Combining contrast enhanced mammography and radio-active free magnetic seed localization of non-palpable breast tumors: A feasibility study

Breast cancer patients are increasingly treated with neoadjuvant chemotherapy
for various reasons. These women receive chemotherapy before any surgery is
performed. Many of these tumors need preoperative seed localization to help
guide the surgeons to the site of the tumor within the breast. In many
hospitals, a radioactive I-125 seed is used for this purpose, which has several
disadvantages, such as a slight increase in radiation dose and extensive
administrative regulations to monitor the location of the seed at any time
(required by law). This administrative work is time consuming, elaborate and
prone to errors. Therefore, interest is shifting towards to use of
non-radioactive seeds, such as the magnetic seeds used in this study. A
drawback of these seeds is the fact that they cause large susceptibility
artifacts on (magnetic!) MRI of the breast. Breast MRI is the most accurate
modality to monitor response to therapy of these women. CEM, an emerging breast
imaging technique, has shown to achieve comparable results with regard to
response monitoring but uses no magnetic fields. Hence, CEM might be an
attractive alternate response monitoring tool in patients treated with
neoadjuvant chemotherapy and having a magnetic seed a surgical marker. To this
point, however, no study in humans has confirmed that this is indeed the case.

To test whether the use of magnetic localization seeds causes image artifacts
on CEM.

Observational feasibility study.

The burden and risk for participating subjects are very small. In regular care,
a radioactive I-125 seed is placed in the breasts of these women, checking the
position with (conventional) FFDM. For this purpose, the iodine seed is
replaced with a (radioactive-free) magnetic seed (Sirius Pintuition). The
latter did not show any relevant imaging artifacts prior to this study in
imaging phantoms (i.e., chicken breasts containing magnetic seeds). Therefore,
we feel confident that these seeds will not show artifacts on clinical CEM
image, but this needs to be confirmed before additional studies regarding the
clinical application of CEM and magnetic seeds combined can be safely
performed. The only additional disadvantage for participants is the slight
increased radiation dose of the (extra) high-energy image CEM image, which is
an increased radiation dose to the breasts of 50-80%. However, these women are
all diagnosed with breast cancer requiring adjuvant radiotherapy, which uses
radiation doses much, much higher than a single mammographic exposure.