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At least 757 records · Page 42Linked to original sources

PubMed1998

Image analysis combined with visual cytology in the early detection of recurrent bladder carcinoma.

BACKGROUND: Early detection of recurrent transitional cell carcinoma of the bladder (TCC) is important to permit early treatment, which produces maximal preservation of the bladder and maximum survival. METHODS: This retrospective cohort study attempted to determine the period of time over which urinary DNA image analysis combined with visual cytology is useful in the early detection of recurrent TCC of the bladder. The authors believe this study is unique in that it measured the effectiveness of this test (image analysis plus visual cytology combined) at varying times before clinical diagnosis of recurrence was made. The cohort was comprised of 175 urologic patients from urologic practices across the U.S. Data, collected between January 1991 and February 1994, included cystoscopy, biopsy, DNA image analysis, and visual cytologic reports. RESULTS: Sixty patients in the cohort were found to have active TCC whereas 115 patients had a history of, but no active, disease during the follow-up period. As expected, the sensitivity and specificity of DNA image analysis in combination with visual cytology, and DNA image analysis alone, were greatest when urinary samples were obtained close to the time of diagnosis. In general, the longer the interval from the combined tests to the time of diagnosis, the lower the sensitivity. The combined tests had predictive value up to 3 months prior to clinical diagnosis when any detectable cytologic abnormality was considered positive. At the optimal cutoff points as determined from receiver operating characteristic curves, sensitivity increased when DNA image analysis was supplemented with visual cytology. CONCLUSIONS: The combination of DNA image analysis and visual cytology provides a better method for the early detection of recurrent TCC than DNA image analysis alone. This test potentially may be useful in providing information regarding bladder tumor recurrence up to 3 months prior to clinical evidence of disease.

Adult↗

PubMed2003

[Three dimensional gait analysis and controlling spastic foot on stroke patients].

INTRODUCTION: The purpose of this work is to assess the interest of three dimensional gait analysis in measuring the effect of orthesis and of selective tibial neurotomy without visual analysis. METHOD: After clinical examination, gait in the two groups was recorded by a three dimensional motion system (Vicon-Oxford Metrics) with free velocity. The gait of ten stroke patients was compared bare-foot and with ankle-foot orthesis. The gait of nine stroke patients was compared bare-foot before and six month after selective tibial neurotomy. Kinematics data were studied in the sagittal plane, and muscular electrical activity was detected on the affected side by a ten-channel telemetry system using surface electrodes. An analogic visual scale ( EVA) was used by the patient, to assess discomfort during walking. RESULTS: In the "orthesis" group, calf spasticity was 2.5 on the Ashworth scale. With ankle-foot orthesis, the walking discomfort on EVA was significantly reduced from 4.25 to 1.16. Gait speed increased significativelly at 0.42 m s(-1) to 0.59 m s(-1). In swing phase, equinus disappeared. In stance phase equinus and recurvatum were controlled, anterior pelvic tilt decreased and hip extension increased. In the "neurotomy" group, 6 months after the tibial neurotomy, calf spasticity decreased from 3.4 to 0. The walking discomfort on EVA, was significantly reduced from 5.97 to 3.6. Gait speed increased from 0.51 m s(-1) to 0.54 m s(-1). Ankle dorsiflexion on the affected side, was possible during stance for five patients and residual motricity was released during swing phase for two patients. Stance knee recurvatum was corrected in five patients. CONCLUSION: Three dimensional analysis specifies the functional gait disability in stroke patients. It specifies the degree of correction provided by orthesis or tibial neurotomy in the various gait cycle phases and the impact on the superior joints.

Adult↗

PubMed1999

Pitfalls in the analysis of electrogastrographic recordings.

