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Time-variant Analysis of Fast-fMRI and Dynamic Contrast Agent MRI Sequences as Examples of 4-dimensional Image Analysis. Methods Inf Med 2018. [DOI: 10.1055/s-0038-1634129] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Summary
Objectives:
Image sequences with time-varying information content need appropriate analysis strategies. The exploration of directed information transfer (interactions) between neuronal assemblies is one of the most important aims of current functional MRI (fMRI) analysis. Additionally, we examined perfusion maps in dynamic contrast agent MRI sequences of stroke patients. In this investigation, the focus centers on distinguishing between brain areas with normal and reduced perfusion on the basis of the dynamics of contrast agent inflow and washout.
Methods:
Fast fMRI sequences were analyzed with time-variant Granger causality (tvGC). The tvGC is based on a time-variant autoregressive model and is used for the quantification of the directed information transfer between activated brain areas. Generalized Dynamic Neural Networks (GDNN) with time-variant weights were applied on dynamic contrast agent MRI sequences as a nonlinear operator in order to enhance differences in the signal courses of pixels of normal and injured tissues.
Results:
A simple motor task (self-paced finger tapping) is used in an fMRI design to investigate directed interactions between defined brain areas. A significant information transfer can be determined for the direction primary motor cortex to supplementary motor area during a short time period of about five seconds after stimulus. The analysis of dynamic contrast agent MRI sequences demonstrates that the trained GDNN enables a reliable tissue classification. Three classes are of interest: normal tissue, tissue at risk for death, and dead tissue.
Conclusions:
The time-variant multivariate analysis of directed information transfer derived from fMRI sequences and the computation of perfusion maps by GDNN demonstrate that dynamic analysis methods are essential tools for 4D image analysis.
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Wallersche Degeneration in der Pyramidenbahn nach paramedianem Ponsinfarkt: eine prospektive Verlaufsstudie. AKTUELLE NEUROLOGIE 2009. [DOI: 10.1055/s-0029-1238508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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3
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Hippocampal brain atrophy after carbon monoxide intoxication. Clin Neurophysiol 2007. [DOI: 10.1016/j.clinph.2006.11.220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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4
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Aneurysm of the extracranial carotid artery with spontaneous echo contrast revealed by duplex sonography. ULTRASCHALL IN DER MEDIZIN (STUTTGART, GERMANY : 1980) 2007; 28:216-8. [PMID: 17366376 DOI: 10.1055/s-2007-962892] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
A 56-year old male patient without cerebrovascular disease or risk factors presented with a painless, pulsatile right-sided cervical swelling. Ultrasonography showed a large aneurysm of the right common and internal carotid artery with homogeneous thickening of the vessel wall as well as a parietal thrombus and a dilation of the left common and internal carotid artery with markedly reduced blood flow velocities. In the enlarged lumen of the right internal carotid artery spontaneous echo contrast was apparent with slow, ineffective but orthograde blood flow motions. Ensuing diagnostic procedures revealed multiple aneurysms involving the aorta and its branches. Despite surgical removal of the aneurysm and glucocorticoid therapy, the patient died from a ruptured aneurysm of a coronary artery a few weeks later. Post-mortem examination showed panarteritis consistent with Takayasu's disease. Spontaneous echo contrast is a frequent echocardiographic finding in patients with atrial fibrillation and mitral stenosis, indicating decreased blood flow. This is associated with an increased risk of embolism. In our patient, spontaneous echo contrast indicated severely disturbed haemodynamics due to a large aneurysm of the carotid artery. In the rare case of multiple aneurysms, differential diagnosis should include dissections, infections, and connective tissue diseases. Takayasu's arteritis, however, should also be considered, which usually presents with stenoses, but may be associated with multiple aneurysms of the aorta or its branches. If the diagnostic criteria are present, immunosuppressive treatment should be initiated.
