scholarly journals BioPEPR: a system for the automatic prescreening of cervical smears.

1979 ◽  
Vol 27 (1) ◽  
pp. 635-641 ◽  
Author(s):  
D J Zahniser ◽  
P S Oud ◽  
M C Raaijmakers ◽  
G P Vooys ◽  
R T Van de Walle
Keyword(s):  
False Positive ◽  
False Positive Rate ◽  
False Negative ◽  
Intermediate Step ◽  
Decision Strategy ◽  
Cervical Smears ◽  
Cathode Ray Tube ◽  
Hierarchical Decision ◽  
Positive Rate

A feasibility study has indicated that a Prescion Encoding and Pattern Recognition (PEPR) cathode ray tube prescreening system for cervical smears can be both accurate and fast. Smears are prepared using a syringing technique and are stained with a Feulgen-type nuclear stain and a protein counter-stain. The use of film as an intermediate step between the cells and Bio PEPR allows the scanning of fields as large as 8 x 8 mm. The morphological features of the cells are measured as directed by a hierarchical decision strategy. Additional programs detect artifacts, overlaps, and leukocytes. For clean samples, false positive and false negative rates on the cell level have been obtained that will allow acceptable smear level rates (10% false positive, 1% false negative). These rates have been reached without compromising the required speed goals of 120 to 180 smears per hr. The efficiency of the system is dependent on the quality of the smears. Measurements on a set of 192 routinely prepared smears indicate acceptable false negative rates and a false positive rate of about 18%. A reduction of this rate is expected with small improvements in cell preparation and measuring software, leading to the overall system efficiency required for commercial feasibility.

scholarly journals Evaluation of optimal urine screening and confirmation cut-off values for opiates, at a national reference laboratory

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Çiğdem Karakükcü ◽  
Mehmet Zahid Çıracı ◽  
Derya Kocer ◽  
Mine Yüce Faydalı ◽  
Muhittin Abdulkadir Serdar
Keyword(s):  
False Positive ◽  
False Positive Rate ◽  
False Negative ◽  
Urine Samples ◽  
Reference Laboratory ◽  
National Reference Laboratory ◽  
Urine Screening ◽  
National Reference ◽  
Positive Rate ◽  
Sensitivity Specificity

Abstract Objectives To obtain optimal immunoassay screening and LC-MS/MS confirmation cut-offs for opiate group tests to reduce false positive (FP) and false negative (FN) rates. Methods A total of 126 urine samples, −50 opiate screening negative, 76 positive according to the threshold of 300 ng/mL by CEDIA method – were confirmed by a full-validated in-house LC-MS/MS method. Sensitivity, specificity, FP, and FN rates were determined at cut-off concentrations of both 300 and 2,000 ng/mL for morphine and codeine, and 10 ng/mL for heroin metabolite 6-mono-acetyl-morphine (6-MAM). Results All CEDIA opiate negative urine samples were negative for morphine, codeine and 6-MAM. Although sensitivity was 100% for each cut-off; specificity was 54.9% at CEDIA cut-off 300 ng/mL vs. LC-MS/MS cut-off 300 ng/mL and, 75% at CEDIA cut-off 2,000 ng/mL vs. LC-MS/MS cut-off 2,000 ng/mL. False positive rate was highest (45.1%) at CEDIA cut-off 300 ng/mL. At CEDIA cut-off 2,000 ng/mL vs. LC-MS/MS cut-off 300 ng/mL, specificity increased to 82.4% and FP rate decreased to 17.6%. All 6-MAM positive samples had CEDIA concentration ≥2,000 ng/mL. Conclusions 2,000 ng/mL for screening and 300 ng/mL for confirmation cut-offs are the most efficient thresholds for the lowest rate of FP opiate results.

