Imaging the Breast Flashcards
In what 4 scenarios might women be referred for breast imaging?
- if they are symptomatic and notice an abnormality of the breast, such as:
- lumps / masses
- skin changes
- shape changes
- nipple discharge
- pain (rarely a sign of malignancy)
- as part of a breast screening programme (asymptomatic women)
- for surveillance after breast cancer
- for surveillance due to family history
What is meant by the “triple assessment” for breast changes?
- the “triple assessment” comprises clinical examination, imaging and histology
What are the risk factors for breast cancer?
What is the epidemiology like?
- smoking
- obesity
- nulliparity
- increasing age
- late menopause
- previous family history
- around 50,000 women are diagnosed with invasive breast cancer each year and 8/10 are >50
Who is invited to the UK screening programme for breast cancer?
- asymptomatic women between 50 - 71** are invited for screening **every 3 years
- women < 50 may be screened if they are at a high risk of developing breast cancer
- women > 71 are not invited to screening, but can have screening if they wish
What symptoms / signs would result in referral to a breast clinic for further investigation into possible breast cancer?
- a lump in the breast or chest wall
- an area of thickened breast tissue
- change in the size / shape of one or both breasts
- discharge from the nipple (may be streaked with blood)
- lumps / swellings in the armpit
- dimpling of the skin around the breasts
- rash on or around the nipple
- change in appearance of the nipple (becoming sunken into the breast)
pain is not usually a sign of cancer
What are the first line techniques for imaging the breast?
- mammography
- ultrasound
How does mammography work?
- it uses X-rays that are equivalent to a couple of months’ background radiation
- the X-rays are specialised and lower energy as normal and pathological breast tissue have similar properties
- the breast is compressed prior to taking the image
Why is the breast compressed in mammography?
How many images are usually taken?
- the breast is compressed to decrease tissue thickness** and **minimise image artefact / blurring
- it is difficult to spot small lesions on mammograms due to the superimposition of strutures in a 2D image of a 3D structure
- this is particularly the case in dense breasts
- taking multiple projection images of the breast from different angles allows reconstruction of a 3D image that provides more detail of breast tissue
- usually craniocaudal and mediolateral views are obtained
- tomosynthesis involves 9 views and gives more information
What is the benefit of using digital mammography over analogue?
- digital mammography allows for image manipulation
What views of the breast are shown here?
right mediolateral oblique and left craniocaudal views
What is Chassaignac bursa?
Why is it important to identify?
- it is a lucency on the mammogram that represents connective tissue between the breast and chest wall
- it should be seen on all CC and MLO mammograms
- if it is not seen, the image is not technically adequate
As well as the presence of Chassaignac bursa, what other technical details must be present in both CC and MLO views in order for the image to be adequate?
- all glandular breast tissue must be seen
- image must be correctly annotated
- no movement artefact
- no skin folds
- images should be symmetrical
What technical details specific to CC and MLO images need to be present in order for the image to be adequate?
Craniocaudal view (CC):
- the nipple should be in profile and in the midline of the image
Mediolateral oblique view (MLO):
- the pectoral shadow should be seen down to the level of the nipple or lower
When is mammography the first line investigation?
- for routine screening (asymptomatic women) over 35 years of age
- for symptomatic women over 35 years of age
women <35 have denser breast tissue, so USS is the first line imaging technique
What are the advantages and disadvantages of mammography?
Advantages:
- relatively cheap and quick
- non-invasive
- very good visualisation
- can be used to guide biopsy (but US is usually used)
Disadvantages:
- can be uncomfortable for some patients
- difficult if breasts are small
- not as effective if breast tissue is dense
How do invasive carcinomas typically appear on a mammogram?
- they are spiculated
- they have poorly defined / irregular margins
- they distort the architecture of surrounding tissue
What is shown in these images?
What is meant by 3D digital tomosynthesis and why is it performed?
- it is difficult to spot small lesions on mammograms due to the superimposition of structures in a 2D image of a 3D structure
- it is more difficult to spot lesions in dense breasts
- taking multiple projection images of the breast from different angles allows for reconstruction into a 3D image that provides more detail of breast tissue
- an X-ray tube rotates through 50o to obtain 9 projections
What is the difference between these images?
the lesion is much easier to identify when 3D tomosynthesis is used compared to a 2D image
What are examples of benign breast lesions?
What features do they all share on US?
- benign lesions include fibroadenomas, lipomas and simple cysts
- they all appear as well-defined, hypoechoic lesions that are uniform in shape** with **normal vascularity
What are the US features of malignant lesions?
When do lymph nodes arouse suspicion?
- carcinomas appear as irregular masses (less uniform in shape) that are poorly defined
- they are hypoechoic
- they may show posterior acoustic shadowing
- they may have internal echoes / shadowing or calcifications
- colour doppler can show abnormal vascularity
- they tend to be taller rather than wide
- lymph nodes are suspicious when they are enlarged** or have **thickened cortices
How is a vacuum-assisted breast biopsy (mammotome / minimally invasive breast biopsy) performed?
When is this used?
- a core biopsy needle is attached to a vacuum that sucks the tissue into the needle
- a rotating cutting device takes the sample
- it may place a clip in-situ for localisation once the procedure is finished
- it uses local anaesthetic
- it is suitable for small impalpable lesions under image guidance
When can contrast-enhanced MRI be used in confirmed malignancy?
- lesions rapidly take up contrast, showing increased vascularity around malignancies
- can be used in lobar carcinomas, which tend to be multifocal
- in axillary lymph node assessment
- to evaluate tumour response to chemotherapy prior to surgery and to detect recurrence
- to assess scars at lumpectomy sites and differentiate scar tissue from recurrence
- to assess invasion of malignancy (i.e. into underlying muscle) and the presence / extent of visceral and/or bony metastases
When is nuclear medicine used in imaging the breast?
sentinel node imaging
- technetium-99m attached to sulphur colloid particles is injected into a tumour
- the particles migrate through the lymphatic system to the nearest lymph node, where they are phagocytosed and retained
- this allows identification of the sentinel lymph nodes
- this aids staging of cancer and allows for planning of future surgery
