OBJECTIVEUsing radioactive nano tracer with different sizes (average diameter were 50, 80 and 100 nm) and dosages (0.01 and 0.02 ml) in the thyroids of rabbits, to study the drainage of thyroid to cervical lymph nodes (LNs) in rabbits and to provide experimental evidence for the choice of ideal sizes and dosages of radioactive Nano tracer for the sentinel lymph node biopsy (SLNB) in thyroid cancer patients.

METHODSThirty adult rabbits were randomly divided into six groups (50 nm - 0.01 ml, 50 nm - 0.02 ml, 80 nm - 0.01 ml, 80 nm - 0.02 ml, 100 nm - 0.01 ml, 100 nm - 0.02 ml of (99m)Tc-Sb(2)S(3)) with five rabbits in each group. A total of 60 sides of thyroids were included. The mean number of LNs with radioactivity, the initial, the strangest and the lasting time of radioactivity in LNs in each group were measured.

RESULTSOne to three LNs were identified in one side neck of rabbits, totally 86 LNs. Most of LNs with radioactivity existed in level VI, counting for 75.6% (65/86). (99m)Tc-Sb(2)S(3) with 50 nm particles was significantly better than that with 80 nm or 100 nm particles with regarding the initial and the strangest radioactive time of (99m)Tc-Sb(2)S(3) in LNs (P < 0.05). There were no significant difference in the mean number of LNs with radioactivity, the initial, the strangest and the lasting time of radioactivity between the dosages of 0.01 ml and 0.02 ml of (99m)Tc-Sb(2)S(3) with same size of particles (P > 0.05).

CONCLUSION(99m)Tc-Sb(2)S(3) with 50 nm particles, in the dosage of 0.01 ml or 0.02 ml, could be good choice for SLNB of thyroid cancer.