Value of 99mTC-sestamibi SPECT/CT fusion over planar pinhole scintigraphy in the evaluation of parathyroid adenoma or hyperplasia

Abstract

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Objectives: Parathyroid scintigraphy with 99mTc-sestamibi has been shown to be a sensitive and specific method for the detection and localization of parathyroid adenomas (PA)in patients with primary hyperparthyroidism (PH). Moreover, pinhole collimator has proven to increase the sensitivity of planar parallel hole collimator in detection of PA. The purpose of the study was to evaluate the additional value of fusion single-photon computed tomography (SPECT) and computed tomography (CT) images in locating PA compared with planar pinhole findings in patients with PH. Methods: Ten consecutive patients(8 women,2 men;age range 41-78 years) with biologically proven PH were included in the study. In all patients cervical ultrasound (US) and double phase scintigraphy after injection of 740 MBq of 99mTc-sestamibi were performed. Anterior planar pinhole images of the neck and anterior planar parallel hole images of the chest were acquired 15 min and 90 min after injection, followed by SPECT and SPECT/CT using a dual-detector scintillation camera (Symbia T2, Siemens). Results: While US was non-contributive in 6/10, double phase pinhole scintigraphy was positive in 9 of 10 patients detecting 9 solitary parathyroid adenomas, 7 in the neck and 2 ectopic adenomas. All were identified in SPECT images and confirmed in SPCT/CT with a precise location in 5 of them. The 2 ectopic adenomas and the 3 retrotracheal adenomas were accurately identified and located by SPECT/CT fusion. Both planar pinhole and SPECT/CT scintigraphy was false-negative in one patient who had negative US findings. Conclusions: Anatomical information provided by CT enables precise location of the functional abnormalities identified by planar pinhole images and 99mTc-sestamibi SPET/CT fusion seems to be useful for a correct surgical approach of primary hyperparathyroidism.