• Title/Summary/Keyword: False positive rate

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Development of a real-time polymerase chain reaction assay for reliable detection of a novel porcine circovirus 4 with an endogenous internal positive control

  • Kim, Hye-Ryung;Park, Jonghyun;Park, Ji-Hoon;Kim, Jong-Min;Baek, Ji-Su;Kim, Da-Young;Lyoo, Young S.;Park, Choi-Kyu
    • Korean Journal of Veterinary Service
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    • v.45 no.1
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    • pp.1-11
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    • 2022
  • A novel porcine circovirus 4 (PCV4) was recently identified in Chinese and Korean pig herds. Although several conventional polymerase chain reaction (cPCR) and real-time PCR (qPCR) assays were used for PCV4 detection, more sensitive and reliable qPCR assay is needed that can simultaneously detect PCV4 and internal positive control (IPC) to avoid false-negative results. In the present study, a duplex qPCR (dqPCR) assay was developed using primers/probe sets targeting the PCV4 Cap gene and pig (glyceraldehyde-3-phosphate dehydrogenase) GAPDH gene as an IPC. The developed dqPCR assay was specifically detected PCV4 but not other PCVs and porcine pathogens, indicating that the newly designed primers/probe set is specific to the PCV4 Cap gene. Furthermore, GAPDH was stably amplified by the dqPCR in all tested viral and clinical samples containing pig cellular materials, indicating the high reliability of the dqPCR assay. The limit of detection of the assay 5 copies of the target PCV4 genes, but the sensitivity of the assay was higher than that of the previously described assays. The assay demonstrated high repeatability and reproducibility, with coefficients of intra-assay and inter-assay variation of less than 1.0%. Clinical evaluation using 102 diseased pig samples from 18 pig farms showed that PCV4 circulated in the Korean pig population. The detection rate of PCV4 obtained using the newly developed dqPCR was 26.5% (27/102), which was higher than that obtained using the previously described cPCR and TaqMan probe-based qPCR and similar to that obtained using the previously described SYBR Green-based qPCR. The dqPCR assay with IPC is highly specific, sensitive, and reliable for detecting PCV4 from clinical samples, and it will be useful for etiological diagnosis, epidemiological study, and control of the PCV4 infections.

Clinical Course of Transferred Patients for Operation Under the Impression of Biliary Atresia (담도폐쇄증 의심하에 수술을 위해 전원된 환자의 임상 경과 분석)

  • Jung, Poong-Man;Lee, Jong-In
    • Advances in pediatric surgery
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    • v.7 no.2
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    • pp.95-104
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    • 2001
  • Biliary atresia (BA) is very difficult to distinguish from neonatal hepatitis (NH) and its prognosis depends on the age at the time of Kasai operation. Therefore early differentiation between these two conditions is very important. Although various clinical and laboratory tests have been reported to differentiate between them, they are still of limited value. From 1980 to 1999, forty-five infants were referred to our pediatric surgical unit for operation for suspected BA. Eight patients underwent Kasai operation immediately because of late diagnosis. These were excluded from the study. The clinical history, physical findings. radiologic and laboratory examinations of 37 cases were analyzed retrospectively. The average age of BA (n=20) was $55.1{\pm}16.7$ days, and that of NH (n=17) was $55.8{\pm}15.6$ days. The sex ratio of BA was 13:7, and that of NH was 14:3. All the patients had obstructive jaundice and acholic stool except 4 BA and 6 NH patients. Acholic stool with yellow component was more frequent in NH. Onset of jaundice was within 2 weeks after birth in 85 % of BA, and in 65% of NH. The onset of acholic stool was within 2 weeks after birth in 60 % of BA, and in 23.5 % of NH. The duration of jaundice and acholic stool of BA were $50.9{\pm}16.6$ days and $41.3{\pm}18.4$ days and those of NH were $40.1{\pm}23.1$ days and $26.6{\pm}25.4$ days respectively. The ultrasonogram and hepatobiliary scan were useful, but not a definitively reliable method for the differentiation of these two diseases. There was no difference in laboratory data. Seventeen cases had NH among 45 referred cases for Kasai operation with the clinical impression of BA, and 4 cases of 17 NH cases needed to be explored to rule out BA. In conclusion. false positive rate of clinical impression of BA was 37.8 %. and negative exploration rate was 8.9 %, Therefore. careful clinical observation for 1-2 weeks by an experienced pediatric surgeon was very important to avoid unnecessary operation to rule out NH up to the age of 8 - 10 weeks. so long as the stool had yellow component.

