Model simulations and comparative evaluations of susceptibility-based and gadolinium contrast enhancement for high-resolution brain venography

摘要

The MRI signal, in terms of amplitude and phase, was simulated for susceptibility-based brain venography (BV) without and with administration of contrast agent (CA) under standard clinical parameters and field magnitude of 1.5 T (Tesla). Then, in order to compare the enhancement due to CA and that one obtained through susceptibility weighted magnitude image (SWI) processing, exploiting only the intrinsic magnetic susceptibility differences between blood and surrounding tissue, the simulated signal was processed with a well-known phase masking technique to increase signal differences as a function of tissue type, thus generating better image contrast. The simulation was carried out adopting a well-established bi-compartmental model, described by a set of analytical formulas. The based simulated signal was processed with the SWI technique considering a conventional masking procedure available in literature and a different masking method designed and described in our previous work. The resulting enhanced signals in terms of image contrast obtained with these two different phase masking procedures and with the administration of conventional CA were compared. The new designed mask (DM), compared with the conventional one, allows to get better results in terms of image contrast for all blood volume fractions considered in the simulation. Additionally, better results can be obtained also with respect to the case of CA administration only. Results from model simulations demonstrate the effectiveness of masking techniques to improve image contrast regarding all vessel sizes of clinical interest in the high resolution susceptibility-based brain venography possibly avoiding, in some cases, the need for CA administration.