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At least 163 records · Page 9Linked to original sources
PubMed1997

Comparison of diagnostic performance and fixation control of two automated perimeters.

BACKGROUND: The Humphrey perimeter and its Statpac (analysis programs have been widely used and studied. Another statistical analysis program, FieldView, is used with the Dicon perimeter. The purpose of this study was to compare the diagnostic performance of the two perimeters and their statistical analysis packages. METHODS: Twenty-three normal subjects (age range, 27 to 83 years) and 31 patients with glaucoma or cerebrovascular disease (age range, 28 to 87 years) experienced in automated perimetry were examined using the Dicon and the Humphrey perimeters. RESULTS: The total number of significant points identified on the Humphrey total deviation probability maps was in close agreement with statistical expectations, while the Dicon total deviation probability maps yielded significantly more false-positive defects than expected for normals. Fixation loss ratios were almost twice as high with the Dicon perimeter (mean, 16%) as compared with the Humphrey perimeter (mean, 9%). The Humphrey perimeter was more reliable than the Dicon in measuring the defect depth of the physiological blind spot. CONCLUSION: The Dicon perimeter appears to yield excessive false-positive findings in normal subjects, resulting in poor sensitivity/specificity combinations, while at the same time failing to properly measure defect depth in scotomas.

Adult↗
PubMed1988

Diagnostic performance of nocturnal penile tumescence studies in healthy, dysfunctional (impotent), and depressed men.

Nocturnal penile tumescence (NPT) studies were evaluated in 17 men with a clinical diagnosis of organic erectile dysfunction in comparison to age-matched healthy controls (n = 17) and depressed men (n = 17). The dysfunctional group had significantly fewer NPT episodes and reduced maximal penile tip changes when compared to healthy controls and depressed patients. Further, the dysfunctional group had significantly diminished erectile fullness and reduced penile rigidity. Diagnostic performance of polygraphic (night 1) and visual inspection (nights 2 or 3) components of the NPT protocol were examined in these criterion groups. A diagnostic classification based on polygraphic measures successfully discriminated 73.5% of dysfunctional and healthy control subjects, but classified 47% of depressives in the dysfunctional range. Use of visual inspection indices correctly identified 88% of the dysfunctional sample and 94% of normal controls, and reduced the "false-positive" rate in depression to only 18%. Results support the diagnostic utility of NPT studies, particularly when enhanced by visual inspection procedures. Nevertheless, the presence of major depression may confound interpretation of such studies.

Circadian Rhythm↗
PubMedDate not supplied

Diagnostic performance of a teleradiology system in primary health care.

Open health care needs proper basic radiological services. Teleradiology makes it possible to get the radiologist's consultation in rural and remote areas and allows the transmission of images between hospitals. A microcomputer-based teleradiology system using a 512 x 512 x 8 bit image matrix with image-processing capabilities and obtainable at a cost of US$ 20,000 was evaluated in daily practice. Images from 372 conventional roentgen examinations were digitized and transmitted via a 64 Kbits/s telephone line from a rural health center to a university hospital, where they were interpreted by two radiologists. The original radiographs were interpreted later and the two reports compared to evaluate the diagnostic performance of system. Slight deterioration of image quality was noticed, though the images were non-diagnostic only in a few cases. The image-processing capability of the system was assessed as useful. Major discrepancies between CRT and film readings were noted in 3.9% of the cases interpreted. The accuracy of CRT readings was about 2% poorer in chest examinations and 5% poorer in bone examinations than in film readings. The teleradiology system proved sufficient for consultation in most conventional radiographs in daily practice, although a system based on a 1024 x 1024 matrix is desirable.

Bone and Bones↗
PubMed2005

Diagnostic performance and prognostic impact of FDG-PET in suspected recurrence of surgically treated non-small cell lung cancer.