Computed Tomography in Partial Carpal Arthrodesis

1997 ◽  
Vol 22 (5) ◽  
pp. 653-655
Author(s):  
J. M. SOLER-MINOVES ◽  
J. GONZALEZ-USTES ◽  
R. PÉREZ ◽  
M. GIFREU ◽  
A. M. GALLART
Keyword(s):  
Computed Tomography ◽  
False Positive ◽  
False Positive Rate ◽  
False Negative ◽  
Plain Radiography ◽  
X Rays ◽  
Positive Rate

We carried out X-rays and computed tomography in 59 wrists in patients who had previous surgical intercarpal fusions. 1.2 mm thick axial images were obtained perpendicular to the axis of the joint. CT showed whether or not the carpal fusions were united. Compared with CT, plain radiography yielded a 25% false negative and 6% false positive rate. We conclude that CT is more useful than plain X-rays for evaluating partial carpal arthrodesis.

Pathologic Assessment of Computerized Tomography Accuracy for the Evaluation of the Laryngeal Cartilaginous Frame Work in Laryngopharyngeal Carcinomas

1989 ◽  
Vol 75 (2) ◽  
pp. 156-162 ◽  
Author(s):  
Sandro Sulfaro ◽  
Francesco Querin ◽  
Luigi Barzan ◽  
Mario Lutman ◽  
Roberto Comoretto ◽  
...  
Keyword(s):  
Computerized Tomography ◽  
False Positive ◽  
False Positive Rate ◽  
False Negative ◽  
False Negative Rate ◽  
Cartilage Destruction ◽  
High False Negative Rate ◽  
Positive Rate ◽  
Pathologic Assessment ◽  
Low Sensitivity

Sixty-six whole-organ sectioned laryngopharyngectomy specimens removed for cancer during a seven-year period were uniformly examined to determine the accuracy of preoperative high resolution computerized tomography (CT) for detection of cartilaginous involvement. Our results indicate that CT has a high overall specificity (88.2%) but a low sensitivity (47.1 %); we observed a high false-negative rate (26.5%) and a fairly low false-positive rate (5.9%). Massive cartilage destruction was easily assessed by CT, whereas both small macroscopic and microscopic neoplastic foci of cartilaginous invasion were missed on CT scans. Moreover, false-positive cases were mainly due to proximity of the tumor to the cartilage. Clinical implications of these results are discussed.

The Effects of Payoff on the Visual Processing of Dental Radiographs

1978 ◽  
Vol 20 (4) ◽  
pp. 385-390 ◽  
Author(s):  
William H. Mobley ◽  
Irwin L. Goldstein
Keyword(s):  
Visual Processing ◽  
False Positive ◽  
False Positive Rate ◽  
Dental Students ◽  
Technical Quality ◽  
Observer Error ◽  
Positive Rate ◽  
Dental Radiographs ◽  
Payoff Condition

The objective of the present study was to reassess the magnitude of observer error by dental students observing dental radiographs. Additionally, the effects of different payoff conditions on observer responses were examined. These data indicated high false positive rates as well as an inability to judge which radiographs were most difficult to assess. Further analyses indicated that false positive rates remained high even when payoff conditions penalized such responses. A payoff condition specifically designed to lower the false positive rate instead resulted in subjects lowering their hit rate and thus raising the miss rate. It is apparent that control of observer error must not only consider the technical quality of the radiograph but also the decision processes of the observer.

scholarly journals Flow microfluorometric system for screening gynecologic cytology specimens using propidium iodide-fluorescein isothiocyanate.

1976 ◽  
Vol 24 (1) ◽  
pp. 322-331 ◽  
Author(s):  
B J Fowlkes ◽  
C J Herman ◽  
M Cassidy
Keyword(s):  
Data Analysis ◽  
Propidium Iodide ◽  
False Positive ◽  
False Positive Rate ◽  
False Negative ◽  
False Negative Rate ◽  
Fluorescein Isothiocyanate ◽  
Clinical Specimens ◽  
Positive Rate ◽  
Abnormal Cells

Seventy cervical cytology specimens have been screened by a xero resolution flow analyzer-sorter using propidium iodide and fluorescein isothiocyanate as fluorochromes for nucleus and cytoplasm, respectively. This system shows a 1% sensitivity for detection of abnormal cells using only crude visual data analysis. Screening of clinical specimens was performed on the instrument with a 5.8% false negative rate and a 11.8% false positive rate by comparison with routine visual cytologic evaluation of the same samples.

