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PubMed1993

Accuracy of endoscopic ultrasonography in the diagnosis and staging of gastric cancer and lymphoma.

BACKGROUND: There is a need to assess the sensitivity, specificity, and predictive value of endoscopic ultrasonography (EUS) in the diagnosis and staging of gastric cancer and lymphoma. METHODS: A prospective study was performed on 86 patients with endoscopic gross appearance suspicious for cancer or lymphoma. Biopsies with endoscopic forceps were always carried out before EUS. All patients underwent laparotomy for final diagnosis, staging, and eventually treatment. The results of EUS were correlated with the histologic findings of the resected specimens, when possible, or with the surgical findings. There were 42 gastric cancers and 44 primary gastric lymphomas. RESULTS: EUS made a correct diagnosis of cancer in 35 of 42 patients, with a sensitivity of 83%. Positive predictability was 87%, specificity was 97%, and negative predictability was 96%. Diagnostic accuracy was 95%. In the evaluation of cancer depth invasion, EUS was correct in 91% of cases. EUS displayed perigastric metastatic lymph nodes in 14 of 25 patients, with a sensitivity of 56%. Positive predictive value was 93%, specificity was 93%, and negative predictive value was 54%. Diagnostic accuracy was 69%. EUS made a correct diagnosis of lymphoma in 39 of 44 patients, with a sensitivity of 89%. Positive predictability was 87%, specificity was 97%, and negative predictability was 97%. Diagnostic accuracy was 95%. In the evaluation of lymphoma depth invasion, EUS was correct in 92% of cases. EUS displayed metastatic perigastric lymph nodes in 8 of 18 patients, with a sensitivity of 44%. Positive predictability was 100%, specificity was 100%, and negative predictability was 72%. Diagnostic accuracy was 77%. CONCLUSIONS: From these data it appears that in these diseases EUS has demonstrated specific ultrasonographic features that allow correct diagnosis and staging in the majority of patients. In difficult cases EUS may help to achieve the correct diagnosis. EUS also appear to be a useful tool for staging of gastric cancer and lymphoma. It shows not only tumor depth and local spread but also the passage from a pathologic to a normal wall and lymph node metastasis. With this accurate noninvasive staging procedure, in the near future many patients will no longer undergo exploratory laparotomy for surgical staging. Thanks to EUS, the choice of conservative or surgical treatment can be strongly affected. In case of surgery, EUS can orient the kind of surgical approach. Moreover, the use of EUS for evaluation of therapy during follow-up will probably become of major importance.

Adult↗
PubMed1993

The accuracy of predictions of violence to others.

OBJECTIVE: To assess the accuracy of clinicians in predicting violence in mental patients. Specifically, to determine if clinicians can predict violence when variation in rates of violence attributable to age, race, and sex is controlled. DESIGN: Two samples of psychiatric patients, matched on age, race, sex, and admission status, were followed up in the community during a 6-month period. One group included individuals assessed by psychiatric emergency department clinicians as likely to be violent to another person during the follow-up period; the other was a comparison group. Patients provided self-reports of violent incidents, and a "collateral," ie, an individual with detailed knowledge of the patient's life, provided this same information. Official records were also reviewed. SETTING: Patients were recruited in the emergency department of a metropolitan psychiatric hospital. Patients and collaterals were interviewed in their homes or in public places in the community. PATIENTS OR OTHER PARTICIPANTS: A consecutive sample of individuals coming into a psychiatric emergency department during daylight and evening shifts was obtained. A total of 2452 patients were approached for consent and 1948 consented. A final sample of 357 patients whom clinicians assessed as likely to be violent and their matched comparison patients were included. MAIN OUTCOME MEASURES: Patients', collaterals', and official records' reports of incidents in which the patient laid hands on another person or threatened someone with a weapon. RESULTS: Violence during the follow-up period was reported in approximately 45% of the cases: 36% in the comparison group and 53% in the cases predicted to be violent. Overall clinical accuracy was significantly better than chance, but predictions of female patients' violence were not better than chance. CONCLUSIONS: The level of patient violence reported using self-reports and collateral reports was higher than has been obtained using other methods. Clinical judgment adds to predictive accuracy, but overall accuracy was modest and particularly low for female patients.

