Search results for "image processing"
showing 10 items of 3285 documents
Word order and Broca’s region: Evidence for a supra-syntactic perspective
2008
It has often been suggested that the role of Broca's region in sentence comprehension can be explained with reference to general cognitive mechanisms (e.g. working memory, cognitive control). However, the (language-related) basis for such proposals is often restricted to findings on English. Here, we argue that an extension of the database to other languages can shed new light on the types of mechanisms that an adequate account of Broca's region should be equipped to deal with. This becomes most readily apparent in the domain of word order variations, which we examined in German verb-final sentences using event-related fMRI. Our results showed that activation in the pars opercularis--a core…
Multislice multiecho T2* cardiovascular magnetic resonance for detection of the heterogeneous distribution of myocardial iron overload.
2006
Purpose To assess the tissue iron concentration of the left ventricle (LV) using a multislice, multiecho T2* MR technique and a segmental analysis. Materials and Methods T2* multiecho MRI was performed in 53 thalassemia major patients. Three short-axis views of the LV were obtained and analyzed with custom-written software. The myocardium was automatically segmented into 12 segments. The T2* value on each segment as well as the global T2* value were calculated. Cine dynamic images were also obtained to evaluate biventricular function parameters by quantitative analysis. Results For the T2* global value, the coefficient of variation (CoV) for intra-/interobserver and interstudy reproducibili…
Muscle kinematics during isometric contraction: Development of phase contrast and spin tag techniques to study healthy and atrophied muscles
2004
Purpose To develop and compare phase-contrast (PC) and spin-tag (ST) MR imaging techniques for accurate quantification of velocity and displacement distribution in the muscle tendon complex of the lower leg during isometric contractions under in vivo conditions, in healthy subjects and subjects with atrophy. Materials and Methods Techniques were developed to acquire PC and ST dynamic images, gated to the force exerted by a subject during isometric contraction. Algorithms were optimized for correction of phase shading errors. Flow velocity quantification was validated in phantoms and ex vivo rabbit muscles. Trajectories of pixels calculated from PC images were compared with those in ST image…
Usefulness of quantitative peritumoural perfusion and proton spectroscopic magnetic resonance imaging evaluation in differentiating brain gliomas fro…
2016
Objectives The purpose of our study was to evaluate whether peritumoural perfusion weighted and proton spectroscopic magnetic resonance imaging can be used in differentiating between primary gliomas and solitary metastases. Methods Ten low-grade gliomas, eight high-grade gliomas and 10 metastases were prospectively evaluated with magnetic resonance imaging, dynamic susceptibility contrast enhanced perfusion imaging and single-voxel proton magnetic resonance spectroscopy before surgical resection or stereotactic biopsy. Maximal relative cerebral blood volume values were calculated drawing three regions of interest of 2 cm2 in the non-enhancing peritumoural areas. Maximal relative cerebral bl…
In-Vivo Estimation and Repeatability of Force-Length Relationship and Stiffness of the Human Achilles Tendon using Phase Contrast MRI
2008
Purpose To devise a method using velocity encoded phase contrast MRI and MR-compatible dynamometry, for in vivo estimation of elastic properties of the human Achilles tendon and to assess within-session and day-to-day repeatability of this technique. Materials and Methods Achilles tendon force and calcaneus-movement-adjusted displacement were measured during a submaximal isometric plantarflexion in 4 healthy subjects, four repeated trials each. The measured force-length (F-L) relationship was least-squares fitted to a cubic polynomial. Typical error was calculated for tendon displacement at multiple force levels, stiffness from the “linear region,” and transition point from the displacement…
Transthoracic three-dimensional echocardiographic volumetry of distorted left ventricles using rotational scanning
1997
The purpose of this study was to evaluate the relation of transthoracic three- and two-dimensional echocardiographic left ventricular volumetry to cineventriculographic volumetry. Twenty-five patients with distorted left ventricles were included in the study. To demonstrate the impact of acquiring data by rotational scanning, we performed three- and two-dimensional echocardiography in 36 latex ventricles with data acquisition in different areas of the ultrasound sectors. Interobserver and intraobserver variability were calculated to test for reproducibility. The three-dimensional imaging system consisted of a rotation motor device, a transthoracic 2.5 MHz transducer, a conventional ultrasou…
Functional connectivity analysis using whole brain and regional network metrics in MS patients
2016
In the present study we investigated brain network connectivity differences between patients with relapsing-remitting multiple sclerosis (RRMS) and healthy controls (HC) as derived from functional resonance magnetic imaging (fMRI) using graph theory. Resting state fMRI data of 18 RRMS patients (12 female, mean age ± SD: 42 ± 12.06 years) and 25 HC (8 female, 29.2 ± 5.38 years) were analyzed. In order to obtain information of differences in entire brain network, we focused on both, local and global network connectivity parameters. And the regional connectivity differences were assessed using regional network parameters. RRMS patients presented a significant increase of modularity in comparis…
Changes in anatomic position of root canal orifices in pluriradicular teeth following re-location during endodontic treatment
2017
Abstract Direct access to the root canals in posterior teeth for endodontic treatment is most frequently facilitated by the straightening of the coronal parts of the root canals, having as a consequence the relocation of the canal orifices on the map of the floor of the pulp chamber ( Christie and Thompson, 1994 ). This procedure intentionally moves the coronal aspect of a canal away from the center of the chamber, while simultaneously removing internal dentin from the pulp chamber walls. The aim of this study was to evaluate the displacement resulting from the relocation of root canal orifices during the initial phase of rotary root canal treatment in molars using the dental operating micr…
Memory detection using fMRI - does the encoding context matter?
2015
Recent research revealed that the presentation of crime related details during the Concealed Information Test (CIT) reliably activates a network of bilateral inferior frontal, right medial frontal and right temporal-parietal brain regions. However, the ecological validity of these findings as well as the influence of the encoding context are still unclear. To tackle these questions, three different groups of subjects participated in the current study. Two groups of guilty subjects encoded critical details either only by planning (guilty intention group) or by really enacting (guilty action group) a complex, realistic mock crime. In addition, a group of informed innocent subjects encoded hal…
Neural correlates of interference inhibition, action withholding and action cancelation in adult ADHD
2011
Attention-Deficit/Hyperactivity Disorder (ADHD) is marked by inhibitory and attentional deficits which can persist into adulthood. Those deficits have been associated with dysfunctional fronto-striatal and fronto-parietal circuits. The present study sought to delineate neural correlates of component specific inhibitory deficits in adult ADHD using functional magnetic resonance imaging (fMRI). 20 adult ADHD patients and 24 matched healthy controls were included. Brain activation was assessed during three stages of behavioral inhibition, i.e. interference inhibition (Simon task), action withholding (Go/no-go task) and action cancelation (Stop-signal task). Behaviorally, ADHD patients were aff…