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 tissue's 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 specimens' 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, Nölke 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.

Abstract P1-01-02: The SentiMag study: Sentinel node biopsy with superparamagnetic iron oxide vs. radioisotope

Background:

The SentiMag study compares the “gold standard” 99mTc with a new technique, which employs superparamagnetic iron oxide particles (SPIO) for localization of sentinel lymph nodes. Aim of this study is to investigate the potential equivalency of the SentiMag® technique in comparison to the gold standard of sentinel lymph node biopsy (SLNB).

Materials and methods:

In a prospective, multicentre and multinational 2-arm study, 150 patients with histologically verified breast carcinoma are examined. For comparison, SLNs are marked initially with radioisotope following a 1- or 2-day protocol. Additionally, SPIO (Sienna+®) is injected in the operation room by the surgeon at least 20 minutes before SLNB into the subareolar interstitial tissue, followed by 5 minutes massage. SLN-detection is carried out using a magnetometer (SentiMag®) and a gamma probe. Preparation and excision of lymph nodes is conducted using both techniques in a parallel manner. All lymph nodes marked with either tracer are excised.

Results:

Interim analysis of 138 patients resulted in a detection rate concordance per patient of 97% (134/138). An average of 1.9 (radioisotope) and 2.0 (SPIO) lymph nodes were collected per patient. Nodal detection rate was 92% (250/273) for the radioisotope vs. 97% (265/273) for the SPIO tracer with magnetometer detection. The proportion of pathologically positive lymph nodes was 38/250 (15%) vs. 39/265 (15%) for the radioisotope and the SPIO tracer respectively. All pathologically positive lymph nodes detected with the conventional technique (radioisotope) were also detected with the new technique (SentiMag®).

Conclusions:

The SentiMag® provides an easy technique which can be rapidly implemented into daily routine. Due to the simple handling, preoperative efforts can be reduced to a minimum. If further and consistent results prove its efficacy, this technique may ultimately replace the standard of care.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-01-02.