Fluorocholine PET Imaging of Parathyroid Disease

Odd Sites of Parathyroid Adenomas: 18F-fluorocholine PET/CT Pointing to the Right Place

Primary hyperparathyroidism is mostly caused by parathyroid adenoma(s) which are generally localized using routine imaging modalities such as neck ultrasonography and 99mTc-SestaMIBI scintigraphy. However, these can miss ectopic parathyroid adenomas due to their limited sensitivities. These ectopic lesions can later lead to failure of surgical excision and necessitate the need for a re-exploration. 18F-fluorocholine (FCH) positron emission tomography/computed tomography (PET/CT) can help in the localization of these ectopic adenomas due to its superior detection rates and spatial resolution. Herein, we report a case of ectopic parathyroid adenomas that were localized on FCH PET/CT.

Brown Tumour in Chronic Kidney Disease: Revisiting an Old Disease with a New Perspective

Osteitis fibrosa cystica (OFC) and Brown Tumours are two related but distinct types of bone lesions that result from the overactivity of osteoclasts and are most often associated with chronic kidney disease (CKD). Despite their potential consequences, these conditions are poorly understood because of their rare prevalence and variability in their clinical manifestation. Canonically, OFC and Brown Tumours are caused by secondary hyperparathyroidism in CKD. Recent literature showed that multiple factors, such as hyperactivation of the renin-angiotensin-aldosterone system and chronic inflammation, may also contribute to the occurrence of these diseases through osteoclast activation. Moreover, hotspot KRAS mutations were identified in these lesions, placing them in the spectrum of RAS-MAPK-driven neoplasms, which were until recently thought to be reactive lesions. Some risk factors contributed to the occurrence of OFC and Brown Tumours, such as age, gender, comorbidities, and certain medications. The diagnosis of OFC and Brown Tumours includes clinical symptoms involving chronic bone pain and laboratory findings of hyperparathyroidism. In radiological imaging, the X-ray and Computed tomography (CT) scan could show lytic or multi-lobular cystic alterations. Histologically, both lesions are characterized by clustered osteoclasts in a fibrotic hemorrhagic background. Based on the latest understanding of the mechanism of OFC, this review elaborates on the manifestation, diagnosis, and available therapies that can be leveraged to prevent the occurrence of OFC and Brown Tumours.

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.

Analysis of the successful clinical treatment of 140 patients with parathyroid adenoma: A retrospective study

BACKGROUND

Parathyroid adenoma (PA) sometimes recurs after surgery, how to improve the surgical success rate of PA is the key to the treatment of this disease.

AIM

To investigate the clinical features, diagnosis, and surgical treatment of patients with PA.

METHODS

Patients who were pathologically confirmed with PA and had undergone surgery for the first time between January 2010 and December 2017 at the Beijing Shijitan Hospital affiliated to Capital Medical University were included in the study. The clinical features, localization diagnosis, and surgical treatment of these patients were analyzed.

RESULTS

Of the 140 patients, 32 were male and 108 were female; 132 cases had one adenoma, and 8 had two adenomas. In addition, 114 cases had clinical symptoms, among which 51, 28, 23, 8, and 4 had urinary system, skeletal system, digestive system, neuromuscular system, and neuropsychiatric symptoms, respectively, while 26 cases had no obvious symptoms. The median level of preoperative parathyroid hormone (PTH) was 201.0 pg/mL. The positive detection rate of technetium-99m sestamibi (Tc-99m MIBI) single-photon emission computed tomography/computed tomography (SPECT/CT), ultrasound examination, and the combined use of Tc-99m MIBI SPECT/CT and ultrasound examination was 92.9%, 85.5%, and 96.4%, respectively. Open surgery was performed in all patients, and PTH was monitored during surgery. The success rate of surgery was 98.6%. After surgery, 21 cases developed hypocalcemia, 1 case developed temporary hoarseness, and 19 cases had transient hypoparathyroidism but there was no permanent hypoparathyroidism, postoperative hemorrhage, or hematoma in the surgical area.

