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PubMed1977

Computerized EEG analysis for studying the effect of drugs on the central nervous system.

Samples of our experience in quantitative pharmaco-EEG are reviewed to discuss and define its applicability and limits. Simple processing systems, such as the computation of Hjorth's descriptors, are useful for on-line monitoring of drug-induced EEG modifications which are evident also at the visual visual analysis. Power spectral analysis is suitable to identify and quantify EEG effects not evident at the visual inspection. It demonstrated how the EEG effects of compounds in a long-acting formulation vary according to the sampling time and the explored cerebral area. EEG modifications not detected by power spectral analysis can be defined by comparing statistically (F test) the spectral values of the EEG from a single lead at the different samples (longitudinal comparison), or the spectral values from different leads at any sample (intrahemispheric comparison). The presently available procedures of quantitative pharmaco-EEG are effective when applied to the study of mutltilead EEG recordings in a statistically significant sample of population. They do not seem reliable in the monitoring of directing of neuropyschiatric therapies in single patients, due to individual variability of drug effects.

Alcoholic Intoxication↗

PubMed1997

Evaluation of the limits of visual detection of image misregistration in a brain fluorine-18 fluorodeoxyglucose PET-MRI study.

In routine clinical work, registration accuracy is assessed by visual inspection. However, the accuracy of visual assessment of registration has not been evaluated. This study establishes the limits of visual detection of misregistration in a registered brain fluorine-18 fluorodeoxyglucose positron emission tomography to magnetic resonance image volume. The "best" registered image volume was obtained by automatic registration using mutual information optimization. Translational movements by 1 mm, 2 mm, 3 mm and 4 mm, and rotational movements by 1 degrees , 2 degrees , 3 degrees and 4 degrees in the positive and negative directions in the x- (lateral), y- (anterior-posterior) and z- (axial) axes were introduced to this standard. These 48 images plus six "best" registered images were presented in random sequence to five observers for visual categorization of registration accuracy. No observer detected a definite misregistration in the "best" registered image. Evaluation for inter-observer variation using observer pairings showed a high percentage of agreement in assigned categories for both translational and rotational misregistrations. Assessment of the limits of detection of misregistration showed that a 2-mm translational misregistration was detectable by all observers in the x- and y-axes and 3-mm translational misregistration in the z-axis. With rotational misregistrations, rotation around the z-axis was detectable by all at 2 degrees rotation whereas rotation around the y-axis was detected at 3-4 degrees . Rotation around the x-axis was not symmetric with a positive rotation being identified at 2 degrees whereas negative rotation was detected by all only at 4 degrees. Therefore, visual analysis appears to be a sensitive and practical means to assess image misregistration accuracy. The awareness of the limits of visual detection of misregistration will lead to increase care when evaluating registration quality in both research and clinical settings.

Brain↗

PubMed1995

Covert orienting biases in scene-based reference frames: orientation priming and visual field differences.

Performance advantages for stimuli presented in the right versus the left visual field have been found in a variety of attentional tasks. Such advantages were exploited in the present set of studies to examine orientation priming and directional biases in retinotopic and scene-based spatial coordinates. The results demonstrate that directional biases occur within spatial coordinates across orientation transformations that dissociate retinotopic from scene-based visual half fields. The results are discussed concerning the representation of spatial maps in higher visual analysis, the role of spatial coordinates in guiding covert orienting, and methods of presenting stimuli in the right or left visual field to test for functional hemispheric asymmetries.

Adult↗

PubMed1979

Description of chromosome banding patterns by band transition sequences: a new basis for automated chromosome analysis.

For visual and automated analysis of banded human chromosomes, the band pattern features of chromosome profiles considered essential for the cytogeneticist were evaluated. These features were found to be related to each peak (dark band) and its adjacent valley (light band) in the direction p--q. A method for extracting and describing these features was developed and implemented on a computer. The method determines three normalized parameters for each peak and adjacent valley: (1) density of peak; (2) density difference (transition) between peak and valley; and (3) position of peak. Each profile is described by a simple sequence of band transitions (BT-sequence). The BT-sequence was visualized as a profile (BT-profile) using only the information retained in the BT-sequence. Visual classification of BT-profiles shows error rates comparable to visual classification of ordinary density profiles (Lundsteen & Granum 1979). It is therefore concluded that the BT-profiles do retain the important band pattern features of the profiles, and it is supposed that the simple and condensed BT-sequences constitute an appropriate basis for automated karyotyping.

