Evaluation of lymphatic drainage of cold thyroid nodules with intratumoralinjection of Tc-99m nanocolloid

Purpose: The lymphatic system may show variations throughout the entire bod y, Knowledge of the variations and aberrant lymph drainage are important wh en planning surgical treatment and radiotherapy. The aim of this study was to evaluate the intratumoral injection technique in the detection of lympha tic drainage of proved or possibly malignant cold thyroid nodules, Materials and Methods: The study group consisted of 13 patients with palpab le solitary cold thyroid nodules, None of the patients had cystic nodules o n ultrasound examination. After fine-needle aspiration biopsy (at least 3 d ays later), 15 MBq (0.4 mCi) Tc-99m nanocolloid particles in a small volume (0.2 mi) were injected into the nodule, Dynamic images (60 frame x 1 minut e) were acquired during the first hour, followed by static anterior and lat eral images at 90 and 120 minutes. Results: Radiopharmaceutical was present in the systemic circulation in two patients, possibly as a result of paratumoral injection. Eleven patients h ad intratumoral accumulation in early frames. Lymph nodes draining the thyr oid nodule were visualized in 10 of 11 patients. In the dynamic acquisition period of 7 of 10 patients, the first draining lymph node could also be id entified. Only 5 of 13 patients had malignant nodules, Lymphatic metastases were detected in one patient's specimens, Conclusions: Preoperative visualization of lymphatic pathways may be used w hen planning for thyroid cancer surgery. Sentinel node detection could yiel d valuable additional information in these patients.