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PubMed2026

Malaria rapid diagnostic tests: performance, pitfalls, and progress.

PURPOSE OF REVIEW: Malaria rapid diagnostic tests (RDTs) have revolutionized malaria diagnosis in endemic settings. RDTs are simple to use and accurate for clinical cases, although sensitivity is reduced at parasite densities below 200 parasites/μl. However, increasing prevalence of hrp2/3 gene deletions in certain areas threaten utility of histidine-rich protein 2 (HRP2)-based RDTs, and lingering HRP2 antigenemia can generate false-positive results after parasite clearance. This review summarizes current performance of malaria RDTs, threats to their validity, and recent innovations to improve their performance and continued role in malaria diagnosis. RECENT FINDINGS: Most World Health Organization (WHO) prequalified RDTs perform well for clinical diagnosis, with only occasional exceptions, including a recently reported issue affecting several countries. RDT sensitivity is generally related to malaria transmission intensity, with higher proportions of false-negative results in lower-transmission areas. Newly prequalified lactate dehydrogenase (pLDH)-based RDTs perform well for both Plasmodium falciparum in areas with >5% hrp2/3 gene deletions and for Plasmodium vivax diagnosis. Several point-of-care alternatives to RDTs, including micro-fluidic devices, hemozoin-detecting devices, and automated hematology analyzers, have shown promising results in small studies, but require larger-scale trials before widespread use. SUMMARY: RDTs remain a critical tool in clinical diagnosis of malaria, and newer pLDH-based tests perform well in areas where hrp2/3 gene deletions threaten validity of HRP2-based RDTs.

Humans↗
PubMedDate not supplied

The radial artery: an alternative access site for diagnostic and interventional coronary procedures.

BACKGROUND: Percutaneous techniques are routinely used in the diagnosis and treatment of cardiovascular disease. The transfemoral route is the most frequently used arterial access site for performing these procedures AIM: To describe a technique to gain arterial access via the radial artery to perform diagnostic and invasive procedures. METHODS: Patient selection is key to establishing a successful transradial service. RESULTS: There is a significant vascular complication rate when using the transfemoral route. Transfemoral access can also be difficult in patients with peripheral vascular disease. Arterial access via the right radial artery represents a realistic alternative to the transfemoral route for performing diagnostic and therapeutic coronary procedures. CONCLUSIONS: The radial artery offers a safe and effective alternative access site for performing diagnostic and interventional coronary procedures. The need for alternatives to femoral artery access is critical in patients with severe peripheral vascular disease. The establishment and ongoing provision of radial artery intervention allows for a significant reduction in major vascular complication rates, earlier patient ambulation, increased patient comfort and the potential to establish day case coronary intervention.

Angioplasty, Balloon, Coronary↗
PubMed1998

Comparison of 3 investigational assays for the free form of prostate specific antigen.

PURPOSE: Measuring percent free/total prostate specific antigen (PSA) versus total PSA alone has been shown to enhance the stratification of cases with and without prostate cancer. We compared the diagnostic performance of 3 free PSA assays when values were interchanged over a common total PSA denominator. MATERIALS AND METHODS: Archival sera from 123 consecutively accrued patients (25 with prostate cancer, 98 with no evidence of malignancy) who had pre-biopsy total PSA levels from 2.0 to 20.0 ng./ml. were obtained from our specimen bank. Serum specimens were analyzed using the Hybritech Tandem R, Dianon Systems and Chiron ACS 180 free PSA assays. Total PSA was measured using the Hybritech Tandem R total PSA assay. Linear regression was performed to evaluate the correlation and agreement among assays. Sensitivity and specificity of cancer detection were calculated to compare diagnostic performance. RESULTS: The required percent free PSA cutoffs were different among the 3 free PSA assays. The cutoffs to ensure a 95% sensitivity of cancer detection were 22, 34 and 34%, and the number of negative biopsies that were prevented at these cutoffs (specificity) was 38, 19 and 33% for the Hybritech, Dianon, and Chiron assays, respectively. CONCLUSIONS: The results among the different assays were not interchangeable. Clinicians should be aware that different percent free PSA cutoffs need to be used based on the type of free and total PSA assays, and that not all assays diagnostically perform the same.

