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PubMed2003

Diagnostic microspheres: an overview.

Diagnostic methods have become increasingly complex and frequently involve the use of agents that must meet the same approval criteria as drugs. The search for diagnostic contrast agents has spread from X-ray to other imaging modalities, especially to magnetic resonance imaging (MRI) and ultrasound. A wide variety of methods have been used to develop microencapsulated agents, from liposomal entrapment to use of biodegradable polymers. Various scientific and technological advancements have been made in the research and development of diagnostic microspheres. Diagnostic microspheres can be used to understand the human body functions in both healthy and sick people. For example, they allow the detection of malignancies vs. benign tissue changes. Diagnostic microspheres give useful clinical information for various diseases, are very stable, and have proven efficacy in the quantitative measurement of blood flow to an organ. This review discusses various aspects of diagnostic microspheres, such as the choice of contrast agents and radioactive molecules, and their applications in blood flow measurements and organ imaging.

Animals↗
PubMed1993

Evaluation of a computer-based diagnostic score system in the diagnosis of jaundice and cholestasis.

A prospective series of 220 patients with jaundice and/or cholestasis was analysed by means of discriminant analysis to evaluate the diagnostic value of various symptoms and signs and basic hepatopancreatobiliary laboratory tests in the differential diagnosis of these patients. In addition, a computer-based diagnostic score (DS) system was developed and compared with the diagnostic value of clinical evaluation (CE), ultrasound (US), computed tomography (CT), and endoscopic retrograde cholangiopancreatography (ERCP). A multivariate stepwise discriminant analysis showed five independent diagnostic factors in distinguishing extrahepatic and intrahepatic diseases: duration of jaundice (p = 0.002), serum protein concentrations (p = 0.002), Normotest (p = 0.04), fever during the past 3 months (p = 0.54), and age (p = 0.58). To sum up the contributions of independent factors, a DS was developed. The discrimination function was as follows: duration of jaundice x 0.97 + age x -0.40 + fever during the past 3 months x 0.33 + serum protein concentration x 0.35 + Normotest x -0.27. The diagnostic sensitivity of DS in the detection of extrahepatic disease was 96%, with a specificity of 80% and an efficiency of 93%. The sensitivities of the imaging methods (62-85%) were inferior to that of DS, whereas the specificities were better (94-98%). The sensitivity of CE was only slightly lower (86%) than that of DS, but the specificity was lowest (57%). In conclusion, relatively few (5 of 40) of the classical symptoms, signs, and biochemical tests proved to be independent diagnostic factors in distinguishing extrahepatic and intrahepatic diseases.(ABSTRACT TRUNCATED AT 250 WORDS)

Cholestasis, Extrahepatic↗
PubMed2000

Evaluation of rapid diagnostic tests for the detection of human immunodeficiency virus types 1 and 2, hepatitis B surface antigen, and syphilis in Ho Chi Minh City, Vietnam.

An evaluation of three new rapid diagnostic test kits for human immunodeficiency virus types 1 and 2 (HIV-1/2), hepatitis B surface antigen (HBsAg), and syphilis involved a two-phase comparison of rapid diagnostic assays using prospectively collected from hospitals and clinics in Ho Chi Minh City, Vietnam. After specificity and sensitivity testing, three new rapid diagnostic test kits were tested in parallel with six commonly used diagnostic test kits. The Determine HIV-1/2 test had fewer indeterminate or equivocal results than the Capillus HIV-1/HIV-2 or HIV Blot 2.2 tests. However, the Determine HIV-1/2 test yielded one false-positive result when compared with the Serodia HIV, HIV Blot 2.2, and microparticle enzyme immunoassay (IMx) HIV tests. The Serodia HBsAg test yielded more false-negative results when compared with the Determine HBsAg diagnostic test kit. The results of the syphilis diagnostic tests evaluated in this clinical trial consistently agreed with those of the rapid plasma reagin test for syphilis. The Determine Syphilis Treponema pallidum (TP) test had three false-positive results compared with the Serodia TP and the Serodia TP x particle agglutination (PA) tests, which had two false-positive results that were confirmed as negative by an ELISA. Application of these serologic tests within this comparative evaluation framework, using the World Health Organization alternative testing strategies, proved to be an effective way to determine serostatus related to HIV, hepatitis B, and syphilis.

