A comparison between 11C-methionine PET/CT and MIBI SPECT/CT for localization of parathyroid adenomas/hyperplasia

The purpose of this study was to compare the sensitivity of single-photon emission computed tomography/computed tomography (SPECT/CT) using 99mTc-sestamibi (MIBI) with that of PET/CT using 11C-methionine (MET) for localization of parathyroid adenomas/hyperplasia in primary hyperparathyroidism.

Twenty-three patients with primary hyperparathyroidism were analyzed. Fifteen patients underwent surgery, and the remaining eight did not, but these patients were clinically diagnosed as having primary hyperparathyroidism. Patients underwent both MET PET/CT and MIBI SPECT/CT scanning. The sensitivities of both modalities were evaluated on a per-patient basis, and on a per-lesion basis for parathyroid lesions detected by surgery. The size of the parathyroid adenoma/hyperplasia and serum intact parathyroid hormone levels were compared with the results of each of the two modalities.

Per-patient sensitivities of MET PET/CT and MIBI SPECT/CT were 65 and 61%, respectively. Per-lesion sensitivities of MET PET/CT and MIBI SPECT/CT were 91 and 73% for histologically confirmed adenomas and 30 and 30% for hyperplastic glands, respectively. No significant differences were observed between the two modalities. The size of uptake-positive lesions was significantly larger than that of uptake-negative lesions in both modalities. Intact parathyroid hormone levels showed no significant difference between uptake-positive and uptake-negative patients in both modalities.

The sensitivities of MET PET/CT and MIBI SPECT/CT were comparable. MET PET/CT has a complementary role in localizing parathyroid adenomas/hyperplasia when MIBI SPECT/CT is inconclusive.