Challenging pre-surgical localization of hyperfunctioning parathyroid glands in primary hyperparathyroidism: the added value of 18F-Fluorocholine PET/CT

18F-fluorocholine PET/CT imaging in primary hyperparathyroidism after negative or inconclusive cervical ultrasonography and 99mTc-MIBI scintigraphy

PURPOSE

Primary hyperparathyroidism (pHPT) is a common endocrine disorder characterized by one or more hyperfunctioning parathyroid glands. Definitive surgical treatment demands precise preoperative localisation of hyperfunctioning parathyroid tissue. The purpose of our study is to assess the value of 18F-fluorocholine positron emission tomography (PET/CT) in preoperative localisation of hyperfunctioning parathyroid glands in patients with biochemically confirmed pHPT and negative or inconclusive cervical ultrasonography and 99mTc-MIBI scintigraphy.

MATERIALS AND METHODS

Our study included 167 patients with biochemically confirmed pHPT and negative or inconclusive cervical ultrasonography and 99mTc-MIBI scintigraphy.

RESULTS

In our study 18F-fluorocholine PET/CT detection rate was 92.81% (155/167) with 182 lesions identified. Overall sensitivity, specificity, accuracy, and positive predictive value (PPV) on a per-lesion analysis were 100%, 75%, 95.33%, and 94.74%. Ninety (90/95) lesions were 18F-fluorocholine PET/CT true positive. A total of 86 patients underwent surgical procedures in which 95 histological lesions were removed. Histology revealed 60 adenomas, 25 hyperplasias, 5 lesions described as inconclusive parathyroid tissue, benign lymph node tissue in 4 lesions and 1 false-positive lesion was follicular thyroid adenoma. After surgery, all patients had PTH serum values measured (15 min after extirpation or during immediate postoperative recovery). Mean PTH serum values in patients with successful surgery decreased by an average of 62.54% (preoperative PTH 14.74 ± 8.54 pmol/L to 6.3 ± 6.8 pmol/L).

CONCLUSION

18F-fluorocholine PET/CT is an accurate, fast, and highly sensitive method for identifying the localization of overactive parathyroid glands in patients with primary hyperparathyroidism.

Contribution of 18 F-fluorocholine PET-CT to the preoperative localisation of parathyroid adenoma for the treatment of primary hyperparathyroidism

18 F-fluorocholine PET-CT is considered a second-line method for the preoperative localisation of parathyroid adenomas in primary hyperparathyroidism. The aim was to compare the diagnostic performance of 18 F-fluorocholine PET-CT and standard imaging modalities in the preoperative localisation of parathyroid adenomas in primary hyperparathyroidism. The primary objective was to assess the performance of 18 F-fluorocholine PET-CT in cases of negative or discordant standard imaging. The secondary objective was to evaluate the diagnostic performance of both 18 F-fluorocholine PET-CT and standard imaging in relation to patient characteristics. We conducted a retrospective, monocentric study, including 156 patients who underwent parathyroidectomy between 2017 and 2023. All patients underwent preoperative 18 F-fluorocholine PET-CT and had an indication for surgery due to primary hyperparathyroidism. A total of 156 patients were included in the study, the majority of whom were women (78%). Seven patients had multigland disease (4.49%). Sensitivity was 60.14% for cervical ultrasound, 46.21% for [99mTc]-MIBI scintigraphy, and 95.97% for 18 F-Fluorocholine PET-CT. 18 F-Fluorocholine PET-CT showed a higher sensitivity than cervical ultrasound and [99mTc]-MIBI scintigraphy, especially for multiple parathyroid adenomas (100, 57.14, and 42.86%, respectively). Univariate analysis showed better results for cervical ultrasound in men (p = 0.005). Larger adenomas showed better performance on [99mTc]-MIBI scintigraphy (p = 0.026), and elevated PTH levels were associated with significantly worse performance on 18 F-fluorocholine PET-CT (p = 0.023). Multivariate analysis showed that scintigraphy performance was worse in the presence of thyroid nodules (p = 0.049, RR = 2.046, 95% CI 1.005-4.166). 18 F-fluorocholine PET-CT is a valuable imaging modality for the preoperative localisation of parathyroid adenomas in primary hyperparathyroidism, with superior performance compared to conventional imaging modalities. [99mTc]-MIBI scintigraphy showed reduced diagnostic performance in the presence of thyroid nodules.

Diagnostic Performances of 18F-Fluorocholine PET/CT as First-Line Functional Imaging Method for Localization of Hyperfunctioning Parathyroid Tissue in Primary Hyperparathyroidism

RATIONALE AND OBJECTIVES

This study evaluated the diagnostic performance of 18F-fluorocholine (FCH) PET/CT as the first-line functional imaging method for preoperative localization of hyperfunctioning parathyroid glands (HPGs) in patients with primary hyperparathyroidism (PHPT).

MATERIALS AND METHODS

This retrospective single-center study included 80 consecutive patients with PHPT, referred for FCH PET/CT between January 2018 and July 2022, and who subsequently underwent surgery. The diagnostic performance of FCH PET/CT was compared to histological results for per-lesion analysis, and to postoperative resolution of biochemical PHPT for per-patient analysis.

RESULTS

18F-FCH-PET/CT revealed 95 positive foci in 77/80 patients and was negative in 3/80 patients. Postoperative resolution of HPT was obtained in 67/80 patients (84%). Per-lesion analysis showed 80 true positives, five true negatives, 11 false negatives, and eight false positives. Seven PET-positive foci could not be compared to histology. In a first per-lesion analysis, excluding these seven anomalies, sensitivity and positive predictive value (PPV) of FCH PET/CT were 88% (95% CI: 79-94) and 91% (95% CI: 87-94), respectively. In a second per-lesion analysis considering the seven anomalies as false positives (maximum bias analysis), PPV was 84% (95% CI: 80%-87%). By per-patient analysis, FCH PET/CT correctly identified and located all pathological glands in 56/80 (70%, 95% CI: 59-80) patients.

CONCLUSION

18F-Fluorocholine PET/CT appears to be an effective pre-surgical imaging method for localization of hyperfunctioning parathyroid tissue in patients with PHPT.

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.

Cost-effectiveness of one-stop-shop [18F]Fluorocholine PET/CT to localise parathyroid adenomas in patients suffering from primary hyperparathyroidism

PURPOSE

We conducted a cost-effectiveness analysis in which we compared a preoperative [18F]Fluorocholine PET/CT-based one-stop-shop imaging strategy with current best practice in which [18F]Fluorocholine PET/CT is only recommended after negative or inconclusive [99mTc]Tc-methoxy isobutyl isonitrile SPECT/CT for patients suffering from primary hyperparathyroidism. We investigated whether the one-stop-shop strategy performs as well as current best practice but at lower costs.

METHODS

We developed a cohort-level state transition model to evaluate both imaging strategies respecting an intraoperative parathyroid hormone monitored treatment setting as well as a traditional treatment setting. The model reflects patients' hospital journeys after biochemically diagnosed primary hyperparathyroidism. A cycle length of twelve months and a lifetime horizon were used. We conducted probabilistic analyses simulating 50,000 cohorts to assess joint parameter uncertainty. The incremental net monetary benefit and cost for each quality-adjusted life year were estimated. Furthermore, threshold analyses regarding the tariff of [18F]Fluorocholine PET/CT and the sensitivity of [99mTc]Tc-methoxy isobutyl isonitrile SPECT/CT were performed.

RESULTS

The simulated long-term health effects and costs were similar for both imaging strategies. Accordingly, there was no incremental net monetary benefit and the one-stop-shop strategy did not result in lower costs. These results applied to both treatment settings. The threshold analysis indicated that a tariff of €885 for [18F]Fluorocholine PET/CT was required to be cost-effective compared to current best practice.

CONCLUSION

Both preoperative imaging strategies can be used interchangeably. Daily clinical practice grounds such as available local resources and patient preferences should inform policy-making on whether a hospital should implement the one-stop-shop imaging strategy.

Update in imaging tests used for the localization of parathyroid pathology

Preoperative localization of parathyroid pathology, generally a parathyroid adenoma, can be difficult in some cases due to the anatomical variants that these glands present. The objective of this review is to analyse the different imaging techniques used for preoperative localization of parathyroid pathology (scintigraphy, ultrasound, CT, MRI and PET). There is great variability between the different tests for the preoperative localization of parathyroid pathology. The importance of knowing the different diagnostic options lies in the need to choose the most suitable test at each moment and for each patient for an adequate management of primary hyperparathyroidism (PHP) with surgical criteria.

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

PURPOSE

The aims of the study were to evaluate the performance and robustness of [18F]fluorocholine PET/CT in detecting hyperfunctioning parathyroid glands in MEN1-related primary hyperparathyroidism (pHPT) at different stages of their disease.