Chromosome Banding↗

PubMed2004

[EEG and video-EEG explorations in refractory partial epilepsy].

The assessment of drug -resistant partial epilepsy by electrophysiological explorations (based on non-invasive EEG) involves two types of analysis: the study of the seizures, primarily by video-EEG exploration, and the study of interictal activities based on visual analysis, and in some centers on techniques of source localization (high resolution EEG and magnetoencephalography, MEG). Seizure recording can be used to confirm the focal nature and the epileptic origin of the seizure as well as other features such as severity (secondary generalization, frequency, falls etc.). In the pre-surgical approach, the video-EEG recordings enable study of the electro-clinical correlations and allow assumptions on the anatomical localization of the epileptogenic zone. Precise analysis of the localization of the interictal activities (especially within the framework of extra-temporal epilepsies) based on source localization methods, makes it possible to put forth assumptions on the localization of the irritative zone.

Anticonvulsants↗

PubMed1988

Computer analysis of pressure tracings from the sphincter of Oddi.

Since the sphincter of Oddi exhibits very regular phasic motor activity it offers itself to the design of a simple computer program in the analysis of gastrointesinal motility. This investigation is the first attempt of a practical application of such a computer program. The signals coming out of the pressure preamplifier are submitted to active filtering in order to prevent aliasing and then to analog to digital conversion. After being fed into a computer they are precessed in a number of controllable and adaptable steps before the final analysis. Computer analysis then yields a detailed quantitative print out of a large variety of variables which compares very favourably with the visual analysis. It speeds up the time of analysis and allows for a study of long-term recording. Computer analysis of pressure tracings from the sphincter of Oddi may serve as a model for a study of motor activity of all parts of the digestive tract with this modern method of data handling.

Ampulla of Vater↗

PubMed2001

Electroencephalography in juvenile neuronal ceroid lipofuscinosis: visual and quantitative analysis.

Fourteen patients with a confirmed diagnosis of juvenile neuronal ceroid lipofuscinosis (JNCL) (aged 6-12.5 years at the beginning of the study) were prospectively followed for 5 years. An electroencephalogram (EEG) was recorded and analysed both visually and quantitatively and a neuropsychological examination was performed once a year. In addition, a cross-sectional EEG study of 32 patients aged 5-27 years was performed. The EEG was often normal before the age of 9 years, and thereafter a progressive background abnormality and increase in paroxysmal activity took place. The EEGs were significantly slower than those of the controls, and the speed of slowing of EEG correlated to the decrease in intelligence quotients (IQ). Quantitative analysis was superior to visual analysis in detecting the deterioration of the background activity. The best parameter describing this was the fast/slow ratio. Peak frequency, percentage of theta and the fast/slow ratio correlated with IQ.

Adolescent↗

PubMed1994

The role of surface information in object recognition: studies of a visual form agnosic and normal subjects.

Three experiments were conducted to explore the role of colour and other surface properties in object recognition. The effects of manipulating the availability of surface-based information on object naming in a patient with visual form agnosia and in two age-matched control subjects were examined in experiment 1. The objects were presented under seven different viewing conditions ranging from a full view of the actual objects to line drawings of those same objects. The presence of colour and other surface properties aided the recognition of natural objects such as fruits and vegetables in both the patient and the control subjects. Experiment 2 was focused on four of the critical viewing conditions used in experiment 1 but with a large sample of normal subjects. As in experiment 1, it was found that surface properties, particularly colour, aided the naming of natural objects. The presence of colour did not facilitate the naming of manufactured objects. Experiment 3 was focused on possible ways by which colour could assist in the recognition of natural objects and it was found that object naming was facilitated only if the objects were presented in their usual colour. The results of the experiments show that colour does improve recognition for some types of objects and that the improvement occurs at a high level of visual analysis.

