Positive contrast visualization of nitinol devices using susceptibility gradient mapping.

Area of Science:

• Medical Imaging
• Materials Science
• Biomedical Engineering

Background:

• Traditional MRI visualization of nitinol devices relies on signal loss from T(2)* effects.
• Local susceptibility differences in nitinol cause signal dropout, hindering clear visualization.
• Positive contrast imaging for nitinol devices remains a challenge in MRI.

Purpose of the Study:

• To adapt a postprocessing method for positive contrast MRI visualization of nitinol devices.
• To map induced susceptibility gradients for enhanced device imaging.
• To demonstrate the effectiveness of the new method on nitinol implants.

Main Methods:

• Adapted a postprocessing technique using regular gradient-echo MR images.
• Mapped k-space shifts via Fourier analysis and center-of-mass calculation.
• Generated quantitative maps of local susceptibility gradients for contrast.

Main Results:

• Successfully generated positive contrast images of nitinol devices.
• The method maps susceptibility gradients, creating device contrast against a noise-only background.
• Positive signal response is dependent on the selected voxel neighborhood size.

Conclusions:

• The adapted postprocessing method enables positive contrast MRI visualization of nitinol devices.
• This technique overcomes limitations of traditional signal loss-based MRI.
• The method offers improved imaging for nitinol implants like wires and stents.