Mammography ARRT Exam Questions & Answers 2026 (11–20)

Question 1

The superficial fascia of the breast has two layers. The posterior (deep) layer separates the breast from which structure?

TheoryPractice · Accepted Answer

Retromammary fat and pectoralis fascia. The deep layer of the superficial fascia forms the posterior boundary of the glandular breast and lies just anterior to the retromammary fat pad and the pectoralis major fascia, defining the posterior margin of the breast proper.

Question 2

How many lobes does the mature female breast typically contain?

TheoryPractice · Accepted Answer

15–20. The adult breast typically contains 15–20 lobes arranged radially around the nipple, each lobe composed of multiple lobules. Each lobe drains via a separate lactiferous duct that opens at the nipple.

Question 3

The smallest functional unit of the breast that is capable of milk secretion is the:

TheoryPractice · Accepted Answer

Terminal duct lobular unit (TDLU). The terminal duct lobular unit (TDLU) consists of the terminal duct and the lobule (acini) it drains; it is the basic secretory unit of the breast and is the site of origin for most breast carcinomas and benign proliferative lesions.

Question 4

Most invasive breast carcinomas arise from which histologic structure within the breast?

TheoryPractice · Accepted Answer

Terminal duct lobular unit (TDLU). The TDLU is the origin of the vast majority of breast carcinomas, both ductal and lobular types, as well as most benign proliferative conditions (fibroadenoma, ADH, LCIS), because it is the most mitotically active epithelial compartment.

Question 5

The lactiferous sinuses (ampullae) are located just beneath the:

TheoryPractice · Accepted Answer

Areola, at the base of the nipple. The lactiferous sinuses are dilated segments of each lactiferous duct located immediately beneath the areola; they serve as reservoirs for milk during lactation before it is expressed through the nipple openings.

Question 6

How many lactiferous duct orifices typically open at the nipple?

TheoryPractice · Accepted Answer

5–10. Each of the 15–20 breast lobes has its own lactiferous duct, but not all open separately at the nipple surface; functional studies suggest 5–10 main orifices are patent in most women, as some ducts converge or are vestigial.

Question 7

On galactography (ductography), a smooth, well-defined intraluminal filling defect within a single lactiferous duct most likely represents:

TheoryPractice · Accepted Answer

Intraductal papilloma. An intraductal papilloma classically appears as a smooth, well-defined filling defect within a single duct on galactography and is the most common cause of spontaneous unilateral nipple discharge in women under 50 years of age.

Question 8

During the luteal phase of the menstrual cycle, lobular acini undergo changes that result in:

TheoryPractice · Accepted Answer

Increased glandular size and perilobular edema, increasing breast density. Rising progesterone and prolactin levels in the luteal phase cause lobular acinar cells to enlarge, perilobular stroma to become edematous, and overall breast density to increase, which is why mammography is ideally performed in the follicular phase.

Question 9

Lobular involution, the natural regression of breast lobules with age, has which effect on mammographic appearance?

TheoryPractice · Accepted Answer

Replaces glandular tissue with fat, decreasing parenchymal density. Lobular involution is the postmenopausal process in which glandular lobules are progressively replaced by fat and fibrous tissue. Complete lobular involution is associated with decreased mammographic density and reduced breast cancer risk.

Question 10

The primary arterial blood supply to the medial breast comes from which vessel?

TheoryPractice · Accepted Answer

Internal mammary (internal thoracic) artery. The internal mammary (internal thoracic) artery, a branch of the subclavian artery, provides the principal blood supply to the medial and central breast via its anterior perforating branches passing through the intercostal spaces.

Mammography ARRT Exam Questions & Answers 2026 (11–20)

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