18F-Fluorocholine PET and Multiphase CT Integrated in Dual Modality PET/4D-CT for Preoperative Evaluation of Primary Hyperparathyroidism

Incidental Detection of Parathyroid Adenoma on 18F-PSMA PET/CT

ABSTRACT

A 70-year-old man, diagnosed with prostate cancer, was referred to the Department of Nuclear Medicine for tumor staging with prostate-specific membrane antigen (PSMA) PET/CT. High PSMA uptake was observed in the prostate without PSMA-avid lymph nodes or distant metastases. Coincidentally, a PSMA-avid nodule was observed dorsal to the right thyroid lobe. A complementary 4-dimensional CT showed a round nodule of 18 mm with quick contrast enhancement well demarcated from its surroundings. Blood tests revealed elevated serum calcium and parathyroid hormone consistent with primary hyperparathyroidism. Subsequently, parathyroidectomy was performed, and histopathological examination of the nodule confirmed a parathyroid adenoma.

18F-Fluorocholine PET/CT Compared with Current Imaging Procedures for Preoperative Localization of Hyperfunctioning Parathyroids in Patients with Chronic Kidney Disease

Hyperparathyroidism (HPT) in patients with chronic kidney disease (CKD) includes secondary (sHPT) and tertiary hyperparathyroidism (tHPT). Considering that the role of preoperative imaging in the clinical setting is controversial, in the present study we have retrospectively compared pre-surgical diagnostic performances of ¹⁸F-Fluorocholine (¹⁸F-FCH) PET/CT, cervical ultrasonography (US), parathyroid scintigraphy, and 4D-CT in a group of 30 patients with CKD and HPT (18/12 sHPT/tHPT), 21 CKD G5 including 18 in dialysis, and 9 kidney transplant recipients. All patients underwent ¹⁸F-FCH, and 22 had cervical US, 12 had parathyroid scintigraphy, and 11 had 4D-CT. Histopathology was the gold standard. Seventy-four parathyroids were removed: 65 hyperplasia, 6 adenomas, and 3 normal glands. In the whole population, in a per gland analysis, ¹⁸F-FCH PET/CT was significantly more sensitive and accurate (72%, 71%) than neck US (25%, 43%), parathyroid scintigraphy (35%, 47%), and 4D-CT (40%, 47%). The specificity of ¹⁸F-FCH PET/CT (69%) was lower than that of neck US (95%) and parathyroid scintigraphy (90%), without, however, achieving significance. ¹⁸F-FCH PET/CT was more accurate than all other diagnostic techniques when sHPT and tHPT patients were considered separately. ¹⁸F-FCH PET/CT sensitivity was significantly higher in tHPT (88%) than in sHPT (66%). Three ectopic hyperfunctioning glands (in three different patients) were all detected by ¹⁸F-FCH PET/CT, two by parathyroid scintigraphy, and none by cervical US and 4D-CT. Our study confirms that ¹⁸F-FCH PET/CT is an effective preoperative imaging option in patients with CKD and HPT. These findings may be of greater importance in patients with tHPT (who could benefit from minimally invasive parathyroidectomy) than in patients with sHPT, who often undergo bilateral cervicotomy. In these cases, preoperative ¹⁸F-FCH PET/CT may be helpful in locating ectopic glands and may guide the surgical choice for gland preservation.

Hyperfunctioning Intrathyroidal Parathyroid: a Misleading Preoperative Diagnosis

Hyperfunctioning parathyroid glands may be rarely located in the thyroidal parenchyma and not identified by imaging or during surgical procedures. We present three patients with primary hyperparathyroidism related to hyperfunctioning intrathyroidal parathyroid retrospectively selected among 732 cases from own Institutional parathyroid PET/CT registry from 2018 to 2022. Intrathyroidal parathyroids showed intense 18F-fluorocholine uptake but a variable echographic pattern, inconstant 99mTc-MIBI uptake, and atypic iodine-contrast enhancement. Although rare, the possibility of an intrathyroidal parathyroid should be considered when no hyperfunctioning gland is found on preoperative imaging and thorough bilateral neck exploration.

