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Abstract #3461

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

Jeong Kon Kim1,2, Ravi Teja Seethamraju3, Ji-Yeon Suh1,2, Gyounggoo Cho4, Woo Hyun Shim2,5, 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.