Adult↗

PubMed1997

Composition of human thrombus assessed by quantitative colorimetric angioscopic analysis.

BACKGROUND: Angioscopy surpasses other diagnostic tools, such as angiography and intravascular ultrasound, in detecting arterial thrombus. This capability arises in part from the unique ability of angioscopy to assess true color during imaging. In practice, hardware-induced chromatic distortions and the subjectivity of human color perception substantially limit the theoretic potential of angioscopic color. We used a novel application of tristimulus colorimetry to quantify thrombus color to both aid in its detection and assess its composition. METHODS AND RESULTS: A series of human thrombus models were constructed in vitro. Spatial homogeneity was ensured by light and electron microscopy. Quantitative colorimetric angioscopic analysis demonstrated excellent measurement reproducibility (mean difference, 0.07% to 0.17%), unaffected by illuminating light intensity (coefficient of variation, 0.21% to 3.67%). Colorimetric parameters C1 and C2 were strongly correlated (r=.99, P<.0001) with thrombus erythrocyte concentration. Principal components analysis transformed these parameters into a single value, the thrombus erythrocyte index, with little (0.06%) loss of content. Measured and predicted concentrations were similar (mean difference, 0.16 erythrocytes per 1 ng). Randomly ordered images were also subjected to visual analysis by three experienced angioscopists, with suboptimal levels of both intraobserver (mean kappa=0.63) and interobserver (mean kappa=0.48) agreement. In addition, visual ranking resulted in a Kendall rank coefficient of 0.72 to 0.76 versus a perfect 1.00 from quantitative measurement. CONCLUSIONS: Quantitative colorimetric angioscopic analysis provides a new, objective, and reproducible analytic tool for assessing angioscopic images of human thrombus. Even under ideal circumstances, experienced angioscopists do a poor job of assessing color (and therefore composition) of human thrombi. This technique can, for the first time, provide quantitative information of thrombus composition during routine diagnostic imaging.

Angioscopy↗

PubMed2001

Echo-planar magnetic resonance myocardial perfusion imaging: parametric map analysis and comparison with thallium SPECT.

Magnetic resonance (MR) perfusion FLASH imaging has been used for assessing coronary artery disease (CAD). Echo-planar MR techniques have advantages in speed and in making MR perfusion imaging results more clinically accessible through parametric maps, but have not been previously assessed. We implemented a spin-echo, echo-planar MR technique and applied it at rest and during adenosine stress in 26 patients with CAD and abnormal thallium single-photon-emission computed tomography (SPECT), and analyzed the results by using a newly developed parametric map analysis of time to peak, peak intensity, and slope of contrast washin. The results were compared with the results of conventional visual analysis of the perfusion cine series. For detecting abnormal coronary territories, MR and SPECT were comparable for sensitivity, specificity, and accuracy (thallium, 70%, 78%, and 73%; MR, 79% 83%, and 80%; P = NS). There was good agreement between thallium and MR during stress (kappa = 0.49), but defects were larger by MR (2.4 vs. 3.1 segments for slope; P < 0.01). Additional segments were detected at rest by MR (58 for slope vs. 25 for thallium), which correlated with areas that became abnormal with stress in the thallium (sensitivity, 100%; specificity, 63%). The parametric maps were easier and faster to interpret than review of the original first-pass series of images (chi2 = 10.8; P < 0.04). The diagnostic performance of echo-planar perfusion MR and SPECT was similar, and combining the results with parametric mapping was useful for interpretation and considerably improved data display for clinical interpretation. MR, however, was faster and yielded images of higher resolution with no radiation burden. In multislice mode, these new MR techniques may have clinical value.

Aged↗

PubMed1996

Effect of bundle branch block on local electrogram morphologic features: implications for arrhythmia diagnosis by stored electrogram analysis.