Comparison of 4D computed tomography and F-18 fluorocholine PET for localisation of parathyroid lesions in primary hyperparathyroidism: A systematic review and meta-analysis

Minimally invasive parathyroidectomy (MIP) is the standard of care for primary hyperparathyroidism (PHPT). Four dimensional computed tomography(4DCT) and F-18 Fluorocholine positron emission tomography/computed tomography (FCH PET/CT) localize adenomas accurately to perform MIP. We aimed to conduct a systematic review and metanalysis to evaluate the diagnostic performance of 4DCT and FCH PET/CT scan for quadrant wise localisation in PHPT patients and to do head-to-head comparison between these two modalities. DESIGN, PATIENTS AND MEASUREMENT : After searching through PubMed and EMBASE databases, 46 studies (using histology as a gold standard) of 4DCT and FCH PET/CT were included. RESULTS: Total number of patients included were 1651 and 952 for 4DCT scan (studies n = 26) and FCH PET/CT scan (studies n = 24) respectively. In per patient analysis, FCH PET/CT and 4DCT had pooled sensitivities of 92% (88-94) and 85% (73-92) respectively and in per lesion analysis, 90% (86-93) and 79% (71-84), respectively. In the subgroup with negative conventional imaging/persistent PHPT, FCH PET/CT had comparable sensitivity to 4DCT (84% [74-90] vs. 72% [46-88]). As per patient wise analysis, FCH PET/CT had better detection rates than 4DCT ([92.4 vs. 76.85], odds ratio -3.89 [1.6-9.36] p = .0024) in the subpopulation where both FCH PET/CT and 4DCT were reported. CONCLUSION: Both 4DCT and FCH PET/CT scan performed well in newly diagnosed patients, patients with persistent disease and in those with inconclusive conventional imaging results. FCH PET/CT scan had a higher pooled sensitivity than 4DCT in detecting patients with PHPT in head to head comparison.

Does 18F-Fluorocholine PET/CT add value to positive parathyroid scintigraphy in the presurgical assessment of primary hyperparathyroidism?

Introduction

To investigate the value of presurgical ¹⁸F-FCH PET/CT in detecting additional hyperfunctioning parathyroids despite a positive ^99mTc-sestamibi parathyroid scintigraphy in patients with primary hyperparathyroidism (pHPT).

Methods

This is a retrospective study involving patients with pHPT, positive parathyroid scintigraphy performed before ¹⁸F-FCH PET/CT, and parathyroid surgery achieved after PET/CT. Imaging procedures were performed according to the EANM practice guidelines. Images were qualitatively interpreted as positive or negative. The number of pathological findings, their topography, and ectopic location were recorded. Histopathology, Miami criterion, and biological follow-up were considered to ensure effective parathyroidectomy confirming the complete excision of all hyperfunctioning glands. The impact of ¹⁸F-FCH PET/CT on therapeutic strategy was recorded.

Results

64/632 scanned pHPT patients (10%) were included in the analysis. According to a per lesion-based analysis, sensitivity, specificity, positive predictive value, and negative predictive value of ^99mTc-sestamibi scintigraphy were 82, 95, 87, and 93%, respectively. The same values for ¹⁸F-FCH PET/CT were 93, 99, 99, and 97%, respectively. ¹⁸F-FCH PET/CT showed a significantly higher global accuracy than ^99mTc-sestamibi scintigraphy: 98% (CI: 95-99) vs. 91% (CI: 87-94%). Youden Index was 0.79 and 0.92 for ^99mTc-sestamibi scintigraphy and ¹⁸F-FCH PET/CT, respectively. Scintigraphy and PET/CT were discordant in 13/64 (20%) patients (49 glands). ¹⁸F-FCH PET/CT identified nine pathologic parathyroids not detected by ^99mTc-sestamibi scintigraphy in 8 patients (12.5%). Moreover, ¹⁸F-FCH PET/CT allowed the reconsideration of false-positive scintigraphic diagnosis (scinti+/PET-) for 8 parathyroids in 7 patients (11%). The ¹⁸F-FCH PET/CT influenced the surgical strategy in 7 cases (11% of the study population).

Conclusion

In a preoperative setting, ¹⁸F-FCH PET/CT seems more accurate and useful than ^99mTc-sestamibi scan in pHPT patients with positive scintigraphic results. Positive parathyroid scintigraphy could be not satisfactory before neck surgery particularly in patients with multiglandular disease, suggesting a need to evolve the practice and define new preoperative imaging algorithms including ¹⁸F-FCH PET/CT at the fore-front in pHPT patients.

Preoperative imaging in primary hyperparathyroidism: Are 11 C-Choline PET/CT and 99m Tc-MIBI/123 Iodide subtraction SPECT/CT interchangeable or do they supplement each other?

