Water signal attenuation by D2O infusion as a novel contrast mechanism for 1H perfusion MRI

Deuterium oxide (D2 O), which is commercially available and nonradioactive, was proposed as a perfusion tracer before the clinical usage of conventional gadolinium-based MRI contrast agents. However, the sensitivity of direct deuterium detection is the major challenge for its application. In this study, we propose a contrast-enhanced strategy to indirectly trace administered D2 O by monitoring the signal attenuation of (1) H MRI. Experiments on D2 O concentration phantoms and in vivo rat brains were conducted to prove the concept of the proposed contrast mechanism. An average maximum signal drop ratio of 5.25 ± 0.91% was detected on (1) H MR images of rat brains with 2 mL of D2 O administered per 100 g of body weight. As a diffusible tracer for perfusion, D2 O infusion is a practicable method for the assessment of tissue perfusion and has the potential to provide different information from gadolinium-based contrast agents, which have limited permeability for blood vessels. Furthermore, the observed negative relaxivities of D2 O reveal the (1) H-D exchange effect. Therefore, applications of perfusion MRI with D2 O as a contrast agent are worthy of further investigation.