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At least 451 records · Page 25Linked to original sources
PubMed2003

An automatic dose dispenser for microtablets--a new concept for individual dosage of drugs in tablet form.

A new concept for individualising the dosage of drugs in solid form is presented. The principle is based on the use of standardised units (microtablets), each containing a subtherapeutic amount of the active ingredient. The required dose is fine-tuned by counting out a specific number of these units. The microtablets are counted electronically from the attached cassette by the automatic dispensing device. The individual dose is set and the dispenser counts and delivers the correct number of microtablets. The usefulness of the automatic dispenser concept and acceptability of the apparatus were evaluated in patients with Parkinson's disease (PD). After initial instruction on use of the dispenser, 20 patients operated it themselves. All patients were generally satisfied with their management of the automatic dispenser and most would be happy to use the device again. Further technical development is required before use in clinical practice, but the current prototype may be acceptable for some patients. It is concluded that the final version of the automatic dose dispenser concept will offer potential for improvement of drug administration for patients with PD or other diseases requiring individual dosage.

Aged↗
PubMed1998

Automatic assessment of cardiac function from short-axis MRI: procedure and clinical evaluation.

Cardiac magnetic resonance imaging (MRI) provides a wealth of morphological and physiological information. Automatic extraction of this information is possible by implementing various image processing techniques. However, existing procedures mostly rely on extensive human interaction and are seldom evaluated on a clinical scale. In this study, a nearly automatic process that extracts physiological parameters from cardiac MR images has been both developed and clinically evaluated. Raw images were obtained in the short-axis view and acquired by a gradient-cho (GE) protocol. In images selected to be analyzed, the only manual step required is the indication of a point in the center of the left ventricle (LV). From a set of such images, the process extracts endocardial and epicardial contours and calculates left ventricular volumes, mass and ejection fraction (EF). The process implements novel approaches to image processing techniques such as thresholding and shape extraction and can be adapted to other acquisition protocols. The process has demonstrated a clear potential for accurate extraction of the endocardial contour but a lower one with respect to the epicardial contour as a result of the low contrast between myocardium and some surrounding tissues, generated by the gradient-echo protocol. The ability of the process to asses physiological parameters has been subjected to a systematic clinical evaluation, which compared parameters, derived manually and automatically, in 10 healthy subjects and 10 patients. The evaluation has indicated that although individual volumes and mass were not accurately assessed, the automatic process has shown high potential for assessing the ejection fraction with relatively high accuracy and reliability.

Adult↗
PubMed1999

Automatic detection of hippocampal atrophy on magnetic resonance images.

An automatic method for identifying hippocampal atrophy on magnetic resonance (MR) images obtained from patients with clinical evidence of temporal lobe epilepsy (TLE) is described. The method is based on the analysis of image intensity differences between patients and controls within a volume of interest (VOI) centred on the hippocampus. The core of the method is a fully automatic signal intensity-based inter-subject image registration technique. In particular, a global affine registration to a reference image is performed, followed by a local affine registration within the VOI. A mask produced by manual segmentation of the mean hippocampus for 30 control subjects enabled investigations to be restricted to a specified region of the VOI approximately corresponding to the hippocampus. Normal variations of hippocampal signal intensity were computed from images obtained for the 30 control subjects. The manual method of hippocampal volumetry, currently an important component of the pre-surgical evaluation of patients with clinical evidence of medically intractable TLE, is used to determine the lower 1st percentile limits of normal hippocampal volume. Hippocampi with volumes below this limit are defined as atrophic. We investigated whether the automatic method can correctly distinguish between 15 patients with significant hippocampal atrophy according to absolute volumes and a further 14 controls. ROC curves enabled evaluation of sensitivity and specificity in respect of an intensity threshold. 100% specificity is required when determining suitability of patients for neurosurgery, resulting in levels of 50% and 70% sensitivity in detecting atrophy in the right and left hippocampus, respectively. We propose that the method can be developed as an automatic screening procedure.

Adolescent↗
PubMed1986

Combined bipolar dual chamber pacing and automatic implantable cardioverter/defibrillator.

A 67 year old man with recurrent hypotensive ventricular tachycardia, amiodarone-induced bradyarrhythmias and severe cardiac dysfunction underwent simultaneous implantation of an automatic cardioverter/defibrillator and bipolar atrioventricular (AV) pacemaker. The pacing electrodes were placed epicardially near the right atrial appendage and on the lateral right ventricular wall. The rate detector of the automatic defibrillator was placed epicardially on the posterobasal left ventricular wall. Effective bipolar AV pacing produced no false counting of the heart rate by the automatic cardioverter/defibrillator, and ventricular tachycardia properly inhibited the pacemaker. Long-term follow-up study confirmed the safety of this treatment. With proper precautions, bipolar AV pacing can be safely combined with an automatic cardioverter/defibrillator.