PURPOSE: The differentiation of recurrent lung cancer and post-therapeutic changes remains a problem for radiological imaging, but FDG-PET allows biological characterisation of tissues by visualising glucose metabolism. We evaluated the diagnostic performance and prognostic impact of FDG-PET in cases of suspected relapse of lung cancer. METHODS: In 62 consecutive patients, 73 FDG-PET scans were performed for suspected recurrence after surgical therapy of lung cancer. FDG uptake by lesions was measured as the standardised uptake value (SUV). PET results were compared with the final diagnosis established by biopsy or imaging follow-up. SUV and clinical parameters were analysed as prognostic factors with respect to survival. RESULTS: FDG-PET correctly identified 51 of 55 relapses and gave true negative results in 16 of 18 remissions (sensitivity, specificity, accuracy: 93%, 89%, 92%). SUV in recurrent tumour was higher than in benign post-therapeutic changes (10.6+/-5.1 vs 2.1+/-0.6, p<0.001). Median survival was longer for patients with lower FDG uptake in recurrent tumour (SUV<11: 18 months, SUV > or = 11: 9 months, p<0.01). Long-term survival was observed mainly after surgical re-treatment (3-year survival rate 38%), even if no difference in median survival for surgical or non-surgical re-treatment was detected (11 vs 12 months, p=0.0627). For patients subsequently treated by surgery, lower FDG uptake predicted longer median survival (SUV<11: 46 months, SUV> or = 11: 3 months, p<0.001). SUV in recurrent tumour was identified as an independent prognostic factor (p<0.05). CONCLUSION: FDG-PET accurately detects recurrent lung cancer. SUV in recurrent tumour is an independent prognostic factor. FDG-PET helps in the selection of patients who will benefit from surgical re-treatment.

Adolescent↗
PubMed1998

Assessment of diagnostic performance of quantitative flow measurements in normal subjects and patients with angiographically documented coronary artery disease by means of nitrogen-13 ammonia and positron emission tomography.

OBJECTIVES: Regional myocardial blood flow (MBF) and flow reserve measurements using nitrogen-13 (N-13) ammonia positron emission tomography (PET) were compared with quantitative coronary angiography to determine their utility in the detection of significant coronary artery disease (CAD). BACKGROUND: Dynamic PET protocols using N-13 ammonia allow regional quantification of MBF and flow reserve. To establish the diagnostic performance of this method, the sensitivity and specificity must be known for varying decision thresholds. METHODS: MBF and flow reserve for three coronary territories were determined in 20 normal subjects and 31 patients with angiographically documented CAD by means of dynamic PET and a three-compartment model for N-13 ammonia kinetics. Ten normal subjects defined the normal mean and SD of MBF and flow reserve, and 10 normal subjects were compared with patients. PET flow obtained in the territory with the most severe stenosis in each patient was correlated with the angiographic assessment of the stenosis (severity > or = 50%, > or = 70%, > or = 90%). Receiver operating characteristic (ROC) curve analysis was performed for 1.5, 2.0, 2.5, 3.0 and 4.0 SD of flow abnormalities. RESULTS: MBF and flow reserve values from the normal subjects and from territories with documented stenoses > or = 50% were significantly different (p < 0.05). A significant difference was found between normal subjects and angiographically normal territories of patients with CAD. High diagnostic accuracy and sensitivity, with moderately high specificity, were demonstrated for detection of all stenoses. CONCLUSIONS: Quantification of myocardial perfusion using dynamic PET and N-13 ammonia provides a high performance level for the detection and localization of CAD. The specificity of dynamic PET was excellent in patients with a low likelihood of CAD, whereas an abnormal flow reserve in angiographically normal territories was postulated to represent early functional abnormalities of vascular reactivity.

Adult↗
PubMedDate not supplied

[Comparison of the diagnostic performance of students of the old and new medical curriculum at the Laval University].

In the Fall of 1982, the "Université Laval" School of Medicine inaugurated a new undergraduate curriculum consisting primarily in the introduction of problem-based learning to foster the development of clinical reasoning. The purpose of the study was to compare the diagnostic performance of the students of the old (n = 118) and the new (n = 120) program. The measurement instrument consisted of 12 short clinical vignettes. There is no significant difference in the performance of the students from the two programs. In spite of these results, it is advocated to wait before initiating yet another curriculum reform or reversal. Finally and for both classes of students, their performance varied significantly from hospital to hospital. A number of suggestions are made to better standardize the quality of clinical teaching across the different hospital settings.

Canada↗
PubMed1998

Diagnostic performance of QT interval variables from 24-h electrocardiography in the long QT syndrome.