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Abstract
A 24-year-old female with a history of epileptic seizures was admitted after prolonged cardiac resuscitation. The clinical course together with additional examinations led to the diagnosis of severe hypoxic cerebral damage, with poor prognosis for neurological outcome. In her initial ECG, as in the ECGs of several family members, QT prolongation was diagnosed. Meticulous history taking and ensuing genetic analysis led to the diagnosis of familial long QT syndrome (LQTS) with a mutation in the LQT-2 gene (HERG). In retrospect, the previous seizure episodes have to be considered cardiac syncopes. Two family members had previously died suddenly, and ECG and genetic analysis revealed that a total of eight family members were affected. These relatives were prophylactically treated with beta blockers or supplied with automated implantable cardioverter defibrillating devices. The literature concerning LQTS, diagnosis and prognosis of cerebral hypoxic damage, and differentiation between seizures and cardiac syncopes is discussed.
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Hippocampal brain atrophy after carbon monoxide intoxication. KLIN NEUROPHYSIOL 2006. [DOI: 10.1055/s-2006-939282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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7
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Zeitverlauf von T2, ADC, DWI und fraktionierter Anisotropie in akuten lakunären Hirnstamminfarkten. AKTUELLE NEUROLOGIE 2006. [DOI: 10.1055/s-2006-953460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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8
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Monitoring und Betriebssicherung des RIS/PACS am Universitätsklinikum Jena. ROFO-FORTSCHR RONTG 2006. [DOI: 10.1055/s-2006-941104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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9
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Time-variant analysis of fast-fMRI and dynamic contrast agent MRI sequences as examples of 4-dimensional image analysis. Methods Inf Med 2006; 45:643-50. [PMID: 17149506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
OBJECTIVES Image sequences with time-varying information content need appropriate analysis strategies. The exploration of directed information transfer (interactions) between neuronal assemblies is one of the most important aims of current functional MRI (fMRI) analysis. Additionally, we examined perfusion maps in dynamic contrast agent MRI sequences of stroke patients. In this investigation, the focus centers on distinguishing between brain areas with normal and reduced perfusion on the basis of the dynamics of contrast agent inflow and washout. METHODS Fast fMRI sequences were analyzed with time-variant Granger causality (tvGC). The tvGC is based on a time-variant autoregressive model and is used for the quantification of the directed information transfer between activated brain areas. Generalized Dynamic Neural Networks (GDNN) with time-variant weights were applied on dynamic contrast agent MRI sequences as a nonlinear operator in order to enhance differences in the signal courses of pixels of normal and injured tissues. RESULTS A simple motor task (self-paced finger tapping) is used in an fMRI design to investigate directed interactions between defined brain areas. A significant information transfer can be determined for the direction primary motor cortex to supplementary motor area during a short time period of about five seconds after stimulus. The analysis of dynamic contrast agent MRI sequences demonstrates that the trained GDNN enables a reliable tissue classification. Three classes are of interest: normal tissue, tissue at risk for death, and dead tissue. CONCLUSIONS The time-variant multivariate analysis of directed information transfer derived from fMRI sequences and the computation of perfusion maps by GDNN demonstrate that dynamic analysis methods are essential tools for 4D image analysis.
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High resolution susceptibility weighted MR-imaging of brain tumors during the application of a gaseous agent. ROFO-FORTSCHR RONTG 2005; 177:1065-9. [PMID: 16021537 DOI: 10.1055/s-2005-858428] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
PURPOSE To employ a high resolution blood oxygenation level dependent (BOLD) method called susceptibility weighted imaging (SWI) together with the breathing of carbogen to investigate the response of cerebral tumors to this breathing gas and to assess tumor anatomy at high resolution. METHODS Five patients with cerebral tumors (four glioblastoma multiforme, one astrocytoma [WHO grade II]) were studied using a susceptibility weighted 3D gradient echo, first order velocity compensated sequence (TE = 45 ms, TR = 67 ms, alpha = 25 degrees , FOV = 256 x 192 x 64 mm(3), typical matrix = 512 x 192 x 64), on a 1.5 T MR scanner while they were breathing air and carbogen. Signal changes between the two breathing conditions were investigated. RESULTS The glioblastomas showed strong but heterogeneous signal changes between carbogen and air breathing, with changes between + 22.4 +/- 4.9 % at the perimeter of the tumors and - 5.0 +/- 0.4 % in peritumoral areas that appeared hyperintense on T (2)-weighted images. The astrocytoma displayed a signal decrease during carbogen breathing (- 4.1 +/- 0.1 % to - 6.8 +/- 0.3 % in peritumoral areas that correspond to hyperintense regions on T (2)-weighted images, and - 3.1 +/- 0.1 % in the tumor-center). CONCLUSIONS SWI provides high resolution images of cerebral anatomy and venous vascularization. Combined with hypercapnia it allows for regional assessment of tumor activity.
