the efficiency of the massive-training methodology. Rooted in a maximum margin property, SVR offers excellent generalization ability and robustness to outliers. On the other hand, GPR approaches nonlinear regression from a Bayesian perspective, which produces both the optimal estimated function and the covariance associated with the estimation. Therefore, both SVR and GPR, as the state-of-the-art nonlinear regression models, are able to offer a performance comparable or potentially superior to that of ANN, with highly efficient training. Both MTSVR and MTGPR were trained directly with voxel values from CTC images. A 3D scoring method based on a 3D Gaussian weighting function was applied to the outputs of MTSVR and MTGPR for distinction between polyps and nonpolyps. To test the performance of the proposed models, the authors compared them to the original MTANN in the distinction between actual polyps and various types of FPs in terms of training time reduction and FP reduction performance. The authors' CTC database consisted of 240 CTC

  11. Massive-training support vector regression and Gaussian process for false-positive reduction in computer-aided detection of polyps in CT colonography

    PubMed Central

    Xu, Jian-Wu; Suzuki, Kenji

    2011-01-01

    Purpose: A massive-training artificial neural network (MTANN) has been developed for the reduction of false positives (FPs) in computer-aided detection (CADe) of polyps in CT colonography (CTC). A major limitation of the MTANN is the long training time. To address this issue, the authors investigated the feasibility of two state-of-the-art regression models, namely, support vector regression (SVR) and Gaussian process regression (GPR) models, in the massive-training framework and developed massive-training SVR (MTSVR) and massive-training GPR (MTGPR) for the reduction of FPs in CADe of polyps. Methods: The authors applied SVR and GPR as volume-processing techniques in the distinction of polyps from FP detections in a CTC CADe scheme. Unlike artificial neural networks (ANNs), both SVR and GPR are memory-based methods that store a part of or the entire training data for testing. Therefore, their training is generally fast and they are able to improve the efficiency of the massive-training methodology. Rooted in a maximum margin property, SVR offers excellent generalization ability and robustness to outliers. On the other hand, GPR approaches nonlinear regression from a Bayesian perspective, which produces both the optimal estimated function and the covariance associated with the estimation. Therefore, both SVR and GPR, as the state-of-the-art nonlinear regression models, are able to offer a performance comparable or potentially superior to that of ANN, with highly efficient training. Both MTSVR and MTGPR were trained directly with voxel values from CTC images. A 3D scoring method based on a 3D Gaussian weighting function was applied to the outputs of MTSVR and MTGPR for distinction between polyps and nonpolyps. To test the performance of the proposed models, the authors compared them to the original MTANN in the distinction between actual polyps and various types of FPs in terms of training time reduction and FP reduction performance. The authors’ CTC database

  12. False positive reduction for lung nodule CAD

    NASA Astrophysics Data System (ADS)

    Zhao, Luyin; Boroczky, Lilla; Drysdale, Jeremy; Agnihotri, Lalitha; Lee, Michael C.

    2007-03-01

    Computer-aided detection (CAD) algorithms 'automatically' identify lung nodules on thoracic multi-slice CT scans (MSCT) thereby providing physicians with a computer-generated 'second opinion'. While CAD systems can achieve high sensitivity, their limited specificity has hindered clinical acceptance. To overcome this problem, we propose a false positive reduction (FPR) system based on image processing and machine learning to reduce the number of false positive lung nodules identified by CAD algorithms and thereby improve system specificity. To discriminate between true and false nodules, twenty-three 3D features were calculated from each candidate nodule's volume of interest (VOI). A genetic algorithm (GA) and support vector machine (SVM) were then used to select an optimal subset of features from this pool of candidate features. Using this feature subset, we trained an SVM classifier to eliminate as many false positives as possible while retaining all the true nodules. To overcome the imbalanced nature of typical datasets (significantly more false positives than true positives), an intelligent data selection algorithm was designed and integrated into the machine learning framework, thus further improving the FPR rate. Three independent datasets were used to train and validate the system. Using two datasets for training and the third for validation, we achieved a 59.4% FPR rate while removing one true nodule on the validation datasets. In a second experiment, 75% of the cases were randomly selected from each of the three datasets and the remaining cases were used for validation. A similar FPR rate and true positive retention rate was achieved. Additional experiments showed that the GA feature selection process integrated with the proposed data selection algorithm outperforms the one without it by 5%-10% FPR rate. The methods proposed can be also applied to other application areas, such as computer-aided diagnosis of lung nodules.

  13. Cranial computed tomographic abnormalities in leptomeningeal metastasis

    SciTech Connect

    Lee, Y.Y.; Glass, J.P.; Geoffray, A.; Wallace, S.

    1984-11-01

    Sixty-four (57.6%) of 111 cancer patients with cerebrospinal fluid cytology positive for malignant cells had cranial computed tomographic (CT) scans within 2 weeks before or after a lumbar puncture. Twenty-two (34.3%) of the 64 had abnormal CT findings indicative of leptomeningeal metastasis. Thirteen (59.6%) of these 22 patients had associated parenchymal metastases. Recognition of leptomeningeal disease may alter the management of patients with parenchymal metastases. Communicating hydrocephalus in cancer patients should be considered to be related to leptomeningeal metastasis until proven otherwise.

  14. Computed Tomographic Angiography of the Abdominal Aorta.

    PubMed

    Hansen, Neil J

    2016-01-01

    Computed tomographic (CT) angiography (CTA) has become the preferred imaging test of choice for various aortic conditions because of its excellent spatial resolution, rapid image acquisition, and its wide availability. CTA provides a robust tool for planning aortic interventions and diagnosing acute and chronic vascular diseases in the abdomen. CTA is the standard for imaging aneurysms before intervention and evaluating the aorta in the acute setting to assess traumatic injury, dissection, and aneurysm rupture. Knowledge of the imaging features of these disease processes, inflammatory vasculitides, and occlusive atherosclerotic disease is essential for guiding surgical and medical management of patients.

  15. Jugular foramen: anatomic and computed tomographic study

    SciTech Connect

    Daniels, D.L.; Williams, A.L.; Haughton, V.M.

    1984-01-01

    The computed tomographic (CT) appearance of the jugular foramen was examined in detail, and anatomic and CT sections were correlated. The pars nervosa and pars vascularis were identified, and, with intravenous contrast enhancement, a rapid sequence of scans at a gantry angle of +30/sup 0/ to the canthomeatal line demonstrated cranial nerves IX, X, and XI. The osseous margins of the jugular foramen were best shown by CT at planes of sections parallel and positive (0/sup 0/-30/sup 0/) to the canthomeatal line. CT can be used to evaluate osseous anatomy and the jugular foramen with precision sufficient to confidently exclude an intracanalicular mass.

  16. [Computer-tomographic cisternography with amipaque].

    PubMed

    Kornienko, V N; Saakian, O A

    1984-01-01

    As compared to ordinary computer tomography, computer-aided tomographic cisternography (CTC) demonstrates better the anatomy of the brain cisterns and at the same time gives an idea of the processes of c.s.f. circulation in dynamic examination. The article discusses the results of examination of 112 patients with various neurosurgical diseases by means of CTC. A detailed classification of the brain cisterns is given. The authors show the advantages of the method in examination of patients with small three-dimentional processes in the chiasma-sellar region, cerebellopontine angle, and posterior cranial fossa, with the syndrome of an "empty" sella turcica, cystic structures, and disorders of c.s.f. circulation.

  17. Computed tomographic appearance of resectable pancreatic carcinoma

    SciTech Connect

    Itai, Y.; Araki, T.; Tasaka, A.; Maruyama, M.

    1982-06-01

    Thirteen patients with resectable pancreatic carcinoma were examined by computed tomography (CT). Nine had a mass, 2 had dilatation of the main pancreatic duct, 1 appeared to have ductal dilatation, and 1 had no sign of abnormality. Resectable carcinoma was diagnosed retrospectively in 8 cases, based on the following criteria: a mass with a distinct contour, frequently containing a tiny or irregular low-density area and accompanied by dilatation of the caudal portion of the main pancreatic duct without involvement of the large vessels, liver, or lymph nodes. Including unresectable cancer, chronic pancreatitis, and obstructive jaundice from causes other than cancer, the false-positive rate was less than 6%. However, a small cancer without change in pancreatic contour is difficult to detect with CT.

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Computed tomographic analysis of meteorite inclusions

    NASA Technical Reports Server (NTRS)

    Arnold, J. R.; Testa, J. P., Jr.; Friedman, P. J.; Kambic, G. X.

    1983-01-01

    The feasibility of obtaining nondestructively a cross-sectional display of very dense heterogeneous rocky specimens, whether lunar, terrestrial or meteoritic, by using a fourth generation computed tomographic (CT) scanner, with modifications to the software only, is discussed. A description of the scanner, and of the experimental and analytical procedures is given. Using this technique, the interior of heterogeneous materials such as Allende can be probed nondestructively. The regions of material with high and low atomic numbers are displayed quickly; the object can then be cut to obtain for analysis just the areas of interest. A comparison of this technique with conventional industrial and medical techniques is made in terms of image resolution and density distribution display precision.

  20. Computed tomographic analysis of meteorite inclusions

    NASA Technical Reports Server (NTRS)

    Arnold, J. R.; Testa, J. P., Jr.; Friedman, P. J.; Kambic, G. X.

    1983-01-01

    The feasibility of obtaining nondestructively a cross-sectional display of very dense heterogeneous rocky specimens, whether lunar, terrestrial or meteoritic, by using a fourth generation computed tomographic (CT) scanner, with modifications to the software only, is discussed. A description of the scanner, and of the experimental and analytical procedures is given. Using this technique, the interior of heterogeneous materials such as Allende can be probed nondestructively. The regions of material with high and low atomic numbers are displayed quickly; the object can then be cut to obtain for analysis just the areas of interest. A comparison of this technique with conventional industrial and medical techniques is made in terms of image resolution and density distribution display precision.

  1. Computed tomographic recognition of gastric varices

    SciTech Connect

    Balthazar, E.J.; Megibow, A.; Naidich, D.; LeFleur, R.S.

    1984-06-01

    The computed tomographic (CT) findings in 13 consecutive patients with proven gastric varices were analyzed and correlated with the radiographic, angiographic, and gastroscopic evaluations. In 11 patients, CT clearly identified large (five) or smaller (six) varices located mainly along the posteromedial wall of the gastric fundus and proximal body of the stomach. Well defined rounded or tubular densities that enhanced during intravenous administration of contrast material and could not be distinguished from the gastric wall were identified. Dense, enhancing, round or tubular, intraluminal filling defects were seen in the cases where the stomach was distended with water. In seven patients, the CT examination correctly diagnosed the pathogenesis of gastric varices by identifying hepatic cirrhosis, calcific pancreatis, and carcinoma of the pancreas.

  2. Prognostic utility of coronary computed tomographic angiography

    PubMed Central

    Otaki, Yuka; Berman, Daniel S.; Min, James K.

    2013-01-01

    Coronary computed tomographic angiography (CCTA) employing CT scanners of 64-detector rows or greater represents a noninvasive method that enables accurate detection and exclusion of anatomically obstructive coronary artery disease (CAD), providing excellent diagnostic information when compared to invasive angiography. There are numerous potential advantages of CCTA beyond simply luminal stenosis assessment including quantification of atherosclerotic plaque volume as well as assessment of plaque composition, extent, location and distribution. In recent years, an array of studies has evaluated the prognostic utility of CCTA findings of CAD for the prediction of major adverse cardiac events, all-cause death and plaque instability. This prognostic information enhances risk stratification and, if properly acted upon, may improve medical therapy and/or behavioral changes that may enhance event-free survival. The goal of the present article is to summarize the current status of the prognostic utility of CCTA findings of CAD. PMID:23809386

  3. A Metric for Reducing False Positives in the Computer-Aided Detection of Breast Cancer from Dynamic Contrast-Enhanced Magnetic Resonance Imaging Based Screening Examinations of High-Risk Women.

    PubMed

    Levman, Jacob E D; Gallego-Ortiz, Cristina; Warner, Ellen; Causer, Petrina; Martel, Anne L

    2016-02-01

    Magnetic resonance imaging (MRI)-enabled cancer screening has been shown to be a highly sensitive method for the early detection of breast cancer. Computer-aided detection systems have the potential to improve the screening process by standardizing radiologists to a high level of diagnostic accuracy. This retrospective study was approved by the institutional review board of Sunnybrook Health Sciences Centre. This study compares the performance of a proposed method for computer-aided detection (based on the second-order spatial derivative of the relative signal intensity) with the signal enhancement ratio (SER) on MRI-based breast screening examinations. Comparison is performed using receiver operating characteristic (ROC) curve analysis as well as free-response receiver operating characteristic (FROC) curve analysis. A modified computer-aided detection system combining the proposed approach with the SER method is also presented. The proposed method provides improvements in the rates of false positive markings over the SER method in the detection of breast cancer (as assessed by FROC analysis). The modified computer-aided detection system that incorporates both the proposed method and the SER method yields ROC results equal to that produced by SER while simultaneously providing improvements over the SER method in terms of false positives per noncancerous exam. The proposed method for identifying malignancies outperforms the SER method in terms of false positives on a challenging dataset containing many small lesions and may play a useful role in breast cancer screening by MRI as part of a computer-aided detection system.

  4. Computed tomographic anatomy of the equine foot.

    PubMed

    Claerhoudt, S; Bergman, E H J; Saunders, J H

    2014-10-01

    This study describes a detailed computed tomographic reference of the normal equine foot. Ten forefeet of five adult cadavers, without evidence of orthopaedic disease, were used. Computed tomography (CT) was performed on all feet. Two-millimetre thick transverse slices were obtained, and sagittal and dorsal planes were reformatted. The CT images were matched with the corresponding anatomic slices. The phalanges and the distal sesamoid bone showed excellent detail. The extensor and flexor tendons (including their attachments) could be clearly evaluated. The collateral (sesamoidean) ligaments could be readily located, but were difficult to delineate at their proximal attachment. The distal digital annular ligament could only be distinguished from the deep digital flexor tendon proximal to the distal sesamoid bone, and its proximal attachment could be identified, but not its distal insertion. Small ligaments (impar ligament, chondrosesamoidean, chondrocoronal and chondrocompedal ligaments, axial and abaxial palmar ligaments of the proximal inter-phalangeal joint) were seen with difficulty and not at all slices. The joint capsules could not be delineated from the surrounding soft tissue structures. The lateral and medial proprius palmar digital artery and vein could be visualized occasionally on some slices. The ungular cartilages, corium and hoof wall layering were seen. The nerves, the articular and fibrocartilage of the distal sesamoid bone and the chondroungular ligament could not be assessed. Computed tomography of the equine foot can be of great value when results of radiography and ultrasonography are inconclusive. Images obtained in this study may serve as reference for CT of the equine foot.

  5. Computed tomographic imaging of stapes implants.

    PubMed

    Warren, Frank M; Riggs, Sterling; Wiggins, Richard H

    2008-08-01

    Computed tomographic (CT) imaging of stapes prostheses is inaccurate. Clinical situations arise in which it would be helpful to determine the depth of penetration of a stapes prosthesis into the vestibule. The accuracy of CT imaging for this purpose has not been defined. This study was aimed to determine the accuracy of CT imaging to predict the depth of intrusion of stapes prostheses into the vestibule. The measurement of stapes prostheses by CT scan was compared with physical measurements in 8 cadaveric temporal bones. The depth of intrusion into the vestibule of the piston was underestimated in specimens with the fluoroplastic piston by a mean of 0.5 mm when compared with the measurements obtained in the temporal bones. The depth of penetration of the stainless steel implant was overestimated by 0.5 mm when compared with that in the temporal bone. The type of implant must be taken into consideration when estimating the depth of penetration into the vestibule using CT scanning because the imaging characteristics of the implanted materials differ. The position of fluoroplastic pistons cannot be accurately measured in the vestibule. Metallic implants are well visualized, and measurements exceeding 2.2 mm increase the suspicion of otolithic impingement. Special reconstructions along the length of the piston may be more accurate in estimating the position of stapes implants.

  6. Computed tomographic findings in orbital Mucor

    SciTech Connect

    Greenberg, M.R.; Lippman, S.M.; Grinnell, V.S.; Colman, M.F.; Edwards, J.E. Jr.

    1985-07-01

    Mucormycosis is an increasingly important infection in immunocompromised patients; knowledge regarding the variability of its clinical manifestations is expanding steadily. The infection is of paranasal sinus origin and may involve the orbit secondarily via freely communicating foramina and venous channels. Death often ensues when the infection spreads either into the cavernous sinus or the central nervous system. Early diagnosis of rhinocerebral mucormycosis is crucial for a successful outcome. Computed tomographic (CT) scanning is used to visualize many intraorbital pathologic abnormalities. The patient discussed in this paper had extensive orbital Mucor that appeared minimal on a CT scan. This inability of the scan to reflect the severity of infection prompted a review of the literature describing the use of CT scans for detecting this potentially fatal, opportunistic infection. The search showed that a disparity between scan findings and the severity of the disease is the rule rather than the exception. Recognition of this disparity has significant implications for appropriate diagnosis and management of orbital Mucor.

  7. Computed tomographic versus catheterization angiography in tetralogy of Fallot.

    PubMed

    Garg, Naveen; Walia, Rohit; Neyaz, Zafar; Kumar, Sunil

    2015-02-01

    To compare multidetector computed tomographic angiography with the gold standard cardiac catheterization and angiography in tetralogy of Fallot. In 40 consecutive patients over 5 years of age with tetralogy of Fallot, multidetector computed tomographic angiography and catheterization angiography studies were compared for intracardiac anatomy, pulmonary anatomy and indices, coronaries and collaterals. Safety parameters, relative advantages and limitations were also analyzed. All catheterization studies required hospitalization whereas all tomographic studies were performed as outpatient procedures. The need for sedation and amount of contrast used were significantly greater in catheterization than in tomographic studies. Complications noted during catheterization were access site complications in 4 patients, cyanotic spells in 2, transient complete heart block requiring temporary pacing in 2, and air embolism in one. No complication was observed during tomographic studies. All tomographic studies were adequate, but 2 catheterization studies were inadequate. Ventricular septal defects, aortic override, level of right ventricular outflow tract obstruction, and pulmonary artery anatomy were equally assessed by both imaging modalities. However, tomographic studies missed additional small muscular ventricular septal defects. There was a linear correlation between tomographic and catheterization studies for pulmonary annulus size, artery sizes, Z-score, and Nakata index. There was complete concordance with respect to side of aortic arch and detection of collaterals. Coronary anatomy was better delineated in tomographic studies. For preoperative evaluation of tetralogy of Fallot patients, multidetector computed tomographic angiography can be used as a reliable noninvasive alternative to cardiac catheterization angiography. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  8. Computed tomographic features of feline nasopharyngeal polyps.

    PubMed

    Oliveira, Cintia R; O'Brien, Robert T; Matheson, Jodi S; Carrera, Inés

    2012-01-01

    The computed tomographic (CT) findings of histopathologically confirmed nasopharyngeal polyps are described in 13 cats. Most polyps were mildly hypoattenuating to adjacent muscles and isoattenuating to soft-tissue (n= 13), homogeneous (n = 12) and with ill-defined borders (n = 10) on precontrast images. After contrast medium administration, the polyps were homogeneous (n = 11), with well-defined borders (n = 13), oval (n = 13), and had rim enhancement (n = 13). Nasopharyngeal polyps were pedunculated in 11 cats with a stalk-like structure connecting the polyp through the auditory tube to an affected tympanic bulla. All cats had at least one tympanic bulla severely affected, with CT images identifying: (1) complete (n = 12) or partial (n = 1) obliteration of either the dorsal or ventral compartments with soft-tissue attenuating material; (2) pathologic expansion (n = 13) with wall thickening (n = 10) that was asymmetric in nine cats; and (3) identification of a polyp-associated stalk-like structure (n = 11). Nine cats had unilateral tympanic bulla disease ipsilateral to the polyp, and four cats had bilateral tympanic bulla disease, most severe ipsilateral to the polyp with milder contralateral pathologic changes. Two cats had minimal osteolysis of the tympanic bulla. Enlargement of the medial retropharyngeal lymph node was seen commonly (n = 8), and in all cats it was ipsilateral to the most affected tympanic bulla. One cat had bilateral lymphadenopathy. CT is an excellent imaging tool for the supportive diagnosis of nasopharyngeal polyps in cats. CT findings of a well-defined mass with strong rim enhancement, mass-associated stalk-like structure, and asymmetric tympanic bulla wall thickening with pathologic expansion of the tympanic bullae are highly indicative of an inflammatory polyp.

  9. Consequences of false-positive screening mammograms.

    PubMed

    Tosteson, Anna N A; Fryback, Dennis G; Hammond, Cristina S; Hanna, Lucy G; Grove, Margaret R; Brown, Mary; Wang, Qianfei; Lindfors, Karen; Pisano, Etta D

    2014-06-01

    False-positive mammograms, a common occurrence in breast cancer screening programs, represent a potential screening harm that is currently being evaluated by the US Preventive Services Task Force. To measure the effect of false-positive mammograms on quality of life by measuring personal anxiety, health utility, and attitudes toward future screening. The Digital Mammographic Imaging Screening Trial (DMIST) quality-of-life substudy telephone survey was performed shortly after screening and 1 year later at 22 DMIST sites and included randomly selected DMIST participants with positive and negative mammograms. Mammogram requiring follow-up testing or referral without a cancer diagnosis. The 6-question short form of the Spielberger State-Trait Anxiety Inventory state scale (STAI-6) and the EuroQol EQ-5D instrument with US scoring. Attitudes toward future screening as measured by women's self-report of future intention to undergo mammographic screening and willingness to travel and stay overnight to undergo a hypothetical new type of mammography that would identify as many cancers with half the false-positive results. Among 1450 eligible women invited to participate, 1226 (84.6%) were enrolled, with follow-up interviews obtained in 1028 (83.8%). Anxiety was significantly higher for women with false-positive mammograms (STAI-6, 35.2 vs 32.7), but health utility scores did not differ and there were no significant differences between groups at 1 year. Future screening intentions differed by group (25.7% vs 14.2% more likely in false-positive vs negative groups); willingness to travel and stay overnight did not (9.9% vs 10.5% in false-positive vs negative groups). Future screening intention was significantly increased among women with false-positive mammograms (odds ratio, 2.12; 95% CI, 1.54-2.93), younger age (2.78; 1.5-5.0), and poorer health (1.63; 1.09-2.43). Women's anticipated high-level anxiety regarding future false-positive mammograms was associated with willingness

  10. Consequences of False-Positive Screening Mammograms

    PubMed Central

    Tosteson, Anna N. A.; Fryback, Dennis G.; Hammond, Cristina S.; Hanna, Lucy G.; Grove, Margaret R.; Brown, Mary; Wang, Qianfei; Lindfors, Karen; Pisano, Etta D.

    2014-01-01

    Importance False-positive mammograms, a common occurrence in breast cancer screening programs, represent a potential screening harm that is currently being evaluated by the United States Preventive Services Task Force. Objective To measure the impact of false-positive mammograms on quality of life by measuring personal anxiety, health utility and future screening attitudes. Design Longitudinal Digital Mammographic Imaging Screening Trial (DMIST) quality-of-life sub-study telephone survey shortly after screening and one year later. Setting Twenty-two DMIST sites Participants Randomly-selected DMIST participants with positive and negative mammograms. Exposure(s) for observational studies Mammogram requiring follow-up testing or referral without a cancer diagnosis. Main Outcome(s) and Measure(s) The Spielberger State-Trait Anxiety Index short-form (STAI-6) and the EuroQol EQ-5D with United States scoring. Attitudes toward future screening measured by women’s self-report of future intention to undergo mammography screening and willingness to travel and stay overnight to receive a hypothetical new mammogram that would detect as many cancers with half the false-positives. Results Among 1,450 eligible women invited to participate, 1,226 women (85%) were enrolled with follow-up interviews obtained for 1,028 (84%). Anxiety was significantly higher for women with false-positive mammograms (STAI-6:35.2 vs. 32.7), but health utility did not differ and there were no significant differences between groups at one year. Future screening intentions differed by group (26% vs. 14% more likely in false-positive vs. negative); willingness to travel and stay overnight did not (11% vs. 10% in false-positive vs. negative). Future screening intention was significantly increased among women with false-positive mammograms (OR: 2.12; 95%CI:1.54, 2.93), younger age (OR:2.78; 95%CI:1.5,5.0) and poorer health (OR: 1.63; 95%CI:1.09, 2.43). Women’s anticipated high-level anxiety regarding

  11. False Positive Mammograms and Detection Controlled Estimation

    PubMed Central

    Kleit, Andrew N; Ruiz, James F

    2003-01-01

    Objective To investigate the causes of false positive in mammograms. Data Sources Secondary data collected from extracts from computerized medical records from 1999 from five thousand patients at a single hospital in a medium-sized Southern city. Study Design Retrospective analysis of electronic medical data on screening and diagnostic mammograms. Detection-controlled estimation (DCE) was used to compare the efficacy of alternative readers of mammogram films. Analysis was also conducted on follow-up exams of women who tested positive in the first stage of investigation. Key variables included whether the patient had had a prior mammogram, age of the patient, and identifiers for the individual physicians. Data Collection/Extraction Methods Hospital maintains electronic medical records (EMR) on all patients. Extracts were performed on this EMR system under the guidance of clinical expertise. Data were collected for all women who had mammograms in 1999. Random samples were employed for screening mammograms, and all data was used for diagnostic mammograms. Principal Findings Study results imply that access to a previous mammogram greatly reduces the incidence of false positives readings. This has important consequences for benefit-cost, and cost-effectiveness analysis of mammography. Were previous mammograms always available, the results imply the number of false positives would decrease by at least half. The results here also indicate that there is no reason to believe this decrease in false positive would be accompanied by an increase in the number of false negatives. Other attributes also affected the number of false positives. Mondays and Wednesdays appear to be more prone to false positives than the other days in the week. There is also some disparity in false positive outcomes among the five physicians studied. With respect to detection-controlled estimation, the results are mixed. With follow-up data, the DCE estimator appears to generate reasonable, robust

  12. A COMPUTED TOMOGRAPHIC STUDY OF SCHIZOPHRENIA

    PubMed Central

    Siddharatha; Lal, Narottam; Tewari, S.C.; Dalal, P.K.; Kohli, Neera; Srivastava, Shrikant

    1997-01-01

    Fifty schizophrenic patients fulfilling DSM-III-R criteria, and group matched normal healthy controls were selected for the study The case and control groups have been compared in terms of VBR, WSF and WTF. In the study schizophrenics have been divided into positive, negative and mixed subgroups on basis of SAPS and SANS, and these subgroups are compared with each other for VBR, WSF & WTF. Tomographic abnormalities were noted in schizophrenics, particularly with negative and mixed subtypes, when compared to controls. PMID:21584057

  13. Soil structure characterized using computed tomographic images

    Treesearch

    Zhanqi Cheng; Stephen H. Anderson; Clark J. Gantzer; J. W. Van Sambeek

    2003-01-01

    Fractal analysis of soil structure is a relatively new method for quantifying the effects of management systems on soil properties and quality. The objective of this work was to explore several methods of studying images to describe and quantify structure of soils under forest management. This research uses computed tomography and a topological method called Multiple...

  14. Computed tomographic findings in penetrating peptic ulcer

    SciTech Connect

    Madrazo, B.L.; Halpert, R.D.; Sandler, M.A.; Pearlberg, J.L.

    1984-12-01

    Four cases of peptic ulcer penetrating the head of the pancreas were diagnosed by computed tomography (CT). Findings common to 3 cases included (a) an ulcer crater, (b) a sinus tract, and (c) enlargement of the head of the pancreas. Unlike other modalities, the inherent spatial resolution of CT allows a convenient diagnosis of this important complication of peptic ulcer disease.

  15. Computed tomographic findings in 15 dogs with eosinophilic bronchopneumopathy.

    PubMed

    Mesquita, Luis; Lam, Richard; Lamb, Christopher R; McConnell, J Fraser

    2015-01-01

    Eosinophilic bronchopneumopathy is a disease characterized by the infiltration of the lung and bronchial mucosa by eosinophils. The aim of the present study was to describe the CT findings in a large series of dogs with confirmed diagnosis of eosinophilic bronchopneumopathy. Computed tomographic scans of 15 dogs with confirmed diagnosis of eosinophilic bronchopneumopathy were evaluated retrospectively by two boarded radiologists who reached a consensus. Abnormalities were identified in 14/15 (93%) dogs, including pulmonary parenchymal abnormalities in 14/15 (93%) dogs, bronchial wall thickening in 13 (87%) dogs, which was considered marked in eight (53%), plugging of the bronchial lumen by mucus/debris in 11 (73%) dogs, and bronchiectasis in nine (60%) dogs. Pulmonary nodules were identified in 5/15 (33%) dogs including one dog with a mass. All dogs with a nodular lung pattern had additional abnormalities. Lymphadenopathy was present in 10 dogs (67%). Lesions associated with eosinophilic bronchopneumopathy are variable and heterogeneous and encompass a wider variety of computed tomographic features than reported previously. Computed tomographic images were abnormal in the majority of affected dogs, hence CT is a useful modality to characterize the nature and distribution of thoracic lesions in dogs with eosinophilic bronchopneumopathy.

  16. Computed tomographic findings in Peyronie's disease.

    PubMed

    Rollandi, G A; Tentarelli, T; Vespier, M

    1985-01-01

    Twenty-one patients with Peyronie's disease were examined by computed tomography (CT) of the penis. Twenty nodules or plaques already diagnosed by clinical examination were identified. In 2 patients with a clinically palpable large plaque, all the albuginea could not be identified by CT, either in the fixed or mobile portion of the penis. Multiple lesions were palpable in 1 patient and could be seen by CT in 5 patients. Seven nonpalpable lesions were identified by CT. Lesions resembled calcified plaques in 10 instances and focal areas of diminished thickness and density of the tunica albuginea in 17 others. Computed tomography seems to be a very useful method in the study of Peyronie's disease. It allows precise evaluation of nodular lesions and it may be useful for monitoring their dimensional evolution. It may also give some insight into the structural composition of the nodules. This study supports theories that Peyronie's disease is a generalized disease of the penis.

  17. Computed tomographic measurement of canine urine concentration.

    PubMed

    Zwingenberger, Allison L; Carrade Holt, Danielle D

    2017-02-01

    Computed tomography (CT) is able to measure the attenuation of urine in Hounsfield units (HU) on abdominal imaging studies. This study was designed to measure the correlation of urine attenuation with urine specific gravity in urine samples of 40 dogs, providing a noninvasive measure of urine concentration. The HU of urine explained 72% of the variance in measured urine specific gravity [R(2) = 0.72, F(1,38) = 95.55, P < 0.001]. This noninvasive measurement can be used to estimate urine concentration in dogs undergoing abdominal CT imaging.

  18. Lymphadenopathy in celiac disease: computed tomographic observations

    SciTech Connect

    Jones, B.; Bayless, T.M.; Fishman, E.K.; Siegelman, S.S.

    1984-06-01

    Lymphadenopathy in patients with celiac disease is generally viewed with alarm due to the association between celiac disease and intestinal lymphoma. Four patients with celiac disease are described in whom significant mesenteric and paraaortic adenopathy was demonstrated by computed tomogrophy (CT). The subsequent clinical course of these patients revealed no evidence of lymphoma. In two patients with longstanding celiac disease and recent relapse, exploratory laparotomy revealed reactive hyperplasia in the enlarged glands; in one patient this was associated with intestinal ulceration, and in the other no underlying pathology was found. Follow-up CT scans in both these patients demonstrated regression of the findings with clinical improvement. In the other two patients, CT was performed as part of the initial evaluation.

  19. A computed tomographic imaging system for experimentation

    NASA Astrophysics Data System (ADS)

    Lu, Yanping; Wang, Jue; Liu, Fenglin; Yu, Honglin

    2008-03-01

    Computed tomography (CT) is a non-invasive imaging technique, which is widely applied in medicine for diagnosis and surgical planning, and in industry for non-destructive testing (NDT) and non-destructive evaluation (NDE). So, it is significant for college students to understand the fundamental of CT. In this work, A CT imaging system named CD-50BG with 50mm field-of-view has been developed for experimental teaching at colleges. With the translate-rotate scanning mode, the system makes use of a 7.4×10 8Bq (20mCi) activity 137Cs radioactive source which is held in a tungsten alloy to shield the radiation and guarantee no harm to human body, and a single plastic scintillator + photomultitude detector which is convenient for counting because of its short-time brightness and good single pulse. At same time, an image processing software with the functions of reconstruction, image processing and 3D visualization has also been developed to process the 16 bits acquired data. The reconstruction time for a 128×128 image is less than 0.1 second. High quality images with 0.8mm spatial resolution and 2% contrast sensitivity can be obtained. So far in China, more than ten institutions of higher education, including Tsinghua University and Peking University, have already applied the system for elementary teaching.

  20. Technical innovation: Multidimensional computerized software enabled subtraction computed tomographic angiography.

    PubMed

    Bhatia, Mona; Rosset, Antoine; Platon, Alexandra; Didier, Dominique; Becker, Christoph D; Poletti, Pierre-Alexandre

    2010-01-01

    Computed tomographic angiography (CTA) is a frequent noninvasive alternative to digital subtraction angiography. We previously reported the development of a new subtraction software to overcome limitations of adjacent bone and calcification in CT angiographic subtraction. Our aim was to further develop and improve this fast and automated computerized software, universally available for free use and compatible with most CT scanners, thus enabling better delineation of vascular structures, artifact reduction, and shorter reading times with potential clinical benefits. This computer-based free software will be available as an open source in the next release of OsiriX at the Web site http://www.osirix-viewer.com.

  1. Excluding False Positive Detections in Kepler Data

    NASA Astrophysics Data System (ADS)

    Caldwell, John J.; Ouvarova, T.; Borucki, W. J.

    2006-09-01

    The NASA Kepler Mission, scheduled for launch in 2008, will search for Earth-size planets orbiting Sun-like stars in or near habitable zones. A high precision photometer will search for planetary transits of parent stars. For a system similar to the Earth-Sun, the decrease in light during a central transit will be one part in 10,000 of the total stellar brightness out of transit. This poster discusses the effort to address a significant concern: the possibility of false positive detections of extra-solar Earth analogs. The concern arises because about 50 per cent of star systems are double or multiple. Further, because the photometer design is constrained by the requirement for high sensitivity to changes of low light levels, the optical resolution is not high compared to other space or terrestrial telescopes. If a relatively nearby Kepler target star happens to contain, within the Kepler PSF, an eclipsing binary system that is reduced in brightness by a factor of 10,000, say because it is 100 times farther away, the photometric profile of an eclipse could mimic a planetary transit. We have therefore developed a program to use archival data from the Hubble Space Telescope to quantify the number density of faint stars in the Kepler field that are in the brightness range that could cause confusion. Since the beginning of the project, the location of the Kepler field itself has been changed to optimize observing efficiency. The work originally included HST/WFPC2 data, and has now been expanded to ACS data as well. We present here a summary of completed and continuing work on faint background systems in the new Kepler field.

  2. Multidetector Computed Tomographic Angiography (MDCTA) for Penetrating Neck Injuries.

    PubMed

    Pasley, Jason; Berg, Regan J; Inaba, Kenji

    2012-07-01

    Evaluation of patients after penetrating neck injury has evolved over time. Previously, location of injury and symptoms were used to determine management. The contemporary management of penetrating neck injuries relies on physical examination. Patients with hard signs of vascular or aerodigestive tract injury require immediate operation, regardless of location of injury. Those with no signs can be observed. For the remainder with soft signs, multidetector computed tomographic angiography (MDCTA) is a highly sensitive and specific screening modality for evaluating the vasculature and aerodigestive structures in the neck. Utilizing MDCTA, the patient can be safely directed towards operative intervention, observation, or further investigation.

  3. Multidetector Computed Tomographic Angiography (MDCTA) for Penetrating Neck Injuries

    PubMed Central

    Pasley, Jason; Berg, Regan J.; Inaba, Kenji

    2012-01-01

    Evaluation of patients after penetrating neck injury has evolved over time. Previously, location of injury and symptoms were used to determine management. The contemporary management of penetrating neck injuries relies on physical examination. Patients with hard signs of vascular or aerodigestive tract injury require immediate operation, regardless of location of injury. Those with no signs can be observed. For the remainder with soft signs, multidetector computed tomographic angiography (MDCTA) is a highly sensitive and specific screening modality for evaluating the vasculature and aerodigestive structures in the neck. Utilizing MDCTA, the patient can be safely directed towards operative intervention, observation, or further investigation. PMID:23908840

  4. Pineal region tumors: computed tomographic-pathologic spectrum

    SciTech Connect

    Futrell, N.N.; Osborn, A.G.; Cheson. B.D.

    1981-11-01

    While several computed tomographic (CT) studies of posterior third ventricular neoplasms have included descriptions of pineal tumors, few reports have concentrated on these uncommon lesions. Some authors have asserted that the CT appearance of many pineal tumors is virtually pathognomonic. A series of nine biopsy-proved pineal gland and eight other presumed tumors is presented that illustrates their remarkable heterogeneity in both histopathologic and CT appearance. These tumors included germinomas, teratocarcinomas, hamartomas, and other varieties. They had variable margination, attentuation, calcification, and suprasellar extension. Germinomas have the best response to radiation therapy. Biopsy of pineal region tumors is now feasible and is recommended for treatment planning.

  5. Computed tomographic spectrum of intracranial mycosis: correlation with histopathology

    SciTech Connect

    Whelan, M.A.; Stern, J.; deNapoli, R.A.

    1981-12-01

    Four cases of intracerebral fungal infection are reviewed. The clinical course is outlined, and the computed tomographic (CT) characteristics are analyzed in light of known pathological data. The CT appearance of intracranial mycosis is dependent on the type of fungus as well as the dominant infecting form, i.e., yeast or hyphae. The hyphal form leads predominantly to a CT pattern consistent with vascular occlusion and secondary abscess formation; the yeast form generally results in noncaseating granulomas, which appear on CT scan as nodular enhancing lesions. If the patient survives the acute infective process, these fungal lesions undergo a prolonged subacute phase, and may eventually calcify.

  6. Coronary computed tomographic angiography: current and future uses

    PubMed Central

    Kantor, Birgit; Kuzo, Ronald S.; Gerber, Thomas C.

    2009-01-01

    Coronary computed tomographic angiography (CCTA) is a direct but minimally invasive method of visualizing coronary arteries. Acceptable indications for this technique include the assessment of suspected or known coronary artery anomalies, the evaluation of chest pain syndromes in patients with non diagnostic stress tests or who are unable to exercise, and exclusion of an ischemic etiology in patients with unexplained left ventricular dysfunction. Assessment of coronary stents with a diameter of <3.0 mm and imaging of asymptomatic patients with a goal of establishing prognosis are currently not accepted indications for CCTA. PMID:20011235

  7. The UF series of tomographic computational phantoms of pediatric patients

    SciTech Connect

    Lee, Choonik; Williams, Jonathan L.; Lee, Choonsik; Bolch, Wesley E.

    2005-12-15

    Two classes of anthropomorphic computational phantoms exist for use in Monte Carlo radiation transport simulations: tomographic voxel phantoms based upon three-dimensional (3D) medical images, and stylized mathematical phantoms based upon 3D surface equations for internal organ definition. Tomographic phantoms have shown distinct advantages over the stylized phantoms regarding their similarity to real human anatomy. However, while a number of adult tomographic phantoms have been developed since the early 1990s, very few pediatric tomographic phantoms are presently available to support dosimetry in pediatric diagnostic and therapy examinations. As part of a larger effort to construct a series of tomographic phantoms of pediatric patients, five phantoms of different ages (9-month male, 4-year female, 8-year female, 11-year male, and 14-year male) have been constructed from computed tomography (CT) image data of live patients using an IDL-based image segmentation tool. Lungs, bones, and adipose tissue were automatically segmented through use of window leveling of the original CT numbers. Additional organs were segmented either semiautomatically or manually with the aid of both anatomical knowledge and available image-processing techniques. Layers of skin were created by adding voxels along the exterior contour of the bodies. The phantoms were created from fused images taken from head and chest-abdomen-pelvis CT exams of the same individuals (9-month and 4-year phantoms) or of two different individuals of the same sex and similar age (8-year, 11-year, and 14-year phantoms). For each model, the resolution and slice positions of the image sets were adjusted based upon their anatomical coverage and then fused to a single head-torso image set. The resolutions of the phantoms for the 9-month, 4-year, 8-year, 11-year, and 14-year are 0.43x0.43x3.0 mm, 0.45x0.45x5.0 mm, 0.58x0.58x6.0 mm, 0.47x0.47x6.00 mm, and 0.625x0.625x6.0 mm, respectively. While organ masses can be

  8. The UF series of tomographic computational phantoms of pediatric patients.

    PubMed

    Lee, Choonik; Williams, Jonathan L; Lee, Choonsik; Bolch, Wesley E

    2005-12-01

    Two classes of anthropomorphic computational phantoms exist for use in Monte Carlo radiation transport simulations: tomographic voxel phantoms based upon three-dimensional (3D) medical images, and stylized mathematical phantoms based upon 3D surface equations for internal organ definition. Tomographic phantoms have shown distinct advantages over the stylized phantoms regarding their similarity to real human anatomy. However, while a number of adult tomographic phantoms have been developed since the early 1990s, very few pediatric tomographic phantoms are presently available to support dosimetry in pediatric diagnostic and therapy examinations. As part of a larger effort to construct a series of tomographic phantoms of pediatric patients, five phantoms of different ages (9-month male, 4-year female, 8-year female, 11-year male, and 14-year male) have been constructed from computed tomography (CT) image data of live patients using an IDL-based image segmentation tool. Lungs, bones, and adipose tissue were automatically segmented through use of window leveling of the original CT numbers. Additional organs were segmented either semiautomatically or manually with the aid of both anatomical knowledge and available image-processing techniques. Layers of skin were created by adding voxels along the exterior contour of the bodies. The phantoms were created from fused images taken from head and chest-abdomen-pelvis CT exams of the same individuals (9-month and 4-year phantoms) or of two different individuals of the same sex and similar age (8-year, 11-year, and 14-year phantoms). For each model, the resolution and slice positions of the image sets were adjusted based upon their anatomical coverage and then fused to a single head-torso image set. The resolutions of the phantoms for the 9-month, 4-year, 8-year, 11-year, and 14-year are 0.43 x 0.43 x 3.0 mm, 0.45 x 0.45 x 5.0 mm, 0.58 x 0.58 x 6.0 mm, 0.47 X 0.47 x 6.00 mm, and 0.625 x 0.625 x 6.0 mm, respectively. While organ

  9. Computed tomographic arthrography of the normal dromedary camel carpus.

    PubMed

    Badawy, Adel M; Marzok, Mohamed A; Eshra, Eman A

    2016-05-18

    The aim of this prospective cadaveric study was to provide a detailed computed tomographic (CT) reference of the carpal joint in healthy dromedary camels. Twelve forelimbs of six apparently healthy camels were used. Computed tomographic imaging of 12 normal cadaveric camel carpal joints was performed before and after intra-articular administration of iodinated contrast medium. Transverse CT images were reconstructed in dorsal and parasagittal planes. The six carpal bones, the radial trochlea, and the proximal articular surface of the metacarpal bones were clearly visible on CT images with the bone setting window. Radiocarpal, carpometacarpal, transverse intercarpal, medial and lateral palmer intercarpal, middle intercarpal, accessory carpoulnar and medial and lateral collateral ligaments, carpal canal, joint capsule, and the extensor and flexor tendons were identified on CT images with the soft-tissue setting window. Postcontrast CT images provided better delineation of intercarpal ligaments, the capsular compartments and recesses. Results indicated that the osseous and the clinically important soft tissue structures of the dromedary camel carpal joint could be identified using CT and CT arthrography. The CT data of this study will serve as a basis for diagnosis of carpal problems in camels.

  10. Visual phrase learning and its application in computed tomographic colonography.

    PubMed

    Wang, Shijun; McKenna, Matthew; Wei, Zhuoshi; Liu, Jiamin; Liu, Peter; Summers, Ronald M

    2013-01-01

    In this work, we propose a visual phrase learning scheme to learn an optimal visual composite of anatomical components/parts from CT colonography images for computer-aided detection. The key idea is to utilize the anatomical parts of human body from medical images and associate them with biological targets of interest (organs, cancers, lesions, etc.) for joint detection and recognition. These anatomical parts of the human body are not necessarily near each other regarding their physical locations, and they serve more like a human body navigation system for detection and recognition. To show the effectiveness of the proposed learning scheme, we applied it to two sub-problems in computed tomographic colonography: teniae detection and classification of colorectal polyp candidates. Experimental results showed its efficacy.

  11. Dissecting aortic aneurysms: accuracy of computed tomographic diagnosis

    SciTech Connect

    Thorsen, M.K.; San Dretto, M.A.; Lawson, T.L.; Foley, W.D.; Smith, D.F.; Berland, L.L.

    1983-09-01

    During a three-year period, fifty patients were evaluated for the possibility of dissecting aortic aneurysm using high-resolution computed tomography (CT). The diagnosis of dissection was made if two contrast-medium-filled channels were identified within the aortic lumen. Eighteen patients were diagnosed with CT as having dissecting aortic aneurysms. Eight patients were evaluated postoperatively and five of these patients had persistence of the double channel. Twenty-four patients had no evidence on CT of aortic dissection. Follow-up was obtained in all patients. There were no known false-negative diagnoses and one false-positive diagnosis. High-resolution CT offers an accurate, noninvasive means to evaluate patients for suspected dissecting aortic aneurysms.

  12. Computer-aided interpretation approach for optical tomographic images

    NASA Astrophysics Data System (ADS)

    Klose, Christian D.; Klose, Alexander D.; Netz, Uwe J.; Scheel, Alexander K.; Beuthan, Jürgen; Hielscher, Andreas H.

    2010-11-01

    A computer-aided interpretation approach is proposed to detect rheumatic arthritis (RA) in human finger joints using optical tomographic images. The image interpretation method employs a classification algorithm that makes use of a so-called self-organizing mapping scheme to classify fingers as either affected or unaffected by RA. Unlike in previous studies, this allows for combining multiple image features, such as minimum and maximum values of the absorption coefficient for identifying affected and not affected joints. Classification performances obtained by the proposed method were evaluated in terms of sensitivity, specificity, Youden index, and mutual information. Different methods (i.e., clinical diagnostics, ultrasound imaging, magnet resonance imaging, and inspection of optical tomographic images), were used to produce ground truth benchmarks to determine the performance of image interpretations. Using data from 100 finger joints, findings suggest that some parameter combinations lead to higher sensitivities, while others to higher specificities when compared to single parameter classifications employed in previous studies. Maximum performances are reached when combining the minimum/maximum ratio of the absorption coefficient and image variance. In this case, sensitivities and specificities over 0.9 can be achieved. These values are much higher than values obtained when only single parameter classifications were used, where sensitivities and specificities remained well below 0.8.

  13. Computer-aided interpretation approach for optical tomographic images.

    PubMed

    Klose, Christian D; Klose, Alexander D; Netz, Uwe J; Scheel, Alexander K; Beuthan, Jurgen; Hielscher, Andreas H

    2010-01-01

    A computer-aided interpretation approach is proposed to detect rheumatic arthritis (RA) in human finger joints using optical tomographic images. The image interpretation method employs a classification algorithm that makes use of a so-called self-organizing mapping scheme to classify fingers as either affected or unaffected by RA. Unlike in previous studies, this allows for combining multiple image features, such as minimum and maximum values of the absorption coefficient for identifying affected and not affected joints. Classification performances obtained by the proposed method were evaluated in terms of sensitivity, specificity, Youden index, and mutual information. Different methods (i.e., clinical diagnostics, ultrasound imaging, magnet resonance imaging, and inspection of optical tomographic images), were used to produce ground truth benchmarks to determine the performance of image interpretations. Using data from 100 finger joints, findings suggest that some parameter combinations lead to higher sensitivities, while others to higher specificities when compared to single parameter classifications employed in previous studies. Maximum performances are reached when combining the minimum/maximum ratio of the absorption coefficient and image variance. In this case, sensitivities and specificities over 0.9 can be achieved. These values are much higher than values obtained when only single parameter classifications were used, where sensitivities and specificities remained well below 0.8.

  14. Cystic tumors of the fetal and neonatal cerebrum: ultrasound and computed tomographic evaluation

    SciTech Connect

    Sauerbrei, E.E.; Cooperberg, P.L.

    1983-06-01

    Three patients (two infants and one fetus) had complex (partially cystic and partially solid) supratentorial tumors involving the brain. The sonographic and computed tomographic appearance in each of these lesions is described and discussed. The cystic component of each lesion was equally well delineated by the two modalities, whereas the peripheral solid component was better defined by contrast-enhanced computed tomographic scans.

  15. Accuracy of the typical computed tomographic appearances of fibrosing alveolitis.

    PubMed Central

    Tung, K T; Wells, A U; Rubens, M B; Kirk, J M; du Bois, R M; Hansell, D M

    1993-01-01

    BACKGROUND--Open lung biopsy is often performed to confirm the diagnosis in patients with suspected fibrosing alveolitis. The superior sensitivity and specificity of high resolution computed tomography (CT) over chest radiography in various diffuse lung diseases suggest that the characteristic appearance of fibrosing alveolitis on high resolution CT might render biopsy confirmation unnecessary. METHODS--The chest radiographs and high resolution CT scans of 86 patients (41 with fibrosing alveolitis and 45 with various other diffuse lung diseases) were examined individually and independently by two observers. No clinical information was given and the observers gave a level of confidence when the diagnosis was thought to be fibrosing alveolitis. RESULTS--The observers correctly and confidently discriminated between fibrosing alveolitis and other diffuse lung diseases on high resolution CT with an accuracy of 88% and on chest radiography with an accuracy of 76%. The false negative rate for fibrosing alveolitis diminished from 29% on chest radiography to 11% on high resolution CT. The false positive rate on chest radiography was 19% and on high resolution CT 13%; the false positive diagnoses on CT were the result of a few conditions (extrinsic allergic alveolitis, sarcoidosis, cryptogenic organising pneumonia, and pulmonary eosinophilia) which mimicked some of the CT features of fibrosing alveolitis. The superficial similarity of the CT patterns of these conditions are discussed. CONCLUSIONS--High resolution CT is superior to chest radiography in establishing the diagnosis of fibrosing alveolitis and the typical CT appearances are virtually pathognomonic. The diagnostic advantages of CT over chest radiography should further reduce the need for open lung biopsy in this condition. Images PMID:8135910

  16. Computed tomographic study of hormone-secreting microadenomas

    SciTech Connect

    Hemminghytt, S.; Kalkhoff, R.K.; Daniels, D.L.; Williams, A.L.; Grogan, J.P.; Haughton, V.M.

    1983-01-01

    A review was made of the computed tomographic (CT) studies of 33 patients with hormone-secreting microadenomas that had been verified by transsphenoidal surgery and endocrinologic evaluation. In previous studies in small series of patients, the CT appearance of pituitary microadenomas has been reported as hypodense, isodense, and hyperdense. In this study, CT showed a region of diminished enhancement and ususally an enlarged pituitary gland in cases of prolactin-secreting adenomas. HGH- or ACTH-secreting adenomas were less consistently hypodense. It is concluded that hypodensity and enlargement in the pituitary gland are the most useful criteria for identification of microadenomas. Some technical factors that may affect the CT appearance of microadenomas and lead to conflicting reports are discussed.

  17. Central nervous system leukemia and lymphoma: computed tomographic manifestations

    SciTech Connect

    Pagani, J.J.; Libshitz, H.I.; Wallace, S.; Hayman, L.A.

    1981-12-01

    Computed tomographic (CT) abnormalities in the brain were identified in 31 of 405 patients with leukemia or lymphoma. Abnormalities included neoplastic masses (15), hemorrhage (nine), abscess (two), other brain tumors (four), and methotrexate leukoencephalopathy (one). CT was normal in 374 patients including 148 with meningeal disease diagnosed by cerebrospinal fluid cytologic examination. Prior to treatment, malignant masses were isodense or of greater density with varying amounts of edema. Increase in size or number of the masses indicated worsening. Response to radiation and chemotherapy was manifested by development of a central low density region with an enhancing rim. CT findings correlated with clinical and cerebrospinal fluid findings. The differential diagnosis of the various abnormalities is considered.

  18. Regional Comparison of Multiphase Computed Tomographic Angiography and Computed Tomographic Perfusion for Prediction of Tissue Fate in Ischemic Stroke.

    PubMed

    d'Esterre, Christopher D; Trivedi, Anurag; Pordeli, Pooneh; Boesen, Mari; Patil, Shivanand; Hwan Ahn, Seong; Najm, Mohamed; Fainardi, Enrico; Shankar, Jai Jai Shiva; Rubiera, Marta; Almekhlafi, Mohammed A; Mandzia, Jennifer; Khaw, Alexander V; Barber, Philip; Coutts, Shelagh; Hill, Michael D; Demchuk, Andrew M; Sajobi, Tolulope; Forkert, Nils D; Goyal, Mayank; Lee, Ting-Yim; Menon, Bijoy K

    2017-04-01

    Within different brain regions, we determine the comparative value of multiphase computed tomographic angiography (mCTA) and computed tomographic perfusion (CTP) in predicting follow-up infarction. Patients with M1-middle cerebral artery occlusions were prospectively included in this multicenter study. Regional analysis was performed for each patient within Alberta Stroke Program Early CT Score regions M2 to M6. Regional pial vessel filling was assessed on mCTA in 3 ways: (1) Washout of contrast within pial vessels; (2) Extent of maximal pial vessel enhancement compared with contralateral hemisphere; (3) Delay in maximal pial vessel enhancement compared with contralateral hemisphere. Cerebral blood flow, cerebral blood volume, and Tmax data were extracted within these Alberta Stroke Program Early CT Score regions. Twenty-four- to 36-hour magnetic resonance imaging/CT was assessed for infarct in each Alberta Stroke Program Early CT Score region (defined as >20% infarction within that region). Mixed effects logistic regression models were used to compare mCTA and CTP parameters when predicting brain infarction. Area under the receiver operating characteristics was used to assess discriminative value of statistical models. Seventy-seven patients were included. mCTA parameter washout and CTP parameter Tmax were significantly associated with follow-up infarction in all models (P<0.05). The area under the receiver operating characteristic for mCTA models ranged from 92% to 94% and was not different compared with all CTP models (P>0.05). Mean Tmax and cerebral blood volume values were significantly different between each washout score (P<0.01) and each delay score category (P<0.01). Mean Tmax, cerebral blood flow, and cerebral blood volume values were significantly different between each extent score category (P<0.05). Similar to CTP, multiphase CTA can be used to predict tissue fate regionally in acute ischemic stroke patients. © 2017 American Heart Association, Inc.

  19. Pediatric computed tomographic angiography: imaging the cardiovascular system gently.

    PubMed

    Hellinger, Jeffrey C; Pena, Andres; Poon, Michael; Chan, Frandics P; Epelman, Monica

    2010-03-01

    Whether congenital or acquired, timely recognition and management of disease is imperative, as hemodynamic alterations in blood flow, tissue perfusion, and cellular oxygenation can have profound effects on organ function, growth and development, and quality of life for the pediatric patient. Ensuring safe computed tomographic angiography (CTA) practice and "gentle" pediatric imaging requires the cardiovascular imager to have sound understanding of CTA advantages, limitations, and appropriate indications as well as strong working knowledge of acquisition principles and image post processing. From this vantage point, CTA can be used as a useful adjunct along with the other modalities. This article presents a summary of dose reduction CTA methodologies along with techniques the authors have employed in clinical practice to achieve low-dose and ultralow-dose exposure in pediatric CTA. CTA technical principles are discussed with an emphasis on the low-dose methodologies and safe contrast medium delivery strategies. Recommended parameters for currently available multidetector-row computed tomography scanners are summarized alongside recommended radiation and contrast medium parameters. In the second part of the article an overview of pediatric CTA clinical applications is presented, illustrating low-dose and ultra-low dose techniques, with an emphasis on the specific protocols. Copyright 2010 Elsevier Inc. All rights reserved.

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

    PubMed

    Hernandez, Cecilia; Mella, Carlos; Navarro, Gonzalo; Olivera-Nappa, Alvaro; Araya, Jaime

    2017-01-01

    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 that more than 50

  1. An interactive, computer-based atlas of neurologic positron emission tomographic studies for use in teaching.

    PubMed

    Berlangieri, S U; Schifter, T; Hoffman, J M; Hawk, T C; Hamblen, S M; Coleman, R E

    1993-06-01

    Recent developments in personal computer hardware and software allow the manipulation of radiologic images. We developed an interactive, computer-based atlas of clinical neurologic positron emission tomographic studies for use as an educational resource. A personal computer and multimedia software were used to assemble the clinical case studies. For each clinical case, the user had available the clinical history, positron emission tomographic and correlative anatomic images, study interpretation, discussion, and references. The clinical cases were selected for their educational value, either as a representative example of an abnormality or for their ability to illustrate a common pitfall in positron emission tomographic imaging of the brain.

  2. Location of mammograms ROI's and reduction of false-positive.

    PubMed

    Salazar-Licea, Luis Antonio; Pedraza-Ortega, Jesús Carlos; Pastrana-Palma, Alberto; Aceves-Fernandez, Marco A

    2017-05-01

    that produces false positives. Moreover, because the image size is reduced the computer processing time will be decreased. This segmentation stage can be an addition to mammograms analysis broadly, not only to find mcc but abnormalities such as circumscribed masses, speculated masses and architectural distortion. Also is useful to create automatically an unsupervised segmentation in mammograms without stage of training. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Computed Tomographic Exploration of the Middle Ethmoidal Artery

    PubMed Central

    Mason, Eric; Solares, C. Arturo; Carrau, Ricardo L.; Figueroa, Ramon

    2015-01-01

    Objectives The integral involvement of sinus and skull base surgeries in the field of otolaryngology makes the endonasal vasculature including the ethmoidal arteries important to consider. The anterior ethmoidal artery (AEA) and posterior ethmoidal artery (PEA) are well-known entities, yet the relatively recent notion of accessory or middle ethmoidal vessels complicates our understanding of this arterial system. Study Design Radiographic study. Methods Fifty computed tomographic angiographies were studied for the presence of accessory/middle ethmoidal arteries (MEAs). If contrasted arteries were not visualized reliably, foramina were accepted as evidence of arteries. The accessory arteries/foramina were then compared with the locations of the AEA and PEA. Results A total of 19 of the 50 patient samples studied had evidence of a right, left, or bilateral middle ethmoidal vessels (38%). Overall, 26 arteries total were identified out of the 100 sides (26%). Unilateral middle arteries were more common than bilateral, and right sided were more common than left. There was no evidence of multiple MEAs on a given side. Conclusion The endonasal surgeon must be cognizant of the possible presence of MEAs. These arteries should be considered when working in the medial orbit and anterior skull base region. PMID:26401479

  4. Adoption of Computed Tomographic Colonography by U.S. Hospitals

    PubMed Central

    McHugh, Megan; Osei-Anto, Awo; Klabunde, Carrie N.; Galen, Barbara A.

    2010-01-01

    Purpose Computed tomographic colonography (CTC) is a new non-invasivetechnology proposed as an option for colorectal cancer screening. The purpose of this study was to identify the percent of U.S. hospitals that offered CTC between 2005 and 2008 and factors that motivated or impeded adoption. Methods We analyzed data on the provision of colorectal cancer screening services by non-federal, general hospitals using the 2005 – 2008 American Hospital Association Annual Surveys. Additionally, in 2009, we conducted exploratory interviews with representatives from radiology departments at nine hospitals – six that provided CTC and three that did not. Results In 2008, 17% of hospitals offered CTC, up from 13% in 2005. Sixty-nine percent of hospitals that offered CTC in 2008 also offered optical colonoscopy services. Factors motivating adoption of CTC included a desire to provide an alternative screening option for frail, elderly patients and patients with a failed optical colonoscopy; long waits for optical colonoscopy; and promising evidence on CTC published in peer-reviewed literature. Lack of reimbursement was a commonly-cited barrier. Conclusion Growth of CTC services at U.S. hospitals occurred even in the absence of Medicare coverage or agreement among national guideline-setting organizations regarding CTC’s use in screening. Almost one-third of hospitals that offer CTC do not offer optical colonoscopy, and may not be prepared to provide adequate follow-up for patients with failed CTCs. PMID:21371666

  5. Current experience with computed tomographic cystography and blunt trauma.

    PubMed

    Deck, A J; Shaves, S; Talner, L; Porter, J R

    2001-12-01

    We present our experience with computed tomographic (CT) cystography for the diagnosis of bladder rupture in patients with blunt abdominal and pelvic trauma and compare the results of CT cystography to operative exploration. We identified all blunt trauma patients diagnosed with bladder rupture from January 1992 to September 1998. We also reviewed the radiology computerized information system (RIS) for all CT cystograms performed for the evaluation of blunt trauma during the same time period. The medical records and pertinent radiographs of the patients with bladder rupture who underwent CT cystography as part of their admission evaluation were reviewed. Operative findings were compared to radiographic findings. Altogether, 316 patients had CT cystograms as part of an initial evaluation for blunt trauma. Of these patients, 44 had an ultimate diagnosis of bladder rupture; 42 patients had CT cystograms indicating bladder rupture. A total of 28 patients underwent formal bladder exploration; 23 (82%) had operative findings that exactly (i.e., presence and type of rupture) matched the CT cystogram interpretation. The overall sensitivity and specificity of CT cystography for detection of bladder rupture were 95% and 100%, respectively. For intraperitoneal rupture, the sensitivity and specificity were 78% and 99%, respectively. CT cystography provides an expedient evaluation for bladder rupture caused by blunt trauma and has an accuracy comparable to that reported for plain film cystography. We recommend CT cystography over plain film cystography for patients undergoing CT evaluation for other blunt trauma-related injuries.

  6. Computed tomographic characteristics of eosinophilic pulmonary granulomatosis in five dogs.

    PubMed

    Fina, Caroline; Vignoli, Massimo; Terragni, Rossella; Rossi, Federica; Wisner, Erik; Saunders, Jimmy H

    2014-01-01

    Canine pulmonary eosinophilic granulomatosis is a rare inflammatory pulmonary disease characterized by formation of eosinophilic granulomas that tend to obliterate the normal pulmonary architecture. The purpose of this retrospective study was to describe the CT characteristics of confirmed idiopathic pulmonary eosinophilic granulomatosis in a group of dogs. Five dogs met inclusion criteria. All patients were young adult dogs of variable breeds. No dog had concurrent occult heartworm disease. Computed tomographic characteristics most commonly included pulmonary masses and nodules of variable size, and lesions were most commonly located in the caudal lung lobes. Four dogs had large pulmonary masses with or without additional nodules and one dog had nodular lesions disseminated throughout the entire lung parenchyma. All large eosinophilic granulomas were smoothly margined, heterogeneous pulmonary masses displaying heterogeneous contrast enhancement. A honeycomb-like enhancement pattern was observed in all but one mass and consisted of multiple hyperattenuating rims delineating central hypoattenuating areas, suggestive of bronchiectatic lung with peripheral enhancing airway walls and fluid-filled, necrotic bronchial lumen. One dog had evidence of tracheobronchial lymphadenopathy. Findings indicated that canine eosinophilic pulmonary granulomatosis should be included as a differential diagnosis for dogs with CT characteristics of multiple pulmonary masses and/or nodules in caudal lung lobes, and a honeycomb-like enhancement pattern in masses after intravenous administration of iodinated contrast medium.

  7. Automatic delineation of the diaphragm in computed tomographic images.

    PubMed

    Rangayyan, Rangaraj M; Vu, Randy H; Boag, Graham S

    2008-10-01

    Segmentation of the internal organs in medical images is a difficult task. By incorporating a priori information regarding specific organs of interest, results of segmentation may be improved. Landmarking (i.e., identifying stable structures to aid in gaining more knowledge concerning contiguous structures) is a promising segmentation method. Specifically, segmentation of the diaphragm may help in limiting the scope of segmentation methods to the abdominal cavity; the diaphragm may also serve as a stable landmark for identifying internal organs, such as the liver, the spleen, and the heart. A method to delineate the diaphragm is proposed in the present work. The method is based upon segmentation of the lungs, identification of the lower surface of the lungs as an initial representation of the diaphragm, and the application of least-squares modeling and deformable contour models to obtain the final segmentation of the diaphragm. The proposed procedure was applied to nine X-ray computed tomographic (CT) exams of four pediatric patients with neuroblastoma. The results were evaluated against the boundaries of the diaphragm as identified independently by a radiologist. Good agreement was observed between the results of segmentation and the reference contours drawn by the radiologist, with an average mean distance to the closest point of 5.85 mm over a total of 73 CT slices including the diaphragm.

  8. Optimization of radiation dose reduction in cardiac computed tomographic angiography.

    PubMed

    Entrikin, Daniel W; Leipsic, Jonathon A; Carr, J Jeffrey

    2011-01-01

    Cardiac computed tomographic angiography (CCTA) has evolved at an unprecedented pace over the past decade, during which time it has proven to be an accurate and effective tool for imaging of the heart in a growing list of clinical applications. However, the rapid growth in the use of CT imaging in general has prompted appropriate concerns regarding increasing medical radiation exposure to patients, particularly with regard to potential long-term risks of radiation-induced malignancy on both individual and population levels. As with all medical imaging modalities, imaging the heart with CCTA should be performed in a manner that achieves diagnostic image quality while maintaining patient radiation exposure as low as reasonably achievable (As Low As Reasonably Achievable [ALARA] principle). The goal of this article is to provide the reader with a wide-ranging review of both primary and secondary techniques that are currently available to minimize patient radiation exposure. Some of the techniques described in this article are universal, whereas others may be scanner specific. By gaining a thorough understanding of the various tools and methodologies employed for reduction of radiation exposure, the cardiac imager should be able to formulate CCTA protocols appropriate for their equipment and their clinical applications, in a manner that optimally preserves diagnostic image quality and minimizes patient radiation dose.

