Optimal Concentrations of Contrast Agent Gadobutrol in T1-Weighted Magnetic Resonance Imaging

The aim of this study was to investigate the optimal concentrations of gadobutrol which the maximum contrast-to noise ratio (CNR) are achieved in magnetic resonance (MR) T₁-weighted (T1W) images from both phantom measurements and simulation. A phantom made of 21 test tubes with various concentrations of gadobutrol (0-160 mM) was investigated. All the studies were performed on a 1.5 T clinical whole-body scanner. Three T1W pulse sequences including two dimensional spoiled gradient echo (2DSPGR), three dimensional fast spoiled gradient echo (3DFSPGR) and conventional spin echo (CSE) were used to obtain T1W images. CNR values were calculated from regions of interest (ROI) of each tube and the optimal concentrations for each pulse sequence were determined. The T₁ and T₂ values of the phantom were also measured to obtain the relaxivity values (r₁ and r₂). Then, the optimal concentrations for each pulse sequence could be simulated by using the r₁ and r₂ values. The results showed that the measured optimal concentrations for 2DSPGR, 3DFSPGR and CSE were 10, 20 and 2.5 mM, respectively. The r₁ and r₂ values of the gadobutrol phantom are 4.13 and 5.7 mM^-1s^-1, respectively. The optimal concentrations by computer simulation are 13.5, 22.8 and 2.0 mM for 2DSPGR 3DFSPGR and CSE respectively, which are in good agreement with the phantom measurements.