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The effect of dependence on the performance of Bayes' theorem: an evaluation using a computer simulation.

A computer simulation is described which generates 'cases' of vaginal discharge. This simulation was used to evaluate the potential effects of dependence between clinical features on the diagnostic performance of Bayes' theorem. The following observations were made: (1) dependence between some but not all pairs of features reduced the overall diagnostic efficiency (judged by the number of true positive diagnoses); (2) the overall reduction in efficiency was never substantial; (3) the largest effects on the diagnosis of individual conditions was observed with rarer diseases, and with combinations of features which were inherently unlikely to be dependent. It is concluded that the diagnostic efficiency of Bayes' theorem will not be greatly influenced by dependence if a reasonable amount of commonsense is applied to the selection of the knowledge base.

Bayes Theorem↗

Diagnostic and prognostic performance of N-terminal ProBNP in primary care patients with suspected heart failure.

BACKGROUND: The value of N-terminal pro-brain natriuretic peptide (NT-proBNP) in terms of diagnosis and prognosis in congestive heart failure (CHF) and left ventricular systolic dysfunction (LVSD) has been demonstrated previously in various populations, but data on primary care patients are sparse. The aim of this study was to evaluate the diagnostic and prognostic performance of NT-proBNP in primary care patients with suspected CHF. METHODS AND RESULTS: Three hundred sixty-seven consecutive patients (mean age, 68.8 years; range, 39.0-84.0 years) who had been referred by their general practitioner for echocardiographic evaluation because of suspected CHF. In all patients, NT-proBNP was measured at baseline and left ventricular ejection fraction (LVEF) was estimated with echocardiography. LVSD (LVEF < or =0.40) was found in 9% of the patients. NT-proBNP was significantly higher in patients with LVSD (P < .0001). With predefined cut off values for NT-proBNP (125 pg/mL), the sensitivity, specificity, positive predictive value, and negative predictive value for the detection of LVSD were 0.97, 0.46, 0.15 and 0.99, respectively. Area under the receiver operating characteristic curve was 0.87. The application of an age-differentiated cut-off value for NT-proBNP (125 pg/mL for <75 years old and 450 pg/mL for > or =75 years old) did not increase diagnostic performance. Patients were followed for a median of 778 days; 8% of the patients died during the follow-up period. The mortality rate was higher in patients with NT-proBNP of >125 pg/mL than in patients with normal values (P < .002, log rank), and the difference persisted after controlling for age, gender, and LVEF (hazard ratio per unit increase in log NT-proBNP, 2.2; range, 1.2-4.1; P = .015). CONCLUSION: In primary care patients who were referred for echocardiography because of suspected CHF, NT-proBNP values <125 pg/mL effectively rule out LVSD. Furthermore low NT-proBNP values are associated with a lower risk of death, independently of age, gender, and LVEF.

Adult↗

[Diagnostic possibilities of the flexible hysteroscopy in irregular uterine bleeding].

The aim of the present study was to evaluate the possibilities of diagnostic flexible hysteroscopy for women with irregular uterine bleeding. The study was based on 569 women aged between 26 and 72 years (mean age 46.78 years) with weak to moderate irregular uterine bleeding who had given agreement for invasive investigations. To all patients initially was performed diagnostic hysteroscopy with the help of a panoramic fibrohysteroscope Pentax LH-150 II (with 5 mm diameter), followed by classical endometrial curettage. The performed hysteroscopies found phase or other normal endometrium at 208 women (36.56%), hyperplasia and poliposis at 258 (45.34%), changes, suspected for atypia and neoplasia at 77 (13.53%) and other different findings at 26 women (4.57%). The following curettage showed the lack of adequate material from uterine cavity at 24 women (4.2%). From the rest patients, at 466 (81.9%) the morphological findings were due to the dysfunctional reasons, other 51 (8.9%) were with different precancer and cancer lesions and at 28 cases, clinically and morphologically was found that the bleeding was due to the presence of sub mucous nodules, intrauterine devices, residua and pathology of the chorion. The comparison of the hysteroscopy results with the clinical and histological findings from the curettage of 454 women, showed good diagnostic possibilities (sensitivity of 78.4% and specificity of 92.5%) of the flexible hysteroscopy for evaluation of women with irregular uterine bleeding. This examination is relatively simple and save endoscopic technique, which require simultaneously performance of a direct biopsy, in order to improve its diagnostic accuracy.

Adult↗

Diagnostic value of HRCT and 3DCT in the assessment of chronic maxillary sinusitis.

