Characterization of D-maltose as a T2 -exchange contrast agent for dynamic contrast-enhanced MRI.

OBJECTIVE

We sought to investigate the potential of D-maltose, D-sorbitol, and D-mannitol as T2 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

T1 and T2 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 T2 measurement was evaluated for all samples. Finally, performances of D-maltose and D-glucose during T2 -weighted DCE-MRI were compared in vivo.

RESULTS

Estimated T2 relaxivities (r2 ) of D-glucose and D-maltose were highly and nonlinearly dependent on pH and echo spacing, reaching their maximum at pH = 7.0 (∼0.08 mM-1 s-1 ). The r2 values of D-sorbitol and D-mannitol were estimated to be ∼0.02 mM-1 s-1 and were invariant to pH and echo spacing for pH ≤7.0. The change in T2 in tumor and muscle tissues remained constant after administration of D-maltose, whereas the change in T2 decreased in tumor and muscle after administration of D-glucose. Therefore, D-maltose has a longer time window for T2 -weighted DCE-MRI in tumors.

CONCLUSIONS

We have demonstrated that D-maltose can be used as a T2 exchange MRI contrast agent. The larger, sustained T2 -weighted contrast from D-maltose relative to D-glucose has practical advantages for tumor diagnoses during T2 -weighted DCE-MRI. Magn Reson Med 80:1158-1164, 2018. © 2018 International Society for Magnetic Resonance in Medicine.