Determination of in vivo rat muscle Gd-DTPA relaxivity at 6.3 T.

For the in vivo relaxivity of Gd-DTPA at 6.3 T in rat muscle a value of 2.7+/-0.

Influence of the pharmacokinetic model on the quantification of the Gd-DTPA uptake rate in brain tumours using direct T1 measurements.

After a bolus injection of Gd-DTPA, a fast tracer uptake in rat brain tumours was already observed during the tracer bolus passage. For the quantification of the uptake rate constant, pharmacokinetic models are commonly used. For a good quantification, the changes of the plasma tracer concentration directly after the bolus injection must be incorporated into these models as prior knowledge.

Spatially selective RF pulses and the effects of digitization on their performance.

Spectrometers make use of D/A converters to generate RF and gradient shapes. This paper examines by exact simulations the time and amplitude digitization effects, inherent to the use of D/A converters, on the performance of amplitude modulated (AM) frequency selective RF pulses. By making use of Fourier theory and the small tip angle approximation, an approximate model of these effects on the magnetization slice profiles is derived and verified for several pulse types by computer simulations.

Diffusion in red blood cell suspensions: separation of the intracellular and extracellular NMR sodium signal.

It is shown that the signal of intracellular and extracellular sodium of red blood cells can be separated by a difference in diffusion. Comparison with proton diffusion experiments conducted in parallel showed that this difference was caused by restriction to the cell volume. The measured proton and sodium root mean square displacements agreed well with the cell dimensions.

Is the magnetic resonance imaging proton spin-lattice relaxation time a reliable noninvasive parameter of developing liver fibrosis?

During the development of liver fibrosis in rats by an individual dose-titrated CCl4 administration, hepatic proton spin-lattice relaxation time (T1) has been measured in vivo every 2 weeks for 8 weeks. Liver content of collagen, triglycerides and water has been measured biochemically in biopsy material. After 4 weeks of CCl4 treatment, T1 increased significantly and remained at the same level, whereas liver collagen reached its maximum at 8 weeks.