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PubMed1989

Neuroleptics and conditional discrimination tasks: cholinergic mediation of the accuracy- and response rate-altering effects of chlorpromazine and clozapine but not haloperidol.

The effects of the neuroleptic compounds clozapine, chlorpromazine and haloperidol were examined alone and in combination with the muscarinic cholinergic agonist oxotremorine in pigeons responding under a fixed-consecutive-number schedule. Under this procedure, nine or more consecutive responses on one response key followed by a single response on a second response key produced 3sec access to grain. In one component of this schedule (FCN 9-SD), an external discriminative stimulus was presented following the completion of the response requirement on the first response key, whereas no stimulus change was programmed in the other component (FCN 9). When administered alone, clozapine (0.1-5.6mg/kg) and chlorpromazine (3.0-170mg/kg) decreased accuracy (i.e. increased the mean number of response runs per reinforcer) under the FCN 9 at doses that had no effect under the FCN 9-SD. In contrast, haloperidol (0.03-1.7mg/kg) and oxotremorine (0.001-0.1mg/kg) had no effect on accuracy under either variant of the FCN schedule. Under both variants of the FCN schedule, clozapine, chlorpromazine, haloperidol and oxotremorine produced dose-related decreases in rates of responding. When administered in combination, oxotremorine (0.01 and 0.03mg/kg) antagonized the accuracy- and response rate-decreasing effects of both clozapine and chlorpromazine. Although neither haloperidol or oxotremorine decreased accuracy when administered alone, these drugs produced large decreases in accuracy when administered in combination. In most instances, the magnitude of these decreases in accuracy was larger than those obtained following the administration of clozapine or chlorpromazine. The effects of the co-administration of oxotremorine and haloperidol on rate of responding were generally additive. These findings indicate that both the accuracy- and response rate-decreasing effects of clozapine and chlorpromazine are, in part, mediated by their antagonist actions at muscarinic cholinergic receptors. In addition, the finding that the co-administration of haloperidol and oxotremorine decreased accuracy provides support at the behavioral level for an interaction of the dopaminergic and cholinergic systems.

Journal Article↗

PubMed1987

The impact of the quality of laboratory staff on the accuracy of laboratory results.

This study tests the premise that laboratories employing medical technologists certified by the Board of Registry of the American Society of Clinical Pathologists (MT[ASCP]) produce more accurate laboratory test results, as measured by the College of American Pathologists proficiency tests. Licensed laboratories in Illinois provided the sample. An accuracy score on the College of American Pathologists proficiency tests was calculated for each laboratory. The accuracy score of a subgroup of laboratories employing all (100%) certified medical technologists was compared with the accuracy score of a subgroup of laboratories employing only noncertified medical technologists. Those laboratories employing only certified medical technologists had a mean accuracy score of 95% (SD = 4%), while laboratories employing only noncertified medical technologists had a mean accuracy score of 75% (SD = 30%). The Mann-Whitney U test was used to identify differences between the two groups of laboratories. A difference in the accuracy scores between the two groups of laboratories was statistically discernible. Since most laboratories employ some certified medical technologists, a second analysis considered the relationship of the proportion of certified medical technologists employed in the laboratory and accuracy on College of American Pathologists proficiency tests. A significant positive Spearman rs correlation confirmed a relationship between employing a higher proportion of certified medical technologists and accuracy of test results.

Certification↗

PubMed1993

[Accuracy of blood glucose self-monitoring in children with type-I diabetes].

UNLABELLED: Children with type I diabetes often believe that they are able do gauge their blood glucose value without measurement. This study investigated how accurate these estimates are and which of the patient characteristics might affect accuracy. Nineteen children with type I diabetes (age 7.3-17.3 years, duration of diabetes 0.1-12.0 years) estimated their blood glucose immediately before a blood glucose measurement by reflectance meter. Ten to 54 estimations and measurements were done by each individual during a summer camp. According to the method of Cox et al. accuracy of estimates was evaluated by error grid analysis. Five zones were defined: accurate estimates (zone A); clinically benign errors (zone B); clinically dangerous errors (zone C, D, E). An overall accuracy index was calculated by subtracting the summed percentage of estimates in zones C, D, E from the percentage in zone A. The mean percentage of estimates in zone A was 41.5 (10.0-75.0)%, the mean overall accuracy index was 9.8 (-47.4-62.5)%. Except for mean blood glucose which was inversely correlated with accuracy index (r = -0.53, P = 0.02) none of the other patient characteristics showed an effect on accuracy index. CONCLUSIONS: Accuracy of blood glucose estimates is lower in children with type I diabetes than in adults and varies substantially between individuals. High mean blood glucose values are associated with a lower accuracy of estimates.

