Quantitative ²³Na magnetic resonance imaging in the abdomen at 3 T

To assess the feasibility of sodium-23 MRI for performing quantitative and non-invasive measurements of total sodium concentration (TSC) and relaxation in a variety of abdominal organs.

Proton and sodium imaging of the abdomen was performed in 19 healthy volunteers using a 3D cones sequence and a sodium-tuned 4-rung transmit/receive body coil on a clinical 3 T system. The effects of B₁ non-uniformity on TSC measurements were corrected using the double-angle method. The long-component of ²³Na T₂* relaxation time was measured using a series of variable echo-times.

The mean and standard deviation of TSC and long-component ²³Na T₂* values were calculated across the healthy volunteer group in the kidneys, cerebrospinal fluid (CSF), liver, gallbladder, spleen, aorta, and inferior vena cava.

Mean TSC values in the kidneys, liver, and spleen were similar to those reported using ²³Na-MRI previously in the literature. Measurements in the CSF and gallbladder were lower, potentially due to the reduced spatial resolution achievable in a clinically acceptable scan time. Mean long-component ²³Na T₂* values were consistent with previous reports from the kidneys and CSF. Intra-population standard error was larger in smaller, fluid-filled structures due to fluid motion and partial volume effects.