Fluorine-18 fluorocholine PET-CT localizes hyperparathyroidism in patients with inconclusive conventional imaging: a multicenter study from the Netherlands

Incidental Detection of Brain Metastases From a Pulmonary Large Cell Neuroendocrine Carcinoma at 18 F-Fluorocholine PET/CT in a Context of Primary Hyperparathyroidism

ABSTRACT

This 65-year-old man suffering from hypercalcemia in a context of hyperparathyroidism treated by calcimimetics was referred to our institution to perform an 18 F-fluorocholine PET/CT in order to localize the pathological parathyroid gland(s). We incidentally discovered a brain metastatic pulmonary large cell neuroendocrine carcinoma in addition to a parathyroid adenoma. This case illustrates the value of FCH PET/CT in hyperparathyroidism workup event under calcimimetic treatment, as well as the potential of FCH PET/CT to reveal occult malignancies.

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.

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.

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.

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.

Evolving Role of [18F]Flurocholine PET/CT in Assessing Primary Hyperparathyroidism: Can It Be Considered the First-Line Functional Imaging Approach?

The accurate detection of hyperfunctioning parathyroid tissue (HFPT) is pivotal in the preoperative assessment of primary hyperparathyroidism (PHPT). PET/CT using [¹⁸F]fluorocholine ([¹⁸F]FCH) showed superior diagnostic performance compared to conventional functional imaging modalities. We aimed to evaluate the diagnostic performance of [¹⁸F]FCH PET/CT as a first-line functional imaging approach in patients with clinically diagnosed PHPT. The imaging and clinical data of 321 PHPT patients, including 271 overt PHPT and 50 mild PHPT, who underwent [¹⁸F]FCH PET/CT as first-line imaging were analysed in this retrospective study. Histopathology was the reference standard. In case of no available histopathology evaluation (conservative management), imaging and clinical follow-ups were considered reference standards. In the overt group (n = 271), [¹⁸F]FCH PET/CT showed sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of 0.99, 0.91, 1.00, 0.80, and 0.99, respectively. Regarding the correlation of the index lesions and initial laboratory data, all [¹⁸F]FCH PET/CT parameters (SUVs, SULs, and mSAD) were significantly correlated with the serum iPTH level. Additionally, SUVmax, SULpeak, and mSAD were significantly associated with the serum calcium level. In the mild group (n = 50), [¹⁸F]FCH PET/CT showed a sensitivity, specificity, PPV, NPV, and accuracy of 0.93, 0.75, 0.95, 0.67, and 0.90. In conclusion, [¹⁸F]FCH PET/CT revealed high diagnostic performance in the detection of HFPTs and the potential to be considered as a first-line imaging modality in the assessment of PHPT, including both overt and mild types. However, its cost-benefit concerning the clinical impact of early PHPT detection should be investigated in future studies.

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.

Detection and localization of hyperfunctioning parathyroid glands on [18F]fluorocholine PET/ CT using deep learning - model performance and comparison to human experts

BACKGROUND

In the setting of primary hyperparathyroidism (PHPT), [18F]fluorocholine PET/CT (FCH-PET) has excellent diagnostic performance, with experienced practitioners achieving 97.7% accuracy in localising hyperfunctioning parathyroid tissue (HPTT). Due to the relative triviality of the task for human readers, we explored the performance of deep learning (DL) methods for HPTT detection and localisation on FCH-PET images in the setting of PHPT.

PATIENTS AND METHODS

We used a dataset of 93 subjects with PHPT imaged using FCH-PET, of which 74 subjects had visible HPTT while 19 controls had no visible HPTT on FCH-PET. A conventional Resnet10 as well as a novel mPETResnet10 DL model were trained and tested to detect (present, not present) and localise (upper left, lower left, upper right or lower right) HPTT. Our mPETResnet10 architecture also contained a region-of-interest masking algorithm that we evaluated qualitatively in order to try to explain the model's decision process.

