Can thallium-pertechnetate subtraction scanning play a role in the preoperative imaging for minimally invasive parathyroidectomy?

PURPOSE: Preoperative Tc-99m sestamibi scanning can identify candidates for minimally invasive parathyroid surgery. However, a significant number of patients with single gland disease have negative scans and are not considered for the minimally invasive procedure.

MATERIALS AND METHODS: To determine if T1-201/Tc-99m sodium pertechnetate subtraction scanning (TPSS) is a viable alternative imaging technique for patients with primary hyperparathyroidism (1 degrees HPTH), we reviewed our experience. The outcomes of 100 consecutive patients with 1 degrees HPTH who underwent preoperative TPSS and parathyroid exploration between 1995 and 2000 at our institution were retrospectively reviewed.

RESULTS: The mean preoperative calcium and parathyroid hormone levels were 10.8 mg/dL and 220 pg/mL, respectively. The overall cure rate was 96%. Single gland disease was present in 88%. Of the 100 patients studied, 15 underwent both a Tc-99m sestamibi scan and TPSS, whereas the other 85 had only the TPSS.

CONCLUSIONS: The sensitivity and positive predictive value of the TPSS were 73.3% and 90.4%, respectively. In the patients undergoing both TPSS and Tc-99m sestamibi scans, the results concurred in 60%. However, in 20% of the remaining patients, TPSS correctly localized the abnormal parathyroid(s) when Tc-99m sestamibi failed. TPSS has a comparable sensitivity and positive predictive value to Tc-99m sestamibi scanning. In patients with a negative Tc-99m sestamibi scan, TPSS can provide additional localizing information. As a result of the high positive predictive value of TPSS, a single parathyroid gland localized by TPSS alone can then be approached by minimally invasive parathyroidectomy.