Expectation maximization reconstruction of positron emission tomography images using anatomical magnetic resonance information.

Using statistical methods the reconstruction of positron emission tomography (PET) images can be improved by high-resolution anatomical information obtained from magnetic resonance (MR) images. We implemented two approaches that utilize MR data for PET reconstruction. The anatomical MR information is modeled as a priori distribution of the PET image and combined with the distribution of the measured PET data to generate the a posteriori function from which the expectation maximization (EM)-type algorithm with a maximum a posteriori (MAP) estimator is derived.

Determination of lattice and grain boundary diffusion coefficients in protective alumina scales on high temperature alloys using SEM, TEM and SIMS.

Grain and grain boundary diffusion coefficients in alumina scales on FeCrAl-based ODS alloys have been determined. The boundary diffusion-coefficients have been derived by combining gravimetrically determined growth rate data with SEM and TEM analyses of the oxide scale microstructure. The diffusion coefficients determined have been used as input parameters for a computer model describing the oxygen isotope exchange between grain and grain boundary in the alumina scale which forms during a two-stage oxidation using (18)O-tracers.

A serial read-out scheme for SQUID systems.

A serial read-out scheme for multichannel SQUID systems is discussed, which can decrease the expense of electronic components needed for conventional multichannel systems. In case of RF SQUID systems, this scheme allows the use of only one transmission line between all SQUIDs and the room temperature electronics, thus decreasing helium losses caused by heat transport through electrical wires. Additionally, part of the read-out electronics can be shared by all channels.

Cerebral metabolism of L-[2-18F]fluorotyrosine, a new PET tracer of protein synthesis.

L-[2-18F]fluorotyrosine (2-18FTyr) was evaluated as a tracer of cerebral protein synthesis for positron emission tomography (PET). Its metabolism in murine cerebrum was studied. The uptake in brain reaches a value of approximately 2% of the injected dose per gram tissue after 60 min.