Abstract P1-20-24: Magnetic seed localisation as the new standard of care for nonpalpable breast lesion localisation: A comparison with hooked-wire localisation

Background and aims: Breast cancer is the most frequent type of cancer diagnosed in women. In breast surgery, screening programs and high-resolution imaging result in higher incidence of impalpable breast lesions, requiring preoperative localisation. Several localisation methods have been developed during the past decades. Since September 2018, Magseed® localisation has become standard of care in University Hospitals Leuven, providing an alternative for the widely used hooked-wire localisation method. The aim of this observational study was to compare hooked-wire localisation and Magseed® localisation in terms of oncological safety, clinical safety and surgeon satisfaction. Methods: Data of 100 patients who underwent Magseed® localisation were prospectively collected between September 2018 and April 2019, and retrospectively of 91 patients who underwent hooked-wire localisation between March 2018 and September 2018. Three patients received two Magseeds® resulting in a total of 103 seeds. Similarly, 11 patients received two hooked-wires so 102 wires were included in this study. Results: Baseline patient and tumour characteristics were similar between both groups. All magnetic seeds were placed under ultrasound guidance, with a median of two days in advance, resulting in logistical ease and more patient comfort. Occurrence of haematomas did not significantly differ between Magseed® and hooked-wire placement (2.97% vs 2.13% ; p = 1.000). 96.12% of the magnetic seeds were placed within 5 mm of the target, similar to 98.04% of the hooked-wires (p = 0.683). All seeds were retrieved during surgery, with an unambiguous detection by Sentimag® in 94.06%. The median ratio excised specimen volume to initial breast volume differs significantly between both groups in favour of hooked-wire (4.5% vs 3.7% ; p = 0.049), but the specimen volume itself is almost identical between the two groups. Positive surgical margin rate was lower for Magseed® compared to hooked-wire, although not significant (4.76% vs 10.39% ; p = 0.233). Due to positive margins, one additional mastectomy was performed in the Magseed® group. In contrast, three mastectomies and one additional excision were necessary in the hooked-wire group. 81% of the Magseed® procedures were scored as ‘easier than hooked-wire’ by our surgeons. Conclusion: The positive margin rate and associated re-excision/mastectomy rate was lower with Magseed® localisation compared to hooked-wire localisation. In addition, comparison of the complication rate showed an equal clinical safety profile. Also specimen volumes are similar with both localisation techniques. Moreover, the high surgeon satisfaction and logistical advantages designate Magseed® localisation as preferable over hooked-wire localisation.

Citation Format: Amelia Dehaene, Ann Smeets, Hanne Vos, Chantal Van Ongeval, Patrick Neven, Annouschka Laenen, Renate Prevos, Thomas Thywissen, Machteld Keupers, Ines Nevelsteen. Magnetic seed localisation as the new standard of care for nonpalpable breast lesion localisation: A comparison with hooked-wire localisation [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P1-20-24.

Contrast-enhanced spectral mammography in the evaluation of breast suspicious calcifications: diagnostic accuracy and impact on surgical management

Background

Detecting pathological breast calcifications remains challenging. Based on recent studies, contrast-enhanced spectral mammography (CESM) was shown to be superior compared to full-field digital mammography (FFDM).

Purpose

To evaluate the diagnostic accuracy of CESM in suspicious breast calcifications and its impact on surgical decision-making.

Material and Methods

All screening recalled patients with suspicious calcifications that underwent CESM in the period October 2012 until September 2015 were included. One experienced radiologist provided a BI-RADS classification for the FFDM images only. The evaluation was repeated for the CESM exam. In a simulated tumor board meeting, two breast surgeons decided on the preferred surgical treatment (breast conservation therapy [BCT] versus mastectomy) for all malignant cases. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated defining BI-RADS ≥4 as being malignant. In addition, differences in surgical decision-making were analyzed and compared using McNemar’s test.

Results

In total, 147 women were included in this study (mean age = 61 years; age range = 49–75 years). Pathology showed 82 benign and 65 malignant lesions, of which 33 were ductal carcinomas in situ and 32 were invasive lesions. Diagnostic performances of CESM (differences compared to FFDM in brackets) were: sensitivity 93.8% (+3%), specificity 36.6% (−2.5%), PPV 54% (0%), and NPV 88.2% (+4%). Based on low-energy images, surgeons suggested BCT in 89% of the cases. Based on the CESM exam, no statistical changes in decisions were observed (86% BCT, P = 0.453).