Aged↗
PubMed1987

Automatic implantable cardioverter-defibrillator: patient survival, battery longevity and shock delivery analysis.

The automatic implantable cardioverter-defibrillator (AICD) has been shown to reduce the mortality rate of patients with malignant ventricular tachyarrhythmias. This report describes experience with implantation of 36 automatic implantable cardioverter-defibrillators (AID-B and AID-BR models) in 22 persons over a 44 month patient follow-up period (mean 19.6 months). There were five deaths: two patients died suddenly 22 and 29 months, respectively, after their second implant, one died of congestive heart failure, one died of respiratory failure and one died of catheter sepsis. Although 11 (50%) of the 22 patients never received a countershock for a ventricular tachyarrhythmia and are still alive, the other 11 received one or more spontaneous countershocks. Nine patients (41%) experienced spurious shocks during the follow-up period. Assuming that the first shock for presumed ventricular tachyarrhythmia prevented death, the hypothetical cumulative survival of patients at 42 months would have been 34 +/- 14.1% in the absence of an automatic implantable cardioverter defibrillator rather than the actual survival rate of 59 +/- 16.8%. The cumulative device survival of the 36 AID-B units was 92 +/- 5.62% at 15 months but diminished to 37 +/- 14.4% by 20 months. No unit lasted longer than 22 months. There were 12 battery depletions. The number of shocks emitted did not influence unit longevity. The manufacturer's elective replacement indicator is of uncertain validity. Six units remained active 7 to 17 months after surpassing their replacement indicator. The automatic implantable cardioverter-defibrillator prolongs the life of many patients with otherwise intractable arrhythmias.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Noninvasive markers for acute heart transplant rejection in children with the use of automatic border detection.

A noninvasive method to detect heart transplant rejection would allow for increased monitoring at reduced risk. Automatic border detection is a new method to assess diastolic abnormalities. The purpose of this study was to determine whether automatic border detection of left ventricular filling detects rejection in children. Nineteen episodes of biopsy-proven rejection in 10 children were retrospectively reviewed. Echocardiograms during rejection were compared with those before rejection and during recovery. Automatic border detection indices were percentage of total left ventricular filling as a result of rapid filling, diastasis, and atrial contraction. The percentage of total ventricular filling during diastasis increased significantly during rejection (10% +/- 6% versus 15% +/- 8%, p = 0.02), and the percentage of filling during the rapid filling phase decreased during rejection (82% +/- 8% versus 77% +/- 11%, p = 0.08). These changes were even more marked for the most severe episodes of rejection. These changes resolved at recovery. Automatic border detection of left ventricular filling patterns are altered during cardiac rejection in children. Filling during diastasis increases significantly, and filling during the rapid filling phase decreases. A prospective analysis is needed to determine whether these changes in filling can obviate the need for cardiac biopsy.

Adolescent↗
PubMedDate not supplied

Automatic 3D vascular tree construction in CT angiography.

This study presents an automatic method for 3D reconstruction of vascular trees using computed-tomography angiographic (CTA) images. The program starts with the CTA slices, performs a sequential procedure of 3D image formation, preprocessing, segmentation, thinning, skeleton pruning and tree construction. It ends with vascular trees along with quantitative data about the trees such as values of diameter, length and bifurcation angles. All the involved algorithms are presented with the emphasis given to the skeleton pruning and tree construction algorithms. The skeletons obtained using a 3D thinning algorithm may contain cycles, spurs, isolated sticks, and non-unit-width parts, which hinder tree construction. As a solution to this problem, a skeleton pruning and tree construction algorithm is proposed. At each stage of the automatic procedure, 3D rendering is provided for visual inspection of the computed results. In the final output, the constructed vascular trees are visualized by rendering the 3D trees and the 3D binary image together in a transparent display mode. The program is carried out in a fully automatic fashion, with a few default settings. Occasionally, user intervention is needed at the 3D segmentation stage to impose an appropriate threshold when the automatic 3D segmentation is obviously sub-optimal for vessel delineation. Experimental demonstrations on both coronary artery phantom and a cast of coronary artery tree of a swine animal model are provided.

Angiography↗
PubMed2002

The N400 is modulated by unconsciously perceived masked words: further evidence for an automatic spreading activation account of N400 priming effects.