Adolescent↗
PubMed1993

Accuracy and reproducibility of duplex ultrasound imaging in a phantom model of femoral artery stenosis.

PURPOSE: The improvement of management strategies in patients with intermittent claudication might depend on a better understanding of the natural history of femoral atherosclerosis. The grading of stenoses, the monitoring of their progression, and the assessment of response to treatment are critically dependent on a method's accuracy and variability. Duplex ultrasound imaging provides a noninvasive way of measuring localized disease, but there has been relatively little objective evaluation of its accuracy and reproducibility. The aim of this study was to evaluate the accuracy and variability of duplex velocity ratio measurements of stenosis. METHODS: In a laboratory flow model of the femoral artery, 14 concentric and eccentric stenoses were examined five times by three sonographers. Measurements were then repeated with a standardized technique in which Doppler angle and aperture position were fixed, giving a total of 420 measurements. RESULTS: Velocity ratio showed good correlation with degree of stenosis, R2 = 0.996. Intraobserver variability was low, but interobserver variability was significant with more severe stenosis (p = 0.002, analysis of variance). Standardization of the technique did not improve accuracy or variability. The 95% confidence limit was +/- 20% for a single reading of velocity ratio for stenoses of > 50% diameter reduction. CONCLUSIONS: We conclude that duplex ultrasound imaging can be used to accurately grade arterial stenosis in this range, and the potential exists for noninvasive monitoring of the progression of preocclusive femoral atherosclerosis and its response to treatment. In addition, repeated measurements of velocity ratio over time should be made by the same observer.

Analysis of Variance↗
PubMed1993

Accuracy of CT arterial portography of the liver compared with findings at laparotomy.

To evaluate the accuracy of CT arterial portography (CTAP) of the liver, CTAP examinations from 111 patients were retrospectively reviewed and compared with the findings at laparotomy. Laparotomy had been performed within 3 weeks after the CTAP examination. In cases of resectable liver tumor, the result from the pathologic examination report was used to calculate the accuracy of CTAP. In cases of nonresectable liver tumor or liver without tumor, CTAP findings were compared with the result of a thorough inspection and palpation of the liver. The right liver lobe and the medial and lateral segments of the left lobe were separately evaluated. Thus, a total of 333 lobes/segments were evaluated. Tumor was found at laparotomy in 80 of 333 lobes or segments. At CTAP a total of 94 lobes were evaluated as positive for tumor growth, 23 of these were falsely interpreted as positive and 9 were falsely interpreted as negative when compared with the findings at laparotomy. However, 3 patients called false-positives later turned out to be true-positives since the lesions were overlooked at operation. A sensitivity of 89%, a specificity of 91%, and an accuracy of 90% was calculated for CTAP. It is concluded that CTAP has a higher accuracy than other radiologic methods and should be considered suitable for preoperative evaluation of potentially resectable liver tumor.

Adult↗
PubMed1993

Matrix effects on proficiency testing materials. Impact on accuracy of cholesterol measurement in laboratories in the nation's largest hospital system.

