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PubMed1999

Accuracy of true frameless stereotaxy: in vivo measurement and laboratory phantom studies. Technical note.

The authors present the results of accuracy measurements, obtained in both laboratory phantom studies and an in vivo assessment, for a technique of frameless stereotaxy. An instrument holder was developed to facilitate stereotactic guidance and enable introduction of frameless methods to traditional frame-based procedures. The accuracy of frameless stereotaxy was assessed for images acquired using 0.5-tesla or 1.5-tesla magnetic resonance (MR) imaging or 2-mm axial, 3-mm axial, or 3-mm helical computerized tomography (CT) scanning. A clinical series is reported in which biopsy samples were obtained using a frameless stereotactic procedure, and the accuracy of these procedures was assessed using postoperative MR images and image fusion. The overall mean error of phantom frameless stereotaxy was found to be 1.3 mm (standard deviation [SD] 0.6 mm). The mean error for CT-directed frameless stereotaxy was 1.1 mm (SD 0.5 mm) and that for MR image-directed procedures was 1.4 mm (SD 0.7 mm). The CT-guided frameless stereotaxy was significantly more accurate than MR image-directed stereotaxy (p = 0.0001). In addition, 2-mm axial CT-guided stereotaxy was significantly more accurate than 3-mm axial CT-guided stereotaxy (p = 0.025). In the clinical series of 21 frameless stereotactically obtained biopsies, all specimens yielded the appropriate diagnosis and no complications ensued. Early postoperative MR images were obtained in 16 of these cases and displacement of the biopsy site from the intraoperative target was determined by fusion of pre- and postoperative image data sets. The mean in vivo linear error of frameless stereotactic biopsy sampling was 2.3 mm (SD 1.9 mm). The mean in vivo Euclidean error was 4.8 mm (SD 2 mm). The implications of these accuracy measurements and of error in stereotaxy are discussed.

Adult↗
PubMed2004

Comparison of hydrocolonic sonograpy accuracy in preoperative staging between colon and rectal cancer.

AIM: To compare the accuracy of hydrocolonic sonography (HUS) in determining the depth of invasion (T stage) in colon and rectal cancer. METHODS: A total of 1 000-2 000 mL of saline was instilled per rectum using a system for barium enemas, and then ultrasonography was conducted by a SSA-270A (Toshiba Co, Japan) sonolayer unit with a 3.75 MHz for 17 patients with colon cancer and 13 patients with rectal cancer before operation. After operation, T stage in HUS was compared with postoperative histological findings. RESULTS: Overall, the accuracy of T stage was 70%. It was 88% in colon cancer and 46% in rectal cancer. In evaluating nodal state, the accuracy of HUS was low in both colon (71%) and rectal cancers (46%) compared with conventional CT or MRI. The overall accuracy of N staging was 60%. CONCLUSION: HUS is valuable to evaluate the depth of invasion in colon cancer, but is less valuable in rectal cancer. Because HUS is low-cost, noninvasive, and readily available at any place, this technique seems to be useful to determine the preoperative staging in colon cancer, but not in rectal cancer.

Adult↗
PubMed2006

Confidence and accuracy in deductive reasoning.

In two experiments, we investigated the relationship between confidence and accuracy in syllogistic reasoning. Participants judged the validity of conclusions and provided confidence ratings twice for each problem: once quickly and again after further deliberation. Correlations between confidence and accuracy were small or nonexistent. In addition, confidence and accuracy were mediated by different variables. Confidence judgments appeared to reflect external cues, so that confidence was greater when the participants were allowed additional time to think about the problem, as well as when the conclusion was either believable or unbelievable, rather than neutral. In contrast, accuracy changed little as a function of the amount of time available and did not differ for believable and neutral problems. These data support a model in which initial decisions are made quickly, on the basis of heuristic cues, and analytic processes are used to justify or rationalize the earlier decision.

Adult↗
PubMed2005

Look little, look often: the influence of gaze frequency on drawing accuracy.

The present article attempts to determine what those who draw accurately do differently than those who do not. Four experiments explore the relation between drawing accuracy and the rate at which artists glance between their drawing and the stimulus (termed gaze frequency). Experiment 1 revealed a positive relation between gaze frequency and drawing accuracy (r2 = .33). Experiments 2, 3, and 4 demonstrated that gaze frequency directly influences drawing accuracy. High gaze frequencies may facilitate drawing accuracy by (1) allowing the artist to hold less information in working memory, (2) reducing memory distortion, and (3) facilitating the reduction of context effects through inattentional blindness.