Evaluation Studies as Topic↗
PubMed1999

Redundancy of single diagnostic test evaluation.

Diagnostic research and diagnostic practice frequently do not cohere. Studies commonly evaluate whether a single test discriminates between disease presence and absence, whereas in practice a test is always judged in the context of other information. This study illustrates drawbacks of single-test evaluation and discusses principles of diagnostic research. We used data on 140 patients suspected of pulmonary embolism who had an inconclusive ventilation-perfusion lung scan. We evaluated three tests: partial pressure of oxygen in arterial blood (PaO2), x-ray film of the thorax, and leg ultrasound. On the basis of single-test evaluations, ultrasound was most informative. Given a prior probability of 0.27, it had a much better combination of positive and negative predictive value (0.71 and 0.21, respectively) relative to thorax x-ray (0.33 and 0.11) and PaO2 (0.35 and 0.27). The combination of positive and negative likelihood ratio was also more promising for ultrasound (7.3 and 0.7) than for thorax x-ray (1.3 and 0.3) and PaO2 (1.3 and 0.9). As the tests are always performed after the history and physical, we judged their added value using multivariable logistic modeling with receiver operating characteristic (ROC) analyses. The ROC areas of the model, including history and physical, with additional PaO2, thorax x-ray, or ultrasound, were 0.75, 0.77, 0.81, and 0.81, respectively, which indicated similar added value of thorax x-ray and ultrasound. Application of the models to patient subgroups also yielded added predictive value for thorax x-ray film. Thus, the results of single-test evaluations may be very misleading. As no diagnosis is based on one test, single-test evaluations have limited value in diagnostic research and only have relevance in the context of screening and the initial phase of test development. Diagnostic research should always apply an approach of constructing, extending, and validating diagnostic models in agreement with routine clinical work-up using logistic regression analyses.

Analysis of Variance↗
PubMed2000

[Methodology of diagnostic validation studies. Errors in study planning and evaluation].

The evaluation of diagnostic tests play an important role in clinical research. Though detailed standards have been developed for treatment evaluation, widely accepted methodological standards in diagnostic test research are still lacking. Following recent methodological research German biostatisticians usually distinguish between 4 types of diagnostic validation studies (Phase I to IV). The diagnostic value of a test can be described by indexes like sensitivity, specificity and predictive values. Sensitivity and specificity are so-called nosological probabilities whereas predictive values describe the probabilities of the disease given a positive or negative test result, respectively. These posterior probabilities depend on the prevalence of the disease in question. The methodological problems that arise in the planning of diagnostic studies differ from those encountered in treatment evaluation. This contribution presents an annotated checklist of the most important faults and shortcomings in the planning and the analysis of diagnostic validation studies. Avoiding these deficiencies may help that the study results are accepted by biostatisticians, clinicians and cost units.

Bias↗
PubMedDate not supplied

[Diagnostic problems in patients with myasthenia gravis].

Myasthenia gravis (MG) is an antigen-specific autoimmune disease in which antibodies directed against nicotinic acetylcholine receptors of the postsynaptic muscle membrane (nAChR) impair neuromuscular transmission. MG is clinically characterized by abnormal muscle fatigue and weakness. The initial symptoms and signs are often unrecognized. Therefore, we analyzed the diagnostic errors and duration of diagnostic delay in patients affected with MG (n = 444) in a ten-year period (January 1, 1983-December 31, 1992) in Yugoslavia. The initial diagnosis was correct in 44.4% of patients and erroneous in 38.4%; 17.2% of patients were admitted without an initial diagnosis. The average duration of diagnostic delay was 11 months. We present the differential diagnostic difficulties in MG and discuss the principles of diagnostic strategy which may reduce the risk of diagnostic errors in MG.