AIMS: The long QT syndrome is mainly defined by QT interval prolongation (QTc > 0.44s). However, data obtained in genotyped patients showed that resting QTc measurement alone may be inaccurate for ascertaining the phenotype. The aim of this study was to evaluate the diagnostic performance of QT interval rate-dependence in untreated chromosome 11-linked patients. METHODS: The study population consisted of 25 untreated long QT patients linked to chromosome 11 and 25 age- and gender-matched controls. QTc intervals were measured on 12-lead resting ECG recordings. From 24-h Holter recordings, the slope of the relationship between ventricular repolarization and heart rate was studied separately day and night to assess neural modulation. Mean heart rates and rate-dependences of QT and Q-maximum of T (QTm) intervals were compared between long QT patients and controls for both time periods. RESULTS: In both groups, the rate-dependences were modulated by day-night influences. When compared to controls, long QT patients showed a significant increase at night in QT/RR slopes (0.158 +/- 0.05 vs 0.117 +/- 0.03, P = 0.002) and QTm/RR slopes (0.163 +/- 0.05 vs 0.116 +/- 0.04, P = 0.0006). Multivariate analysis, adjusting QTc interval on age and gender, discriminated between long QT patients and controls with a 76% sensitivity and a 84% specificity. A 96% sensitivity and a 96% specificity were reached by taking into account the QTm/RR slope at night, the QTc interval and the mean heart rate during the day. CONCLUSION: QT interval variables obtained from 24-h ECG recordings improve long QT syndrome diagnosis by showing an increased nocturnal ventricular repolarization rate-dependence in genotyped chromosome 11-linked patients.

Adolescent↗
PubMed2005

Diagnostic performance of quantitative kappa and lambda free light chain assays in clinical practice.

BACKGROUND: The quantitative assay for free light chains (FLCs) is a recently introduced commercial test reported to be sensitive and specific for detecting FLC diseases such as primary systemic amyloidosis (AL), light chain deposition disease (LCDD), nonsecretory multiple myeloma (NSMM), and light chain multiple myeloma. We evaluated its diagnostic performance in clinical practice. METHODS: All FLC clinical test results generated in 2003 were abstracted from the Laboratory Information System. Diagnoses were obtained from the Dysproteinemia database and the patient medical history. RESULTS: In 2003, we received samples for FLC assays from 1020 Mayo Clinic patients. The majority of these patients (88%) had bone marrow-derived monoclonal plasma cell disorders (PCDs). The 121 patients who did not have monoclonal gammopathy all had FLC kappa/lambda ratios within the range of values obtained for a reference population in our laboratory. Among the patients with monoclonal gammopathies were patients with multiple myeloma (330), AL (269), monoclonal gammopathy of undetermined significance (114), smoldering multiple myeloma (72), plasmacytoma (22), NSMM (20), macroglobulinemia (9), LCDD (7), and a variety of other PCDs. Among the 110 AL patients who had not been previously treated and who had a FLC assay performed within 120 days of diagnosis, the FLC kappa/lambda ratio was positive in 91% compared with 69% for serum immunofixation electrophoresis (IFE) and 83% for urine IFE. The combination of serum IFE and serum FLC assay detected an abnormal result in 99% (109 of 110) of patients with AL. CONCLUSION: The performance of the FLC assay in this analysis of clinical laboratory data is consistent with results from published retrospective validation studies.

Amyloidosis↗
PubMed1989

Improved diagnostic performance of exercise thallium-201 single photon emission computed tomography over planar imaging in the diagnosis of coronary artery disease: a receiver operating characteristic analysis.

