ObjectiveTo investigate the increasing value of SPECT/CT fusion imaging with a dual-phase and dual-tracer technique for localizing parathyroid lesions in an unselected patient cohort with hyperparathyroidism.

MethodsPatients with biochemically confirmed hyperparathyroidism were included in a prospective trial. The baseline values of all laboratory parameters were determined 1-2 weeks before ⁹⁹Tc^m-MIBI parathyroid scintigraphy was performed. Afterward, 40-60 MBq ⁹⁹Tc^mO₄^- was injected with static thyroid image acquisition, followed by 600 MBq ⁹⁹Tc^m-MIBI injection. SPECT/CT was acquired immediately. With ⁹⁹Tc^m-MIBI additional delayed imaging were acquired. Patients were subjected to a subtraction protocol. Surgical and histological findings were used as the standard of comparison, sensitivity and specificity were calculated, and McNemar test and Wilcoton test were conducted to compare them at a significant level of 0.05.

ResultsThe preoperative parathyroid hormone(PTH) levels of primary and secondary hyperparathyroidism were (102.4±88.8), (98.2±53.6) pmol/L, and the serum calcium level was (2.9±0.3), (1.9±0.2) mmol/L respectively. After surgical examination was completed, 40 enlarged parathyroid glands were found in 28 patients. Of these patients, 21 had single adenoma, and 7 had a multi-gland disease. The dual-phase technique could be used to accurately detect and diagnose parathyroid disease in 19 of 40 histological samples. The sensitivity and specificity for parathyroid disease localization were 47.5%(19/40). For those who yielded negative results and underwent the subtraction phase, five other lesions were detected, indicating an increased detection sensitivity(60.0%), the difference was significant(χ²=2.761, P=0.125). Furthermore, 26 of 40 histological samples were diagnosed with SPECT/CT fusion imaging, 25 hyperparathyroidism lesions were detected with dual-phase and subtraction-combined analysis, and 26 of 40 histological samples were accurately diagnosed with dual-phase combined with SPECT/CT fusion imaging. Subtraction-combined SPECT/CT fusion imaging and all combined scintigraphy diagnostic values exhibited the same performance. The sensitivity and specificity of the proposed method significantly improved compared with those of the dual-phase technique(67.5% vs. 47.5%, χ²=6.635, P=0.02; 93.3% vs. 86.7%, χ²=4.432, P=0.04).

ConclusionFor patients with hyperparathyroidism, the detection rate of lesions by conventional dual-phase plane imaging combined with subtraction plane imaging and SPECT/CT fusion imaging was improved compared with that by single-and dual-phase plane imaging.