Design, construction and evaluation of an anthropomorphic head phantom with realistic susceptibility artifacts.

PURPOSE

To design and construct an anthropomorphic head phantom using materials of appropriate magnetic susceptibility and air spaces of realistic dimensions, with the aim of reproducing the susceptibility artifacts found in the human brain.

MATERIALS AND METHODS

The phantom is based on a plastic skull filled with MnCl2-doped water. Materials to mimic soft tissue (wax) and bone (plastic skull) were chosen based on mass susceptibility measurements using a superconducting quantum interference device (SQUID) magnetometer. The phantom was designed for and evaluated at 4.7T using field mapping and echo-planar imaging (EPI).

RESULTS

The main magnetic field (B0) maps of the phantom resemble those of four volunteers' brains and have similar standard deviations (SDs). Maps of the B0 field gradients in the phantom and real brains are also similar. The phantom has relaxation times close to those of brain tissue at 4.7T. Gradient-echo (GE)-EPI images of the phantom suffer from susceptibility artifacts comparable to those in real heads and at anatomically realistic locations.

CONCLUSION

The phantom is a useful tool for evaluating and comparing different susceptibility artifact reduction techniques. The phantom could also be used to test CT-MRI coregistration in the presence of susceptibility artifacts since the water-filled brain cavity is both CT- and MR-visible.