Aged↗
PubMedDate not supplied

Image quality in radiography of midfacial trauma.

Image quality in radiography of midfacial trauma was studied in 618 patients treated for midfacial injury. The visibility of key anatomic areas was related to essential technical factors influencing image quality as well as to the radiologic diagnostic performance. Regression analysis revealed that the visibility of the key anatomic areas was significantly dependent on the technical factors. However, the radiologic diagnostic performance was not significantly dependent on the visibility of the key anatomic areas. The results indicate that image quality was not a limiting factor for radiologic diagnostic performance in midfacial trauma.

Facial Bones↗
PubMed2001

Comparison of image reconstruction algorithms in myocardial perfusion scintigraphy.

The purpose of this study was to compare the clinical utility of two image reconstruction algorithms in myocardial perfusion SPECT (single-photon emission computed tomography): filtered back-projection (FBP) and ordered subset expectation maximization (OSEM). A rest/stress one-day protocol with 99mTc-MIBI or tetrofosmin was performed on 102 consecutive patients who underwent coronary angiography. After SPECT data acquisition, images were reconstructed with FBP and OSEM algorithms. We assessed diagnostic performance (sensitivity, specificity and accuracy) in detecting coronary artery stenosis and evaluated regional tracer uptake with a 4-point scoring system. Although there were no significant differences in diagnostic performance between FBP and OSEM reconstruction, the OSEM method yielded higher uptake in the RCA area than the FBP method by reducing the count-loss artifact due to hepatic uptake of the tracers. In addition, regional uptake in the LCX area was significantly lower in the OSEM image than in the FBP image; this phenomenon was observed mainly in patients with coronary stenosis and/or infarction in the LCX territory. In conclusion, OSEM and FBP offered comparable diagnostic performance in stress myocardial perfusion SPECT. The OSEM method contributed to reduction of the count-loss artifact in inferior and posterior walls and to easy recognition of hypoperfusion in the LCX area.

Algorithms↗
PubMed1998

Percent free prostate-specific antigen in assessing the probability of prostate cancer under optimal analytical conditions.

Although general consensus exists that percent free prostate-specific antigen (PSA) is superior to total immunoreactive PSA for prostate cancer (CaP) detection, its diagnostic performance is not yet well established. Analytical problems may account for difficulties in evaluating percent free PSA because the free PSA concentration is substantially lower than that of total PSA. The aim of the present study was to establish the diagnostic performances of the IMMULITE percent free PSA assay from Diagnostics Products Corp. under experimental conditions optimized to minimize analytical variability. Eighty-five patients with untreated primary CaP and 261 with untreated benign prostate hypertrophy (BPH) were prospectively enrolled. The Diagnostics Products IMMULITE total (Third Generation) and free PSA were measured by the same technician, using the same instrument and the same reagent batch. We calculated the post-test probability to express how the likelihood of the diagnosis of CaP changed after the percent free PSA was determined. Areas under the ROC curves of percent free PSA were better than those of total PSA in every evaluated range of total PSA. The percent free PSA could have reduced the rate of unnecessary biopsies by 47% in patients with total PSA >/=4 microg/L with only 3.8% false-negative results. The post-test probability of percent free PSA was, however, <50% in men 50-70 years of age, using cutoff points providing sensitivity from 99% to 80%. Percent free PSA is superior to total PSA in distinguishing primary CaP from BPH in patients with total PSA between 2 and 30 microg/L. In men with low total PSA, the diagnostic performance of the percent free PSA assay may be optimized by controlling methodological variability. The percent free PSA assay is effective in reducing the rate of unnecessary biopsies in men with total PSA >4 microg/L. However, the post-test probability provided by percent free PSA is relatively low in asymptomatic patients 50-70 years of age.

Aged↗
PubMed1999

Can self-reported encoding strategy and recognition skill be diagnostic of performance in eyewitness identifications?

The relationship between 3 witness factors and identification accuracy, as well as calibration and diagnosticity of confidence, was investigated. A total of 384 participants in an eyewitness experiment rated their facial recognition skill, general memory skill, and self-reported encoding strategy on a questionnaire presented after the photo-confrontation. Participants who rated themselves to be good face recognizers showed a slightly higher overall accuracy with a more diagnostic confidence-accuracy relation. Participants who reported that they relied on a holistic encoding strategy were associated with more accurate identifications and a stronger confidence-accuracy relation than those who reported an analytic encoding strategy. Degree of self-reported general memory skill was not diagnostic of identification performance.

