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PubMed2005

The association between operator confidence and accuracy of ultrasonography performed by novice emergency physicians.

The variable accuracy of emergency department (ED) ultrasound described in the literature has limited its utility as the sole imaging modality in critical decision making. Although ultrasound accuracy is highly dependent upon the technical abilities of the operator and conditions unique to each patient, no previous study of ED ultrasound has included estimates of operator confidence. This prospective observational study explores the association between operator confidence and the accuracy of ED ultrasound. Ultrasound was not performed in our ED until a formal training module was instituted. Patients were enrolled prospectively for the first year following the training module if they underwent one of the following ultrasound studies: abdominal examination for intraperitoneal fluid, right upper quadrant examination for gallstones, renal examination for hydronephrosis, pelvic examination for intrauterine pregnancy, abdominal examination for aorta diameter > 3 cm, or cardiac examination for pericardial fluid. In addition, formal ultrasound, computed tomography, magnetic resonance imaging, or an invasive procedure was required as a "gold standard" for each patient. Operators recorded their interpretation of the ED ultrasound and rated their confidence with the analysis before the formal imaging study or procedure. Test performance characteristics for each examination type and for all studies together were determined. The association between operator confidence and accuracy was explored using logistic regression and by determining test performance characteristics with patients stratified by confidence value. A total of 276 ED ultrasound studies were included. There were no significant differences in accuracy between ED attendings and residents. Overall accuracy, sensitivity, specificity, LR+, and LR- were 90%, 92%, 86%, 6.8, and 0.09, respectively. With confidence scores of 9 or 10 (n = 113), these values improved to 96%, 99%, 90%, 9.6, and 0.01, respectively. Logistic regression revealed an association between confidence and ED ultrasound accuracy (p < 0.001). It is concluded that a significant association exists between operator confidence and the accuracy of ED ultrasound. High confidence values are associated with clinically useful test performance characteristics.

Abdomen↗
PubMed2002

Cognitive research enhances accuracy of food frequency questionnaire reports: results of an experimental validation study.

OBJECTIVE: To test whether changing a food frequency questionnaire (FFQ) on the basis of cognitive theory and testing results in greater accuracy. Accuracy was examined for 4 design issues: a) Grouping: asking about foods in a single vs multiple separate questions; b) different forms of a food: asking consumption frequency of each form of a food (eg, skim, 2%, whole milk) vs a nesting approach--asking frequency of the main food (eg, milk) and proportion of times each form was consumed; c) additions (eg, sugar to coffee): asking independent of the main food vs nested under the main foods; d) units: asking frequency and portion size vs frequency of units (eg, cups of coffee). DESIGN: Participants in two randomly assigned groups completed 30 consecutive daily food reports (DFRs), followed by 1 of 2 FFQs that asked about foods consumed in the past month. One was a new, cognitively-based National Cancer Institute (NCI) Diet History Questionnaire; the other was the 1992 NCI-Block Health Habits and History Questionnaire. SUBJECTS/SETTING: 623 participants, age range 25 to 70 years, from metropolitan Washington, DC. Statistical analyses performed Accuracy was assessed by comparing DFR and FFQ responses using categorical (percent agreement) and continuous (rank order correlation, discrepancy scores) agreement statistics. RESULTS: Grouping: accuracy was greater using separate questions. Different forms of food: accuracy was greater using nesting. Additions: neither approach was consistently superior; accuracy of the addition report was affected by accuracy of the main food report. Units: both approaches were similarly accurate. CONCLUSIONS: Accuracy of FFQ reporting can be improved by restructuring questions based on cognitive theory and testing.

Adult↗
PubMed1990

The effect of baseline electrocardiographic abnormalities on the diagnostic accuracy of exercise-induced ST segment changes.

