Three-dimensional saltwater-freshwater fingering in porous media: contrast agent MRI as basis for numerical simulations.

This study investigated miscible fingering phenomena in a saturated porous medium due solely to fluid density differences. The objective was to determine dissolved salt concentrations in the porous medium and, thus, local fluid density with high temporal resolution and covering substantial volume. A magnetic resonance imaging method, which can achieve this goal by adding Cu(II)SO(4) to salt solutions, has been developed.

Accelerated tagging for the assessment of left ventricular myocardial contraction under physical stress.

A TFEPI-CSPAMM sequence is introduced, which is optimized with respect to acquisition speed and image quality. The sequence is used in a stress study, where a short breath-hold duration is crucial, and tested for reproducibility of deformation parameters extracted by HARP for repeated measurements.

Spiral MR myocardial tagging.

In the present study, complementary spatial modulation of magnetization (CSPAMM) myocardial tagging was extended with an interleaved spiral imaging sequence. The use of a spiral sequence enables the acquisition of grid-tagged images with a tagline distance as low as 4 mm in a single breath-hold. Alternatively, a high temporal resolution of 77 frames per second was obtained with 8-mm grid spacing.

RingTag: ring-shaped tagging for myocardial centerline assessment.

Rationale And Objectives: Although endocardial ejection indexes lead to overestimation of contractility in hypertrophied hearts, circumferential fiber shortening at the mid wall (cFS) is less affected by wall thickness. In this study magnetic resonance tagging is exploited to assess directly cFS in normal and hypertrophied hearts.

Methods: A novel tagging procedure generates freely definable, convex ring saturation bands.

Myocardial tagging with 3D-CSPAMM.

Purpose: To introduce a true three-dimensional (3D) tagging technique for the assessment of myocardial tissue motion.

Materials And Methods: To generate a 3D tagging grid, a complementary spatial modulation of magnetization (CSPAMM) was applied in three spatial directions. Imaging was performed using a conventional fast 3D gradient-echo sequence.