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PubMed2006

Rapid and automatic localization of the anterior and posterior commissure point landmarks in MR volumetric neuroimages.

RATIONALE AND OBJECTIVE: Accurate identification of the anterior commissure (AC) and posterior commissure (PC) is critical in neuroradiology, functional neurosurgery, human brain mapping, and neuroscience research. Moreover, major stereotactic brain atlases are based on the AC and PC. Our goal is to provide an algorithm for a rapid, robust, accurate and automatic identification of AC and PC. MATERIALS AND METHOD: The method exploits anatomical and radiological properties of AC, PC and surrounding structures, including morphological variability. The localization is done in two stages: coarse and fine. The coarse stage locates the AC and PC on the midsagittal plane by analyzing their relationships with the corpus callosum, fornix, and brainstem. The fine stage refines the AC and PC in a well-defined volume of interest, analyzing locations of lateral and third ventricles, interhemispheric fissure, and massa intermedia. RESULTS: The algorithm was developed using simple operations, like histogramming, thresholding, region growing, 1D projections. It was tested on 94 diversified T1W and SPGR datasets. After the fine stage, 71 (76%) volumes had an error between 0-1 mm for the AC and 55 (59%) for the PC. The mean errors were 1.0 mm (AC) and 1.0 mm (PC). The accuracy has improved twice due to fine stage processing. The algorithm took about 1 second for coarse and 4 seconds for fine processing on P4, 2.5 GHz. CONCLUSION: The use of anatomical and radiological knowledge including variability in algorithm formulation aids in localization of structures more accurately and robustly. This fully automatic algorithm is potentially useful in clinical setting and for research.

Algorithms↗
PubMed2006

Rapid and automatic calculation of the midsagittal plane in magnetic resonance diffusion and perfusion images.

RATIONALE AND OBJECTIVES: A near real-time and fully automatic method for calculation of the midsagittal plane (MSP) for magnetic resonance (MR) diffusion and perfusion images is introduced. MATERIALS AND METHODS: The method is based on the Kullback-Leibler's (KL) measure quantifying the difference between two intensity distributions. The MSP is a sagittal plane with the highest KL measure. The method was validated quantitatively for 61 diffusion-weighted imaging (DWI), cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), peak height (PKHT), and time to peak (TPP) data sets of 11 stroke patients based on the ground truth provided by two raters. RESULTS: Average angular errors are less than 1 degrees for DWI and less than 2 degrees for CBF and CBV. Average distance errors measured in the worst case (on the brain's bounding box) are less than 2.5 mm for DWI and less than 5 mm for CBF and CBV. This algorithmic accuracy is at the level of interrater variability. Results obtained for the other perfusions maps (MTT, PKHT, TTP) were inferior; therefore, processing of CBF or CBV is preferred for accurate and robust calculation of the MSP from perfusion maps. Calculation of the MSP takes about half a second on a standard computer. CONCLUSIONS: The proposed method is near real-time and fully automatic, and neither user interaction nor parameter setting is needed. It does not require preprocessing of data. The method potentially is useful in rapid and automated processing of MR stroke diffusion and perfusion images.

Algorithms↗
PubMed2004

Automatic non-associative semantic priming: episodic affective priming of naming responses.

Affective priming for associatively unrelated prime-target pairs was investigated using (a) the naming task, (b) a short stimulus onset asynchrony (250 ms), and (c) primes that had acquired their affective connotation during a differential evaluative conditioning procedure. Despite the fact that the primes and the targets were related on the affective dimension only, significant priming emerged. This finding indicates that mere affective overlap is sufficient to produce automatic priming. As such, our results are in line with theoretical accounts of automatic priming that are based on semantic relatedness.

Affect↗
PubMed2004

Is egocentric space automatically encoded?

Using the criteria defined by Hasher and Zacks [Hasher, L., & Zacks, R. T. (1979). Automatic and effortful processes in memory. Journal of Experimental Psychology: General, 108(3), 356-388], three studies examined the effects of intent of memorization, dual task interference, old age, practice and individual differences on memory for egocentric positions. Results showed that dual task interference and old age slightly influenced memory for egocentric positions. Small but significant individual differences were also observed. However, intent of memorization and practice had no influence on accuracy. The findings demonstrate that encoding of egocentric space works rather automatically but nevertheless requires minimal attentional resources.

Adult↗
PubMed2004

Noninvasive mapping of left ventricular electromechanical asynchrony by three-dimensional echocardiography and semi-automatic contour detection.