Analysis of stored local ventricular electrogram recordings is a useful diagnostic tool in the evaluation of patients with implantable cardioverter defibrillators. Visual analysis of local electrogram morphologic features has been demonstrated to be useful in distinguishing ventricular tachycardia from supraventricular rhythm. The effect of bundle branch block (BBB) aberration during supraventricular tachycardia on local electrogram morphologic features is not entirely clear. Erroneous diagnoses resulting from a change in electrogram morphologic features with BBB may occur. To determine whether the development of BBB can produce a change in local electrogram morphologic features and whether this change is dependent on the site of recording, we retrospectively reviewed local electrogram recordings from 23 patients who had intermittent BBB during electrophysiologic evaluation of documented or suspected supraventricular tachycardia. Local electrogram recordings from catheters placed in the right ventricular apex and coronary sinus during supraventricular tachycardia with BBB aberrancy were compared with recordings during narrow complex supraventricular tachycardia or normal sinus rhythm. Bipolar recordings were made with a 5 mm interelectrode distance with filter settings at 40 to 400 Hz. Three independent blinded observers defined the paired electrograms as the same or distinctly different. During right BBB a change in electrogram morphologic features was demonstrated in 11 (85%) of 13 recordings from the right ventricular apex and in only 1 (8%) of 12 recordings from the coronary sinus. In contrast, during left BBB a change in electrogram morphologic features was seen in 6 (100%) of 6 recordings from the coronary sinus and in only 1 (8%) of 13 recordings from the right ventricular apex. These results demonstrate that when the described recording techniques are used, a change in local ventricular electrogram morphologic features BBB is predominantly manifest in recording sites ipsilateral to the BBB, whereas recording sites contralateral to the BBB are relatively unaffected. This information may have implications regarding interpretation of stored electrograms when an attempt is made to establish a rhythm diagnosis leading to implantable cardioverter defibrillator therapy.

Adolescent↗

PubMedDate not supplied

Spectral analysis of fetal heart rate variability in fetuses with supraventricular extrasystoles.

OBJECTIVE: Fetal heart rate (FHR) variability is an important indicator of fetal well-being. In fetal tachyarrhythmias, however, visual analysis of FHR variability is limited. We therefore applied power spectral analysis of FHR to evaluate the fetal state. METHODS: Fetal R-R intervals were detected by means of an external ECG in 3 fetuses with supraventricular extrasystoles after cardiac malformations had been excluded by fetal echocardiography. Using an autoregressive model, power spectral densities were calculated from 20 consecutive 256-beat segments for the following frequency bands: <0.03 Hz (very low frequency), 0.03-0.069 Hz (low frequency; LF), 0.07-0.129 Hz (mid-frequency) and 0.13-1.0 Hz (high frequency; HF). RESULTS: The FHR variability in fetal supraventricular extrasystoles mainly resulted from the HF component (63.91 +/- 6.97%). The sympatho-vagal balance (LF/HF) was decreased in the tracings with extrasystoles (0.13). CONCLUSION: The analysis of FHR variability in fetal supraventricular extrasystoles revealed an imbalance between sympathetic and parasympathetic regulation.

Adult↗

PubMed2001

Web-based tissue microarray image data analysis: initial validation testing through prostate cancer Gleason grading.