RESULTS

The models detected the presence of HPTT with an accuracy of 83% and determined the quadrant of HPTT with an accuracy of 74%. The DL methods performed statistically worse (p < 0.001) in both tasks compared to human readers, who localise HPTT with the accuracy of 97.7%. The produced region-of-interest mask, while not showing a consistent added value in the qualitative evaluation of model's decision process, had correctly identified the foreground PET signal.

CONCLUSIONS

Our experiment is the first reported use of DL analysis of FCH-PET in PHPT. We have shown that it is possible to utilize DL methods with FCH-PET to detect and localize HPTT. Given our small dataset of 93 subjects, results are nevertheless promising for further research.

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.

Diagnostic Performance of 18F-Choline Positron Emission Tomography/Contrast-Enhanced Computed Tomography in Adenoma Detection in Primary Hyperparathyroidism after Inconclusive Imaging: A Retrospective Study of 215 Patients

Simple Summary

Primary hyperparathyroidism is a common pathology. Its curative treatment is based on surgery with precise localisation of the affected parathyroid glands. Our retrospective study aimed to assess the diagnostic performance of a novel imaging method called ¹⁸F-choline positron emission tomography/contrast-enhanced computed tomography (PET/ceCT) in adenoma detection after inconclusive imaging. ¹⁸F-choline PET/ceCT presented excellent diagnostic performance as a second-line imaging method. These results confirm its utility, and it could replace Tc99m-sestamibi single photon emission CT/CT as the first-line imaging method in patients with primary hyperparathyroidism.

Abstract

This large, retrospective, single-centre study evaluated the diagnostic performance of ¹⁸F-choline positron emission tomography/contrast-enhanced computed tomography (PET/ceCT) in preoperative parathyroid adenoma detection in primary hyperparathyroidism cases after negative/inconclusive ultrasound or other imaging findings. We included patients who underwent surgery and ¹⁸F-choline PET/ceCT for inconclusive imaging results between 2015 and 2020. We compared the ¹⁸F-choline PET/ceCT results with surgical and histopathological findings and identified the variables influencing the correlation between ¹⁸F-choline PET/ceCT and surgical findings. Of 215 enrolled patients, 269 glands (mean lesion size, 10.9 ± 8.0 mm) were analysed. There were 165 unilocular and 50 multilocular lesions; the mean preoperative calcium level was 2.18 ± 0.19 mmol/L. Among 860 estimated lesions, 219 were classified as true positive, 21 as false positive, and 28 as false negative. The per-lesion sensitivity was 88.66%; specificity, 96.57%; positive predictive value, 91.40%; and negative predictive value, 95.39%. The detection and cure rates were 82.0% and 95.0%, respectively. On univariate and multivariate analyses, the maximum standardised uptake value (SUVmax), lesion size, and unilocularity correlated with the pathologic findings of hyperfunctioning glands. ¹⁸F-choline PET/ceCT presents favourable diagnostic performance as a second-line imaging method, with SUVmax, lesion size, and unilocularity predicting a high correlation between the ¹⁸F-choline PET/ceCT and surgical findings.

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.

C-11 methionine positron emission tomography scans improve the preoperative localization of pathologic parathyroid glands in primary hyperparathyroidism

BACKGROUND AND AIMS

Preoperative localization of pathologic parathyroid glands is essential in the preparation of a parathyroidectomy. We evaluated the use of a C-11 methionine positron emission tomography/computed tomography scan in a 7-year period in selected patients with primary hyperparathyroidism. The indications to perform a C-11 methionine positron emission tomography/computed tomography were either persistent primary hyperparathyroidism after parathyroidectomy or inconclusive preoperative localization on ultrasound and sestaMIBI.

MATERIALS AND METHODS

A group of 36 patients was referred for a C-11 methionine positron emission tomography/computed tomography. Biochemical data, pathology, and results of sestaMIBI were collected retrospectively. The primary hyperparathyroidism patients were divided into two groups. In group 1 (N = 17), the C-11 methionine positron emission tomography/computed tomography was performed before parathyroidectomy. In group 2 (N = 19), the C-11 methionine positron emission tomography/computed tomography was performed after unsuccessful parathyroidectomy and before a reoperation.

