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At least 109 records · Page 6Linked to original sources
PubMed2002

Prospective screening for blunt cerebrovascular injuries: analysis of diagnostic modalities and outcomes.

OBJECTIVE: To prospectively examine outcomes associated with an aggressive screening protocol for blunt cerebrovascular injury (BCVI), and to compare the accuracy of computed tomographic angiography (CTA) and magnetic resonance angiography (MRA) versus conventional angiography with respect to BCVI diagnosis. SUMMARY BACKGROUND DATA: In the past 5 years, BCVI (carotid and vertebral arteries) has been recognized with increasing frequency. Initial studies described blunt carotid injuries and their associated morbidity, while more recent reports have established the devastating potential of blunt vertebral injuries. It has been suggested that early diagnosis and anticoagulation will improve outcomes and that less-invasive diagnostic techniques than conventional angiography are desirable for screening. However, there are neither established screening criteria nor studies comparing optimal diagnostic modalities. METHODS: The screened population included all patients with cervical spine fractures, LeFort II or III facial fractures, Horner's syndrome, skull base fractures involving the foramen lacerum, neck soft tissue injury, or neurological abnormalities unexplained by intracranial injuries. Patients underwent screening with four-vessel cerebral angiography. During the first half of the study, patients also underwent helical CTA. Selected patients during this same period underwent MRA. At the time of diagnosis, anticoagulant or antiplatelet therapy was instituted unless clinically contraindicated. Results of this screening protocol were compared to a previously published cohort with cerebrovascular injuries (1995-1999) from the authors' institution. RESULTS: Two hundred sixteen patients were screened over a 2-year period (3.5% of all blunt trauma admissions). Angiography identified 24 patients with carotid artery injuries (CAI) and 43 patients with vertebral artery injuries (VAI) for an overall screening yield of 29%. While the incidence of CAI remained similar between the current study and the previous study group, the incidence of VAI diagnosis increased. Stroke rates in those with CAI were also similar between the two periods. The stroke rate in VAI, however, was markedly lower at 0% as compared to 14% in the previous group. Comparison of CTA and MRA with cerebral angiography in 143 patients demonstrated sensitivities of 47% and 50%, respectively, for CAI; sensitivities were 53% (CTA) and 47% (MRA) for VAI. CONCLUSIONS: Aggressive screening of patients with blunt head and neck trauma identified an incidence of BCVI in 1.03% of blunt admissions. Early identification, which led to early treatment, significantly reduced stroke rates in patients with VAI, but provided no outcome improvement with CAI. More encompassing screening may be required to improve outcomes for patients with CAI. However, less-invasive diagnostic techniques (CTA and MRA) are inadequate for screening. Technological advances are necessary before abandonment of conventional angiography, which remains the standard for diagnosis.

Adult↗
PubMedDate not supplied

Relation of observer agreement to accuracy according to a two-receiver signal detection model of diagnosis.

A long-standing problem of medical diagnosis is why rates of observer disagreement are so high. To study this question a model of test interpretation is defined which accounts for disagreement when observers use identical diagnostic strategies. Test subjects are assigned to one of two disease classes on the basis of two parameters: the test score and lambda, the diagnostic certainty, a parameter analogous to signal-to-noise ratio. The rate of disagreement and the mean error rate of independent ideal observers are derived as a function of diagnostic strategy. It follows from the model that: 1) Maximization of the ratio of disagreement to error defines an optimal diagnostic strategy with advantages over maximum likelihood and Bayes diagnostic strategies. 2) Disagreement exceeds error if the sensitivity and specificity of independent observers exceed one-half for all lambda. 3) The ratio of disagreement to error can be no greater than two if test interpretation is dichotomous but can approach infinity for trichotomous interpretation, i.e., if observers are allowed to interpret cases as indeterminate.

Bayes Theorem↗
PubMed2000

Diagnostic dilemmas in detection of prostate cancer in patients undergoing transrectal ultrasound-guided needle biopsy of the prostate.