Adolescent↗

PubMed1996

Do commercial serological kits for Helicobacter pylori infection differ in accuracy? A meta-analysis.

OBJECTIVES: To compare the accuracy of common commercial serological kits for Helicobacter pylori and to ascertain factors affecting accuracy. METHODS: A comprehensive MEDLINE and manual search strategy was used to identify all articles comparing two or more kits. Each article was critically appraised for sample characteristics, study design, and data handling. The data comparing accuracy of the kits was analyzed by standard statistical methods as well as summary receiver operator characteristic curves (sROCs). A sROC also was used to estimate overall test accuracy and to identify factors affecting the measurement of accuracy. RESULTS: The 21 studies identified were of varying quality, but our analyses suggested that different commercial kits did not have significantly different accuracy. Overall, at a sensitivity of 85%, specificity was estimated to be 79%. Test accuracy measured was significantly higher in studies with smaller proportions of infected patients. CONCLUSIONS: There is little evidence in the literature to suggest that any one of the common commercial serological kits is more accurate than any other. The overall accuracy of these kits may not be adequate for clinical decision-making in all patient groups.

Helicobacter Infections↗

PubMedDate not supplied

A new coincidence model for single particle counters, part III: realization of single particle counting accuracy.

U.S.P. objective tests for particle contamination in injectable fluids are based on counts of single particles in a specified test volume. Accuracy standards for these tests must therefore be based on single particle count accuracy. A definitive analysis for this purpose is described whose results can be used during a counting experiment. To improve the accuracy of particle counter data, U.S.P.XXIII has added a particle counter accuracy requirement defined in terms of a maximum particle concentration for 10 microns particles at which there is a 10% ratio of coincident occurrences. The 10% coincident count ratio cannot be directly measured: it must be calculated from experimental results using a model of the counting process. The U.S.P.XXIII count accuracy specification relies on vendor statements without definition of the methodology or model to be employed. The model of particle counting described in the literature is the Geometric Poisson model due to Jaenicke (4) and extended by Lieberman (5). Recent publications (1, 2) have shown that calculations based on this model do not agree with experimental data. This conclusion is supported and extended in this paper. The single particle counting error estimate for U.S.P.XXIII (788) SVI (3), using Jaenicke's Geometric model to evaluate a good commercial laser sourced detector, is 9.32%; the single particle count error estimate for this detector using the experimentally validated Particle-Triggered Poisson model is 19%. The count error for the concentration calculated with the Jaenicke Geometric model for the same detector is 40.5% when calculated with the validated Particle-Triggered Poisson model. The estimated count error increases for particles larger than 10 microns. Light extinction particle counters are well behaved instruments fully capable of the workhorse task of making accurate, routine single particle contamination measurements in injectable products. In principle, any particle counter instrument now in use, operated within calculated particle size and concentration contours, can deliver accurate single particle counting data. Operation within these limits both within and below the U.S.P.XXIII (788) (3) size range will assure single particle count accuracy without the injection of false counts or undercounts. These count limits vary with particle size and are determined by the capability of the counter. No single particle test can characterize the complex particle size and concentration response of a detector. In practice, selection of a counter with sufficient capability to provide the desired accuracy without constant dilution is an important consideration. When particle concentration exceeds the selected count accuracy contour, dilution and a repeat of the assay provide a practical solution.

Drug Contamination↗

PubMed2002

Accuracy of hysteroscopy in the diagnosis of endometrial cancer and hyperplasia: a systematic quantitative review.