Tissue microarray technology promises to enhance tissue-based molecular research by allowing improved conservation of tissue resources and experimental reagents, improved internal experimental control, and increased sample numbers per experiment. Organized, well-validated collection and analysis of the voluminous image data produced by tissue microarray technology is critical to maximize its value. Web-based technology for visual analysis and searchable storage of microarray image data could provide optimal flexibility for research groups in meeting this goal, but this approach has not been examined scientifically. Toward this goal, a prostate tissue microarray block containing 432 tissue cores (0.6 mm diameter) was constructed. Moderately compressed (200 kb).jpg images of each tissue spot were acquired and were saved using a naming convention developed by the SPORE Prostate Tissue Microarray Collaborative Group. Four hundred three tissue array spot images were uploaded into a database developed for this study and were converted to.fpx format to decrease Internet transmission times for high-resolution image data. In phase I of the image analysis portion of the study, testing and preliminary analysis of the Web technology was performed by 2 pathologists (M.A.R. and G.S.B.). In phase II, 2 pathologists (J.I.E. and T.M.W.) with no previous exposure to this technology and no knowledge of the structure of the study were presented a set of 130 sequential tissue spot images via the Web on their office computers. In phase III, the same pathologists were presented a set of 193 images, including all 130 from phase II and 63 others, with image presentation order randomized. With each zoomable tissue spot image, each pathologist was presented with a nested set of questions regarding overall interpretability of the image, presence or absence of cancer, and predominant and second most frequent Gleason grade. In phases II and III of the study, 319 of 323 (99%) image presentations using this Web technology were rated interpretable. Comparing the 2 pathologists' readings in phases II and III, Gleason grade determinations by each pathologist were identical in 179 of 221 (81%) determinations and were within 1 point of each other in 221 of 221 (100%) determinations, a performance rate similar to if not better than that previously reported for direct microscopic Gleason grading. Interobserver comparison of Gleason score determinations and intraobserver comparisons for Gleason grade and score also showed a pattern of uniformity similar to those reported in direct microscope-based Gleason grading studies. Interobserver (7.5%) and intraobserver (5% and 3%) variability in determining whether diagnosable cancer was present point out the existence of a "threshold effect" that has rarely been studied but may provide a basis for identification of features that are most amenable to improved diagnostic standardization. In summary, storage and analysis of tissue microarray spot images using Web-based technology is feasible and practical, and the quality of images obtained using the techniques described here appears adequate for most tissue-based pathology research applications. HUM PATHOL 32:417-427.

Databases, Factual↗

PubMed2005

Ontological analysis of gene expression data: current tools, limitations, and open problems.

Independent of the platform and the analysis methods used, the result of a microarray experiment is, in most cases, a list of differentially expressed genes. An automatic ontological analysis approach has been recently proposed to help with the biological interpretation of such results. Currently, this approach is the de facto standard for the secondary analysis of high throughput experiments and a large number of tools have been developed for this purpose. We present a detailed comparison of 14 such tools using the following criteria: scope of the analysis, visualization capabilities, statistical model(s) used, correction for multiple comparisons, reference microarrays available, installation issues and sources of annotation data. This detailed analysis of the capabilities of these tools will help researchers choose the most appropriate tool for a given type of analysis. More importantly, in spite of the fact that this type of analysis has been generally adopted, this approach has several important intrinsic drawbacks. These drawbacks are associated with all tools discussed and represent conceptual limitations of the current state-of-the-art in ontological analysis. We propose these as challenges for the next generation of secondary data analysis tools.

Algorithms↗

PubMed1999

Tracking the time course of object categorization using event-related potentials.

Object categorization processes were investigated by measuring event-related potentials while subjects categorized objects at the superordinate (e.g. animal), basic (e.g. dog) and subordinate (e.g. beagle) levels of abstraction. An enhanced negative deflection (N1) was found at posterior recording sites for subordinate level categorizations compared with basic level categorizations and was interpreted as a marker of increased visual analysis. In contrast, superordinate level categorizations produced a larger frontal negativity relative to basic level categorizations and were interpreted as an indicator of increased semantic processing. These results suggest a neurophysiological basis for the separate cognitive processes responsible for subordinate and superordinate object categorizations.

Adult↗

PubMedDate not supplied

Prevalence of blindness and visual impairment among Jordanian diabetics.

PURPOSE: To investigate the prevalence of blindness and visual impairment among a population of Jordanian diabetics. METHODS: A total of 986 diabetic patients were fully assessed, including complete history, examination, and laboratory tests. All patients underwent detailed eye examination, which included visual acuity, slit-lamp examination, tonometry, funduscopy, and fundus fluorescein angiography (FFA). RESULTS: Of all patients examined, 53.2% were male and 46.8% were female. The mean age and duration of diabetes were 55.3 and 11.9 years. Of all patients, 93.3% had type 2 while 6.7% had type 1 diabetes mellitus (DM). Over half (50.3%) were on oral hypoglycemic agents, 34% on insulin, and 14.5% on both types of treatment, whereas only 1.2% were on diet alone. The mean value for HbA1c was 7.7%. The prevalence of blindness among participants was found to be 7.4%, while 10.1% were visually impaired. Diabetic retinopathy (DR) was present in 64.1%, 37.8% had cataract, and 8.7% had undergone cataract surgery. Using multivariate logistic regression analysis, visual impairment was significantly associated with age, treatment of diabetes, and DR, while only age and retinopathy were significantly related to blindness. CONCLUSIONS: DM is a common disease in Jordan and DR is highly prevalent among Jordanian diabetics. National screening and educational programs are highly needed to reduce the risk of blindness and visual impairment among diabetic patients.

