Preoperative low-dose intradermal SPIO increases lymph node magnetic signal: multi-cohort study
Ione Linné, Désirée Bourghardt Wiklund, Sarah Palm, Aniko Kovacs, Abdi-Fatah Hersi, Nushin Mirzaei, Andreas Karakatsanis, Staffan Eriksson, Roger Olofsson Bagge, Fredrik Wärnberg, Kian ChinAbstract
Introduction
SPIO-guided sentinel lymph node biopsy (SLNB) is established in breast cancer surgery. Low-dose SPIO (0.1 ml) has shown comparable detection rates to standard doses, but its effect on magnetic signal intensity is unclear. This study compared two SPIO injection protocols.
Methods
Patients from two prospective cohort studies undergoing SLNB were included. The Low-dose group received 0.1 ml intradermal SPIO 1–7 days preoperatively. The High-dose group received 1.5 ml periareolar SPIO on the day of surgery. Primary endpoint was highest lymph node signal intensity per patient. Groups were compared using non-parametric tests and multivariable linear regression.
Results
A total of 139 patients were included. Median signal intensity was higher in the Low-dose group than in the High-dose group (3000 versus 580 counts; P < 0.001). Highest signal was found in the first removed node in 80 versus 71% (P = 0.47). High-dose protocol was independently associated with 94% lower signal intensity versus Low-dose (95% c.i. 77–98%; P < 0.001).
Discussion
Low-dose intradermal SPIO was associated with higher magnetic signal intensity than same-day high-dose periareolar injection. Injection technique and timing may improve SLNB performance and optimise future SPIO protocols