Adult↗
PubMed1996

Effects of dose reduction on digital chest imaging using a selenium detector: a study of detecting simulated diffuse interstitial pulmonary disease.

OBJECTIVE: The purpose of this study was to evaluate the effect of dose reduction on the diagnostic performance of a new digital chest imaging system in which amorphous selenium is used as the X-ray detector. Diagnostic performance was assessed for the detection of simulated diffuse interstitial pulmonary disease (DIPD). MATERIALS AND METHODS: DIPD was simulated by superimposing plastic sheets that contained small radiopaque objects (birdseed) on an anthropomorphic chest phantom. We varied the number of sheets from zero to four to simulate the degree of abnormality. We made 80 images with a standard X-ray dose, 80 images with 55% of the standard dose, and 80 images with 35% of the standard dose. Six observers were asked to indicate the presence of DIPD using a five-level scale of confidence. Two hundred forty chest images were then analyzed using receiver operating characteristic (ROC) curves. RESULTS: The area under the ROC curve was 87.2 for all readers with standard-dose imaging (95% confidence interval [CI], 83.7-90.7), 91.7 with 55% of the standard dose (95% CI, 88.8-94.6), and 90.0 with the 35% dose (95% CI, 87.1-92.9). The area under the ROC curve for subtle DIPD (one superimposed sheet) was 75.3 for all readers with standard-dose imaging (95% CI, 67.1-83.5), 79.7 with 55% of the standard dose (95% CI, 71.9-87.5), and 70.3 with the 35% dose (95% CI, 61.7-78.9). For each dose, we observed a gradual improvement of the ROC curves with each additional sheet superimposed on the chest phantom (p < .001). CONCLUSION: We found no significant difference in diagnostic performance among images made with standard X-ray dose, those made with a 55% dose, and those made with a 35% dose (95% CI).

Humans↗
PubMed2001

[Role of PSA velocity in the detection of prostate cancer. A study of 986 males].

OBJECTIVE: To analyze the role of PSA velocity (PSAV) in the detection of prostate cancer (Pca) when compared to other valid alternatives. PATIENTS AND METHODS: From a Pca screening program, 986 men were evaluated in two visits (601 of them agreed for a third visit). Serum PSA was performed in every visit (PSA1, PSA2 and PSA3). All Pca diagnosed after PSA1 were excluded. Criteria for biopsy (PSA2 and PSA3) were PSA > 4 ng/ml, or PSAV > 0.7 ng/ml/year. Diagnostic performance of PSAV was compared with other options (PSA alone, DRE, and PSA density -PSAD-). RESULTS: Median age was 57 years. Median interval between visits were 679 days and 852.5 days respectively. During PSA2, 122 biopsies were indicated (91 performed). After PSA3, 78 were indicated and 24 done. This great proportion of not biopsied men was due to refusal. Seven Pca were detected during PSA2, and 5 during PSA3. Sensitivity of PSAV (two draws) was 0.86, specificity 0.95, missed 1 cancer of 7 and needed 7.5 biopsies per cancer. When three PSA samples available, PSAV missed 2 cancers of 5, and 2.7 biopsies per cancer needed. PSA alone detected 86% of the cancers, multiplying by 2 the number of biopsies needed. Not DRE, nor PSAD improved the diagnostic performance of PSAV when combined with this parameter. CONCLUSIONS: Diagnostic performance of PSAV was found to be unacceptable in our hands. The need for a third biopsy in these studies make them difficult to reproduce. Validation of PSAV is a difficult task to achieve, we think its role remains questioned.

Aged↗
PubMed1999

Diagnosis of urogenital Chlamydia trachomatis infection by use of DNA amplification.