A system for analyzing left ventricular (LV) electromechanical asynchrony based on transesophageal 3-dimensional echocardiography (3-DE) and semi-automatic endocardial contour detection is described. Eighteen consecutive patients underwent 3-DE. Using TomTec 4DLV software, a 3-dimensional endocardial surface was reconstructed throughout the cardiac cycle. Matlab software generated color-coded polar maps, displaying regional LV displacement and its timing. At the segmental level, Bland-Altmann assessment showed intraobserver variability of LV displacement of 0.1 +/- 3.0 mm and timing of -5.6 +/- 160 ms (bias +/- 2 SD) for all segments and -1.6 +/- 94 ms for the nonapical segments. The combination of 3-DE and semi-automatic contour detection is feasible and provides unique information for assessing regional LV endocardial displacement and electromechanical asynchrony.

Aged↗
PubMed2006

A design for automatic preparation of highly concentrated 188Re-perrhenate solutions.

Rhenium-188 is extremely suitable for the radiotherapy of balloon dilation for the coronary artery restenosis. To satisfy the need of highly concentrated (188)Re-perrhenate for the clinical applications, we designed an apparatus to achieve the purpose of concentrating (188)Re-perrhenate solution. This apparatus comprised of a concentrator, a control box and a computer with an automatic control program. A column of cation-exchange resin in Ag(+) form and an anion-exchange column in series were used in the concentration procedure. More than 90% of (188)Re isotope in the original solution could be collected with 1mL of 0.9% NaCl solution added to collect the (188)Re adsorbed in the column in this final process (90.7+/-2.2%, n=15). We also found that the radiochemical purity in the final solution remained unchanged (100%). The designed process could automatically increase the quality and efficiency of the production of highly concentrated rhenium-188 solution, and could also reduce the radiation dose absorbed by the operator.

Chromatography, Ion Exchange↗
PubMed2005

Automatic processing of multilingual medical terminology: applications to thesaurus enrichment and cross-language information retrieval.

OBJECTIVES: We present in this article experiments on multi-language information extraction and access in the medical domain. For such applications, multilingual terminology plays a crucial role when working on specialized languages and specific domains. MATERIAL AND METHODS: We propose firstly a method for enriching multilingual thesauri which extracts new terms from parallel corpora, and secondly, a new approach for bilingual lexicon extraction from comparable corpora, which uses a bilingual thesaurus as a pivot. We illustrate their use in multi-language information retrieval (English/German) in the medical domains. RESULTS: Our experiments show that these automatically extracted bilingual lexicons are accurate enough (85% precision for term extraction) for semi-automatically enriching mono- or bi-lingual thesauri such as the universal medical language system, and that their use in cross-language information retrieval significantly improves the retrieval performance (from 22 to 40% average precision) and clearly outperforms existing bilingual lexicon resources (both general lexicons and specialized ones). CONCLUSION: We show in this paper first that bilingual lexicon extraction from parallel corpora in the medical domain could lead to accurate, specialized lexicons, which can be used to help enrich existing thesauri and second that bilingual lexicons extracted from comparable corpora outperform general bilingual resources for cross-language information retrieval.

Electronic Data Processing↗
PubMed2005

Semi-automatic learning of simple diagnostic scores utilizing complexity measures.

OBJECTIVE: Knowledge acquisition and maintenance in medical domains with a large application domain ontology is a difficult task. To reduce knowledge elicitation costs, semi-automatic learning methods can be used to support the domain specialists. They are usually not only interested in the accuracy of the learned knowledge: the understandability and interpretability of the learned models is of prime importance as well. Then, often simple models are more favorable than complex ones. METHODS AND MATERIAL: We propose diagnostic scores as a promising approach for the representation of simple diagnostic knowledge, and present a method for inductive learning of diagnostic scores. It can be incrementally refined by including background knowledge. We present complexity measures for determining the complexity of the learned scores. RESULTS: We give an evaluation of the presented approach using a case base from the fielded system SonoConsult. We further discuss that the user can easily balance between accuracy and complexity of the learned knowledge applying the presented measures. CONCLUSIONS: We argue that semi-automatic learning methods can support the domain specialist efficiently when building (diagnostic) knowledge systems from scratch. The presented complexity measures allow for an intuitive assessment of the learned patterns.

Algorithms↗
PubMed2006

Temporal grouping affects the automatic processing of deviant sounds.

The present study investigates the influence of auditory temporal grouping on automatic sound processing. We compared the mismatch negativity (MMN) event-related potential elicited by successive deviant tones in a condition in which sounds were organized in tone pairs with respective MMN obtained in a non-paired sequence. When successive deviants belonged to different tone pairs the second deviant elicited a higher MMN amplitude than the corresponding deviant in the non-paired condition. Moreover, this temporal grouping had immediate effects on the extraction of rules as revealed by the finding that first and single deviants at the second position of a tone pair elicited larger MMNs than corresponding deviants in the non-paired condition or first and single deviants at the first position of a tone pair. Results demonstrate that auditory objects generated by temporal proximity are treated as relatively encapsulated units and that automatic deviance-detection may rely on multiple hierarchically organized representations of sound sequences.

