A quantitative study of the pixel-shifting, blurring and nonlinear distortions in MRI images caused by the presence of metal implants

Magnetic resonance imaging has found an increasing number of medical applic ations in recent rears due to its technical merits as well as its non-invas ive nature. However, ifs full potential has been severely limited by magnet ic susceptibility difference artefacts caused by the presence of ferromagne tic sources such as orthopedic implants, dental work or metallic needles us ed in neurosurgery. In this study, we propose a method to numerically quant ify the distortions resulting from the magnetic susceptibility differences by investigating the phenomena from three perspectives: (1) pixel displacem ent, (2) blurring and (3) nonlinearity. For this purpose, phantom images ob tained from a magnetic resonance scanner were studied. Attempts made to rec onstruct an ideal image from ifs distorted version by appropriately compens ating for the three types of distortions yielded encouraging results.