The objective of this collaborative study with the Department of Veterans Affairs (VA), College of American Pathologists (CAP), and the Centers for Disease Control and Prevention (CDC) was to quantitate the matrix-induced biases of cholesterol measurements on the CAP Comprehensive Chemistry Surveys materials used in proficiency testing (PT). A total of 174 VA Medical Centers outpatient clinics and clinical laboratories participate in the VA-CDC National Cholesterol Standardization and Certification Program. This study was conducted in 112 VA laboratories that have been standardized for measuring cholesterol accurately (within +/- 3.0% of the CDC reference-method values) using fresh, unfrozen, unadulterated human serum samples. Fresh serum samples and 1990 CAP Surveys materials were sent by overnight mail, and the laboratories were asked to analyze them simultaneously in triplicate in a single analytic batch run. The results showed significant matrix-effect biases with the CAP Surveys materials with six of the eight major peer groups, despite the fact that accuracy of cholesterol measurements was maintained with fresh serum samples. The magnitude and direction (positive or negative) of the matrix-effect biases were instrument, reagent, and method specific using the following peer groups: du Pont Dimension (-8.9%); Beckman CX4, CX5, and CX7 (-5.5%); Kodak Ektachem 400, 500, and 700 (+4.4%); Instrumentation Laboratory Monarch (-3.1%); Baxter Paramax (-2.4%); Technicon SMAC and RA (+1.3%); Hitachi/BMD 704 through 747 (+0.4%); and Abbott Spectrum (-0.3%). The CAP PT materials used currently do not behave in a manner identical to fresh human serum when measuring cholesterol on many, but not all, analytic systems. The observed biases due to "matrix effects" with PT materials will cause incorrect conclusions about the accuracy of many laboratory procedures performed on fresh patient specimens. This matrix-effect phenomenon will severely hamper interlaboratory accuracy transfer, standardization efforts, and monitoring performance of a laboratory's testing accuracy with the use of the current survey materials used in PT programs. Collaborative efforts are needed to (1) improve PT fluids to analytically behave more like fresh, human serum; (2) improve instrument design and reagent formulation; and (3) select methods and methodologic parameters that are more "robust" and less sensitive to the exact character of processed calibrators, quality control, and PT materials.

Bias↗
PubMed1993

Achieving accuracy for routine clinical chemistry methods by using patient specimen correlations to assign calibrator values. A means of managing matrix effects.

Accurate results obtained from routine methods used in the clinical laboratory can be achieved if the methods are traceable to definitive or reference methods or are based on widely accepted methodologic principles. At Eastman Kodak Co (Rochester, NY), we assign calibrator values for each method that is available on Kodak Ektachem analyzers by correlation to a reference method or a methodologic principle using patient specimens. Kodak's Reference Laboratory is responsible for maintaining the accuracy and consistency of the reference method or methodologic principle by standardizing with National Institute of Standards and Technology materials, where available, monitoring performance through statistical process control, participating in proficiency testing programs, and following procedures consistent with the International Organization for Standardization guideline, "General Requirements for the Competence of Calibrations and Testing Laboratories (ISO 25). "Patient samples that span the reportable range are run in replicate on the reference method or methodologic principle over several days. These patient sample results are then used to create a calibration curve based on the relationship of concentration to the raw response of the routine method, where the same patient samples are also run in replicate on the same day. Each day, multiple vials of stable calibrator fluids are included in these tests, along with control materials. Each calibrator is assigned a value of equivalent concentration (in millimoles per liter) by predicting the concentration that would be present at the measured response if the test fluid were a patient sample. These are termed supplementary assigned values (SAVs). The same calibrators can be used to compensate for matrix effects resulting from changes in reagent formulations, by appropriately adjusting the assigned values. For example, when a process improvement for Kodak Ektachem clinical chemistry slides for phosphorus was introduced, an SAV change of 0.39 mmol/L (1.2 mg/dL) was required for one calibrator to maintain accuracy of the patient samples. A comparison of patient samples, using the SAVs specific for each formulation, gave excellent correlation (in millimoles per liter; r2 = 0.995) by the following equation: New Formulation = 1.02 (Old Formulation) -0.016; Sy.x = 0.074. The benefits of this approach to calibration include (1) accuracy is traceable to a reference method or methodologic principle and, wherever available, to reference materials; (2) new calibrator values (SAVs) can be assigned whenever the reagent formulation changes to maintain accurate patient results; and (3) if matrix effects are present, they will not adversely influence accuracy because traceability is based on patient sample comparisons.

Bias↗
PubMed1995

Accuracy of diagnostic methods used for epidemiological studies of Helicobacter pylori.

