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PubMed2000

Automatic labelling of the human cortical surface using sulcal basins.

Human brain mapping aims at establishing correspondences between brain function and brain anatomy. One of the most intriguing problems in this field is the high interpersonal variability of human neuroanatomy which makes studies across many subjects very difficult. The cortical folds ('sulci') often serve as landmarks that help to establish correspondences between subjects. In this paper, we will present a method that automatically detects and attributes neuroanatomical names to the cortical folds using image analysis methods applied to magnetic resonance data of human brains. We claim that the cortical folds can be subdivided into a number of substructures which we call sulcal basins. The concept of sulcal basins allows us to establish a complete parcellation of the cortical surface into separate regions. These regions are neuroanatomically meaningful and can be identified from MR data sets across many subjects. Sulcal basins are segmented using a region growing approach. The automatic labelling is achieved by a model matching technique.

Algorithms↗
PubMed2002

Automatic detection and segmentation of evolving processes in 3D medical images: Application to multiple sclerosis.

The study of temporal series of medical images can be helpful for physicians to perform pertinent diagnoses and to help them in the follow-up of a patient: in some diseases, lesions, tumors or anatomical structures vary over time in size, position, composition, etc., either because of a natural pathological process or under the effect of a drug or a therapy. It is a laborious and subjective task to visually and manually analyze such images. Thus the objective of this work was to automatically detect regions with apparent local volume variation with a vector field operator applied to the local displacement field obtained after a non-rigid registration between two successive temporal images. On the other hand, quantitative measurements, such as the volume variation of lesions or segmentation of evolving lesions, are important. By studying the information of apparent shrinking areas in the direct and reverse displacement fields between images, we are able to segment evolving lesions. Then we propose a method to segment lesions in a whole temporal series of images. In this article we apply this approach to automatically detect and segment multiple sclerosis lesions that evolve in time series of MRI scans of the brain. At this stage, we have only applied the approach to a few experimental cases to demonstrate its potential. A clinical validation remains to be done, which will require important additional work.

Automation↗
PubMed1997

Demonstration of accuracy and clinical versatility of mutual information for automatic multimodality image fusion using affine and thin-plate spline warped geometric deformations.

This paper applies and evaluates an automatic mutual information-based registration algorithm across a broad spectrum of multimodal volume data sets. The algorithm requires little or no pre-processing, minimal user input and easily implements either affine, i.e. linear or thin-plate spline (TPS) warped registrations. We have evaluated the algorithm in phantom studies as well as in selected cases where few other algorithms could perform as well, if at all, to demonstrate the value of this new method. Pairs of multimodal gray-scale volume data sets were registered by iteratively changing registration parameters to maximize mutual information. Quantitative registration errors were assessed in registrations of a thorax phantom using PET/CT and in the National Library of Medicine's Visible Male using MRI T2-/T1-weighted acquisitions. Registrations of diverse clinical data sets were demonstrated including rotate-translate mapping of PET/MRI brain scans with significant missing data, full affine mapping of thoracic PET/CT and rotate-translate mapping of abdominal SPECT/CT. A five-point thin-plate spline (TPS) warped registration of thoracic PET/CT is also demonstrated. The registration algorithm converged in times ranging between 3.5 and 31 min for affine clinical registrations and 57 min for TPS warping. Mean error vector lengths for rotate-translate registrations were measured to be subvoxel in phantoms. More importantly the rotate-translate algorithm performs well even with missing data. The demonstrated clinical fusions are qualitatively excellent at all levels. We conclude that such automatic, rapid, robust algorithms significantly increase the likelihood that multimodality registrations will be routinely used to aid clinical diagnoses and post-therapeutic assessment in the near future.

Abdomen↗
PubMed1998

Automatic construction of eigenshape models by direct optimization.

