S. Siemonsen

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Quantitative transverse relaxation rates in normal aging brain are essential to investigate pathologies associated with iron accumulation and tissue degeneration. Since absolute values depend on imaging methods and magnetic field strengths, continuous evaluation of specific reference values remains requisite. Multi-echo turbo spin echo and multi-echo(More)
BACKGROUND AND PURPOSE The purpose of this study was to analyze angiographic and clinical results before and after additional endovascular therapy in patients with previously coiled but reopened cerebral aneurysms and to identify possible risk factors for retreatment of an aneurysm. MATERIALS AND METHODS Follow-up with selective digital subtraction(More)
BACKGROUND AND PURPOSE We hypothesize that in comparison to diffusion-weighted imaging, quantitative T2 values (qT2) are more directly related to water uptake in ischemic tissue, depending on time from symptom onset. We measured the increase of qT2 in the infarct core to quantify the correlation between time from symptom onset and change in qT2. METHODS(More)
BACKGROUND AND PURPOSE Physiologic age-related T2* and T2' values are required as reference for comparison with disease-related deviations. In our study, T2* and T2' values (T2 values as control) were determined with MR imaging in healthy subjects to determine standard values and investigate age-related changes. MATERIALS AND METHODS Data of 50 patients(More)
OBJECTIVE To evaluate the use of fluid-attenuated inversion recovery (FLAIR) imaging as surrogate marker of lesion age within the first 6 hours of ischemic stroke. METHODS e analyzed FLAIR and diffusion-weighted imaging (DWI) sequences performed within 6 hours of symptom onset in 120 consecutive patients with ischemic stroke with known symptom onset. The(More)
BACKGROUND AND PURPOSE The purpose of this study was to estimate the safety and efficacy of abciximab treatment in combination with prophylactic heparin, acetylsalicylic acid (ASA), and clopidogrel application in cases of thrombus formation complicating endovascular coil embolization in cerebral aneurysms. METHODS Thromboembolic incidents during(More)
T2’ values reflect the presence of deoxyhaemoglobin related to high local oxygen extraction. We assessed the feasibility of T2’ imaging to display regions with high metabolic activity in brain gliomas. MRI was performed in 25 patients (12 female; median age 46 years; range 2–69) with brain gliomas with additional T2 and T2* sequences. T2’ maps were derived(More)
Different compositions of the extra cellular matrix with changing concentrations of more or less hydrophilic components like proteins may have a major influence on the diffusion phenomena found in gliomas. 24 patients (14 male / 10 female) with histologically confirmed non necrotic glioma underwent preoperative MRI, including magnetisation transfer (MTR),(More)
INTRODUCTION The objective of our study was to determine whether the combination of hypointense spots ("cerebral microbleeds," CMBs) with a leukoaraiosis is associated with the risk of parenchymal hematoma (PH) after thrombolytic therapy. PATIENTS AND METHODS We analyzed magnetic resonance imaging (MRI) scans acquired within 6 hours after symptom onset(More)
BACKGROUND AND PURPOSE T2'-Magnetic resonance imaging (MRI) allows estimation of oxygen metabolism in normal appearing white and gray matter (NAWM and NAGM) and is sensitive to local iron deposition. We hypothesized that T2' imaging is feasible in routine use and reveals differences between MS patients and healthy subjects. METHODS T2- and T2*-weighted(More)