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PubMed2006

Macrovesicular hepatic steatosis in living liver donors: use of CT for quantitative and qualitative assessment.

PURPOSE: To determine prospectively the diagnostic performance of unenhanced computed tomography (CT) in the assessment of macrovesicular steatosis in potential donors for living donor liver transplantation by using same-day biopsy as a reference standard. MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained. A total of 154 candidates, including 104 men (mean age, 30.2 years +/- 10.3 [standard deviation]) and 50 women (mean age, 31.8 years +/- 11.2), underwent same-day unenhanced CT and ultrasonography-guided liver biopsy. Histologic degree of macrovesicular steatosis was determined. Three liver attenuation indices were derived: liver-to-spleen attenuation ratio (CT(L)(/S)), difference between hepatic and splenic attenuation (CT(L)(-S)), and blood-free hepatic parenchymal attenuation (CT(LP)). Regression equations were used to quantitatively estimate the degree of macrovesicular steatosis. Limits of agreement between estimated macrovesicular steatosis and the reference standard were calculated. Receiver operating characteristic analyses were used to determine the performance of each index for qualitative diagnosis of macrovesicular steatosis of 30% or greater. The cutoff value that provided a balance between sensitivity and specificity and the highest cutoff value that yielded 100% specificity were determined. RESULTS: Limits of agreement were -14% to 14% for CT(L)(/S) and CT(L)(-S) and -13% to 13% for CT(LP). Performance in diagnosing macrovesicular steatosis of 30% or greater was not significantly different among indices (P > .05). Cutoff values of 0.9, -7, and 58 were determined for CT(L)(/S), CT(L)(-S), and CT(LP), respectively, and provided a balance between sensitivity and specificity. Cutoff values of 0.8, -9, and 42 were determined for CT(L)(/S), CT(L)(-S), and CT(LP), respectively, and yielded 100% specificity for all indices, with corresponding sensitivities of 82%, 82%, and 73% for CT(L)(/S), CT(L)(-S), and CT(LP), respectively. CONCLUSION: Diagnostic performance of unenhanced CT for quantitative assessment of macrovesicular steatosis is not clinically acceptable. Unenhanced CT, however, provides high performance in qualitative diagnosis of macrovesicular steatosis of 30% or greater.

Adult↗
PubMed2001

Caries inhibition in rats by a sodium fluoride, tripolyphosphate toothpaste with whitening and anti-tartar properties.

The anti-caries properties of a silica-based, sodium fluoride (NaF) toothpaste containing sodium tripolyphosphate (NaTPP) with tooth whitening and anti-tartar properties (Aquafresh Whitening), in specific pathogen-free Osborne-Mendel rats, were assessed in this study. A silica-based, fluoride-free placebo containing NaTPP, and a NaF-containing silica-based USP reference standard toothpaste were used as negative and positive control toothpastes, respectively. Sixty weanling rats were randomly distributed into groups of 20; all were inoculated with S. mutans 10449S, ate cariogenic diet 2000, and drank demineralized water ad libitum. Each toothpaste, packaged in coded tubes, was applied to the dentitions of the rats' teeth for one minute, twice daily on weekdays, and once daily on weekends and holidays. Both the NaF/NaTPP-containing and the NaF-containing USP standard toothpaste groups had lower total enamel caries scores (41 to 45%) than the group treated with the fluoride-free NaTPP-containing placebo. Similar dimensioned differences were evident both at smooth surface and sulcal enamel sites, and in dentinal sites. All were statistically significant at p < 0.001. There were no statistically significant differences at any tooth surface category site between the two fluoride-containing toothpastes' effects. It is thus apparent that Aquafresh Whitening has the anticaries benefit of a USP reference standard NaF toothpaste.

Analysis of Variance↗
PubMed2005

Effective and accurate screening for diabetic retinopathy using a 60 degree mydriatic fundus camera.

