A Pilot Study of the Impact of Microwave Ablation on the Dielectric Properties of Breast Tissue

Percutaneous microwave ablation (MWA) is a promising technology for patients with breast cancer, as it may help treat individuals who have less aggressive cancers or do not respond to targeted therapies in the neoadjuvant or pre-surgical setting. In this study, we investigate changes to the microwave dielectric properties of breast tissue that are induced by MWA. While similar changes have been characterized for relatively homogeneous tissues, such as liver, those prior results are not directly translatable to breast tissue because of the extreme tissue heterogeneity present in the breast. This study was motivated, in part by the expectation that the changes in the dielectric properties of the microwave antenna’s operation environment will be impacted by tissue composition of the ablation target, which includes not only the tumor, but also its margins. Accordingly, this target comprises a heterogeneous mix of malignant, healthy glandular, and adipose tissue. Therefore, knowledge of MWA impact on breast dielectric properties is essential for the successful development of MWA systems for breast cancer. We performed ablations in 14 human ex-vivo prophylactic mastectomy specimens from surgeries that were conducted at the UW Hospital and monitored the temperature in the vicinity of the MWA antenna during ablation. After ablation we measured the dielectric properties of the tissue and analyzed the tissue samples to determine both the tissue composition and the extent of damage due to the ablation. We observed that MWA induced cell damage across all tissue compositions, and found that the microwave frequency-dependent relative permittivity and conductivity of damaged tissue are lower than those of healthy tissue, especially for tissue with high fibroglandular content. The results provide information for future developments on breast MWA systems.

Development and application of human breast phantoms in microwave diagnostic and therapeutic technologies

We highlight recent progress in the development of high-fidelity numerical and physical breast phantoms. These phantoms mimic the anatomical structure and physical properties that are relevant to accurately portraying microwave interactions with the human breast. The phantoms are currently being used in numerous laboratory studies of microwave diagnostic and therapeutic technologies for a variety of potential clinical applications in breast health and disease management.

Affinity purification of polyclonal antibodies from antigen immobilized in situ in sodium dodecyl sulfate-polyacrylamide gels

A procedure for the preparation of affinity-purified antibody is described. Protein mixtures are separated by electrophoresis in sodium dodecyl sulfate (SDS)--polyacrylamide gels. Individual bands of protein are cut from the gel and fixed in situ with glutaraldehyde. The gel pieces are then homogenized and washed extensively with buffered solutions and chaotropic agents. The washed gels can then be used as immunoadsorbents to purify antibodies from crude antisera. This method should be especially useful for the preparation of small amounts of antibody to proteins that are difficult to purify by conventional means, that are available only in limited quantity, or that cannot be blotted to immunoadsorbents such as nitrocellulose or diazotized paper.