39. First implementation in France of nonpalpable breast lesions localization using an 125I-seed (radioactive)

Introduction For the excision of nonpalpable breast lesions, the surgeon needs a landmark previously placed under radiological or ultrasound imaging control. The current technique consists in implanting a metal wire from the lesion to the skin, which presents some constraints in terms of patient comfort, surgery precision (potential wire migration) and medical organization. Here is presented the implementation of breast lesion localization using an 125 I radioactive seed as part of a mononoclinical trial comparing the wire-guided and radioguided techniques. Today, a feedback over 18 patients enables a first report on this technique. Methods In order to insure the feasibility of the iodine seed (IsoSeed® - Eckert & Ziegler) technique, the radiopaque and echogenic seed’s features were checked. In the surgery room, the iodine seed (A  125 I, 99mTc-nanocolloid is used to guide the sentinel node biopsy which comes with every breast lesion excision. The influence of 99mTc (140 keV) on the 125 I (27 keV) detection was studied. The radioprotection concerning the medical staff, the patient and his entourage was assessed using the brachytherapy software VARISEED®. Before the clinical implementation of the technique, the whole protocol (implantation, excision and anatomopathology) was simulated using a piece of meat. Results The seed is visible under X-Ray and ultrasound imaging. Thus this localization technique is possible, as well as the control of the seed presence into the lesion using Faxitron imaging (X-Ray). The 11 mm diameter probe was approved by the surgeons. With a 1.5 cm focalization (FWHM of the radial sensitivity curve), it offers the best compromise sensitivity/focalization. In light of the clinical activities, the scattered radiation of 99mTc does not trouble the 125 I seed detection. For a seed implanted at 1, 2 and 3 cm depth, the breast skin dose was respectively evaluated at 2.2, 0.5 and 0.2 mGy/MBq/day. The highest activity and implantation duration being 10 MBq and 10 days, there is no contraindication to this technique due to radioprotection. The simulation using the piece of meat led to validate every step of the protocol with the different operators and thus resolve every major difficulty in relation to this technique. Conclusions The 18 iodine seed localizations (activity: 4.4 ± 1.5 MBq (1 σ ) , presence duration in the breast: 4.6 ± 3 days (1 σ ) ) were successful and enabled to optimize the established protocol. They confirm that this technique brings the solution to the constraints linked to the wire-guided localization: the seed positioning and the surgery gesture are made easier, the patient comfort is unquestionably improved and the medical organization flows better. Today, no seed migration has been observed, which may also promise a gain in precision.