Electrogastrography (EGG) is a noninvasive method to study gastric myoelectrical activity in humans. Because frequency characteristics are the most reliable parameters and visual analysis of the EGG recordings is notoriously difficult, automated frequency analysis, especially running spectrum analysis, is often used. However, EGG frequency spectra can be misinterpreted easily. Movement artifacts and noise from various sources can result in abnormal frequency spectra with significant power in the low-frequency and high-frequency range, or even make the EGG completely uninterpretable. Signals that differ from a sinusoid waveform have harmonics in the high-frequency range of the spectrum and may be interpreted as abnormal. Visual inspection of raw signals and frequency spectra remains essential in the analysis of EGG signals. The value of computerized analysis should not be overrated. EGG is an important research tool, but a clinical role still needs to be established.

Animals↗

PubMed1986

New techniques for the analysis of the human sleep-wake cycle.

Two new techniques for the analysis of the human sleep-wake cycle are presented and illustrated. The first is based on a wrist-worn solid-state activity monitor which can record movement activity for prolonged time periods. The method has been applied to document phase-shifts of the rest-activity cycle after crossing time-zones; to analyze the effect of hypnotic drugs on movements during sleep; and to record the severe disruption of sleep and waking in narcolepsy. The second technique consists of all-night spectral analysis of the sleep EEG. In addition to conventional sleep stage scoring by visual analysis, power density values of the sleep EEG are computed for 4-sec epochs in the range of 0.25-25.0 Hz. The spectra provide a more refined and quantitative description of the sleep process than analysis of the sleep stage distribution. The method revealed within individual sleep stages significant trends through the night as well as specific changes induced by sleep deprivation. Spectral analysis was also applied for determining the effect of benzodiazepine hypnotics on the sleep EEG, and for documenting subtle, residual drug effects in the following drug-free night.

Circadian Rhythm↗

PubMedDate not supplied

A comparison of the pharmacophore identification programs: Catalyst, DISCO and GASP.

Three commercially available pharmacophore generation programs, Catalyst/HipHop, DISCO and GASP, were compared on their ability to generate known pharmacophores deduced from protein-ligand complexes extracted from the Protein Data Bank. Five different protein families were included Thrombin, Cyclin Dependent Kinase 2, Dihydrofolate Reductase, HIV Reverse Transcriptase and Thermolysin. Target pharmacophores were defined through visual analysis of the data sets. The pharmacophore models produced were evaluated qualitatively through visual inspection and according to their ability to generate the target pharmacophores. Our results show that GASP and Catalyst outperformed DISCO at reproducing the five target pharmacophores.

Algorithms↗

PubMed2001

Automated assessment of dipyridamole 201Tl myocardial SPECT perfusion scintigraphy by case-based reasoning.

UNLABELLED: This study evaluated the diagnostic accuracy of case-based reasoning (CBR) to automatically detect significant coronary artery disease from dipyridamole 201Tl myocardial SPECT perfusion scintigrams. METHODS: The study population included 240 patients (182 men, 58 women; mean age +/- SD, 61 +/- 12 y) on whom coronary angiography and perfusion scintigraphy were performed within 6 +/- 11 d of each other. The patients were divided into two groups according to the presence or absence of significant coronary disease in any major coronary vessel. Regional myocardial tracer uptake was observed in 84 segments by polar map analysis. For each scintigraphic image, a CBR algorithm based on a similarity metric was used to identify similar scintigraphic images within the case library. The angiographic results of these similar cases were used to obtain the CBR reading, which was compared with the true angiographic results. Myocardial scintigrams were also analyzed by a first-generation Cedars-Sinai (CS) method, including a comparison with a reference database, and by the visual analysis of an expert reader. RESULTS: By receiver-operating-characteristic analysis, the diagnostic accuracy of CBR was not different from the interpretation by the CS algorithm and from visual interpretation (P = not significant [NS]). For detection of significant coronary disease, the respective sensitivities at 50% and 80% specificity were 90% and 67% for CBR, 88% and 65% for CS polar map analysis, and 91% and 74% for visual interpretation. For the detection of coronary disease in the vascular territories assigned to the left anterior descending and the right coronary arteries, CBR and CS polar map analysis showed similar diagnostic accuracy (P = NS). However, for detection of disease in the circumflex artery, CS polar map analysis was slightly better than CBR (P = 0.03). CONCLUSION: Automated interpretation of dipyridamole 201Tl myocardial SPECT perfusion images by CBR has diagnostic accuracy similar to that of visual interpretation or CS analysis. Thus, use of a case library that includes a variety of normal and abnormal perfusion images does not appear to have greater diagnostic power than use of reference limits.

