Diagnostic accuracy meta-analysis: review of an important tool in radiological research and decision making

Accuracy of transvaginal sonoelastography for differential diagnosis between malignant and benign cervical lesions: A systematic review and meta-analysis

BACKGROUND

To evaluate the performance of transvaginal sonoelastography (TVSE) for differential diagnosis between malignant and benign cervical lesions using a meta-analysis.

METHODS

An independent literature search was conducted on the English medical database, including PubMed, Embase and Medline, Cochrane Library, Web of Science, and OVID. The diagnostic accuracy of TVSE was compared with that of histopathology, which is the gold reference standard for diagnosis. The accuracy of TVSE was assessed by calculating the pooled sensitivity, specificity, diagnostic odds ratio, and area under the curve (AUC). The imaging mechanisms, assessment methods, and QUADAS scores were assessed with a meta-regression analysis. A Deeks funnel plot was performed for evaluating publication bias.

RESULTS

Six eligible studies reported a total sample of 615 cervical lesions (415 cancers, 200 benign lesions). TVSE showed a pooled diagnostic odds ratio of 21.42 (95% CI 13.65-33.61), sensitivity of 0.87 (95% CI 0.84-0.90), specificity of 0.79 (95% CI 0.72-0.84), and an AUC of 0.892 (Q* = 0.822). The results of the meta-regression analysis showed that the imaging mechanism (P = .253), the assessment method (P = .279), or QUADAS score (P = .205) did not affect the study heterogeneity.

CONCLUSION

TVSE has a relatively high and satisfactory value for differential diagnosis between malignant and benign cervical lesions. The diagnostic performance of strain elastography and shear wave elastography were similar and good. However, to accommodate heterogeneity and publication bias, high-quality studies are required to further comparative effectiveness analyses to verify the efficacy of ultrasound detection.

Endothelial damage is aggravated in acute GvHD and could predict its development

The aim of the present study was to explore whether there is enhanced endothelial dysfunction in patients developing acute GvHD (aGvHD) after allogeneic hematopoietic cell transplantation (allo-HCT) and to identify biomarkers with predictive and/or diagnostic value. In in vitro experiments, endothelial cells (ECs) were exposed to serum from patients with (aGvHD, n=31) and without (NoGvHD, n=13) aGvHD, to evaluate changes in surface adhesion receptors, the reactivity of the extracellular matrix by measuring the presence of Von Willebrand factor (VWF) and platelet adhesion, and the activation of intracellular signaling proteins. Plasma levels of VWF, ADAMTS-13, TNF receptor 1 (TNFR1), soluble vascular cell adhesion molecule 1 and soluble intercellular adhesion molecule 1 were also measured. In vitro results showed a more marked proinflammatory and prothrombotic phenotype in ECs in association with aGvHD. Regarding circulating biomarkers, levels of VWF and TNFR1 above an optimal cutoff score, taken independently or combined, at day 7 after allo-HCT, would be able to positively predict that around 90% of patients will develop aGvHD. Our results demonstrate that endothelial damage is aggravated in those allo-HCT recipients developing aGvHD, and that VWF and TNFR1 are promising predictive aGvHD biomarkers. These findings could contribute to improve the understanding of the pathophysiology of aGvHD.

Systematic Review and Meta-Analysis of Studies Evaluating Diagnostic Test Accuracy: A Practical Review for Clinical Researchers-Part II. Statistical Methods of Meta-Analysis

Meta-analysis of diagnostic test accuracy studies differs from the usual meta-analysis of therapeutic/interventional studies in that, it is required to simultaneously analyze a pair of two outcome measures such as sensitivity and specificity, instead of a single outcome. Since sensitivity and specificity are generally inversely correlated and could be affected by a threshold effect, more sophisticated statistical methods are required for the meta-analysis of diagnostic test accuracy. Hierarchical models including the bivariate model and the hierarchical summary receiver operating characteristic model are increasingly being accepted as standard methods for meta-analysis of diagnostic test accuracy studies. We provide a conceptual review of statistical methods currently used and recommended for meta-analysis of diagnostic test accuracy studies. This article could serve as a methodological reference for those who perform systematic review and meta-analysis of diagnostic test accuracy studies.