Epidemiological studies involve groups of individuals, or whole populations, many or most of whom are not ill. Clinical investigation has an individual perspective and precise statements need to be made about the individual alone. Serological methods are most commonly used for population-based epidemiological studies. Non-invasive epidemiological methods, using breath tests or the study of saliva or urine, are increasing in use. All methods depend on accuracy in identifying presently infected or non-infected persons, and accuracy in defining a previously infected person. The performance of serological methods varies with the antigens chosen, the population from which reference sera are drawn, age, ethnicity, and homologous and heterologous infection rates in the population being studied. Much of the standardization of epidemiological assays has been done in adults, which means that for children there is still uncertainty concerning standards and cut-off values. Because of differences in strains of H. pylori in different geographical areas, antigen selection is important when geographical comparisons are made. The sensitivity and specificity of a test is not strongly affected by the prevalence of infection. However, as the prevalence rises in the tested populations, the reported positive predictive value rises, and the negative predictive value falls. Depending on the patient population studied, accuracy varies with changes in the prevalence, and its magnitude depends both on the sensitivity and specificity. Accuracy is therefore not a very useful measure. It is better to look at the sensitivity and specificity, and the prevalence in the study, where they are measured. An alternative to separating test results into two or three categories is to report likelihood ratios, which report the probability of a person with a particular result being truly positive compared with the probability of a person with that result being truly negative. A receiver operating characteristic (ROC) curve, which describes the effect of varying the cut-off value on the performance of a test, can be useful in comparing the performance of two or more different tests. The use of multiple tests to augment positive culture as a 'gold standard', has been aided by use of polymerase chain reactions and other molecular biological methods. However, this augmentation has its limitations, since each of the additional methods may produce false positives. For example, polymerase chain reactions can be falsely positive if instruments are contaminated. There are people with more than one strain of Helicobacter pylori in the stomach, and, without molecular biological efforts, or serological typing tests, the 'gold standard' does not deal with multiple infections.

Helicobacter Infections↗
PubMed1996

[Precision and accuracy of blood lipid analyses by a portable device (Cholestech-LDX)].

PURPOSE: To verify whether precision and accuracy of lipids analyses by a new portable device, Cholestech-lipid desktop analyzer (LDX), were in agreement with the guidelines of the National Cholesterol Education Program (NCEP). METHODS: Serum samples from 45 outpatients were collected for the determination of total Cholesterol (TC), HDL-cholesterol (HDL-C) and triglycerides (TG). These samples were analysed simultaneously by the Cholestech-LDX, and by the automatic enzymatic methods routinely used at the Heart Institute's laboratory. Precision was determined by repeating 20 times the evaluation of the same sample of venous blood. Accuracy was established confronting the values of the lipids variables obtained with Cholestech-LDX against the values determined by the automatic enzymatic routine. RESULTS: Accuracy for TC was 1.60% (NCEP < or = 3%), for HDL-C was -2.74% (NCEP < or = 6%) and for TG was 2.11% (NCEP < or = 5%). Precision for CT was 3.05% (NCEP < or = 3%), for HDL-C was 1.05% (NCEP < or = 6%) and for TG was 2.65% (NCEP < 5%). CONCLUSION: Precision and accuracy of lipids evaluation by the Cholestech-LDX are within the guidelines of the National Cholesterol Education Program. Therefore the cholestech-LDX seems to be a reliable alternative to the conventional biochemical routine, allowing population screenings.

Cholesterol↗
PubMed1997

Accuracy and precision of CT angiography in a model of carotid artery bifurcation stenosis.

PURPOSE: To determine optimal acquisition parameters and measurement techniques for CT angiography of the carotid bifurcation. METHODS: Anatomic phantoms were created in which the diameter of the carotid artery stenoses ranged from 15% to 95%. Initially, we compared the accuracy of stenosis determination obtained by using various values of section collimation and table pitch. Subsequently, applying the combination of collimation and pitch that yielded the greatest longitudinal coverage without degradation in accuracy, we compared the accuracy of measurements performed with various display algorithms, including axial, magnified axial, maximum intensity projection (MIP), and shaded surface display (SSD) images. Last, we determined the effect on accuracy of varying both window and level settings. The standard of reference for all measurements was considered to be caliper measurements made of the models at the time of their construction. RESULTS: CT angiography was highly accurate for determining the percentage of stenosis; the average difference between CT angiographic measurements and the standard of reference was less than 1% for all parameter combinations and measurement techniques. Precision varied among the measurement techniques. Magnified axial images provided more precise measurements than either the MIP or SSD images. Although there was a trend toward improved precision with the use of magnified versus unmagnified axial images and MIP versus SSD images, neither of these comparisons reached statistical significance. Systematic error was produced by changing the level setting from that halfway between the luminal density and vessel wall density. Random error was introduced by using window settings greater than zero. CONCLUSION: CT angiography was highly accurate and precise for determining percentage of stenosis. The highest precision was attained by using magnified axial images with the level halfway between luminal density and vessel wall density and with the window set to zero.

