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PubMedDate not supplied

The accuracy of endoscopic ultrasound, endoscopic retrograde cholangiopancreatography, computed tomography, and transabdominal ultrasound in the detection and staging of primary ampullary tumors.

BACKGROUND/AIMS: To compare the accuracy between EUS (endoscopic ultrasound), ERCP (endoscopic retrograde cholangiopancreatography), CT (computed tomography), and transabdominal US (ultrasound) in the detection and staging of primary ampullary tumors. We will also try to discuss the influence of endobiliary stent on EUS in staging ampullary tumors. METHODOLOGY: Twenty-one patients with ampullary tumors were evaluated by EUS, ERCP, CT, and US before operation. The accuracy was assessed with TNM staging and compared with the surgical-pathological findings. RESULTS: EUS was superior to CT and US in detecting ampullary tumors, but EUS and ERCP are of similar sensitivity (EUS 95%, ERCP 95%, CT 19%, US 5%). EUS was superior to CT and US in T staging (EUS 75%, CT 5%, US 0%) and detecting lymph node metastasis (EUS 50%, CT 33%, US 0%) of ampullary tumors. The accuracy of EUS in T and N staging of ampullary tumors tended to be decreased in the presence of endobiliary stent (stenting: T 71%, N 75%; nonstenting T 83%, N 100%), but there was no statistical significance. CONCLUSIONS: EUS was superior to CT and US in assessing primary ampullary tumors, but it was not significantly superior to ERCP in detecting ampullary tumors. The presence of endobiliary stent may decrease the accuracy of EUS in staging ampullary tumors.

Aged↗
PubMed2002

Monte Carlo simulation studies of EEG and MEG localization accuracy.

Both electroencephalography (EEG) and magnetoencephalography (MEG) are currently used to localize brain activity. The accuracy of source localization depends on numerous factors, including the specific inverse approach and source model, fundamental differences in EEG and MEG data, and the accuracy of the volume conductor model of the head (i.e., the forward model). Using Monte Carlo simulations, this study removes the effect of forward model errors and theoretically compares the use of EEG alone, MEG alone, and combined EEG/MEG data sets for source localization. Here, we use a linear estimation inverse approach with a distributed source model and a realistic forward head model. We evaluated its accuracy using the crosstalk and point spread metrics. The crosstalk metric for a specified location on the cortex describes the amount of activity incorrectly localized onto that location from other locations. The point spread metric provides the complementary measure: for that same location, the point spread describes the mis-localization of activity from that specified location to other locations in the brain. We also propose and examine the utility of a "noise sensitivity normalized" inverse operator. Given our particular forward and inverse models, our results show that 1) surprisingly, EEG localization is more accurate than MEG localization for the same number of sensors averaged over many source locations and orientations; 2) as expected, combining EEG with MEG produces the best accuracy for the same total number of sensors; 3) the noise sensitivity normalized inverse operator improves the spatial resolution relative to the standard linear estimation operator; and 4) use of an a priori fMRI constraint universally reduces both crosstalk and point spread.

Algorithms↗
PubMed2002

Do resemblance ratings measure the accuracy of facial approximations?

Since forensic facial approximations are used to promote recognition of a deceased person, an accurate forensic facial approximation (FFA) should be easily recognized as the person to whom the skull belonged (target individual). However, the accuracy of FFAs has been previously assessed by the direct comparison of an FFA to the corresponding target individual for similarity (i.e., a resemblance rating). Resemblance ratings may not indicate a facial approximation's accuracy since the resemblance of non-target individuals is not accounted for. This experiment tests the validity of using resemblance ratings to assess the accuracy of FFAs. The study indicates that there is no statistically significant difference between: (a) resemblance ratings of FFAs to target individuals and (b) resemblance ratings of FFAs to individuals incorrectly identified as the target individual. It is concluded that it is not possible from resemblance ratings to determine the accuracy and/or quality of a facial approximation since a non-target individual may receive a resemblance rating equal to, or higher than, the target individual.

Cephalometry↗
PubMed2002

Estrogen improves response accuracy and attenuates the disruptive effects of delta9-THC in ovariectomized rats responding under a multiple schedule of repeated acquisition and performance.