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Usefulness of Scan Position Change on Dual Time Point PET-CT in Pancreas Cancer (췌장암 Dual Time Point PET/CT 검사에서 Scan Position Change의 유용성 평가)

  • Chang, Boseok;Kim, Jae Ho
    • Journal of the Korean Society of Radiology
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    • v.10 no.5
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    • pp.299-305
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    • 2016
  • Despite of the development of medical equipments and technology. Pancreatic cancer has maked high false positive rate and low survival rate compared to other cancers. Therefore, early catch of pancreatic cancer is the only way to enhance the viability. It is important to find the exact location of the pancreas cancer in early stage. The method of optimum scan for early detection of pancreatic cancer on PET/CT exam is proposed. Examined the anatomical region that potentially can be missing from the supine position of ordinary pet/ct exam. The characteristics and usefulness of angle variation ($0^{\circ}$, $30^{\circ}$, $45^{\circ}$, $60^{\circ}$, $90^{\circ}$) of patients scan position is analyzed. The proposed scan method (named JJ-projection) is bringing advantage of anatomical discrimination by separating stomach, liver, gallbladder duodenum and pancreas. ROC curve analysis is shows to advantage of the JJ-Projection method. The sensitivity has increased 4.6% than the supine delay scan method, the results sensitivity has increased from 91% to 95.2%. The specificity has increased from 75.1% to 84%. Compared with the results observed in cancer by biological biopsy, The accuracy has increased from 86.8% to 94.1%.

Comparison of Diagnostic Accuracy for Detecting Coronary Artery Disease of Dipyridamole $^{99m}Tc$-MIBI Myocardial SPECT and It's Defect Map between Men and Women (디피리다몰 부하 $^{99m}Tc$-MIBI 심근 SPECT 극성결손지도를 이용한 관동맥질환 진단의 남녀 비교)

  • Bae, Sang-Kyun;Lee, Dong-Soo;Oh, Byung-Hee;Chung, June-Key;Lee, Myoung-Mook;Park, Young-Bae;Lee, Myung-Chul;Seo, Jung-Don;Lee, Young-Woo;Koh, Chang-Soon
    • The Korean Journal of Nuclear Medicine
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    • v.27 no.1
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    • pp.59-64
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    • 1993
  • To evaluate the usefulness and differences in diagnosing coronary artery disease (CAD) between men and women of intravenous dipyridamole $^{99m}Tc$-MIBI myocardial SPECT, we obtained $^{99m}Tc$-MIBI myocardial SPECT and compared with the findings of coronary angiographies. Ninety eight male and 37 female patients who underwent dipyridamole $^{99m}Tc$-MIBI myocardial imaging within one month of cardiac catheterization were studied. Scans were considered abnormal if perfusion defect was detected and the defect size was more than 12% for left anterior descending artery (LAD) and circumflex (LCX) and 8% for right coronary artery (RCA) territories. Lesions${\geqq}$50% luminal diameter narrowing were considered significant CAD. Overall sensitivity for detection of CAD was 94.3% in men and 96.4% in women; specificity was 70% in men and 52.6% in women (P=not significant, ns). Vessel-matched sensitivity was 75.3% in men and 72.7% in women (P=ns): specificity was 84.6% in men and 67.9% in women (P < 0.025). For individual coronary artery, the sensitivity in men and women was 87.7%, 81.8% for LAD; 78%, 83.3% for RCA and 52.2%, 46.7% for LCX (P=ns): the specificity was 80%, 40% for LAD (P<0.01), 82.5%, 68.4% for RCA, 88.9%, 86.4% for LCX (P=ns). The hemodynamic parameter after intravenous dipyridamole in men and women were significantly changed; the heart rate was increased and systolic, diastolic blood pressure was decreased. Adverse effects were reported in 58.8% of men and 72.7% in women (P=ns). The incidence of chest pain and headache were higher in women. There was no significant difference in the incidences of nausea, abdominal pain, dizziness, facial flushing, dyspnea. In conclusion, dipyridamole $^{99m}Tc$-MIBI myocardial SPECT is a safe, noninvasive test for evaluation of CAD. There was no gender difference to detect CAD, but more false-positive rate in women especially in the territory of LAD.

