Preoperative [ 99m Tc]MIBI SPECT/CT Interpretation Criteria for Localization of Parathyroid Adenomas-Correlation with Surgical Findings.

PURPOSE: Minimally invasive surgery for parathyroid adenomas (PTA) requires precise identification and localization of the diseased gland prior to exploration for optimal surgical planning. The Perrier classification allows for accurate, reproducible, and reliable description of PTA location and communication of clinically significant information to surgeons. The current study compares the Perrier localization of PTA on [99m Tc]methoxyisobutylisonitrile ([99m Tc]MIBI) single-photon emission computed tomography (SPECT)/X-ray computed tomography (CT) with the results of surgery.

PROCEDURES: Eighty-eight patients (60 females), age 13-82 years, with primary hyperparathyroidism underwent [99m Tc]MIBI SPECT/CT prior to surgery. Eight patients had parathyroid hyperplasia and underwent excision of 3.5 parathyroid glands, including five patients with a negative [99m Tc]MIBI study and three patients with multiple foci of uptake, and were excluded from further analysis. Each PTA was localized to Perrier levels A-G. The surgeon located each PTA found on surgery using the same classification. PTA localization on SPECT/CT and at surgery was compared.

RESULTS: Eighty patients with surgically confirmed PTA were analyzed. On [99m Tc]MIBI SPECT/CT, 63 patients had a single and one patient had two PTAs for a total of 65 PTAs. At surgery, 85 PTAs were resected in 80 patients, including 75 patients with single and 5 with two PTAs. Twenty PTAs found on surgery were not detected on [99m Tc]MIBI. The relatively lower weight of these 20 PTAs is probably the main reason for the false-negative results group. The same Perrier localization was determined on SPECT/CT and surgery in 52/65 PTAs (80 %). In the 13 incongruent cases, the PTAs were localized at different locations but on the same side of the thyroid gland.

CONCLUSIONS: [99m Tc]MIBI SPECT/CT accurately localized a PTA according to the Perrier classification in 80 % of cases. Reporting SPECT/CT results using anatomy-based PTA localization criteria accepted by surgeons can contribute significantly towards better interspecialty communication and will improve performance of minimally invasive surgical removal of PTAs.