Qualitative interpretation of tomographic and planar scintigrams, a five point rating scale and receiver operating characteristic analysis were utilized to compare single photon emission computed tomography and conventional planar imaging of myocardial thallium-201 uptake in the accuracy of the diagnosis of coronary artery disease and individual vessel involvement. One hundred twelve patients undergoing cardiac catheterization and 23 normal volunteers performed symptom-limited treadmill exercise, followed by stress and redistribution imaging by both tomographic and planar techniques, with the order determined randomly. Paired receiver operating characteristic curves revealed that single photon emission computed tomography was more accurate than planar imaging over the entire range of decision thresholds for the overall detection and exclusion of coronary artery disease and involvement of the left anterior descending and left circumflex coronary arteries. Tomography offered relatively greater advantages in male patients and in patients with milder forms of coronary artery disease, who had no prior myocardial infarction, only single vessel involvement or no lesion greater than or equal to 50 to 69%. Tomography did not appear to provide improved diagnosis in women or in detection of disease in the right coronary artery. Although overall detection of coronary artery disease was not improved in patients with prior myocardial infarction, tomography provided improved identification of normal and abnormal vascular regions, particularly of the left anterior descending and circumflex artery regions. These results indicate that single photon emission computed tomography provides improved diagnostic performance compared with planar imaging in many clinical subgroups, and suggest that it represents the diagnostic imaging procedure of choice in exercise thallium-201 perfusion studies.

Adrenergic beta-Antagonists↗
PubMedDate not supplied

[Diagnostic performance of mammography in patients with clinically impercetible tumors. Analysis of 1005 tumors].

UNLABELLED: Breast cancer is an important public health problem. Early diagnosis is the only method of efficient secondary prevention in the control of the illness as it permits rapid and effective treatment. The objective of this study was to carry out a methodical analysis that would enable us to increase the diagnostic performance of the mammogram and to diminish the number of unnecessary surgical biopsies. MM: We selected impalpable mammary tumors in patients with radiological suspicion of breast cancer, on which surgical biopsy by harpoon had been practiced in the Lozano Blesa Hospital, Zaragoza, between October 1991 and January 2005. RESULTS: We analyzed a total of 1005 tumors in 965 patients, with an average age of 57 years. In our series of 1005 tumors, 40% were PVV. CONCLUSIONS: The diagnosis of radiological suspicion and the indication for biopsy or mammographic control are subjective and personal appreciations, but based on the systematic analysis of radiological signs of incipient tumors. This analysis enables us to establish a cut-off point to include the tumors in BIRADS.

Adult↗
PubMed2004

Diagnostic performance of quantitative ultrasound calcaneus measurement in case finding for osteoporosis in Thai postmenopausal women.

AIM: Dual-energy X-ray absorptiometry (DXA) is currently considered the gold standard for the diagnosis of osteoporosis. Quantitative ultrasound (QUS) can be an alternative method that is less expensive, portable, and can be used at a primary care level to indicate osteoporosis in women. The present study aimed to assess the diagnostic performance of QUS calcaneus measurement in a case finding for osteoporosis in Thai postmenopausal women using DXA as a gold standard. METHODS: Three hundred postmenopausal women, who had not menstruated normally for at least 1 year, were included in the study. To determine the accuracy and reliability of QUS of the calcaneus, calcaneus bone density measurement was carried out using the QUS and left femoral neck bone density was measured using DXA. Bone mass density (BMD) was interpreted as osteoporotic or normal using WHO criteria for determining the performance of QUS. Optimal cut-off values were determined using a receiver operating characteristic (ROC) curve for diagnosing the osteoporosis cases. RESULTS: The number of osteoporosis cases in this study was 107 (35.67%). The sensitivity, specificity, positive and negative predictive values were 39.25%, 91.71%, 72.41%, 73.14%, respectively, when using the T-score of the WHO criteria as a reference. The positive and negative likelihood ratios were 4.73 and 0.66. When using the ROC curve to determine the optimal cut-off values, using the stiffness index of the QUS and categorizing age (<65 years and >or=65 years) before conducting the test, sensitivity and specificity were 77.6% and 59.6%, respectively. CONCLUSIONS: Bone mass density measurement for predicting osteoporosis using QUS had a very low sensitivity and was not good enough to replace the standard tool (DXA).

Absorptiometry, Photon↗
PubMed1983

Comparative diagnostic performance of the Telemed computer ECG program.

One thousand consecutive ECG's from an ambulatory population of patients with suspected or proven cardiac disease were evaluated using two versions of the Telemed computerized ECG system. Only minor differences were found between the two programs. In version 6 vs. version 5, 87% vs. 90% of 287 normal ECG's were correctly classified and 93% vs. 96% of abnormal ECG's were correctly classified; the percent of acceptable diagnostic agreement was 86.2% and 87.4% respectively (NS). The sensitivity for arrhythmia detection, transmural inferior infarction and ST-T wave abnormalities was slightly greater in version 6. The increased sensitivity was not accompanied by decreased specificity. The sensitivity for left ventricular hypertrophy decreased from 95.2% to 91.4% in version 6 with a slight increase in specificity (95.2% to 97.0%). In conclusion, criteria changes in the most recent version of the Telemed program have not resulted in a major change in diagnostic performance. Arrhythmia detection is slightly but not significantly improved.

