Numerical simulation of the b-SSFP sequence in MR perfusion-weighted imaging of the kidney

Magnetic resonance (MR) simulation is one of the possible approaches to test and develop new imaging protocols. It can assist in fast, on-demand verification of various hypotheses concerning the impact of different physical and/or technical factors on image appearance. In this paper, we perform numerical simulation of dynamic contrast-enhanced MR imaging. In particular, we present the implementation of the so-called balanced steady state free precession sequence and show its application in the synthesis of DCE-MR images mimicking perfusion-weighted examinations of the kidney. To this end, we designed a simplified digital phantom of renal parenchyma comprising of kidney cortex and medulla. The phantom was constructed based on manual segmentation of a real high-resolution CT image of the abdomen. The contrast agent kinetics was incorporated into the model by assigning time-varying $T_{1}$ relaxation time to the kidney tissue segments. The relevant T1 time courses were determined based on analysis of real DCE-MR studies. Eventually, the practical aspects of the designed simulator are illustrated in an example application, where selected image-derived perfusion characteristics are referred to physiological parameters of the kidney.