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[Differential diagnosis of solitary neurosarcoidosis]. DER NERVENARZT 2005; 76:984-7. [PMID: 15905982 DOI: 10.1007/s00115-004-1864-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Sarcoidosis is an inflammatory multisystemic disease characterised by noncaseating epithelioid granulomas. The lung is affected in over 90% of patients. According to clinical criteria, the nervous system is involved in 5-9%. However, in autopsy series this number increases to 25%. Solitary involvement of the nervous system without signs of systemic disease is rare and diagnostically cryptic. Due to the wide variety of neurologic symptoms, definite diagnosis of sarcoidosis is possible only by histopathological proof of noncaseating epithelioid granulomas. We report a 51-year-old woman who presented with chronic basal meningitis and involvement of the peripheral and central nervous system due to solitary neurosarcoidosis. Diagnostic procedures and differential diagnosis are discussed.
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Initial DWI and ADC imaging may predict outcome in acute disseminated encephalomyelitis: report of two cases of brain stem encephalitis. J Neurol Neurosurg Psychiatry 2005; 76:996-8. [PMID: 15965210 PMCID: PMC1739724 DOI: 10.1136/jnnp.2004.045500] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Two young patients with acute disseminated encephalomyelitis (ADEM) of the brain stem are described. In spite of similar lesion sites in the brain stem, reaching from the upper medulla to the mesencephalon, the outcomes of the patients were very different: one made a full clinical recovery within three weeks while the other remained in a locked-in state more than a year after the disease episode. Both patients also differed in magnetic resonance imaging (MRI) findings on admission. The patient who remained in a locked-in state had pathological diffusion weighted imaging (DWI) scans and decreased apparent diffusion coefficient maps initially, with severe tissue destruction on follow up computed tomography, while the patient who recovered fully showed initially increased apparent diffusion coefficient values and almost complete resolution of MRI changes on follow up. Thus a comparison of these two cases may indicate differences in the underlying pathology in ADEM (vasogenic v cytotoxic oedema) that may be crucial for estimating tissue damage and clinical outcome.
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Hochaufgelöste suszeptibilitätsgewichtete MR-Bildgebung bei Hirntumoren unter Modulation der Blutoxygenierung. ROFO-FORTSCHR RONTG 2005. [DOI: 10.1055/s-2005-868334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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15
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Hochauflösende suszeptibilitätsgewichtete Bildgebung als diagnostische Möglichkeit in der pädiatrischen Neuroradiologie. ROFO-FORTSCHR RONTG 2005. [DOI: 10.1055/s-2005-868314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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16
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Visualisierung der symmetrischen Stammganglienverkalkung mittels räumlich hochaufgelöster suszeptibilitätsgewichteter MR-Bildgebung. ROFO-FORTSCHR RONTG 2005. [DOI: 10.1055/s-2005-868327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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17
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MR-Volumetrie der Hypophyse: In-vitro- and In-vivo-Resultate einer neuen semiautomatischen interaktiven Segmentationstechnik. ROFO-FORTSCHR RONTG 2005. [DOI: 10.1055/s-2005-868328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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18
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Long-Term Brain Atrophy after Focal Ischemic Stroke: A Longitudinal Study Applying Deformation-Based Morphometry. KLIN NEUROPHYSIOL 2004. [DOI: 10.1055/s-2004-832160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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19
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Clinical course of isolated brain stem strokes. KLIN NEUROPHYSIOL 2004. [DOI: 10.1055/s-2004-831973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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20
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Exposure to a Routine MRI Brain Scan at 1.5 T does not affect Subsequent MEG Examinations. KLIN NEUROPHYSIOL 2004. [DOI: 10.1055/s-2004-831972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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21
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Optimized Voxel-Based Group Analysis of Diffusion Tensor Imaging by means of Barycentric Linear Anisotropy. KLIN NEUROPHYSIOL 2004. [DOI: 10.1055/s-2004-832031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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22