Transrectal ultrasound (TRUS)-guided needle biopsy of the prostate is a widely practised method for obtaining high quality tissue cores for histological diagnosis in men with suspected prostate cancer. Technological advances such as high-resolution hand held probes with biplanar imaging capabilities and spring-loaded needles that easily permit multiple biopsies to be obtained have ensured that this technique has rightly taken its place at the forefront of prostate cancer diagnosis. However, the capacity for TRUS to identify prostate cancer remains limited because of poor specificity and variability in the ultrasonic appearance of tumours. Widespread prostate-specific antigen (PSA) testing has increasingly resulted in greater numbers of tumours being diagnosed at an early stage, when they are clinically impalpable and ultrasonically indistinguishable from surrounding normal prostate tissue. In this setting, the principal role for TRUS is to facilitate systematic sampling of all relevant zones of the prostate. Despite advances in technology and in our understanding of this disease, a number of diagnostic dilemmas arise. Should we perform lesion-directed or random biopsies? How many tissue cores should be obtained for optimal diagnostic yield, to reduce the incidence of false-negative biopsies? What areas of the prostate should be biopsied to give the best diagnostic results? If the initial biopsies fail to detect cancer, who should undergo repeat biopsy? Some have also voiced concern that TRUS risks identifying clinically insignificant disease. Here, we review the studies that have addressed these issues and have lead to the evolution of TRUS-guided prostate biopsy into an essential tool in the detection of carcinoma of the prostate. Prostate Cancer and Prostatic Diseases (2000) 3, 13-20

Journal Article↗
PubMed1999

[Diagnosis of coronary disease: thallium-201 dipyridamole tomoscintigraphy of the myocardium].

OBJECTIVES: Determine the diagnostic performance of thallium-201 myocardial scintigraphy using dipyridamole injection for the detection of coronary heart disease (myocardial ischemia and/or necrosis). Determine for each coronary artery the degree of angiographic stenosis for optimal diagnostic performance. PATIENTS AND METHODS: The study included 309 patients who underwent coronarography within 6 months of the scintigraphy examination. None of the patients experienced a coronary event during this interval. Diagnostic performance of the scintigraphic exploration was compared with angiographic findings (stenosis 70%) used as the gold standard. The degree of angiographic stenosis for optimal scintigraphic performance was determined from the receiver operating characteristic (ROC) curves. RESULTS: The sensitivity of scintigraphy to detect angiographically demonstrated coronary disease was 84% with a specificity of 72%. The positive and negative predictive values were 87% and 66% respectively. Test accuracy was 80%. Sensitivity was better for detecting lesions of the anterior interventricular coronary than for the right coronary or circumflex. In addition, sensitivity varied with the number of vessels involved: 76% for single-vessel disease versus 90% for two- or three-vessel disease. The data analysis also suggested that an angiographic stenosis threshold of 50% provided optimal predictive value for scintigraphy for each of the three vessel territories. An analysis based on maximal stenosis in each patient, notwithstanding the congruency between lesion localization and diseased vessel territories, was found to provide less diagnostic precision. CONCLUSION: Thallium-201 dipyridamole myocardial scintigraphy offers diagnostic performance comparable to that established with thallium-201 scintigraphy performed after exercise alone. Scintigraphic detection of a perfusion defect generally corresponds to an angiographic stenosis of 50%.

Coronary Disease↗
PubMed1993

Economic/reimbursement issues in MR imaging with gadolinium contrast agents.

Implementation of an accurate, reliable index of cost effectiveness would help to advance technology assessment and reimbursement of MR imaging procedures, including gadolinium enhancement. To this end, an objective, consensual measure that satisfies the need for "gold-standard" confirmation of diagnostic impressions in routine clinical practice and limits interpreter bias has been developed. Eponymously termed Diagnostic Merit, this barometer is expressed as the percentage of independent judges confirming diagnostic impressions entered by case-blinded radiologists assigned unenhanced and enhanced image sets for interpretation. The judges, who are informed of clinical indications, clinical follow-up, and unblinded diagnostic interpretation of the MR scans, confirm only those case-blind interpretations deemed "close enough for diagnostic utility" to actual clinical profiles. According to this method, gadopentetate dimeglumine has been shown to be cost effective by promoting optimal diagnostic performance. This improvement in utility offsets the cost of the gadolinium contrast agent. Efficacies of gadodiamide and gadoteridol, two other contrast agents in development, have been demonstrated by other measures but are probably also evaluable through the Diagnostic Merit method. CPT-4 codes for contrast-enhanced MR imaging are reviewed.