CONTEXT: Hysteroscopy (direct endoscopic visualization of the endometrial cavity) is used extensively in the evaluation of common gynecologic problems, such as menorrhagia and postmenopausal bleeding. However, there is a continuing debate about the value of this technology in the diagnosis of serious endometrial disease. OBJECTIVE: To determine the accuracy of hysteroscopy in diagnosing endometrial cancer and hyperplasia in women with abnormal uterine bleeding. DATA SOURCES: Relevant articles were identified through searches of the Cochrane Library, MEDLINE, and EMBASE (1984-2001), manual searches of bibliographies of known primary and review articles, and contact with manufacturers. STUDY SELECTION: Studies were selected blindly, independently, and in duplicate if accuracy of hysteroscopy was estimated in women with abnormal uterine bleeding, using histopathologic findings as a reference standard. Our search identified 3486 articles; 208 of these were deemed to be potentially eligible and were retrieved for detailed data extraction. Sixty-five primary studies were analyzed, including 26 346 women. DATA EXTRACTION: Data were abstracted on characteristics and quality from each study. Results for diagnostic accuracy were extracted to form 2 x 2 contingency tables separately for endometrial cancer and endometrial disease (cancer, hyperplasia, or both). Pooled likelihood ratios (LRs) were used as summary accuracy measures. DATA SYNTHESIS: The pretest probability of endometrial cancer was 3.9% (95% confidence interval [CI], 3.7%-4.2%). A positive hysteroscopy result (pooled LR, 60.9; 95% CI, 51.2-72.5) increased the probability of cancer to 71.8% (95% CI, 67.0%-76.6%), whereas a negative hysteroscopy result (pooled LR, 0.15; 95% CI, 0.13-0.18) reduced the probability of cancer to 0.6% (95% CI, 0.5%-0.8%). There was statistical heterogeneity in pooling of LRs, but an explanation for this could not be found in spectrum composition and study quality. The overall accuracy for the diagnosis of endometrial disease was modest compared with that of cancer, and the results were heterogeneous. The accuracy tended to be higher among postmenopausal women and in the outpatient setting. CONCLUSION: The diagnostic accuracy of hysteroscopy is high for endometrial cancer, but only moderate for endometrial disease (cancer or hyperplasia).

Endometrial Hyperplasia↗

PubMed1997

Dental emergence among urban Zambian school children: an assessment of the accuracy of three methods in assigning ages.

In situations where birth records are unavailable and stated ages are unreliable, the emergence of the permanent dentition can serve as an indicator of age. Due to substantial variation in the timing of tooth emergence, a sample (n = 721) of Zambian school children, with known ages, was examined to provide a tooth emergence reference standard for the area. Three methods for assigning ages were utilized and their accuracy assessed. A random test sample was withheld from the original study in order to further evaluate the methods' accuracy. The three methods-1) number of teeth, 2) regression and 3) probit analysis-were applied to Zambian children, and estimates of age were made. Predicted ages were compared to actual ages to determine the percentage of accuracy in three categories-(+/-) .5, +/- 1.0 and +/- 2.0 years- and paired t-tests were conducted. Each of the three methods was then applied to the test sample, and their accuracy was evaluated in the same manner. Methods 1 and 2 were found to provide the higher percentage of correct ages within +/- .5 years, assigning roughly 39% of both male and female children within this increment. This was also the case at the next increment, with methods 1 and 2 assigning a higher percentage (66-76%) of children to the +/- 1.0 year category, while the accuracy of method 3 was quite a bit lower. The results for the test sample were very similar to those of the main sample. The overall accuracy of methods 1 and 2 was very similar in both the main and test samples, while method 3 had lower accuracy and t-tests indicated significant differences. Therefore, due to ease of application in the field setting, method 1, mean age per number of teeth emerged, is the method of choice.

Adolescent↗

PubMed2005

Relative accuracy of fine-needle aspiration and frozen section in the diagnosis of lesions of the parotid gland.

BACKGROUND: Both fine-needle aspiration (FNA) and frozen section (FS), although useful in preoperative and intraoperative management, have their advantages and pitfalls when used in the diagnosis of salivary gland lesions. The accuracy of each of these modalities has been assessed separately in many studies; a direct comparison of these techniques on a large cohort has not been well studied. Herein, we determine the relative accuracies of both FNA and FS in the diagnosis of salivary gland lesions. METHODS: We reviewed a cohort of 220 cases of parotid gland FNA with histologic follow-up; FS was performed in 57 cases (26%). The sensitivity, specificity, and accuracy of FNA and FS were determined with respect to the final histologic diagnosis. For these calculations, benign diagnosis was considered negative, whereas a malignant diagnosis was considered positive. In addition, we re-reviewed the FNA and FS slides in cases that had conflicting FNA and FS results. RESULTS: Of the 220 cases examined, the FNA diagnoses were as follows: benign (n = 142), malignant (n = 52), indeterminate (n = 14), and nondiagnostic (n = 12). Correlating these findings with the histologic findings, nine cases (4%) were false negative, whereas 12 (5%) were false positive. The sensitivity, specificity, and accuracy for FNA when diagnostic were 86%, 92%, and 90%, respectively. In 57 cases with FS, seven (12%) were false negative, whereas none were false positive. The FS was able to change to benign four diagnoses that were malignant by FNA and provide a diagnosis for five nondiagnostic FNAs. The sensitivity, specificity, and accuracy for FS were 77%, 100%, and 88%, respectively. The sensitivity, specificity, and accuracy for FNA and FS combined were 90%, 100%, and 95%, respectively. CONCLUSIONS: Both FNA and FS provide a similar accuracy. FS may be useful if FNA is nondiagnostic and may also be useful in confirming or refuting malignancy in some cases. Hence, both techniques are complementary to each other in the diagnosis of salivary gland lesions.