RESULTS

Overall, in 30 of the 36 patients (83%), C-11 methionine positron emission tomography/computed tomography identified a true-positive pathologic parathyroid gland confirmed by an experienced pathologist, consistent with a positive predictive value of 91%. In group 1, 94% of the patients (N = 16) had pathologic parathyroid tissue identified by C-11 methionine positron emission tomography/computed tomography. This resulted in a clinical benefit in 13 patients (76%). In group 2, the benefit was slightly lower, as 74% of the patients (N = 14) had a true-positive C-11 methionine positron emission tomography/computed tomography scan resulting in a clinical benefit in nine patients (47%).

CONCLUSION

In two selected groups of patients planned for an initial operation or reoperation of primary hyperparathyroidism and inconclusive conventional imaging, we found C-11 methionine positron emission tomography/computed tomography to give parathyroid surgeons a clinical benefit in the majority of cases, electing the patients for unilateral surgery.

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.

New therapies for patients with multiple endocrine neoplasia type 1

In 1953, for the first time, Paul Wermer described a family presenting endocrine gland neoplasms over several generations. The transmission was autosomal dominant and the penetrance was high. Forty years later in 1997, the multiple endocrine neoplasia type 1 (MEN1) gene was sequenced, thus enabling diagnosis and early optimal treatment. Patients carrying the MEN1 gene present endocrine but also non-endocrine tumors. Parathyroid, pancreatic and pituitary impairment are the three main types of endocrine involvement. The present article details therapeutic management of hyperparathyroidism, neuroendocrine pancreatic tumors and pituitary adenomas in patients carrying the MEN1 gene. Significant therapeutic progress has in fact been made in the last few years. As concerns the parathyroid glands, screening of family members and regular monitoring of affected subjects now raise the question of early management of parathyroid lesions and optimal timing of parathyroid surgery. As concerns the duodenum-pancreas, proton-pump inhibitors are able to control gastrin-secreting syndrome, reducing mortality in MEN1 patients. Mortality in MEN1 patients is no longer mainly secondary to uncontrolled hormonal secretion but to metastatic (mainly pancreatic) disease progression. Tumor risk requires regular monitoring of morphological assessment, leading to iterative pancreatic surgery in a large number of patients. Finally, pituitary adenomas in MEN1 patients are traditionally described as aggressive, invasive and resistant to medical treatment. However, regular pituitary screening showed them to be in fact infra-centimetric and non-secreting in the majority of patients. Consequently, it is necessary to regularly monitor MEN1 patients, with regular clinical, biological and morphological work-up. Several studies showed that this regular monitoring impairs quality of life. Building a relationship of trust between patients and care provider is therefore essential. It enables the patient to be referred for psychological or psychiatric care in difficult times, providing long-term support and preventing any breakdown in continuity of care.

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.

11C-Methionine PET/CT in patients with primary hyperparathyroidism and inconclusive pre-operative imaging work-up: diagnostic accuracy and role of semi-quantitative analysis

OBJECTIVE

¹¹C-Methionine PET/CT (C-MET) is a promising method in detecting abnormal parathyroid glands in patients with primary hyperparathyroidism (PHPT). The first aim of the study was to evaluate which is the diagnostic role of C-MET in patients with PHPT and inconclusive pre-operative imaging. Second, we aimed to investigate whether C-MET semi-quantitative parameters may reflect biochemical and histological characteristics of involved glands.

METHODS

Patients with PHPT, undergoing C-MET after an inconclusive pre-operative imaging and having a parathyroid surgery, were retrospectively included. C-MET visual and semi-quantitative assessment was performed. Parameters, as SUV_max, SUV_peak, SUV_mean, functional lesion volume (FLV) and total lesion activity (TLA), were measured for each detected lesion; SUV_mean, FLV and TLA were calculated on 40-90% thresholds of SUV_max to define SUV_mean40-90, FLV_40-90 and TLA_40-90, respectively. Results were correlated with patients' clinical-laboratory (calcium and PTH values) and histological data (size and weight of excised glands). Mann-Whitney test was used and P value < 0.05 was considered significant.