OBJECTIVE

Preoperative location of hyperfunctioning parathyroid glands (HPGs) is vital when planning minimally invasive surgery in patients with primary hyperparathyroidism (PHPT). Dual-isotope subtraction scintigraphy with ^99m Tc-MIBI/¹²³ Iodide using SPECT/CT and planar pinhole imaging (Di-SPECT) has shown high sensitivity, but is challenged by high radiation dose, time consumption and cost. ¹¹ C-Choline PET/CT (faster with a lower radiation dose) is non-inferior to Di-SPECT. We aim to clarify to what extent the two are interchangeable and how often there are discrepancies.

DESIGN

This is a prospective, GCP-controlled cohort study.

PATIENTS AND MEASUREMENTS

One hundred patients diagnosed with PHPT were included and underwent both imaging modalities before parathyroidectomy. Clinical implications of differences between imaging findings and negative imaging results were assessed. Surgical findings confirmed by biochemistry and pathology served as reference standard.

RESULTS

Among the 90 patients cured by parathyroidectomy, sensitivity was 82% (95% confidence interval [CI]: 74%-88%) and 87% (95% CI: 79%-92%) for Choline PET and Di-SPECT, respectively, p = .88. In seven cases at least one imaging modality found no HPG. Of these, neither modality found any true HPGs and only two were cured by surgery. When a positive finding in one modality was incorrect, the alternative modality was correct in approximately half of the cases.

CONCLUSION

Choline PET and Di-SPECT performed equally well and are both appropriate as first-line imaging modalities for preoperative imaging of PHPT. When the first-line modality fails to locate an HPG, additional preoperative imaging with the alternate modality offers no benefit. However, if parathyroidectomy is unsuccessful, additional imaging with the alternate modality has merit before repeat surgery.

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.

Contemporary Multimodality Imaging of Primary Hyperparathyroidism

Primary hyperparathyroidism (PHPT) is a disorder characterized by hypercalcemia and an elevated or inappropriately normal parathyroid hormone level. Classic features include bone pain, fractures, renal impairment, nephrolithiasis, and mental disturbance. However, most cases of PHPT are now asymptomatic at diagnosis or associated with nonspecific neurocognitive changes. The most frequent cause of PHPT is a solitary adenoma that secretes parathyroid hormone without the normal suppressive effect of serum calcium. A smaller number of cases can be attributed to multigland disease. Parathyroidectomy is curative and is considered for nearly all affected patients. Although PHPT is primarily a clinical and biochemical diagnosis, imaging is key to the localization of adenomas, which can lie in conventional locations adjacent to the thyroid gland or less commonly at ectopic sites in the neck and mediastinum. In addition, accurate localization facilitates the use of a minimally invasive or targeted surgical approach. Frequently used localization techniques include US, parathyroid scintigraphy, and four-dimensional CT. Second- and third-line modalities such as MRI, PET/CT, and selective venous sampling with or without parathyroid arteriography can increase confidence before surgery. These localization techniques, along with the associated technical aspects, relative advantages, and drawbacks, are described. Local expertise, patient factors, and surgeon preference are important considerations when determining the type and sequence of investigation. A multimodality approach is ultimately desirable, particularly in challenging scenarios such as multigland disease, localization of ectopic adenomas, and persistent or recurrent PHPT. Online supplemental material is available for this article. ^©RSNA, 2022.

Advanced Computed Tomographic Localization Techniques for Primary Hyperparathyroidism: A Systematic Review and Meta-analysis

Importance

Emerging computed tomographic (CT) imaging techniques for the localization of primary hyperparathyroidism (PHPT) may be superior to the current imaging standard, thus necessitating a critical review and pooling of available evidence.

Objective

Primary hyperparathyroidism requires accurate imaging to guide definitive surgical management. Advanced techniques including 4-dimensional computed tomographic (4D-CT) scan have been investigated over the past decade. We sought to evaluate the efficacy of these emerging imaging techniques through pooled analysis of the existing evidence.

Data Sources

PubMed, Embase, and Web of Science databases were queried for original English articles without any restrictions on date.

Study Selection

We included comparative observational studies but excluded animal studies, case reports, and case series. Overall, 353 abstracts were screened independently by 2 investigators along with a third reviewer to resolve conflicts. A total of 26 full-text articles were included in this review.