Adenolymphoma↗

PubMed2003

Closely spaced external standard: a universal method of achieving 5 ppm mass accuracy over the entire MALDI plate in axial matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

Close deposition of the sample and external standard was used in axial matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) to achieve mass accuracy equivalent to that obtained with an internal standard across the entire MALDI plate. In this work, the sample and external standard were deposited by continuous deposition in separate traces, each approximately 200 micro m wide. The dependence of the mass accuracy on the distance between the sample and standard traces was determined across a MALDI target plate with dimensions of 57.5 mm x 57.0 mm by varying the gap between the traces from 100 micro m to 4 mm. During acquisition, two adjacent traces were alternately irradiated with a 200-Hz laser, such that the peaks in the resulting mass spectra combined the sample and external standard. Ion suppression was not observed even when the peptide concentrations in the two traces differed by more than two orders of magnitude. The five peaks from the external standard trace were used in a four-term mass calibration of the masses of the sample trace. The average accuracy across the whole plate with this method was 5 ppm when peaks of the sample trace had signal-to-noise ratios of at least 30 and the gap between the traces was approximately 100 micro m. This approach was applied to determining peptide masses of a reversed-phase liquid chromatographic (LC) separation of a tryptic digest of beta-galactosidase deposited as a long serpentine trace across the MALDI plate, with accuracy comparable to that obtainable using internal calibration. In addition, the eluent from reversed-phase LC separation of a strong cation-exchange fraction containing tryptic peptides from a yeast lysate along with the closely placed external standard was deposited on the MALDI plate. The data obtained in the MS and MS/MS modes on a MALDI-TOF/TOF mass spectrometer were combined and used in database searching with MASCOT. Since the significant score is a function of mass accuracy in the MS mode, database searching with high mass accuracy reduced the number of false positives and also added peptides which otherwise would have been eliminated at lower mass accuracy (false negatives).

Calibration↗

PubMed2006

An ROC-type measure of diagnostic accuracy when the gold standard is continuous-scale.

ROC curves and summary measures of accuracy derived from them, such as the area under the ROC curve, have become the standard for describing and comparing the accuracy of diagnostic tests. Methods for estimating ROC curves rely on the existence of a gold standard which dichotomizes patients into disease present or absent. There are, however, many examples of diagnostic tests whose gold standards are not binary-scale, but rather continuous-scale. Unnatural dichotomization of these gold standards leads to bias and inconsistency in estimates of diagnostic accuracy. In this paper, we propose a non-parametric estimator of diagnostic test accuracy which does not require dichotomization of the gold standard. This estimator has an interpretation analogous to the area under the ROC curve. We propose a confidence interval for test accuracy and a statistical test for comparing accuracies of tests from paired designs. We compare the performance (i.e. CI coverage, type I error rate, power) of the proposed methods with several alternatives. An example is presented where the accuracies of two quick blood tests for measuring serum iron concentrations are estimated and compared.

Adolescent↗

PubMed1997

Influence of tumor position on accuracy of endorectal ultrasound staging.

