In vivo imaging of human breast cancer mouse model with high level expression of calcium sensing receptor at 3T

Objectives: To demonstrate that manganese can visualise calcium sensing receptor (CaSR)-expressing cells in a human breast cancer murine model, as assessed by clinical 3T magnetic resonance (MR). Methods: Human MDA-MB-231-Luc or MCF7-Luc breast cancer cells were orthotopically grown in NOD/SCID mice to a minimum mass of 5 mm. Mice were evaluated on T1-weighted sequences before and after intravenous injection of MnCl ₂. To block the CaSR-activated Ca ²⁺ channels, verapamil was injected at the tumour site 5 min before Mn ²⁺ administration. CaSR expression in vivo was studied by immunohistochemistry. Results: Contrast enhancement was observed at the tumour periphery 10 min after Mn ²⁺ administration, and further increased up to 40 min. In verapamil-treated mice, no contrast enhancement was observed. CaSR was strongly expressed at the tumour periphery. Conclusion: Manganese enhanced magnetic resonance imaging can visualise CaSR-expressing breast cancer cells in vivo, opening up possibilities for a new MR contrast agent. Key Points : • Manganese contrast agents helped demonstrate breast cancer cells in an animal model. • Enhancement was most marked in cells with high calcium sensing receptor expression. • Manganese uptake was related to the distribution of CaSR within the tumour. • Manganese MRI may become useful to investigate human breast cancer.