CONCLUSION

For patients with clinically unexplained skeletal system, urinary system, and neuropsychiatric symptoms, the possibility of PA should be considered. Imaging examinations such as ultrasound and Tc-99m MIBI SPECT/CT could be integrated before surgery to obtain accurate localization diagnosis. Precise preoperative localization, intraoperative PTH monitoring, and delicate surgery to protect the integrity of the PA capsule ensure a minimally invasive and successful 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.

Preoperative Imaging with [18F]-Fluorocholine PET/CT in Primary Hyperparathyroidism

Primary hyperparathyroidism (pHPT) is a common endocrine disorder due to hyperfunctioning parathyroid glands. To date, the only curing therapy is surgical removal of the dysfunctional gland, making correct detection and localization crucial in order to perform a minimally invasive parathyroidectomy. ¹⁸F-Fluorocholine positron emission tomography/computed tomography (¹⁸F-FCH PET/CT) has shown promising results for the detection of pHPT, suggesting superiority over conventional imaging with ultrasounds or scintigraphy. A total of 33 patients with pHPT who had negative or equivocal findings in conventional imaging received ¹⁸F-FCH PET/CT preoperatively and were retrospectively included. A pathological hyperfunctional parathyroid gland was diagnosed in 24 cases (positive PET, 72.7%), 4 cases showed equivocal choline uptake (equivocal PET, 12.1%), and in 5 cases, no enhanced choline uptake was evident (negative PET, 15.2%). Twelve of the twenty-four detected adenoma patients underwent surgery, and in all cases, a pathological parathyroid adenoma was resected at the site detected by PET/CT. Two of the six patients without pathological choline uptake who received a parathyroidectomy revealed no evidence of parathyroid adenoma tissue in the histopathological evaluation. This retrospective study analyzes ¹⁸F-FCH PET/CT in a challenging patient cohort with pHPT and negative or equivocal conventional imaging results and supports the use of ¹⁸F-FCH for the diagnosis of hyperfunctional parathyroid tissue, especially in this patient setting, with a 100% true positive and true negative detection rate. Our study further demonstrates the importance of ¹⁸F-FCH PET/CT for successful surgical guidance.

Quantitative analysis in parathyroid adenoma scintigraphy

OBJECTIVE

Surgery is the only curative treatment for primary hyperparathyroidism. Parathyroid scintigraphy is one method used to preoperatively localize the lesion. We examined time-related changes in radiopharmaceutical uptake in parathyroid adenomas (PTAs) and thyroid gland by quantitative single-photon-emission computed tomography (SPECT) imaging to assess differences between rapid and delayed washout patterns.

PATIENTS AND METHODS

The study group consisted of 35 histologically verified PTAs after radio-guided surgery extirpation in 33 patients with primary hyperparathyroidism. Patients underwent a three-phase SPECT/CT study of the neck and upper thorax post 99mTc-methoxyisobutylisonitrile (MIBI) injection. Images were reconstructed using a proprietary ordered-subset-conjugate-gradient-maximization algorithm (Siemens xSPECT Quant). PTAs were divided into those with a rapid (group A) and those with a slow (group B) washout pattern. SUVmax values of PTAs and thyroid gland tissue at 10, 90 and 180 min post 99mTc-MIBI injection were recorded and statistically assessed. Retention indexes related to the early examination were calculated for PTA and thyroid gland (RI-PTA and RI-TG).

RESULTS

There were 11 PTAs in group A and 24 in group B. Significant between-group differences in PTA SUVmax and PTA/thyroid gland ratios were observed only at 180 min postinjection (P = 0.0297, P = 0.0222, respectively). RI-PTAs differed significantly at 90 and 180 min postinjection (P = 0.0298, P = 0.0431). No differences in PTA volumes, thyroid gland SUVmax values or RI-TG were observed between the groups.

CONCLUSION

PTAs with rapid and slow washout patterns have different characteristics on quantitative analysis in later phases. No significant differences in directly measurable quantitative values (SUVmax, PTA/thyroid gland ratio) at the early stages of multi-phase examination were observed.