It is a matter of debate whether the N400 component of the event-related brain potential (ERP) is sensitive to unconscious automatic priming mechanisms or to strategic mechanisms only. Recent studies demonstrated N400 modulation by masked primes at a short SOA supporting an automatic spreading activation account. However, it cannot be ruled out that strategic mechanisms based upon partial prime identification contributed to the observed priming effects. The present study was set up to substantiate masked N400 priming effects as an index of automatic spreading activation. It was assessed whether partial identification of the masked words due to backward priming could have supported strategic priming to occur. In experiment 1, ERPs were recorded while subjects performed lexical decisions on targets preceded by masked and unmasked primes at an SOA of 67 ms. Masked words, which were not consciously perceived, as well as visible words were shown to modulate the N400 to meaningfully related target words. Experiment 2 required subjects to perform decisions on visual, lexical and semantic features of masked words presented with or without semantically related context words. Subjects performed at chance in all tasks. Furthermore, the results exclude the possibility that backward priming has rendered the masked words partially visible. The present study therefore demonstrates that N400 priming effects can be reliably obtained from unconsciously perceived masked words at a very short SOA and strengthens the notion that the N400 is modulated by automatic spreading activation and not exclusively by strategic semantic processes.

Adult↗
PubMed1992

[Automatic analysis of sleep-wake states during the first year of life].

Automatic analysis on infant sleep tracing was first considered as an aid to the rapid construction of hypnograms. It has long been thought more complicated than in adults, because of the significant changes in electrogenesis during the first year of life, resulting in difficulty to adapt to the criteria of Rechtschaffen and Kales (1968), even if modified, or to those of Anders et al (1971). In fact, these studies have shown that automatic analysis of sleep EEG tracings permit an easier analysis of the changes in electrogenesis according to subject age, sleep stage and time of night. Moreover, automatic analysis of parameters which change with the sleep-wake stages shows the continuity of these changes, and therefore the somewhat arbitrary nature of conventional hypnogram classification. The mathematical treatment of this information facilitates their visualisation, and permits a better analysis of circadian and ultradian variations that could scarcely be formalized by classical hypnogram analysis. In the study of maturation occurring during the first months of life, automatic signal processing will require adaptation that will lead to new forms of reasoning.

Circadian Rhythm↗
PubMed2003

Competition between automatic and controlled processes.

We investigated the competition between automatic and controlled processes in a word stem completion task. Prime-display duration and the prime-target interval were manipulated. On each trial a masked prime was displayed briefly, followed either immediately or after a delay by a word stem. The subjects were required to complete each stem with the first word that came to mind, to report any prime they could identify, and not to give as completion any identified prime. By the assumption that automatic processes require less stimulus input and can be completed faster than consciously controlled processes we expected a stronger performance contribution from automatic processes with the shorter prime-display durations and in the immediate stems condition. The results confirmed this expectation. The findings highlight that consciously controlled processes require more time to run their course than unconscious automatic processes.

Adult↗
PubMed2003

Brain activity during automatic semantic priming revealed by event-related functional magnetic resonance imaging.

Semantic priming occurs when a subject is faster in recognising a target word when it is preceded by a related word compared to an unrelated word. The effect is attributed to automatic or controlled processing mechanisms elicited by short or long interstimulus intervals (ISIs) between primes and targets. We employed event-related functional magnetic resonance imaging (fMRI) to investigate blood oxygen level dependent (BOLD) responses associated with automatic semantic priming using an experimental design identical to that used in standard behavioural priming tasks. Prime-target semantic strength was manipulated by using lexical ambiguity primes (e.g., bank) and target words related to dominant or subordinate meaning of the ambiguity. Subjects made speeded lexical decisions (word/nonword) on dominant related, subordinate related, and unrelated word pairs presented randomly with a short ISI. The major finding was a pattern of reduced activity in middle temporal and inferior prefrontal regions for dominant versus unrelated and subordinate versus unrelated comparisons, respectively. These findings are consistent with both a dual process model of semantic priming and recent repetition priming data that suggest that reductions in BOLD responses represent neural priming associated with automatic semantic activation and implicate the left middle temporal cortex and inferior prefrontal cortex in more automatic aspects of semantic processing.

Adult↗
PubMed2003

Automatic change detection in multimodal serial MRI: application to multiple sclerosis lesion evolution.

