Abstract #3461

R1 & R2* Changes According to Gd Concentration: A Potential Limiting Factor in Converting MR Signal Intensity to Gd Concentration

Jeong Kon Kim^1,2, Ravi Teja Seethamraju³, Ji-Yeon Suh^1,2, Gyounggoo Cho⁴, Woo Hyun Shim^2,5, Young Ro Kim²

¹Department of Radiology, Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea, Republic of; ²Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, MA, United States; ³SIEMENS Medical Solutions USA, Inc, Boston, MA, United States; ⁴MRI Team, Korea Basic Science Institute; ⁵Bio & Brain, Korea Advanced Institute of Science & Technology

When 0.1 mol/kg of Gd is injected, plasma concentration of Gd ranges from 2.83 to 12.64 mM according to the time sequence. In our phantom study, R1 reached plateau at approximately 7.5 mM and R2* exponentially increased with increasing Gd concentration. Therefore, R2* effect becomes dominant over R1 effect at high Gd concentration, such as 7.5 mM or greater. These patterns of R1 and R2* changes may limit conventional methods converting MR signal intensity to Gd concentration, particularly in measuring arterial input function, as they consider that delta R1 is linearly proportional to Gd concentration and R2* effect is negligible.