Carotid Arteries↗
PubMed1997

Placement of cardiac electrodes: written, simulated, and actual accuracy.

BACKGROUND: Research has shown that critical care nurses show low accuracy on written tests of placement of electrodes, yet it is unknown how this low accuracy translates into placement of electrodes on actual patients. OBJECTIVES: To determine if accuracy scores differ between three methods (written knowledge, simulated clinical practice, actual clinical practice) of evaluating placement of continuous ECG electrodes by a group of cardiac care nurses. METHODS: A standardized scoring diagram was used with three different methods of measuring the accuracy of 44 nurses who worked on a telemetry unit or medical ICU in placing continuous ECG electrodes. The three methods were (1) written knowledge--placement of stickers on a diagram of a torso, (2) simulated clinical practice--placement of electrodes on a human model, and (3) actual clinical practice--placement of electrodes on an assigned patient. RESULTS: For the total diagram score (maximum score = 11), no significant differences among groups were found. For the V1 subscale score (maximum score = 4), a significant difference among groups was found: Scheffé's test showed that the significant difference was between simulated and actual clinical practice. Percentages of nurses achieving the maximum, or accurate, score were 18% for written knowledge, 25% for simulated clinical practice, and 9% for actual clinical practice. CONCLUSIONS: Although total scores did not differ among groups, the mean scores indicate that placement of electrodes was not accurate by any method. This finding has implications for how electrode placement is taught to nurses and for the accountability of nurses for placement of electrodes on their patients.

Clinical Competence↗
PubMed1997

[The diagnostic accuracy and reproducibility of computed tomography with water distention and induced hypotonia in the preoperative staging of gastric tumors].

Thirty-five patients with gastric cancer were preoperatively examined with CT performed in the prone position. Patient preparation consisted in filling the stomach with tap water and i.v. glucagon administration. The CT images were independently reviewed by two radiologists, who staged each tumor according to the TNM classification. The results were compared with surgical and histological findings. The overall accuracy for T staging ranged 74-77%, overstaging 17-23%; understaging was 3%. Diagnostic sensitivity, specificity and accuracy for serosal invasion were 100%, 80%, 85% and 100%, 84% e 88%, respectively, for the two radiologists. The overall accuracy for N staging was 48% and 51% for the two observers, respectively. Considering N1 and N2 as a single group, accuracy ranged 68-77%. The interobserver agreement analyzed by the "K tests" was 80%, with a K index of 60%. CT performed with the patient in the prone position, after preparation with gastric wall hypotony and distension with water, is a valid technique permitting excellent depiction of the gastric wall and providing useful preoperative information to the surgeon.

Adult↗
PubMedDate not supplied

Accuracy and porosity of denture bases submitted to two polymerization cycles.

