The efficacy of fluorine-18-choline PET/CT in comparison with 99mTc-MIBI SPECT/CT in the localization of a hyperfunctioning parathyroid gland in primary hyperparathyroidism

Aim The aim of this study was to determine the role of fluorine-18-choline (¹⁸F-FCH) PET/CT in comparison with technetium-99m-methoxyisobutylisonitrile (^99mTc-MIBI) single-photon emission computed tomography/computed tomography (SPECT/CT) in primary hyperparathyroidism and to investigate whether maximum standardized uptake value (SUV_max) may be indicative of disease severity. Patients and methods Thirty-five primary hyperparathyroidism patients (24 females, 11 males, mean age: 55.31 ± 12.27, range: 25-72 years) who underwent ^99mTc-MIBI SPECT/CT and ¹⁸F-FCH PET/CT and had inconclusive neck ultrasonography (USG) were studied. The diagnostic power of both modalities and the relationship between SUV_max and biochemical [serum parathormone (PTH), calcium, phosphorus, vitamin D3 levels, urinary calcium excretion/24 h] and clinical (bone mineral densitometry and urinary USG results) parameters were analyzed. Results In 29 of 35 patients, ^99mTc-MIBI SPECT/CT and ¹⁸F-FCH were concordant (κ = 0.64, P = 0.001). In five of 35 patients with a negative SPECT/CT, ¹⁸F-FCH PET/CT accurately localized parathyroid adenomas. In one patient, ¹⁸F-FCH was false negative and ^99mTc-MIBI SPECT/CT showed the lesion. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of ^99mTc-MIBI SPECT/CT and ¹⁸F-FCH PET/CT were calculated to be 78, 100, 100, 70, 86%, and 96, 100, 100, 93, and 97%, respectively. SUV_max was correlated with lumbal T scores (P = 0.026). The mean serum PTH levels were significantly higher (P = 0.026) and lumbal and femur T scores were significantly lower (P = 0.04 and 0.008) in patients with SUV_max greater than 4.4 (i.e. the mean SUV_max calculated in positive cases). Conclusion ¹⁸F-FCH PET/CT has a high diagnostic power in primary hyperparathyroidism and can be used for further evaluation of patients with inconclusive neck USG and ^99mTc-MIBI SPECT/CT. SUV_max of the hyperfunctioning parathyroid gland seems to be predictive of disease severity in terms of serum PTH and bone mineral densitometry results. Studies with larger patient groups are needed to support these data.