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Does the Shape of the Brain Depend on Gravity? KLIN NEUROPHYSIOL 2004. [DOI: 10.1055/s-2004-832203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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23
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Volumetry of the Pituitary Gland: An Initial in vitro and in vivo MR Study. KLIN NEUROPHYSIOL 2004. [DOI: 10.1055/s-2004-831940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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24
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Impedance Measurements and Tissue Characteristics of the Human Brain: Real-Time Impedance Monitoring During Stereotactic Procedures. KLIN NEUROPHYSIOL 2004. [DOI: 10.1055/s-2004-831917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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25
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BOLD-MR Angiography as a Diagnostic Tool for Asymptomatic Cavernomas in Children. KLIN NEUROPHYSIOL 2004. [DOI: 10.1055/s-2004-832091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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26
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Application of Exogeneous Gaseous Agents in Patients with Brain Tumors using High-Resolution Susceptibility-Weighted Imaging. KLIN NEUROPHYSIOL 2004. [DOI: 10.1055/s-2004-832133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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27
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Visualization of symmetric striatopallidodentate calcinosis by using a high-resolution susceptibility-weighted MR sequence. KLIN NEUROPHYSIOL 2004. [DOI: 10.1055/s-2004-831935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Abstract
Posterior reversible encephalopathy syndrome is a proposed cliniconeuroradiological entity characterized by headache, altered mental status, cortical blindness, seizures, and other focal neurological signs, and a diagnostic magnetic resonance imaging picture. A variety of different etiologies have been reported like hypertension, pre-eclampsia/eclampsia, cyclosporin A or tacrolimus neurotoxicity, uraemia and porphyria. With early diagnosis and prompt treatment, the syndrome is usually fully reversible. We report a case of recurrent PRES of unknown aetiology following intensive care unit treatment and only moderately elevated blood pressure. Clinicians as well as radiologists must be familiar with this clinically frightening, underdiagnosed condition to assure timely diagnosis and treatment to prevent persistent deficits.
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Frühzeitige Diagnose intrakranieller Veränderungen bei Mb. Sturge-Weber mit räumlich hochaufgelöster MR-Venographie. ROFO-FORTSCHR RONTG 2004. [DOI: 10.1055/s-2004-828103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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30
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Hochaufgelöste MR-Venographie zur Detektion multipler Cavernome im Kindesalter. ROFO-FORTSCHR RONTG 2004. [DOI: 10.1055/s-2004-828194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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31
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Zwei Fälle von Hirnstammenzephalitis - ADC und DWI als mögliche Prognosefaktoren für die neurologische Restitution. AKTUELLE NEUROLOGIE 2004. [DOI: 10.1055/s-2004-833415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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32
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Echoplanar diffusion-weighted MRI with intravenous gadolinium-DTPA. Neuroradiology 2003; 45:592-7. [PMID: 12923668 DOI: 10.1007/s00234-003-0965-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2002] [Accepted: 02/04/2003] [Indexed: 11/24/2022]
Abstract
It is occasionally necessary to repeat diffusion weighted imaging (DWI) after giving intravenous contrast medium (CM). However, the effects of CM on DWI and apparent diffusion coefficients (ADC) have not been fully examined. The aim of this prospective study was to investigate whether there are any diagnostically significant differences between echo-planar imaging (EPI)-DWI before and after intravenous CM. EPI-DWI was acquired twice in 203 consecutive patients before and after i.v. CM. Three blinded readers rated the diagnostic image quality. Quantitative ADC calculations were performed before and after CM in all 72 patients with lesions sufficiently large for quantification, and in 72 normal brain regions. Of the 203 patients, 127 had abnormalities on MRI, including ischaemic stroke (52), bleeding (nine), brain tumour with disturbed blood-brain barrier (BBB) (18) and other lesions (48). There were no significant signal differences on isotropic DWI before and after CM, even in lesions with definite disturbance of the BBB. No statistically significant difference between ADC of lesions and contralateral normal brain was observed.