Although exercise-induced ST segment depression is thought to be unreliable marker of myocardial ischemia in the presence of resting electrocardiographic changes, this conclusion is based on limited and disparate data from studies often lacking acceptable measures of ischemia. To determine the diagnostic accuracy of the ST segment response in a blinded prospective protocol, we compared ST deviation to thallium201 SPECT scintigraphy in 95 patients during exercise. Diagnostic accuracy was poor in the 95 patients with resting abnormalities: left bundle branch block (LBBB) = 70%, complete right bundle branch block (cRBBB) = 75%, incomplete right bundle branch block (incRBBB) = 79%, intraventricular conduction delay (IVCD) = 44%, left ventricular hypertrophy (LVH) = 59%, digitalis = 53%, compared with a diagnostic accuracy of 90% in 29 patients without resting changes. There were 20 false negative and 17 false positive ST segment responses. The extent and direction of resting ST deviation varied substantially and had no influence on diagnostic accuracy. The extent of change in ST deviation with exercise required for a positive response did not alter diagnostic accuracy: -1.0 mm = 61%, -1.5 mm = 63%, and -2.0 = 61%. While the location of regional ischemia did not influence the accuracy of ST segment analysis, a QRS duration less than 120 msec did improve diagnostic accuracy. Our data confirm that ST segment analysis with exercise testing is not reliable in patients with resting electrocardiographic abnormalities and demonstrates that accuracy is not improved by adjusting for either resting or exercise-induced ST segment changes or for location of the ischemic region.

Aged↗
PubMed1994

Combined time-domain and spectral turbulence analysis of the signal-averaged ECG improves its predictive accuracy in postinfarction patients.

The predictive accuracy of time-domain (TD) late potential analysis of the signal-averaged electrocardiogram in postmyocardial infarction (MI) is limited by the high incidence of false positives in inferior MI. However, frequency-domain spectral turbulence (ST) analysis suffers from a high incidence of false positives, especially in anterior MI. A prospective study was conducted of 262 patients with acute MI to investigate the hypothesis that combined TD and ST analyses of the signal-averaged electrocardiogram could improve its predictive accuracy for serious arrhythmic events in the post-MI period. Abnormal TD criteria were RMS40 less than 25 microV at 25 Hz plus RMS40 less than 16 microV at 40 Hz, and abnormal ST criteria were a turbulence score of 3 or 4. Seventeen patients had arrhythmic events during 10.5 +/- 2.4 months of follow-up evaluation (13 sudden cardiac death judged to be due to arrhythmia and 4 nonfatal sustained ventricular tachycardia). The total predictive accuracy of combined TD and ST (92%) was higher than TD (87%), whereas ST had the lowest total predictive accuracy of 78%. The negative predictive accuracy of all three analyses was high (96-97%). However, the positive predictive accuracy of TD (28%) was higher than ST (14%). Combined TD and ST significantly improved the positive predictive accuracy of the test to 35% in the total group and to 40% in patients with first anterior or inferior MI. The best results were obtained in patients with first anterior MI, where the positive predictive accuracy of combined analysis was 50%.

Arrhythmias, Cardiac↗
PubMed1996

Mutations in yeast ribosomal proteins S28 and S4 affect the accuracy of translation and alter the sensitivity of the ribosomes to paromomycin.

Ribosomal proteins S12, S5 and S4 of Escherichia coli are essential for the control of translational accuracy. Their yeast equivalents, i.e., S28, S4 and S13, have also been implicated in this process. Using a poly(U)-dependent cell-free translation system, we determined the accuracy of translation and the sensitivity to antibiotic paromomycin of yeast ribosomes carrying mutant ribosomal proteins S28 and/or S4. Our results confirm by quantitative biochemical methods previous genetic data showing that proteins S28 and S4 are involved in the decoding activity of the ribosome and interact to control translational accuracy. We find that the suppressor mutation SUP44 in yeast S4, decreased the accuracy of translation. To examine the effect of mutant S28, we disrupted RPS28B and introduced in RPS28A the same substitutions that cause hyperaccurate translation or antibiotic resistance in bacteria. Three of these substitutions (Lys-62-->Asn, Thr or Gln) similarly increased translational accuracy in vitro or antibiotic resistance. In the presence of the SUP44 mutation, these substitutions partially reversed the decrease of translational accuracy caused by SUP44. However, the Lys-62-->Arg substitution decreased translational accuracy and caused antibiotic sensitivity both in nonsuppressor and in SUP44 haploids. These results establish the role of Lys-62 of S28 in optimizing translational accuracy and provide a more precise view of the functional role of two important ribosomal proteins.

