Performance of [18F]fluorocholine PET/CT in MEN1-related primary hyperparathyroidism before initial surgery or for persistent/recurrent disease

Results of 18F-choline and 11C-methionine positron emission tomography/computed tomography for the preoperative localization of hyperfunctional parathyroid glands in primary hyperparathyroidism

BACKGROUND

Preoperative localization of hyperfunctioning parathyroid glands in primary hyperparathyroidism is essential for successful parathyroid surgery, particularly in patients with previous negative imaging or reoperations.

METHODS

A multicenter registry study was performed in 776 patients with primary hyperparathyroidism from 53 hospitals in Germany and Austria who underwent parathyroid surgery after preoperative 18F-choline or 11C-methionine positron emission tomography/computed tomography (PET/CT).

RESULTS

In 683 of 776 patients (88%) (78% female, aged 15-86 years), primary hyperparathyroidism was caused by a single-gland parathyroid adenoma. A total of 9.2% patients had multiglandular disease, 0.4% had parathyroid carcinoma, and, in 2.4%, no hyperfunctional parathyroid glands were found intraoperatively. The sensitivity of 18F-choline PET/CT was 87.9% compared with 83.2% for 11C-methionine PET/CT with a positive predictive value for 18F-choline PET/CT and 11C-methionine PET/CT of 88.5% and 85.6%, respectively. A subgroup analysis revealed more positive results for 18F-choline PET/CT in patients with previous neck surgery (89.0%) than for 11C-methionine PET/CT (74.2%, P = .0411). Positive PET/CT results significantly reduced surgery times decreasing from 93 minutes (±56.54) to 71 minutes (±43.48, P < .0001). Postoperative normalization of calcium levels was achieved in 729 patients (93.9%). In the case of positive PET/CT findings, 97.2% of the patients were cured (P < .0001).

CONCLUSION

Both PET/CT tracers showed excellent detection rates of hyperfunctioning parathyroid glands in primary hyperparathyroidism, especially in a setting with a high percentage of reoperations and negative sestamibi scans.

Management of primary hyperparathyroidism in MEN1: From initial subtotal surgery to complex treatment of the remaining gland

Multiple endocrine neoplasia type 1 (MEN1) is a rare genetic disease with autosomal dominant transmission, which can cause various tumors, particularly endocrine, in a given patient. Primary hyperparathyroidism (PHPT) is the most common and earliest manifestation, leading to surgery before the age of 50 in most patients. Biological severity and renal and/or bone complications dictate the timing of parathyroid surgery. The objective is to correct hypercalcemia to prevent impact, while minimizing the risk of hypoparathyroidism. The most widely recommended procedure is subtotal parathyroidectomy (3 or 3.5 glands removed), with thymic horn resection via a cervical route. The development of imaging techniques, however, makes it possible to discuss partial surgery (resection of 1 or 2 glands) on a case-by-case basis depending on preoperative imaging and other elements such as patient age. Finally, hypercalcemia recurrence after initial surgery is a common feature of MEN1, and management of the remaining gland is challenging with various options: reoperation, calcimimetics and US-guided ablation or therapeutic abstention.

Chapter 10: What parathyroid imaging is required for hyperparathyroidism?

In over 80% of cases, primary hyperparathyroidism results from hypersecretion of PTH by a single parathyroid adenoma. Multi-glandular involvement, combining adenoma and/or hyperplasia in varying proportions, is also possible, although less frequent. When the diagnosis of hyperparathyroidism is certain and surgery is envisaged, imaging is useful for locating the hyperfunctioning gland or glands. First-line exploration is based on a parathyroid ultrasound and a nuclear medicine examination, which may be parathyroid scintigraphy, preferably double isotope I/12399m Tc-sestamibi, with planar and tomoscintigraphic acquisitions, or a PET-CT scan with 18F-choline. In the event of negative results, it is advisable to perform a choline PET scan if the initial examination was scintigraphy. In difficult situations, additional investigations using 4D parathyroid CT or parathyroid MRI, fine-needle aspiration cytology and determination of PTH in the flushing fluid are possible after multidisciplinary discussion in an expert center.

