Abstract P2-14-23: Successful intraoperative margin assessment in DCIS and invasive breast cancer with diffuison-weighted MRI using the Clearsight™ system

Aim Aim of our study is to evaluate the performance of the ClearSight™ system (ClearCut Medical, Ltd.) in assessing surgical margins for DCIS and IBC in breast conserving surgery Material and Methods The ClearSight™ system utilizes a diffusion-weighted-imaging (DWI) protocol to create 2D surface maps showing T2*, a MR parameter related to the tissue9s apparent diffusion coefficient (ADC), with a depth penetration of 1.5mm. ADC is a highly accurate differentiator for irregular versus normal tissue. From November 2017 a prospective, blinded post marketing study (N=63), evaluating the performance of the ClearSight™ system has been conducted in the Breast Centre at the Agaplesion Markus Krankenhaus, Frankfurt, Germany. After standard evaluation with ultrasound and/or X-ray, the specimens were scanned with the ClearSight™ system, and results were compared with the final histopathology results on a margin per margin bases, applying a simple T2* threshold to flag irregular tissue. Results Breast specimens9 margins from 60 patients were analyzed. Pursuant to the breast conserving surgery (BCS), 348 margins were scanned by the ClearSight™ system. A rigid T2* threshold comparison with the pathology findings resulted in a sensitivity of 80% and specificity of 84%. Accuracy for invasive and in-situ cancers was found to be similar for tissues scanned within one hour after excision. After that sensitivity for DCIS started to drop and was found to be 56% after 2 hours. Further accuracy improvements can be achieved if the reading physician is free to apply an intuitive diffusion map interpretation rather than adhere to a fixed threshold. Conclusion The data suggest that ClearSightTM can reduce excision rates by a robust 80% if the excised breast tissue is scanned within one hour. Tissue drying impacts sensitivity for DCIS negatively. Free map interpretation leads to better results than a fixed threshold. Citation Format: Thill M, Kelling K, van Haasteren V, Traub L, Nolke J, Szwarcfiter I, Shapiro M, Schon A, Aulmann S. Successful intraoperative margin assessment in DCIS and invasive breast cancer with diffuison-weighted MRI using the Clearsight™ system [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-14-23.