Mammography ARRT Exam Questions & Answers 2026 (21–30)

Question 1

The lateral thoracic artery, a branch of the axillary artery, primarily supplies blood to which region of the breast?

TheoryPractice · Accepted Answer

Lateral and upper outer quadrant. The lateral thoracic artery descends along the lateral thoracic wall and provides branches that supply the lateral breast, particularly the upper outer quadrant and the axillary tail of Spence.

Question 2

On contrast-enhanced MRI, which feature of tumor neovascularity is most characteristic of malignancy in the kinetic curve analysis?

TheoryPractice · Accepted Answer

Initial rapid enhancement followed by washout (type III curve). Malignant lesions typically show rapid initial enhancement (due to angiogenesis and vessel leakiness) followed by washout on delayed images (type III curve), whereas benign lesions more often show persistent or plateau enhancement. The washout pattern has the highest positive predictive value for malignancy.

Question 3

What percentage of breast lymphatic drainage flows toward the axillary lymph nodes?

TheoryPractice · Accepted Answer

75–97%. Approximately 75–97% of breast lymph drains to the axillary lymph nodes, making them the primary regional nodal basin for breast cancer staging and sentinel lymph node biopsy.

Question 4

The axillary lymph nodes are divided into three levels based on their relationship to which muscle?

TheoryPractice · Accepted Answer

Pectoralis minor. Axillary lymph nodes are classified into Levels I (lateral/inferior to pectoralis minor), Level II (posterior to pectoralis minor), and Level III (medial/superior to pectoralis minor, also called the infraclavicular or apical nodes).

Question 5

The Rotter (interpectoral) lymph nodes are located between which two muscles?

TheoryPractice · Accepted Answer

Pectoralis major and pectoralis minor. Rotter nodes (interpectoral nodes) lie between the pectoralis major and minor muscles and drain toward Level II axillary nodes; they are important to identify during axillary dissection and can be sites of breast cancer metastasis.

Question 6

Internal mammary lymph nodes are most commonly located in which intercostal spaces?

TheoryPractice · Accepted Answer

1st through 3rd. The internal mammary (parasternal) nodes lie along the internal mammary vessels predominantly in the first three intercostal spaces, receiving drainage mainly from the medial and central breast. Metastasis here (especially Level III+ disease) worsens prognosis.

Question 7

In breast cancer staging, the sentinel lymph node (SLN) is defined as:

TheoryPractice · Accepted Answer

The first regional node(s) that directly receive lymphatic drainage from the tumor. The sentinel lymph node is defined as the first node(s) in the lymphatic basin to receive direct drainage from the primary tumor; its pathologic status predicts the status of the remaining regional nodes, allowing selective axillary dissection.

Question 8

Sensory innervation to the nipple-areola complex is primarily derived from which nerve?

TheoryPractice · Accepted Answer

Lateral cutaneous branch of the 4th intercostal nerve. The nipple-areola complex receives its primary sensory innervation from the lateral cutaneous branch of the 4th intercostal nerve (T4 dermatome), which is important to preserve during mastectomy and reduction mammoplasty to maintain nipple sensation.

Question 9

During axillary lymph node dissection, injury to the long thoracic nerve (nerve of Bell) results in which clinical finding?

TheoryPractice · Accepted Answer

Winged scapula. The long thoracic nerve innervates the serratus anterior muscle; if injured during axillary dissection, the serratus anterior becomes paralyzed, causing the medial border of the scapula to protrude posteriorly, known as winged scapula.

Question 10

The embryologic structure from which the breast develops is called the:

TheoryPractice · Accepted Answer

Mammary ridge (milk line). The breast develops from the mammary ridge (milk line), an ectodermal thickening that forms bilaterally from the axilla to the inguinal region in the 4th–6th week of fetal development. In humans, only the pectoral pair of buds normally persist.

Mammography ARRT Exam Questions & Answers 2026 (21–30)

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