UNLABELLED: Endorectal ultrasound is a well-established method of preoperative staging of rectal neoplastic lesions. PURPOSE: This study was undertaken to evaluate whether tumor site (in terms of height) and position (with respect to the rectal circumference) have an influence on the reliability of endoluminal ultrasound staging. METHODS: From January 1991 to May 1996, 154 consecutive patients with a total of 162 rectal tumors were examined preoperatively using endorectal ultrasound. Apart from staging all tumors using the uT/uN classification, tumor level and tumor position were recorded prospectively. Neoplasms were subdivided into low rectal (0-6 cm from the anal verge), mid rectal (7-12 cm), and higher lesions (> 12 cm). Furthermore, the lumen was divided into an anterior, left lateral, posterior, and right lateral position, and all tumors, apart from circular lesions (n = 9), were subclassified accordingly. RESULTS: Overall, we found 40 (25 percent) adenomas, 15 (9 percent) T1, 29 (18 percent) T2, 67 (41 percent) T3, and 11 (7 percent) T4 lesions. Overall accuracy was 78 percent. Staging accuracy for low rectal tumors (n = 41) was 68 percent, whereas 76 and 88 percent of mid (n = 96) and high (n = 25) neoplasms were staged correctly, respectively. The difference was not statistically significant. With regard to position, 47 tumors were situated anteriorly (77 percent accuracy), 42 in the left lateral position (69 percent accuracy), 33 posteriorly (73 percent accuracy), and 31 in the right lateral position (81 percent accuracy). Differences did not reach statistical significance. CONCLUSION: Endorectal ultrasound is currently the best method for preoperative assessment of the depth of infiltration of rectal tumors. However, rectal anatomy seems to affect staging accuracy in the lower rectum because the structure of the ampulla recti renders endosonographic examination more difficult. In addition, endosonographic layers are less well defined at this level. Both factors contribute to a lower reliability and predictive value of endorectal ultrasound staging in the lower rectum, although statistical significance was not reached in this study. On the other hand, tumor position with respect to rectal circumference does not influence the predictive value of endorectal ultrasound.

Endosonography↗

PubMed1987

Accuracy of suture techniques of surgeons with different surgical experience.

The pinpoint accuracy in the suturing techniques of 35 surgeons was measured by the distance deviated from an expected needle exit. The grip of the needle holder used by the surgeons was their habitual one. Accuracy was tested using two ways of suturing; namely with, and without wavering a needle to aim at an exit after suturing began. Where the surgeons did not waver the needle, accuracy improved both when the surgical experience was greater than one year (p less than 0.05) and again when the experience exceeded 10-15 years (not significant). Difference of the accuracy between individual surgeons disappeared in those surgeons with 15 to 20 years experience. Where the surgeons wavered the needle, improvement was more marked in the former period and less in the latter. Wavering improved the accuracy in each group (p less than 0.01), but with the possible danger of injuring tissue. In conclusion, accuracy was not as precise as most surgeons' confidence believed. A significant improvement was observed with 1-year experience, but the improvement thereafter was poor. Fifteen to 20 years experience was not enough to acquire a suturing technique not necessitating needle wavering in the tissue, still yielding a 1.7 mm deviation in a 2 cm suture-stride. It was however enough to eliminate surgeons' individual differences in accuracy.

General Surgery↗

PubMed2002

Effects of nicotine and mecamylamine on choice accuracy in an operant visual signal detection task in female rats.

RATIONALE: During the past decade, central nicotinic systems have been shown in both experimental animals and humans to play an important role in cognitive function. However, the way in which specific aspects of cognitive function are affected by nicotinic systems has remained unclear. In humans, the most pronounced action of nicotine is to improve attention, but in rats, memory improvement is more easily seen. This may be due to differences in methods for assessing attention in rats and humans or to species differences in the roles of nicotinic systems in cognitive function. In the current study, we explored the effects of nicotine and mecamylamine using an operant visual signal detection task designed to model sustained attention processes common to rats and humans. METHODS: Adult female rats ( n=35) were trained to perform the signal detection task to a stable baseline of about 75% accuracy. The rats were then assigned to two subgroups of high and low accuracy based on overall accuracy (hits and correct rejections) at the end of training. All rats were then injected (SC, 10 min before testing) with saline or different doses of nicotine (0.0125, 0.025, 0.05, 0.1, 0.2 and 0.4 mg/kg) or the nicotinic antagonist mecamylamine (1, 2 and 4 mg/kg). RESULTS: A low dose range of nicotine (0.0125, 0.025, and 0.05 mg/kg) caused a dose-related increase in percent correct rejection. This dose range did not affect correct detections of the signal (percent hit). Higher doses of nicotine (0.1, 0.2 and 0.4 mg/kg) did not affect percent correct rejection, but did have a time-dependent effect on percent hit. Early in the session, the higher doses of nicotine reduced percent hit, whereas during the later part of the session higher doses of nicotine increased percent hit. Effects of nicotine did not differ between the high- and low-accuracy rats. Mecamylamine decreased choice accuracy, reducing both percent hit and percent correct rejection. Mecamylamine reduced percent hit in the low-accuracy rats at a lower drug dose than in the high-accuracy rats. CONCLUSIONS: These results support the involvement of nicotinic systems in attention in rats, as has been shown in humans. This rat model of sustained attention may provide a good approach to studying neural mechanisms underlying the effects of nicotinic cholinergic receptors on attention and a means to evaluate the potential of novel nicotinic agonists to counteract attentional dysfunction.