METHODS

Retrospective French multicenter study including patients with MEN1 pHPT who underwent [18F]fluorocholine PET/CT at initial diagnosis or for evaluation of persistent/recurrent disease. PET/CT were independently reviewed by two readers in a blinded manner. The assessment of PET/CT on a per-patient basis was assessed using a comprehensive set of criteria that considered pathological findings or agreement with alternative diagnostic methods in non-operated patients. The secondary objectives included the analysis of the performance of PET/CT at a per-lesion level, with reference to a pathological Gold Standard, and examining its interobserver reproducibility.

RESULTS

A total of 71 MEN1 patients were included (73 PET/CT) in the study. At the per-patient level (entire cohort), [18F]fluorocholine PET/CT sensitivity ranged from 98.5 to 100% among the different readers. An average of 1.77 glands per PET was described, with 2.35 glands at the initial diagnosis (n = 23) and 1.5 in previously operated cases (n = 50). PET/CT detected more lesions than conventional imaging work-up (neck ultrasound and/or scintigraphy). At the per-lesion level (41 operated patients), sensitivity ranged across different readers from 84.4 to 87%, and specificity ranged from 94.7 to 98.8%. At initial diagnosis, all patients that exhibited 3 or more abnormal glands on PET underwent subtotal parathyroidectomy while 7 out of 13 patients with 1 or 2 gland abnormalities on PET underwent less than subtotal parathyroidectomy. Finally, the degree of inter-observer agreement was high.

CONCLUSION

[18F]fluorocholine PET/CT is a reliable and robust imaging modality for the evaluation of MEN1-related pHPT and could guide surgeons in achieving the optimal benefit-risk ratio. This study gives a great impetus for its adoption as a primary diagnostic tool in this context.

Pearls of Parathyroidectomy: How to Find the Hard to Find Ones

The treatment of hyperparathyroidism through parathyroidectomy requires careful and complete preoperative evaluation. There are multiple imaging modalities and methods available to clinicians today to aid in identifying a pathological lesion; however, each has limitations that the clinician must understand. A systematic approach to patient evaluation, imaging, and surgical exploration is necessary to ensure accurate diagnosis and maximize the chances of minimally invasive and successful surgical removal.

Comparison of Neck Ultrasonography, Dual Phase 99mTc-Sestamibi with early SPECT-CT & 18F-Fluorocholine PET-CT as First Line Imaging in Patients with Primary Hyperparathyroidism

Introduction

Successful surgical treatment for primary hyperparathyroidism requires accurate localization of abnormal parathyroid tissue in terms of location and number. Imaging is important for localizing the parathyroid adenoma, and there has been significant interest in 18F-fluorocholine (FCH) positron emission tomography/computed tomography (PET/CT) for this purpose.

Aim

This study attempted to ascertain the utility of 18F-FCH PET/CT as a first-line investigation in preoperative localization of abnormal parathyroid tissue in primary hyperparathyroidism, in comparison with 99mTc-sestamibi dual-phase scintigraphy with early single-photon emission computed tomography (SPECT)/CT and neck ultrasonography.

Materials and Methods

Fifty-five patients with biochemical features of primary hyperparathyroidism were enrolled in this study. They underwent neck ultrasonography, 99mTc-sestamibi dual-phase scintigraphy with early SPECT/CT, and 18F-FCH PET/CT for localization of parathyroid lesions. Thirty-three patients underwent surgical resection of the detected lesions. For two patients, clinical and biochemical follow-up was used as a gold standard.

Results

A total of 40 lesions were resected in the 33 patients who underwent surgery. A further two lesions were localized in two patients with clinical and biochemical follow-up as the gold standard. Of these 42 lesions, 41 were detected in preoperative imaging and 1 lesion was noted intraoperatively and resected. 41/42 lesions were detected by 18F-FCH PET/CT (detection rate: 97.6%), 33/42 by 99mTc-sestamibi dual-phase scintigraphy with early SPECT/CT (detection rate: 78.5%), and 30/42 by neck ultrasonography (detection rate: 71.4%).

Conclusion

Detection rates on 18F-FCH PET/CT were superior to both 99mTc-sestamibi dual-phase scintigraphy with early SPECT/CT and neck ultrasonography in preoperative localization of parathyroid lesions in patients with primary hyperparathyroidism.

18F-fluorocholine PET/MRI versus ultrasound and sestamibi for the localization of parathyroid adenomas

PURPOSE

Accurate preoperative localization is imperative to facilitate a minimally invasive parathyroidectomy (MIP) in primary hyperparathyroidism (pHPT). This study aims to compare the diagnostic value of standard-of-care localization techniques (ultrasound [US] and 99mTechnetium (99mTc) -sestamibi scintigraphy) to [F-18]-fluorocholine positron emission tomography/magnetic resonance imaging (FCH-PET/MRI) to determine the additional clinical usefulness of PET/MRI in a Canadian cohort.

METHODS

We conducted a prospective, appropriately powered, study to compare the diagnostic value of -FCH PET/MRI to that of the US and 99mTc-sestamibi scintigraphy for localization of parathyroid adenomas in a patient with pHPT. The primary outcome was the per-lesion sensitivity and positive predictive value (PPV) of FCH-PET/MRI, US, and 99mTc-sestamibi scintigraphy. Intraoperative surgeon localization, parathormone levels, and histopathological findings were used as reference standards.

RESULTS

Forty-one patients underwent FCH-PET/MRI of which 36 patients had parathyroidectomy. In these 36 patients, 41 parathyroid lesions were histologically confirmed as adenomas or hyperplastic glands. Per-lesion sensitivity of FCH-PET/MRI was 82.9% and of US and 99mTc-sestamibi scintigraphy combined at 50.0%, respectively. The sensitivity of FCH-PET/MRI was superior to that of US and 99mTc-sestamibi scintigraphy (p = 0.002). In the 19 patients in whom both US and 99mTc-sestamibi scintigraphy were negative, PET/MRI correctly identified the parathyroid adenoma in 13 patients (68%).

CONCLUSIONS

FCH-PET/MRI is a highly accurate imaging modality for localization of parathyroid adenomas in a tertiary center in North America. It is a superior functional imaging modality to 99mTc-sestamibi scintigraphy alone and more sensitive for localization of parathyroid lesions than US and 99mTc-sestamibi scintigraphy combined. This imaging modality could become the most valuable preoperative localization study given its superior performance in localizing parathyroid adenomas.

Impact of Fluoro-Choline PET/CT in Reduction in Failed Parathyroid Localization in Primary Hyperparathyroidism

INTRODUCTION

Accurate localization of the pathological parathyroid gland is a prerequisite for minimally invasive surgical management of hyperparathyroidism (HPT). Poor imaging or discordance in odd situations like ectopic adenomas, parathyroid hyperplasia, syndromic HPT results in localization dilemma thus causing failed parathyroidectomy. We studied the impact of Fluoro-Choline (FCH) PET/CT imaging in reduction in localization failure of parathyroid adenoma.

MATERIALS AND METHODS

We did a retrospective observational study (2018-2021) of HPT among which 97 patients underwent focused parathyroidectomy (FP). All patients had undergone ultrasound imaging and 99mTc-sestaMIBI scan with early SPECT/CT (MIBI). When this preliminary imaging was doubtful or negative or multiple lesions were expected, FCH PET/CT was performed. We compared the localization accuracy of MIBI scan and FCH PET/CT with surgical outcomes as reference standard.

RESULTS

MIBI scan showed overall lesion detection rate (LDR) of 88.65% in localization of pathological parathyroid gland in 97 patients. The addition of FCH PET/CT improved the overall lesion detection to 97.9%. The overall possible localization failure was reduced from 11.34 to 2.06% with the addition of FCH PET/CT (p < 0.05). Out of 97 patients of FP, 87 patients showed features of parathyroid adenoma. Single hyperplastic gland was seen in 7 patients, lipoadenoma was seen in 1 patient and 1 patient had features suggestive of parathyroiditis on histopathology. FCH PET/CT was a useful adjunct and showed significant reduction in localization failure of parathyroid adenoma.

Comparison of [18F]fluorocholine PET/CT with [99mTc]sestamibi and ultrasonography to detect parathyroid lesions in primary hyperparathyroidism: a prospective study

BACKGROUND

Primary hyperparathyroidism is a common endocrine disorder produced by the increase of parathyroid hormone (PTH) due to a benign adenoma of a single parathyroid gland, or as multiple gland hyperplasia, or as a rare malignant tumor. Preoperative imaging scans are frequently necessary for the minimally invasive parathyroidectomies to identify the location of enlarged parathyroid glands and to design the procedure.

METHODS

The diagnostic reliability of [18F]fluorocholine positron emission tomography/computed tomography (FCH PET/CT), [99mTc]sestamibi [multiplexed ion beam imaging (MIBI)] and cervical ultrasonography was analyzed in 37 patients diagnosed with primary hyperparathyroidism undergoing minimally invasive parathyroidectomy. The three preoperative imaging techniques were correlated with intraoperative and histopathological findings as well as changes in biochemical parameters (serum PTH and calcium levels). Statistical analysis was carried out with SPSS version 24.0.

