ObjectiveThe value of ⁹⁹Tc^m-MIBI SPECT/CT fusion imaging in primary hyperparathyroidism (PHPT) and secondary hyperparathyroidism (SHPT) was evaluated.

MethodsA total of 97 HPT patients (28 PHPT patients and 69 SHPT) were enrolled in this retrospective study. The ⁹⁹Tc^m-MIBI SPECT/CT imaging features, clinical symptoms, serum PTH, Ca, P, and AKP were analyzed. The following data were compared between PHPT and SHPT patients:imaging features; pathological findings; laboratory examination results; and relevance of diagnostic efficiency and clinical index.

Results(1) The sensitivity and specificity of ⁹⁹Tc^m-MIBI SPECT/CT in PHPT were 96.55% and 98.78%, respectively. By contrast, the sensitivity and specificity of ⁹⁹Tc^m-MIBI SPECT/CT SHPT were 68.77% and 79.17%, respectively. (2) PHPT generally exhibited single lesion with average diameter was 17.4 mm. Compared with PHPT, SHPT generally displayed more lesions with smaller diameter of 12.8 mm (Z=-2.591, P=0.010) and more likely to be found with calcification(χ²=9.588, P < 0.01). (3) The percentage of patients without special clinical symptoms was higher in PHPT(χ²=11.713, P < 0.001). The percentage of patients with calculus in urinary system was also higher in PHPT(χ²=6.075, P < 0.001). However, the percentage of patients with ostalgia was higher in SHPT(χ²=24.382, P < 0.001). Serum PTH and AKP were significantly higher in SHPT(Z=-6.663, -4.326, both P < 0.001). PHPT had high serum calcium level and low phosphorus level, whereas SHPT showed normal or slightly higher calcium level and significantly high phosphorus level.

Conclusions⁹⁹Tc^m-MIBI SPECT/CT fusion imaging had a significant value in preoperation localization of HPT, especially in PHPT. Compared with PHPT, SHPT had a greater increase in serum PTH and AKP and usually exhibited several lesions which are smaller and more likely to accompany calcification.