UNLABELLED: OBJECTIVES. To establish whether an experienced endocrinologist could screen accurately for diabetic retinopathy using mydriatic 60 degree fundus photographs compared with a reference standard, viz. the combined highest scores of two experienced ophthalmologists. DESIGN: Retrospective review of 60 degree colour transparency photographs taken over a 6-year period. Retinopathy was graded in a standardised way. SETTING: Patients attending the diabetic clinic at Johannesburg Hospital, South Africa. SUBJECTS: Fifteen hundred and seventeen patients (2446 eyes) formed the basis for the study. Patients were included if there was more than 50% readability of the fundus photographs. OUTCOME MEASURES: Outcome measures were prevalence of any retinopathy and presence of referable (severe) retinopathy. Interobserver agreement was measured using the kappa statistic, and sensitivity and specificity of the screener were evaluated. RESULTS: The prevalence of retinopathy at the clinic was approximately 30%, but only about 12% was severe enough to warrant referral to the ophthalmology outpatient department. The endocrinologist was very accurate in determining cases requiring referral; there was 97% agreement with the reference standard, viz. the combined highest score of two experienced ophthalmologists (gold standard). Correlation on the determination of any retinopathy was less accurate (80% agreement), mostly owing to the endocrinologist reporting more isolated microaneurysms than the ophthalmologists. The screening method used gave a sensitivity of 83% and specificity of 99% which are within recommended standards. CONCLUSIONS: The screening strategy using a mydriatic fundus camera at the diabetic clinic was found to be effective and accurate and greatly reduced the number of possible referrals to the ophthalmology outpatient department.

Adult↗
PubMed2006

Agreement and validity of pharmacy data versus self-report for use of osteoporosis medications among chronic glucocorticoid users.

PURPOSE: Pharmacy and linked claims databases are commonly used to determine medication receipt as a measure of quality of care. However, these data sources have not been previously compared with self-reported data for receipt of medications used for glucocorticoid-induced osteoporosis (GIOP). METHODS: Using databases from a national managed care organization (MCO), we identified 6282 chronic glucocorticoid users (60+ days in 18 months). We compared self-reported current use of alendronate, risedronate, calcitonin, and raloxifene (reference standard) to different intervals of preceding pharmacy data to determine agreement, sensitivity, specificity, and positive and negative predictive values of the pharmacy data. RESULTS: Survey respondents (n = 2363) were mean +/- SD age 53 +/- 14 years old, 70% women, and 78% Caucasian. Agreement between self-reported and pharmacy data ranged from Kappa = 0.64 (95%CI 0.53-0.75) (calcitonin) to 0.80 (0.76-0.84) (alendronate). The positive predictive value of a filled prescription in the pharmacy database in the prior 6 months exceeded 90% compared to the reference standard of self-reported current bisphosphonate use. However, the 6-month interval of pharmacy data failed to capture >25% of self-reported current bisphosphonate users. The optimal interval of pharmacy data to distinguish between current and past bisphosphonate users was 120-180 days. CONCLUSIONS: Among chronic glucocorticoid users enrolled in managed care, underreporting of current osteoporosis medication use was uncommon, and agreement between self-report and pharmacy data was high. Use of pharmacy data alone is unlikely to underestimate quality of osteoporosis care, but different intervals of pharmacy data have important implications on the ability to identify current users of osteoporosis medications.

Alendronate↗
PubMed2006

Iron bioavailability from fortified fluid milk and petit suisse cheese determined by the prophylactic-preventive method.

In this research, we measure the iron bioavailability of micronized ferric orthophosphate when it is used to fortify low-fat fluid milk enriched with calcium and petit suisse cheese using the prophylactic-preventive method in rats. Four groups of male weaned rats received a basal diet (control diet; 6.5 ppm Fe), a reference standard diet (SO4Fe; 18.2 ppm Fe), a basal diet using iron-fortified fluid milk as the iron source (milk diet; Fe ppm 17.9), and a basal diet using iron-fortified petit suisse cheese as the iron source (cheese diet; 18.0 ppm Fe) for 22 d. The iron bioavailability of the different sources was calculated as the ratio between the mass of iron incorporated into hemoglobin during the experiment and the total iron intake per animal. The relative biological values with regard to the reference standard (RBV%) were 61% and 69% for the milk and cheese diet, respectively. These results show that according to this method, the iron bioavailability in both fortified foods can be considered as medium bioavailability rates.

Animals↗
PubMed2005

Measurement of input functions in rodents: challenges and solutions.

