Imaging Case 28:
Breast cancer - Invasive Lobular Carcinoma
During breast-conserving surgery, intraoperative assessment of the resected tumor specimen is a common practice to determine whether the removal was complete. This is particularly important for patients with Invasive Lobular Carcinoma (ILC), who have a higher rate of positive margins. Traditional techniques such as specimen radiography, macroscopic evaluation, and frozen sections, while widely used, have limitations in terms of performance or efficiency [1].
Recent studies suggest that high-resolution specimen PET-CT imaging with FDG-based radiotracers can provide a precise visualization of the resected breast tumor specimen. This technique provides surgeons, in a fast and efficient way, information that can help evaluate resection completeness, potentially improving surgical decision-making [2,3].
In this case, we demonstrate how intraoperative specimen PET-CT imaging enhances confidence in the operating room, giving the surgeon a clear, real-time view of the resected tissue and the ability to take immediate action if necessary.
This case is part of the multi-center prospective BrIMA study (NCT04999917).
Patient history
A 75-year-old woman was diagnosed with Invasive Lobular Carcinoma in the left breast. The tumor size on preoperative imaging was approximately 20 mm. Biopsy showed a grade 2 tumor, with receptor status ER/PR/HER2+ and a Ki-67 level of 30%. Preoperative staging was cT1cN0M0. Based on these findings, the patient was scheduled for breast-conserving surgery (BCS) with sentinel node removal.
Figure 1: Transverse, coronal, and sagittal slices of the specimen PET-CT images of the tumor specimen, together with a 3D view. Specimen orientation is as indicated. The PET tracer scale bar is depicted on the left-hand side. These images reveal a clear region with increased 18F-FDG uptake.
Specimen PET-CT imaging
On the morning of the surgery, the patient received an intravenous injection of 0.8 MBq/kg of 18F-FDG at the Nuclear Medicine Department. Following administration, the patient was transferred to the operating theatre, where breast-conserving surgery was performed.
Approximately one hour after injection, the tumor specimen was resected via palpation. Immediately after resection, a high-resolution specimen PET-CT scan was acquired in the operating theatre. Fig. 1 presents three orthogonal views of the specimen PET-CT images, along with a 3D reconstruction. The PET images, displayed in color scale, are superimposed on the grayscale CT images.
The specimen PET-CT scan revealed increased 18F-FDG uptake at a clear distance from the specimen border in all directions. The 18F-FDG uptake was closest to the anterior border of the specimen Based on these findings, the surgeon opted not to perform a cavity shave. The specimen was then transported to the Pathology Department for macroscopic evaluation to assess the surgical margins. This evaluation confirmed complete resection, consistent with the specimen PET-CT findings where FDG uptake was seen at a clear distance from the border.
During the imaging of the main specimen, lymph node dissection was performed with the use of Magtrace and the sentimag system: One sentinel (1), one parasentinel (2) and one level 1 axilla (3) were resected. These nodes were imaged using the AURA 10 specimen PET-CT scanner, for which the circular dense structures show no significant 18F-FDG uptake, see Fig. 2.
Figure 2: Different slices of the specimen PET-CT images of the resected lymph nodes, together with a 3D view. The PET tracer scale bar is depicted on the left-hand side. During this procedure, one sentinel (1), one parasentinel (2) and one level 1 axilla node (3) was resected, for which the circular dense structures show no significant 18F-FDG uptake.
Table 1: Tumor and lymph node characteristics assessed by histopathological evaluation.
Histopathological evaluation
The histopathological results are listed in Table 1, which were available after several days. This postoperative final pathology showed that all margins were tumor-free, and no metastasis was found in the lymph nodes.
Discussion and conclusion
When correlating the PET-CT images with the pathology, the tumor and its negative margins could be located on the PET-CT images as a region of increased 18F-FDG uptake, at a clear distance from the tissue boundary. This information reassured the surgeon at the point of surgery, and no additional volume needed to be removed. This new technique gives the surgeon confidence to make a guided decision and optimize both clinical and cosmetic outcomes.
References
[1] St John et al. (2017). Diagnostic Accuracy of Intraoperative Techniques for Margin Assessment in Breast Cancer Surgery: A Meta-analysis. Ann Surg.
[2] Göker M. et al. (2020). 18F-FDG micro-PET/CT for intra-operative margin assessment during breast-conserving surgery. Acta Chirurgica Belgica. https://doi.org/10.1080/00015458.2020.1774163 ;
[3] Lambert B. et al. (2025) Feasibility study on the implementation of a mobile high-resolution PET/CT scanner for surgical specimens: exploring clinical applications and practical considerations. Eur J Nucl Med Mol Imaging. https://doi.org/10.1007/s00259-025-07143-z ;