Iodine-125 seed implantation treatment of lung metastases < 2.5 cm using 5-ml syringe as a guide

Small lung metastases change their location with respiration, making difficult to localize, therefore, increasing the number of punctures. Accurate puncture can reduce trauma to lung tissue and accelerate patient's recovery. The aim of the study was to present our experience with the technique of using local anesthesia 5-ml syringe as a guide for computerized tomography-guided iodine-125 seed implantation (CT-ISI).

This was a retrospective study, including patients with small metastatic tumors in the lung, treated with CT-ISI between December 2013 and March 2018 at the Affiliated Hospital of the University. The patients were divided according to whether a 5-ml syringe was used as a guide during CT-ISI or not. The final follow-up was on March 31^st, 2018. Implantation success and complications were examined.

Nineteen patients were included. A total of 840 seeds were used, with 44.2 ±33.6 (range, 10-160) seeds per patient. The mean D₉₀ for CT-ISI was 134.5 ±7.5 Gy. Treatment intervention for eleven patients was performed using a 5-ml syringe as a guide during CT-ISI. There were no differences in total dose and number of implanted seeds between the two groups, but the number of punctures per lesion was lower in the syringe group than in the no-syringe group (1.9 ±0.5 vs. 2.9 ±0.6, p < 0.001), suggesting a higher puncture accuracy. The total number of SMTIL was 50 (median, 2; range, 1-10), and the median size was 1.9 cm (range, 0.8-2.4 cm). All SMTIL were well-controlled at 6-months follow-up (response rate [RR] = 100%). One patient in the no-syringe group experienced grade 2 chest tightness, chest pain, intraoperative needle tract bleeding, and post-operative blood in sputum.

Puncture with a 5-ml syringe as a guide during CT-ISI seems to be a more accurate option for patients with small (< 2.5 cm) lung metastasis.