0000000000073712
AUTHOR
Timothy P.l. Roberts
Flußquantifizierung von intrakardialen Shuntvolumina unter Verwendung der MR-Phasenkontrast-Technik in Atemanhaltephase
PURPOSE Comparison of a breath-hold, velocity-encoded, phase-difference magnetic resonance (MR) sequence for intracardiac shunt flow measurement with the invasive shunt size determination by oximetry. PATIENTS AND METHODS 10 patients with different cardiac shunts (6 ASD/3 VSD/1 PDA) and four healthy individuals were investigated using a 1.5 Tesla Siemens Vision system. For flow measurements a breath-hold, velocity-encoded, phase-difference magnetic resonance (MR) sequence was used ('through plane', FLASH 2D-sequence, TR/TE 110/5 ms, 'velocity encoding' 250 cm/s). Mean flow (ml/R-R interval) in the ascending aorta, the pulmonary trunk, and the right and left pulmonary arteries was determined…
MRI using hyperpolarized noble gases.
The aim of this study was to review the physical basis of MRI using hyperpolarized noble gases as well as the present status of preclinical and clinical applications. Non-radioactive noble gases with a nuclear spin 1/2 (He-3, Xe-129) can be hyperpolarized by optical pumping. Polarization is transferred from circularly polarized laser light to the noble-gas atoms via alkali-metal vapors (spin exchange) or metastable atoms (metastability exchange). Hyperpolarization results in a non-equilibrium polarization five orders of magnitude higher than the Boltzmann equilibrium compensating for the several 1000 times lower density of noble gases as compared with liquid state hydrogen concentrations in…
The Chameleon on the branches: spectral state transition and dips in NGC 247 ULX-1
Soft Ultra-Luminous X-ray (ULXs) sources are a subclass of the ULXs that can switch from a supersoft spectral state, where most of the luminosity is emitted below 1 keV, to a soft spectral state with significant emission above 1 keV. In a few systems, dips have been observed. The mechanism behind this state transition and the dips nature are still debated. To investigate these issues, we obtained a long XMM-Newton monitoring campaign of a member of this class, NGC 247 ULX-1. We computed the hardness-intensity diagram for the whole dataset and identified two different branches: the normal branch and the dipping branch, which we study with four and three hardness-intensity resolved spectra, r…
Broadband X-ray spectral variability of the pulsing ULX NGC 1313 X-2
[Context] It is thought that ultraluminous X-ray sources (ULXs) are mainly powered by super-Eddington accreting neutron stars or black holes as shown by the recent discovery of X-ray pulsations and relativistic winds. [Aims] This work presents a follow-up study of the spectral evolution over two decades of the pulsing ULX NGC 1313 X-2 in order to understand the structure of the accretion disc. The primary objective is to determine the shape and nature of the dominant spectral components by investigating their variability with the changes in the source luminosity. [Methods[ We performed a spectral analysis over the canonical 0.3-10.0 keV energy band of all the high signal-to-noise XMM-Newton…
Helium-3-MRT der Lungenventilation: Erste klinische Anwendungen
PURPOSE: of the study is the visualisation of normal pulmonary ventilation in healthy volunteers and the evaluation of abnormalities in patients with different lung diseases using 3He magnetic resonance imaging (3He-MRI). MATERIAL AND METHODS: Hyperpolarized 3He gas (V = 300 ml, p = 3 x 10(5) Pa, polarised to 35-45% by optical pumping, provided in special glass cells) was inhaled by eight healthy volunteers and ten patients with different lung diseases. A 3D FLASH sequence (TR = 11.8 ms; TE = 5 ms; matrix 144 x 256, FOV 350 mm, section thickness 7-10 mm, coronal orientation) was performed in a single breath-hold (22-42 s). Clinical and radiological examinations were available for correlatio…
Quasi-periodic dipping in the ultraluminous X-ray source, NGC 247 ULX-1
Most ultraluminous X-ray sources (ULXs) are believed to be stellar mass black holes or neutron stars accreting beyond the Eddington limit. Determining the nature of the compact object and the accretion mode from broadband spectroscopy is currently a challenge, but the observed timing properties provide insight into the compact object and details of the geometry and accretion processes. Here we report a timing analysis for an 800 ks XMM-Newton campaign on the supersoft ultraluminous X-ray source, NGC 247 ULX-1. Deep and frequent dips occur in the X-ray light curve, with the amplitude increasing with increasing energy band. Power spectra and coherence analysis reveals the dipping preferential…
Diagnose eines intramyokardialen Hämatoms nach traumatischem Myokardinfarkt durch Magnetresonanztomographie
Thoraxverletzungen treten bei etwa 30% aller traumatisierten Patienten auf, wobei in den meisten Fallen Verkehrsunfalle die Ursache sind. Wir berichten uber den Fall eines Patienten, der nach einem Skiunfall einen traumatischen Vorderwandinfarkt erlitt. Im weiteren Verlauf kam es zu einer ausgedehnten intramyokardialen Einblutung. Differentialdiagnostisch kam zunachst ein linksventrikulares Pseudo- bzw. Pseudopseudoaneurysma in Frage, kernspintomographisch konnte jedoch durch den Nachweis eines schmalen Myokardsaums sowohl ventral als auch dorsal der Raumforderung die Diagnose eines intramyokardialen Hamatoms gestellt werden. Bei dem Patienten wurde daraufhin eine aortokoronare Bypass-Opera…
Analysis of intrapulmonary O2concentration by MR imaging of inhaled hyperpolarized helium-3
Inhalation of hyperpolarized 3He allows magnetic resonance imaging (MRI) of ventilated airspaces.3He hyperpolarization decays more rapidly when interacting with paramagnetic O2. We describe a method for in vivo determination of intrapulmonary O2 concentrations ([O2]) based on MRI analysis of the fate of measured amounts of inhaled hyperpolarized3He in imaged regions of the lung. Anesthetized pigs underwent controlled normoventilation in a 1.5-T MRI unit. The inspired O2 fraction was varied to achieve different end-tidal [O2] fractions ([Formula: see text]). With the use of a specifically designed applicator,3He (100 ml, 35–45% polarized) was administered at a predefined time within single …
Die akute Gefäßperforation mit Shuntbildung in den rechten Ventrikel nach perkutaner transluminaler Koronarangioplastie. Kernspintomographischer und dopplersonographischer Nachweis des Shuntflusses
Die Gefasperforation nach transluminaler Koronarangioplastie (PTCA) stellt eine seltene Komplikation dieser etablierten Behandlungsmethode dar. Die Therapie wird bestimmt durch die hamodynamische Beeintrachtigung des linken oder rechten Ventrikels. Wir berichten uber den Fall einer Gefasperforation nach PTCA mit Shuntbildung von der rechten Koronararterie in den rechten Ventrikel, wobei der Shuntflus sowohl kernspintomographisch als auch dopplersonographisch dargestellt werden konnte.