Adult↗
PubMed2001

Imaging diagnostic approach to tumours of ramus and angle of the mandible.

The abundance of up-to-date diagnostic equipment and imaging techniques makes it necessary to reconsider diagnostic approach to many maxillofacial disorders, including mandibular tumours, and to elaborate algorithms of radiological examinations allowing for the planning of a cost-effective treatment based on thorough diagnostics. The material was composed of 146 case records of 68 patients examined in the years 1995-2000 in the Medical University of Lublin. There were selected radiograms as well as the results of other imaging modalities of persons with clinically confirmed tumours of mandibular ramus or angle. In each case there were noted: the initial and the final diagnosis as well as the number and sequence of the performed diagnostic examinations. On the basis of the obtained results there was proposed a diagnostic algorithm in cases of mandibular angle and ramus tumours, which was presented in the form of a scheme. It was proved that conventional radiograms are still fundamental in initial selection of patients while other diagnostic imaging methods are indispensable in treatment planning.

Diagnostic Imaging↗
PubMed2002

[Systematic reviews in practice. X. Searching, selecting and the methodological assessment of diagnostic evaluation research].

Literature concerning the value of diagnostic tests is poorly indexed in electronic bibliographical databases. An extensive, sensitive and specific search strategy for evaluation of a diagnostic test in Medline is a combination of key words or text words concerning the diagnostic test with: 'sensitivity and specificity' (exploded), 'mass screening' (exploded), 'reference values', 'false positive reactions', 'false negative reactions', 'specificit$.tw', 'screening.tw', 'false positive$.tw', 'false negative$.tw', 'accuracy.tw', 'predictive value$.tw', 'reference value$.tw', 'roc$.tw' or 'likelihood ratio$.tw'. Inclusion and exclusion criteria select publications which meet certain minimum requirements, such as the presence of an accepted reference standard, a clear definition of 'diseased', and the presence of a suitable outcome measure. The methodological assessment list should contain a number of validity criteria as well as a number of criteria by which to measure the extent to which the study results can be generalised. Important assessment criteria that may affect the diagnostic value of the test are: study design, blinding, use of different reference standards, the absence of details about the diagnostic criteria for the diagnostic test and insufficient information about the study population.

Diagnostic Tests, Routine↗
PubMedDate not supplied

[Comparative evaluation of diagnostic preparations].

The diagnostic value of preparations is commonly characterized by sensitivity and specificity. But not all these characteristics make it possible to decide unequivocally which of the preparations to be compared is superior to the other one with respect to its diagnostic value. It is proposed that in the choice of a diagnostic preparation its capacity to provide data for exact diagnosis should be considered, i.e. the additional characteristic indicating the spread of the disease under study. As an example, the comparison of the diagnostic value of conventional methods and the polymerase chain reaction in the diagnostics of helicobacteriosis is presented. The described method for the evaluation of the diagnostic value of the preparation is well-grounded, simple and obvious.

Antigens, Bacterial↗
PubMed2005

Pulmonary embolism: diagnostic algorithms.

In 90% of cases the clinical suspicion of pulmonary embolism (PE) is raised by clinical signs and symptoms, while in only 10% of cases PE is suspected on the basis of electrocardiographic, arterial blood gas analysis or radiological findings. The combination of clinical signs and symptoms and the results of first-level diagnostic tests (electrocardiography, gas analysis and chest X-ray) allows a fairly accurate classification of patients with "clinical suspicion of PE" into three categories of clinical (or pre-test) probability: low, intermediate and high. The clinical diagnosis of PE is very often inaccurate making the use of additional tests, including imaging techniques, mandatory. The choice and the combination (= diagnostic algorithms) of second- and third-level diagnostic tests (D-dimer, venous ultrasound, echocardiography, lung scintigraphy, helical computed tomography and pulmonary angiography) depend primarily on the clinical conditions of patients and their pre-test probability. We propose two diagnostic algorithms: 1) a diagnostic algorithm for patients with clinically suspected PE and critical clinical conditions (unstable patients), 2) a diagnostic algorithm for patients with clinically suspected PE and non-critical clinical conditions (hemodynamically stable patients).