Adult↗

PubMed1997

Evidence for rapid face recognition from human scalp and intracranial electrodes.

It is still generally believed that complex visual analysis is not carried out within the first 100 ms. Here we show that intra- and extracranial visual evoked potentials (VEPs) differentiate previously seen faces from novel faces as early as 50 ms after stimulus onset. EEG was recorded from scalp electrodes in 12 male healthy volunteers (group I) and intracranially from implanted depth electrodes in the temporal and frontal cortex of seven epilepsy patients (group II). Both groups were engaged in a face recognition task. All subjects showed significant differential responses which occurred very early (50-90 ms) and later (190-600 ms). In group II, the early responses were recorded more frequently in the right hemisphere, whereas the late differential VEPs were found in both hemispheres. Both types of VEPs were more frequent in the temporal neocortex, underlining its role as a major contributor to these fast recognition processes.

Adult↗

PubMed1999

Flow visualization study to improve hemocompatibility of a centrifugal blood pump.

A correlation study was conducted among quantitative flow visualization analysis, computational fluid dynamic analysis, and hemolysis tests regarding the flow in a centrifugal blood pump to prevent hemolysis. Particular attention was paid to the effect of the impeller/casing gap widths on the flow in the volute and in the outlet. Flow vector maps were obtained for 250% scaled-up models with various geometries, using an argon ion laser light sheet, a high speed video camera, and particle tracking velocimetry. In terms of the results, in the small radial gap model, high shear occurred near the inside wall of the outlet and stagnation near the outside wall of the outlet whereas the standard model maintained smooth flow and low shear. The small radial gap model showed a lower head and greater hemolysis than the standard model. This head decrease could be partly restored by relocating the outlet position; however, the hemolysis level hardly decreased. From these results, it was found that the small radial gap itself is important. It was also confirmed by detailed flow visualization and simple laminar shear analysis near the wall that the small radial gap caused a wider high shear layer (110-120 microm) than the standard model (approximately 80 microm). In the small radial gap model, the high shear layer in the outlet (approximately 50 microm) is much narrower than that in the volute. Flow visualization together with the aid of computational fluid dynamic analysis would be useful to eliminate the causes of hemolysis.

Blood Flow Velocity↗

PubMedDate not supplied

Visual-discrimination deficits after lesions of the centrifugal visual system in pigeons (Columba livia).

The effects of bilateral lesions of the centrifugal visual system (CVS) on the visual-discrimination capacity were studied in pigeons. Three different behavioral experiments, each testing different aspects of visual analysis, were performed. In the first two experiments, a grain-grit discrimination task and a visual-acuity determination, stimuli were presented in the frontal binocular visual field. A third experiment investigated the early detection of slow moving objects, introduced into the monocular lateral visual field. After bilateral lesions in the nucleus isthmo-opticus (ION) and in the ectopic nucleus isthmo-opticus (EION), a multiple linear regression analysis was employed to correlate the postoperative performance in all three tasks with the amount of structure loss within ION and EION. Deficits in the grain-grit discrimination procedure were a function of the ION lesion extent and did not depend on EION damage. Thus, these two structures could be functionally differentiated for the first time. Neither the ION nor the EION seems to be involved in visual-acuity performance or the early detection of large shadows moving forward through the visual field. Our data support the hypothesis that the CVS is involved in pecking and food selection among static stimuli at a short viewing distance in ground-feeding birds such as pigeons and chickens.

