3T Renal 23Na-MRI: effects of desmopressin in patients with central diabetes insipidus

The purpose of this prospective study was to assess physiologic changes in the renal corticomedullary Na-23-concentration ([Na-23]) gradient with Na-23-MRI at 3.0T in patients with central diabetes insipidus (CDI) before and after intranasal administration of 20 mu g desmopressin (DDAVP). Four patients with CDI (all male, mean age 60.2 years) were included in this IRB-approved study. For Na-23-imaging, a 3D density adapted, radial GRE-sequence (TE = 0.55 ms; TR = 120 ms; projections = 8,000; spatial resolution = 5 x 5 x 5 mm(3)) was used in combination with a dedicated Na-23-coil and reference phantoms. The corticomedullary [Na-23] gradient (in mmol/L/mm) was calculated pixel-by-pixel along a linear region-of-interest (ROI) spanning from the renal cortex in the direction of the medulla. Mean +/- A SDs of [Na-23] were calculated for each patient as well as for the entire group. Mean [Na-23] increased along the corticomedullary gradient from the cortex (pre-DDAVP 38.0 +/- A 6.3 mmol/L vs. post-DDAVP 30.7 +/- A 3.5 mmol/L) to the medulla (pre-DDAVP 71.6 +/- A 14.8 mmol/L vs. post-DDAVP 59.7 +/- A 10.8 mmol/L). The overall mean decrease of [Na-23] after DDAVP administration was 17.1 +/- A 1.1 %. Na-23-MRI with state-of-the-art techniques at 3T depicts the physiologic renal response to the administration of desmopressin in patients with central diabetes insipidus.