Conclusion

CESM only slightly improves the diagnostic accuracy of the evaluation of breast calcifications. It is not of added value compared to FFDM in guiding surgical decision-making.

Whole liver CT texture analysis to predict the development of colorectal liver metastases-A multicentre study

OBJECTIVES

CT texture analysis has shown promise to differentiate colorectal cancer patients with/without hepatic metastases.

AIM

To investigate whether whole-liver CT texture analysis can also predict the development of colorectal liver metastases.

MATERIAL AND METHODS

Retrospective multicentre study (n=165). Three subgroups were assessed: patients [A] without metastases (n=57), [B] with synchronous metastases (n=54) and [C] who developed metastases within ≤24 months (n=54). Whole-liver texture analysis was performed on primary staging CT. Mean grey-level intensity, entropy and uniformity were derived with different filters (σ0.5-2.5). Univariable logistic regression (group A vs. B) identified potentially predictive parameters, which were tested in multivariable analyses to predict development of metastases (group A vs. C), including subgroup analyses for early (≤6 months), intermediate (7-12 months) and late (13-24 months) metastases.

RESULTS

Univariable analysis identified uniformity (σ0.5), sex, tumour site, nodal stage and carcinoembryonic antigen as potential predictors. Uniformity remained a significant predictor in multivariable analysis to predict early metastases (OR 0.56). None of the parameters could predict intermediate/late metastases.

CONCLUSIONS

Whole-liver CT-texture analysis has potential to predict patients at risk of developing early liver metastases ≤6 months, but is not robust enough to identify patients at risk of developing metastases at later stage.

Rectal cancer: assessment of complete response to preoperative combined radiation therapy with chemotherapy--conventional MR volumetry versus diffusion-weighted MR imaging

PURPOSE

To determine diagnostic performance of diffusion-weighted (DW) magnetic resonance (MR) imaging for assessment of complete tumor response (CR) after combined radiation therapy with chemotherapy (CRT) in patients with locally advanced rectal cancer (LARC) by means of volumetric signal intensity measurements and apparent diffusion coefficient (ADC) measurements and to compare the performance of DW imaging with that of T2-weighted MR volumetry.

MATERIALS AND METHODS

A retrospective analysis of 50 patients with LARC, for whom clinical and imaging data were retrieved from a previous imaging study approved by the local institutional ethical committee and for which all patients provided informed consent, was conducted. Patients underwent pre- and post-CRT standard T2-weighted MR and DW MR. Two independent readers placed free-hand regions of interest (ROIs) in each tumor-containing section on both data sets to determine pre- and post-CRT tumor volumes and tumor volume reduction rates (volume). ROIs were copied to an ADC map to calculate tumor ADCs. Histopathologic findings were the standard of reference. Receiver operating characteristic (ROC) curves were generated to compare performance of T2-weighted and DW MR volumetry and ADC. The intraclass correlation coefficient (ICC) was used to evaluate interobserver variability and the correlation between T2-weighted and DW MR volumetry.

RESULTS

Areas under the ROC curve (AUCs) for identification of a CR that was based on pre-CRT volume, post-CRT volume, and volume, respectively, were 0.57, 0.70, and 0.84 for T2-weighted MR versus 0.63, 0.93, and 0.92 for DW MR volumetry (P = .15, .02, .42). Pre- and post-CRT ADC and ADC AUCs were 0.55, 0.54, and 0.51, respectively. Interobserver agreement was excellent for all pre-CRT measurements (ICC, 0.91-0.96) versus good (ICC, 0.61-0.79) for post-CRT measurements. ICC between T2-weighted and DW MR volumetry was excellent (0.97) for pre-CRT measurements versus fair (0.25) for post-CRT measurements.

CONCLUSION

Post-CRT DW MR volumetry provided high diagnostic performance in assessing CR and was significantly more accurate than T2-weighted MR volumetry. Post-CRT DW MR was equally as accurate as volume measurements of both T2-weighted and DW MR. Pre-CRT volumetry and ADC were not reliable.