Eye Movements↗
PubMed2000

The rereading effect: metacomprehension accuracy improves across reading trials.

Guided by a hypothesis that integrates principles of monitoring from a cue-based framework of metacognitive judgments with assumptions about levels of text representation derived from theories of comprehension, we discovered that rereading improves metacomprehension accuracy. In Experiments 1 and 2, the participants read texts either once or twice, rated their comprehension for each text, and then were tested on the material. In both experiments, correlations between comprehension ratings and test scores were reliably greater for participants who reread texts than for participants who read texts only once. Furthermore, in contrast to the low levels of accuracy typically reported in the literature, rereading produced relatively high levels of accuracy, with the median gamma between ratings and test performance being +.60 across participants from both experiments. Our discussion focuses on two alternative hypotheses--that improved accuracy is an artifact of when judgments are collected or that it results from increased reliability of test performance--and on evidence that is inconsistent with these explanations for the rereading effect.

Adult↗
PubMed2000

Accounts of the confidence-accuracy relation in recognition memory.

Confidence and accuracy, while often considered to tap the same memory representation, are often found to be only weakly correlated (e.g., Bothwell, Deffenbacher, & Brigham, 1987; Deffenbacher, 1980). There are at least two possible (nonexclusive) reasons for this weak relation. First, it may be simply due to noise of one sort or another; that is, it may come about because of both within- and between-subjects statistical variations that are partially uncorrelated for confidence measures on the one hand and accuracy measures on the other. Second, confidence and accuracy may be uncorrelated because they are based, at least in part, on different memory representations that are affected in different ways by different independent variables. We propose a general theory that is designed to encompass both of these possibilities and, within the context of this theory, we evaluate effects of four variables--degree of rehearsal, study duration, study luminance, and test luminance--in three face recognition experiments. In conjunction with our theory, the results allow us to begin to identify the circumstances under which confidence and accuracy are based on the same versus different sources of information in memory. The results demonstrate the conditions under which subjects are quite poor at monitoring their memory performance, and are used to extend cue utilization theories to the domain of face recognition.

Cognition↗
PubMedDate not supplied

Accuracy and precision of the NovoPen 3 insulin delivery device after mechanical and temperature stresses.

OBJECTIVE: To evaluate the precision, accuracy, and durability of an insulin pen injection device (NovoPen 3) at three preset doses (2 IU, 35 IU, and 70 IU) after exposure to various stress and durability tests that were intended to simulate daily use by patients. METHODS: Twenty-nine reusable NovoPen 3 insulin delivery devices were tested. The precision and accuracy of 10 insulin pen devices were evaluated after they were subjected to multiple thermal and vibration stress tests. Another 10 pen devices were subjected to a free-fall test. Nine other insulin pens were subjected to endurance testing that simulated 5 years of injections. RESULTS: The accuracy (as measured by the relative error of the delivered dose of insulin) of the insulin pen injection devices was within 1% of the preset dose after all stress or endurance tests. A free-fall test produced no indication of damage except for broken clips and snap catches on the caps, which did not affect the integrity or performance of the insulin pens. The precision of the pen devices (as measured by relative standard deviations of delivered volumes of insulin) was likewise high after thermal stress, vibration stress, free-fall testing, or 5-year endurance testing. CONCLUSION: Overall, this study showed that the insulin pen injection devices tested were durable under conditions of stress likely to be encountered in daily patient use. Neither a wide variety of repetitive stresses nor insulin injection cycles corresponding to 5 years of use affected the accuracy or precision enough to have clinical significance for reliable insulin delivery.

Equipment Failure↗
PubMed2004

[The effect of empathy on accuracy of behavior prediction in social exchange situation].

Seventy-six participants first played a prisoner's dilemna (PD) game with an anonymous partner and then predicted behavior of other participants in the same PD game. In addition, they took a test of accuracy in judging sociometric relations among group members. Of the four factors of empathy, the two reflecting emotional aspects--self-directed and other-directed emotional responses--were found to have no relation with accuracy in predicting behavior of other participants and judging sociometric relations among group members. In contrast, the other two reflecting cognitive aspects--imagination and perspective taking--were found to be related to accuracy in predicting behavior of other participants in the PD game. Of the two, imagination was a better indicator of accuracy in the prediction than perspective taking. Implications of these findings are discussed in terms of domain specificities of adaptive task that different aspects of empathy are thought to fulfill.

Adult↗
PubMed2006

Evaluating the accuracy of health news publications in a drug literature evaluation course.