Data Extraction and Synthesis

This review was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guidelines. Data was independently extracted by 2 investigators and subsequently pooled into a meta-analysis using a random-effects model.

Main Outcomes and Measures

Measures of imaging diagnostic performance such as sensitivity, specificity, positive predictive value, and negative predictive value were the primary outcomes of interest.

Results

Overall, of 34 articles screened, 26 met criteria for qualitative synthesis, and 23 of these were appropriate for meta-analysis. Of the 26 studies included, there were 5845 patients, of which 4176 were women (79.2%). The average of mean ages reported in 23 studies was 60.9 years. Meta-analysis in all patients with PHPT revealed pooled sensitivity that was greater with 4D-CT (81%; 95% CI, 77%-84%; I2 = 88%) compared with the current first-line modality of sestamibi-single-photon emission CT (SPECT/CT) (65%; 95% CI, 59%-70%; I2 = 93%). For patients with recurrent PHPT requiring reoperation, 4D-CT pooled sensitivity was 81% (95% CI, 64%-98%; I2 = 93%) in contrast to 53% (95% CI, 35%-71%; I2 = 81%) for sestamibi-SPECT/CT. The overall quality of the 26 studies was moderate with a median (range) Methodological Index for Nonrandomized Studies score for all included studies of 15.5 (13-19).

Conclusions and Relevance

The findings of this systematic review and with meta-analyses of numerous studies from the past decade suggest that the 4D-CT can be more sensitive and specific than sestamibi-SPECT/CT in localizing PHPT. More research is needed to determine the clinical significance of this improvement in localization.

Management and Long-Term Follow-Up of Hyperparathyroidism in Multiple Endocrine Neoplasia Type 1: Single Center Experience

Background: Primary hyperparathyroidism (PHPT) in the most common and earliest manifestation of multiple endocrine neoplasia type-1 (MEN1). Epidemiological data have been reported in MEN1 patients but data on long-term follow-up focusing on PHPT are scarce. Methods: In this retrospective cohort study, we included patients diagnosed with MEN1-related PHPT that were under regular follow-up in our institution. Results: Data on 68 patients (39 males), with a mean age at MEN1-diagnosis of 39 ± 13.06 years, were analyzed. Pancreatic neuroendocrine tumors were encountered in 82% (71% nonsecreting) followed by pituitary adenomas in 66% (49% nonsecreting). Mean age at PHPT diagnosis was 35.2 ± 4.0 years. Parathyroidectomy was performed in 57 patients (82.3%), of whom 56% achieved long-term remission, while 12.2% and 31.5% had persistent and recurrent disease, respectively (median follow-up of 4 years; range 1–21 years). Cinacalcet restored serum calcium levels in 33.8%, both as first and as a second line treatment. Permanent hypoparathyroidism occurred in 19.2%. MEN1 pathogenic variants were identified in 77.2% of the tested individuals, but no genotype-phenotype associations were reported. Conclusions: MEN1-related PHPT involves a multiglandular disease and its management remains a therapeutic challenge, as recurrent disease can develop even after 20 years of follow-up. Prolonged follow-up of these patients at referral centers is critical for their optimal management.

18F-Fluorocholine PET and 4D-CT in Patients with Persistent and Recurrent Primary Hyperparathyroidism

Patients with primary hyperparathyroidism (pHPT) can develop persistent (P-pHPT) or recurrent (R-pHPT) disease after parathyroidectomy. Before recommending reoperation, recurrence must be accurately identified because of the high risk of complications. Our study evaluates ¹⁸F-fluorocholine (¹⁸F-FCH) PET/CT and 4D-CT integrated in PET/4D-CT in patients with P-pHPT/R-pHPT. Patients with P-pHPT/R-pHPT investigated by ¹⁸F-FCH PET/4D-CT between May 2018 and March 2021 were retrospectively included. Forty-two patients were included, 37 of whom underwent 4D-CT. The sensitivity and detection rate (DR%) were 95% and 88% for ¹⁸F-FCH PET/CT and 70% and 63% for 4D-CT, respectively. PET/CT and 4D-CT were concordant in 18/24 glands and concordant and positive in 15/24 (63%) glands. Discordant results were obtained for 6/24 glands. The surgical success rate was 65%. PET/CT showed significantly higher sensitivity than 4D-CT. Dynamic CT allowed the identification of no additional glands missed by PET/CT, and the combination of the 2 techniques did not improve the sensitivity or DR%. ¹⁸F-FCH PET/CT appears to be a valuable technique to accurately detect hyperfunctioning parathyroid tissue in patients with P-pHPT/R-pHPT and is better than 4D-CT. Except for cases with doubtful locations of PET targets that may require 4D-CT for surgical guidance, standard nonenhanced ¹⁸F-FCH PET/CT can be effectively recommended in patients with P-pHPT/R-pHPT before reoperation.

