Three-dimensional T(1), T(2) and proton density mapping with inversion recovery balanced SSFP.

By combining a balanced steady-state free precession (bSSFP) readout with an initial inversion pulse, all three contrast parameters, T(1), T(2) and proton density (M(0)), may be rapidly calculated from the signal progression in time. However, here it is shown that this technique is quite sensitive to variation in the applied transmit RF (B(1)) field, leading to pronounced errors in calculated values. Two-dimensional (2D) acquisitions are taxed to accurately quantify the relaxation, as the short RF pulses required by SSFP's rapid TR contain a broad spectrum of excitation angles.

New methods in diffusion-weighted and diffusion tensor imaging.

Considerable strides have been made by countless individual researchers in diffusion-weighted imaging (DWI) to push DWI from an experimental tool, limited to a few institutions with specialized instrumentation, to a powerful tool used routinely for diagnostic imaging. The field of DWI constantly evolves, and progress has been made on several fronts. These developments are primarily composed of improved robustness against patient and physiologic motion, increased spatial resolution, new biophysical and tissue models, and new clinical applications for DWI.

Perfusion mapping with multiecho multishot parallel imaging EPI.

Echo-planar imaging (EPI) is the standard technique for dynamic susceptibility-contrast (DSC) perfusion MRI. However, EPI suffers from well-known geometric distortions, which can be reduced by increasing the k-space phase velocity. Moreover, the long echo times (TEs) used in DSC lead to signal saturation of the arterial input signal, and hence to severe quantitation errors in the hemodynamic information.

Identifying systematic errors in quantitative dynamic-susceptibility contrast perfusion imaging by high-resolution multi-echo parallel EPI.

Several obstacles usually confound a straightforward perfusion analysis using dynamic-susceptibility contrast-based magnetic resonance imaging (DSC-MRI). In this work, it became possible to eliminate some of these sources of error by combining a multiple gradient-echo technique with parallel imaging (PI): first, the large dynamic range of tracer concentrations could be covered satisfactorily with multiple echo times (TE) which would otherwise result in overestimation of image magnitude in the presence of noise. Second, any bias from T(1) relaxation could be avoided by fitting to the signal magnitude of multiple TEs.