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Thomas Trieb

Publications and source records attributed to Thomas Trieb.

14 recordsLinked to original sources
PubMed2006

Single-beat noninvasive imaging of cardiac electrophysiology of ventricular pre-excitation.

OBJECTIVES: The aim of this study was to determine whether noninvasive imaging of cardiac electrophysiology (NICE) is feasible in patients with Wolff-Parkinson-White (WPW) syndrome in the clinical setting of a catheter laboratory and to test the accuracy of the noninvasively obtained ventricular activation sequences as compared with that of standard invasive electroanatomic mapping. BACKGROUND: NICE of ventricular activation could serve as a useful tool in the treatment of cardiac arrhythmias and might help improve our understanding of arrhythmia mechanisms. METHODS: NICE works by fusing the data from high-resolution electrocardiographic mapping and a model of the patient's cardiac anatomy obtained by magnetic resonance imaging. The ventricular activation sequence was computed with a bidomain theory-based heart model to solve this inverse problem. Noninvasive imaging of cardiac electrophysiology was performed in 7 patients with WPW syndrome undergoing catheter ablation of the accessory pathway. The position error of NICE was defined as the distance between the site of earliest activation computed by NICE and the successful ablation site identified by electroanatomic mapping (CARTO; Biosense Webster, Diamond Bar, California) for normal atrioventricular (AV) conduction as well as for adenosine-induced AV block. RESULTS: The error introduced by geometric coupling of the CARTO data and the NICE model was 5 +/- 3 mm (model discretization 10 mm). All ventricular accessory pathway insertion sites were identified with an accuracy of 18.7 +/- 5.8 mm (baseline) and 18.7 +/- 6.4 mm (adenosine). CONCLUSIONS: The individual cardiac anatomy model obtained for each patient enables accurate noninvasive electrocardiographic imaging of ventricular pre-excitation in patients with WPW syndrome. Noninvasive imaging of cardiac electrophysiology might be used as a complementary noninvasive approach to localize the origin and help identify and understand the underlying mechanisms of cardiac arrhythmias.

Adult↗
PubMed2006

Neural correlates of verbal semantic memory in patients with temporal lobe epilepsy.

Functional imaging data suggest that the core network engaged in verbal semantic memory (SM) processing encompasses frontal and temporal lobe structures, with a strong left lateralization in normal right handers. The impact of long term temporal lobe epilepsy (TLE) on this network has only partly been elucidated. We studied verbal SM in 50 patients with chronic, intractable TLE (left TLE=26, right TLE=24) and 35 right handed normal controls using a verbal fMRI semantic decision paradigm. All patients had language lateralized to the left hemisphere, as verified by the intracarotid amobarbital procedure. Within and between group analyses showed remarkable, group-specific activation profiles. The control group activated frontal and temporal areas bilaterally, with a strong left predominance. Left TLE patients showed a shift of activations of left frontal and medial temporal areas to homologous regions in the right hemisphere. Furthermore, left TLE subjects utilized subcortical structures such as the thalamus and putamen to accomplish the verbal SM task. Contrastively, the activation pattern of right TLE patients resembled that of normal controls, but exhibited "hypofrontality" with a shift from frontal to posterior regions in the temporal, parietal and occipital lobe. Our results show that chronic epileptic activity originating from temporal seizure foci is associated with an alteration of neural circuits which support semantic language processing and that side of seizure focus has a specific impact on the resulting activation network. These findings presumably result from morphological changes and from functional reorganization which are both inherent to chronic TLE.

Adult↗
PubMed2006

Isolated numerical skills in posterior cortical atrophy--an fMRI study.

Posterior cortical atrophy (PCA) is characterized by bilateral parieto-occipito-temporal atrophy and hypometabolism. Neuropsychological impairments include complex visual disturbances, alexia, agraphia, finger agnosia, right-left disorientation and dyscalculia. A recent case study reported severe numerical deficits with some selectively preserved numerical skills in a patient affected by PCA [Delazer, M., Karner, E., Zamarian, L., Donnemiller, E., & Benke, T. (2006). Number processing in posterior cortical atrophy--a neuropsycholgical case study. Neuropsychologia]. In a functional magnetic resonance imaging (fMRI) study brain activation patterns related to these selectively preserved numerical skills were analyzed. Recitation of multiplication tables and counting forward were contrasted to word recitation in a block design. Contrasts between experimental conditions and control condition yielded significant activation of inferior and medial temporal structures. Since numerical processing is generally associated with parietal activation, it was hypothesized that preserved brain structures would compensate for the functional deficits.