In a group of 37 patients with chronic maxillary sinusitis in whom CT examination had been performed diagnostic value of secondary spatial reconstructions and high-resolution sections was analysed. It was found that the supplementation of standard CT examination with high-resolution sections and spatial pictures increases diagnostic possibilities in the assessment of maxillary sinusitis as for recognising, differentiating and determining anatomical etiologic factors.

Chronic Disease↗

Investigation of the infertile couple: should diagnostic laparoscopy be performed in the infertility work up programme in patients undergoing intrauterine insemination?

Diagnostic laparoscopy is normally the standard procedure performed as the final test in the infertility work up before progressing to infertility treatment. Recently, there has been a growing tendency to bypass diagnostic laparoscopy after a normal hysterosalpingogram and instead to start direct infertility treatment [intrauterine insemination (IUI) or IVF] for indications such as unexplained infertility, male subfertility and cervical hostility. In our clinic, laparoscopy revealed abnormalities that resulted in changed treatment decisions in 25% of the patients who would normally have been scheduled for IUI if laparoscopy had not been performed. The changed treatments mainly concerned surgery for minimal/mild endometriosis and periadnexal adhesions, both performed during the diagnostic laparoscopy. Because the effect of such interventions on the success rate of IUI has never been described, it still remains unclear whether laparoscopy is usefully performed in these cases. Therefore, further prospective studies should be performed to assess whether delaying, or bypassing entirely, diagnostic laparoscopy is more cost effective and if laparoscopic interventions for intra-abdominal abnormalities are effective in terms of higher pregnancy rates after treatment with IUI.

Endometriosis↗

[Performance of an open low-field MR unit in routine examination of knee lesions and comparison with high field systems].

The purpose of this study was to analyze the diagnostic value of a low-field open MR system in the diagnosis of knee lesions and to compare it with that of high-field MR systems. In 139 knees,arthroscopic investigations were used as the gold standard to calculate sensitivity, specificity, predictive values and accuracy of the low-field open MR system. Figures for high field systems were taken from the literature. The values for the open MR system relative to arthroscopy were as follows: sensitivity 66%,specificity 95%,positive predictive value 64%,negative predictive value 92%, and accuracy 82%. The corresponding values taken from 10 relevant publications for highfield systems were: sensitivity 81%, specificity 90%, accuracy 90%. A lower diagnostic performance has to be expected using open low field MR units for knee lesions in comparison to high field units. Sedative drugs can make it possible for claustrophobic patients to be investigated in high-field units. The use of open low-field scanners may still be indicated in very adipose patients who do not fit into closed units.

Adolescent↗

The eyes have it. How good is DIAGNOdent at detecting caries?

DATA SOURCES: Medline (1999-June 2004) provided the primary data source with references from one paper being reviewed for additional studies. The authors of one article were contacted for additional details. STUDY SELECTION: Articles, in English that assessed a commercially available caries detection device the DIAGNOdent (KaVo Dental GmbH Biberach), used human teeth with and without caries, and expressed diagnostic performance in terms of sensitivity and specificity of caries detection against a histological gold standard were included. DATA EXTRACTION AND SYNTHESIS: Data were extracted to determine whether articles included: an appropriate study population; an adequate description of the test; an appropriate reference standard; a blinded comparison of test and reference samples and avoidance of verification bias. No quality score was assigned. RESULTS: Of the 25 studies identified, 16 assessed the in vitro performance of DIAGNOdent (DD) on occlusal surfaces of primary and permanent posterior teeth, four reported similar in vivo assessments, two examined DD performance on smooth surfaces and the final three addressed detection of secondary caries and residual caries in simulated cavities. DD sensitivity scores for in vitro detection of occlusal dentinal caries ranged from 0.19 to 1.0 (n=16) with 14 of the 16 results being >/=0.73. Specificity values ranged from 0.52 to 1.00. DD tended to show higher sensitivity but lower specificity than visual assessment methods. Only four studies considered DD in vivo performance and demonstrated sensitivity from 0.73 to 0.96 and specificity from 0.63 to 0.95. CONCLUSIONS: In the limited studies available DD demonstrated greater sensitivity but poorer specificity than visual caries diagnosis. Combined with the fact that little in vivo evidence is available for DD performance, the greater number of false-positive diagnoses suggest it should not be relied on as a clinician's primary diagnostic method.

Comment↗

Computer-aided diagnosis of breast cancer in mammography: evidence and potential.