A new approach to the problem of automatic construction of eigenshape models is presented. Eigenshape models have proved to be successful in a variety of medical image analysis problems. However, automatic construction of eigenshape models has proved to be a difficult problem, and in many applications the models are built by hand-a painstaking process. We show that the fundamental problem is a choice of the correct pose and parametrization of each shape in the training set. Eigenshape models are not invariant under reparametrizations and pose transformations of the training shapes. Since there is no a priori correct choice for the pose and parametrization of each shape, their value should be chosen so as to produce a model that is compact and specific. This problem can be solved by finding an objective function that measures these properties and varying the pose and parametrization of each shape to optimize this function. We show that the appropriate objective function is the determinant of the covariance matrix. We go on to show how this objective function can be optimized by a genetic algorithm (GA) and thus give a practical method for building eigenshape models. The models produced are often better than hand-built ones. The advantages of a GA over other choices of optimization method are that no assumptions about the nature of the shapes being modelled is required and that the global minimum of the objective function can, in principle, be found.

Algorithms↗
PubMed2003

Automatic concept extraction from spoken medical reports.

OBJECTIVE: The objective of this project is to investigate methods whereby a combination of speech recognition and automated indexing methods substitute for current transcription and indexing practices. METHODS: We based our study on existing speech recognition software programs and on NOMINDEX, a tool that extracts MeSH concepts from medical text in natural language and that is mainly based on a French medical lexicon and on the UMLS. For each document, the process consists of three steps: (1) dictation and digital audio recording, (2) speech recognition, (3) automatic indexing. The evaluation consisted of a comparison between the set of concepts extracted by NOMINDEX after the speech recognition phase and the set of keywords manually extracted from the initial document. The method was evaluated on a set of 28 patient discharge summaries extracted from the MENELAS corpus in French, corresponding to in-patients admitted for coronarography. RESULTS: The overall precision was 73% and the overall recall was 90%. Indexing errors were mainly due to word sense ambiguity and abbreviations. A specific issue was the fact that the standard French translation of MeSH terms lacks diacritics. A preliminary evaluation of speech recognition tools showed that the rate of accurate recognition was higher than 98%. Only 3% of the indexing errors were generated by inadequate speech recognition. DISCUSSION: We discuss several areas to focus on to improve this prototype. However, the very low rate of indexing errors due to speech recognition errors highlights the potential benefits of combining speech recognition techniques and automatic indexing.

Abstracting and Indexing↗
PubMed2000

Automatic carpal tunnel syndrome tester.

OBJECTIVE: A device for automatic testing of sensory latency across the carpal tunnel is described. A fixed bar contains a stimulating electrode distally and a bipolar recording set up with the two poles at 7 and 14 cm distance proximally. The device is thus based on the so called 14/7 method, using orthodromic testing. METHODS: Automatic testing of electrode resistance and muscle relaxation precedes the self triggered start of stimulation. The latencies are analyzed according to a special algorithm. The proximal/distal latency index is increased in carpal tunnel syndrome (CTS). RESULTS: Healthy controls (32 hands in 32 subjects) and patients referred with suspicion of CTS (258 hands) were studied with the new device, by conventional technique and sometimes by inching (centimetering) across the carpal tunnel. A positive CTS result with the tester was in accordance with the routine test in 94% of the patients. Conversely, routine studies showed CTS in 118 hands. Among those, the tester agreed in 44, showed no signals in 70 and indicated normal findings in 4 hands. In cases with a combination of polyneuropathy and CTS, the CTS was detected in 5 out of 6 cases. A complete test takes about 1 min per hand. CONCLUSIONS: The results are very promising.

Adult↗
PubMed2002

An automatic method for the recognition and classification of the A-phases of the cyclic alternating pattern.

OBJECTIVES: The aim of this research has been to introduce an automatic method, simple from the mathematical and computational points of view, for the recognition and classification of the A-phases of the cyclic alternating pattern. METHODS: The automatic method was based on the computation of 5 descriptors, which were derived from the EEG signal and were able to provide a meaningful data reduction. Each of them corresponded to a different frequency band. RESULTS: The computation of these descriptors, followed by the introduction of two suitable thresholds and of simple criteria for logical discrimination, provided results which were in good agreement with those obtained with visual analysis. The method was versatile and could be applied to the study of other important microstructure phenomena by means of very small adaptations. CONCLUSIONS: The simplicity of the method leads to a better understanding and a more precise definition of the visual criteria for the recognition and classification of the microstructure phenomena.

Adult↗
PubMed2003

Wavelet based automatic seizure detection in intracerebral electroencephalogram.