In this study was verified accuracy and porosity of denture bases submitted to double cycles of polymerization. Thirty-Six master casts were made in dental stone from the impression of the metal die. They were divided in three groups. Denture bases of conventional acrylic resin were made on the casts of the groups I (GI-control) and II (GII), polymerized in water bath during 9 hours at 73 degrees C, and specific resin for microwave polymerization were made on the casts of the group III (GIII) and cured at 500 W during 3 minutes. Accuracy was verified by the weight of a impression material put between the denture base and cast die under load of 2 Kg. Afterwards, all the denture bases were relined by addition method and those of the group I and II were relined with the same material and polymerization technic. The denture bases of the group II were filled with the same resin, however cured in microwave oven with 500 W during 3 minutes. Accuracy was reevaluated. The porosity was verified by the immersion of the specimens in a solution of permanent black ink and the pores were counted through a stereo light microscope under magnification of 6.3 x. The average and standard deviation obtained for accuracy before and after the relining were respectively: GI: 0.63 +/- 0.02 - 0.66 +/- 0.03; GII: 0.63 +/- 0.03 - 0.68 +/- 0.03: GIII: 0.58 +/- 0.02 - 0.80 +/- 0.05. There was a significant difference (p < 0.05 as tested by Tukey) only for the group III. The average and standard deviation for porosity before and after the relining were respectively: GI: 8.33 +/- 0.63 - 9.25 +/- 0.85; GII: 8.17 +/- 0.98 - 10.08 +/- 1.63: GIII: 5.41 +/- 0.78 - 6.58 +/- 1.02. There was a significant difference (p < 0.05) for the group III before relining. The conclusion is that after relining, the conventional resin cured by water bath or microwaves energy showed a better adaptation, and the highest number of pores.

Composite Resins↗
PubMed1995

The effect of the type and technique used for impression making on the accuracy of elastomeric impression materials.

The effect of the technique used for impression making on the accuracy of three types impression materials, (vinyl silicons, condensation silicons and polyether elastomers) was evaluated. Three main impression making techniques were used. Impressions were made for stainless steel master model. The impressions were poured after thirty minutes with improved stone into stone casts. Accuracy was assessed by comparing seven measurements of the master model to their corresponding on the stone case produced. A travelling microscope of 0.001 mm accuracy was used for measurements. The results of the study have shown that all elastomeric impression materials produced accurate impression but with significant difference among them. The polyether was more accurate than silicon impressions. The technique used for making the impression had more effect on the relative accuracy than the type of the material. Reference for the best technique for each type was concluded.

Acrylic Resins↗
PubMed1998

Pleural fluid: accuracy of computed tomography in differentiating exudates from transudates.

PURPOSE: To determine the accuracy of computed tomography in differentiating pleural exudates from transudates when reviewed subjectively by two experienced radiologists in a community hospital. METHODS: Computed tomography scans of 55 consecutive patients who had a thoracenteses within 10 days of the study were retrospectively reviewed independently by two experienced staff radiologists. They were asked to evaluate subjectively parietal pleural thickness (anterior, lateral, posterior), attenuation of extra-pleural fat, and categorize pleural fluid as loculated or free flowing. Radiographic findings were correlated with biochemical results of thoracentesis (Light's criteria) to assess the accuracy of computed tomography in differentiating pleural exudates from transudates. RESULTS: For the diagnosis of an exudate, pleural thickening alone had the best sensitivity and specificity (50%, 100%, respectively) with an accuracy of 55%. CONCLUSION: Subjective evaluations for increased pleural thickness have a high accuracy for diagnosing pleural exudates.

Exudates and Transudates↗
PubMed1998

[Locoregional staging of prostatic carcinoma: accuracy of magnetic resonance with endorectal coil in 75 patients treated with radical prostatectomy].