Computer-aided diagnosis (CAD) methods are being developed to help radiologists improve the interpretation of mammograms for the detection of breast cancer. We review several laboratory observer performance studies of computer-aided diagnosis of malignant and benign breast lesions. These studies show that CAD can improve radiologist diagnostic performance by increasing the number of their biopsy recommendations for actual malignant lesions while reducing the number of their biopsy recommendations for suspicious but actually benign lesions, and by reducing the variability in their interpretation of mammograms. These results indicate a potential clinical role of CAD in mammography for the detection of breast cancer.

Breast Neoplasms↗

Performance indexes of a dot-enzyme-linked immunosorbent assay (dot-ELISA) and an enzyme-linked immunosorbent assay (IgG-ELISA) for field surveys of New World leishmaniasis.

Diagnostic performance indexes of sensitivity, specificity, positive predictive value and efficiency were determined for dot-ELISA and IgG-ELISA tests in 340 leishmaniasis sera. Sensitivity of the dot-ELISA was significantly lower than IgG-ELISA's; the two tests had indexes of specificity and positive predictive value of the same magnitude. Seventy-eight sera gave a negative dot-ELISA test result and a positive IgG-ELISA test result. When sera were classified according to different criteria as how to interpret this diversity, the kappa statistic did not corroborate the classification indicating that the two tests display a substantial strength of agreement. The results presented indicate that performance indexes accrued in a survey where variables are well known may be extrapolated to other population studies if the disease presents itself as highly prevalent (due to a selection bias or not) and may be expected to discriminate a disease status among test positives.

Enzyme-Linked Immunosorbent Assay↗

Diagnosis of bone lesions by subtraction radiography.

Examiner diagnostic accuracy and response times were compared using subtraction and conventional radiography in a dog model. Osseous lesions were induced interproximally and through the mandibular buccal bone interradicularly and radicularly. Standardized preoperative and postoperative conventional radiographs of the induced lesions were compared to subtraction images of the same sites by 11 dentists. Examiners using the subtraction technique demonstrated improved diagnostic performance (P less than 0.001) and response times (P less than 0.001). Additionally, this method yielded a 30% reduction in equivocal diagnostic decisions. Data from this study suggest that subtraction radiography is a sensitive and accurate method to detect osseous lesions associated with periodontal diseases.

Alveolar Process↗

Developmental right-hemisphere syndrome: clinical spectrum of the nonverbal learning disability.

We report the clinical characteristics of the developmental right-hemisphere syndrome (DRHS), a nonverbal learning disability, in 20 children (9 girls and 11 boys; mean age = 9.5 years) who also manifested attention-deficit/hyperactivity disorder (ADHD), severe graphomotor problems, and marked slowness of performance. Diagnostic criteria for this study included (a) emotional and interpersonal difficulties; (b) paralinguistic communication problems; (c) impaired visuospatial skills, verbal IQ > performance IQ, and verbal IQ > or = 85; and either (d) dyscalculia or (e) neurological signs on the left side of the body. In this group, verbal IQ was significantly higher than performance IQ (106.6 +/- 13.0 vs. 85.1 +/- 13.1, respectively, p < .01). Arithmetic was the lowest score among the verbal subtests (7.8 +/- 3.5, p < .01) and Geometrical Design was the lowest score among the performance subtests (5.8 +/- 1.7). Thirteen children had soft neurological signs on the left side of the body. ADHD was seen in all 20 children, marked slowness of performance in 16, and severe graphomotor problems in 18. The latter two features have not been previously described as part of DRHS.

Adolescent↗

Use of commercial enzyme immunoassays and immunomagnetic separation systems for detecting Escherichia coli O157 in bovine fecal samples.

A commercial enzyme immunoassay (EIA) (E. coli O157 Visual Immunoassay; Tecra Diagnostics) performed on enrichment cultures in modified Escherichia coli broth (mECn) was compared with immunomagnetic separation (IMS) (Dynabeads anti-E. coli O157; Dynal) performed on enrichment cultures in modified buffered peptone water (BPW-VCC) for the detection of E. coli O157 in bovine fecal samples. Tests on fecal suspensions inoculated with each of 12 different strains of E. coli O157 showed that both the EIA and IMS methods were 10- to 100-fold more sensitive than direct culture or enrichment subculture methods for detection of the organism. EIA and IMS were then compared for detection of E. coli O157 in bovine rectal swabs. For confirmation of positive EIA tests, a commercial system (Immunocapture System [ICS]; Tecra Diagnostics) was compared with IMS; both were performed on mECn enrichment cultures. Of 200 rectal swabs examined, 17 gave positive results in the EIA which were confirmed by both confirmation systems, 2 gave positive results in the EIA which were confirmed by IMS but not by ICS, and 1 gave a positive result in the EIA which was confirmed by ICS but not by IMS. Of these 20, 15 were also positive by the BPW-VCC-IMS culture system; a further 3 samples were positive by this culture system but gave a negative result in the EIA. Eight samples were negative by the BPW-VCC-IMS culture system but gave a positive result in the EIA which could not be confirmed by either confirmation system. Further examination of the eight unconfirmed EIA-positive samples yielded sorbitol-fermenting E. coli O157 from three samples. Of the remaining five cultures, four were positive in an EIA for verocytotoxins (VT) and two were positive in a cell culture assay for VT1. The remaining 170 samples were negative by both EIA and BPW-VCC-IMS. The Tecra EIA and IMS are both technically simple and sensitive methods for detecting E. coli O157 in bovine fecal samples. There was no statistically significant difference between the numbers of positives detected by the different assays (P = 0.29).

