Advanced approaches to imaging primary breast cancer: an update

Abstract

Breast cancer (BC) is the most common cancer in women. Early detection of BC plays an important role in preventing advanced disease and improving survival. In this article, we aim to describe both advantages and limitations of conventional and new BC-imaging modalities. A literature search was performed for the period of January 2013 through October 2018, using search engines such as PubMed, PMC, and Google scholar. Search topics included: “breast cancer”, “breast lesion”, and “breast tumor imaging, diagnosis, and detection”. A total of 143 papers which primarily addressed imaging efficacy issues are included in the review. Mammography is the oldest and most commonly utilized screening modality for BC. Ultrasonography (US), computed tomography (CT), magnetic resonance imaging (MRI), positron emission mammography (PEM), and positron emission tomography/computed tomography (PET/CT) are the other conventional BC-imaging modalities. To overcome certain weaknesses of these modalities, new imaging tools including contrast-enhanced spectral mammography (CSEM), digital breast tomosynthesis (DBT), multiparametric (MP)-MRI, microwave imaging, and PET/MRI have been investigated. Conventional BC-imaging modalities have both advantages and limitations. When utilized in combination, they are often complementary. For example, a limitation of mammography is low sensitivity in dense breasts. The addition of DBT lessens this limitation by providing three-dimensional (3D) images of the breast that minimizes the effect of overlying breast tissue. Additionally, US added to mammography in dense breasts increases screening sensitivity and has the advantages of accessibility and lack of ionizing radiation. MRI is currently the most sensitive method used for detecting BC. When MRI is not suitable for patients, such as those with prosthesis, dedicated breast CT can be used. Scintimammography is another alternative method, although not commonly performed due to low sensitivity in < 1 cm tumors. Breast-specific gamma imaging (BSGI), on the other hand, can detect breast tumor < 1 cm; however, effective radiation dose is higher than mammography. PEM, with its high resolution, has been developed to image small breast tumors. PET/CT and PET/MRI have also been used to detect BC. Despite complementary roles of conventional imaging techniques, none of them have addressed all issues in BC diagnosis. Research studies developing novel target-specific molecular imaging agents are in progress with hopes to fill gaps in currently available imaging technologies.