Abstract #3193

Development of a transmit gain calibration method using the Bloch-Siegert shift for nonproton hyperpolarized MRI on a preclinical 7T scanner

Collin J. Harlan^1,2, Keith A. Michel^2,3, and James A. Bankson^1,2

¹The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, TX, United States, ²Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, United States, ³Imaging Physics Residency Program, The University of Texas MD Anderson Cancer Center, Houston, TX, United States

Synopsis

Keywords: Hyperpolarized MR (Gas), Hyperpolarized MR (Gas), Transmit Gain Calibration, Bloch-Siegert Shift

Motivation: Transmit gain calibration is necessary for nonproton hyperpolarized MRI to accurately calibrate excitation angles.

Goal(s): To implement a phase-based TG calibration method using the Bloch-Siegert shift for nonproton HP MRI on a preclinical 7T scanner.

Approach: An off-resonance Fermi-shaped Bloch-Siegert pulse follows directly an excitation pulse. Percent difference between our measured Bloch-Siegert TG calibration factors and the validation TG calibration factors for ¹H and ¹³C were calculated.

Results: Our method allows for fast, accurate, and robust TG calibration of preclinical nonproton HP MRI studies with minimal error (<5%) for ¹H and ¹³C.

Impact: This method will facilitate efficient transmit calibration for ¹³C and HP ¹²⁹Xe MRI on a preclinical 7T scanner, where limited bore size and the inability to easily implement a thermal calibration phantom can make ¹²⁹Xe TG calibration a challenge.

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