High Resolution CT and Bronchography in the Assessment of Bronchiectasis

1991 ◽  
Vol 32 (6) ◽  
pp. 439-441 ◽  
Author(s):  
K. Young ◽  
F. Aspestrand ◽  
A. Kolbenstvedt
Keyword(s):  
Retrospective Study ◽  
High Resolution ◽  
False Positive ◽  
False Positive Rate ◽  
False Negative ◽  
False Negative Rate ◽  
High Resolution Ct ◽  
Negative Rate ◽  
Different Types ◽  
Positive Rate

To elucidate the reliability of CT in the assessment of bronchiectasis, a retrospective study of high resolution CT and bronchography was carried out. A segment by segment comparison of 259 segmental bronchi from 70 lobes of 27 lungs in 19 patients was performed using bronchography as standard. CT was positive in 87 of 89 segmental bronchi with bronchiectasis giving a false-negative rate of 2%. CT was negative in 169 of 170 segmental bronchi without bronchiectasis at bronchography, giving a false-positive rate of 1%. There was agreement between the two modalities in identifying the different types of bronchiectasis.

Hand Gesture Recognition using Ensembles of Radial Basis Function (RBF) Networks and Decision Trees

1997 ◽  
Vol 11 (06) ◽  
pp. 845-872 ◽  
Author(s):  
Srinivas Gutta ◽  
Ibrahim F. Imam ◽  
Harry Wechsler
Keyword(s):  
Human Computer Interaction ◽  
Decision Trees ◽  
Gesture Recognition ◽  
False Positive ◽  
Cross Validation ◽  
False Positive Rate ◽  
False Negative ◽  
False Negative Rate ◽  
Hand Gesture ◽  
Positive Rate

Hand gestures are the natural form of communication among people, yet human-computer interaction is still limited to mice movements. The use of hand gestures in the field of human-computer interaction has attracted renewed interest in the past several years. Special glove-based devices have been developed to analyze finger and hand motion and use them to manipulate and explore virtual worlds. To further enrich the naturalness of the interaction, different computer vision-based techniques have been developed. At the same time the need for more efficient systems has resulted in new gesture recognition approaches. In this paper we present an hybrid intelligent system for hand gesture recognition. The hybrid approach consists of an ensemble of connectionist networks — radial basis functions (RBF) — and inductive decision trees (AQDT). Cross Validation (CV) experimental results yield a false negative rate of 1.7% and a false positive rate of 1% while the evaluation takes place on a data base including 150 images corresponding to 15 gestures of 5 subjects. In order to assess the robustness of the system, the vocabulary of the gestures has been increased from 15 to 25 and the size of the database from 150 to 750 images corresponding now to 15 subjects. Cross Validation (CV) experimental results yield a false negative rate of 3.6% and a false positive rate of 1.8% respectively. The benefits of our hybrid architecture include (i) robustness via query by consensus as provided by ensembles of networks when facing the inherent variability of the image formation and data acquisition process, (ii) classifications made using decision trees, (iii) flexible and adaptive thresholds as opposed to ad hoc and hard thresholds and (iv) interpretability of the way classification and retrieval is eventually achieved.

scholarly journals KS(conf): A Light-Weight Test if a Multiclass Classifier Operates Outside of Its Specifications

2019 ◽  
Vol 128 (4) ◽  
pp. 970-995
Author(s):  
Rémy Sun ◽  
Christoph H. Lampert
Keyword(s):  
False Positive ◽  
False Positive Rate ◽  
A Priori ◽  
False Negative ◽  
True Positive Rate ◽  
Convolutional Network ◽  
The Road ◽  
Positive Rate ◽  
On The Road ◽  
Main Component