Algorithms↗
PubMed1995

Responses to a payment policy denying professional charges for diagnostic imaging by nonradiologist physicians.

OBJECTIVE: To assess the impact of a payment policy denying reimbursement for the imaging-related professional services of nonradiologist physicians by comparing the use of and expenditures for diagnostic imaging examinations before and after implementation of the policy. DESIGN: Retrospective economic evaluation of claims and expenditures for diagnostic imaging examinations filed by physicians practicing in the 20 US counties having the greatest number of United Mine Workers of America Health and Retirement Funds (hereafter referred to as Funds) beneficiaries. SETTING: Insurance claims database of Funds beneficiaries, most of whom are elderly and live in rural communities and small towns. INTERVENTION: The January 1, 1993, implementation of a reimbursement policy denying payment of professional claims for diagnostic imaging of nonradiologist physicians. MAIN OUTCOME MEASURES: Numbers and types of eligible claims and Funds payments for diagnostic imaging examinations during the year before and after the intervention, normalized for changes in the number of beneficiaries. RESULTS: Despite the rejection of $811,466 in claims disallowed by the policy, the Funds paid 12% more for diagnostic imaging performed in the 20 counties we studied during 1993 than during 1992. The Funds reimbursed 41% more claims per beneficiary for diagnostic imaging in 1993 than in 1992 (t = -8.03, P < .0001). The absolute number of professional claims per beneficiary increased more than did technical or global claims. CONCLUSIONS: Despite a payment policy designed, in part, to reduce the Funds' imaging-related expenditures, the physicians we studied filed more claims, leading to greater expenditures. An increased number of self-referred technical claims and greater referral to hospital radiology departments likely account for most of the observed increases in utilization and costs.

Cost Control↗
PubMed1995

[The efficiency of using diagnostic methods in the polyclinic].

Due to the formation of consulting and diagnostic polyclinics (CDP) in the Russian Armed Forces the significance of multipurpose diagnostical process in military garrison has met a considerable upgrade. The authors take into account the experience of CDP work and recommend to make a rational centralization of diagnostical process and determine the outlook for the development of diagnostical technologies adapted for different polyclinics, making a rational use of modern diagnostical equipment and enhancing the qualification of personnel occupied with diagnostical work.

Diagnosis↗
PubMed1996

The impact of diagnostic testing on therapeutic interventions.

OBJECTIVE: To gain insight into the usefulness of managing the earlier phase of decision making, we examined the relationship between selected diagnostic tests and the therapeutic interventions they might trigger. DESIGN: Medicare's National Claims History and Part B files were used to obtain summary information on 100% of all physician claims submitted from 1987 through 1993. We regressed the annual rates of selected therapeutic interventions on selected diagnostic tests, which had been previously paired based on the clinical expectation that the test might drive subsequent intervention. POPULATION AND SETTING: These data represent the physician services received by approximately 30 million elderly Americans in each of 7 years. MAIN OUTCOME MEASURE: Coefficient of determination (R2). RESULTS: The annual rate for the diagnostic tests increased rapidly during the period (range, 1.4- to 3.0-fold increase) and accounted for the bulk of the variance in therapeutic intervention rates (R2>0.80, P<.01) for five diagnostic-therapeutic pairs: cardiac catheterization with cardiac revascularization procedures, imaging of the spine with back surgery, swallowing studies with percutaneous gastrostomy, mammography with breast biopsy and excision, and prostate biopsy with prostatectomy. Although the rate of abdominal ultrasound increased during the period, it was not related with either cholecystectomy or abdominal aortic aneurysm repair. CONCLUSION: There has been a substantial increase in diagnostic testing in the United States that closely tracked the increase of clinically relevant downstream procedures. Managing diagnostic testing could be an important strategy for controlling the increase of therapeutic interventions.

