Modern possibilities of single-photon emission tomography combined with computed tomography, in identifying impaired parathyroids in patients with primary and secondary hyperparathyroidism

Aim. Evaluation of diagnostic possibilities of the optimal protocol of hybrid single-photon emission tomography in the assessment of the functional state of parathyroids in patients with various types of primary and secondary hyperparathyroidism. Material and methods. The study consistently included 138 patients with a diagnosis of primary (normocalcemic, nPHPT, and hypercalcemic, hPHPT) or secondary HPT (due to the acquired vitamin D deficiency, as well as with terminal chronic kidnet disease, CKD). Nuclear study of neck and mediastum with 99mTc-MIBI was performed in the planar two-phase scintigraphy mode according to a standard protocol, with an estimation of parathyroid visualization intensity, as well as in single-photon emission tomography, combined with computed tomography (SPECT/CT) performed in a early phase, one hour after MIBI injection, and in a delayed phase, with anassessment of the ratio of the average signal intensities from parathyroids and the overall signal (ROIparatyroid/ROIoverall) by axial image.Results. The frequency of parathyroid ectopia in PHPT was 24.3%, adenomas with rapid clearance- 43.2%. ROIparatyroid/ROIoverall value (criterion of a clearer visualization of parathyroids against the background of a common signal from the thyroid) in the group of patients with adenomas with normal clearance exceeded 2.0-2.5 in all phases of the study. In cases of adenomas with rapid clearance, mean value of this parameter was 2.11 ± 0.16 in the early phase, 2.42 ± 0.21 in the intermediate phase, significantly decreased by the delayed phase (1.76 ± 0.24, P = 0.003). The sensitivity of the ultrasound, planar scintigraphy, SPECT and SPECT/CT in identifying the modified parathyroids in patients with nPHPT (n = 15) was 66.7%, 53.3%, 86.7%, 93.3%, respectively, with hPHPT (n=59) - 78.0%, 76.3%, 93.2%, 98.3%, respectively. In patients with an acquired vitamin D deficiency (n = 50), impaired parathyroids were visualized by SPECT/CT in 8% of cases, in patients with CKD (n = 14) - in 14.3% of cases.Conclusion. SPECT/CT of the neck area is a key method of topical imaging of impaired parathyroids in preoperative preparation of patients with SHPT caused by CKD. The method may have a diagnostic value in treatment-resistant patients with vitamin D deficiency and upper-normal PTH and calcium levels in terms of detection of the nodular form of parathyroid hyperplasia. The implementation of the SPECT/CT after one hour after the injection of MIBI increases the sensitivity of the study.