INTRODUCTION: Tracer kinetic modeling used in conjunction with positron emission tomography (PET) is an excellent tool for the noninvasive quantification of physiological, biological and molecular processes and their alterations due to disease. Currently, complex multi-compartment modeling approaches are being applied in a variety of clinical studies to determine myocardial perfusion, viability and glucose utilization as well as fatty acid metabolism and oxidation in the normal and diseased heart. These kinetic models require two key measurements of tracer activity over time, tracer activity in arterial blood (input function) and its corresponding activity in the organ of interest. The alteration in the time course of tracer activity as it travels from blood to the organ of interest describes the kinetics of the tracer. To be able to implement these approaches in rodent models of disease using small-animal PET (microPET), it is imperative that the input function is measured accurately. METHODS: The blood input functions in rodent experiments were obtained by (1) direct blood sampling, (2) direct measurement of blood activity by a beta-detecting probe that counts the activity in the blood, (3) an arterial-venous bypass (A/V shunt), (4) factor analysis of dynamic structures from dynamic PET images and (5) measurement from region-of-interest (ROI) analysis of dynamic PET images. Direct blood sampling was used as the reference standard to which the results of the other techniques were compared. RESULTS: Beta probes are difficult to operate and may not provide accurate blood input functions unless they are used intravenously, which requires complicated microsurgery. A similar limitation applies to the A/V shunt. Factor analysis successfully extracts the blood input function for mice and rats. The ROI-based method is less accurate due to limited image resolution of the PET system, which results in severe partial volume effect and spillover from myocardium. CONCLUSION: The current reference standard, direct blood sampling, is more invasive and has limited temporal resolution. With current imaging technology, image-based extraction of blood input functions is possible by factor analysis, while forthcoming technological developments are likely to allow extraction of input function directly from the images. These techniques will reduce the level of complexity and invasiveness for animal experiments and are likely to be used more widely in the future.

Animals↗
PubMed2005

Identification of relevant ICF categories for indication, intervention planning and evaluation of health resort programs: a Delphi exercise.

Health resort programs have a long tradition, mainly in European countries and Japan. They rely on local resources and the physical environment, physical medicine interventions and traditional medicine to optimise functioning and health. Arguably because of the long tradition, there is only a limited number of high-quality studies that examine the effectiveness of health resort programs. Specific challenges to the evaluation of health resort programs are to randomise the holistic approach with a varying number of specific interventions but also the reliance on the effect of the physical environment. Reference standards for the planning and reporting of health resort studies would be highly beneficial. With the International Classification of Functioning Disability and Health (ICF), we now have such a standard that allows us to describe body functions and structures, activities and participation and interaction with environmental factors. A major challenge when applying the ICF in practice is its length. Therefore, the objective of this project was to identify the ICF categories most relevant for health resort programs. We conducted a consensus-building, three-round, e-mail survey using the Delphi technique. Based on the consensus of the experts, it was possible to come up with an ICF Core Set that can serve as reference standards for the indication, intervention planning and evaluation of health resort programs. This preliminary ICF Core Set should be tested in different regions and in subsets of health resort visitors with varying conditions.

Activities of Daily Living↗
PubMed2000

Ethnic differences in the growth of low-birthweight infants.

Differences in growth were investigated among ethnic groups in low-birthweight babies (< 2500 g or < 32 weeks gestation) at birth and at 2-3 years. This prospective study was based on data for all 3091 low-birthweight live births in the South East Thames Region, UK, over a 1-year period, surviving to discharge from hospital. Weights were recorded at birth and at 2-3 years for 998 babies, and head circumferences for 859. These were compared with the UK 1990 reference standards. Ethnic differences were adjusted for parity, multiple birth, smoking and alcohol during pregnancy, mother's height, weight and age, marital status, partner's support and social class. At 2-3 years, there was substantial average catch-up growth only for the weight of infants of > or = 32 weeks' gestation. Babies < 32 weeks gestation had fallen behind. Head circumferences had failed to keep up or had fallen behind for both groups. The ethnic groups had similar birthweight standard deviation scores (SDS). At 2-3 years, Black babies of < 32 weeks' gestation had gained in weight and head circumference compared with White babies (adjusted difference in weight SDS: 0.71, [95% CI 0.28, 1.13]). Asian babies of at least 32 weeks' gestation had smaller heads than White, a difference that increased with time. It was concluded that ethnic differences in the growth of low-birthweight infants are related to gestational age. Although most of the babies born at < 28 weeks' gestation were close to their birthweight reference standards, only the Black infants had maintained their position at 2-3 years. Black infants, particularly when born preterm, tend to put on more weight than White.

Black or African American↗
PubMed2005

The Wells rule does not adequately rule out deep venous thrombosis in primary care patients.