BACKGROUND: Automatic seizure detection is often used during long-term monitoring, and is particularly important during intracerebral investigations. Existing methods make many false detections, particularly in intracerebral electroencephalogram (EEG) because of frequent large amplitude rhythmic activity bursts that are non-epileptiform. OBJECTIVE: To develop a seizure detection method for intracerebral monitoring that is as sensitive as existing methods but has fewer false detections. METHODS: To capture the rhythmic nature of seizure discharges, we developed a wavelet-based method, examining how different frequency ranges fluctuate compared to the background. In particular, the system remembers rhythmic bursts occurring commonly in the background to avoid detecting them as seizures. RESULTS: The method was evaluated on test data from 11 patients, including 229 h and 66 seizures, and its performance compared to the method of Gotman (Electroencephalogr clin Neurophysiol 76 (1990) 317). Detection sensitivity was unchanged at close to 90%, but false detections were reduced from 2.4 to 0.3/h. CONCLUSIONS: Perfect sensitivity is unlikely because the morphology of seizure discharges is so variable. Nevertheless, the 87% sensitivity obtained in the combined training and testing data is quite high. We reduced the average false alarm rate to one per 3 h of recording, or 6 per 24-h period. Given how rapidly one can decide visually that a detection is erroneous, false detections should not cause any burden to the reviewer. SIGNIFICANCE: In intracerebral EEG it is possible to detect seizures automatically with high sensitivity and high specificity.

Electroencephalography↗
PubMed1999

Spike detection II: automatic, perception-based detection and clustering.

OBJECTIVES: We developed perception-based spike detection and clustering algorithms. METHODS: The detection algorithm employs a novel, multiple monotonic neural network (MMNN). It is tested on two short-duration EEG databases containing 2400 spikes from 50 epilepsy patients and 10 control subjects. Previous studies are compared for database difficulty and reliability and algorithm accuracy. Automatic grouping of spikes via hierarchical clustering (using topology and morphology) is visually compared with hand marked grouping on a single record. RESULTS: The MMNN algorithm is found to operate close to the ability of a human expert while alleviating problems related to overtraining. The hierarchical and hand marked spike groupings are found to be strikingly similar. CONCLUSIONS: An automatic detection algorithm need not be as accurate as a human expert to be clinically useful. A user interface that allows the neurologist to quickly delete artifacts and determine whether there are multiple spike generators is sufficient.

Adolescent↗
PubMed1999

Automatic detection of cyclic alternating pattern (CAP) sequences in sleep: preliminary results.

OBJECTIVES: The analysis of cyclic alternating pattern (CAP) provides important microstructural information on arousal instability and on EEG synchrony modulation in the sleep process. This work presents a methodology for automatic classification of the micro-organization of human sleep EEG, using the CAP paradigm. METHODS: The classification system is composed of 3 parts: feature extraction, detection and classification. The feature extraction part is an EEG generation model-based maximum likelihood estimator. The detector part for the CAP phases A and B is done by a variable length template matched filter, while the classification criteria part is implemented on a state machine ruled-based decision system. RESULTS AND CONCLUSIONS: The preliminary results of the automatic classifier on a group of 4 middle-aged adults are presented. The high agreement between the detector and visual scoring is very promising in the achievement of a fully automated scoring system, although a more exhaustive evaluation program is needed.

Adult↗
PubMed2003

An automatic ambulatory device for detection of AASM defined arousals from sleep: the WP100.

OBJECTIVES AND BACKGROUND: Arousals from sleep are associated with increased sympathetic activation and therefore with peripheral vasoconstriction. Sleep fragmentation in the form of multiple arousals is associated with daytime somnolence and cognitive impairment; however, manual scoring of arousal is time consuming and problematic due to relatively high inter-scorer variability. We have recently shown that automated analysis of in-lab recorded peripheral arterial tone (PAT) signal and the pulse rate derived from it can accurately assess arousals from sleep as defined by the American Academy of Sleep Medicine (AASM). In the current study we sought to extend these findings to the Watch_PAT100 (WP100), an ambulatory device measuring PAT, oximetry and actigraphy. METHODS: Sixty-eight subjects (61 patients referred to the sleep lab with suspected obstructive sleep apnea and seven healthy volunteers, mean age 46.3+/-14.2 years) underwent a whole night polysomnography (PSG) with simultaneous recording of PAT signal by the ambulatory WP100 device. The PSG recordings were blindly manually analyzed for arousals based on AASM criteria, while PAT was scored automatically based on the algorithm developed previously. RESULTS: There was a significant correlation between AASM arousals derived from the PSG and PAT autonomic arousals derived from the WP100 (R=0.87, P<0.001), with a good agreement across a wide range of values. The sensitivity and specificity of PAT in detecting patients with at least 20 arousals per hour of sleep were 0.80 and 0.79, respectively, with a receiver operating characteristic curve having an area under the curve of 0.87. CONCLUSIONS: We conclude that automatic analysis of peripheral arterial tonometry signal derived from the ambulatory device Watch_PAT100 can accurately identify arousals from sleep in a simple and time saving fashion.

