Gadopentetate dimeglumine versus ultrasmall super-paramagnetic iron oxide for dynamic contrast-enhanced MR imaging of tumor angiogenesis in human colon carcinoma in mice

PURPOSE: To compare the kinetic physiologic properties of a clinical contrast agent, gadopentetate dimeglumine, with those of ultrasmall superparamagnetic iron oxide (USPIO) particles for dynamic contrast material-enhanced magnetic resonance (MR) imaging of tumor angiogenesis in human colon carcinoma in mice with a clinical MR imaging unit. MATERIALS AND METHODS: Thirty-two mice with human colon carcinoma were injected with either gadopentetate dimeglumine (n = 16) or USPIO (n = 16) for dynamic contrast-enhanced MR imaging and pre- and postcontrast T2 and T2* measurements. Dynamic contrast-enhanced MR imaging measurements were analyzed by using a two-compartment model to calculate the endothelial transfer coefficient surface area product (K-PS) for the tumor microvasculature, the reflux coefficient (k), and the fractional plasma volume (f(PV)). K-PS, k, and f(PV) maps were compared with histologic microvessel density (MVD) and used to observe differences between core and rim regions of tumor. RESULTS: Results in 30 mice (15 in the gadopentetate dimeglumine group and 15 in the USPIO group) could be used. KPS values measured with both agents correlated well with MVD in hot spots (gadopentetate dimeglumine: r = 0.6, P = .02; USPIO: r = 0:6, P = .01). No significant difference (P = .4) in correlation was found between the two agents. Both USPIO and gadopentetate dimenglumine deomonstrated higher MVD and K-PS values in tumor rim than in tumor core (P < .01). Tumor k values 0.3, P = .4) and USPIO (r = 0.2, P = .6), while f(PV) values correlated well with correlated poorly with whole-tumor MVD for both gadopentetate dimeglumine (r = 0.3, P = .4) and USPIO (r = 0.2,; P = .6), while f(PV) values correlated well with whole-tumor MVD for USPIO (r = 0.6, P = .02) but not gadopentetate dimeglumine (r = -0.01; P = .98). T2 and T2* measurements showed small differences between areas of high and low angiogenic activity with both agents. CONCLUSION: The kinetic physiologic properties of gadopentetate dimeglumine are as good as those of USPIO for dynamic contrast-enhanced MR imaging for calculating K-PS as a measurement of angiogensis in human colon carcinoma. Further studies with patients may reveal whether gadopentetate dimeglumine might be used for this purpose in clinical practice. (C) RSNA, 2003.