Animals↗

PubMed1980

Clinical estimation of infarct size by 201thallium perfusion scintigraphy and by creatine kinase-MB in early myocardial infarction.

201Thallium (201Tl) perfusion scintigraphy was performed in 22 patients with first acute transmural myocardial infarction within the initial 12 h after onset of symptoms. The size of the abnormally perfused area on 201Tl images was estimated by visual analysis and by a computer-assisted technique. 201Tl values for infarct size were compared to a biochemical estimate of infarct size using the cardiac specific esoenzyme creatine kinase-MB (CK-MB) and total creatine kinase (CK). Estimates of myocardial damage obtained from the visual and computer-assisted analysis of the 201Tl images showed a statistically significant correlation with the enzymatic estimates of infarct size. These results suggest that quantitative evaluation of 201Tl image defects may provide useful information regarding the degree of myocardial damage in the very early stages of acute infarction before biochemical estimates of infarct size are available, and that sequential imaging with 201Tl might provide an independent method of monitoring evolutionary changes in myocardial damage.

Adult↗

PubMed2006

Detection of motion onset and offset: reaction time and visual evoked potential analysis.

Manual reaction time (RT) and visual evoked potentials (VEP) were measured in motion onset and offset detection tasks. A considerable homology was observed between the temporal structure of RTs and VEP intervals, provided that the change in motion was detected as soon as the VEP signal has reached critical threshold amplitude. Both manual reactions and VEP rise in latency as the velocity of the onset or offset motion decreases and were well approximated by the same negative power function with the exponent close to -2/3. This indicates that motion processing is normalised by subtracting the initial motion vector from ongoing motion. A comparison of the motion onset VEP signals in two different conditions, in one of which the observer was instructed to abstain from the reaction and in the other to indicate as fast as possible the beginning of the motion, contained accurate information about the manual response.

Adult↗

PubMed1983

[Spectral analysis of fast EEG rates in normal 6-to-16-year-old children].

Spectral analysis of EEGs from 208 school children aged from 6 to 16 shows two types of beta activity: anterior beta which is low in amplitude but increases in energy in response to eye opening and posterior beta which, like alpha, decreases in response to eye opening. After reviewing the role of the FFT in frequency analysis we conclude that anterior beta activity corresponds to the classic beta rhythm of visual analysis, while posterior beta activity probably represents harmonics of alpha or even theta activity. In any case, beta activity in the normal child is very low in amplitude and energy.

Adolescent↗

PubMed1989

Maslach Burnout Inventory: factor structures and norms for USA pharmacists.

This study was conducted to establish normative data as well as evaluate the construct validity and reliability of the three subscales of the Maslach Burnout Inventory when given to a national sample of USA licensed practicing pharmacists. Data were subjected to principal factors analysis with iteration and a varimax rotation to obtain a three-factor solution. Visual analysis and statistical comparison provided empirical support for the presence of the hypothesized (a priori) constructs of Emotional Exhaustion, Depersonalization, and Lack of Personal Accomplishment. Internal consistency of the derived subscales, as measured by Cronbach's alpha coefficient, were comparable with previous data. Pharmacists' subscale scores were significantly lower than those obtained in studies of the helping professions.

Adult↗

PubMed1998

Tracing the timing of human analysis of motion and chromatic signals from occipital to temporo-parieto-occipital cortex: a transcranial magnetic stimulation study.

In human visual analysis, the initial processing of motion and chromatic signals may be mediated by feed-forward pathways from striate cortex to segregated areas of extrastriate cortex. The time-course of occipital to temporo-parieto-occipital motion processing was unknown, as was the selectivity of the effect of transcranial magnetic stimulation (TMS) on motion processing. TMS delivered over occipital cortex degraded the discrimination of motion-defined form (MDF) in a discrete time window beginning 100-120 ms from the onset of the visual stimulus. Bilateral focal TMS delivered over the temporo-parieto-occipital junction (TPO) disrupted the discrimination of MDF in a time window beginning 20-40 ms later than the effect of TMS delivered over occipital cortex. Bilateral focal TMS delivered over TPO also degraded the discrimination of CDF, motion direction, and color.

