*Article* **Contrast-Enhanced Spectral Mammography Assessment of Patients Treated with Neoadjuvant Chemotherapy for Breast Cancer**

**Katarzyna Steinhof-Radwa ´nska 1,\*, Anna Grazy ´ ˙ nska 2, Andrzej Lorek 3, Iwona Gisterek 4, Anna Barczyk-Gutowska 1, Agnieszka Bobola 4, Karolina Okas 2, Zuzanna Lelek 2, Irmina Morawska 2, Jakub Potoczny 2, Paweł Niemiec 5 and Karol Szyluk 6**


**Abstract:** Background: Evaluating the tumor response to neoadjuvant chemotherapy is key to planning further therapy of breast cancer. Our study aimed to evaluate the effectiveness of lowenergy and subtraction contrast-enhanced spectral mammography (CESM) images in the detection of complete response (CR) for neoadjuvant chemotherapy (NAC) in breast cancer. Methods: A total of 63 female patients were qualified for our retrospective analysis. Low-energy and subtraction CESM images just before the beginning of NAC and as a follow-up examination 2 weeks before the end of chemotherapy were compared with one another and assessed for compliance with the postoperative histopathological examination (HP). The response to preoperative chemotherapy was evaluated based on the RECIST 1.1 criteria (Response Evaluation Criteria in Solid Tumors). Results: Low-energy images tend to overestimate residual lesions (6.28 mm) and subtraction images tend to underestimate them (2.75 mm). The sensitivity of low-energy images in forecasting CR amounted to 33.33%, while the specificity was 92.86%. In the case of subtraction CESM, the sensitivity amounted to 85.71% and the specificity to 71.42%. Conclusions: CESM is characterized by high sensitivity in the assessment of CR after NAC. The use of only morphological assessment is insufficient. CESM correlates well with the size of residual lesions on histopathological examination but tends to underestimate the dimensions.

**Keywords:** contrast-enhanced spectral mammography; breast cancer; neoadjuvant chemotherapy; complete response; response evaluation criteria in solid tumors