Cost-Benefit Analysis↗
PubMed2002

[Diagnostic and therapeutic strategy for an incidental finding of an adrenal mass].

The incidental finding of an unsuspected adrenal mass ranges from 0.5% to 5% in abdominal CT series. The optimal diagnostic approach to such masses is to diagnose malignant or secretory tumors requiring excision and to otherwise avoid unnecessary surgery. Physical examination generally contributes little. A standard biochemical evaluation should include the measurement of 24 hour urinary catecholamines and metanephrine, urinary free cortisol and plasma cortisol levels at 8 a.m. and 8 p.m. combined with an overnight low-dose dexamethasone suppression test, serum potassium assay, and determination of upright plasma aldosterone to plasma renin activity. These tests will serve to screen for pheochromocytoma, subclinical Cushing's syndrome, and primary hyperaldosteronism respectively. Imaging characteristics suggestive of malignancy include: size greater than 4 cm., heterogeneous lesion and/or density greater than 20 Hounsfield Units on CT scan, slow enhancement with delayed washout after intravenous contrast injection on CT scan, and slightly decreased signal intensity in out of phase (fat suppressed) MR acquisition. Fine-needle aspiration biopsy should be performed only if metastatic disease is suspected. Adrenal scintigraphy with iodocholesterol may be useful where adenoma with subclinical Cushing's syndrome or solid tumor is suspected. In summary, the following strategy is recommended for the management of adrenal incidentalomas : mass lesions larger than 4 cm. and hormone-secreting tumors should be removed. All non-secreting adrenal incidentalomas smaller than 4 cm. in diameter should be followed by serial imaging at regular intervals (6, 12, and 36 months) and by endocrine reevaluation at one year.

Adrenal Cortex Function Tests↗
PubMed1984

Guidelines for radiation protection in the cardiac catheterization laboratory.

Even though radiation levels in the catheterization laboratory are the highest encountered during any commonly performed diagnostic study, dose levels to laboratory personnel should not approach the maximum permissible. A certain minimum amount of radiation is necessary to produce optimal diagnostic images. Therefore, optimum use of radiation protection devices and measures is essential. The goal should be dose minimization, keeping personnel radiation dose as low as reasonably achievable. In the cardiac angiographic suite this goal can be assumed to have been accomplished if: (1) maximum use is made of suitable radiation protection devices, (2) film-and video-imaging chains are optimized, (3) good radiographic technique is employed, (4) strict ongoing quality control programs are maintained for radiographic equipment and cine processor, and (5) there is compliance with all federal, state and local regulations for the safe use of ionizing radiation.

Allied Health Personnel↗
PubMed1985

Biochemical identification of patients with gallstones associated with acute pancreatitis on the day of admission to hospital.

Current trends in the treatment of gallstone pancreatitis require rapid diagnosis of cholelithiasis. This study evaluates the diagnostic potential of plasma aspartate aminotransferase (AST), alkaline phosphatase, and bilirubin on the day of admission to hospital in 215 attacks of acute pancreatitis. The optimal diagnostic cut-off level for AST was 60 IU/1. A transient elevation above 60 IU/1 was recorded in 111 (84.1%) of 132 attacks associated with gallstones, but in only 12 (14.5%) of 83 attacks without stones, and was unrelated to the severity of the attack. Elevated levels of alkaline phosphatase and bilirubin were also more common in attacks associated with gallstones but were less reliable for the identification of cholelithiasis than AST. As a sensitive indicator of hepatocyte disruption, the early and transient rise in plasma AST is consistent with the concept of transient ampullary obstruction in gallstone pancreatitis, and may be useful in identifying patients who require urgent surgical or endoscopic disimpaction.

Acute Disease↗
PubMed1999

Testicular sperm extraction: comprehensive analysis with simultaneously performed histology in 1418 biopsies from 766 subfertile men.

