Magnetic Resonance Imaging of the Whole Body, Including Diffusion, in the Medical Evaluation of Breast Cancers at High Risk for Metastasis and the Follow-up of Metastatic Cancers

Whole-body MRI including diffusion is a booming technique. Numerous studies have demonstrated its interest in metastatic cancers.

Breast cancers, especially hormone-sensitive ones, are very osteophilic and bones are the most frequent metastatic site. Other sites include the lungs, liver, pleura, distant lymph nodes, soft tissue and the central nervous system.

Metastasis are located exclusively in the bones in 30% of the cases. The most commonly affected bones include the axial skeleton, rich in hematopoietic bone marrow : column, pelvis, skull, ribs, clavicles, the proximal part of the femur and humerus. Five percent of breast cancers are directly metastatic and 20 to 30% of localized breast cancers progress to metastatic stage. This potentially affects a large number of patients, with a median survival of 30 to 36 months.Patients with bone metastases only have a better survival rate than others: 20% at 5 years. It is therefore important to use a reliable and reproducible examination for the monitoring of treatment response.

Apart from morphological criteria (lesion size and RECIST criteria), MRI provides quantitative functional criteria (diffusion and ADC values). According to a recent study, whole body MRI is as good as PET/CT and more effective than bone scintigraphy for the diagnosis of bone metastases for cancers of breast and prostate with a high metastatic risk. However, this is a preliminary study with a limited and heterogeneous cohort of patients.

Therefore, it seems appropriate to study the performance of whole body MRI in the pre-therapeutic assessment of breast cancer with a high risk for metastasis and the monitoring of metastatic breast cancer.