Intrafraction motion monitoring to determine PTV margins in early stage breast cancer patients receiving neoadjuvant partial breast SABR

Current status of biopsy markers for the breast in clinical settings

INTRODUCTION

A breast biopsy marker is a very small object that is introduced into the breast to serve as a tissue marker. The placement of a breast marker following a biopsy or to mark an abnormality in the breast has become standard practice in the clinical setting. Breast biopsy markers offer a wide range of benefits which includes the prevention of re-biopsy of a benign tumor, differentiating multiple lesions within the breast, evaluation of the extent of a tumor, and increased precision during surgery.

AREAS COVERED

This review article presents a range of breast biopsy markers used in clinical practice. First, an overview of the necessity of breast markers in healthy breast management. Second, it summarizes the diversity in composition, shape, unique properties and features, and bio-absorbable carriers of breast biopsy markers. Finally, it also discusses the possible use of clinically approved breast biopsy markers in various scenarios and their implications.

EXPERT OPINION

This review serves as a guide in the selection of an appropriate breast marker. We believe that some of the common drawbacks associated with current breast biopsy markers can be overcome by developing novel polymer-metal and composite-based breast biopsy markers.

Intrafraction motion during radiotherapy of breast tumor, breast tumor bed, and individual axillary lymph nodes on cine magnetic resonance imaging

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Intrafraction motion of the breast and individual axillary lymph nodes was studied.

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Displacements were investigated using cine magnetic resonance imaging.

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Motion was separated into breathing and drift components.

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Medians of the maximum displacements were small, <3 mm for breast and lymph nodes.

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Intrafraction motion of the tumor (bed) was less in prone than in supine position.

Background and purpose

In (ultra-)hypofractionation, the contribution of intrafraction motion to treatment accuracy becomes increasingly important. Our purpose was to evaluate intrafraction motion and resulting geometric uncertainties for breast tumor (bed) and individual axillary lymph nodes, and to compare prone and supine position for the breast tumor (bed).

Materials and methods

During 1–3 min of free breathing, we acquired transverse/sagittal interleaved 1.5 T cine magnetic resonance imaging (MRI) of the breast tumor (bed) in prone and supine position and coronal/sagittal cine MRI of individual axillary lymph nodes in supine position. A total of 31 prone and 23 supine breast cine MRI (in 23 women) and 52 lymph node cine MRI (in 24 women) were included. Maximum displacement, breathing amplitude, and drift were analyzed using deformable image registration. Geometric uncertainties were calculated for all displacements and for breathing motion only.

Results

Median maximum displacements (range over the three orthogonal orientations) were 1.1–1.5 mm for the breast tumor (bed) in prone and 1.8–3.0 mm in supine position, and 2.2–2.4 mm for lymph nodes. Maximum displacements were significantly smaller in prone than in supine position, mainly due to smaller breathing amplitude: 0.6–0.9 mm in prone vs. 0.9–1.4 mm in supine. Systematic and random uncertainties were 0.1–0.4 mm in prone position and 0.2–0.8 mm in supine position for the tumor (bed), and 0.4–0.6 mm for the lymph nodes.

Conclusion

Intrafraction motion of breast tumor (bed) and individual lymph nodes was small. Motion of the tumor (bed) was smaller in prone than in supine position.