ARRS 2022 Abstracts


E1996. Breast Imaging as Seen on CT: A Pictorial Review of Breast Pathology Incidentally Detected on Chest Computed Tomography
  1. Stephany Barreto; University of California, San Francisco
  2. Bonnie Joe; University of California, San Francisco
  3. Elissa Price; University of California, San Francisco
  4. Kimberly Ray; University of California, San Francisco
On a routine chest CT, incidentally discovered breast lesions are common and lead to breast clinic referrals. Although chest CT is not a primary method for evaluating breast pathology, CT does offer a larger field of view, superior contrast, and cross-sectional capability as compared to mammography. As such, valuable information can be obtained from CT features of breast lesions, leading to discovery and aiding in management (i.e., CT guidance in axillary lymph node localization). Breast pathology seen on chest CT include benign breast calcifications, benign and malignant breast masses, postoperative changes, and axillary lymphadenopathy. The purpose of this pictorial review is to present incidentally detected breast lesions from routine chest CT in conjunction with a literature review of the significance of these findings.

Educational Goals / Teaching Points
The goals of this exhibit are to review CT anatomy of the chest wall (i.e., lymph node levels) and typical lymphatic drainage patterns of breast cancer; demonstrate findings of breast and associated pathologies (i.e., primary and recurrent breast cancer, axillary metastasis, postoperative changes) on chest CT scans and discuss CT descriptors of lesions; depict non-breast related pathologies seen on chest CT scans in the breast region (i.e., bilateral or unilateral lymphadenopathy associated with systemic or non-breast related causes); and present data on malignant versus benign features of breast lesions on chest CT scans.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
A practicing radiologist must be familiar with suspicious appearance of breast lesions on CT scans. Studies have shown that incidental breast lesions detected on chest CT scans with non-circumscribed spiculated margins and an irregular shape were more likely associated with malignancy. Calcifications and increasing age were not significantly associated with cancer. Enhancement patterns found to be associated with malignancy are rim enhancement, higher hounsfield units (HU) (> 57–60), and increases in HU over time greater than or equal to 32 HU. Non-breast pathologies such as COVID-related vaccine lymphadenopathy have been recognized in the breast imaging field over the past year and can be seen as an incidental finding on chest CT. Axillary lymphadenopathy associated with vaccinations such as COVID-19, which are administered within the deltoid, tends to follow a pattern of enlarged high level 1 or 2 axillary nodes without enlargement of lower level 1 nodes. In contrast, breast cancer-associated lymphadenopathy has a predictable pattern of enlargement beginning in the lower level 1 lymph node chain and progressing to higher level 1, 2, and 3 lymph node chains.

Knowledge of expected imaging appearance of malignant versus benign breast lesions on routine chest CT can allow the interpreting radiologist to more accurately identify suspicious lesions that require further workup. Radiologists in breast clinics should be aware of presentations of breast and non-breast pathologies on chest CT, as these are common incidental finding referrals and can alter the course of a patient's care.