Adolescent↗

PubMed2001

Prediction of myocardial infarction versus cardiac death by gated myocardial perfusion SPECT: risk stratification by the amount of stress-induced ischemia and the poststress ejection fraction.

UNLABELLED: The combination of myocardial perfusion and poststress ejection fraction (EF) provides incremental prognostic information. This study assessed predictors of nonfatal myocardial infarction (MI) versus cardiac death (CD) by gated myocardial SPECT and examined the value of integrating the amount of ischemia and poststress EF data in risk stratification. METHODS: We identified 2,686 patients who underwent resting (201)Tl/stress (99m)Tc-sestamibi gated SPECT and were monitored for >1 y. Patients who underwent revascularization < or = 60 d after the nuclear test were censored from the prognostic analysis. Visual scoring of perfusion images used 20 segments and a scale of 0--4. Poststress EF was automatically generated. RESULTS: Cox regression analysis showed that after adjusting for prescan data, the most powerful predictor of CD was poststress EF, whereas the best predictor of MI was the amount of ischemia (summed difference score [SDS]). Integration of the EF and SDS yielded effective stratification of patients into low-, intermediate-, and high-risk subgroups. Patients with EF >50% and a large amount of ischemia were at intermediate risk (2%--3%), whereas those with mild or moderate ischemia were at low risk of CD (<1%/y). Patients with EF between 30% and 50% were at intermediate risk even in the presence of only mild or moderate ischemia. In patients with EF <30%, the CD rate was high (>4%/y) irrespective of the amount of ischemia. CONCLUSION: Poststress EF is the best predictor of CD, whereas the amount of ischemia is the best predictor of nonfatal MI. Integration of perfusion and function data improves stratification of patients into low, intermediate, and high risk of CD.

Adenosine↗

PubMed2001

Brain perfusion spect in juvenile neuro-Behçet's disease.

UNLABELLED: Regional cerebral blood flow was evaluated by (99m)Tc-hexamethylpropyleneamine oxime SPECT in 7 patients (age range, 7--18 y; mean age, 9.1 y) affected with Behçet's disease and signs or symptoms of central nervous system involvement at different times of their clinical history. METHODS: Three patients suffered from seizures, 3 patients were affected with severe persistent headache that was refractory to common analgesic and nonsteroidal antiinflammatory drugs, and 1 patient had recurrent episodes of acute intracranial hypertension. Electroencephalography was performed on all patients, MRI on 5 patients, and CT on 1 patient. Brain SPECT was performed using a high-resolution, brain-dedicated camera. After conventional visual analysis by 2 expert readers, 2 transaxial sections were drawn parallel to the bicommissural line: the first across the thalami and the second across the temporal lobe at the level of the mesiotemporal structures. Cortical regions of interest were drawn automatically on the cortical ribbon on the 2 sections, whereas other regions of interest were drawn by hand around the basal ganglia, the thalami, and the mesiotemporal structures. Asymmetry analysis was then applied, and hypoperfusion was considered when the asymmetry value was >10%. RESULTS: Hypoperfusion was observed in all patients by visual and asymmetry analyses; this finding was localized mainly in the basal ganglia, the thalami, and the temporal cortex, including its mesial portion. Temporal hypoperfusion was found primarily in patients with seizures, and hypoperfusion of deep gray nuclei was found mainly in the other patients. Electroencephalography disclosed brain functional impairment in 5 of 6 patients, where- as MRI showed multiple bilateral white matter lesions in 1 patient suffering from persistent headache. CONCLUSION: As in adults, perfusion SPECT seems to be very sensitive in disclosing brain abnormalities in children and adolescents with Behçet's disease and signs or symptoms of central nervous system involvement, even with negative findings on brain MRI.

Behcet Syndrome↗