Anti-Bacterial Agents↗
PubMed1996

Lower diagnostic accuracy of thallium-201 SPECT myocardial perfusion imaging in women: an effect of smaller chamber size.

OBJECTIVES: We attempted to formally compare the diagnostic accuracy of thallium-201 single-photon emission computed tomographic (SPECT) myocardial perfusion imaging in men and women and the effect of chamber size on accuracy. BACKGROUND: The diagnostic accuracy of conventional exercise testing has been shown to be lower in women. Less is known about the relative accuracy of perfusion imaging. Because of smaller body size, women have a smaller heart size than men, a factor that may reduce accuracy. METHODS: We identified 323 patients undergoing thallium-201 SPECT myocardial perfusion imaging who either had < 5% probability of coronary artery disease (CAD) by Bayesian analysis or who underwent cardiac catheterization within 60 days of stress testing. Patients with documented history of infarction, coronary artery bypass grafting, pathologic Q waves on the electrocardiogram, left bundle branch block or nonischemic cardiomyopathy were not included. We performed strict quantitative analysis, and receiver operating characteristic (ROC) curves were generated and the area under the curve was calculated for men and women. A size index was generated from the number of short-axis slices and average radius of each slice, and the group was classified as having a large or a small chamber size. The ROC areas of men and women with a large and a small chamber size were then compared. RESULTS: Diagnostic accuracy was lower in women than in men (ROC are 0.82 vs. 0.93, p < 0.05) despite similar values for peak heart rate and rate-pressure product and similar severity of CAD. There was a greater difference in accuracy between patients with a large versus a small chamber size (ROC area 0.94 vs. 0.73, p < 0.01) despite similar levels of exercise and severity of CAD. When we compared men and women in groups stratified by chamber size, we could not detect a significant difference between ROC area values of men and women (large: 0.94 men, 0.93 women, p = 0.77, power to detect difference in area of 0.15 = 91%; small: 0.79 men, 0.72 women, p = 0.58, power to detect difference in area of 0.15 = 35%). CONCLUSIONS: The diagnostic accuracy of thallium SPECT myocardial perfusion imaging is lower in women than in men. Most of the difference appears to be due to smaller left ventricular chamber size in women, although a small residual gender effect in smaller heart sizes cannot be entirely excluded. It is proposed that the most likely cause for this difference is the relatively greater effect of imaging blurring on smaller hearts.

Aged↗
PubMed2000

Home blood pressure: accuracy is independent of monitoring schedules.

Long-term morbidity and mortality from hypertension are more closely related to home than to casual office blood pressure levels. There is no generally accepted recommendation on how to best schedule home blood pressure (HBP) recordings, perhaps because the effect of varying the home monitoring schedule on the HBP average is not well studied. The goals of this analysis are to describe the effects of HBP monitoring schedules on the accuracy of resultant HBP averages and to determine which monitoring schedule parameters correlate with HBP accuracy. Twelve published studies, each including home, office, and awake ambulatory blood pressure means were identified. Accuracy of office and HBP averages were determined by their agreement with corresponding awake ambulatory averages. Variations in HBP monitoring schedule parameters did not significantly affect the accuracy of the resultant HBP averages among the studies. In univariate analyses, no individual parameter correlated significantly with the final HBP average accuracy. As the total number of HBP readings obtained increased, or as other monitoring schedule parameters intensified, the superior accuracy of HBP levels as compared to that of casual office values also failed to significantly improve. No HBP accuracy differences were found among groups characterized by different HBP schedule parameter ranges. In conclusion, the accuracy of HBP measurements, as determined by their agreement with an awake ambulatory mean, is maintained regardless of substantial variations in HBP monitoring schedules. Therefore, the majority of the benefits derived from HBP monitoring will likely be achieved by obtaining only a few HBP measurements using a minimally complex monitoring schedule.

Blood Pressure↗
PubMed1998

Clinical accuracy of the diagnosis of cutaneous malignant melanoma.

