Enhancement of phase-contrast MR angiography with superparamagnetic iron oxide

The effect of superparamagnetic iron oxide particles (AMI-227) was assessed in three-dimensional (3D) phase-contrast (PC) MR angiography (MRA), with various scanning parameters for raw at 1.5 T. The blood T1 and T2 before and after 20 μmol Fe/kg of AMI-227 injection were measured sequentially at .47 T. The visualization of abdominal aorta, renal artery, inferior vena cave, and portal vein was respectively evaluated before and after AMI-227 injection qualitatively by the four confidence levels and quantitatively by analysis of signal-to-noise ratio (SNR) of vessels. The blood T1 and T2 were sufficiently shortened for at least 1 hour after AMI-227 injection. The visualization of each vessel was improved by AMI-227 at various velocity encoding (VENC) value, suggesting the extended application of PC-MRA in various conditions. The optimal flip angle was increased from 20°to 30°in higher VENC after AMI-227 injection, resulting in higher signal from blood flow. Quantitative analyses showed that the optimal flip angle to achieve the maximum SNR seemed to be 20°in unenhanced images, but the optimal flip angle of the high speed flow was increased by contrast enhancement. The postcontrast PC-MRA provides the increased sensitivity of slow flow components, even with a high VENC gradient. AMI-227 can significantly improve SNR to Mood vessels during 3D-PC-MRA with various scanning parameters.