0000000000179788
AUTHOR
Ernst-wilhelm Otten
Quantification of Regional Intrapulmonary Oxygen Partial Pressure Evolution during Apnea by 3He MRI
We present a new method to determine in vivo the temporal evolution of intrapulmonary oxygen concentrations by functional lung imaging with hyperpolarized (3)Helium ((3)He-->). Single-breath, single-bolus visualization of (3)He--> administered to the airspaces is used to analyze nuclear spin relaxation caused by the local oxygen partial pressure p(O(2))(t). We model the dynamics of hyperpolarization in the lung by rate equations. Based hereupon, a double acquisition technique is presented to separate depolarization by RF pulses and oxygen induced relaxation. It permits the determination of p(O(2)) with a high accuracy of up to 3% with simultaneous flip angle calibration using no additional …
MR imaging of the lungs with hyperpolarized helium-3 gas transported by air.
Hyperpolarized noble gas MRI shows promise in the functional imaging of the pulmonary air spaces. The production of hyperpolarized (HP) gas requires specialized laser optical pumping apparatus, which is not likely to be home built in the majority of clinical MRI radiology centres. There are two routes through which HP gas will be made available to hospitals for clinical use: either the apparatus will be installed locally at a considerable expense to the centre, or a central facility will produce the gas and then deliver it to remote MRI sites as and when required. In this study, the feasibility of transporting large quantities of HP gas for in vivo MR imaging from a remote production facili…
Final State Interaction Effects in 3He(e ,e'p)
Abstract Asymmetries in quasi-elastic 3 He ( e → , e ′ p ) have been measured at a momentum transfer of 0.67 (GeV/ c ) 2 and are compared to a calculation which takes into account relativistic kinematics in the final state and a relativistic one-body current operator. With an exact solution of the Faddeev equation for the 3 He -ground state and an approximate treatment of final state interactions in the continuum good agreement is found with the experimental data.
Precision measurement of the conversion electron spectrum of 83mKr with a solenoid retarding spectrometer
This paper reports on precision measurements of conversion lines in the decay of 83mKr with nuclear transition energies of 32.1 keV and 9.4 keV, respectively. The spectra were taken from a submonolayer surface of 83mKr frozen onto a cold backing, using the new Mainz solenoid retarding spectrometer. The high luminosity and resolution of this instrument enables the observation of all allowed conversion lines up to the N-shell and to fully separate the elastic component from inelastic satellites. The combined analysis of the data yields the transition energies Ey=32151.5±1.1 eV and 9405.9±0.8 eV, respectively. The experiment served also to pilot the application of this spectrometer to the ques…
On dewetting dynamics of solid films of hydrogen isotopes and its influence on tritium [Beta] spectroscopy
The dewetting dynamics of solid films of hydrogen isotopes, quench-condensed on a graphite substrate, was measured at various temperatures below desorption by observing the stray light from the film. A schematic model describing the dewetting process by surface diffusion is presented, which agrees qualitatively with our data. The activation energies of different hydrogen isotopes for surface diffusion were determined. The time constant for dewetting of a quench-condensed T2 film at the working temperature of 1.86 K of the mainz neutrino mass experiment was extrapolated.
Assessment of a single-acquisition imaging sequence for oxygen-sensitive (3)He-MRI.
MRI of the lungs using hyperpolarized helium-3 (3He) allows the determination of intrapulmonary oxygen partial pressures (pO2). The need to separate competing processes of signal loss has hitherto required two different imaging series during two different breathing maneuvers. In this work, a new imaging strategy to measure pO2 by a single series of consecutive scans is presented. The feasibility of the method is demonstrated in three healthy human volunteers. Maps and histograms of intrapulmonary pO2 are calculated. Changes in the oxygen concentration of the inhaled gas mixture are well reproduced in the histograms. Monte Carlo (MC) simulations of the temporal evolution of 3He hyperpolariza…
Stability of solid T2 films
Abstract Films of molecular tritium, physisorbed on a cold substrate, have been investigated by means of ellipsometry. A significant effect of the radioactive decay processes on the desorption kinetics and the low temperature stability of these films is not observed.