OBJECTIVES: To design an assignment for second-professional year pharmacy students to assess the accuracy and quality of health information published in the news. DESIGN: Students in a literature evaluation course were assigned a health-related news publication to review and find the original published research article. They then critically evaluated the quality and accuracy of the news publication based on the original research. All students wrote a critique focusing on the quality and accuracy of the news article and potential responses the lay public might have. ASSESSMENT: Eighty-four percent of students agreed the writing assignment reinforced critical literature evaluation skills, while 90% agreed the assignment contributed to completion of course objectives. CONCLUSIONS: A writing assignment requiring comparison of a news publication to the original research reinforces critical literature evaluation and communication skills, as well as stimulates thought about the accuracy, quality, and public responses to health information published in the news.

Education, Pharmacy↗
PubMed1988

Diagnosis of skin cancer in the general population: clinical accuracy in the Nambour survey.

The accuracy and validity of diagnoses of skin cancer that were made by experienced dermatologists in a Queensland community survey have been investigated. Histological examination confirmed 54% of 100 clinical diagnoses of basal-cell carcinoma, squamous-cell carcinoma or intraepidermal carcinoma. Clinical accuracy was higher for basal-cell carcinoma (59%) than for squamous-cell carcinoma (39%) or intraepidermal carcinoma (38%). Such levels of diagnostic accuracy are to be expected when an unselected population is surveyed because of the relatively low prevalence of skin cancer compared with that in the patient population of a specialist practice. This reduction in diagnostic accuracy is unrelated to clinical skills, and should be borne in mind when conducting any skin-cancer screening programme in the general community.

Adult↗
PubMed1997

Systematic review of the diagnostic accuracy of dermatoscopy in detecting malignant melanoma.

OBJECTIVE: To assess the evidence that dermatoscopy improves the accuracy of diagnosis of melanomas in clinical practice. DATA SOURCES: MEDLINE 1983-January 1997, EMBASE 1980-1996, and bibliographies of retrieved articles. STUDY SELECTION AND DATA EXTRACTION: Studies selected were original studies with formal methods and results sections comparing diagnostic accuracy of dermatoscopy for malignant melanoma with another clinical method; the criterion standard was excision biopsy with histopathological examination; and accuracy of dermatoscopic diagnosis was determined over a spectrum of stages of melanoma and skin lesions commonly confused with melanoma. Data were extracted by a single observer. DATA SYNTHESIS: 579 articles were identified; six studies met the inclusion criteria. Positive likelihood ratios for dermatoscopy for diagnosis of melanoma ranged from 2.9 to 10.3. Dermatoscopy had 10%-27% higher sensitivity than clinical diagnosis in the two studies with the most clinically equivocal lesions. However, when sensitivity of clinical diagnosis was more than 84%, sensitivity of dermatoscopy was only slightly higher. One study of dermatologists with no training in dermatoscopy showed a significant decrease in sensitivity. CONCLUSIONS: Variability between studies in methods, observers and types of pigmented skin lesions and lack of studies in primary care make generalisation of results difficult. Dermatoscopy appeared not to improve the accuracy of diagnosis enough to alter the clinical management of most pigmented skin lesions. Further research with more explicit methods is needed.

Humans↗
PubMed2003

Individual and combined effects of age, breast density, and hormone replacement therapy use on the accuracy of screening mammography.

BACKGROUND: The relationships among breast density, age, and use of hormone replacement therapy (HRT) in breast cancer detection have not been fully evaluated. OBJECTIVE: To determine how breast density, age, and use of HRT individually and in combination affect the accuracy of screening mammography. DESIGN: Prospective cohort study. SETTING: 7 population-based mammography registries in North Carolina; New Mexico; New Hampshire; Vermont; Colorado; Seattle, Washington; and San Francisco, California. PARTICIPANTS: 329 495 women 40 to 89 years of age who had 463 372 screening mammograms from 1996 to 1998; 2223 women received a diagnosis of breast cancer. MEASUREMENTS: Breast density, age, HRT use, rate of breast cancer occurrence, and sensitivity and specificity of screening mammography. RESULTS: Adjusted sensitivity ranged from 62.9% in women with extremely dense breasts to 87.0% in women with almost entirely fatty breasts; adjusted sensitivity increased with age from 68.6% in women 40 to 44 years of age to 83.3% in women 80 to 89 years of age. Adjusted specificity increased from 89.1% in women with extremely dense breasts to 96.9% in women with almost entirely fatty breasts. In women who did not use HRT, adjusted specificity increased from 91.4% in women 40 to 44 years of age to 94.4% in women 80 to 89 years of age. In women who used HRT, adjusted specificity was about 91.7% for all ages. CONCLUSIONS: Mammographic breast density and age are important predictors of the accuracy of screening mammography. Although HRT use is not an independent predictor of accuracy, it probably affects accuracy by increasing breast density.

