Imaging Case 31:
Breast cancer - Invasive Ductal Carcinoma
Specimen imaging, particularly margin assessment, plays a crucial role in breast cancer surgery. Over the past 30 years, breast-conserving surgery (BCS) followed by radiation therapy has become the preferred standard of care for women with early-stage breast cancer. While BCS offers survival rates comparable to mastectomy, it provides superior cosmetic outcomes.
Successful BCS requires complete tumor excision with negative resection margins. However, positive margins are associated with a two- to threefold increase in ipsilateral breast tumor recurrence and are the primary reason for reoperation in BCS patients.
To ensure successful tumor removal, intraoperative margin assessment is a common practice during BCS. Techniques such as specimen radiography and frozen section analysis are widely used, yet each has limitations in terms of accuracy, efficiency, or practicality [1].
Recent publications have shown that high-resolution specimen PET-CT imaging with FDG-based radiotracers can provide an accurate view of the resected breast tumor specimen and may help enable assessing completeness of resection in a fast and efficient way [2,3]. In this clinical case, we demonstrate how intraoperative specimen PET-CT imaging enhances surgical confidence by offering a clear, real-time view of the resected tissue. This allows the surgeon to make immediate, informed decisions, optimizing surgical outcomes.
This case is presented with the support of AZ Maria Middelares, Ghent, Belgium, and is part of the investigator driven study to explore potential indications of an intraoperative specimen PET-CT imager (Trial registration number: BUN: B0172022000009).
Patient history
A 70-year-old female patient was diagnosed with breast cancer in her left breast. Preoperative imaging, including MRI, ultrasound, and mammography, revealed three small lesions: Two lesions located at the lower inner quadrant close to each other, and one lesion located superiorly. A suspicion of a fourth lesion was seen, also at the 5 o’clock region, however with inconclusive results. No lymph node metastases were detected.
Core biopsy confirmed the diagnosis of an invasive ductal carcinoma (IDC), NST, without chest-wall infiltration. The tumor was characterized as follows: progesterone receptor (PR) and estrogen receptor (ER) positive, HER2 negative, Ki-67 level at 10%, grade 2, and staging of T1bN0M0. Based on these findings, the patient was scheduled for breast-conserving surgery (BCS) with sentinel lymph node resection.
Figure 1: Transverse, coronal, and sagittal slices of the specimen PET-CT images of the first 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 confirmed the presence of the seed, providing reassurance that the correct lesion had been removed. The PET image showed diffuse low-grade uptake, probably correlating with normal breast tissue, but no focal region of uptake of the size expected by preoperative imaging (< 10 mm).
Specimen PET-CT imaging
Due to the small size of the lesions, three magnetic seeds were placed preoperatively for localization. The AURA 10 specimen PET-CT scanner was employed during surgery to get a clear 3D image of the resected specimen, helping the surgeon to verify complete resection of all target regions. The patient received an intramural injection of 99mTc for sentinel node localization, and was intravenously injected with 0.8 MBq/kg of 18F-FDG at the Nuclear Medicine Department. The patient was then transferred to the operating theatre and breast-conserving surgery was performed.
The surgeon removed three tumor lesions by excising two separate specimens:
First, the surgeon localized and excised the lesion at the superior position 90 minutes post-injection. Immediately after resection, a high-resolution specimen PET-CT scan was acquired in the operating room, see Fig. 1. These images confirmed the presence of the seed, providing reassurance that the correct lesion had been removed. The PET image showed diffuse low-grade uptake, probably correlating with normal breast tissue, but no focal region of uptake of the size expected by preoperative imaging (< 10 mm). Given the lesion's small size and the fact that a core biopsy had been performed preoperatively, it could be suspected that no residual tumor tissue remained in this area.
During the imaging of the first specimen, the surgeon resected a second specimen containing the remaining two lesions, located at the lower inner quadrant close to each other. Intraoperatively, an additional lesion was suspected via palpation. 113 minutes post-injection, this second tumor specimen was imaged with the AURA 10 specimen PET-CT scanner, revealing three distinct regions with increased 18F-FDG uptake: two containing a seed (1,2) and one identified by palpation (3), see Fig. 2. The 18F-FDG uptake of these regions was seen at a certain distance from the specimen border, and the surgeon deemed no additional shaving was necessary.
Figure 2: Transverse, coronal, and sagittal slices of the specimen PET-CT images of the second 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 three distinct regions with increased 18F-FDG uptake: two containing a seed (1,2) and one identified by palpation which had no preoperative correlation (3).
Figure 3: The (a) CT and (b) specimen PET-CT images of the sentinel lymph nodes. The PET tracer scale bar is depicted on the right-hand side. The CT images visualize two circular dense structures allowing confirmation that two lymph nodes were resected. The specimen PET-CT images of the lymph nodes showed no significant 18F-FDG uptake.
While the second specimen was being scanned, the sentinel lymph nodes were removed. At 130 minutes post-injection, a specimen PET-CT scan of the lymph nodes was taken, see Fig 3. The CT images (a) visualize two circular dense structures allowing confirmation that two lymph nodes were resected. The specimen PET-CT images (b) of the lymph nodes showed no significant 18F-FDG uptake.
Histopathological evaluation
After PET-CT imaging, the surgical specimen was sent to the pathology department for routine histopathological evaluation, which was available after seven days. The histopathological results are listed in Table 1.
For the specimen associated with the tumor lesion at 12 o’clock, no invasive component was found inside the specimen. The pathologist suspected that the invasive tumor was removed during biopsy. Only small lesions of DCIS and LCIS were detected.
The second specimen associated with two lesions located at the lower inner quadrant, revealed two grade 2 Invasive Ductal Carcinomas, NST measuring approximately 10 mm (superior located) and approximately 5 mm (inferior located). In addition, ductal carcinoma in situ (DCIS) was seen within and outside the invasive tumors, i.e., a spread area of approximately 20 mm surrounding the invasive tumor. Importantly, this DCIS component showed a clear focus outside the invasive components, for which margins were measured negative. Comparison with the specimen PET-CT images suggests that this focus correlates to the region of increased 18F-FDG uptake identified via palpation (3).The surgical margins for the invasive lesions were negative as well, with a minimum distance of 5 mm.
Histopathological analysis of the sentinel lymph nodes showed no evidence of tumor involvement in both nodes.
Table 1: Tumor and lymph node characteristics assessed by histopathological evaluation.
Discussion and conclusion
This case underscores the effectiveness of the specimen PET-CT imager in providing crucial information to the surgeon at the point of surgery that can be used to help them confirm resection of all target regions.
Notably, the first tumor specimen was confirmed to contain no invasive tumor, a finding consistent with intraoperative PET-CT imaging. For the second tumor specimen, three lesions were identified with specimen PET-CT: two preoperatively marked with magnetic seeds and one discovered through intraoperative palpation and specimen PET-CT imaging. The three lesions were confirmed by histopathology. The 18F-FDG uptake of these lesions was seen at a certain distance of the specimen border, correlating well with the completeness of the resection and alignment with histopathological findings.
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 ;