Inflow effect of Signal Intensity for the Centre out Phase-Encoding and Linear Phase-Encoding Acquisitions on Inversion Recovery T1-weighted TurboFLASH images

Two common acquisition strategies in MRI are Centre out Phase-Encoding (COPE) and Linear Phase-Encoding (LPE). The objectives of this study were to (1) to investigate the effect of concentrations (0.8 and 1.2mmol/L) and different velocities on signal intensity (SI) strength, (2) to find the inflow effect at different velocities at the two concentrations using the LPE and COPE acquisitions, and (3) to recommend the best acquisition for measuring perfusion with MRI using inversion recovery T1-weighted images. A flow phantom was designed to produce four different steady state flows at the same time. The stationary state can be obtained when the water flow was stopped. All studies were carried out using a 1.5T clinical MR scanner. Mean SI was obtained in ROIs. The inflow correction factor can be calculated from the SI of the steady state flow divided by the SI of the stationary state at the same position in the image. The results show that an increase in concentration and the velocity is associated with increase in the inflow correction factor for the both acquisitions. But the inflow has less effect on SI with the COPE than the LPE acquisition. In addition, the correction value depends on concentration. For measuring the absolute perfusion, the velocity and concentration of contrast agent of the arterial input function should be known to find the inflow correction factor using the two acquisitions. Otherwise, the COPE is the better acquisition for measuring perfusion, because inflow has less effect on SI.