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PubMed2003

[Automatization and robotics of the set-up and treatment of patients irradiated for brain and base ot the skull tumors].

Progresses of the three-dimensional imageries and of the software of planning systems makes that the radiotherapy of the tumours of brain and the base of skull is increasingly precise. The set-up of the patients and the positioning of the beams are key acts whose realization can become extremely tiresome if the requirement of precision increases. This precision very often rests still on the visual comparison of digital images. In the near future, the development of the automated systems controlled by robots should allow a noticeable improvement of the precision, safety and speed of the patient set-up.

Automation↗
PubMed2006

Feature extraction for EEG-based brain-computer interfaces by wavelet packet best basis decomposition.

A method based on wavelet packet best basis decomposition (WPBBD) is investigated for the purpose of extracting features of electroencephalogram signals produced during motor imagery tasks in brain-computer interfaces. The method includes the following three steps. (1) Original signals are decomposed by wavelet packet transform (WPT) and a wavelet packet library can be formed. (2) The best basis for classification is selected from the library. (3) Subband energies included in the best basis are used as effective features. Three different motor imagery tasks are discriminated using the features. The WPBBD produces a 70.3% classification accuracy, which is 4.2% higher than that of the existing wavelet packet method.

Adult↗
PubMed2002

Fast in vivo water quantification in rat brain oedema based on T(1) measurement at high magnetic field.

BACKGROUND: In vivo water content determination based on magnetic resonance (MR) method is of importance in clinical practice as well as in animal studies to follow up the treatment given in order to reduce brain oedema. The methods proposed in the literature so far are largely time consuming. The aim of this study was to find a fast in vivo water quantification method having real advantage for patients suffering from critical conditions. METHOD: Cold injury was applied to provoke brain oedema in fourteen rats. T(1) values of both the oedematous area and the contralateral normal cortex were determined by two independent methods 24 hours after the cold impact. First, from a series of images recorded by inversion recovery spin echo (IRSE) sequence and then by progressive saturation experiment performed by localised MR spectroscopy using stimulated echo acquisition mode (STEAM). To reduce the acquisition time, a two-element repetition time array was optimised for the STEAM experiment, whereas four inversion times were used for T(1) mapping. Both methods were validated against gel phantoms with known T(1) values. After the MR measurements the animals were sacrificed and the water contents of the regions of interest were determined by gravimetric wet-dry method. FINDINGS: The reciprocals of the in vivo measured T(1) values were correlated with the reciprocals of the brain water contents. STEAM experiment showed stronger correlation (r=0.96) than IRSE (r=0.93). In addition, STEAM provided more accurate T(1) values in the phantom study. Determination of brain water content based on T1 measurement does work also at high magnetic field. Determination of brain water content by Magnetic Resonance Spectroscopy is feasible within 2 minutes. INTERPRETATION: Using the presented fast method, water content can be determined within a couple of minutes in animal experiments as well as in the daily clinical practice.

Animals↗
PubMedDate not supplied

Diffusion MRI: apparent diffusion coefficient (ADC) values in the normal brain and a classification of brain disorders based on ADC values.

Diffusion-weighted imaging, dependent on motion of water molecules, provides information regarding tissue integrity. Apparent diffusion coefficient (ADC) values in the normal brain parenchyma, and those in a variety of lesions were studied by echo-planar diffusion MRI in 310 cases. Brain disorders were classified based on their ADC values, taking the ADC values of the normal brain white matter as the principal category. In the normal white matter ADC ranges were 0.60-1.05x10(-3)mm(2)/s, and the mean ADC value was 0.84+/-0.11x10(-3)mm(2)/s. It was possible to distribute brain disorders, as well as artefacts on diffusion MRI to five major categories: category 1, ADC similar to normal white matter; category 2, ADC lower than normal white matter; category 3, ADC higher than normal white matter; category 4, ADC similar to CSF; and category 5, markedly low or high ADC. Further studies can provide addition of different lesions as well as refinements of these categories.

Adolescent↗
PubMed1998

Answering questions with an electroencephalogram-based brain-computer interface.

OBJECTIVE: To demonstrate that humans can learn to control selected electroencephalographic components and use that control to answer simple questions. METHODS: Four adults (one with amyotrophic lateral sclerosis) learned to use electroencephalogram (EEG) mu rhythm (8 to 12Hz) or beta rhythm (18 to 25Hz) activity over sensorimotor cortex to control vertical cursor movement to targets at the top or bottom edge of a video screen. In subsequent sessions, the targets were replaced with the words YES and NO, and individuals used the cursor to answer spoken YES/NO questions from single- or multiple-topic question sets. They confirmed their answers through the response verification (RV) procedure, in which the word positions were switched and the question was answered again. RESULTS: For 5 consecutive sessions after initial question training, individuals were asked an average of 4.0 to 4.6 questions per minute; 64% to 87% of their answers were confirmed by the RV procedure and 93% to 99% of these answers were correct. Performances for single- and multiple-topic question sets did not differ significantly. CONCLUSIONS: The results indicate that (1) EEG-based cursor control can be used to answer simple questions with a high degree of accuracy, (2) attention to auditory queries and formulation of answers does not interfere with EEG-based cursor control, (3) question complexity (at least as represented by single versus multiple-topic question sets) does not noticeably affect performance, and (4) the RV procedure improves accuracy as expected. Several options for increasing the speed of communication appear promising. An EEG-based brain-computer interface could provide a new communication and control modality for people with severe motor disabilities.

