Efficacy of in-vivo counting in parathyroid radioguided surgery and usefulness of its association with scintigraphy and intraoperative PTHi.

AIM

To evaluate the efficacy of the γ probe, alone and in combination with other techniques, in primary hyperparathyroidism surgery, as well as its ability to distinguish between single-gland and multiple-gland diseases.

MATERIALS AND METHODS

Sixty-three patients with primary hyperparathyroidism submitted to radioguided parathyroidectomy, with a minimum follow-up of 1 year, were included. A preoperatory scintigraphy with technetium-99m methoxyisobutylisonitrile was performed in all cases and the excised specimens were histopathologically examined. Intraoperative intact parathyroid hormone (ioPTHi) data were available for 59 patients.

RESULTS

Sixty-three patients underwent radioguided parathyroidectomy: 30 minimally invasive radioguided parathyroidectomy, 18 unilateral, and 15 bilateral surgeries. A receiver operating characteristic curve analysis was carried out to distinguish between normal and pathological glands. Using a cut-off value of 1.15 for the γ-probe in-vivo index, we obtained 87% sensitivity, 95% specificity, and 97% positive predictive value (PPV). There were statistically significant differences among in-vivo indexes sorted by type of gland histology (Kruskall-Wallis; P=0.001). A receiver operating characteristic curve was again used to discriminate between single-gland and several-gland pathologies. For a cut-off of 1.51, we achieved 67% sensitivity, 87% specificity, and 95% PPV.

CONCLUSION

Pathological glands can be detected by the γ probe (in-vivo index>1.15) with a PPV of 97%. Although an in-vivo index greater than 1.51 is suggestive of a solitary adenoma (PPV=95%), there are a significant number of cases (27%) with lower indexes, these would erroneously lead to an extended surgery in search of a multiglandulary disease. For this reason, the combined determination of the intraoperative intact parathyroid hormone is recommended to identify multiglandulary disease.