RESULTS

Thirty-eight patients (36 female, age: 57.69 ± 15.13 years) were included. Pre-operative median calcium and PTH values were 11.1 mg/dl [interquartile range (IQR) 10.6-11.5] and 154.6 pg/ml (IQR 101.8-227.0), respectively. C-MET showed a parathyroid uptake in 30 out of thirty-eight patients (78.9%). Among 42 nodules excised, C-MET correctly detected the side of the neck (right/left) in 30/42 with sensitivity, specificity and accuracy of 79, 75 and 79%, respectively. C-MET correctly identified the exact position (superior/inferior) in 27/42 with sensitivity, specificity and accuracy of 75, 50 and 71%, respectively. SUV_peak, FLV_50-70 and TLA_40-70 were significantly (P < 0.05) higher in patients with higher PTH results. The histological size resulted significantly (P < 0.05) higher in abnormal glands with higher SUV_max, SUV_peak, FLV_40-80 and TLA_40-90, the weight was higher in glands with higher SUV_peak, SUV_mean40-50, FLV_40-80 and TLA_40-90.

CONCLUSIONS

C-MET showed a good performance in detecting hyperfunctioning parathyroid glands in PHPT patients with inconclusive pre-operative imaging. Semi-quantitative PET-derived parameters closely correlated with PTH as well as with size and weight of the excised gland, thus reflecting some biochemical and histological characteristics of involved glands.

A rare cause of persistent hyperparathyroidism

In a case of patient with persistent hypercalcemia after parathyroidectomy, different imaging techniques and particularly 18F-fluorocholine PET/CT are important to localize the adenoma even in a very unusual location.

Performance of F-18 Fluorocholine PET/CT for Detection of Hyperfunctioning Parathyroid Tissue in Patients with Elevated Parathyroid Hormone Levels and Negative or Discrepant Results in conventional Imaging

Objective

Our aim was to assess the diagnostic performance of F-18 fluorocholine (FCH) positron emission tomography/computed tomography (PET/CT) in detecting hyperfunctioning parathyroid tissue (HPT) in patients with elevated parathyroid hormone levels with negative or inconclusive conventional imaging results and to compare the findings with those obtained using technetium-99m sestamibi (MIBI) scintigraphy and neck ultrasonography (US).

Materials and Methods

Images of 105 patients with hyperparathyroidism who underwent FCH PET/CT, dual-phase MIBI parathyroid scintigraphy (median interval: 42 days), and neck US were retrospectively analyzed. The gold standard was histopathological findings for 81 patients who underwent parathyroidectomy and clinical follow-up findings in the remaining 24 patients. Sensitivities, positive predictive values (PPVs), and accuracies were calculated for all imaging modalities.

Results

Among the 81 patients who underwent parathyroidectomy, either parathyroid adenoma (n = 64), hyperplasia (n = 9), neoplasia (n = 4), or both parathyroid adenoma and hyperplasia (n = 1) were detected, except 3 patients who did not show HPT. Of the 24 (23%) patients who were followed-up without operation, 22 (92%) showed persistent hyperparathyroidism. FCH PET/CT showed significantly higher sensitivity than MIBI scintigraphy and US in detection of HPT (p < 0.01). Sensitivity, PPV, and accuracy of FCH PET/CT were 94.1% (95/101), 97.9% (95/97), and 92.4% (97/105), respectively. The corresponding values for MIBI scintigraphy and US were 45.1% (46/102), 97.9% (46/47), and 45.7% (48/105) and 44.1% (45/102), 93.8% (45/48), and 42.9% (45/105), respectively. Among the 35 patients showing negative MIBI scintigraphy and neck US findings, 30 (86%) showed positive results on FCH PET/CT. FCH PET/CT could demonstrate ectopic locations of HPT in 11 patients whereas MIBI and US showed positive findings in only 6 and 3 patients, respectively.