Adult↗
PubMed2006

Automatic control of biomass gasifiers using fuzzy inference systems.

A fuzzy controller for biomass gasifiers is proposed. Although fuzzy inference systems do not need models to be tuned, a plant model is proposed which has turned out very useful to prove different combinations of membership functions and rules in the proposed fuzzy control. The global control scheme is shown, including the elements to generate the set points for the process variables automatically. There, the type of biomass and its moisture content are the only data which need to be introduced to the controller by a human operator at the beginning of operation to make it work autonomously. The advantages and good performance of the fuzzy controller with the automatic generation of set points, compared to controllers utilising fixed parameters, are demonstrated.

Algorithms↗
PubMed2005

Capillary electrophoresis enhanced by automatic two-way background correction using cubic smoothing splines and multivariate data analysis applied to the characterisation of mixtures of surfactants.

Mixtures of the surfactant classes coconut diethanolamide, cocamido propyl betaine and alkylbenzene sulfonate were separated by capillary electrophoresis in several media containing organic solvents and anionic solvophobic agents. Good resolution between both the surfactant classes and the homologues within the classes was achieved in a BGE containing 80 mM borate buffer of pH 8.5, 20% n-propanol and 40 mM sodium deoxycholate. Full resolution, assistance in peak assignment to the classes (including the recognition of solutes not belonging to the classes), and improvement of the signal-to-noise ratio was achieved by multivariate data analysis of the time-wavelength electropherograms. Cubic smoothing splines were used to develop an algorithm capable of automatically modelling the two-way background, which increased the sensitivity and reliability of the multivariate analysis of the corrected signal. The exclusion of significant signals from the background model was guaranteed by the conservativeness of the criteria used and the safeguards adopted all along the point selection process, where the CSS algorithm supported the addition of new points to the initially reduced background sample. Efficient background modelling made the application of multivariate deconvolution within extensive time windows possible. This increased the probability of finding quality spectra for each solute class by orthogonal projection approach. The concentration profiles of the classes were improved by subsequent application of alternating least squares. The two-way electropherograms were automatically processed, with minimal supervision by the user, in less than 2 min. The procedure was successfully applied to the identification and quantification of the surfactants in household cleaners.

Electrophoresis, Capillary↗
PubMed2005

Delayed automatic detection of change in speech sounds in adults with autism: a magnetoencephalographic study.

OBJECTIVE: Autism is a form of pervasive developmental disorder in which dysfunction in interpersonal relationships and communication is fundamental. This study evaluated neurophysiological abnormalities at the basic level of language processing, i.e. automatic change detection of speech and non-speech sounds, using magnetoencephalographic recording of mismatch response elicited by change in vowels and tones. METHODS: The auditory magnetic mismatch field (MMF) was evaluated in 9 adults with autism and 19 control subjects using whole-head magnetoencephalography. The MMF in response to the duration change of a pure tone or vowel /a/ and that in response to across-phoneme change between vowels /a/ and /o/, were recorded. RESULTS: The groups were not significantly different in MMF power under any conditions. However, the autism group showed a left-biased latency prolongation of the MMF particularly under the across-phoneme change condition, and this latency delay was significantly associated with greater symptom severity. CONCLUSIONS: These results suggest that adults with autism are associated with delayed processing for automatic change detection of speech sounds. These electrophysiological abnormalities at the earliest level of information processing may contribute to the basis for language deficits observed in autism. SIGNIFICANCE: These results provide the first evidence for delayed latency of phonetic MMF in adults with autism.

Acoustic Stimulation↗
PubMed2004

Semia: semi-automatic interactive graphic editing tool to annotate ambulatory ECG records.

We designed and developed a special purpose interactive graphic editing tool semi-automatic (Semia) to annotate transient ischaemic ST segment episodes and other non-ischaemic ST segment events in 24h ambulatory electrocardiogram (ECG) records. The tool allows representation and viewing of the data, interaction with the data globally and locally at different resolutions, examining data at any point, manual adjustment of heart-beat fiducial points, and manual and automatic editing of annotations. Efficient and fast display of ambulatory ECG signal waveforms, display of diagnostic and morphology feature-vector time-series, dynamic interface controls, and automated procedures to help annotate, made the tool efficient, user friendly and usable. Human expert annotators used the Semia tool to successfully annotate the Long-Term ST database (LTST DB), a result of a multinational effort. The tool supported paperless editing of annotations at dislocated geographical sites. We present design, characteristic "look and feel", functionality, and development of Semia annotating tool.