Acoustic Stimulation↗
PubMed2006

Language lateralization in temporal lobe epilepsy: a comparison between fMRI and the Wada Test.

PURPOSE: Recent studies have claimed that language functional magnetic resonance imaging (fMRI) can identify language lateralization in patients with temporal lobe epilepsy (TLE) and that fMRI-based findings are highly concordant with the conventional assessment procedure of speech dominance, the intracarotid amobarbital test (IAT). METHODS: To establish the power of language fMRI to detect language lateralization during presurgical assessment, we compared the findings of a semantic decision paradigm with the results of a standard IAT in 68 patients with chronic intractable right and left temporal lobe epilepsy (rTLE, n=28; lTLE, n=40) who consecutively underwent a presurgical evaluation program. The patient group also included 14 (20.6%) subjects with atypical (bilateral or right hemisphere) speech. Four raters used a visual analysis procedure to determine the laterality of speech-related activation individually for each patient. RESULTS: Overall congruence between fMRI-based laterality and the laterality quotient of the IAT was 89.3% in rTLE and 72.5% in lTLE patients. Concordance was best in rTLE patients with left speech. In lTLE patients, language fMRI identified atypical, right hemisphere speech dominance in every case, but missed left hemisphere speech dominance in 17.2%. Frontal activations had higher concordance with the IAT than did activations in temporoparietal or combined regions of interest (ROIs). Because of methodologic problems, recognition of bilateral speech was difficult. CONCLUSIONS: These data provide evidence that language fMRI as used in the present study has limited correlation with the IAT, especially in patients with lTLE and with mixed speech dominance. Further refinements regarding the paradigms and analysis procedures will be needed to improve the contribution of language fMRI for presurgical assessment.

Adolescent↗
PubMed2006

Predictors of carpal tunnel syndrome: accuracy of gray-scale and color Doppler sonography.

OBJECTIVE: The purpose of this study was to retrospectively assess the accuracy of gray-scale and color Doppler sonography in the diagnosis of carpal tunnel syndrome. MATERIALS AND METHODS: A total of 206 wrists in 151 patients with a clinical suspicion of carpal tunnel syndrome were examined with high-resolution sonography using a 7-15-MHz linear array transducer. The presence of median nerve swelling, edema, and flattening and increased bowing of the flexor retinaculum was evaluated with gray-scale sonography, and the presence of nerve hypervascularization was evaluated with color Doppler sonography. Sensitivity and specificity were calculated for each sonographic feature in comparison with nerve conduction studies as the standard of reference. Multivariate logistic regression analysis was used to determine variables predictive of carpal tunnel syndrome. RESULTS: Carpal tunnel syndrome was confirmed in 172 wrists at nerve conduction studies. A median nerve cross-sectional area of at least 0.11 cm2 was calculated as a definition of median nerve swelling. In comparison with nerve conduction studies, nerve swelling showed the highest accuracy (91%) among gray-scale sonography criteria, and the presence of intraneural hypervascularization showed the highest accuracy (95%) among all sonography criteria. Logistic regression analysis showed that nerve hypervascularization was the only variable that independently predicted median nerve entrapment (odds ratio, 16.4; 95% confidence interval, 8.7-31.1; p <0.001). CONCLUSION: Color Doppler sonography is more accurate than gray-scale sonography for characterizing median nerve involvement in patients with suspected carpal tunnel syndrome.

Adolescent↗
PubMed2005

Reduced aortic elastic properties in a child with Takayasu arteritis: case report and literature review.

