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

Abstract

Deuterium oxide (D2O), 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 D2O by monitoring the signal attenuation of 1H MRI. Experiments on D2O 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 1H MR images of rat brains with 2 mL of D2O administered per 100 g of body weight. As a diffusible tracer for perfusion, D2O 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 D2O reveal the 1H-D exchange effect. Therefore, applications of perfusion MRI with D2O as a contrast agent are worthy of further investigation. © 2013 John Wiley & Sons, Ltd.