Publications (7)31.42 Total impact
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Article: Variability of Clinical Functional MR Imaging Results: A Multicenter Study.
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ABSTRACT: Purpose:To investigate intersite variability of clinical functional magnetic resonance (MR) imaging, including influence of task standardization on variability and use of various parameters to inform the clinician whether the reliability of a given functional localization is high or low.Materials and Methods:Local ethics committees approved the study; all participants gave written informed consent. Eight women and seven men (mean age, 40 years) were prospectively investigated at three experienced functional MR sites with 1.5- (two sites) or 3-T (one site) MR. Nonstandardized motor and highly standardized somatosensory versions of a frequently requested clinical task (localization of the primary sensorimotor cortex) were used. Perirolandic functional MR variability was assessed (peak activation variability, center of mass [COM] variability, intraclass correlation values, overlap ratio [OR], activation size ratio). Data quality measures for functional MR images included percentage signal change (PSC), contrast-to-noise ratio (CNR), and head motion parameters. Data were analyzed with analysis of variance and a correlation analysis.Results:Localization of perirolandic functional MR activity differed by 8 mm (peak activity) and 6 mm (COM activity) among sites. Peak activation varied up to 16.5 mm (COM range, 0.4-16.5 mm) and 45.5 mm (peak activity range, 1.8-45.5 mm). Signal strength (PSC, CNR) was significantly lower for the somatosensory task (mean PSC, 1.0% ± 0.5 [standard deviation]; mean CNR, 1.2 ± 0.4) than for the motor task (mean PSC, 2.4% ± 0.8; mean CNR, 2.9 ± 0.9) (P < .001, both). Intersite variability was larger with low signal strength (negative correlations between signal strength and peak activation variability) even if the task was highly standardized (mean OR, 22.0% ± 18.9 [somatosensory task] and 50.1% ± 18.8 [motor task]).Conclusion:Clinical practice and clinical functional MR biomarker studies should consider that the center of task-specific brain activation may vary up to 16.5 mm, with the investigating site, and should maximize functional MR signal strength and evaluate reliability of local results with PSC and CNR.© RSNA, 2013.Radiology 03/2013; · 5.73 Impact Factor -
Dataset: Beisteiner-Cortical-Neuroplasticity-Brachial-Plexus-Lesion ArchNeurol-11-2011
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Article: New type of cortical neuroplasticity after nerve repair in brachial plexus lesions.
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ABSTRACT: In brachial plexus avulsion, a recent technique connects the ending of the disrupted musculocutaneous nerve to the side of the intact phrenic nerve to regain elbow flexion. This requires the phrenic nerve to perform a new double function: independent control of breathing and elbow flexion. Neuroplastic changes associated with acquisition of double nerve functions have not yet been investigated. To evaluate neuroplastic changes associated with acquisition of double nerve functions in a monofunctional nerve (phrenic nerve). Clinical and functional magnetic resonance imaging investigations during arm movements, forced inspiration, and motor control tasks. Investigations at the Medical University of Vienna, Vienna, Austria. Three healthy control subjects, 2 patients with phrenic nerve end-to-side coaptation, and 1 control patient with C7 end-to-end coaptation (same clinical presentation but phrenic nerve unchanged). Clinical documentation showed that both patients with phrenic nerve end-to-side coaptation were able to control the diaphragm and the biceps independently via the same phrenic nerve. In contrast to all controls, both patients with phrenic nerve end-to-side coaptation activated the cortical diaphragm areas with flexion of the diseased arm. Our functional magnetic resonance imaging data indicate that the patient's cortical diaphragm areas reorganize in such a way that independent control of breathing and elbow flexion is possible with the same neuronal population.Archives of neurology 11/2011; 68(11):1467-70. · 6.31 Impact Factor -
Article: An fMRI marker for peripheral nerve regeneration.
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ABSTRACT: Final outcome after surgical repair of peripheral nerve transections varies. Here, we present the first longitudinal functional magnetic resonance imaging (fMRI) observation of cortical somatosensory reorganization patterns after surgery. A 43-year-old man presented with isolated complete transection of the right median nerve and underwent immediate epineural end-to-end coaptation. Applying standardized vibrotactile median nerve stimulation, 3 T brain activation maps were evaluated at 1, 7, 15 weeks and 1 year after surgery. Initially, the affected hemisphere showed no primary activation but increased frontoparietal activity. After 1 year, primary activation had recovered, and frontoparietal activity was decreased relative to the nonaffected hemisphere. Based on these longitudinal fMRI patterns, we propose a new marker for restoration of somatosensory function, which may not be provided by electrophysiological methods.Neurorehabilitation and neural repair 03/2011; 25(6):577-9. · 4.49 Impact Factor -
Article: How much are clinical fMRI reports influenced by standard postprocessing methods? An investigation of normalization and region of interest effects in the medial temporal lobe.
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ABSTRACT: Recent evidence has indicated that standard postprocessing methods such as template-based region of interest (ROI) definition and normalization of individual brains to a standard template may influence final outcome of functional magnetic resonance imaging investigations. Here, we provide the first comprehensive investigation into whether ROI definition and normalization may also change the clinical interpretation of patient data. A series of medial temporal lobe epilepsy patients were investigated with a clinical memory paradigm and individually delineated as well as template-based ROIs. Different metrics for activation quantification were applied. Results show that the application of template-based ROIs can significantly change the clinical interpretation of individual patient data. This relates to sensitivity for brain activation and hemispheric dominance. We conclude that individual ROIs should be defined on nontransformed functional data and that use of more than one metric for activation quantification is beneficial.Human Brain Mapping 03/2010; 31(12):1951-66. · 5.88 Impact Factor -
Article: A population-specific symmetric phase model to automatically analyze susceptibility-weighted imaging (SWI) phase shifts and phase symmetry in the human brain.
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ABSTRACT: To create a population-specific symmetric phase model and to evaluate the susceptibility-weighted imaging (SWI) phase in terms of phase shift using different segmentation methods (manual and automatic) and phase shift symmetry, which is expected as a marker for lateralized Parkinson's disease (PD) symptoms. SWI and T(1)-weighted data from 25 PD patients and five healthy controls were acquired on a 3T MRI system. A population-specific, symmetric phase model was developed. Regions of interest (ROIs) were defined manually on the phase model, manually on each individual data set, and automatically using model-based segmentation (MBS). Manually- and MBS-defined ROIs were compared using kappa values, and left-right phase symmetry was evaluated using correlation analysis. Independent of the analysis method, a phase increase from the anterior to the posterior putamen, and the average phase value relationship substantia nigra > globus pallidus > red nucleus was found. Phase symmetry analysis shows a difference between lateralized and symmetric PD. The symmetric phase model helps to analyze phase data with similar accuracy, but a greatly reduced tracing effort compared to individual tracing and also allows evaluating left-right phase symmetries.Journal of Magnetic Resonance Imaging 12/2009; 31(1):215-20. · 2.70 Impact Factor -
Article: Evaluation of functional cortex for the diseased hand in a patient after hemispherectomy.
Archives of neurology 01/2009; 65(12):1664-5. · 6.31 Impact Factor
Top co-authors
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Institutions
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2009–2011
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Medical University of Vienna
- Universitätsklinik für Neurologie
Vienna, Vienna, Austria
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