Diagnostic Tests, Routine↗
PubMed1998

[Research on diagnostic tests in Medicina Clinica. A methodological assessment].

BACKGROUND: Research on diagnostic tests have not reached the same methodological rigour as other areas of clinical research. Identification of more frequent and important methodological flaws could contribute to raise the quality of diagnostic test studies. The aim of this study was to evaluate the methodology of diagnostic test studies published in MEDICINA CLINICA. MATERIAL AND METHODS: Forty two articles about diagnostic test studies published in MEDICINA CLINICA from 1992 through 1995 were selected. Two set of methodological criteria were applied (JAMA 1995; 274: 645-651 and Revisiones en Salud Pública 1993; 3: 243-262). Each article was independently evaluated by two observers. RESULTS: Of the 42 articles evaluated, 33 determined sensitivity and specificity, and 9 only sensitivity. There was a well-defined gold-standard in the majority of the studies (90%) but it was not applied to all patients in 21% of them. Description of the diagnostic test evaluated was present in 79% and test reproducibility was assessed in only 19%. Source of patients, eligibility criteria for study subjects and spectrum composition were considered in 31, 36 and 31%, respectively. Avoidance of work-up bias and review bias was done in 69 and 36% of the articles. Only 12% considered indeterminate results, 50% reported test indexes for relevant clinical subgroups and statistical precision was provided in 17% of the studies. CONCLUSION: Methodological quality of the research on diagnostic tests published in MEDICINA CLINICA is similar to that observed in the best world clinical journals. Nevertheless, there are opportunities to improve several aspects of study design and presentation that will facilitate its clinical applicability and general utility.

Diagnostic Techniques and Procedures↗
PubMed1993

A review of Iliad and Quick Medical Reference for primary care providers. Two diagnostic computer programs.

Two diagnostic computer programs, Iliad (Applied Informatics Inc, Salt Lake City, Utah) and Quick Medical Reference (Camdat Corp, Pittsburgh, Pa), are commercially available. Both describe a large subset of internal medicine diseases. These programs, also called knowledge bases, have different structures and diagnostic methods and emphasize somewhat different experimental observations regarding problem solving and expert diagnostic behavior. Quick Medical Reference has more diverse reference features and emphasizes diagnostic competitors (diseases that explain similar features in a case). Iliad has better developed teaching features and emphasizes a probabilistic approach. The histories and methods of these programs place various constraints on their diagnostic capabilities, especially from a primary care perspective. Although neither program is currently likely to fill the role of an expert diagnostic consultant for a family practitioner, both have potential as unique reference and teaching tools in primary care.

Aged↗
PubMed1997

Primary cardiac lymphoma in immunocompetent patients: diagnostic and therapeutic management.

BACKGROUND: Primary cardiac lymphoma (PCL) is extremely rare in immunocompetent patients. Different definition criteria have been employed in published series. Prognosis is poor due to diagnostic delay and relevance of the site of disease. METHODS: Two cases observed at the study institution are reported, with a review of 48 cases published in the literature from 1980 to 1996. Only patients with lymphoma confined to the heart and/or pericardium and those with a single and asymptomatic extracardiac site were considered for analysis. RESULTS: Eight patients had minimal extracardiac disease. The most common presentation was unresponsive heart failure. Electrocardiography findings were not specific. PCL usually arose in the right chambers as a mass, with or without pericardial effusion (> 80%). Chest X-rays, transthoracic echocardiography, and computed tomography scans are standard in diagnostic workup, but transesophageal echocardiography (TEE) and magnetic resonance imaging (MRI) showed a sensitivity > 90%. Cytology of pericardial effusion was diagnostic in 67% of cases. Thoracotomy was diagnostic in all cases, whereas less invasive procedures had high false-negative rates. Gross resection has no role. Early anthracycline-containing chemotherapy appears to improve survival, whereas the role of radiotherapy has not yet been defined. CONCLUSIONS: The diagnosis of PCL should be considered in patients with a cardiac mass and/or unexplained refractory pericardial effusion. Adequate diagnostic workup, including TEE and MRI, allows confirmation of the early suspicion of PCL. In the absence of a diagnostic cytology, an open biopsy may be indicated to avoid treatment delay. There is no evidence that PCL should be treated differently from other bulky aggressive lymphomas arising at other anatomic sites.