Despite evidence of an interaction between cannabinoids and estrogen in the brain, little information is available regarding the consequences of this interaction on behavior. A within-subjects design was used to examine the effects of estrogen and delta9-tetrahydrocannabinol (delta9-THC) on learning and memory in ovariectomized rats responding under a multiple schedule of repeated acquisition and performance. Treatment with low physiological levels of estrogen, delivered in Silastic capsules, improved response accuracy without affecting response rate during acquisition. Estrogen also attenuated the ability of delta9-THC (0.56- 3.2 mg/kg) to decrease response accuracy and rate during acquisition and response accuracy during performance. Results indicate that estrogen can improve accuracy during acquisition of a nonspatial operant task and can attenuate delta9-THC- induced behavioral deficits.

Animals↗
PubMed2002

The influence of head movement on the accuracy of a rapid pointing task.

BACKGROUND: Eye-hand coordination contributes to sports performance. The positive effect of head movement on the accuracy of eye-hand coordination of some subjects has been demonstrated for self-paced or single tasks, but not for rapid, repetititive tasks, such as those sometimes required in sports. The purpose of this study was to determine whether head movement is detrimental to performance of a rapid, repetitive pointing task. METHODS: Pointing accuracy and speed were tested using the AcuVision 1000 trainer, a device designed to assess and train eye-hand coordination. Twenty-six subjects participated. In one trial, subjects were told to turn their heads toward the targets as they pointed at them. In a second trial, subjects were told to keep their heads stationary as they pointed at the targets. The order of the trials was counter-balanced and subjects were randomly assigned to one of the orders. RESULTS: Pointing accuracy was significantly greater in the head movement trial than in the no head movement trial. CONCLUSIONS: Head movement increased the accuracy of this rapid task. Head movement probably allows more-accurate encoding of target position by maintaining the eyes in less-eccentric positions of gaze.

Adolescent↗
PubMed2002

Adjusted clinical groups: predictive accuracy for Medicaid enrollees in three states.

Actuarial split-sample method were used to assess predictive accuracy of adjusted clinical groups (ACGs) for Medicaid enrollees in Georgia, Mississippi (lagging in managed care penetration), and California. Accuracy for two non-random groups--high-cost and located in urban poor areas--was assessed. Measures for random groups were derived with and without short-term enrollees to assess the effect of turnover on predictive accuracy. ACGs improved predictive accuracy for high-cost conditions in all States, but did so only for those in Georgia's poorest urban areas. Higher and more unpredictable expenses of short-term enrollees moderated the predictive power of ACGs. This limitation was significant in Mississippi due in part, to that State's very high proportion of short-term enrollees.

Actuarial Analysis↗
PubMed2000

Accuracy of cytological findings in abnormal cervical smears by cytohistologic comparison.

To investigate the accuracy rates of cytology in abnormal cervical smears and the factors contributing to a discrepant diagnosis between cytology and histology repots of cervical intraepithelial and invasive neoplasm. During the four-year period 1993 to 1996, abnormal cervical smear findings, which were followed by cervical biopsy, were available in 709 patients. The cytology and histology slides were reviewed in each case. The accuracy rates of cytology before and after review were investigated. The accuracy rate of cytology was 48%. Following review it became 56%, mainly due to a reduction in the number of cases in which the smear showed a lesser degree of CIN than did the biopsy. The proportion of cases in which the cytological impression of CIN was more severe than the histology was minimally altered. The results suggest that difficulty in the interpretation of cervical smear as well as sampling errors are responsible for reduced accuracy even in smears which are considered representative of the pathological process.

Adenocarcinoma↗
PubMed2003

Use of a dual-head coincidence camera and 18F-FDG for detection and nodal staging of non-small cell lung cancer: accuracy as determined by 2 independent observers.