RESULTS

In 30 of 37 patients (81.1%), FCH PET/CT correctly localized the pathological gland. In 3 cases of ectopic adenomas, the accuracy of the techniques was 100% (3/3) for FCH PET/CT, 66.7% (2/3) for MIBI, and 33.3% (1/3) for neck ultrasonography. Neither neck ultrasonography nor MIBI were able to locate pathological parathyroid glands in those patients with multiglandular disease, while FCH PET/CT correctly located one patient (1/3, 33.3%) with two adenomas and 3 patients (3/6, 50.0%) with hyperplasia. The three imaging techniques, FCH PET/CT, MIBI and neck ultrasound yielded a sensitivity of 92.1%, 57.9% and 32.4%, a positive predictive value of 94.6%, 84.6% and 78.6%, and a diagnostic accuracy of 96.4%, 85.7% and 79.0%, respectively.

CONCLUSIONS

In this group of patients diagnosed with primary hyperparathyroidism, FCH PET/CT was superior to MIBI and neck ultrasound in detecting adenomas, particularly in the presence of ectopic glands or multiglandular disease.

Retrospective real-life study on preoperative imaging for minimally invasive parathyroidectomy in primary hyperparathyroidism

The objective of this study was to retrospectively evaluate preoperative imaging modalities for localization of parathyroid adenomas with a view to enable minimally invasive parathyroidectomy and in particular, to consider the contribution of ¹⁸F-fluorocholine-PET/CT. 104 patients with primary hyperparathyroidism, who underwent parathyroid surgery in a single centre during a 6-year period were included. Of these, 103 underwent ultrasound, 97 ^99mTc-Pertechnetate/SestaMIBI-SPECT, 20 MRI and 30 ¹⁸F-fluorocholine-PET/CT. Based on surgical findings, sensitivities and specificities for correct lateralisation in orthotopic locations were: for ultrasound 0.75 (0.65-0.83) and 0.89 (0.81-0.94), for ^99mTc-MIBI-SPECT 0.57 (0.46-0.67) and 0.97 (0.91-0.99), for MRI 0.60 (0.36-0.81) and 0.83 (0.59-0.96) and for ¹⁸F-fluorocholine-PET/CT 0.90 (0.73-0.98) and 0.90 (0.73-0.98). Correctly lateralized adenomas were significantly larger than those not found with ultrasound (p = 0.03) and SPECT (p = 0.002). Pre-operative PTH-levels were higher in single adenomas detected by scintigraphy than in those not (p = 0.02). 64 patients could be treated with a minimally invasive procedure. Cure after parathyroidectomy was obtained in 94% of patients. ¹⁸F-Fluorocholine-PET/CT could be shown to be a highly accurate modality to localize parathyroid adenomas preoperatively, obviating the need for total exploration in the majority of patients in whom ultrasound and scintigraphic results are discordant or both negative.

Functional imaging for hyperparathyroidism

Once hyperparathyroidism has been proven, the goal of parathyroid functional imaging is to identify one or more pathological glands in view of guiding a possibly targeted surgical procedure, while maximizing the chances for recovery. Currently, parathyroid radionuclide imaging is based on two techniques, parathyroid scintigraphy and ¹⁸F-fluorocholine - positron emission tomography (PET). The main radiopharmaceutical in scintigraphy is ^99mTc-sestamibi, which can be used alone, in the dual-phase parathyroid scan, or in comparison with a thyroid radiotracer, pertechnetate (NaTcO₄) or iodine 123 (dual-tracer method). The acquisitions can be planar and/or tomographic (SPECT). It is now recognized that the ^99mTc-sestamibi - iodine 123 dual-tracer method is more efficient than the dual-phase scan, while SPECT-CT improves the sensitivity and specificity of the scintigraphy. This imaging and cervical ultrasonography are considered to be the two first-line reference techniques in preoperative assessment of hyperparathyroidism. More recently developed, ¹⁸F-fluorocholine detected by PET-CT has shown excellent performance, at least equal to that of scintigraphy. Initially considered as a second-line technique, its advantages over scintigraphy have prompted some authors to suggest it as the only examination to be performed in preoperative assessment of hyperparathyroidism. That said, due to a lack of specificity in ¹⁸F-fluorocholine uptake, which has been observed on inflammatory lesions and, particularly, in the mediastinal lymph nodes, and given the absence of simultaneous comparison of thyroid function, this strategy remains contested, and possibly reserved for patients without any associated thyroid pathology; large-scale evaluation would be justified.

Multiple endocrine neoplasia type 1 or 4: detection of hyperfunctioning parathyroid glands with 18F-fluorocholine PET/CT. Illustrative cases and pitfalls

¹⁸F-fluorocholine (FCH) PET/CT is now well established to detect the hyperfunctioning parathyroid glands (HFPTG) in a case of sporadic primary hyperparathyroidism (pHPT), but only limited evidence is available about the utility of FCH PET/CT to detect the HFPTG in patients with multiple endocrine neoplasia (MEN) type 1 or 4. The pHPT in this context frequently consists in a multiglandular disease with small hyperplastic glands rather than adenomas, which is challenging for imaging modalities. The data of patients with MEN1 or MEN4 after parathyroidectomy referred to FCH PET/CT for presurgical localization of HFPTG were retrospectively reviewed, including follow-up after parathyroidectomy, in search for diagnostic performance and for potential pitfalls. In the present cohort, 16 patients referred to FCH PET/CT as part of their initial pHPT work-up were subsequently operated, 44 abnormal parathyroid glands (PT) were resected, of which 32 (73%) had been detected on FCH PET/CT and 2 considered as equivocal foci. Nine patients referred to FCH PET/CT for recurrent pHPT who were subsequently operated, 14 abnormal PT were resected, all had been detected on FCH PET/CT. FCH PET/CT permitted a unilateral approach for PTx in 4 of them. In one patient with MEN4 and pHPT, the HFPTG could not be visualized on FCH PET/CT but was localized by ultrasonography. Several causes of false positive or false negative results, incidental finding and pitfalls are listed and discussed. FCH PET/CT has a positive benefit/risk ratio in the detection of HFPTG in case of MEN1 (the data in MEN4 being currently very limited) with the most effective detection rate of current imaging modalities for HFPTG, few pitfalls, and an adequate impact on patient management compared to sesta MIBI SPECT and ultrasonography.

Multiglandular Parathyroid Disease in Primary Hyperparathyroidism With Inconclusive Conventional Imaging

Inconclusive preoperative imaging is a strong predictor of multiglandular parathyroid disease (MGD) in patients with primary hyperparathyroidism (PHPT). MGD was investigated in a cohort of 17 patients with PHPT (mean age 64.9 years, total calcium 2.75 mmol/l and parathyroid hormone (PTH) 113.3 ng/l) who underwent 18F-fluorocholine PET/CT (FCH) imaging before surgery. The initial MIBI SPECT scintigraphy (MIBI) and/or neck ultrasound were not conclusive or did not localize all pathological parathyroid glands, and PHPT persisted after surgery. Sporadic MGD was present in 4 of 17 patients with PHPT (24 %). In 3 of 4 patients with MGD, FCH correctly localized 6 pathological parathyroid glands and surgery was successful. Excised parathyroid glands were smaller (p <0.02) and often hyperplastic in MGD than in single gland disease. In two individuals with MGD, excision of a hyperplastic parathyroid gland led to a false positive decline in intraoperative PTH and/or postoperative serum calcium. Although in one patient it was associated with partial false negativity, parathyroid imaging with FCH seemed to be superior to neck ultrasound and/or MIBI scintigraphy in MGD.

European Expert Consensus on Practical Management of Specific Aspects of Parathyroid Disorders in Adults and in Pregnancy: Recommendations of the ESE Educational Program of Parathyroid Disorders

This European expert consensus statement provides recommendations for the diagnosis and management of primary hyperparathyroidism (PHPT), chronic hypoparathyroidism in adults (HypoPT), and parathyroid disorders in relation to pregnancy and lactation. Specified areas of interest and unmet needs identified by experts at the second ESE Educational Program of Parathyroid Disorders (PARAT) in 2019, were discussed during two virtual workshops in 2021, and subsequently developed by working groups with interest in the specified areas. PHPT is a common endocrine disease. However, its differential diagnosing to familial hypocalciuric hypercalcemia (FHH), the definition and clinical course of normocalcemic PHPT, and the optimal management of its recurrence after surgery represent areas of uncertainty requiring clarifications. HypoPT is an orphan disease characterized by low calcium concentrations due to insufficient PTH secretion, most often secondary to neck surgery. Prevention and prediction of surgical injury to the parathyroid glands are essential to limit the disease-related burden. Long-term treatment modalities including the place for PTH replacement therapy and the optimal biochemical monitoring and imaging surveillance for complications to treatment in chronic HypoPT, need to be refined. The physiological changes in calcium metabolism occurring during pregnancy and lactation modify the clinical presentation and management of parathyroid disorders in these periods of life. Modern interdisciplinary approaches to PHPT and HypoPT in pregnant and lactating women and their newborns children are proposed. The recommendations on clinical management presented here will serve as background for further educational material aimed for a broader clinical audience, and were developed with focus on endocrinologists in training.