Adipose Tissue↗
PubMed2005

Accuracy of 3-dimensional color Doppler-derived flow volumes with increasing image depth.

OBJECTIVES: We and others have reported on the use of digital color Doppler sonography from real-time 3-dimensional (3D) echocardiography and its use in accurately calculating cardiac flow volumes, namely stroke volume (SV) and, hence, cardiac output. However, in some patients, image depth is higher than average, and this may affect the accuracy of volume calculation. We sought to investigate the impact of image depth and the accompanying change in signal strength, spatial resolution, and pulse repetition frequency on the accuracy of SV calculation from 3D color Doppler data in an in vitro model. METHODS: A tube model of the left ventricular outflow tract was constructed from plastic tubing and connected to a pulsatile pump. The volume flowing through the tube was imaged using a 3D echocardiography system. Stroke volumes from the pump were computed from the DICOM data using commercially available software and compared with a reference standard of timed volumes with the use of a graduated measuring cylinder over a range of depth settings and SVs. RESULTS: There was good correlation between the 3D-derived SVs and the reference cylinder measures over all depths from 4 to 16 cm at 1-cm increments with a tube diameter of 17 mm, a pump rate of 60 beats/min, and SVs ranging from 20 to 70 mL. The average r(2) value for the 13 different depths was 0.976. However, the accuracy of the 3D method of volume calculation appeared to fall at depths greater than 13 cm, especially at higher SVs. CONCLUSIONS: Stroke volume calculation from real-time 3D color Doppler data in this in vitro study shows that at depths greater than approximately 13 cm, accuracy decreases, especially at higher SVs. This may be due to decreased resolution and the reduced frame rate at these depths. At shallower depths, volume calculation form the 3D Doppler data appears very accurate.

Analysis of Variance↗
PubMed2005

Accuracy of sentinel lymph node biopsy for the assessment of axillary status in patients with early (T1) breast carcinoma.

OBJECTIVE: To determine the accuracy of SLN biopsy for the assessment of axillary status, and prognostic markers leading to lymphatic metastasis in patients with early (T1) breast cancer. DESIGN: Cross-sectional study. PLACE AND DURATION OF STUDY: Department of Surgery, Teaching and Research Hospital. Between January 2000 and August 2004. PATIENTS AND METHODS: SLN mapping by blue dye method was performed on 39 patients with T1 breast carcinoma. SLNs, level 1 and 2 axillary nodes were dissected and excised. The size, pathologic features of the primary tumor, SLNs and other axillary nodes, and hormone receptors were evaluated by histopathologic examination. The rate of SLNs and non-SLNs involvement, and demographic, clinical and pathologic risk factors leading to nodal metastasis were established. The diagnostic accuracy of SLN for axillary status was calculated. RESULTS: SLNs were identified in 37 (95%) patients. The axilla had metastasis in 11 (28%) patients. Malignant cells involved SLNs in 8 patients. Non-SLNs had metastasis in 3 patients without SLN involvement. The sensitivity, specificity and accuracy of SLN biopsy for predicting axillary status was calculated as 73%, 100% and 92% respectively. Four of 5 patients with non-SLN metastasis were pre-menopausal (p=0.03), and hormone receptor negative (p=0.04). All 5 patients had T1c tumors (p=0.14) and lymphovascular invasion (p=0.0004). CONCLUSION: SLN biopsy with high diagnostic accuracy may prevent unnecessary dissection of the axilla in the majority of patients with early (T1) breast carcinoma. Some risk factors as pre-menopausal status, absence of hormone receptors, and presence of lymphovascular invasion must be taken into account as important determinant of non-SLNs metastasis.

Adult↗
PubMed1993

Accuracy and reliability of 'specialized' physical therapists in auscultating tape-recorded lung sounds.