Numerous studies on DNA amplification and diagnosis of C. trachomatis infections have been performed since the first PCR for detection of C. trachomatis in clinical samples was described in 1990, but optimal sample preparation procedures are still lacking. The major problem in evaluating the diagnostic performance of the DNA amplification methods is that there is no clinical or microbiological reference standard for C. trachomatis infection. The evaluated diagnostic performance will therefore always be a reflection of of the chosen comparator(s). Despite this, it seems that the DNA amplification methods are more sensitive than the cell culture techniques and the techniques based on immunology. Compared with the tests based on immunology the specificity is also improved, which makes the DNA amplification methods useful for sample types contaminated with organisms cross-reacting in the immunologically based methods, i.e. pharyngeal and rectal swab samples. However, the specificity and thereby the predictive value of a positive test is not optimal. Since the predictive value of a positive test is highly influenced by the prevalence in the tested population, evaluation of applied tests is constantly needed, especially since the prevalence may be expected to decrease with intensified test activity and due to changes in safe sex practices after the advent of AIDS. The improved sensitivity of the DNA amplification methods allows the use of sample material in which the content of Chlamydia organisms is lower than in conventional swab samples, i.e. urine, semen, and vaginal secretions can be used as sample material. these samples can be obtained by the individuals themselves, and since transport conditions seem less critical for the test performance, samples can also be taken in the privacy of the home and subsequently mailed by the individual directly to the diagnostic laboratory. Such strategy for testing has led to improved partner tracing and universal screening, compared with traditional swab examinations at physicians' offices. Tests with an optimal diagnostic performance have not yet been reached, and several sample categories have not been studied sufficiently. The societal implications of the use of self-collected samples and universal screening have not been studied in full, but a milestone for new strategies in detection and preventing urogenital C. trachomatis epidemics has been reached with the availability of DNA amplification techniques.

Chlamydia Infections↗
PubMed1988

Multiple reading procedures: the performance of diagnostic tests.

This paper examines the effects on sensitivity and specificity of various multiple reading procedures. Multiple reading procedures entail the performance of a diagnostic test several times and consequent assignment of the subject to an 'affected' or 'unaffected' group. A Unanimity rule (that is, all tests must be positive) leads to the largest predictive value positive, but may have unacceptably low sensitivity. The rule which classifies the subject as positive based on the majority of the tests increases both the sensitivity and specificity of the individual test. Variability of subjects' sensitivity and specificity (that is, case of correct diagnosis on a test) affects the performance of these rules. We also study alternative procedures in which the final test is a better, but more expensive, test.

Diagnostic Techniques and Procedures↗
PubMed1994

Craniosynostosis: diagnostic imaging with three-dimensional CT presentation.

PURPOSE: To measure diagnostic performance and preference of two three-dimensional CT reconstruction modalities (voxel-gradient and surface-projection) displayed two ways (conventional and unwrapped) in craniosynostosis confirmed by surgical inspection and histologic analysis of resected sutures. METHODS: High-resolution 2-mm contiguous CT sections were obtained and three-dimensional reconstruction images generated for 25 infants and children with skull deformities before surgical treatment of craniosynostosis. Two pediatric radiologists and two neuroradiologists first ranked images by their own preferences for diagnostic use. Then they diagnosed craniosynostosis from images presented in random order and blinded. The standard of reference was inspection during surgery and histologic evaluation of excised sutures. Finally, reviewers repeated their subjective preference tests. RESULTS: The least experienced radiologist had 100% sensitivity for all imaging modalities and specificities ranging from 43% to 83%. The two most experienced radiologists performed nearly identically, with sensitivities of 96% and specificities of 100%. After performing diagnostic tasks using all image types, all radiologists preferred conventional surface projections. CONCLUSION: Experienced readers can achieve nearly perfect diagnostic performance using the latest three-dimensional CT reconstruction images, making it a contribution to the diagnostic process. Although performance is nearly identical for all modalities, readers strongly prefer conventionally presented surface-projection images.

Algorithms↗
PubMed2006

Usefulness of artificial neural network for differential diagnosis of hepatic masses on CT images.