Abstract We study the problem of automatically detecting if a given multi-class classifier operates outside of its specifications (out-of-specs), i.e. on input data from a different distribution than what it was trained for. This is an important problem to solve on the road towards creating reliable computer vision systems for real-world applications, because the quality of a classifier’s predictions cannot be guaranteed if it operates out-of-specs. Previously proposed methods for out-of-specs detection make decisions on the level of single inputs. This, however, is insufficient to achieve low false positive rate and high false negative rates at the same time. In this work, we describe a new procedure named KS(conf), based on statistical reasoning. Its main component is a classical Kolmogorov–Smirnov test that is applied to the set of predicted confidence values for batches of samples. Working with batches instead of single samples allows increasing the true positive rate without negatively affecting the false positive rate, thereby overcoming a crucial limitation of single sample tests. We show by extensive experiments using a variety of convolutional network architectures and datasets that KS(conf) reliably detects out-of-specs situations even under conditions where other tests fail. It furthermore has a number of properties that make it an excellent candidate for practical deployment: it is easy to implement, adds almost no overhead to the system, works with any classifier that outputs confidence scores, and requires no a priori knowledge about how the data distribution could change.

scholarly journals Evaluating the usefulness of breast strain elastography for intraductal lesions

2021 ◽  
Author(s):  
Yumi Kokubu ◽  
Keiko Yamada ◽  
Masahiko Tanabe ◽  
Ayumi Izumori ◽  
Chieko Kato ◽  
...  
Keyword(s):  
False Positive ◽  
False Positive Rate ◽  
False Negative ◽  
False Negative Rate ◽  
Intraductal Papilloma ◽  
Breast Diseases ◽  
Strain Elastography ◽  
Negative Rate ◽  
Positive Rate ◽  
Sensitivity Specificity

Abstract Purpose Strain elastography for imaging lesion stiffness is being used as a diagnostic aid in the malignant/benign discrimination of breast diseases. While acquiring elastography in addition to B-mode images has been reported to help avoid performing unnecessary biopsies, intraductal lesions are difficult to discriminate whether they are malignant or benign using elastography. An objective evaluation of strain in lesions was performed in this study by measuring the elasticity index (E-index) and elasticity ratio (E-ratio) of lesions as semi-quantitative numerical indicators of the color distribution of strain. We examined whether ductal carcinoma in situ (DCIS) and intraductal papilloma could be distinguished using these semi-quantitative numerical indicators. Methods In this study, 170 ultrasonographically detected mass lesions in 162 cases (106 malignant lesions and 64 benign lesions)—in which tissue biopsy by core needle biopsy and vacuum-assisted biopsy, or surgically performed histopathological diagnosis, was performed—were selected as subjects from among 1978 consecutive cases (from January 2014 to December 2016) in which strain elastography images were acquired, in addition to standard B-mode breast ultrasonography, by measuring the E-index and E-ratio. Results The cut-off values for E-index and E-ratio in the malignant/benign discrimination of breast lesions were determined to be optimal values at 3.5 and 4.2, respectively, based on receiver operating characteristic (ROC) curve analysis. E-index sensitivity, specificity, accuracy, and AUC value (area under the curve) were 85%, 86%, 85%, and 0.860, respectively, while those for E-ratio were 78%, 74%, 74%, and 0.780, respectively. E-index yielded superior results in all aspects of sensitivity, specificity, accuracy, and AUC values, compared to those of E-ratio. The mean E-index values for malignant tumors and benign tumors were 4.46 and 2.63, respectively, indicating a significant difference (P < 0.001). E-index values of 24 DCIS lesions and 25 intraductal papillomas were 3.88 and 3.35, respectively, which showed a considerably close value, while the false-negative rate for DCIS was 29.2%, and the false-positive rate for intraductal papilloma was as high as 32.0%. Conclusion E-index in strain elastography yielded better results than E-ratio in the malignant/benign discrimination of breast diseases. On the other hand, E-index has a high false-negative rate and false-positive rate for intraductal lesions, a factor which should be taken into account when making ultrasound diagnoses.

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