Conclusion

FCH PET/CT is an effective imaging modality for detection of HPT with the highest sensitivity among the available imaging techniques. Therefore, FCH PET/CT can be recommended especially for patients who show negative or inconclusive results on conventional imaging.

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.

Identification of Occult Adenomas in Primary Hyperparathyroidism With 18F-fluorocholine PET/CT

INTRODUCTION

Single parathyroid adenomas are the most common cause of primary hyperparathyroidism (PHP) in our population. Parathyroidectomy is still the only potentially curative treatment and requires preoperative localization imaging studies to perform selective surgery. In patients with negative results on conventional tests, PET/CT has demonstrated higher sensitivity rates.

METHODS

A prospective cohort study was designed, including 34 patients diagnosed with PHP between 2017 and 2019, candidates for surgery with negative preoperative localization tests with scintigraphy and MIBI SPECT/CT. All patients underwent PET/CT with 18F-Fluorocholine. The clinical, biochemical and postoperative outcome results were compared with a control group of 30 patients with positive standard tests.

RESULTS

Hyperfunctional parathyroid tissue was detected in 85% of the patients that had undergone choline PET/CT. The selective resection of the adenoma identified in these patients achieved curative criteria in 87% of the cases without undergoing bilateral cervical surgical exploration. The preoperative levels of PTH, calcemia and gland weight were significantly lower in this group compared to the control group. No differences were identified in cure criteria or approach between the 2groups.

CONCLUSION

In our study, choline PET/CT showed higher detection rates compared to the gold standard. The increase provides the opportunity to perform unilateral selected adenoma resection, especially in patients with smaller adenomas associated with lower calcemia and PTH levels and patients with previous cervical surgery.

Recent advances in the understanding and management of primary hyperparathyroidism

Primary hyperparathyroidism is a hormonal disorder whose prevalence is approximately 1–2% in the United States of America. The disease has become more recognizable to clinicians in an earlier phase and, at present, patients can be diagnosed with “classic”, “normocalcemic”, “normohormonal”, or “mild, asymptomatic” primary hyperparathyroidism. Surgery, with a focused parathyroidectomy when possible, or a four-gland exploration, is the only way to cure the disease. Cure is determined by use of intra-operative parathyroid hormone monitoring with long-term cure rates ranging from 90–95%. Newer adjuncts to surgery include CT or PET imaging and near-infrared immunofluorescence. This article highlights updates in parathyroid disease and advances in parathyroid surgery; it does not provide a comprehensive summary of the disease process or a review of surgical indications, which can be found in the AAES guidelines or NIH Symposium on primary hyperparathyroidism.

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.

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).

Parathyroid scintigraphy in primary hyperparathyroidism: comparison between double-phase and subtraction techniques and possible affecting factors

PURPOSE

Parathyroid scintigraphy is superior to other imaging techniques in detecting hyperfunctioning parathyroid glands. It is mainly performed using double-phase or dual-tracer subtraction methods. Neither of the techniques is perfect and different protocols are being used. We aimed to evaluate the accuracy of double-phase and subtraction methods in detecting abnormal gland as well as the potential effects of coexisting thyroid disease and clinical-laboratory data.

METHODS

We considered patients with primary hyperparathyroidism who underwent parathyroid surgery, after a parathyroid scintigraphy between April 2015 and February 2017. Sixty-eight patients were included; in 45 cases (66.2%), a thyroid disease was coexistent. Diagnostic performances of the two techniques were compared. The effect of thyroid disease and clinical-pathological data on examination interpretation was considered.

RESULTS

Double-phase scintigraphy showed higher sensitivity and accuracy in detecting the exact abnormal gland compared to the digital subtraction (90% and 75% vs. 76% and 66%, respectively). For double-phase technique, sensitivity and accuracy were higher in cases with no thyroid disease when compared to those with thyroid disease (92% and 86% vs. 88% and 69%, respectively). Similarly, for digital subtraction, sensitivity and accuracy were higher in the absence of thyroid disease compared to their presence (84% and 79% vs. 70% and 58%, respectively). There was no significant variation in the performance of both techniques, considering clinical-laboratory data.