  9. Computed tomographic findings of fungal rhinitis and sinusitis in cats.

    PubMed

    Karnik, Ketaki; Reichle, Jean K; Fischetti, Anthony J; Goggin, Justin M

    2009-01-01

    The computed tomographic (CT) findings of fungal rhinitis/sinusitis in cats were characterized. The CT images of 10 cats ranging in age from 7 to 13 years were examined. The mean age was 10.8 years and all were neutered males. Nasal aspergillosis was diagnosed in five cats, cryptococcosis in three cats, hyalohyphomycosis in one cat, and trichosporonosis in one cat. Bilateral disease was present in eight cats, seven had abnormal soft tissue attenuation in two-thirds of the nasal cavity, and six had turbinate lysis. Seven cats had also lysis of the hard palate, nasal septum, or frontal bone. One cat had lysis of the cribriform plate. Five of the nine cats whose lymph nodes were imaged had lymph node enlargement. There was contrast medium enhancement in the nasal cavity in all cats, with either a primarily peripheral rim or heterogeneous pattern. There appears to be an overlap of clinical signs, age, and CT features of cats with nasal neoplasia and those with fungal rhinitis/ sinusitis.

  10. microRNA target prediction programs predict many false positives.

    PubMed

    Pinzón, Natalia; Li, Blaise; Martinez, Laura; Sergeeva, Anna; Presumey, Jessy; Apparailly, Florence; Seitz, Hervé

    2017-02-01

    According to the current view, each microRNA regulates hundreds of genes. Computational tools aim at identifying microRNA targets, usually selecting evolutionarily conserved microRNA binding sites. While the false positive rates have been evaluated for some prediction programs, that information is rarely put forward in studies making use of their predictions. Here, we provide evidence that such predictions are often biologically irrelevant. Focusing on miR-223-guided repression, we observed that it is often smaller than inter-individual variability in gene expression among wild-type mice, suggesting that most predicted targets are functionally insensitive to that microRNA. Furthermore, we found that human haplo-insufficient genes tend to bear the most highly conserved microRNA binding sites. It thus appears that biological functionality of microRNA binding sites depends on the dose-sensitivity of their host gene and that, conversely, it is unlikely that every predicted microRNA target is dose-sensitive enough to be functionally regulated by microRNAs. We also observed that some mRNAs can efficiently titrate microRNAs, providing a reason for microRNA binding site conservation for inefficiently repressed targets. Finally, many conserved microRNA binding sites are conserved in a microRNA-independent fashion: Sequence elements may be conserved for other reasons, while being fortuitously complementary to microRNAs. Collectively, our data suggest that the role of microRNAs in normal and pathological conditions has been overestimated due to the frequent overlooking of false positive rates. © 2017 Pinzón et al.; Published by Cold Spring Harbor Laboratory Press.

  11. microRNA target prediction programs predict many false positives

    PubMed Central

    Pinzón, Natalia; Martinez, Laura; Sergeeva, Anna; Presumey, Jessy; Apparailly, Florence

    2017-01-01

    According to the current view, each microRNA regulates hundreds of genes. Computational tools aim at identifying microRNA targets, usually selecting evolutionarily conserved microRNA binding sites. While the false positive rates have been evaluated for some prediction programs, that information is rarely put forward in studies making use of their predictions. Here, we provide evidence that such predictions are often biologically irrelevant. Focusing on miR-223-guided repression, we observed that it is often smaller than inter-individual variability in gene expression among wild-type mice, suggesting that most predicted targets are functionally insensitive to that microRNA. Furthermore, we found that human haplo-insufficient genes tend to bear the most highly conserved microRNA binding sites. It thus appears that biological functionality of microRNA binding sites depends on the dose-sensitivity of their host gene and that, conversely, it is unlikely that every predicted microRNA target is dose-sensitive enough to be functionally regulated by microRNAs. We also observed that some mRNAs can efficiently titrate microRNAs, providing a reason for microRNA binding site conservation for inefficiently repressed targets. Finally, many conserved microRNA binding sites are conserved in a microRNA-independent fashion: Sequence elements may be conserved for other reasons, while being fortuitously complementary to microRNAs. Collectively, our data suggest that the role of microRNAs in normal and pathological conditions has been overestimated due to the frequent overlooking of false positive rates. PMID:28148562

  12. Angiomatous lymphoid hamartoma of the pelvis: characteristic calcification and computed tomographic appearance

    SciTech Connect

    Goodman, K.; Baim, R.S.; Clair, M.R.; Perkes, E.A.

    1983-03-01

    A case of angiomatous lymphoid hamartoma of the female pelvis is reported. A description of the computed tomographic appearance is included and an apparently common and characteristic form of calcification is described.

  13. False positive test results for pheochromocytoma from 2000 to 2008.

    PubMed

    Yu, R; Wei, M

    2010-10-01

    Testing for pheochromocytoma becomes more frequent in clinical practice. False positive test results may cause patient anxiety and unnecessary imaging studies. The data on false positive results for pheochromocytoma in routine clinical practice are lacking. To examine the prevalence of false positive results and to reveal the clinical features and laboratory tests of patients with markedly elevated but false positive test results, a database of tests for pheochromocytoma at a large general hospital between 2000 and 2008 was reviewed. Of 1,896 patients tested, 417 (22.0%) had at least one abnormal test result and 66 (3.5%) had markedly elevated results. 24 patients with markedly elevated but false positive results received 65 imaging studies and 1 adrenalectomy. The causes of the misleading results included physiological variations (33%), laboratory errors (29%), and drug interference with measurement (21%). The false positive rate of a markedly elevated result was lowest for vanillylmandelic acid (9%) and highest for urine metanephrines (50%) (p = 0.03). Nearly half of all test results were normal and 79% of patients had at least one normal result. Therefore false positive test results for pheochromocytoma are rather common. Markedly elevated but false positive test results can potentially be avoided by judicious selection of patients and tests. Pretest risk, physiological variations of catecholamine levels, laboratory errors, and drug interference should be considered in interpreting abnormal test results. © J. A. Barth Verlag in Georg Thieme Verlag KG Stuttgart · New York.

  14. Computed tomographic appearance of canine tonsillar neoplasia: 14 cases.

    PubMed

    Thierry, Florence; Longo, Maurizio; Pecceu, Evi; Zani, Davide D; Schwarz, Tobias

    2017-09-19

    The palatine tonsil is an uncommon site of oral canine neoplasia. For affected tonsils, squamous cell carcinoma is the most frequent type of neoplasia, followed by melanoma and lymphoma. Computed tomography (CT) is increasingly used for investigation of canine oropharyngeal pathology; however, limited information is available on the CT appearance of tonsillar neoplasms. Objectives of this retrospective descriptive case series were to characterize the CT features of canine tonsillar neoplasia and determine whether specific CT features differentiate nonneoplastic from neoplastic tonsils. Computed tomographic studies of 14 dogs diagnosed with tonsillar neoplasia were retrieved from two referral hospitals and reviewed by two observers. Diagnosis was based on histology or cytology. Carcinoma was diagnosed in 11 dogs, melanoma in two and lymphoma in one dog. Specific CT features of the tonsil and regional lymph nodes did not differentiate neoplastic from nonneoplastic tonsillar diseases, but regional lymph node CT features were useful for diagnosis in some cases. Marked enlargement (width ≥ 18 mm, 12/18), heterogeneity (16/18), and loss of the hypoattenuating hilus (18/18) of the medial retropharyngeal lymph node were common concomitant features of tonsillar neoplasia. The medial retropharyngeal and mandibular lymphadenomegaly was ipsilateral to the neoplastic tonsil in 8/12 and 6/9 dogs, respectively. Five dogs demonstrated little or no enlargement of the tonsil despite the associated metastatic lymphadenomegaly. Tonsillar neoplasia should therefore be considered as a differential diagnosis for dogs with CT evidence of isolated medial retropharyngeal lymphadenomegaly (regardless of normally sized tonsils), or of any enlarged tonsil with no associated lymphadenomegaly. © 2017 The Authors. Veterinary Radiology & Ultrasound published by Wiley Periodicals, Inc. on behalf of American College of Veterinary Radiology.

  15. "Pseudostring sign" on carotid computed tomographic angiography: collateralization by vasa vasorum.

    PubMed

    Ahmed, Manzoor; Kang, Preet; Pinault, Gilles; Jean-Claude, Jessie

    2009-01-01

    We present 3 cases of unilateral internal carotid artery (ICA) occlusions with prominent single collateralizing vessel of vasa vasorum on computed tomographic angiography. The features on axial source and 3-dimensional images of computed tomographic angiography include "pseudostring sign," serpigenous course of the vasa vasorum, eccentric dot appearance in the wall of chronically thrombosed ICA, and termination in the neck or reconstituting into the ICA at or below the skull base.

  16. Computed tomographic findings in 57 cats with primary pulmonary neoplasia.

    PubMed

    Aarsvold, Stacie; Reetz, Jennifer A; Reichle, Jean K; Jones, Ian D; Lamb, Christopher R; Evola, Maria G; Keyerleber, Michele A; Marolf, Angela J

    2015-01-01

    Primary pulmonary neoplasia is relatively uncommon in cats and generally has a poor prognosis. In this multicenter, retrospective study of 57 cats with pulmonary neoplasia, the most frequent presenting signs were anorexia/inappetence (39%) and cough (37%). The pulmonary tumors were considered to be incidental findings in 9% cats. In computed tomographic (CT) images, primary pulmonary tumors appeared as a pulmonary mass in 55 (96%) cats and as a disseminated pulmonary lesion without a defined mass in two (4%) cats. Most pulmonary tumors were in the caudal lobes, with 28 (49%) in the right caudal lobe and 17 (30%) in the left caudal lobe. CT features associated with pulmonary tumors included mass in contact with visceral pleura (96%), irregular margins (83%), well-defined borders (79%), bronchial compression (74%), gas-containing cavities (63%), foci of mineral attenuation (56%), and bronchial invasion (19%). The mean (range) maximal dimension of the pulmonary masses was 3.5 cm (1.1-11.5 cm). Additional foci of pulmonary disease compatible with metastasis were observed in 53% cats. Pleural fluid was evident in 30% cats and pulmonary thrombosis in 12% cats. The histologic diagnoses were 47 (82%) adenocarcinomas, six (11%) tumors of bronchial origin, three (5%) adenosquamous cell carcinomas, and one (2%) squamous cell carcinoma. In this series, adenocarcinoma was the predominant tumor type, but shared many features with less common tumor types. No associations were identified between tumor type and CT features. Prevalence of suspected intrapulmonary metastasis was higher than in previous radiographic studies of cats with lung tumors.

  17. Automated Astrophysical False Positive Analysis of Transiting Planet Signals

    NASA Astrophysics Data System (ADS)

    Morton, Timothy

    2015-08-01

    Beginning with Kepler, but continuing with K2 and TESS, transiting planet candidates are now found at a much faster rate than follow-up observations can be obtained. Thus, distinguishing true planet candidates from astrophysical false positives has become primarily a statistical exercise. I will describe a new publicly available open-source Python package for analyzing the astrophysical false positive probabilities of transiting exoplanet signals. In addition, I will present results of applying this analysis to both Kepler and K2 planet candidates, resulting in the probabilistic validation of thousands of exoplanets, as well as identifying many likely false positives.

  18. False-Positive Stress Echocardiograms: A Continuing Challenge.

    PubMed

    Qamruddin, Salima

    2016-01-01

    Stress echocardiography is an integral test in the cardiac diagnostic laboratory and has high sensitivity and specificity. Despite the excellent specificity of stress echocardiography, we continue to see a subset of patients with false-positive tests (defined as <50% diameter stenosis on subsequent coronary angiography). These false-positive findings present a management challenge because it remains unclear if and how to treat these patients. This article reviews relevant clinical studies and their outcomes. Studies suggest that a group of patients develops a hypertensive response to exercise and therefore may have false-positive stress echocardiography. Hence, superior blood pressure control prior to stress echocardiography may prevent some false-positive tests. In addition, a subset of patients has microvascular abnormalities, vasomotor changes, endothelial dysfunction, and/or small vessel coronary disease that can lead to false-positive stress echocardiography. The evidence is insufficient to state that a false-positive stress echocardiography in the absence of obstructive coronary artery disease portends a poor outcome, but considerable evidence shows that some of these patients have microvascular abnormalities and endothelial dysfunction and consequently may benefit from aggressive medical management and further testing.

  19. Identification of false positive exercise tests with use of electrocardiographic criteria: A possible role for atrial repolarization waves

    SciTech Connect

    Sapin, P.M.; Koch, G.; Blauwet, M.B.; McCarthy, J.J.; Hinds, S.W.; Gettes, L.S. )

    1991-07-01

    Atrial repolarization waves are opposite in direction to P waves, may have a magnitude of 100 to 200 mu V and may extend into the ST segment and T wave. It was postulated that exaggerated atrial repolarization waves during exercise could produce ST segment depression mimicking myocardial ischemia. The P waves, PR segments and ST segments were studied in leads II, III, aVF and V4 to V6 in 69 patients whose exercise electrocardiogram (ECG) suggested ischemia (100 mu V horizontal or 150 mu V upsloping ST depression 80 ms after the J point). All had a normal ECG at rest. The exercise test in 25 patients (52% male, mean age 53 years) was deemed false positive because of normal coronary arteriograms and left ventricular function (5 patients) or normal stress single photon emission computed tomographic thallium or gated blood pool scans (16 patients), or both (4 patients). Forty-four patients with a similar age and gender distribution, anginal chest pain and at least one coronary stenosis greater than or equal to 80% served as a true positive control group. The false positive group was characterized by (1) markedly downsloping PR segments at peak exercise, (2) longer exercise time and more rapid peak exercise heart rate than those of the true positive group, and (3) absence of exercise-induced chest pain. The false positive group also displayed significantly greater absolute P wave amplitudes at peak exercise and greater augmentation of P wave amplitude by exercise in all six ECG leads than were observed in the true positive group.

  20. Preoperative imaging for DIEA perforator flaps: a comparative study of computed tomographic angiography and Doppler ultrasound.

    PubMed

    Rozen, Warren M; Phillips, Timothy J; Ashton, Mark W; Stella, Damien L; Gibson, Robert N; Taylor, G Ian

    2008-01-01

    Abdominal donor-site flaps, including the transverse rectus abdominis musculocutaneous (TRAM) and deep inferior epigastric artery (DIEA) perforator flaps, are standard in autologous breast reconstruction. With significant variation in the vascular anatomy of the abdominal wall, preoperative imaging is essential for preoperative planning and reducing intraoperative error. Doppler and color duplex sonography have been used with varying results, and the quest continues for optimal preoperative assessment. Computed tomographic angiography has recently been proposed as a noninvasive modality for this purpose. This is the first study to formally compare preoperative Doppler ultrasound with computed tomographic angiography for imaging the DIEA. Eight consecutive patients undergoing DIEA perforator flap surgery for breast reconstruction underwent both computed tomographic angiography and Doppler ultrasound preoperatively. All investigations and procedures were performed at the same institution with the same primary and assisting surgeons and the same radiology team. Computed tomographic angiography was superior to Doppler ultrasound at identifying the course of the DIEA and its branching pattern, and in visualizing its perforators. Preoperative computed tomographic angiography was highly specific (100 percent) and more sensitive in mapping and visualizing perforators (p = 0.0078). It was also proficient at identifying the superficial epigastric arterial system and for effectively displaying the results intraoperatively. It was substantially quicker and removed the interobserver error associated with Doppler ultrasonography. The study was ceased after eight patients because of the overwhelming benefit of computed tomographic angiography over Doppler ultrasonography. Computed tomographic angiography is a valuable imaging modality for the preoperative assessment of the donor-site vascular supply for TRAM and DIEA perforator flaps.

  1. Preoperative imaging for DIEA perforator flaps: a comparative study of computed tomographic angiography and doppler ultrasound.

    PubMed

    Rozen, Warren M; Phillips, Timothy J; Ashton, Mark W; Stella, Damien L; Gibson, Robert N; Taylor, G Ian

    2008-01-01

    Abdominal donor-site flaps, including the transverse rectus abdominis musculocutaneous (TRAM) and deep inferior epigastric artery (DIEA) perforator flaps, are standard in autologous breast reconstruction. With significant variation in the vascular anatomy of the abdominal wall, preoperative imaging is essential for preoperative planning and reducing intraoperative error. Doppler and color duplex sonography have been used with varying results, and the quest continues for optimal preoperative assessment. Computed tomographic angiography has recently been proposed as a noninvasive modality for this purpose. This is the first study to formally compare preoperative Doppler ultrasound with computed tomographic angiography for imaging the DIEA. Eight consecutive patients undergoing DIEA perforator flap surgery for breast reconstruction underwent both computed tomographic angiography and Doppler ultrasound preoperatively. All investigations and procedures were performed at the same institution with the same primary and assisting surgeons and the same radiology team. Computed tomographic angiography was superior to Doppler ultrasound at identifying the course of the DIEA and its branching pattern, and in visualizing its perforators. Preoperative computed tomographic angiography was highly specific (100 percent) and more sensitive in mapping and visualizing perforators (p = 0.0078). It was also proficient at identifying the superficial epigastric arterial system and for effectively displaying the results intraoperatively. It was substantially quicker and removed the interobserver error associated with Doppler ultrasonography. The study was ceased after eight patients because of the overwhelming benefit of computed tomographic angiography over Doppler ultrasonography. Computed tomographic angiography is a valuable imaging modality for the preoperative assessment of the donor-site vascular supply for TRAM and DIEA perforator flaps.

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

    PubMed Central

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

    2015-01-01

    Background 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. Methodology/Principal Findings 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). Conclusion 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. PMID:26161864

  3. Designing occupancy studies when false-positive detections occur

    USGS Publications Warehouse

    Clement, Matthew

    2016-01-01

    1.Recently, estimators have been developed to estimate occupancy probabilities when false-positive detections occur during presence-absence surveys. Some of these estimators combine different types of survey data to improve estimates of occupancy. With these estimators, there is a tradeoff between the number of sample units surveyed, and the number and type of surveys at each sample unit. Guidance on efficient design of studies when false positives occur is unavailable. 2.For a range of scenarios, I identified survey designs that minimized the mean square error of the estimate of occupancy. I considered an approach that uses one survey method and two observation states and an approach that uses two survey methods. For each approach, I used numerical methods to identify optimal survey designs when model assumptions were met and parameter values were correctly anticipated, when parameter values were not correctly anticipated, and when the assumption of no unmodelled detection heterogeneity was violated. 3.Under the approach with two observation states, false positive detections increased the number of recommended surveys, relative to standard occupancy models. If parameter values could not be anticipated, pessimism about detection probabilities avoided poor designs. Detection heterogeneity could require more or fewer repeat surveys, depending on parameter values. If model assumptions were met, the approach with two survey methods was inefficient. However, with poor anticipation of parameter values, with detection heterogeneity, or with removal sampling schemes, combining two survey methods could improve estimates of occupancy. 4.Ignoring false positives can yield biased parameter estimates, yet false positives greatly complicate the design of occupancy studies. Specific guidance for major types of false-positive occupancy models, and for two assumption violations common in field data, can conserve survey resources. This guidance can be used to design efficient

  4. Computed Tomographic Findings of Syphilitic Aortitis: A Case Report

    SciTech Connect

    Kimura, Fumiko; Satoh, Hideyuki; Sakai, Fumikazu; Nishii, Noriko; Tohda, Joe; Fujimura, Mikihiko; Haruta, Shoji; Yamazaki, Kenji; Endo, Masahiro; Sakomura, Yasunari; Kurosama, Hiromi; Kasanuki, Hiroshi

    2004-03-15

    We describe the computerized tomographic (CT) findings of the aortic wall in a case of acute-phase syphilitic arteritis. The delayed phase of the contrast-enhanced CT shows a double-ring configuration of the thick thoracic aortic wall, which is similar to CT findings previously reported for Takayasu arteritis. We speculate that the resemblance of the CT findings for these two diseases accounts for their similar histopathological features.

  5. Selective reduction of CAD false-positive findings

    NASA Astrophysics Data System (ADS)

    Camarlinghi, N.; Gori, I.; Retico, A.; Bagagli, F.

    2010-03-01

    Computer-Aided Detection (CAD) systems are becoming widespread supporting tools to radiologists' diagnosis, especially in screening contexts. However, a large amount of false positive (FP) alarms would inevitably lead both to an undesired possible increase in time for diagnosis, and to a reduction in radiologists' confidence in CAD as a useful tool. Most CAD systems implement as final step of the analysis a classifier which assigns a score to each entry of a list of findings; by thresholding this score it is possible to define the system performance on an annotated validation dataset in terms of a FROC curve (sensitivity vs. FP per scan). To use a CAD as a supportive tool for most clinical activities, an operative point has to be chosen on the system FROC curve, according to the obvious criterion of keeping the sensitivity as high as possible, while maintaining the number of FP alarms still acceptable. The strategy proposed in this study is to choose an operative point with high sensitivity on the CAD FROC curve, then to implement in cascade a further classification step, constituted by a smarter classifier. The key issue of this approach is that the smarter classifier is actually a meta-classifier of more then one decision system, each specialized in rejecting a particular type of FP findings generated by the CAD. The application of this approach to a dataset of 16 lung CT scans previously processed by the VBNACAD system is presented. The lung CT VBNACAD performance of 87.1% sensitivity to juxtapleural nodules with 18.5 FP per scan is improved up to 10.1 FP per scan while maintaining the same value of sensitivity. This work has been carried out in the framework of the MAGIC-V collaboration.

  6. False positives in psychiatric diagnosis: implications for human freedom.

    PubMed

    Wakefield, Jerome C

    2010-02-01

    Current symptom-based DSM and ICD diagnostic criteria for mental disorders are prone to yielding false positives because they ignore the context of symptoms. This is often seen as a benign flaw because problems of living and emotional suffering, even if not true disorders, may benefit from support and treatment. However, diagnosis of a disorder in our society has many ramifications not only for treatment choice but for broader social reactions to the diagnosed individual. In particular, mental disorders impose a sick role on individuals and place a burden upon them to change; thus, disorders decrease the level of respect and acceptance generally accorded to those with even annoying normal variations in traits and features. Thus, minimizing false positives is important to a pluralistic society. The harmful dysfunction analysis of disorder is used to diagnose the sources of likely false positives, and propose potential remedies to the current weaknesses in the validity of diagnostic criteria.

  7. Escitalopram-Induced Amenorrhea and False Positive Urine Pregnancy Test

    PubMed Central

    Hour, Siv; Gunasekar, Palanikumar; Gray, Caron; Smith, James F.

    2017-01-01

    Escitalopram is a selective serotonin reuptake inhibitor antidepressant approved by the Food and Drug Administration for the treatment of major depressive disorder and generalized anxiety disorder. A 34-year-old female patient with major depressive disorder developed amenorrhea and had a false-positive urine pregnancy test after initiation of escitalopram treatment. To our knowledge, no published case report of amenorrhea and false-positive urine pregnancy tests in women taking escitalopram exists. This case report suggests that women of child-bearing age should be carefully monitored for amenorrhea while they are on an antidepressant treatment regimen. PMID:28197332

  8. Evaluation of computerized detection of pulmonary embolism in independent data sets of computed tomographic pulmonary angiographic (CTPA) scans

    NASA Astrophysics Data System (ADS)

    Zhou, Chuan; Chan, Heang-Ping; Sahiner, Berkman; Hadjiiski, Lubomir M.; Chughtai, Aamer; Patel, Smita; Wei, Jun; Cascade, Philip N.; Kazerooni, Ella A.

    2009-02-01

    Computed tomographic pulmonary angiography (CTPA) has been reported to be an effective means for clinical diagnosis of pulmonary embolism (PE). We are developing a computer-aided diagnosis (CAD) system for assisting radiologists in detection of pulmonary embolism in CTPA images. The pulmonary vessel tree is extracted based on the analysis of eigenvalues of Hessian matrices at multiple scales followed by 3D hierarchical EM segmentation. A multiprescreening method is designed to identify suspicious PEs along the extracted vessels. A linear discriminant analysis (LDA) classifier with feature selection is then used to reduce false positives (FPs). Two data sets of 59 and 69 CTPA PE cases were randomly selected from patient files at the University of Michigan (UM) and the PIOPED II study, respectively, and used as independent training and test sets. The PEs that were identified by three experienced thoracic radiologists were used as the gold standard. The detection performance of the CAD system was assessed by free response receiver operating characteristic analysis. The results indicated that our PE detection system can achieve a sensitivity of 80% at 18.9 FPs/case on the PIOPED cases when the LDA classifier was trained with the UM cases. The test sensitivity with the UM cases is 80% at 22.6 FPs/cases when the LDA classifier was trained with the PIOPED cases.

  9. False positive reaction for carboxyhemoglobin in blood from liver tissue.

    PubMed

    Lund, A

    1979-01-01

    On spectrophotometric determination of carboxyhemoglobin in blood collected from the liver of three bodies at three days post-mortem, false positive results were found (5--15 per cent saturation), since samples of heart blood collected a few hours after death did not contain carboxyhemoglobin.

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

    ERIC Educational Resources Information Center

    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. A Demonstration of Regression False Positive Selection in Data Mining

    ERIC Educational Resources Information Center

    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…

  12. Looking for Childhood Schizophrenia: Case Series of False Positives.

    ERIC Educational Resources Information Center

    Stayer, Catherine; Sporn, Alexandra; Gogtay, Nitin; Tossell, Julia; Lenane, Marge; Gochman, Peter; Rapoport, Judith L.

    2004-01-01

    Extensive experience with the diagnosis of childhood-onset schizophrenia indicates a high rate of false positives. Most mislabeled patients have chronic disabling, affective, or behavioral disorders. The authors report the cases of three children who passed stringent initial childhood-onset schizophrenia "screens" but had no chronic psychotic…

  13. High false positive rates in common sensory threshold tests.

    PubMed

    Running, Cordelia A

    2015-02-01

    Large variability in thresholds to sensory stimuli is observed frequently even in healthy populations. Much of this variability is attributed to genetics and day-to-day fluctuation in sensitivity. However, false positives are also contributing to the variability seen in these tests. In this study, random number generation was used to simulate responses in threshold methods using different "stopping rules": ascending 2-alternative forced choice (AFC) with 5 correct responses; ascending 3-AFC with 3 or 4 correct responses; staircase 2-AFC with 1 incorrect up and 2 incorrect down, as well as 1 up 4 down and 5 or 7 reversals; staircase 3-AFC with 1 up 2 down and 5 or 7 reversals. Formulas are presented for rates of false positives in the ascending methods, and curves were generated for the staircase methods. Overall, the staircase methods generally had lower false positive rates, but these methods were influenced even more by number of presentations than ascending methods. Generally, the high rates of error in all these methods should encourage researchers to conduct multiple tests per individual and/or select a method that can correct for false positives, such as fitting a logistic curve to a range of responses.

  14. Detecting False Positives in Multielement Designs: Implications for Brief Assessments

    ERIC Educational Resources Information Center

    Bartlett, Sara M.; Rapp, John T.; Henrickson, Marissa L.

    2011-01-01

    The authors assessed the extent to which multielement designs produced false positives using continuous duration recording (CDR) and interval recording with 10-s and 1-min interval sizes. Specifically, they created 6,000 graphs with multielement designs that varied in the number of data paths, and the number of data points per data path, using a…

  15. Ascites causing a false-positive radionuclide liver image

    SciTech Connect

    Williams, A.G. Jr.; Christie, J.H.; Mettler, F.A. Jr.; Wicks, J.D.

    1983-02-01

    False-positive radionuclide liver images can occur due to impingement on the liver by adjacent normal anatomic structures or adjacent pathologic masses or fluid collections. A patient with ascites in the anterior subphrenic space had an apparent cold lesion in the left lobe of the liver. Ultrasonography demonstrated a normal left lobe and localized the fluid collection.

  16. Looking for Childhood Schizophrenia: Case Series of False Positives.

    ERIC Educational Resources Information Center

    Stayer, Catherine; Sporn, Alexandra; Gogtay, Nitin; Tossell, Julia; Lenane, Marge; Gochman, Peter; Rapoport, Judith L.

    2004-01-01

    Extensive experience with the diagnosis of childhood-onset schizophrenia indicates a high rate of false positives. Most mislabeled patients have chronic disabling, affective, or behavioral disorders. The authors report the cases of three children who passed stringent initial childhood-onset schizophrenia "screens" but had no chronic psychotic…

  17. Detecting False Positives in Multielement Designs: Implications for Brief Assessments

    ERIC Educational Resources Information Center

    Bartlett, Sara M.; Rapp, John T.; Henrickson, Marissa L.

    2011-01-01

    The authors assessed the extent to which multielement designs produced false positives using continuous duration recording (CDR) and interval recording with 10-s and 1-min interval sizes. Specifically, they created 6,000 graphs with multielement designs that varied in the number of data paths, and the number of data points per data path, using a…

  18. Epidemiology, Public Health, and the Rhetoric of False Positives

    PubMed Central

    Blair, Aaron; Saracci, Rodolfo; Vineis, Paolo; Cocco, Pierluigi; Forastiere, Francesco; Grandjean, Philippe; Kogevinas, Manolis; Kriebel, David; McMichael, Anthony; Pearce, Neil; Porta, Miquel; Samet, Jonathan; Sandler, Dale P.; Costantini, Adele Seniori; Vainio, Harri

    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 for epistemological modesty. J Natl Cancer Inst 100:988–995 (2008)] argued that “epidemiology is particularly prone to the generation of false-positive results.” They also said “the tendency to emphasize and over-interpret what appear to be new findings is commonplace, perhaps in part because of a belief that the findings provide information that may ultimately improve public health” and that “this tendency to hype new findings increases the likelihood of downplaying inconsistencies within the data or any lack of concordance with other sources of evidence.” The authors supported these serious charges against epidemiology and epidemiologists with few examples. Although we acknowledge that false positives do occur, we view the position of Boffetta and colleagues on false positives as unbalanced and potentially harmful to public health. Objective We aim to provide a more balanced evaluation of epidemiology and its contribution to public health discourse. Discussion Boffetta and colleagues ignore the fact that false negatives may arise from the very processes that they tout as generating false-positive results. We further disagree with their proposition that false-positive results from a single study will lead to faulty decision making in matters of public health importance. In practice, such public health evaluations are based on all the data available from all relevant disciplines and never to our knowledge on a single study. Conclusions The lack of balance by Boffetta and colleagues in their evaluation of the impact of false-positive findings on epidemiology, the charge that “methodological vigilance is often absent” in epidemiologists’ interpretation of

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

    PubMed

    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

  20. [Hardware-software system for monitoring parameters and characteristics of X-ray computer tomographs under operation conditions].

    PubMed

    Blinov, N N; Zelikman, M I; Kruchinin, S A

    2007-01-01

    The results of testing of hardware and software for monitoring parameters (mean number of CT units, noise, field uniformity, high-contrast spatial resolution, layer width, dose) and characteristics (modulation transfer function) of X-ray computer tomographs are presented. The developed hardware and software are used to monitor the stability of X-ray computer tomograph parameters under operation conditions.

  1. Computer-aided detection of pulmonary embolism in computed tomographic pulmonary angiography (CTPA): performance evaluation with independent data sets.

    PubMed

    Zhou, Chuan; Chan, Heang-Ping; Sahiner, Berkman; Hadjiiski, Lubomir M; Chughtai, Aamer; Patel, Smita; Wei, Jun; Cascade, Philip N; Kazerooni, Ella A

    2009-08-01

    The authors are developing a computer-aided detection system for pulmonary emboli (PE) in computed tomographic pulmonary angiography (CTPA) scans. The pulmonary vessel tree is extracted using a 3D expectation-maximization segmentation method based on the analysis of eigen-values of Hessian matrices at multiple scales. A parallel multiprescreening method is applied to the segmented vessels to identify volume of interests (VOIs) that contained suspicious PE. A linear discriminant analysis (LDA) classifier with feature selection is designed to reduce false positives (FPs). Features that characterize the contrast, gray level, and size of PE are extracted as input predictor variables to the LDA classifier. With the IRB approval, 59 CTPA PE cases were collected retrospectively from the patient files (UM cases). With access permission, 69 CTPA PE cases were randomly selected from the data set of the prospective investigation of pulmonary embolism diagnosis (PIOPED) II clinical trial. Extensive lung parenchymal or pleural diseases were present in 22/59 UM and 26/69 PIOPED cases. Experienced thoracic radiologists manually marked 595 and 800 PE as the reference standards in the UM and PIOPED data sets, respectively. PE occlusion of arteries ranged from 5% to 100%, with PE located from the main pulmonary artery to the subsegmental artery levels. Of the 595 PE identified in the UM cases, 245 and 350 PE were located in the subsegmental arteries and the more proximal arteries, respectively. The detection performance was assessed by free response ROC (FROC) analysis. The FROC analysis indicated that the PE detection system could achieve an overall sensitivity of 80% at 18.9 FPs/case for the PIOPED cases when the LDA classifier was trained with the UM cases. The test sensitivity with the UM cases was 80% at 22.6 FPs/cases when the LDA classifier was trained with the PIOPED cases. The detection performance depended on the arterial level where the PE was located and on the

  2. Computer-aided detection of pulmonary embolism in computed tomographic pulmonary angiography (CTPA): Performance evaluation with independent data sets

    PubMed Central

    Zhou, Chuan; Chan, Heang-Ping; Sahiner, Berkman; Hadjiiski, Lubomir M.; Chughtai, Aamer; Patel, Smita; Wei, Jun; Cascade, Philip N.; Kazerooni, Ella A.

    2009-01-01

    The authors are developing a computer-aided detection system for pulmonary emboli (PE) in computed tomographic pulmonary angiography (CTPA) scans. The pulmonary vessel tree is extracted using a 3D expectation-maximization segmentation method based on the analysis of eigenvalues of Hessian matrices at multiple scales. A parallel multiprescreening method is applied to the segmented vessels to identify volume of interests (VOIs) that contained suspicious PE. A linear discriminant analysis (LDA) classifier with feature selection is designed to reduce false positives (FPs). Features that characterize the contrast, gray level, and size of PE are extracted as input predictor variables to the LDA classifier. With the IRB approval, 59 CTPA PE cases were collected retrospectively from the patient files (UM cases). With access permission, 69 CTPA PE cases were randomly selected from the data set of the prospective investigation of pulmonary embolism diagnosis (PIOPED) II clinical trial. Extensive lung parenchymal or pleural diseases were present in 22∕59 UM and 26∕69 PIOPED cases. Experienced thoracic radiologists manually marked 595 and 800 PE as the reference standards in the UM and PIOPED data sets, respectively. PE occlusion of arteries ranged from 5% to 100%, with PE located from the main pulmonary artery to the subsegmental artery levels. Of the 595 PE identified in the UM cases, 245 and 350 PE were located in the subsegmental arteries and the more proximal arteries, respectively. The detection performance was assessed by free response ROC (FROC) analysis. The FROC analysis indicated that the PE detection system could achieve an overall sensitivity of 80% at 18.9 FPs∕case for the PIOPED cases when the LDA classifier was trained with the UM cases. The test sensitivity with the UM cases was 80% at 22.6 FPs∕cases when the LDA classifier was trained with the PIOPED cases. The detection performance depended on the arterial level where the PE was located and on the

  3. Analysis for chemical agent breakdown products: Avoiding IMPA false positives

    SciTech Connect

    Ives, K.M.; Markowitz, V.

    1996-12-31

    Cleanup of DOD sites where chemical warfare agents have been used or stored presents a number of unique problems. Isopropylmethylphosphonic Acid (IMPA), a degradation product of Sarin (GB), is one important contaminant to be monitored at many such sites. IMPA has historically been determined by Army Environmental Center (AEC) method UT02, an ion chromatography method. This method is prone to serious interference problems which can lead an inexperienced analyst to report false positive results. A study of interferences present in groundwater samples taken from a US military installation was undertaken. The interference problems were identified, and techniques were developed which minimize the problem in most samples. These techniques have been used by the authors in several large studies at DOD sites, and have virtually eliminated false positive problems.

  4. Gallbladder tuberculosis: False-positive PET diagnosis of gallbladder cancer

    PubMed Central

    Ramia, JM; Muffak, K; Fernández, A; Villar, J; Garrote, D; Ferron, JA

    2006-01-01

    Gallbladder tuberculosis (GT) is an extremely rare disease, and very few cases have been reported in the literature. The first case of GT was described in 1870 by Gaucher. A correct preoperative diagnosis of GT is unusual, and it is frequently confused with various gallbladder diseases. We present a new case of a patient who underwent surgery with the preoperative diagnosis of gallbladder cancer after a false positive positron emission tomography scan in the diagnostic work-up. PMID:17072992

  5. False-positive colorimetric capnometry after ingestion of carbonated beverages.

    PubMed

    Keller, William Ryan; Biehler, Jefrey; Linares, Marc Yves-Rene; Garcia-Pena, Barbara M

    2009-02-01

    To investigate the potential for false-positive colorimetric capnometric readings during esophageal intubation after ingestion of carbonated beverages. The study was conducted in the human patient simulation laboratory of a tertiary care pediatric hospital. The sole outcome measurement was the capnometric indicator membrane color after expiration for 10 breaths. Readings were recorded for scenarios simulating 8 different models. For all carbonated beverage trials with a cuffed endotracheal tube (ETT) and those with 2 and 6 oz of beverage in the gastric sac with an uncuffed ETT, a false-positive result was observed on the capnometer's indicator for breaths 1 through 10. The sensitivity of the capnometer for the detection of CO2 after full exhalation of breath 6 for these trials was 100%. For trials containing 12 oz in the gastric sac and an uncuffed ETT, yellow was observed on the capnometer indicator for breaths 1 through 3, tan for breaths 4 through 6, and purple for breath 7. The sensitivity of the capnometer for the detection of adequate CO2 after full exhalation of breath 6 for these trials was 0%. The overall sensitivity of the capnometer for the carbonated beverage models with a cuffed ETT was 100%, whereas the combined sensitivity for the trials with an uncuffed ETT was 67%. Under proper circumstances, a significant potential exists for false-positive colorimetric capnometric results in the presence of even small amounts of carbonated beverages.

  6. Reducing False Positives in Runtime Analysis of Deadlocks

    NASA Technical Reports Server (NTRS)

    Bensalem, Saddek; Havelund, Klaus; Clancy, Daniel (Technical Monitor)

    2002-01-01

    This paper presents an improvement of a standard algorithm for detecting dead-lock potentials in multi-threaded programs, in that it reduces the number of false positives. The standard algorithm works as follows. The multi-threaded program under observation is executed, while lock and unlock events are observed. A graph of locks is built, with edges between locks symbolizing locking orders. Any cycle in the graph signifies a potential for a deadlock. The typical standard example is the group of dining philosophers sharing forks. The algorithm is interesting because it can catch deadlock potentials even though no deadlocks occur in the examined trace, and at the same time it scales very well in contrast t o more formal approaches to deadlock detection. The algorithm, however, can yield false positives (as well as false negatives). The extension of the algorithm described in this paper reduces the amount of false positives for three particular cases: when a gate lock protects a cycle, when a single thread introduces a cycle, and when the code segments in different threads that cause the cycle can actually not execute in parallel. The paper formalizes a theory for dynamic deadlock detection and compares it to model checking and static analysis techniques. It furthermore describes an implementation for analyzing Java programs and its application to two case studies: a planetary rover and a space craft altitude control system.

  7. Computed tomographic findings of cerebral fat embolism following multiple bone fractures.

    PubMed

    Law, Huong Ling; Wong, Siong Lung; Tan, Suzet

    2013-02-01

    Fat embolism to the lungs and brain is an uncommon complication following fractures. Few reports with descriptions of computed tomographic (CT) findings of emboli to the brain or cerebral fat embolism are available. We report a case of cerebral fat embolism following multiple skeletal fractures and present its CT findings here.

  8. Computed tomographic enteroclysis with air and virtual enteroscopy: protocol and feasibility for small bowel evaluation.

    PubMed

    Yoshikawa, Toshiyuki; Takehara, Yasuo; Kikuyama, Masataka; Takeuchi, Ken; Hanai, Hiroyuki

    2012-04-01

    We describe our optimized protocol for computed tomographic enteroclysis using air as the contrast material and report an early assessment of its clinical performance. Thirty-one examinations of computed tomographic enteroclysis with air were performed in 30 patients in our hospital from September 2008 to September 2010. The volume of injected air and intra-intestinal pressure were monitored in 16 cases. The data were reviewed for ratios of successful whole small bowel depictions out of the total number of examinations for patients without stenosis. Efforts were made to confirm depicted abnormal findings when possible by other imaging techniques, intra-operative findings, histopathological findings, and subsequent history. The injected air volume and final intra-intestinal pressure were 2925 ± 686 ml and 24.5 ± 7.1cm H₂O in cases without stenosis. In 19 examinations with anterograde air injection for patients without stenosis, whole small bowel depiction was achieved in 16 (84.2%). Computed tomographic enteroclysis with air was useful for detecting strictures (in Crohn's disease, malignant lymphoma, metastatic carcinoma), Meckel's diverticulum, and for excluding other obstructive conditions in ileus. Computed tomographic enteroclysis with air has a potential to enable the exploration of the whole small bowel, thereby providing information of small bowel lesions that complements other techniques. Copyright © 2011 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.

  9. The interface sign: a computed tomographic sign for distinguishig pleural and intra-abdominal fluid

    SciTech Connect

    Teplick, J.G.; Teplick, S.K.; Goodman, L.; Haskin, M.E.

    1982-07-01

    On computed tomographic scans of the upper abdomen the interface sign can help distinguish pleural and intra-abdominal fluid readily and accurately.A hazy interface between the fluid and liver or spleen is characteristic of pleural fluid. A sharp interface is characteristic of ascites. The interface sign has proved to be accurate in 30 consecutive cases.

  10. Parallel computing for simultaneous iterative tomographic imaging by graphics processing units

    NASA Astrophysics Data System (ADS)

    Bello-Maldonado, Pedro D.; López, Ricardo; Rogers, Colleen; Jin, Yuanwei; Lu, Enyue

    2016-05-01

    In this paper, we address the problem of accelerating inversion algorithms for nonlinear acoustic tomographic imaging by parallel computing on graphics processing units (GPUs). Nonlinear inversion algorithms for tomographic imaging often rely on iterative algorithms for solving an inverse problem, thus computationally intensive. We study the simultaneous iterative reconstruction technique (SIRT) for the multiple-input-multiple-output (MIMO) tomography algorithm which enables parallel computations of the grid points as well as the parallel execution of multiple source excitation. Using graphics processing units (GPUs) and the Compute Unified Device Architecture (CUDA) programming model an overall improvement of 26.33x was achieved when combining both approaches compared with sequential algorithms. Furthermore we propose an adaptive iterative relaxation factor and the use of non-uniform weights to improve the overall convergence of the algorithm. Using these techniques, fast computations can be performed in parallel without the loss of image quality during the reconstruction process.

  11. EMPLOYING TOPOGRAPHICAL HEIGHT MAP IN COLONIC POLYP MEASUREMENT AND FALSE POSITIVE REDUCTION

    PubMed Central

    Yao, Jianhua; Li, Jiang; Summers, Ronald M.

    2008-01-01

    CT Colonography (CTC) is an emerging minimally invasive technique for screening and diagnosing colon cancers. Computer Aided Detection (CAD) techniques can increase sensitivity and reduce false positives. Inspired by the way radiologists detect polyps via 3D virtual fly-through in CTC, we borrowed the idea from geographic information systems to employ topographical height map in colonic polyp measurement and false positive reduction. After a curvature based filtering and a 3D CT feature classifier, a height map is computed for each detection using a ray-casting algorithm. We design a concentric index to characterize the concentric pattern in polyp height map based on the fact that polyps are protrusions from the colon wall and round in shape. The height map is optimized through a multi-scale spiral spherical search to maximize the concentric index. We derive several topographic features from the map and compute texture features based on wavelet decomposition. We then send the features to a committee of support vector machines for classification. We have trained our method on 394 patients (71 polyps) and tested it on 792 patients (226 polyps). Results showed that we can achieve 95% sensitivity at 2.4 false positives per patient and the height map features can reduce false positives by more than 50%. We compute the polyp height and width measurements and correlate them with manual measurements. The Pearson correlations are 0.74 (p=0.11) and 0.75 (p=0.17) for height and width, respectively. PMID:19578483

  12. A study of temporomandibular joint osteoarthritis using computed tomographic imaging.

    PubMed

    Massilla Mani, F; Sivasubramanian, S Satha

    2016-06-01

    This study aimed to determine the various bony changes in osteoarthritis (OA) of elderly patients who are suffering from temporomandibular joint dysfunction (TMD) and to find if all the changes manifesting in generalized OA were presented in temporomandibular joint (TMJ). Thirty TMJs of fifteen elderly patients who were diagnosed with TMD were selected for the study. Patient with TMD were subjected to computerized tomographic (CT) imaging, and the various bony changes in the TMJ were recorded. CT study of TMJ showed that there is a positive evidence of joint involvement in 80% of the cases. In this study, female patients were more commonly affected by OA than the males. The condylar changes (69.93%) are more common than the changes in the articular eminence (6.6%) and condylar fossa (10%). About 56.6% of TMJ in the study was affected by the early manifestations of the OA. CT study showed that there is a positive evidence of TMJ involvement in the elderly patients with TMD. The results show that condylar changes are more common than the changes in the articular eminence and condylar fossa. The study also shows that most of the patients are affected by early TMJ OA; hence, initiating treatment at early stages may prevent the disease progression. Copyright © 2016 Chang Gung University. Published by Elsevier B.V. All rights reserved.

  13. Primary pontine haemorrhage: clinical and computed tomographic correlations.

    PubMed Central

    Weisberg, L A

    1986-01-01

    The clinical and computerised tomographic findings in 40 patients with primary pontine haemorrhage were reviewed. Twenty-nine patients were hypertensive. Four patients had angiographic or necropsy evidence of vascular malformations. In 33 cases, there was rapid deterioration to maximal neurological deficit; whereas in seven cases, there was sudden onset but subsequent progression to maximal deficit 24 hours to 5 days following the initial ictus. Seven patients had clinical features considered atypical for pontine haemorrhage. Five patients survived and four of these were capable of performing activities of daily living within 3 months of the haemorrhage. In all cases CT showed a hyperdense non-enhancing brain stem haematoma. There was evidence of ventricular extension in 27 cases. There was CT evidence of subarachnoid blood in only two patients who also had vascular malformations. In 26 cases, there was CT evidence that the haematoma extended to the midbrain and in four cases to the thalamic region. In six cases CT was repeated 6 to 21 days after the initial scan and it showed resolution of the haematoma in size and density; none of the haematomas showed post-contrast enhancement on initial or follow-up CT. Images PMID:3701344

  14. Automatic lung nodule graph cuts segmentation with deep learning false positive reduction

    NASA Astrophysics Data System (ADS)

    Sun, Wenqing; Huang, Xia; Tseng, Tzu-Liang Bill; Qian, Wei

    2017-03-01

    To automatic detect lung nodules from CT images, we designed a two stage computer aided detection (CAD) system. The first stage is graph cuts segmentation to identify and segment the nodule candidates, and the second stage is convolutional neural network for false positive reduction. The dataset contains 595 CT cases randomly selected from Lung Image Database Consortium and Image Database Resource Initiative (LIDC/IDRI) and the 305 pulmonary nodules achieved diagnosis consensus by all four experienced radiologists were our detection targets. Consider each slice as an individual sample, 2844 nodules were included in our database. The graph cuts segmentation was conducted in a two-dimension manner, 2733 lung nodule ROIs are successfully identified and segmented. With a false positive reduction by a seven-layer convolutional neural network, 2535 nodules remain detected while the false positive dropped to 31.6%. The average F-measure of segmented lung nodule tissue is 0.8501.

  15. Mechanisms for Generating False Positives for Extrasolar Life

    NASA Astrophysics Data System (ADS)

    Domagal-Goldman, Shawn; Meadows, Victoria; Schwieterman, Edward; Luger, Rodrigo; Wordsworth, Robin; Barnes, Rory; Segura, Antigona; Claire, Mark; Virtual Planetary Laboratory

    2015-01-01

    Future mission concepts designed to look for life generally plan to search for oxygen (O2), ozone (O3), and/or methane (CH4). However, mechanisms exist for generating each of these species abiotically. In this presentation, we will review these processes, and discuss the atmospheres that result from them. In general, false positives can form in atmospheres with severe redox imbalance. This redox imbalance can also be thought of as extreme elemental composition, skewed towards very high or very low O/H ratios. Specific examples of this include: 1) loss of H through the top of a planetary atmosphere that leads to high O/H and an atmosphere rich in O2 and O3 2) atmospheres whose volcanism is O-rich and H-poor (i.e., highly oxidized), which leads to an atmosphere that with high O/H that can accumulate O3 and potentially O2 3) atmospheres in which H escape is slow, leading to low O/H and accumulation of CH4 and 4) atmospheres in which volcanic outgassing is H-rich (highly reduced), leading to low O/H and potential accumulation of CH4. Each of these cases would constitute a 'false positive' for life if O2, O3, or CH4 were detected without obtaining the chemical atmospheric context that could indicate a severe redox imbalance exists.Methods exist for discriminating between these 'false positives' where the gases arise from abiotic sources, and 'true positives' where the gases arise by biological sources. The best means of doing this is to obtain measurements of both O-rich (O2/O3) and H-rich (CH4) species, allowing identification of non-extreme O/H ratios in the atmosphere, and eliminating this abiotic source of O2, O3, and CH4. Because this is the most likely cause of abiotic production of these species, the elimination of this explanation would indicate that these gases were instead likely produced by biology.More specific methods to identify each of these false positives mechanisms also exist, but will not be discussed in detail in this presentation.

  16. Detection of various anatomic patterns of root canals in mandibular incisors using digital periapical radiography, 3 cone-beam computed tomographic scanners, and micro-computed tomographic imaging.

    PubMed

    Paes da Silva Ramos Fernandes, Luciana Maria; Rice, Dwight; Ordinola-Zapata, Ronald; Alvares Capelozza, Ana Lucia; Bramante, Clovis Monteiro; Jaramillo, David; Christensen, Heidi

    2014-01-01

    The purpose of this study was to compare the accuracy of digital periapical (PA) radiography and 3 cone-beam computed tomographic (CBCT) scanners in the identification of various internal anatomic patterns in mandibular incisors. Forty mandibular incisors were scanned using micro-computed tomographic imaging as the gold standard to establish the internal anatomic pattern. The number of root canals and internal patterns were classified into type I (single canal, n = 12), type Ia (single oval canal, n = 12), and type III (2 canals, n = 16). The teeth were placed in a human mandible, and digital PA radiography and 3 CBCT scans (Kodak 9000 3D [Carestream Health, Rochester, NY], Veraviewepocs 3De [J Morita MFG Corp, Kyoto, Japan], NewTom 5G [QR Srl, Verona, Italy]) were performed. Two blinded examiners classified each tooth's anatomic pattern, which were then compared with the micro-computed tomographic determinations. Considering type I and type Ia, which both presented with 1 root canal, there was a high degree of accuracy for all methods used (P > .05). The same result was found for type III. When identifying the shape of single canals (type I), CBCT imaging was more accurate compared with PA radiography. Concerning oval canals (type Ia), there was a significant difference between PA radiography and NewTom CBCT (PA radiography = 44%, NewTom = 88%). However, there were no significant differences between the 3 CBCT units. Double-exposure digital PA radiography for mandibular incisors is sufficient for the identification of the number of root canals. All CBCT devices showed improved accuracy in the identification of single root canal anatomy when a narrow canal was present. However, the identification of oval canals was improved only with the NewTom CBCT device. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  17. DSM-5, psychiatric epidemiology and the false positives problem.

    PubMed

    Wakefield, J C

    2015-06-01

    The revision effort leading to the publication of the fifth edition of the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM-5) was flawed in process, goals and outcome. The revision process suffered from lack of an adequate public record of the rationale for changes, thus shortchanging future scholarship. The goals, such as dimensionalising diagnosis, incorporating biomarkers and separating impairment from diagnosis, were ill-considered and mostly abandoned. However, DSM-5's greatest problem, and the target of the most vigorous and sustained criticism, was its failure to take seriously the false positives problem. By expanding diagnosis beyond plausible boundaries in ways inconsistent with DSM-5's own definition of disorder, DSM-5 threatened the validity of psychiatric research, including especially psychiatric epidemiology. I present four examples: increasing the symptom options while decreasing the diagnostic threshold for substance use disorder, elimination of the bereavement exclusion from major depression, allowing verbal arguments as evidence of intermittent explosive disorder and expanding attention-deficit/hyperactivity disorder to adults before addressing its manifest false positives problems.

  18. ON THE LOW FALSE POSITIVE PROBABILITIES OF KEPLER PLANET CANDIDATES

    SciTech Connect

    Morton, Timothy D.; Johnson, John Asher E-mail: johnjohn@astro.caltech.edu

    2011-09-10

    We present a framework to conservatively estimate the probability that any particular planet-like transit signal observed by the Kepler mission is in fact a planet, prior to any ground-based follow-up efforts. We use Monte Carlo methods based on stellar population synthesis and Galactic structure models, and report false positive probabilities (FPPs) for every Kepler Object of Interest, assuming a 20% intrinsic occurrence rate of close-in planets in the radius range 0.5 R{sub +} < R{sub p} < 20 R{sub +}. Nearly 90% of the 1235 candidates have FPP <10%, and over half have FPP <5%. This probability varies with the magnitude and Galactic latitude of the target star, and with the depth of the transit signal-deeper signals generally have higher FPPs than shallower signals. We establish that a single deep high-resolution image will be an effective follow-up tool for the shallowest (Earth-sized) transits, providing the quickest route toward probabilistically validating the smallest candidates by potentially decreasing the FPP of an Earth-sized transit around a faint star from >10% to <1%. Since Kepler has detected many more planetary signals than can be positively confirmed with ground-based follow-up efforts in the near term, these calculations will be crucial to using the ensemble of Kepler data to determine population characteristics of planetary systems. We also describe how our analysis complements the Kepler team's more detailed BLENDER false positive analysis for planet validation.

  19. On the Low False Positive Probabilities of Kepler Planet Candidates

    NASA Astrophysics Data System (ADS)

    Morton, Timothy D.; Johnson, John Asher

    2011-09-01

    We present a framework to conservatively estimate the probability that any particular planet-like transit signal observed by the Kepler mission is in fact a planet, prior to any ground-based follow-up efforts. We use Monte Carlo methods based on stellar population synthesis and Galactic structure models, and report false positive probabilities (FPPs) for every Kepler Object of Interest, assuming a 20% intrinsic occurrence rate of close-in planets in the radius range 0.5 R ⊕ < Rp < 20 R ⊕. Nearly 90% of the 1235 candidates have FPP <10%, and over half have FPP <5%. This probability varies with the magnitude and Galactic latitude of the target star, and with the depth of the transit signal—deeper signals generally have higher FPPs than shallower signals. We establish that a single deep high-resolution image will be an effective follow-up tool for the shallowest (Earth-sized) transits, providing the quickest route toward probabilistically validating the smallest candidates by potentially decreasing the FPP of an Earth-sized transit around a faint star from >10% to <1%. Since Kepler has detected many more planetary signals than can be positively confirmed with ground-based follow-up efforts in the near term, these calculations will be crucial to using the ensemble of Kepler data to determine population characteristics of planetary systems. We also describe how our analysis complements the Kepler team's more detailed BLENDER false positive analysis for planet validation.

  20. MTS in false positive reduction for multi-sensor fusion

    NASA Astrophysics Data System (ADS)

    Woodley, Robert; Gosnell, Michael; Cudney, Elizabeth

    2014-05-01

    The Mahalanobis Taguchi System (MTS) is a relatively new tool in the vehicle health maintenance domain, but has some distinct advantages in current multi-sensor implementations. The use of Mahalanobis Spaces (MS) allows the algorithm to identify characteristics of sensor signals to identify behaviors in machines. MTS is extremely powerful with the caveat that the correct variables are selected to form the MS. In this research work, 56 sensors monitor various aspects of the vehicles. Typically, using the MTS process, identification of useful variables is preceded by validation of the measurements scale. However, the MTS approach doesn't directly include any mitigating steps should the measurement scale not be validated. Existing work has performed outlier removal in construction of the MS, which can lead to better validation. In our approach, we modify the outlier removal process with more liberal definitions of outliers to better identify variables' impact prior to identification of useful variables. This subtle change substantially lowered the false positive rate due to the fact that additional variables were retained. Traditional MTS approaches identify useful variables only to the extent they provide usefulness in identifying the positive (abnormal) condition. The impact of removing false negatives is not included. Initial results show our approach can reduce false positive values while still maintaining complete fault identification for this vehicle data set.

  1. Phenolphthalein false-positive reactions from legume root nodules.

    PubMed

    Petersen, Daniel; Kovacs, Frank

    2014-03-01

    Presumptive tests for blood play a critical role in the examination of physical evidence and in the determination of subsequent analysis. The catalytic power of hemoglobin allows colorimetric reactions employing phenolphthalein (Kastle-Meyer test) to indicate "whether" blood is present. Consequently, DNA profiles extracted from phenolphthalein-positive stains are presumed to be from blood on the evidentiary item and can lead to the identification of "whose" blood is present. Crushed nodules from a variety of legumes yielded phenolphthalein false-positive reactions that were indistinguishable from true bloodstains both in color quality and in developmental time frame. Clothing and other materials stained by nodules also yielded phenolphthalein false-positive reactivity for several years after nodule exposure. Nodules from leguminous plants contain a protein (leghemoglobin) which is structurally and functionally similar to hemoglobin. Testing of purified leghemoglobin confirmed this protein as a source of phenolphthalein reactivity. A scenario is presented showing how the presence of leghemoglobin from nodule staining can mislead investigators. © 2013 American Academy of Forensic Sciences.

  2. THE XO PLANETARY SURVEY PROJECT: ASTROPHYSICAL FALSE POSITIVES

    SciTech Connect

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

    2010-07-15

    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.

  3. Modeling false positive error making patterns in radiology trainees for improved mammography education.

    PubMed

    Zhang, Jing; Silber, James I; Mazurowski, Maciej A

    2015-04-01

    While mammography notably contributes to earlier detection of breast cancer, it has its limitations, including a large number of false positive exams. Improved radiology education could potentially contribute to alleviating this issue. Toward this goal, in this paper we propose an algorithm for modeling of false positive error making among radiology trainees. Identifying troublesome locations for the trainees could focus their training and in turn improve their performance. The algorithm proposed in this paper predicts locations that are likely to result in a false positive error for each trainee based on the previous annotations made by the trainee. The algorithm consists of three steps. First, the suspicious false positive locations are identified in mammograms by Difference of Gaussian filter and suspicious regions are segmented by computer vision-based segmentation algorithms. Second, 133 features are extracted for each suspicious region to describe its distinctive characteristics. Third, a random forest classifier is applied to predict the likelihood of the trainee making a false positive error using the extracted features. The random forest classifier is trained using previous annotations made by the trainee. We evaluated the algorithm using data from a reader study in which 3 experts and 10 trainees interpreted 100 mammographic cases. The algorithm was able to identify locations where the trainee will commit a false positive error with accuracy higher than an algorithm that selects such locations randomly. Specifically, our algorithm found false positive locations with 40% accuracy when only 1 location was selected for all cases for each trainee and 12% accuracy when 10 locations were selected. The accuracies for randomly identified locations were both 0% for these two scenarios. In this first study on the topic, we were able to build computer models that were able to find locations for which a trainee will make a false positive error in images that were not

  4. False-positive results with amylase testing of citrus fruits.

    PubMed

    Ricci, Ugo; Carboni, Ilaria; Torricelli, Francesca

    2014-09-01

    In a case of robbery in which the criminals passed through the garden adorned with calamondin trees (Citrus madurensis), the investigators found in the grass six calamondin fruits, some undamaged, while others apparently bitten. The fruits were collected and sent to the laboratory for DNA analysis to verify the presence of saliva and robbers' DNA profile. A specific immunochromatographic strip test for saliva confirmed the presence of human salivary α-amylase, but similar positive results were also observed for intact calamondin and other citrus fruits. Further analysis with a specific automated amylase test confirmed the absence of amylase activity. DNA quantification and typing using a specific forensic kit revealed no human DNA presence in any fruits. This case report demonstrates for the first time the occurrence of false positives when human saliva is sought on citrus fruits. © 2014 American Academy of Forensic Sciences.

  5. False-Positive Viability PCR Results: An Association with Microtubes.

    PubMed

    Agustí, Gemma; Fittipaldi, Mariana; Codony, Francesc

    2017-03-01

    Currently, one of the most challenged points to expand the use of viability PCR technique is achieving the complete exclusion of dead cells amplification signals, thus avoiding the overestimation of live cells population. Considering that, and based on the hypothesis that DNA may be retained by microtube walls, the impact of the microtube was addressed on signals from live and heat-killed cells. A double-dye reagent, PEMAX™, which comprises a mix of photo-reactive azide forms of phenanthridium, was used in this work. We found that if both the incubation and the photoactivation steps are carried out in different microtubes, the dead cell signal is greatly reduced than when those steps are done in the same tube. Therefore, the strategy depicted in this study presents a simple and efficient step in minimizing false-positive signal when employing viability PCR.

  6. False-positive tangible outcomes of functional analyses.

    PubMed

    Rooker, Griffin W; Iwata, Brian A; Harper, Jill M; Fahmie, Tara A; Camp, Erin M

    2011-01-01

    Functional analysis (FA) methodology is the most precise method for identifying variables that maintain problem behavior. Occasionally, however, results of an FA may be influenced by idiosyncratic sensitivity to aspects of the assessment conditions. For example, data from several studies suggest that inclusion of a tangible condition during an FA may be prone to a false-positive outcome, although the extent to which tangible reinforcement routinely produces such outcomes is unknown. We examined susceptibility to tangible reinforcement by determining whether a new response was acquired more readily when exposed to a tangible contingency relative to others commonly used in an FA (Study 1), and whether problem behavior known not to have a social function nevertheless emerged when exposed to tangible reinforcement (Study 2). Results indicated that inclusion of items in the tangible condition should be done with care and that selection should be based on those items typically found in the individual's environment.

  7. Decreasing the number of false positives in sequence classification.

    PubMed

    Machado-Lima, Ariane; Kashiwabara, André Yoshiaki; Durham, Alan Mitchell

    2010-12-22

    A large number of probabilistic models used in sequence analysis assign non-zero probability values to most input sequences. To decide when a given probability is sufficient the most common way is bayesian binary classification, where the probability of the model characterizing the sequence family of interest is compared to that of an alternative probability model. We can use as alternative model a null model. This is the scoring technique used by sequence analysis tools such as HMMER, SAM and INFERNAL. The most prevalent null models are position-independent residue distributions that include: the uniform distribution, genomic distribution, family-specific distribution and the target sequence distribution. This paper presents a study to evaluate the impact of the choice of a null model in the final result of classifications. In particular, we are interested in minimizing the number of false predictions in a classification. This is a crucial issue to reduce costs of biological validation. For all the tests, the target null model presented the lowest number of false positives, when using random sequences as a test. The study was performed in DNA sequences using GC content as the measure of content bias, but the results should be valid also for protein sequences. To broaden the application of the results, the study was performed using randomly generated sequences. Previous studies were performed on aminoacid sequences, using only one probabilistic model (HMM) and on a specific benchmark, and lack more general conclusions about the performance of null models. Finally, a benchmark test with P. falciparum confirmed these results. Of the evaluated models the best suited for classification are the uniform model and the target model. However, the use of the uniform model presents a GC bias that can cause more false positives for candidate sequences with extreme compositional bias, a characteristic not described in previous studies. In these cases the target model is more

  8. Consequences of treating false positive heparin-induced thrombocytopenia.

    PubMed

    Marler, Jacob; Unzaga, Jessica; Stelts, Sundae; Oliphant, Carrie S

    2015-11-01

    Identification of patients with heparin-induced thrombocytopenia is encumbered by false positive enzyme-linked immuno assay (ELISA) antibody results, therefore a serotonin release assay (SRA) is used for confirmation. Recently, several studies have demonstrated that increasing the optical density (OD) threshold (currently at 0.4) of the antibody test enhances the positive predictive value. The purpose of this study was to determine the frequency of patients who were ELISA antibody positive but SRA negative, and the costs and bleeding events associated with alternative anticoagulant treatment. We hypothesized that treating patients with a positive ELISA antibody OD value of <1.0 would result in increased cost and bleeding risk. This retrospective chart review was conducted on adult hospitalized patients from 2011 to 2013. Patients with positive ELISA antibodies (OD of 0.4-1.0) and an SRA result were included. Eighty-five patients were identified with positive antibodies (average OD of 0.66), 100 % of which were found to be SRA negative. A total of 59 patients (69 %) received alternative anticoagulants. The average duration of treatment was 3.1 days, and 4 patients (4.7 %) experienced a bleeding event. The cost of testing and laboratory monitoring was $36,346 and the cost of the alternative anticoagulants totaled $47,179. The total cost was $83,525, with an average total cost per patient of $982. This study adds to the body of literature suggesting treatment should only be initiated if the OD is one or greater. The high false positive rate caused increased cost and some bleeding events.

  9. False-positive technetium 99m depreotide scintigraphy resulting from round atelectasis.

    PubMed

    Thomas, Linda P; Balingit, Antonio G; Morison, David S; Gilman, Matthew D

    2003-04-01

    The authors report two cases of round atelectasis that showed increased accumulation of technetium (Tc) 99m depreotide on planar and single photon emission computed tomographic scintigraphy. It should be considered that round atelectasis is a potential nonmalignant cause for positive 99mTc depreotide scintigraphy.

  10. The case for computed tomographic angiography for initial management of lower gastrointestinal hemorrhage

    PubMed Central

    Cura, Marco

    2017-01-01

    Lower gastrointestinal hemorrhage remains a common disease, frequently presenting with acute life-threatening symptoms. Although prompt detection and treatment are imperative, it is difficult to diagnose lower gastrointestinal hemorrhage in an accurate and efficient manner. Most available modalities are time consuming. Computed tomographic angiography of the abdomen and pelvis, on the other hand, has the unique capability of rapidly detecting whether life-threatening hemorrhage is occurring and accurately localizing it, thus facilitating definitive treatment. We present a case in which computed tomographic angiography was invaluable in the detection and subsequent empirical transarterial embolization of a lower gastrointestinal hemorrhage and offer evidence as to why it should be a first-line tool in the management of these patients. PMID:28670085

  11. The case for computed tomographic angiography for initial management of lower gastrointestinal hemorrhage.

    PubMed

    Gupton, Theodore; Cura, Marco

    2017-07-01

    Lower gastrointestinal hemorrhage remains a common disease, frequently presenting with acute life-threatening symptoms. Although prompt detection and treatment are imperative, it is difficult to diagnose lower gastrointestinal hemorrhage in an accurate and efficient manner. Most available modalities are time consuming. Computed tomographic angiography of the abdomen and pelvis, on the other hand, has the unique capability of rapidly detecting whether life-threatening hemorrhage is occurring and accurately localizing it, thus facilitating definitive treatment. We present a case in which computed tomographic angiography was invaluable in the detection and subsequent empirical transarterial embolization of a lower gastrointestinal hemorrhage and offer evidence as to why it should be a first-line tool in the management of these patients.

