Radiographic Techniques: Mammography Overview

Radiographic Techniques

• Mammography is a radiographic examination of breast tissue.
• It visualizes normal breast structures and pathologies.
• Low kVp (typically 28 kVp) is used for mammography.
• Radiation dose must be minimized due to breast tissue sensitivity.
• Mammography is performed on symptomatic women with a known history or suspected abnormality, and as a screening procedure for asymptomatic women.
• Consistent technique and image quality are crucial, particularly in screening mammography.
• Other techniques like MRI and ultrasound also play roles in breast imaging.

Mammography Techniques

• Mammography is a type of soft-tissue radiography.
• It's used to diagnose or treat patients through recording images of internal body structures to evaluate the presence or absence of diseases, foreign bodies and damage or anomalies.
• A mammography system consists of a high-voltage generator, X-ray tube, tube filtration, compression device, image-recording system, and an automatic exposure control (AEC).

Mammography: Recommended Projections (Basic)

• Basic Projections:
  • 45-degree medio-lateral oblique (MLO)
  • Craniocaudal (CC)
• Used in the diagnosis or treatment of patients by recording images of the internal structure of the body.

Radiological Considerations

• Lesion Characteristics:
  • Four main types: masses, calcifications, architectural distortion, and density.
  • Masses are assessed by shape, margin, and density.
  • Benign masses tend to be round, oval, and well-defined.
  • Malignant masses tend to be irregular in shape and often hyperdense.
  • Low-density lesions suggest fat and are usually benign.

Calcifications

• Calcification variations: size, shape, number, and orientation.
• There are several benign forms like popcorn and milk-like calcifications, and various shapes/types of calcifications, like rod- or ring-like.
• Malignant calcifications are often grouped, linear, and irregular in size and shape.

Architectural Distortion

• Architectural distortion is a feature of many carcinomas and may also occur with benign conditions, such as sclerosing adenosis.
• Typically, this is diagnosable only by histology.
• Focal increased density may be a sign of malignancy, but low specificity unless combined with other features.

Other Techniques (e.g. Ultrasound, MRI)

• Ultrasound:
  • Most widely used, readily available alternative imaging technique.
  • Best for determining if a lesion is a cyst; also useful in detecting other fluid-filled diseases like abscesses.
  • Provides different tissue information, such as homogeneity, acoustic shadowing, and vascularity.
  • Aids in assessing mammographically indeterminate masses and guiding biopsies.
  • Important in younger patients with dense breasts and lower suspicion for malignancy because it minimizes radiation exposure.
• MRI (Magnetic Resonance Imaging):
  • Expensive, time-consuming, and not widely available.
  • Some patients cannot tolerate it due to claustrophobia.
  • Demonstrates morphological features.

45-degree Medio-lateral Oblique (MLO) Projection

• The equipment is angled at 45 degrees from the vertical.
• The patient's position, arm placement, and table adjustments are important to prevent confusion with other mammographic projections.

Essential Image Characteristics

• Axilla, glandular tissue, and pectoral muscle should be visible.
• Projections (images) should be symmetrical (mirror images).
• No overlying structures, folds in the breast tissue, or nipple misalignment should exist.

Cranio-Caudal (CC) Projection

• The mammography equipment is positioned with the X-ray beam vertically downwards.
• The patient faces the equipment with arms at her side.
• The patient is ideally rotated 15–20 degrees to align the side of the breast under examination with the horizontal breast-support table.
• The radiographer positions and holds the breast.
• Clear images show the breast's axillary side and nipple midline.