Feasibility of Ex Vivo Margin Assessment with Hyperspectral Imaging during Breast-Conserving Surgery: From Imaging Tissue Slices to Imaging Lumpectomy Specimen

Developing algorithms for analyzing hyperspectral images as an intraoperative tool for margin assessment during breast-conserving surgery requires a dataset with reliable histopathologic labels. The feasibility of using tissue slices hyperspectral dataset with a high correlation with histopathology for developing an algorithm for analyzing the images from the surface of lumpectomy specimens was investigated. We presented a method to acquire hyperspectral images from the lumpectomy surface with a high correlation with histopathology. The tissue slices dataset was compared with the dataset obtained on lumpectomy specimen and the wavelengths with a penetration depth up to the minimum sample thickness of the tissue slices were used to develop a tissue classification algorithm. Spectral differences were observed between tissue slices and lumpectomy datasets due to differences in the sample thickness between both datasets; wavelengths with a high penetration depth were able to penetrate through the thinner tissue slices, affecting the captured signal. By using only wavelengths with a penetration depth up to the minimum sample thickness of the tissue slices, the adipose tissue could be discriminated from other tissue types, but differentiating malignant from connective tissue was more challenging.

Lumpectomy Specimen Radiography: Does Orientation or 3-Dimensional Tomosynthesis Improve Margin Assessment?

Purpose Our purpose was twofold. First, we sought to determine whether 2 orthogonal oriented views of excised breast cancer specimens could improve surgical margin assessment compared to a single unoriented view. Second, we sought to determine whether 3D tomosynthesis could improve surgical margin assessment compared to 2D mammography alone. Materials and Methods Forty-one consecutive specimens were prospectively imaged using 4 protocols: single view unoriented 2D image acquired on a specimen unit (1VSU), 2 orthogonal oriented 2D images acquired on the specimen unit (2VSU), 2 orthogonal oriented 2D images acquired on a mammogram unit (2V2DMU), and 2 orthogonal oriented 3D images acquired on the mammogram unit (2V3DMU). Three breast imagers randomly assessed surgical margin of the 41 specimens with each protocol. Surgical margin per histopathology was considered the gold standard. Results The average area under the curve (AUC) was 0.60 for 1VSU, 0.66 for 2VSU, 0.68 for 2V2DMU, and 0.60 for 2V3DMU. Comparing AUCs for 2VSU vs 1VSU by reader showed improved diagnostic accuracy using 2VSU; however, this difference was only statistically significant for reader 3 (0.73 vs 0.63, P = .0455). Comparing AUCs for 2V3DMU vs 2V2DMU by reader showed mixed results, with reader 1 demonstrating increased accuracy (0.72 vs 0.68, P = .5984), while readers 2 and 3 demonstrated decreased accuracy (0.50 vs 0.62, P = .1089 and 0.58 vs 0.75, P = .0269). Conclusions 2VSU showed improved accuracy in surgical margin prediction compared to 1VSU, although this was not statistically significant for all readers. 3D tomosynthesis did not improve surgical margin assessment.

Effect of LigaSure™, Monopolar Cautery, and Bipolar Cautery on Surgical Margins in Breast-Conserving Surgery

Background: We compared the differences in thermal damage at the surgical margin between monopolar cautery, bipolar cautery, and LigaSure™ in breast cancer lumpectomy specimens and assessed the effect of these techniques on the evaluation of the surgical margins. Methods: 30 patients scheduled for breast-conserving surgery for breast cancer were included in this study. During lumpectomy, each of the superior, inferior, lateral, and medial borders of the tumour was excised using one of the following: a scalpel, monopolar cautery, bipolar cautery, and LigaSure technology. The surgical margins of frozen and paraffin-embedded tissue sections of the lumpectomy specimen were evaluated. Thermal damage was defined as the maximum depth of thermal damage (in mm) from the surgical margin, and the level was categorized as none, low (≤1 mm), or high (>1 mm). Results: There was no statistically significant difference between monopolar cautery, bipolar cautery, and LigaSure in terms of thermal damage. There was no thermal damage at the surgical margin in tissues dissected by scalpel. Conclusion: Thermal damage due to the excision method may cause false-negative and false-positive results in the surgical margin evaluation of lumpectomy specimens. More research is needed on the effects of different energy modalities on surgical margin evaluation in breast-conserving surgery.

Breast density and the risk for positive lumpectomy margins.

50 Background: Current methods for intraoperative assessment of lumpectomy margins are limited, and a meaningful proportion of patients require re-excision to achieve acceptable margins. There is little available information regarding the relationship of mammographic breast density (BD) and positive margin rate. Methods: The MarginProbe device uses radiofrequency spectroscopy to evaluate the margins of lumpectomy specimens. The current study utilized data from the MarginProbe Pivotal Trial (Dune Medical Devices, Israel, NCT00749931). This randomized clinical trial compared adjunctive intraoperative use of the MarginProbe device with surgeons’ standard approach to lumpectomy surgery. For the current analysis, data was compiled from the period prior to patient randomization and device use. Variables of interest included BD, patient and tumor characteristics, and the margin status of the main lumpectomy specimen (prior to device use in the device arm). For the purpose of this analysis, a positive margin was considered tumor on ink. Statistical analysis was performed with univariate and multivariate analysis, and linear/logistic regression. Results: A total of 664 patients were enrolled in the trial. 450 patients had preoperative breast density information available, and formed the basis for this analysis. As expected, higher BD was associated with younger age, lower BMI and smaller breast and specimen volume. Increased BD was also associated with increased use of preoperative MRI imaging (odds ratio 2.2, p<0.0001). Higher BD was also associated with a significant increase in main lumpectomy specimen positive margin rate (Table). The odds ratio was 1.46 per change in density category (p=0.011). BD remained significantly associated with positive margins after controlling for age, BMI and breast volume. Conclusions: Higher BD is an independent risk factor for positive margins in main lumpectomy specimens, suggesting that adjunctive methods for intraoperative margin assessment may be particularly helpful in these patients. [Table: see text]