Localization of Parathyroid Disease with ‘sequential Multiphase and Dual-Tracer’ Technique and Comparison with Neck Ultrasound

ObjectiveThe aim of the study was to evaluate the accuracy of the sequential multiphase and dual-tracer (SMADT) technique utilizing technetium-99m pertechnetate ((TcO4)-Tc-99m) and dynamic technetium-99m-2-methoxyisobutylisonitrile (Tc-99m-MIBI) with single-photon emission computed tomography/computed tomography (SPECT/CT) for localization of hyperfunctioning parathyroid tissue and compare the results with ultrasound (US).Materials and methodsSixty-four patients with hyperparathyroidism were scanned over 4 years. For the SMADT technique, 80MBq (TcO4)-Tc-99m was injected with dynamic thyroid image acquisition started at 20min, followed by 900MBq Tc-99m-MIBI injection at 30min; the dynamic imaging continued for 50min. SPECT was acquired at 60min, with SPECT/CT of the neck at 3h. Subsequent subtraction and statistical difference analyses were performed. Neck US was carried out within 3 months. Findings for each parathyroid gland and thyroid were classified as positive or negative. The patients underwent surgical resection of parathyroid tissue on the basis of imaging results. SMADT and US findings were correlated with histology as the gold standard.ResultsEighty-six histological samples were resected. The sensitivity of SMADT for localization to individual glands was 70.6% [95% confidence interval (CI)=58.1-80.7%] and that for neck US was 60.3% (95% CI=47.7-71.8%, P=0.26). Specificity was 94.4% (95% CI=70.6-99.7%) for SMADT and 72.2% (95% CI=46.4-89.2%) for neck US (P=0.13). Sensitivities in multigland disease were 63.6% (95% CI=31.6-87.6%) for SMADT and 36.4% (95% CI=12.4-68.4%) for US (P=0.37) and in nodular thyroid disease were 83.8% (95% CI=67.3-93.2%) and 66.7% (95% CI=48.9-80.9%), respectively (P=0.07).ConclusionSMADT results in better localization of varying parathyroid pathologies and complements the role of US in patients with multigland disease and nodular thyroid.