Animals↗

Effect of quantum noise on the detection of incipient proximal caries.

The effect of quantum noise on the radiographyic detectability of proximal carious lesions was studied. Bitewing radiographs obtained from patients considered to be free of caries were digitized and stored in a computer using a sampling interval comparable to screen-film systems. Lesions limited in depth to one half the thickness of the enamel were induced by means of computer simulation. Various amounts of randomly generated quantum noise were added to each radiographic image. The results from observer-performance studies show that the lesions can be detected reliably in the presence of substantial amounts of quantum noise, suggesting that comparable diagnostic performance could be obtained with significantly faster imagining systems than those currently used in dentistry.

Analog-Digital Conversion↗

Posttreatment assessment of response using FDG-PET/CT for patients treated with definitive radiation therapy for head and neck cancers.

PURPOSE: The goal of this study was to evaluate coregistered [18F] fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT) for the detection of persistent disease after definitive radiation therapy in head and neck cancer. METHODS AND MATERIALS: Posttreatment FDG-PET/CT was performed in 28 patients on average 8 weeks (range, 4 to 15.7 weeks) after completing definitive radiation therapy. FDG-PET/CT was visually analyzed for the entire patient group and at two time points (4-8 and >8 weeks) after treatment. The contrast-enhanced CT portion of PET/CT was separately analyzed blinded to the results of coregistered FDG-PET/CT and classified as negative or positive for residual locoregional disease. Pathologic findings and clinical follow-up served as the reference standard. RESULTS: Follow-up data were available for all 28 patients (median, 17.6 months). Regarding the detection of residual disease, the overall sensitivity and specificity of FDG-PET/CT was 76.9% and 93.3%, respectively, compared with 92.3% and 46.7% for contrast-enhanced CT. The accuracy of FDG-PET/CT was 85.7%, compared with 67.9% for CT alone. All false-negative (n = 3) and false-positive (n = 1) FDG-PET/CT results occurred between 4 and 8 weeks after treatment. At 8 weeks or later after treatment, the specificity of CT was 28%, compared with 100% for FDG-PET/CT. CONCLUSIONS: The metabolic-anatomic information from coregistered FDG-PET/CT provided the most accurate assessment for treatment response when performed later than 8 weeks after the conclusion of radiation therapy. FDG-PET/CT excelled by a higher specificity and overall diagnostic performance than CT imaging alone. These results support a potential clinical role of FDG-PET/CT in the early assessment of therapy response after definitive radiation therapy.

Adult↗

Neural networks analysis of astrocytic gliomas from MRI appearances.

A three-layered backpropagation neural network was developed to differentiate malignant from benign brain tumors in a group of patients with astrocytic gliomas. The MRI findings of 43 patients were reviewed before biopsy by three neuroradiologists independently. This provided a database made up of 129 patients' records each of which comprised 13 parameters derived from pre- and post-contrast MR images. The network's generalizing ability was then tested to predict the outcome of biopsy in 36 new cases and its performance compared to that of radiologist using ROC analysis. The output of the network with and without radiologists' impression yielded a better diagnostic performance with relative ROC areas of 0.94 and 0.91, respectively; compared to 0.84 obtained by radiologist. These results demonstrate that the neural network can effectively differentiate malignant from benign brain tumors.

Algorithms↗

The dermatoscopic ABCD rule does not improve diagnostic accuracy of malignant melanoma.

