Abstract #2622

Systematic analysis of relaxometric constant in brain using temperature-dependent relaxometry and susceptibility: Toward 7T chi-separation

Hyeong-Geol Shin^1,2, Yuto Uchida², Javier Redding-Ochoa³, Kengo Onda¹, Sooyeon Ji⁴, Alexander Barrett³, Adnan Bibic⁵, Juan C. Troncoso³, Jiye Kim⁴, Peter van Zijl^1,2, Kenichi Oishi^1,6, and Xu Li²

¹Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States, ²F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, baltimore, MD, United States, ³Department of Pathology, Division of Neuropathology, Johns Hopkins University School of Medicine, Baltimore, MD, United States, ⁴Department of Electrical and Computer Engineering, Seoul National University, Seoul, Korea, Republic of, ⁵F.M. Kirby Research Center for Preclinical Imaging Facility, Kennedy Krieger Institute, baltimore, MD, United States, ⁶The Richman Family Precision Medicine Center of Excellence in Alzheimer's Disease, baltimore, MD, United States

Synopsis

Keywords: Susceptibility/QSM, Susceptibility

Motivation: Important physical parameter, relaxometric constant$$$\;{D_r}$$$, linking magnetic susceptibility to induced transverse relaxation acceleration (i.e.,$$$\;{R2'}$$$) has not yet been fully understood in brain.

Goal(s): To investigate underlying mechanisms affecting relaxometric constant in brain using temperature-dependent relaxometry and susceptibility and explore a better field-strength correction for ultra-high-field MRI.

Approach: 3T and 7T R2*/R2'/quantitative-susceptibility maps were acquired from a post-mortem brain at different temperatures and analyzed based on the physical model.

Results: In human brain, effects of temperature-dependent water susceptibility, water diffusion, and field strength on D_r were observed, and a field-strength correction coefficient was calculated, generating consistent chi-separation maps at both 3T and 7T.

Impact: A better understanding of relaxometric constant in brain can provide better insight on effects of susceptibility sources (e.g., iron and myelin), on MR relaxometry, improving quantification accuracy of those biological substances using MRI.

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