Histopathological Features of Parathyroid Adenoma and 18F-Choline Uptake in PET/MR of Primary Hyperparathyroidism

BACKGROUND

The aim of this study was to assess the relationship between the histopathological properties of hyperfunctioning parathyroids and parathyroid 18F-choline uptake.

PATIENTS AND METHODS

A total of 31 parathyroid adenomas were retrospectively analyzed in patients with primary hyperparathyroidism and preoperative 18F-choline PET/MR. PET/MR parameters of parathyroid glands (SUVmax and target-to-background ratio in early-phase [EP] and late-phase [LP]), MRI volume, preoperative parathyroid hormone (PTH) serum concentration, and postoperative histopathology (predominant cell type and growth pattern of adenoma cells, location and size of adenoma) were assessed. The relationship of PET/MR parameters, PTH, and histological parameters was determined using linear regression, Spearman correlation and Kruskal-Wallis test.

RESULTS

The median volume of parathyroid adenoma was 421.78 ± 142.46 mm3 (46.39-4412.69). Adenomas were predominantly composed of chief, water-clear, and oncocytic/oxyphilic cells in 27/31, 2/31, and 2/31 cases, respectively. The growth pattern was predominantly solid, follicular, and trabecular in 18/31, 8/31, and 5/31, respectively. The SUVmax was 6.71 ± 3.39 in EP and 6.91 ± 3.97 in LP. Follicular growth pattern had slightly higher EP SUVmax (trabecular: 4.12 ± 0.56; solid: 6.62 ± 3.19; follicular: 8.56 ± 3.96; P = 0.046). Spearman correlation showed strong positive correlation between volume and both EP and LP SUVmax (0.626; P = 0.0001 and 0.576; P = 0.0001, respectively). Linear regression analysis revealed significant correlation between PTH level and EP and LP SUVmax (both P = 0.001); in contrast, no correlation was found between PTH level and both cell type and growth pattern.

CONCLUSIONS

Our findings suggest that 18F-choline uptake of parathyroid adenomas might be associated both with the histological growth pattern and adenoma volume, but not with a specific cell type.

Diagnostic performances of cervical ultrasound, sestamibi scintigraphy and contrast-enhanced 18F-fluorocholine positron emission tomography in primary hyperparathyroidism

Purpose: Preoperative localization of pathological parathyroids is crucial for a minimally invasive treatment of primary hyperparathyroidism (PHPT). This study compares contrast-enhanced ¹⁸F-fluorocholine positron emission tomography (FCH-PET/CT), cervical ultrasound (CU) and conventional scintigraphic imaging modalities (MIBI scintigraphy), combined and individually for preoperative localization of hyper-functional parathyroids in PHPT. The gold standard is histological examination. Methods: Data from consecutive patients with a clinical suspicion of PHPT were retrospectively collected. All three imaging modalities were systematically performed. MIBI scintigraphy, consisted of ^99mTc-sestamibi/¹²³I-sodium iodide SPECT/CT, ^99mTc-sestamibi/¹²³I-sodium iodide planar subtraction imaging and ^99mTc-sestamibi planar dual-phase imaging. The ability of FCH-PET/CT, CU and MIBI scintigraphy to identify a hyper-functional parathyroid and specify the side or identify an ectopic location was noted. Patients underwent surgical exploration if at least one exam was positive. CU + MIBI scintigraphy combined was considered as a positive test if CU and MIBI scintigraphy separately showed a hyper-functional parathyroid gland on the same side, or the same ectopic location, and negative in other cases. The composite judgment criterion for pathological parathyroid combined histological analysis and normalization of PTH and calcium levels. Results: 149 pathological parathyroids were found in 143 of the 144 included patients. FCH-PET/CT diagnosed 148/149 pathological parathyroids. Only four false positives and one false negative were found. The FCH-PET/CT sensitivity of 99.3% was superior to that of CU at 75.2% (P < 0.0001), MIBI scintigraphy at 65.1% (P < 0.0001) and CU + MIBI scintigraphy combined at 89.9%, (P = 0.0009). 5/5 ectopic locations were diagnosed by FCH-PET/CT, 2/5 by MIBI and 0/5 by CU. Accuracy was better for FCH-PET/CT at 98% than CU at 84% (P < 0.0001), MIBI scintigraphy at 81% (P < 0.0001) or CU + MIBI scintigraphy at 91% (P < 0.0001). Among the 72 (50%) patients who had a negative CU + MIBI scintigraphy combined test, FCH-PET/CT correctly identified hyper-functional thyroids in 70 (97.2%) patients. Average FCH-PET/CT hyperfunctional parathyroid uptake was higher than the adjacent thyroid (SULmax 6.45 vs 2.15) (P < 0.0001). Conclusion: Accuracy of FCH-PET/CT is higher than CU and MIBI scintigraphy for localization of hyper-functional parathyroids, justifying the systematic use of FCH-PET/CT as the first-line method for PHPT diagnosis.

Head-to-head comparison among 18F-choline PET/CT, 4D contrast-enhanced CT, and 18F-choline PET/4D contrast-enhanced CT in the detection of hyperfunctioning parathyroid glands: a systematic review and meta-analysis

INTRODUCTION

In primary hyperparathyroidism (PHPT), the localization of hyperfunctioning parathyroid gland (HPTG) allows tailored surgery. Although Four-Dimensional Contrast-enhanced Computed Tomography (4DCeCT) and ¹⁸F-choline Positron Emission Tomography/Computed Tomography (PET/CT) are reported to be promising second-line imaging procedures, no meta-analysis of their comparison exists.

DESIGN

we conducted a systematic review and meta-analysis to find original papers reporting the head-to-head comparison of 4DCeCT, ¹⁸F-choline PET/CT and integrated ¹⁸F-choline-PET/4DCeCT.

METHODS

this systematic review was conducted according to PRISMA. PubMed, CENTRAL, Scopus, and Web of Science were searched until January 2021. Studies comparing the ability of 4DCeCT, ¹⁸F-choline PET/CT and ¹⁸F-choline PET/4DCeCT to identify HPTG in patients with PHPT were selected. A per patient-based analysis of the three procedures was conducted in all patients (detection rate, DR) and in those with histologically confirmed HPTG (sensitivity).

RESULTS

Of the 78 records identified, five articles (153 PHPT patients) published between January the 1st, 2018 and January the 31st, 2021 were included. The pooled DR of ¹⁸F-choline PET/CT, 4DCeCT and ¹⁸F-choline PET/4DCeCT was 0.86, 0.69, and 0.86, respectively, while their pooled sensitivity was 0.89, 0.77 and 0.93, respectively. The analysis of pooled discrepancy showed that the sensitivity of ¹⁸F-choline PET/CT and ¹⁸F-choline PET/4DCeCT was higher than that of 4DCeCT by 0.11 and 0.13, respectively, the sensitivity of ¹⁸F-choline PET/4DCeCT being 0.06 higher than that of ¹⁸F-Choline PET/CT.

CONCLUSIONS

This meta-analysis suggests that the sensitivity of ¹⁸F-choline PET/CT and ¹⁸F-choline PET/4DCeCT is higher than that of 4DCeCT, while only a slight difference was observed between ¹⁸F-choline PET/CT and ¹⁸F-choline PET/4DCeCT.

Four-dimensional computed tomography (4D-CT) for preoperative parathyroid localization: A good study but are we using it?

BACKGROUND

Four-dimensional computed tomography (4D-CT) scan to localize abnormal parathyroid glands is diagnostically superior to ultrasound (US) and sestamibi. The implementation of 4D-CT imaging is unknown.

METHODS

The Collaborative Endocrine Surgery Quality Improvement Program (CESQIP) database from 2014 to 2018 was utilized. Patients with hyperparathyroidism undergoing an initial operation were included. The rate of US, sestamibi and 4D-CT performance was calculated for the entire study population, and for each institution.

RESULTS

7,959 patients were included. In 311(3.9%) patients, no preoperative imaging was recorded. Of patients with imaging, US was performed in 6,872(86.3%), sestamibi in 5,094(64.0%), and 4D-CT in 1,630(20.4%). The combination of US and sestamibi was most frequent (3,855, 48.4%). Institutional rates of 4D-CT performance varied from 0.1% to 88.7%.

CONCLUSIONS

Of the imaging modalities, 4D-CT was utilized least frequently and with greatest variability. Given the high accuracy of 4D-CT, efforts to reduce this variation may improve overall preoperative localization in patients with hyperparathyroidism.

18F-Choline PET/CT, MRI, and Software-Based Image Fusion Analysis in Patients With Primary Hyperparathyroidism

PURPOSE

The aim of this study was to evaluate the diagnostic performance of 18F-choline PET and MRI in patients with primary hyperparathyroidism. Furthermore, the additional value of software-based PET/MRI scan fusion was analyzed.

