Effect of phase-encoding scheme on the relationship between contrast agent concentration and signal intensity on inversion recovery turbo fast low-angle shot T1-weighted images.

Previous studies have shown that the image parameters such as the repetition time and inversion time (TI) and image sequences can have an effect on the maximum linearity between signal intensity (SI) and concentration. Our aim in this study was to investigate the effect of a phase-encoding scheme (linear phase-encoding and center out phase-encoding) at different TIs on the maximum linear relationship between contrast agent concentration and SI using inversion recovery TurboFLASH (turbo fast low angle shot) T1-weighted images in MRI. 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 measurement of coil non-uniformity. The vials of different concentrations were used for the measurement of the maximum linear relationship between SI and concentration and the effect of a phase-encoding scheme on the linearity, where the squared correlations (R2) between the corrected SI and the concentration were equal to 0.95 and 0.99. The results showed that the linear relationship between SI and concentration was dependent on the phase-encoding scheme and on the TIs. The results also showed that the maximum linearity with the linear phase-encoding acquisition was higher than that with the center out phase-encoding acquisition at the same R2. This study shows that the phase-encoding scheme is an important parameter when the SI is measured. These schemes can have an effect on the maximum linearity between SI and concentration.