A Collision Intrathyroidal Tumor Causing Primary Hyperparathyroidism: Evidence From an 18F-Choline PET/CT Study

ABSTRACT

A 67-year-old man was diagnosed with primary hyperparathyroidism and normofunctioning left nodular goiter. Fine-needle aspiration cytology showed thyroid (Thy) 4 (suspicious of malignancy). After first-line imaging proved negative, integrated 18F-choline PET/4D contrast-enhanced CT revealed uptake by the thyroid nodule and by 3 nodules of the left central compartment. Thyroidectomy and lymphadenectomy were performed. Histopathology revealed a collision tumor (ie, 2 histologically distinct tumors occurring at the same anatomic site) composed of both PTC (papillary thyroid carcinoma) and parathyroid carcinoma within the left thyroid nodule. Lymph nodes showed PTC metastases. Primary hyperparathyroidism and calcium levels normalized, and the patient underwent radioiodine therapy.

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.

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.

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.

Diagnostic Role of Four-Dimensional Computed Tomography for Preoperative Parathyroid Localization in Patients with Primary Hyperparathyroidism: A Systematic Review and Meta-Analysis

We sought to systematically evaluate diagnostic performance of four-dimensional computed tomography (4D-CT) in the localization of hyperfunctioning parathyroid glands (HPGs) in patients with primary hyperparathyroidism (pHPT). We calculated the pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratios (DOR) of 4D-CT on a per-lesion level, as well as pooled sensitivity and positive predictive value (PPV) on a per-patient level with 95% confidence intervals (CIs). Additionally, we plotted summary receiver operating characteristic (SROC) curves and evaluated the areas under the curves (AUC). A total of 16 studies were included in the analysis. Their pooled sensitivity, specificity, PLR, NLR, and DOR of 4D-CT on per-lesion level were 75% (95%CI: 66–82%), 85% (95%CI: 50–97%), 4.9 (95%CI: 1.1–21.3), 0.30 (95%CI: 0.19–0.45), and 17 (95%CI: 3–100), respectively, with an AUC of 81% (95%CI: 77–84%). We also observed heterogeneity in sensitivity (I² = 79%) and specificity (I² = 94.7%), and obtained a pooled sensitivity of 81% (95%CI: 70–90%) with heterogeneity of 81.9% (p < 0.001) and PPV of 91% (95%CI: 82–98%) with heterogeneity of 80.8% (p < 0.001), based on a per-patient level. Overall, 4D-CT showed moderate sensitivity and specificity for preoperative localization of HPG(s) in patients with pHPT. The diagnostic performance may improve with 4D-CT’s promotion to first-line use on a lesion-based level, further research is needed to confirm the results.

Preoperative Localization for Primary Hyperparathyroidism: A Clinical Review

With increasing use of minimally invasive parathyroidectomy (PTx) over traditional bilateral neck exploration in patients with primary hyperparathyroidism (PHPT), accurate preoperative localization has become more important to enable a successful surgical outcome. Traditional imaging techniques such as ultrasound (US) and sestamibi scintigraphy (MIBI) and newer techniques such as parathyroid four-dimension computed tomography (4D-CT), positron emission tomography (PET), and magnetic resonance imaging (MRI) are available for the clinician to detect the diseased gland(s) in the preoperative workup. Invasive parathyroid venous sampling may be useful in certain circumstances such as persistent or recurrent PHPT. We review the diagnostic performance of these imaging modalities in preoperative localization and discuss the advantages and weaknesses of these techniques. US and MIBI are established techniques commonly utilized as first-line modalities. 4D-CT has excellent diagnostic performance and is increasingly performed in first-line setting and as an adjunct to US and MIBI. PET and MRI are emerging adjunct modalities when localization has been equivocal or failed. Since no evidence-based guidelines are yet available for the optimal imaging strategy, clinicians should be familiar with the range and advancement of these techniques. Choice of imaging modality should be individualized to the patient with consideration for efficacy, expertise, and availability of such techniques in clinical practice.

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.

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.