PATIENTS AND METHODS

This retrospective study includes 42 patients (38 women) with an age between 32.5 and 79.1 years. PET/CT scans were performed on a dedicated system after injection of 250 to 350 MBq 18F-choline. For the MRI examination, T1-weighted images of the cervical region were used. The image fusion was made by anatomical coregistration using an automated algorithm based on mutual information.

RESULTS

A total of 46 lesions were discovered and histologically confirmed in 42 patients. Histopathological examination revealed 38 adenomas and 8 hyperplasias. This means that, in 4 of these 42 patients, 2 lesions per patient were discovered. PET/CT also detected 46 abnormal findings, but only 43 were correctly recognized, whereas the other 3 were false-positive (FP). Six lesions could not be detected correctly: 3 were FP and 3 false-negative, which resulted in a sensitivity of 93.5% and a specificity of 97.5%. The site-specific evaluation showed 18 true-positive enlarged parathyroid glands with MRI, but also produced 13 FP findings and failed to detect 28 lesions; the sensitivity and specificity are thus 39.1% and 89.3%, respectively. The difference in detection rate between 18F-choline PET/CT and MRI was statistically significant (P < 0.001).

CONCLUSIONS

18F-choline PET/CT is clearly superior to MRI for localization diagnostics in primary hyperparathyroidism. Image fusion of both modalities can be helpful for more precise anatomical assignment.

Assessment and Comparison of 18F-Fluorocholine PET and 99mTc-Sestamibi Scans in Identifying Parathyroid Adenomas: A Metaanalysis

Hyperparathyroidism is an endocrine disorder caused by one or more hyperfunctioning parathyroid glands. Current imaging consisting of ultrasound and 99mTc-sestamibi is imprecise, making localization difficult. 18F-fluorocholine (18F-FCH) PET has recently shown promise in presurgical localization of parathyroid adenomas. The primary aim of this study was to summarize the sensitivities and specificities of studies using 18F-FCH PET to localize hyperparathyroidism. A secondary aim was to summarize a subset of studies in which 99mTc-sestamibi scans were also used and to compare the performance of the 2 modalities. Methods: We searched the MEDLINE and EMBASE databases following the PRISMA (Preferred Reporting Items for Systematic Review and Metaanalysis) statement. Quality was assessed using the QUADAS-2 tool (Quality Assessment of Diagnostic Accuracy Studies). Twenty studies were included for quantitative assessment in our metaanalysis. A random-effects model and a hierarchic summary receiver-operating-characteristic model was used to summarize the sensitivity of 18F-FCH PET in detecting abnormal parathyroid adenomas. We used the same methodology to assess sensitivity of 99mTc-sestamibi, as a comparison to 18F-FCH PET. Results:18F-FCH PET had a high sensitivity, 0.97 (range, 0.96-0.98), for the detection of abnormal parathyroid adenomas. In the subpopulation for which both 18F-FCH and 99mTc-sestamibi were reported, 18F-FCH also had a higher sensitivity, 0.96 (0.94-0.98), than the 0.54 (0.29-0.79) reported for 99mTc-sestamibi (P < 0.001). Conclusion:18F-FCH PET demonstrates high localization accuracy in patients with hyperparathyroidism. This metaanalysis supports the use of 18F-FCH over 99mTc-sestamibi in patients with hyperparathyroidism.

Sestamibi Single-Positron Emission Computed Tomography/Diagnostic-quality Computed Tomography for the localization of abnormal parathyroid glands in patients with primary hyperparathyroidism: What clinicopathologic factors affect its accuracy?

PURPOSE

Sestamibi Single-Positron Emission Computed Tomography/Diagnostic-quality Computed Tomography (MIBI-SPECT/CT) is a common technology used for primary hyperparathyroidism (PHPT) localization in clinical practice. However, the clinicopathologic factors affecting the accuracy of MIBI-SPECT/CT and the potential limitations remain unclear.

METHODS

Retrospectively enrolled PHPT patients (n = 280) were analyzed from August 2017 to December 2019.

RESULTS

Of 96 patients with PHPT (mean age, 54 years; 63 females), 17 had discordance between MIBI-SPECT/CT and intraoperative findings. Among the 17 patients with discordance, 58.8% had major discordance, which occurred in most patients with multigland disease (MGD). Compared with concordant patients, discordant patients exhibited increased frequencies of autoimmune thyroid disease (29.4% vs 10.1%, p = 0.035), MDG (41.2% vs 3.8%, p = 0.035), higher PTH (296 pg/mL vs 146 pg/mL; p = 0.012),and lower phosphorus levels (0.77 mmol/L vs 0.90 mmol/L; p = 0.024). MDG (odds ratio [OR], 16.95; 95% CI 2.10-142.86), parathyroid lesion size of 12 mm or less (OR, 6.93; 95% CI 1.41-34.10), and a PTH level higher than 192.5 pg/mL (OR, 12.66; 95% CI 2.17-71.43) were independently associated with discordant MIBI-SPECT/CT results.

CONCLUSION

MGD was most strongly associated with discordance between MIBI-SPECT/CT and intraoperative findings followed by a PTH level higher than 192.5 pg/mL and parathyroid lesion size of 12 mm or less. Surgeons should recognize these potential limitations, which may improve the preoperative procedure by encouraging further localization imaging and promptly facilitate intraoperative troubleshooting.

Surgical management of MILD hyperparathyroidism

INTRODUCTION

There is no consensus for management of Mild primary hyperparathyroidism (MILD-pHP). Specific management has been suggested by some authors. We have compared the surgical management of the patients with MILD-pHP to those with Classic primary hyperparathyroidism (C-pHP) treated by surgery according to The Fourth International Workshop on pHP.

MATERIALS AND METHODS

Data of 173 patients who underwent a parathyroidectomy were reviewed and retrospectively analysed. Management of 32 patients with MILD-pHPT (18.5%) patients were compared to that of 141 (81.5%) patients with C-pHPT.

RESULTS

MILD-pHP group was more often discovered after non-fractured osteoporosis (21.9% vs 7.1%, p = 0.02) and surgery for chondrocalcinosis was more often carried out (6.3% vs 0%, p = 0.03) in the MILD-pHP group. A Mini-Invasive Parathyroidectomy (MIP) was carried out in 81.3% of cases, and 87.5% of patients had a single adenoma. The rate of multiglandular pathology was not different. Same day discharge was significantly higher in MILD-pHP group (37.5% vs 17.7%, p = 0.01). Success was obtained in 87.5% in the MILD-pHP group, there was no significant difference with the C-pHP group (92.9%, p = 0.48). There was no significant difference in the imaging performances. Imaging discordance was observed in 18.8% of cases in MILD-pHP and 33.6% in C-pHP (p = 0.38) without correlation with surgical failure.

CONCLUSION

This study suggests that, by selecting patients on the basis of concordant imaging and international recommendations, there is no difference in outcome between MILD-pHP and C-pHP treated surgically.

Superior sensitivity of 18F-fluorocholine: PET localization in primary hyperparathyroidism

BACKGROUND

Preoperative parathyroid imaging guides surgeons during parathyroidectomy. This study evaluates the clinical impact of ¹⁸F-fluorocholine positron emission tomography for preoperative parathyroid localization on patients with primary hyperparathyroidism.

METHODS

Patients with primary hyperparathyroidism and indications for parathyroidectomy had simultaneous ¹⁸F-fluorocholine positron emission tomography imaging/magnetic resonance imaging. In patients who underwent subsequent parathyroidectomy, cure was based on lab values at least 6 months after surgery. Location-based sensitivity and specificity of ¹⁸F-fluorocholine positron emission tomography imaging was assessed using 3 anatomic locations (left neck, right neck, and mediastinum), with surgery as the gold standard.

RESULTS

In 101 patients, ¹⁸F-fluorocholine positron emission tomography localized at least 1 candidate lesion in 93% of patients overall and in 91% of patients with previously negative imaging, leading to a change in preoperative strategy in 60% of patients. Of 76 patients who underwent parathyroidectomy, 58 (77%) had laboratory data at least 6 months postoperatively, with 55/58 patients (95%) demonstrating cure. ¹⁸F-fluorocholine positron emission tomography successfully guided curative surgery in 48/58 (83%) patients, compared with 20/57 (35%) based on ultrasound and 13/55 (24%) based on sestamibi. In a location-based analysis, sensitivity of ¹⁸F-fluorocholine positron emission tomography (88.9%) outperformed both ultrasound (37.1%) and sestamibi (27.5%), as well as ultrasound and sestamibi combined (47.8%).

CONCLUSION

Long-term results in the first cohort in the United States to use ¹⁸F-fluorocholine positron emission tomography for parathyroid localization confirm its utility in a challenging cohort, with better sensitivity than ultrasound or sestamibi.

