Preoperative localization of parathyroid adenoma in video-assisted era: is cervical ultrasound or 99mTc Sesta MIBI scintigraphy better?

BACKGROUND: Endocrine surgeon localizes solitary adenoma (SA) in preoperative time by cervical ultrasound (c-US) and/or 99mTc Sesta MIBI scintigraphy (MIBI-S), but in clinical practice they often show discordant results. The aim of our study is to verify if c-US and MIBI-S have different sensitivity in preoperative localization of SA, depending on its localization, in planning minimally invasive video-assisted parathyroidectomy (MIVAP).

METHODS: This is a retrospective analysis of data (demographics data, preoperative localization of SA by US and MIBI-S, presence of associated thyroid disease, preoperative calcemia, preoperative serum PTH, surgical time, intraoperative PTH values, day 1 postoperative calcemia, definitive histological report) about patients consecutively submitted to MIVAP because of SA between January 2011 and January 2014 in the department of endocrine and general surgery of the University Hospital of Parma (Italy). The data, expressed as percentages (%) and means (±SD), were analyzed with SPSS Statistics 22.0 program.

RESULTS: The c-US detected 56.25% of the superior SA (9/16 patients) and it failed to identify 7 superior adenomas (43.75%); MIBI-S identified 6/16 superior SA (37.5%) and failed in the identification of 10 superior adenomas (62.5%). For inferior SA, c-US was positive in 39/45 patients (86.66%) and falsely negative in 6/45 patients (13.33%); MIBI-S correctly showed 31/45 inferior adenomas (68.88%) and it was falsely negative in 14/45 patients (31.11%). MIBI-S showed decreased sensitivity in the identification of superior SA (P=0.0383). C-US had a high sensitivity in the identification of the inferior SA (P=0.0280).

CONCLUSIONS: C-US and MIBI-S are the best diagnostic tools for preoperative localization of SA, but both have decreased sensitivity in the presence of a concomitant thyroid diseases. In our experience c-US showed high sensitivity in the identification of inferior SA and MIBI-S showed a decreased sensitivity in the identification of superior SA. Discordant results in the identification of SA did not contraindicate MIVAP. Intraoperative parathormone dosage is fundamental to guide the endocrine surgeon and to verify the completeness of surgical resection.