Mammography, Ultrasound and Breast MRI: How the Imaging Methods Differ

Mammography, ultrasound and magnetic resonance imaging (MRI) are different techniques used to examine breast tissue. Each produces images in a different way and provides information about different features of the breast.

No single imaging method answers every clinical question. The choice of examination depends on the reason for assessment, the findings that need to be investigated and the patient's individual circumstances.

1. Mammography: Examining Breast Tissue Using X-rays

Mammography uses low-dose X-rays to produce images of the breast. It is used for both breast cancer screening and diagnostic assessment.

Mammography can demonstrate findings such as masses, calcifications, asymmetries and architectural distortion. It is particularly useful for identifying certain changes in breast tissue that may not be felt during a physical examination.

What is 3D mammography?

Three-dimensional mammography, also known as digital breast tomosynthesis (DBT), captures multiple low-dose X-ray images from different angles as the X-ray tube moves in an arc around the breast.

These images are reconstructed into thin sections, allowing the radiologist to examine the breast tissue layer by layer. This can help reduce the effect of overlapping tissue and improve the visibility of certain findings.

3D mammography is not a replacement for all other breast imaging examinations. Additional imaging may still be required depending on the clinical findings.

Learn more about 3D Mammography at Luma

2. Breast Ultrasound: Examining the Structure of a Finding

Breast ultrasound uses high-frequency sound waves to produce images of breast tissue. It does not use ionising radiation.

It is commonly used to assess a palpable breast lump or to examine an area identified on mammography.

Ultrasound can help the radiologist assess:

• Whether a lump is fluid-filled or solid

• The shape and margins of a lesion

• The internal characteristics of an abnormality

• The relationship of a finding to surrounding tissue

Ultrasound also has an important role in image-guided procedures. When a finding can be clearly seen on ultrasound, the radiologist may use real-time ultrasound images to guide a biopsy needle towards the area.

How does ultrasound complement mammography?

Mammography and ultrasound provide different information. For example, mammography may identify an area of concern, while ultrasound can provide further detail about its structure.

However, ultrasound does not replace mammography in every situation. The two examinations may be used together when clinically indicated.

Learn more about Breast Ultrasound at Luma

3. Breast MRI: Providing Additional Information in Selected Cases

Breast MRI uses a strong magnetic field, radio waves and a computer to produce detailed images of breast tissue. It does not use ionising radiation.

Most breast MRI examinations performed for cancer detection or assessment involve an intravenous contrast agent. This helps highlight areas of tissue with increased contrast enhancement.

Breast MRI may be considered in selected situations, including:

• Assessing the extent of a known breast cancer

• Investigating selected findings that remain unclear after mammography and ultrasound

• Screening women with certain hereditary breast cancer gene mutations or a sufficiently high estimated lifetime risk

• Assessing breast implants or other specific clinical concerns, where appropriate

MRI provides additional information but is not required for every woman. It is also not routinely used as a replacement for mammography or ultrasound.

Learn more about Breast MRI at Luma

4. Why Might More Than One Imaging Method Be Used?

Different imaging methods can provide complementary information about the same area of breast tissue.

For example:

• Mammography may identify a group of calcifications that requires closer examination.

• Ultrasound may help determine whether a lump is fluid-filled or solid.

• MRI may provide additional information about the extent of a known cancer or a selected finding that is not adequately characterised by other imaging.

Using more than one imaging method does not automatically mean that a finding is suspicious for cancer. It may simply be necessary to answer a particular clinical question.

5. How is the Appropriate Imaging Examination Selected?

The radiologist considers the clinical question and available information when determining which examination is appropriate.

Factors may include:

• The type and location of the finding

• Whether the examination is for screening or diagnostic assessment

• Breast density and tissue characteristics

• Symptoms and clinical examination findings

• Previous imaging results

• Personal and family medical history, where relevant

The choice of imaging is therefore individualised rather than based on a single examination being universally better than another.