Primary Hyperparathyroidism: Defining the Appropriate Preoperative Imaging Algorithm

Primary hyperparathyroidism is a common and potentially debilitating endocrine disorder for which surgery is the only curative treatment. Preoperative imaging is always recommended, even in cases of conventional bilateral neck exploration, with a recognized role for 99mTc-sestamibi scintigraphy in depicting ectopic parathyroid lesions. Scintigraphy can also play a major role in guiding a targeted, minimally invasive parathyroidectomy. However, the ability to recognize multiple-gland disease (MGD) varies greatly depending on the imaging protocol used. Preoperative diagnosis of MGD is important to reduce the risks of conversion to bilateral surgery or failure. In this article we discuss imaging strategies before first surgery as well as in the case of repeat surgery for persistent or recurrent primary hyperparathyroidism. We describe a preferred algorithm and alternative options. Dual-tracer 99mTc-sestamibi/123I subtraction scanning plus neck ultrasound is the preferred first-line option. This approach should improve MGD detection and patient selection for minimally invasive parathyroidectomy. Second-line imaging procedures in case of negative or discordant first-line imaging results are presented. High detection rates can be obtained with 18F-fluorocholine PET/CT or with 4-dimensional CT. The risk of false-positive results should be kept in mind, however. Adding a contrast-enhanced arterial-phase CT acquisition to conventional 18F-fluorocholine PET/CT can be a way to improve accuracy. We also briefly discuss other localization procedures, including 11C-methionine PET/CT, MRI, ultrasound-guided fine-needle aspiration, and selective venous sampling for parathyroid hormone measurement.

18F-Fluorocholine Positron Emission Tomography/Computed Tomography is a Highly Sensitive but Poorly Specific Tool for Identifying Malignancy in Thyroid Nodules with Indeterminate Cytology: The Chocolate Study

Background: Refining the risk of malignancy in patients presenting with thyroid nodules with indeterminate cytology (IC) is a critical challenge. We investigated the performances of ¹⁸F-fluorocholine (FCH) positron emission tomography/computed tomography (PET/CT) to predict malignancy. Methods: Between May 2016 and March 2019, 107 patients presenting with a thyroid nodule ≥15 mm with IC and eligible for surgery were included in this prospective study. Head-and-neck PET/CT acquisitions were performed 20 and 60 minutes after injection of 1.5 MBq/kg of FCH. PET/CT acquisition was scored positive when maximal standardized uptake value in the IC nodule was higher than in the thyroid background. Pathology was the gold standard for diagnosis. Results: At pathology, 19 (18%) nodules were malignant, 87 were benign, and one was a noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). Sensitivity, specificity, accuracy, positive-predictive value (PPV), and negative-predictive value (NPV) of FCH PET/CT in detecting cancer or NIFTP were 90%, 50%, 55%, 29%, and 96% at 20 minutes and 85%, 49%, 67%, 28%, and 94% at 60 minutes, respectively. Higher specificity (58% vs. 33%, p = 0.01) was observed in nononcocytic (n = 72) than in oncocytic IC nodules (n = 35). The pre-PET/CT probability of cancer or NIFTP in Bethesda III-IV nodules was 11% and the post-PET/CT probability was 19% in PET-positives and 0% in PET-negatives. In retrospective analysis, 42% of surgeries would have been unnecessary after PET/CT and 81% before (p < 0.001), resulting in a hypothetical 48% reduction (95% confidence interval [32-64]). Conclusions: FCH PET/CT offers high NPV to reliably exclude cancer in PET-negative IC nodules, but suffers from low PPV, particularly in those with oncocytic cytology. ClinicalTrials.gov identifier: NCT02784223.

Diagnostic Value of Choline PET in the Preoperative Localization of Hyperfunctioning Parathyroid Gland(s): A Comprehensive Overview

Hyperparathyroidism is a metabolic disorder characterized by the excessive production of the parathyroid hormone. The diagnosis is based on clinical and laboratory data. In most cases the only treatment is surgery and a correct preoperatory localization of the hyperfunctioning parathyroid gland(s) is essential. Currently, ultrasonography combined with [^99mTc]Tc-MIBI parathyroid scintigraphy, optionally associated with single photon emission computed tomography/computed tomography (SPECT/CT), represent the standard preoperative imaging. In recent years, a number of studies have evaluated the potential role of choline positron emission tomography (PET) in hyperparathyroidism with promising results. Most of the recent evidence underlined its higher sensitivity and diagnostic accuracy in the localization of hyperfunctioning parathyroid glands. Choline PET has a higher spatial resolution that is useful for the detection of smaller parathyroid glands and it also has shorter examination times and favorable radiation exposure. These are just a few of the aspects that support it to overcome traditional imaging. Moreover, from the preliminary data, the choline uptake mechanism seems to also have an impact on its better performance. For these reasons, if first used as second level imaging in patients with negative or inconclusive traditional imaging results, several authors have supported its use as a first line investigation. This comprehensive overview aims to provide an accurate description of the preliminary results available in the literature about the use of choline PET/CT in hyperparathyroidism and to compare these results with the performance of traditional imaging methods.

Will 18F-fluorocholine PET/CT replace other methods of preoperative parathyroid imaging?

INTRODUCTION

Primary hyperparathyroidism (PHPT) is a common endocrine disorder usually due to hyperfunctioning parathyroid glands (HPs). Surgical removal of the HPs is the main treatment for PHPT, making the correct detection and localization of HPs crucial to guiding targeted and minimally invasive surgical treatment in patients with PHPT. To date, different imaging methods have been used to detect and localize HPs, including radiology, nuclear medicine, and hybrid techniques.

METHODS

The present work discusses the role and value of different imaging methods in PHPT and, particularly, evaluates the potential role of ¹⁸F-fluorcholine PET/CT as a "one-stop-shop" method for preoperative parathyroid localization in patients with PHPT.

DISCUSSION

Cervical ultrasound (US) and parathyroid scintigraphy using ^99mTc-MIBI are the most commonly employed methods in clinical practice. More recently, four-dimensional computed tomography (4D CT) and positron emission tomography (PET) with radiolabeled choline have emerged as useful alternatives in cases of negative or discordant findings from first-line imaging methods.

CONCLUSIONS

Due to the excellent diagnostic performance of radiolabeled choline PET/CT and the low radiation burden, this technique seems to be an ideal candidate to substitute current imaging procedures including US, MIBI scintigraphy, 4D CT and MRI and perform a fast and reliable "one-stop-shop" preoperative localization of HP in patients with PHPT, including challenging cases of postoperative persistent/recurrent disease.

Misleading localization by 18F-fluorocholine PET/CT in familial hypocalciuric hypercalcemia type-3: a case report

BACKGROUND

Familial hypocalciuric hypercalcemia (FHH) is a heterogeneous autosomal-dominant disorder of calcium hemostasis that may be difficult to distinguish clinically from mild primary hyperparathyroidism. Loss-of-function mutations mainly involving Arg15 residue of the adaptor-related protein complex 2, sigma subunit 1 (AP2S1) cause a rarer, more recently recognized form of FHH, FFH type-3. Recently, ¹⁸F-fluorocholine positron emission tomography/computed tomography (FCH-PET/CT) showed superior sensitivity to conventional imaging in localizing parathyroid adenomas. We report a new FFH type-3 patient who underwent unnecessary parathyroidectomy in association with misleading FCH-PET/CT imaging.

CASE PRESENTATION

A 29-year old woman was initially evaluated for parathyroid hormone (PTH)-dependent hypercalcemia in 2013. Medical history was positive only for chronic constipation and malaise with no personal or family history of hypercalcemia, kidney stones, or neck surgery. Over seven years, serum calcium level was 2.51-2.89 mmol/L with concomitant PTH level of 58.7-94.8 mmol/L. Serum phosphate levels were in the low/low normal range. Serum creatinine and magnesium levels were normal. 25-hydroxy vitamin D level was 13 nmol/L. 24-hour urine calcium level was 1.92 mmol/day but increased to 6.99 mmol/day after treatment with cholecalciferol 1000 IU daily. Bone mineral density and renal ultrasound were normal. Parathyroid ultrasound showed two hypoechoic nodules inferior to the left and right thyroid lobes; however, ^99mtechnitium-sestamibi scans (2013, 2016, 2018) were negative. FCH-PET/CT (2019) showed focal uptake co-localizing with the nodule inferior to the left thyroid lobe. The patient underwent left inferior parathyroidectomy and pathology was consistent with parathyroid hyperplasia. However, postoperatively, serum calcium and PTH levels remained elevated and FCH-PET/CT and ultrasound showed persistence of the uptake/nodule. Whole exome sequencing showed Arg15Cys mutation in the AP2S1 gene characteristic of FHH type-3.

CONCLUSIONS

In this new case of FHH type-3, FCH-PET/CT failed to localize to the hyperplastic parathyroid glands and localized instead to apparently a lymph node. This, together with increased urinary calcium after vitamin D supplementation, led to unnecessary parathyroidectomy. Given the increasingly lower cost of genetic testing and the cost of follow up and unnecessary surgery, it may prudent to include genetic testing for FHH early on in patients with mild PTH-dependent hypercalcemia.