Diagnostic accuracy for melanoma was determined in a dedicated pigmented lesion clinic. We assessed the impact of duration of experience in dermatology and also the relationship between tumour thickness and accuracy of clinical diagnosis. We reviewed the histopathology request forms and reports for all biopsies generated by the Pigmented Lesion Clinic, Western Infirmary, Glasgow during 1992-94 inclusive. The clinic is staffed by two consultants, one senior registrar and one registrar. Diagnostic accuracy, index of suspicion, sensitivity, specificity and positive predictive value were calculated for the clinic overall, and for each grade of staff. One hundred and sixty-three lesions were diagnosed clinically as melanoma. A histopathological diagnosis of melanoma was made for 128 lesions during this period, 113 of which had been correctly diagnosed before surgery. The diagnostic accuracy for two dermatologists each with > 10 years experience in dermatology was 80%, with sensitivity of 91% and positive predictive value of 86%. Diagnostic accuracy rates for two senior registrars (each with 3-5 years experience) and six registrars (each with 1-2 years experience) were 62% and 56%, respectively. Thin and intermediate thickness melanomas generated the greatest inaccuracy irrespective of clinical experience, although registrars failed to recognize melanoma three times more often than the other groups. We report the diagnostic accuracy for melanoma by trained dermatologists to be higher than previously reported. In comparison with trainees, > 10 years experience in dermatology and exposure to more than 10 melanomas per year appears to be associated with greater diagnostic accuracy. Knowledge of the current clinical diagnostic accuracy at varying levels of experience is essential if the impact of training is to be evaluated. As pigmented lesions of virtually all types can be treated within dermatology departments, dermatologists are the appropriate first point of referral for suspected early melanoma.

Clinical Competence↗
PubMed2000

Methods for determining the accuracy of radiostereometric analysis (RSA).

The problem of determining the noise level in any measuring system remains urgent. Radiostereometric analysis (RSA) is a radiographic system of unique accuracy which has applications in areas where minute motions or no motion at all occurs. Examples are micromotion between endoprostheses and bone and in fracture healing. We have determined the accuracy of the RSA system as applied to a clinical series of spinal fusions, where the conditions for RSA were not optimal. Using the usual test-retest methodology on a phantom, we showed that its accuracy can be grossly overestimated in the individual case. We found considerable variations in the accuracy in the individual case, depending on the rigid-body configuration. The overall accuracy, expressed as 3-D "vectors" for rotation and translation, respectively, correlated with the condition number, a method for characterizing the marker configuration. Indeed, the condition number explained as much as 92% of the variation in overall rotation. This condition number, however, cannot be used to analyze the accuracy of one degree of freedom of rotation alone. Mathematical simulation of the accuracy in the individual case of the individual dimension, using in-house software, showed that the accuracy (95% confidence) varied between 0.4 and 4.6 degrees of rotation about the transverse axis, corresponding to a clinical stress series of extension and flexion.

Artifacts↗
PubMed1994

The effects of temporal-precision and time-minimization constraints on the spatial and temporal accuracy of aimed hand movements.

Discrete aimed hand movements, made by subjects given temporal-accuracy and time-minimization task instructions, were compared. Movements in the temporal-accuracy task were made to a point target with a goal movement time of 400 ms. A circular target then was manufactured that incorporated the measured spatial errors from the temporal-accuracy task, and subjects attempted to contact the target with a minimum movement time and without missing the circular target (time-minimization task instructions). This procedure resulted in equal movement amplitude and approximately equal spatial accuracy for the two task instructions. Movements under the time-minimization instructions were completed rapidly (M = 307 ms) without target misses, and tended to be made up of two submovements. In contrast, movements under temporal-accuracy instructions were made more slowly (M = 397 ms), matching the goal movement time, and were typically characterized by a single submovement. These data support the hypothesis that movement times, at a fixed movement amplitude versus target width ratio, decrease as the number of submovements increases, and that movements produced under temporal-accuracy and time-minimization have different control characteristics. These control differences are related to the linear and logarithmic speed-accuracy relations observed for temporal-accuracy and time-minimization tasks, respectively.

Journal Article↗
PubMed2002

Accuracy of CT in local staging of gallbladder carcinoma.