CONCLUSIONS

Double-phase scintigraphy has been more accurate than digital subtraction. The presence of thyroid disease could be a possible limit, affecting the subtraction more than the double-phase technique. Clinical data did not influence the scintigraphic outcome.

Parathyroid imaging with 18F-fluorocholine PET/CT as a first-line imaging modality in primary hyperparathyroidism: a retrospective cohort study

BACKGROUND

¹⁸F-fluorocholine (FCH) PET/CT is a promising technique for visualizing hyperfunctioning parathyroid glands in hyperparathyroidism. It is still under debate whether to use this technique as a first-line imaging modality or to use it when conventional techniques such as ^99mTc-sestamibi scintigraphy or ultrasonography are inconclusive. This study evaluates FCH PET/CT as a first-line modality.

METHODS

Patients with primary hyperparathyroidism, referred between June 2015 and December 2018 for FCH PET/CT as a first-line imaging method, were included in this study. Baseline characteristics, clinical data, scan results, and type of treatment were recorded. The rate of correct detection was calculated on a per patient-based and a per lesion-based analysis. The reference standard comprised histopathological results, intraoperative response to parathyroidectomy, and clinical follow-up.

RESULTS

Two hundred and seventy-one patients were included, of which 139 patients underwent parathyroidectomy, 48 were treated with calcimimetics, and 84 patients received further follow-up without active treatment. In the surgically treated group, a single adenoma was suspected in 127 scans, double adenoma in three scans, and one scan showed evidence of three hyperfunctioning glands. In eight scans, no lesions were visualized. A total of 154 parathyroid glands were surgically removed. The rate of correct detection was calculated at 96% and 90%, on a per patient-based and per lesion-based analysis, respectively.

CONCLUSION

This retrospective study in a large cohort shows high detection rates of FCH PET/CT in primary hyperparathyroidism, which is in accordance to literature. The use of FCH PET/CT as a first-line imaging modality in preoperative planning of parathyroid surgery may therefore be a suitable choice.

Mild sporadic primary hyperparathyroidism: high rate of multiglandular disease is associated with lower surgical cure rate

BACKGROUND

Mild primary hyperparathyroidism (serum calcium ≤ 2.85 mmol/L) is the most representative form of pHPT nowadays. The aim of this study was to evaluate its subtypes and the multiglandular disease (MGD) rate as it may lower the sensitivity of preoperative parathyroid scintigraphy and the surgical cure rate.

METHODS

We retrospectively included patients with mild pHPT who underwent parathyroid dual-tracer scintigraphy with ^99mTc-MIBI SPECT/CT and surgery between January 2013 and December 2015. Cure was defined as normalization of serum calcium (or PTH in the normocalcemic form) at 6 months. MGD was defined by either two abnormal resected glands or persistent disease after resection of at least one abnormal gland.

RESULTS

We included 121 patients. Median preoperative serum calcium was 2.68 mmol/L and median PTH was 83.4 pg/mL. A total of 141 glands were resected (95 adenomas, 33 hyperplasias). The subtypes were 57% classic, 32.2% normohormonal, and 10.7% normocalcemic. MGD occurred in 23.5% of patients divided as 13%, 30%, and 64% respectively (p = 0.0011). The surgical cure rate was 85.2%. The normocalcemic form had lower cure rate than the normohormonal (45% vs 84%, p = 0.018) and classic forms (45% vs 93%, p = 0.0006). MIBI scintigraphy identified at least one abnormal lesion, later confirmed by the pathologist in 90/98 patients, making the sensitivity per patient 91.8% (95% CI 84.1-96.2%).

CONCLUSIONS

MGD is strongly associated with mild pHPT, especially the normocalcemic form where it accounts for 64% of cases. Bilateral neck exploration should be performed in this population to improve the cure rate, even if the scintigraphy shows a single focus.

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.