Intraoperative Detection of Hyperplastic Parathyroid Gland With Positron Emitter 18F-Fluorocholine and Handheld Probe

We present the first intraoperative detection of a hyperplastic parathyroid gland with a positron emitter F-fluorocholine and handheld probe, with the estimation of the absorbed dose to the surgeon and surgical staff. Intraoperative positron emitter detection enabled the resection of a small parathyroid gland, resulting in normal postoperative values of PTH and serum calcium in a 69-year-old woman. Calculated whole-body dose to the surgical staff and surgeons' fingers is well below the annual limits for exposed workers and the general public. Intraoperative F-FCH detection with handheld probe is a safe and feasible method for localizing small parathyroid glands.

18F-choline PET/CT and PET/MRI in primary and recurrent hyperparathyroidism: a systematic review of the literature

The aims of the present systematic review were to: (1) assess the role of ¹⁸F-fluorocholine (FCH) positron emission tomography (PET) with computed tomography (CT) and PET with magnetic resonance imaging (MRI) in patients with biochemically known hyperparathyroidism; (2) compare the diagnostic performance of FCH PET/CT or PET/MRI with conventional morphological and functional imaging. A literature search until December 2019 was performed in the PubMed, Scopus and Web of Science databases, using the terms “choline” AND “PET” AND “hyperparathyroidism”. The search was conducted with and without the addition of filters (e.g., language: English only; type of article: original article; subjects: humans only) and selecting only articles published in the last 5 years. Twenty-three articles and 1112 patients were considered. Different FCH PET/CT acquisition protocols were adopted across the studies, using dynamic, early or delayed scans. FCH PET/CT proved more accurate than ultrasonography (US) or 99mTc-sestamibi single-photon emission tomography (SPET). PET/MRI also seemed to be more accurate than MRI alone in detecting benign parathyroid lesions. FCH PET/CT is more accurate than conventional morphological and functional imaging modalities (US or SPET) for the detection of benign parathyroid lesions. It could, therefore, be a reliable tool in both primary and recurrent hyperparathyroidism.

18F-fluorocholine PET/CT in MEN1 Patients with Primary Hyperparathyroidism

BACKGROUND

Primary hyperparathyroidism (HPT1) is the most frequent endocrinopathy in multiple endocrine neoplasia type 1 (MEN1). Its surgical management is challenging. We aimed to describe and compare the imaging findings of parathyroid ultrasound (US), sestaMIBI scintigraphy (sestaMIBI), and ¹⁸F-fluorocholine (FCH) PET/CT in a series of MEN1 patients with HPT1.

METHODS

Retrospective analysis of a cohort of MEN1 patients with HPT1 assessed by parathyroid US, sestaMIBI scintigraphy and SPECT/CT, and FCH-PET/CT for potential surgery between 2015 and 2019.

RESULTS

Twenty-two patients with a confirmed diagnosis of MEN1 who presented with HPT1 and were assessed by the 3 imaging modalities were included. After imaging workups, 11 patients were operated on for the first time, 4 underwent a redo surgery, and 7 did not undergo an operation. The overall patient-based positivity rate of imaging was 91% (20 of 22) for parathyroid US and 96% (21 of 22) for both sestaMIBI and FCH-PET/CT. The 3 imaging modalities demonstrated negative findings in 1/22 patient who did not undergo surgery. Overall, 3 pathologic glands were not detected by any imaging technique. SestaMIBI and FCH-PET/CT both resulted in the same 3 false-positive results in ectopic areas with a significant uptake on two thymic carcinoid tumors and one inflammatory lymph node. FCH-PET/CT provided more surgically relevant data than sestaMIBI in 4/11 patients with initial surgery and in 1/4 patient who underwent redo surgery.

CONCLUSIONS

Compared to sestaMIBI scintigraphy, FCH-PET/CT provides additional information regarding the number of pathologic parathyroid glands and their localization in MEN1 patients with HPT1.

18F-choline PET/4D CT in hyperparathyroidism: correlation between biochemical data and study parameters

BACKGROUND

Hyperparathyroidism (HPT) is characterised by increased levels of parathyroid hormone (HPT), surgical excision being the only definitive curative option. After establishing the need for surgery, it is essential to identify the parathyroid glands in the preoperative period to use a minimally invasive approach. Negativity and / or discrepancy in first-line studies (ultrasound and Tc-99m MIBI parathyroid scintigraphy) require more accurate images to reduce the likelihood of bilateral cervical exploration or reintervention.

OBJECTIVES

a) To demonstrate the sensitivity of ¹⁸F-fluorocholine (¹⁸F-choline) positron emission tomography (PET)/4D computed tomography (4D CT) in HPT. b) To check whether there is a correlation between calcaemia and preoperative PTH versus size and early and late SUVmax (Standardized Uptake Value) of the gland, determined by ¹⁸F-choline PET/4D CT and c) to study the behaviour of parathyroid lesions with intravenous contrast (IV).

MATERIAL AND METHODS

A total of 28 patients were included between 2016 and 2019 in a single institution. Prospective observational cohort study. Correlations were analysed using Pearson's coefficient for variables with normal distribution and Spearman (rho) for those with non-normal distribution. Anatomopathological analysis was the benchmark standard to determine sensitivity was. A p<.05 was interpreted as significant. STATA 13 software was used.

RESULTS

Of the 28 patients who underwent ¹⁸F-choline PET/4D CT, 18 were operated. Of the 26 lesions diagnosed by ¹⁸F-choline PET/4D CT as suggestive of parathyroid lesions, 23 corresponded to glandular disease (adenoma or hyperplasia) establishing a sensitivity of 88.5%. There was a correlation between the patient's preoperative PTH and the maximum size of the gland on ¹⁸F-choline PET/4D CT. (Spearman=.66; p=.0014). The parathyroid lesions showed, in addition to IV contrast enhancement, distinctive behavioural characteristics identified as highly suggestive.

CONCLUSIONS

18F-choline PET/CT 4D is an anatomical and functional study with high sensitivity in patients with HPT with negative or discrepant first-line studies. Preoperative PTH showed a correlation with maximum gland size on ¹⁸F-choline PET/CT 4D. Parathyroid lesions behave in a highly suggestive way and are enhanced by IV contrast.

Evaluation of the performance of ultrasonography and 99mTc-sestamibi scintigraphy for primary hyperparathyroidism surgery

INTRODUCTION

Minimally invasive surgery has become the standard surgical attitude in primary hyperparathyroidism. It requires precise preoperative lesion localization. The aim of the present study was to evaluate the performance of ultrasonography and 99mTc-sestamibi scintigraphy in minimally invasive surgery for primary hyperparathyroidism.

MATERIALS AND METHODS

A retrospective study included all patients managed surgically for primary hyperparathyroidism between January 2008 and November 2017 in the University Hospital of Brest (France). Two hundred and seventy-three patients underwent ultrasonography and 99mTc-sestamibi scintigraphy. Results determined intrinsic (sensitivity and specificity) and extrinsic (positive and negative predictive values) performance on per-patient and per-gland analysis. Demographic, preoperative, interventional and cure data were compared according to ultrasonography and scintigraphy results, distinguishing 3 patient groups: concordant n=156, discordant n=99, negative n=18.

RESULTS

On per-gland analysis, sensitivity was 70% for ultrasound, 74% for 99mTc-sestamibi scintigraphy and 81% for associated ultrasound-scintigraphy; positive predictive values were 89%, 91% and 96%, respectively. Gland volume and concomitant thyroid pathology rates differed significantly (both p=0.003) between the 3 imaging results groups.

CONCLUSION

The performance of associated ultrasound-99mTc-sestamibi-scintigraphy provided a positive predictive value of 96%. Combining the two techniques reduced surgical morbidity.

Localization of Parathyroid Disease in Reoperative Patients with Primary Hyperparathyroidism

The localization of persistent or recurrent disease in reoperative patients with primary hyperparathyroidism presents challenges for radiologists and surgeons alike. In this article, we summarize the relevant imaging modalities, compare their accuracy in identifying reoperative disease, and outline their advantages and disadvantages. Accurate localization by preoperative imaging is a predictor of operative success, whereas negative or discordant preoperative imaging is a risk factor for operative failure. Ultrasound is a common first-line modality because it is inexpensive, accessible, and radiation-free. However, it is highly operator-dependent and less accurate in the reoperative setting than in the primary setting. Sestamibi scintigraphy is superior to ultrasound in localizing reoperative disease but requires radiation, prolonged imaging times, and reader experience for accurate interpretation. Like ultrasound, sestamibi scintigraphy is less accurate in the reoperative setting because reoperative patients can exhibit distorted anatomy, altered perfusion of remaining glands, and interference of radiotracer uptake. Meanwhile, four-dimensional computed tomography (4DCT) is superior to ultrasound and sestamibi scintigraphy in localizing reoperative disease but requires the use of radiation and intravenous contrast. Both 4DCT and magnetic resonance imaging (MRI) do not significantly differ in accuracy between unexplored and reoperative patients. However, MRI is more costly, inaccessible, and time-consuming than 4DCT and is inappropriate as a first-line modality. Hybrid imaging with positron emission tomography and computed tomography (PET/CT) may be a promising second-line modality in the reoperative setting, particularly when first-line modalities are discordant or inconclusive. Lastly, selective venous sampling should be reserved for challenging cases in which noninvasive modalities are negative or discordant. In the challenging population of reoperative patients with PHPT, a multimodality approach that utilizes the expertise of high-volume centers can accurately localize persistent or recurrent disease and enable curative parathyroidectomy.