Questionable value of [99mTc]-sestamibi scintigraphy in patients with pHPT and negative ultrasound

PURPOSE

A successful focused surgical approach in primary hyperparathyroidism (pHPT) relies on accurate preoperative localization of the parathyroid adenoma (PA). Most often, ultrasound is followed by [^99mTc]-sestamibi scintigraphy, but the value of this approach is disputed. Here, we evaluated the diagnostic approach in patients with surgically treated pHPT in our center with the aim to further refine preoperative diagnostic procedures.

METHODS

A single-center retrospective analysis of patients with pHPT from 01/2005 to 08/2021 was carried out followed by evaluation of the preoperative imaging modalities to localize PA. The localization of the PA had to be confirmed intraoperatively by the fresh frozen section and significant dropping of the intraoperative parathyroid hormone (PTH) levels.

RESULTS

From 658 patients diagnosed with pHPT, 30 patients were excluded from the analysis because of surgery for recurrent or persistent disease. Median age of patients was 58.0 (13-93) years and 71% were female. Neck ultrasound was carried out in 91.7% and localized a PA in 76.6%. In 23.4% (135/576) of the patients, preoperative neck ultrasound did not detect a PA. In this group, [^99mTc]-sestamibi correctly identified PA in only 25.4% of patients. In contrast, in the same cohort, the use of [¹¹C]-methionine or [¹¹C]-choline PET resulted in the correct identification of PA in 79.4% of patients (OR 13.23; 95% CI 5.24-33.56).

CONCLUSION

[¹¹C]-Methionine or [¹¹C]-choline PET/CT are superior second-line imaging methods to select patients for a focused surgical approach when previous ultrasound failed to identify PA.

Are Non-Coding RNAs Useful Biomarkers in Parathyroid Tumorigenesis?

Tumors of the parathyroid glands are common endocrine diseases almost always characterized by parathyroid hormone hypersecretion that determines the clinical manifestations of primary hyperparathyroidism, such as fatigue, kidney problems, weakness, brittle bones, and other symptoms. Most parathyroid neoplasia are benign adenomas, although rare malignant forms have been described. They are heterogeneous in terms of clinical presentation and the associated signs and symptoms overlap with those of disease and aging. Furthermore, most patients with hypercalcemia are discovered during routine blood tests for other reasons. Surgical removal is considered the main therapeutic option to cure these endocrine tumors and, therefore, innovative therapeutic approaches are actively required. Recently, a growing number of studies have suggested that alterations to the epigenetic mechanisms could play a pivotal role in parathyroid tumorigenesis. Most of the attention has been focused on non-coding RNAs (ncRNAs) (i.e., miRNAs, lncRNAs, and circRNAs) whose expression profile has been found to be deregulated in parathyroid tumors. The aim of the present paper is to give an insight into the ncRNAs involved in parathyroid tumorigenesis, which could be used in the future either as innovative diagnostic biomarkers or as therapeutic targets for the treatment of this endocrine neoplasia.

Hiperparatiroidismo primario por adenoma paratiroideo doble con glándulas paratiroides eutópica y ectópica

El hiperparatiroidismo primario (HPTP) es una afección producida por el exceso de secreción de hormona paratiroidea a partir de glándulas paratiroides que funcionan autárquicamente. Constituye la causa más común de hipercalcemia en la población. Por su embriología, las paratiroides son glándulas que pueden tener localizaciones ectópicas de forma frecuente. El HPTP se presenta en forma esporádica en el 90% de los casos, resultante en general de un adenoma único con expansiones monoclonales de una estirpe celular única. Menos frecuentemente (2-15%), se asocia con un segundo adenoma funcionante. La forma familiar (10%) se asocia a síndrome de neoplasias endócrinas múltiples (NEM) como NEM 1 y NEM 2A. Se presenta un caso de adenoma paratiroideo doble, con el segundo adenoma paratiroideo localizado en el mediastino, describiéndose los estudios preoperatorios y de localización glandular, así como los hallazgos operatorios.