The dermatoscopic ABCD rule has been suggested to improve diagnostic performance regarding cutaneous malignant melanoma. Using this rule, a total dermatoscopy score is calculated from the presence of various dermatoscopic elements. A total dermatoscopy score above 4.75 signifies possible and 5.45 probable melanoma. We compared the diagnostic accuracy of dermatoscopy with and without the use of the ABCD rule. Furthermore, receiver operating characteristic analysis was performed for the ABCD rule. The area under the receiver operating characteristic curve was 0.854 (range 0.777-0.906) demonstrating that in 85.4% of the cases, cutaneous malignant melanomas were rated higher than the non-melanoma skin lesions. Sensitivity for the melanoma diagnosis was higher for simple dermatoscopy than when the ABCD rule was used (p<0.05). There was no difference in specificity when a total dermatoscopy score of 4.75 was used as cut-off point, but specificity was lower for simple dermatoscopy than when the total dermatoscopy score of 5.45 was used. Diagnostic accuracy was higher for simple dermatoscopy than for the ABCD rule (p<0.01). In conclusion, the dermatoscopic ABCD rule was not superior to simple dermatoscopy, and fewer malignant melanomas were identified with this rule.

Biopsy, Needle↗

Preoperative diagnosis of ovarian tumors with MR imaging: comparison with transvaginal sonography, positron emission tomography, and histologic findings.

OBJECTIVE: Our study evaluated the diagnostic performance of MR imaging compared with that of transvaginal sonography and positron emission tomography (PET) in patients with clinically asymptomatic adnexal findings. An additional goal was to determine whether the combination of the three methods enhanced their diagnostic accuracy. SUBJECTS AND METHODS: Included in the study were 103 women with suspicious adnexal findings on sonography. Patients underwent transvaginal sonography, MR imaging, and PET within 3 weeks of the initial sonography. For MR imaging, axial and sagittal T1-weighted gradient-echo sequences (unenhanced and enhanced) and T2-weighted turbo-spin-echo sequences were acquired. Transvaginal sonography was performed with a 7.5-MHz transducer head. For PET, a modern full-ring scanner was used. The results of diagnostic imaging techniques were first evaluated separately, and reviewers were blinded to the results of other methods. Finally, a second session resulted in a consensus diagnosis based on the findings of all three methods. Results of histology were considered the gold standard. RESULTS: Histology revealed 12 malignant and 91 benign ovarian tumors. The following data were calculated for MR imaging, transvaginal sonography, PET, and consensus diagnosis: sensitivities, 83%, 92%, 58%, 92%; specificities, 84%, 59%, 78%, 84%; diagnostic accuracies, 83%, 63%, 76%, 85%, respectively. MR imaging, particularly with contrast-enhanced fat-saturated T1-weighted sequences, was found to correctly reveal dermoid and endometrial cysts. All three methods had false-negative findings with borderline tumors. CONCLUSION: Transvaginal sonography is the diagnostic method of choice as a screening technique for ovarian processes. Suspicious findings on transvaginal sonography should be confirmed on MR imaging. If MR imaging confirms a dermoid or endometrial cyst, further diagnostic procedures may be unnecessary. In all other cases, a surgical evaluation must be considered.

Adolescent↗

Clinical validation of the avidin/indium-111 biotin approach for imaging infection/inflammation in orthopaedic patients.

We report here the results of a validation study of the avidin/indium-111 biotin approach in patients with skeletal lesions. This study involved 54 patients with orthopaedic conditions: 20 patients with intermediate suspected osteomyelitis of the trunk, 19 patients with infection/inflammation of prosthetic joint replacements, and 15 patients with suspected osteomyelitis of appendicular bones. Avidin (3 mg) was injected as an i.v. bolus, followed 4 h later by 111In-biotin; imaging was acquired 30 min and 16-18 h after administration of 111In-biotin. Technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO)-labelled leucocyte scintigraphy was performed in 39/54 patients. The overall sensitivity of the avidin/111In-biotin scan was 97.7% (versus 88.9% for 99mTc-HMPAO leucocyte scintigraphy). While the diagnostic performance of avidin/111In-biotin scintigraphy was similar to that of 99mTc-HMPAO leucocyte scintigraphy in patients with prosthetic joint replacements or osteomyelitis of appendicular bones, the avidin/111In-biotin approach clearly performed better than 99mTc-HMPAO leucocyte scintigraphy in patients with suspected osteomyelitis of the trunk (100% sensitivity, specificity and accuracy versus 50% sensitivity, 100% specificity and 66.7% accuracy for 99mTc-HMPAO-leucocyte scintigraphy). These results demonstrate the feasibility of the avidin/111In-biotin approach for imaging sites of infection/inflammation in the clinical setting. Although no systematic advantages of avidin/111In-biotin scintigraphy were found versus 99mTc-HMPAO leucocyte scintigraphy, the newer scintigraphic method is more practicable and involves lower biological risk for the operators.

Avidin↗