Animals↗

PubMed1997

Improvement in accuracy of delayed recall in aged and non-aged, mature monkeys after intramuscular or transdermal administration of the CNS nicotinic receptor agonist ABT-418.

ABT-418 was evaluated for its ability to enhance accuracy on a delayed matching-to-sample (DMTS) task by aged monkeys following intramuscular administration, and in non-aged mature monkeys following transdermal application. Aged monkeys were impaired in their performance of the DMTS task such that the longest delay intervals performed at above-chance levels extended only to 20 s. In contrast, for non-aged, mature animals, delay intervals extended to 140 s. In aged monkeys, the response to ABT-418 was highly individualized with animals responding to one or more doses in the range of 2-259 nmol/kg. A systematic dose-dependent enhancement of DMTS accuracy was not observed. When the individualized "best dose" was administered on a separate occasion, overall DMTS accuracy was increased by 12.6%. By 24 h after administration, accuracy was at control levels. In young monkeys, a significant dose-dependent enhancement of DMTS performance (an overall increase of 11.25% above baseline accuracy) was observed 5 h after application of a transdermal patch designed to maintain steady-state plasma levels of ABT-418 of 40-60 ng/ml over a 24-h period. Again there was some individual responsiveness to one of the three doses. When data included only the individualized best doses of ABT-418 for each animal, a similar enhancement of accuracy was observed for both the 5-h and 24-h test intervals. In neither the aged nor the young cohorts was enhancement of performance associated with altered response latencies or with any overt side effects of ABT-418. Thus, these data are consistent with the ability of ABT-418 to improve DMTS performance in both young and aged monkeys. In aged monkeys, this response was observed only after administration of individualized optimal doses for different monkeys. In young monkeys, a more systematic enhancement of DMTS accuracy was observed. Further, transdermal delivery of ABT-418 in non-aged monkeys demonstrated prolonged performance enhancement compared with IM injection to at least 24 h after patch administration.

Administration, Cutaneous↗

PubMed2004

Surface-based registration accuracy of CT-based image-guided spine surgery.

Registration is a critical and important process in maintaining the accuracy of CT-based image-guided surgery. The aim of this study was to evaluate the effects of the area of intraoperative data sampling and number of sampling points on the accuracy of surface-based registration in a CT-based spinal-navigation system, using an optical three-dimensional localizer. A cadaveric dry-bone phantom of the lumbar spine was used. To evaluate registration accuracy, three alumina ceramic balls were attached to the anterior and lateral aspects of the vertebral body. CT images of the phantom were obtained (1-mm slice thickness, at1-mm intervals) using a helical CT scanner. Twenty surface points were digitized from five zones defined on the basis of anatomical classification on the posterior aspects of the target vertebra. A total of 20 sets of sampling data were obtained. Evaluation of registration accuracy accounted for positional and rotational errors. Of the five zones, the area that was the largest and easiest to expose surgically and to digitize surface points was the lamina. The lamina was defined as standard zone. On this zone, the effect of the number of sampling points on the positional and rotational accuracy of registration was evaluated. And the effects of the additional area selected for intraoperative data sampling on the registration accuracy were evaluated. Using 20 surface points on the posterior side of the lamina, positional error was 0.96 mm +/- 0.24 mm root-mean-square (RMS) and rotational error was 0.91 degrees +/- 0.38 degrees RMS. The use of 20 surface points on the lamina usually allows surgeons to carry out sufficiently accurate registration to conduct computer-aided spine surgery. In the case of severe spondylosis, however, it might be difficult to digitize the surface points from the lamina, due to a hypertrophic facet joint or the deformity of the lamina and noisy sampling data. In such cases, registration accuracy can be improved by combining use of the 20 surface points on the lamina with surface points on other zones, such as on the both sides of the spinous process.

