Intraoperative gamma probe guidance with ^99mTc-pertechnetate in the completion thyroidectomy

Intraoperative gamma probe (GP) guidance with ^99mTc-pertechnetate in the completion total thyroidectomy after a first thyroidectomy was investigated in this prospective study.

The study group comprises of fourteen consecutive patients (14 females, age mean 50.2 ± 12.0 years, age range 29–73 years). All patients underwent a second thyroidectomy due to inadequate (5/14 patients) and complementary (9/14 patients) interventions. Serum-free three iodothyronine, free thyroxin and thyroid stimulating hormone measurements, a neck ultrasonography (USG) and thyroid scintigraphy (TS) were performed in the preoperative and postoperative period. After a 185 MBq (5 mCi) injection of ^99mTc-pertechnetate, background (BG), left thyroid lobe (LTL), right thyroid lobe (RTL) and pyramidal tyroid lobe (PTL) regions were counted in time before and after resection of thyroid remnants by intraoperative GP. All resection materials were evaluated by histopathologic examination.

Preoperative TSH was less than 30 mIU/mL (mean 21 ± 7) in all patients. Functioning thyroid remnants were shown in 13/14 patients on the preoperative TS and USG, which were diagnosed by USG in one but by TS in other one. We calculated that percentage median (minimum–maximum) values were 220.90% (56.00–411.11%) in LTL, 80.43% (11.54–471.05%) in RTL and 66.60% (−3.33 to 158.33%) in PTL for counts before resection, on the other hand, 15.96% (−20.55 to 47.62%) in LTL, 17.59% (−15.07 to 38.46%) in RTL and 17.59% (−1.96 to 57.14%) in PTL regions for counts after resection. There were statistically significant differences between these values belonging to before and after resection for LTL (p = 0.001), RTL (p = 0.001) and PTL (p = 0.008). Bilateral small foci in a patient and unilateral focus in other patient were observed in postoperative TS. Unilateral focus was detected on the RTL by GP, but not bilateral foci. Postoperative TSH levels increased to 30 mIU/mL (mean 69 ± 26) at least. There was a statistically significant difference between preoperative and postoperative TSH values (p < 0.001). Histopathologic confirmation revealed that all removed materials were the thyroid tissues.

Gamma probe guidance with ^99mTc-pertechnetate seemed to be a good option and easy available method in patients undergoing the completion total thyroidectomy.