Interpreting MR images of the lumbar spine remains a formidable diagnostic challenge, especially in patients with degenerative changes. What are the pertinent findings? Which abnormalities are ...clinically relevant? Which changes should be viewed as normal aging? The purpose of this presentation is to present a standardized 7-step approach towards interpreting MR images of the degenerative lumbar spine.
Nucl.Phys.A681:291-294,2001 Inclusive and exclusive hard-photon (E$_\gamma >$ 30 MeV) production in five
different heavy-ion reactions ($^{36}$Ar+$^{197}$Au, $^{107}$Ag, $^{58}$Ni,
$^{12}$C at 60{\it ...A} MeV and $^{129}$Xe+$^{120}$Sn at 50{\it A} MeV) has been
studied coupling the TAPS photon spectrometer with several charged-particle
multidetectors covering more than 80% of 4$\pi$. The measured spectra, slope
parameters and source velocities as well as their target-dependence, confirm
the existence of thermal bremsstrahlung emission from secondary nucleon-nucleon
collisions that accounts for roughly 20% of the total hard-photon yield. The
thermal slopes are a direct measure of the temperature of the excited nuclear
systems produced during the reaction.
Magnetic resonance imaging (MRI) examinations of the brain can be performed with several coil types, depending on the design of the MRI unit and the information required. Traditionally, MRI ...examinations of the brain are performed with quadrature (i.e., circularly polarized) head coils. These volume coils are closely shaped around the head of the patient and usually present a so-called “bird-cage” configuration. Many coils are split in half, for easier patient access and positioning. Recently, phased-array head coils have become the standard of practice for state-of-the-art high-resolution MRI of the brain. Phased-array head coils contain multiple small coil elements, which are arranged in an integrated design which surrounds the head (e.g., 8-, 12- or even 32-channel head coils). Data from the individual coils are integrated by special software to compensate for the nonuniform distribution of the signal-to-noise ratio (SNR) between the peripheral and central parts of the brain. The major advantage of a multichannel, phased-array head coil is that it allows the application of parallel acquisition techniques (PAT), which can be used to speed up MRI. The concept is to reduce the number of phase-encoding steps by switching a field gradient for each phase-encoding step. Skipping, for example, every second phase-encoding line accelerates the acquisition speed by a factor of two. This is called the acceleration or PAT factor. The trade-off for this increased imaging speed is a decrease in SNR. Image reconstruction with PAT techniques is more complicated, and several algorithms have been described, depending on whether image reconstruction takes place before (SMASH, GRAPPA (generalized autocalibrating partially parallel acquisition)) or after (SENSE) Fourier transform of the image data.
Phys.Lett.B461:28,1999 We report on a measurement of hard photons (Eg>30 MeV) in the reaction Ar+Ca
at 180A MeV at an energy in which photons from the decay of pi0 mesons are
dominating. Simultaneous ...measurement with the TAPS spectrometer of the photon
spectrum and photon-photon coincidences used for the identification of pi0
enabled the subtraction of pi0 contribution. The resulting photon spectrum
exhibits an exponential shape with an inverse slope of
E0=(53+-0.03(stat)-5+8(syst)) MeV. The photon multiplicity, equal to
(1.21+-0.03(stat)+0.3-0.2(syst))10E0-2, is roughly one order of magnitude
larger than the value extrapolated from existing systematics. This enhancement
of the hard photon production is attributed to a strong increase in the
contribution of secondary np collisions to the total photon yield. We conclude
that, on average, the number of np collisions which contribute to the hard
photon production is 7 times larger than the number of first chance np
collisions in the reaction Ar+Ca at 180A MeV.
Isotopic yields for light particles and intermediate mass fragments have been measured for 112Sn+112Sn, 112Sn+124Sn, 124Sn+112Sn and 124Sn+124Sn central collisions at E/A=50 MeV and compared with ...predictions of stochastic mean field calculations. These calculations predict a sensitivity of the isotopic distributions to the density dependence of the asymmetry term of the nuclear equation of state. However, the secondary decay of the excited fragments modifies significantly the primary isotopic distributions and these modifications are rather sensitive to theoretical uncertainties in the excitation energies of the hot fragments. The predicted final isotope distributions are narrower than the experimental data and the sensitivity of the predicted yields to the density dependence of the asymmetry term is reduced.
Intracystic carcinoma of the breast Kersschot, E A; Hoste, M V; Dochez, C L ...
RöFo : Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebende Verfahren,
06/1986, Letnik:
144, Številka:
6
Journal Article
Photon energy spectra up to the kinematic limit have been measured in 190 MeV proton reactions with light and heavy nuclei to investigate the influence of the multiple-scattering process on the ...photon production. Relative to the predictions of models based on a quasi-free production mechanism a strong suppression of bremsstrahlung is observed in the low-energy region of the photon spectrum. We attribute this effect to the interference of photon amplitudes due to multiple scattering of nucleons in the nuclear medium.
Thoracic spinal cord herniation and arachnoid cyst van den Hauwe, L; Van Goethem, J W; Goedseels, K ...
JBR-BTR : organe de la Societe royale belge de radiologie (SRBR) = orgaan van de Koninklijke Belgische Vereniging voor Radiologie (KBVR),
2006 May-Jun, Letnik:
89, Številka:
3
Journal Article
Tuberous sclerosis and subependymal giant cell astrocytoma Lambrecht, V; Van Goethem, J W; Ozsarlak, O ...
JBR-BTR : organe de la Societe royale belge de radiologie (SRBR) = orgaan van de Koninklijke Belgische Vereniging voor Radiologie (KBVR),
2005 May-Jun, Letnik:
88, Številka:
3
Journal Article