Analysis of Variance↗

PubMed2026

Evaluation of a cornea-specialized large language model for diagnostic and management accuracy in complex corneal cases.

PURPOSE: To evaluate whether a cornea-specialized large language model (LLM) enhanced with retrieval-augmented generation (RAG) improves clinicians' diagnostic and management accuracy in complex corneal cases compared to a general-purpose GPT-4o model and unaided clinician performance. METHODS: This prospective, randomized, masked evaluation study involved three cornea trainees who each independently reviewed 39 real-world corneal cases under three experimental conditions: unaided, GPT-4o-assisted, and assisted by a cornea-specialized GPT-4o model. The cornea-specialized model was constructed by embedding over 200 publicly available Wikipedia articles into GPT-4o's RAG framework. Participants provided open-ended diagnoses and selected the next-step management options (multiple choice). They were allowed up to three GPT-4o queries per case, and the AI-assisted arms were randomized to minimize bias. Accuracy for both tasks was compared against expert reference standards using McNemar's test. RESULTS: Diagnostic accuracy was 48.7%, 20.5%, and 38.5% unaided, improving to 69.2%, 46.2%, and 59.0% with general GPT-4o (p<0.04). The cornea-specialized GPT-4o further improved accuracy to 71.8%, 48.7%, and 74.4%, with improvements over unaided performance for all clinicians (p<0.01). For next-step decisions, unaided accuracy was 76.9%, 87.2%, and 59.0%. With the specialized model, Ophthalmologist 3 improved to 71.8% (p<0.05), Ophthalmologist 1 remained high at 82.1%, and Ophthalmologist 2 declined to 64.1% (p<0.05). CONCLUSIONS: A cornea-specialized LLM enhanced with RAG improved diagnostic accuracy in complex corneal cases, particularly among clinicians with lower baseline performance. Effects on management accuracy were inconsistent. Future studies should explore the use of open-ended management tasks and examine whether smaller, curated retrieval corpora yield better model performance.

Humans↗

PubMed1988

Comparative accuracy of clinical tests for diagnosis and prognosis of coronary artery disease.

The discriminant accuracy of 14 variables derived from clinical evaluation, cardiac fluoroscopy, exercise electrocardiography, thallium scintigraphy and radionuclide angiography was assessed with respect to the diagnosis of angiographic coronary artery disease (CAD) among 607 patients undergoing coronary angiography, and with respect to the prognosis of subsequent cardiac death or nonfatal infarction among 4,104 patients followed for 1 year after testing. Discriminant accuracy (quantified in terms of the area under a receiver-operating characteristic curve for each variable) ranged from 50 to 73% for diagnosis, and from 54 to 77% for prognosis. Although there was a great deal of variability from test to test, variables representing direct or indirect manifestations of myocardial ischemia tended to correlate better with prognosis. Thus, variables derived from radionuclide angiography and thallium scintigraphy tended to have more prognostic accuracy than diagnostic accuracy, while fluoroscopy tended to have more diagnostic accuracy than prognostic accuracy. The pattern associated with clinical evaluation and exercise electrocardiography was less discernable. Accordingly, the accuracy of noninvasive tests with respect to diagnosis and prognosis of CAD should be separately determined based on individual empiric observation.

Adult↗

PubMed1994

Precision and accuracy of stereotactic convergent beam irradiations from a linear accelerator.

PURPOSE: The accuracy and the precision for radiosurgery procedures at linear accelerator facilities were investigated. METHODS AND MATERIALS: The technique of convergent beam irradiation, that is a series of successive isocentric arc irradiations, is specifically considered in this paper. Accuracy and precision depend on a sequence of methods and equipment among which localization of the target, patient alignment, and the dose delivery are the most critical steps. The purpose of the investigation was to quantitatively assess their contribution to the overall accuracy. The definitions and methods used to quantify and control accuracy are described. Measurements were carried out at a phantom to analyze the localization and positioning errors. Errors which may occur with the dose delivery technique were studied by a computer simulation. RESULTS: The calculations showed that these errors are not the main contributors to the overall accuracy as long as the linac inaccuracies are in the order or less than 1 mm. The accuracy found in the localization and positioning methods was less than 1 mm. CONCLUSION: It was concluded that an overall accuracy in the order of 1 mm can be obtained also under routine conditions. The great importance of adequate quality control is emphasized.

Humans↗