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Fire Detection Approach using Robust Moving-Region Detection and Effective Texture Features of Fire (강인한 움직임 영역 검출과 화재의 효과적인 텍스처 특징을 이용한 화재 감지 방법)

  • Nguyen, Truc Kim Thi;Kang, Myeongsu;Kim, Cheol-Hong;Kim, Jong-Myon
    • Journal of the Korea Society of Computer and Information
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    • v.18 no.6
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    • pp.21-28
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    • 2013
  • This paper proposes an effective fire detection approach that includes the following multiple heterogeneous algorithms: moving region detection using grey level histograms, color segmentation using fuzzy c-means clustering (FCM), feature extraction using a grey level co-occurrence matrix (GLCM), and fire classification using support vector machine (SVM). The proposed approach determines the optimal threshold values based on grey level histograms in order to detect moving regions, and then performs color segmentation in the CIE LAB color space by applying the FCM. These steps help to specify candidate regions of fire. We then extract features of fire using the GLCM and these features are used as inputs of SVM to classify fire or non-fire. We evaluate the proposed approach by comparing it with two state-of-the-art fire detection algorithms in terms of the fire detection rate (or percentages of true positive, PTP) and the false fire detection rate (or percentages of true negative, PTN). Experimental results indicated that the proposed approach outperformed conventional fire detection algorithms by yielding 97.94% for PTP and 4.63% for PTN, respectively.

Use of Sentinel Lymph Node Biopsy after Neoadjuvant Chemotherapy in Patients with Axillary Node-Positive Breast Cancer in Diagnosis

  • Choi, Hee Jun;Kim, Isaac;Alsharif, Emad;Park, Sungmin;Kim, Jae-Myung;Ryu, Jai Min;Nam, Seok Jin;Kim, Seok Won;Yu, Jonghan;Lee, Se Kyung;Lee, Jeong Eon
    • Journal of Breast Cancer
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    • v.21 no.4
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    • pp.433-4341
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    • 2018
  • Purpose: This study aimed to evaluate the effects of sentinel lymph node biopsy (SLNB) on recurrence and survival after neoadjuvant chemotherapy (NAC) in breast cancer patients with cytology-proven axillary node metastasis. Methods: We selected patients who were diagnosed with invasive breast cancer and axillary lymph node metastasis and were treated with NAC followed by curative surgery between January 2007 and December 2014. We classified patients into three groups: group A, negative sentinel lymph node (SLN) status and no further dissection; group B, negative SLN status with backup axillary lymph node dissection (ALND); and group C, no residual axillary metastasis on pathology with standard ALND. Results: The median follow-up time was 51 months (range, 3-122 months) and the median number of retrieved SLNs was 5 (range, 2-9). The SLN identification rate was 98.3% (234/238 patients), and the false negative rate of SLNB after NAC was 7.5%. There was no significant difference in axillary recurrence-free survival (p=0.118), disease-free survival (DFS; p=0.578) or overall survival (OS; p=0.149) among groups A, B, and C. In the subgroup analysis of breast pathologic complete response (pCR) status, there was no significant difference in DFS (p=0.271, p=0.892) or OS (p=0.207, p=0.300) in the breast pCR and non-pCR patients. Conclusion: These results suggest that SLNB can be feasible and oncologically safe after NAC for cytology-determined axillary node metastasis patients and could help reduce arm morbidity and lymphedema by avoiding ALND in SLN-negative patients.

