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

ABSTRACT

OBJECTIVES: 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. MATERIALS AND METHODS: 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. RESULTS: 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. DISCUSSION: 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.