UNLABELLED: The accurate detection of lung carcinoma and the determination of its stage remain significant clinical problems. (18)F-FDG PET has been shown to improve detection and staging of lung cancer and to prevent unnecessary invasive procedures. Positron imaging with dual-head gamma cameras may not be as sensitive as PET, but recent studies have shown good results with these cameras. METHODS: In the present study, we investigated 100 patients, 76 of whom were male and 24 female (mean age +/- SD, 60.7 +/- 9.4 y), with suspected non-small cell lung cancer. (18)F-FDG scanning was performed using a dual-head coincidence camera 1 h after the intravenous injection of 185 MBq of (18)F-FDG. For 46 patients, attenuation correction was also performed. Two independent observers unaware of clinical status analyzed all imaging studies. TNM classification was assigned after surgical staging. RESULTS: In 44 patients with clinically suspected bronchogenic carcinoma, no evidence of malignancy was found. However, in 56 patients a pulmonary neoplasm was demonstrated. At interobserver analysis, a kappa value of 0.94 (P < 0.0001) was found for detection of the primary tumor and a kappa value of 0.63 (P < 0.0001) was found for mediastinal staging. A sensitivity of 96%, a specificity of 93%, and an accuracy of 95% were found for detection of pulmonary neoplasm. Assessment of lymph node involvement showed a sensitivity of 50%, a specificity of 92%, and an accuracy of 77%. The sensitivity of CT in assessing lymph node involvement was 36%, the specificity was 86%, and the accuracy was 67%. Attenuation correction provided more anatomic information, but no differences were seen between attenuation-corrected and non-attenuation-corrected images for detecting lesions or lymph node involvement. CONCLUSION: The present study confirms earlier data showing that (18)F-FDG scans obtained with dual-head coincidence cameras are useful in the detection of non-small cell lung cancer and less suitable for staging of lymph node involvement, with accuracy comparable to that of CT.

Carcinoma, Non-Small-Cell Lung↗
PubMedDate not supplied

Total occlusion versus hairline residual lumen of the internal carotid arteries: accuracy of single section helical CT angiography.

BACKGROUND AND PURPOSE: Routine carotid sonography and MR angiography cannot reliably detect the markedly reduced flow velocities associated with very severe carotid stenosis. In this study, we sought to evaluate the accuracy of single row detector helical CT angiography in distinguishing hairline residual lumen from total occlusion of severely stenosed internal carotid arteries (ICAs). METHODS: From our departmental data base of single row detector CT angiography studies performed for evaluation of ICA occlusive disease, 21 cases were identified with evidence of either hairline residual lumen or total occlusion on correlative conventional catheter radiographic arteriograms; these included seven cases of proved hairline residual lumen and 14 cases of proved total occlusion. Two neuroradiologists, blinded to the radiographic arteriography results, graded the diseased ICA on each CT angiogram as definitely occluded, probably occluded, indeterminate, probably patent, or definitely patent. Receiver operating characteristic curves were generated for each neuroradiologist. RESULTS: At an operating point on the receiver operating characteristic curve corresponding to 90% sensitivity, the first reader achieved 95% specificity and the second reader achieved 80% specificity for distinguishing hairline residual lumen from total occlusion. Absolute accuracy rates were 95% and 85%, respectively. No significant difference in accuracy was observed between the two readers (P =.28, two-tailed t test). CONCLUSION: Single row detector CT angiography can distinguish total ICA occlusion from hairline residual lumen with a high degree of accuracy. In equivocal cases, conventional catheter arteriography may be desirable to confirm the diagnosis.

Aged↗
PubMed2003

Accuracy of international normalized ratio determined by portable venous-blood coagulation monitor versus a central laboratory.

BACKGROUND: The CoaguChek is a portable monitor unit for measuring the international normalized ratio (INR). The purpose of the study was to evaluate the accuracy of a portable prothrombin time (PT) monitor (CoaguChek, Roche Diagnostics, Mannheim, Germany) compared with the laboratory method. MATERIAL AND METHOD: Paired venous blood INRs were performed in 220 consecutive outpatient tests mainly in anticoagulated (n = 210) and non-anticoagulated (n = 10) individuals. Accuracy was evaluated in 220 tests by parallel assessment of INRs (CoaquChek and laboratory). Accuracy was determined using statistic regression analysis and clinical agreement (expanded and narrow criteria). Agreement in dual INR measurement also was evaluated as a function of increasing INR. RESULTS: The CoaguChek significantly correlated with the laboratory measurement (r = 0.89). The proportion of dual INR measurements that satisfied the clinical relevant expanded, and narrow agreement criteria was 90 per cent and 86 per cent respectively. Eighty-two per cent of all dual measurements were within 0.5 INR units. The accuracy of the portable monitor was greatest for INR values less than 3.0; above this INR level the portable monitor overestimated laboratory INR values. CONCLUSIONS: The CoaguChek is an accurate alternative to laboratory assessment of INR at values < 3.0. The authors suggest the use of the monitor in non anticoagulated patients or anticoagulated patients at values less than 3, as most physicians in Thailand prefer lower INR than in Western countries.