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Diffusion weighted magnetic resonance imaging in the diagnosis of reversible ischaemic deficits of the brainstem. J Neurol Neurosurg Psychiatry 2002; 72:572-5. [PMID: 11971039 PMCID: PMC1737856 DOI: 10.1136/jnnp.72.5.572] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVES To evaluate the sensitivity of diffusion weighted magnetic resonance imaging (MRI) for the diagnosis of clinically suspected reversible ischaemic deficits of the brainstem. METHODS A total of 158 consecutive patients presenting with acute signs of brainstem dysfunction were investigated using EPI diffusion weighted MRI within 24 hours of the onset of symptoms. High resolution T1 and T2 weighted imaging was performed as a follow up after a median of six days. RESULTS Fourteen of the 158 patients had a complete clinical recovery within 24 hours (transitory ischaemic attack (TIA)), and 19 patients recovered in less than one week (prolonged reversible neurological deficit (RIND)). Diffusion weighted MRI showed acute ischaemic deficits in 39% of patients with transient neurological deficits. The detection rate seemed to be higher in patients with longer lasting symptoms, but the difference between patients with TIA (29%) and RIND (47%) was not significant. CONCLUSIONS Diffusion weighted MRI is a sensitive indicator of acute ischaemic brainstem deficits even in patients with reversible neurological deficit. Early identification of patients with TIA and increased risk of stroke may influence acute management and improve patient outcome.
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The masseter reflex: postprocessing methods and influence of age and gender. Normative values of the masseter reflex. Eur Neurol 2002; 46:202-5. [PMID: 11721127 DOI: 10.1159/000050805] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
OBJECTIVES Normative values of the masseter reflex are scarce. We studied the latencies, amplitudes and side differences of the masseter reflex in 105 healthy volunteers between the ages of 5 and 78 years. METHODS Latencies were calculated as the mean of 10 single sweeps and, simultaneously, measured from the summation curve. Short-term reproducibility was determined in 33 volunteers by retesting the reflex after 1 week. RESULTS There was a positive correlation between age and latencies and a negative correlation between age and amplitude. Maximal normal latencies were 8.3 ms for men and 7.9 ms for women in the age group below 50 years and 9.1 and 9.2 ms for the age group above 50 years. Latency differences between the right and left sides of >0.4 ms for subjects aged below 50 years and >0.5 ms for subjects aged above 50 years exceeded the 95% confidence interval. Amplitudes did not depend on gender. Calculated as a percentage of the side with higher amplitude, differences above one third could be accepted as abnormal. CONCLUSION The masseter reflex appears to be a stable and robust clinical test, if age and gender differences are taken into account.
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Abstract
We acquired high-resolution MRI and anisotropically diffusion-weighted images (DWI) with direction-selective gradients of the brain stem in 20 healthy volunteers, to identify brain-stem structures such as white-matter tracts and nuclei which show diffusion anisotropy. After averaging and superposition of individual cuts, the images were projected onto appropriate plates of the Schaltenbrand and Wahren anatomical atlas. We identified 20 structures--white-matter tracts and some nuclei--with high contrast. The direction of fibres could be determined as areas of increased (parallel to) or decreased diffusion (perpendicular to the gradient). This study may contribute to understanding of the functional anatomy of the brain stem.
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Topodiagnostic value of blink reflex R1 changes: a digital postprocessing MRI correlation study. Muscle Nerve 2001; 24:1327-31. [PMID: 11562912 DOI: 10.1002/mus.1151] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The aim of the study was to investigate the relation of the blink reflex R1 arc to known anatomical brainstem structures. Acute vascular brainstem lesions as identified by magnetic resonance imaging (MRI) of patients with isolated R1 pathology were superimposed into a stereotactic anatomical atlas using a new method of digital postprocessing. Isolated acute brainstem lesions were documented by diffusion-weighted MRI in 12 of 24 patients with unilateral R1 pathology. The lesions were located in the ipsilateral mid- to lower pons. In three patients only, the lesion had partial contact with the principal sensory nucleus of the trigeminal nerve (PSN) on at least one level. In two patients, the lesion involved the medial longitudinal fasciculus. Most lesions were located medially and ventrally to the PSN on transverse slices. Our results underline the high localizing value of changes in the R1 component of the blink reflex in patients with ipsilateral pontine functional deficits. Although available physiological evidence suggests that the R1 component of the blink reflex traverses an oligosynaptic pathway, this MRI study does not support the view that synaptic transmission in the PSN subserves R1. The reflex arc probably descends more medially and ventrally on its course to the facial nucleus.
