Effects of inversion and saturation times on relationships between contrast agent concentrations and signal intensities of T₁-weighted magnetic resonance images

摘要

The present study was an attempt to investigate the effect of variation of inversion time (T _I) and saturation time (T _S) on the linear relationship between contrast agent concentration and signal intensity (SI) on Turbo Fast Low Angle Shot (TurboFLASH) T ₁-weighted images in MRI. For this purpose, inversion recovery (IR) and saturation recovery (SR) sequences (Center out Phase-Encoding acquisition) were used. A phantom was designed to hold 25 vials which contained either different (between 0 and 19.77 mmol/L) or constant (1.20 mmol/L) concentrations of contrast agent. The vials of constant concentration were used for the measurement of coil non-uniformity, which was normalized to give a correction factor. The vials of different concentrations were used to measure the SI by using different sequences and different T _I and T _S values. To calculate the corrected SI for different concentrations, we multiplied the SI of each vial by its correction factor. The relationships between the corrected SI and the concentration [were evaluated], where the threshold of (R 2 = 0.95 and 0.99) was maintained. This study shows that different sequences and different T _I and T _S values can have an effect on the correlation between the SI and concentration. Regardless of the values of T _I, T _S, and the different IR and SR sequences chosen, the linear relationship between the SI and concentration was about twice that previously reported (i.e., 0.8 mmol/L, R 2 = 0.95).