RATIONALE AND OBJECTIVE: Our purpose in this study is to apply an artificial neural network (ANN) for differential diagnosis of certain hepatic masses on computed tomographic (CT) images and evaluate the effect of ANN output on radiologist diagnostic performance. MATERIALS AND METHODS: We collected 120 cases of hepatic disease. We used a single three-layer feed-forward ANN with a back-propagation algorithm. The ANN is designed to differentiate four hepatic masses (hepatocellular carcinoma, intrahepatic peripheral cholangiocarcinoma, hemangioma, and metastasis) by using nine clinical parameters and 24 radiological findings in dual-phase contrast-enhanced CT images. Thus, the ANN consisted of 33 input units and four output units. Subjective ratings for the 24 radiological findings were provided independently by two attending radiologists. All clinical cases were used for training and testing of the ANN by implementation of a round-robin technique. In the observer test, CT images of all 120 cases (30 cases for each disease) were used. CT images were viewed by seven radiologists first without and then with ANN output. Radiologist performance was evaluated by using receiver operating characteristic (ROC) analysis on a continuous rating scale. RESULTS: Averaged area under the ROC curve for ANN alone was 0.961. The diagnostic performance of seven radiologists increased from 0.888 to 0.934 (P < .02) when they used ANN output. CONCLUSION: The ANN can provide useful output as a second opinion to improve radiologist diagnostic performance in the differential diagnosis of hepatic masses seen on contrast-enhanced CT.

Aged, 80 and over↗
PubMed1989

Safety and efficacy of percutaneous transluminal coronary angioplasty performed at time of diagnostic catheterization compared with that performed at other times.

Performing diagnostic cardiac catheterization and percutaneous transluminal coronary angioplasty (PTCA) as a single, combined procedure might provide savings in patient hospitalization days and more efficient use of catheterization laboratory time. To assess the safety and efficacy of combined diagnostic coronary angiography and PTCA, we reviewed all elective PTCA procedures performed at our institution during 1985 and 1986 so that we could compare patients who had diagnostic angiography and angioplasty on separate days (n = 404) with those who had the combined procedure (n = 120). The success rate and incidences of urgent bypass surgery, acute myocardial infarction, transient azotemia and procedure-related death were not different in the 2 groups. The mean hospitalization time was 6.2 days in the group with combined angiography and angioplasty, and 7.3 days in the group having separate procedures.

Angiography↗
PubMed2004

Ability of foot radiographs to predict rheumatoid arthritis in patients with early arthritis.

OBJECTIVE: In a cohort of patients with early arthritis, to evaluate how well foot radiographs at study inclusion predicted a diagnosis of rheumatoid arthritis (RA) 2 years later. METHODS: A cohort of patients with arthritis of less than one year duration was evaluated in a multicenter study and followed for 30 +/- 11 months. An observer blinded to patient data read all 149 hand and foot radiographs done at study inclusion, using item 7 of the 1987 American College of Rheumatology (ACR) criteria for RA and Sharp's method to score erosions and joint space narrowing. RESULTS: The kappa coefficient for the 1987 ACR item 7 was 0.52 for bony decalcification and 0.87 for erosions. Intra and interobserver correlation coefficients for Sharp's scores ranged from 0.90 to 0.98. Erosions at the feet were significantly associated with RA. The item 7 erosion component at the feet was more specific than the full item 7 (97.5% vs 94%; p = 0.01). Sharp's erosion score at the feet was not better than the erosion component of item 7 (sensitivity 18%; specificity 97.5%). Combined use of radiographs of the hands and feet improved the diagnostic performance of the item 7 erosion component; (sensitivity and specificity of item 7 erosions at the hands combined with the feet were 32.5% and 94.5%, respectively). CONCLUSION: The "erosion" criterion at the feet had the best diagnostic performance and was significantly associated with a diagnosis of RA. Combining hand and foot radiographs improved diagnostic performance.

Adult↗
PubMed1999

Empirical evidence of design-related bias in studies of diagnostic tests.

