Abstract #3547

Effect of Static Background Gradients on Diffusion Contrast Near Large Metallic Implants

Philip Kenneth Lee^1,2, Daehyun Yoon², and Brian Andrew Hargreaves^1,2,3

¹Electrical Engineering, Stanford University, Stanford, CA, United States, ²Radiology, Stanford University, Stanford, CA, United States, ³Bioengineering, Stanford University, Stanford, CA, United States

Synopsis

Metallic implants create severe off-resonance adjacent to the implant, in the range of 2-20 kHz at 3T. The off-resonance pattern creates a static, “always on” background gradient with unknown amplitude and polarity. Static non-linear background gradients are a known source of local encoding errors, but their effect on diffusion contrast near implants has not yet been evaluated. Static background gradients are distinct from diffusion gradient non-linearities, which affect the achieved b-value if sufficiently large. We apply theoretical results and phantom experiments to evaluate two different diffusion encoding schemes and evaluate the effect of metal-induced off-resonance on ADC quantification.

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