Room: Exhibit Hall | Forum 8
Purpose: The bias of phase, magnetic moment, or susceptibility of an object in MRI images acquired by multi-channel rf coil with parallel imaging technique is relatively unexplored. This investigation may provide the degree of accuracy in quantitative biomarkers using parallel imaging technique.
Methods: We prepared a gel phantom including a Gd-DTPA straw. The phantom was imaged in a multi-channel rf coil and a quadrature coil in the multi-echo gradient echo sequence at 3T. There were three conditions in the acquisition setup. One was acquired by the quadrature coil. The other was acquired by the multi-channel coil without acceleration (Acc. 1). Another was acquired by the multi-channel coil with the acceleration factor two (Acc. 2). We used GRAPPA as parallel imaging technique. The magnetic moment of each object was quantified by CISSCO method. In addition, we analyzed the averaged phase of the sagittal sinus and magnetic moment of one vein in human brain in Acc. 1 and Acc. 2.
Results: For phantom study, the magnetic moment, and susceptibility results agreed with the expected values, and were consistent between the quadrature coil, Acc. 1, and Acc. 2. The phase inside the straw also agreed with the expected value in three conditions. For human images, the phase value of the sagittal sinus in Acc. 1 was consistent with that in Acc. 2. The magnetic moment of a vein in Acc. 1 also agreed with that in Acc. 2. However, the phase inside the vein was not consistent between Acc. 1 and Acc. 2.
Conclusion: Phase values in phantom and sagittal sinus in the preliminary study may not be affected by using the multi-channel coil with GRAPPA. The magnetic moment of this Gd-DTPA straw and the cerebral vein would not be affected by using GRAPPA,either. However, the phase in veins may need further investigation!