  12. Invited review-Computed tomographic angiography (CTA) of the thoracic cardiovascular system in companion animals.

    PubMed

    Drees, Randi; François, Christopher J; Saunders, Jimmy H

    2014-01-01

    Computed tomographic angiography (CTA) of the thoracic cardiovascular system is offering new diagnostic opportunities in companion animal patients with the increasing availability of multidetector-row computed tomographic (MDCT) units in veterinary facilities. Optimal investigation of the systemic, pulmonary, and coronary circulation provides unique challenges due to the constant movement of the heart, the small size of several of the structures of interest, and the dependence of angiographic quality on various contrast bolus design and patient factors. Technical and practical aspects of thoracic cardiovascular CTA are reviewed in light of the currently available veterinary literature and future opportunities given utilizing MDCT in companion animal patients with suspected thoracic cardiovascular disease. © 2014 American College of Veterinary Radiology.

  13. Gouda frame redesigned specifically for computed tomographic compatibility.

    PubMed

    Gouda, K I; Freidberg, S R; Baker, R A; Larsen, C R; Silverman, M L

    1986-01-01

    The Gouda stereotactic frame has been redesigned for use with computed tomography. The patient is attached to the frame, is scanned, and is moved to the operating room for stereotactic biopsy. The Gouda frame permits accurate biopsy of otherwise inaccessible tumors of the brain.

  14. Spiral computed tomographic evaluation and endodontic management of a mandibular first molar with three distal canals.

    PubMed

    Mushtaq, Mubashir; Farooq, Riyaz; Rashid, Aamir; Robbani, Irfan

    2011-04-01

    The use of spiral computed tomography serves as a boon in endodontic diagnosis of complex anatomic variations. The present case demonstrates the spiral tomographic evaluation and endodontic management of a mandibular first molar with 5 canals (2 mesial and 3 distal canals), which is a very rare anatomic variant. Such anatomic variations should be taken into account in day to day endodontic practice to ensure a high degree of clinical success.

  15. Optimal Computed Tomographic Perfusion Scan Duration for Assessment of Acute Stroke Lesion Volumes.

    PubMed

    Kasasbeh, Aimen S; Christensen, Søren; Straka, Matus; Mishra, Nishant; Mlynash, Michael; Bammer, Roland; Albers, Gregory W; Lansberg, Maarten G

    2016-12-01

    The minimal scan duration needed to obtain reliable lesion volumes with computed tomographic perfusion (CTP) has not been well established in the literature. We retrospectively assessed the impact of gradual truncation of the scan duration on acute ischemic lesion volume measurements. For each scan, we identified its optimal scan time, defined as the shortest scan duration that yields measurements of the ischemic lesion volumes similar to those obtained with longer scanning, and the relative height of the fitted venous output function at its optimal scan time. We analyzed 70 computed tomographic perfusion scans of acute stroke patients. An optimal scan time could not be determined in 11 scans (16%). For the other 59 scans, the median optimal scan time was 32.7 seconds (90th percentile 52.6 seconds; 100th percentile 68.9 seconds), and the median relative height of the fitted venous output function at the optimal scan times was 0.39 (90th percentile 0.02; 100th percentile 0.00). On the basis of a linear model, the optimal scan time was T0 plus 1.6 times the width of the venous output function (P<0.001; R(2)=0.49). This study shows how the optimal duration of a computed tomographic perfusion scan relates to the arrival time and width of the contrast bolus. This knowledge can be used to optimize computed tomographic perfusion scan protocols and to determine whether a scan is of sufficient duration. Provided a baseline (T0) of 10 seconds, a total scan duration of 60 to 70 seconds, which includes the entire downslope of the venous output function in most patients, is recommended. © 2016 American Heart Association, Inc.

  16. Development of an electrical impedance computed tomographic two-phase flows analyzer. Annual technical report for program renewal

    SciTech Connect

    Jones, O.C.

    1993-05-01

    This progress report details the theoretical development, numerical results, experimental design (mechanical), experimental design (electronic), and experimental results for the research program for the development of an electrical impedance computed tomographic two-phase flow analyzer.

  17. Computed tomographic beam-hardening artefacts: mathematical characterization and analysis.

    PubMed

    Park, Hyoung Suk; Chung, Yong Eun; Seo, Jin Keun

    2015-06-13

    This paper presents a mathematical characterization and analysis of beam-hardening artefacts in X-ray computed tomography (CT). In the field of dental and medical radiography, metal artefact reduction in CT is becoming increasingly important as artificial prostheses and metallic implants become more widespread in ageing populations. Metal artefacts are mainly caused by the beam-hardening of polychromatic X-ray photon beams, which causes mismatch between the actual sinogram data and the data model being the Radon transform of the unknown attenuation distribution in the CT reconstruction algorithm. We investigate the beam-hardening factor through a mathematical analysis of the discrepancy between the data and the Radon transform of the attenuation distribution at a fixed energy level. Separation of cupping artefacts from beam-hardening artefacts allows causes and effects of streaking artefacts to be analysed. Various computer simulations and experiments are performed to support our mathematical analysis.

  18. Computed tomographic beam-hardening artefacts: mathematical characterization and analysis

    PubMed Central

    Park, Hyoung Suk; Chung, Yong Eun; Seo, Jin Keun

    2015-01-01

    This paper presents a mathematical characterization and analysis of beam-hardening artefacts in X-ray computed tomography (CT). In the field of dental and medical radiography, metal artefact reduction in CT is becoming increasingly important as artificial prostheses and metallic implants become more widespread in ageing populations. Metal artefacts are mainly caused by the beam-hardening of polychromatic X-ray photon beams, which causes mismatch between the actual sinogram data and the data model being the Radon transform of the unknown attenuation distribution in the CT reconstruction algorithm. We investigate the beam-hardening factor through a mathematical analysis of the discrepancy between the data and the Radon transform of the attenuation distribution at a fixed energy level. Separation of cupping artefacts from beam-hardening artefacts allows causes and effects of streaking artefacts to be analysed. Various computer simulations and experiments are performed to support our mathematical analysis. PMID:25939628

  19. Computed tomographic identification of calcified optic nerve drusen

    SciTech Connect

    Ramirez, H.; Blatt, E.S.; Hibri, N.S.

    1983-07-01

    Four cases of optic disk drusen were accurately diagnosed with orbital computed tomography (CT). The radiologist should be aware of the characteristic CT finding of discrete calcification within an otherwise normal optic disk. This benign process is easily differentiated from lesions such as calcific neoplastic processes of the posterior globe. CT identification of optic disk drusen is essential in the evaluation of visual field defects, migraine-like headaches, and pseudopapilledema.

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

    PubMed

    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.

  1. V/Q SPECT and computed tomographic pulmonary angiography.

    PubMed

    Leblanc, Michel; Paul, Narinder

    2010-11-01

    Planar ventilation and perfusion (V/Q) scintigraphy has been largely displaced by computed tomography pulmonary angiography (CTPA) in recent years for the diagnosis of pulmonary embolism (PE). This change can be attributed to multiple studies that demonstrate CTPA has a reasonable sensitivity and good prognostic value in negative cases, associated with the ability to deliver few indeterminate results and provide an alternate diagnosis in a significant number of patients. However, the technique has significant limitations. The Prospective Investigation of Pulmonary Embolism Diagnosis II (PIOPED II) study has shown a sensitivity of 83%, which is not optimal. However, CT technology has greatly progressed since this time, and therefore it is likely that this number has improved. The PIOPED II study has also shown that there may be a problem in positive or negative predictive value when the imaging results are discordant with the clinical probability. Additional concerns include allergies, contrast nephropathy associated with the use of intravenous contrast in patients with impaired creatinine clearance, suboptimal results in pregnant women, and high radiation exposure. In recent years, V/Q single-photon emission computed tomography has emerged as a mature technique for the diagnosis of PE and has been shown to be clearly superior to planar V/Q. The technique has excellent sensitivity for PE and is not associated with most of the limitations of CTPA, although it has its own set of limitations in patients with very severe chronic obstructive pulmonary disease or with a severely abnormal chest x-ray. V/Q single-photon emission computed tomography can be used as the initial modality for PE diagnosis in a wide variety of situations although CTPA remains invaluable in specific scenarios. Copyright © 2010 Elsevier Inc. All rights reserved.

  2. Computed tomographic images of discospondylitis in a calf

    PubMed Central

    TSUKA, Takeshi; YAMAMOTO, Naoki; SANESHIGE, Makoto; MORITA, Takehito; SUNDEN, Yuji; MURAHATA, Yusuke; AZUMA, Kazuo; OSAKI, Tomohiro; ITO, Norihito; OKAMOTO, Yoshiharu; IMAGAWA, Tomohiro

    2015-01-01

    A 2-month-old male Japanese Black calf was presented with a 30-day history of progressive ataxia. Antemortem examination using computed tomography (CT) revealed narrowing of the disc spaces due to destruction of intervertebral structures between the first and second thoracic vertebrae and between the second and third thoracic vertebrae. Osteolysis was evident as irregular hypoattenuating lesions within the opposing end plates of the first, second and third thoracic vertebrae. Pseudomonas aeruginosa was detected as the causative bacteria, and discospondylitis was diagnosed. To the best of our knowledge, this is the first bovine case report describing the application of CT for the diagnosis of discospondylitis. PMID:26256229

  3. Computed tomographic diagnosis of nongastrointestinal foreign bodies in dogs.

    PubMed

    Jones, Jeryl C; Ober, Christopher P

    2007-01-01

    Clinical data and computed tomography (CT) studies were reviewed for 13 dogs with confirmed nongastrointestinal foreign bodies. Locations of foreign bodies were the nasal cavity, thoracic wall, retropharyngeal region, and cerebellum. Types of foreign bodies included small plant components, blades of grass, wooden sticks, cloth fibers, and a needle. Foreign bodies in five dogs were not identified on CT, and secondary reactions resembled neoplastic or fungal disease. In eight dogs, foreign bodies were recognized by their shape and/or internal architecture. In two dogs, three-dimensional reformatting helped demonstrate foreign bodies in relation to palpable bony landmarks.

  4. Recent Advances in Computed Tomographic Technology: Cardiopulmonary Imaging Applications.

    PubMed

    Tabari, Azadeh; Lo Gullo, Roberto; Murugan, Venkatesh; Otrakji, Alexi; Digumarthy, Subba; Kalra, Mannudeep

    2017-03-01

    Cardiothoracic diseases result in substantial morbidity and mortality. Chest computed tomography (CT) has been an imaging modality of choice for assessing a host of chest diseases, and technologic advances have enabled the emergence of coronary CT angiography as a robust noninvasive test for cardiac imaging. Technologic developments in CT have also enabled the application of dual-energy CT scanning for assessing pulmonary vascular and neoplastic processes. Concerns over increasing radiation dose from CT scanning are being addressed with introduction of more dose-efficient wide-area detector arrays and iterative reconstruction techniques. This review article discusses the technologic innovations in CT and their effect on cardiothoracic applications.

  5. Pediatric ophthalmic computed tomographic scanning and associated cancer risk.

    PubMed

    Mills, David M; Tsai, Salina; Meyer, Dale R; Belden, Clifford

    2006-12-01

    To review pediatric neuroimaging studies of the head and orbit and the radiation-induced cancer risk associated with computed tomography in light of recent attention to pediatric radioimaging by the US Food and Drug Administration, the National Cancer Institute, pediatricians, and radiologists. Perspective. Literature review. Institutional. Pediatric ophthalmic patients requiring neuroimaging studies. INTERVENTION/PROCEDURE: Review of the current literature. After review of the current literature and discussion of the related issues, recommendations are made for pediatric neuroimaging studies of the head and orbit. Computed tomography (CT) of the head and orbit may be performed in children with the appropriate indications as long as the radiation exposure is minimized. Information obtained from CT scans of the head and orbit may determine or affect management in the pediatric ophthalmic population. Because of the concern of cancer induced by radiation exposure in children, neuroimaging modalities without radiation exposure, such as magnetic resonance imaging or ultrasound, may be considered. However, when CT is indicated, it is reasonable and acceptable to perform CT of the head and orbit while minimizing the radiation exposure, thereby adhering to the "ALARA" (as low as reasonably achievable) policy recommended by the US Food and Drug Administration. Further studies of the actual radiation dose delivered during pediatric CT of the head and orbit and the true incidence of radiation-induced cancers after scans are warranted.

  6. Hybrid computing: CPU+GPU co-processing and its application to tomographic reconstruction.

    PubMed

    Agulleiro, J I; Vázquez, F; Garzón, E M; Fernández, J J

    2012-04-01

    Modern computers are equipped with powerful computing engines like multicore processors and GPUs. The 3DEM community has rapidly adapted to this scenario and many software packages now make use of high performance computing techniques to exploit these devices. However, the implementations thus far are purely focused on either GPUs or CPUs. This work presents a hybrid approach that collaboratively combines the GPUs and CPUs available in a computer and applies it to the problem of tomographic reconstruction. Proper orchestration of workload in such a heterogeneous system is an issue. Here we use an on-demand strategy whereby the computing devices request a new piece of work to do when idle. Our hybrid approach thus takes advantage of the whole computing power available in modern computers and further reduces the processing time. This CPU+GPU co-processing can be readily extended to other image processing tasks in 3DEM. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Computed tomographic analysis of calvarial hyperostosis in captive lions.

    PubMed

    Gross-Tsubery, Ruth; Chai, Orit; Shilo, Yael; Miara, Limor; Horowitz, Igal H; Shmueli, Ayelet; Aizenberg, Itzhak; Hoffman, Chen; Reifen, Ram; Shamir, Merav H

    2010-01-01

    Osseous malformations in the skull and cervical vertebrae of lions in captivity are believed to be caused by hypovitaminosis A. These often lead to severe neurologic abnormalities and may result in death. We describe the characterization of these abnormalities based on computed tomography (CT). CT images of two affected and three healthy lions were compared with define the normal anatomy of the skull and cervical vertebrae and provide information regarding the aforementioned osseous malformations. Because bone structure is influenced by various factors other than the aforementioned disease, all values were divided by the skull width that was not affected. The calculated ratios were compared and the most pronounced abnormalities in the affected lions were, narrowing of the foramen magnum, thickening of the tentorium osseus cerebelli and thickening of the dorsal arch of the atlas. CT is useful for detection of the calvarial abnormalities in lions and may be useful in further defining this syndrome.

  8. Computed tomographic diagnosis of intraventricular hemorrhage: etiology and prognosis

    SciTech Connect

    Graeb, D.A.; Robertson, W.D.; Lapointe, J.S.; Nugent, R.A.; Harrison, P.B.

    1982-04-01

    Sixty-eight patients with intraventricular hemorrhage (IVH) diagnosed by computed tomography (CT) were reviewed retrospectively to determine the etiology and prognosis, relationship to delayed hydrocephalus, and effect on neurological outcome. The most common causes were a ruptured aneurysm, trauma, and hypertensive hemorrhage. Ruptured aneurysms of the anterior communicating artery can often be predicted from the nonenhanced CT scan. The total mortality rate was 50%; however, 21% of patients returned to normal or had only mild disability. Patients in whom no cause was identified had a better prognosis. Delayed hydrocephalus was related to the effects of subarachnoid hemorrahage rather than obstruction of the ventricular system by blood. IVH per se is seldon a major factor in the neurological outcome.

  9. Temporomandibular joints: high-resolution computed tomographic evaluation

    SciTech Connect

    Thompson, J.R.; Christiansen, E.; Hasso, A.N.; Hinshaw, D.B. Jr.

    1984-01-01

    High-resolution computed tomography of the temporomandibular joint (TMJ) was performed in 43 patients. Exquisite detail of the face, skull base, and TMJs was obtained with CT using soft tissue and bone algorithms, narrow collimation, and multiplanar images. In 10 patients clinically suspected of joint derangement, CT results were in close agreement with surgical findings and arthrography in 13/15 joints. CT showed indirect signs of disc dislocation, and the dislocated disc itself in 81% of affected joints. In two patients, arthrography with CT proved to be more helpful than conventional arthrography alone. CT without intra-articular contrast material provided information not appreciated on conventional radiogaphs in 28 patients (65%) and was particularly helpful in evaluating patients with disc pathosis and trauma. Early experience with CT of the TMJ shows that it is an excellent method of evaluation at acceptable radiation exposure levels that adds essential information not seen on standard radiographs.

  10. Maturation of normal primate white matter: computed tomographic correlation

    SciTech Connect

    Quencer, R.M.

    1982-09-01

    Five infant baboons were examined with computed tomography (CT) during the first year of their lives to determine the rate and degree of normal white matter maturation in frontal, occipital, and parietal areas. The increase in CT numbers with age was correlated with gross and histologic specimens. Two phases of maturation were identified: a rapid phase (first 8-12 weeks) and a gradual phase (after 12 weeks). Frontal white matter was the most immature in the immediate postnatal period but it became equal in attenuation to the other regions by 4 weeks of age. Knowledge of white matter maturation rates may be particularly useful in cases of neonatal hypoxia/ischemia where zones of periventricular hypodensity are identified. The failure of such regions to follow a normal rate of maturation may indicate damage to the white matter and have significant prognostic implications.

  11. Recurrent largngeal nerve paralysis: a laryngographic and computed tomographic study

    SciTech Connect

    Agha, F.P.

    1983-07-01

    Vocal cord paralysis is a relatively common entity, usually resulting from a pathologic process of the vagus nerve or its recurrent larynegeal branch. It is rarely caused by intralargngeal lesions. Four teen patients with recurrent laryngeal nerve paralysis (RLNP) were evaluated by laryngography, computed tomography (CT), or both. In the evaluation of the paramedian cord, CT was limited in its ability to differentiate between tumor or RLNP as the cause of the fixed cord, but it yielded more information than laryngography on the structural abnormalities of the larynx and pre-epiglottic and paralaryngeal spaces. Laryngography revealed distinct features of RLNP and is the procedure of choice for evaluation of functional abnormalities of the larynx until further experience with faster CT scanners and dynamic scanning of the larynx is gained.

  12. Computer-aided teniae coli detection using height maps from computed tomographic colonography images

    NASA Astrophysics Data System (ADS)

    Wei, Zhuoshi; Yao, Jianhua; Wang, Shijun; Summers, Ronald M.

    2011-03-01

    Computed tomographic colonography (CTC) is a minimally invasive technique for colonic polyps and cancer screening. Teniae coli are three bands of longitudinal smooth muscle on the colon surface. They are parallel, equally distributed on the colon wall, and form a triple helix structure from the appendix to the sigmoid colon. Because of their characteristics, teniae coli are important anatomical meaningful landmarks on human colon. This paper proposes a novel method for teniae coli detection on CT colonography. We first unfold the three-dimensional (3D) colon using a reversible projection technique and compute the two-dimensional (2D) height map of the unfolded colon. The height map records the elevation of colon surface relative to the unfolding plane, where haustral folds corresponding to high elevation points and teniae to low elevation points. The teniae coli are detected on the height map and then projected back to the 3D colon. Since teniae are located where the haustral folds meet, we break down the problem by first detecting haustral folds. We apply 2D Gabor filter banks to extract fold features. The maximum response of the filter banks is then selected as the feature image. The fold centers are then identified based on piecewise thresholding on the feature image. Connecting the fold centers yields a path of the folds. Teniae coli are finally extracted as lines running between the fold paths. Experiments were carried out on 7 cases. The proposed method yielded a promising result with an average normalized RMSE of 5.66% and standard deviation of 4.79% of the circumference of the colon.

  13. Prediction of Clinical Outcome After Acute Ischemic Stroke: The Value of Repeated Noncontrast Computed Tomography, Computed Tomographic Angiography, and Computed Tomographic Perfusion.

    PubMed

    Dankbaar, Jan W; Horsch, Alexander D; van den Hoven, Andor F; Kappelle, L Jaap; van der Schaaf, Irene C; van Seeters, Tom; Velthuis, Birgitta K

    2017-09-01

    Early prediction of outcome in acute ischemic stroke is important for clinical management. This study aimed to compare the relationship between early follow-up multimodality computed tomographic (CT) imaging and clinical outcome at 90 days in a large multicenter stroke study. From the DUST study (Dutch Acute Stroke Study), patients were selected with (1) anterior circulation occlusion on CT angiography (CTA) and ischemic deficit on CT perfusion (CTP) on admission, and (2) day 3 follow-up noncontrast CT, CTP, and CTA. Follow-up infarct volume on noncontrast CT, poor recanalization on CTA, and poor reperfusion on CTP (mean transit time index ≤75%) were related to unfavorable outcome after 90 days defined as modified Rankin Scale 3 to 6. Four multivariable models were constructed: (1) only baseline variables (model 1), (2) model 1 with addition of infarct volume, (3) model 1 with addition of recanalization, and (4) model 1 with addition of reperfusion. Area under the curves of the receiver operating characteristic curves of the models were compared using the DeLong test. A total of 242 patients were included. Poor recanalization was found in 21%, poor reperfusion in 37%, and unfavorable outcome in 44%. The area under the curve of the receiver operating characteristic curve without follow-up imaging was 0.81, with follow-up noncontrast CT 0.85 (P=0.02), CTA 0.86 (P=0.01), and CTP 0.86 (P=0.01). All 3 follow-up imaging modalities improved outcome prediction compared with no imaging. There was no difference between the imaging models. Follow-up imaging after 3 days improves outcome prediction compared with prediction based on baseline variables alone. CTA recanalization and CTP reperfusion do not outperform noncontrast CT at this time point. URL: http://www.clinicaltrials.gov. Unique identifier: NCT00880113. © 2017 American Heart Association, Inc.

  14. Distinguishing true from false positives in genomic studies: p values.

    PubMed

    Broer, Linda; Lill, Christina M; Schuur, Maaike; Amin, Najaf; Roehr, Johannes T; Bertram, Lars; Ioannidis, John P A; van Duijn, Cornelia M

    2013-02-01

    Distinguishing true from false positive findings is a major challenge in human genetic epidemiology. Several strategies have been devised to facilitate this, including the positive predictive value (PPV) and a set of epidemiological criteria, known as the "Venice" criteria. The PPV measures the probability of a true association, given a statistically significant finding, while the Venice criteria grade the credibility based on the amount of evidence, consistency of replication and protection from bias. A vast majority of journals use significance thresholds to identify the true positive findings. We studied the effect of p value thresholds on the PPV and used the PPV and Venice criteria to define usable thresholds of statistical significance. Theoretical and empirical analyses of data published on AlzGene show that at a nominal p value threshold of 0.05 most "positive" findings will turn out to be false if the prior probability of association is below 0.10 even if the statistical power of the study is higher than 0.80. However, in underpowered studies (0.25) with a low prior probability of 1 × 10(-3), a p value of 1 × 10(-5) yields a high PPV (>96 %). Here we have shown that the p value threshold of 1 × 10(-5) gives a very strong evidence of association in almost all studies. However, in the case of a very high prior probability of association (0.50) a p value threshold of 0.05 may be sufficient, while for studies with very low prior probability of association (1 × 10(-4); genome-wide association studies for instance) 1 × 10(-7) may serve as a useful threshold to declare significance.

  15. Understanding the mechanisms creating false positive lumpectomy margins.

    PubMed

    Dooley, William C; Parker, Jeanene

    2005-10-01

    All breast surgeons deal with the frustration of initial pathologic close or positive margins that have no residual cancer upon re-excision. To understand the mechanisms that create false positive margins, specimen handling was standardized in a single surgeon's practice and margin issues were tracked. Prospectively over a 3.5-year period, needle-localized lumpectomies for the management of early-stage breast cancer were standardized in all aspects of specimen handling, including surgeon inking and specimen compression for specimen radiography for quality assurance. The current study reviews 220 such cases where the original lumpectomy included a small piece of overlying skin from over the target lesion. All specimen radiography was performed with compression at the skin to deep level to bias the "pancaking" effect of pushing tumor to specimen surface to the deep margin. Of the 220 therapeutic lumpectomies performed for clinical stage 0-2 breast cancer in this fashion, 175 (79.5%) had negative margins by a distance of 10 mm or more. Margins less than 10 mm were classified as close and were present in 20 (9.1%) of cases. These were heavily biased toward margins closer than 2 mm. Positive initial margins accounted for 25 (11.4%) of cases. Of the 45 close or positive margin cases, 12 involved the deep margin only, and on re-excision none was found to have residual tumor. When other single margins were involved, re-excision found tumor in 5 of 14 cases (35.7%). When multiple margins were close or positive, 9 of 19 cases (47.3%) were found to have residual tumor at re-excision. Specimen compression increases the incidence of false margin positivity. The best predictors of true margin positivity are multiple close or positive margins or margin positivity in a direction not associated with specimen ex vivo compression.

  16. [Recurrence paralysis: computed tomographic analysis of intrathoracic findings].

    PubMed

    Delorme, S; Knopp, M V; Kauczor, H U; Zuna, I; Trost, U; Haberkorn, U; van Kaick, G

    1992-09-01

    The long and singular course of the inferior (recurrent) laryngeal nerve makes it very vulnerable to infiltration by tumors of various locations. In particular, mediastinal and pulmonary lesions must be considered in the case of left vocal chord palsy. Recurrent nerve paralysis caused by a tumor indicates advanced disease. We retrospectively reviewed the computed tomography (CT) findings in 29 patients with bronchogenic carcinoma or mediastinal tumors and recurrent nerve paralysis with respect to the site, size and extent of the tumor and the lymph node status. The review revealed a marked predominance of left upper lobe tumors with extensive lymph node metastases to the anterior mediastinum and the aortopulmonary window. The extent of mediastinal involvement exceeded the average involvement in a control group of 30 randomly selected patients with bronchogenic carcinoma at the time of presentation. In all patients CT demonstrated tumor tissue which could have caused the paralysis at one or more sites along the anatomical course of the recurrent nerve. In most cases the tumor was located at the aortic arch. The left paratracheal region, right paratracheal region and right pulmonary apex were affected in one case each. We conclude that in patients with cancer, CT is a suitable method for localizing a recurrent nerve lesion.

  17. 64-MULTIDETECTOR COMPUTED TOMOGRAPHIC ANGIOGRAPHY OF THE CANINE CORONARY ARTERIES

    PubMed Central

    Drees, Randi; Frydrychowicz, Alex; Reeder, Scott B.; Pinkerton, Marie E.; Johnson, Rebecca

    2012-01-01

    Canine coronary artery angiography (CTA) was performed in four anesthetized healthy dogs using 64-multi-detector computed tomography. Esmolol, a β-1 adrenergic receptor antagonist, and sodium nitroprusside, an arteriolar and venous dilator, were administered to enhance visualization of the coronary arteries by reducing heart rate and creating vasodilation. The left main coronary artery with its three main branches and the right coronary artery were visualized and subdivided in 13 segments for evaluation. Optimal reconstruction interval, expressed as percentage of the R-to-R interval, was determined at 5% in 2.9%, 35% in 1%, 75% in 21.2%, 85% in 43.3%, and 95% in 31.7% of the segments. Overall image quality was good in 41.3% of the segments and excellent in 14.4%. There was blur in 98.1%, motion in 17.3%, and stair step in 6.7% of the evaluated segments, but these artifacts did not interfere with anatomic depiction of the arteries. Cross-sectional anatomy of the coronary arteries as evaluated from the coronary CTA agreed well with gross anatomic evaluation and published information. The use of esmolol did not lead to the target heart rate of 60–65 beats/min. Nitroprusside had no significant effect on visualized length or diameter of the coronary artery branches. Coronary CTA is useful for the anatomic depiction of coronary artery branches in the dog. PMID:21521398

  18. Computed Tomographic Evaluation of Presumptively Normal Canine Sternal Lymph Nodes.

    PubMed

    Iwasaki, Ryota; Mori, Takashi; Ito, Yusuke; Kawabe, Mifumi; Murakmi, Mami; Maruo, Kohji

    The sternal lymph nodes receive drainage from a wide variety of structures in the thoraco-abdominal region. Evaluation of these lymph nodes is essential, especially in cancer patients. Computed tomography (CT) can detect sternal lymph nodes more accurately than radiography or ultrasonography, and the criteria of the sternal lymphadenopathy are unknown. The purpose of this retrospective study was to describe the CT characteristics of the sternal lymph nodes in dogs considered unlikely to have lymphadenopathy. The ratio of the short axis dimension of the sternal lymph nodes to the thickness of the second sternebra was also investigated. At least one sternal lymph node was identified in each of the 152 dogs included in the study. The mean long axis and short axis dimensions were 0.700 cm and 0.368 cm, respectively. The mean ratio of the sternal lymph nodes to the second sternebrae was 0.457, and the 95% prediction interval ranged from 0.317 to 0.596 (almost a fixed value independent of body weight). These findings will be useful when evaluating sternal lymphadenopathy using CT.

  19. The computed tomographic appearance of equine temporohyoid osteoarthropathy.

    PubMed

    Hilton, Hugo; Puchalski, Sarah M; Aleman, Monica

    2009-01-01

    Equine temporohyoid osteoarthropathy is characterized by progressive osseous proliferation of the temporohyoid articulation and surrounding structures. The diagnosis has generally been made using radiography and endoscopy of the guttural pouch. Recently, computed tomography (CT) has been used in the diagnosis of temporohyoid osteoarthropathy. This study was performed to determine the CT imaging characteristics of temporohyoid osteoarthropathy and to compare these to radiographic and endoscopic findings. CT scans from 16 horses with a final diagnosis of temporohyoid osteoarthropathy were reviewed. Five horses that had undergone CT scan for reasons other than temporohyoid osteoarthropathy were included as controls. Qualitative and quantitative data were used to describe the magnitude of the CT findings. Osseous proliferation of the stylohyoid bone and temporohyoid articulation was found to be a consistent feature of temporohyoid osteoarthropathy. Thickening of the ceratohyoid bone and proliferation of its articulation with the stylohyoid bone was frequently identified and this finding may have surgical implications. Horses with neurologic deficits had increased stylohyoid width that was significantly different than the subclinically affected side. CT evaluation also allowed the identification of subclinical bilateral disease in horses thought to be unilaterally affected based on clinical examination.

  20. Vertebrobasilar system computed tomographic angiography in central vertigo.

    PubMed

    Paşaoğlu, Lale

    2017-03-01

    The incidence of vertigo in the population is 20% to 30% and one-fourth of the cases are related to central causes. The aim of this study was to evaluate computed tomography angiography (CTA) findings of the vertebrobasilar system in central vertigo without stroke.CTA and magnetic resonance images of patients with vertigo were retrospectively evaluated. One hundred twenty-nine patients suspected of having central vertigo according to history, physical examination, and otological and neurological tests without signs of infarction on diffusion-weighted magnetic resonance imaging were included in the study. The control group included 120 patients with similar vascular disease risk factors but without vertigo. Vertebral and basilar artery diameters, hypoplasias, exit-site variations of vertebral artery, vertebrobasilar tortuosity, and stenosis of ≥50% detected on CTA were recorded for all patients. Independent-samples t test was used in variables with normal distribution, and Mann-Whitney U test in non-normal distribution. The difference of categorical variable distribution according to groups was analyzed with χ and/or Fisher exact test.Vertebral artery hypoplasia and ≥50% stenosis were seen more often in the vertigo group (P = 0.000, <0.001). Overall 78 (60.5%) vertigo patients had ≥50% stenosis, 54 (69.2%) had stenosis at V1 segment, 9 (11.5%) at V2 segment, 2 (2.5%) at V3 segment, and 13 (16.6%) at V4 segment. Both vertigo and control groups had similar basilar artery hypoplasia and ≥50% stenosis rates (P = 0.800, >0.05).CTA may be helpful to clarify the association between abnormal CTA findings of vertebral arteries and central vertigo.This article reveals the opportunity to diagnose posterior circulation abnormalities causing central vertigo with a feasible method such as CTA.

  1. Vertebrobasilar system computed tomographic angiography in central vertigo

    PubMed Central

    Paşaoğlu, Lale

    2017-01-01

    Abstract The incidence of vertigo in the population is 20% to 30% and one-fourth of the cases are related to central causes. The aim of this study was to evaluate computed tomography angiography (CTA) findings of the vertebrobasilar system in central vertigo without stroke. CTA and magnetic resonance images of patients with vertigo were retrospectively evaluated. One hundred twenty-nine patients suspected of having central vertigo according to history, physical examination, and otological and neurological tests without signs of infarction on diffusion-weighted magnetic resonance imaging were included in the study. The control group included 120 patients with similar vascular disease risk factors but without vertigo. Vertebral and basilar artery diameters, hypoplasias, exit-site variations of vertebral artery, vertebrobasilar tortuosity, and stenosis of ≥50% detected on CTA were recorded for all patients. Independent-samples t test was used in variables with normal distribution, and Mann–Whitney U test in non-normal distribution. The difference of categorical variable distribution according to groups was analyzed with χ2 and/or Fisher exact test. Vertebral artery hypoplasia and ≥50% stenosis were seen more often in the vertigo group (P = 0.000, <0.001). Overall 78 (60.5%) vertigo patients had ≥50% stenosis, 54 (69.2%) had stenosis at V1 segment, 9 (11.5%) at V2 segment, 2 (2.5%) at V3 segment, and 13 (16.6%) at V4 segment. Both vertigo and control groups had similar basilar artery hypoplasia and ≥50% stenosis rates (P = 0.800, >0.05). CTA may be helpful to clarify the association between abnormal CTA findings of vertebral arteries and central vertigo. This article reveals the opportunity to diagnose posterior circulation abnormalities causing central vertigo with a feasible method such as CTA. PMID:28328808

  2. Computed tomographic evaluation of head diseases in the horse: 15 cases.

    PubMed

    Tietje, S; Becker, M; Böckenhoff, G

    1996-03-01

    The rapid development of software and technology now allows a large amount of diagnostic information to be obtained from a computed tomographic examination. This imaging technique can also be usefully applied to the horse, given appropriate premises and a custom built table for accurate positioning. Computed tomography of the skull has considerable advantages over other techniques, as structures are viewed without superimposition. Fifteen cases are used to demonstrate how through high image quality (precise detail, reduction in artefacts) and objective measurement of density, various pathological changes can be analysed and exact diagnoses achieved. In particular, short measurement and examination times allow preoperative imaging under general anaesthesia giving significant information to assist subsequent surgery.

  3. Facial nerve between the stylomastoid foramen and the parotid: computed tomographic imaging

    SciTech Connect

    Curtin, H.D.; Wolfe, P.; Snyderman, N.

    1983-10-01

    A small segment of the facial nerve between its exit from the stylomastoid foramen and its entrance into the parotid is surrounded by fat and, therefore, can be imaged well using modern computed tomography. A small dot can be seen surrounded by fat just beneath the stylomastoid foramen on computed tomographic scan. To verify that this indeed represented the facial nerve, tissue sections and an injection into the mastoid segment of the intratemporal facial nerve were performed. The anatomic correlation and clinical material demonstrating involvement of the facial nerve in this region are presented.

  4. Ossification in the caudal attachments of the ligamentum flavum: an anatomic and computed tomographic study

    SciTech Connect

    Williams, D.M.; Gabrielson, T.O.; Latack, J.T.

    1982-12-01

    A review of anatomic specimens and routine computed tomographic (CT) scans of the chest and abdomen demonstrated that ossification in the caudal attachments of the ligamentum flavum is a common anatomic finding, but a much less common CT finding. Its characteristic location should help prevent confusion with other entities. The present study was prompted by a case of thoracic spine trauma, reported here, in which areas of bone density in the spinal canal simulated fracture fragments. The true nature of these bony projections, namely ossification in the ligamentum flavum, was established by computer reconstruction of axial CT images.

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

    SciTech Connect

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

    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

  6. [Computed tomographic anatomy of the salivary glands in the cat].

    PubMed

    Fromme, V; Köhler, C; Piesnack, S; Oechtering, G; Ludewig, E

    2016-01-01

    The aim of the study was to define anatomical characteristics of the feline salivary glands in cross-sectional images obtained by unenhanced computed tomography (CT) and to describe landmarks for a reliable identification. Heads of adult normocephalic cats without indications of cephalic disease were examined. Cats were included in the prospective part of the study when examined no later than 1 hour post mortem (n = 16). In the retrospective part of the study, previous CT-studies were evaluated (n = 25). The results of both groups were evaluated separately. Initially, the possibility of identifying and delineating the salivary glands from the surrounding tissue was assessed. Anatomical structures of the head were then defined as landmarks. Dimensions and density (Hounsfield units, HU) of the salivary glands were determined based on transversal and reconstructed sagittal images. In total, 94.3% of the parotid glands, 90.7% of the mandibular glands and 96.8% of the zygomatic glands could be delineated. The remaining salivary glands could not be identified. Anatomical landmarks, including the external ear canal, the musculus (M.) masseter, the M. pterygoideus medialis and the bulbus oculi facilitated the identification. Comparing the size of the salivary glands of both groups revealed differences (measured lateromedially and rostrocaudally) in size of ≤   2 mm. The definable salivary glands varied significantly in their density. The mean density of the glandula (Gl.) parotis was 65 HU, of the Gl. mandibularis 62 HU and of the Gl. zygomatica 57 HU. The comparisons of densities of both sides of the glands did not show statistically significant differences. The large salivary glands (Gl. parotis and Gl. mandibularis) and the Gl. zygomatica of the cat can be reliably identified in CT-images. CT landmarks and data regarding the size and density of each gland could be gathered. The remaining minor salivary glands could not be delineated accurately. The difference in

  7. Quantification of Vasa Vasorum Density in Multi-Slice Computed Tomographic Coronary Angiograms: Role of Computed Tomographic Image Voxel Size

    SciTech Connect

    Moritz, R.; Eaker, D; Langheinrich, A; Jorgensen, S; Bohle, R; Ritman, E

    2010-01-01

    This study is motivated by the possibility of using computed tomography (CT) to detect early coronary atherosclerosis by the increased CT values within the arterial wall resulting from vasa vasorum proliferation. Coronary arteries (n = 5) with early atherosclerotic changes were injected with Microfil and scanned (micro-CT). Noise was added to the CT projection data sets (to represent the radiation exposure of current clinical CT scanners) and then reconstructed to generate 3-dimensional images at different voxel sizes. Higher CT values were detected because of contrast agent in vasa vasorum if voxel size was less than (150 {micro}m){sup 3}. Contrast in the main lumen increased the CT values dramatically at voxels greater than (100 {micro}m){sup 3}, whereas CT values of the same specimen without contrast in the main lumen remained constant. Voxel sizes less than (200 {micro}m){sup 3} are needed to quantitate arterial wall opacification due to vasa vasorum proliferation.

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

    PubMed

    Mahdavi, Mahmoud A; Lin, Yen-Han

    2007-07-23

    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. 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. Gene Ontology annotations along with the deduced knowledge rules could be implemented to partially remove false predicted PPI pairs. Removal of false positives

  9. Experimental Actinobacillus pleuropneumoniae challenge in swine: comparison of computed tomographic and radiographic findings during disease.

    PubMed

    Brauer, Carsten; Hennig-Pauka, Isabel; Hoeltig, Doris; Buettner, Falk F R; Beyerbach, Martin; Gasse, Hagen; Gerlach, Gerald-F; Waldmann, Karl-H

    2012-04-30

    In pigs, diseases of the respiratory tract like pleuropneumonia due to Actinobacillus pleuropneumoniae (App) infection have led to high economic losses for decades. Further research on disease pathogenesis, pathogen-host-interactions and new prophylactic and therapeutic approaches are needed. In most studies, a large number of experimental animals are required to assess lung alterations at different stages of the disease. In order to reduce the required number of animals but nevertheless gather information on the nature and extent of lung alterations in living pigs, a computed tomographic scoring system for quantifying gross pathological findings was developed. In this study, five healthy pigs served as control animals while 24 pigs were infected with App, the causative agent of pleuropneumonia in pigs, in an established model for respiratory tract disease. Computed tomographic (CT) findings during the course of App challenge were verified by radiological imaging, clinical, serological, gross pathology and histological examinations. Findings from clinical examinations and both CT and radiological imaging, were recorded on day 7 and day 21 after challenge. Clinical signs after experimental App challenge were indicative of acute to chronic disease. Lung CT findings of infected pigs comprised ground-glass opacities and consolidation. On day 7 and 21 the clinical scores significantly correlated with the scores of both imaging techniques. At day 21, significant correlations were found between clinical scores, CT scores and lung lesion scores. In 19 out of 22 challenged pigs the determined disease grades (not affected, slightly affected, moderately affected, severely affected) from CT and gross pathological examination were in accordance. Disease classification by radiography and gross pathology agreed in 11 out of 24 pigs. High-resolution, high-contrast CT examination with no overlapping of organs is superior to radiography in the assessment of pneumonic lung lesions

  10. Use of spiral computed tomographic angiography in monitoring abdominal aortic aneurysms after transfemoral endovascular repair.

    PubMed Central

    Balm, R; Jacobs, M J

    1997-01-01

    Transfemoral endovascular repair of abdominal aortic aneurysms has proved to be technically feasible in a selected group of patients. However, long-term efficacy has not been proved. Graft performance after implantation can be monitored by a single imaging technique: spiral computed tomographic angiography. With this technique, the parameters for continuing clinical success of the procedure-graft patency, endoleaks, graft migration, attachment site diameter, attachment system failure, and aneurysm diameter-can be monitored. Only in selected cases will an additional imaging technique be necessary. PMID:9339508

  11. Conventional metrizamide myelography (MM) and computed tomographic metrizamide myelography (CTMM) in scoliosis: a comparative study

    SciTech Connect

    Pettersson, H.; Harwood-Nash, D.C.; Fitz, C.R.; Chuang, H.S.; Armstrong, E.

    1982-01-01

    A retrospective examination was performed to assess the accuracy of metrizamide myelography (MM) and computed tomographic metrizamide myelography (CTMM) in scoliosis. Of 81 consecutive scoliotic children studied by myelography, 30 had only MM while the remaining 51 had CTMM immediately afterward. CTMM added esential diagnostic information in 13 cases of dysraphism and 4 cases, both methods gave the same imformation. The outhors conclude that in patients with severe scoliosis, dysraphism, and scoliosis with localized neurological disturbances, CTMM should always be added to MM or be the only examination; while in idiopathic scoliosis with vague neurological disturbances a survey of the entire spine is essential, preferably with MM.

  12. Automating the segmentation of medical images for the production of voxel tomographic computational models.

    PubMed

    Caon, M; Mohyla, J

    2001-12-01

    Radiation dosimetry for the diagnostic medical imaging procedures performed on humans requires anatomically accurate, computational models. These may be constructed from medical images as voxel-based tomographic models. However, they are time consuming to produce and as a consequence, there are few available. This paper discusses the emergence of semi-automatic segmentation techniques and describes an application (iRAD) written in Microsoft Visual Basic that allows the bitmap of a medical image to be segmented interactively and semi-automatically while displayed in Microsoft Excel. iRAD will decrease the time required to construct voxel models.

  13. Computed tomographic mammography. Diagnosis of mammographically and clinically occult carcinoma of the breast.

    PubMed

    Sibala, J L; Chang, C H; Lin, F; Jewell, W R

    1981-01-01

    If breast cancer can be detected early, while it is still localized and before it can be palpated, the prognosis for cure is excellent. Heretofore, conventional mammography has been the only means available to detect cancer at such an early stage. Two cases of minimal breast carcinoma measuring less than 5 mm in diameter have been detected and correctly diagnosed using computed tomographic mammography (CT/M). Both cases occurred in fatty breasts and were clinically and mammographically occult. These cases demonstrate the value of CT/M in the diagnosis of minimal breast carcinoma that would have been missed otherwise.

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

    PubMed

    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. Using Spitzer to Estimate the Kepler False Positive Rate and to Validate Kepler Candidates.

    NASA Astrophysics Data System (ADS)

    Desert, Jean-Michel; Charbonneau, D.; Fressin, F.; Torres, G.

    2012-01-01

    I present the results from an ongoing large campaign with the Spitzer Space Telescope to gather near-infrared photometric measurements of Kepler Objects of Interest (KOI). Our goals are (1) to validate the planetary status of these Kepler candidates, (2) to estimate observationally the false positive rate, and (3) to study the atmospheres of confirmed planets through measurements of their secondary eclipses. Our target list spans of wide range of candidate sizes and periods orbiting various spectral type stars. The Spitzer observations provide constraints on the possibility of astrophysical false positives resulting from stellar blends, including eclipsing binaries and hierarchical triples. The number of possible blends per star is estimated using stellar population synthesis models and observational probes of the KOI close environments from direct imaging (e.g. Adaptive Optics, Speckle images, Kepler centroids). Combining all the above information with the shape of the transit lightcurves from the Kepler photometry, we compute odd ratios for the 34 candidates we observed in order to determine their false positive probability. Our results suggest that the Kepler false positive rate in this subset of candidates is low. I finally present a new list of Kepler candidates that we were able to validate using this method. This work is based on observations made with the Spitzer, which is operated by JPL/Caltech, under a contract with NASA. Support was provided by NASA through an award issued by JPL/Caltech. Kepler was selected as the 10th mission of the Discovery Program. Funding for this mission is provided by NASA, Science Mission Directorate.

  16. "Does replication groups scoring reduce false positive rate in SNP interaction discovery?: Response"

    PubMed Central

    2010-01-01

    A response to Toplak et al: Does replication groups scoring reduce false positive rate in SNP interaction discovery? BMC Genomics 2010, 11:58. Background The genomewide evaluation of genetic epistasis is a computationally demanding task, and a current challenge in Genetics. HFCC (Hypothesis-Free Clinical Cloning) is one of the methods that have been suggested for genomewide epistasis analysis. In order to perform an exhaustive search of epistasis, HFCC has implemented several tools and data filters, such as the use of multiple replication groups, and direction of effect and control filters. A recent article has claimed that the use of multiple replication groups (as implemented in HFCC) does not reduce the false positive rate, and we hereby try to clarify these issues. Results/Discussion HFCC uses, as an analysis strategy, the possibility of replicating findings in multiple replication groups, in order to select a liberal subset of preliminary results that are above a statistical criterion and consistent in direction of effect. We show that the use of replication groups and the direction filter reduces the false positive rate of a study, although at the expense of lowering the overall power of the study. A post-hoc analysis of these selected signals in the combined sample could then be performed to select the most promising results. Conclusion Replication of results in independent samples is generally used in scientific studies to establish credibility in a finding. Nonetheless, the combined analysis of several datasets is known to be a preferable and more powerful strategy for the selection of top signals. HFCC is a flexible and complete analysis tool, and one of its analysis options combines these two strategies: A preliminary multiple replication group analysis to eliminate inconsistent false positive results, and a post-hoc combined-group analysis to select the top signals. PMID:20576100

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

    NASA Astrophysics Data System (ADS)

    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.

  18. 64-Slice Computed Tomographic Angiography for the Diagnosis of Intermediate Risk Coronary Artery Disease

    PubMed Central

    2010-01-01

    Executive Summary In July 2009, the Medical Advisory Secretariat (MAS) began work on Non-Invasive Cardiac Imaging Technologies for the Diagnosis of Coronary Artery Disease (CAD), an evidence-based review of the literature surrounding different cardiac imaging modalities to ensure that appropriate technologies are accessed by patients suspected of having CAD. This project came about when the Health Services Branch at the Ministry of Health and Long-Term Care asked MAS to provide an evidentiary platform on effectiveness and cost-effectiveness of non-invasive cardiac imaging modalities. After an initial review of the strategy and consultation with experts, MAS identified five key non-invasive cardiac imaging technologies for the diagnosis of CAD. Evidence-based analyses have been prepared for each of these five imaging modalities: cardiac magnetic resonance imaging, single photon emission computed tomography, 64-slice computed tomographic angiography, stress echocardiography, and stress echocardiography with contrast. For each technology, an economic analysis was also completed (where appropriate). A summary decision analytic model was then developed to encapsulate the data from each of these reports (available on the OHTAC and MAS website). The Non-Invasive Cardiac Imaging Technologies for the Diagnosis of Coronary Artery Disease series is made up of the following reports, which can be publicly accessed at the MAS website at: www.health.gov.on.ca/mas or at www.health.gov.on.ca/english/providers/program/mas/mas_about.html Single Photon Emission Computed Tomography for the Diagnosis of Coronary Artery Disease: An Evidence-Based Analysis Stress Echocardiography for the Diagnosis of Coronary Artery Disease: An Evidence-Based Analysis Stress Echocardiography with Contrast for the Diagnosis of Coronary Artery Disease: An Evidence-Based Analysis 64-Slice Computed Tomographic Angiography for the Diagnosis of Coronary Artery Disease: An Evidence-Based Analysis Cardiac

  19. Computed tomographic findings in three dogs naturally infected with Crenosoma vulpis.

    PubMed

    Mortier, Jeremy R; Fina, Caroline J; Edery, Elsa; White, Crystal L; Dhumeaux, Marc P

    2017-09-10

    Crenosoma vulpis is a nematode lungworm found in wild and domestic canids in some parts of North America and Europe. Reported radiographic findings are nonspecific and consist of a combination of bronchial and interstitial changes of variable severity. This retrospective, case series study aimed to describe thoracic computed tomographic (CT) findings for a group of dogs with confirmed crenosomosis. Selection criteria were presentation with a chronic cough during the period of January 2016 to February 2017, evaluation by thoracic CT, and final diagnosis of C. vulpis infection based on bronchoscopic findings, bronchoalveolar lavage fluid analysis, and quantitative polymerase chain reaction. Medical records and CT images were retrieved and reviewed by a board-certified veterinary internist, a veterinary internal medicine resident, two board-certified veterinary radiologists, and a veterinary radiology intern, and findings were recorded. Three dogs met inclusion criteria. Thoracic CT findings for all dogs included the following: diffuse bronchial wall thickening, multifocal peribronchial ground glass attenuation, consolidation of the pulmonary parenchyma, and cylindrical bronchiectasis. In two dogs, the bronchial wall thickening was irregular to nodular, which was consistent with the bronchoscopic findings. Two dogs showed pulmonary parenchymal bands. Thoracic computed tomographic changes in dogs with C. vulpis are consistent with those seen on thoracic radiographs and crenosomosis should be considered in dogs with these findings. © 2017 American College of Veterinary Radiology.

  20. PATHOLOGIC BASIS FOR RIM ENHANCEMENT OBSERVED IN COMPUTED TOMOGRAPHIC IMAGES OF FELINE NASOPHARYNGEAL POLYPS.

    PubMed

    Lamb, Christopher R; Sibbing, Kendall; Priestnall, Simon L

    2016-01-01

    In postcontrast computed tomographic (CT) images, feline nasopharyngeal polyps typically demonstrate enhancement of the peripheral rim. Computed tomographic images and histologic specimens of a case series of 22 cats with surgically removed nasopharyngeal polyps were reviewed retrospectively in an attempt to elucidate the origin of rim enhancement. Polyps were present in the tympanic cavity in 15 (68%) cats (three with extension into the nasopharynx), only in the nasopharynx in four (18%) cats, and only in the external ear canal in the remaining three (14%) cats. All polyps had variable degrees of epithelial injury. Hemorrhage and inflammatory infiltration were significantly more marked in the superficial stroma whereas edema was significantly more marked in the core stroma. In noncontrast CT images (n = 22), the tympanic bulla was thickened in all 15 cats with a polyp in the tympanic cavity and enlarged in eight (53%) of these cats. In postcontrast CT images (n = 15), an outer zone of relatively increased attenuation compatible with a rim was observed in 11 (73%) polyps. The magnitude and extent of rim enhancement in CT images was positively correlated with the histologic grade of inflammation in the superficial stroma and negatively correlated with the grade of edema in the superficial stroma. It appears that inflammation is the major determinant of contrast medium accumulation in feline nasopharyngeal polyps, and the tendency for inflammation to affect predominantly the superficial layers explains the frequent observation of a rim in postcontrast CT images.

  1. THE FALSE POSITIVE RATE OF KEPLER AND THE OCCURRENCE OF PLANETS

    SciTech Connect

    Fressin, Francois; Torres, Guillermo; Charbonneau, David; Dressing, Courtney D.; Bryson, Stephen T.; Christiansen, Jessie; Jenkins, Jon M.; Batalha, Natalie M.; Walkowicz, Lucianne M.

    2013-04-01

    The Kepler mission is uniquely suited to study the frequencies of extrasolar planets. This goal requires knowledge of the incidence of false positives such as eclipsing binaries in the background of the targets, or physically bound to them, which can mimic the photometric signal of a transiting planet. We perform numerical simulations of the Kepler targets and of physical companions or stars in the background to predict the occurrence of astrophysical false positives detectable by the mission. Using real noise level estimates, we compute the number and characteristics of detectable eclipsing pairs involving main-sequence stars and non-main-sequence stars or planets, and we quantify the fraction of those that would pass the Kepler candidate vetting procedure. By comparing their distribution with that of the Kepler Objects of Interest (KOIs) detected during the first six quarters of operation of the spacecraft, we infer the false positive rate of Kepler and study its dependence on spectral type, candidate planet size, and orbital period. We find that the global false positive rate of Kepler is 9.4%, peaking for giant planets (6-22 R{sub Circled-Plus }) at 17.7%, reaching a low of 6.7% for small Neptunes (2-4 R{sub Circled-Plus }), and increasing again for Earth-size planets (0.8-1.25 R{sub Circled-Plus }) to 12.3%. Most importantly, we also quantify and characterize the distribution and rate of occurrence of planets down to Earth size with no prior assumptions on their frequency, by subtracting from the population of actual Kepler candidates our simulated population of astrophysical false positives. We find that 16.5% {+-} 3.6% of main-sequence FGK stars have at least one planet between 0.8 and 1.25 R{sub Circled-Plus} with orbital periods up to 85 days. This result is a significant step toward the determination of eta-earth, the occurrence of Earth-like planets in the habitable zone of their parent stars. There is no significant dependence of the rates of planet

  2. Computed Tomographic Angiography-Based Planning of Bipedicled DIEP Flaps with Intraflap Crossover Anastomosis: An Anatomical and Clinical Study.

    PubMed

    Kim, So Young; Lee, Kyeong-Tae; Mun, Goo-Hyun

    2016-09-01

    When using deep inferior epigastric artery perforator (DIEP) flaps in breast reconstruction, harvesting bipedicled flaps can be a valuable option in cases requiring the transfer of a large portion of harvested flaps. Connecting the bilateral deep inferior epigastric arteries (DIEAs) by intraflap crossover anastomosis is one of the most popular methods of constructing bipedicled DIEP flaps. Planning the primary and secondary pedicle configurations for reliable intraflap crossover anastomosis is crucial. To achieve this, detailed anatomical DIEA information might be helpful. However, meticulous planning of bipedicled DIEP flaps based on computed tomographic angiography has not been reported. Detailed anatomical investigation of DIEA branches was conducted using computed tomographic angiographs of 100 hemiabdomens. Thirty-eight prospectively collected patients who underwent breast reconstruction using bipedicled DIEP flaps with intraflap crossover under computed tomographic angiography-based planning were reviewed. Three intramuscular DIEA branching patterns with distinct branch point topography, branch diameters, and superior continuations cranial to sizable perforators were observed. In the prospective clinical study, a primary pedicle with a recipient branch for intraflap crossover anastomosis could be specified preoperatively using computed tomographic angiography-based anatomical data of the pedicles, including size of DIEA branches or their superior continuation and size of perforators. In all cases, the bipedicle configuration was easily achieved as planned on computed tomographic angiography, and secure perfusion of the entire flap was achieved. The authors' results suggest that computed tomographic angiography provides detailed anatomical DIEA information, and comprehensive analysis of these data allows precise planning of bipedicle configurations with intraflap crossover anastomosis in DIEP flaps. Therapeutic, IV.

  3. Non-Hodgkin lymphoma: computed tomographic demonstration of unusual extranodal involvement.

    PubMed

    Glazer, H S; Lee, J K; Balfe, D M; Mauro, M A; Griffith, R; Sagel, S S

    1983-10-01

    With the advent of computed tomography, lymphomatous involvement of sites other than lymph nodes is being seen with increasing frequency. Review of computed tomographic scans in 400 patients with newly diagnosed or recurrent non-Hodgkin lymphoma revealed 37 patients to have involvement of 56 unusual sites below the diaphragm: psoas/iliacus muscle (16 patients), kidney (13 patients), pancreas (5 patients), adrenal (4 patients), skin/subcutaneous tissue (4 patients), abdominal wall musculature (4 patients), peritoneum (4 patients), omentum (3 patients), and female reproductive tract (3 patients). These were mostly seen in patients with lymphomas of diffuse architecture, especially diffuse histiocytic lymphoma. Concomitant retroperitoneal and/or mesenteric adenopathy was very common; extranodal involvement was rarely the only site of initial or recurrent lymphoma.

  4. Simple load frame for in situ computed tomography and x-ray tomographic microscopy

    SciTech Connect

    Breunig, T.M. ); Stock, S.R.; Brown, R.C. )

    1993-05-01

    In many instances, the response of a sample to external stimuli must be observed repeatedly during the course of an experiment. The sequence in which features are formed is often critical to proper identification of the mechanisms operating, for example, in fatigue and fracture. Merely observing what is visible at the surface of the sample can be misleading or can provide inadequate information about what governs fatigue crack growth or about what controls the fracture process. X-ray imaging allows one to observe the interior of samples and is an attractive technique to use with in situ stressing of test specimens. Here, a simple compact, inexpensive load frame is described for in situ x-ray computed tomography and for very high resolution computed tomography, termed x-ray tomographic microscopy. The load frame is evaluated, and its use is illustrated by observations of crack closure as a function of load in a notched tensile sample of Al-Li-2090.

  5. Non-Hodgkin lymphoma: computed tomographic demonstration of unusual extranodal involvement

    SciTech Connect

    Glazer, H.S.; Lee, J.K.T.; Balfe, D.M.; Mauro, M.A.; Griffith, R.; Sagel, S.S.

    1983-10-01

    With the advent of computed tomography, lymphomatous involvement of sites other than lymph nodes is being seen with increasing frequency. Review of computed tomographic scans in 400 patients with newly diagnosed or recurrent non-Hodgkin lymphoma revealed 37 patients to have involvement of 56 unusual sites below the diaphragm: psoas/iliacus muscle (16 patients), kidney (13 patients), pancreas (5 patients), adrenal (4 patients), skin/subcutaneous tissue (4 patients), abdominal wall musculature (4 patients), peritoneum (4 patients), omentum (3 patients), and female reproductive tract (3 patients). These were mostly seen in patients with lymphomas of diffuse architecture, especially diffuse histiocytic lymphoma. Concomitant retroperitoneal and/or mesenteric adenopathy was very common; extraodal involvement was rarely the only site of initial or recurrent lymphoma.

  6. Time-Dependent Computed Tomographic Perfusion Thresholds for Patients With Acute Ischemic Stroke.

    PubMed

    d'Esterre, Christopher D; Boesen, Mari E; Ahn, Seong Hwan; Pordeli, Pooneh; Najm, Mohamed; Minhas, Priyanka; Davari, Paniz; Fainardi, Enrico; Rubiera, Marta; Khaw, Alexander V; Zini, Andrea; Frayne, Richard; Hill, Michael D; Demchuk, Andrew M; Sajobi, Tolulope T; Forkert, Nils D; Goyal, Mayank; Lee, Ting Y; Menon, Bijoy K

    2015-12-01

    Among patients with acute ischemic stroke, we determine computed tomographic perfusion (CTP) thresholds associated with follow-up infarction at different stroke onset-to-CTP and CTP-to-reperfusion times. Acute ischemic stroke patients with occlusion on computed tomographic angiography were acutely imaged with CTP. Noncontrast computed tomography and magnectic resonance diffusion-weighted imaging between 24 and 48 hours were used to delineate follow-up infarction. Reperfusion was assessed on conventional angiogram or 4-hour repeat computed tomographic angiography. Tmax, cerebral blood flow, and cerebral blood volume derived from delay-insensitive CTP postprocessing were analyzed using receiver-operator characteristic curves to derive optimal thresholds for combined patient data (pooled analysis) and individual patients (patient-level analysis) based on time from stroke onset-to-CTP and CTP-to-reperfusion. One-way ANOVA and locally weighted scatterplot smoothing regression was used to test whether the derived optimal CTP thresholds were different by time. One hundred and thirty-two patients were included. Tmax thresholds of >16.2 and >15.8 s and absolute cerebral blood flow thresholds of <8.9 and <7.4 mL·min(-1)·100 g(-1) were associated with infarct if reperfused <90 min from CTP with onset <180 min. The discriminative ability of cerebral blood volume was modest. No statistically significant relationship was noted between stroke onset-to-CTP time and the optimal CTP thresholds for all parameters based on discrete or continuous time analysis (P>0.05). A statistically significant relationship existed between CTP-to-reperfusion time and the optimal thresholds for cerebral blood flow (P<0.001; r=0.59 and 0.77 for gray and white matter, respectively) and Tmax (P<0.001; r=-0.68 and -0.60 for gray and white matter, respectively) parameters. Optimal CTP thresholds associated with follow-up infarction depend on time from imaging to reperfusion. © 2015 American Heart

  7. Computed Tomographic Morphometry of the Internal Anatomy of Mandibular Second Primary Molars.

    PubMed

    Kurthukoti, Ameet J; Sharma, Pranjal; Swamy, Dinesh Francis; Shashidara, R; Swamy, Elaine Barretto

    2015-01-01

    Need for the study: The most important procedure for a successful endodontic treatment is the cleaning and shaping of the canal system. Understanding the internal anatomy of teeth provides valuable information to the clinician that would help him achieve higher clinical success during endodontic therapy. To evaluate by computed tomography-the internal anatomy of mandibular second primary molars with respect to the number of canals, cross-sectional shape of canals, cross-sectional area of canals and the root dentin thickness. A total of 31 mandibular second primary molars were subjected to computed-tomographic evaluation in the transverse plane, after mounting them in a prefabricated template. The images, thus, obtained were analyzed using De-winter Bio-wizard® software. All the samples demonstrated two canals in the mesial root, while majority of the samples (65.48%) demonstrated two canals in the distal root. The cross-sectional images of the mesial canals demonstrated a round shape, while the distal canals demonstrated an irregular shape. The root dentin thickness was highly reduced on the distal aspect of mesial and mesial aspect of distal canals. The mandibular second primary molars demonstrated wide variation and complexities in their internal anatomy. A thorough understanding of the complexity of the root canal system is essential for understanding the principles and problems of shaping and cleaning, determining the apical limits and dimensions of canal preparations, and for performing successful endodontic procedures. How to cite this article: Kurthukoti AJ, Sharma P, Swamy DF, Shashidara R, Swamy EB. Computed Tomographic Morphometry of the Internal Anatomy of Mandibular Second Primary Molars. Int J Clin Pediatr Dent 2015;8(3):202-207.

  8. Myocardial stunning in hypertrophic cardiomyopathy: recovery predicted by single photon emission computed tomographic thallium-201 scintigraphy

    SciTech Connect

    Fine, D.G.; Clements, I.P.; Callahan, M.J.

    1989-05-01

    A young woman with hypertrophic cardiomyopathy confirmed by echocardiography and cardiac catheterization presented with chest pain and features of a large left ventricular aneurysm. The initial diagnosis was myocardial ischemia with either an evolving or an ancient myocardial infarction. Subsequently, verapamil therapy was associated with complete resolution of the extensive left ventricular wall motion abnormalities, normalization of left ventricular ejection fraction and a minimal myocardial infarction. Normal thallium uptake on single photon emission computed tomographic scintigraphy early in the hospital course predicted myocardial viability in the region of the aneurysm. Thus, orally administered verapamil may reverse spontaneous extensive myocardial ischemia in hypertrophic cardiomyopathy and possibly limit the extent of myocardial infarction in such circumstances.

  9. Optical tomographic detection of rheumatoid arthritis with computer-aided classification schemes

    NASA Astrophysics Data System (ADS)

    Klose, Christian D.; Klose, Alexander D.; Netz, Uwe; Beuthan, Jürgen; Hielscher, Andreas H.

    2009-02-01

    A recent research study has shown that combining multiple parameters, drawn from optical tomographic images, leads to better classification results to identifying human finger joints that are affected or not affected by rheumatic arthritis RA. Building up on the research findings of the previous study, this article presents an advanced computer-aided classification approach for interpreting optical image data to detect RA in finger joints. Additional data are used including, for example, maximum and minimum values of the absorption coefficient as well as their ratios and image variances. Classification performances obtained by the proposed method were evaluated in terms of sensitivity, specificity, Youden index and area under the curve AUC. Results were compared to different benchmarks ("gold standard"): magnet resonance, ultrasound and clinical evaluation. Maximum accuracies (AUC=0.88) were reached when combining minimum/maximum-ratios and image variances and using ultrasound as gold standard.

  10. Computed tomographic evidence of atherosclerosis in the mummified remains of humans from around the world.

    PubMed

    Thompson, Randall C; Allam, Adel H; Zink, Albert; Wann, L Samuel; Lombardi, Guido P; Cox, Samantha L; Frohlich, Bruno; Sutherland, M Linda; Sutherland, James D; Frohlich, Thomas C; King, Samantha I; Miyamoto, Michael I; Monge, Janet M; Valladolid, Clide M; El-Halim Nur El-Din, Abd; Narula, Jagat; Thompson, Adam M; Finch, Caleb E; Thomas, Gregory S

    2014-06-01

    Although atherosclerosis is widely thought to be a disease of modernity, computed tomographic evidence of atherosclerosis has been found in the bodies of a large number of mummies. This article reviews the findings of atherosclerotic calcifications in the remains of ancient people-humans who lived across a very wide span of human history and over most of the inhabited globe. These people had a wide range of diets and lifestyles and traditional modern risk factors do not thoroughly explain the presence and easy detectability of this disease. Nontraditional risk factors such as the inhalation of cooking fire smoke and chronic infection or inflammation might have been important atherogenic factors in ancient times. Study of the genetic and environmental risk factors for atherosclerosis in ancient people may offer insights into this common modern disease.

  11. Nephroureterectomy and ureteroneocystostomy in an alpaca with bilateral ectopic ureters diagnosed by computed tomographic excretory urography.