INTRODUCTION: We investigated the accuracy of MRI of the prostate with an endorectal surface coil in determing penetration of the prostatic capsule and invasion of seminal vescicles in prostate carcinoma. MATERIAL AND METHODS: Endorectal coil MRI (1 Tesla) was performed in 300 patients with biopsy-proved cancer. The PSA levels were always calculated and all the patients were examined with transrectal ultrasound. The imaging protocol included Turbo Spin Echo T2-weigthed (3900/150 TR/TE) axial and coronal images and T1-weigthed (650/15 TR/TE) axial images, 4 mm thick interleaved sections with .4 mm intersection gap, FOV 180 mm, 256 x 256 matrix (reconstruction 512). Seventy-five patients underwent radical prostatectomy and MR images were compared with pathologic findings of capsular penetration and invasion of seminal vescicles. The MR signs specific for capsular penetration were: deformation (irregularity) of capsular profile, capsular retraction with irregular margins, capsular interruption, obliteration of periprostatic adipose tissue, asymmetry of neurovascular bundles. RESULTS: MRI correctly depicted 37 of 45 pathologic stage T2 lesions and correctly depicted macroscopic capsular penetration (T3) in 18 of 23 cases. Microscopic capsular penetration was overestimated in all 7 cases. Sensitivity, specificity, accuracy, for microscopic and macroscopic capsular penetration were 60, 82, 73% respectively. Sensitivity, specificity, accuracy for macroscopic capsular penetration were 78, 82, 80% respectively. Sensitivity, specificity, accuracy for depiction of seminal vesicle involvment were 80, 100, 93%, respectively. The most reliable signs of capsular penetration were capsular interruption and invasion of periprostatic adipose tissue, while asymmetry of the neurovascular bundle was not seen. CONCLUSIONS: MRI provides accurate preoperative local staging. The two main limitations of MRI were the high rate of microscopic capsular penetration and the difficulty in detecting capsular penetration of tumor when the lesions are in the prostate apex. Prostate enlargement also made diagnosis more difficult.

Aged↗
PubMedDate not supplied

[Optimization and diagnostic accuracy of computerized tomography with tridimensional spiral technique in the study of craniostenosis].

INTRODUCTION: Conventional Computed Tomography (CT) with three-dimensional (3D) reconstructions is considered the most complete and accurate imaging modality to diagnose craniosynostosis. However, the introduction of Spiral CT (SCT) opened new possibilities for 3D studies of the skull in pediatric patients with craniosynostosis. The purpose of our study is two fold: first, to optimize the scanning and imaging parameters to obtain diagnostic images in a single spiral scan; second, to assess the diagnostic accuracy of such images in the identification of normal and abnormal cranial vault sutures. MATERIAL AND METHODS: Seventy-eight pediatric patients (age range: 1-35 months; mean: 11.8 months) with craniosynostosis were submitted to SCT of the head. The images were acquired with the following parameters: 3- and 5-mm nominal slice thickness, 5-6 mm/s table feed (pitch 1-2), 165 mAs and 120 kV. Two different algorithms and increases were used for image reconstructions. A first set of images was reconstructed with 2-mm increases and a soft tissue algorithm: these images were used for brain studies and for 3D reconstructions. A second set of slices was reconstructed with 5-mm increases and a bone algorithm to visualize the sutures of the axial plane. The 3D images were processed with the Shaded Surface Display software with threshold values ranging 120-150 HU. All images were acquired with a single spiral scan lasting less than 30 seconds. Two blinded radiologists analyzed the 3D and the planar images independently to evaluate the course and depth of each cranial suture. The sensitivity, specificity and diagnostic accuracy of both 3D and planar SCT images were evaluated. The frequency of artifacts (the Lego effect, boiled egg, pseudoforamina, movement, and chainsaw artifacts) and their influence on the final diagnosis were studied on 3D SCT images. RESULTS: The diagnostic accuracy rates of 3D SCT images, by suture, were: sagittal 90.7%, metopic 100%, left lamboid 90.9%, right lamboid 93.9%, left coronal 85.7%, right coronal 91.1%. The diagnostic accuracy rates of the axial images, by suture, were: sagittal 90.7%, metopic 95.5%, left lamboid 86.4%, right lamboid 90.9%, left coronal 83.7%, right coronal 91.1%. The interobserver agreement on 3D images was: sagittal 91.1%, metopic 100%, left lamboid 88.9%, right lamboid 91.1%, left coronal 88.9%, right coronal 84.4%. The Lego effect artifact was the most frequent one (82%) and affected image evaluation in 6.3% of cases. CONCLUSIONS: Our results prove that 3D SCT is a very accurate technique for identifying normal and abnormal sutures and presents many advantages over conventional 3D CT in the examination of pediatric patients with craniosynostosis. The quality of 3D SCT images was adequate and the artifacts did not affect the final diagnostic yield significantly.

Child, Preschool↗
PubMedDate not supplied

[Computerized tomography with lipiodol in hepatocarcinoma. Assessment of its diagnostic accuracy with anatomo-pathological control].

