Contrast Enhanced Mammography

Introduction

Hi everyone, my name is Azadeh Elmi. I'm one of the faculties at UC San Diego. In this presentation, we'll be talking about contrast-enhanced mammography and how this emerging modality might perform and fit in our daily clinical practice as breast imagers.

Objectives

We will:

  • Cover the basics, techniques, and physics behind contrast-enhanced mammography.
  • Discuss the algorithm for interpretation and reading the studies with contrast-enhanced mammography.
  • Compare the evidence-based performance of this modality versus conventional imaging like mammography, ultrasound, and MRI.
  • Review common imaging findings, mostly based on the indication of the studies.
  • Go over the BI-RADS terminology that we can use to interpret and report these studies.
  • Discuss challenges and pitfalls associated with this modality.

Topics

Basics, Techniques, and Physics

Contrast-enhanced mammography combines digital mammography with the injection of contrast material to highlight areas of increased blood flow, potentially indicating malignancy. The dual-energy technique involves taking images at both low and high energy levels to enhance contrast while minimizing radiation exposure. This technique has evolved from earlier methods which had higher radiation doses and longer imaging times.

Interpretation Algorithm

Radiologists evaluate low-energy images, equivalent to conventional digital mammograms, to identify calcifications, masses, and asymmetries. Subtraction images are used to assess areas of abnormal enhancement. If an abnormality is detected, further imaging such as ultrasound or MRI may be performed to confirm findings and guide biopsy. Recent developments include the introduction of contrast-enhanced mammography-guided breast biopsy systems.

Performance Comparison

Studies have shown that contrast-enhanced mammography significantly improves cancer detection rates compared to mammography alone, particularly in dense breast tissue. Sensitivity ranges from 94% to 100%, comparable to MRI, but with a lower false positive rate. This makes it a valuable tool for supplemental screening, especially in cases where MRI is contraindicated or unavailable.

Case-Based Review

Several case studies demonstrate the effectiveness of contrast-enhanced mammography:

  • Case 1: A 48-year-old woman with dense breasts had a small cancer detected by contrast-enhanced mammography that was not visible on conventional mammograms. Biopsy confirmed invasive ductal carcinoma.
  • Case 2: A 51-year-old high-risk patient with BRCA gene mutation had an irregular enhancing mass detected, correlating with findings on ultrasound. Biopsy confirmed invasive ductal carcinoma.
  • Case 3: A 56-year-old woman with a history of breast cancer had new non-mass enhancement detected by contrast-enhanced mammography, leading to the diagnosis of invasive lobular carcinoma.
  • Case 4: A 59-year-old woman with segmental non-mass enhancement detected, correlating with MRI findings. Biopsy confirmed non-calcified DCIS.

Challenges and Pitfalls

While contrast-enhanced mammography improves cancer detection, it also presents challenges:

  • False Positives: Benign lesions like fibroadenomas, papillomas, and abscesses can enhance similarly to malignant lesions, leading to unnecessary biopsies.
  • Background Enhancement: Differentiating between normal tissue enhancement and malignancy can be difficult, though overall enhancement is lower compared to MRI.
  • False Negatives: Certain cancers, especially invasive lobular carcinoma, may not enhance and be missed. Suspicious findings on conventional mammograms or ultrasound should still be biopsied if contrast-enhanced mammography is negative.
  • Field of View Limitations: Lesions in areas not well-covered by mammographic views, such as the axillary tail or deep in the axilla, may be missed.
  • Lack of Official BI-RADS Terminology: Currently, there is no official BI-RADS lexicon for contrast-enhanced mammography, though future updates are expected to address this.

Conclusion

Contrast-enhanced mammography enhances cancer detection rates compared to traditional mammography, particularly in dense breast tissue. It offers a cost-effective, accessible alternative to MRI with fewer false positives, making it a valuable tool for breast cancer screening and diagnosis. With ongoing advancements and the introduction of guided biopsy systems, its utility in clinical practice is expected to grow.

Thank you for your attention.