Adult↗
PubMed1995

Automatic-interactive measurement of resorption cavities in transiliac bone biopsies and correlation with deoxypyridinoline.

Measuring bone resorption accurately by histomorphometry of bone biopsies is a challenge. Several techniques have been proposed including the measurement of eroded surfaces and resorption depth, but they have not been compared between themselves nor with biochemical assessment of bone resorption. In addition, there is a need for a rapid method that could be used more routinely. We describe here an automatic interactive method using a color analyzer (Visiolab, BIOCOM, France) with a specific software for the evaluation of erosion depth, eroded volume, eroded surface, osteoclast number, and surface. Thirty transiliac undecalcified bone biopsies stained with Goldner's trichrome were used in this study, taken from subjects suffering from osteoporosis or primary hyperparathyroidism. At the time of the biopsy a 2 h fasting morning urine sample was collected for measurement by HPLC of total deoxypyridinoline, the most sensitive marker of bone resorption. There was a highly significant correlation between maximum erosion depth measured directly and the one calculated according to the count of eroded lamellae (E. F. Eriksen, et al. Metab Bone Dis Relat Res 5:243-252; 1984) (r = 0.76; p = 0.0001). A significant correlation was found between urinary deoxypyridinoline and eroded volume/bone volume in cancellous and endocortical bone measured with the automatic interactive technique (r = 0.48; p = 0.007). In contrast, other histological indexes of bone resorption did not correlate with urinary deoxypyridinoline. The volume of resorption cavities appears to be the most valid index of bone resorption rate as it was correlated with the urinary excretion of total deoxypyridinoline.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2002

Deficits in automatically detecting changes in conjunction of auditory features in patients with schizophrenia.

Disturbances in processing simple acoustic changes in a stream of stimuli have been widely reported in patients with schizophrenia, but little is know about auditory feature conjunction in these individuals. This study was designed to examine the extent to which patients with schizophrenia automatically process changes in conjunction of auditory features by using event-related brain potentials. Seventeen patients and 17 age-matched controls were presented with frequent low pitch tones at 45 degrees to the left of center and frequent high pitch tones at 45 degrees to the right of center while performing a continuous visual serial-choice reaction time task. The sequence of auditory stimuli included rare conjunction-deviants comprised of a different combination of features (e.g., low pitch tone at 45 degrees right) and double-deviant tones that differed from the standard tones in both pitch and location (i.e., middle pitch at 0 degrees azimuth). Conjunction-deviant stimuli elicited an MMN wave that was maximum at frontocentral sites. Compared with controls, the MMN to conjunction-deviant was reduced in patients and was more centrally distributed. Double-deviant sounds generated a biphasic MMN followed by a P3a wave at central sites. Both MMN and P3a were reduced in patients compared with controls. These results show that patients with schizophrenia have difficulty in automatically detecting changes in a combination of auditory features as well as orienting to what "normally" would be considered salient by healthy individuals.

Acoustic Stimulation↗
PubMed2002

Automatic processing of tones and speech stimuli in children with specific language impairment.