The automatic analysis of subtle changes between MRI scans is an important tool for assessing disease evolution over time. Manual labeling of evolutions in 3D data sets is tedious and error prone. Automatic change detection, however, remains a challenging image processing problem. A variety of MRI artifacts introduce a wide range of unrepresentative changes between images, making standard change detection methods unreliable. In this study we describe an automatic image processing system that addresses these issues. Registration errors and undesired anatomical deformations are compensated using a versatile multiresolution deformable image matching method that preserves significant changes at a given scale. A nonlinear intensity normalization method is associated with statistical hypothesis test methods to provide reliable change detection. Multimodal data is optionally exploited to reduce the false detection rate. The performance of the system was evaluated on a large database of 3D multimodal, MR images of patients suffering from relapsing remitting multiple sclerosis (MS). The method was assessed using receiver operating characteristics (ROC) analysis, and validated in a protocol involving two neurologists. The automatic system outperforms the human expert, detecting many lesion evolutions that are missed by the expert, including small, subtle changes.

Algorithms↗
PubMedDate not supplied

Comparison of post-stress ejection fraction and relative left ventricular volumes by automatic analysis of gated myocardial perfusion single-photon emission computed tomography acquired in the supine and prone positions.

BACKGROUND: We have previously described an automatic method for measuring left ventricular ejection fraction (LVEF) for myocardial perfusion single-photon emission computed tomography (SPECT). The repeatability of this method has not been previously described. METHODS AND RESULTS: This study compares LVEF and relative end-systolic and end-diastolic volumes assessed from myocardial perfusion SPECT by our automatic method in 180 consecutive patients undergoing gated myocardial perfusion SPECT with injection of 99mTc-labeled sestamibi in whom the acquisitions were performed sequentially in supine and prone positions. The algorithm operated completely automatically in the prone and supine positions in 178 of the 180 patients. Very high correlations were observed for LVEF (r = 0.93), relative left ventricular end-systolic volume (r = 0.98), and relative left ventricular end-diastolic volume (r = 0.97). The mean paired absolute difference between LVEFs in the prone and supine position was 3.8+/-3.2, for left ventricular end-systolic volume was 4.9+/-4.8 ml, and for left ventricular end-diastolic volume was 7.4+/-6.7 ml. When patients were classified by the extent and severity of stress perfusion defect, there was no significant difference in repeatability for the measurements in any category. CONCLUSIONS: Our algorithm for automatic quantification of LVEF and relative end-systolic and end-diastolic volumes from gated 99mTc sestamibi myocardial perfusion SPECT is repeatable. When performed in the prone position, values of ejection fractions and ventricular volumes are essentially identical to those obtained in the supine position.

Adult↗
PubMed2003

Automatic registration of MR and SPECT images for treatment planning in prostate cancer.

RATIONALE AND OBJECTIVES: To aid in surgical and radiation therapy planning for prostate adenocarcinoma, a general-purpose automatic registration method that is based on mutual information was used to align magnetic resonance (MR) images and single photon emission computed tomographic (SPECT) images of the pelvis and prostate. MATERIALS AND METHODS: The authors assessed the effects of various factors on alignment between pairs of MR and SPECT images, including the use of particular pulse sequences in MR imaging, image voxel intensity scaling, the use of different regions on the MR-SPECT histogram, spatial masking of nonoverlapping visual data between images, and multiresolution optimization. A mutual information algorithm was used as the cost function for automatic registration. Automatic registration was deemed acceptable when it resulted in a transformation with less than 2 voxel units (6 mm) difference in translation and less than 2 degree difference in rotation from that obtained with manual registration performed independently by nuclear medicine radiologists. RESULTS: Paired sets of MR and SPECT image volumes from four of five patients were successfully registered. For successful registration, MR images must be optimal and registration must be performed at full spatial resolution and at the full intensity range. Masking, cropping, and the normalization of mutual information, used to register partially overlapping MR-SPECT volumes, were not successful. Multiresolution optimization had little effect on the accuracy and speed of the registration. CONCLUSION: Automatic registration between MR and SPECT images of the pelvis can be achieved when data acquisition and image processing are performed properly. It should prove useful for prostate cancer diagnosis, staging, and treatment planning.

Adenocarcinoma↗
PubMed1998

Automatic accurate non-invasive quantitation of blood flow, cross-sectional vessel area, and wall shear stress by modelling of magnetic resonance velocity data.

OBJECTIVES: To apply a new, automatic and non-invasive method for quantification of blood flow, dynamic cross-sectional vessel area, and wall shear stress (WSS) by in vivo magnetic resonance velocity mapping of normal subjects. DESIGN: Prospective, open study. MATERIALS: Six young volunteers. METHODS: A three-dimensional paraboloid model enabling automatic determination of blood flow, vessel distensibility and WSS was applied to blood velocity determinations in the common carotid artery. Blood flow was also determined by a manual edge detection method. RESULTS: Using the new method, the common carotid mean blood flow was 7.28 (5.61-9.63) (mean (range)) ml/s. By the manual-method blood flow was 7.21 (5.55-9.60) ml/s. Mean luminal vessel area was 26% larger in peak systole than in diastole. Mean/peak WSS was 0.82/2.28 N/m2. Manually and automatically determined flows correlated (r2 = 0.998, p < 0.0001). WSS and peak centre velocity were associated (r2 = 0.805, p < 0.0001). CONCLUSIONS: Blood flow, luminal vessel area dilatation, and WSS can be determined by the automatic three-dimensional paraboloid method. The hypothesis of association between peak centre velocity and WSS was not contradicted by the results of the present study.