Added value of 18F-fluorocholine positron emission tomography-computed tomography in presurgical localization of hyperfunctioning parathyroid glands after dual tracer subtraction scintigraphy failure: A retrospective study of 47 patients

Hyperparathyroidism is a common endocrine disorder. The precise localization of causal parathyroid gland is crucial to guide surgical treatment. Several studies report the added value of 18F-fluorocholine (FCH) positron emission tomography-computed tomography (PET/CT) as second line imaging but rely on suboptimal first-line imaging using 99mTc-sestaMIBI dual phase scintigraphy. The aim of this study is to evaluate the percentage of successful parathyroid localization with FCH PET/CT after failure of a more sensitive first-line detection protocol associating neck ultrasonography and 99mTc-Pertechnetate/99mTc-sestaMIBI dual tracer subtraction scintigraphy.We included retrospectively 47 patients who underwent a FCH PET/CT as second line imaging for biologically proven primary hyperparathyroidism from November 2016 to October 2018 in Godinot Institute (Reims, France). 99mTc-Pertechnetate/99mTc-sestaMIBI dual tracer subtraction scintigraphy and neck ultrasonography were used as first-line imaging and failed to localize the causal parathyroid lesion in all cases.FCH PET/CT demonstrated at least 1 parathyroid target lesion in 29 patients (62%). 21/29 patients underwent surgery. Target lesions corresponded histologically to hyperfunctioning parathyroid glands for all 21 patients and surgery was followed by hyperparathyroidism biological resolution. Calcium serum levels were associated to FCH PET/CT positivity (P = .002) and a trend toward significance was seen for Parathyroid hormone (PTH) levels (P = .09).FCH PET/CT is a promising tool in second-line parathyroid imaging. Large prospective studies and cost-effectiveness analyses are needed to precise its role.

A Hungry Bone Syndrome Predicted by 18F-Fluorocholine PET/CT

Predicting hungry bone syndrome (HBS) after surgical cure of primary hyperparathyroidism (PHPT) can be challenging. A 57-year-old man diagnosed with PHPT was assessed preoperatively by F-fluorocholine PET/CT. An intense and diffuse tracer uptake of the axial and peripheral skeleton was visualized, in addition to a pathologic uptake suggestive of hyperfunctioning parathyroid gland. After the removal of a parathyroid adenoma, a severe and prolonged HBS requiring high doses of calcium and active metabolites of vitamin D was observed. This observation suggests that intense and diffuse bone uptake on F-fluorocholine PET/CT could be a predictive factor for HBS in patients with PHPT.

F18-choline/C11-choline PET/CT thyroid incidentalomas

INTRODUCTION

Thyroid incidentaloma is defined as a thyroid lesion incidentally and newly detected by imaging techniques performed for an unrelated purpose and especially for a non-thyroid disease. Aim of this review is to evaluate the prevalence and clinical significance of focal incidental radiolabelled choline uptake in the thyroid gland (CTI) revealed by PET or PET/CT.

METHODS

A comprehensive computer literature search of the PubMed/MEDLINE, Scopus, and Embase databases was conducted to find relevant published articles about the prevalence and clinical significance of CTIs detected by PET or PET/CT in patients studied for other oncologic purposes.

RESULTS

Fifteen articles (14 case reports, one retrospective study on a larger population sample) were included in the systematic review. Considering the case reports, 7/14 CTIs were benign and 7/14 malignant. In the retrospective study on a larger population sample, 14/15 CTIs which underwent further investigations were benign.

CONCLUSION

Despite very rare but probably underestimated, CTIs frequently signal in the presence of unexpected lesions in the thyroid that differ from the indicated reason for which the patient was initially scanned, and the risk of malignancy is not negligible.

Novel PET tracers: added value for endocrine disorders

Nuclear medicine has been implicated in the diagnosis and treatment of endocrine disorders for several decades. With recent development of PET tracers, functional imaging now plays a major role in endocrine tumors enabling with high performance to their localization, characterization, and staging. Besides ¹⁸F-FDG, which may be used in the management and follow-up of endocrine tumors, new tracers have emerged, such as ¹⁸F-DOPA for neuroendocrine tumors (NETs) (medullary thyroid carcinoma, pheochromocytomas and paragangliomas and well-differentiated NETs originating from the midgut) and ¹⁸F-Choline in the field of primary hyperparathyroidism. Moreover, some peptides such as somatostatin analogs can also be used for peptide receptor radionuclide therapy. In this context, Gallium-68 labeled somatostatin analogs (⁶⁸Ga-SSA) can help to tailor therapeutic choices and follow the response to treatment in the so-called "theranostic" approach. This review emphasizes the usefulness of these three novel PET tracers (¹⁸F-Choline, ¹⁸F-FDOPA, and ⁶⁸Ga-SSA) for primary hyperparathyroidism and neuroendocrine tumors.

Parathyroid Imaging by 18F-Fluorocholine PET/CT in Patients With Primary Hyperparathyroidism and Inconclusive Conventional Methods: Clinico-Pathological Correlations

18F-fluorocholine positron emission tomography/computed tomography (FCH) was performed after inconclusive neck ultrasound and 99Tc-sestaMIBI SPECT (MIBI) scintigraphy in patients with primary hyperparathyroidism (PHPT) to localize abnormal parathyroid glands before surgery. The results were retrospectively evaluated and compared to postoperative histopathological findings. 13 patients with PHPT were enrolled (mean age 64.3 years, preoperative calcium 2.74 mmol/l and parathyroid hormone 114.6 ng/l). FCH localized hyperfunctioning parathyroid glands in 12 patients of 13 (per patient sensitivity 92 % and positive predictive value (PPV) 100 %). Fourteen parathyroid lesions (11 adenomas, 3 hyperplastic glands) were resected with a mean size of 11.9 mm (per lesion sensitivity 93 % and PPV 81 %). Four adenomas and one hyperplastic gland were composed of only chief cells, whereas five lesions contained both chief and oxyphil cells. In three patients an exclusively oxyphil adenoma was found, surprisingly with negative MIBI scintigraphy in spite of a high mitochondria content in the oxyphil parathyroid cells. 12 of 13 patients had thyroid disease. In our limited study sample, FCH correctly identified parathyroid adenomas and/or hyperplastic glands in 92 % of patients with previously inconclusive conventional imaging. Unlike MIBI, FCH successfully localized small, hyperplastic and multiple hyperfunctioning parathyroid glands, irrespective of their histopathological composition.

Diagnostic Performance of F-18 Fluorocholine PET/CT for Parathyroid Localization in Hyperparathyroidism: a Systematic Review and Meta-Analysis

The purpose of the current study was to investigate the diagnostic performance of F-18 Fluorocholine (FCH) positron emission tomography/computed tomography (PET/CT) for localization of hyperfunctioning parathyroid gland in patients with hyperparathyroidism (HPT) through a systematic review and meta-analysis. The MEDLINE/PubMed and EMBASE database, from the earliest available date of indexing through April 30, 2018, were searched for studies evaluating the diagnostic performance of F-18 FCH PET/CT for localization of hyperfunctioning parathyroid gland in patients with HPT. We determined the sensitivities and specificities across studies, calculated positive and negative likelihood ratios (LR+ and LR-), and constructed summary receiver operating characteristic curves. Across eight studies (272 patients), the pooled sensitivity for F-18 FCH PET/CT was 0.90 (95% CI, 0.86-0.94) without heterogeneity (I² = 7.1) and a pooled specificity of 0.94 (95% CI, 0.90-0.96) with heterogeneity (I² = 79.8). Likelihood ratio (LR) syntheses gave an overall positive likelihood ratio (LR+) of 5.3 (95% CI, 1.2-24.3) and negative likelihood ratio (LR-) of 0.15 (95% CI, 0.08-0.29). The pooled diagnostic odds ratio (DOR) was 38 (95% CI, 8-174). Hierarchical summary receiver operating characteristic (ROC) curve indicates that the areas under the curve were 0.9492 (SE, 0.0215). In meta-regression analysis, no definite variable was the source of the study heterogeneity. The current meta-analysis showed the high sensitivity and specificity of F-18 FCH PET/CT for localization of hyperfunctioning parathyroid gland. At present, the literature regarding the use of F-18 FCH PET/CT for localization of hyperfunctioning parathyroid gland remains still limited; thus, further large multicenter studies would be necessary to substantiate the diagnostic accuracy of F-18 FCH PET/for localization of hyperfunctioning parathyroid gland in patients with HPT.