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Drug-induced nonconvulsive status epilepticus with low dose of tiagabine. Epileptic Disord 2001; 3:147-50. [PMID: 11679307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
In placebo-controlled trials, the overall incidence of nonconvulsive status epilepticus was no higher in the tiagabine-treated group than in the placebo-group. Case reports of nonconvulsive status epilepticus under tiagabine suggested a specific role of dose levels, since in these patients symptoms occurred mostly at 40 mg/day or higher. We report a case of complex partial status epilepticus in a patient receiving a low dose of tiagabine and review all 11 case reports of nonconvulsive status epilepticus in patients on tiagabine, with regard to daily doses. Our analysis suggests an individual risk threshold of unknown aetiology.
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Time course of lesion development in patients with acute brain stem infarction and correlation with NIHSS score. Eur J Radiol 2001; 39:180-5. [PMID: 11566246 DOI: 10.1016/s0720-048x(01)00372-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND AND PURPOSE diffusion weighted magnetic resonance imaging (MRI) is highly sensitive in detecting acute supratentorial cerebral ischemia and Diffusion Weighted Imaging (DWI) lesion size has been shown to correlate strongly with the neurologic deficit in middle cerebral artery territory stroke. However, data concerning infratentorial strokes are rare. We examined the size and evolution of acute brain stem ischemic lesions and their relationship to neurological outcome. METHODS brain stem infarctions of 11 patients were analyzed. We performed DWI in all patients and in 7/11 patients within 24 h, T2W sequences within the first 2 weeks (10/11 patients) and follow-up MRI (MR2) within 3-9 months (median 4.8 months) later (12/12 patients). Lesion volumes were compared with early and follow-up neurologic deficit as determined by National Institutes of Health Stroke Scale (NIHSS) score. RESULTS the relative infarct volumes--with MR2 lesion size set to 100%--decreased over the time (P<0.02) with a mean shrinking factor of 3.3 between DWI (MR0) and the follow-up MRT (P<0.02), and 1.6 between early T2W (MR1) and MR2 (P<0.04). The mean DWI volume size (MR0) was larger than the early T2W (P<0.02). Although neurological outcome was good in all patients (mean NIHSS score of 1.3 at follow-up), early NIHSS and follow-up NIHSS scores were strongly correlated (r=0.9, P<0.00). NIHSS score at follow-up was highly correlated with lesion size of DWI (MR0; r=0.71, P<0.04) and T2W of MR1 (r=0.86, P<0.001). CONCLUSIONS in this study, we saw a shrinking of the brain stem infarct volume according to clinical improvement of patients. Great extension of restricted diffusion in the acute stage does not necessarily implicate a large resulting infarction or a bad clinical outcome.
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A new method to investigate brain stem structural-functional correlations using digital post-processing MRI--reliability in ischemic internuclear ophthalmoplegia. Eur J Neurol 2001; 8:489-93. [PMID: 11554915 DOI: 10.1046/j.1468-1331.2001.00279.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We investigated the reliability of a new digital post-processing magnetic resonance imaging (MRI) technique in ischemic brain stem lesions to identify relations of the lesion to anatomical brain stem structures. The target was a medial longitudinal fasciculus (MLF) lesion, which was evident from ipsilateral internuclear ophthalmoplegia (INO). Sixteen patients with acute unilateral INO and an isolated acute brain stem lesion in T2- and EPI-diffusion weighted MRI within 2 days after the onset of symptoms were studied. The MRI slice direction was parallel and perpendicular to a slice selection of a stereotactic anatomical atlas. The individual slices were normalized and projected in the digitalized atlas. The eye movement disorder was monitored by electro-oculography. In all patients with clinical or subclinical electro-oculographically documented INO and MRI proven brain stem infarction the lesion covered or at least partially overlapped the ipsilateral MLF at one or more atlas levels. We conclude that digital post-processing MRI with normalizing and projecting brain stem lesions in an anatomical atlas is a reliable method to demonstrate the anatomical structures involved by the lesion. Combined with electrophysiological brain stem testing, this method may be a useful tool to identify incompletely understood pathways mediating brain stem reflexes or the generators of evoked potentials.
