MRI ductography of contrast agent distribution and leakage in normal mouse mammary ducts and ducts with in situ cancer

High resolution 3D MRI was used to study contrast agent distribution and leakage in normal mouse mammary glands and glands containing in situ cancer after intra-ductal injection. Five female FVB/N mice (~ 19 weeks old) with no detectable mammary cancer and eight C3(1) SV40 Tag virgin female mice (~ 15 weeks old) with extensive in situ cancer were studied. A 34G, 45° tip Hamilton needle with a 25μL Hamilton syringe was inserted into the tip of the nipple and approximately 15 μL of a Gadodiamide was injected slowly over 1 min into the nipple and throughout the duct on one side of the inguinal gland. Following injection, the mouse was placed in a 9.4 T MRI scanner, and a series of high resolution 3D T1-weighted images was acquired with a temporal resolution of 9.1 min to follow contrast agent leakage from the ducts. The first image was acquired at about 12 min after injection. Ductal enhancement regions detected in images acquired between 12 and 21 min after contrast agent injection was five times smaller in SV40 mouse mammary ducts (p < 0.001) than in non-cancerous FVB/N mouse mammary ducts, perhaps due to rapid washout of contrast agent from the SV40 ducts. The contrast agent washout rate measured between 12 min and 90 min after injection was ~ 20% faster (p < 0.004) in SV40 mammary ducts than in FVB/N mammary ducts. These results may be due to higher permeability of the SV40 ducts, likely due to the presence of in situ cancers. Therefore, increased permeability of ducts may indicate early stage breast cancers.