Introduction
Hi everyone, my name is Azadeh Almi. I'm one of the breast imaging attendings at UCSD. I joined UCSD almost a year ago in a joint position with Eisenhower Cancer Center. In this presentation, we'll discuss the advantages and challenges of evaluating calcifications on tomosynthesis and synthesized views, primarily used in screening. I have nothing to disclose.
Opening Objectives
In the next 30 minutes, we will:
- Describe the differences between 2D mammography, tomosynthesis, and synthesized view for evaluating calcifications.
- Discuss the appearance of benign and suspicious calcifications on tomosynthesis and synthesized view.
- Address the challenges and artifacts encountered when imaging calcifications on tomosynthesis and synthesized view.
- Touch on the application of tomosynthesis for guiding stereotactic biopsy for sampling calcifications.
Topics with Summary and Key Points
1. Evaluation of Calcification
Tomosynthesis is emerging as a standard of care for breast imaging in both academia and private practices across the country. Major advantages include superior assessment of asymmetries and masses compared to conventional 2D mammography, resulting in improved cancer detection and reduced callbacks and false positives. However, concerns remain regarding the assessment of calcifications using standalone synthetic mammography and tomosynthesis.
2. Challenges in Detecting and Characterizing Calcifications
Identifying and characterizing calcifications is challenging. Despite improvements in technology, magnification views remain the standard for assessing indeterminate calcifications due to their high contrast resolution and sharp processing algorithms. Synthetic views created from tomosynthesis can vary in effectiveness based on the reconstruction algorithm used, which may enhance or suppress calcifications.
3. Benefits and Pitfalls of Synthetic View and Tomosynthesis
Synthetic view combined with tomosynthesis reduces radiation dose and imaging time, making it a desirable substitute for conventional 2D mammography. This combination improves the conspicuity of medium and large calcifications but may lead to false positives due to pseudocalcifications and motion artifacts. Studies show that tomosynthesis has a slightly lower sensitivity for evaluating calcifications compared to conventional digital mammography, with reported sensitivities in the 80% range for tomosynthesis and synthetic view versus 90% for conventional mammography.
4. Detection and Characterization of Calcifications
Tomosynthesis aids in the detection and characterization of calcifications by providing better visualization of distribution. When using tomosynthesis, we rely on synthetic views to detect calcifications. These synthetic views are virtual 2D mammography images created from tomosynthesis acquisitions using various reconstruction algorithms, which can either enhance or suppress calcifications based on their size, morphology, and the type of algorithm used.
Key factors in assessing calcifications include:
- Morphology: We examine the borders and shape of calcifications.
- Distribution: Different predictive values are assigned based on distribution patterns.
- Changes over time: We evaluate how calcifications change over past mammograms.
5. Applications in Screening and Biopsy
Tomosynthesis aids in detecting and characterizing benign calcifications, such as vascular calcifications, skin calcifications, and milk of calcium. It also helps in evaluating malignant calcifications and the extent of disease.
For example:
- Vascular Calcifications: Tomosynthesis helps identify early forms of vascular calcifications by visualizing them within vascular structures.
- Skin Calcifications: Tomosynthesis helps distinguish skin calcifications by showing their superficial location in the first or last three tomosynthesis slices.
- Milk of Calcium: Tomosynthesis helps confirm the layering appearance of milk of calcium within cysts, aiding in characterization as benign.
Tomosynthesis-guided biopsy facilitates faster targeting and accurate localization, reducing procedure time by about 50%. This is due to the accurate depth information provided by tomosynthesis, eliminating the need for paired images and using the full detector size for easier localization.
6. Pitfalls and Artifacts
Despite improvements in technology, some pitfalls and artifacts still limit the assessment of calcifications. Pseudocalcifications, a known artifact of synthetic views, result from algorithms enhancing densities or ligaments, falsely appearing as calcifications. Motion artifacts can degrade image quality, making subtle findings and calcifications harder to evaluate.
Common artifacts include:
- Shadowing or Halo Artifact: Low density areas surrounding high density objects can obscure subtle findings.
- Zipper Artifact: Repetition of dense objects out of the tomosynthesis plane can degrade image quality around subtle findings.
Conclusion
Conventional mammography is slightly more sensitive than tomosynthesis and synthetic view for evaluating calcifications. While the combination of synthetic view and tomosynthesis is promising, more studies and longer follow-up are needed to establish its efficacy. Tomosynthesis helps in detecting and assessing calcifications' distribution, but magnification views are still needed for indeterminate cases. Continued improvements in technology and reconstruction algorithms are anticipated to enhance performance. Tomosynthesis-guided biopsy offers faster and more accurate targeting for sampling suspicious findings.
Thank you for your attention. At the end of the session, we will have a question and answer session. You can also email me with any questions. Have a great day.