The introduction of intracytoplasmic sperm injection (ICSI) has revolutionized treatment of male-factor infertility. Even with a single spermatozoon a pregnancy can be achieved. In cases of azoospermia due to obstruction or highly impaired spermatogenesis, spermatozoa can be retrieved directly from testicular tissue recovered by testicular biopsy followed by sperm extraction. The predictive value of histology from semi-thin sections of testicular biopsies was assessed in relation to testicular sperm extraction (TESE) results, using 1418 biopsy samples from 766 subfertile men which were evaluated simultaneously using a modified Johnsen score and an ordinal classification system for spermatozoa in TESE samples. In 655 men bilateral samples were available. Based on histological findings and TESE results, the quality of spermatogenesis in the right testes was significantly better than that in the left testes. There was a difference between the two sides in 35.7% of all patients for histology and 32.7% for TESE results. When best results from either testis were used for analysis, 76.9% of all men revealed spermatozoa in TESE preparations, although during histological evaluation of semi-thin sections only 64% of all men had shown mature spermatids. In a core group of 250 azoospermic men without anamnestic hints to obstruction and most likely to benefit from ICSI, TESE was successful in 62.8% men. Subdivision of this group dependent on follicle stimulating hormone (FSH) serum concentrations revealed that even in cases of increased FSH concentration, between 39.1 and 64.7% of men showed mature spermatids in their TESE samples. A subset of 70 azoospermic men from the main sample with symptoms and history suggestive of an obstruction and considered as positive controls showed a positive TESE result in all patients. The histology had failed to predict this in 2.9% of all cases. Nevertheless, in five men an early stage of testicular tumour (carcinoma in situ = CIS) was detected. Two of these males suffered from bilateral CIS. This reflects a prevalence of 0.7% testicular malignancy in the group of patients without a history of excurrent duct obstruction. The data demonstrate that a trial TESE with histology based on the semi-thin sectioning technique is a powerful diagnostic and therapeutic procedure, which justifies the invasive nature of sperm retrieval for ICSI. In addition, the results stress the importance of bilateral biopsies to gain optimal diagnostic and therapeutic results.

Adult↗
PubMed1995

Sample adequacy in detecting Chlamydia trachomatis.

OBJECTIVE: Chlamydia trachomatis is an important etiological agent in female genital infection and may result in infertility. In recent years rapid diagnostic methods have become widely used as alternatives to cell culture. Our objective was to evaluate the technique of direct fluorescence assay (DFA) in estimating the presence of C. trachomatis. METHODS: Specimens taken from 40 infertile and 20 fertile women were examined by DFA for the presence of C. trachomatis. RESULTS: Six of forty (15%) infertile women were found to be positive whereas no positive specimens were detected in the control group. When the specimens were grouped into those which were adequate or inadequate, 19 and five specimens, respectively, were adequate in the infertile and healthy groups. If only adequate specimens are included in estimating the presence of Chlamydia, the percentage is 31.6%. CONCLUSIONS: In order to use DFA as a more reliable and rapid diagnostic test of C. trachomatis in female genital infection, false-negativity must be eliminated. Specimens must be collected adequately and concentrated in order to achieve optimal diagnostic success.

Cervix Uteri↗
PubMed2001

[Usefulness of thoracic imaging and computed tomography in evaluation of neoplastic changes of lungs and mediastinum in children].

Radiological methods of imaging diagnostics allow to evaluate exactly and to monitor the treatment course of pathological lesions in chest. Basic examinations are: plain chest X-ray and computer tomography. Optimal diagnostic algorithm of neoplastic changes in chest is not always univocally defined. The aim of the study is to compare the results of estimation of the presence and type of neoplastic changes in mediastinum and lungs based on X-ray and computer tomography. The results indicate that initial and control X-ray examination allows to diagnose mediastinal lymphadenopathy coexisting with pulmonary hilus extension. CT is used to diagnose and monitor lung tissue and mediastinal changes.

Adolescent↗
PubMed1989

[General problems of selection and interpretation of diagnostic methods].

The author draws attention to general principles which must be respected in the selection and interpretation of diagnostic methods. He discusses the importance of basic characteristics of the diagnostic test (reliability, accuracy, sensitivity, specificity, predictive value) and their application in the examination process. He explains the importance of ROC analysis in the selection of the optimal diagnostic method. He refers to the criteria which must be taken into account when introducing and evaluating a new examination method.