BACKGROUND: Using data from secondary care outpatients, Wells and colleagues developed a diagnostic rule to estimate the probability of the presence of deep venous thrombosis (DVT). The accuracy of the Wells rule has not been properly validated for use in primary care patients in whom DVT is suspected. OBJECTIVE: To validate the diagnostic accuracy of the Wells rule, with and without D-dimer testing, in a primary care setting. DESIGN: Cross-sectional study with prospective data collection from 1 January 2002 to 1 March 2003. SETTING: 110 primary care practices in a circumscribed geographic region in The Netherlands. PARTICIPANTS: 1295 consecutive patients who consulted their primary care physician about symptoms suggestive of DVT. MEASUREMENTS: All patients underwent history-taking and physical examination to calculate the Wells rule score, and D-dimer testing. Repeated leg ultrasonography was the reference standard to determine the true presence or absence of DVT. RESULTS: In the primary care setting, 12.0% of patients in the low-risk group had DVT; the original study by Wells and colleagues reported a rate of 3% among such patients. When combined with negative results on a D-dimer test, the Wells rule yielded a prevalence of DVT of 2.9% in the lowest-risk group, whereas the prevalence was 0.9% in the original study. LIMITATIONS: Patients with previous DVT were included, and the diagnostic reference standard was different from that used in Wells and colleagues' original study. CONCLUSION: The Wells rule, alone or in combination with D-dimer testing, does not guarantee accurate estimation of risk in primary care patients in whom DVT is suspected.

Adult↗
PubMed1986

Flow cytometric evaluation of proliferative activity and ploidy in myelodysplastic syndromes and acute leukemias.

Propidium iodide (PI) DNA distribution of bone marrow (BM) cells was studied by flow cytometry (FCM) in 36 patients without hematologic or malignant disease (normal BM) and in 172 patients with anemias (36 pts), myelodysplastic syndromes (MDS) (33 pts) and acute leukemia (AL) at diagnosis (60 pts), remission (24 pts) and relapse (19 pts). White blood cells from normal male subjects were used as an external diploid reference standard (median CV = 3.8). Patients with normal BM, anemias, MDS and acute leukemia at diagnosis had tritiated thymidine labeling index (LI) and most with MDS and AL had also evaluable cytogenetics performed on the same BM sample used for FCM. In normal BM, median aliquot of cells with PI-DNA content intermediate between the diploid and the tetraploid value (2n-4n cells %) was 15.7. The ratio between the fluorescence intensity of the G0/1 peak of normal BM cells and the fluorescence intensity of the G0/1 peak of the reference standard (FI ratio) ranged from 93 to 1.05 (mean +/- 2SD). The 2n-4n cell % was higher than normal in anemias (p less than .001), lower in leukemias (p less than .001) and widely scattered in MDS. A linear correlation was found between 2n-4n cell % and LI, with 2n-4n cell % value higher than LI. The FI ratio was lower than normal in anemias (p less than .05), higher in AL with normal cytogenetics (p less than .02) and broadly scattered in MDS with normal cytogenetics. From our experience, PI-DNA-FCM is a simple and adequate method to evaluate proliferative activity in hematologic diseases. Nevertheless, caution must be taken in attributing small changes in FI ratio to aneuploidy, since they are found in anemias and in MDS and AL with normal cytogenetics, possibly due to differences in PI uptake by different cell types.

Acute Disease↗
PubMed2001

Malaria rapid diagnostic devices: performance characteristics of the ParaSight F device determined in a multisite field study.

Microscopic detection of parasites has been the reference standard for malaria diagnosis for decades. However, difficulty in maintaining required technical skills and infrastructure has spurred the development of several nonmicroscopic malaria rapid diagnostic devices based on the detection of malaria parasite antigen in whole blood. The ParaSight F test is one such device. It detects the presence of Plasmodium falciparum-specific histidine-rich protein 2 by using an antigen-capture immunochromatographic strip format. The present study was conducted at outpatient malaria clinics in Iquitos, Peru, and Maesod, Thailand. Duplicate, blinded, expert microscopy was employed as the reference standard for evaluating device performance. Of 2,988 eligible patients, microscopy showed that 547 (18%) had P. falciparum, 658 (22%) had P. vivax, 2 (0.07%) had P. malariae, and 1,750 (59%) were negative for Plasmodium. Mixed infections (P. falciparum and P. vivax) were identified in 31 patients (1%). The overall sensitivity of ParaSight F for P. falciparum was 95%. When stratified by magnitude of parasitemia (no. of asexual parasites per microliter of whole blood), sensitivities were 83% (>0 to 500 parasites/microl), 87% (501 to 1,000/microl), 98% (1,001 to 5,000/microl), and 98% (>5,000/microl). Device specificity was 86%.