PURPOSE: To assess the diagnostic accuracy and predictive value of Lipiodol CT for hepatocellular carcinoma (HCC) before liver transplantation (OLT). MATERIAL AND METHODS: Seventy-eight cirrhotic patients awaiting OLT underwent Lipiodol CT to demonstrate the presence and extent of possible HCC. Radiologically, focal uptake areas with dense, homogeneous or "mosaic" iodized oil uptake were considered to be neoplastic nodules. All patients underwent OLT within 4 months of Lipiodol CT. Pathologic examination of the explanted livers was performed using the standard technique and, if necessary, with additional slices. Pathologic findings were compared with radiologic results to calculate the diagnostic accuracy and predictive value of Lipiodol CT in relation to both patients and lesions. RESULTS: Lipiodol CT depicted 61 focal areas of iodized oil uptake in 48 patients; pathologic examinations detected 57 HCC lesions in 42 patients (diameter .8 cm, mean 2.2 cm); agreement with radiologic diagnosis was found in 35 patients only. Patient by patient, Lipiodol CT had 83.3% sensitivity, 63.8% specificity, 74.3% diagnostic accuracy, 72.9% positive predictive value (PPV), and 76.6% negative predictive value. Lesion by lesion, Lipiodol CT showed overall sensitivity and PPV of 75.4-70.5%, 74-69.8% for "small" HCCs (diameter < or = 3 cm), and 72.9-71.1% for nodules < or = 2 cm in size. Eighteen uptake areas in 13 patients were diagnosed as HCC by Lipiodol CT but the finding was not confirmed at histology: 4 were hemangiomas and 14 corresponded to cirrhotic tissue without neoplastic foci. CONCLUSIONS: Our study, as the few others comparing radiologic results and pathologic findings of whole explanted liver, demonstrates that Lipiodol CT has relatively low diagnostic accuracy; particularly, specificity and PPV were limited by possible false positives, with HCC overstaging and mistakes in the indications/contraindications for OLT.

Adult↗
PubMed2004

A systematic review of the diagnostic accuracy of natriuretic peptides for heart failure.

BACKGROUND: The diagnosis of heart failure is difficult, with both overdiagnosis and underdiagnosis occurring commonly in practice. Natriuretic peptides have been proposed as a possible test for assisting diagnosis. We assessed the diagnostic accuracy of brain natriuretic peptide (BNP), including a comparison with atrial natriuretic peptide (ANP). METHODS: Electronic searches were conducted of MEDLINE and EMBASE from January 1994 to December 2002 and handsearches of reference lists of included studies. We included studies that assessed the diagnostic accuracy of BNP against echocardiographic or clinical criteria or that compared the diagnostic accuracy of BNP with ANP. Two reviewers assessed studies for inclusion and quality and extracted the relevant data. A meta-analysis was performed by pooling the diagnostic odds ratios for studies that used a common reference standard. RESULTS: Twenty studies were included. For the 8 studies (n = 4086) that measured BNP against the criterion of left ventricular ejection fraction of 40% or less (or equivalent), the pooled diagnostic odds ratio was 11.6 (95% confidence interval, 8.4-16.1). The pooled diagnostic odds ratio was greater, 30.9 (95% confidence interval, 27.0-35.4), in the 7 studies (n = 2374) that measured BNP against clinical criteria (generally a consensus view using all other clinical information). The diagnostic odds ratio was similar in studies conducted in general practice and in hospital settings. Three studies compared BNP with N-terminal-ANP, a precursor form of ANP, and pooling of the results of these studies showed BNP to be a more accurate marker of heart failure than NT-ANP. CONCLUSIONS: Brain natriuretic peptide is an accurate marker of heart failure. Use of a cutoff value of 15 pmol/L achieves high sensitivity, and BNP values below this exclude heart failure in patients in whom disease is suspected. As the diagnostic odds ratio for BNP is greater when assessed against clinical criteria than against left ejection fraction alone, BNP may also be detecting patients with "diastolic" heart failure.

Atrial Natriuretic Factor↗