Céline Porte – cporte@ukaachen.de

Institute for Experimental Molecular Imaging
RWTH Aachen University
Aachen, North Rhine-Westphalia 52074

Fabian Kiessling – fkiessling@ukaachen.de
Institute for Experimental Molecular Imaging, RWTH Aachen University
Aachen, 52074

Popular version of 1aBAb3 – Monitoring of neoadjuvant chemotherapy response of breast cancer with ultrasound localization microscopy
Presented at the 186th ASA Meeting
Read the abstract at https://eppro02.ativ.me/web/index.php?page=IntHtml&project=ASASPRING24&id=3675343

–The research described in this Acoustics Lay Language Paper may not have yet been peer reviewed–

One in every eight women develops breast cancer over her lifetime. Despite tremendous advances in therapy over the last decades, particularly aggressive breast cancer remains challenging to treat. The current clinical standard is to subject these patients to chemotherapy already before surgically removing their tumor. The ultimate goal of this treatment is to make the tumor disappear completely and to use the surgery solely to confirm that no cancer cells are remaining in the tissue. However, the majority of patients does not sufficiently respond to the chemotherapy treatment. In this case, the therapeutic outcome must be critically weighed against the expected side effects and risks. Therefore, it is highly important to 1) better identify patients that are likely to not sufficiently respond to the therapy (patient preselection) and to 2) make sure that patients subjected to therapy do indeed respond (therapy monitoring).

breast cancer
Figure 1: Super-resolution ultrasound image of a human breast tumor.

In our study, we are investigating the use of super-resolution ultrasound (Fig. 1) for these two applications. This emerging technique provides histology-like images of vessel trees and allows to determine the blood flow within each individual vessel, thus providing new information on microvascular perfusion. As the vascular system is tightly bound to tumor development, we hypothesize that super-resolution ultrasound might reveal differences between fully and incompletely responding patients.

To investigate this, we examined breast cancer patients during their chemotherapy treatment. More precisely, we characterized their tumor right before they received their first, second, and fourth dose of chemotherapeutics. Here, we measured the tumor size and recorded ultrasound videos in which we highlighted the vessels using a contrast agent. We subsequently post-processed these videos to obtain super-resolution images of the vessel architecture and blood flow velocities. Finally, we extracted a multitude of morphological and functional vessel features, which together form a vascular fingerprint.

Our approach revealed that patients responding fully to therapy differed noticeably from partial responders before the start of chemotherapy. Their tumors were more vascularized, their vessels more tortuous, and the vessel architecture was different. Both patient groups could be distinguished with high accuracy when applying a first classification approach. During chemotherapy, many features associated with malignancy normalized in case of full responders, meaning that the vessels resembled more and more those of healthy tissue. In contrast, this was not observed for partial responders.

These findings show that super-resolution ultrasound might be able to fill a tremendous gap in therapy monitoring and, especially, patient preselection of breast cancer patients. Being able to identify patients that insufficiently respond to therapy would avoid the side effects of an ineffective therapy and would allow the medical doctors to look for a more adequate treatment. In that way, super-resolution ultrasound could considerably improve the therapy outcome of these patients.

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