Adolescent↗
PubMed1999

The IgG1/G2 subclass shift--a sensitive, tissue non-specific marker for malignancy. Diagnostic performance with squamous cell carcinoma of the head and neck.

A significant decrease in %IgG1 accompanied by an increase in %IgG2 in total serum IgG has been previously reported as a highly sensitive marker for detecting early stages of carcinomas of various localizations. Here we investigated the question as to whether this phenomenon is also observed in sera of patients with squamous cell carcinoma of the head-neck region (SCC-HN), and to evaluate its diagnostic performance in the post-operative monitoring. Using quantitative affinity chromatography, serum concentrations of IgG1, IgG2 and total IgG were determined in 81 patients with different stages of primary and untreated SCC-HN, in 51 SCC-HN patients in post-therapeutical follow up, and in 33 patients with organ matched benign diseases. The data were compared with a total of 174 healthy controls. It was found that (i) 105 SCC-HN patients exhibited a mean value of 56.0 +/- 0.7% IgG1, which likewise differed from healthy controls (63.2 +/- 0.5) and benign diseases (61.5 +/- 1.0) with P < 0.0005, (ii) sensitivities and specificities for discriminating primary malignancies from healthy controls were 70 and 74% respectively, and from benign diseases 65 and 76%, (iii) highest sensitivities and specificities were observed with post-therapeutic cases suffering from tumour recurrence (88% and 75%) or patients with distant metastases (87% and 86%), (iv) apparently tumour-free post-therapeutic patients showed a mean %IgG1 not different from the normal value. The decrease in %IgG1 accompanied by increased %IgG2 is an efficient, sensitive and early marker of SCC-HN, which appears particularly useful for the post-therapeutic monitoring.

Aged↗
PubMed2003

[Computerised monitoring of integrated cervical screening. Indicators of diagnostic performance].

In a previous issue of this journal, we presented the background, rationale, general methods, and indicators of participation of a computerised system for the monitoring of integrated cervical screening, i.e. the integration of spontaneous Pap smear practice into organised screening. We also reported the results of the application of those indicators in the general database of the Pathology Department of Imola Health District in northern Italy. In the current paper, we present the rationale and definitions of indicators of diagnostic performance (total Pap smears and rate of unsatisfactory Pap smears, distribution by cytology class reported, rate of patients without timely follow-up, detection rate, positive predictive value, distribution of cytology classes reported by histology diagnosis, and distribution of cases of CIN and carcinoma registered by detection modality) as well as the results of their application in the same database as above.

Adolescent↗
PubMedDate not supplied

The role of clinical "experience" in diagnostic performance.

Twenty-one physicians examined records of 43 patients who had attended the hospital because of chest pain. Of these patients, 20 had had coronary heart disease (CHD), 15 had had nonspecific pain, and eight had had pulmonary embolism. The physicians indicated the probability of CHD in each case on the basis of 18 clinical findings, not including ECG, x-ray, or biochemical studies. The trial was repeated five years later, using the same records, by 16 of the same physicians. Diagnostic accuracy was evaluated by ROC curves, and the weight ascribed to each cue was inferred by multiple regression with estimated probability of CHD as the dependent variable. No significant change of areas under the ROC curves with increasing length of clinical experience was observed. Multiple regression was significant in 30 of 37 analyses. The distributions of most physicians' estimates of probabilities had similar shapes five years apart. It is concluded that "experience" does not have a clear role in diagnostic performance based on recorded data and that personal calibration and preferences in estimating probabilities often persist for years.

Adult↗
PubMed2005

Diagnostic performance of nanoparticle-enhanced magnetic resonance imaging in the diagnosis of lymph node metastases in patients with endometrial and cervical cancer.

