Assessment of T1 and T2 relaxation times of deuterium (2H) labeled resonances in the human liver and kidney using k-space reordered 3D concentric ring trajectory sampling at 7T.

OBJECTIVE

Deuterium metabolic imaging (DMI) is an emerging MR technique providing non-invasive insights into glucose metabolism. Reliable concentration estimation depends on knowledge of tissue specific relaxation times. This study reports T₁ and T₂ relaxation time constants of deuterium-labeled water (HDO) and glucose (Glc) from the human liver and kidney at 7T.

MATERIALS AND

METHODS

Twelve healthy volunteers (6f/6 m) were examined using k-space-reordered inversion-recovery and spin-echo DMI with non-Cartesian concentric-ring trajectory (CRT) sampling. Seven volunteers underwent oral 2H-Glc (0.8 g/kg body weight) administration. Data were averaged over organ-specific masks before spectral fitting. One volunteer was measured after oral D₂O (0.5 ml/kg body weight) administration.

RESULTS

Faster longitudinal relaxation but similar transversal relaxation were observed for 2H-labeled Glc in the liver compared to kidney tissue (T₁liver/kidney = 60 ± 4 ms/85 ± 18 ms, p = 0.016; T₂liver/kidney = 31 ± 6 ms/35 ± 2 ms, p = 0.283). HDO exhibited significantly shorter liver relaxation times (T1liver/kidney = 218 ± 24 ms/324 ± 34 ms, p < 0.001; T₂liver/kidney = 28 ± 4 ms/39 ± 6 ms, p < 0.001). D₂O loading improved voxelwise SNR enabling renal T₁/T₂ mapping of HDO.

DISCUSSION: Hepatic and renal glucose homeostasis is often impaired in several pathophysiological conditions such as tumors, diabetes and metabolic dysfunction-associated steatotic liver disease. Using organ-specific 2H relaxation times increases the accuracy of concentration estimation and can help to improve the understanding of underlying metabolic processes in future abdominal DMI studies, which can help to push abdominal DMI towards clinical application.