Adolescent↗
PubMed1999

Regression diagnostics for the class A regressive model with quantitative phenotypes.

Regression diagnostic methods are developed and investigated under the Class A regressive model proposed by Bonney [(1984) Am J Med Genet 18:731-749]. We call a family whose phenotypic distribution does not conform to the same genetic model as the majority of the families an etiotic family. The exact case-deletion approach for identifying etiotic families, based on examining the changes in each model parameter estimate by excluding one family at a time, is very time-consuming. We proposed three alternative diagnostic methods: the empirical influence function (EIF), the one-step approximation, and the approximated one-step approach. These methods can be computed efficiently and were incorporated into the existing software package S.A.G.E. A thorough Monte-Carlo investigation of the performance of the diagnostic methods was conducted and generally supports the EIF approach as the recommended alternative. The phenotypic variance is the parameter whose associated regression diagnostic most frequently and correctly identified etiotic families in the models that were examined. An analysis of body mass index data from 402 individuals in 122 Muscatine, Iowa families is used to illustrate the methods. A Class A regressive model with a recessive major locus and equal mother-offspring and father-offspring correlations provided the best-fitting model. The proposed regression diagnostics identified up to 7.4% of the 122 families as etiotic. As a result of this investigation, case-deletion diagnostic assessment is now a practical component in the analysis of quantitative family data.

Adolescent↗
PubMed2004

Mac-2-binding protein is a diagnostic marker for biliary tract carcinoma.

BACKGROUND: Biliary tract carcinoma is a deadly disease, accounting for nearly 4500 malignancy-related deaths each year in the United States. Early detection has the potential to improve survival for patients with biliary tract malignancies, enabling curative surgical resection. Early detection approaches would benefit from an accurate, minimally invasive diagnostic test. To identify novel diagnostic markers, the authors recently completed a comprehensive proteomic study of bile samples from patients with biliary carcinoma. One of the proteins identified by tandem mass spectrometry was Mac-2-binding protein (Mac-2BP). The authors evaluated the performance of Mac-2BP and its ligand, galectin-3, as diagnostic markers for patients with biliary carcinoma. METHODS: Levels of Mac-2BP, galectin-3, and CA19-9 were measured using an enzyme-linked immunosorbent assay (ELISA) in bile samples from patients with biliary tract carcinoma (n = 26), benign biliary conditions (n = 32), and primary sclerosing cholangitis (n = 20). Serum levels of Mac-2BP and galectin-3 also were determined using ELISA. Mac-2BP tissue expression was investigated by immunohistochemical methods using a biliary carcinoma tissue microarray. RESULTS: Biliary Mac-2BP levels were elevated by a factor of approximately 3 in the biliary carcinoma group compared with the group of patients who had PSC or another type of nonneoplastic biliary disease. In contrast, Mac-2BP levels were not elevated in serum samples from patients with biliary carcinoma. According to the immunohistochemical analysis, Mac-2BP was expressed in 34 of 36 patients (94.4%) with biliary tract carcinoma. As a diagnostic marker for biliary carcinoma, Mac-2BP levels were as accurate as biliary CA19-9 levels, with an area under the curve (AUC) of 0.70 on receiver operator characteristic analysis. The use of both of these bile markers in combination, however, led to significantly better diagnostic accuracy compared with the accuracy achieved using CA19-9 alone (AUC, 0.75; P < 0.001). Serum and biliary galectin-3 levels did not differ in the biliary carcinoma group relative to the control groups. CONCLUSIONS: Biliary Mac-2BP levels, especially when used in conjunction with biliary CA19-9 levels, showed promise as a novel diagnostic marker for biliary tract carcinoma.

Aged↗