Respiratory self-gated multiple gradient recalled echo sequence for free-breathing abdominal R2* mapping.

Abdominal effective transverse relaxation rate (R(2)*) mapping is critical for a wide range of applications. However, respiratory motion can lead to significant image quality deterioration and R(2)* overestimation. For this work, we explored the feasibility of combining respiratory self-gating techniques with a multiple gradient-recalled echo sequence for free-breathing abdominal R(2)* measurements. In a series of eight normal volunteers, respiratory self-gated-multiple gradient-recalled echo methods effectively avoided motion artifacts to produce quantitative R(2)* measurements in liver, spleen, and kidneys that were comparable to R(2)* measurements produced while breath-holding. Respiratory self-gated-multiple gradient-recalled echo methods demonstrated the potential to avoid the need for breath-holding during abdominal R(2)* mapping. For clinical application, respiratory self-gated-multiple gradient-recalled echo approaches could be particularly useful for R(2)* measurements in those patients unable or unwilling to sustain sufficiently long breath-holds to avoid motion artifacts.