Animals↗
PubMed2003

Sublimation characterization and vapor pressure estimation of an HIV nonnucleoside reverse transcriptase inhibitor using thermogravimetric analysis.

The purpose of this research is to investigate the sublimation process of DPC 963, a second-generation nonnucleoside reverse transcriptase inhibitor for HIV-1 retrovirus, and to better understand the effect of sublimation during active pharmaceutical ingredient (API) manufacture and formulation development, especially the drying processes. Sublimation of DPC 963 at 150 degrees C and above was determined by thermogravimetric analysis-Fourier transform infrared (TGA-FTIR). The rates of sublimation at different temperatures were measured using isothermal TGA. Condensed material was collected and analyzed by differential scanning calorimetry (DSC), x-ray powder diffraction (XRPD), and infrared (IR) spectrometry. Benzoic acid was used as a reference standard to derive a linear logarithmic relationship between sublimation/evaporation rate and vapor pressure specific to the TGA system used in this study. Sublimation and evaporation of DPC 963 were found to follow apparent zero-order kinetics. Using the Eyring equation, the enthalpy and entropy of the sublimation and evaporation processes were obtained. The enthalpies of sublimation and evaporation were found to be 29 and 22 kcal/mol, respectively. The condensed material from the vapor phase was found to exist in 2 physical forms, amorphous and crystalline. Using benzoic acid as a reference standard, vapor pressure of DPC 963 at different temperatures was calculated using the linear logarithmic relationship obtained. DPC 963 undergoes sublimation at appreciable rates at 150 degrees C and above but this is not likely to pose a serious issue during the manufacturing process. Vapor pressure estimation using thermogravimetric analysis provided sufficient accuracy to be used as a fast, simple, and safe alternative to the traditional methods of vapor pressure determination.

Chemical Phenomena↗
PubMed2006

Stage T1 non-small cell lung cancer: preoperative mediastinal nodal staging with integrated FDG PET/CT--a prospective study.

PURPOSE: To prospectively evaluate the sensitivity and specificity of integrated fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) and computed tomography (CT) (PET/CT) for the preoperative diagnosis of mediastinal nodal metastasis in stage T1 non-small cell lung cancer (NSCLC), with surgical and histologic results as reference standards. MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained. From June 2003 to February 2005, 150 patients (89 men and 61 women; mean age, 59 years) with stage T1 NSCLC at stand-alone CT underwent integrated PET/CT and surgical staging. Two observers (one radiologist and one nuclear medicine physician) evaluated prospectively and in consensus the mediastinal nodes by analyzing both PET (functional) and CT (anatomic) images. Nodal stages were determined by using the American Joint Committee on Cancer staging system and surgical and histologic findings as the reference standard. Statistical evaluation of malignant lymph nodes was performed on per-nodal-station and per-person bases. RESULTS: A total of 568 mediastinal nodal stations were evaluated. Nodes were positive for malignancy in 34 (23%) of 150 patients and 55 (10%) of 568 nodal stations. For depiction of malignant nodes, the respective sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of integrated PET/CT were 42% (23 of 55), 100% (513 of 513), 100% (23 of 23), 94% (513 of 545), and 94% (536 of 568) on per-nodal-station basis and 47% (16 of 34), 100% (116 of 116), 100% (16 of 16), 87% (116 of 134), and 88% (132 of 150) on a per-patient basis. CONCLUSION: Integrated FDG PET/CT provides high specificity and positive predictive value of mediastinal nodal staging in stage T1 NSCLC, although the sensitivity is low.

Adult↗
PubMed1992

[Normal values of the immunoglobulin G subclasses in an adult population. Importance in a study of their deficiency].

