Bloch simulation of geometric distortion around air bubbles acquired with a 7 T MRI system

Motivation: To reproduce geometric distortions around air bubbles imaged with a 7 Tesla MRI system using Bloch simulation. Goal(s): To find a strategy to calculate geometric distortion caused by susceptibility effects in Bloch simulation. Approach: Inhomogeneous magnetic fields were calculated using summing up magnetic fields generated by magnetic dipoles in the air bubbles in a spherical phantom. Results: Geometric distortions were reproduced by the Bloch simulations using the inhomogeneous magnetic fields calculated by summation of the magnetic fields generated by the magnetic dipoles in the air bubbles. Bubbles deformed by the strong static magnetic field were observed. Impact: Geometric distortion around arbitrary shaped air bubbles was reproduced by the Bloch simulation. An air bubble at 7T was found to be deformed by the strong static magnetic field and the large diamagnetic susceptibility of water.