sentinel lymph node biopsy for papillary thyroid cancer: the effect of dose, tracer and application of massage

Objective(s): in patients with papillary thyroid cancer (ptc), sentinel lymph node (sln) radio-guided biopsy is not routinely used for detection of involved neck lymph nodes (nln); 99mtc- antimony sulfide colloid (99mtc- asc) has been used for this purpose. in this study, besides 99mtc-asc another radiotracer, 99mtc-phytate (99mtc-p) with different doses and injection methods were evaluated. methods: twenty-two patients, scheduled to undergo thyroidectomy for ptc, were injected for radio-guided sln biopsy in the morning of operation in 3 groups: intra tumoral injection of about 1 mci 99mtc-p (group a; n=5); peritumoral injection of less than 3 mci 99mtc-asc (group b; n=6); and peritumoral injection of 3 to 5 mci 99mtc-asc with application of massage (group c; n=9). a patient refused to complete the study. a patient with follicular thyroid cancer was also excluded. no nln was detected in the pre-operative ultra-sonographic examinations of all patients. central neck dissection was done for all the participants. the presence of radio guided detected nln and results of pathology were assessed. results: in group a and b, no sln was detected. nlns were resected in 4 patients in group a and b; 2 of them involved by the tumor. in group c, 6 out of 9 patients (66.7%) had between 1 to 6 slns; the procedure failed to detect nln in a patient in group c with surgically resected reactive nln (failure rate 1 out of 7). conclusion: the results underscored the significance of sln radio guided biopsy in patients with ptc; the radiotracer, dose and method of injection may affect the detection rate.