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.

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

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

18F-Fluorocholine PET/CT, Tc-99m-MIBI and TC-99m-MDP SPECT/CT in Tertiary Hyperparathyroidism with Renal Osteodystrophy

Tertiary hyperparathyroidism (HPT) is a metabolic disorder characterized by the semi-autonomous hypersecretion of parathyroid hormone (PTH), leading to hypercalcemia. It can be the end result of persistent secondary hyperparathyroidism and is most commonly observed in patients with long-standing chronic kidney disease (CKD) and often after renal transplantation. Untreated HPT can lead to progressive bone disease, fibrocystic osteitis, and soft-tissue calcifications, along with other severe complications. In the 2009 Kidney Disease Improving Global Outcomes (KDIGO) guidelines, CKD-Mineral and Bone Disorder (CKD-MBD) is used to describe the broader clinical syndrome encompassing mineral, bone, and calcific cardiovascular abnormalities that develop as a complication of CKD. We report a 62-year-old female with a severe HPT evolved from advanced chronic kidney disease (stage 5D, KDIGO). Patient was evaluated with multimodality nuclear medicine functional imaging to assess hyperfunctioning parathyroid glands and bone lesions. Tc-99m-methoxyisobutylisonitrile (MIBI) dual-phase scintigraphy, Tc-99m-methylenediphosphonate (MDP) bone scan and ¹⁸F-Fluorocholine positron emission tomography/computed tomography (¹⁸F-FCH PET/CT) were performed before surgery.

Dural Metastases of Advanced Prostate Cancer Detected by 18F-Fluorocholine

Prostate cancer with extensive dural metastases is very rare, with only few cases described in the literature. We report one such case of a 74-year-old man with advanced prostate cancer, and in relatively good clinical condition. The patient returned with complaints of headache and diplopia. Fluorocholine (¹⁸F) chloride (¹⁸F-FCH) is an analog of choline in which a hydrogen atom has been replaced by fluorine (¹⁸F). After crossing the cell membrane by a carrier-mediated mechanism, choline is phosphorylated by choline kinase to produce phosphorylcholine. ¹⁸F-FCH positron emission tomography–computed tomography (PET/CT) is widely used to stage and restage patients affected by prostate cancer with good sensitivity. ¹⁸F-FCH PET/CT showed disease progression with the onset of multiple skull lesions. Numerous suspicious dural hypermetabolic lesions indicating neoplastic involvement were detected along the fronto-parietal convexities, in the left fronto-orbital region and right lateral wall of the orbit, concerning for metastases in these regions. A contrast-enhanced computed tomography (CECT) scan was performed which showed corresponding enhancing tissue which correlated with the PET findings. The final imaging diagnosis was osteo-dural metastases from prostate cancer associated with poor outcome. Awareness of this pattern of metastases may be of clinical relevance in order to avoid unnecessary invasive diagnostic procedures in groups of patients with a dismal prognosis.

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.

Triple Tracer Positivity in Metastatic Lymph Nodes from Well-Differentiated Neuroendocrine Tumor in MEN-1 Syndrome

Patients with multiple endocrine neoplasia type 1 usually have a combination of endocrine disorders due to lesions in the pancreas, parathyroid gland, and pituitary gland. Functional imaging using different tracers in addition to conventional imaging are applied in localizing the primary sites, determining the disease extent, and characterizing the lesions. We present a diagnosed case of multiple endocrine neoplasia type 1 with interesting incidental imaging findings showing ^99mTc-sestamibi and ¹⁸F-fluorocholine uptake in addition to ⁶⁸Ga-DOTANOC uptake in metastatic mediastinal and cervical lymph nodes arising from gastroenteropancreatic neuroendocrine tumor. This case shows the possibility of imaging the neuroendocrine tumors with 3 different tracers, namely ⁶⁸Ga-DOTANOC, ^99mTc-sestamibi, and ¹⁸F-fluorocholine.

Baseline and Post-treatment 18F-Fluorocholine PET/CT Predicts Outcomes in Hepatocellular Carcinoma Following Locoregional Therapy

BACKGROUND AND AIMS

¹⁸F-fluorocholine positron emission tomography/computed tomography (¹⁸F-FCH PET/CT) is an emerging functional imaging technique in the diagnosis and management of hepatocellular carcinoma (HCC). The aim of this study was to assess the ability of a pre- and post-treatment ¹⁸F-FCH PET/CT to predict prognosis and treatment response in early-stage HCC.