Comparison of a whole blood Interferon-γ assay and A tuberculin skin test for detecting latent tuberculosis infection in children (소아 잠복 결핵 감염 진단에 있어서 투베르쿨린 피부반응 검사와 결핵 특이항원 자극 Interferon-γ 분비능 측정의 비교)

  • Chun, Jin-Kyong;Kim, Chang Ki;Kim, Hyun Sook;Jung, Ghee Young;Linton, John A.;Kim, Ki Hwan;Lee, Taek Jin;Jeon, Ji Hyun;Kim, Dong Soo
    • Clinical and Experimental Pediatrics
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    • v.51 no.9
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    • pp.971-976
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    • 2008
  • Purpose : Surveillance for detecting and managing latent tuberculosis infection (LTBI) is a key component of tuberculosis control. The classic surveillance tool, the tuberculin skin test (TST), may have some limitations when used in the Bacillus Calmette-$Gu{\acute{e}}rin$ (BCG)-vaccinated population. The object was to perform a blood test $QuantiFERON^{(R)}$-TB Gold In Tube (QFT-G IT) based on the detection of interferon-$\gamma$ ($IFN-{\gamma}$) released by T cells in response to Mycobacterium tuberculosis-specific antigens, and to compare the efficacy of this new diagnostic tool for LTBI with that of TST. Methods : For six months, between October 1, 2006 and April 30, 2007, data were collected from 111 patients under 15 years of age at Severance Children's Hospital. TST and QFT-G IT tests were performed with children with or without contact histories of tuberculosis. In addition to these tests, we examined comparative data from 29 adults who had tuberculosis, to detect false negative rates in the QFT-G IT method. Results : Thirty-three children had household contact histories. In this group, 15% and 42% of cases were found to be positive using the QFT-G IT assay and TST, respectively. Agreement was low between these two tests (${\kappa}=0.39$). In the adult active tuberculosis group, the QFT-G IT false negative rate defined as a positive culture and a negative QFT-G IT result was 12.5%. Conclusion : In diagnosing LTBI in children, the usefulness of a whole-blood $IFN-{\gamma}$ assay employing TB-specific antigens will be revealed only by examining additional longitudinal clinical data; this study serves as a starting point in that process.

Automatic Text Extraction from News Video using Morphology and Text Shape (형태학과 문자의 모양을 이용한 뉴스 비디오에서의 자동 문자 추출)

  • Jang, In-Young;Ko, Byoung-Chul;Kim, Kil-Cheon;Byun, Hye-Ran
    • Journal of KIISE:Computing Practices and Letters
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    • v.8 no.4
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    • pp.479-488
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    • 2002
  • In recent years the amount of digital video used has risen dramatically to keep pace with the increasing use of the Internet and consequently an automated method is needed for indexing digital video databases. Textual information, both superimposed and embedded scene texts, appearing in a digital video can be a crucial clue for helping the video indexing. In this paper, a new method is presented to extract both superimposed and embedded scene texts in a freeze-frame of news video. The algorithm is summarized in the following three steps. For the first step, a color image is converted into a gray-level image and applies contrast stretching to enhance the contrast of the input image. Then, a modified local adaptive thresholding is applied to the contrast-stretched image. The second step is divided into three processes: eliminating text-like components by applying erosion, dilation, and (OpenClose+CloseOpen)/2 morphological operations, maintaining text components using (OpenClose+CloseOpen)/2 operation with a new Geo-correction method, and subtracting two result images for eliminating false-positive components further. In the third filtering step, the characteristics of each component such as the ratio of the number of pixels in each candidate component to the number of its boundary pixels and the ratio of the minor to the major axis of each bounding box are used. Acceptable results have been obtained using the proposed method on 300 news images with a recognition rate of 93.6%. Also, my method indicates a good performance on all the various kinds of images by adjusting the size of the structuring element.

