PET/CT with 18F-Choline in the preoperative localization of hyperparathyroidism: correlation with intraoperative findings and other imaging techniques

Introduction: To establish the relationship between the localization results of 18F-Choline PET/CT in patients with a biochemical diagnosis of hyperparathyroidism, the intraoperative findings and other imaging techniques.

Methods: We included 17 patients (13 females, 4 males; 56.3 ± 14.4 years old) with a biochemical diagnosis of hyperparathyroidism who were referred to our department for 18F-Choline PET/CT. The indication for PET/CT was: pre-surgical localization diagnosis in cases with other negative, doubtful or inconclusive diagnostic imaging techniques. Two tomographic images centered in the cervico-thoracic region were acquired 5 and 60 minutes after intravenous administration of 185 MBq of 18F-Choline. All patients had other previous imaging techniques: dual-phase parathyroid scintigraphy with [99mTc] Tc-MIBI (16 patients), cervical ultrasound (13 patients), cervical CT (6 patients), cervical MRI (3 patients) and 4D cervical CT (5 patients). All patients underwent surgery. PET/CT results were correlated with those of the other imaging techniques and intraoperative anatomopathological findings and analytical parameters. Calcium and iPTH values were collected pre-surgery, inmediately after surgery, as well as intraoperative PTH, to ensure the surgical success. Two patients had previous cervical surgery.

Results: In surgery, the pathological gland was located in 16 cases (15 solitary adenomas, 1 double adenoma). All these patients had subsequent normalization of serum iPTH levels. PET/CT with 18F-Choline was positive in 14 out of 16 patients, but in one of them additional multiglandular disease not detected by PET/CT was found. Two patients (2/16) had a negative PET/CT study, one of them due to multiglandular disease (not localized in any other imaging technique).

The patient in which the parathyroid adenoma was not found during surgery, it was a false positive, due to a papilar thyroid carcinoma, in PET/CT with 18F-Choline and MIBI scan.

There was correlation between 18F-Choline PET/CT and the other imaging techniques in the following cases: [99mTc] Tc-MIBI scintigraphy: 2/16 patients, cervical ultrasound: 3/13, cervical CT 0/6, cervical MRI 2/3 and cervical CT 4D 1/5. Apart from 18F-Choline, neither of the other tests gave relevant information because of their negative or doubtful result, except in one patient in which the only positive imaging technique was 4D cervical CT.

It should be noted that in 8 out of 17 cases, the only positive test was PET/CT with 18F-Choline.

The detection rate per patient with 18F-Choline is 87.5%, and considering the detection per lesion the rate is 82.4%.

Conclusions: 18F-Choline PET/CT is a recommended preoperative localization technique in patients with hyperparathyroidism with other negative, doubtful or inconclusive imaging techniques, showing good correlation with intraoperative findings, probably with lower sensitivity in cases of multiglandular disease, as other imaging tests. It is remarkable that in 47% of the patients the only test that was able to localize the parathyroid adenoma was the 18F-Choline PET/CT.

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