    PubMed

    Polf, Holly D; Smith, Shasta; Simpson, Katharine M; Rochat, Mark C

    2015-01-01

    To report diagnosis and treatment of urinary incontinence in a female Huacaya alpaca. Clinical case report. Female intact Huacaya alpaca (n = 1) METHODS: Computed tomographic (CT) excretory urography and vaginourethrography were performed to diagnose the cause of urinary incontinence. Bilateral ectopic ureters and left hydronephrosis and hydroureter were diagnosed. Left nephroureterectomy and right ureteroneocystostomy were performed with subsequent resolution of clinical signs. Pyelonephritis was identified by culture of the resected left kidney. CT excretory urography was helpful in the diagnosis of bilateral ectopic ureters in an alpaca and provided information for surgical planning. Surgical repair by ureteroneocystostomy and unilateral nephroureterectomy was successful in resolving clinical signs. © Copyright 2014 by The American College of Veterinary Surgeons.

  12. Coronary computed tomographic angiography in the emergency room: state of the art.

    PubMed

    Cheezum, Michael K; Bittencourt, Marcio S; Hulten, Edward A; Scirica, Benjamin M; Villines, Todd C; Blankstein, Ron

    2014-02-01

    Chest pain is a common complaint in the emergency department often necessitating testing to exclude underlying obstructive coronary artery disease. While the traditional evaluation of patients with suspected acute coronary syndrome often consists of serial electrocardiograms and cardiac biomarkers, followed by selective use of stress testing for further risk stratification, this approach is costly and inefficient. Recently, coronary computed tomographic angiography (CTA) has offered an alternative approach with a high sensitivity and negative predictive value to exclude obstructive coronary artery disease that can rapidly identify patients with low rates of downstream major adverse cardiac events. In this review, the authors provide an overview of available data on the use of CTA for evaluating acute chest pain, while emphasizing its advantages and disadvantages compared to existing strategies. In addition, we provide a suggested algorithm to identify how CTA can be incorporated into the evaluation of acute chest pain and discuss tips for successful implementation of CTA in the emergency department.

  13. Shining Pearls Sign: A New Identity for Venous Malformations on Computed Tomographic Imaging.

    PubMed

    Bhat, Venkatraman; Bhat, Varun

    2016-12-01

    Vascular malformations, in particular venous malformations (VM), are common lesions involving the pediatric and adolescent population. VM occur at approximately 1:5,000 to 10,000; approximately 40% of them occur in the head and neck regions. Classical appearance of VM on imaging is a demonstration of near-normal-sized or mildly dilated feeding arteries which subsequently lead to dilated venous structures of varying caliber, thus constituting the malformation. Phleboliths are the hallmark of VM. Plain radiography has been an established modality for demonstrating phleboliths. The emergence of computed tomographic (CT) as a preferred imaging modality for the evaluation of a complex vascular malformation necessitates familiarity with the spectrum of CT appearances of this lesion. This presentation illustrates an additional CT sign, "shining pearls sign," highlighting the striking display of phleboliths in the vascular malformations, prompting correct diagnosis.

  14. The use of helical computed tomographic scan to assess bony physeal bridges.

    PubMed

    Loder, R T; Swinford, A E; Kuhns, L R

    1997-01-01

    Coronal and sagittal reformatted images of the physis obtained with the helical computed tomography (CT) scanner were studied in five children. This technique allows tomographic slices at 1.0-mm thickness and can be performed in approximately 20 s. The distal femora were studied in two children, the distal tibia in two children, and the distal radius in one child. In three children, after physeal mapping, bar resections were performed. In all cases, the location and size of the bar was accurately predicted by the map constructed from the helical CT scan. We recommend the helical CT scan to prepare physeal maps to determine the extent and location of physeal bony bars because of excellent bony detail, radiation doses one half to one quarter those of conventional tomography, and the rapidity of scanning, which bypasses the need for sedation.

  15. Stature estimation from skull measurements using multidetector computed tomographic images: A Japanese forensic sample.

    PubMed

    Torimitsu, Suguru; Makino, Yohsuke; Saitoh, Hisako; Sakuma, Ayaka; Ishii, Namiko; Yajima, Daisuke; Inokuchi, Go; Motomura, Ayumi; Chiba, Fumiko; Yamaguchi, Rutsuko; Hashimoto, Mari; Hoshioka, Yumi; Iwase, Hirotaro

    2016-01-01

    The aim of this study was to assess the correlation between stature and cranial measurements in a contemporary Japanese population, using three-dimensional (3D) computed tomographic (CT) images. A total of 228 cadavers (123 males, 105 females) underwent postmortem CT scanning and subsequent forensic autopsy between May 2011 and April 2015. Five cranial measurements were taken from 3D CT reconstructed images that extracted only cranial data. The correlations between stature and each of the cranial measurements were assessed with Pearson product-moment correlation coefficients. Simple and multiple regression analyses showed significant correlations between stature and cranial measurements. In conclusion, cranial measurements obtained from 3D CT images may be useful for forensic estimation of the stature of Japanese individuals, particularly in cases where better predictors, such as long bones, are not available. Copyright © 2015. Published by Elsevier Ireland Ltd.

  16. Is coronary computed tomographic angiography the "gold standard" for coronary artery disease?

    PubMed

    Hecht, Harvey S

    2009-01-01

    The proliferation of noninvasive diagnostic tests has been accompanied by validation of each technology by a "gold standard." The anatomic "gold standard" of catheter angiography has been uniformly employed to validate the functional technologies of nuclear, echocardiographic and magnetic resonance stress testing and fractional flow reserve, which are then paradoxically used to judge the anatomic findings. Catheter angiography has also been used as the "gold standard" for the newest technology, coronary computed tomographic angiography (CCTA). By virtue of similar three dimensional characteristics, intravascular ultrasound may be the more appropriate standard for CCTA. However, because of the paradoxical interdependence of the validations, there can be no true "gold standard" for any technology; clinical, outcomes may ultimately be the best option. In the interim, clinical judgment and common sense should be substituted for slavish adherence to an absolute "gold standard" for diagnostic imaging and total reliance on a single diagnostic test.

  17. Health technology assessment: a review of international activity and examples of approaches with computed tomographic colonography.

    PubMed

    Husereau, Don; Morrison, Andra; Battista, Renaldo; Goeree, Ron

    2009-05-01

    The growth of health technology assessment (HTA) internationally is currently reflected in the growing membership of the International Network of Agencies for Health Technology Assessment. Many national and regional HTA institutions emerged in the 1980s and 1990s, and more recently, HTA has emerged in newly industrialized countries and in European Union member states in transition. Health technology assessment activities are becoming an increasingly important part of health care culture, with the appearance of HTA units in hospitals and hospital departments. This article provides a brief overview of who conducts HTA internationally and looks at how HTA is conducted and how this information is used. To highlight the different structures, processes, and methods available, a portion of this article is dedicated to describing different approaches that have been observed with respect to the assessment of computed tomographic colonography in North America for population-based colorectal cancer screening.

  18. The spine in 3D. Computed tomographic reformation from 2D axial sections.

    PubMed

    Virapongse, C; Gmitro, A; Sarwar, M

    1986-01-01

    A new program (3D83, General Electric) was used to reformat three-dimensional (3D) images from two-dimensional (2D) computed tomographic axial scans in 18 patients who had routine scans of the spine. The 3D spine images were extremely true to life and could be rotated around all three principle axes (constituting a movie), so that an illusion of head-motion parallax was created. The benefit of 3D reformation with this program is primarily for preoperative planning. It appears that 3D can also effectively determine the patency of foraminal stenosis by reformatting in hemisections. Currently this program is subject to several drawbacks that require user interaction and long reconstruction time. With further improvement, 3D reformation will find increasing clinical applicability.

  19. Rare Root Canal Configuration of Bilateral Maxillary Second Molar Using Cone-beam Computed Tomographic Scanning.

    PubMed

    Zeng, Chang; Shen, Ya; Guan, Xiaoyue; Wang, Xin; Fan, Mingwen; Li, Yuhong

    2016-04-01

    The aim of this article was to present a right maxillary second molar with an unusual root canal morphology of 4 roots and 5 canals as confirmed by cone-beam computed tomographic (CBCT) imaging. The tooth had a C-shaped mesiobuccal root (CBCT imaging revealed that the root was closer to the palate than the buccal side) with 2 canals, 2 fused distobuccal roots with 2 separate canals, and 1 normal bulky palatal root with 1 canal. After thoroughly examining the rare anatomy, root canal treatment was applied on the tooth. This article shows the complexity of maxillary second molar variation and shows the significance of CBCT imaging in the confirmation of the 3-dimensional anatomy of teeth and endodontic treatment. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  20. Ultrasound-guided mesenteric lymph node iohexol injection for thoracic duct computed tomographic lymphography in cats.

    PubMed

    Kim, Mieun; Lee, Hyeyeon; Lee, Namsoon; Choi, Mihyeon; Kim, Junyoung; Chang, Dongwoo; Choi, Mincheol; Yoon, Junghee

    2011-01-01

    Computed tomographic (CT) lymphography was performed in cats using percutaneous ultrasound-guided injection of contrast medium into a mesenteric lymph node. The thoracic duct and its branches were clearly delineated in CT images of seven cats studied. The thoracic duct was characterized by anatomic variation and appeared as single or multiple branches. The thoracic duct and the cisterna chyli were identified along the ventral or left ventral aspect of the vertebrae from the level of the cranial lumbar to the caudal cervical vertebrae. The thoracic duct was identified in the central caudal mediastinum, deviated to the left in the cranial mediastinum, and finally moved toward the venous system. Small volumes of extranodal contrast medium leakage were identified in all cats. After injection, the mesenteric lymph nodes were cytologically normal. Ultrasound-guided CT lymphography via percutaneous mesenteric lymph node injection appears safe and effective in cats.

  1. Development of the two Korean adult tomographic computational phantoms for organ dosimetry

    SciTech Connect

    Lee, Choonsik; Lee, Choonik; Park, Sang-Hyun; Lee, Jai-Ki

    2006-02-15

    Following the previously developed Korean tomographic phantom, KORMAN, two additional whole-body tomographic phantoms of Korean adult males were developed from magnetic resonance (MR) and computed tomography (CT) images, respectively. Two healthy male volunteers, whose body dimensions were fairly representative of the average Korean adult male, were recruited and scanned for phantom development. Contiguous whole body MR images were obtained from one subject exclusive of the arms, while whole-body CT images were acquired from the second individual. A total of 29 organs and tissues and 19 skeletal sites were segmented via image manipulation techniques such as gray-level thresholding, region growing, and manual drawing, in which each of segmented image slice was subsequently reviewed by an experienced radiologist for anatomical accuracy. The resulting phantoms, the MR-based KTMAN-1 (Korean Typical MAN-1) and the CT-based KTMAN-2 (Korean Typical MAN-2), consist of 300x150x344 voxels with a voxel resolution of 2x2x5 mm{sup 3} for both phantoms. Masses of segmented organs and tissues were calculated as the product of a nominal reference density, the prevoxel volume, and the cumulative number of voxels defining each organs or tissue. These organs masses were then compared with those of both the Asian and the ICRP reference adult male. Organ masses within both KTMAN-1 and KTMAN-2 showed differences within 40% of Asian and ICRP reference values, with the exception of the skin, gall bladder, and pancreas which displayed larger differences. The resulting three-dimensional binary file was ported to the Monte Carlo code MCNPX2.4 to calculate organ doses following external irradiation for illustrative purposes. Colon, lung, liver, and stomach absorbed doses, as well as the effective dose, for idealized photon irradiation geometries (anterior-posterior and right lateral) were determined, and then compared with data from two other tomographic phantoms (Asian and Caucasian), and

  2. Fractional Flow Reserve and Coronary Computed Tomographic Angiography: A Review and Critical Analysis.

    PubMed

    Hecht, Harvey S; Narula, Jagat; Fearon, William F

    2016-07-08

    Invasive fractional flow reserve (FFR) is now the gold standard for intervention. Noninvasive functional imaging analyses derived from coronary computed tomographic angiography (CTA) offer alternatives for evaluating lesion-specific ischemia. CT-FFR, CT myocardial perfusion imaging, and transluminal attenuation gradient/corrected contrast opacification have been studied using invasive FFR as the gold standard. CT-FFR has demonstrated significant improvement in specificity and positive predictive value compared with CTA alone for predicting FFR of ≤0.80, as well as decreasing the frequency of nonobstructive invasive coronary angiography. High-risk plaque characteristics have also been strongly implicated in abnormal FFR. Myocardial computed tomographic perfusion is an alternative method with promising results; it involves more radiation and contrast. Transluminal attenuation gradient/corrected contrast opacification is more controversial and may be more related to vessel diameter than stenosis. Important considerations remain: (1) improvement of CTA quality to decrease unevaluable studies, (2) is the diagnostic accuracy of CT-FFR sufficient? (3) can CT-FFR guide intervention without invasive FFR confirmation? (4) what are the long-term outcomes of CT-FFR-guided treatment and how do they compare with other functional imaging-guided paradigms? (5) what degree of stenosis on CTA warrants CT-FFR? (6) how should high-risk plaque be incorporated into treatment decisions? (7) how will CT-FFR influence other functional imaging test utilization, and what will be the effect on the practice of cardiology? (8) will a workstation-based CT-FFR be mandatory? Rapid progress to date suggests that CTA-based lesion-specific ischemia will be the gatekeeper to the cardiac catheterization laboratory and will transform the world of intervention. © 2016 American Heart Association, Inc.

  3. Relationship of Hypertension to Coronary Atherosclerosis and Cardiac Events in Patients With Coronary Computed Tomographic Angiography.

    PubMed

    Nakanishi, Rine; Baskaran, Lohendran; Gransar, Heidi; Budoff, Matthew J; Achenbach, Stephan; Al-Mallah, Mouaz; Cademartiri, Filippo; Callister, Tracy Q; Chang, Hyuk-Jae; Chinnaiyan, Kavitha; Chow, Benjamin J W; DeLago, Augustin; Hadamitzky, Martin; Hausleiter, Joerg; Cury, Ricardo; Feuchtner, Gudrun; Kim, Yong-Jin; Leipsic, Jonathon; Kaufmann, Philipp A; Maffei, Erica; Raff, Gilbert; Shaw, Leslee J; Villines, Todd C; Dunning, Allison; Marques, Hugo; Pontone, Gianluca; Andreini, Daniele; Rubinshtein, Ronen; Bax, Jeroen; Jones, Erica; Hindoyan, Niree; Gomez, Millie; Lin, Fay Y; Min, James K; Berman, Daniel S

    2017-08-01

    Hypertension is an atherosclerosis factor and is associated with cardiovascular risk. We investigated the relationship between hypertension and the presence, extent, and severity of coronary atherosclerosis in coronary computed tomographic angiography and cardiac events risk. Of 17 181 patients enrolled in the CONFIRM registry (Coronary CT Angiography Evaluation for Clinical Outcomes: An International Multicenter Registry) who underwent ≥64-detector row coronary computed tomographic angiography, we identified 14 803 patients without known coronary artery disease. Of these, 1434 hypertensive patients were matched to 1434 patients without hypertension. Major adverse cardiac events risk of hypertension and non-hypertensive patients was evaluated with Cox proportional hazards models. The prognostic associations between hypertension and no-hypertension with increasing degree of coronary stenosis severity (nonobstructive or obstructive ≥50%) and extent of coronary artery disease (segment involvement score of 1-5, >5) was also assessed. Hypertension patients less commonly had no coronary atherosclerosis and more commonly had nonobstructive and 1-, 2-, and 3-vessel disease than the no-hypertension group. During a mean follow-up of 5.2±1.2 years, 180 patients experienced cardiac events, with 104 (2.0%) occurring in the hypertension group and 76 (1.5%) occurring in the no-hypertension group (hazard ratios, 1.4; 95% confidence intervals, 1.0-1.9). Compared with no-hypertension patients without coronary atherosclerosis, hypertension patients with no coronary atherosclerosis and obstructive coronary disease tended to have higher risk of cardiac events. Similar trends were observed with respect to extent of coronary artery disease. Compared with no-hypertension patients, hypertensive patients have increased presence, extent, and severity of coronary atherosclerosis and tend to have an increase in major adverse cardiac events. © 2017 American Heart Association, Inc.

  4. Predictors of internal mammary vessel diameter: A computed tomographic angiography-assisted anatomic analysis.

    PubMed

    Cook, Julia A; Tholpady, Sunil S; Momeni, Arash; Chu, Michael W

    2016-10-01

    The internal mammary vessels are the most common recipient vessels in free flap breast reconstruction. The literature on internal mammary vascular anatomy is limited by small sample sizes, cadaveric studies, or intraoperative changes. The purpose of this study is to analyze internal mammary anatomy using computed tomographic angiography. A retrospective review of 110 consecutive computed tomographic angiography studies of female patients was performed. Measurements of vessel caliber, distance of internal mammary vessels to sternum, location of internal mammary vein bifurcation, intercostal space height, and chest width were analyzed. Patient demographics and comorbidities were reviewed. The right internal mammary artery and vein were larger than the left in all intercostal spaces (p = 0.02 and p < 0.001, respectively). A significant correlation was found between both skeletal chest width and body mass index with internal mammary vessel caliber at the third intercostal space (p ≤ 0.02). The internal mammary vein bifurcated at the third intercostal space bilaterally, 4.3 and 1.2 mm caudal to the third rib on the right and left sides, respectively. The third intercostal space was <1.5 cm in 25% of patients. Understanding the anatomy, bifurcation, and caliber of internal mammary vessels can aid preoperative planning of autologous, free flap breast reconstruction. On average, the internal mammary vein bifurcates at the third intercostal space; patients with larger chest widths and body mass index had larger caliber internal mammary vessels, and 25% of patients had third intercostal space <1.5 cm and, thus, may not be suitable candidates for rib-sparing techniques. Copyright © 2016 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

  5. Automatic detection of myocardial contours in cine-computed tomographic images

    SciTech Connect

    Philip, K.P.; Dove, E.L.; Stanford, W.; Chandran, K.B. . Dept. of Biomedical Engineering); McPherson, D.D.; Gotteiner, N.L.; Vonesh, M.J. . Dept. of Internal Medicine); Reed, J.E.; Rumberger, J.A. . Dept. of Cardiovascular Diseases)

    1994-06-01

    Quantitative evaluation of cardiac function from cardiac images requires the identification of the myocardial walls. This generally requires the clinician to view the image and interactively trace the contours. This method is susceptible to great variability that depends on the experience and knowledge of the particular operator tracing the contours. The particular imaging modality that is used may also add tracing difficulties. Cine-computed tomography (cine-CT) is an imaging modality capable of providing high quality cross-sectional images of the heart. CT images, however, are cluttered. To decrease this variability, investigators have developed computer-assisted or near-automatic techniques for tracing these contours. All of these techniques, however, require some operator intervention to confidently identify myocardial borders. The authors present a new algorithm that automatically finds the heart within the chest, and then proceeds to outline the myocardial contours. Information at each tomographic slice is used to estimate the contours at the next tomographic slice, thus allowing the algorithm to work in near-apical cross-sectional images where the myocardial borders are often difficult to identify. The algorithm does not require operator input and can be used in a batch mode to process large quantities of data. An evaluation and correction phase is included to allow an operator to view the results and selectively correct portions of contours. They tested the algorithm by automatically identifying the myocardial borders of 27 cardiac images obtained from three human subjects and quantitatively comparing these automatically determined borders with those traced by an experienced cardiologist.

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

    PubMed Central

    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

  7. Reduction of false positives in lung nodule detection using a two-level neural classification.

    PubMed

    Lin, J S; Lo, S B; Hasegawa, A; Freedman, M T; Mun, S K

    1996-01-01

    The authors have developed a neural-digital computer-aided diagnosis system, based on a parameterized two-level convolution neural network (CNN) architecture and on a special multilabel output encoding procedure. The developed architecture was trained, tested, and evaluated specifically on the problem of diagnosis of lung cancer nodules found on digitized chest radiographs. The system performs automatic "suspect" localization, feature extraction, and diagnosis of a particular pattern-class aimed at a high degree of "true-positive fraction" detection and low "false-positive fraction" detection. In this paper, the authors aim at the presentation of the two-level neural classification method in reducing false-positives in their system. They employed receiver operating characteristics (ROC) method with the area under the ROC curve (A(z)) as the performance index to evaluate all the simulation results. The two-level CNN showed superior performance (A(z)=0.93) to the single-level CNN (A(z)=0.85). The proposed two-level CNN architecture is proven to be promising and to be extensible, problem-independent, and therefore, applicable to other medical or difficult diagnostic tasks in two-dimensional (2-D) image environments.

  8. Pulmonary Nodule Detection in CT Images: False Positive Reduction Using Multi-View Convolutional Networks.

    PubMed

    Setio, Arnaud Arindra Adiyoso; Ciompi, Francesco; Litjens, Geert; Gerke, Paul; Jacobs, Colin; van Riel, Sarah J; Wille, Mathilde Marie Winkler; Naqibullah, Matiullah; Sanchez, Clara I; van Ginneken, Bram

    2016-05-01

    We propose a novel Computer-Aided Detection (CAD) system for pulmonary nodules using multi-view convolutional networks (ConvNets), for which discriminative features are automatically learnt from the training data. The network is fed with nodule candidates obtained by combining three candidate detectors specifically designed for solid, subsolid, and large nodules. For each candidate, a set of 2-D patches from differently oriented planes is extracted. The proposed architecture comprises multiple streams of 2-D ConvNets, for which the outputs are combined using a dedicated fusion method to get the final classification. Data augmentation and dropout are applied to avoid overfitting. On 888 scans of the publicly available LIDC-IDRI dataset, our method reaches high detection sensitivities of 85.4% and 90.1% at 1 and 4 false positives per scan, respectively. An additional evaluation on independent datasets from the ANODE09 challenge and DLCST is performed. We showed that the proposed multi-view ConvNets is highly suited to be used for false positive reduction of a CAD system.

  9. Characteristics of false positive findings in CT colonography CAD: a comparison of two fecal tagging regimens

    NASA Astrophysics Data System (ADS)

    Morra, Lia; Delsanto, Silvia; Agliozzo, Silvano; Baggio, Riccardo; Belluccio, Erika; Correale, Loredana; Genova, Dario; Bert, Alberto; Regge, Daniele

    2009-02-01

    The successful application of Computer Aided Detection schemes to CT Colonography depends not only on their performances in terms of sensitivity and specificity, but also on the interaction with the radiologist, and thus ultimately on factors such as the nature of CAD prompts and the reading paradigm. Fecal tagging is emerging as a widely accepted technique for patient preparation, and patient-friendlier schemes are being proposed in an effort to increase compliance to screening programs; the interaction between CAD and FT regimens should likewise be taken into account. In this scenario, an analysis of the characteristics of CAD prompts is of paramount importance in order to guide further research, both from clinical and technical viewpoints. The CAD scheme analyzed in this paper is essentially composed of five steps: electronic cleansing, colon surface extraction, polyp candidate segmentation, pre-filtering of residual tagged stool and classification of the generated candidates in true polyps vs. false alarms. False positives were divided into six categories: untagged and tagged solid stool, haustral folds, extra-colonic candidates, ileocecal valve and cleansing artifacts. A full cathartic preparation was compared with a semi-cathartic regimen with sameday fecal tagging, which is characterized by higher patient acceptance but also higher inhomogeneity. The distribution of false positives at segmentation reflects the quality of preparation, as more inhomogeneous tagging results in a higher number of untagged solid stool and cleansing artifacts.

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

    PubMed

    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.

  11. Noncontrast computed tomographic Hounsfield unit evaluation of cerebral venous thrombosis: a quantitative evaluation.

    PubMed

    Besachio, David A; Quigley, Edward P; Shah, Lubdha M; Salzman, Karen L

    2013-08-01

    Our objective is to determine the utility of noncontrast Hounsfield unit values, Hounsfield unit values corrected for the patient's hematocrit, and venoarterial Hounsfield unit difference measurements in the identification of intracranial venous thrombosis on noncontrast head computed tomography. We retrospectively reviewed noncontrast head computed tomography exams performed in both normal patients and those with cerebral venous thrombosis, acquiring Hounsfield unit values in normal and thrombosed cerebral venous structures. Also, we acquired Hounsfield unit values in the internal carotid artery for comparison to thrombosed and nonthrombosed venous structures and compared the venous Hounsfield unit values to the patient's hematocrit. A significant difference is identified between Hounsfield unit values in thrombosed and nonthrombosed venous structures. Applying Hounsfield unit threshold values of greater than 65, a Hounsfield unit to hematocrit ratio of greater than 1.7, and venoarterial difference values greater than 15 alone and in combination, the majority of cases of venous thrombosis are identifiable on noncontrast head computed tomography. Absolute Hounsfield unit values, Hounsfield unit to hematocrit ratios, and venoarterial Hounsfield unit value differences are a useful adjunct in noncontrast head computed tomographic evaluation of cerebral venous thrombosis.

  12. False positive reduction for pulmonary nodule detection using two-dimensional principal component analysis

    NASA Astrophysics Data System (ADS)

    Choi, Wook-Jin; Choi, Tae-Sun

    2009-08-01

    Pulmonary nodule detection is a binary classification problem. The main objective is to classify nodule from the lung computed tomography (CT) images. The intra class variability is mainly due to the grey-level variance, texture differences and shape. The purpose of this study is to develop a novel nodule detection method which is based on Two-dimensional Principal Component Analysis (2DPCA). We extract the futures using 2DPCA from nodule candidate images. Nodule candidates are classified using threshold. The proposed method reduces False Positive (FP) rate. We tested the proposed algorithm by using Lung Imaging Database Consortium (LIDC) database of National Cancer Institute (NCI). The experimental results demonstrate the effectiveness and efficiency of the proposed method. The proposed method achieved 85.11% detection rate with 1.13 FPs per scan.

  13. Anterior cervical fusion assessment using reconstructed computed tomographic scans: surgical confirmation of 254 segments.

    PubMed

    Song, Kwang-Sup; Chaiwat, Piyaskulkaew; Kim, Han Jo; Mesfin, Addisu; Park, Sang-Min; Riew, K Daniel

    2013-12-01

    Retrospective study developing diagnostic criteria. To validate 2 computed tomography-based findings, extragraft bone bridging (ExGBB) and intragraft bone bridging (InGBB), as diagnostic criteria for anterior cervical fusion using subsequent surgical confirmation and to demonstrate the different diagnostic accuracy on the basis of the graft material used. The accuracy and the methodology for evaluating bone bridging on computed tomographic scans to determine anterior cervical fusion status have not been validated or standardized. One hundred ten patients with 254 surgically explored segments along with reconstructed computed tomographic scans were included. Bone bridging at each cervical level was assessed for ExGBB and InGBB. ExGBB was defined as complete cortical bridging at any peripheral margins (anterior, posterior, left, or right) of the operated disc space, outside of the graft. InGBB was defined as cortical or trabecular bridging within the confines of the graft only. ExGBB and InGBB were serially evaluated on reformatted coronal and sagittal views by 3 independent raters. The reliabilities and validities correlated with surgical exploration were evaluated. Surgical exploration revealed 123 fused and 131 pseudarthrosis segments. The reliability of 3 raters showed near perfect agreement for ExGBB and substantial agreement for InGBB. ExGBB also had higher validity for all raters than did InGBB. The autocortical graft group had the highest accuracy for both InGBB and ExGBB, with both values being nearly identical. The allograft group had the next highest validity values. For the cage group, InGBB had the lowest specificity (53.2%) and positive predictive value (35.5%), whereas ExGBB had 100% sensitivity and negative predictive value. ExGBB seems to be a far more reliable and accurate to determine anterior cervical fusion. The diagnostic criteria using bone bridging should be different based on the intradiscal materials. With cages in particular, InGBB seems

  14. Evaluation of Cervical Spine Clearance by Computed Tomographic Scan Alone in Intoxicated Patients With Blunt Trauma.

    PubMed

    Bush, Lisa; Brookshire, Robert; Roche, Breanna; Johnson, Amelia; Cole, Frederic; Karmy-Jones, Riyad; Long, William; Martin, Matthew J

    2016-09-01

    cervical collar for intoxication had no missed CSIs but were kept immobilized for a mean (SD) of 12 (19) hours. Computed tomographic scans had an overall negative predictive value of 99.2% for patients with CSIs and a negative predictive value of 99.8% for ruling out CSIs that required immobilization or stabilization. In this study, alcohol or drug intoxication was common and resulted in significant delays to cervical spine clearance. Computed tomographic scans were highly reliable for identifying all clinically significant CSIs. Spine clearance based on a normal CT scan among intoxicated patients with no gross motor deficits appears to be safe and avoids prolonged and unnecessary immobilization.

  15. A retrospective analysis of false-positive infectious screening results in blood donors

    PubMed Central

    Vo, Michelle T.; Bruhn, Roberta; Kaidarova, Zhanna; Custer, Brian S.; Murphy, Edward L.; Bloch, Evan M.

    2016-01-01

    BACKGROUND False-positive infectious transfusion screening results remain a challenge with continued loss of both donors and blood products. We sought to identify associations between donor demographic characteristics (age, race, sex, education, first-time donor status) and testing false positive for viruses during routine blood donation screening. In addition the study assessed the prevalence of high-risk behaviors in false-positive donors. STUDY DESIGN AND METHODS Blood Systems, Inc. donors with allogeneic donations between January 1, 2011, and December 31, 2012, were compared in a case-control study. Those with a false-positive donation for one of four viruses (human immunodeficiency virus [HIV], human T-lymphotropic virus [HTLV], hepatitis B virus [HBV], and hepatitis C virus [HCV]) were included as cases. Those with negative test results were controls. For a subset of cases, infectious risk factors were evaluated. RESULTS Black race and Hispanic ethnicity were associated with HCV and HTLV false-positive results. Male sex and lower education were associated with HCV false positivity, and age 25 to 44 was associated with HTLV false positivity. First-time donors were more likely to be HCV false positive although less likely to be HBV and HTLV false positive. No significant associations between donor demographics and HIV false positivity were observed. A questionnaire for false-positive donors showed low levels of high-risk behaviors. CONCLUSION Demographic associations with HCV and HTLV false-positive results overlap with those of true infection. While true infection is unlikely given current testing algorithms and risk factor evaluation, the findings suggest nonrandom association. Further investigation into biologic mechanisms is warranted. PMID:26509432

  16. Seeing is believing: video classification for computed tomographic colonography using multiple-instance learning.

    PubMed

    Wang, Shijun; McKenna, Matthew T; Nguyen, Tan B; Burns, Joseph E; Petrick, Nicholas; Sahiner, Berkman; Summers, Ronald M

    2012-05-01

    In this paper, we present development and testing results for a novel colonic polyp classification method for use as part of a computed tomographic colonography (CTC) computer-aided detection (CAD) system. Inspired by the interpretative methodology of radiologists using 3-D fly-through mode in CTC reading, we have developed an algorithm which utilizes sequences of images (referred to here as videos) for classification of CAD marks. For each CAD mark, we created a video composed of a series of intraluminal, volume-rendered images visualizing the detection from multiple viewpoints. We then framed the video classification question as a multiple-instance learning (MIL) problem. Since a positive (negative) bag may contain negative (positive) instances, which in our case depends on the viewing angles and camera distance to the target, we developed a novel MIL paradigm to accommodate this class of problems. We solved the new MIL problem by maximizing a L2-norm soft margin using semidefinite programming, which can optimize relevant parameters automatically. We tested our method by analyzing a CTC data set obtained from 50 patients from three medical centers. Our proposed method showed significantly better performance compared with several traditional MIL methods.

  17. Determination of planning target volume for whole stomach irradiation using daily megavoltage computed tomographic images.

    PubMed

    Johnson, Matthew E; Pereira, Gisele C; El Naqa, Issam M; Goddu, S Murty; Al-Lozi, Rawan; Apte, Aditya; Mansur, David B

    2012-01-01

    Whole stomach radiation therapy is often used in the management of gastric lymphoma. However, very limited data exist with regard to planning target volume requirements for the whole stomach. This study retrospectively analyzed daily megavoltage computed tomographic (CT) scans of gastric lymphoma patients in order to help determine the interfraction variation of the stomach position. Forty-one daily megavoltage CT images from 3 gastric lymphoma patients were used for stomach contouring. Each patient's megavoltage CT images were rigidly registered to their CT simulation data sets, and the margin in each direction that covered at least 95% of the daily stomach volumes was computed using a simple grid search. Patient setup variation was also calculated from the daily patient shifts. The organ motion margin was then added to the setup margin to render the total margin. A uniform margin of 2.2 cm is required to cover 95% of the stomach over the treatment course. However, direction-specific margins were observed from 1.72, 1.88, 0.92, 2.23, 1.90, and 0.86 cm for the right, left, posterior, anterior, superior, and inferior directions, respectively. The results of this study provide helpful 3-dimensional volumetric information to the limited existing data on margin requirements for whole stomach radiation therapy. Copyright © 2012 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.

  18. Two methods of Haustral fold detection from computed tomographic virtual colonoscopy images

    NASA Astrophysics Data System (ADS)

    Chowdhury, Ananda S.; Tan, Sovira; Yao, Jianhua; Linguraru, Marius G.; Summers, Ronald M.

    2009-02-01

    Virtual colonoscopy (VC) has gained popularity as a new colon diagnostic method over the last decade. VC is a new, less invasive alternative to the usually practiced optical colonoscopy for colorectal polyp and cancer screening, the second major cause of cancer related deaths in industrial nations. Haustral (colonic) folds serve as important landmarks for virtual endoscopic navigation in the existing computer-aided-diagnosis (CAD) system. In this paper, we propose and compare two different methods of haustral fold detection from volumetric computed tomographic virtual colonoscopy images. The colon lumen is segmented from the input using modified region growing and fuzzy connectedness. The first method for fold detection uses a level set that evolves on a mesh representation of the colon surface. The colon surface is obtained from the segmented colon lumen using the Marching Cubes algorithm. The second method for fold detection, based on a combination of heat diffusion and fuzzy c-means algorithm, is employed on the segmented colon volume. Folds obtained on the colon volume using this method are then transferred to the corresponding colon surface. After experimentation with different datasets, results are found to be promising. The results also demonstrate that the first method has a tendency of slight under-segmentation while the second method tends to slightly over-segment the folds.

  19. Seeing is Believing: Video Classification for Computed Tomographic Colonography Using Multiple-Instance Learning

    PubMed Central

    Wang, Shijun; McKenna, Matthew T.; Nguyen, Tan B.; Burns, Joseph E.; Petrick, Nicholas; Sahiner, Berkman

    2012-01-01

    In this paper we present development and testing results for a novel colonic polyp classification method for use as part of a computed tomographic colonography (CTC) computer-aided detection (CAD) system. Inspired by the interpretative methodology of radiologists using 3D fly-through mode in CTC reading, we have developed an algorithm which utilizes sequences of images (referred to here as videos) for classification of CAD marks. For each CAD mark, we created a video composed of a series of intraluminal, volume-rendered images visualizing the detection from multiple viewpoints. We then framed the video classification question as a multiple-instance learning (MIL) problem. Since a positive (negative) bag may contain negative (positive) instances, which in our case depends on the viewing angles and camera distance to the target, we developed a novel MIL paradigm to accommodate this class of problems. We solved the new MIL problem by maximizing a L2-norm soft margin using semidefinite programming, which can optimize relevant parameters automatically. We tested our method by analyzing a CTC data set obtained from 50 patients from three medical centers. Our proposed method showed significantly better performance compared with several traditional MIL methods. PMID:22552333

  20. COMPUTED TOMOGRAPHIC ANATOMY AND CHARACTERISTICS OF RESPIRATORY ASPERGILLOSIS IN JUVENILE WHOOPING CRANES

    PubMed Central

    Kelley, Cristin; Pinkerton, Marie E.; Hartup, Barry K.

    2015-01-01

    Respiratory diseases are a leading cause of morbidity and mortality in captivity reared, endangered whooping cranes (Grus americana). Objectives of this retrospective, case series, cross‐sectional study were to describe computed tomography (CT) respiratory anatomy in a juvenile whooping crane without respiratory disease, compare CT characteristics with gross pathologic characteristics in a group of juvenile whooping cranes with respiratory aspergillosis, and test associations between the number of CT tracheal bends and bird sex and age. A total of 10 juvenile whooping cranes (one control, nine affected) were included. Seven affected cranes had CT characteristics of unilateral extrapulmonary bronchial occlusion or wall thickening, and seven cranes had luminal occlusion of the intrapulmonary primary or secondary bronchi. Air sac membrane thickening was observed in three cranes in the cranial and caudal thoracic air sacs, and air sac diverticulum opacification was observed in four cranes. Necropsy lesions consisted of severe, subacute to chronic, focally extensive granulomatous pathology of the trachea, primary bronchi, lungs, or air sacs. No false positive CT scan results were documented. Seven instances of false negative CT scan results occurred; six of these consisted of subtle, mild air sacculitis including membrane opacification or thickening, or the presence of small plaques found at necropsy. The number of CT tracheal bends was associated with bird age but not sex. Findings supported the use of CT as a diagnostic test for avian species with respiratory disease and tracheal coiling or elongated tracheae where endoscopic evaluation is impractical. PMID:26592357

  1. Three-dimensional segmentation of the tumor in computed tomographic images of neuroblastoma.

    PubMed

    Deglint, Hanford J; Rangayyan, Rangaraj M; Ayres, Fábio J; Boag, Graham S; Zuffo, Marcelo K

    2007-09-01

    Segmentation of the tumor in neuroblastoma is complicated by the fact that the mass is almost always heterogeneous in nature; furthermore, viable tumor, necrosis, and normal tissue are often intermixed. Tumor definition and diagnosis require the analysis of the spatial distribution and Hounsfield unit (HU) values of voxels in computed tomography (CT) images, coupled with a knowledge of normal anatomy. Segmentation and analysis of the tissue composition of the tumor can assist in quantitative assessment of the response to therapy and in the planning of the delayed surgery for resection of the tumor. We propose methods to achieve 3-dimensional segmentation of the neuroblastic tumor. In our scheme, some of the normal structures expected in abdominal CT images are delineated and removed from further consideration; the remaining parts of the image volume are then examined for tumor mass. Mathematical morphology, fuzzy connectivity, and other image processing tools are deployed for this purpose. Expert knowledge provided by a radiologist in the form of the expected structures and their shapes, HU values, and radiological characteristics are incorporated into the segmentation algorithm. In this preliminary study, the methods were tested with 10 CT exams of four cases from the Alberta Children's Hospital. False-negative error rates of less than 12% were obtained in eight of 10 exams; however, seven of the exams had false-positive error rates of more than 20% with respect to manual segmentation of the tumor by a radiologist.

  2. Implications for the False-positive Rate in Kepler Planet Systems from Transit Duration Ratios

    NASA Astrophysics Data System (ADS)

    Morehead, Robert C.; Ford, Eric B.

    2015-01-01

    Confirming transiting exoplanet candidates through traditional follow-up methods is challenging, especially for faint host stars. Most of Kepler's validated planets relied on statistical methods to separate true planets from false-positives. Multiple transiting planet systems (MTPS) have been previously shown to have low false-positive rates and over 851 planets in MTPSs have been statistically validated so far (Lissauer et al. 2014; Rowe et al. 2014). We show that the period-normalized transit duration ratio (ξ) offers additional information that can be used to establish the planetary nature of these systems. We briefly discuss the observed distribution of ξ for the Q1-Q16 Kepler Candidate Search. We also utilize ξ to develop a Bayesian statistical framework combined with Monte Carlo methods to determine which pairs of planet candidates in a MTPS are consistent with the planet hypothesis for a sample of 676 MTPSs that include both candidate and confirmed planets. This analysis proves to be efficient and advantageous in that it only requires catalog-level bulk candidate properties and galactic population modeling to compute the probabilities of a myriad of stellar blend scenarios, without needing additional observational follow-up. Our results agree with the previous results of a low false-positive rate in the Kepler MTPSs. Out of our sample of 1,358 pairs of candidates, we find that about 100 pairs have a probability greater than 0.99 of being a MTPS associated with the target star, over 800 pairs have a probability greater than 0.99 of being a MTPS associated with the target star or another star blended in the photometric aperture. Further more, we find that well over a 1,000 pairs have a probability greater than 0.99 to be planetary in nature, either orbiting the same star or separately orbiting two different stars in the aperture. This implies, independently of any other estimates, that most of the MTPSs detected by Kepler are very likely to be planetary in

  3. Assessment of the Radiation Effects of Cardiac Computed Tomographic Angiography Using Protein and Genetic Biomarkers

    PubMed Central

    Nguyen, Patricia K.; Lee, Won Hee; Li, Yong Fuga; Hong, Wan Xing; Hu, Shijun; Chan, Charles; Liang, Grace; Nguyen, Ivy; Ong, Sang-Ging; Churko, Jared; Wang, Jia; Altman, Russ B.; Fleischmann, Dominik; Wu, Joseph C.

    2016-01-01

    Objectives To evaluate whether radiation exposure from cardiac computed tomographic angiography is associated with DNA damage and whether damage leads to programmed cell death and activation of genes involved in apoptosis and DNA repair. Background Exposure to radiation from medical imaging has become a public health concern, but whether it causes significant cell damage remains unclear. Methods We conducted a prospective cohort study in 67 patients undergoing cardiac computed tomographic angiography (CTA) between January 2012 and December 2013 in two US medical centers. Median blood radiation exposure was estimated using phantom dosimetry. Biomarkers of DNA damage and apoptosis were measured by flow cytometry, whole genome sequencing, and single cell polymerase chain reaction. Results The median DLP was 1535.3 mGy·cm (969.7 – 2674.0 mGy·cm). The median radiation dose to the blood was 29.8 milliSieverts (18.8 – 48.8 mSv). Median DNA damage increased 3.39% (1.29 – 8.04%, P<0.0001) post-radiation. Median apoptosis increased 3.1-fold (1.4 – 5.1-fold, P<0.0001) post-radiation. Whole genome sequencing revealed changes in the expression of 39 transcription factors involved in the regulation of apoptosis, cell cycle, and DNA repair. Genes involved in mediating apoptosis and DNA repair were significantly changed post-radiation, including DDB2 [1.9-fold (1.5 – 3.0-fold), P<0.001], XRCC4 [3.0-fold (1.1 – 5.4-fold), P=0.005], and BAX [1.6-fold (0.9 – 2.6-fold), P<0.001]. Exposure to radiation was associated with DNA damage [OR: 1.8 (1.2 – 2.6), P=0.003]. DNA damage was associated with apoptosis [OR: 1.9 (1.2 – 5.1), P<0.0001] and gene activation [OR: 2.8 (1.2 – 6.2), P=0.002]. Conclusions Patients exposed to radiation from cardiac CTA had evidence of DNA damage, which was associated with programmed cell death and activation of genes involved in apoptosis and DNA repair. PMID:26210695

  4. Selective computed tomographic angiography in traumatic subarachnoid hemorrhage: a pilot study.

    PubMed

    Balinger, Kathryn J; Elmously, Adham; Hoey, Brian A; Stehly, Christy D; Stawicki, Stanislaw Peter; Portner, Marc E

    2015-11-01

    Computed tomographic angiography (CTA) tends to be overused in patients with traumatic subarachnoid hemorrhage (tSAH) to rule out intracranial aneurysmal disease. We hypothesized that there are two exclusive subsets of patients with tSAH that maybe at increased risk for aneurysm and thus should undergo CTA, those "found down" with an unknown mechanism of injury and those with "central subarachnoid hemorrhage" (CSH, in the subarachnoid cisterns and Sylvian fissures). This pilot study was performed to provide more information on the validity of our hypothesis. A retrospective analysis was performed on trauma patients with tSAH who underwent CTA of the brain. Patients presented to a level I trauma center from January 2008-December 2012. Our principal outcome was the diagnosis of an intracranial aneurysm. Student t-test, chi-squared test, Mann-Whitney U test, and binary logistic regression were used for statistical analysis, with significance set at alpha = 0.05. Of 617 total patients with tSAH, 186 patients underwent CTA. Majority of patients were male (64%), with median age of 56 y. Median Glasgow coma scale on presentation was 15, and the median injury severity score was 16. Thirteen patients (6.99%) had an aneurysm on the follow-up CTA. Of those, 8 of 13 (61.5%) were felt to have presented with a ruptured aneurysm. Among those, 5 of 8 (62.5%) sustained a fall and 3 of 8 (37.5%) resulted from a motor vehicle crash. Among the 14 patients (7.5%) "found down", none had an aneurysm. All eight patients with a ruptured aneurysm (100%) had CSH, whereas none of the five patients with unruptured aneurysm had CSH. On multivariate analysis, suprasellar cistern hemorrhage was the most predictive noncontrast computed tomographic finding with regard to aneurysm presence (odds ratio, 4.78; 95% confidence interval, 1.33-17.1). Patients with an aneurysmal disease had a significantly higher mean arterial pressure on presentation (median, 115 mm Hg) than those without an aneurysm

  5. Acute appendicitis: clinical outcome in patients with an initial false-positive CT diagnosis.

    PubMed

    Stengel, Joseph W; Webb, Emily M; Poder, Liina; Yeh, Benjamin M; Smith-Bindman, Rebecca; Coakley, Fergus V

    2010-07-01

    To investigate the clinical outcome in patients with a diagnosis of appendicitis at computed tomography (CT) in whom treatment is deemed unnecessary after clinical evaluation. After institutional review board approval, 2283 patients (856 men, 1427 women; mean age, 46 years; age range, 18-99 years) who underwent CT because they were suspected of having appendicitis between 2002 and 2007 were retrospectively identified. CT reports were reviewed, and the likelihood of appendicitis was assigned a score on a five-point scale: score 1, definitely absent; score 2, nonvisualized appendix with no secondary signs of inflammation; score 3, equivocal; score 4, probable; and score 5, definitely present. Diagnosis of appendicitis at CT was considered a false-positive result if the CT report was classified as probable or definite appendicitis but the patient was not treated within 4 days. Cases with false-positive results were reviewed by two readers blinded to patient outcome, supporting clinical data, and prospective scan interpretation, and a grade was assigned by using the same scale. Medical records were reviewed to determine outcomes. Descriptional statistics were used. Overall, 516 (23%) of 2283 patients had CT findings of probable or definite appendicitis. Thirteen (3%) of 516 patients did not receive immediate treatment for appendicitis. Of these, five (38%; 95% confidence interval: 18%, 65%) underwent later appendectomy with proved appendicitis after a mean interval of 118 days (range, 5-443 days). Seven (54%) of 13 patients never developed appendicitis across a mean follow-up of 583 days (range, 14-1460 days). One (8%) of 13 had a normal appendix at eventual surgery. Five of 13 patients with CT findings of appendicitis and reassuring clinical evaluation results in whom immediate treatment was deferred ultimately returned with appendicitis. In patients with CT results positive for appendicitis and benign or atypical clinical findings, a diagnosis of chronic or recurrent

  6. Reducing false positives of small bowel segmentation on CT scans by localizing colon regions

    NASA Astrophysics Data System (ADS)

    Zhang, Weidong; Liu, Jiamin; Yao, Jianhua; Summers, Ronald M.

    2014-03-01

    Automated small bowel segmentation is essential for computer-aided diagnosis (CAD) of small bowel pathology, such as tumor detection and pre-operative planning. We previously proposed a method to segment the small bowel using the mesenteric vasculature as a roadmap. The method performed well on small bowel segmentation but produced many false positives, most of which were located on the colon. To improve the accuracy of small bowel segmentation, we propose a semi-automated method with minimum interaction to distinguish the colon from the small bowel. The method utilizes anatomic knowledge about the mesenteric vasculature and a statistical method of colon detection. First, anatomic labeling of the mesenteric arteries is used to identify the arteries supplying the colon. Second, a statistical detector is created by combining two colon probability maps. One probability map is of the colon location and is generated from colon centerlines generated from CT colonography (CTC) data. Another probability map is of 3D colon texture using Haralick features and support vector machine (SVM) classifiers. The two probability maps are combined to localize colon regions, i.e., voxels having high probabilities on both maps were labeled as colon. Third, colon regions identified by anatomical labeling and the statistical detector are removed from the original results of small bowel segmentation. The method was evaluated on 11 abdominal CT scans of patients suspected of having carcinoid tumors. The reference standard consisted of manually-labeled small bowel segmentation. The method reduced the voxel-based false positive rate of small bowel segmentation from 19.7%±3.9% to 5.9%±2.3%, with two-tailed P-value < 0.0001.

  7. False positive reduction for wall thickness-based detection of colonic flat polyps via CT colonography

    NASA Astrophysics Data System (ADS)

    Pomeroy, Marc; Li, Lihong C.; Han, Hao; Wei, Xinzhou; Pickhardt, Perry J.; Liang, Zhengrong

    2017-03-01

    Computer-aided detection (CAD) of flat polyps, in contrast to other polyp types, is challenging due to their lack of projections from the colonic surface and limited geometrical features that can be extracted from such polyps. In this paper, we present a new approach for CAD of flat polyps via colon wall thickness mapping, texture feature extraction and analysis. First, we integrated our previous work of detecting flat polyp candidates via colon wall thickness mapping into this study for automated detection of initial polyp candidates (IPCs). The colon wall segmentation is established on a coupled level-set method after the lumen is electronically cleansed by a sophisticated statistical algorithm, which considers the partial volume effect to preserve the mucosa layer details. The IPC detection was performed based on the wall thickness local pattern. From each IPC volume, we extracted the 14 Haralick texture features and 16 additional features that were previously demonstrated to improve polyp classification performance. Then, we adopted the Rpackage "randomForest" to classify the features for false positive (FP) reduction. We evaluated our method via 16 patient datasets. The proposed scheme achieved a high capacity in terms of the well-known area under the curve value of 0.930. The FPs was reduced to less than 3 FPs/per polyp. The experiment results demonstrate the feasibility of our method in achieving computer aided detection of flat polyps, therefore, improving the screening capability of computed tomography cololongraphy.

  8. Preliminary application of high-definition computed tomographic Gemstone Spectral Imaging in lung cancer.

    PubMed

    Wang, Guangli; Zhang, Chengqi; Li, Mingying; Deng, Kai; Li, Wei

    2014-01-01

    To evaluate the feasibility of multiparameter quantitative measurement lung cancer by Gemstone Spectral Imaging (GSI) high-definition computed tomography. Seventy-seven patients who were found to have a lung mass or a nodule by CT plain scan for the first time received chest contrast CT scan with GSI mode on high-definition computed tomography. The GSI viewer was used to display the spectral curve, iodine-based images, water-based images, and 101 sets of monochromatic images of a selected region of interest from the relative homogeneous area of the mass or nodule. Iodine concentration, water concentration, spectral curve slope, and CT values at 40 keV of the region of interest were measured. Finally, 68 eligible patients were divided into a pneumonia group (n = 24) and a malignant tumor group (n = 44, including squamous carcinoma, n = 29, and adenocarcinoma, n = 15). Significant differences existed in iodine concentration (t = 6.459), spectral curve slope (t = 6.276), and CT values at 40 keV (t = 6.698) between the pneumonia group and the malignant tumor group (P < 0.05), as well as between squamous carcinoma and adenocarcinoma (t = 6.494, 5.634, 6.091, respectively, P < 0.05), whereas water concentrations were found to have no difference between the 2 groups (t = 0.082, P > 0.05) and between the 2 types of malignant tumors (t = 1.234, P > 0.05). High-definition computed tomographic GSI technique might be helpful to differentiate lung cancer from lung benign lesions by providing qualitative and quantitative information.

  9. A Closer Look at Self-Reported Suicide Attempts: False Positives and False Negatives

    ERIC Educational Resources Information Center

    Ploderl, Martin; Kralovec, Karl; Yazdi, Kurosch; Fartacek, Reinhold

    2011-01-01

    The validity of self-reported suicide attempt information is undermined by false positives (e.g., incidences without intent to die), or by unreported suicide attempts, referred to as false negatives. In a sample of 1,385 Austrian adults, we explored the occurrence of false positives and false negatives with detailed, probing questions. Removing…

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

    ERIC Educational Resources Information Center

    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…

  11. Cardiac computed tomographic angiography for detection of cardiac sources of embolism in stroke patients.

    PubMed

    Hur, Jin; Kim, Young Jin; Lee, Hye-Jeong; Ha, Jong-Won; Heo, Ji Hoe; Choi, Eui-Young; Shim, Chi-Young; Kim, Tae Hoon; Nam, Ji Eun; Choe, Kyu Ok; Choi, Byoung Wook

    2009-06-01

    We assessed the diagnostic performance of 2-phase 64-slice cardiac computed tomographic angiography (CCTA) for the detection of a cardiac source of embolism in stroke patients using transesophageal echocardiography (TEE) as the reference standard. We selected 137 patients who had experienced a recent episode of stroke and had undergone both 2-phase 64-slice CCTA and TEE within a period of 5 days. A potential cardiac source of embolism detected at both CCTA and TEE was recorded, and echocardiographic findings were categorized into high- and medium-risk sources based on the TOAST (Trial of Org 10172 in Acute Stroke Treatment) classification. Of 137 patients, 100 abnormal findings in 91 patients were found on TEE, and 46 patients had no abnormal finding on TEE. The overall sensitivity, specificity, positive predictive value, and negative predictive value of the 64-slice CCTA for detecting cardiac sources of embolism were 89% (95% CI, 82%, 95%), 100% (95% CI, 90%, 100%), 100% (95% CI, 95%, 100%), and 81% (95% CI, 70%, 92%), respectively. TEE detected a total of 47 high-risk sources of embolism, whereas CT detected 44 lesions. For medium-risk sources of cardiac embolic stroke, TEE detected a total of 53 abnormal findings, whereas CT detected 44 abnormal findings. Of 53 lesions, there were 8 false-negative results on CT (5 patent foramen ovale and 3 atrial septal aneurysm). Two-phase 64-slice CCTA is a noninvasive and useful modality for detecting high-risk cardiac sources of embolism in stroke patients.

  12. Whole-Brain Computed Tomographic Perfusion Imaging in Acute Cerebral Venous Sinus Thrombosis

    PubMed Central

    Mokin, Maxim; Ciambella, Chelsey C.; Masud, Muhammad W.; Levy, Elad I.; Snyder, Kenneth V.; Siddiqui, Adnan H.

    2016-01-01

    Background Acute cerebral venous sinus thrombosis (VST) can be difficult to diagnose because of its diverse clinical presentation. The utility of perfusion imaging for diagnosing VST is not well understood. Summary We retrospectively reviewed cases of acute VST in patients who underwent whole-brain (320-detector-row) computed tomographic (CT) perfusion imaging in combination with craniocervical CT venography. Perfusion maps that were analyzed included cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time, and time to peak. Among the 10 patients with acute VST included in this study, 9 had perfusion abnormalities. All perfusion abnormalities were localized in areas adjacent to the occluded sinus and did not match typical anterior or posterior circulation arterial territories. Bilateral perfusion deficits were seen in 4 cases. In 2 cases, parenchymal hemorrhage was diagnosed on noncontrast CT imaging; in those cases, focal CBV and CBF were reduced. Key Messages Whole-brain CT perfusion imaging with 320-detector-row scanners can further assist in establishing the diagnosis of VST by detecting perfusion abnormalities corresponding to venous and not arterial territories. CT perfusion could assist in the differentiation between focal reversible changes, such as those caused by vasogenic edema, and irreversible changes due to infarction. PMID:27051406

  13. Value of computed tomographic angiography in neck and extremity pediatric vascular trauma.

    PubMed

    Hogan, Anthony R; Lineen, Edward B; Perez, Eduardo A; Neville, Holly L; Thompson, William R; Sola, Juan E

    2009-06-01

    We sought to define the sensitivity and specificity of computed tomographic angiography (CTA) in pediatric vascular injuries. All neck and extremity CTAs performed in pediatric patients at a level 1 trauma center were reviewed from 2001 to 2007. Overall, 78 patients were identified with an average age of 15.0 +/- 4.0 (0-18 years). Males outnumbered females 3.6:1. CTA was performed for 41 penetrating and 37 blunt traumas. Most penetrating injuries were due to missile wounds (71%) or stab wounds (17%). Eleven major vascular injuries resulted from penetrating trauma. For penetrating trauma, CTA was 100% sensitive and 93% specific. CTA for penetrating trauma had a positive predictive value (PPV) of 85% and negative predictive value (NPV) of 100%. Most blunt injuries were due to motor vehicle accidents (57%), followed by pedestrian hit by car (27%). Eight major vascular injuries resulted from blunt trauma. For blunt trauma, CTA was 88% sensitive and 100% specific. CTA for blunt trauma had a PPV of 100% and an NPV of 97%. The accuracy for penetrating and blunt trauma was 95% and 97%, respectively. CTA is highly sensitive, specific, and accurate for pediatric neck and extremity vascular trauma.

  14. Computer tomographic evaluation of talar edge configuration for osteochondral graft transplantation.

    PubMed

    Wiewiorski, Martin; Hoechel, Sebastian; Wishart, Katarina; Leumann, André; Müller-Gerbl, Magdalena; Valderrabano, Victor; Nowakowski, Andrej Maria

    2012-09-01

    To successfully surgically reconstruct osteochondral lesions of the talus, the exact three-dimensional (3D) configuration of the upper articular surface of the talus has to be respected. We assessed the talar geometry by measuring the coronal and sagittal talar edge radius and the frontal talar profile in multiplanar reconstructions of computer tomographic (CT) studies of 79 patients (83 feet) with a healthy ankle joint. An image visualization software designated for coordinate measurement was used to perform the measurement. In the coronal plane, the mean lateral talar edge radius was 4.0 mm and the medial 4.5 mm. In the sagittal planes the mean lateral talar edge radius was 20.3 mm, the radius of the sulcus 20.7 mm and the medial talar edge radius 20.4 mm. The talus showed a concave shape in coronal cuts. These results show a significant difference between medial and lateral talar edge configuration in coronal planes. The measurements of the lateral and medial sagittal radius and the mid-sagittal radius in the sulcus tali show no statistically significant difference. The depth of the talar sulcus shows no correlation to age or sex. Different sizes of custom-made tissue-engineered grafts according to the location of the osteochondral lesion at the talus are needed for exact surgical reconstruction of the anatomy. Osteochondral lesions are three dimensional; therefore, a 3D preoperative planning tool by CT scan or MRI is mandatory. Copyright © 2012 Wiley Periodicals, Inc.

  15. A Novel Colon Wall Flattening Model for Computed Tomographic Colonography: Method and Validation

    PubMed Central

    Wang, Huafeng; Chen, Yuexi; Li, Lihong; Pan, Haixia; Gu, Xianfeng

    2014-01-01

    Computed tomographic colonography (CTC) has been developed for screening of colon cancer. Flattening the three-dimensional (3D) colon wall into two-dimensional (2D) image is believed to (1) provide supplementary information to the endoscopic views and further (2) facilitate colon registration, taniae coli (TC) detection, and haustral fold segmentation. Though the previously-used conformal mapping-based flattening methods can preserve the angular geometry, they have the limitations in providing accurate information of the 3D inner colon wall due to the lack of undulating topography. In this paper, we present a novel colon-wall flattening method using a strategy of 2.5D approach. Coupling with the conformal flattening model, the presented new approach builds an elevation distance map to depict the neighborhood characteristics of the inner colon wall. We validated the new method via two CTC applications: TC detection and haustral fold segmentation. Experimental results demonstrated the effectiveness of our strategy for CTC studies. PMID:25642397

  16. Histologic and micro-computed tomographic analyses of replanted teeth stored in different kind of media.

    PubMed

    de Paula Reis, Manuella Verdinelli; Moura, Camilla Christian Gomes; Soares, Priscilla Barbosa Ferreira; Leoni, Graziela Bianchi; Souza-Neto, Manoel Damião; Barbosa, Darceny Zanetta; Soares, Carlos José

    2014-05-01

    Coconut water (CW) and soy milk (SM) have been proposed as storage media for avulsed teeth because of their nutrients that preserve cell viability. The present study investigated the periodontal healing process of dog teeth replanted after storage in CW, SM, and whole milk (WM) using micro-computed tomographic (μCT) and histologic analyses compared with immediate tooth replantation. Forty roots of 10 adult beagle dogs were extracted and subjected to the following protocols: immediate replantation after extraction (control), stored in CW with an adjusted pH, and SM and WM for 50 minutes before replantation. The animals were euthanized 28 days postoperatively, and the obtained specimens were scanned using a μCT scanner and subjected to routine processing for histometric analyses under an optical microscope. CW and SM performed similarly to WM; however, SM showed significantly higher ankylosis than the control group. Additionally, this study showed that the combined use of histologic analysis and μCT is a promising method to better identify tooth resorption and the repair process and to evaluate the total extension of the periodontium. CW as a storage medium is a promising transport media for avulsed teeth. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  17. Prophylactic appendectomy: unnecessary in children with incidental appendicoliths detected by computed tomographic scan.

    PubMed

    Rollins, Michael D; Andolsek, William; Scaife, Eric R; Meyers, Rebecka L; Duke, Tonya H; Lilyquist, Michael; Barnhart, Douglas C

    2010-12-01

    Controversy exists regarding the clinical significance of an isolated appendicolith on computed tomographic (CT) scan. We sought to determine the risk of developing appendicitis in children with an incidentally noted appendicolith. We retrospectively reviewed all pelvic CT scans in patients 18 years or younger at a tertiary care children's hospital from October 2005 to September 2008. Patients with an appendicolith and no radiographic evidence of acute appendicitis were selected for further review. Written questionnaire and telephone follow-up were attempted in all patients. Two thousand nine hundred thirteen pelvic CT scans were performed during the study period. The incidence of an isolated appendicolith during the study period was 2.6% (n = 75). Seven patients underwent appendectomy at initial presentation. Nine children underwent appendectomy subsequently: 3 electively and 6 at the time of return with abdominal pain. Only 6 of these 16 appendectomy specimens had histologic evidence of appendicitis, whereas only 3 demonstrated an appendicolith. Subsequent appendicitis developed in 5.8% (n = 4) of patients with an isolated appendicolith. Follow-up was achieved in 50% of patients who did not have an appendectomy (median, 2.8 years). Children with an incidental appendicolith are at low risk for developing appendicitis. The appendicoliths were often a transient finding not confirmed on surgical pathologic condition or subsequent imaging. Copyright © 2010 Elsevier Inc. All rights reserved.

  18. Hyperspectral Computed Tomographic Imaging Spectroscopy of Vascular Oxygen Gradients in the Rabbit Retina In Vivo

    PubMed Central

    Kashani, Amir H.; Kirkman, Erlinda; Martin, Gabriel; Humayun, Mark S.

    2011-01-01

    Diagnosis of retinal vascular diseases depends on ophthalmoscopic findings that most often occur after severe visual loss (as in vein occlusions) or chronic changes that are irreversible (as in diabetic retinopathy). Despite recent advances, diagnostic imaging currently reveals very little about the vascular function and local oxygen delivery. One potentially useful measure of vascular function is measurement of hemoglobin oxygen content. In this paper, we demonstrate a novel method of accurately, rapidly and easily measuring oxygen saturation within retinal vessels using in vivo imaging spectroscopy. This method uses a commercially available fundus camera coupled to two-dimensional diffracting optics that scatter the incident light onto a focal plane array in a calibrated pattern. Computed tomographic algorithms are used to reconstruct the diffracted spectral patterns into wavelength components of the original image. In this paper the spectral components of oxy- and deoxyhemoglobin are analyzed from the vessels within the image. Up to 76 spectral measurements can be made in only a few milliseconds and used to quantify the oxygen saturation within the retinal vessels over a 10–15 degree field. The method described here can acquire 10-fold more spectral data in much less time than conventional oximetry systems (while utilizing the commonly accepted fundus camera platform). Application of this method to animal models of retinal vascular disease and clinical subjects will provide useful and novel information about retinal vascular disease and physiology. PMID:21931729

  19. Utility of Computed Tomographic Enteroclysis/Enterography for the Assessment of Mucosal Healing in Crohn's Disease

    PubMed Central

    Hashimoto, Shinichi; Shimizu, Kensaku; Shibata, Hiroaki; Kanayama, Satoko; Tanabe, Ryo; Onoda, Hideko; Matsunaga, Naohumi; Sakaida, Isao

    2013-01-01

    Aim. When determining therapeutic strategy, it is important to diagnose small intestinal lesions in Crohn's disease (CD) precisely and to evaluate mucosal healing as well as clinical remission in CD. The purpose of this study was to compare findings from computed tomographic enteroclysis/enterography (CTE) with those from the mucosal surface and to determine whether the state of mucosal healing can be determined by CTE. Materials and Methods. Of the patients who underwent CTE for CD, 39 patients were examined whose mucosal findings could be confirmed by colonoscopy, capsule endoscopy, balloon endoscopy, or with the resected surgical specimens. Results. According to the CTE findings, patients were determined to be in the active CD group (n = 31) or inactive CD group (n = 8). The proportion of previous surgery, clinical remission, stenosis, and CDAI score all showed significant difference between groups. Mucosal findings showed an association with ulcer in 93.6% of active group patients but in only 12.5% of inactive group patients (P < 0.0001), whereas mucosal healing was found in 62.5% of inactive group patients but in only 3.2% of active group patients (P < 0.0001). Conclusion. CTE appeared to be a useful diagnostic method for assessment of mucosal healing in Crohn's disease. PMID:23710169

  20. Splanchnic vein thrombosis in necrotizing acute pancreatitis: Detection by computed tomographic venography

    PubMed Central

    Jiang, Wei; Zhou, Jing; Ke, Lu; Li, Gang; Tong, Zhi-Hui; Li, Wei-Qin; Li, Jie-Shou

    2014-01-01

    AIM: To assess the diagnostic accuracy of computed tomographic venography (CTV) for splanchnic vein thrombosis (SVT) detection in necrotizing acute pancreatitis (AP) patients. METHODS: Forty-three patients with necrotizing AP who underwent both CTV and digital subtraction angiography (DSA) within 3 d were analyzed in this retrospective comparative study. All CTV procedures were performed with a dual-source CT scanner. The presence and location of SVT were determined via blinded imaging data analyses. RESULTS: According to the DSA results, 17 (39.5%) of the total 43 patients had SVT. The sensitivity, specificity, positive and negative predictive values of CTV for SVT detection were 100% (95%CI: 77.1%-100%), 92.3% (95%CI: 73.4%-98.7%), 89.5% (95%CI: 65.5%-98.2%) and 100% (95%CI: 82.8%-100%), respectively. CONCLUSION: CTV is an effective examination for SVT detection in patients with necrotizing AP with high positive and negative predictive values. PMID:25469039

  1. Semiquantitative Computed Tomographic Characteristics for Lung Adenocarcinoma and Their Association with Lung Cancer Survival

    PubMed Central

    Wang, Hua; Schabath, Matthew B.; Liu, Ying; Berglund, Anders E.; Bloom, Gregory C.; Kim, Jongphil; Stringfield, Olya; Eikman, Edward A.; Klippenstein, Donald L.; Heine, John J.; Eschrich, Steven A.; Ye, Zhaoxiang; Gillies, Robert J.