Chapter 6: Syndromic primary hyperparathyroidism

Syndromic primary hyperparathyroidism has several features in common: younger age at diagnosis when compared with sporadic primary hyperparathyroidism, often synchronous or metachronous multi-glandular involvement, higher possibility of recurrence, association with other endocrine or extra-endocrine disorders, and suggestive family background with autosomal dominant inheritance. Hyperparathyroidism in multiple endocrine neoplasia type 1 is the most common syndromic hyperparathyroidism. It is often asymptomatic in adolescents and young adults, but may be responsible for recurrent lithiasis and/or bone loss. Hyperparathyroidism-jaw tumor syndrome is less frequent, but often immediately symptomatic, with higher blood calcium levels, and is sometimes associated with an atypic parathyroid tumor or parathyroid carcinoma. Hyperparathyroidism in multiple endocrine neoplasia type 2A is not at the forefront of the clinical picture, rarely revealing the disease, and often manifests with few symptoms. Multiple endocrine neoplasia type 4 is a more recently described entity, in which hyperparathyroidism seems to occur later and be less severe than in previous syndromes. In all cases, the indications and modalities of surgical treatment should be discussed in an expert center. The risk of recurrence after surgery, particularly high in multiple endocrine neoplasia type 1, requires long-term monitoring.

Up-to-Date Imaging for Parathyroid Tumor Localization in MEN1 Patients with Primary Hyperparathyroidism: When and Which Ones (A Narrative Pictorial Review)

Patients diagnosed with multiple endocrine neoplasia type-1 (MEN1) often initially present with primary hyperparathyroidism (pHPT), and typically undergo surgical intervention. While laboratory tests are fundamental for diagnosis, imaging is crucial for localizing pathological parathyroids to aid in precise surgical planning. In this pictorial review, we will begin by comprehensively examining key imaging techniques and their established protocols, evaluating their effectiveness in detecting abnormal parathyroid glands. This analysis will emphasize both the advantages and potential limitations within the clinical context of MEN1 patients. Additionally, we will explore integrated imaging approaches that combine multiple modalities to enhance localization accuracy and optimize surgical planning-an essential component of holistic management in MEN1 cases. Various imaging techniques are employed for presurgical localization, including ultrasound (US), multiphase parathyroid computed tomography (CT) scanning (4D CT), magnetic resonance imaging (MRI), and nuclear medicine techniques like single photon emission computed tomography/CT (SPECT/CT) and positron emission tomography/CT (PET/CT). US is non-invasive, readily available, and provides high spatial resolution. However, it is operator-dependent and may have limitations in certain cases, such as intrathyroidal locations, the presence of bulky goiters, thyroid nodules, and previous thyroidectomy. Four-dimensional CT offers dynamic imaging, aiding in the identification of enlarged parathyroid glands, particularly in cases of ectopic or supernumerary glands. Despite concerns about radiation exposure, efforts are underway to optimize protocols and reduce doses, including the use of dual-energy CT. MR imaging offers excellent soft tissue contrast without radiation exposure, potentially providing superior differentiation between parathyroid glands and the surrounding structures. Radionuclide imaging, especially PET/CT using radiopharmaceuticals like [18F]FCH, shows promising results in localizing parathyroid tumors, particularly in patients with MEN1. [18F]FCH PET/CT demonstrates high sensitivity and may provide additional information compared to other imaging modalities, especially in cases of recurrent HPT.

18F-Fluorocholine-Positron Emission Tomography/Computerized Tomography (FCH PET/CT) Imaging for Detecting Abnormal Parathyroid Glands: Indication, Practice, Interpretation and Diagnostic Performance

In patients with confirmed hyperparathyroidism (HPT) scheduled for surgical treatment, the preoperatory imaging permits to optimize the operatory protocol of parathyroidectomy (PTX), in particular by selecting those patients who can benefit from minimally invasive PTX (MIPTX). The MIPTX has the merit to shorten the operative time, incision length, and to reduce the operatory risks. With preoperative localization studies, the rate of PTX failure, in particular due to nonsuspected multiglandular or ectopic disease, has been profoundly decreased. The first cases of incidental localization of abnormal parathyroid glands (PTs) on FCH PET/CTs performed for another indication were reported more than one decade ago. Since then, significant amount of data from heterogeneous series of patients consistently confirmed better diagnostic performances of FCH PET/CT (sensitivity for detection of abnormal PT 97%, range 96%-98%) in comparison with other radiopharmaceuticals, ultrasonography or 4D-CeCT in localizing hyperfunctioning parathyroid glands (HFPTGs) in case of primary HPT. Utility of FCH PET/CT in case of renal HPT has been reported in fewer series. The article discusses and summarizes the bibliographic evidence on documented indications of FCH PET/CT in patients with HPT, its safety profile, the practice of FCH PET/CT and interpretation of FCH PET/CT findings, including potential interpretation pitfalls and tips to avoid them. Our real-world experience over 12 years reinforces published evidence supporting the use of FCH PET/CT as the first-line radionuclide imaging technique in patients with all types of HPT in whom surgery is an option.