Dual-Phase 99mTc Sestamibi Scintigraphy With Neck and Thorax SPECT/CT in Primary Hyperparathyroidism

Abstract

To assess the diagnostic value of dual-phase (99m)Tc sestamibi scintigraphy with neck and thorax single-photon emission computed tomography/computed tomography (SPECT/CT) in patients with primary hyperparathyroidism, and to analyze the relationships between SPECT/CT data and serum calcium or parathyroid hormone (PTH) concentrations. (99m)Tc sestamibi scintigraphy was performed in 94 consecutive patients. Images included early and delayed planar neck images and delayed neck and thorax SPECT/CT. Scintigraphy was scored positive or negative. Fifty-nine sestamibi studies (63%) were positive. SPECT/CT demonstrated a single focus in 56 patients, in usual parathyroid sites in 80% of cases and in unusual sites in the remaining 20% (retrotracheal area, 7%; intrathyroidal, 9%; mediastinum, 4%), and double foci in 3. Serum calcium values were higher in patients with a positive scintigraphy than in those with a negative scintigraphy (2.80 vs. 2.66 mmol/L, P = 0.001) with similar figures for serum PTH values (129 vs. 107 pg/mL, P = 0.0649). In patients with a measurable parathyroid adenoma on integrated CT scan (n = 43), the greatest axial diameter of the adenoma was correlated to serum calcium (r = 0.405, P < 0.0071) or PTH concentrations (r = 0.589, P < 0.0001). Fifty-four patients underwent surgery, 45 with a positive, and 9 with a negative preoperative scintigraphy, resulting in a sensitivity of 92% (95% CI: 80-98) and a specificity of 83% (95% CI: 36-100). Dual-phase (99m)Tc sestamibi scintigraphy with SPECT/CT enables to identify a parathyroid adenoma in about two-thirds of patients with primary hyperparathyroidism and allows the surgeon to plan appropriate surgery. The likelihood of scintigraphy to be positive is affected by calcium or PTH concentrations.