    2015-01-01

    Background Computed tomographic (CT) characteristics derived from noninvasive images that represent the entire tumor may have diagnostic and prognostic value. The purpose of this study was to assess the association of a standardized set of semiquantitative CT characteristics of lung adenocarcinoma with overall survival. Patients and Methods An initial set of CT descriptors was developed to semiquantitatively assess lung adenocarcinoma in patients (n=117) who underwent resection. Survival analyses were used to determine the association between each characteristic and overall survival. Principle component analysis (PCA) was used to determine characteristics that may differentiate histological subtypes. Results Characteristics significantly associated with overall survival included pleural attachment (p < 0.001), air bronchogram (p = 0.03), and lymphadenopathy (p = 0.02). Multivariate analyses revealed pleural attachment was significantly associated with an increased risk of death overall (hazard ratio [HR] = 3.21; 95% confidence interval [CI] 1.53 – 6.70) and among patients with lepidic predominant adenocarcinomas (HR = 5.85; 95% CI 1.75 – 19.59), while lymphadenopathy was significantly associated with an increased risk of death among patients with adenocarcinomas without a predominant lepidic component (HR = 3.07; 95% CI 1.09 – 8.70). A PCA model showed that texture (ground-glass opacity component) was most important for separating the two subtypes. Conclusion A subset of the semiquantitative characteristics described herein has prognostic importance and ability to distinguish between different histological subtypes of lung adenocarcinoma. PMID:26077095

  2. Stereotactic interstitial brachytherapy of malignant astrocytomas with remarks on postimplantation computed tomographic appearance

    SciTech Connect

    Willis, B.K.; Heilbrun, M.P.; Sapozink, M.D.; McDonald, P.R.

    1988-09-01

    Seventeen patients were treated with stereotactically implanted high activity iodine-125 seeds, 12 patients for recurrent malignant astrocytomas (Protocol I) and 5 patients for newly diagnosed glioblastomas (Protocol II). Total radiation dosage to the recurrent tumors in Protocol I, including prior external beam irradiation, averaged 13,500 cGy. In the follow-up period of 6 to 50 months, the survival rate was 93% at 6 months, 60% at 12 months, 50% at 18 months, and 38% at 24 months after implantation. In Protocol II, brachytherapy was used as an interstitial radiation boost to the conventional treatment of newly diagnosed glioblastomas. External beam therapy and interstitial brachytherapy provided 11,000 cGy to these tumors. In the follow-up period of 15 to 27 months, there was a 100% survival at 12 months, 75% at 18 months, and 25% at 24 months after implantation. Eight of our 17 patients required reoperation for persistent or recurrent mass lesions at 6 to 15 months postimplantation; 7 were found to harbor masses of radionecrosis containing nests of anaplastic astrocytes; 1 had frank tumor recurrence. Median survival in this group of patients requiring reoperation was 18.7 months postimplantation. In a review of postimplantation computed tomographic scans, significant mass effect and crossover of hypodensity or enhancement into the corpus callosum or opposite hemisphere were found to have prognostic significance; persistent areas of contrast enhancement and excessive peritumoral hypodensity did not.

  3. Performance of computed tomographic colonography improved by total quality management techniques

    NASA Astrophysics Data System (ADS)

    Garry, John L.; Reed, Judd E.; Johnson, C. Daniel

    2000-04-01

    Our institution has been using an internally developed system for the analysis of Computed Tomographic Colonography (CTC) since 1994. This system has gone through several major revisions during that period. Careful application of 'total quality management' (TQM) principles have been utilized to enhance such aspects of performance as patient comfort, latency between examination and reporting of results, capability and reliability of 'picture archive system' (PACS) and network components, as well as reliability of results. CTC is now being practiced at our institution for clinical screening and research applications. To date, 1500 patients have been scanned. On an average day, six patients are scanned for research and/or clinical purposes. Research patient data remain on the CTC workstation for future analysis by the Radiologists while clinical patient data are analyzed as soon as the data have been received at the CTC workstation. An enlarged dynamic axial stack augmented by multiple interactive, off axis reformatted and perspective volume rendered endoluminal views have proven to be the most effective reading mode. Well over 1000 patient scans have been analyzed utilizing this specific protocol. When compared to corresponding patient BE and/or Colonoscopy procedures, CTC findings of potential cancers and polyps have compared very favorably.

  4. Normal morphometry of the thoracic aorta in the german shepherd dog: a computed tomographic study.

    PubMed

    Dabanoglu, I

    2007-06-01

    Computed tomographic images of the thoracic aorta of 14 German shepherd dogs were examined in order to determine the morphometry of the thoracic aorta. Examinations were carried out in the transverse plane at both intervertebral and mid-vertebral levels of each thoracic vertebra between T(5) and T(13). The dorsoventral and transversal diameters as well as cross-section area of the thoracic aorta were measured. The widest transversal diameter was observed at T(4-5), whereas the largest dorsoventral diameter was detected at T(5). The maximum cross-section area was detected at T(4-5). When dorsoventral and transversal diameters were compared between males and females, the aortic diameter was found to be smaller in males than in females. Although the shape of the thoracic aorta was transversal oval in the majority of the examined females, the shape of the thoracic aorta was dorsoventral oval in the majority of the males. There were significant differences between all levels measured for transversal (P < 0.001), dorsoventral (P < 0.001) diameters and cross-section area (P < 0.001) of the thoracic aorta. And there was a significant correlation between the three parameters examined. However, the correlation coefficient was highest in females.

  5. A novel colonic polyp volume segmentation method for computer tomographic colonography

    NASA Astrophysics Data System (ADS)

    Wang, Huafeng; Li, Lihong C.; Han, Hao; Song, Bowen; Peng, Hao; Wang, Yunhong; Wang, Lihua; Liang, Zhengrong

    2014-03-01

    Colorectal cancer is the third most common type of cancer. However, this disease can be prevented by detection and removal of precursor adenomatous polyps after the diagnosis given by experts on computer tomographic colonography (CTC). During CTC diagnosis, the radiologist looks for colon polyps and measures not only the size but also the malignancy. It is a common sense that to segment polyp volumes from their complicated growing environment is of much significance for accomplishing the CTC based early diagnosis task. Previously, the polyp volumes are mainly given from the manually or semi-automatically drawing by the radiologists. As a result, some deviations cannot be avoided since the polyps are usually small (6~9mm) and the radiologists' experience and knowledge are varying from one to another. In order to achieve automatic polyp segmentation carried out by the machine, we proposed a new method based on the colon decomposition strategy. We evaluated our algorithm on both phantom and patient data. Experimental results demonstrate our approach is capable of segment the small polyps from their complicated growing background.

  6. Quantitative evaluation of cervical cord compression by computed tomographic myelography in Thoroughbred foals

    PubMed Central

    YAMADA, Kazutaka; SATO, Fumio; HADA, Tetsuro; HORIUCHI, Noriyuki; IKEDA, Hiroki; NISHIHARA, Kahori; SASAKI, Naoki; KOBAYASHI, Yoshiyasu; NAMBO, Yasuo

    2016-01-01

    ABSTRACT Five Thoroughbred foals (age, 8–33 weeks; median age, 31 weeks; weight, 122–270 kg; median weight, 249 kg) exhibiting ataxia with suspected cervical myelopathy (n=4) and limb malformation (n=1) were subjected to computed tomographic (CT) myelography. The areas of the subarachnoid space and cervical cord were measured on transverse CT images. The area of the cervical cord was divided by the area of subarachnoid space, and stenosis ratios were quantitatively evaluated and compared on the basis of histopathological examination. The sites with a ratio above 52.8% could have been primary lesion sites in the histopathological examination, although one site with a ratio of 54.1% was not a primary lesion site. Therefore, in this study, a ratio between 52.8–54.1% was suggested to be borderline for physical compression that damages the cervical cord. All the cervical vertebrae could not be scanned in three of the five cases. Therefore, CT myelography is not a suitable method for locating the site of compression, but it should be used for quantitative evaluation of cervical stenosis diagnosed by conventional myelography. In conclusion, the stenosis ratios determined using CT myelography could be applicable for detecting primary lesion sites in the cervical cord. PMID:27974873

  7. Evaluation of radiographic, computed tomographic, and cadaveric anatomy of the head of boa constrictors.

    PubMed

    Banzato, Tommaso; Russo, Elisa; Di Toma, Anna; Palmisano, Giuseppe; Zotti, Alessandro

    2011-12-01

    To evaluate the radiographic, computed tomographic (CT), and cadaveric anatomy of the head of boa constrictors. 4 Boa constrictor imperator cadavers. Cadavers weighed 3.4 to 5.6 kg and had a body length ranging from 189 to 221 cm. Radiographic and CT images were obtained with a high-detail screen-film combination, and conventional CT was performed with a slice thickness of 1.5 mm. Radiographic images were obtained in ventrodorsal, dorsoventral, and left and right laterolateral recumbency; CT images were obtained with the animals positioned in ventral recumbency directly laying on a plastic support. At the end of the radiographic and CT imaging session, 2 heads were sectioned following a stratigraphic approach; the other 2, carefully maintained in the same position on the plastic support, were moved into a freezer (-20°C) until completely frozen and then sectioned into 3-mm slices, respecting the imaging protocol. The frozen sections were cleaned and then photographed on each side. Anatomic structures were identified and labeled on gross anatomic images and on the corresponding CT or radiographic image with the aid of available literature. Radiographic and CT images provided high detail for visualization of bony structures; soft tissues were not easily identified on radiographic and CT images. Results provide an atlas of stratigraphic and cross-sectional gross anatomy and radiographic and CT anatomy of the heads of boa constrictors that might be useful in the interpretation of any imaging modality in this species.

  8. Computed tomographic findings and treatment of a bull with pituitary gland abscess.

    PubMed

    Braun, Ueli; Malbon, Alexandra; Kochan, Manon; Riond, Barbara; Janett, Fredi; Iten, Cornelia; Dennler, Matthias

    2017-01-13

    In cattle, the prognosis of brain abscess is unfavourable and treatment is therefore not recommended. To the knowledge of the authors, there has been no report of successful treatment of a brain abscess in cattle.This report describes the clinical, computed tomographic and postmortem findings in a Holstein-Friesian bull with a hypophyseal abscess. The main clinical findings were generalised ataxia, ptyalism, prolapse of the tongue, dropped jaw, dysphagia, head tilt and unilateral ptosis. Cerebrospinal fluid evaluation revealed 2437 leukocytes/µl and severe pleocytosis. CT examination of the head showed a cavitary lesion consistent with an abscess in the hypophysis. Treatment consisted of gentamicin and flunixin meglumine for 3 days and amoxicillin for 40 days. The neurological signs resolved within 8 days of the start of treatment. The bull was slaughtered 11 months later because of infertility, and a postmortem examination was carried out. Histologically, a mild chronic non suppurative meningoencephalitis restricted to the ventral diencephalon was diagnosed. In addition, there was mild to moderate multifocal chronic lymphoplasmacytic hypophysitis with mild multifocal fibrosis. This case report stresses the significance of CT in confirming the clinical and laboratory diagnosis of central nervous system disorders in cattle and for localising brain lesions. Treatment of the brain abscess resulted, with respect to the central nervous disorder, in a successful outcome and was encouraging considering that most cases have an unfavourable prognosis.

  9. Trade-off between false positives and false negatives in the linkage analysis of complex traits.

    PubMed

    Todorov, A A; Rao, D C

    1997-01-01

    This study examines the issue of false positives in genomic scans for detecting complex trait loci using subpair linkage methods and investigates the trade-off between the rate of false positives and the rate of false negatives. It highlights the tremendous cost in terms of power brought about by an excessive control of type I error and, at the same time, confirms that a larger number of false positives can occur otherwise in the course of a genomic scan. Finally, it compares the power and rate of false positives obtained in preplanned replicated studies conducted using a liberal significance level to those for single-step studies that use the same total sample size but stricter levels of significance. For the models considered here, replicate studies were found more attractive as long as one is willing to accept a trade-off, exchanging a much lower rate of false negatives for a slight increase in the rate of false positives.

  10. Radiographic and computed tomographic demonstration of pseudotumor cerebri due to rapid weight gain in a child with pelvic rhabdomyosarcoma

    SciTech Connect

    Berdon, W.E.; Barker, D.H.; Barash, F.S.

    1982-06-01

    Rapid weight gain in a malnourished child can be associated with suture diastasis in the pattern of pseudotumor cerebri; this has been previously reported in deprivational dwarfism and cystic fibrosis. In a child with pelvic rhabdomyosarcoma, skull radiographs and cranial computed tomographic (CT) scans were available prior to a period of rapid weight gain induced by hyperalimentation. Suture diastasis developed and repeat CT scans showed this to be accompanied by smaller ventricles.

  11. Arterial Obstruction on Computed Tomographic or Magnetic Resonance Angiography and Response to Intravenous Thrombolytics in Ischemic Stroke

    PubMed Central

    Mair, Grant; von Kummer, Rüdiger; Adami, Alessandro; White, Philip M.; Adams, Matthew E.; Yan, Bernard; Demchuk, Andrew M.; Farrall, Andrew J.; Sellar, Robin J.; Sakka, Eleni; Palmer, Jeb; Perry, David; Lindley, Richard I.; Sandercock, Peter A.G.

    2017-01-01

    Background and Purpose— Computed tomographic angiography and magnetic resonance angiography are used increasingly to assess arterial patency in patients with ischemic stroke. We determined which baseline angiography features predict response to intravenous thrombolytics in ischemic stroke using randomized controlled trial data. Methods— We analyzed angiograms from the IST-3 (Third International Stroke Trial), an international, multicenter, prospective, randomized controlled trial of intravenous alteplase. Readers, masked to clinical, treatment, and outcome data, assessed prerandomization computed tomographic angiography and magnetic resonance angiography for presence, extent, location, and completeness of obstruction and collaterals. We compared angiography findings to 6-month functional outcome (Oxford Handicap Scale) and tested for interactions with alteplase, using ordinal regression in adjusted analyses. We also meta-analyzed all available angiography data from other randomized controlled trials of intravenous thrombolytics. Results— In IST-3, 300 patients had prerandomization angiography (computed tomographic angiography=271 and magnetic resonance angiography=29). On multivariable analysis, more extensive angiographic obstruction and poor collaterals independently predicted poor outcome (P<0.01). We identified no significant interaction between angiography findings and alteplase effect on Oxford Handicap Scale (P≥0.075) in IST-3. In meta-analysis (5 trials of alteplase or desmoteplase, including IST-3, n=591), there was a significantly increased benefit of thrombolytics on outcome (odds ratio>1 indicates benefit) in patients with (odds ratio, 2.07; 95% confidence interval, 1.18–3.64; P=0.011) versus without (odds ratio, 0.88; 95% confidence interval, 0.58–1.35; P=0.566) arterial obstruction (P for interaction 0.017). Conclusions— Intravenous thrombolytics provide benefit to stroke patients with computed tomographic angiography or magnetic

  12. Arterial Obstruction on Computed Tomographic or Magnetic Resonance Angiography and Response to Intravenous Thrombolytics in Ischemic Stroke.

    PubMed

    Mair, Grant; von Kummer, Rüdiger; Adami, Alessandro; White, Philip M; Adams, Matthew E; Yan, Bernard; Demchuk, Andrew M; Farrall, Andrew J; Sellar, Robin J; Sakka, Eleni; Palmer, Jeb; Perry, David; Lindley, Richard I; Sandercock, Peter A G; Wardlaw, Joanna M

    2017-02-01

    Computed tomographic angiography and magnetic resonance angiography are used increasingly to assess arterial patency in patients with ischemic stroke. We determined which baseline angiography features predict response to intravenous thrombolytics in ischemic stroke using randomized controlled trial data. We analyzed angiograms from the IST-3 (Third International Stroke Trial), an international, multicenter, prospective, randomized controlled trial of intravenous alteplase. Readers, masked to clinical, treatment, and outcome data, assessed prerandomization computed tomographic angiography and magnetic resonance angiography for presence, extent, location, and completeness of obstruction and collaterals. We compared angiography findings to 6-month functional outcome (Oxford Handicap Scale) and tested for interactions with alteplase, using ordinal regression in adjusted analyses. We also meta-analyzed all available angiography data from other randomized controlled trials of intravenous thrombolytics. In IST-3, 300 patients had prerandomization angiography (computed tomographic angiography=271 and magnetic resonance angiography=29). On multivariable analysis, more extensive angiographic obstruction and poor collaterals independently predicted poor outcome (P<0.01). We identified no significant interaction between angiography findings and alteplase effect on Oxford Handicap Scale (P≥0.075) in IST-3. In meta-analysis (5 trials of alteplase or desmoteplase, including IST-3, n=591), there was a significantly increased benefit of thrombolytics on outcome (odds ratio>1 indicates benefit) in patients with (odds ratio, 2.07; 95% confidence interval, 1.18-3.64; P=0.011) versus without (odds ratio, 0.88; 95% confidence interval, 0.58-1.35; P=0.566) arterial obstruction (P for interaction 0.017). Intravenous thrombolytics provide benefit to stroke patients with computed tomographic angiography or magnetic resonance angiography evidence of arterial obstruction, but the sample was

  13. Texture analysis of computed tomographic images in osteoporotic patients with sinus lift bone graft reconstruction.

    PubMed

    Marchand-Libouban, Hélène; Guillaume, Bernard; Bellaiche, Norbert; Chappard, Daniel

    2013-05-01

    Bone implants are now widely used to replace missing teeth. Bone grafting (sinus lift) is a very useful way to increase the bone volume of the maxilla in patients with bone atrophy. There is a 6- to 9-month delay for the receiver grafted site to heal before the implants can be placed. Computed tomography is a useful method to measure the amount of remaining bone before implantation and to evaluate the quality of the receiver bone at the end of the healing period. Texture analysis is a non-invasive method useful to characterize bone microarchitecture on X-ray images. Ten patients in which a sinus lift surgery was necessary before implantation were analyzed in the present study. All had a bone reconstruction with a combination of a biomaterial (beta tricalcium phosphate) and autograft bone harvested at the chin. Computed tomographic images were obtained before grafting (t0), at mid-interval (t1, 4.2 ± 0.7 months) and before implant placement (t2, 9.2 ± 0.6 months). Texture analysis was done with the run-length method. A significant increase of texture parameters at t1 reflected a gain of homogeneity due to the graft and the beginning of bone remodeling. At t2, some parameters remained high and corresponded to the persistence of bone trabeculae while the resorption of biomaterials was identified by other parameters which tended to return to pregraft values. Texture analysis identified changes during the healing of the receiver site. The method is known to correlate with microarchitectural changes in bone and could be a useful approach to characterized osseointegrated grafts.

  14. Radiographic, computed tomographic, and ultrasonographic findings with migrating intrathoracic grass awns in dogs and cats.

    PubMed

    Schultz, Ryan M; Zwingenberger, Allison

    2008-01-01

    The purpose of this study was to describe the clinical, radiographic, and computed tomographic findings in dogs and cats with migrating intrathoracic grass awns. Thirty-five dogs and five cats with visual confirmation of a grass awn following surgery, endoscopy or necropsy, and histology were assessed. The medical records and all diagnostic imaging studies were reviewed retrospectively. Labrador Retrievers or English Pointers < 5 years of age, with a history of coughing and hyperthermia, were the most common presentations. Seventeen animals had an inflammatory leukogram of which 14 had a left shift or toxic neutrophils. Radiographs were performed in 38 animals and computed tomography (CT) in 14. Thoracic radiographs were characterized by focal pulmonary interstitial to alveolar opacities (n = 26) that occurred most commonly in the caudal (n = 19) or accessory lobes (n = 8). Additional findings included pneumothorax (n = 9), pleural effusion (n = 8), and pleural thickening (n = 7). Pulmonary opacities identified on radiographs correlated to areas of pneumonia and foreign body location. CT findings included focal interstitial to alveolar pulmonary opacities (n = 12) most commonly in the right caudal lung lobe (n = 9), pleural thickening (n = 11), mildly enlarged intrathoracic lymph nodes (n = 10), soft tissue tracking (n = 7) with enhancing margins (n = 4), pneumothorax (n = 6), pleural effusion (n = 4), and foreign body visualization (n = 4). Histologic diagnoses included pulmonary and mediastinal granulomas or abscesses, bronchopneumonia, and pleuritis. Migrating intrathoracic grass awns should be considered as a differential diagnosis in coughing, febrile animals with focal interstitial to alveolar pulmonary opacities, pleural effusion, pleural thickening, and/or pneumothorax on radiographs or CT.

  15. Image display system for synchronous interpretaion of supine and prone computed tomographic colography

    NASA Astrophysics Data System (ADS)

    Reed, Judd E.; Johnson, C. Daniel

    1998-06-01

    Computed tomographic colography (CTC or virtual colonoscopy) is a new technique for imaging the colon for the detection of colorectal neoplasms. Early clinical assessment of this procedure has shown that the performance of this test is acceptable for colorectal screening examinations. The current version of CTC utilizes an interactive combination of axial, reformatted 2D and 3D images (from an endoluminal perspective) that are generated in real time. Retained fluid in the lumen of the colon is a commonly encountered problem that can obscure lesions. Prone imaging in addition to standard supine views are often required to visualize obscured colonic segments. Although the colorectum is often seen optimally with combined supine and prone views, twice as much interpretation time is required with both acquisitions. The purpose of this study is to describe a novel system of synchronous display of supine and prone images of the colon. Simultaneous display of synchronized (anatomically registered) views of the colon eliminates the need for two separate readings of the colon and shortens interpretation time. This tool has all of the features of the original CTC interpretation system (presented in 1995) and includes recent innovations such as virtual pathology which is present in another paper within this Proceeding. The anatomic levels are indexed to match each other and advanced synchronously as the radiologist interprets the data set. Axial, reformatted 2D and 3D images are displayed and simultaneously updated for both prone and supine images on the same computer screen. The colon only needs to be reviewed once with the diagnostic benefit of both scans. In many cases, the two scans can be interpreted nearly as quickly as one. Conclusion: Synchronous display of prone and supine images of the colon is a new enhancement for CTC that combines with advantages of prone and supine views without the added interpretations time of reviewing two separate scans.

  16. COMPUTED TOMOGRAPHIC ANATOMY AND CHARACTERISTICS OF RESPIRATORY ASPERGILLOSIS IN JUVENILE WHOOPING CRANES.

    PubMed

    Schwarz, Tobias; Kelley, Cristin; Pinkerton, Marie E; Hartup, Barry K

    2016-01-01

    Respiratory diseases are a leading cause of morbidity and mortality in captivity reared, endangered whooping cranes (Grus americana). Objectives of this retrospective, case series, cross-sectional study were to describe computed tomography (CT) respiratory anatomy in a juvenile whooping crane without respiratory disease, compare CT characteristics with gross pathologic characteristics in a group of juvenile whooping cranes with respiratory aspergillosis, and test associations between the number of CT tracheal bends and bird sex and age. A total of 10 juvenile whooping cranes (one control, nine affected) were included. Seven affected cranes had CT characteristics of unilateral extrapulmonary bronchial occlusion or wall thickening, and seven cranes had luminal occlusion of the intrapulmonary primary or secondary bronchi. Air sac membrane thickening was observed in three cranes in the cranial and caudal thoracic air sacs, and air sac diverticulum opacification was observed in four cranes. Necropsy lesions consisted of severe, subacute to chronic, focally extensive granulomatous pathology of the trachea, primary bronchi, lungs, or air sacs. No false positive CT scan results were documented. Seven instances of false negative CT scan results occurred; six of these consisted of subtle, mild air sacculitis including membrane opacification or thickening, or the presence of small plaques found at necropsy. The number of CT tracheal bends was associated with bird age but not sex. Findings supported the use of CT as a diagnostic test for avian species with respiratory disease and tracheal coiling or elongated tracheae where endoscopic evaluation is impractical. © 2015 The Authors. Veterinary Radiology & Ultrasound published by Wiley Periodicals, Inc. on behalf of American College of Veterinary Radiology.

  17. Statistical approaches to account for false-positive errors in environmental DNA samples.

    PubMed

    Lahoz-Monfort, José J; Guillera-Arroita, Gurutzeta; Tingley, Reid

    2016-05-01

    Environmental DNA (eDNA) sampling is prone to both false-positive and false-negative errors. We review statistical methods to account for such errors in the analysis of eDNA data and use simulations to compare the performance of different modelling approaches. Our simulations illustrate that even low false-positive rates can produce biased estimates of occupancy and detectability. We further show that removing or classifying single PCR detections in an ad hoc manner under the suspicion that such records represent false positives, as sometimes advocated in the eDNA literature, also results in biased estimation of occupancy, detectability and false-positive rates. We advocate alternative approaches to account for false-positive errors that rely on prior information, or the collection of ancillary detection data at a subset of sites using a sampling method that is not prone to false-positive errors. We illustrate the advantages of these approaches over ad hoc classifications of detections and provide practical advice and code for fitting these models in maximum likelihood and Bayesian frameworks. Given the severe bias induced by false-negative and false-positive errors, the methods presented here should be more routinely adopted in eDNA studies.

  18. Consequences of a false-positive mammography result: drug consumption before and after screening.

    PubMed

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

    2016-05-01

    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 of drug use for women with false-positive versus women with normal mammograms, before and after the event, using population-based registers, 1997-2006. The ratio of the ratios (RRR) assessed the impact. Results Before the test, 40.3% of women from the false-positive group versus 36.2% from the normal 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 mammograms already before the screening event, while the changes from before to after screening were similar for both groups. The results point to the importance of control for potential selection in studies of screening effects.

  19. Reducing false-negative and false-positive diagnoses in anatomic pathology consultation material.

    PubMed

    Renshaw, Andrew A; Gould, Edwin W

    2013-12-01

    Previous studies have shown that there are disagreements in interlaboratory consultation, including false-negative and false-positive diagnoses. To date, methods to reduce false-negative and false-positive diagnoses have been poorly documented. To identify features associated with false-negative and false-positive diagnoses in anatomic pathology. We reviewed the results of interlaboratory consultation in our institution during a 9-year period. For false-negative and false-positive diagnoses, methods that might have prevented the error were identified. Disagreements were identified in 810 of 8082 consults (10%). Fifty-four false-negative cases (0.7% of all consults) and 27 false-positive cases (0.3%) were identified. False-negative cases were more common in breast (20 of 1131; 1.8%), genitourinary (16 of 970; 1.7%), hematologic (3 of 242; 1.3%), and cytology (3 of 404; 0.8%) than in all other sites combined (P < .001); no significant difference in sites were identified for false-positive cases. Overall, there was no difference in the percentage of cases that were reviewed by more than one pathologist in either false-negative cases (109 of 810; 13.5%) or false-positive cases (135 of 810; 16.7%), compared with all other consults (858 of 7272; 11.8%) (P = .74 and .59, respectively). However, on review, 12 of all 27 false-positive cases (44%) might have been prevented by the use of immunohistochemistry alone, and 36 of all 54 false-negative cases (67%) might have been prevented by the use of a second review; special stains, including immunohistochemistry; additional levels; changes in processing; and hedges. Approximately one-half of false-negative and false-positive cases (48 of 81; 59%) might be preventable by the use of a combination of pathologic methods.

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

    PubMed

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

    2008-01-01

    There is an ongoing debate concerning possible disadvantages of mammography screening, one being the consequence of receiving a false positive test-result. It is argued that receiving a false positive answer may have short- and/or long-term adverse psychological effects on women, but results from different studies are conflicting. We tested if there was a difference in continued participation behaviour between the group of women who have been subject to a false positive result and those who have not. The study used the registers from the first six invitation rounds of the mammography screening programme in Copenhagen (1991-2003). We estimated the relative risk of not participating in the subsequent screening round for women with a false positive test using women with a negative test as baseline. As outcome measure odds ratios (OR) with 95% confidence intervals (CI) were used. There was no significant difference in participation in the subsequent round between women with a false positive test and women with a negative test. The proportion of screens resulting in false positive answers, both after assessment and after surgery, decreased from 5.54% in Round 1 to 1.79% in Round 5. Participation in the subsequent screening round was well above 80% in all five screening rounds. Our results showed that women experiencing a false positive test at mammography screening participated in the subsequent screening round to the same extent as did 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 of

  1. Computed Tomographic Perfusion Selection and Clinical Outcomes After Endovascular Therapy in Large Vessel Occlusion Stroke.

    PubMed

    Bouslama, Mehdi; Haussen, Diogo C; Grossberg, Jonathan A; Dehkharghani, Seena; Bowen, Meredith T; Rebello, Leticia C; Bianchi, Nicolas A; Frankel, Michael R; Nogueira, Raul G

    2017-05-01

    Different imaging paradigms have been used to select patients for endovascular therapy in stroke. We sought to determine whether computed tomographic perfusion (CTP) selection improves endovascular therapy outcomes compared with noncontrast computed tomography alone. Review of a prospectively collected registry of anterior circulation stroke patients undergoing stent-retriever thrombectomy at a tertiary care center between September 2010 and March 2016. Patients undergoing CTP were compared with those with noncontrast computed tomography alone. The primary outcome was the shift in the 90-day modified Rankin scale (mRS). A total of 602 patients were included. CTP-selected patients (n=365, 61%) were younger (P=0.02) and had fewer comorbidities. CTP selection (n=365, 61%) was associated with a favorable 90-day mRS shift (adjusted odds ratio [aOR]=1.49; 95% confidence interval [CI], 1.06-2.09; P=0.02), higher rates of good outcomes (90-day mRS score 0-2: 52.9% versus 40.4%; P=0.005), modified Thrombolysis in Cerebral Infarction-3 reperfusion (54.8% versus 40.1%; P<0.001), smaller final infarct volumes (24.7 mL [9.8-63.1 mL] versus 34.6 mL [13.1-88 mL]; P=0.017), and lower mortality (16.6% versus 26.8%; P=0.005). When matched on age, National Institutes of Health Stroke Scale (NIHSS) score, and glucose (n=424), CTP remained associated with a favorable 90-day mRS shift (P=0.016), lower mortality (P=0.02), and higher rates of reperfusion (P<0.001). CTP better predicted functional outcomes in patients presenting after 6 hours (as assessed by comparison of logistic regression models: Akaike information criterion: 199.35 versus 287.49 and Bayesian information criterion: 196.71 versus 283.27) and those with an Alberta Stroke Program Early Computed Tomography Score ≤7 (Akaike information criterion: 216.69 versus 334.96 and Bayesian information criterion: 213.6 versus 329.94). CTP selection is associated with a favorable mRS shift in patients undergoing stent

  2. Computed 3D visualisation of an extinct cephalopod using computer tomographs

    PubMed Central

    Lukeneder, Alexander

    2012-01-01

    The first 3D visualisation of a heteromorph cephalopod species from the Southern Alps (Dolomites, northern Italy) is presented. Computed tomography, palaeontological data and 3D reconstructions were included in the production of a movie, which shows a life reconstruction of the extinct organism. This detailed reconstruction is according to the current knowledge of the shape and mode of life as well as habitat of this animal. The results are based on the most complete shell known thus far of the genus Dissimilites. Object-based combined analyses from computed tomography and various computed 3D facility programmes help to understand morphological details as well as their ontogentical changes in fossil material. In this study, an additional goal was to show changes in locomotion during different ontogenetic phases of such fossil, marine shell-bearing animals (ammonoids). Hence, the presented models and tools can serve as starting points for discussions on morphology and locomotion of extinct cephalopods in general, and of the genus Dissimilites in particular. The heteromorph ammonoid genus Dissimilites is interpreted here as an active swimmer of the Tethyan Ocean. This study portrays non-destructive methods of 3D visualisation applied on palaeontological material, starting with computed tomography resulting in animated, high-quality video clips. The here presented 3D geometrical models and animation, which are based on palaeontological material, demonstrate the wide range of applications, analytical techniques and also outline possible limitations of 3D models in earth sciences and palaeontology. The realistic 3D models and motion pictures can easily be shared amongst palaeontologists. Data, images and short clips can be discussed online and, if necessary, adapted in morphological details and motion-style to better represent the cephalopod animal. PMID:24850976

  3. Computed 3D visualisation of an extinct cephalopod using computer tomographs

    NASA Astrophysics Data System (ADS)

    Lukeneder, Alexander

    2012-08-01

    The first 3D visualisation of a heteromorph cephalopod species from the Southern Alps (Dolomites, northern Italy) is presented. Computed tomography, palaeontological data and 3D reconstructions were included in the production of a movie, which shows a life reconstruction of the extinct organism. This detailed reconstruction is according to the current knowledge of the shape and mode of life as well as habitat of this animal. The results are based on the most complete shell known thus far of the genus Dissimilites. Object-based combined analyses from computed tomography and various computed 3D facility programmes help to understand morphological details as well as their ontogentical changes in fossil material. In this study, an additional goal was to show changes in locomotion during different ontogenetic phases of such fossil, marine shell-bearing animals (ammonoids). Hence, the presented models and tools can serve as starting points for discussions on morphology and locomotion of extinct cephalopods in general, and of the genus Dissimilites in particular. The heteromorph ammonoid genus Dissimilites is interpreted here as an active swimmer of the Tethyan Ocean. This study portrays non-destructive methods of 3D visualisation applied on palaeontological material, starting with computed tomography resulting in animated, high-quality video clips. The here presented 3D geometrical models and animation, which are based on palaeontological material, demonstrate the wide range of applications, analytical techniques and also outline possible limitations of 3D models in earth sciences and palaeontology. The realistic 3D models and motion pictures can easily be shared amongst palaeontologists. Data, images and short clips can be discussed online and, if necessary, adapted in morphological details and motion-style to better represent the cephalopod animal.

  4. Association between renal dysfunction and the mixed plaque of coronary artery on computed tomographic angiography.

    PubMed

    Sung, Jiyoon; Chang, Jae Hyun; Chung, Wook-Jin; Jung, Ji Yong; Na, Sun Young; Lee, Hyun Hee; Sung, Yon Mi; Moon, Chan Il; Hwang, Young-Hwan; Chung, Wookyung; Kim, Sejoong

    2011-01-01

    Coronary artery plaque is related to development of coronary artery disease (CAD), and chronic kidney disease is associated with CAD. However, the association of renal dysfunction (RD) with coronary artery plaque characteristics has not been fully elucidated. We evaluated the association between RD and coronary artery plaque characteristics in patients with suspected CAD, who underwent multislice computed tomographic angiography (CTA). A total of 918 patients were classified into 4 groups: group with no plaque (NP) (48.9%), group with calcified plaque (CP) (16.0%), group with noncalcified plaque (NCP) (22.4%), and group with mixed plaque (MP) (12.7%). NCP is considered as rupture-prone soft plaque, and CP as more stable lesion. The mean of estimated glomerular filtration rate (eGFR) was 82.5 ± 15.4 mL/min/1.73 m(2), and the prevalence of RD (defined as eGFR < 60 mL/min/1.73 m(2)) was 6.3%. The prevalence of RD was 3.3% in the NP group, 10.2% in the CP group, 5.3% in the NCP group, and 14.5% in the MP group (P < 0.001 by ANOVA tests). The adjusted odds ratio for RD was 3.38 (95% confidence interval, 1.27-9.04) for the MP group, compared with the NP group. The presence of RD showed an independent association with the MP counts (r = 0.155, P < 0.001); however, there was no association between RD and other plaque characteristics. In conclusion, RD is associated with MP rather than CP or NCP, compared with NP, which may reflect one of the developmental processes of CAD in patients with RD.

  5. Identification of the distinguishing features of Crohn's disease and ischemic colitis using computed tomographic enterography.

    PubMed

    Chen, Min; Remer, Erick M; Liu, Xiuli; Lopez, Rocio; Shen, Bo

    2017-08-01

    Background and aims: The differential diagnosis between Crohn's disease (CD) and ischemic colitis (ISC) is important as their clinical management is different. ISC can easily be misdiagnosed as CD, especially in elderly populations. The distinctive radiographic features of the two disease entities have not been investigated. The aim of this study is to assess the utility of computed tomographic enterography (CTE) in the differential diagnosis between CD and ISC. Methods: Patients with confirmed CD and ISC were identified through an electronic medical record search of the Cleveland Clinic Foundation. Patients who had undergone CTE, with or without concurrent colonoscopy and histopathological specimens, were included in this study. CTE images were blindly re-reviewed by an expert gastrointestinal radiologist. The sensitivities, specificities, accuracies and positive and negative predictive values for each of the CTE findings in differentiating CD from ISC were estimated. Kappa coefficients (κ) were calculated to measure diagnosis agreement between CTE and the reference standard. Results: A total of 34 eligible patients were included in this study with 17 having CD and 17 having ISC. In differentiating CD from ISC, the presence of mucosal hyperenhancement and absence of the "target sign" on CTE showed a sensitivity of 100% each for CD, while the two radiographic features yielded a low specificity of 35.3% and 76.5%, respectively. The presence of stricture had a lower sensitivity of 64.7% for the detection of CD but had a high specificity of 100%. In distinguishing CD from ISC, the accuracy of presence of mucosal hyperenhancement, stricture and absence of target sign were 67.7%, 82.4% and 88.2%, respectively. The combination of the presence of mucosal hyperenhancement and the absence of the target sign achieved an accuracy of 100% for distinguishing CD from ISC. There was a good correlation between CTE and the reference standard for distinguishing CD from ISC (κ

  6. Micro-computed Tomographic Analysis of Mandibular Second Molars with C-shaped Root Canals.

    PubMed

    Amoroso-Silva, Pablo Andrés; Ordinola-Zapata, Ronald; Duarte, Marco Antonio Hungaro; Gutmann, James L; del Carpio-Perochena, Aldo; Bramante, Clovis Monteiro; de Moraes, Ivaldo Gomes

    2015-06-01

    The goal of the present study was to evaluate the morphometric aspects of the internal anatomy of the root canal system of mandibular second molars with C-shaped canals. Fifty-two extracted second mandibular molars with C-shaped canals, fused roots, and radicular grooves were selected from a Brazilian population. The samples were scanned with a micro-computed tomographic scanner at a voxel size of 19.6 μm. The root canal cross sections were recorded as C1, C2, C3, and C4 root canal configurations according to the modified Melton classification. Morphometric parameters, including the major and minor diameters of the root canals, the aspect ratio, the roundness, and the tridimensional configuration (merging, symmetric, and asymmetric), were evaluated. The 3-dimensional reconstruction images of the teeth indicated an even distribution within the sample. The analysis of the prevalence of the different cross-sectional configurations of the C-shaped molars revealed that these were predominantly of the C4 and C3 configurations (1 mm from the apex) and the C1 and C2 configurations in the cervical third. According to the morphometric parameters, the C1 and the distal aspect of the C2 configurations exhibited the lowest roundness values and higher values for the area, major diameter, and aspect ratio in the apical third. Mandibular molars with C-shaped root canals exhibited similar distributions of symmetric, asymmetric, and merging type canals. The C1 configuration and the distal aspect of the C2 configuration exhibited the highest area values, low roundness values, and large apical diameters. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  7. Coronary computed tomographic angiographic findings in asymptomatic patients with type 2 diabetes mellitus.

    PubMed

    Park, Gyung-Min; Lee, Seung-Whan; Cho, Young-Rak; Kim, Chan Joon; Cho, Jung Sun; Park, Mahn-Won; Her, Sung Ho; Ahn, Jung-Min; Lee, Jong-Young; Park, Duk-Woo; Kang, Soo-Jin; Kim, Young-Hak; Lee, Cheol Whan; Koh, Eun Hee; Lee, Woo Je; Kim, Min-Seon; Lee, Ki-Up; Kang, Joon-Won; Lim, Tae-Hwan; Park, Seong-Wook; Park, Seung-Jung; Park, Joong-Yeol

    2014-03-01

    There are limited data regarding the role of coronary computed tomographic angiography (CCTA) in asymptomatic patients with type 2 diabetes mellitus. We analyzed 557 asymptomatic type 2 diabetic patients who underwent CCTA. Cardiac event was defined as a composite of cardiac death, nonfatal myocardial infarction, acute coronary syndrome requiring hospitalization, or late revascularization. Atherosclerotic plaques were observed in 395 patients (70.9%), and 170 patients (30.5%) showed significant coronary artery disease (CAD) on CCTA. Ninety-two patients (16.5%) were associated with a significant stenosis in the left main or proximal left anterior descending artery. During the follow-up period (33.7 ± 7.8 months), although an excellent prognosis was observed in patients without significant CAD on CCTA, those with significant CAD showed more cardiac events (7.1% vs 0.5%) and lower 3-year event-free survival rates (99.2 ± 0.6% vs 90.9 ± 2.6%, p <0.001). Furthermore, in group with significant CAD, patients with significant CAD in the left main or proximal left anterior descending artery had more cardiac events (10.9% vs 2.6%) and lower 3-year event-free survival rates (97.4 ± 1.8% vs 86.1 ± 4.2%, p = 0.049). On multivariate analysis, family history of premature CAD, previous history of stroke, higher UK Prospective Diabetes Study 10-year risk scores, neuropathy, and retinopathy were independent clinical predictors of having significant CAD and left main or proximal left anterior descending artery significant CAD on CCTA. In conclusion, about 1/3 of asymptomatic type 2 diabetic patients had significant CAD on CCTA with a subsequent high risk for cardiac events. These findings suggest that CCTA may have a potential role in identifying patients with high cardiovascular risks in asymptomatic type 2 diabetes.

  8. Saddle Pulmonary Embolism: Laboratory and Computed Tomographic Pulmonary Angiographic Findings to Predict Short-term Mortality.

    PubMed

    Liu, Min; Miao, Ran; Guo, Xiaojuan; Zhu, Li; Zhang, Hongxia; Hou, Qing; Guo, Youmin; Yang, Yuanhua

    2017-02-01

    Saddle pulmonary embolism (SPE) is rare type of acute pulmonary embolism and there is debate about its treatment and prognosis. Our aim is to assess laboratory and computed tomographic pulmonary angiographic (CTPA) findings to predict short-term mortality in patients with SPE. This was a five-centre, retrospective study. The clinical information, laboratory and CTPA findings of 88 consecutive patients with SPE were collected. One-month mortality after diagnosis of SPE was the primary end-point. The correlation of laboratory and CTPA findings with one-month mortality was analysed with area under curve (AUC) of receiver operating characteristic (ROC) curves and logistic regression analysis. Eighteen patients with SPE died within one month. Receiver operating characteristic curves revealed that the cutoff values for the right and left atrial diameter ratio, the right ventricular area and left ventricular area ratio (RVa/LVa ratio), Mastora score, septal angle, N-terminal pro-brain natriuretic peptide and cardiac troponin I (cTnI) for detecting early mortality were 2.15, 2.13, 69%, 57°, 3036 pg/mL and 0.18ng/mL, respectively. Using logistic regression analysis of laboratory and CTPA findings with regard to one-month mortality of SPE, RVa/LVa ratio and cTnI were shown to be independently associated with early death. A combination of cTnI and RVa/LVa ratio revealed an increase in the AUC value, but the difference did not reach significance compared with RVa/LVa or cTnI, alone (P>0.05). In patients with SPE, both the RVa/LVa ratio on CTPA and cTnI appear valuable for the prediction of short-term mortality. Copyright © 2016 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

  9. Computed tomographic and radiographic examination of dental structures in South American camelid specimen of different ages

    PubMed Central

    2014-01-01

    Background Tooth root problems and periodontal diseases are common in South American camelids (SAC). The objective was to evaluate and optimize the imaging technique for dental radiography in SAC and to describe the radiographic and computed tomographic (CT) anatomy of normal teeth at different ages. In this study, the heads of 20 healthy SAC slaughtered for meat production or euthanized for reasons not related to dental problems included 7 female and 10 male llamas and 3 male alpacas. Using a standardized protocol, radiographs and CT scans of the 20 specimen were performed. Results The most useful radiographic projections for mandibular and maxillary cheek teeth evaluation turned out to be lateral30°ventral - laterodorsal and lateral30°dorsal - lateroventral with slight separation of the dental arcades respectively. Digital radiographic and CT appearance of the mandibular and maxillary teeth were described from the beginning of mineralization till maturity. In addition the normal range of the CT radio density of different cheek teeth and different dental tissues were measured. Hounsfield units of different dental tissues of SAC turned out to be similar to equids. Deviation, shortening and partial destruction of the distal tooth root of mandibular 09′s and 10′s and of maxillary 09′s was observed and the existence of a common pulp chamber in younger teeth was revealed. Conclusions The present study provides information about the dental imaging morphology in clinically healthy SAC. This basic information provides fundamental knowledge for evaluating images and planning treatments in clinically affected animals. PMID:24393365

  10. A Cone-Beam Computed Tomographic Study on Mandibular First Molars in a Chinese Subpopulation

    PubMed Central

    Ma, Yue; Han, Ting; Chen, Xinyu; Wan, Fang; Lu, Yating; Yan, Songhe; Wang, Yan

    2015-01-01

    The purpose of this study was to conduct a cone-beam computed tomographic (CBCT) investigation on the root and canal configuration of the mandibular first molars, especially the morphology of the disto-lingual (DL) root, in a Chinese subpopulation. A total of 910 CBCT images of the mandibular first molars were collected from 455 patients who underwent CBCT examinations as a preoperative assessment for implants or orthodontic treatment. The following information was analyzed and evaluated: tooth position, gender, root and root canal number per tooth, root canal type of the mesial root(s) and distal root(s), angle of the DL root canal curvature, distance between two distal canal orifices in the teeth with DL root, and angle of disto-buccal canal orifice–disto-lingual canal orifice–mesio-lingual canal orifice (DB-DL-ML). Most of the mandibular first molars (64.9%, n = 591) had two roots with three root canals, and most of the mesial root canals (87.7%, n = 798) were type VI. The prevalence of the DL root was 22.1% (n = 201). The right side had a higher prevalence of DL root than the left side (p<0.05). Additionally, the curvature of the DL root canal were greater in the bucco-lingual (BL) orientation (30.10°±14.02°) than in the mesio-distal (MD) orientation (14.03°± 8.56°) (p<0.05). Overall there was a high prevalence of DL root in the mandibular first molars, and most of the DL roots were curved in different degrees. This study provided detailed information about the root canal morphology of the mandibular first molars in a Chinese subpopulation. PMID:26241480

  11. Computed tomographic angiography as a useful adjunct in the diagnosis of brain death.

    PubMed

    Welschehold, Stefan; Kerz, Thomas; Boor, Stephan; Reuland, Katharina; Thömke, Frank; Reuland, Andre; Beyer, Christian; Tschan, Christoph; Wagner, Wolfgang; Müller-Forell, Wibke; Giese, Alf

    2013-05-01

    Because of its widespread accessibly, computed tomographic angiography (CT-A) is a promising technique in the detection of intracranial circulatory arrest in brain death (BD). Several studies assessed this tool, but neither have standardized evaluation parameters been developed nor has information about specificity become available. We conducted a prospective study between January 2008 and April 2012. Thirty patients were admitted to our University Hospital (16 men and 14 women; age, 18-88 years) and underwent CT-A scanning at two occasions: immediately after the first signs of loss of brain stem reflexes and after definitive determination of brain. The results of CT-A were compared with transcranial Doppler ultrasonography and electroencephalogram. In 3 of 30 patients, we observed a termination of contrast flow at the level of the skull base and foramen magnum in arterial scanning series before the clinical determination of BD. After the clinical determination of BD, the opacification of all vascular territories in arterial phase scanning was found in one case, but venous phase scanning revealed no blood return in internal cerebral veins. In all other cases, contrast filling ceased at level of skull base or below. The specificity of CT-A in the detection of intracranial circulatory arrest was 90%, and sensitivity was 97%. CT-A is reliable and appropriate technical investigation to detect intracranial circulatory arrest in BD. The evaluation of contrast enhancement in arterial phase scanning seems to be more reliable than that in venous phase. An international consensus about a uniformly applied CT-A protocol for the evaluation of BD should be established.

  12. Volumetric Planning Using Computed Tomographic Angiography Improves Clinical Outcomes in DIEP Flap Breast Reconstruction.

    PubMed

    Lee, Kyeong-Tae; Mun, Goo-Hyun

    2016-05-01

    The present study evaluated outcomes of deep inferior epigastric perforator (DIEP) flap breast reconstruction using volumetric planning-which is preoperative planning based on volumetric data of the breast and flap estimated from computed tomographic angiography. A prospective review of three patient cohorts undergoing DIEP flap breast reconstruction from June of 2009 to February of 2015 was performed. Cohort 1 comprised 48 cases in which no volumetric planning was used. Cohort 2 included the next 101 consecutive cases undergoing breast reconstruction according to an algorithm based on volumetric planning. Cohort 3 consisted of the next 109 consecutive cases using a modified algorithm. The inset rate (weight ratio of the inset flap to harvested flap) was estimated during volumetric planning, and specific surgical strategies, such as incorporating multiple perforators, conducting venous augmentation (cohort 2), or harvesting bipedicled flaps (cohort 3), were used with reference to it. Rates of perfusion-related complications were compared. All but one flap survived completely. Fat necrosis occurred in 9.7 percent. Overall, the perfusion-related complication rate was 22.9 percent of cohort 1, 10.9 percent in cohort 2, and 5.6 percent in cohort 3 (p = 0.006). The fat necrosis rates were 19.1, 9.9, and 5.6 percent in cohorts 1, 2, and 3, respectively (p = 0.032). A multivariate analysis demonstrated that volumetric planning had independent benefits for preventing perfusion-related complications (p = 0.003). The authors' results suggest that volumetric planning can facilitate elaborate planning and reduce perfusion-related complications, enabling reliable breast reconstruction using DIEP flaps. Therapeutic, III.

  13. Pulmonary Leptospirosis With Diffuse Alveolar Hemorrhage: High-Resolution Computed Tomographic Findings in 16 Patients.

    PubMed

    von Ranke, Felipe Mussi; Zanetti, Gláucia; Escuissato, Dante Luiz; Hochhegger, Bruno; Marchiori, Edson

    2016-01-01

    The aim of this study was to evaluate the high-resolution computed tomographic (HRCT) findings from patients with leptospirosis and diffuse alveolar hemorrhage (DAH). We retrospectively reviewed HRCT findings from 16 patients diagnosed as having leptospirosis causing DAH. The patient sample was composed of 13 men and 3 women aged 22 to 53 years (mean age, 34.5 years). Diagnosis was established with confirmation of leptospirosis infection by serologic microagglutination test. Histopathological study was performed in 8 patients. Two chest radiologists analyzed the HRCT images and reached decisions by consensus. The predominant HRCT findings were ground-glass opacities and airspace nodules (both n = 12, 75%), ground-glass nodules (n = 9, 56.25%), consolidations (n = 7, 43.75%), "crazy-paving" pattern (n = 3, 18.75%), and interlobular septal thickening without ground-glass opacity (n = 3, 18.75%). Bilateral pleural effusion was an associated finding in 2 (12.5%) patients. Analysis of the axial distribution of the lesions revealed diffuse distribution in 11 (68.75%) patients and peripheral lung zone predominance in 5 (31.25%) patients. Abnormalities were bilateral in all 16 (100%) patients. Analysis of the craniocaudal distribution of the lesions revealed lower zone predominance in 9 (56.25%) patients, diffuse distribution in 5 (31.25%) patients, middle zone predominance in 1 (6.25%) patient, and upper zone predominance in 1 (6.25%) patient. The most frequent HRCT findings in patients with leptospirosis causing DAH were ground-glass opacities, airspace nodules, ground-glass nodules, and consolidations. The lesions showed symmetrical distribution with lower zone predominance in most cases.

  14. Computed tomographic colonography without cathartic preparation for the detection of colorectal polyps.

    PubMed

    Iannaccone, Riccardo; Laghi, Andrea; Catalano, Carlo; Mangiapane, Filippo; Lamazza, Antonietta; Schillaci, Alberto; Sinibaldi, Giovanni; Murakami, Takamichi; Sammartino, Paolo; Hori, Masatoshi; Piacentini, Francesca; Nofroni, Italo; Stipa, Vincenzo; Passariello, Roberto

    2004-11-01

    We prospectively compared the performance of low-dose multidetector computed tomographic colonography (CTC) without cathartic preparation with that of colonoscopy for the detection of colorectal polyps. A total of 203 patients underwent low-dose CTC without cathartic preparation followed by colonoscopy. Before CTC, fecal tagging was achieved by adding diatrizoate meglumine and diatrizoate sodium to regular meals. No subtraction of tagged feces was performed. Colonoscopy was performed 3-7 days after CTC. Three readers interpreted the CTC examinations separately and independently using a primary 2-dimensional approach using multiplanar reconstructions and 3-dimensional images for further characterization. Colonoscopy with segmental unblinding was used as reference standard. The sensitivity of CTC was calculated both on a per-polyp and a per-patient basis. For the latter, specificity, positive predictive values, and negative predictive values were also calculated. CTC had an average sensitivity of 95.5% (95% confidence interval [CI], 92.1%-99%) for the identification of colorectal polyps > or =8 mm. With regard to per-patient analysis, CTC yielded an average sensitivity of 89.9% (95% CI, 86%-93.7%), an average specificity of 92.2% (95% CI, 89.5%-94.9%), an average positive predictive value of 88% (95% CI, 83.3%-91.5%), and an average negative predictive value of 93.5% (95% CI, 90.9%-96%). Interobserver agreement was high on a per-polyp basis (kappa statistic range, .61-.74) and high to excellent on a per-patient basis (kappa statistic range, .79-.91). Low-dose multidetector CTC without cathartic preparation compares favorably with colonoscopy for the detection of colorectal polyps.

  15. Radiation dose to patients and image quality evaluation from coronary 256-slice computed tomographic angiography

    NASA Astrophysics Data System (ADS)

    Chen, Liang-Kuang; Wu, Tung-Hsin; Yang, Ching-Ching; Tsai, Chia-Jung; Lee, Jason J. S.

    2010-07-01

    The aim of this study is to assess radiation dose and the corresponding image quality from suggested CT protocols which depends on different mean heart rate and high heart rate variability by using 256-slice CT. Fifty consecutive patients referred for a cardiac CT examination were included in this study. All coronary computed tomographic angiography (CCTA) examinations were performed on a 256-slice CT scanner with one of five different protocols: retrospective ECG-gating (RGH) with full dose exposure in all R-R intervals (protocol A), RGH of 30-80% pulsing window with tube current modulation (B), RGH of 78±5% pulsing window with tube current modulation (C), prospective ECG-triggering (PGT) of 78% R-R interval with 5% padding window (D) and PGT of 78% R-R interval without padding window (E). Radiation dose parameters and image quality scoring were determined and compared. In this study, no significant differences were found in comparison on image quality of the five different protocols. Protocol A obtained the highest radiation dose comparing with those of protocols B, C, D and E by a factor of 1.6, 2.4, 2.5 and 4.3, respectively ( p<0.001), which were ranged between 2.7 and 11.8 mSv. The PGT could significantly reduce radiation dose delivered to patients, as compared to the RGH. However, the use of PGT has limitations and is only good in assessing cases with lower mean heart rate and stable heart rate variability. With higher mean heart rate and high heart rate variability circumstances, the RGH within 30-80% of R-R interval pulsing window is suggested as a feasible technique for assessing diagnostic performance.

  16. Evaluation of contraindications and efficacy of oral Beta blockade before computed tomographic coronary angiography.

    PubMed

    de Graaf, Fleur R; Schuijf, Joanne D; van Velzen, Joëlla E; Kroft, Lucia J; de Roos, Albert; Sieders, Allard; Jukema, J Wouter; Schalij, Martin J; van der Wall, Ernst E; Bax, Jeroen J

    2010-03-15

    Multidetector computed tomographic coronary angiography (CTA) image quality is inversely related to the heart rate (HR). As a result beta-blocking medication is routinely administered before investigation. In the present study, the use, contraindications, and efficacy of prescan beta blockade with regard to HR reduction and CTA image quality were assessed. In 537 patients referred for CTA, the baseline HR and blood pressure were measured on arrival, and contraindications for beta blockade were noted. Unless contraindicated, a single dose of metoprolol was administered orally 1 hour before data acquisition in patients with a HR of > or =65 beats/min according to a predefined medication protocol. After 1 hour, the HR was remeasured. A total of 283 patients (53%) had a HR of > or =65 beats/min. In this group, beta blockade was contraindicated in 46 patients (16%). Metoprolol was administered to the remaining 237 patients. However, 26 patients (11%) received suboptimal (lower dose than prescribed by protocol) beta blockade because of contraindications. Of the 211 patients receiving optimal beta blockade, 57 (27%) did not achieve the target HR. Of the patients with contraindications to beta blockade, 43 (60%) did not achieve the target HR. Compared to patients with optimal HR control, those receiving no or suboptimal beta blockade because of contraindications had significantly fewer examinations of good image quality (40% vs 74%, p <0.001), and significantly more examinations of poor image quality (20% vs 6%, p <0.001). In conclusion, most patients require HR reduction before CTA. Contraindications to beta blockade are present in a substantial proportion of patients. This results in suboptimal HR control and image quality, indicating the need for alternative approaches for HR reduction.

  17. Terminal digit preference biases polyp size measurements at endoscopy, computed tomographic colonography, and histopathology.

    PubMed

    Plumb, Andrew A; Nickerson, Claire; Wooldrage, Katherine; Bassett, Paul; Taylor, Stuart A; Altman, Douglas; Atkin, Wendy; Halligan, Steve

    2016-10-01

    Terminal digit preference bias for "pleasing" numbers has been described in many areas of medicine. The aim of this study was to determine whether endoscopists, radiologists, and pathologists exhibit such bias when measuring colorectal polyp diameters. Colorectal polyp diameters measured at endoscopy, computed tomographic colonography (CTC), and histopathology were collated from a colorectal cancer screening program and two parallel multicenter randomized trials. Smoothing models were fitted to the data to estimate the expected number of polyps at 1-mm increments, assuming no systematic measurement bias. The difference between the expected and observed numbers of polyps was calculated for each terminal digit using statistical modeling. The impact of measurement bias on per-patient detection rates of polyps ≥ 10 mm was estimated for each modality. A total of 92 124 individual polyps were measured by endoscopy (91 670 screening and 454 from trials), 2385 polyps were measured by CTC (1664 screening, 721 trials), and 79 272 were measured by histopathology (78 783 screening, 489 trials). Clustering of polyp diameter measurements at 5-mm intervals was demonstrated for all modalities, both in the screening program and the trials. The statistical models estimated that per-patient detection rates of polyps ≥ 10 mm were over-inflated by 2.4 % for endoscopy, 3.1 % for CTC, and 3.3 % for histopathology in the screening program, with similar trends in the randomized trials. Endoscopists, radiologists, and pathologists all exhibit terminal digit preference when measuring colorectal polyps. This will bias trial data, referral rates for further testing, adenoma surveillance regimens, and comparisons between tests. © Georg Thieme Verlag KG Stuttgart · New York.

  18. Tendon transfer around the shoulder in obstetric brachial plexus paralysis: clinical and computed tomographic study.

    PubMed

    El-Gammal, Tarek Abdalla; Saleh, Waleed Riad; El-Sayed, Amr; Kotb, Mohammed M; Imam, Hesham Mostafa; Fathi, Nihal Ahmad

    2006-01-01

    One hundred nine obstetrical palsy patients with defective shoulder abduction and external rotation had subscapularis release and transfer of teres major to infraspinatus with or without pedicle transfer of the clavicular head of pectoralis major to deltoid. The age at surgery averaged 67 months (11-192) and follow-up averaged 36 months (12-80). Thirty-nine cases had follow-up CT scan of both shoulders. Improvement of abduction averaged 64 degrees and that of external rotation 50 degrees, 100% and 290% gain, respectively. Both negatively correlated with the age at surgery (P < 0.001), and were significantly higher in patients operated younger than 4 years. On computed tomographic scans, the degree of glenoid retroversion positively correlated (P < 0.001) with the age at surgery, and was significantly higher in patients operated older than 4 years. The degree of posterior subluxation showed no significant difference between different ages. There was no significant difference between the operated and normal sides in patients operated younger than 4years with regard to glenoid retroversion and in those operated younger than 2 years with regard to posterior subluxation. The operation is useful for correction of defective shoulder abduction and external rotation in obstetric palsy. It is best performed before the age of 2 to get maximal improvement in motion and prevent secondary bone changes. Between the ages of 2 and 4, it also resulted in significant improvement in motion and prevented glenoid retroversion, but not posterior subluxation. After the age of 4, the improvement in motion was not significant and secondary bone changes were not prevented.

  19. Computed tomographic morphometry of thoracic pedicles: safety margin of transpedicular screw fixation in malaysian malay population.

    PubMed

    Liau, Kai Ming; Yusof, Mohd Imran; Abdullah, Mohd Shafie; Abdullah, Sarimah; Yusof, Abdul Halim

    2006-07-15

    A cross-sectional study of thoracic pedicle morphometry (T1-T12) of 180 Malaysian Malay patients obtained from computed tomographic scan. To determine the safety margin in the placement of thoracic transpedicular screw in the Malay population. Previous studies have shown a significantly smaller thoracic pedicular parameters in Asians compared with whites. The safety margin in the placement of thoracic transpedicular screw in our population therefore needs to be defined. T1-T12 vertebral pedicles were studied in 180 Malay ethnic patients (age range, 18-80 years). The following parameters were studied: transverse outer pedicle diameter, transverse inner pedicle diameter, transverse pedicle angle, chord length, pedicle length, and pedicle cortical thickness. The data obtained were statistically analyzed using Student's t test and ANOVA test. Female patients have significantly smaller dimensions in most of the parameters measured compared with male patients. However, no significant difference was found between age groups. Transverse outer pedicle diameter were widest at T1 (male, 8.42 mm; female, 7.56 mm) and narrowest at T4 (male, 4.56 mm; female, 3.95 mm). Pedicle diameters of less than 5.5 mm were commonly seen at T4 followed by T5, T6, T7, T8, and T9. A significant percentage of patients have an outer diameter of less than 4.5 mm from T4-T7. The medial cortices were 50% thicker than the lateral cortices at most levels. Chord lengths were maximum at T8 and minimum at T1. Transverse pedicle angle were widest at T1 and less than 5 degrees from T7-T12. The results suggest that the current pedicle screw system is not suitable for the majority of Malay population, especially at midthoracic level. The smaller pedicle measurements in Malays may be attributed to their shorter body built compared with whites.

  20. Computed tomographic differences of pyogenic liver abscesses caused by Klebsiella pneumoniae and non-Klebsiella pneumoniae.

    PubMed

    Kim, Sung-Bum; Je, Bo-Kyung; Lee, Kee Yeol; Lee, Seung Hwa; Chung, Hwan-Hoon; Cha, Sang Hoon

    2007-01-01

    To investigate the distinctive computed tomographic(CT) features of pyogenic liver abscess (PLA) caused by Klebsiella pneumoniae (KLA). 114 PLA patients (62 men, 52 women, age range 25-89 years, mean age 60.9 years) with positive yield of blood or pus cultures were divided into 2 groups; KLA group (n = 58) and non-KLA group (n = 56). We retrospectively reviewed the CT images. The independent-sample t-test, X2 test, or Fisher's exact test were used with SPSS for windows version 11.0. Gas formation showed no significant difference between two groups (P = 0.284), but air-fluid pattern was found only in KLA group (P = 0.027). The rim on dynamic CT was showed less frequently in KLA group than non-KLA group (P < 0.001), and smooth and regular rim was more common in non-KLA group (P < 0.001). The septation and septal breakage were more common in KLA group (P < 0.001). The turquoise sign was found significantly more in KLA group (P < 0.001). The hairball sign was detected only in KLA group (P < 0.001). The cluster sign was less frequent in KLA group (P < 0.001). KLA had a series of characteristic intra-abscess features; septal breakage, turquoise-like structure, hairball-like content, air-fluid level, and no enhanced rim. When turquoise/hairball sign or air-fluid level is present in abscess, KLA would be a probable diagnosis in the clinical field.

  1. Stent sizing by coronary computed tomographic angiography: comparison with conventional coronary angiography in an experienced setting.

    PubMed

    de Silva, Ramesh; Mussap, Christian J; Hecht, Harvey S; van Mieghem, Nicolas M; Matarazzo, Thomas J; Roubin, Gary S; Panagopoulos, Georgia

    2011-11-01

    The goal was to compare stent sizing by coronary computed tomographic angiography (CCTA) with that deployed in an experienced setting based upon conventional coronary angiography (CA). Stent sizing is currently performed by visual estimation, with infrequent guidance by intravascular ultrasound. CCTA permits quantitative determination of stent length (Stent L) and diameter (Stent D). Projected L (CTA-Stent L) and D (CTA-Stent D) were determined from CCTA obtained in 248 patients with 352 lesions undergoing percutaneous coronary intervention within 4 months of the CCTA, and were compared to the Stent-L and Stent-D of the actually deployed stents. The effects of lesion modification and calcified plaque were also evaluated. There were significant correlations between CTA-Stent L and Stent L (r = 0.656, P < 0.0001) and between CTA-Stent D and Stent D (r = 0.40, P < 0.001). Median predicted CTA-Stent L was slightly longer (20 mm vs. 18 mm, P < 0.0001) and predicted CTA-Stent D was slightly smaller (3.0 mm vs. 3.2 mm, P < 0.0001) than Stent-L and Stent-D, respectively. The differences were unchanged in stents with lesion modification by pre-dilation or intracoronary nitroglycerin. CTA Stent-L and CTA Stent-D increased significantly with increasing calcium (P < 0.0001 and P = 0.019, respectively). (1) There are significant correlations between CCTA and CA based stent sizing in an experienced setting. (2) CCTA projects slightly longer and slightly smaller diameter stents than those deployed during PCI irrespective of lesion modification; the small differences are unlikely to have clinical significance. (3) CCTA may offer a noninvasive alternative to intravascular ultrasound for stent planning. Copyright © 2011 Wiley-Liss, Inc.

  2. Pediatric small bowel intussusception disease: feasibility of screening for surgery with early computed tomographic evaluation.