BACKGROUND: Quantification of the IgG subclasses (IgGS) requires highly sensitive and specific techniques since their molecular structure is more than 95% homologous. At present, ELISA and RIA are the most appropriate techniques; although the variability of these techniques and the possible ethnic differences in serum levels of IgGS oblige each laboratory to establish its own reference values in a normal population, a condition necessary for defining IgGS deficits. METHODS: In the present study the normal serum values of IgGS in 100 healthy individuals were established. Serum quantification of the IgGS was performed by optimization of the indirect ELISA technique using AcMo and OMS reference standards H00-03 for the 4 subclasses, calibrated vs the OMS WHO 67/97 pattern. RESULTS: Normal values observed for IgG1 were 2.61-10.81 g/l; IgG2, 1.12-4.08 g/l; IgG3, 0.22-2.88 g/l; and IgG4, 0.05-1.56 g/l obtained as of the mean +/- 2 SD for IgG1 and as of the extent of the values of the remaining 3 subclasses by following a non-normal distribution. The sensitivity of the technique was 0.05 g/l with mean intra and inter analysis coefficients of 3.5% and 10.7% respectively. The correlation between total IgG and the sum of the 4 subclasses showed a r = 0.894 (p less than 0.01). CONCLUSIONS: The ELISA technique using AcMo and OMS reference standards is an adequate method for the quantification of the IgG subclasses. However, given the variability of this technique and in order to avoid error, strict working conditions, such as the use of control sera at 2 concentration levels, should be observed for the 4 IgGS in each of the analytic series and each series should also be duplicated.

Adult↗
PubMed2003

Verification of caries inhibition by a tartar control toothpaste.

OBJECTIVE: The anticaries properties of a silica-based, sodium fluoride (NaF) toothpaste containing tetrapotassium pyrophosphate (PPi) with anti-tartar properties (Aquafresh All Tartar Control) were assessed in specific pathogen-free Osborne-Mendel rats. METHODOLOGY: The dentifrice was compared to a silica-based, fluoride-free control toothpaste that contained PPi but no NaF, termed a "Placebo" (negative control), and a NaF-containing silica-based USP reference standard toothpaste which was used as a positive fluoride control toothpaste. Sixty weanling rats were randomly distributed into groups of 20; all were inoculated with S. mutans 10449S, ate cariogenic diet 2000, and drank demineralized water, ad libitum. Each toothpaste, contained in coded tubes, was applied to the dentitions of rats' teeth for one minute, twice daily on weekdays and once daily on weekends and holidays. There was no difference in weight gains or in recoveries of the S. mutans inoculant from tooth swabs among the groups at either the 24- or 38-day post-inoculation recovery date. After euthanasia at 42 days and defleshing, heads were randomly coded and scored blindly for carious lesions according to Keyes/Larson methods. Only after scoring was completed were the random codes broken to enable statistical analyses. Only after statistical analyses were completed and the data reported to sponsor were the identities of the test items revealed. RESULTS: Both the NaF/PPi-containing and the NaF-containing USP standard toothpaste groups had lower total enamel caries scores (29.8 to 30.6%, respectively) than the group treated with the fluoride-free PPi-containing control. Similar-dimensioned differences were evident both at smooth surface and sulcal enamel sites and in dentinal sites. All were statistically significant at p < 0.001. There were no statistically significant differences at any tooth surface category site between the two fluoride-containing toothpastes' effects. CONCLUSION: It is thus apparent that Aquafresh All Tartar Control, an anti-tartar NaF toothpaste, retains the anticaries benefit of a USP reference standard NaF toothpaste in vivo.

Animals↗
PubMed2005

Colorectal polyps: detection with low-dose multi-detector row helical CT colonography versus two sequential colonoscopies.

PURPOSE: To prospectively evaluate the diagnostic accuracy of low-radiation-dose computed tomographic (CT) colonography for detection of colorectal polyps by using two sequential colonoscopies, with the second colonoscopy as the reference standard. MATERIALS AND METHODS: The study was local ethics committee approved, and all patients gave written informed consent. Colonographic images were acquired by using a low-dose multi-detector row CT protocol (effective milliampere-second setting, 10 mAs). Three observers interpreted the CT colonographic data separately and independently by using a two-dimensional technique. Initial conventional colonoscopy was performed by an endoscopist unaware of the CT colonographic findings. Second colonoscopy performed within 2 weeks by a colonoscopist aware of both the CT colonographic and the initial colonoscopic findings served as the reference standard. The sensitivities of CT colonography and initial colonoscopy were calculated on a per-polyp and a per-patient basis. Specificities and positive and negative predictive values also were calculated on a per-patient basis. RESULTS: Eighty-eight patients underwent CT colonography and initial conventional colonoscopy on the same day. Per-polyp sensitivities were 62% and 83% for CT colonography and initial colonoscopy, respectively. Sensitivities for detection of polyps 6 mm in diameter or larger were 86% and 84% for CT colonography and initial colonoscopy, respectively. Initial colonoscopy failed to depict 16 polyps, six of which were correctly detected with CT colonography. For identification of patients with polyps 6 mm in diameter or larger, CT colonography and initial colonoscopy, respectively, had sensitivities of 84% and 90%, specificities of 82% and 100%, positive predictive values of 70% and 100%, and negative predictive values of 91% and 95%. CONCLUSION: Low-dose CT colonography compares favorably with colonoscopy for detection of colorectal polyps 6 mm in diameter or larger, with markedly decreased performance for detection of polyps 5 mm in diameter or smaller.