Adult↗
PubMed1997

The body in the brain: neural bases of corporeal awareness.

Recent studies have begun to unravel the brain mechanisms that underlie the mental representation of the body. Imitation of movements by neonates suggests an implicit knowledge of the body structure that antedates the adult body schema. This can include inanimate objects that bear systematic relations to the body, as shown by the elimination from self awareness of a body part and its associated paraphernalia after selective brain lesions. Dynamic aspects of the body schema are revealed by spontaneous sensations from a lost body part as well as by orderly phantom sensations elicited by stimulation of body areas away from the amputation line and even by visual stimulation. The mechanisms of the body schema exhibit stability, since some brain regions seem permanently committed to representing the corresponding body parts in conscious awareness, and plasticity, since brain regions deprived of their natural inputs from a body part become reactive to inputs from other body parts.

Adult↗
PubMedDate not supplied

Extent of cognitive decline in traumatic brain injury based on estimates of premorbid intelligence.

Global cognitive impairment following traumatic brain injury (TBI) is common, with some abilities more significantly affected than others. However, due to difficulties in estimating premorbid intelligence, there has been no systematic evaluation of the extent of decline in different cognitive abilities following TBI. Recent studies indicate that the Wide Range Achievement Test-Revised (WRAT-R) Reading subtest is an accurate estimate of premorbid intelligence, suggesting that post-TBI cognitive test scores can be compared to the WRAT-R to estimate the extent of decline that occurs in specific cognitive abilities. The current study estimated the extent of deficit in intelligence, memory, attention, speed of processing, and cognitive flexibility for 97 outpatients with TBI. Extent of decline was calculated by subtracting WRAT-R z-scores from cognitive test z-scores to determine a z-difference score (ZDiff) for each cognitive ability. The results suggest that intelligence is least declined following TBI (WAIS-R 3-4-point decline; VIQ ZDiff = -0.23: FIQ ZDiff = -0.27), followed by attention (WMS-R 5-point decline; ZDiff = -0.31), memory (WMS-R 6-9-point decline; Verbal Memory ZDiff = -0.41; General Memory ZDiff = -0.51; Delay Memory ZDiff = -0.57), speed of processing (Trails A 15-16 second decline; ZDiff = -1.90) and cognitive flexibility (Trails B 35-52 second decline; ZDiff = -2.65). Implications for provision of feedback to individuals with TBI and their families are discussed.

Adolescent↗
PubMed1997

Effects of thalamic deep brain stimulation based on tremor type and diagnosis.

It has been suggested that deep brain stimulation (DBS) is less effective in alleviating proximal than distal postural arm tremor reduction is said to be less in essential tremor (ET) than in Parkinson's disease (PD). We analyzed blinded rater's tremor scores and subjects' disability ratings at 3-month follow-up to examine the effects of DBS based on tremor type (rest, kinetic, distal postural, proximal postural) and diagnosis (ET, PD). An independent examiner provided tremor scores using randomized videotaped footage of 19 ET and 10 PD subjects at baseline and at follow-up with DBS "on." Subjects provided self-ratings of disability at baseline and at follow-up. Comparisons of baseline and follow-up tremor scores and disability ratings were made using the Mann-Whitney U and Wilcoxon rank sum W test; correlation analyses were performed using Spearman rank order correlation test. There were significant and essentially equal improvements in tremor scores of test, kinetic, distal postural, and proximal postural tremor at follow-up. Only one subject had no improvement in tremor. Tremor improved significantly and to the same extent in ET and PD subjects in each position except "at rest," which was most improved in PD (p = 0.0003). ET and PD subjects did not differ in the extent of disability improvement. Improved disability correlated only with improved postural tremor scores; proximal postural and distal postural (r = 0.41, p = 0.03; r = 0.47, p = 0.01). DBS is effective in alleviating tremor and disability in both ET and PD. Resting, kinetic, distal postural, and proximal postural tremor can be reduced to an equal degree. However, DBS produces the greatest improvement in disability in association with improved postural tremor in both ET and PD.

