Gadolinium-DTPA enhanced MRI demonstrates uterine vascular changes associated with artificially induced decidualization and ovoimplantation in rats

Gadolinium‐DTPA enhanced magnetic resonance (MR) imaging has been used to demonstrate uterine vascular changes during ovoimplantation and artificially induced decidualization in rats. Evans blue dye and Gd‐DTPA were injected i.v. into rats 10 h after unilateral decidualization was induced by injection of sesame oil into the lumen of one uterine horn. Animals were killed various times later and uteri were removed, T1‐weighted proton imaging was performed, and mean image intensities for stimulated and control uterine horns were calculated by computer‐assisted image analysis. Macroscopic bluing confined to stimulated horns was apparent 5 min after tracer injection and increased in intensity until the experiment was terminated at 320 min. Analysis of MR images showed that mean image intensity of control horns did not change significantly at any time after injection of the Gd‐DTPA and Evans blue whereas mean image intensity of stimulated horns increased significantly by 5 min after injection, peaked at 20 min, and returned to values not different from controls by 320 min. T1‐weighted images of day 6 pregnant rats injected with Gd‐DTPA and Evans blue revealed patterns of image enhancement that matched those of macroscopic bluing. Uterine concentrations of radioactivity after injection of 153Gd‐DTPA indicated that increased extracellular fluid volume (ECFV) produces the image enhancement of stimulated horns since the tracer permeates the extracellular fluid of both horns. Gd‐DTPA‐enhanced MR imaging of uteri after deciduogenic stimulation revealed significant image enhancement for stimulated horns at both 9 and 27 h after stimulation. We conclude that Gd‐DTPA enhanced MR imaging allows the identification of uterine vascular changes during ovoimplantation and decidualization and that this methodology may be useful in both experimental and clinical settings.