Aged↗
PubMed2000

Digital radiography versus conventional radiography in chest imaging: diagnostic performance of a large-area silicon flat-panel detector in a clinical CT-controlled study.

OBJECTIVE: The objective of this study was to compare the diagnostic performance of a digital large-area silicon flat-panel detector with that of a conventional screen-film system in clinical chest imaging using abnormal findings documented by CT as the reference standard. SUBJECTS AND METHODS: Eighty patients (46 men and 34 women; age range,18-91 years; mean age, 63 years) who underwent CT of the chest were examined with the new digital radiography system, which is based on a 43 x 43 cm silicon flat-panel detector, and with a conventional screen-film system, which is used routinely in clinical practice. Posteroanterior and lateral radiographs were obtained. Four radiologists analyzed the digital and conventional images separately for chest abnormalities and rated the images using a five-level scale of confidence; CT was used as the reference standard. Diagnostic value was assessed using receiver operating characteristic curves for each abnormality. RESULTS: No significant differences were found between the area under the receiver operating characteristic curve of the digital and that of the conventional radiography method for almost all investigated criteria. The only exception was mediastinal abnormalities, for which the digital method provided better results than the conventional method (p < 0.05). CONCLUSION: The diagnostic performance of the new large-area silicon flat-panel detector is equivalent or superior to that of the conventional screen-film system for clinical chest imaging and can replace conventional radiography systems. This new technology offers transmission and storage possibilities inherent to digital radiology that would facilitate daily practice and reduce the initial high costs in the long-term.

Adolescent↗
PubMed2004

Usefulness and validity of diagnostic nasogastric aspiration in patients without hematemesis.

STUDY OBJECTIVE: We estimate the test characteristics of nasogastric aspiration to diagnose upper gastrointestinal tract hemorrhage in patients without hematemesis. METHODS: In this retrospective cohort study, medical records from patients admitted to 2 urban hospitals between 1997 and 2002 for gastrointestinal tract bleeding without hematemesis were reviewed. Positive nasogastric aspiration results were classified by the severity of hemorrhage, and negative results were classified by the presence or absence of bile. The reference standard for nasogastric aspiration was the source of bleeding-upper versus non--upper gastrointestinal tract--from the hospital discharge summary. Confidence intervals (CIs) for proportions and likelihood ratios (LRs) were calculated. RESULTS: Of 333 eligible patients, 235 were offered nasogastric aspiration, and 220 accepted the test. Results of 220 attempts were distributed as follows: negative, 158 (72%), including 9 (4%) with bile; nasogastric aspiration aborted, 13 (6%); and positive, 49 (23%), including 4 (2%) that were strongly positive (> or =450 mL red blood). Test characteristics of nasogastric aspiration to detect upper gastrointestinal tract bleeding in 213 patients with a reference standard diagnosis were as follows: sensitivity 42% (95% CI 32% to 51%), specificity 91% (95% CI 83% to 95%), negative predictive value 64% (95% CI 56% to 71%), and positive predictive value 92% (95% CI 79% to 97%). The nasogastric aspiration accurately predicted the source of bleeding in 66% of patients (95% CI 59% to 72%). The likelihood ratio of a positive nasogastric aspiration was 11 (95% CI 4 to 30), and the likelihood ratio of a negative nasogastric aspiration was 0.6 (95% CI 0.5 to 0.7). CONCLUSION: In patients without hematemesis, a positive nasogastric aspiration, seen in 23%, indicates probable upper gastrointestinal tract bleeding (LR+ 11), but a negative nasogastric aspiration, seen in 72%, provides little information (LR- 0.6).

Aged↗