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

Purpose: To assess the diagnostic value of dual-phase Tc-99m 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. Materials and Methods: Tc-99m 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. Results: 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). Conclusions: Dual-phase Tc-99m 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.