UNLABELLED: Takayasu arteritis (TA) is a chronic inflammatory vasculitis of the aorta and its major branches with a very low incidence in Europe and North America. Our objective was to determine the elastic properties of the affected ascending and descending aortic walls non-invasively in a 14-year-old Iraqi girl with a 3-year history of fever, fatigue, malaise and diffuse pain. Ultrasound and magnetic resonance angiography showed marked thickening of the aortic wall, dilatation of the aortic arch, and decreased luminal diameters of the abdominal aorta and both subclavian arteries, consistent with TA. Ascending and descending aortic elastic properties such as distensibility and stiffness index were markedly reduced compared to a group of healthy controls (n=39): ascending aortic distensibility was 20 kPa(-1) x 10(-3) versus 63+/-23 kPa(-1) x 10(-3) in controls, and the ascending aortic stiffness index 9.6 versus 3.5+/-1.3 in controls. Although the patient's general condition improved rapidly on oral prednisolone and azathioprine and inflammatory parameters normalised within 3 weeks, the aortic elastic parameters did not change during the first 2 weeks of anti-inflammatory treatment. Unfortunately, no further follow-up was possible. CONCLUSION: In patients with Takayasu arteritis, non-invasive quantification of reduced aortic elastic properties can help to assess aortic involvement, and possibly to follow disease activity and vascular response to therapy.

Abdominal Pain↗
PubMed2005

Voxel-based morphometry in narcolepsy.

BACKGROUND AND PURPOSE: Voxel-based morphometry (VBM) is a magnetic resonance imaging (MRI)-based indirect volumetry, which allows the investigation of the entire brain without restriction of predefined regions-of-interest. Recent studies using this technique reported controversial results in patients with narcolepsy. PATIENTS AND METHODS: In this study, 12 patients with narcolepsy according to the criteria of the International Classification of Sleep Disorders were compared to 12 age-matched controls with normal MR images using VBM. Sex and global differences in voxel intensities were used as confounding covariates. RESULTS: Significant gray matter loss was found in the right prefrontal and frontomesial cortex of patients with narcolepsy. White matter comparison revealed no significant changes in patients or controls. The comparison of cerebrospinal fluid partition detected an enlargement of subarachnoidal space of controls close to the prefrontal cortex. CONCLUSIONS: The volume reduction of gray matter in narcoleptic patients could indicate a disease-related atrophy pattern. However, the results of VBM studies in narcolepsy are contradictory. A possible systematic bias due to inhomogeneous patient groups, stimulant medication history or pre-statistical image processing must be considered. We suggest that studies with drug-naive patients and/or region-of-interest-based volumetric studies should be performed in areas defined by VBM.

Adult↗
PubMed2005

Hippocampal formation involvement in a language-activation task in patients with mesial temporal lobe epilepsy.

PURPOSE: The study aims to explore the contribution of the hippocampal formation to the retained language-comprehension network in patients with unilateral mesial temporal lobe epilepsy (TLE). METHODS: We performed a functional magnetic resonance (MRI) study based on a language comprehension paradigm in 45 right-handed patients with unilateral mesial TLE and 35 healthy control subjects. Activations in the hippocampal formations in both hemispheres were analyzed for each subject as well as for groups of left TLE, right TLE, and controls. RESULTS: In sum, 82% of TLE patients displayed hippocampal activations. A significant difference in hippocampal activation between left and right TLE was found: Right TLE patients showed increased activity in the left hippocampal formation compared with left TLE patients. In contrast, patients with left TLE did not show increased activity in the right hippocampal formation compared with right TLE patients. In comparison with a healthy control group, right TLE patients activated the left hippocampal formation to a greater extent, whereas patients with left TLE did not activate the right hippocampal formation to a greater degree. These findings point to an increased involvement of the left hippocampal formation during a language-comprehension task in right TLE patients. In contrast, left TLE in right-handed patients seems not associated with an enhanced involvement of the right hippocampal formation in retained language comprehension. CONCLUSIONS: These findings suggest that effective language comprehension in right-handed subjects with TLE depends on the involvement of the left hippocampal formation and underline the risks of postoperative language decline in patients with left TLE.

Adolescent↗
PubMed2004

Basal forebrain atrophy is a distinctive pattern in dementia with Lewy bodies.