    PubMed

    Ko, Sheung-Fat; Tiao, Mao-Meng; Hsieh, Chie-Song; Huang, Fu-Chen; Huang, Chung-Cheng; Ng, Shu-Hang; Lee, Shin-Yee; Chen, Min-Chi

    2010-04-01

    This study investigated the feasibility of early computed tomographic (CT) evaluation and the operative results of pediatric small bowel intussusception with deteriorating ischemic or obstructive symptoms, so-called small bowel intussusception disease (SBID). Between 1988 and 1999, among 18 patients surgically proven SBID (conventional group), 12 mimicked ileocolic intussusception and were conventionally managed with abdominal radiography, ultrasonography, reduction enema, and eventually operation. Between 2000 and 2008, we applied a modified approach with inclusion of early CT evaluation if ultrasonography showed a target lesion suspicious for SBID (diameter

  3. Computed tomographic evaluation of dynamic alteration of the canine lumbosacral intervertebral neurovascular foramina.

    PubMed

    Worth, Andrew J; Hartman, Angela; Bridges, Janis P; Jones, Boyd R; Mayhew, Joe I G

    2017-02-01

    To develop a computed tomographic (CT) method to measure the volume of the lumbosacral intervertebral neurovascular foramina (IVF) in dogs, and determine the effect of the range of motion of the lumbosacral (LS) junction on this measurement in German shepherd dogs (GSDs) with degenerative lumbosacral stenosis (DLSS) compared to unaffected controls. In vivo analysis and retrospective case series. Twenty-four working Police GSDs, 12 diagnosed with DLSS and 12 unaffected by DLSS were compared to 10 Greyhounds without DLSS. Three-dimensional renderings of CT data were used to measure the lumbosacral foraminal volume of dogs positioned in dorsal recumbency with the LS junction alternately positioned in extension, neutral position, and flexion. Volumetric analysis of the IVF was found repeatable for the extended and neutral positions (interclass correlation coefficient of 0.89 and 0.8, respectively). The mean lumbosacral IVF volume was decreased by 74% between LS flexion and extension in Greyhounds, compared to 79 and 85% reductions in GSDs unaffected and affected by DLSS, respectively. The lumbosacral IVF volume was decreased by 23% when comparing extended to neutral LS positions in Greyhounds, 29% in unaffected GSDs, and 31% in affected GSDs. IVF volumes were smaller in affected GSDs compared to unaffected GSDs (P < .05) and Greyhounds (P < .01). Positioning the LS junction in full extension decreases the volume of the lumbosacral IVF. This dynamic narrowing was more pronounced in GSDs with signs of DLSS than in GSDs not overtly affected by DLSS. © 2017 The American College of Veterinary Surgeons.

  4. A method for visualizing high-density porous polyethylene (medpor, porex) with computed tomographic scanning.

    PubMed

    Vendemia, Nicholas; Chao, Jerry; Ivanidze, Jana; Sanelli, Pina; Spinelli, Henry M

    2011-01-01

    Medpor (Porex Surgical, Inc, Newnan, GA) is composed of porous polyethylene and is commonly used in craniofacial reconstruction. When complications such as seroma or abscess formation arise, diagnostic modalities are limited because Medpor is radiolucent on conventional radiologic studies. This poses a problem in situations where imaging is necessary to distinguish the implant from surrounding tissues. To present a clinically useful method for imaging Medpor with conventional computed tomographic (CT) scanning. Eleven patients (12 total implants) who have undergone reconstructive surgery with Medpor were included in the study. A retrospective review of CT scans done between 1 and 16 months postoperatively was performed using 3 distinct CT window settings. Measurements of implant dimensions and Hounsfield units were recorded and qualitatively assessed. Of the 3 distinct window settings studied, namely, "bone" (W1100/L450), "soft tissue"; (W500/L50), and "implant" (W800/L200), the implant window proved the most ideal, allowing the investigators to visualize and evaluate Medpor in all cases. Qualitative analysis revealed that Medpor implants were able to be distinguished from surrounding tissue in both the implant and soft tissue windows, with a density falling between that of fat and fluid. In 1 case, Medpor could not be visualized in the soft tissue window, although it could be visualized in the implant window. Quantitative analysis demonstrated a mean (SD) density of -38.7 (7.4) Hounsfield units. Medpor may be optimally visualized on conventional CT scans using the implant window settings W800/L200, which can aid in imaging Medpor and diagnosing implant-related complications.

  5. A Cone-Beam Computed Tomographic Study on Mandibular First Molars in a Chinese Subpopulation.

    PubMed

    Zhang, Xin; Xiong, Shijiang; Ma, Yue; Han, Ting; Chen, Xinyu; Wan, Fang; Lu, Yating; Yan, Songhe; Wang, Yan

    2015-01-01

    The purpose of this study was to conduct a cone-beam computed tomographic (CBCT) investigation on the root and canal configuration of the mandibular first molars, especially the morphology of the disto-lingual (DL) root, in a Chinese subpopulation. A total of 910 CBCT images of the mandibular first molars were collected from 455 patients who underwent CBCT examinations as a preoperative assessment for implants or orthodontic treatment. The following information was analyzed and evaluated: tooth position, gender, root and root canal number per tooth, root canal type of the mesial root(s) and distal root(s), angle of the DL root canal curvature, distance between two distal canal orifices in the teeth with DL root, and angle of disto-buccal canal orifice-disto-lingual canal orifice-mesio-lingual canal orifice (DB-DL-ML). Most of the mandibular first molars (64.9%, n = 591) had two roots with three root canals, and most of the mesial root canals (87.7%, n = 798) were type VI. The prevalence of the DL root was 22.1% (n = 201). The right side had a higher prevalence of DL root than the left side (p<0.05). Additionally, the curvature of the DL root canal were greater in the bucco-lingual (BL) orientation (30.10°±14.02°) than in the mesio-distal (MD) orientation (14.03°± 8.56°) (p<0.05). Overall there was a high prevalence of DL root in the mandibular first molars, and most of the DL roots were curved in different degrees. This study provided detailed information about the root canal morphology of the mandibular first molars in a Chinese subpopulation.

  6. [Specific features of interpretation of myocardial perfusion single-photon emission computed tomography with computed tomographic absorption correction].

    PubMed

    Ansheles, A A

    2014-01-01

    To study the capabilities of a hybrid single-photon emission computed tomography/computed tomography (SPECT/CT) system during myocardial perfusion imaging study, to evaluate the impact of absorption correction (AC), and to reveal factors influencing the contribution of AC to the diagnostic result of the study. The study included 167 patients who underwent myocardial perfusion SPECT with and without CT AC. Differences between AC and non-AC studies were visually analyzed; the results of the analysis were used to form groups of visual differences. The supposed factors influencing the contribution of AC were studied, by assigning visual differences to a particular group. The possible variants of the impact of AC were described in the baseline scintigrams. AC made a significant contribution in 68% of cases. With AC, the perfusion defects visible during non-AC study recovered in 80% of these cases. The factors predicting substantial differences between the AC and non-AC studies included weight, end diastolic volume, male sex, patients with small focal perfusion defects and transient ischemia, and inadequate injected activity. Factors, such as body mass index, large perfusion defects, CT subsystem and orbit settings, and time from the injection of a radiotracer to the initiation of a study, had no substantial impact on the contribution of AC. During AC studies, SRS and transient ischemic dilatation were significantly higher than during non-AC studies, requiring a shift of standard criteria. There were some methodical features of interpretation of myocardial perfusion SPECT using CT correction. Myocardial SPECT with AC enhances the diagnostic value of the technique, simplifies the interpretation of myocardial perfusion SPECT, and reduces the number of false-positive and questionable results.

  7. False positive stress-test in a patient with pericardial effusion.

    PubMed

    Mateja, Candice; Mishkin, Joseph; George, Malika; Chheda, Hemant; Guglin, Maya

    2009-10-02

    We report a case of false positive stress test in a patient with cardiac tamponade. After the drainage of pericardial effusion, reversible defect on a stress test resolved. Cardiac catheterization revealed normal coronary arteries.

  8. Accounting for false-positive acoustic detections of bats using occupancy models

    USGS Publications Warehouse

    Clement, Matthew J.; Rodhouse, Thomas J.; Ormsbee, Patricia C.; Szewczak, Joseph M.; Nichols, James D.

    2014-01-01

    4. Synthesis and applications. Our results suggest that false positives sufficient to affect inferences may be common in acoustic surveys for bats. We demonstrate an approach that can estimate occupancy, regardless of the false-positive rate, when acoustic surveys are paired with capture surveys. Applications of this approach include monitoring the spread of White-Nose Syndrome, estimating the impact of climate change and informing conservation listing decisions. We calculate a site-specific probability of occupancy, conditional on survey results, which could inform local permitting decisions, such as for wind energy projects. More generally, the magnitude of false positives suggests that false-positive occupancy models can improve accuracy in research and monitoring of bats and provide wildlife managers with more reliable information.

  9. Association of Multiorgan Computed Tomographic Phenomap With Adverse Cardiovascular Health Outcomes: The Framingham Heart Study.

    PubMed

    Shah, Ravi V; Yeri, Ashish S; Murthy, Venkatesh L; Massaro, Joe M; D'Agostino, Ralph; Freedman, Jane E; Long, Michelle T; Fox, Caroline S; Das, Saumya; Benjamin, Emelia J; Vasan, Ramachandran S; O'Donnell, Christopher J; Hoffmann, Udo

    2017-09-20

    Increased ability to quantify anatomical phenotypes across multiple organs provides the opportunity to assess their cumulative ability to identify individuals at greatest susceptibility for adverse outcomes. To apply unsupervised machine learning to define the distribution and prognostic importance of computed tomography-based multiorgan phenotypes associated with adverse health outcomes. This asymptomatic community-based cohort study included 2924 Framingham Heart Study participants between July 2002 and April 2005 undergoing computed tomographic imaging of the chest and abdomen. Participants are from the offspring and third-generation cohorts. Eleven computed tomography-based measures of valvular/vascular calcification, adiposity, and muscle attenuation. All-cause mortality and cardiovascular disease (myocardial infarction, stroke, or cardiovascular death). The median age of the participants was 50 years (interquartile range, 43-60 years), and 1422 (48.6%) were men. Principal component analysis identified 3 major anatomic axes: (1) global calcification (defined by aortic, thoracic, coronary, and valvular calcification); (2) adiposity (defined by pericardial, visceral, hepatic, and intrathoracic fat); and (3) muscle attenuation that explained 65.7% of the population variation. Principal components showed different evolution with age (continuous increase in global calcification, decrease in muscle attenuation, and U-shaped association with adiposity) but similar patterns in men and women. Using unsupervised clustering approaches in the offspring cohort (n = 1150), we identified a cohort (n = 232; 20.2%) with an unfavorable multiorgan phenotype across all 3 anatomic axes as compared with a favorable multiorgan phenotype. Membership in the unfavorable phenotypic cluster was associated with a greater prevalence of cardiovascular disease risk factors and with increased all-cause mortality (hazard ratio, 2.61; 95% CI, 1.74-3.92; P < .001), independent of

  10. From Docking False-Positive to Active Anti-HIV Agent

    PubMed Central

    Barreiro, Gabriela; Kim, Joseph T.; Guimarães, Cristiano R. W.; Bailey, Christopher M.; Domaoal, Robert A.; Wang, Ligong; Anderson, Karen S.

    2008-01-01

    Virtual screening of the Maybridge library of ca. 70,000 compounds was performed using a similarity filter, docking, and MM-GB/SA post-processing to seek potential non-nucleoside inhibitors of HIV-1 reverse transcriptase (NNRTIs). Though known NNRTIs were retrieved well, purchase and assaying of representative, top-scoring compounds from the library failed to yield any active anti-HIV agents. However, the highest-ranked library compound, oxadiazole 1, was pursued as a potential “near-miss” with the BOMB program to seek constructive modifications. Subsequent synthesis and assaying of several polychloro-analogs did yield anti-HIV agents with EC50 values as low as 310 nM. The study demonstrates that it is possible to learn from a formally unsuccessful virtual-screening exercise and, with the aid of computational analyses, to evolve efficiently a false positive into a true active. In addition, the need for adequate structure validation was confirmed by the apparent misrepresentation of a purchased compound elsewhere as the present oxadiazole core compound, 16. PMID:17918923

  11. Reduction of false positives by extracting fuzzy rules from data for polyp detection in CTC scans

    NASA Astrophysics Data System (ADS)

    Siddique, Musib M.; Zheng, Yalin; Yang, Xiaoyun; Beddoe, Gareth

    2008-03-01

    This paper presents an adaptive neural network based Fuzzy Inference System (ANFIS) to reduce the false positive (FP) rate of detected colonic polyps in Computed Tomography Colonography (CTC) scans. Extracted fuzzy rules establish linguistically interpretable relationships in the data that are easy to understand, validate, and extend. The system takes several features identified from regions extracted by a segmentation algorithm and decides whether the regions are true polyps. In the training phase, subtractive clustering is used to down-sample the negative regions in order to get balanced data. The rule extraction method is based on estimating clusters in the data using the subtractive clustering algorithm; each cluster obtained corresponds to a fuzzy rule that maps a region in the input space to an output class. After the number of rules and initial rule parameters are obtained by cluster estimation, the rule parameters are optimized using a hybrid learning algorithm which is a combination of least-squares estimation with back propagation. The evolved Sugeno-type FIS has been tested on a total of 129 scans with 99 polyps of sizes 5-15 mm by experienced radiologists. The results indicate that for 93% detection sensitivity (on polyps), the evolved FIS method is able to remove 88% of FPs generated by the segmentation algorithm leaving 7.5 FP per scan. The high sensitivity rate of our results show the promise of neuro-fuzzy classifiers as an aid for interpreting CTC examinations.

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

    PubMed

    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. Congenital absence of the gallbladder: another cause of false-positive hepatobiliary image

    SciTech Connect

    Dickinson, C.Z.; Powers, T.A.; Sandler, M.P.; Partain, C.L.

    1984-01-01

    Hepatobiliary imaging with the various technetium-labeled IDA compounds is more than 90% sensitive and specific for the diagnosis of acute cholecystitis. Causes of false-positive studies include chronic cholecystitis, cystic-duct obstruction by tumor, prolonged fasting, the nonfasting state, pancreatitis, alcoholism, parenteral hyperalimentation, and severe intercurrent illness. A case of congenital absence of the gallbladder is sumbitted as another cause of a false-positive scan.

  14. False-positive cryptococcal antigen latex agglutination caused by disinfectants and soaps.

    PubMed Central

    Blevins, L B; Fenn, J; Segal, H; Newcomb-Gayman, P; Carroll, K C

    1995-01-01

    Five disinfectants or soaps were tested to determine if any could be responsible for false-positive results obtained with the Latex-Crypto Antigen Detection System kit (Immuno-Mycologics, Inc., Norman, Okla.). Three disinfectants or soaps (Derma soap, 7X, and Bacdown) produced false-positive agglutination after repeated washing of ring slides during testing of a known negative cerebrospinal fluid specimen. PMID:7650214

  15. Screening Mammograms by Community Radiologists: Variability in False-Positive Rates

    PubMed Central

    Elmore, Joann G.; Miglioretti, Diana L.; Reisch, Lisa M.; Barton, Mary B.; Kreuter, William; Christiansen, Cindy L.; Fletcher, Suzanne W.

    2011-01-01

    Background Previous studies have shown that the agreement among radiologists interpreting a test set of mammograms is relatively low. However, data available from real-world settings are sparse. We studied mammographic examination interpretations by radiologists practicing in a community setting and evaluated whether the variability in false-positive rates could be explained by patient, radiologist, and/or testing characteristics. Methods We used medical records on randomly selected women aged 40–69 years who had had at least one screening mammographic examination in a community setting between January 1, 1985, and June 30, 1993. Twenty-four radiologists interpreted 8734 screening mammograms from 2169 women. Hierarchical logistic regression models were used to examine the impact of patient, radiologist, and testing characteristics. All statistical tests were two-sided. Results Radiologists varied widely in mammographic examination interpretations, with a mass noted in 0%–7.9%, calcification in 0%–21.3%, and fibrocystic changes in 1.6%–27.8% of mammograms read. False-positive rates ranged from 2.6% to 15.9%. Younger and more recently trained radiologists had higher false-positive rates. Adjustment for patient, radiologist, and testing characteristics narrowed the range of false-positive rates to 3.5%–7.9%. If a woman went to two randomly selected radiologists, her odds, after adjustment, of having a false-positive reading would be 1.5 times greater for the radiologist at higher risk of a false-positive reading, compared with the radiologist at lowest risk (95% highest posterior density interval [similar to a confidence interval] = 1.17 to 2.08). Conclusion Community radiologists varied widely in their false-positive rates in screening mammograms; this variability range was reduced by half, but not eliminated, after statistical adjustment for patient, radiologist, and testing characteristics. These characteristics need to be considered when evaluating false-positive

  16. False-positive interferences of common urine drug screen immunoassays: a review.

    PubMed

    Saitman, Alec; Park, Hyung-Doo; Fitzgerald, Robert L

    2014-09-01

    Urine drug screen (UDS) immunoassays are a quick and inexpensive method for determining the presence of drugs of abuse. Many cross-reactivities exist with other analytes, potentially causing a false-positive result in an initial drug screen. Knowledge of these potential interferents is important in determining a course of action for patient care. We present an inclusive review of analytes causing false-positive interferences with drugs-of-abuse UDS immunoassays, which covers the literature from the year 2000 to present. English language articles were searched via the SciFinder platform with the strings 'false positive [drug] urine' yielding 173 articles. These articles were then carefully analyzed and condensed to 62 that included data on causes of false-positive results. The discussion is separated into six sections by drug class with a corresponding table of cross-reacting compounds for quick reference. False-positive results were described for amphetamines, opiates, benzodiazepines, cannabinoids, tricyclic antidepressants, phencyclidine, lysergic acid diethylamide and barbiturates. These false-positive results support the generally accepted practice that immunoassay positive results are considered presumptive until confirmed by a second independent chemical technique.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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.

  19. Cost-Effectiveness of Computed Tomographic Colonography Screening for Colorectal Cancer in the Medicare Population

    PubMed Central

    Lansdorp-Vogelaar, Iris; Rutter, Carolyn M.; Savarino, James E.; van Ballegooijen, Marjolein; Kuntz, Karen M.; Zauber, Ann G.

    2010-01-01

    Background The Centers for Medicare and Medicaid Services (CMS) considered whether to reimburse computed tomographic colonography (CTC) for colorectal cancer screening of Medicare enrollees. To help inform its decision, we evaluated the reimbursement rate at which CTC screening could be cost-effective compared with the colorectal cancer screening tests that are currently reimbursed by CMS and are included in most colorectal cancer screening guidelines, namely annual fecal occult blood test (FOBT), flexible sigmoidoscopy every 5 years, flexible sigmoidoscopy every 5 years in conjunction with annual FOBT, and colonoscopy every 10 years. Methods We used three independently developed microsimulation models to assess the health outcomes and costs associated with CTC screening and with currently reimbursed colorectal cancer screening tests among the average-risk Medicare population. We assumed that CTC was performed every 5 years (using test characteristics from either a Department of Defense CTC study or the National CTC Trial) and that individuals with findings of 6 mm or larger were referred to colonoscopy. We computed incremental cost-effectiveness ratios for the currently reimbursed screening tests and calculated the maximum cost per scan (ie, the threshold cost) for the CTC strategy to lie on the efficient frontier. Sensitivity analyses were performed on key parameters and assumptions. Results Assuming perfect adherence with all tests, the undiscounted number life-years gained from CTC screening ranged from 143 to 178 per 1000 65-year-olds, which was slightly less than the number of life-years gained from 10-yearly colonoscopy (152–185 per 1000 65-year-olds) and comparable to that from 5-yearly sigmoidoscopy with annual FOBT (149–177 per 1000 65-year-olds). If CTC screening was reimbursed at $488 per scan (slightly less than the reimbursement for a colonoscopy without polypectomy), it would be the most costly strategy. CTC screening could be cost-effective at

  20. Multidetector computed tomographic pulmonary angiography in patients with a high clinical probability of pulmonary embolism.

    PubMed

    Moores, L; Kline, J; Portillo, A K; Resano, S; Vicente, A; Arrieta, P; Corres, J; Tapson, V; Yusen, R D; Jiménez, D

    2016-01-01

    ESSENTIALS: When high probability of pulmonary embolism (PE), sensitivity of computed tomography (CT) is unclear. We investigated the sensitivity of multidetector CT among 134 patients with a high probability of PE. A normal CT alone may not safely exclude PE in patients with a high clinical pretest probability. In patients with no clear alternative diagnosis after CTPA, further testing should be strongly considered. Whether patients with a negative multidetector computed tomographic pulmonary angiography (CTPA) result and a high clinical pretest probability of pulmonary embolism (PE) should be further investigated is controversial. This was a prospective investigation of the sensitivity of multidetector CTPA among patients with a priori clinical assessment of a high probability of PE according to the Wells criteria. Among patients with a negative CTPA result, the diagnosis of PE required at least one of the following conditions: ventilation/perfusion lung scan showing a high probability of PE in a patient with no history of PE, abnormal findings on venous ultrasonography in a patient without previous deep vein thrombosis at that site, or the occurrence of venous thromboembolism (VTE) in a 3-month follow-up period after anticoagulation was withheld because of a negative multidetector CTPA result. We identified 498 patients with a priori clinical assessment of a high probability of PE and a completed CTPA study. CTPA excluded PE in 134 patients; in these patients, the pooled incidence of VTE was 5.2% (seven of 134 patients; 95% confidence interval [CI] 1.5-9.0). Five patients had VTEs that were confirmed by an additional imaging test despite a negative CTPA result (five of 48 patients; 10.4%; 95% CI 1.8-19.1), and two patients had objectively confirmed VTEs that occurred during clinical follow-up of at least 3 months (two of 86 patients; 2.3%; 95% CI 0-5.5). None of the patients had a fatal PE during follow-up. A normal multidetector CTPA result alone may not safely

  1. Constraining the false positive rate for Kepler planet candidates with multicolour photometry from the GTC

    NASA Astrophysics Data System (ADS)

    Colón, Knicole D.; Ford, Eric B.; Morehead, Robert C.

    2012-10-01

    Using the Optical System for Imaging and low Resolution Integrated Spectroscopy (OSIRIS) instrument installed on the 10.4-m Gran Telescopio Canarias (GTC), we acquired multicolour transit photometry of four small (Rp≲5 R⊕) short-period (P ≲ 6 d) planet candidates recently identified by the Kepler space mission. These observations are part of a programme to constrain the false positive rate for small, short-period Kepler planet candidates. Since planetary transits should be largely achromatic when observed at different wavelengths (excluding the small colour changes due to stellar limb darkening), we use the observed transit colour to identify candidates as either false positives (e.g. a blend with a stellar eclipsing binary either in the background/foreground or bound to the target star) or validated planets. Our results include the identification of KOI 225.01 and KOI 1187.01 as false positives and the tentative validation of KOI 420.01 and KOI 526.01 as planets. The probability of identifying two false positives out of a sample of four targets is less than 1 per cent, assuming an overall false positive rate for Kepler planet candidates of 10 per cent (as estimated by Morton & Johnson). Therefore, these results suggest a higher false positive rate for the small, short-period Kepler planet candidates than has been theoretically predicted by other studies which consider the Kepler planet candidate sample as a whole. Furthermore, our results are consistent with a recent Doppler study of short-period giant Kepler planet candidates. We also investigate how the false positive rate for our sample varies with different planetary and stellar properties. Our results suggest that the false positive rate varies significantly with orbital period and is largest at the shortest orbital periods (P < 3 d), where there is a corresponding rise in the number of detached eclipsing binary stars (i.e. systems that can easily mimic planetary transits) that have been discovered by

  2. Hypertension is strongly associated with false-positive bicycle exercise stress echocardiography testing results.

    PubMed

    Keller, Karsten; Stelzer, Kathrin; Munzel, Thomas; Ostad, Mir Abolfazl

    2016-12-01

    Exercise echocardiography is a reliable routine test in patients with known or suspected coronary artery disease. However, in ∼15% of all patients, stress echocardiography leads to false-positive stress echocardiography results. We aimed to investigate the impact of hypertension on stress echocardiographic results. We performed a retrospective study of patients with suspected or known stable coronary artery disease who underwent a bicycle exercise stress echocardiography. Patients with false-positive stress results were compared with those with appropriate results. 126 patients with suspected or known coronary artery disease were included in this retrospective study. 23 patients showed false-positive stress echocardiography results. Beside comparable age, gender distribution and coronary artery status, hypertension was more prevalent in patients with false-positive stress results (95.7% vs. 67.0%, p = 0.0410). Exercise peak load revealed a borderline-significance with lower loads in patients with false-positive results (100.0 (IQR 75.0/137.5) vs. 125.0 (100.0/150.0) W, p = 0.0601). Patients with false-positive stress results showed higher systolic (2.05 ± 0.69 vs. 1.67 ± 0.39 mmHg/W, p = 0.0193) and diastolic (1.03 ± 0.38 vs. 0.80 ± 0.28 mmHg/W, p = 0.0165) peak blood pressure (BP) per wattage. In a multivariate logistic regression test, hypertension (OR 17.6 [CI 95% 1.9-162.2], p = 0.0115), and systolic (OR 4.12 [1.56-10.89], p = 0.00430) and diastolic (OR 13.74 [2.46-76.83], p = 0.00285) peak BP per wattage, were associated with false-positive exercise results. ROC analysis for systolic and diastolic peak BP levels per wattage showed optimal cut-off values of 1.935mmHg/W and 0.823mmHg/W, indicating false-positive exercise echocardiographic results with AUCs of 0.660 and 0.664, respectively. Hypertension is a risk factor for false-positive stress exercise echocardiographic results in patients with known or

  3. Experimental investigation of false positive errors in auditory species occurrence surveys

    USGS Publications Warehouse

    Miller, David A.W.; Weir, Linda A.; McClintock, Brett T.; Grant, Evan H. Campbell; Bailey, Larissa L.; Simons, Theodore R.

    2012-01-01

    False positive errors are a significant component of many ecological data sets, which in combination with false negative errors, can lead to severe biases in conclusions about ecological systems. We present results of a field experiment where observers recorded observations for known combinations of electronically broadcast calling anurans under conditions mimicking field surveys to determine species occurrence. Our objectives were to characterize false positive error probabilities for auditory methods based on a large number of observers, to determine if targeted instruction could be used to reduce false positive error rates, and to establish useful predictors of among-observer and among-species differences in error rates. We recruited 31 observers, ranging in abilities from novice to expert, that recorded detections for 12 species during 180 calling trials (66,960 total observations). All observers made multiple false positive errors and on average 8.1% of recorded detections in the experiment were false positive errors. Additional instruction had only minor effects on error rates. After instruction, false positive error probabilities decreased by 16% for treatment individuals compared to controls with broad confidence interval overlap of 0 (95% CI: -46 to 30%). This coincided with an increase in false negative errors due to the treatment (26%; -3 to 61%). Differences among observers in false positive and in false negative error rates were best predicted by scores from an online test and a self-assessment of observer ability completed prior to the field experiment. In contrast, years of experience conducting call surveys was a weak predictor of error rates. False positive errors were also more common for species that were played more frequently, but were not related to the dominant spectral frequency of the call. Our results corroborate other work that demonstrates false positives are a significant component of species occurrence data collected by auditory

  4. Reduced lung-cancer mortality with low-dose computed tomographic screening.

    PubMed

    Aberle, Denise R; Adams, Amanda M; Berg, Christine D; Black, William C; Clapp, Jonathan D; Fagerstrom, Richard M; Gareen, Ilana F; Gatsonis, Constantine; Marcus, Pamela M; Sicks, JoRean D

    2011-08-04

    The aggressive and heterogeneous nature of lung cancer has thwarted efforts to reduce mortality from this cancer through the use of screening. The advent of low-dose helical computed tomography (CT) altered the landscape of lung-cancer screening, with studies indicating that low-dose CT detects many tumors at early stages. The National Lung Screening Trial (NLST) was conducted to determine whether screening with low-dose CT could reduce mortality from lung cancer. From August 2002 through April 2004, we enrolled 53,454 persons at high risk for lung cancer at 33 U.S. medical centers. Participants were randomly assigned to undergo three annual screenings with either low-dose CT (26,722 participants) or single-view posteroanterior chest radiography (26,732). Data were collected on cases of lung cancer and deaths from lung cancer that occurred through December 31, 2009. The rate of adherence to screening was more than 90%. The rate of positive screening tests was 24.2% with low-dose CT and 6.9% with radiography over all three rounds. A total of 96.4% of the positive screening results in the low-dose CT group and 94.5% in the radiography group were false positive results. The incidence of lung cancer was 645 cases per 100,000 person-years (1060 cancers) in the low-dose CT group, as compared with 572 cases per 100,000 person-years (941 cancers) in the radiography group (rate ratio, 1.13; 95% confidence interval [CI], 1.03 to 1.23). There were 247 deaths from lung cancer per 100,000 person-years in the low-dose CT group and 309 deaths per 100,000 person-years in the radiography group, representing a relative reduction in mortality from lung cancer with low-dose CT screening of 20.0% (95% CI, 6.8 to 26.7; P=0.004). The rate of death from any cause was reduced in the low-dose CT group, as compared with the radiography group, by 6.7% (95% CI, 1.2 to 13.6; P=0.02). Screening with the use of low-dose CT reduces mortality from lung cancer. (Funded by the National Cancer

  5. Psychological distress in U.S. women who have experienced false-positive mammograms.

    PubMed

    Jatoi, Ismail; Zhu, Kangmin; Shah, Mona; Lawrence, William

    2006-11-01

    In the United States, approximately 10.7% of all screening mammograms lead to a false-positive result, but the overall impact of false-positives on psychological well-being is poorly understood. Data were analyzed from the 2000 U.S. National Health Interview Survey (NHIS), the most recent national survey that included a cancer control module. Study subjects were 9,755 women who ever had a mammogram, of which 1,450 had experienced a false-positive result. Psychological distress was assessed using the validated K6 questionnaire and logistic regression was used to discern any association with previous false-positive mammograms. In a multivariate analysis, women who had indicated a previous false-positive mammogram were more likely to report feeling sad (OR = 1.18, 95% CI, 1.03-1.35), restless (OR = 1.23, 95% CI, 1.08-1.40), worthless (OR = 1.27, 95% CI, 1.04-1.54), and finding that everything was an effort (OR = 1.27, 95% CI, 1.10-1.47). These women were also more likely to have seen a mental health professional in the 12 months preceding the survey (OR = 1.28, 95% CI, 1.03-1.58) and had a higher composite score on all items of the K6 scale (P < 0.0001), a reflection of increased psychological distress. Analyses by age and race revealed that, among women who had experienced false-positives, younger women were more likely to feel that everything was an effort, and blacks were more likely to feel restless. In a random sampling of the U.S. population, women who had previously experienced false-positive mammograms were more likely to report symptoms of anxiety and depression.

  6. Understanding false positives in reporter gene assays: in silico chemogenomics approaches to prioritize cell-based HTS data.

    PubMed

    Crisman, Thomas J; Parker, Christian N; Jenkins, Jeremy L; Scheiber, Josef; Thoma, Mathis; Kang, Zhao Bin; Kim, Richard; Bender, Andreas; Nettles, James H; Davies, John W; Glick, Meir

    2007-01-01

    High throughput screening (HTS) data is often noisy, containing both false positives and negatives. Thus, careful triaging and prioritization of the primary hit list can save time and money by identifying potential false positives before incurring the expense of followup. Of particular concern are cell-based reporter gene assays (RGAs) where the number of hits may be prohibitively high to be scrutinized manually for weeding out erroneous data. Based on statistical models built from chemical structures of 650 000 compounds tested in RGAs, we created "frequent hitter" models that make it possible to prioritize potential false positives. Furthermore, we followed up the frequent hitter evaluation with chemical structure based in silico target predictions to hypothesize a mechanism for the observed "off target" response. It was observed that the predicted cellular targets for the frequent hitters were known to be associated with undesirable effects such as cytotoxicity. More specifically, the most frequently predicted targets relate to apoptosis and cell differentiation, including kinases, topoisomerases, and protein phosphatases. The mechanism-based frequent hitter hypothesis was tested using 160 additional druglike compounds predicted by the model to be nonspecific actives in RGAs. This validation was successful (showing a 50% hit rate compared to a normal hit rate as low as 2%), and it demonstrates the power of computational models toward understanding complex relations between chemical structure and biological function.

  7. False-positive identification of Escherichia coli in treated municipal wastewater and wastewater-irrigated soils.

    PubMed

    McLain, Jean E T; Rock, Channah M; Lohse, Kathleen; Walworth, James

    2011-10-01

    The increasing use of treated wastewater for irrigation heightens the importance of accurate monitoring of water quality. Chromogenic media, because they are easy to use and provide rapid results, are often used for detection of Escherichia coli in environmental samples, but unique levels of organic and inorganic compounds alter the chemistry of treated wastewater, potentially hindering the accurate performance of chromogenic media. We used MI agar and molecular confirmatory methods to assess false-positive identification of E. coli in treated wastewater samples collected from municipal utilities, an irrigation holding pond, irrigated soils, and in samples collected from storm flows destined for groundwater recharge. False-positive rates in storm flows (4.0%) agreed closely with USEPA technical literature but were higher in samples from the pond, soils, and treatment facilities (33.3%, 38.0%, and 48.8%, respectively). Sequencing of false-positive isolates confirmed that most were, like E. coli, of the family Enterobacteriaceae, and many of the false-positive isolates were reported to produce the β-D-glucuronidase enzyme targeted by MI agar. False-positive identification rates were inversely related to air temperature, suggesting that seasonal variations in water quality influence E. coli identification. Knowledge of factors contributing to failure of chromogenic media will lead to manufacturer enhancements in media quality and performance and will ultimately increase the accuracy of future water quality monitoring programs.

  8. Receipt of a false positive test result during routine screening for ovarian cancer: a teachable moment?

    PubMed

    Floyd, Andrea; Steffens, Rachel F; Pavlik, Edward; Andrykowski, Michael A

    2011-03-01

    The term "teachable moment" (TM) has been used to describe a life transition or event which motivates an individual to change a behavior or presents an opportunity to intervene to prompt behavior change. We examined whether receipt of a false positive ovarian cancer (OC) screening result may represent a TM. 403 women participating in an OC screening program completed questionnaires assessing demographic, clinical, behavioral, and psychosocial information. The TM was operationalized as expressed interest in receiving health-related information. We hypothesized that among women receiving a false positive screening test result, those women who had experienced greater personal perceived risk for OC as well as distress would be more interested in receiving health-related information than women receiving a normal result. Analyses revealed that women receiving a false positive screening result were less interested in receiving health-related information than women receiving a normal screening result. For women receiving a false positive result, expressed interest in receipt of health-related information was only modestly related to distress and related even less to perceptions of OC risk. Our data do not support viewing a false positive OC screening result as a TM. Potential explanations for the current findings as well as recommendations for future research investigating the TM are discussed.

  9. Should computed tomographic colonography replace optical colonoscopy in screening for colorectal cancer?

    PubMed

    Veerappan, Ganesh R; Cash, Brooks D

    2009-04-01

    Clinical evidence amassed over the last several decades indicates that routine colorectal cancer (CRC) screening, compared to no screening, detects CRC at an earlier stage, reduces the incidence of CRC or the progression early CRC through polypectomy, and reduces CRC mortality. Computed tomographic colonography (CTC) is a minimally invasive, structural evaluation of the entire colorectum that has recently been advocated by multiple American professional medical societies as an effective alternative for CRC screening. The potential advantages of CTC, including rapid image acquisition and processing, non-invasiveness, and decreased procedural risks of perforation, bleeding, and sedation complications may serve to improve the low rates of colorectal cancer screening that are currently observed in our society. Several large studies of CTC as a CRC screening test have reported excellent results but have been criticized because of the expertise of CTC interpreters participating in those trials. As a response to these criticisms, the long-awaited results of the American College of Radiology Imaging Network (ACRIN) National CT Colonography Trial were recently published. The purpose of this study was to assess the accuracy of CTC in a "community based" environment to determine if previous results obtained at expert sites could be replicated. All CTC were confirmed and compared to conventional colonoscopy, the gold-standard colorectal cancer screening test. For polyps >10 mm, the results obtained in the ACRIN trial were comparable to previous studies with a mean CTC sensitivity of 90% and a mean CTC specificity of 86%. The sensitivity of CTC fell to 78% for lesions >6 mm, a value that some studies have suggested is comparable to the detection rate of conventional colonoscopy. This study adds to the body of literature regarding the efficacy of CTC and will likely be cited by many as evidence supporting CTC as an acceptable CRC screening test, in the same league as colonoscopy

  10. Physiological and computed tomographic predictors of outcome from lung volume reduction surgery.

    PubMed

    Washko, George R; Martinez, Fernando J; Hoffman, Eric A; Loring, Stephen H; Estépar, Raúl San José; Diaz, Alejandro A; Sciurba, Frank C; Silverman, Edwin K; Han, MeiLan K; Decamp, Malcolm; Reilly, John J

    2010-03-01

    Previous investigations have identified several potential predictors of outcomes from lung volume reduction surgery (LVRS). A concern regarding these studies has been their small sample size, which may limit generalizability. We therefore sought to examine radiographic and physiologic predictors of surgical outcomes in a large, multicenter clinical investigation, the National Emphysema Treatment Trial. To identify objective radiographic and physiological indices of lung disease that have prognostic value in subjects with chronic obstructive pulmonary disease being evaluated for LVRS. A subset of the subjects undergoing LVRS in the National Emphysema Treatment Trial underwent preoperative high-resolution computed tomographic (CT) scanning of the chest and measures of static lung recoil at total lung capacity (SRtlc) and inspiratory resistance (Ri). The relationship between CT measures of emphysema, the ratio of upper to lower zone emphysema, CT measures of airway disease, SRtlc, Ri, the ratio of residual volume to total lung capacity (RV/TLC), and both 6-month postoperative changes in FEV(1) and maximal exercise capacity were assessed. Physiological measures of lung elastic recoil and inspiratory resistance were not correlated with improvement in either the FEV(1) (R = -0.03, P = 0.78 and R = -0.17, P = 0.16, respectively) or maximal exercise capacity (R = -0.02, P = 0.83 and R = 0.08, P = 0.53, respectively). The RV/TLC ratio and CT measures of emphysema and its upper to lower zone ratio were only weakly predictive of postoperative changes in both the FEV(1) (R = 0.11, P = 0.01; R = 0.2, P < 0.0001; and R = 0.23, P < 0.0001, respectively) and maximal exercise capacity (R = 0.17, P = 0.0001; R = 0.15, P = 0.002; and R = 0.15, P = 0.002, respectively). CT assessments of airway disease were not predictive of change in FEV(1) or exercise capacity in this cohort. The RV/TLC ratio and CT measures of emphysema and its distribution are weak but statistically significant

  11. A Survey of Cone-beam Computed Tomographic Use among Endodontic Practitioners in the United States.

    PubMed

    Setzer, Frank C; Hinckley, Nathan; Kohli, Meetu R; Karabucak, Bekir

    2017-05-01

    Cone-beam computed tomographic (CBCT) imaging is an emerging technology for clinical endodontic practice. The aim of this study was to investigate the acceptance, accessibility, and usage of CBCT imaging among American Association of Endodontists members in the United States by means of an online survey. An invitation to participate in a web-based survey was sent to 3076 members of the American Association of Endodontists. The survey consisted of 8 questions on demographics, access to CBCT machines, field of view (FOV), frequency of use for particular applications, and reasons in case CBCT was not used. A total of 1083 participants completed the survey, giving an overall completed response rate of 35.2%; 80.30% of the participants had access to a CBCT scan, of which 50.69% (n = 443) were on-site and 49.31% (n = 431) were off-site, and 19.30% of all respondents denied having access to CBCT imaging. Limited FOV was used by 55.26% participants, 22.37% used larger FOV formats, and the remaining 22.37% were not sure about the format. There was a significantly greater usage of CBCT technology in residency programs (n = 78/84 [92.86%]) compared with practitioners who had finished an endodontic specialty program (n = 796/999 [79.68%]) (χ(2) = 10.30, P = .02). Practitioners used CBCT imaging "frequent" or "always" for internal or external resorptions (47.28%), preoperatively for surgical retreatment or intentional replantation (45.34%), missing canals (25.39%), preoperatively for nonsurgical retreatments (24.91%), differential diagnosis (21.16%), identifying periradicular lesions (18.26%), calcified cases (13.54%), immature teeth (4.71%), and to assess healing (3.87%). There was a significant difference in on-site and off-site CBCT imaging use for any of these applications (P < .001). Prevalent reasons for not using CBCT technology were cost (53.79%) and lack of installation space (8.29%). General concerns were expressed about resolution limitations, radiation

  12. Virtual pathology: a new paradigm for interpretation of computed tomographic colonography

    NASA Astrophysics Data System (ADS)

    Reed, Judd E.; Johnson, C. Daniel

    1998-06-01

    Computed tomographic colonography (CTC or virtual colonoscopy) is a new technique for imaging the colon for the detection of colorectal neoplasm. Early clinical assessment of this procedure has shown that the performance of this test is acceptable for colorectal screening examinations. The current version of CTC utilizes an interactive combination of axial, reformatted 2D and 3D images (from an endoluminal perspective) that are generated in real time. Navigating the colorectum within the virtual endoscopy (VE) metaphor is tedious. To alleviate this problem and free the radiologist to concentrate on diagnosis, a two pass approach has been adopted. In the first pass, the colon is semiautomatically navigated and its midline is recorded. Then in a second pass, the radiologist moves the view point (virtual endoscope tip) along this midline. This second pass alone takes from 15 to 40 minutes per scan. Additional volume rendered displays have been developed which show longer segments of the colon in formats analogous to views which may be seen at autopsy. These include a technique called planar virtual pathology' (PVP) which uses image planes of the two longitudinal transcolonic sections as cut planes within isometric volume rendered images. Scenes are rendered with rays passing orthogonally through these planes from both sides. Each of the four resulting images depicts approximately one half of the inner surface of a 12 cm bowel segment. Interpretation is performed by viewing these colon segments at approximately 8 cm intervals. In this way, the entire colon can be rapidly examined with a minimum of navigational input from the radiologist. Other virtual pathology views have also been developed. These include cylindrical virtual pathology (CVP) and mercator virtual pathology (MVP). CVP views are formed by casting rays perpendicular to a straight line which approximates a segment of the colon midline. These views are analogous to the result of splitting a segment of

  13. Physiological and Computed Tomographic Predictors of Outcome from Lung Volume Reduction Surgery

    PubMed Central

    Washko, George R.; Martinez, Fernando J.; Hoffman, Eric A.; Loring, Stephen H.; Estépar, Raúl San José; Diaz, Alejandro A.; Sciurba, Frank C.; Silverman, Edwin K.; Han, MeiLan K.; DeCamp, Malcolm; Reilly, John J.

    2010-01-01

    Rationale: Previous investigations have identified several potential predictors of outcomes from lung volume reduction surgery (LVRS). A concern regarding these studies has been their small sample size, which may limit generalizability. We therefore sought to examine radiographic and physiologic predictors of surgical outcomes in a large, multicenter clinical investigation, the National Emphysema Treatment Trial. Objectives: To identify objective radiographic and physiological indices of lung disease that have prognostic value in subjects with chronic obstructive pulmonary disease being evaluated for LVRS. Methods: A subset of the subjects undergoing LVRS in the National Emphysema Treatment Trial underwent preoperative high-resolution computed tomographic (CT) scanning of the chest and measures of static lung recoil at total lung capacity (SRtlc) and inspiratory resistance (Ri). The relationship between CT measures of emphysema, the ratio of upper to lower zone emphysema, CT measures of airway disease, SRtlc, Ri, the ratio of residual volume to total lung capacity (RV/TLC), and both 6-month postoperative changes in FEV1 and maximal exercise capacity were assessed. Measurements and Main Results: Physiological measures of lung elastic recoil and inspiratory resistance were not correlated with improvement in either the FEV1 (R = −0.03, P = 0.78 and R = –0.17, P = 0.16, respectively) or maximal exercise capacity (R = –0.02, P = 0.83 and R = 0.08, P = 0.53, respectively). The RV/TLC ratio and CT measures of emphysema and its upper to lower zone ratio were only weakly predictive of postoperative changes in both the FEV1 (R = 0.11, P = 0.01; R = 0.2, P < 0.0001; and R = 0.23, P < 0.0001, respectively) and maximal exercise capacity (R = 0.17, P = 0.0001; R = 0.15, P = 0.002; and R = 0.15, P = 0.002, respectively). CT assessments of airway disease were not predictive of change in FEV1 or exercise capacity in this cohort. Conclusions: The RV/TLC ratio and CT measures

  14. Evaluating the Toxicity Reduction With Computed Tomographic Ventilation Functional Avoidance Radiation Therapy.

    PubMed

    Faught, Austin M; Miyasaka, Yuya; Kadoya, Noriyuki; Castillo, Richard; Castillo, Edward; Vinogradskiy, Yevgeniy; Yamamoto, Tokihiro

    2017-10-01

    Computed tomographic (CT) ventilation imaging is a new modality that uses 4-dimensional (4D) CT information to calculate lung ventilation. Although retrospective studies have reported on the reduction in dose to functional lung, no work to our knowledge has been published in which the dosimetric improvements have been translated to a reduction in the probability of pulmonary toxicity. Our work estimates the reduction in toxicity for CT ventilation-based functional avoidance planning. Seventy previously treated lung cancer patients who underwent 4DCT imaging were used for the study. CT ventilation maps were calculated with 4DCT deformable image registration and a density change-based algorithm. Pneumonitis was graded on the basis of imaging and clinical presentation. Maximum likelihood methods were used to generate normal tissue complication probability (NTCP) models predicting grade 2 or higher (2+) and grade 3+ pneumonitis as a function of dose (V5 Gy, V10 Gy, V20 Gy, V30 Gy, and mean dose) to functional lung. For 30 patients a functional plan was generated with the goal of reducing dose to the functional lung while meeting Radiation Therapy Oncology Group 0617 constraints. The NTCP models were applied to the functional plans and the clinically used plans to calculate toxicity reduction. By the use of functional avoidance planning, absolute reductions in grade 2+ NTCP of 6.3%, 7.8%, and 4.8% were achieved based on the mean fV20 Gy, fV30 Gy, and mean dose to functional lung metrics, respectively. Absolute grade 3+ NTCP reductions of 3.6%, 4.8%, and 2.4% were achieved with fV20 Gy, fV30 Gy, and mean dose to functional lung. Maximum absolute reductions of 52.3% and 16.4% were seen for grade 2+ and grade 3+ pneumonitis for individual patients. Our study quantifies the possible toxicity reduction from CT ventilation-based functional avoidance planning. Reductions in grades 2+ and 3+ pneumonitis were 7.1% and 4.7% based on mean dose-function metrics, with

  15. Dual-source computed tomographic coronary angiography: image quality and stenosis diagnosis in patients with high heart rates.

    PubMed

    Zheng, Minwen; Li, Jiayi; Xu, Jian; Chen, Kang; Zhao, Hongliang; Huan, Yi

    2009-01-01

    We sought to evaluate prospectively the effects of heart rate and heart-rate variability on dual-source computed tomographic coronary image quality in patients whose heart rates were high, and to determine retrospectively the accuracy of dual-source computed tomographic diagnosis of coronary artery stenosis in the same patients.We compared image quality and diagnostic accuracy in 40 patients whose heart rates exceeded 70 beats/min with the same data in 40 patients whose heart rates were 70 beats/min or slower. In both groups, we analyzed 1,133 coronary arterial segments. Five hundred forty-five segments (97.7%) in low-heart-rate patients and 539 segments (93.7%) in high-heart-rate patients were of diagnostic image quality. We considered P < 0.05 to be statistically significant. No statistically significant differences between the groups were found in diagnostic-image quality scores of total segments or of any coronary artery, nor were any significant differences found between the groups in the accurate diagnosis of angiographically significant stenosis.Calcification was the chief factor that affected diagnostic accuracy. In high-heart-rate patients, heart-rate variability was significantly related to the diagnostic image quality of all segments (P = 0.001) and of the left circumflex coronary artery (P = 0.016). Heart-rate variability of more than 5 beats/min most strongly contributed to an inability to evaluate segments in both groups. When heart rates rose, the optimal reconstruction window shifted from diastole to systole.The image quality of dual-source computed tomographic coronary angiography at high heart rates enables sufficient diagnosis of stenosis, although variability of heart rates significantly deteriorates image quality.

  16. Collateral Status on Baseline Computed Tomographic Angiography and Intra-Arterial Treatment Effect in Patients With Proximal Anterior Circulation Stroke.

    PubMed

    Berkhemer, Olvert A; Jansen, Ivo G H; Beumer, Debbie; Fransen, Puck S S; van den Berg, Lucie A; Yoo, Albert J; Lingsma, Hester F; Sprengers, Marieke E S; Jenniskens, Sjoerd F M; Lycklama À Nijeholt, Geert J; van Walderveen, Marianne A A; van den Berg, René; Bot, Joseph C J; Beenen, Ludo F M; Boers, Anna M M; Slump, Cornelis H; Roos, Yvo B W E M; van Oostenbrugge, Robert J; Dippel, Diederik W J; van der Lugt, Aad; van Zwam, Wim H; Marquering, Henk A; Majoie, Charles B L M

    2016-03-01

    Recent randomized trials have proven the benefit of intra-arterial treatment (IAT) with retrievable stents in acute ischemic stroke. Patients with poor or absent collaterals (preexistent anastomoses to maintain blood flow in case of a primary vessel occlusion) may gain less clinical benefit from IAT. In this post hoc analysis, we aimed to assess whether the effect of IAT was modified by collateral status on baseline computed tomographic angiography in the Multicenter Randomized Clinical Trial of Endovascular Treatment of Acute Ischemic Stroke in the Netherlands (MR CLEAN). MR CLEAN was a multicenter, randomized trial of IAT versus no IAT. Primary outcome was the modified Rankin Scale at 90 days. The primary effect parameter was the adjusted common odds ratio for a shift in direction of a better outcome on the modified Rankin Scale. Collaterals were graded from 0 (absent) to 3 (good). We used multivariable ordinal logistic regression analysis with interaction terms to estimate treatment effect modification by collateral status. We found a significant modification of treatment effect by collaterals (P=0.038). The strongest benefit (adjusted common odds ratio 3.2 [95% confidence intervals 1.7-6.2]) was found in patients with good collaterals (grade 3). The adjusted common odds ratio was 1.6 [95% confidence intervals 1.0-2.7] for moderate collaterals (grade 2), 1.2 [95% confidence intervals 0.7-2.3] for poor collaterals (grade 1), and 1.0 [95% confidence intervals 0.1-8.7] for patients with absent collaterals (grade 0). In MR CLEAN, baseline computed tomographic angiography collateral status modified the treatment effect. The benefit of IAT was greatest in patients with good collaterals on baseline computed tomographic angiography. Treatment benefit appeared less and may be absent in patients with absent or poor collaterals. URL: http://www.trialregister.nl and http://www.controlled-trials.com. Unique identifier: (NTR)1804 and ISRCTN10888758, respectively. © 2016

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

    PubMed

    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.

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

    PubMed Central

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

    2014-01-01

    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 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 ERN’s were found in the medial-frontal cortex following false positive responses. Cadets who made fewer errors also produced deeper ERN’s, 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. PMID:19813139

  19. Root Canal Treatment of Mandibular Second Premolar with Three Separate Roots and Canals Using Spiral Computed Tomographic

    PubMed Central

    Hariharavel, V. P.; Kumar, A. Ashok; Ganesh, C.; Aravindhan, R.

    2014-01-01

    Anatomic and internal morphology of a root canal system is more complex and differs for each individual tooth of which mandibular premolars have earned the reputation for having aberrant anatomy. The occurrence of three canals with three separate foramina in mandibular second premolars is very rare. A wider knowledge on both clinical and radiological anatomy especially spiral computed tomographic is absolutely essential for the success of endodontic treatment. These teeth may require skillful and special root canal special shaping and obturating techniques. This paper reports an unusual case of a mandibular second premolar with atypical canal pattern that was successfully treated endodontically. PMID:25101187

  20. Good visibility of TITAN-2 coronary stents demonstrable on cardiac computer tomographic angiography: a report of 2 cases.

    PubMed

    Ong, Paul Jau; Jau, Ong Paul; Ho, Hee Hwa; Hwa, Ho Hee; Jafary, Fahim Haider; Haider, Jafary Fahim; Loh, Kwok Kong; Kong, Loh Kwok; Ooi, Yau Wei; Wei, Ooi Yau; Wong, Chun Pong; Pong, Wong Chun; Foo, David; David, Foo

    2011-09-01

    Numerous studies have sought to assess stent patency by cardiac computer tomographic angiography (CCTA) in comparison with invasive coronary angiography in patients who had undergone percutaneous coronary stenting. Even with newer generation scanners, CCTA has been of limited value in the assessment of the revascularized patient. The main reason being blooming artifact from metallic stents often obscures stent luminal dimension, making the stented segment unassessable. We report on a novel finding of good visibility of TITAN-2 coronary stents demonstrable on CCTA for 2 patients and discuss the possible mechanism and potential implications of this observation.

  1. Overcoming the effects of false positives and threshold bias in graph theoretical analyses of neuroimaging data

    PubMed Central

    Drakesmith, M.; Caeyenberghs, K.; Dutt, A.; Lewis, G.; David, A.S.; Jones, D.K.

    2015-01-01

    Graph theory (GT) is a powerful framework for quantifying topological features of neuroimaging-derived functional and structural networks. However, false positive (FP) connections arise frequently and influence the inferred topology of networks. Thresholding is often used to overcome this problem, but an appropriate threshold often relies on a priori assumptions, which will alter inferred network topologies. Four common network metrics (global efficiency, mean clustering coefficient, mean betweenness and smallworldness) were tested using a model tractography dataset. It was found that all four network metrics were significantly affected even by just one FP. Results also show that thresholding effectively dampens the impact of FPs, but at the expense of adding significant bias to network metrics. In a larger number (n = 248) of tractography datasets, statistics were computed across random group permutations for a range of thresholds, revealing that statistics for network metrics varied significantly more than for non-network metrics (i.e., number of streamlines and number of edges). Varying degrees of network atrophy were introduced artificially to half the datasets, to test sensitivity to genuine group differences. For some network metrics, this atrophy was detected as significant (p < 0.05, determined using permutation testing) only across a limited range of thresholds. We propose a multi-threshold permutation correction (MTPC) method, based on the cluster-enhanced permutation correction approach, to identify sustained significant effects across clusters of thresholds. This approach minimises requirements to determine a single threshold a priori. We demonstrate improved sensitivity of MTPC-corrected metrics to genuine group effects compared to an existing approach and demonstrate the use of MTPC on a previously published network analysis of tractography data derived from a clinical population. In conclusion, we show that there are large biases and instability

  2. Automatic detection of lung nodules: false positive reduction using convolution neural networks and handcrafted features

    NASA Astrophysics Data System (ADS)

    Fu, Ling; Ma, Jingchen; Ren, Yacheng; Han, Youn Seon; Zhao, Jun

    2017-03-01

    Lung cancer is the leading cause of cancer deaths worldwide. Early diagnosis is critical in increasing the 5-year survival rate of lung cancer, so the efficient and accurate detection of lung nodules, potential precursors to lung cancer, is evermore important. In this paper, a computer-aided lung nodule detection system using convolution neural networks (CNN) and handcrafted features for false positive reduction is developed. The CNNs were trained with three types of images: lung CT images, their nodule-enhanced images, and their blood vessel-enhanced images. For each nodule candidate, nine 2D patches from differently oriented planes were extracted from each type of images. Patches of the same orientation from the same type of image across different candidates were used to train the CNNs independently, which were used to extract 864 features. 88 handcrafted features including intensity, shape, and texture features were also obtained from the lung CT images. The CNN features and handcrafted features were then combined to train a classifier, and a support vector machine was adopted to achieve the final classification results. The proposed method was evaluated on 1004 CT scans from the LIDC-IDRI database using 10-fold cross-validation. Compared with the traditional CNN method using only lung CT images, the proposed method boosted the sensitivity of nodule detection from 89.0% to 90.9% at 4 FPs/scan and from 71.6% to 78.2% at 1 FP/scan. This indicates that a combination of handcrafted features and CNN features from both lung CT images and enhanced images is a promising method for lung nodule detection.

  3. False positive malaria rapid diagnostic test in returning traveler with typhoid fever.

    PubMed

    Meatherall, Bonnie; Preston, Keith; Pillai, Dylan R

    2014-07-09

    Rapid diagnostic tests play a pivotal role in the early diagnosis of malaria where microscopy or polymerase chain reaction are not immediately available. We report the case of a 39 year old traveler to Canada who presented with fever, headache, and abdominal pain after visiting friends and relatives in India. While in India, the individual was not ill and had no signs or symptoms of malaria. Laboratory testing upon his return to Canada identified a false positive malaria rapid diagnostic (BinaxNOW® malaria) result for P. falciparum with coincident Salmonella Typhi bacteraemia without rheumatoid or autoimmune factors. Rapid diagnostic test false positivity for malaria coincided with the presence or absence of Salmonella Typhi in the blood. Clinicians should be aware that Salmonella Typhi infection may result in a false positive malaria rapid diagnostic test. The mechanism of this cross-reactivity is not clear.

  4. False positive malaria rapid diagnostic test in returning traveler with typhoid fever

    PubMed Central

    2014-01-01

    Background Rapid diagnostic tests play a pivotal role in the early diagnosis of malaria where microscopy or polymerase chain reaction are not immediately available. Case presentation We report the case of a 39 year old traveler to Canada who presented with fever, headache, and abdominal pain after visiting friends and relatives in India. While in India, the individual was not ill and had no signs or symptoms of malaria. Laboratory testing upon his return to Canada identified a false positive malaria rapid diagnostic (BinaxNOW® malaria) result for P. falciparum with coincident Salmonella Typhi bacteraemia without rheumatoid or autoimmune factors. Rapid diagnostic test false positivity for malaria coincided with the presence or absence of Salmonella Typhi in the blood. Conclusions Clinicians should be aware that Salmonella Typhi infection may result in a false positive malaria rapid diagnostic test. The mechanism of this cross-reactivity is not clear. PMID:25005493

  5. A closer look at self-reported suicide attempts: false positives and false negatives.

    PubMed

    Plöderl, Martin; Kralovec, Karl; Yazdi, Kurosch; Fartacek, Reinhold

    2011-02-01

    The validity of self-reported suicide attempt information is undermined by false positives (e.g., incidences without intent to die), or by unreported suicide attempts, referred to as false negatives. In a sample of 1,385 Austrian adults, we explored the occurrence of false positives and false negatives with detailed, probing questions. Removing false positives decreased the rate of suicide attempters from 4.3% to 2.7%. Probing questions also revealed 0.8% false negatives. We recommend using probing questions with both those who report a suicide attempt and those who do not report a suicide attempt to increase the validity of self-reported suicide-related information.

  6. Organ dose assessment in pediatric fluoroscopy and CT via a tomographic computational phantom of the newborn patient

    NASA Astrophysics Data System (ADS)

    Staton, Robert J.

    Of the various types of imaging modalities used in pediatric radiology, fluoroscopy and computed tomography (CT) have the highest associated radiation dose. While these examinations are commonly used for pediatric patients, little data exists on the magnitude of the organ and effective dose values for these procedures. Calculation of these dose values is necessary because of children's increased sensitivity to radiation and their long life expectancy for which to express radiation's latent effects. In this study, a newborn tomographic phantom has been implemented in a radiation transport code to evaluate organ and effective doses for newborn patients in commonly performed fluoroscopy and CT examinations. Organ doses were evaluated for voiding cystourethrogram (VCUG) fluoroscopy studies of infant patients. Time-sequence analysis was performed for videotaped VCUG studies of five different patients. Organ dose values were then estimated for each patient through Monte Carlo (MC) simulations. The effective dose values of the VCUG examination for five patients ranged from 0.6 mSv to 3.2 mSv, with a mean of 1.8 +/- 0.9 mSv. Organ doses were also assessed for infant upper gastrointestinal (UGI) fluoroscopy exams. The effective dose values of the UGI examinations for five patients ranged from 1.05 mSv to 5.92 mSv, with a mean of 2.90 +/- 1.97 mSv. MC simulations of helical multislice CT (MSCT) exams were also completed using, the newborn tomographic phantom and a stylized newborn phantom. The helical path of the source, beam shaping filter, beam profile, patient table, were all included in the MC simulations of the helical MSCT scanner. Organ doses and effective doses and their dependence on scan parameters were evaluated for newborn patients. For all CT scans, the effective dose was found to range approximately 1-13 mSv, with the largest values occurring for CAP scans. Tube current modulation strategies to reduce patient dose were also evaluated for newborn patients

  7. False positive diagnosis on (131)iodine whole-body scintigraphy of differentiated thyroid cancers.

    PubMed

    Triggiani, Vincenzo; Giagulli, Vito Angelo; Iovino, Michele; De Pergola, Giovanni; Licchelli, Brunella; Varraso, Antonio; Dicembrino, Franca; Valle, Guido; Guastamacchia, Edoardo

    2016-09-01

    (131)Iodine is used both to ablate any residual thyroid tissue or metastatic disease and to obtain whole-body diagnostic images after total thyroidectomy for differentiated thyroid cancer (DTC). Even though whole-body scan is highly accurate in showing thyroid residues as well as metastases of DTC, false positive results can be found, possibly leading to diagnostic errors and unnecessary treatments. This paper reviews the physiological and pathological processes involved as well as the strategy to recognize and rule out false positive radioiodine images.

  8. False-positive scalp activity in 131I imaging associated with hair coloring.

    PubMed

    Yan, Di; Doss, Mohan; Mehra, Ranee; Parsons, Rosaleen B; Milestone, Barton N; Yu, Jian Q

    2013-03-01

    A patient with metastatic papillary thyroid carcinoma (after surgical resection of tumor and positive lymph nodes) undergoing thyroid ablation therapy with (131)I is described. Whole-body scintigraphy was performed 1 wk after ablation therapy to evaluate the presence of residual disease. The whole-body images demonstrated an artifact caused by tracer accumulation in the patient's scalp related to recent hair coloring. Common etiologies of false-positive (131)I scintigraphic findings are briefly reviewed. The importance of taking preventative measures to decrease the number of false-positive findings and recognizing these findings when they occur is discussed.

  9. Quantitative real-time PCR eliminates false-positives in colony screening PCR.

    PubMed

    Skarratt, Kristen K; Fuller, Stephen J

    2014-01-01

    We report an alternative approach to colony screening using real-time PCR (qPCR) which can be used instead of the traditional end-point PCR to eliminate false-positives and reduce processing times. False-positive transformants can easily be distinguished from true-positives by comparing Ct values derived from qPCR amplification curves. In addition, the use of qPCR allows for more efficient processing since a gel electrophoresis step is not required and the screening process is no longer limited by the capacity of the gel apparatus.

  10. False positive results for antibody to HIV in two men with systemic lupus erythematosus.

    PubMed Central

    Esteva, M H; Blasini, A M; Ogly, D; Rodríguez, M A

    1992-01-01

    False positive results were obtained for HIV tests in two men with active systemic lupus erythematosus (SLE) who were suspected of being infected with HIV because of fever, weight loss, lymphadenopathy, and inflammatory myopathy. Enzyme linked immunosorbent assays (ELISAs) for HIV were twice positive when tested three times over a period of six months. Western blot analysis showed reactivity against the gp41 band in patient 1. False positive results for HIV tests can occur in patients with SLE, potentially leading to an erroneous diagnosis of HIV infection. PMID:1417140

  11. A novel spherical shell filter for reducing false positives in automatic detection of pulmonary nodules in thoracic CT scans

    NASA Astrophysics Data System (ADS)

    van de Leemput, Sil; Dorssers, Frank; Ehteshami Bejnordi, Babak

    2015-03-01

    Early detection of pulmonary nodules is crucial for improving prognosis of patients with lung cancer. Computer-aided detection of lung nodules in thoracic computed tomography (CT) scans has a great potential to enhance the performance of the radiologist in detecting nodules. In this paper we present a computer-aided lung nodule detection system for computed tomography (CT) scans that works in three steps. The system first segments the lung using thresholding and hole filling. From this segmentation the system extracts candidate nodules using Laplacian of Gaussian. To reject false positives among the detected candidate nodules, multiple established features are calculated. We propose a novel feature based on a spherical shell filter, which is specifically designed to distinguish between vascular structures and nodular structures. The performance of the proposed CAD system was evaluated by partaking in the ANODE09 challenge, which presents a platform for comparing automatic nodule detection programs. The results from the challenge show that our CAD system ranks third among the submitted works, demonstrating the efficacy of our proposed CAD system. The results also show that our proposed spherical shell filter in combination with conventional features can significantly reduce the number of false positives from the detected candidate nodules.

  12. Sex Differences in Patients With CAM Deformities With Femoroacetabular Impingement: 3-Dimensional Computed Tomographic Quantification.

    PubMed

    Yanke, Adam B; Khair, M Michael; Stanley, Robert; Walton, David; Lee, Simon; Bush-Joseph, Charles A; Espinoza Orías, Alejandro; Espinosa Orias, Alejandro A; Inoue, Nozomu; Nho, Shane J

    2015-12-01

    To determine if significant differences exist between male and female CAM deformities using quantitative 3-dimensional (3D) volume and location analysis. Retrospective analysis of preoperative computed tomographic (CT) scans for 138 femurs (69 from male patients and 69 from female patients) diagnosed with impingement from November 2009 to November 2011 was completed. Those patients who presented with hip complaints and had a history, physical examination (limited range of motion, positive impingement signs), plain radiographs (anteroposterior pelvis, 90° Dunn view, false profile view), and magnetic resonance images consistent with femoroacetabular impingement (FAI) and in whom a minimum of 6 months of conservative therapy (oral anti-inflammatory agents, physical therapy, and activity modification) had failed were indicated for arthroscopic surgery and had a preoperative CT scan. Scans were segmented, converted to point cloud data, and analyzed with a custom-written computer program. Analysis included mean CAM height and volume, head radius, and femoral version. Differences were analyzed using an unpaired t test with significance set at P < .05. Female patients had greater femoral anteversion compared with male patients (female patients, 15.5° ± 8.3°; male patients, 11.3° ± 9.0°; P = .06). Male femoral head radii were significantly larger than female femoral heads (female patients, 22.0 ± 1.3 mm; male patients, 25.4 ± 1.3 mm; P < .001). Male CAM height was significantly larger than that in female patients (female patients, 0.66 ± 0.61 mm; male patients, 1.51 ± 0.75 mm; P < .001). Male CAM volume was significantly larger as well (male patients, 433 ± 471 mm(3); female patients, 89 ± 124 mm(3); P < .001). These differences persisted after normalizing height (P < .001) and volume (P < .001) to femoral head radius. Average clock face distribution was from the 1:09 o'clock position ± the 2:51 o'clock position to the 3:28 o'clock position ± the 1:59 o

  13. Evaluation of causes of false positive Tc-99m IDA scintigraphy in biliary atresia

    SciTech Connect

    Kumura, D.; Miller, J.H.; Sinatra, F.