It is well known from behavioural experiments that children with specific language impairment (SLI) have difficulties discriminating consonant-vowel (CV) syllables such as /ba/, /da/, and /ga/. Mismatch negativity (MMN) is an auditory event-related potential component that represents the outcome of an automatic comparison process. It could, therefore, be a promising tool for assessing central auditory processing deficits for speech and non-speech stimuli in children with SLI. MMN is typically evoked by occasionally occurring 'deviant' stimuli in a sequence of identical 'standard' sounds. In this study MMN was elicited using simple tone stimuli, which differed in frequency (1000 versus 1200 Hz) and duration (175 versus 100 ms) and to digitized CV syllables which differed in place of articulation (/ba/, /da/, and /ga/) in children with expressive and receptive SLI and healthy control children (n=21 in each group, 46 males and 17 females; age range 5 to 10 years). Mean MMN amplitudes between groups were compared. Additionally, the behavioural discrimination performance was assessed. Children with SLI had attenuated MMN amplitudes to speech stimuli, but there was no significant difference between the two diagnostic subgroups. MMN to tone stimuli did not differ between the groups. Children with SLI made more errors in the discrimination task, but discrimination scores did not correlate with MMN amplitudes. The present data suggest that children with SLI show a specific deficit in automatic discrimination of CV syllables differing in place of articulation, whereas the processing of simple tone differences seems to be unimpaired.

Acoustic Stimulation↗
PubMed1986

Controlled and automatic information processing in senile dementia: a review.

The evidence on cognitive decline in senile dementia is reviewed with respect to the distinction between controlled and automatic processing. It is argued that controlled processing, which requires the attentional resources of the individual, declines in early senile dementia. However, automatic processing, which does not require attentional resources, is well maintained until late in the disorder. Implications of this view are drawn for the development of effective screening instruments which can be used for the early detection of dementia in the general population.

Aged↗
PubMed1999

Concerning the automaticity of syntactic processing.

In a within-subjects design, event-related potentials were compared for two types of sentence-final syntactic errors: Incorrect verb inflection and incorrect word category (phrase structure). In a grammatical judgment task, these errors triggered robust N400 and P600 components. To assess the degree of automaticity of the underlying linguistic processes, the N400 and P600 effects were measured in a task for which the participants judged whether a word in a sentence was printed in upper case. In this physical judgment task, the N400 and P600 following verb inflection errors were greatly attenuated or absent, whereas those elicited by word category violation were only slightly diminished in amplitude. The data suggest that word category information is processed more automatically than inflectional information. The P600 appears to reflect a relatively controlled language-related process.

Adult↗
PubMed1978

Automatic quantitative analysis of the electromyogram in partially denervated distal muscles: comparison with motor unit counting.

Using the ANOPS-101 minicomputer, an automatic analysis of muscle action potentials (MAP) was performed on a total of 53 extensor digitorum brevis (EDB) and abductor pollicis brevis (APB) muscles in patients with other evidence of denervation. The results were compared with observations made on 27 control subjects and they were also matched against estimates of functioning motor units made by the incremental stimulating technique of McComas et al (1971). Although the incidence of abnormal MAP parameters was relatively low in both muscles, it was possible to improve the diagnostic yield by combining the results for individual muscles. The relative merits and disadvantages of motor unit counting and automatic MAP analysis are discussed.

Adult↗
PubMed2006

The role of the basal ganglia in the control of automatic visuospatial attention.

Cognitive impairments in patients with basal ganglia dysfunction are primarily revealed where performance relies on internal, voluntary control processes. Evidence suggests that this also extends to impaired control of more automatic processes, including visuospatial attention. The present study used a non-predictive peripheral cueing paradigm to compare and contrast visuospatial deficits in patients with Parkinson's disease (PD) with those previously revealed in patients with Huntington's disease (HD) (Fielding et al., 2006a). Compared to age-matched controls, both PD and HD patients exhibited increased distractibility or poor fixation, however only PD patients responded erroneously to cue stimuli more frequently than control subjects. All subjects demonstrated initial facilitation for valid versus invalid cues following the shorter stimulus-onset asynchronies (SOAs) and a performance decrement at the longer SOAs (inhibition of return), although there was a clear differentiation between these groups for immediate SOAs. Unlike both control and PD subjects, where IOR manifested between 350 and 1000 msec, IOR was evident as early as 150 msec for HD patients. Further, for PD patients, spatially valid cues resulted in hyper-reflexivity following 150 msec SOAs, with saccadic latencies shorter than those generated in response to un-cued targets. Thus contrasting deficits were revealed in PD and HD, emphasizing the important contribution of the basal ganglia in the control of more automatic behaviors

Aged↗