Breast anatomy and scan technique

Question 1

How many lobes are in the breast?

Answer 1

15-20

Question 2

What are the three layers of breast tissue and their divisions?

Answer 2

Subcutaneous zone (between skin and anterior mammary fascia), mammary zone (between anterior and posterior mammary fascia), and retromammary zone (contains mostly fat, blood vessels, and lymphatics).

Question 3

What breast layer is most likely affected by pathology?

Answer 3

Middle mammary zone

Question 4

What are the different levels of axillary LN’s and what are their boundaries?

Answer 4

Level 1 - lateral and inferior to pec minor
Level 2 - deep to pec minor
Level 3 - superior and medial to pec minor

Question 5

What are Rotter’s LN’s?

Answer 5

LN’s that lie between pec minor and pec major (interpectoral space).

Question 6

Which LN’s of the breast area are most likely to be affected by pathology first?

Answer 6

Axillary LN’s (level 1).

Question 7

Where are the internal mammary LN’s located?

Answer 7

Just lateral to the sternum

Question 8

What other LN’s should be checked to see if invasion is extensive?

Answer 8

Supraclavicular and jugular LN’s.

Question 9

What are Cooper’s ligaments?

Answer 9

Fibrous connections which run between the undersurface of the breast skin and the pectoral muscles.

Question 10

What is the sentinel node?

Answer 10

The first LN that lymph and thus cancer drains into.

Question 11

What are the four criteria of breast annotations to include upon discovery of a mass?

Answer 11

Side
Clock face position
Distance from nipple in cm
Transducer orientation

Question 12

What is radial and antiradial scanning?

Answer 12

Scanning around the nipple in a clock fashion. Antiradial scanning is perpendicular to the line of this type of scanning.

Question 13

What is the advantage of radial scanning?

Answer 13

Ducts lie radially in comparison to nipple so components of DCIS will be seen better.

Question 14

What are some techniques that can be used to differentiate between a solid vs cystic breast mass?

Answer 14

Colour Doppler and ballotment (differentiates solid mass from cystic mass with internal echoes)

Question 15

How can spatial compounding be utilised in breast imaging?

Answer 15

Turning it off can highlight posterior acoustic enhancement
Turning it on will mean the internal contents of the mass is less affected by artifact

Question 16

What pathologies are associated with pain on ballotment?

Answer 16

Acutely inflamed cysts and acute periductal mastitis

Question 17

How can Doppler be used to differentiate between benign reactive vs. metastatic LN’s?

Answer 17

Mets have transcapsular vascularity and high resistance waveform

Question 18

What are the different types of benign cystic structures/features in the breast?

Answer 18

Simple
MOC cysts
Fat fluid level
Eggshell calcs (most often seen on mammo and don’t require US)
Clustered macrocysts
Cysts of skin origin
Foam and acorn cysts

Question 19

What is the functional unit of the breast called and what is it comprised of?

Answer 19

Terminal duct lobular unit
Ductule drains into the interlobular terminal duct then into the extralobular terminal duct - these make up the TDLU

Question 20

What should you have on the deepest portion of your screen when scanning the breast?

Answer 20

Pectoralis muscle

Question 21

What technique can you use to prevent shadowing from Cooper’s ligaments?

Answer 21

Heel-toeing the transducer

Question 22

What are the different descriptors we can use/assess when analysing breast lesions?

Answer 22

Margins (well-circumscribed, indistinct, angular, micro-lobulated, spiculated; is there a capsule - is it hyper/hypoechoic, is it thin or thick?)
Echogenicity
Posterior acoustic features
Surrounding tissue (any invasion into the ducts, changes to Cooper’s ligaments, architectural distortion, retraction. oedema?)
Vascularity (within, feeding vessel, surrounding the lesion?)