PURPOSE: To evaluate the accuracy of CT for staging gallbladder cancers, especially the T-factor of the TNM staging system. MATERIAL AND METHODS: CT investigations of 100 patients with surgically proven gallbladder cancers were retrospectively analyzed. Dynamic helical CT was performed in 16 patients and conventional CT in the remaining 84. On CT, three radiologists attempted tumor staging for these patients; the majority opinion was used for final decision. According to CT protocols (dynamic helical CT vs. conventional CT) and each tumor type (thickened wall/intraluminal mass/massive), the accuracy of CT staging was compared. The CT staging was correlated with the surgico-pathologic results. RESULTS: The overall accuracy of CT for staging gallbladder cancers was 71%; it was 79% for T1 and T2 tumors, 46% for T3 tumors, and 73% for T4 tumors. For all three readers, the poorest accuracy was obtained in T3 tumors. No statistically significant difference was noted in the accuracy between the groups undergoing conventional CT and dynamic helical CT. A statistically significant difference was noted in the accuracy for staging thickened wall and intraluminal mass types of tumors (p<0.05); the highest accuracy was obtained in the intraluminal mass type (89%) and the massive type (83%), while it was 54% in the thickened wall type. CONCLUSION: The accuracy of tumor staging with CT in patients with gallbladder cancer depends on the morphological type of tumor. The poorest result is obtained in the thickened wall type.

Adult↗
PubMed2003

Association of volume and volume-independent factors with accuracy in screening mammogram interpretation.

BACKGROUND: Early detection of breast cancer is associated with the accurate reading of screening mammograms, but factors that influence reading accuracy are not well understood. We thus investigated whether reading volume and other factors were independently associated with accuracy in reading screening mammograms in a population of U.S. radiologists. METHODS: A random selection of 110 of 292 radiologists who agreed to participate, if selected, interpreted screening mammograms from 148 randomly selected women. Original index mammograms (i.e., mediolateral oblique and craniocaudal views of each breast) were used; comparison original mammograms were provided when available. Radiologist-level and facility-level factors were surveyed. Two standard metrics of screening accuracy, both based on receiver operating characteristic curves, were analyzed. The influence of volume on accuracy after controlling for other factors was assessed with multiple regression analysis. RESULTS: Current reading volume was not statistically significantly associated with interpretive accuracy. More recently trained radiologists interpreted mammograms more accurately than those trained earlier (-0.76% [95% confidence interval (CI) = -1.75% to -0.02%] reduction in sensitivity per year since residency). Facility-level factors that were statistically significantly and independently associated with better accuracy were the number of diagnostic breast imaging examinations and image-guided breast interventional procedures performed (0.55% [95% CI = 0.11% to 2.40%] increase in accuracy per examination or procedure offered), being classified as a comprehensive breast diagnostic and/or screening center or freestanding mammography center (1.39% [95% CI = 0.15% to 3.82%] higher than a hospital radiology department or multispecialty medical clinic), and being a facility that practiced double reading (1.61% [95% CI = 1.99% to 11.65%]) higher than in a facility without such practice). CONCLUSIONS: Individual radiologists' current reading volume was not statistically significantly associated with accuracy in reading screening mammograms, but several other factors were. Expertise reflects a complex multifactorial process that needs further clarification.

Adult↗
PubMed2005

More genes or more taxa? The relative contribution of gene number and taxon number to phylogenetic accuracy.

The relative contribution of taxon number and gene number to accuracy in phylogenetic inference is a major issue in phylogenetics and of central importance to the choice of experimental strategies for the successful reconstruction of a broad sketch of the tree of life. Maximization of the number of taxa sampled is the strategy favored by most phylogeneticists, although its necessity remains the subject of debate. Vast increases in gene number are now possible due to advances in genomics, but large numbers of genes will be available for only modest numbers of taxa, raising the question of whether such genome-scale phylogenies will be robust to the addition of taxa. To examine the relative benefit of increasing taxon number or gene number to phylogenetic accuracy, we have developed an assay that utilizes the symmetric difference tree distance as a measure of phylogenetic accuracy. We have applied this assay to a genome-scale data matrix containing 106 genes from 14 yeast species. Our results show that increasing taxon number correlates with a slight decrease in phylogenetic accuracy. In contrast, increasing gene number has a significant positive effect on phylogenetic accuracy. Analyses of an additional taxon-rich data matrix from the same yeast clade show that taxon number does not have a significant effect on phylogenetic accuracy. The positive effect of gene number and the lack of effect of taxon number on phylogenetic accuracy are also corroborated by analyses of two data matrices from mammals and angiosperm plants, respectively. We conclude that, for typical data sets, the number of genes utilized may be a more important determinant of phylogenetic accuracy than taxon number.