METHODS

Patients with early- or intermediate-stage HCC planned for locoregional therapy were prospectively enrolled. Baseline demographic and tumor information was collected and baseline and post-treatment ¹⁸F-FCH PET/CT performed. Maximum standardized uptake values (SUVmax) were determined for each HCC lesion, and the difference between baseline and post-treatment SUVmax values were compared with progression-free survival outcomes.

RESULTS

A total of 29 patients with 39 confirmed HCC lesions were enrolled from a single clinical center. Patients were mostly men (89.7%) with hepatitis C or alcohol-related cirrhosis (65.5%) and early-stage disease (89.7%). Per-patient and per-lesion sensitivity of ¹⁸F-FCH PET/CT was 72.4% and 59.0%, respectively. A baseline SUVmax < 13 was associated with a superior median progression-free survival compared with an SUVmax of > 13 (17.7 vs. 5.1 months; p = 0.006). A > 45% decrease in SUVmax between baseline and post-treatment ¹⁸F-FCH PET/CT ("responders") was associated with a superior mean progression-free survival than a percentage decrease of < 45% ("non-responders," 36.1 vs. 11.6 months; p = 0.034).

CONCLUSIONS

Baseline and post-treatment ¹⁸F-FCH PET/CT predicts outcomes in early-stage HCC undergoing locoregional therapy. This technique may identify patients with an objective response post-locoregional therapy who would benefit from further therapy.

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.

Usefulness of 18F-fluorocoline PET/CT in prostate cancer patients with biochemical recurrence: Influence of PSA kinetics and hormone therapy

PURPOSE

To evaluate the capacity of 18f-fluorocholine positron emission tomography/computed tomography (FCH PET/CT) to detect biochemical recurrence of prostate cancer and to determine the correlation with PSA kinetics and influence of antiandrogen hormone therapy.

PATIENTS AND METHODS

Observational and retrospective study, which included patients with prostate cancer and criteria for biochemical recurrence and/or resistance to castration, according to the European Association of Urology. FCH PET/CT results were classified as positive or negative, using as gold standard the pathology report, findings of other imaging test, and/or clinical follow-up results. The correlation between FCH PET/CT and PSA kinetics (PSA at the time of exploration [PSA-trigger], doubling time [PSAdt] and velocity [PSAva]) was studied and the influence of hormone therapy was analysed.

RESULTS

The study included 203 patients. The FCH PET/CT detection rate was 43.3%. The group of patients with FCH PET/CT positive showed more aggressive PSA kinetics (PSAdt: 7.5 months and PSAva 8.37±14.8ng/ml/a) than the FCH PET/CT negative group (PSAdt: 14.5±7.6 months and PSAva: 1.8±3.7ng/ml/a). The detection rate of FCH PET/CT in the subgroup with castration resistance was 89.1%, significantly higher than in the group with radical treatment at 29.9%, p<.001.

CONCLUSIONS

FCH PET/CT is useful to detect biochemical recurrence of prostate cancer, especially in patients who receive hormone therapy or more aggressive PSA kinetics.

Dual-Time-Point 18F-Fluorocholine PET/CT in Parathyroid Imaging

¹⁸F-fluorocholine (¹⁸F-FCH) PET/CT is a promising and increasingly used scan technique in the preoperative imaging of parathyroid adenoma. Several acquisition methods have been evaluated in the literature, but the optimal image acquisition time point after administration of the tracer is still under debate. Methods: Patients who had hyperparathyroidism, underwent dual-time-point ¹⁸F-FCH PET/CT (image acquisition, 5 min; 60 min after injection), and had histologically proven pathologic parathyroid glands were retrospectively included in the study. Early and late images were compared both visually and quantitatively. Results: Sixty-four patients were included, and a total of 71 parathyroid glands were surgically removed. Visually, there were no differences between early and late images of hyperfunctioning parathyroid glands in 44 patients (69%); in 13 patients (20%), visualization on early images was better; in 6 patients (9%), visualization of hyperfunctioning glands was best on late images; and in 1 patient (2%), the lesion was exclusively visualized on late images. For the total cohort, there was a significant decrease in ¹⁸F-FCH uptake in the glands on late versus early time points (P = 0.001), but there was a significant increase in the ratio of parathyroid uptake to thyroid uptake (P = 0.037). The group of patients with better visualization on early images showed a decrease over time in both parathyroid uptake and the ratio of parathyroid uptake to thyroid uptake, significant in comparison to those in both the group with better visualization at later time points and the group in which visualization was similar at both time points (P values of 0.000-0.018). There were no significant differences in ¹⁸F-FCH uptake and the ratio of parathyroid uptake to thyroid uptake between the latter 2 groups (P values of 0.200-0.709). Conclusion: In most patients (89%), hyperfunctioning parathyroid glands were adequately visualized on early imaging; however, in a subset of patients (11%), such glands were best visualized at later time points. Therefore, we recommend the acquisition of dual-time-point images in parathyroid imaging with ¹⁸F-FCH PET/CT or the creation of an opportunity to acquire additional late images after review of early images when findings are inconclusive.