Adolescent↗

PubMedDate not supplied

Diagnostic criteria for detection of postinfarction ischemia by quantitative analysis of stepwise dobutamine radionuclide ventriculography.

BACKGROUND: Application of the traditional diagnostic criteria validated for exercise testing may be inappropriate when dobutamine infusion is associated with radionuclide ventriculography (RNV). The objective of this study was to establish appropriate diagnostic criteria for evaluation of dobutamine stress testing with RNV for the detection of early postinfarction ischemia. METHODS: RNV was performed at baseline and during dobutamine infusion in 10 control subjects and in 30 patients who were studied within 1 week after uncomplicated myocardial infarction. Several quantitative parameters including left ventricular ejection fraction (EF), regional EF, and absolute change in global and regional EF were tested. In addition, regional wall-motion changes were scored by visual analysis. The limit of normal response for each quantitative parameter was defined as the 95th percentile of the distribution observed in control subjects. On the basis of predischarge clinical evaluation and exercise stress testing, patients were grouped as having evidence of residual ischemia (group 1, 15 patients) or no evidence of ischemia (group 2, 15 patients). Sensitivity, specificity, and accuracy in the detection of postinfarction ischemia were calculated for each parameter, and empiric receiver-operating characteristic curves were generated. RESULTS: The limits of the normal response to dobutamine infusion in the control subjects were found to be a 7.5% and a 12.5% increase in global EF at low and high dose, respectively. Median baseline EF was significantly lower in patients than in control subjects (Mann-Whitney U test: P < .001). There were no differences in resting EF between group 1 and group 2 patients. However, median high-dose EF and increase in EF were significantly lower in group 1 as compared with group 2 patients (56% vs 72% and 5% vs 17%, respectively; Mann-Whitney U test: P < .0001 for both). A biphasic (up-and-down) response with initial increase at low dose followed by decrease or no change in EF at high dose was observed in 66% of group 1 patients and only in 13% of group 2 subjects. The best criterion for detection of postinfarction ischemia was a change of <12.5% in global EF at high-dose dobutamine infusion, with 80% predictive accuracy. The traditional criterion, a change of <5 % or a decrease in EF, yielded an accuracy of only 63%. The association of a change of <12.5% with a biphasic response increased accuracy to 87%, with a sensitivity of 93% and a specificity of 80%. Quantitative regional wall motion analysis showed greater diagnostic accuracy than visual wall motion scoring (83% vs 70%). CONCLUSIONS: Application of appropriate criteria and stepwise quantitative analysis of RNV during dobutamine infusion may increase accuracy in the detection of early postinfarction ischemia.

Blood Pressure↗

PubMed1996

Quantitative EEG analysis as a supplement to the clinical coma scale RLS85.

BACKGROUND: The aim of the study was to investigate the correlation between EEG indicators and clinical scores based on the RLS85 (Reaction Level Scale 85) in comatose patients. The results of a simple visual assessment of the EEG, using an arbitrary scale with typical EEG patterns, were compared with those obtained by quantitative electroencephalography (qEEG). METHOD: The RLS85 scores were examined in 34 patients with impaired consciousness due to brain tumours, vascular lesions or head injuries. The EEG was recorded shortly before or after the clinical examination. The semiquantitative assessment was made by visual inspection of the tracings, using an arbitrary scale where 12 EEG patterns with increasing proportion of slow activity were displayed. Parallel to the visual analysis, the EEGs were processed by means of EEG spectrum analysis and the power/amplitude in slow frequency bands was used as an indicator. The results were based on correlation between various types of EEG variables and the RLS scores which were obtained in the same patients. RESULTS: The correlation between the visual EEG indicators and coma scores ranged between 0.53 and 0.57 (P < 0.01). As regards the computerised EEG analysis, the correlation between the clinical scores and various EEG spectrum values did not exceed 0.45 (P < 0.01). A higher correlation could be obtained by combining eight EEG variables; the multiple correlation coefficient was then 0.68. CONCLUSIONS: The amount of EEG slow activity is significantly correlated to the RLS85 score. This means that the EEG also provides information on the level and not only on the changes of the coma degree. Surprisingly, the indicators based on quantitative EEG, as used in commercially available instruments, did not give better results than the visual assessment. However, the results of the computerised analysis could be improved using multivariate statistical methods. The study also showed a way to improve communication between the neurophysiologist and clinician by presenting the EEG findings in terms similar to those used in the clinical scales. However, the clinician should be aware of the fact that the "EEG score" and the clinical score is not the same: the intention is to supplement rather than to simulate the clinical observation.