Evolution, Molecular↗
PubMed2001

A systematic review of discharge coding accuracy.

BACKGROUND: The aim of the study was to review systematically the literature measuring the accuracy of routine UK hospital statistics that classify patients on discharge. METHODS: A systematic review was carried out of studies comparing routine discharge statistics about an episode of hospital care with the original medical record. Dual quality assessment and extraction was completed for included studies. Qualitative and descriptive analyses were undertaken. Additional comparisons of factors that could potentially introduce systematic variation in coding accuracy were also undertaken. RESULTS: Thirty studies were identified, of which 21 were included in the review. Twelve of these were conducted in England and Wales, and nine in Scotland. The majority assessed the accuracy of a single diagnosis, or selection of diagnoses in a limited range of hospital settings. The median coding accuracy rates were 91 per cent for diagnostic codes and 69.5 per cent for operation or procedure codes in studies in England or Wales; 82 per cent for diagnostic codes and 98 per cent for operation or procedure codes in Scottish studies. There were no significant differences in coding accuracy over time or in the type or rarity of the codes being assessed. Accuracy rates were higher for ICD7 codes (median 96.5 per cent) than for ICD8 (median 87 per cent) or ICD9 (median 77 per cent). CONCLUSIONS: Coding accuracy on average is high in the United Kingdom, especially for operations and procedures. However, policy-makers, planners and researchers need to recognize and account for the degree of inaccuracy in routine hospital information statistics. Further research is needed into methods of improving and maintaining coding accuracy.

Abstracting and Indexing↗
PubMed1989

Decreased flow accuracy from volumetric infusion pumps.

Accurate flow from infusion pumps should be maintained when exposed to a variety of clinical conditions. The intent of this study was to evaluate in vitro flow rate accuracy of three infusion pumps subjected to the influences of variable back-pressure, solution viscosity, and infusion rates. A factorial study design was selected to determine the influence of three flow rates (5, 10, and 20 ml/h), three back-pressures (100, 200, and 300 mm Hg), and two solution viscosities (5%, 25% dextrose in water) on flow rate accuracy from three infusion pumps (Abbott 4P, IVAC 560, and Travenol 6200) using a standard gravimetric technique. Mean +/- SD accuracy values were -9.4 +/- 6.4% (range -29.1 to -0.7), 0.5 +/- 2.2% (range -4.2 to 6.3), and -0.5 +/- 4.7% (range -8.5 to 9.9) of the desired rate for the Abbott, IVAC, and Travenol devices, respectively. Back-pressure was the only factor to influence significantly flow accuracy for the Abbott device (r = .81). All factors significantly influenced accuracy for the Travenol device (r = .55). No factor influenced accuracy for the IVAC infusion pump. Both the IVAC 560 and Travenol 6200 have acceptable flow accuracy values within the range of study factors examined. The Abbott 4P had significant decreases in flow accuracy in response to increasing back-pressure.

Calibration↗
PubMed1996

Accuracy and reliability of disposable pressure transducers coupled with modern pressure monitors.

