Table 1 A summary of the MRI features of common breast entities during pregnancy and lactation

Galactocele

Non-fat-suppressed T1-weighted and fat-suppressed T2-weighted images could determine the diagnosis among lactating patients with a cystic lesion including a thin septa, heterogeneous content, and fat-fluid level

Lactating adenoma

Morphology-wise resembles a fibroadenoma-like lesion; a well circumscribed mass, containing hypointense septa, causing mass effect on adjacent parenchyma and the main galactiferous ducts of the NAC

On DCE, a benign kinetic curve of persistent enhancement may appear

Fibroadenoma

Morphology-wise, usually exhibits a benign shape on unenhanced sequences, including a sharp contour without signs of infiltration

On DCE, typically exhibits benign patterns of a persistent kinetic curve

Duct-ectasia

Fat-suppressed T1 and T2-weighted images may display an enlarged ductal structure, depending on if its content is composed of protein or fluids, respectively

A unilateral duct dilatation may be an indicator of malignancy and could enhance on DCE, therefore requiring a further diagnostic work-up

Mastitis and Abscess

MRI is not indicated during acute mastitis; however, if symptoms persist despite optimal treatment, MRI may be performed to rule out an inflammatory breast cancer

On DCE these two differentials may exhibit an overlapping suspicious features, thus clinical correlation and tissue sampling may be indicated

PABC

During pregnancy—unenhanced DWI/DTI could determine the diagnosis

During lactation—DCE is of value, despite BPE limitations. DWI/DTI can improve tumor conspicuity. Hypo-intensity on T2 weighted images can assist in delineation of NME lesion, like DCIS

Post-weaning—BPE drops, and DCE utility returns to optimum