    1985-05-01

    Forty-four patients between 1 1/2 and 25 weeks of age with conjugated hyperbilirubinemia were evaluated by Tc-99m IDA scintigraphy for possible biliary atresia (BA). There were 21 true positives, defined as no GI activity by twenty-four hours after pretreatment with phenobarbital 5 mg/kg/day for three days. There were 15 true negatives, eight false positives and no false negatives. Causes for false positives included five neonatal hepatitis and three patients with of cholestasis associated with septo-optic dyplasia. Sensitivity of this procedure was 100% and specificity was 65% with an accuracy of 82%. Recognizing septo-optic dysplasia as a cause of cholestasis clinically further increases specificity to 79% and an accuracy of 90%. In the remaining false positives with neonatal hepatitis, four had poor hepatic uptake, however two of sixteen BA cases also had poor hepatic uptake. If reduced hepatic activity is used as a criterion against BA, specificity increases to 95% but sensitivity decreases to 88%. Septo-optic dysplasia is an unusual syndrome characterized by absent septum pellucidum, hypoplasia of one or both optic nerves, and hypothalamic pituitary dysfunction. Recognition of this entity will reduce false positive interpretation. Poor hepatic uptake with no twenty-four hour GI activity is helpful in excluding BA.

  14. False Positives in Multiple Regression: Unanticipated Consequences of Measurement Error in the Predictor Variables

    ERIC Educational Resources Information Center

    Shear, Benjamin R.; Zumbo, Bruno D.

    2013-01-01

    Type I error rates in multiple regression, and hence the chance for false positive research findings, can be drastically inflated when multiple regression models are used to analyze data that contain random measurement error. This article shows the potential for inflated Type I error rates in commonly encountered scenarios and provides new…

  15. Doxylamine: a cause for false-positive gas chromatographic assay for phencyclidine.

    PubMed

    Schaldenbrand, J D; McClatchey, K D; Patel, J A; Muilenberg, M J

    1981-01-01

    A 25-year-old white woman ingested an unknown quantity of doxylamine succinate and flurazepam. Urine immunoassay screen (EMIT-dau) was positive for benzodiazopine and negative for phencyclidine. Subsequent gas chromatographic assay of the urine revealed a markedly positive assay for phencyclidine. Doxylamine was ultimately found to be the cause for the false-positive gas chromatographic assay for phencyclidine.

  16. On False-Positive and False-Negative Decisions with a Mastery Test.

    ERIC Educational Resources Information Center

    Wilcox, Rand R.

    Wilcox (1977) examines two methods of estimating the probability of a false-positive on false-negative decision with a mastery test. Both procedures make assumptions about the form of the true score distribution which might not give good results in all situations. In this paper, upper and lower bounds on the two possible error types are described…

  17. False-positive outcome and drug residue in milk samples over withdrawal times.

    PubMed

    Kang, J H; Jin, J H; Kondo, F

    2005-03-01

    This study was conducted to identify false-positive outcomes and drug residues in milk samples over withdrawal times and to determine whether the positive results were caused by drug residues or natural inhibitors. A total of 73 milk samples over withdrawal times after the last intramammary infusion were collected from each treated quarter of cows and tested using the Delvotest SP assay. Reading time was 150, 165, and 180 min, and results of samples were recorded according to the color of the well containing the control milk sample. There were 24, 20, and 12 positive samples at the reading times of 150, 165, and 180 min, respectively. All 24 positive milk samples were heated at 82 degrees C for 5 min and retested to verify that the positive results were caused by drug residues or natural inhibitors. Twenty-one samples that exhibited positive results were negative after heat treatment, and drug residues were not identified by LacTek and Charm tests. However, 3 samples that exhibited positive results from heat treatment of 82 degrees C were positive for drugs. In our study, most positive results (89%) in the milk samples over withdrawal times were false-positive results by natural inhibitors. Moreover, the heat treatment is a fast, simple, and inexpensive method to remove false-positive results and has no effect on positive samples containing drugs. We suggest that heat treatment before screening tests is an effective way to reduce false-positive results in the milk samples.

  18. False-Positive Results of Enzyme Immunoassays for Human Immunodeficiency Virus in Patients with Uncomplicated Malaria

    PubMed Central

    Gasasira, Anne F.; Dorsey, Grant; Kamya, Moses R.; Havlir, Diane; Kiggundu, Moses; Rosenthal, Philip J.; Charlebois, Edwin D.

    2006-01-01

    Malaria may impact upon human immunodeficiency virus (HIV) test results. We evaluated two HIV enzyme immunoassays (EIAs) by testing 1,965 Ugandans with malaria. We found poor positive predictive values (53% and 76%), particularly with younger age. Combining EIAs eliminated false positives but missed 21% of true positives. Performance of HIV EIAs in malaria may be unsatisfactory. PMID:16891532

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

    EPA Science Inventory

    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...

  20. Aerosolized vaccine as an unexpected source of false-positive Bordetella pertussis PCR results.

    PubMed

    Salimnia, Hossein; Lephart, Paul R; Asmar, Basim I; Prebelich, Dawn; Paulson, Erin; Fairfax, Marilynn R

    2012-02-01

    When 13 of 13 nasal wash specimens from a single pediatrician's office tested positive for low quantities of Bordetella pertussis DNA, we suspected prelaboratory contamination. Investigation revealed that Pentacel and Adacel vaccines contain high copy numbers of B. pertussis DNA, which can be aerosolized, causing false-positive B. pertussis PCR results.

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

    EPA Science Inventory

    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...

  2. Are False-Positive Rates Leading to an Overestimation of Noise-Induced Hearing Loss?

    ERIC Educational Resources Information Center

    Schlauch, Robert S.; Carney, Edward

    2011-01-01

    Purpose: To estimate false-positive rates for rules proposed to identify early noise-induced hearing loss (NIHL) using the presence of notches in audiograms. Method: Audiograms collected from school-age children in a national survey of health and nutrition (the Third National Health and Nutrition Examination Survey [NHANES III]; National Center…

  3. Are False-Positive Rates Leading to an Overestimation of Noise-Induced Hearing Loss?

    ERIC Educational Resources Information Center

    Schlauch, Robert S.; Carney, Edward

    2011-01-01

    Purpose: To estimate false-positive rates for rules proposed to identify early noise-induced hearing loss (NIHL) using the presence of notches in audiograms. Method: Audiograms collected from school-age children in a national survey of health and nutrition (the Third National Health and Nutrition Examination Survey [NHANES III]; National Center…

  4. Generalized site occupancy models allowing for false positive and false negative errors

    USGS Publications Warehouse

    Royle, J. Andrew; Link, W.A.

    2006-01-01

    Site occupancy models have been developed that allow for imperfect species detection or ?false negative? observations. Such models have become widely adopted in surveys of many taxa. The most fundamental assumption underlying these models is that ?false positive? errors are not possible. That is, one cannot detect a species where it does not occur. However, such errors are possible in many sampling situations for a number of reasons, and even low false positive error rates can induce extreme bias in estimates of site occupancy when they are not accounted for. In this paper, we develop a model for site occupancy that allows for both false negative and false positive error rates. This model can be represented as a two-component finite mixture model and can be easily fitted using freely available software. We provide an analysis of avian survey data using the proposed model and present results of a brief simulation study evaluating the performance of the maximum-likelihood estimator and the naive estimator in the presence of false positive errors.

  5. Research: Association of Low-Amplitude QRSs with False-Positive Asystole Alarms.

    PubMed

    Pelter, Michele M; Fidler, Richard; Hu, Xiao

    2016-01-01

    Although electrocardiographic monitoring is valuable for continuous surveillance of intensive care unit (ICU) patients, false alarms are common and have been cited as a cause of alarm fatigue. ANSI/AAMI EC12:2002 states that electrocardiograms (ECGs) should not detect a QRS if the waveform is less than 0.15 mV (1.5 mm) for adult patients, in order to avoid mislabeling P waves or baseline noise as QRSs during complete heart block or asystole. However, ECG software algorithms often use more conservative QRS thresholds, which may result in false-positive asystole alarms in patients with low-amplitude QRS complexes. To 1) assess the frequency of low QRS amplitude in a group of ICU patients with one or more false-positive asystole alarms and 2) determine whether low-amplitude QRSs are associated with false-positive asystole alarms during continuous ECG monitoring. Hospital-acquired standard 12-lead ECGs were examined in a group of 82 ICU patients who had one or more false-positive asystole alarms. Low QRS amplitude was defined as a unidirectional (only positive or negative) QRS of less than 5 mm in two of four leads (I, II, III, and V1). Low-amplitude QRSs were present in 45 of 82 (55%) patients. The presence of low-amplitude QRSs did not differ according to age, sex, or race. Patients treated in the cardiac ICU had the highest proportion of low-amplitude QRSs. An equivalent proportion of patients had false-positive asystole alarms by group (no low-amplitude QRSs 95% vs. low-amplitude QRSs 87%; P = 0.229). Eight patients (10%) had both true- and false-positive asystole alarms (two [5%] with no low-amplitude QRSs and six [13%] with low-amplitude QRSs; P = 0.229). Low-amplitude QRS, as assessed from hospital 12-lead ECGs, occurs frequently and is more common in cardiac ICU patients. However, this ECG feature did not identify patients with false-positive asystole alarms during continuous ECG monitoring.

  6. Can computed tomographic gastrography and multiplanar reformatting aid the laparoscopic surgeon in planning a gastric resection? A pictorial essay.

    PubMed

    Zalev, Arthur H; Grantcharov, Teodor; Deitel, Wayne

    2013-02-01

    To assess the value and feasibility of computed tomographic gastrography and multiplanar reformatting in the preoperative evaluation of patients undergoing laparoscopic gastric resection. Fourteen patients with gastric lesions were included in the study. A supine scan was performed after a hypotonic drug, an effervescent agent, and intravenous contrast. This was followed by delayed prone and decubitus scans. We created multiplanar reformats, transparency rendered images, and endoluminal images. The tumours were localized, and distances were measured to the esophagogastric junction and the pylorus. Eleven patients underwent resections. Seven had laparoscopic wedge resections for aberrant pancreas (1 patient), carcinoid (1), Castleman disease (1), and gastrointestinal stromal tumours (GISTs) (4). One patient had an open subtotal gastrectomy for carcinoma due to adhesions. One had a hand-assisted sleeve resection for a gastrointestinal stromal tumour. Two had hand-assisted total gastrectomies for carcinoma and a GIST. For surgical planning, the surgeon rated the imaging extremely useful in 7 and useful in 4. Imaging was extremely useful or useful to localize laparoscopically invisible tumours in 6 patients and to relate tumours to the esophagogastric junction or pylorus and to assess localized vs extensive resection in 8. Correlation was excellent between the preoperative imaging and the intraoperative findings. Computed tomographic gastrography and multiplanar reformatting are useful aids in preoperative planning of laparoscopic gastric resections. Copyright © 2013 Canadian Association of Radiologists. Published by Elsevier Inc. All rights reserved.

  7. Tuning the cache memory usage in tomographic reconstruction on standard computers with Advanced Vector eXtensions (AVX).

    PubMed

    Agulleiro, Jose-Ignacio; Fernandez, Jose-Jesus

    2015-06-01

    Cache blocking is a technique widely used in scientific computing to minimize the exchange of information with main memory by reusing the data kept in cache memory. In tomographic reconstruction on standard computers using vector instructions, cache blocking turns out to be central to optimize performance. To this end, sinograms of the tilt-series and slices of the volumes to be reconstructed have to be divided into small blocks that fit into the different levels of cache memory. The code is then reorganized so as to operate with a block as much as possible before proceeding with another one. This data article is related to the research article titled Tomo3D 2.0 - Exploitation of Advanced Vector eXtensions (AVX) for 3D reconstruction (Agulleiro and Fernandez, 2015) [1]. Here we present data of a thorough study of the performance of tomographic reconstruction by varying cache block sizes, which allows derivation of expressions for their automatic quasi-optimal tuning.

  8. The early development of medial coronoid disease in growing Labrador retrievers: radiographic, computed tomographic, necropsy and micro-computed tomographic findings.

    PubMed

    Lau, S F; Wolschrijn, C F; Hazewinkel, H A W; Siebelt, M; Voorhout, G

    2013-09-01

    Medial coronoid disease (MCD) encompasses lesions of the entire medial coronoid process (MCP), both of the articular cartilage and the subchondral bone. To detect the earliest signs of MCD, radiography and computed tomography were used to monitor the development of MCD in 14 Labrador retrievers, from 6 to 7 weeks of age until euthanasia. The definitive diagnosis of MCD was based on necropsy and micro-computed tomography findings. The frequency of MCD in the dogs studied was 50%. Radiographic findings did not provide evidence of MCD, ulnar subtrochlear sclerosis or blunting of the cranial edge of the MCP. Computed tomography was more sensitive (30.8%) than radiography (0%) in detecting early MCD, with the earliest signs detectable at 14 weeks of age. A combination of the necropsy and micro-computed tomography findings of the MCP showed that MCD was manifested as a lesion of only the subchondral bone in dogs <18 weeks of age. In all dogs (affected and unaffected), there was close contact between the base of the MCP and the proximal radial head in the congruent joints. Computed tomography and micro-computed tomography findings indicated that the lesions of MCD probably originated at the base of the MCP. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. The effects of gestational age and birth weight on false-positive newborn-screening rates.

    PubMed

    Slaughter, Jonathan L; Meinzen-Derr, Jareen; Rose, Susan R; Leslie, Nancy D; Chandrasekar, Ram; Linard, Sharon M; Akinbi, Henry T

    2010-11-01

    Newborn-screening false-positive rates (FPRs) are disproportionately increased in preterm infants. The objective of this study was to determine variation in newborn screening FPRs according to birth weight and gestational age. Our secondary objective was to examine the effect of postnatal age on FPRs in preterm infants. The Ohio State Newborn Screening Program Database was analyzed to determine the overall and birth weight-specific FPRs for 18 analytes. Data were stratified into birth weight categories (<1000 g, 1000-1499 g, 1500-2499 g, 2500-3999 g, and >4000 g). In addition, to examine the effect of postnatal age on FPRs, we examined the 2 analytes with the highest FPRs, thyrotropin with back-up thyroxine and 17-hydroxyprogesterone, in infants whose gestational age was <32 weeks, determined on the basis of postnatal age at screening. Data from 448 766 neonates were reviewed. Infants with very low birth weight (VLBW) comprised 1.9% of the study cohort, but accounted for 18% of false-positive results. For 14 of 18 analytes studied, FPRs increased with decreasing birth weight/gestational age and were significantly increased in infants with VLBW compared with infants who weighed 2500 to 3999 g (P < .001). Thyrotropin/back-up thyroxine and 17-hydroxyprogesterone accounted for 62% of total false-positive results in VLBW infants. When blood specimens were collected at a postnatal age of ≥ 48 hours in infants born at <32 weeks, a 44% relative reduction in 17-hydroxyprogesterone false-positive results was detected. False-positive newborn-screening rates are disproportionately increased in VLBW infants. FPRs may be reduced by delaying screening of <32 weeks' gestation, preterm infants until 24 to 48 hours' postnatal age.

  10. Psychological consequences of false-positive screening mammograms in the UK.

    PubMed

    Bond, Mary; Pavey, Toby; Welch, Karen; Cooper, Chris; Garside, Ruth; Dean, Sarah; Hyde, Christopher J

    2013-04-01

    To identify the psychological effects of false-positive screening mammograms in the UK. Systematic review of all controlled studies and qualitative studies of women with a false-positive screening mammogram. The control group participants had normal mammograms. All psychological outcomes including returning for routine screening were permitted. All studies had a narrative synthesis. The searches returned seven includable studies (7/4423). Heterogeneity was such that meta-analysis was not possible. Studies using disease-specific measures found that, compared to normal results, there could be enduring psychological distress that lasted up to 3 years; the level of distress was related to the degree of invasiveness of the assessment. At 3 years the relative risks were, further mammography, 1.28 (95% CI 0.82 to 2.00), fine needle aspiration 1.80 (95% CI 1.17 to 2.77), biopsy 2.07 (95% CI 1.22 to 3.52) and early recall 1.82 (95% CI 1.22 to 2.72). Studies that used generic measures of anxiety and depression found no such impact up to 3 months after screening. Evidence suggests that women with false-positive mammograms have an increased likelihood of failing to reattend for routine screening, relative risk 0.97 (95% CI 0.96 to 0.98) compared with women with normal mammograms. Having a false-positive screening mammogram can cause breast cancer-specific distress for up to 3 years. The degree of distress is related to the invasiveness of the assessment. Women with false-positive mammograms are less likely to return for routine assessment than those with normal ones.

  11. False positivity of circumsporozoite protein (CSP)-ELISA in zoophilic anophelines in Bangladesh.

    PubMed

    Bashar, Kabirul; Tuno, Nobuko; Ahmed, Touhid Uddin; Howlader, Abdul Jabber

    2013-02-01

    Circumsporozoite protein enzyme-linked immunosorbent assays (CSP-ELISAs) are widely used for malaria vector identification throughout the world. However, several studies have reported false-positive results when using this method. The present study was conducted to estimate the frequency of false positives among anopheline species in malaria endemic areas of Bangladesh. In total, 4724 Anopheles females belonging to 25 species were collected and tested for Plasmodium falciparum, Plasmodium vivax-210, and P. vivax-247 CSP. Initially, 144 samples tested positive using routine CSP-ELISA, but the number of positive results declined to 85 (59%) when the samples were tested after heating at 100°C for 10min to remove false-positive specimens. Ten species, Anopheles annularis, Anopheles baimaii, Anopheles barbirostris, Anopheles jeyporiensis, Anopheles karwari, Anopheles kochi, Anopheles minimus s.l., Anopheles peditaeniatus, Anopheles philippinensis, and Anopheles vagus were CSP-positive. The highest and lowest infection rates were found in An. baimaii (4/25, 16.0%) and An. jeyporiensis (1/139, 0.67%), respectively. A significant correlation was found (regression analysis, R(2)=0.49, F=8.25, P<0.05) between human blood index results and the true CSP-positive ratios in 15 Anopheles species. We confirmed that false-positive reactions occurred more frequently in zoophilic species. The relatively high proportion of false positives (40%) that was found in this study should warn malaria epidemiologists working in the field to be cautious when interpreting ELISA results. Copyright © 2012 Elsevier B.V. All rights reserved.

  12. New Constraints on the False Positive Rate for Short-Period Kepler Planet Candidates

    NASA Astrophysics Data System (ADS)

    Colón, Knicole D.; Morehead, Robert C.; Ford, Eric B.

    2015-01-01

    The Kepler space mission has discovered thousands of potential planets orbiting other stars, thereby setting the stage for in-depth studies of different populations of planets. We present new multi-wavelength transit photometry of small (Rp < 6 Earth radii), short-period (P < 6 days) Kepler planet candidates acquired with the Gran Telescopio Canarias. Multi-wavelength transit photometry allows us to search for wavelength-dependent transit depths and subsequently identify eclipsing binary false positives (which are especially prevalent at the shortest orbital periods). We combine these new observations of three candidates with previous results for five other candidates (Colón & Ford 2011 and Colón, Ford, & Morehead 2012) to provide new constraints on the false positive rate for small, close-in candidates. In our full sample, we identify four candidates as viable planets and four as eclipsing binary false positives. We therefore find a higher false positive rate for small, close-in candidates compared to the lower false positive rate of ~10% determined by other studies for the full sample of Kepler planet candidates (e.g. Fressin et al. 2013). We also discuss the dearth of known planets with periods less than ~2.5 days and radii between ~3 and 11 Earth radii (the so-called 'sub-Jovian desert'), since the majority of the candidates in our study are located in or around this 'desert.' The lack of planets with these orbital and physical properties is not expected to be due to observational bias, as short-period planets are generally easier to detect (especially if they are larger or more massive than Earth). We consider the implications of our results for the other ~20 Kepler planet candidates located in this desert. Characterizing these candidates will allow us to better understand the formation processes of this apparently rare class of planets.

  13. Reducing False-Positive Pregnancy Test Results in Patients With Cancer.

    PubMed

    McCash, Samuel I; Goldfrank, Deborah J; Pessin, Melissa S; Ramanathan, Lakshmi V

    2017-09-05

    To assess whether the use of a laboratory test specific for intact human chorionic gonadotropin (hCG) would reduce the number of false-positive pregnancy test results. From October 21, 2014, to January 20, 2015, and April 1, 2015, to June 2, 2015, all serum samples sent for pregnancy screening at a large cancer center with a value of 5 milli-international units/mL or greater total β-hCG were frozen and stored and then retested using intact hCG reagent. We compared the accuracy of total β-hCG and intact hCG results for the diagnosis of clinically confirmed pregnancy. A negative test was defined as 14 milli-international units/mL or less, our current institutional cutoff. We also assessed a cutoff of less than 5 milli-international units/mL, a historical cutoff to rule out pregnancy. We performed intact hCG testing on 64 patient samples, of which 34 had originally resulted positive when tested for total β-hCG. These included 21 cases of clinically confirmed pregnancy and 13 false-positive cases. No women were pregnant when their intact hCG concentration was 14 milli-international units/mL or less, and all pregnancies were detected at and above this concentration. Intact hCG reduced the number of false-positive pregnancy test results from 13 to 1, a 92% reduction (95% CI 64-99%), corresponding to a reduction in the false-positive rate from 38% (95% CI 22-56%) to 3% (95% CI 1-15%). The use of intact hCG reagent in patients with cancer reduces the rate of false-positive pregnancy test results without increasing the rate of false-negative test results.

  14. Case Reports of Aripiprazole Causing False-Positive Urine Amphetamine Drug Screens in Children.

    PubMed

    Kaplan, Justin; Shah, Pooja; Faley, Brian; Siegel, Mark E

    2015-12-01

    Urine drug screens (UDSs) are used to identify the presence of certain medications. One limitation of UDSs is the potential for false-positive results caused by cross-reactivity with other substances. Amphetamines have an extensive list of cross-reacting medications. The literature contains reports of false-positive amphetamine UDSs with multiple antidepressants and antipsychotics. We present 2 cases of presumed false-positive UDSs for amphetamines after ingestion of aripiprazole. Case 1 was a 16-month-old girl who accidently ingested 15 to 45 mg of aripiprazole. She was lethargic and ataxic at home with 1 episode of vomiting containing no identifiable tablets. She remained sluggish with periods of irritability and was admitted for observation. UDS on 2 consecutive days came back positive for amphetamines. Case 2 was of a 20-month-old girl who was brought into the hospital after accidental ingestion of an unknown quantity of her father's medications which included aripiprazole. UDS on the first day of admission came back positive only for amphetamines. Confirmatory testing with gas chromatography-mass spectrometry (GC-MS) on the blood and urine samples were also performed for both patients on presentation to detect amphetamines and were subsequently negative. Both patients returned to baseline and were discharged from the hospital. To our knowledge, these cases represent the first reports of false-positive amphetamine urine drug tests with aripiprazole. In both cases, aripiprazole was the drug with the highest likelihood of causing the positive amphetamine screen. The implications of these false-positives include the possibility of unnecessary treatment and monitoring of patients.

  15. Optimizing contrast media injection protocols in state-of-the art computed tomographic angiography.

    PubMed

    Lell, Michael M; Jost, Gregor; Korporaal, Johannes Georg; Mahnken, Andreas Horst; Flohr, Thomas G; Uder, Michael; Pietsch, Hubertus

    2015-03-01

    Very short acquisition times and the increasing use of low-kilovolt protocols in standard computed tomographic (CT) angiography (CTA) examinations demand modifications in the contrast media (CM) injection regimen. The aim of this study was to optimize the use of tube voltage-adjusted CM delivery parameters, especially injection duration and iodine delivery rate (IDR), in thoracoabdominal CTA in a porcine model. Eight pigs (53-72 kg) were examined with a third-generation dual-source CT system with a dynamic CTA protocol (4-dimensional spiral, 454-mm scan length, 2.5-second temporal resolution, 70-second total acquisition time). Six CM injection protocols were applied in randomized order and intraindividually compared. The standard CTA protocol was performed at 120 kV, with an injection of 300 mg iodine/kg body weight and a flow of 5 mL/s (IDR, 1.5 g/s). On the basis of phantom measurements for the low-kilovolt CTA protocols, the iodine dosage was adjusted to 150 mg iodine/kg (70 kV) and 210 mg iodine/kg (90 kV). Therefore, either the IDR was kept constant and the injection time was reduced, or the injection time was kept constant and the IDR was reduced by modifying the CM flow or concentration. Time attenuation curves, time to peak, and peak enhancement were calculated for different locations within the aorta, renal arteries, and large veins. The heart rates were comparable among the different injection protocols (66.9-78.1 beats per minute). The average injection peak pressure depended on the flow rate and CM concentration and ranged from 42.9 to 114.7 psi. The average arterial peak enhancement was comparable for protocols with identical injection times and reduced IDR (362.4 HU [standard 120-kV protocol; 300 mg iodine/kg; IDR, 1.5 g/s], 360.0 HU [70 kV; 150 mg iodine/kg; IDR, 0.75 g/s], 365.4 HU [70 kV; 150 mg iodine/kg; IDR, 0.75 g/s; CM, 150 mg iodine/mL], 344.3 HU [90 kV; 210 mg iodine/kg; IDR, 1.1 g/s]). Higher peak enhancements could be achieved by applying

  16. Use of CA-125 Tests and Computed Tomographic Scans for Surveillance in Ovarian Cancer.

    PubMed

    Esselen, Katharine M; Cronin, Angel M; Bixel, Kristin; Bookman, Michael A; Burger, Robert A; Cohn, David E; Cristea, Mihaela; Griggs, Jennifer J; Levenback, Charles F; Mantia-Smaldone, Gina; Meyer, Larissa A; Matulonis, Ursula A; Niland, Joyce C; Sun, Charlotte; O'Malley, David M; Wright, Alexi A

    2016-11-01

    A 2009 randomized clinical trial demonstrated that using cancer antigen 125 (CA-125) tests for routine surveillance in ovarian cancer increases the use of chemotherapy and decreases patients' quality of life without improving survival, compared with clinical observation. The Society of Gynecologic Oncology guidelines categorize CA-125 testing as optional and discourage the use of radiographic imaging for routine surveillance. To date, few studies have examined the use of CA-125 tests in clinical practice. To examine the use of CA-125 tests and computed tomographic (CT) scans in clinical practice before and after the 2009 randomized clinical trial and to estimate the economic effect of surveillance testing. A prospective cohort of 1241 women with ovarian cancer in clinical remission after completion of primary cytoreductive surgery and chemotherapy at 6 National Cancer Institute-designated cancer centers between January 1, 2004, and December 31, 2011, was followed up through December 31, 2012, to study the use of CA-125 tests and CT scans before and after 2009. Data analysis was conducted from April 9, 2014, to March 28, 2016. The use of CA-125 tests and CT scans before and after 2009. Secondary outcomes included the time from CA-125 markers doubling to retreatment among women who experienced a rise in CA-125 markers before and after 2009, and the costs associated with surveillance testing using 2015 Medicare reimbursement rates. Among 1241 women (mean [SD] age 59 [12] years; 1112 white [89.6%]), the use of CA-125 testing and CT scans was similar during the study period. During 12 months of surveillance, the cumulative incidence of patients undergoing 3 or more CA-125 tests was 86% in 2004-2009 vs 91% in 2010-2012 (P = .95), and the cumulative incidence of patients undergoing more than 1 CT scan was 81% in 2004-2009 vs 78% in 2010-2012 (P = .50). Among women whose CA-125 markers doubled (n = 511), there was no significant difference in the time to

  17. [Dobutamine-related coronary spasm among patients with false positive dobutamine stress echocardiography: Prevalence and predictors].

    PubMed

    Aboukhoudir, F; Aboukhoudir, I; Pansieri, M; Rekik, S

    2015-11-01

    Dobutamine stress echocardiography (DSE) is being consistently used as an exercise-independent stress modality aimed at the detection of coronary artery disease (CAD) and the evaluation of myocardial ischemia. It may though occasionally induce coronary vasospasm. In this study, we aimed to evaluate the prevalence and predictors of dobutamine-related coronary spasm in patients without known CAD and false positive DSE (positive DSE but no significant coronary lesions on angiogram). Three thousand nine hundred and fifty-two patients referred to our echocardiography laboratory for DSE between January 2010 and May 2012 were prospectively investigated. Those with positive DSE underwent coronary angiograms with systematic methylergometrine intracoronary injection in case of absence of significant coronary stenosis or spontaneous occlusive coronary spasm. Patients with spontaneous occlusive coronary spasm or positive methylergometrine test but no significant stenoses were enrolled and compared with those with positive DSE but no coronary lesions nor spontaneous or induced spasm ("true" false positive DSE). Twenty-nine patients with DSE-related vasospasm (19.4% of positive DES without known CAD) were compared with 56 patients with no lesions and no spasm ("true" false positive DSE). They were more frequently smokers (72.4% vs 37.5%; P=0.003); they had more frequently dyslipidemia (79.3% vs 43%; P=0.001); they also had a larger ischemic area at peak DSE (3.4 segments vs 2.7 segments; P=0.05). On multivariate analysis, dyslipidemia (HR=10.7; 95% CI=[2.7-42.1]; P=0.001) and active smoking (HR=6.1; 95% CI=[1.7-21.1]; P=0.004) were found to be independent predictors of spasm-related DSE rather than "true" false positive DSE. DSE-related coronary spasm is present in a significant proportion of patients with erroneously labelled "false" positive DSE and should systematically be ruled out. Dyslipidemia and active smoking were independent predictors of spasm rather than "true" false

  18. Risk of Breast Cancer in Women with False-Positive Results according to Mammographic Features.

    PubMed

    Castells, Xavier; Torá-Rocamora, Isabel; Posso, Margarita; Román, Marta; Vernet-Tomas, Maria; Rodríguez-Arana, Ana; Domingo, Laia; Vidal, Carmen; Baré, Marisa; Ferrer, Joana; Quintana, María Jesús; Sánchez, Mar; Natal, Carmen; Espinàs, Josep A; Saladié, Francina; Sala, María

    2016-08-01

    Purpose To assess the risk of breast cancer in women with false-positive screening results according to radiologic classification of mammographic features. Materials and Methods Review board approval was obtained, with waiver of informed consent. This retrospective cohort study included 521 200 women aged 50-69 years who underwent screening as part of the Spanish Breast Cancer Screening Program between 1994 and 2010 and who were observed until December 2012. Cox proportional hazards regression analysis was used to estimate the age-adjusted hazard ratio (HR) of breast cancer and the 95% confidence interval (CI) in women with false-positive mammograms as compared with women with negative mammograms. Separate models were adjusted for screen-detected and interval cancers and for screen-film and digital mammography. Time without a breast cancer diagnosis was plotted by using Kaplan-Meier curves. Results When compared with women with negative mammograms, the age-adjusted HR of cancer in women with false-positive results was 1.84 (95% CI: 1.73, 1.95; P < .001). The risk was higher in women who had calcifications, whether they were (HR, 2.73; 95% CI: 2.28, 3.28; P < .001) or were not (HR, 2.24; 95% CI: 2.02, 2.48; P < .001) associated with masses. Women in whom mammographic features showed changes in subsequent false-positive results were those who had the highest risk (HR, 9.13; 95% CI: 8.28, 10.07; P < .001). Conclusion Women with false-positive results had an increased risk of breast cancer, particularly women who had calcifications at mammography. Women who had more than one examination with false-positive findings and in whom the mammographic features changed over time had a highly increased risk of breast cancer. Previous mammographic features might yield useful information for further risk-prediction models and personalized follow-up screening protocols. (©) RSNA, 2016 Online supplemental material is available for this article.

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

    PubMed Central

    Hannoush, Zeina C.; Palacios, Juan D.; Kuker, Russ A.

    2017-01-01

    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. PMID:28246564

  20. Diagnostic Issues and Controversies in DSM-5: Return of the False Positives Problem.

    PubMed

    Wakefield, Jerome C

    2016-01-01

    The fifth revision of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) was the most controversial in the manual's history. This review selectively surveys some of the most important changes in DSM-5, including structural/organizational changes, modifications of diagnostic criteria, and newly introduced categories. It analyzes why these changes led to such heated controversies, which included objections to the revision's process, its goals, and the content of altered criteria and new categories. The central focus is on disputes concerning the false positives problem of setting a valid boundary between disorder and normal variation. Finally, this review highlights key problems and issues that currently remain unresolved and need to be addressed in the future, including systematically identifying false positive weaknesses in criteria, distinguishing risk from disorder, including context in diagnostic criteria, clarifying how to handle fuzzy boundaries, and improving the guidelines for "other specified" diagnosis.

  1. False-positive amphetamine toxicology screen results in three pregnant women using labetalol.

    PubMed

    Yee, Lynn M; Wu, Danny

    2011-02-01

    Labetalol is commonly used for control of hypertension in pregnancy. A component of the workup for new-onset hypertension in pregnancy often includes a urine drug screen. A labetalol metabolite is structurally similar to amphetamine and methamphetamine, thus causing potential cross-reactivity in drug immunoassays. We present one case of cocaine-induced hypertensive crisis superimposed on chronic hypertension and two cases of severe preeclampsia for which patients required escalating doses of labetalol for hypertension, with subsequent false-positive amphetamine urine drug screen results. In pregnant women requiring labetalol for treatment of hypertensive disease, a urine drug screen may be falsely positive for amphetamines and methamphetamines. Providers should be cognizant of this possibility when interpreting the results of urine drug screens.

  2. False-positive and false-negative rates in meconium drug testing.

    PubMed

    Moore, C; Lewis, D; Leikin, J

    1995-11-01

    To determine the number of false-negative results produced by inefficient extraction of drugs from meconium, three published procedures were compared by using previously confirmed positive and negative meconium specimens. The methods were not equivalent in their ability to extract drugs from the matrix. To determine the number of false positives reported by the use of screen-only (unconfirmed) results, 535 screen-positive meconium specimens were subjects to confirmation by gas chromatography-mass spectrometry. Fifty-seven percent of the samples were confirmed positive for one or more of the drugs under investigation, showing that a false-positive rate as high as 43% may exist when unconfirmed screening results are used.

  3. KUIPER BELT OBJECT OCCULTATIONS: EXPECTED RATES, FALSE POSITIVES, AND SURVEY DESIGN

    SciTech Connect

    Bickerton, S. J.; Welch, D. L.; Kavelaars, J. J. E-mail: welch@physics.mcmaster.ca

    2009-05-15

    A novel method of generating artificial scintillation noise is developed and used to evaluate occultation rates and false positive rates for surveys probing the Kuiper Belt with the method of serendipitous stellar occultations. A thorough examination of survey design shows that (1) diffraction-dominated occultations are critically (Nyquist) sampled at a rate of 2 Fsu{sup -1}, corresponding to 40 s{sup -1} for objects at 40 AU, (2) occultation detection rates are maximized when targets are observed at solar opposition, (3) Main Belt asteroids will produce occultations light curves identical to those of Kuiper Belt Objects (KBOs) if target stars are observed at solar elongations of: 116{sup 0} {approx}< {epsilon} {approx}< 125 deg., or 131 deg. {approx}< {epsilon} {approx}< 141 deg., and (4) genuine KBO occultations are likely to be so rare that a detection threshold of {approx}>7-8{sigma} should be adopted to ensure that viable candidate events can be disentangled from false positives.

  4. False positive of an immunochromatography kit for detection of norovirus in neonatal feces.

    PubMed

    Niizuma, Takahiro; Obinata, Kaoru; Ikari, Hiromi; Kamata, Ayako; Lee, Tsubasa; Kinoshita, Keiji; Shimizu, Toshiaki

    2013-02-01

    Norovirus was detected in the feces from five neonates in the growing care unit by a rapid immunochromatography (ICG) kit. However, confirmation using reverse transcription polymerase chain reaction (RT-PCR), RT-loop-mediated isothermal amplification (RT-LAMP), and nested RT-PCR methods showed negative results from all the feces. In addition, the ICG test for the detection of norovirus was positive for four cases out of the 16 feces from other asymptomatic neonates/infants. Only one feces out of the four samples was positive by RT-LAMP. In this study, among the factors related to false positives with the norovirus ICG kit, there were no differences regarding the commencement of feeding, nutrition, and sample collection methods. Since the false positive rate of ICG in the diagnosis of norovirus infection in neonates and early infancy is high, ICG is not an appropriate method, and it is necessary to confirm the results using reliable methods like RT-PCR.

  5. Copy-Number Variation and False Positive Prenatal Aneuploidy Screening Results

    PubMed Central

    Snyder, Matthew W.; Simmons, LaVone E.; Kitzman, Jacob O.; Coe, Bradley P.; Henson, Jessica M.; Daza, Riza M.; Eichler, Evan E.; Shendure, Jay; Gammill, Hilary S.

    2015-01-01

    SUMMARY Investigations of noninvasive prenatal screening for aneuploidy by analysis of circulating cell-free DNA (cfDNA) have shown high sensitivity and specificity in both high-risk and low-risk cohorts. However, the overall low incidence of aneuploidy limits the positive predictive value of these tests. Currently, the causes of false positive results are poorly understood. We investigated four pregnancies with discordant prenatal test results and found in two cases that maternal duplications on chromosome 18 were the likely cause of the discordant results. Modeling based on population-level copy-number variation supports the possibility that some false positive results of noninvasive prenatal screening may be attributable to large maternal copy-number variants. (Funded by the National Institutes of Health and others.) PMID:25830323

  6. Copy-number variation and false positive prenatal aneuploidy screening results.

    PubMed

    Snyder, Matthew W; Simmons, LaVone E; Kitzman, Jacob O; Coe, Bradley P; Henson, Jessica M; Daza, Riza M; Eichler, Evan E; Shendure, Jay; Gammill, Hilary S

    2015-04-23

    Investigations of noninvasive prenatal screening for aneuploidy by analysis of circulating cell-free DNA (cfDNA) have shown high sensitivity and specificity in both high-risk and low-risk cohorts. However, the overall low incidence of aneuploidy limits the positive predictive value of these tests. Currently, the causes of false positive results are poorly understood. We investigated four pregnancies with discordant prenatal test results and found in two cases that maternal duplications on chromosome 18 were the likely cause of the discordant results. Modeling based on population-level copy-number variation supports the possibility that some false positive results of noninvasive prenatal screening may be attributable to large maternal copy-number variants. (Funded by the National Institutes of Health and others.).

  7. False-positive cerebrospinal fluid cryptococcus antigen in Libman-Sacks endocarditis.

    PubMed

    Isseh, Iyad N; Bourgi, Kassem; Nakhle, Asaad; Ali, Mahmoud; Zervos, Marcus J

    2016-12-01

    Cryptococcus meningoencephalitis is a serious opportunistic infection associated with high morbidity and mortality in immunocompromised hosts, particularly patients with advanced AIDS disease. The diagnosis is established through cerebrospinal fluid (CSF) cryptococcus antigen detection and cultures. Cryptococcus antigen testing is usually the initial test of choice due its high sensitivity and specificity along with the quick availability of the results. We hereby report a case of a false-positive CSF cryptococcus antigen assay in a patient with systemic lupus erythematosus presenting with acute confusion. While initial CSF evaluation revealed a positive cryptococcus antigen assay, the patient's symptoms were inconsistent with cryptococcus meningoencephalitis. A repeat CSF evaluation, done 3 days later, revealed a negative CSF cryptococcus antigen assay. Given the patient's active lupus disease and the elevated antinuclear antibody titers, we believe that the initial positive result was a false positive caused by interference from autoantibodies.

  8. Doxylamine toxicity: seizure, rhabdomyolysis and false positive urine drug screen for methadone.

    PubMed

    Syed, Husnain; Som, Sumit; Khan, Nazia; Faltas, Wael

    2009-01-01

    The present report highlights the possible adverse effects of doxylamine, a common over the counter sleep aid. Doxylamine is an antihistamine that at toxic doses can cause anticholinergic effects, including seizures, rhabdomyolysis and death. The following case describes a patient with doxylamine toxicity who presented with seizure and confusion. Our patient was managed symptomatically, and remained otherwise stable throughout his hospitalisation. This case is atypical in terms of a delayed rhabdomyolysis and a false positive urine drug screen test for methadone. There is evidence that doxylamine at toxic levels can lead to false positives for methadone and phencyclidine testing using immunoassay-based urine drug screen kits. Urine drug screen testing on patients who are hospitalised is typically performed using immunoassays. However, in certain cases confirmatory secondary testing may be required. Doxylamine is prone to abuse and knowledge of the clinical presentation of its toxicity and the management of acute overdose can be life-saving.

  9. Modeling false positive detections in species occurrence data under different study designs.

    PubMed

    Chambert, Thierry; Miller, David A W; Nichols, James D

    2015-02-01

    The occurrence of false positive detections in presence-absence data, even when they occur infrequently, can lead to severe bias when estimating species occupancy patterns. Building upon previous efforts to account for this source of observational error, we established a general framework to model false positives in occupancy studies and extend existing modeling approaches to encompass a broader range of sampling designs. Specifically, we identified three common sampling designs that are likely to cover most scenarios encountered by researchers. The different designs all included ambiguous detections, as well as some known-truth data, but their modeling differed in the level of the model hierarchy at which the known-truth information was incorporated (site level or observation level). For each model, we provide the likelihood, as well as R and BUGS code needed for implementation. We also establish a clear terminology and provide guidance to help choosing the most appropriate design and modeling approach.

  10. Unusual false-positive radioiodine whole-body scans in patients with differentiated thyroid carcinoma.

    PubMed

    Salvatori, M; Saletnich, I; Rufini, V; Troncone, L

    1997-06-01

    Radioiodine whole-body imaging is the most accurate method in the diagnosis of metastases from differentiated thyroid cancer. However, false-positive images rarely occur. The authors report unusual cases of thymic hyperplasia and post-traumatic skull changes mimicking mediastinal, skull, or cerebral metastases. Nonthyroidal causes were diagnosed by other radionuclide studies (bone and brain scintigraphy) and CT scans. Follow-up and undetectable thyroglobulin levels helped confirm the benign cause.

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

    PubMed

    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.

  12. PCR evaluation of false-positive signals from two automated blood-culture systems.

    PubMed

    Karahan, Z Ceren; Mumcuoglu, Ipek; Guriz, Haluk; Tamer, Deniz; Balaban, Neriman; Aysev, Derya; Akar, Nejat

    2006-01-01

    Rapid detection of micro-organisms from blood is one of the most critical functions of a diagnostic microbiology laboratory. Automated blood-culture systems reduce the time needed to detect positive cultures, and reduce specimen handling. The false-positive rate of such systems is 1-10%. In this study, the presence of pathogens in 'false-positive' bottles obtained from BACTEC 9050 (Becton Dickinson) and BacT/Alert (Biomérieux) systems was investigated by eubacterial and fungal PCR. A total of 169 subculture-negative aerobic blood-culture bottles (104 BacT/Alert and 65 BACTEC) were evaluated. Both fungal and eubacterial PCRs were negative for all BACTEC bottles. Fungal PCR was also negative for the BacT/Alert system, but 10 bottles (9.6%) gave positive results by eubacterial PCR. Sequence analysis of the positive PCR amplicons indicated the presence of the following bacteria (number of isolates in parentheses): Pasteurella multocida (1), Staphylococcus epidermidis (2), Staphylococcus hominis (1), Micrococcus sp. (1), Streptococcus pneumoniae (1), Corynebacterium spp. (2), Brachibacterium sp. (1) and Arthrobacter/Rothia sp. (1). Antibiotic usage by the patients may be responsible for the inability of the laboratory to grow these bacteria on subcultures. For patients with more than one false-positive bottle, molecular methods can be used to evaluate the microbial DNA in these bottles. False positives from the BACTEC system may be due to elevated patient leukocyte counts or the high sensitivity of the system to background increases in CO(2) concentration.

  13. The magnitude and challenge of false-positive newborn screening test results.

    PubMed

    Kwon, C; Farrell, P M

    2000-07-01

    This study examined for the first time to our knowledge the national data available from newborn screening programs in the United States and determined the salient characteristics of various screening tests for 3 hereditary metabolic disorders and 2 congenital endocrinopathies with emphasis on positive predictive values (PPVs) to delineate the magnitude of false-positive results. Reports published by the Council of Regional Networks for Genetic Services for 1990 through 1994 were examined carefully, paying particular attention to phenylketonuria, galactosemia, biotinidase deficiency, congenital hypothyroidism, and congenital adrenal hyperplasia (CAH). Because of recent improvements in data collecting, reporting, and tabulating, we used data from 1993 and 1994 to determine the apparent sensitivity, specificity, relative incidence rates, and PPVs for the 5 disorders. For biotinidase deficiency and CAH, we also calculated relative incidence rates and PPVs for 1991 and 1992. Our analyses revealed the following best estimates for the relative incidence rates of 5 disorders: phenylketonuria, 1:14,000; galactosemia, 1:59,000; biotinidase deficiency, 1:80,000; congenital hypothyroidism, 1:3,300; and CAH, 1:20,000. An apparent sensitivity of 100% has been reported by the various states for most of the disorders, and specificity levels are all above 99%. The PPVs, however, range from 0.5% to 6.0%. Consequently, on average, there are more than 50 false-positive results for every true-positive result identified through newborn screening in the United States. The magnitude of false-positive results generated in newborn screening programs, particularly for congenital endocrinopathies, presents a great challenge for future improvement of this important public health program. Attention must be given to improved laboratory tests, use of more specific markers, and better risk communication for families of patients with false-positive test results.

  14. Identifying false-positive ST-elevation myocardial infarction in emergency department patients.

    PubMed

    Nfor, Tonga; Kostopoulos, Louie; Hashim, Hani; Jan, M Fuad; Gupta, Anjan; Bajwa, Tanvir; Allaqaband, Suhail

    2012-10-01

    In a push to treat ST-elevation myocardial infarction (STEMI) patients with primary percutaneous coronary intervention (PCI) within 90 min of door-to-balloon time, emergency cardiac catheterization laboratory activation protocols bypass routine clinical assessments, raising the possibility of more frequent catheterizations in patients with no culprit coronary lesion. To determine the incidence, predictors, and prognosis of false-positive STEMI. We followed a prospective cohort of patients diagnosed with STEMI by usual criteria receiving emergency cardiac catheterization with intention of primary PCI between January 2005 and December 2007 at a tertiary care center. False-positive STEMI was defined as absence of a clear culprit lesion on coronary angiography. Of 489 patients who received emergency cardiac catheterization indicated for STEMI, 54 (11.0%, 95% confidence interval [CI] 8.3-13.8) had no culprit lesion on coronary angiography. Independent predictors of false-positive STEMI were absence of chest pain (odds ratio [OR] 18.2, 95% CI 3.7-90.1), no reciprocal ST-segment changes (OR 11.8, 95% CI 5.14-27.3), fewer than three cardiovascular risk factors (OR 9.79, 95% CI 4.0-23.8), and symptom duration longer than 6h (OR 9.2, 95% CI 3.6-23.7); all p<0.001. Using predictors, we modeled a risk score that achieved 88% (95% CI 81-94%) accuracy in identifying patients with negative coronary angiography. Among the false-positive STEMI patients, 48.1% had other serious diagnoses related to their electrocardiographic findings. When the diagnosis of STEMI is in doubt, clinicians may use predictors to quickly reassess the likelihood of an alternative diagnosis. Copyright © 2012 Elsevier Inc. All rights reserved.

  15. Occupancy models for data with false positive and false negative errors and heterogeneity across sites and surveys

    Treesearch

    Paige F.B. Ferguson; Michael J. Conroy; Jeffrey Hepinstall-Cymerman; Nigel Yoccoz

    2015-01-01

    False positive detections, such as species misidentifications, occur in ecological data, although many models do not account for them. Consequently, these models are expected to generate biased inference.The main challenge in an analysis of data with false positives is to distinguish false positive and false negative...

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

    PubMed

    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.

  17. False-positive rates in two-point parametric linkage analysis.

    PubMed

    Szymczak, Silke; Simpson, Claire L; Cropp, Cheryl D; Bailey-Wilson, Joan E

    2014-01-01

    Two-point linkage analyses of whole genome sequence data are a promising approach to identify rare variants that segregate with complex diseases in large pedigrees because, in theory, the causal variants have been genotyped. We used whole genome sequence data and simulated traits provided by Genetic Analysis Workshop 18 to evaluate the proportion of false-positive findings in a binary trait using classic two-point parametric linkage analysis. False-positive genome-wide significant log of odds (LOD) scores were identified in more than 80% of 50 replicates for a binary phenotype generated by dichotomizing a quantitative trait that was simulated with a polygenic component (that was not based on any of the provided whole genome sequence genotypes). In contrast, when the trait was truly nongenetic (created by randomly assigning affected-unaffected status), the number of false-positive results was well controlled. These results suggest that when using two-point linkage analyses on whole genome sequence data, one should carefully examine regions yielding significant two-point LOD scores with multipoint analysis and that a more stringent significance threshold may be needed.

  18. False-Positive Results in Cancer Epidemiology: A Plea for Epistemological Modesty

    PubMed Central

    McLaughlin, Joseph K.; La Vecchia, Carlo; Tarone, Robert E.; Lipworth, Loren; Blot, William J.

    2008-01-01

    False-positive results are inherent in the scientific process of testing hypotheses concerning the determinants of cancer and other human illnesses. Although much of what is known about the etiology of human cancers has arisen from well-conducted epidemiological studies, epidemiology has been increasingly criticized for producing findings that are often sensationalized in the media and fail to be upheld in subsequent studies. Herein we describe examples from cancer epidemiology of likely false-positive findings and discuss conditions under which such results may occur. We suggest general guidelines or principles, including the endorsement of editorial policies requiring the prominent listing of study caveats, which may help reduce the reporting of misleading results. Increased epistemological humility regarding findings in epidemiology would go a long way to diminishing the detrimental effects of false-positive results on the allocation of limited research resources, on the advancement of knowledge of the causes and prevention of cancer, and on the scientific reputation of epidemiology and would help to prevent oversimplified interpretations of results by the media and the public. PMID:18612135

  19. Flagging False Positives Following Untargeted LC-MS Characterization of Histone Post-Translational Modification Combinations.

    PubMed

    Willems, Sander; Dhaenens, Maarten; Govaert, Elisabeth; De Clerck, Laura; Meert, Paulien; Van Neste, Christophe; Van Nieuwerburgh, Filip; Deforce, Dieter

    2017-02-03

    Epigenetic changes can be studied with an untargeted characterization of histone post-translational modifications (PTMs) by liquid chromatography-mass spectrometry (LC-MS). While prior information about more than 20 types of histone PTMs exists, little is known about histone PTM combinations (PTMCs). Because of the combinatorial explosion it is intrinsically impossible to consider all potential PTMCs in a database search. Consequentially, high-scoring false positives with unconsidered but correct alternative isobaric PTMCs can occur. Current quality controls can neither estimate the amount of unconsidered alternatives nor flag potential false positives. Here, we propose a conceptual workflow that provides such options. In this workflow, an in silico modeling of all candidate isoforms with known-to-exist PTMs is made. The most frequently occurring PTM sets of these candidate isoforms are determined and used in several database searches. This suppresses the combinatorial explosion while considering as many candidate isoforms as possible. Finally, annotations can be classified as unique or ambiguous, the latter implying false positives. This workflow was evaluated on an LC-MS data set containing 44 histone extracts. We were able to consider 60% of all candidate isoforms. Importantly, 40% of all annotations were classified as ambiguous. This highlights the need for a more thorough evaluation of modified peptide annotations.

  20. False positives complicate ancient pathogen identifications using high-throughput shotgun sequencing

    PubMed Central

    2014-01-01

    Background Identification of historic pathogens is challenging since false positives and negatives are a serious risk. Environmental non-pathogenic contaminants are ubiquitous. Furthermore, public genetic databases contain limited information regarding these species. High-throughput sequencing may help reliably detect and identify historic pathogens. Results We shotgun-sequenced 8 16th-century Mixtec individuals from the site of Teposcolula Yucundaa (Oaxaca, Mexico) who are reported to have died from the huey cocoliztli (‘Great Pestilence’ in Nahautl), an unknown disease that decimated native Mexican populations during the Spanish colonial period, in order to identify the pathogen. Comparison of these sequences with those deriving from the surrounding soil and from 4 precontact individuals from the site found a wide variety of contaminant organisms that confounded analyses. Without the comparative sequence data from the precontact individuals and soil, false positives for Yersinia pestis and rickettsiosis could have been reported. Conclusions False positives and negatives remain problematic in ancient DNA analyses despite the application of high-throughput sequencing. Our results suggest that several studies claiming the discovery of ancient pathogens may need further verification. Additionally, true single molecule sequencing’s short read lengths, inability to sequence through DNA lesions, and limited ancient-DNA-specific technical development hinder its application to palaeopathology. PMID:24568097

  1. The trazodone metabolite meta-chlorophenylpiperazine can cause false-positive urine amphetamine immunoassay results.

    PubMed

    Baron, Jason M; Griggs, David A; Nixon, Andrea L; Long, William H; Flood, James G

    2011-07-01

    Amphetamines and methamphetamines are part of an important class of drugs included in most urine drugs of abuse screening panels, and a common assay to detect these drugs is the Amphetamines II immunoassay (Roche Diagnostics). To demonstrate that meta-chlorophenylpiperazine (m-CPP), a trazodone metabolite, cross-reacts in the Amphetamines II assay, we tested reference standards of m-CPP at various concentrations (200 to 20,000 g/L). We also tested real patient urine samples containing m-CPP (detected and quantified by HPLC) with no detectable amphetamine, methamphetamine, or MDMA (demonstrated by GC MS). In both the m-CPP standards and the patient urine samples, we found a strong association between m-CPP concentration and Amphetamines II immunoreactivity (r = 0.990 for the urine samples). Further, we found that patients taking trazodone can produce urine with sufficient m-CPP to result in false-positive Amphetamines II results. At our institution, false-positive amphetamine results occur not infrequently in patients taking trazodone with at least 8 trazodone-associated false-positive results during a single 26-day period. Laboratories should remain cognizant of this interference when interpreting results of this assay.

  2. Human papillomavirus false positive cytological diagnosis in low grade squamous intraepithelial lesion.

    PubMed

    Núñez-Troconis, José; Delgado, Mariela; González, Julia; Velásquez, Jesvy; Mindiola, Raimy; Whitby, Denise; Conde, Betty; Munroe, David J

    2009-12-01

    The purpose of this study was to investigate the number of Human Papillomavirus false positive cytological diagnosis in low grade squamous intraepithelial lesions (LSIL). Three hundred and two women who assisted to an Out-Patient Gynecologic Clinic in Maracaibo, Venezuela, were recruited for this study. Each patient had the Pap smear and a cervical swab for Hybrid Capture 2 (HC2). Three cytotechnologists reviewed the Pap smears and two pathologists rescreened all of them. The cytotechnologists reported 161 (53.3%) Pap smears negatives for intraepithelial lesion (IL) or malignancy, and 141 cases (46.7%) with epithelial abnormalities. They reported 46% of 302 patients with HPV infection in Pap smear slides. The pathologists found that 241 (79.8%) Pap smears were negatives for IL or malignancy and 61 (20.2%), with abnormal Pap smears. They found 14.6% HPV infection in all Pap smears (p<0.0001; 46% vs 14.6%). The HC2 study showed that 47 samples (15.6%) were positive for HPV. The study found that 114 Pap smears (False Positive: 85%) of 134 reported by the cytotechnologists and 24 (False Positive: 43%) of 56 cytologies reported by the pathologists as LSIL, were negative for HPV infection determined by HC2 (p<0.00003). The present study suggests that the cytotechnologists overdiagnosed cellular changes associated with HPV infection in the Pap smear, increasing the FP cytological diagnosis of LSIL.

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

    PubMed

    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.

  4. The Emerging Roles of Coronary Computed Tomographic Angiography: Acute Chest Pain Evaluation and Screening for Asymptomatic Individuals

    PubMed Central

    Chien, Ning; Wang, Tzung-Dau; Chang, Yeun-Chung; Lin, Po-Chih; Tseng, Yao-Hui; Lee, Yee-Fan; Ko, Wei-Chun; Lee, Bai-Chin; Lee, Wen-Jeng

    2016-01-01

    Coronary computed tomographic angiography (CCTA) has been widely available since 2004. After that, the diagnostic accuracy of CCTA has been extensively validated with invasive coronary angiography for detection of coronary arterial stenosis. In this paper, we reviewed the updated evidence of the role of CCTA in both scenarios including acute chest pain and screening in asymptomatic adults. Several large-scale studies have been conducted to evaluate the diagnostic value of CCTA in the context of acute chest pain patients. CCTA could play a role in delivering more efficient care. For risk stratification of asymptomatic patients using CCTA, latest studies have revealed incremental benefits. Future studies evaluating the totality of plaque characteristics may be useful for determining the role of noncalcified plaque for risk stratification in asymptomatic individuals. PMID:27122947

  5. Clinical, histologic, and computed tomographic features of oral papillary squamous cell carcinoma in dogs: 9 cases (2008- 2011).

    PubMed

    Soukup, Jason W; Snyder, Christopher J; Simmons, Betsie T; Pinkerton, Marie E; Chun, Ruthanne

    2013-01-01

    Medical records of dogs diagnosed with oral papillary squamous cell carcinoma between December 2008 and April 2011 were reviewed. Information abstracted included signalment, tumor location, tumor size, computed tomographic (CT) features, evidence of metastatic disease based on cytologic examination of lymph node aspirates and thoracic radiography, treatment, surgical margins, histologic features, and treatment outcome. Dogs included in the study were all sexually altered, predominantly large breed dogs with a mean age of 3.9-years (range, 0.5 to 9.0-years). The most common location was the rostral maxilla. Invasion of underlying bone and lymphadenopathy were evident on CT imaging in most dogs. No evidence of metastasis was found on mandibular lymph node cytology and thoracic radiography. Histologic analysis revealed similar morphologic findings for all surgically resected tumors. Surgical excision with 1-2 cm margins was complete in all cases, with a mean tumor-free interval of 12.1-months.

  6. Laparoscopic Sentinel Node Biopsy Using Real-time 3-dimensional Single-photon Emission Computed Tomographic Guidance in Endometrial Cancer.

    PubMed

    Fernandez-Prada, Sara; Delgado-Sanchez, Elsa; De Santiago, Javier; Zapardiel, Ignacio

    2015-01-01

    In endometrial cancer, the histopathological analysis of the lymphatic nodes is essential to establish a correct prognosis and tailored adjuvant treatment. It is well-known that patients with early-stage endometrial cancer have a low incidence of nodal disease. In this group, systematic lymphadenectomy is not recommended. To improve the detection rate of sentinel nodes in clinical practice, new techniques are emerging like real-time 3-dimensional single-photon emission computed tomographic (SPECT) imaging. We report our experience using this innovative technique for intraoperative detection of sentinel nodes in endometrial cancer. The real-time 3-dimensional SPECT sentinel node biopsy seems to be feasible and accurate in endometrial cancer although further studies are needed to set the precision and predictive values compared with the current differed SPECT techniques and blue dye techniques. Copyright © 2015 AAGL. Published by Elsevier Inc. All rights reserved.

  7. IMAGING DIAGNOSIS: COMPUTED TOMOGRAPHIC FINDINGS IN A CASE OF ADENOSQUAMOUS CARCINOMA OF THE HEAD AND NECK IN A CAT.

    PubMed

    Chow, Kathleen Ella; Krockenberger, Mark; Collins, David

    2016-01-01

    A 15-year-old female spayed domestic long-haired cat was referred for trismus, hypersalivation, and bilateral ocular discharge. On examination, the cat showed pain on palpation of the left zygomatic arch, palpable crepitus of the frontal region, and limited retropulsion of both globes. A contrast-enhanced sinonasal computed tomographic study was performed, showing facial distortion and extensive osteolysis of the skull, extending beyond the confines of the sinonasal and paranasal cavities. Additionally, soft tissue and fluid accumulation were observed in the nasal cavities and paranasal sinuses. Postmortem biopsy samples acquired from the calvarium yielded a histologic diagnosis of sinonasal adenosquamous carcinoma, a rare and particularly aggressive neoplasm previously only reported in the esophagus of one cat.

  8. Removal of filling materials from oval-shaped canals using laser irradiation: a micro-computed tomographic study.

    PubMed

    Keleş, Ali; Arslan, Hakan; Kamalak, Aliye; Akçay, Merve; Sousa-Neto, Manoel D; Versiani, Marco Aurélio

    2015-02-01

    The aim of this study was to assess the efficacy of lasers in removing filling remnants from oval-shaped canals after retreatment procedures with rotary instruments using micro-computed tomographic imaging. The root canals of 42 mandibular canines were prepared and obturated using the warm vertical compaction technique. Retreatment was performed with rotary instruments, and the specimens were distributed in 3 groups (n = 14) according to the laser device used in a later stage of retreatment procedure: Er:YAG, Er:YAG laser-based photon-induced photoacoustic streaming, and Nd:YAG. The specimens were scanned in a micro-computed tomographic device after root canal filling and each stage of retreatment at a resolution of 13.68 μm. The percentage differences of the remaining filling material before and after laser application within and between groups were statistically compared using the paired sample t test and 1-way analysis of variance test, respectively. Significance level was set at 5%. Overall, filling residues were located mainly in the apical third and into canal irregularities after the retreatment procedures. After using rotary instruments, the mean percentage volume of the filling remnants ranged from 13%-16%, with no statistical significant difference between groups (P > .05). Within groups, additional laser application had a significant reduction in the amount of the remaining filling materials (P < .05). A comparison between groups showed that Er:YAG laser application after the use of rotary instruments had a significantly higher removal of filling remnants (~13%) than Er:YAG laser-based photon-induced photoacoustic streaming (~4%) and Nd:YAG (~3%) (P < .05). None of the retreatment procedures completely removed the filling materials. The additional use of lasers improved the removal of filling material after the retreatment procedure with rotary instruments. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights

  9. Micro-computed tomographic analysis of the root canal morphology of the distal root of mandibular first molar.

    PubMed

    Filpo-Perez, Carolina; Bramante, Clovis Monteiro; Villas-Boas, Marcelo Haas; Húngaro Duarte, Marco Antonio; Versiani, Marco Aurélio; Ordinola-Zapata, Ronald

    2015-02-01

    The aim of this study was to evaluate the morphologic aspects of the root canal anatomy of the distal root of a mandibular first molar using micro-computed tomographic analysis. One-hundred distal roots of mandibular first molars were scanned using a micro-computed tomographic device at an isotropic resolution of 19.6 μm. The percentage frequency distribution of the morphologic configuration of the root canal was performed according to the Vertucci classification system. Two-dimensional parameters (area, perimeter, roundness, aspect ratio, and major and minor diameters) and the cross-sectional shape of the root canal were analyzed in the apical third at every 1-mm interval from the main apical foramen in roots presenting Vertucci types I and II configurations (n = 79). Data were statistically compared using the Kruskal-Wallis and Dunn tests with a significance level set at 5%. Seventy-six percent of the distal roots had a single root canal. Two, three, and four canals were found in 13%, 8%, and 3% of the sample, respectively. In 13 specimens, the configuration of the root canal did not fit into Vertucci's classification. Overall, 2-dimensional parameter values significantly increased at the 3-mm level (P < .05). The prevalence of oval canals was higher at the 1-mm level and decreased at the 5-mm level in which long oval and flattened canals were more prevalent. The distal roots of the mandibular first molars showed a high prevalence of single root canals. The prevalence of long oval and flattened canals increased in the coronal direction. In 13% of the samples, canal configurations that were not included in Vertucci's configuration system were found. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  10. COMPARISON OF TRANSVERSE COMPUTED TOMOGRAPHIC EXCRETORY UROGRAPHY IMAGES AND MAXIMUM INTENSITY PROJECTION IMAGES FOR DIAGNOSING ECTOPIC URETERS IN DOGS.

    PubMed

    Secrest, Scott; Bugbee, Andrew; Waller, Kenneth; Jiménez, David A

    2017-03-01

    Computed tomographic maximum intensity projection (MIP) images have been shown to improve reader confidence in their diagnoses and to improve detection of vascular structures and pulmonary nodules. The objectives of this method comparison study were to compare transverse source computed tomographic excretory urography (CTEU) images to two, five, and 10 slab thick MIP images for diagnosing canine ectopic ureters, compare reader confidence, and evaluate interobserver agreement. Two board-certified veterinary radiologists and a board-certified small animal internist blindly reviewed transverse source CTEU and two, five, and 10 slab thick MIP images of 24 dogs enrolled in the study. Inclusion criteria included a diagnostic CTEU and either cystoscopic or surgical confirmation of the presence or absence of ureteral ectopia. Eleven dogs were confirmed to have 17 ectopic ureters at surgery and/or cystoscopically. There was no significant difference in reader diagnoses between viewing methods or between viewing methods and the surgical/cystoscopic findings (P < 0.001). Reader confidence was significantly greater on two (P = 0.0080) and five (P = 0.0009) slab thick MIP images with significant interobserver agreement between readers for all viewing methods (P values ranging between 0.0363 and <0.001). In addition, the diagnostic accuracy of MIP images was similar to or better than transverse source CTEU images, when assessed by a radiologist. The study results suggest that CTEU is a reliable imaging technique for diagnosing canine ectopic ureters among specialists of varied experience. In addition, thin slice reconstructed MIP images improve reader confidence and potentially diagnostic accuracy, and thus their use should be considered, especially in more challenging cases.