PURPOSE: Lymph node metastases affect management and prognosis of patients with gynecologic malignancies. Preoperative nodal assessment with computed tomography or magnetic resonance imaging (MRI) is inaccurate. A new lymph node-specific contrast agent, ferumoxtran-10, composed of ultrasmall particles of iron oxide (USPIO), may enhance the detection of lymph node metastases independent of node size. Our aim was to compare the diagnostic performance of MRI with USPIO against standard size criteria. METHODS: Forty-four patients with endometrial (n = 15) or cervical (n = 29) cancer were included. MRI was performed before and after administration of USPIO. Two independent observers viewed the MR images before lymph node sampling. Lymph node metastases were predicted using size criteria and USPIO criteria. Lymph node sampling was performed in all patients. RESULTS: Lymph node sampling provided 768 pelvic or para-aortic nodes for pathology, of which 335 were correlated on MRI; 17 malignant nodes were found in 11 of 44 patients (25%). On a node-by-node basis, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) by size criteria were 29%*, 99%, 56%, and 96%, and by USPIO criteria (reader 1/reader 2) were 93%/82%* (*P = .008/.004), 97%/97%, 61%/59%, and 100%/99%, respectively (where [*] indicates the statistical difference of P = x/x between the two results marked by the asterisk). On a patient-by-patient basis, sensitivity, specificity, PPV, and NPV by size criteria were 27%*, 94%, 60%, and 79%, and by USPIO criteria (reader 1/reader 2) were 100%/91%* (*P = .031/.06), 94%/87%, 82%/71%, and 100%/96%, respectively. The kappa statistic was 0.93. CONCLUSION: Lymph node characterization with USPIO increases the sensitivity of MRI in the prediction of lymph node metastases, with no loss of specificity. This may greatly improve preoperative treatment planning.

Adult↗
PubMed1999

Occult lumbosacral dysraphism in children and young adults: diagnostic performance of fast screening and conventional MR imaging.

PURPOSE: To compare fast screening and conventional magnetic resonance (MR) imaging for the detection of occult dysraphic myelodysplasias in children and young adults. MATERIALS AND METHODS: A retrospective case-control study included 101 patients (mean age, 4.9 years; range, 1 day to 26 years) suspected of having occult lumbosacral dysraphism. Sixty case patients had myelodysplastic lesions (19 filar lipoma, 14 syringomyelia, 10 intradural lipoma, eight dermal sinus, five diastematomyelia, five lipomyelomeningocele, two caudal regression syndrome); 41 control patients had no dysraphic lesions; 17 patients had associated renal anomalies. Two neuroradiologists reviewed MR images from conventional and fast screening protocols. Diagnostic performance parameters included sensitivity, specificity, and area under the receiver operating characteristic curve (Az value). RESULTS: The sensitivity of conventional and fast screening MR studies was 97.1% and 98.5%, respectively, the specificity was 90.9% and 84.8%, respectively. The Az value was 0.973 for the fast screening and 0.976 for the conventional MR studies (P = .83). Interobserver agreement was very good for fast screening images (kappa = 0.68) and excellent for conventional images (kappa = 0.75). For renal anomalies, the Az value was 0.786 and 0.853 for fast screening and conventional MR imaging, respectively (P = .28). CONCLUSION: Conventional three-plane lumbosacral MR imaging in children and young adults suspected of having occult dysraphism provides better diagnostic information than does fast screening two-plane MR imaging because of its higher specificity and interobserver agreement.

Adolescent↗
PubMed1994

A temporal analysis of QMR: abstracted temporal representation and reasoning and initial assessment of diagnostic performance trade-offs.

Explicit temporal representation and reasoning (TRR) in medical decision-support systems (MDSS) is generally considered to be a useful but often neglected aspect of system design and implementation. Given the great burden of explicit TRR both in knowledge acquisition and computational efficiency, developers of general-purpose large-scale systems typically utilize implicit (i.e., abstracted) forms of TRR. We are interested in understanding better the trade-offs of not incorporating explicit TRR in large general-purpose MDSS along the dimensions of system expressive power and diagnostic accuracy. In particular, we examine the types of abstracted TRR employed in QMR, a diagnostic system in the domain of general internal medicine, and the high-level effects of such an implicit treatment of time in the system's diagnostic performance. We present our findings and discuss implications for MDSS design and implementation practices.

Artificial Intelligence↗