Diagnosis↗
PubMed2000

Venous thromboembolic disease: an observational study in medical-surgical intensive care unit patients.

PURPOSE: Acute and chronic illness, immobility, and procedural and pharmacologic interventions may predispose patients in the intensive care unit (ICU) to venous thromboembolic (VTE) disease. The purpose of this study was to observe potential risk factors and diagnostic tests for VTE, and prophylaxis against VTE in medical-surgical ICU patients. MATERIALS AND METHODS: In a prospective observational study, 93 consecutive patients admitted to a mixed medical-surgical ICU were followed. We recorded demographics, admitting diagnoses, APACHE II score, VTE risk factors, antithrombotic, anticoagulant and thrombolytic agents, diagnostic tests for deep venous thrombosis (DVT) and pulmonary embolus (PE), and clinical outcomes. RESULTS: Patients were 65.5 (15.5) years old with an APACHE II score of 21.1 (9.0); 44 (47.3%) were female. Admission diagnoses were medical (58, 67.4%) and surgical (35, 37.6%). The duration of ICU stay was 3 days (interquartile range: 1, 8.5 days) and the ICU mortality rate was 20.4% (19 of 93). We observed 8 VTE events among 5 of 93 patients (incidence 5.4% [0.8 to 10.0]); 2 patients had DVT and PE before admission, 1 had DVT as an admitting diagnosis, 1 had DVT on day 2 and PE on day 3, and 1 had PE on day 2. Over 804 ICU patient-days, 2 of 5 ultrasound examinations diagnosed DVT and 2 of 3 ventilation-perfusion lung scans diagnosed PE. Of 64 patients in whom heparin was not contraindicated and who were not anticoagulated, subcutaneous heparin prophylaxis was prescribed for 40 (62.5%) patients. ICU-acquired VTE risk factors were mechanical ventilation (odds ratio [OR] 1.56), immobility (OR 2.14), femoral venous catheter (OR 2.24), sedatives (OR 1.52), and paralytic drugs (OR 4.81), whereas VTE heparin prophylaxis (OR 0.08), aspirin (OR 0.42), and thromboembolic disease stockings (OR 0.63) were associated with a lower risk. Only warfarin (OR 0.07, P =.01) and intravenous heparin (OR 0.04, P<.01) were associated with a significantly decreased risk of VTE. CONCLUSIONS: Several ICU-acquired risk factors for VTE were documented in this medical-surgical ICU. VTE prophylaxis was underprescribed, and VTE diagnostic tests were infrequent. Further research is required to determine the incidence, predisposing factors, attributable morbidity, mortality, and costs of VTE in medical-surgical ICU patients, the optimal diagnostic test strategies, and the most cost-effective approaches of prophylaxis.

APACHE↗
PubMed1994

Generating explanations and tutorial problems from Bayesian networks.

We present a system that generates explanations and tutorial problems from the probabilistic information contained in Bayesian belief networks. BANTER is a tool for high-level interaction with any Bayesian network whose nodes can be classified as hypotheses, observations, and diagnostic procedures. Users need no knowledge of Bayesian networks, only familiarity with the particular domain and an elementary understanding of probability. Users can query the knowledge base, identify optimal diagnostic procedures, and request explanations. We describe BANTER's algorithms and illustrate its application to an existing medical model.

Algorithms↗
PubMed2000

Combining diagnostic test results to increase accuracy.

When multiple diagnostic tests are performed on an individual or multiple disease markers are available it may be possible to combine the information to diagnose disease. We consider how to choose linear combinations of markers in order to optimize diagnostic accuracy. The accuracy index to be maximized is the area or partial area under the receiver operating characteristic (ROC) curve. We propose a distribution-free rank-based approach for optimizing the area under the ROC curve and compare it with logistic regression and with classic linear discriminant analysis (LDA). It has been shown that the latter method optimizes the area under the ROC curve when test results have a multivariate normal distribution for diseased and non-diseased populations. Simulation studies suggest that the proposed non-parametric method is efficient when data are multivariate normal.The distribution-free method is generalized to a smooth distribution-free approach to: (i) accommodate some reasonable smoothness assumptions; (ii) incorporate covariate effects; and (iii) yield optimized partial areas under the ROC curve. This latter feature is particularly important since it allows one to focus on a region of the ROC curve which is of most relevance to clinical practice. Neither logistic regression nor LDA necessarily maximize partial areas. The approaches are illustrated on two cancer datasets, one involving serum antigen markers for pancreatic cancer and the other involving longitudinal prostate specific antigen data.