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Wertigkeit der Elektrophysiologie bei Hirnstammischämie und normalem diffusionsgewichteten und hoch auflösenden MRT. KLIN NEUROPHYSIOL 2001. [DOI: 10.1055/s-2001-17281] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Abstract
Transcranial magnetic stimulation was used to investigate the corticofacial projections in 53 patients with (n = 28) and without (n = 25) central facial paresis due to unifocal ischaemic lesions at different brainstem levels. Lesion topography documented by MRI studies was correlated with the electrophysiological findings. In the majority of patients the corticofacial fibres travel within the ventromedial base of the pons and cross the midline at the level of the facial nucleus. In some individuals, however, we found evidence that corticolingual fibres form an 'aberrant bundle' in a paralemniscal position at the dorsal edge of the pontine base. In other patients the corticofacial fibres loop down into the ventral part of the upper medulla, cross the midline and ascend in the dorsolateral medullary region ipsilaterally to the facial nucleus. The findings suggest that facial paresis due to a brainstem lesion may present as contralateral supranuclear facial paresis by a lesion of the cerebral peduncle, pontine base, the aberrant bundle and the ventral medulla. Supranuclear facial paresis ipsilateral to the lesion side may result from a lesion in the lateral medulla, and facial paresis of the supranuclear type may be imitated by a lesion of the peripheral facial nerve in the dorsolateral medulla with involvement of the lower pons.
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Apparent diffusion coefficient decreases and magnetic resonance imaging perfusion parameters are associated in ischemic tissue of acute stroke patients. J Cereb Blood Flow Metab 2001; 21:577-84. [PMID: 11333368 DOI: 10.1097/00004647-200105000-00012] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Perfusion-and diffusion-weighted magnetic resonance imaging scans are thought to allow the characterization of tissue at risk of infarction. The authors tested the hypothesis that the apparent diffusion coefficient (ADC) decrease should be associated with the severity of the perfusion deficit in ischemic tissue of acute stroke patients. Perfusion-and diffusion-weighted scans were performed in 11 patients with sudden onset of neurologic deficits within the last 6 hours and T2-weighted magnetic resonance imaging scans were obtained after 6 days. Parameter images of the maximum of the contrast agent concentration, time to peak, relative cerebral blood volume, relative cerebral blood flow, and relative mean transit time were computed from the perfusion-weighted data. A threshold function was used to identify tissue volumes with stepwise ADC decreases. An onionlike distribution of successively decreasing ADC values was found, with the lowest ADC in the center of the ischemic region. Correspondingly, tissue perfusion decreased progressively from the periphery toward the ischemic core. This effect was most pronounced in the time-to-peak maps, with a linear association between ADC decrease and time-to-peak increase. Apparent diffusion coefficient values decreased from the periphery toward the ischemic core, and this distribution of ADC values was strongly associated with the severity of the perfusion deficit.
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Abstract
Our purpose of this study was to demonstrate the clinical potential and spatial resolution of a new MRI technique: high-resolution blood oxygen-level dependent venography (HRBV), in well-known intracranial vascular lesions, such as cavernous and venous angiomas, and venous sinus thrombosis. HRBV provides unique high-resolution information on veins without administration of contrast medium. The data are independent of conventional findings on MRI and potentially useful in characterising and demonstrating the architecture of vascular lesions of the brain.
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Dysarthria in acute ischemic stroke: lesion topography, clinicoradiologic correlation, and etiology. Neurology 2001; 56:1021-7. [PMID: 11320172 DOI: 10.1212/wnl.56.8.1021] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND AND PURPOSE Although dysarthria is a frequent symptom in cerebral ischemia, there is little information on its anatomic specificity, spectrum of associated clinical characteristics, and etiologic mechanisms. METHODS An investigation of 68 consecutive patients with sudden onset of dysarthria due to a single infarction confirmed by MRI or CT was conducted. RESULTS Dysarthria was associated with a classic lacunar stroke syndrome in 52.9% of patients. Isolated dysarthria and dysarthria-central facial and lingual paresis occurred in 2.9% (n = 2) and 10.3% (n = 7), respectively. Dysarthria-clumsy hand syndrome was observed in 11.7% (n = 8) of patients and associated with pure motor hemiparesis and/or ataxic hemiparesis in 27.9% (n = 19). The lesions were due to small-vessel disease in 52.9% (n = 36), to cardioembolism in 11.8% (n = 8), and to large-vessel disease in only 4.4% (n = 3) of cases. Infarctions were located in the lower part of the primary motor cortex (5.9%; n = 4), middle part of the centrum semiovale (23.5%; n = 16), genu and ventral part of the dorsal segment of the internal capsule (8.8%; n = 6), cerebral peduncle (1.5%; n = 1), base of the pons (30.9%; n = 21), and ventral pontomedullary junction (1.5%; n = 1). Isolated cerebellar infarctions affected the rostral paravermal region in the superior cerebellar artery territory. CONCLUSIONS Extracerebellar infarcts causing dysarthria were located in all patients along the course of the pyramidal tract. This finding correlates with the frequent occurrence of associated pyramidal tract signs in 90.7% (n = 62) of patients. Isolated cerebellar infarcts leading to dysarthria were in all cases located in the territory of the superior cerebellar artery.