Update of the role of Nuclear Medicine techniques in the pre-surgical localization of primary hyperparathyroidism

Primary hyperparathyroidism is one of the most frequent endocrine disorders. Its diagnosis is biochemical. Imaging techniques are not useful for the diagnosis of this pathology; they are just tools for pre-surgical localization. In this continuing education, we will analyze the different imaging modalities used in this indication, focusing on Nuclear Medicine. The most commonly used imaging technique in this context is the parathyroid scintigraphy, nowadays double phase protocol with ^99mTc-MIBI and the double tracer with ^99mTc-MIBI/^99mTc-pertechnetate, associated in the first case to SPECT or SPECT/CT, in an early or late phase. The PET/CT with different tracers is showing good results, especially applied to cases of failure in the pre-surgical scintigraphic localization. We expose the results of the morphological imaging techniques as well as the usefulness of combining techniques.

Choline PET/CT in parathyroid imaging: a systematic review

One of the most promising imaging techniques in primary hyperparathyroidism is PET/CT with choline-based tracers. To investigate the current evidence of these tracers in localizing parathyroid adenoma, a systematic review was performed. A comprehensive literature search was carried out and eligible studies were analyzed. Data were extracted, the level of evidence was scored, and performance data were pooled to calculate the weighted detection rate. Eleven articles were included in this study. The pooled detection rate was 97 and 94% on per patient-based and per lesion-based analysis, respectively. There was considerable heterogeneity between studies and the level of evidence was determined to be 3a-, following Oxford criteria. Choline PET/CT has shown favorable results in detection of hyperfunctioning parathyroid tissue and may replace conventional technetium-99m-sestamibi scintigraphy in preoperative planning of parathyroid surgery. However, the quality of current evidence is moderate, and additional high-quality studies are needed to confirm these numbers.

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.

[18F]Fluorocholine Uptake of Parathyroid Adenoma Is Correlated with Parathyroid Hormone Level

PURPOSE

The aim of the study was to investigate the relationship between [¹⁸F]fluoromethyl-dimethyl-2-hydroxyethylammonium ([¹⁸F]FCh) positron emission tomography (PET) parameters, laboratory parameters, and postoperative histopathological results in patients with primary hyperparathyroidism (pHPT) due to parathyroid adenomas.

PROCEDURES

This retrospective study was conducted in 52 patients with biochemically proven pHPT. [¹⁸F]FCh-PET parameters (maximum standardized uptake value: SUV_max) in early phase (after 2 min) and late phase (after 50 min), metabolic volume, and adenoma-to-background ratio (ABR), preoperative laboratory results (PTH and serum calcium concentration), and postoperative histopathology (location, size, volume, and weight of adenoma) were assessed. Relationship of PET parameters, laboratory parameters, and histopathological parameters was assessed using the Mann-Whitney U test and Spearman correlation coefficient. MRI characteristics of parathyroid adenomas were also analyzed.

RESULTS

The majority of patients underwent a PET/MR scan, 42 patients (80.7 %); 10 patients (19.3 %) underwent PET/CT. We found a strong positive correlation between late-phase SUV_max and preoperative PTH level (r = 0.768, p < 0.001) and between late-phase ABR and preoperative PTH level (r = 0.680, p < 0.001). The surgical specimen volume was positively correlated with the PET/MR lesion volume (r = 0.659, p < 0.001). No significant association was observed between other [¹⁸F]FCh-PET parameters, laboratory parameters, and histopathological findings. Cystic adenomas were larger than non-cystic adenomas (p = 0.048).

CONCLUSIONS

[¹⁸F]FCh uptake of parathyroid adenomas is strongly correlated with preoperative PTH serum concentration. Therefore, the preoperative PTH level might potentially be able to predict success of [¹⁸F]FCh-PET imaging in hyperparathyroidism, with higher lesion-to-background ratios being expected in patients with high PTH. PET/MR is accurate in estimating the volume of parathyroid adenomas.

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.

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.

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

PURPOSE

To evaluate the added value of ¹⁸F-Fluorocholine (¹⁸F-FCH) PET/CT in presurgical imaging of patients with primary hyperparathyroidism (HPT) and challenging localization of the hyper-functioning parathyroid glands.