[18F]fluoro-ethylcholine-PET Plus 4D-CT (FEC-PET-CT): A Break-Through Tool to Localize the "Negative" Parathyroid Adenoma. One Year Follow Up Results Involving 170 Patients

Background: The diagnostic performance of [¹⁸F]fluoro-ethylcholine-PET-CT&4D-CT (FEC-PET&4D-CT) to identify parathyroid adenomas (PA) was analyzed when ultrasound (US) or MIBI-Scan (MS) failed to localize. Postsurgical one year follow-up data are presented. Methods: Patients in whom US and MS delivered either incongruent or entirely negative findings were subjected to FEC-PET&4D-CT and cases from July 2017 to June 2020 were analyzed, retrospectively. Cervical exploration with intraoperative PTH-monitoring (IO-PTH) was performed. Imaging results were correlated to intraoperative findings, and short term and one year postoperative follow-up data. Results: From July 2017 to June 2020 in 171 FEC-PET&4D-CTs 159 (92.9%) PAs were suggested. 147 patients already had surgery, FEC-PET&4D-CT accurately localized in 141; false neg. 4, false pos. 2, global sensitivity 0.97; accuracy 0.96, PPV 0.99. All of the 117 patients that already have completed their 12-month postoperative follow up had normal biochemical parameter, i.e., no signs of persisting disease. However, two cases may have a potential for recurrent disease, for a cure rate of at least 98.3%. Conclusion: FEC-PET&4D-CT shows unprecedented results regarding the accuracy localizing PAs. The one-year-follow-up data demonstrate a high cure rate. We, therefore, suggest FEC-PET-CT as the relevant diagnostic tool for the localization of PAs when US fails to localize PA, especially after previous surgery to the neck.

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.

Surgical options in treating patients with primary hyperparathyroidism

Background

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

Conclusions

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

The role of 18F-FCH PET/CT in patients with uremic hyperparathyroidism compared with 99mTc-sestaMIBI SPECT/CT and ultrasonography

BACKGROUND

The aim of this study was to evaluate the diagnostic efficacy of ¹⁸F-fluorocholine (¹⁸F-FCH) PET/CT for uremic hyperparathyroidism (uHPT) compared to ^99mTc-sestaMIBI SPECT/CT and ultrasonography (US).

METHODS

A total of 17 uHPT patients with stage 5 chronic kidney disease (CKD) were prospectively enrolled. All patients underwent US, ^99mTc-sestaMIBI SPECT/CT, and ¹⁸F-FCH within 2 months and received surgical treatment. Visual and quantitative methods were used for image analyses. Intraoperative localization and postoperative histological results of the reference standard as well as the sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) of the three modalities were analyzed using Pearson's χ² tests. In addition, the diagnostic efficacy of ¹⁸F-FCH PET/CT for uHPT was evaluated. The relationships between PET parameters and laboratory parameters were assessed using the Spearman correlation coefficient.

RESULTS

A total of 63 parathyroid hyperplasia lesions were resected in 17 uHPT patients, and 53 lesions were detected using ¹⁸F-FCH PET/CT with no false-positive results. The sensitivity, specificity, accuracy, PPV, and NPV were 84.13%, 100%, 86.49%, 100%, and 52.38%, respectively. In comparison, the corresponding values for ^99mTc-sestaMIBI SPECT/CT and US were 63.49%, 90.91%, 67.57%, 97.56%, and 30.30% and 61.90%, 81.82%, 64.86%, 95.12%, and 27.27%, respectively. The volume of hyper-functioning parathyroid glands was significantly different between lesions positive in ¹⁸F-FCH PET/CT and negative in ¹⁸F-FCH PET/CT (mean volume 1.36 ± 0.55 cm³ vs. 0.83 ± 0.26 cm³; P = 0.019). US misidentified intrathyroidal parathyroid hyperplasia as thyroid nodules in three patients, while ¹⁸F-FCH PET correctly identified the anatomy. No significant associations were observed between PET parameters and laboratory parameters in uHPT.

CONCLUSION

¹⁸F-FCH PET/CT was more sensitive and accurate for uHPT than ^99mTc-sestaMIBI SPECT/CT and US, and had better preoperative diagnostic efficacy, particularly for lesions diagnosed as a thyroid nodule by US.