OBJECTIVE: To determine the bedside accuracy of direct patient pressure monitoring when used with new and clinically used disposable blood pressure (BP) transducers. DESIGN: Prospective study. SETTING: Laboratory bench and critical care units in an adult and children's hospital. SUBJECTS: Seventy-five bedside patient monitors (25 Marquette Electronics, 25 Spacelab Medical, and 25 Hewlett-Packard), and 100 disposable transducers (50 from Utah Medical Products and 50 from Abbott Critical Care Systems [25 new, 25 clinically used of each manufacturer]) were tested. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: A +/- 2% accuracy requirement for bedside monitors and the +/- 3% American National Standards Institute accuracy standard for disposable BP transducers were used. To test the accuracy of the bedside monitors, a certified transducer simulator was used to apply 100 mm Hg to each bedside monitor. To test the accuracy of the disposable BP transducers, a very accurate (+/- 0.05%) pneumatic dead weight tester was used to apply pressures to the transducer. A digital power supply and a 6 1/2 digit voltmeter were used. The average output of the bedside monitors when 100 mm Hg was applied was 99.90 +/- 0.83 mm Hg, with the worst cases being 98 and 103 mm Hg. For all 100 disposable pressure transducers, the average output was 100.03 +/- 0.55 mm Hg, with the worst cases being 98.53 and 101.36 when 100 mm Hg was applied. There was no important difference in the accuracy of the transducers obtained from the two vendors nor whether the transducers had been used clinically. CONCLUSIONS: All disposable BP transducers tested were much more accurate than the American National Standards Institute standard for accuracy. Even the worst case transducers were twice as accurate as required by the American National Standards Institute standard. Only one bedside monitor was outside the +/- 2% accuracy range (103 mm Hg). Based on these findings, this author recommends that fixed calibration disposable transducers and fixed calibration bedside pressure monitoring systems be used. The clinical risks of air embolism and infection from the calibrating mercury manometer and the complexity of the calibration task are the overriding factors for making these recommendations.

Adult↗
PubMed2003

Accuracy of spinal navigation for magerl screws.

The influence of a protocol of preoperative computed tomography scanning and a special registration technique was assessed on the accuracy of navigation for implanting Magerl C1-C2-screws. The use of navigation systems for implanting Magerl screws could help to decrease the risk of complications and to reduce the required skin incision. Two parameters conceivably affecting the accuracy are the protocol of preoperative computed tomography scanning and the registration technique. Four cervical spine segments of human cadavers were scanned with two computed tomography protocols. Registration was done based on anatomic landmarks or using a specially designed percutaneous registration device. For the accuracy check, the pointer tip was placed exactly on the markers. The displayed distance on the monitor was referred as an estimate of accuracy. Varying the computed tomography protocol did not significantly affect the accuracy. The mean accuracy was improved from 3 mm after anatomic pair-point matching to 1.5 mm after matching using the percutaneous registration device. The accuracy obtainable seems to be sufficient for implanting Magerl screws by using frameless stereotactic navigation. Three-millimeter slice thickness and 2-mm table increment is a proper protocol for preoperative computed tomography scanning. Fiducial markers improve the accuracy significantly.

Arthritis, Rheumatoid↗
PubMed2005

Use, accuracy, and implications for patient management of [18F]-2-fluorodeoxyglucose-positron emission/computerized tomography for head and neck tumors.

OBJECTIVES/HYPOTHESIS: Positron emission tomography (PET) has shown promise for early detection and accurate staging of cancer patients. A limited number of studies suggest PET/computed tomography (CT) may improve these variables; however, no published study has specifically evaluated clinical outcomes with PET/CT for head and neck (HN) tumors. The current study evaluates the use, accuracy, and implications for patient management of PET/CT scans in patients with HN tumors. STUDY DESIGN: Retrospective cohort outcomes study at a tertiary care center. METHODS: The authors identified 795 consecutive PET/CT at our institution. A total of 113 were obtained for HN tumors; 97 were used in the final analysis. Accuracy, use, and implications for patient care management decisions were correlated with each PET/CT scan. Multiple regression analysis was performed. RESULTS: Accuracy, sensitivity, and specificity were measured by comparing the PET/CT results at the primary tumor site, cervical node sites, and distant sites with either pathologic or definitive clinical diagnoses. PET/CT had an overall per scan accuracy of 72% and a per patient accuracy of 69%. When stratification for rationale of obtaining the scan was performed, accuracy was 80% for staging distant disease, 67% for primary tumor evaluation, 72% for evaluation for recurrence, and 60% for unknown primary tumor evaluation. CONCLUSIONS: PET/CT imaging is a promising tool for evaluating HN tumors; however, in clinical practice, the proper use of such technology is not well studied. In our study, PET/CT had an overall accuracy of 72% in evaluating HN tumors, and PET/CT had the most accuracy in the detection of distant metastasis.

Brain↗