Abstract
PURPOSE: We sought to investigate the potential of D-maltose, D-sorbitol, and D-mannitol as T(2) exchange magnetic resonance imaging (MRI) contrast agents. We also sought to compare the in vivo pharmacokinetics of D-maltose with D-glucose with dynamic contrast enhancement (DCE) MRI. METHODS: T(1) and T(2) relaxation time constants of the saccharides were measured using eight pH values and nine concentrations. The effect of echo spacing in a multiecho acquisition sequence used for the T(2) measurement was evaluated for all samples. Finally, performances of D-maltose and D-glucose during T(2)-weighted DCE-MRI were compared in vivo. RESULTS: Estimated T(2) relaxivities (r(2)) of D-glucose and D-maltose were highly and nonlinearly dependent on pH and echo spacing, reaching their maximum at pH=7.0 (~0.08mM(−1) s(−1)). The r(2) values of D-sorbitol and D-mannitol were estimated to be ~0.02mM(−1) s(−1) and were invariant to pH and echo spacing for pH ≤7.0. The change in T(2) in tumor and muscle tissues remained constant after administration of D-maltose, whereas the change in T(2) decreased in tumor and muscle after administration of D-glucose. Therefore, D-maltose has a longer time window for T(2)-weighted DCE-MRI in tumors. CONCLUSION: We have demonstrated that D-maltose can be used as a T(2) exchange MRI contrast agent. The larger, sustained T(2)-weighted contrast from D-maltose relative to D-glucose has practical advantages for tumor diagnoses during T(2)-weighted DCE-MRI.