Abstract
Background: Primary tumour biology and axillary lymph node status are crucial prognostic factors in breast cancer treatment. The LowMag trial introduced a magnetic sentinel lymph node biopsy (SLNB) procedure using a Superparamagnetic Iron Oxide (SPIO) tracer and handheld magnetometer as a radiation-free alternative for axillary staging. The objective of this clinical pilot study was to assess a low-dose magnetic tracer for non-invasive preoperative evaluation of lymph node metastases and intraoperative SLN detection to achieve accurate imaging in the diagnostic phase. This may save axillary surgery in 80% of patients without lymph node metastases.
Methods: Patients with confirmed invasive breast cancer or ductal carcinoma in situ, eligible for SLNB, were included in the LowMag trial (NTR 4858, http://www.trialregister.nl) consisted of radioactive and magnetic SLNB. The SLNs were perioperatively detected by Sentimag® (counts were documented), and inked to keep track of spatial orientation between MRI and histopathology. Amount of iron was estimated post-surgery using two magnetic devices: SPaQ and Sentimag®. Additional ex vivo MRI was acquired using low-field MRI system (Pure Devices). After buffered in formalin fixation, the LN were lamellated perpendicular to the MRI planes, and consecutively sectioned at 2 μm distance and stained with H&E, Perls Prussian blue, CK8/18 and CD68.
Results: In an interim assessment of 20 LNs (nine patients) two LNs from two patients contained a metastasis. The analysis revealed good concordance of uptake between magnetic and radioactive tracer. Median amount of iron trapped in the LN was 19.21 μg (ranging from 0.1 pg to 109 μg). In pathology, iron particles were observed in both the subcapsular space and sinusoids of healthy LNs, with macrophages located in proximity. In the metastatic LNs, tumour cells were observed in both subcapsular and parenchymal regions, primarily situated in the central area. There was limited infiltration into the adjacent adipose tissue, and sinusoids. Regions occupied by tumour cells show no iron infiltration.
In MRI, healthy LN with low iron content shows a centrally located fatty region without iron uptake. Healthy tissue regions within metastatic LNs exhibit a behaviour similar to that of the healthy LNs. In the metastatic sites, there was a reduced presence of iron contrast.
Conclusion: The MRI images clearly differentiate between fat, nodal tissue and SPIO tracer (either in signal intensity or in texture), demonstrating a potential of LN imaging using a low-field MRI system.
Methods: Patients with confirmed invasive breast cancer or ductal carcinoma in situ, eligible for SLNB, were included in the LowMag trial (NTR 4858, http://www.trialregister.nl) consisted of radioactive and magnetic SLNB. The SLNs were perioperatively detected by Sentimag® (counts were documented), and inked to keep track of spatial orientation between MRI and histopathology. Amount of iron was estimated post-surgery using two magnetic devices: SPaQ and Sentimag®. Additional ex vivo MRI was acquired using low-field MRI system (Pure Devices). After buffered in formalin fixation, the LN were lamellated perpendicular to the MRI planes, and consecutively sectioned at 2 μm distance and stained with H&E, Perls Prussian blue, CK8/18 and CD68.
Results: In an interim assessment of 20 LNs (nine patients) two LNs from two patients contained a metastasis. The analysis revealed good concordance of uptake between magnetic and radioactive tracer. Median amount of iron trapped in the LN was 19.21 μg (ranging from 0.1 pg to 109 μg). In pathology, iron particles were observed in both the subcapsular space and sinusoids of healthy LNs, with macrophages located in proximity. In the metastatic LNs, tumour cells were observed in both subcapsular and parenchymal regions, primarily situated in the central area. There was limited infiltration into the adjacent adipose tissue, and sinusoids. Regions occupied by tumour cells show no iron infiltration.
In MRI, healthy LN with low iron content shows a centrally located fatty region without iron uptake. Healthy tissue regions within metastatic LNs exhibit a behaviour similar to that of the healthy LNs. In the metastatic sites, there was a reduced presence of iron contrast.
Conclusion: The MRI images clearly differentiate between fat, nodal tissue and SPIO tracer (either in signal intensity or in texture), demonstrating a potential of LN imaging using a low-field MRI system.
| Original language | English |
|---|---|
| Article number | 113752 |
| Journal | European journal of cancer |
| Volume | 200 |
| Issue number | Supplement 1 |
| DOIs | |
| Publication status | Published - 1 Mar 2024 |
| Event | 14th European Breast Cancer Conference, EBCC 2024 - Allianz MiCo • Milano Convention Centre, Milan, Italy Duration: 20 Mar 2024 → 22 Mar 2024 Conference number: 14 |