We determined brain atrophy patterns in dementia with Lewy bodies and Alzheimer's disease using voxel-based morphometry, an indirect volumetry. Ten patients with dementia with Lewy bodies, 10 patients with Alzheimer's disease and 10 controls were included. All groups were matched for age; sex and global differences in voxel intensities were included as confounding covariates. We observed basal forebrain atrophy discriminating dementia with Lewy bodies from Alzheimer's disease. Compared to controls, atrophy of lateral prefrontal cortex and left premotor cortex was seen in dementia with Lewy bodies whereas atrophy of the medial temporal cortex, posterior parietal cortex, thalamus and temporo-occipital areas was observed in Alzheimer's disease. Atrophy of insular cortex was found in both patient groups.

Aged↗
PubMed2003

Multimodality cranial image fusion using external markers applied via a vacuum mouthpiece and a case report.

PURPOSE: To present a simple and precise method of combining functional information of cranial SPECT and PET images with CT and MRI, in any combination. MATERIAL AND METHODS: Imaging is performed with a hockey mask-like reference frame with image modality-specific markers in precisely defined positions. This frame is reproducibly connected to the VBH vacuum mouthpiece, granting objectively identical repositioning of the frame with respect to the cranium. Using these markers, the desired 3-D imaging modalities can then be manually or automatically registered. This information can be used for diagnosis, treatment planning, and evaluation of follow-up, while the same vacuum mouthpiece allows precisely reproducible stereotactic head fixation during radiotherapy. RESULTS: 244 CT and MR data sets of 49 patients were registered to a root square mean error (RSME) of 0.9 mm (mean). 64 SPECT-CT fusions on 18 of these patients gave an RMSE of 1.4 mm, and 40 PET-CT data sets of eight patients were registered to 1.3 mm. An example of the method is given by means of a case report of a 52-year-old patient with bilateral optic nerve meningioma. CONCLUSION: This technique is a simple, objective and accurate registration tool to combine diagnosis, treatment planning, treatment, and follow-up, all via an individualized vacuum mouthpiece. Especially for low-resolution PET and even more so for some very diffuse SPECT data sets, activity can now be accurately correlated to anatomic structures.

Equipment Design↗
PubMed2003

Medial temporal lobe activation during semantic language processing: fMRI findings in healthy left- and right-handers.

Medial temporal lobe (MTL) areas are well known to serve episodic memory functions; their contribution to semantic memory has been occasionally noticed but not studied in detail. In the present fMRI study, 35 right-handed and 35 left-handed healthy subjects performed a semantic decision paradigm during which subjects heard spoken concrete nouns designating objects and had to decide on whether these objects were available in the supermarket and cost lest then a certain amount of money. The control paradigm consisted of sequences of low and high tones where subjects had to decide whether a sequence contained two high tones. The resulting contrast activation of semantic decision versus tone decision involved neocortical temporal, parietal, and prefrontal areas. Additional significant, bilateral activations in the MTL, the hippocampal formation, and adjacent areas were found. The exact incidence and location of activation was studied in a single-subject analysis for all 70 subjects. At the chosen threshold of P<0.001, 94% of subjects showed activations in the MTL and inferior temporal lobe (ITL). Activations were found along the longitudinal axis of the MTL, including the hippocampal formation and the parahippocampal gyrus. In the ITL, parts of the fusiform and lingual gyri were activated. Activations were similar in right- and left-handers. We conclude from this study that the MTL and parts of the ITL can be added to the areas activated by semantic verbal memory processing.

Acoustic Stimulation↗
PubMedDate not supplied

Congenital proximal radioulnar synostosis associated with bilateral hypoplasia of the scaphoid bone, bilateral os lunatotriquetrum, and anomalies of the carpometacarpal complex.

We describe a unique case of bilateral os lunatotriquetrum associated with bilateral hypoplasia of the scaphoid bone. On both sides, the medial carpi were in a single row. The capitate bone occupied the lunate position, whereas the lunatotriquetral bone was displaced ulnarly and tilted. The capitate thus articulated with the radius and metacarpal bones, consistent with carpal collapse. In addition, there was congenital proximal radioulnar synostosis on the left side.

Abnormalities, Multiple↗