Deuterium brain imaging at 7T during D₂ O dosing

To characterize the (² H) deuterium MR signal measured from human brain at 7T in participants loading with D₂ O to ˜1.5% enrichment over a six-week period.

² H spectroscopy and imaging measurements were used to track the time-course of ² H enrichment within the brain during the initial eight-hour loading period in two participants. Multi-echo gradient echo (MEGE) images were acquired at a range of TR values from four participants during the steady-state loading period and used for mapping ² H T₁ and T₂ ^* relaxation times. Co-registration to higher resolution ¹ H images allowed T₁ and T₂ ^* relaxation times of deuterium in HDO in cerebrospinal fluid (CSF), gray matter (GM), and white matter (WM) to be estimated.

² H concentrations measured during the eight-hour loading were consistent with values estimated from cumulative D₂ O dose and body mass. Signal changes measured from three different regions of the brain during loading showed similar time-courses. After summing over echoes, gradient echo brain images acquired in 7.5 minutes with a voxel volume of 0.36 ml showed an SNR of ˜16 in subjects loaded to 1.5%. T₁ -values for deuterium in HDO were significantly shorter than corresponding values for ¹ H in H₂ O, while T₂ ^* values were similar. ² H relaxation times in CSF were significantly longer than in GM or WM.

Deuterium MR Measurements at 7T were used to track the increase in concentration of ² H in brain during heavy water loading. ² H T₁ and T₂ ^* relaxation times from water in GM, WM, and CSF are reported.