How Reliable is Sputum PCR Test in the Diagnosis of Pulmonary Tuberculosis When Sputum Smear is Negative? (객담 결핵균 도말검사가 음성일때 중합효소연쇄반응검사와 진단적 신뢰도에 관한 연구)

  • Baek, Seung-Hoon;Lee, Jae-Myung;Kang, Min-Jong;Son, Jee-Woong;Lee, Seung-Joon;Kim, Dong-Gyu;Lee, Myung-Goo;Hyun, In-Gyu;Jung, Ki-Suck;Lee, Kyung-Wha;Joe, Hyun-Chan
    • Tuberculosis and Respiratory Diseases
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    • v.50 no.2
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    • pp.222-228
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    • 2001
  • Backgrounds : Recent technological developments have introduced a new method to identifying M. tuberculosis complex DNA in clinical samples directly. The direct amplification test (DAT) is approved for identifying M. tuberculosis complex in respiratory specimens that are smear-positive for acid-fast bacilli (AFB). When there is a discrepancy between the AFB smear and DAT, no information on their clinical utility is currently available. In this study, the diagnostic reliability of DAT was investigated in suspected pulmonary tuberculosis patients whose sputum AFB smear was negative. Methods : From June 1, 1998 through May 30, 1999, 909 patients with presumed active pulmonary tuberculosis were enrolled. A sputum AFB stain, culture, DAT and/or biopsy were performed. Using the criteria of clinical tuberculosis or confirmed tuberculosis, the positive predictive value of DAT in diagnosing pulmonary tuberculosis was investigated. Results : The positive predictive value of DAT was 82.1% by the clinically active tuberculosis criteria. However, it decreased to 61.5% when diagnosis was restricted to only to culture positive or biopsy proven cases. The false positive rate of DAT was 18.0%. Conclusion : The DAT is a valuable diagnostic method in suspected patients whose sputum AFB is was negative.

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A study of Diagnostic Significance of Simultaneous Examination of Proteinuria and Hematuria in the Urinary Mass Screening (집단뇨검사(Urinary mass screening) 방법으로 단백뇨와 혈뇨의 동시검사가 가지는 진단적 가치에 대한 연구)

  • Kim, Young-Kyoun;Lee, Chong-Guk
    • Childhood Kidney Diseases
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    • v.3 no.1
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    • pp.57-63
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    • 1999
  • Purpose : To evaluate the diagnostic significance of simultaneous examination of hematuria and proteinuria in the urinary mass screening for early detection ot incipient renal diseases. Method and Object : During the period of 4 months from August to December in 1997, we did urinary mass screening on students of first grade of high school (16 years aged group) nationwide together with Korean Association of Health(KAH). In the first screening test, Comber-10 $N^{(R)}$ M dipsticks were used to detect proteinuria, hematuria, pyuria and nitrite simultaneously. Total 26,508 students (16 years aged group) from 33 high schools in every province in Korea, respectively, complied to the urinary mass screening. After then, one high school in Seoul was selected to reveal the true incidence of incipient renal diseases among students who showed hematuria in the initial screening through intensive examinations. Those who had hematuria and/or proteinuria visited the Paik hospital, and underwent blood tests and ultrasonographic examinations. The results were evaluated. Results 1) The initial screening revealed that the prevalence of proteinuria, hematuria, pyuria and positive nitrite urine, were $0.73\%,\;2.69\%,\;0.23\%\;and\;0.03\%$, respectively. 2) The first urinary screening among 875 students from one high school in Seoul selected fir the second test showed proteinuria, hematuria, pyuria and positive nitrite urine, were $0.91\%,\;4.68\%,\;0.34\%\;and\;0\%$, respectively. a) Total 8 among 875 students showed proteinuria, but one of them had orthostatic proteinuria and those remaining 7 students had transient proteinuria. b) There were 41 students who had hematuria in the initial screening. Among 33 who complied the second test, only one student showed asymptomatic isolated hematuria and those remaining students were normal. Conclusion : 1) Because of high false positive hematuria rate in the urinary mass screening, it dosen't seem to be appropriate that hematuria screening using dipsticks be included in the urinary mass screening. 2) A unified organization is needed from the fret that so various results of urinary mass screening came out. 3) Positive rates of pyuria and nitrite were so low that validity of urinary mass screening for urinary tract infection needs more studies.

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