Uncertainty in clinical prediction rules: the value of credible intervals

Decision making in physical therapy is increasingly informed by evidence in the form of probabilities. Prior beliefs concerning diagnoses, prognoses, and treatment effects are quantitatively revised by the integration of new information derived from the history, physical examination, and other investigations in a well-recognized application of Bayes' theorem. Clinical prediction rule development studies commonly employ such methodology to produce quantified estimates of the likelihood of patients having certain diagnoses or achieving given outcomes. To date, the physical therapy literature has been limited to the discussion and calculation of the point estimate of such probabilities. The degree of precision associated with the construction of posterior probabilities, which requires consideration of both uncertainty associated with pretest probability and uncertainty associated with test accuracy, remains largely unrecognized and unreported. This paper provides an introduction to the calculation of the uncertainty interval, known as a credible interval, around posterior probability estimates. The method for calculating the credible interval is detailed and illustrated with example data from 2 clinical prediction rule development studies. Two relatively quick and simple methods for approximating the credible interval are also outlined. It is anticipated that knowledge of the credible interval will have practical implications for the incorporation of probabilistic evidence in clinical practice. Consistent with reporting standards for interventional and diagnostic studies, it is equally appropriate that studies reporting posterior probabilities calculate and report the level of precision associated with these point estimates.

Accuracy of quantitative ultrasound elastography for differentiation of malignant and benign breast abnormalities: a meta-analysis

The purpose of this study was to systematically review recent literature on diagnostic performance of strain ratio and length ratio, two different strain measurements in ultrasound elastography, for differentiating benign and malignant breast masses. A literature search of PubMed and other medical and general purpose databases from inception through January 2012 was conducted. Published studies that evaluated the diagnostic performance of ultrasound elastography alone reporting either strain ratio or length ratio for characterization of focal breast lesions and using cytology (fine needle aspiration) or histology (core biopsy) as a reference standard were included. Summary diagnostic performance measures were assessed using bivariate generalized linear mixed modeling. Nine studies reported strain ratio for 2,087 breast masses (667 cancers, 1,420 benign lesions). Summary sensitivity and specificity were 88 % (95 % Credible Interval (CrI), 84-91 %), and 83 % (95 % CrI, 78-88 %), respectively. The positive and negative likelihood ratios (LR) were 5.57 (95 % CrI, 3.85-8.01) and 0.14 (95 % CrI, 0.09-0.20), respectively. The inconsistency index for heterogeneity was 6 % (95 % CrI, 1-22 %) for sensitivity and 8 % (95 % CrI, 3-24 %) for specificity. Analysis of three studies reporting length ratio for 450 breast masses demonstrated sensitivity and specificity of 98 % (95 % CrI, 93-99 %) and 72 % (95 % CrI, 31-96 %), respectively. Strain ratio and length ratio have good diagnostic performance for distinguishing benign from malignant breast masses. Although, this performance may not be incrementally superior to that of breast imaging reporting and data system (BIRADS) in B-mode ultrasound, the application of USE using strain ratio or length ratio in combination with USB may have the potential to benefit the patients, and this requires further comparative effectiveness and cost-effectiveness analyses.

Web-based tools for quality assurance and radiation protection in diagnostic radiology

Practical and philosophical aspects of radiation protection in diagnostic radiology have changed very little over the past 50 y even though patient doses have continued to rise significantly in this period. This rise has been driven by technological developments, such as multi-slice computed tomography, that have been able to improve diagnostic accuracy but not necessarily provide the same level of risk-benefit to all patients or groups of patients given the dose levels involved. Can practical radiation protection strategies hope to keep abreast of these ongoing developments? A project was started in 1992 in Liverpool that aimed to develop IT driven quality assurance (QA)/radiation protection software tools based upon a modular quality assurance dose data system. One of the modules involved the assessment of the patient entrance surface air kerma (ESAK) for an X-ray examination that was based upon the use of calibrated X-ray tube exposure factors to calculate ESAK as well as collecting appropriate patient details (age, sex, weight, thickness etc). The package also contained modules for logging all necessary equipment performance QA data. This paper will outline the experience gained with this system through its transition from a local application on a stand alone PC within the department to the current web-based approach. Advantages of a web-based approach to delivering such an application as well as centrally storing data originating on many hospital sites will be discussed together with the scientific support processes that can be developed with such a system. This will include local, national and international considerations. The advantages of importing radiographic examination details directly from other electronic storage systems such as a hospital's radiology information system will be presented together with practical outcomes already achieved. This will include the application of statistical techniques to the very large data sets generated. The development of new examination QA performance indicators will be discussed. The application of web-based IT tools for QA and radiation protection in diagnostic radiology is already opening up the possibility of developing new and improved scientific support services as well as research possibilities in radiological informatics. These will be outlined together with areas for possible future development by the medical physics community.