Investigating the Feasibility of In Vivo Perfusion Imaging Methods for Spinal Cord Using Hyperpolarized [13C]t-Butanol and [13C,15N2]Urea

Purpose This study examined the feasibility of using two novel agents, hyperpolarized [ 13 C]t-butanol and [ 13 C, 15 N 2 ]urea, for assessing in vivo perfusion of the intact spinal cord in rodents. Due to their distinct permeabilities to blood brain barrier (BBB), we hypothesized that [ 13 C]t-butanol and [ 13 C, 15 N 2 ]urea exhibit unique 13 C signal characteristics in the spinal cord. Procedures Dynamic 13 C t-butanol MRI data were acquired from healthy Long-Evans rats using a symmetric, ramp-sampled, partial-Fourier 13 C echo-planar imaging sequence after the injection of hyperpolarized [ 13 C]t-butanol solution. In subsequent scans, dynamic 13 C urea MRI data were acquired after the injection of hyperpolarized [ 13 C, 15 N 2 ]urea. The SNRs of t-butanol and urea were calculated for regions corresponding to spine, supratentorial brain, and blood vessels and plotted over time. Mean peak SNR and AUC were calculated from the dynamic plots for each region and compared between t-butanol and urea. Results In spine and supratentorial brain, the mean peak SNR and AUC of t-butanol were significantly higher than those of urea ( p