Aged↗
PubMedDate not supplied

Effect of illumination on the accuracy of identifying interproximal carious lesions on bitewing radiographs.

BACKGROUND: Dentists generally use a viewbox as the primary source of illumination when examining radiographs. Secondary sources of illumination (i.e., light other than that originating from the viewbox) can reduce radiographic contrast and may therefore affect diagnostic accuracy. OBJECTIVE: To determine if the accuracy of identifying interproximal carious lesions on bitewing radiographs depends on the level of secondary illumination. METHODS: Fourteen dentists examined bitewing radiographs of simulated interproximal lesions on dentition phantoms in conditions of maximal secondary illumination (the light condition) and minimal secondary illumination (the dark condition). RESULTS: There was no significant difference (p = 0.07) in the accuracy of identifying simulated interproximal carious lesions on bitewing radiographs in the light mean accuracy (72%+/-12%) and dark (75% +/- 12%) conditions. CLINICAL SIGNIFICANCE: Examining bitewing radiographs on a viewbox located in the operatory is adequate for accurately identifying interproximal carious lesions.

Dental Caries↗
PubMed2000

Diagnostic accuracy of mammography and scintimammography in detection of primary breast cancer related size of the tumour.

BACKGROUND: The detection of breast cancer relies on physical examination and mammography (XMM). The sensitivity of conventional imaging is lesions-size dependent. However, mammography has good sensitivity in small tumours when microcalcification is present, but the sensitivity is relatively low in other small tumours. The use of scintimammography with Tc-99m sestaMIBI (SMM) may be helpful in this situation. The aim of this study is to compare the diagnostic accuracy of mammography and scintimammography across all groups with different sizes of lesions. METHODS: Data for 273 patients aged 26 to 84 years (mean 52; SD 12) with 298 lesions were analysed. All lesions were removed and final histology and pathological size of the tumours were retrospectively reviewed (mean size 2.9 cm, SD 2.4 cm). All patients had XMM and SMM. Each imaging study was graded using five grades of certainty. SMM images were reviewed by an independent specialist blinded to clinical presentation and XMM results. The diagnostic accuracy of each test, overall and by each lesions size subgroup, was compared using receiver operating characteristic curve (ROC) analysis. RESULTS: The sensitivity of scintimammography was consistently high across all size groups; overall 89% (82?100%) compared with 68% (51?88%) for mammography. In those tumours below 2 cm, the area under the ROC was significantly larger with SMM than XMM (p < 0.05), with 80% certainty indicative of greater diagnostic accuracy. Also in all patients the area under the ROC was significantly larger with SMM than XMM (p < 0.05), with 90% certainty indicative of greater diagnostic accuracy. In other groups of lesions size the area under ROC for SMM was larger in lesions size between 2 and 4 cm and slightly smaller in lesions over 4 cm, but it was not significant. CONCLUSION: Scintimammography using Tc-99m sestaMIBI seems to be a sensitive and consistently reliable diagnostic test for breast cancer independent of the size of the tumour.

Journal Article↗
PubMed2003

Accuracy of three diagnostic tests used alone and in combination for detecting Helicobacter pylori infection in patients with bleeding gastric ulcers.