This study investigated the accuracy and inter-rater reliability of 'specialized' physical therapists in the auscultation of tape-recorded lung sounds. In addition, a correlation was investigated between accuracy of interpretation and the number of years of specialization in the field of cardiorespiratory physical therapy. This research follows an earlier study which investigated the accuracy and inter-rater reliability of auscultating tape-recorded lung sounds in a 'non-specialized' cohort of physical therapists. The subjects were 26 'specialized' cardiorespiratory physical therapists working in acute urban teaching hospitals. These individuals were required to have been practising currently and exclusively for at least one year in the area of cardiorespiratory physical therapy. Participants listened with a stethoscope to five different sounds and identified them from a standardized list of terms. One of three tapes with the same lung sounds in different order was randomly selected for each physical therapist. The percentage of correct answers for all subjects was calculated. An accurate response in the detection of lung sounds was arbitrarily defined as a percentage of correct answers of 70% or greater. The difference between the pooled correct response rate of 50% and the arbitrarily set value of 70% was statistically significant (z = 2.23, p < 0.05), indicating that the 'specialized' physical therapists were not accurate in identifying lung sounds. There was no relationship evident between the accuracy and the number of years of cardiorespiratory 'specialization' (r = 0.08). Analysis of inter-rater reliability revealed 'fair agreement' (kappa = 0.26) among subjects. These results were similar to those found in the previous study.(ABSTRACT TRUNCATED AT 250 WORDS)

Auscultation↗
PubMed1997

The effects of automated encoders on coding accuracy and coding speed.

Encoded data on diagnoses and procedures are put to a broad range of uses. Coding accuracy and speed are imperative. One method that coding experts have recommended to improve coding accuracy and speed is automated encoders. The article describes the effect of automated encoders on coding accuracy and speed when used by trained coding staff. A study involving six Veterans Administration medical centers found that, overall, coding accuracy improved 19.4 percent after implementation of encoding software. The effect on coding speed, however, depended on the system set-up, with some set-ups actually reducing the number of discharges coded per day.

Abstracting and Indexing↗
PubMed1997

Inventory accuracy in 60 days!

Despite great advances in manufacturing technology and management science, thousands of organizations still don't have a handle on basic inventory accuracy. Many companies don't even measure it properly, or at all, and lack corrective action programs to improve it. This article offers an approach that has proven successful a number of times, when companies were quite serious about making improvements. Not only can it be implemented, but also it can likely be implemented within 60 days per area, if properly managed. The hardest part is selling people on the need to improve and then keeping them motivated. The net cost of such a program? Probably less than nothing, since the benefits gained usually far exceed the costs. Improved inventory accuracy can aid in enhancing customer service, determining purchasing and manufacturing priorities, reducing operating costs, and increasing the accuracy of financial records. This article also addresses the gap in contemporary literature regarding accuracy program features for repetitive, JIT, cellular, and process- and project-oriented environments.

Equipment and Supplies↗
PubMed1999

The diagnostic accuracy of ultrasound scan in predicting endometrial hyperplasia and cancer in postmenopausal bleeding.

OBJECTIVE: To determine the accuracy of ultrasound scan in the diagnosis of endometrial hyperplasia and cancer in postmenopausal bleeding. DESIGN: A prospective diagnostic accuracy study (1996-97). SETTING: Minimal access surgical training centers in two large teaching hospitals. METHODS: Ultrasound scan and outpatient endometrial sampling were performed on 96 patients with postmenopausal bleeding. Patients unable to have these outpatient procedures had a formal inpatient hysteroscopy and curettage. Test performance characteristics were computed for ultrasound scan comparing its estimate of endometrial thickness with histologic diagnosis that served as a 'gold' standard. OUTCOME MEASURES: Accuracy of the ultrasonic endometrial thickness was estimated using sensitivity, specificity and predictive values for binary data. For multilevel data, the diagnostic accuracy was computed using likelihood ratios (LRs). An LR < decreased the probability that endometrial hyperplasia/cancer was present, whereas an LR > 1 increased the probability that such lesion was present. RESULTS: Using endometrial thickness > or =4 mm, the sensitivity of ultrasound to detect the endometrial malignancy was 92.9%, the specificity was 500%, and the positive and negative predictive values were 24.1% and 97.6% respectively. Analysis using likelihood ratio (LR) revealed that LR was 0.14 for endometrial thickness > or =4.0 mm, 0.94 for endometrial thickness 4.1-9.0 mm, and 3.3 for endometrial thickness >9.0 mm. CONCLUSION: In women with postmenopausal bleeding, malignancy can probably be safely excluded if sonographic endometrial thickness is < or = 4.0 mm. However, the probability of endometrial hyperplasia/cancer is not particularly altered by the knowledge that endometrial thickness on scan is >4.0 mm.

Biopsy↗