Incremental role of 18F-fluorocholine PET/CT over technetium-99m-labeled MIBI scan in hyperparathyroidism

Persistent hyperparathyroidism due to mediastinal parathyroid adenoma treated with selective arterial embolization with embosphere: first case in the literature

Primary hyperparathyroidism (PHPT) is the most common cause of hypercalcemia in the clinical setting and affects 0.3% of the population. Parathyroidectomy is the only definitive cure. Unfortunately, even in the most experienced hands, persistent primary hyperparathyroidism (P-PHPT) occurs in 4.7% of the patients. Ectopic adenomas are difficult to localize before and during operation and usually end up with P-PHPT. Herein, we presented a case with P-PHPT due to mediastinal parathyroid adenoma that was successfully ablated with selective arterial embolization. A 57-year-old female patient was admitted to our endocrinology clinic with persistent hypercalcemia 4 months after the initial surgery for PHPT that had been performed in another center. The patient did not accept the second operation, and serum calcium and parathyroid hormone (PTH) remained high despite medical treatment with cinacalcet and IV zoledronate. In the 99-m Tc-MIBI scintigraphy with SPECT, a 18 × 12-mm-sized lesion in the mediastinum at the paratracheal region was detected which was confirmed to be a possible parathyroid adenoma with fluorocholine PET and chest computed tomography (CT). The right bronchial artery that was detected to supply the mediastinal mass in CT angiography was selectively catheterized and embolized with embosphere. Right after the procedure, serum PTH and calcium levels were normalized and remained normal in 23 months of follow-up. Selective arterial embolization is a treatment option for ectopically located adenomas which are difficult to resect and in cases with certain comorbidities which constitute a contraindication for surgery.

Surgical options in treating patients with primary hyperparathyroidism

Background

Primary hyperparathyroidism is the third most common endocrine disorder for which surgical procedure called parathyroidectomy is the most effective treatment. Since the early 20^th century, parathyroid surgery has improved extensively. With the advances in preoperative imaging and with understanding the causes of disease, new and minimally invasive surgical approaches overrode the standard bilateral exploratory operations. Directed parathyroidectomy is currently the standard technique for treatment of primary hyperparathyroidism worldwide.

Conclusions

Surgery is the only definitive treatment of primary hyperparathyroidism. The most appropriate type of surgical procedure depends on the number and localization of the hyperactive parathyroid glands, availability of modern imaging techniques, limitation of each type of procedure and expertise.

18Fluorocholine PET/CT scanning with arterial phase-enhanced CT is useful for persistent/recurrent primary hyperparathyroidism: first UK case series results

INTRODUCTION

Redo parathyroidectomy for persistent/recurrent primary hyperparathyroidism is associated with a higher risk of complications and should be planned only with convincing localisation. We assessed whether 18fluorocholine positron emission tomography/computed tomography could identify parathyroid adenoma(s) in patients with persistent/recurrent primary hyperparathyroidism and negative conventional scans.

MATERIALS AND METHODS

A departmental database was used to identify patients with failed localisation attempts (sestamibi single photon emission computed tomography/computed tomography and/or computed tomography/magnetic resonance imaging and/or selective parathyroid hormone sampling) after previous unsuccessful surgery for primary hyperparathyroidism. 18Fluorocholine positron emission tomography was performed in all patients and redo surgery offered to those with positive findings.

RESULTS

18Fluorocholine positron emission tomography incorporating arterial and portal phase enhanced computed tomography was performed in 12 patients with persistent/recurrent primary hyperparathyroidism (four men and eight women). Seven patients (58%) were cured after excision of adenomas located in ectopic positions (n = 3) or in anatomical position (n = 4). Five patients (42%) had persistent hypercalcaemia and repeat 18fluorocholine scan confirmed that the area highlighted on preoperative scans was excised. The arterial phase enhancement of the computed tomography was significantly different between cured and not-cured patients (P = 0.007). All seven cured patients had either a strong or weak enhancing pattern on computed tomography. Standardised uptake value at 60 minutes in patients with successful surgery (range 2.7-15.7, median 4.05) was higher than in patients with failed surgery (range 1.8-5.8, median 3.2) but was not statistically significant (P = 0.300).

DISCUSSION

18fluorocholine scanning can identify elusive parathyroid adenomas, including those that are ectopic, and is useful in the management of patients with persistent/recurrent primary hyperparathyroidism when first-line scans are negative. The grading of the arterial phase of computed tomography can help to differentiate between true adenomas and false positive targets (lymph nodes).

Fluorocholine PET Imaging of Parathyroid Disease

To give an overview of the potential clinical utility of 18F-fluorocholine PET/CT (FCH PET/CT) in imaging of parathyroid adenoma. Available studies have provided preliminary results of 18F-FCH PET/CT in primary and secondary hyperparathyroidism. Results of various studies have shown that 18F-FCH is a promising upcoming tracer for the detection of parathyroid adenomas, especially when multiple, or having low size. FCH PET/CT has the potential to be a standard investigation in the detection of parathyroid lesions.

Incidental Detection of Parathyroid Adenoma on Somatostatin Receptor PET/CT and Incremental Role of 18F-Fluorocholine PET/CT in MEN1 Syndrome

Multiple endocrine neoplasia type 1 (MEN1) syndrome is characterized by combined occurrence of tumors of endocrine glands including the parathyroid, the pancreatic islet cells, and the anterior pituitary gland. Parathyroid involvement is the most common manifestation and usually the first clinical involvement in MEN1 syndrome, followed by gastroentero-pancreatic neuroendocrine tumors (NETs). Here we present a case where the patient initially presented with metastatic gastric NET and a single parathyroid adenoma was detected incidentally on ⁶⁸Ga-DOTANOC PET/CT done as part of post ¹⁷⁷Lu-DOTATATE therapy (PRRT) follow-up. Further ¹⁸F-fluorocholine PET/CT showed four adenomas for which the patient subsequently underwent subtotal parathyroidectomy.