CONTEXT: The literature contains a large number of potential biases in the evaluation of diagnostic tests. Strict application of appropriate methodological criteria would invalidate the clinical application of most study results. OBJECTIVE: To empirically determine the quantitative effect of study design shortcomings on estimates of diagnostic accuracy. DESIGN AND SETTING: Observational study of the methodological features of 184 original studies evaluating 218 diagnostic tests. Meta-analyses on diagnostic tests were identified through a systematic search of the literature using MEDLINE, EMBASE, and DARE databases and the Cochrane Library (1996-1997). Associations between study characteristics and estimates of diagnostic accuracy were evaluated with a regression model. MAIN OUTCOME MEASURES: Relative diagnostic odds ratio (RDOR), which compared the diagnostic odds ratios of studies of a given test that lacked a particular methodological feature with those without the corresponding shortcomings in design. RESULTS: Fifteen (6.8%) of 218 evaluations met all 8 criteria; 64 (30%) met 6 or more. Studies evaluating tests in a diseased population and a separate control group overestimated the diagnostic performance compared with studies that used a clinical population (RDOR, 3.0; 95% confidence interval [CI], 2.0-4.5). Studies in which different reference tests were used for positive and negative results of the test under study overestimated the diagnostic performance compared with studies using a single reference test for all patients (RDOR, 2.2; 95% CI, 1.5-3.3). Diagnostic performance was also overestimated when the reference test was interpreted with knowledge of the test result (RDOR, 1.3; 95% CI, 1.0-1.9), when no criteria for the test were described (RDOR, 1.7; 95% CI, 1.1-2.5), and when no description of the population under study was provided (RDOR, 1.4; 95% CI, 1.1-1.7). CONCLUSION: These data provide empirical evidence that diagnostic studies with methodological shortcomings may overestimate the accuracy of a diagnostic test, particularly those including nonrepresentative patients or applying different reference standards.

Bias↗
PubMed2001

Assessment of a new logistic model in the preoperative evaluation of adnexal masses.

OBJECTIVE: To assess a new logistic regression model developed to predict malignancy in adnexal masses. METHODS: In the first part of this study, we developed a logistic model by applying logistic regression analysis in a series of 268 adnexal masses (203 benign and 65 malignant lesions) in 248 patients (mean age, 43.6 years; SD, 14.2 years) evaluated and treated at our institution. Eleven parameters were entered in the logistic regression analysis in a forward stepwise way. In the second part of the study, we evaluated the model's diagnostic performance in a further set of 135 adnexal masses (103 benign and 32 malignant tumors) in 129 patients (mean age, 44.4 years; SD, 14.6 years). This diagnostic performance was compared with that of age, tumor volume, Sassone's and Ferrazzi's B-mode ultrasonographic morphologic scoring systems, serum cancer antigen 125 level, and the tumor's lowest resistive index. Comparison was done by calculating the area under the receiver operating characteristic curve. RESULTS: In logistic analysis, only menopausal status, the presence of papillary projections, the logarithm of the cancer antigen 125 value, tumor blood flow location, and the lowest resistive index were retained in the model. The model had the best area under the curve (0.97), significantly higher than patient age (area under the curve, 0.78; P = .001), tumor volume (area under the curve, 0.68; P < .0001), cancer antigen 125 (area under the curve, 0.88; P = .008), lowest resistive index (area under the curve, 0.85; P = .011), Ferrazzi's scoring system (area under the curve, 0.89; P = .01), and maximal peak systolic velocity (area under the curve, 0.71; P< .0001). Comparison with Sassone's scoring system (area under the curve, 0.91) did not reach statistical significance, but a clear trend was found (P = .116). CONCLUSIONS: The model had the best diagnostic performance for discriminating between benign and malignant adnexal masses. A clinical prospective evaluation is needed to confirm its actual value.

Adnexal Diseases↗
PubMed1998

International standards for test methods and reference sera for diagnostic tests for antibody detection.

International standards are necessary to ensure that the diagnostic tests used by trading partners meet a minimum standard of diagnostic performance. The tests that are used to qualify animals for international movement must provide a degree of confidence that those animals which give negative test results (and therefore qualify for movement) are free of a particular infectious disease agent. Without the development of standards for diagnostic tests, no level of international harmonisation can ever be achieved. International standards for both test methods and sera serve to establish a baseline on which inferences can be made with respect to the diagnostic performance of a given test in a given laboratory. International standard test methods set baseline analytical and diagnostic performance requirements for new reagents or methodologies. International standard sera are primary reference standards and serve as both reference materials for the calibration of test methods and reagents and prototypes for the production of national and working standards. For most serological test methods, three standard sera should be established: a strong positive, a weak positive and a negative standard. These standards are used to calibrate the detection range and analytical sensitivity of the test method. Assays calibrated in this way are more likely to exhibit a diagnostic sensitivity and specificity which parallels that of the standard test method, thus resulting in a higher degree of international harmonisation.

Animals↗