Adolescent↗
PubMed2002

Influence of the lateral ventricles and irregular skull base on brain kinematics due to sagittal plane head rotation.

Two-dimensional physical models of the human head were used to investigate how the lateral ventricles and irregular skull base influence kinematics in the medial brain during sagittal angular head dynamics. Silicone gel simulated the brain and was separatedfrom the surrounding skull vessel by paraffin that provided a slip interface between the gel and vessel. A humanlike skull base model (HSB) included a surrogate skull base mimicking the irregular geometry of the human. An HSBV model added an elliptical inclusion filled with liquid paraffin simulating the lateral ventricles to the HSB model. A simplified skull base model (SSBV) included ventricle substitute but approximated the anterior and middle cranial fossae by a flat and slightly angled surface. The models were exposed to 7600 rad/s2 peak angular acceleration with 6 ms pulse duration and 5 deg forced rotation. After 90 deg free rotation, the models were decelerated during 30 ms. Rigid body displacement, shear strain and principal strains were determined from high-speed video recorded trajectories of grid markers in the surrogate brains. Peak values of inferior brain surface displacement and strains were up to 10.9X (times) and 3.3X higher in SSBV than in HSBV. Peak strain was up to 2.7X higher in HSB than in HSBV. The results indicate that the irregular skull base protects nerves and vessels passing through the cranial floor by reducing brain displacement and that the intraventricular cerebrospinal fluid relieves strain in regions inferior and superior to the ventricles. The ventricles and irregular skull base are necessary in modeling head impact and understanding brain injury mechanisms.

Biomechanical Phenomena↗
PubMed2003

Subcortical, cerebellar, and magnetic resonance based consistent brain image registration.

A new landmark-initialized segmentation and intensity-based (LI-SI) inverse-consistent linear elastic image registration algorithm is presented. This method uses manually identified landmarks, segmented volumetric (anatomical) structures, and normalized image signal intensity information to coregister datasets. The features used for image registration and evaluation include 35 cortical, cerebellar, and commissure landmarks manually identified by experts, subcortical and cerebellar regions defined semi-automatically by an artificial neural network and manually trimmed for validity by experts, and tissue classified images that were generated using a discriminant analysis of three magnetic resonance image sets representing T1, T2, and PD modalities. Four groups of results were computed for coregistering 16 datasets with the following registration techniques: rigid registration, extended Talairach registration, intensity-only inverse-consistent linear elastic registration, and the new LI-SI registration. Results are presented showing that relative overlap measurements increased as the dimensionality of the registration algorithm and amount of anatomical information increased. The average relative overlap improved from 0.53 for the rigid registration to 0.55 for the Talairach registration to 0.74 for the intensity-only and to 0.85 for the LI-SI algorithm. We showed a statistically significant improvement for all but one structure using the intensity-only algorithm compared to the Talairach registration. Furthermore, statistically significant improvements for all structures were achieved using the LI-SI algorithm compared to the intensity-only algorithm.

Adult↗
PubMed2003

A method for attenuation and scatter correction of brain SPECT based on computed tomography images.

A method for attenuation and scatter correction of brain single photon emission computed tomography (SPECT) is described where computed tomography (CT) images of the brain are used for the calculation of attenuation maps. The method is evaluated for the substance 99mTc hexamethylpropylene amine oxime. A transmission dependent scatter correction is utilized and is based on ray sums calculated through the attenuation map. A method based on external markers is used to align the SPECT and CT image volumes. The markers need only to be present during the SPECT acquisition since the corresponding landmarks can be found without markers on the CT images. The mismatching has been investigated for five patients who have undergone both a CT examination and a SPECT examination with markers. Twelve individuals from the staff have pointed out the landmarks on the CT images, with an average standard deviation of 3.4 mm. Reconstructions with an attenuation map shifted the corresponding 95% confidence interval have been performed to obtain an estimation of the quantitative uncertainty caused by the mismatching, and quantitative errors of up to 6.3% have been measured. At present the method is probably most useful when groups of patients are studied.

Algorithms↗
PubMed2004

Management of posttraumatic brain swelling based on clinical typing.

OBJECTIVE: To investigate the clinical typing and prophylactico-therapeutic measures for acute posttraumatic brain swelling (BS). METHODS: A retrospective study was performed in 66 cases of acute posttraumatic BS. There were 3 groups based on computered tomography (CT) scanning: 23 cases of hemisphere brain swelling (HBS) with middle line shift for less than 5 mm within 24 hours (Group A), 20 with middle line shift for more than 5 mm (Group B), and 23 with bilateral diffuse brain swelling (Group C). RESULTS: (1) The mortality rates of the operative and nonoperative management in Group A, Group B, and Group C were 20.0%, 31.6%, and 75.0% versus 44.4%, 0, and 85.7%, respectively (P>0.05); while the rates in subgroups with different middle line shift (more than 5 mm and less or equal 5 mm) were 29.2% and 75.0% versus 75.0% and 44.4%, respectively (0.05>P>0.01). (2) The good recovery rate and mortality in Group A were 47.8% and 39.1%, respectively and in Group C, 8.7% and 78.3%, respectively. There was a very significant difference between Group A and Group C (P<0.01). (3) The total survival rate of the selective comprehensive therapy was 53.1%. CONCLUSIONS: (1) Acute posttraumatic BS needs to be diagnosed correctly and promptly with CT scanning within 4 hours. (2) For patients with midline shift for more than 5 mm, especially with thin-layered subdural hematoma, surgical intervention is essential to reduce the fatality of acute posttraumatic BS.

