Clinical impact of SPECT-CT in the diagnosis and surgical management of hyper-parathyroidism.

Unlabelled: Hyper-functioning parathyroid glands with autonomous overproduction of PTH is the most frequent cause of hypercalcemia in outpatient populations with primary hyper-parathyroidism. It is generally caused by a solitary adenoma in 80%-90% of patients. Despite the various methodologies that are available for preoperative localization of parathyroid lesions, there is still no certain preoperative imaging algorithm to guide a surgical approach prior to the management of primary hyper-parathyroidism (P-HPT). Minimally invasive surgery has replaced the traditional bilateral neck exploration (BNE) as the initial approach in parathyroidectomy at many referral hospitals worldwide. In our study, we investigated diagnostic contributions of SPECT-CT combined with conventional planar scintigraphy in the detection of hyper-functioning parathyroid gland localization, since planar imaging has limitations. We also evaluated the efficacy of preoperative USG in adding to initial diagnostic imaging algorithms to localize a parathyroid adenoma.

Methods: A total of 256 consecutive surgically naive patients with hyper-parathyroidism diagnosis were included in the following preoperative localization study. The study consisted of 256 consecutive patients with HPT, with a selected 154 patients who had neck surgery with definitive histology reports. All patients had 99mTc-methoxyisobutylisonitrile (99mTc-MIBI) double-phase scintigraphy. The SPECT-CT procedure, combined with standard 99mTc-MIBI planar parathyroid scintigraphy with a pinhole and parallel-hole collimator to evaluate whether the SPECT-CT procedure was able to provide additional information in the localization of the pathology, caused hyper-parathyroidism in both P-HPT and S-HPT.

Results: In the 154 P-HPT patients, 168 lesions (142 adenomas including 2 intrathyroidal and 2 double adenoma, 2 carcinoma, and 22 hyperplastic glands (four patients had MEN I, each with four hyperplastic glands)), were found at surgery. SPECT-CT detected more lesions than planar imaging in P-HPT (97.8% vs. 87.6%). SPECT-CT detected all adenomas and increased sensitivity, particularly in small lesions. Regardless of their size, the number of detected hyperplastic glands by SPECT-CT was remarkably higher than planar imaging.