Analysis of Gd serum concentrations by EIA. Gd concentrations were determined by two different EIA assays using GdN20 (A) and GdQ13 (B). Bar charts represent mean Gd concentrations [ng/ml] and error bars represent standard errors. Gd concentrations in sera derived from patients with benign and malignant ovarian tumors as measured by GdQ13-EIA are plotted as ROC-curve (C). Statistical significance for all tests was assumed for p < 0.05.