SU-D-303-06: Evaluations of Quantified Magnetic Moments From Different MRI Hardware




Our quick study here is to validate whether the quantified magnetic moments of the same object are the same from different MRI machines and rf head coils.


We constructed a gel phantom consisting of an empty straw with a diameter of 2.6-mm, a 3-mm diameter glass bead, and a 5-mm diameter glass bead. We imaged the phantom with a 4 echo gradient echo sequence on a 1.5-T Siemens Sonata and a 3-T Verio. On the 1.5-T, we used a quadrature single-channel birdcage coil and an 8-channel coil. On the 3-T, we used a single channel circular-polarized (CP) receiving coil and a 12-channel coil, which outputs only 4 channels. After removing the background phase with the SHARP method [1], we quantified magnetic moments of the three objects at each echo time for each coil, using the CISSCO method described in [2, 3].


The quantified magnetic moments for each object are consistent among 4 echo times and different hardware. In addition, the quantified values agree with the expected values within uncertainties.


For each of the three objects, we have demonstrated self consistencies of quantified magnetic moments between four different setups at four different echo times, using the CISSCO method. These results support that, with the appropriate post processing procedures and methods applied on images acquired from any MRI hardware or imaging parameters, we should obtain the same magnetic moment of the same object of interest. However, phase images improperly post processed may or may not lead to the correct quantified magnetic moment of the object. Post processing methods such as quantitative susceptibility mapping or combination of phase images from individual rf channels require further studies.

Ref:[1] Schweser et. al, NeuroImage, 2011, pp. 2789–2807. [2] Cheng et. al, MRI, 2015, in press. [3] Cheng et. al, PMB, 2009, pp. 7025–7044.

DOD/USAMRAA W81XWH-12-1-0522