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Abstract #1414

Magnetic Field Dependence of 31P Relaxation in Cortical Bone

Alan C. Seifert1, Alexander C. Wright1, Henry H. Ong1, Thomas J. Connick1, Stephen Pickup1, Suzanne L. Wehrli2, Felix W. Wehrli1

1Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States; 2NMR Core Facility, Children's Hospital of Philadelphia, Philadelphia, PA, United States

X-ray-based bone mineral density examinations measure apparent, rather than true, density. Solid-state 31P MRI has the potential to quantify true density, but due to uniquely unfavorable relaxation properties, SNRs dependence on field strength is not certain. We therefore measured T1 and T2* of 31P in five lamb cortical bone samples by saturation-recovery and line width at five field strengths (3T-11.7T), and calculated predicted SNRs using the gradient-echo signal equation. With increasing B0, T1 increased from 26s to 97s, and T2* decreased from 189s to 98s. If k-space center is sampled <130s after excitation, higher field strength should provide better SNR.