Adolescent↗

PubMedDate not supplied

Characterization of focal liver lesions with half-fourier acquisition single-shot turbo-spin-echo (HASTE) and inversion recovery (IR)-HASTE sequences.

The half-Fourier acquisition single-shot turbo-spin-echo (HASTE) sequence allows for heavily T2-weighted images, and the inversion recovery (IR)-HASTE sequence represents the T1 value of the tissue in a very short time. This study was undertaken to determine whether characterizing focal liver lesions can be made by combination with these very fast sequences. Seventy-four patients (33 cysts, 28 hemangiomas, and 33 malignant solid liver masses [15 metastatic tumors, 14 hepatocellular carcinomas, and 4 cholangiocarcinomas) underwent dynamic CT and breath-hold abdominal MRI using turbo-spin-echo (TSE), HASTE, and IR-HASTE sequences with variable T1 values on a 1.5-T MR unit. The imaging time for each slice was 2 seconds for HASTE imaging and 2 to 4 seconds for IR-HASTE imaging. Lesion detection and qualitative characterization were evaluated. Quantitative analysis was performed by measuring the contrast-to-noise ratios (CNRs) as well as visual analysis. The inversion time (TI) nulling values were also statistically analyzed. All cystic lesions were detected on both TSE and HASTE imagings. For solid lesions, TSE failed to detect one small solid lesion and HASTE sequence failed to detect three lesions. With HASTE sequences, all cysts and hemangiomas were markedly hyperintense in comparison with malignant solid masses. CNRs of hemangiomas or cysts were significantly higher than those of malignant solid masses (P < .01), and there was no overlap. The TI nulling value was 1,100+/-100 msec for hemangiomas, 1,900+/-110 msec for cysts, and 740+/-140 msec for malignant solid masses. There was no overlap between the TI nulling values of hemangiomas and cysts (P < .01). By combining the CNR from the HASTE sequence and the TI nulling value from the IR-HASTE sequence, complete discrimination among malignant solid masses, hemangiomas, and cysts of the liver could be made. Application of HASTE (representing T2 values) and IR-HASTE (representing T1 values) sequences provided a rapid and reliable imaging method for characterizing focal liver lesions without the use of contrast medium.

Adolescent↗

PubMed1986

[Gd-DTPA in magnetic resonance diagnosis of chronic myocardial infarct].

30 patients with myocardial infarction older than three weeks were examined by MRI prior and following intravenous injection of 0.1-0.2 mmol/kg Gd-DTPA, 201TL-SPECT and cineventriculography. Gd-DTPA did not cause any significant change (p less than 0.05) of T2-values for infarcted or non-infarcted myocardium. Compared with this, signal intensity for T1-weighted images increased after the application of the contrast agent both for normal (26 +/- 14%) and infarcted myocardium (33 +/- 16%). The intraindividual signal intensity ratio for infarcted and normal myocardium increased from 1.06 +/- 0.07 to 1.12 +/- 0.09 after the injection of Gd-DTPA. The diagnosis of myocardial infarction by visual analysis of signal intensity was not possible in individual cases. Myocardial infarction could only be visualized indirectly by morphological changes such as wall thinning and aneurysm.

Adult↗