Journal Article↗
PubMed1997

Magnetic resonance angiography in the resectability assessment of suspected pancreatic tumours.

The aim of this prospective study was to evaluate MRI, including MR angiography (MRA), in the preoperative assessment of the resectability of suspected malignancy of the pancreas. A total of 17 patients with suspected pancreatic carcinoma and planned surgery were investigated with conventional angiography, ultrasonography with Doppler technique, MRI and MRA. The MRA protocol included both 2D inflow angiography and 3D phase-contrast angiography. Surgery was carried out in 13 patients. The image quality of MRA was judged satisfactory in all cases. The findings with respect to vascular involvement agreed between the radiological methods in all but 3 cases. When the findings were correlated with the final diagnosis, one false-negative case was found for each of the three methods. The results suggest that MRI with MRA, including both the phase-contrast and inflow techniques, has a similar diagnostic value to that of conventional angiography and ultrasonography in the preoperative assessment of the portal venous system in patients with pancreatic carcinoma. Further studies are needed to establish the optimal diagnostic procedure.

Biopsy↗
PubMed2001

Dipyridamole-atropine-induced myocardial infarction in a patient with patent epicardial coronary arteries.

BACKGROUND: The diagnostic accuracy of the physical and pharmacological stress echocardiography tests is higher than routine exercise electrocardiography. They have an acceptable safety profile and have been rarely associated with severe adverse effects. CASE REPORT: We present a case of acute anterior myocardial reinfarction immediately after exercise and pharmacological (dipyridamole-atropine) stress echocardiography testing 1 month after successful stent implantation in LAD. Our patient was a 43-year-old man with a history of heavy smoking and hypertension. Remarkably, the stress echocardiogram was non-diagnostic few hours before the infarction occurred. Angiography performed 4 months after the reinfarction revealed neither a culprit lesion nor stent thrombosis. CONCLUSION: Aggressive "last generation" pharmacological stress testing may provide optimal diagnostic accuracy, but as in our case, complications may occur, even after negative stress testing. To our knowledge, this is the first reported case of an acute myocardial infarction as a severe complication of stress testing, which developed in a patient after stent implantation.

Adult↗
PubMedDate not supplied

Role of ultrasonography in the diagnosis and management of thyroid cancer.

OBJECTIVE: To review the role of ultrasonography in the detection and management of thyroid cancer. METHODS: Viewpoints are presented on the appropriate applications and the advantages of ultrasonography, based on an extensive personal experience with more than 1,500 ultrasound examinations for assessment of thyroid nodules and for follow-up surveillance of patients with thyroid cancer. RESULTS: Ultrasonography is ideal for thyroid imaging because of the high echogenicity of thyroid tissue, the superficial site of the thyroid that allows the use of high-frequency transducers yielding high resolution, and the low expense compared with other techniques. In patients with a thyroid nodule, ultrasonography can assist in distinguishing benign from malignant disease. Ultrasound studies will characterize the presence of cystic versus solid elements, the degree of echogenicity of solid elements, the existence of calcifications, and the regularity and definition of the nodule borders. Although individual sonographic features of thyroid nodules are not specific for benign or malignant lesions, a constellation of typical features has more diagnostic value. Hypoechogenicity, poorly defined irregular margins, and microcalcifications are characteristics that should increase the index of suspicion for a malignant nodule. Cytologic examination of fine-needle aspirates is the optimal diagnostic test, and ultrasonographic guidance for performance of the aspiration biopsy is often helpful and sometimes critical. Ultrasonography is also useful for detection of cervical lymph node metastatic lesions. Lymph nodes involved with metastatic thyroid cancer tend to become rounded and bulging, and they lose their hilar echoes as their structure becomes disrupted. CONCLUSION: Because of its high resolution and relatively reasonable cost, ultrasonography is valuable in the diagnosis and management of thyroid cancer.

Humans↗