Ambulatory Care Information Systems↗
PubMed2005

Automatic extraction of brain surface and mid-sagittal plane from PET images applying deformable models.

In this study, we propose and evaluate new methods for automatic extraction of the brain surface and the mid-sagittal plane from functional positron emission tomography (PET) images. Designing methods for these segmentation tasks is challenging because the spatial distribution of intensity values in a PET image depends on the applied radiopharmaceutical and the contrast to noise ratio in a PET image is typically low. We extracted the brain surface with a deformable model which is based on a global optimization algorithm. The global optimization allows reliable automation of the extraction task. Based on the extracted brain surface, the mid-sagittal plane was determined. The method was tested with the image of the Hoffman brain phantom (FDG) and the images from the brain studies with the FDG (17 images) and the C11-Raclopride tracers (4 images). In addition to the brain surfaces, we applied the deformable model for extraction of the coarse cortical structure based on the tracer uptake from FDG-PET brain images. The proposed segmentation methods provide a promising direction for automatic processing and analysis of PET brain images.

Adult↗
PubMed2005

Experience modulates automatic imitation.

Action observation gives rise to activation in corresponding areas of the premotor and primary motor cortices. We tested the hypothesis that this activation depends on visual-motor connections established through correlated experience of observing and executing the same action. Previous work has shown that hand opening and hand closing gestures are facilitated when subjects observe the movement they are performing, relative to a condition in which they observe a different movement from the one they are performing. Experiment 1 replicated this finding in a simple reaction time (RT) procedure using stimulus-response (SR) movements in orthogonal planes. This implies that the effect is an example of automatic imitation, an instruction-independent tendency to execute movements that are topologically similar to those observed, and not merely an example of spatially compatible responding. In Experiment 2, the automatic imitation effect found in Experiment 1 was abolished by a brief period of training in which subjects responded to hand opening by closing their hands, and to hand closing by opening their hands. This outcome is consistent with the hypothesis that, rather than being innate, the cortical connections mediating motor activation by action observation are formed through experience.

Adult↗
PubMed2005

Robotic movement elicits automatic imitation.

Recent behavioural and neuroimaging studies have found that observation of human movement, but not of robotic movement, gives rise to visuomotor priming. This implies that the 'mirror neuron' or 'action observation-execution matching' system in the premotor and parietal cortices is entirely unresponsive to robotic movement. The present study investigated this hypothesis using an 'automatic imitation' stimulus-response compatibility procedure. Participants were required to perform a prespecified movement (e.g. opening their hand) on presentation of a human or robotic hand in the terminal posture of a compatible movement (opened) or an incompatible movement (closed). Both the human and the robotic stimuli elicited automatic imitation; the prespecified action was initiated faster when it was cued by the compatible movement stimulus than when it was cued by the incompatible movement stimulus. However, even when the human and robotic stimuli were of comparable size, colour and brightness, the human hand had a stronger effect on performance. These results suggest that effector shape is sufficient to allow the action observation-matching system to distinguish human from robotic movement. They also indicate, as one would expect if this system develops through learning, that to varying degrees both human and robotic action can be 'simulated' by the premotor and parietal cortices.

Adult↗
PubMed2004

Validation of automatically measured monophasic action potential recordings.

This study devised an automatic monophasic action potential (MAP) measurement program, and compared the computer-measured MAP durations with those measured manually by two independent observers in order to facilitate the analysis of MAP data obtained during a clinical electrophysiology study. The results were compared at various cycle lengths and during pharmacologic or physiologic interventions. This program identified the onset, plateau, and baseline accurately using the MAP data. The automatically measured MAP durations at the 90% repolarization level (MAPd) strongly correlated with those measured manually (r = 0.99). The MAPd shortened in parallel as the pacing cycle length was progressively shortened from 800 to 600, 400 and 300 ms.

Action Potentials↗
PubMed2005

Automatic noise robust registration of radiographs for subtraction using strategic local correlation: an application to radiographs of dental implants.

Most of digital subtraction methods in dental radiography are based on registration using manual landmarks. We have developed an automatic registration method without using the manual selection of landmarks. By restricting a geometrical matching of images to a region of interest (ROI), we compare the cross-correlation coefficient only between the ROIs. The affine or perspective transform parameters satisfying maximum of cross-correlation between the local regions are searched iteratively by a fast searching strategy. The parameters are searched on the 14 scale image coarsely and then, the fine registration is performed on the original scale image. The developed method can match the images corrupted by Gaussian noise with the same accuracy for the images without any transform simulation. The registration accuracy of the perspective method shows a 17% improvement over the manual method. The application of the developed method to radiographs of dental implants provides an automatic noise robust registration with high accuracy in almost real time.

Dental Implants↗