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Mechanisms and predictors of chronic facial pain in lateral medullary infarction. Ann Neurol 2001; 49:493-500. [PMID: 11310627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
The purpose of this study was to identify clinical predictors and anatomical structures involved in patients with pain after dorsolateral medullary infarction. Eight out of 12 patients (67%) developed poststroke pain within 12 days to 24 months after infarction. The pain occurred in the ipsilateral face (6 patients) and/or the contralateral limbs and trunk (5 patients, 3 of whom also had facial pain). Ipsilateral facial pain was significantly correlated with lower medullary lesions, including those of the spinal trigeminal tract and/or nucleus, as documented by magnetic resonance imaging. The R2 blink reflex component was abnormal only in patients with facial pain. Likewise, pain and temperature sensation in the ipsilateral face was decreased in all patients with facial pain but not in patients without pain. Ipsilateral touch sensation in the face was also decreased in all patients with facial pain, but the lesions revealed on magnetic resonance imaging did not involve the principal sensory nucleus of the fifth cranial nerve, and the R1 blink reflex latencies were normal. Although facial pain was correlated with lesions of the spinal trigeminal tract and/or nucleus, none of the lesions involved the subnucleus caudalis, which contains most nociceptive neurons. These findings suggest that facial pain after medullary infarction is due to lesions of the lower spinal trigeminal tract (axons of primary afferent neurons), leading to deafferentation of spinal trigeminal nucleus neurons.
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Intracranial and extracranial MR angiography in occipital horn syndrome. Eur Radiol 2001; 10:1683. [PMID: 11044951 DOI: 10.1007/pl00022807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Vasculitic wallenberg syndrome with detection of anti-proteinase 3 antibodies in the cerebrospinal fluid of a patient with severe Wegener's granulomatosis and only mild kidney involvement. Nephrol Dial Transplant 2000; 15:893-6. [PMID: 10831648 DOI: 10.1093/ndt/15.6.893] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Blink reflex R2 changes and localisation of lesions in the lower brainstem (Wallenberg's syndrome): an electrophysiological and MRI study. J Neurol Neurosurg Psychiatry 1999; 67:630-6. [PMID: 10519870 PMCID: PMC1736618 DOI: 10.1136/jnnp.67.5.630] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVES Pathways of late blink reflexes are detected by high resolution MRI. Electronically matched stroke lesions superimposed to an anatomical atlas show the suspected course. METHODS Fifteen patients with infarction of the lower brainstem, MRI lesions and electrically elicited blink reflexes were examined. The involved structures in patients with R2 and R2c blink reflex changes were identified by biplane high resolution MRI with individual slices matched to an anatomical atlas at 10 different levels using digital postprocessing methods. RESULTS The blink reflexes were normal in five of 15 patients (33%) and showed loss or delay of R2 and R2c to stimulation ipsilaterally to lesion (R2-i and R2c-i) in eight (53%). Loss or delay of R2-i/R2c-i was seen in lesions covering the entire trigeminal spinal tract and nucleus (TSTN) at at least one level. These infarctions were located more dorsally within the medulla. Patients with normal blink reflexes showed lesions sparing or involving the TSTN only partially. They more often had incomplete Wallenberg's syndromes and MRI lesions were located more ventrally. CONCLUSIONS Using digital postprocessing MRI methods it was possible to identify central pathways of late blink reflex in patients with Wallenberg's syndrome. This method is suggested as a new approach to identify incompletely understood functional structures of the brainstem.
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