Aim: The aim of this study was to determine the role of fluorine-18-choline (F-FCH) PET/CT in comparison with technetium-99m-methoxyisobutylisonitrile (Tc-MIBI) single-photon emission computed tomography/computed tomography (SPECT/CT) in primary hyperparathyroidism and to investigate whether maximum standardized uptake value (SUVmax) 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 Tc-MIBI SPECT/CT and F-FCH PET/CT and had inconclusive neck ultrasonography (USG) were studied. The diagnostic power of both modalities and the relationship between SUVmax 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, Tc-MIBI SPECT/CT and F-FCH were concordant (κ=0.64, P=0.001). In five of 35 patients with a negative SPECT/CT, F-FCH PET/CT accurately localized parathyroid adenomas. In one patient, F-FCH was false negative and Tc-MIBI SPECT/CT showed the lesion. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of Tc-MIBI SPECT/CT and F-FCH PET/CT were calculated to be 78, 100, 100, 70, 86%, and 96, 100, 100, 93, and 97%, respectively. SUVmax 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 SUVmax greater than 4.4 (i.e. the mean SUVmax calculated in positive cases).
Conclusion: F-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 Tc-MIBI SPECT/CT. SUVmax 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.