  11. Preexisting Dentinal Microcracks in Nonendodontically Treated Teeth: An Ex Vivo Micro-computed Tomographic Analysis.

    PubMed

    PradeepKumar, Angambakkam Rajasekaran; Shemesh, Hagay; Chang, Jeffrey Wen-Wei; Bhowmik, Ahendita; Sibi, Swamy; Gopikrishna, Velayutham; Lakshmi-Narayanan, Lakshmikanthanbharathi; Kishen, Anil

    2017-06-01

    This study evaluated the prevalence, location, and pattern of preexisting dentinal microcracks in roots of extracted teeth without endodontic treatment in patients from 2 age groups using micro-computed tomographic imaging. Six hundred thirty-three nonendodontically treated teeth extracted using an atraumatic procedure because of reasons unrelated to this study were collected and divided based on the patient age. Teeth were scanned with micro-computed tomographic imaging (resolution of 26.7 μm) to examine the presence of preexisting dentinal microcracks in roots. The characteristic features of preexisting dentinal microcracks determined were location, extent, length, and coronoapical distribution. Chi-square bivariate analysis was performed to assess the association between various parameters. Forty-five of 633 nonendodontically treated teeth exhibited preexisting microcracks in roots with a prevalence of 7.1%. The prevalence of preexisting microcracks was found to be 8.3% in older patients (40-70 years) compared with 3.7% in younger patients (20-39 years) (P < .050). A significant association was found between the preexisting microcracks in mandibular teeth (10.3%) when compared with maxillary teeth (2.9%) (P < .001). All preexisting microcracks were located mesiodistally; 66% occurred in the cervical and middle thirds of root. Only 33% of the preexisting microcracks were complete in nature, showing canal involvement. Complete dentinal microcracks exhibited a mean length of 6.9 mm, whereas incomplete cracks had a mean length of 3.75 mm (P < .001). Preexisting dentinal microcracks in roots of nonendodontically treated teeth occurred more often in older patients (40-70 years) in the mesiodistal direction. They were predominantly found in the cervical and middle thirds of root and were more likely to be incomplete in nature. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  12. Computed tomographic features of apical infection of equine maxillary cheek teeth: a retrospective study of 49 horses.

    PubMed

    Bühler, M; Fürst, A; Lewis, F I; Kummer, M; Ohlerth, S

    2014-07-01

    Computed tomographic (CT) studies evaluating the relevance of individual CT features of apical infection in maxillary cheek teeth are lacking. To study the prevalence and relationship of single CT features in horses with and without clinical evidence of apical infection in maxillary cheek teeth. Retrospective case-control study. Multislice CT scans of the head of 49 horses were evaluated retrospectively. Changes of the infundibulum, pulp, root, lamina dura, periodontal space and alveolar bone in maxillary cheek teeth were recorded. Single CT changes were much more prevalent in the 28 horses with clinical signs. However, infundibular changes and a nondetectable lamina dura were also common in the 21 horses without clinical evidence of apical infection. Computed tomographic abnormalities of the pulp, root, periapical bone and periodontal space and the presence of a tooth fracture were significantly related. Infundibular changes were not associated with other CT signs of apical infection. Although nondetectable lamina dura was the most frequent CT change in all teeth in both studied groups, it was most commonly a solitary feature in otherwise normal teeth. Apical infections, defined as ≥3 CT changes, occurred mainly in the 108/208, 109/209 and 110/210 (Triadan numbers) and were found only in horses with clinical evidence of apical infection, except in one horse without clinical signs that had one affected root. Combined CT changes of the pulp, root, lamina dura, periapical bone and periodontal space and the presence of a tooth fracture appear to be reliable features to diagnose apical infection in maxillary cheek teeth. As a solitary feature, a nondetectable lamina dura should be interpreted cautiously and may even be considered normal due to its minor thickness and/or too low resolution of the imaging modality. © 2013 EVJ Ltd.

  13. Preoperative Computed Tomographic Angiogram Measurement of Abdominal Muscles Is a Valuable Risk Assessment for Bulge Formation after Microsurgical Abdominal Free Flap Breast Reconstruction.

    PubMed

    Kappos, Elisabeth A; Jaskolka, Jeff; Butler, Kate; O'Neill, Anne C; Hofer, Stefan O P; Zhong, Toni

    2017-07-01

    A major shortcoming associated with abdominal tissue breast reconstruction is long-term abdominal wall morbidity. Although abdominal muscle size on computed tomographic angiography has been correlated with morbidity following many abdominal operations, it has not been studied for breast reconstruction. Therefore, the authors evaluated the association between preoperative computed tomography angiography-derived measurements of abdominal core muscles and postoperative abdominal wall morbidity after abdominal tissue breast reconstruction. In this retrospective matched case-control study of women who underwent microsurgical abdominal flap breast reconstruction at one institution between January 2011 and June 2015, the authors evaluated all cases of postoperative bulge/hernia, matched by type of abdominal flap and body mass index in a ratio of 1:2 to controls without bulge/hernia. The authors obtained morphometric measurements of abdominal core muscles on preoperative computed tomographic angiographs. Using univariable and multivariable logistic regressions, the authors examined the effects of clinical risk factors and computed tomographic angiography morphometric measurements on postoperative bulge/hernia formation. Of the 589 patients who underwent abdominal free flap breast reconstruction, symptomatic bulges/hernias were identified in 35 patients (5.9 percent). When compared to the 70 matched controls, multivariable analysis showed that decreased area of rectus abdominis muscle (OR, 0.18; p < 0.01) and increased inter-rectus abdominis distance (OR, 1.14; p < 0.01) on computed tomographic angiography were significant risk factors associated with postoperative bulge/hernia. Preoperative computed tomographic angiography allows objective measurements of the patient's abdominal muscle anatomy that provide valuable prognostic information on the risk of bulge/hernia formation following abdominally based microsurgical breast reconstruction. Risk, III.

  14. In Thyroidectomized Thyroid Cancer Patients, False-Positive I-131 Whole Body Scans Are Often Caused by Inflammation Rather Than Thyroid Cancer

    PubMed Central

    Garger, Yana Basis; Winfeld, Mathew; Friedman, Kent; Blum, Manfred

    2016-01-01

    Objective. To show that I-131 false-positive results on whole-body scans (WBSs) after thyroidectomy for thyroid cancer may be a result of inflammation unassociated with the cancer. Methods. We performed a retrospective image analysis of our database of thyroid cancer patients who underwent WBS from January 2008 to January 2012 to identify and stratify false positives. Results. A total of 564 patients underwent WBS during the study period; 96 patients were referred for 99 I-131 single-photon emission computed tomography (SPECT/CT) scans to better interpret cryptic findings. Among them, 73 scans were shown to be falsely positive; 40/73 or 54.7% of false-positive findings were a result of inflammation. Of the findings, 17 were in the head, 1 in the neck, 4 in the chest, 3 in the abdomen, and 14 in the pelvis; 1 had a knee abscess. Conclusions. In our series, inflammation caused the majority of false-positive WBSs. I-131 SPECT/CT is powerful in the differentiation of inflammation from thyroid cancer. By excluding metastatic disease, one can properly prognosticate outcome and avoid unnecessary, potentially harmful treatment of patients with thyroid cancer. PMID:26977418

  15. Frequency of false positive amphetamine screens due to bupropion using the Syva EMIT II immunoassay.

    PubMed

    Casey, Erica R; Scott, Mitchell G; Tang, Schirin; Mullins, Michael E

    2011-06-01

    Bupropion is a commonly prescribed, monocyclic antidepressant often used as an aid for smoking cessation. Several case reports have described false positive amphetamine urine drug screens (UDS) associated with bupropion. We sought to determine whether false positive amphetamine UDS due to the use of bupropion would be a frequent occurrence. We conducted an IRB-approved, retrospective chart review of all emergency department patients who underwent UDS between 1 January 2006 and 31 July 2007. All urine samples were screened using Syva EMIT II Plus immunoassay reagents. All positive screens underwent confirmation by gas chromatography (GC). We reviewed the records of patients with positive amphetamine UDS. We documented prescription use of bupropion, other antidepressants, stimulants, antipsychotics, and anti-hypertensives. We recorded evidence of polysubstance abuse (PSA) as patients who had had a documented diagnosis or laboratory evidence of abuse of at least two substances (drugs or ethanol). Of 10,011 urine drug screens, 362 (3.6%) were positive for amphetamine. GC confirmed amphetamines in 234 (65%), but failed to confirm in 128 (35%). Among the 234 confirmed, records reflected use of bupropion in three (1.3%), other antidepressants in 38 (16%), antipsychotics in 17 (8%), and amphetamine in 50 (21%). Records indicated evidence of PSA in 55 (24%). Among the 128 which failed to confirm, records reflected prescription use of bupropion in 53 (41%). None whose drug screen failed to confirm had evidence of PSA. Therapeutic use of bupropion appears to be the most frequent cause of false positive urine drug screens for amphetamines in our population.

  16. The Transiting Exoplanet Survey Satellite: Simulations of Planet Detections and Astrophysical False Positives

    NASA Astrophysics Data System (ADS)

    Sullivan, Peter W.; Winn, Joshua N.; Berta-Thompson, Zachory K.; Charbonneau, David; Deming, Drake; Dressing, Courtney D.; Latham, David W.; Levine, Alan M.; McCullough, Peter R.; Morton, Timothy; Ricker, George R.; Vanderspek, Roland; Woods, Deborah

    2015-08-01

    The Transiting Exoplanet Survey Satellite (TESS) is a NASA-sponsored Explorer mission that will perform a wide-field survey for planets that transit bright host stars. Here, we predict the properties of the transiting planets that TESS will detect along with the EB stars that produce false-positive photometric signals. The predictions are based on Monte Carlo simulations of the nearby population of stars, occurrence rates of planets derived from Kepler, and models for the photometric performance and sky coverage of the TESS cameras. We expect that TESS will find approximately 1700 transiting planets from 2× {10}5 pre-selected target stars. This includes 556 planets smaller than twice the size of Earth, of which 419 are hosted by M dwarf stars and 137 are hosted by FGK dwarfs. Approximately 130 of the R< 2 {R}\\oplus planets will have host stars brighter than {K}s=9. Approximately 48 of the planets with R< 2 {R}\\oplus lie within or near the habitable zone (0.2< S/{S}\\oplus < 2); between 2 and 7 such planets have host stars brighter than {K}s=9. We also expect approximately 1100 detections of planets with radii 2-4 {R}\\oplus , and 67 planets larger than 4 {R}\\oplus . Additional planets larger than 2 {R}\\oplus can be detected around stars that are not among the pre-selected target stars, because TESS will also deliver full-frame images at a 30-minute cadence. The planet detections are accompanied by over 1000 astrophysical false positives. We discuss how TESS data and ground-based observations can be used to distinguish the false positives from genuine planets. We also discuss the prospects for follow-up observations to measure the masses and atmospheres of the TESS planets.

  17. Reducing laparoscopic radical prostatectomy false-positive margin rates using cyanoacrylate tissue glue.

    PubMed

    Kumar, Manal; Mansour, Paul; Vesey, Sean G

    2009-10-01

    Trauma to the prostate surface from laparoscopic instruments may have a role in creating false-positive margins during laparoscopic radical prostatectomy (LRP). To determine the feasibility of using cyanoacrylate glue to repair iatrogenic lacerations and to evaluate the glue's effect on the positive surgical margin rates of LRP specimens. We used porcine kidneys as a surrogate experimental tissue to help determine the quality, robustness, and adequacy of glued repairs in experimentally created lacerations. A matched control group of unrepaired kidney specimens and kidney specimens repaired with glue were subjected to full histopathologic processing. Exposure of a nephron to surface marker ink was considered to be a "positive margin." The efficacy and impact of glue repairs on LRP specimens that had sustained iatrogenic intraoperative surface trauma were also assessed. We evaluated the success of glue repair in preventing subcapsular renal parenchymal staining. We also compared the rate of positive margins in LRP specimens with and without routine glue repair of the surface of the prostate. The glue remained effective throughout the entire laboratory process and did not interfere with histopathologic assessment. As hypothesised, cyanoacrylate glue repair of the renal lacerations prevented staining of subcapsular tissues with marker dye and therefore prevented what might otherwise be considered false-positive staining. The rate of positive margins of the 40 LRP specimens without glue repair was 35%, compared with a rate of 10% for 40 glue-repaired specimens. The limitations of the study are that follow-up was short and that the prostatectomy specimens were compared with consecutive controls rather than with matched randomised controls. Cyanoacrylate glue is a novel, inexpensive, and very effective prostate repair agent that does not interfere with histologic processing. It is possible to accurately repair iatrogenic prostate lacerations with cyanoacrylate glue and

  18. High false-positive rate of questionnaire-based restless legs syndrome diagnosis in multiple sclerosis.

    PubMed

    Mery, V; Kimoff, R J; Suarez, I; Benedetti, A; Kaminska, M; Robinson, A; Lapierre, Y; Bar-Or, A; Trojan, D A

    2015-07-01

    Restless legs syndrome (RLS) is diagnosed by self-reported symptoms. Multiple sclerosis (MS) patients have disease-related symptoms which could mimic RLS. This study assessed the: (1) false-positive rate for questionnaire-based RLS diagnosis in MS patients and (2) utility of periodic leg movements during wakefulness (PLMW) on overnight polysomnography (PSG) in identifying true-positive RLS patients. Ambulatory MS patients without known sleep disorders were recruited. Subjects completed the International RLS Study Group (IRLSG) diagnostic questionnaire (IRLDQ) and underwent full overnight PSG. IRLDQ-positive patients underwent clinical evaluation to confirm the diagnosis and completed the RLS severity scale (IRLS). Seventy-one MS patients (mean age 46.8 ± 10.4 years) were evaluated. Thirty-eight had a positive IRLDQ. RLS diagnosis was confirmed in 22, yielding a false-positive rate of 42% [95% confidence interval (CI) 26-59%], predominantly attributable to paresthesiae (n = 7), and cramps and/or muscle spasms (n = 4). IRLS scores were not significantly different between subjects with confirmed and nonconfirmed RLS. The PLMW index was significantly higher in patients with confirmed RLS (55.4 ± 41.9 vs. 29.7 ± 18.8, p = 0.03). The sensitivity of a PLMW index >70/h for true-positive IRLDQ was 8/22 = 36%, 95% CI: 17.2-59.3, and the specificity was 16/16 = 100%, 95% CI: 79.4-100. MS patients have a high false-positive rate of RLS diagnosis using a standardized questionnaire largely attributable to MS-related sensorimotor symptoms. While detailed clinical evaluation is essential for confirming RLS diagnosis, the PLMW index may provide useful adjunctive information. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Power and false-positive rate in QTL detection with near-isogenic line libraries.

    PubMed

    Falke, K C; Frisch, M

    2011-04-01

    Libraries of near-isogenic lines (NILs) were used for quantitative trait locus (QTL) detection in model species and economically important crops. The experimental design and genetic architecture of the considered traits determine the statistical properties of QTL detection. The objectives of our simulation study were to (i) investigate the population sizes required to develop NIL libraries in barley and maize, (ii) compare NIL libraries with nonoverlapping and overlapping donor segments and (iii) study the number of QTLs and the size of their effects with respect to the power and the false-positive rate of QTL detection. In barley, the development of NIL libraries with target segment lengths of 10 c and marker distances of 5 cM was possible using a BC(3)S(2) backcrossing scheme and population sizes of 140. In maize, population sizes larger than 200 were required. Selection for the recipient parent genome at markers flanking the target segments with distances between 5 and 10 cM was required for an efficient control of the false-positive rate. NIL libraries with nonoverlapping donor chromosome segments had a greater power of QTL detection and a smaller false-positive rate than libraries with overlapping segments. Major genes explaining 30% of the genotypic difference between the donor and recipient were successfully detected even with low heritabilities of 0.5, whereas for minor genes explaining 5 !or 10%, high heritabilities of 0.8 or 0.9 were required. The presented results can assist geneticists and breeders in the efficient development of NIL libraries for QTL detection.

  20. False-positive Trichuris suis egg counts in pigs in relation to coprophagia.

    PubMed

    Boes, J; Johansen, M V; Eriksen, L; Bøgh, H O; Nansen, P; Stephenson, L S

    1998-03-01

    Sixteen non-infected control pigs housed together with 16 pigs infected with Trichuris suis, excreted T. suis eggs in their faeces (range 20-4, 960 eggs per gram faeces (EPG)). When the control pigs were moved to clean pens, their egg counts dropped to zero EPG within five days. A significant correlation was found between T. suis egg counts of infected and control pigs penned together (r = 0.89, P < 0.001). These results suggest that false-positive faecal egg counts may be the result of coprophagia.

  1. Distinguishing True and False Positive Oxygen Signatures with Models and Observations

    NASA Astrophysics Data System (ADS)

    Schwieterman, Edward; Domagal-Goldman, Shawn; Meadows, Victoria; Luger, Rodrigo; Barnes, Rory; Wordsworth, Robin; Virtual Planetary Laboratory

    2015-01-01

    The spectral detection of oxygen (O2) or its photochemical bi-product ozone (O3) in a planetary atmosphere has been considered a robust signature of life because O2 is highly reactive and significant continuous abiotic sources were thought to be implausible. However, recent work has revealed the possibility that O2 or O3 may build up to spectrally detectable levels due to enhanced photolysis of O-bearing molecules by UV-active host stars (Domagal-Goldman et al. 2014, Tian et al. 2014) or photolysis of water and subsequent escape of hydrogen in thin (< 0.2 bar) atmospheres where the water is not cold trapped in the troposphere (Wordsworth et al. 2014). Additionally, there is the possibility that significant amounts of abiotic O2 could remain in post-runaway greenhouse atmospheres in the habitable zone of late type stars (Luger & Barnes 2014). Using photochemical and spectral models, we examine possible observing strategies that could discriminate between abiotic and biogenic oxygen scenarios. For example, false positives may be confirmed by the spectral detection of sibling molecules generated when large amounts of oxygen are photochemically produced (such as CO). False positives that result from H escape could be detected by measuring the mixing ratio of O2, which should be high (~1) when H escape causes O2 buildup. In contrast, true biosignatures could be confirmed by the simultaneous presence of a detectable reduced gas such as methane (CH4) which should not persist when O2 build up is caused by past H escape or by photochemical production of O2 in H-poor atmospheres. We use photochemical and spectral models to predict which combinations of planetary and stellar parameters will be most likely to produce conditions that would allow observational discrimination between true and false positives. We examine the spectral range, resolving power, and minimum integration times necessary to detect true and false positive indicators for a cross-section of model scenarios

  2. Brown tumor of bone: A potential source of false-positive thallium-201 localization

    SciTech Connect

    Yang, C.J.; Seabold, J.E.; Gurll, N.J.

    1989-07-01

    Brown tumor of bone (osteitis fibrosa cystica) should be included in the differential diagnosis of lesions that cause false-positive thallium-201 localization in patients with primary hyperparathyroidism. We report a case of a brown tumor of the upper sternum mimicking a superior mediastinal parathyroid neoplasm in a patient with persistent hyperparathyroidism 9 years after a negative neck exploration (with subtotal thyroidectomy and thymectomy). A /sup 201/TI//sup 99m/Tc pertechnetate subtraction scintigram demonstrated complete subtraction of this /sup 201/TI focus.

  3. A case of false positive Troponin I in a patient affected by cryoglobulinemic vasculitis.

    PubMed

    Bellan, M; Pirisi, M; Bellomo, G; Sainaghi, P P

    2017-05-22

    Troponin I (TnI) false positive results have been reported in patients affected by immune disorders. We report the case of a 74-year-old woman affected by cryoglobulinemic vasculitis, admitted to the Emergency Room because of a lipotimic episode. A marked elevation of TnI plasma concentration was confirmed in multiple determinations, despite the absence of symptoms or electrocardiogram findings suggesting myocardial infarction. TnI plasma concentration was reported normal after re-testing with a different commercial kit. A false TnI positivity should be considered in patients with immune disorders, especially if seropositive for rheumatoid factor, when the clinical context does not suggest myocardial infarction.

  4. Finding False Positives Planet Candidates Due To Background Eclipsing Binaries in K2

    NASA Astrophysics Data System (ADS)

    Mullally, Fergal; Thompson, Susan E.; Coughlin, Jeffrey; DAVE Team

    2016-06-01

    We adapt the difference image centroid approach, used for finding background eclipsing binaries, to vet K2 planet candidates. Difference image centroids were used with great success to vet planet candidates in the original Kepler mission, where the source of a transit could be identified by subtracting images of out-of-transit cadences from in-transit cadences. To account for K2's roll pattern, we reconstruct out-of-transit images from cadences that are nearby in both time and spacecraft roll angle. We describe the method and discuss some K2 planet candidates which this method suggests are false positives.

  5. [A pseudo-outbreak of pharyngeal gonorrhoea related to a false-positive PCR-result].

    PubMed

    Verzijl, A; Berretty, P J M; Erceg, A; Krekels, G A M; Van den Brule, A J C; Boel, C H E

    2007-03-24

    Nucleic acid amplification tests, including the polymerase chain reaction (PCR), are sensitive and specific tests that are often used for diagnosing sexually transmitted diseases (STDs). A pseudo-outbreak of pharyngeal gonorrhoea in a group of prostitutes turned out to have been caused by false-positive test results due to commensal oropharyngeal Neisseria species. Specific molecular tests may yield erroneous results. When the results of an STD study have major consequences at a legal or social level, it is advisable, in consultation with a medical microbiologist, to take a sample for culture or to carry out a second molecular test aimed at a different part of the bacterial genome.

  6. False-Positive PET/CT After Cyanoacrylate Sealing of a Pancreaticojejunostomy.

    PubMed

    Belyaev, Orlin; Munding, Johanna; Tannapfel, Andrea; Uhl, Waldemar

    2015-05-01

    In 2013, a 68-year-old male had a pancreaticoduodenectomy for pancreatic cancer. The pancreaticojejunostomy was sealed with cyanoacrylate (Dermabond) to prevent postoperative pancreatic fistula. Local recurrence of malignancy at the anastomosis was suspected 18 months later in PET/CT. Surgical revision was performed and anastomosis resected. However, histology showed no tumor recurrence, but strong inflammation and foreign-body reaction towards Dermabond. The sealant caused false-positive PET/CT findings, so its use in oncologic surgery should be abandoned.

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

    SciTech Connect

    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.

  8. False positive I-131 MIBG due to dilated renal pelvis: a case report

    SciTech Connect

    Bahar, R.H.; Mahmoud, S.; Ibrahim, A.; al-Gazzar, A.H.

    1988-12-01

    A case of false positive I-131 MIBG imaging for detection of pheochromocytoma is presented. There was an area of increased tracer uptake in the left renal region that showed steadily reducing activity over a period of three days. This raised the suspicion of a dilated renal pelvis, which was later confirmed by Tc-99m DTPA imaging. It is advisable in cases of ambiguous I-131 MIBG imaging to use Tc-99m DTPA rather than Tc-99m DMSA for localizing the kidneys and renal pelvis.

  9. Vy-PER: eliminating false positive detection of virus integration events in next generation sequencing data

    PubMed Central

    Forster, Michael; Szymczak, Silke; Ellinghaus, David; Hemmrich, Georg; Rühlemann, Malte; Kraemer, Lars; Mucha, Sören; Wienbrandt, Lars; Stanulla, Martin; Franke, Andre

    2015-01-01

    Several pathogenic viruses such as hepatitis B and human immunodeficiency viruses may integrate into the host genome. These virus/host integrations are detectable using paired-end next generation sequencing. However, the low number of expected true virus integrations may be difficult to distinguish from the noise of many false positive candidates. Here, we propose a novel filtering approach that increases specificity without compromising sensitivity for virus/host chimera detection. Our detection pipeline termed Vy-PER (Virus integration detection bY Paired End Reads) outperforms existing similar tools in speed and accuracy. We analysed whole genome data from childhood acute lymphoblastic leukemia (ALL), which is characterised by genomic rearrangements and usually associated with radiation exposure. This analysis was motivated by the recently reported virus integrations at genomic rearrangement sites and association with chromosomal instability in liver cancer. However, as expected, our analysis of 20 tumour and matched germline genomes from ALL patients finds no significant evidence for integrations by known viruses. Nevertheless, our method eliminates 12,800 false positives per genome (80× coverage) and only our method detects singleton human-phiX174-chimeras caused by optical errors of the Illumina HiSeq platform. This high accuracy is useful for detecting low virus integration levels as well as non-integrated viruses. PMID:26166306

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

    SciTech Connect

    Sliski, David H.; Kipping, David M.

    2014-06-20

    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%.

  11. Reagent decontamination to eliminate false-positives in Escherichia coli qPCR.

    PubMed

    Silkie, Sarah S; Tolcher, Matthew P; Nelson, Kara L

    2008-03-01

    The application of real-time quantitative PCR (qPCR) for the detection of low concentrations of Escherichia coli as well as universal 16S rDNA has been hindered by false-positives due to endogenous contamination of PCR reagents with E. coli and other bacterial DNA. We optimized a DNase I decontamination method to eliminate false-positives in a qPCR assay targeting the uidA gene in E. coli. In contrast to previous methods reported in the literature, our decontamination method did not cause PCR inhibition. We determined that residual DNase I activity was the cause of the inhibition in the previous methods, and eliminated it by ensuring complete inactivation prior to qPCR. DNase inactivation was accomplished by adding dithiothreitol (DTT) and then heating for 30 min at 80 degrees C. The optimized DNase method was compared to another decontamination method, ultrafiltration, and to untreated controls. We detected contamination in 85% of the untreated commercial PCR master mix samples at a level of about 10 copies per well (12.5 microL of master mix). Both decontamination methods could eliminate up to 100 copies of added contaminant DNA and did not cause PCR inhibition, resulting in a reduction of the detection limit to 10 copies per reaction well.

  12. I am Not Dead Yet: Identification of False-Positive Matches to Death Master File

    PubMed Central

    Turchin, Alexander; Shubina, Maria; Murphy, Shawn N

    2010-01-01

    Patient death is an important clinical outcome. It is typically ascertained by matching database records with external death indices. Accuracy of the matching algorithms is imperfect. We have investigated whether clinical records made > 1 month after the date of death accurately identify false positive matches to the Death Master File. Positive predictive value (PPV) varied from 74.7% (notes) to 95.9% (labs) and sensitivity from 57.4% (adverse medication reactions) to 94.9% (notes). Presence of any two out of four (billing data, labs, vital signs and medications) data elements had sensitivity of 83.0% and PPV of 98.3%. Area under the ROC curve for a multivariable logistic model that included the number of these four data elements recorded > 1 month after death was 0.987. Clinical data recorded after the date of death can help identify false positive matches to death indices and could be utilized to improve existing record linkage algorithms. PMID:21347090

  13. Estimating False Positive Contamination in Crater Annotations from Citizen Science Data

    NASA Astrophysics Data System (ADS)

    Tar, P. D.; Bugiolacchi, R.; Thacker, N. A.; Gilmour, J. D.

    2017-01-01

    Web-based citizen science often involves the classification of image features by large numbers of minimally trained volunteers, such as the identification of lunar impact craters under the Moon Zoo project. Whilst such approaches facilitate the analysis of large image data sets, the inexperience of users and ambiguity in image content can lead to contamination from false positive identifications. We give an approach, using Linear Poisson Models and image template matching, that can quantify levels of false positive contamination in citizen science Moon Zoo crater annotations. Linear Poisson Models are a form of machine learning which supports predictive error modelling and goodness-of-fits, unlike most alternative machine learning methods. The proposed supervised learning system can reduce the variability in crater counts whilst providing predictive error assessments of estimated quantities of remaining true verses false annotations. In an area of research influenced by human subjectivity, the proposed method provides a level of objectivity through the utilisation of image evidence, guided by candidate crater identifications.

  14. Application of artificial neural networks for reduction of false-positive detections in digital chest radiographs.

    PubMed

    Lin, J S; Ligomenides, P A; Freedman, M T; Mun, S K

    1993-01-01

    A methodology based on the fuzzy set theory and the convolution neural network (CNN) architecture is proposed to tackle the problem of reducing false-positive rate in automatic lung nodule detection. The CNN which simulates human visual mechanism was trained by a supervised back-propagation algorithm based on fuzzy membership functions. The training and testing database consists of image blocks (each 32 x 32 pixels) of suspected lung nodule areas (nodule candidates) which were generated from our pre-scanning program [1]. A linguistic label was assigned to each nodule candidate of the training set, then the label was converted to a membership value through a pre-defined membership function and used as teaching signal (desired outputs) during the network learning. Before the nodule candidate was fed to the network input, it was pre-processed to reduce the complex background noise and the contrast discrepancy resulted from film development. During the network testing phase, a defuzzification process was applied to decipher the trained network's output triggered by the nodule candidate in the testing set. Finally, a Receiver Operating Characteristic (ROC) analysis was used to evaluate the CNN's performance based on the defuzzified output of the testing database. Preliminary results showed an average Az (the performance index) of 0.84 which is equivalent to 0.80 true-positive detection (sensitivity) with an average 2-3 false-positive detections per chest image.

  15. Application of artificial neural networks for reduction of false-positive detections in digital chest radiographs.

    PubMed Central

    Lin, J. S.; Ligomenides, P. A.; Freedman, M. T.; Mun, S. K.

    1993-01-01

    A methodology based on the fuzzy set theory and the convolution neural network (CNN) architecture is proposed to tackle the problem of reducing false-positive rate in automatic lung nodule detection. The CNN which simulates human visual mechanism was trained by a supervised back-propagation algorithm based on fuzzy membership functions. The training and testing database consists of image blocks (each 32 x 32 pixels) of suspected lung nodule areas (nodule candidates) which were generated from our pre-scanning program [1]. A linguistic label was assigned to each nodule candidate of the training set, then the label was converted to a membership value through a pre-defined membership function and used as teaching signal (desired outputs) during the network learning. Before the nodule candidate was fed to the network input, it was pre-processed to reduce the complex background noise and the contrast discrepancy resulted from film development. During the network testing phase, a defuzzification process was applied to decipher the trained network's output triggered by the nodule candidate in the testing set. Finally, a Receiver Operating Characteristic (ROC) analysis was used to evaluate the CNN's performance based on the defuzzified output of the testing database. Preliminary results showed an average Az (the performance index) of 0.84 which is equivalent to 0.80 true-positive detection (sensitivity) with an average 2-3 false-positive detections per chest image. PMID:8130511

  16. The Clinical Significance of the Biological False Positive Serologic Reactor: A Study of 113 Cases

    PubMed Central

    Knight, Allan; Wilkinson, R. D.

    1963-01-01

    Biological false positive serologic reactors were studied during a long-term follow-up of asymptomatic patients with chronic false positive serology for syphilitic reagin. This was done with a view to facilitating the early diagnosis of systemic disease, particularly collagen disorders, which are frequently associated with this finding in women. One hundred and thirteen cases were studied. Thirty-eight were “acute”, i.e. positive for less than six months, 58 were “chronic”, i.e. positive for more than six months, and the remainder still positive but followed for less than six months. Of 39 female chronic reactors, 10 were diagnosed as having collagen disease, and in six the BFP reaction preceded clinical diagnosis of the disease. Five had no apparent disease. In 19 male chronic reactors, there was no evidence of collagen disorders and five were free of any recognizable pathology. The remainder in both sexes were found to have a wide variety of systemic illnesses. PMID:14033756

  17. Compliance With Screening Mammography Guidelines After a False-Positive Mammogram.

    PubMed

    Hardesty, Lara A; Lind, Kimberly E; Gutierrez, Eric J

    2016-09-01

    To assess whether women with a false-positive mammogram who do return for screening are less likely to be compliant with screening mammography guidelines than are women with a negative mammogram. This institutional review board-approved, HIPAA-compliant retrospective cohort study includes women >40 years old who received 9,385 consecutive, nonbaseline screening mammograms between December 1, 2012 and December 31, 2013. Using linear regression, we evaluated differences in time between mammograms by prior recall status, after adjusting for location of current mammogram (outpatient office versus mobile unit) and age. Using Fisher's exact test, we evaluated the association between compliance with screening guidelines and the recall status on prior mammogram, and compared by location the proportions of noncompliant women who were recalled from prior mammogram. Time between mammograms does not differ based on prior recall status (P = .83). There is no association between compliance with screening mammography guidelines and recall status on prior mammogram (ACR guidelines P = .398, United States Preventive Services Task Force guidelines P = .416). Noncompliant women recalled on prior mammogram are more likely to undergo mammography at the outpatient office rather than the mobile unit (ACR guidelines P = .0004, United States Preventive Services Task Force guidelines P = .0032). A prior false-positive mammogram is not a significant deterrent to compliance with screening guidelines in those women who return for screening. Copyright © 2016 American College of Radiology. Published by Elsevier Inc. All rights reserved.

  18. A High False Positive Rate for Kepler Planetary Candidates of Giant Stars using Asterodensity Profiling

    NASA Astrophysics Data System (ADS)

    Sliski, David H.; Kipping, David M.

    2014-06-01

    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%. Based on archival data of the Kepler telescope.

  19. Allelic Dropout Can Cause False-Positive Results for Prader-Willi and Angelman Syndrome Testing

    PubMed Central

    Hussain Askree, Syed; Hjelm, Lawrence N.; Ali Pervaiz, Muhammad; Adam, Margaret; Bean, Lora J.H.; Hedge, Madhuri; Coffee, Bradford

    2011-01-01

    The diagnosis of many genetic disorders relies on a combination of clinical suspicion and confirmatory genetic testing. Our laboratory uses a standard methylation-sensitive PCR (MSP) to target the differentially methylated SNRPN gene to test for Prader-Willi syndrome (PWS) and Angelman syndrome. One patient, a 27-month-old female, who lacked the classical clinical features of PWS, but had a molecular diagnosis of PWS by MSP by another laboratory, had repeat testing in our laboratory. Testing by MSP in our laboratory also identified an apparent loss of the unmethylated paternal allele, consistent with a diagnosis of PWS. Confirmatory testing using Southern blot analysis with a methylation-sensitive restriction enzyme showed a normal pattern of methylation, detecting both the methylated maternal and unmethylated paternal alleles. To investigate these discrepant results, we amplified and sequenced the SNRPN locus in this patient and identified a single nucleotide change within the binding site for the unmethylated DNA-specific primer. These results indicate this nucleotide change led to allelic dropout in the MSP analysis, yielding the false-positive result. Subsequently, MSP analysis using an alternate primer set that was developed by our laboratory detected both methylated and unmethylated alleles. These findings illustrate that allelic dropout due to the presence of rare polymorphisms can cause false-positive results in commonly used MSP assays and lead to molecular misdiagnosis. PMID:21227401

  20. Detection of circulating prostate tumor cells: alternative spliced variant of PSM induced false-positive result.

    PubMed

    Hisatomi, Hisashi; Nagao, Kumi; Kawakita, Mutsuji; Matsuda, Tadashi; Hirata, Hiroyuki; Yamamoto, Shigeki; Nakamoto, Takaaki; Harasawa, Hiroshi; Kaneko, Noboru; Hikiji, Kazumasa; Tsukada, Yutaka

    2002-11-01

    RT-nested PCR has been introduced as a highly specific and sensitive assay method to detect the prostate-specific membrane antigen (PSM) mRNA in peripheral blood. However, appreciable percentages of false-positive cases have been reported. Additionally, primer sets reported previously could not discriminate between PSM and PSM', an alternatively spliced variant, mRNA. These isoforms can be produced from a single gene. Switches in alternative splicing patterns are often controlled with strict cell-type or developmental-stage specificity. Therefore, it is most important to discriminate between PSM mRNA and PSM' mRNA. Using our highly specific primer sets, PSM mRNA was detected in 3 of 24 peripheral blood samples of normal male volunteers (12.5%) and was not detected in peripheral blood of 11 normal female volunteers. PSM' mRNA was detected in 5 of 24 peripheral blood samples of normal male volunteers (20.8%) and in 4 of 11 of normal female volunteers (36.4%). PSM' mRNA induced false-positive results, it is important for genetic diagnosis of prostate cancer to discriminate between PSM and PSM' using our primer sets with high specificity. The advances in the uniquely designed primer sets may allow researchers to detect a real PSM mRNA without PSM' mRNA.

  1. Vy-PER: eliminating false positive detection of virus integration events in next generation sequencing data.

    PubMed

    Forster, Michael; Szymczak, Silke; Ellinghaus, David; Hemmrich, Georg; Rühlemann, Malte; Kraemer, Lars; Mucha, Sören; Wienbrandt, Lars; Stanulla, Martin; Franke, Andre

    2015-07-13

    Several pathogenic viruses such as hepatitis B and human immunodeficiency viruses may integrate into the host genome. These virus/host integrations are detectable using paired-end next generation sequencing. However, the low number of expected true virus integrations may be difficult to distinguish from the noise of many false positive candidates. Here, we propose a novel filtering approach that increases specificity without compromising sensitivity for virus/host chimera detection. Our detection pipeline termed Vy-PER (Virus integration detection bY Paired End Reads) outperforms existing similar tools in speed and accuracy. We analysed whole genome data from childhood acute lymphoblastic leukemia (ALL), which is characterised by genomic rearrangements and usually associated with radiation exposure. This analysis was motivated by the recently reported virus integrations at genomic rearrangement sites and association with chromosomal instability in liver cancer. However, as expected, our analysis of 20 tumour and matched germline genomes from ALL patients finds no significant evidence for integrations by known viruses. Nevertheless, our method eliminates 12,800 false positives per genome (80× coverage) and only our method detects singleton human-phiX174-chimeras caused by optical errors of the Illumina HiSeq platform. This high accuracy is useful for detecting low virus integration levels as well as non-integrated viruses.

  2. False-Positive Results after Environmental Pinworm PCR Testing due to Rhabditid Nematodes in Corncob Bedding

    PubMed Central

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

    2014-01-01

    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. PMID:25650980

  3. Single-primer PCR correction: a strategy for false-positive exclusion.

    PubMed

    Ma, J; Wang, P W; Yao, D; Wang, Y P; Yan, W; Guan, S C

    2011-02-01

    Polymerase chain reaction (PCR) technology plays an important role in molecular biology research, but false-positive and nonspecific PCR amplification have plagued many researchers. Currently, research on the optimization of the PCR system focuses on double-primer-based PCR products. This research has shown that PCR amplification based on single-primer binding to the DNA template is an important contributing factor to obtaining false-positive results, fragment impurity, and nonspecific fragment amplification, when the PCR conditions are highly restricted during PCR-based target gene cloning, detection of transgenic plants, simple-sequence repeat marker-assisted selection, and mRNA differential display. Here, we compared single- and double-primer amplification and proposed "single-primer PCR correction"; improvements in PCR that eliminate interference caused by single-primer-based nonspecific PCR amplification were demonstrated and the precision and success rates of experiments were increased. Although for some kinds of experiments, the improvement effect of single-primer PCR correction was variable, the precision and success rate could be elevated at 12-50% in our experiment by this way.

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

    PubMed

    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.

  5. Detection of false positive mutations in BRCA gene by next generation sequencing.

    PubMed

    Suryavanshi, Moushumi; Kumar, Dushyant; Panigrahi, Manoj Kumar; Chowdhary, Meenakshi; Mehta, Anurag

    2016-11-15

    BRCA1 and BRCA2 genes are implicated in 20-25% of hereditary breast and ovarian cancers. New age sequencing platforms have revolutionized massively parallel sequencing in clinical practice by providing cost effective, rapid, and sensitive sequencing. This study critically evaluates the false positives in multiplex panels and suggests the need for careful analysis. We employed multiplex PCR based BRCA1 and BRCA2 community Panel with ion torrent PGM machine for evaluation of these mutations. Out of all 41samples analyzed for BRCA1 and BRCA2 five were found with 950_951 insA(Asn319fs) at Chr13:32906565 position and one sample with 1032_1033 insA(Asn346fs) at Chr13:32906647, both being frame-shift mutations in BRCA2 gene. 950_951 insA(Asn319fs) mutation is reported as pathogenic allele in NCBI dbSNP. On examination of IGV for all these samples, it was seen that both mutations had 'A' nucleotide insertion at 950, and 1032 position in exon 10 of BRCA2 gene. Sanger Sequencing did not confirm these insertions. Next-generation sequencing shows great promise by allowing rapid mutational analysis of multiple genes in human cancer but our results indicate the need for careful sequence analysis to avoid false positive results.

  6. Peptizer, a tool for assessing false positive peptide identifications and manually validating selected results.

    PubMed

    Helsens, Kenny; Timmerman, Evy; Vandekerckhove, Joël; Gevaert, Kris; Martens, Lennart

    2008-12-01

    False positive peptide identifications are a major concern in the field of peptidecentric, mass spectrometry-driven gel-free proteomics. They occur in regions where the score distributions of true positives and true negatives overlap. Removal of these false positive identifications necessarily involves a trade-off between sensitivity and specificity. Existing postprocessing tools typically rely on a fixed or semifixed set of assumptions in their attempts to optimize both the sensitivity and the specificity of peptide and protein identification using MS/MS spectra. Because of the expanding diversity in available proteomics technologies, however, these postprocessing tools often struggle to adapt to emerging technology-specific peculiarity. Here we present a novel tool named Peptizer that solves this adaptability issue by making use of pluggable assumptions. This research-oriented postprocessing tool also includes a graphical user interface to perform efficient manual validation of suspect identifications for optimal sensitivity recovery. Peptizer is open source software under the Apache2 license and is written in Java.

  7. False positive tests for anti-hepatitis C antibodies and the problem of notifying blood donors.

    PubMed

    Bar-Shany, S; Green, M S; Shinar, E

    1996-06-01

    All donated blood in Israel is tested for anti-hepatitis C virus (HCV) antibodies by enzyme immunoassay (EIA) and donors are notified of the result. There is evidence that at low antibody titres, the percentage of false positives may be high, with consequent labelling of healthy people as being infected with HCV. In this study we examined the correlation between anti-HCV antibody titres determined by a second generation EIA test with supplemental EIA tests and evidence of abnormal liver function. Blood samples of 201 Israeli civilians who donated blood during 1992 and were repeat reactive for anti-HCV antibody based on second generation EIA, were tested by a supplemental test. Follow-up data were obtained from the donors and their family physicians. Results of anti-HCV EIA tests on two separate occasions of blood donation were highly correlated with each other (r = 0.86). Positive supplemental tests and abnormal liver function tests were found only in those subjects with high antibody titres. Furthermore low antibody titres were more prevalent during the winter months, suggesting that seasonal intercurrent infections may increase the percentage of false positives. A high proportion of blood donors labelled as anti-HCV antibody positive based on low antibody titres, may not be at increased risk of carrying HCV. Since labelling would result in creating unnecessary anxiety among blood donors, it is important to confirm such results with test such as radioimmunoblot assay (RIBA).

  8. Estimating False Positive Contamination in Crater Annotations from Citizen Science Data

    NASA Astrophysics Data System (ADS)

    Tar, P. D.; Bugiolacchi, R.; Thacker, N. A.; Gilmour, J. D.

    2016-11-01

    Web-based citizen science often involves the classification of image features by large numbers of minimally trained volunteers, such as the identification of lunar impact craters under the Moon Zoo project. Whilst such approaches facilitate the analysis of large image data sets, the inexperience of users and ambiguity in image content can lead to contamination from false positive identifications. We give an approach, using Linear Poisson Models and image template matching, that can quantify levels of false positive contamination in citizen science Moon Zoo crater annotations. Linear Poisson Models are a form of machine learning which supports predictive error modelling and goodness-of-fits, unlike most alternative machine learning methods. The proposed supervised learning system can reduce the variability in crater counts whilst providing predictive error assessments of estimated quantities of remaining true verses false annotations. In an area of research influenced by human subjectivity, the proposed method provides a level of objectivity through the utilisation of image evidence, guided by candidate crater identifications.

  9. False-positive rates associated with the use of multiple performance and symptom validity tests.

    PubMed

    Larrabee, Glenn J

    2014-06-01

    Performance validity test (PVT) error rates using Monte Carlo simulation reported by Berthelson and colleagues (in False positive diagnosis of malingering due to the use of multiple effort tests. Brain Injury, 27, 909-916, 2013) were compared with PVT and symptom validity test (SVT) failure rates in two nonmalingering clinical samples. At a per-test false-positive rate of 10%, Monte Carlo simulation overestimated error rates for: (i) failure of ≥2 out of 5 PVTs/SVT for Larrabee (in Detection of malingering using atypical performance patterns on standard neuropsychological tests. The Clinical Neuropsychologist, 17, 410-425, 2003) and ACS (Pearson, Advanced clinical solutions for use with WAIS-IV and WMS-IV. San Antonio: Pearson Education, 2009) and (ii) failure of ≥2 out of 7 PVTs/SVT for Larrabee (Detection of malingering using atypical performance patterns on standard neuropsychological tests. The Clinical Neuropsychologist, 17, 410-425, 2003; Malingering scales for the Continuous Recognition Memory Test and Continuous Visual Memory Test. The Clinical Neuropsychologist, 23, 167-180, 2009 combined). Monte Carlo overestimation is likely because PVT performances are atypical in pattern or degree for what occurs in actual neurologic, psychiatric, or developmental disorders. Consequently, PVT scores form skewed distributions with performance at ceiling and restricted range, rather than forming a standard normal distribution with mean of 0 and standard deviation of 1.0. These results support the practice of using ≥2 PVT/SVT failures as representing probable invalid clinical presentation.

  10. False-positive postmortem EMIT drugs-of-abuse assay due to lactate dehydrogenase and lactate in urine.

    PubMed

    Sloop, G; Hall, M; Simmons, G T; Robinson, C A

    1995-01-01

    Three cases of multiple false-positive drug tests are described. Postmortem urine specimens were screened using the enzyme-multiplied immunoassay technique. All patients had proteinuria and lactic aciduria. These false-positive reactions were due to the presence of lactate dehydrogenase (LDH), lactic acid, and protein. This finding was confirmed by creating a multiple false-positive sample with a solution of LDH and lactate in 5% bovine serum albumin at pH 6.

  11. Periprocedural safety of 64-detector row coronary computed tomographic angiography: results from the prospective multicenter ACCURACY trial.

    PubMed

    Bell, George W; Edwardes, Michael; Dunning, Allison M; Glasofer, Sidney; Lin, Fay Y; Labounty, Troy M; Delago, Augustin; Budoff, Matthew J; Min, James K

    2010-01-01

    Coronary computed tomographic angiography (CCTA) requires iodinated contrast and often atrioventricular nodal blocking agents and nitroglycerin for heart rate lowering and coronary vasodilation, respectively. To date, the periprocedural safety of CCTA is unknown. The purpose of this study was to evaluate the periprocedural safety of CCTA. We prospectively evaluated 232 patients with symptomatic chest pain without preexisting renal insufficiency at 16 sites who underwent CCTA as part of the Assessment by Coronary Computed Tomographic Angiography of Individuals Undergoing Invasive Coronary Angiography (ACCURACY) trial. Patients received iodinated contrast, β-blockers, and nitroglycerin as part of a predefined CCTA protocol. We assessed the rates of adverse events (AEs) related to these agents. As measured by serum creatinine and creatinine clearance, no significant change was observed in renal function from baseline (1.00 ± 0.19 mg/dL; modification of diet in renal disease [MDRD]: 76.91 ± 17.96 mL/min/1.73 m(2)) to 48 hours (1.0 ± 0.2 mg/dL; P = 1.00; MDRD change: 0.2 ± 12.4 mL/min/1.73 m(2); P = 0.83) or at 30 days (1.0 ± 0.2 mg/dL; P = 0.52; MDRD change: -0.9 ± 16.9 mL/min/1.73 m(2); P = 0.77). Mean systolic blood pressure decreased from baseline (133 ± 19 mm Hg) at 1 hour (125 ± 17 mm Hg; P < 0.001) and rebounded at 48 hours (133 ± 17 mm Hg). Mean heart rate decreased from baseline (65 ± 10 beats/min) at 1 hour (60 ± 7 beats/min) but rose at 48 hours (69 ± 11 beats/min; P < 0.001. All patients were asymptomatic from baseline to follow-up. The performance of CCTA is safe with low rates of AEs. © 2010 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.

  12. False-positive pH aspirates after nasogastric tube insertion in head and neck tumour

    PubMed Central

    Sellers, Claudia Kate

    2012-01-01

    Nasogastric (NG) feeding tubes are commonly inserted to supplement enteral nutrition in certain patient groups, including those with head and neck cancers where swallowing may be compromised. An NHS National Patient Safety Alert was released in 2011 detailing ongoing cases of significant morbidity and mortality attached to the incorrect placement of NG feeding tubes in hospital inpatients. Since 2005, there were 21 deaths and 79 cases of harm nationally due to feeding into the lung through misplaced tubes. pH testing remains the first-line method of placement confirmation, with chest x-ray used when no aspirate is gained or where pH testing fails to confirm suitable acidity. We present a case report describing false-positive NG tube placement confirmation tests in a patient with head and neck cancer, who was administered feed into lung parenchyma with significant morbidity. We discuss the case for specific NG tube placement protocols in head and neck cancer patients. PMID:22927281

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

    PubMed

    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

  14. Occurrence of false-positive most probable number tests for fecal streptococci in marine waters.

    PubMed

    Buck, J D

    1969-10-01

    By the use of the most probable number technique with azide dextrose and ethyl violet azide broths for enterococci, the common occurrence of false-positive tests was noted when marine and estuarine waters were sampled. Organisms isolated included a marine bacterium, gram-positive and gram-negative nonmarine bacteria, and yeasts. All cultures were capable of growth in azide-dextrose, ethyl violet-azide, and KF broths. Representative isolates grew in media containing 0.08% NaN(3). The tentatively accepted most probable number method for fecal streptococci is thus of dubious value in assessment of sewage pollution levels in estuarine waters. All positive tubes must be examined microscopically for the presence of nonstreptococcal forms.

  15. False positive RNA binding activities after Ni-affinity purification from Escherichia coli.

    PubMed

    Milojevic, Tetyana; Sonnleitner, Elisabeth; Romeo, Alessandra; Djinović-Carugo, Kristina; Bläsi, Udo

    2013-06-01

    A His-tag is often added by means of recombinant DNA technology to a heterologous protein of interest, which is then over-produced in Escherchia coli and purified by one-step immobilized metal-affinity chromatography (IMAC). Owing to the presence of 24 histidines at the C-termini of the hexameric E. coli RNA chaperone Hfq, the protein co-purifies with His-tagged proteins of interest. As Hfq can bind to distinct RNA substrates with high affinity, its presence can obscure studies performed with (putative) RNA binding activities purified by IMAC. Here, we present results for a seemingly positive RNA-binding activity, exemplifying that false-positive results can be avoided if the protein of interest is either subjected to further purification step(s) or produced in an E. coli hfq- strain.

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

    SciTech Connect

    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.

  17. Occurrence of False-Positive Most Probable Number Tests for Fecal Streptococci in Marine Waters1

    PubMed Central

    Buck, John D.

    1969-01-01

    By the use of the most probable number technique with azide dextrose and ethyl violet azide broths for enterococci, the common occurrence of false-positive tests was noted when marine and estuarine waters were sampled. Organisms isolated included a marine bacterium, gram-positive and gram-negative nonmarine bacteria, and yeasts. All cultures were capable of growth in azide-dextrose, ethyl violet-azide, and KF broths. Representative isolates grew in media containing 0.08% NaN3. The tentatively accepted most probable number method for fecal streptococci is thus of dubious value in assessment of sewage pollution levels in estuarine waters. All positive tubes must be examined microscopically for the presence of nonstreptococcal forms. PMID:4983956

  18. Quantification of false positive reduction in nucleic acid purification on hemorrhagic fever DNA.

    SciTech Connect

    James, Conrad D.; Pohl, Kenneth Roy; Derzon, Mark Steven; McClain, Jaime; Achyuthan, Komandoor

    2006-11-01

    Columbia University has developed a sensitive highly multiplexed system for genetic identification of nucleic acid targets. The primary obstacle to implementing this technology is the high rate of false positives due to high levels of unbound reporters that remain within the system after hybridization. The ability to distinguish between free reporters and reporters bound to targets limits the use of this technology. We previously demonstrated a new electrokinetic method for binary separation of kb pair long DNA molecules and oligonucleotides. The purpose of this project 99864 is to take these previous demonstrations and further develop the technique and hardware for field use. Specifically, our objective was to implement separation in a heterogeneous sample (containing target DNA and background oligo), to perform the separation in a flow-based device, and to develop all of the components necessary for field testing a breadboard prototype system.

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

    SciTech Connect

    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

    2010-04-20

    Ten days of commissioning data (Quarter 0) and 33 days of science data (Quarter 1) yield instrumental flux time series of {approx}150,000 stars that were combed for transit events, termed threshold crossing events(TCE), each having a total detection statistic above 7.1{sigma}. TCE light curves are modeled as star+planet systems. Those returning a companion radius smaller than 2R{sub 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.

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

    SciTech Connect

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

    2012-06-10

    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.

  1. Eliminating false positive C4 sugar tests on New Zealand Manuka honey.

    PubMed

    Rogers, Karyne M; Somerton, Kerry; Rogers, Pamela; Cox, Julie

    2010-08-30

    Carbon isotope analyses (delta(13)C) of some New Zealand Manuka honeys show that they often fail the internationally recognised Association of Official Analytical Chemists sugar test (AOAC method 998.12) which detects added C(4) sugar, although these honeys are from unadulterated sources. Failure of these high value products is detrimental to the New Zealand honey industry, not only in lost export revenue, but also in brand and market reputation damage. The standard AOAC test compares the carbon isotope value of the whole honey and corresponding protein isolated from the same honey. Differences between whole honey and protein delta(13)C values should not be greater than +1.0 per thousand, as it indicates the possibility of adulteration with syrups or sugars from C(4) plants such as high fructose corn syrup or cane sugar.We have determined that during the standard AOAC method, pollen and other insoluble components are isolated with the flocculated protein. These non-protein components have isotope values which are considerably different from those of the pure protein, and can shift the apparent delta(13)C value of protein further away from the delta(13)C value of the whole honey, giving a false positive result for added C(4) sugar. To eliminate a false positive C(4) sugar test for Manuka honey, prior removal of pollen and other insoluble material from the honey is necessary to ensure that only the pure protein is isolated. This will enable a true comparison between whole honey and protein delta(13)C isotopes. Furthermore, we strongly suggest this modification to the AOAC method be universally adopted for all honey C(4) sugar tests.

  2. Parathyroid incidentalomas detected during thyroid ultrasonography and effect of chronic thyroiditis on false positive parathyroid lesions.

    PubMed

    Ozdemir, Didem; Arpaci, Dilek; Ucler, Rifki; Cuhaci, Neslihan; Ersoy, Reyhan; Cakir, Bekir

    2012-12-01

    We aimed to determine the prevalence of parathyroid incidentalomas in patients referred for thyroid ultrasonography (US) and investigate the role of chronic thyroiditis on false positive lesions. Patients suspected to have parathyroid lesions during thyroid US were recorded prospectively between August 2009 and January 2010. Patients referred for parathyroid US and patients with known high serum calcium or parathyroid hormone (PTH) levels were excluded. Suspected parathyroid lesions were defined as hypoechoic, homogeneous, solid lesions with regular margins located outside the thyroid lobe, most commonly inferior to the thyroid gland. Thyroid US was performed in 6,528 patients. There were 78 patients (1.19 %) (73 female and 5 male) with suspected parathyroid lesion. The diagnosis of a true parathyroid adenoma was confirmed in 6 (7.69 %) patients. In patients with true adenoma, mean serum calcium, phosphorus, and PTH levels were 10.57 ± 0.48 mg/dl, 3.03 ± 0.52 mg/dl, and 182.91 ± 46.62 pg/ml, respectively. Among 72 patients with false positive parathyroid lesion, antithyroid peroxidase antibody was positive in 50 (69.4 %), antithyroglobulin antibody was positive in 46 (63.9 %), and one of these antibodies were positive in 59 (81.9 %) patients. Also, 46 (63.9 %) of these patients had thyroid dysfunctions (43 hypothyroidism and 3 hyperthyroidism) and 59 (81.9 %) had chronic thyroiditis ultrasonographically. Parathyroid incidentaloma was detected in 0.09 % of patients referred for thyroid US. The presence of clinically or ultrasonographically chronic thyroiditis might cause inadvertent interpretation of a hypoechoic lesion as a parathyroid pathology during thyroid US.

  3. Automated detection of pulmonary nodules in CT: false positive reduction by combining multiple classifiers

    NASA Astrophysics Data System (ADS)

    Suárez-Cuenca, Jorge Juan; Guo, Wei; Li, Qiang

    2011-03-01

    The purpose of this study was to investigate the usefulness of various classifier combination methods for improving the performance of a CAD system for pulmonary nodule detection in CT. We employed CT cases in the publicly available lung image database consortium (LIDC) dataset, which included 85 CT cases with 110 nodules. We first used six individual classifiers for nodule detection in CT, including linear discriminant analysis (LDA), quadratic discriminant analysis (QDA), artificial neural network (ANN), and three types of support vector machines (SVM). Five informationfusion methods were then employed to combine the classifiers' outputs for improving detection performance. The five combination methods included two supervised (likelihood ratio method and neural network) and three unsupervised ones (the mean, the product, and the majority-vote of the output scores from the six individual classifiers). Leave-one-caseout was employed to train and test individual classifiers and supervised combination methods. At a sensitivity of 80 %, the numbers of false positives per case for the six individual classifiers were 6.1 for LDA, 19.9 for QDA, 8.6 for ANN, 23.7 for SVM-dot, 17.0 for SVM-poly, and 23.35 for SVM-ANOVA; the numbers of false positives per case for the five combination methods were 3.4 for the majority-vote rule, 6.2 for the mean, 5.7 for the product, 9.7 for the neural network, and 28.1 for the likelihood ratio method. The majority-vote rule achieved higher performance levels than other combination methods. It also achieved higher performance than the best individual classifier, which is not the case for other combination methods.

  4. Blue-white screening liquid can eliminate false positives in blue-white colony screening.

    PubMed

    Zhang, Y S

    2016-06-10

    Although blue-white screening based on α-complementation has been widely used in the screening of genetically modified bacteria, only a single blue-white screening is typically not enough to eliminate false positives. Sometimes, a secondary blue-white screening for the target colonies is required. In this study, two methods were used to investigate the feasibility of secondary blue-white screening for target colonies on lysogeny broth (LB)-ampicillin agar plates. The first method consisted of covering the target colonies grown on LB-ampicillin plate medium with a sterilized filter paper soaked in a solution of 60 μL 20 mg/mL X-gal and 8 μL 20% IPTG. The second method was that blue and white colonies were randomly selected from the blue-white screening plate medium and then re-streaked onto the blue-white screening medium. The colonies were then treated by two methods and incubated at 37°C for 12 h. The results showed that some of the white colonies treated by the two methods showed results similar to the colonies grown on the blue-white screening medium. These results indicate that the target colonies grown on blue-white screening medium can still be used to carry out a secondary blue-white screening. Thus, a blue-white screening liquid was successfully developed. Using the blue-white screening liquid, false positives can be eliminated directly based on the color of the target colonies. This will greatly improve the screening efficiency of positive clones and has important practical implications.

  5. The patterns of false positive lesions for chest radiography observer performance: insights into errors and locations

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    To examine the lobar distribution of false positives on a set of nodule-free and nodule-containing chest radiographs when radiologists are requested to perform an unframed task (oral report) compared to a framed task (nodule/s identification). A set of 40 chest images, 21 nodule-free (NF) and 19 nodule-containing (NC), was used. Ten radiologists participated in the study; first an oral clinical report was performed (unframed task, UFT) naming any abnormality seen, a confidence score and the location of reported abnormalities. The second (framed task, FT) had the same images randomly presented and radiologists were asked to locate any lung nodule/s and record their confidence and location of nodules. There was no statistical difference between the mean number of false positives (FPs) per lobe per case type (UFT or FT) with the exception of the right lower lobe (RLL) P=0.021. When the comparison of FPs for tasks and case types was carried out there were significant changes. For the NF cases there are significant differences for right upper lobe (RUL) P=0.0003, left upper lobe (LUL) P=0.0412; for NC cases there are significant differences for RUL P=0.009, RLL P=0.0112, LUL P=0.0337 and left lower lobe (LLL) P=0.0209. There was no significant correlation between the presence of a nodule in a given lobe and the occurrence of a FP in that lobe. The number and lobar location of FPs identified on a chest image by a radiologist is influenced by the task and case type.

  6. High False Positives and False Negatives in Yeast Parameter in an Automated Urine Sediment Analyzer

    PubMed Central

    Aydin, Ozgur; Ellidag, Hamit Yasar; Eren, Esin; Yilmaz, Necat

    2015-01-01

    Summary Background Automated urine sediment analyzers have proven their feasibility in medical laboratories. However, editing manual microscopic review of some specimens severely limits the usefulness of such systems. This study aims to give feedback on the practical experience on »Yeast«, which is one of the parameters that compel frequent manual reviews. Methods 5448 freshly collected urine specimens submitted from various departments of our hospital for diagnostic urinalysis were studied by the UriSed® (77 Elektronika, Hungary). A specialist medical doctor inspected every image on-board, and reviewed the ones with a »Yeast« alarm by traditional manual microscopy. Results UriSed alarmed in 491 samples (9%) for yeast. In 59 samples (1%) the number of particles exceeded the cut-off and a »positive for yeast« was set. A false positive report of yeast +1 to 3+/HPF was found in 51 samples (0.9%). There were 8 cases with positive for yeast from both microscopic methods. Thirty-three »negative for yeast« samples were corrected as positive after the manual microscopic review. Conclusions We report a high percentage of false positives and negatives in the yeast parameter, in line with other studies on UriSed as well as on other instruments in the market. As an important feedback, our observations showed that the major concern in false results was »the focusing problem«. We believe in the necessity of a focus check and comparison of alarms between images on board. PMID:28356844

  7. Effect of beta blockade on single photon emission computed tomographic (SPECT) thallium-201 images in patients with coronary disease

    SciTech Connect

    Narahara, K.A.; Thompson, C.J.; Hazen, J.F.; Brizendine, M.; Mena, I.

    1989-05-01

    We evaluated the effect of beta blockers on thallium-201 (Tl-201) single photon emission computed tomographic (SPECT) imaging in 12 patients with coronary disease using an automated computer algorithm. Maximal exercise heart rate and blood pressure were reduced and exercise time was increased with beta blockers. Estimated stress defect size decreased from 47 +/- 36.3 gm during placebo treatment to 32 +/- 27.1 gm during beta blocker therapy (-32%; p less than 0.01). The placebo treatment redistribution defect was estimated to be 28 +/- 29.8 gm. It fell to 15 +/- 23.3 gm with beta blockade (-46%; p less than 0.005). All patients had a stress Tl-201 defect during placebo treatment and eight had redistribution defects consistent with residual scar. During beta blocker therapy, 2 of 12 patients had normal stress-redistribution studies and only five patients had redistribution defects. Beta blockade can reduce exercise and redistribution Tl-201 SPECT defect size significantly while simultaneously increasing exercise time and reducing angina. Beta blockers may unmask or may eliminate evidence of redistribution. Tl-201 SPECT imaging may be useful in defining the reduction in ischemia produced by cardiac drugs.

  8. A Method for Identifying Contours in Processing Digital Images from Computer Tomograph

    NASA Astrophysics Data System (ADS)

    Roşu, Şerban; Pater, Flavius; Costea, Dan; Munteanu, Mihnea; Roşu, Doina; Fratila, Mihaela

    2011-09-01

    The first step in digital processing of two-dimensional computed tomography images is to identify the contour of component elements. This paper deals with the collective work of specialists in medicine and applied mathematics in computer science on elaborating new algorithms and methods in medical 2D and 3D imagery.

  9. False Positive STEMI Activations in a Regional Network: Comprehensive Analysis and Clinical Impact. Results From the Catalonian Codi Infart Network.

    PubMed

    Regueiro, Ander; Fernández-Rodríguez, Diego; Freixa, Xavier; Bosch, Xavier; Martín-Yuste, Victoria; Brugaletta, Salvatore; Roqué, Mercè; Sabaté, Manel; Masotti, Mónica

    2017-07-12

    ST-segment elevation myocardial infarction (STEMI) network activation by a noncardiologist reduces delay times but may increase the rate of false-positive STEMI diagnoses. We aimed to determine the prevalence, predictors, and clinical impact of false-positive activations within the Catalonian STEMI network (Codi Infart). From January 2010 through December 2011, all consecutive patients treated within the Codi Infart network were included. Code activations were classified as appropriate if they satisfied both electrocardiogram and clinical STEMI criteria. Appropriate activations were classified as false positives using 2 nonexclusive definitions: a) "angiographic" if a culprit coronary artery was not identified, and b) "clinical" if the discharge diagnosis was other than STEMI. In total, 5701 activations were included. Appropriate activation was performed in 87.8% of the episodes. The rate of angiographic false positives was 14.6%, while the rate of clinical false positives was 11.6%. Irrespective of the definition, female sex, left bundle branch block, and previous myocardial infarction were independent predictors of false-positive STEMI diagnoses. Using the clinical definition, hospitals without percutaneous coronary intervention and patients with complications during the first medical contact also had a false-positive STEMI diagnoses rate higher than the mean. In-hospital and 30-day mortality rates were similar for false-positive and true-positive STEMI patients after adjustment for possible confounders. False-positive STEMI diagnoses were frequent. Outcomes were similar for patients with a true-positive or false-positive STEMI diagnosis treated within a STEMI network. The presence of any modifiable predictors of a false-positive STEMI diagnosis warrants careful assessment to optimize the use of STEMI networks. Copyright © 2017 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.

  10. Change in Abdominal Morphology After Surgical Correction of Thoracolumbar Kyphosis Secondary to Ankylosing Spondylitis: A Computed Tomographic Study.

    PubMed

    Ji, Ming-Liang; Qian, Bang-Ping; Qiu, Yong; Wang, Bin; Mao, Sai-Hu; Zhu, Ze-Zhang; Yu, Yang

    2015-12-01

    A computed tomographic study. To investigate the change in abdominal morphology in surgically treated patients with ankylosing spondylitis (AS) and thoracolumbar kyphosis. Severe thoracolumbar kyphosis in patients with AS exerts pressure on the abdominal cavity and subsequently causes intra-abdominal complications. Several spinal osteotomy techniques have been widely used to correct AS-related thoracolumbar kyphosis. To date, the changed abdominal morphology in patients with AS undergoing surgical correction of thoracolumbar kyphosis has not been addressed. A total of 29 patients with AS undergoing lumbar pedicle subtraction osteotomy for correction of thoracolumbar kyphosis were retrospectively reviewed. Computed tomographic scans of the spine were used to measure the longitudinal, transverse, and anterior-posterior diameters of the abdominal cavity. Furthermore, the abdominal cavity was considered as an ellipsoid structure, thereby allowing calculation of its volume. Radiographical evaluations included global kyphosis (GK), thora