Adult↗
PubMed1998

Interrelationships of brain, cranial base and mandible.

The purpose of this study is to evaluate the neural and masticatory growth factors that contribute to the development of the cranial base. Cephalometric and submentovertex (SMV) radiographs of 66 adult human skulls, of Caucasian (India) origin and unknown gender were used in this study. Results indicate that the cranial base, posterior to the foramen caecum, develops in response to brain growth. The part anterior to the foramen caecum develops in response to the mandible. Our findings indicate that: 1. the glabella instead of the nasion should be considered as the most anterior point of the cranial base. Mandibular dimensions (the height and the length) have a better correlation with CG than CN. 2. Instead of a single parameter, sella-nasion (SN), two parameters, the foramen caecum-glabella (CG) and the foramen caecum-sella (CS) should be considered. In cephalometry the more stable line CS, rather than SN, can be used for registration of successive radiographs; 3. The typical mandibular retrognathia, and/or the decrease in the posterior height (ascending ramus) of a Class II malocclusion could be explained by their positive correlation with SB (sella-basion) and the negative correlation with angle GSB.

Adult↗
PubMed2002

Novel treatments of mood disorders based on brain circuitry (ECT, MST, TMS, VNS, DBS).

Advances in understanding the functional and structural anatomy of depression outlined in this issue set the stage for attempting to manipulate implicated brain regions as potential antidepressant therapies. On the one hand, these circuit- and device-based approaches to treating depression are not new. Electroconvulsive therapy (ECT) dates back to the beginning of modern biologic psychiatry with the discovery and rapid increase of first chemical (around 1910), and then later ECT. On the other hand, this area represents an important paradigm shift with treatments that are radical and different. A dizzying array of diverse technologies now allows researchers to stimulate the brain in undreamed of ways. However, the approaches described in this article are still considered experimental and are not approved for use in the United States by the Food and Drug Administration (FDA), except ECT, which predates the FDA. These device-based approaches to brain stimulation offer promise as potential acute and even longterm treatments. Additionally, the research determining whether and how these devices work to influence mood promises to help unravel the neurophysiology of mood regulation. These novel treatments are thus the translational tools to bridge from advances in brain imaging, into new treatments for depressed patients.

Brain↗
PubMedDate not supplied

Spatial registration of digital brain atlases based on fuzzy set theory.

We present a semiautomatic method based on fuzzy set theory for adjusting a computerized brain atlas to magnetic resonance images (MRIs) of the human cerebral cortex. The atlas was registered to three-dimensional MRI data sets of 10 healthy volunteers. After a global matching using the external contour of the brain, several local procedures were performed regarding selected primary furrows and cytoarchitectonic areas. The final transformation matrix was calculated with respect to these anatomical structures and to their local matrices. Evaluation revealed an increase in accuracy as expressed by a reduction of the visible mismatch with respect to the registration of cortical and subcortical brain structures.

Atlases as Topic↗
PubMed2005

An improved P300-based brain-computer interface.

A brain-computer interface (BCI) is a system for direct communication between brain and computer. The BCI developed in this work is based on a BCI described by Farwell and Donchin in 1988, which allows a subject to communicate one of 36 symbols presented on a 6 x 6 matrix. The system exploits the P300 component of event-related brain potentials (ERP) as a medium for communication. The processing methods distinguish this work from Donchin's work. In this work, independent component analysis (ICA) was used to separate the P300 source from the background noise. A matched filter was used together with averaging and threshold techniques for detecting the existence of P300s. The processing method was evaluated offline on data recorded from six healthy subjects. The method achieved a communication rate of 5.45 symbols/min with an accuracy of 92.1% compared to 4.8 symbols/min with an accuracy of 90% in Donchin's work. The online interface was tested with the same six subjects. The average communication rate achieved was 4.5 symbols/min with an accuracy of 79.5 % as apposed to the 4.8 symbols/min with an accuracy of 56 % in Donchin's work. The presented BCI achieves excellent performance compared to other existing BCIs, and allows a reasonable communication rate, while maintaining a low error rate.

Adult↗