Magnetic resonance imaging for characterisation of a chick embryo model of cancer cell metastases

Background Metastasis is the most common cause of death for cancer patients, hence its study has rapidly expanded over the past few years. To fully understand all the steps involved in metastatic dissemination, in vivo models are required, of which murine ones are the most common. Therefore pre-clinical imaging methods have mainly been developed for small mammals. However, the potential of preclinical imaging techniques such as magnetic resonance imaging (MRI) to monitor cancer growth and metastasis in non-mammalian in vivo models is not commonly used. We have here used MRI to measure primary neuroblastoma tumour size and presence of metastatic dissemination in a chick embryo model. We compared its sensitivity and accuracy to end-point fluorescence detection.

Methods Human neuroblastoma cells were labelled with GFP and micron-sized iron particles (MPIOs) and implanted on the extraembryonic chorioallantoic membrane of the chick embryo at E7. T2 RARE, T2 weighted FLASH as well as time-of-flight MR angiography imaging was applied at E14. Primary tumours as well as metastatic deposits in the chick embryo were dissected post imaging to compare with MRI results.

Results MPIO labelling of neuroblastoma cells allowed in ovo observation of the primary tumour and tumour volume measurement non-invasively over time. Moreover, T₂ weighted and FLASH imaging permitted the detection of very small metastatic deposits in the chick embryo.

Conclusions The use of contrast agents enabled the detection of metastatic deposits of neuroblastoma cells in a chick embryo model, thereby reinforcing the potential of this cost efficient and convenient, 3R compliant, in vivo model for cancer research.