Effect of metallic materials on magnetic resonance image uniformity: a quantitative experimental study

Area of Science:

• Medical Imaging
• Materials Science
• Biomedical Engineering

Background:

• Metallic materials are increasingly used in medical devices, raising concerns about their impact on Magnetic Resonance (MR) imaging.
• Assessing the effect of metallic implants on MR image quality is crucial for accurate diagnosis and treatment planning.

Purpose of the Study:

• To quantitatively evaluate the influence of various metallic materials on MR image uniformity using a standardized methodology.
• To identify specific metallic materials that degrade MR image quality.

Main Methods:

• Six types of 1 cm cubic metallic materials (Au, Ag, Al, Au-Ag-Pd alloy, Ti, Co-Cr alloy) were embedded in a glass phantom.
• Scans were performed using a 1.5-T MR scanner with T1-weighted spin echo (SE) and gradient echo (GRE) sequences, following ASTM F2119-07 standards.
• Image uniformity was measured using the non-uniformity index (NUI).

Main Results:

• Cobalt-chromium (Co-Cr) alloy and titanium (Ti) significantly reduced MR image uniformity, especially in T1-GRE sequences.
• Co-Cr implants caused the most substantial decrease in uniformity, with effects extending up to 6.6 cm.
• Other metallic materials tested (Au, Ag, Al, Au-Ag-Pd alloy) showed no significant impact on image uniformity.

Conclusions:

• MR image uniformity is compromised by the presence of Co-Cr and Ti, influenced by the scanning sequence and coil type.
• The observed image non-uniformity is likely due to the high magnetic susceptibility of Co-Cr and Ti.
• Standardized assessment methods are essential for quantifying the impact of metallic materials on MR imaging.