OBJECTIVE: Accuracy of diagnostic methods for detecting Helicobacter pylori (H. pylori) infection among patients with bleeding peptic ulcers has not been thoroughly investigated. The aim of this study was to compare the diagnostic tests and their combined usage in detection of H. pylori infection in patients with bleeding gastric ulcers and without the use of nonsteroidal anti-inflammatory drugs. METHODS: A total of 57 patients who presented with bleeding gastric ulcers by endoscopy were enrolled. The status of H. pylori was identified by performing the rapid urease test (RUT), histology and (13)C-labeled urea breath test (UBT). The criteria for having H. pylori infection was a minimum of two positive tests. RESULTS: The prevalence of H. pylori infection in our patient group was 80.7%. Among the three tests used: RUT, histology, and UBT, sensitivities were 56.5%, 97.8% and 100%, while specificities were 100%, 45.5% and 81.8%, respectively. The overall accuracies of the tests were 78.3%, 71.6% and 90.9%, respectively. Although UBT obtained significantly higher accuracy than histology (P = 0.02) as opposed to RUT (P = 0.11), UBT had significantly higher sensitivity than RUT (P < 0.001). In terms of combining any two of the three tests, more accuracy (98.9%) was achieved when both UBT and histology were used to confirm the diagnosis of the other. Conversely, failure to use combined tests generated the potential of missing a proper H. pylori diagnosis. CONCLUSIONS: UBT is superior to the other two tests in bleeding gastric ulcers. RUT lacks sensitivity for detection of H. pylori infection. However, the concomitant use of UBT and histology seems to be more accurate when gastric ulcers present with bleeding.

Adolescent↗
PubMed2003

Investigation on the accuracy of the blood glucose monitoring device Prestige IQ.

The aim of this study was to investigate the accuracy and reliability of the blood glucose self-monitoring system Prestige IQ (Home Diagnostics, Inc., Ft. Lauderdale, USA) in comparison to an established blood glucose reference method and four commercially available blood glucose self-monitoring devices. Over a 3-month period, 61 patients with Type 1 (T1DM) and Type 2 diabetes mellitus (T2DM) participated in this study. The patients entered the study clinic for two visits. Each visit consisted of 7 glucose determinations in samples of capillary whole blood drawn from the fingertip. The first and last measurements were determined using the laboratory reference and the mean of both readings was used as the reference value for statistical analysis. The 5 remaining glucose measurements were performed in randomized order using the 5 commercially available blood glucose devices. One hundred twenty-one data sets were generated and used to evaluate accuracy. Prestige IQ blood glucose results obtained from the fingertip agreed well with the laboratory reference (linear regression analysis: slope = 1.016; intercept = 0.4 mg/dl; SD = 13.555 mg/dl; correlation r = 0.972) and were comparable to the results generated using the other four blood glucose devices. Bland-Altman analysis for reliability confirmed that 119 out of 121 Prestige IQ results (98.3%) exhibited acceptable accuracy as defined in the new ISO/DIS guideline 15197.2 (85.1-99.2% in this area for the other devices). Error-grid-analysis shows all Prestige IQ glucose results in clinically acceptable zones A and B (95.9% in zone A and 4.1% in zone B). In conclusion, Prestige IQ showed excellent performance with clinically acceptable accuracy and reliability as compared to both the laboratory reference and the four commercially available self-monitoring blood glucose systems.

Aged↗
PubMed2004

Accuracy of transvaginal ultrasound for the evaluation of myometrial invasion in endometrial carcinoma.

OBJECTIVE: To evaluate the accuracy of transvaginal ultrasound for the evaluation of myometrial invasion in endometrial carcinoma in comparison with standard paraffin section. METHOD: A total of 111 patients with endometrial carcinoma diagnosed from fractional curettage underwent pre-operative transvaginal ultrasonography to assess myometrial invasion. Operation for surgical staging was subsequently performed and the hysterectomy specimen was evaluated for depth of myometrial invasion by standard paraffin section blinded from transvaginal ultrasound results. Final histopathologic diagnosis and depth of myometrial invasion were obtained from standard paraffin section. Ultrasonographic assessment was compared with the histopathological results. RESULTS: In evaluation of myometrial invasion, transvaginal ultrasound yielded the sensitivity of 69.4 per cent, specificity of 70.6 per cent, positive predictive value of 53.2 per cent, negative predictive value of 82.8 per cent, and accuracy of 70.3 per cent. The accuracy, sensitivity, specificity, negative predictive value, false positive and negative rates were comparable between grade 3 and grade 1 and 2 tumors. However, the positive predictive value was significantly higher among grade 3 than grade 1 and 2 tumors. The Kappa coefficients were 0.57 and 0.22 for grade 3 and grade 1 and 2 tumors respectively. CONCLUSION: Transvaginal ultrasound for assessment of depth of myometrial invasion in endometrial carcinoma provided acceptable accuracy compared with standard paraffin section. This technique might be of value for the decision making in the intra-operative management of endometrial carcinoma.