Adult↗
PubMed1999

Clinical and in vitro film quality comparison of manual and automatic exposure control in panoramic radiography.

OBJECTIVE: Automatic exposure control has been used successfully in medicine to improve image quality and reduce the number of retakes necessitated by inadequate operator selection of exposure factors. The purpose of this study was to assess the influence of automatic exposure control on panoramic image quality. STUDY DESIGN: A total of 352 patients were imaged with either the OP 100 or the Orthophos Plus panoramic machine. An expert consensus panel judged film quality using a 5-point scale. Differences in quality that would have resulted from the use of operator-determined exposures were calculated through use of an algorithm validated with test images of a human phantom. RESULTS: McNemar's test demonstrated significant improvements in quality with automatic exposure control (P = .001) in comparison with manual exposure control. No quality difference was found between the 2 machines (P = .9661). Manual exposure selection by oral and maxillofacial radiology residents was better than selection by technologists and assistants (P = .006). CONCLUSIONS: This study confirms the utility of automatic exposure control for panoramic radiography.

Adult↗
PubMed2003

Automatic vs hand-controlled walking of paraplegics.

A rule-based control and its application in functional electrical stimulation (FES) assisted walking of subjects with paraplegia are described in this paper. The design of rules for control comprises the following two steps: (1) determination of muscle activation patterns by using a fully customized spatial (3D) model of paraplegic walking, and (2) learning of rules, that is, correlation between the muscle activation patterns and kinematics of walking by means of an artificial neural network. The adopted FES system activated eight muscle groups with surface electrodes. The only joints allowing movement in the coronal plane were the hips, and externally controlled joints in sagittal plane were ankles, knees and hips. The simulation minimized the tracking error of the joint angles and the total activation of all eight muscles being stimulated. A radial-basis function artificial neural network was applied for learning of rules. Three automatically controlled modes (slow, near-normal, and near-ballistic) and hand-controlled walking were evaluated in six subjects with a complete spinal cord lesion (T8-T10). The performance of walking was assessed by the following: (1) energy consumption based on oxygen uptake, (2) physiological cost index, (3) maximum speed of walking, and (4) a questionnaire. The results showed that all modes of walking are achievable and that automatic control leads to more efficient and faster walking. The speed of walking achieved by automatic control was almost three times bigger compared with the speed of hand-controlled walking. The energy cost and rate decreased significantly when automatic control was applied; yet, they were still much bigger than the values measured in able-bodied subjects. The objective outcome measures suggest that the near-ballistic walking was the most effective, yet a questionnaire shows that most subjects preferred slow walking. The most likely reason for the preference of lower efficiency walking over the faster end energy efficient near-ballistic walking was that paraplegic patients had difficulties in synchronizing the voluntary movement of the trunk and arms to the artificially controlled movements of legs.

Adolescent↗
PubMedDate not supplied

Automatically identifying gene/protein terms in MEDLINE abstracts.

MOTIVATION: Natural language processing (NLP) techniques are used to extract information automatically from computer-readable literature. In biology, the identification of terms corresponding to biological substances (e.g., genes and proteins) is a necessary step that precedes the application of other NLP systems that extract biological information (e.g., protein-protein interactions, gene regulation events, and biochemical pathways). We have developed GPmarkup (for "gene/protein-full name mark up"), a software system that automatically identifies gene/protein terms (i.e., symbols or full names) in MEDLINE abstracts. As a part of marking up process, we also generated automatically a knowledge source of paired gene/protein symbols and full names (e.g., LARD for lymphocyte associated receptor of death) from MEDLINE. We found that many of the pairs in our knowledge source do not appear in the current GenBank database. Therefore our methods may also be used for automatic lexicon generation. RESULTS: GPmarkup has 73% recall and 93% precision in identifying and marking up gene/protein terms in MEDLINE abstracts. AVAILABILITY: A random sample of gene/protein symbols and full names and a sample set of marked up abstracts can be viewed at http://www.cpmc.columbia.edu/homepages/yuh9001/GPmarkup/. Contact. hy52@columbia.edu. Voice: 212-939-7028; fax: 212-666-0140.

Abstracting and Indexing↗