METHODS

We included 27 consecutive patients with primary HPT (19 F; median age: 58 years), with either (i) non-conclusive pre-surgical localization with ⁹⁹mTc-sestaMIBI scintigraphy and neck ultrasonography (US), (ii) recurrence of previously operated HPT, or (iii) familiar HPT with a suspicion of multiple gland disease. Histological findings and resolution of HPT were considered as the gold standard.

RESULTS

¹⁸F-FCH PET/CT was positive in 24/27 patients. Twenty-one patients underwent surgery with 27 resected lesions (14 adenomas, 11 hyperplastic glands, two hyper-functioning histologically normal glands), with resolution of HPT in 19/21 patients (90%). ¹⁸F-FCH PET/CT localized 22 lesions in 17/21 patients (per patient: sensitivity 81%, positive predictive value (PPV) 94%; per gland: sensitivity 76%, PPV 85%, specificity 91%, negative predictive value (NPV) 86%). ¹⁸F-FCH PET/CT found eight lesions which were undetectable on both ⁹⁹mTc-sestaMIBI scintigraphy and US. In patients with a familial HPT and/or a multiple gland disease, sensitivity was 100 and 79% on a per-patient and a per-gland analysis respectively, while NPV was 63%. In six patients with a persistence or recurrence of previously treated HPT, ¹⁸F-FCH PET/CT localized all lesions, both in sporadic and familiar disease.

CONCLUSIONS

¹⁸F-FCH PET/CT is a promising modality in challenging pre-surgical localization of hyper-functioning parathyroid glands, such as inconclusive standard imaging, recurrence after surgery, or suspected multiple gland disease.

Localisation of ectopic mediastinal parathyroid adenoma by 18F-fluorocholine PET/CT

We report the case of two patients with newly diagnosed primary hyperparathyroidism: a 40-year-old woman during pregnancy and a 60-year-old man with initial hypercalcaemic crisis. In the first case, a bilateral neck exploration with parathyroidectomy during the second trimester of pregnancy was unsuccessful and the patient remained hypercalcaemic. Postpartum imaging assessment with technetium (^99mTc)-sestamibi scintigraphy could not supply conclusive diagnostic results. The use of ¹⁸F-fluorocholine (FCH) positron emission tomography (PET)/CT provided the accurate localisation of an ectopic parathyroid adenoma in the anterior mediastinum which was successfully resected by a thoracoscopic approach. In the second case, ^99mTc-sestamibi scintigraphy was inconclusive as well and FCH-PET/CT localised an ectopic parathyroid adenoma in the mediastinum and thus bilateral neck exploration could be spared. Both patients had surgical cure of their disease.

Primary hyperparathyroidism

In this Review, we describe the pathogenesis, diagnosis and management of primary hyperparathyroidism (PHPT), with a focus on recent advances in the field. PHPT is a common endocrine disorder that is characterized by hypercalcaemia and elevated or inappropriately normal serum levels of parathyroid hormone. Most often, the presentation of PHPT is asymptomatic in regions of the world where serum levels of calcium are routinely measured. In addition to mild hypercalcaemia, PHPT can manifest with osteoporosis and hypercalciuria as well as with vertebral fractures and nephrolithiasis, both of which can be asymptomatic. Other clinical forms of PHPT, such as classical disease and normocalcaemic PHPT, are less common. Parathyroidectomy, the only curative treatment for PHPT, is recommended in patients with symptoms and those with asymptomatic disease who are at risk of progression or have subclinical evidence of end-organ sequelae. Parathyroidectomy results in an increase in BMD and a reduction in nephrolithiasis. Various medical therapies can increase BMD or reduce serum levels of calcium, but no single drug can do both. More data are needed regarding the neuropsychological manifestations of PHPT and the pathogenetic mechanisms leading to sporadic PHPT, as well as on risk factors for complications of the disorder. Future work that advances our knowledge in these areas will improve the management of the disorder.