Carcinoma, Endometrioid↗
PubMed2004

99mTc-HMPAO-leukocyte scintigraphy in patients with symptomatic total hip or knee arthroplasty: improved diagnostic accuracy by means of semiquantitative evaluation.

UNLABELLED: The aim of this study was to evaluate the diagnostic value, in suspected infectious prostheses, of (99m)Tc-labeled hexamethylpropyleneamine oxime ((99m)Tc-HMPAO) leukocyte scintigraphy interpreted with the addition of a semiquantitative analysis. METHODS: By means of a retrospective review, we included a group of 78 consecutive patients with suspected hip or knee prosthesis infection. We performed 91 (99m)Tc-HMPAO-leukocyte scintigraphies and examined 95 localizations that were suspect. Images were acquired at 3 different time points after the injection of the labeled leukocytes: 50 min (early images), 4 h, and 24 h (late images). The scintigraphic examinations were independently evaluated by 3 observers; qualitative and semiquantitative analyses were performed. The final diagnosis of infection was based on surgical, histologic, and bacteriologic data and follow-up. RESULTS: On qualitative analysis, sensitivity, specificity, and accuracy were 80.4%-87%, 65.3%-71.4%, and 75.8%-77.9%, respectively. On semiquantitative analysis, sensitivity, specificity, and accuracy were 95.6%, 95.8%, and 95.8%, respectively. The analysis of 95% confidential intervals showed statistically significant differences in specificity and accuracy between semiquantitative and qualitative analyses. CONCLUSION: In those patients who underwent (99m)Tc-HMPAO-leukocyte scintigraphy for suspected hip or knee prosthesis infection, the addition of a semiquantitative evaluation to the qualitative analysis of early and late images leads to a significant improvement in both specificity and accuracy.

Adult↗
PubMed2004

Routine controls for the geometric accuracy assessment of MR images used in neurosurgery.

AIM: This paper describes the methodology we set up in our hospital to investigate whether or not the MR images from our MRI device are geometrically reliable for use as reference images in stereotactic neurosurgery procedures. In fact, in these clinical procedures geometric accuracy is a prime concern. MRI is often the only diagnostic methodology by which the pathology of interest is detectable. On the other hand, the physical measurements on which this technology lies do non guarantee geometrical accuracy. METHODS: So we set up a measurement protocol to assess the geometric accuracy of an MR image. To reach this goal we use a self-designed phantom. On this simple phantom, simulating a human head, the stereotactic ring used for neurosurgical procedures was mounted. We made acquisitions in CT and MRI, and compared the images found. RESULTS: Our findings were that, with our MRI device, the geometric accuracy obtained depends only on the acquisition matrix used, and is not affected by other technological factors. CONCLUSION: The method here described can be used in any site where stereotactic neurosurgical procedures are applied on the basis of MR images, as it is simple and cheap, both from an economic point of view, and from a machine-time and personnel-time point of view.

Image Processing, Computer-Assisted↗
PubMedDate not supplied

Accuracy and precision of a system for assessing severity of tooth wear.

PURPOSE: The purpose of this study was to introduce a computer-assisted quantitative tooth wear-analyzing system and test its accuracy and precision. MATERIALS AND METHODS: An image of a horizontally projected dental arch was captured, and the facet area of each tooth was calculated using a digital image analyzer. For normalization, the facet area of the individual tooth was divided by the total area of the corresponding tooth; this result was the tooth wear score. The accuracy and precision of this method were determined through the intraclass correlation coefficient using 10 dental casts. Tooth wear on the dental casts of 50 subjects was actually measured. RESULTS: The accuracy of the tooth wear score determined by a newly trained examiner was greater than 0.85 of the intraclass correlation coefficient; this was tested against the score determined by consensus of three experienced examiners. The reproducibility within a 1-week interval was also greater than 0.85. With regard to the tooth wear score from 50 sets of dental casts, the distribution of tooth wear was generally consistent with data reported in the literature. CONCLUSION: The results suggest that the newly trained examiner can exhibit adequate accuracy and precision after appropriate training in identifying tooth wear facets. Recorded data from 50 subjects added face validity to this new system.

Adult↗