Evaluation of recurrent parathyroid carcinoma: A new imaging tool in uncommon entity

Parathyroid carcinoma (PTC) is a rare endocrine tumor and uncommon cause for primary hyperparathyroidism. ¹⁸F-fluorocholine (FCH) positron emission tomography and computed tomography (PET/CT) has shown promising results in the detection of parathyroid adenoma, though its role in PTC is undefined due to the paucity of incidence. The authors in this case report discuss the possible complimentary role of FCH PET/CT with ¹⁸F-fluorodeoxyglucose PET/CT in the evaluation of the management of suspected recurrence, since this rare entity has high loco-regional and distant recurrence of the disease.

How we read FCH-PET/CT for prostate cancer

Over the last decade, ¹⁸F-fluorocholine positron emission tomography/computed tomography (FCH-PET/CT) has gained in popularity for the staging and restaging of patients with prostate cancer (PCa). However, despite abundant literature on the topic, there is a lack of publications on how to actually interpret FCH-PET/CT in a clinical setting. Here we propose a practical, TNM-oriented approach to read FCH-PET/CT, with notes on procedure technique, image display, review sequence and report structure. The purpose of this article is to provide guidance to radiologists, nuclear medicine physicians and residents who are new to FCH-PET/CT, as well as to propose an alternate approach to more experienced physicians.

Impact of fasting on (18)F-fluorocholine gastrointestinal uptake and detection of lymph node metastases in patients with prostate cancer

Background

¹⁸F-fluorocholine PET/CT is used to detect lymph node metastases in prostate cancer patients. Physiological ¹⁸F-fluorocholine in the gastrointestinal tract, especially in the intestines, may interfere with the detection of malignant lymph nodes. Fasting is frequently proposed in literature; however, scientific support is lacking. This study aims to determine the impact of fasting on ¹⁸F-fluorocholine uptake in the gastrointestinal tract.

Methods

Eighty patients were studied, 40 fasted for at least 6 h prior to ¹⁸F-fluorocholine administration while the other 40 did not fast. ¹⁸F-fluorocholine uptake pattern and intensity were evaluated in the intestine near the abdominal aorta and four regions near the iliac arteries. ¹⁸F-fluorocholine intensity was also measured in the liver, pancreas, stomach and spleen.

Findings

No statistically significant differences were found in ¹⁸F-fluorocholine uptake in the gastrointestinal tract between the fasting and non-fasting group.

Conclusions

Fasting for 6 h has no effect on ¹⁸F-fluorocholine uptake in the gastrointestinal tract. Therefore, no effects on the detection of malignant lymph nodes are expected, and fasting is not recommended in our opinion.

Evidence of 18F-FCH Uptake in Human T98G Glioblastoma Cells

AIM

Tumor and chemo/radiotherapy-damaged brain tissues are hardly distinguishable by conventional morphological imaging. (18)F-FCH was compared against (18)F-FDG in the T98G glioblastoma cell line with regard to their radiopharmaceutical uptake, in order to test its diagnostic power on brain tumor lesions.

MATERIALS AND METHODS

Equimolar amounts of (18)F-FCH and (18)F-FDG were added to human glioblastoma T98G cells and human dermal fibroblasts for 20, 40, 60, 90 and 120 min of incubation. Radiopharmaceutical uptake was expressed as a percentage of the administered dose. Cold choline was used for binding competition experiments.

RESULTS

In T98G cells (18)F-FCH was taken-up in higher amounts than 18F-FDG after 60 min. In fibroblasts, uptake was lower than 1% for both radiopharmaceuticals. Cold choline reduced the uptake of FCH to 1% similarly to fibroblasts.

CONCLUSION

Our results prove the efficacy of (18)F-FCH as a promising tracer, better than (18)F-FDG in establishing the tumor-to-background ratio in brain tumors.

Oncocytic Adenoma of Thyroid Incidentally Detected by 18F-Fluorocholine PET/CT

A 58-old-man underwent (18)F-fluorocholine PET/CT for restaging of prostate cancer because of a rising level of prostate-specific antigen.( 18)F-fluorocholine showed no significant tracer uptake at the site of the prostatectomy or the pelvic lymph nodes. Incidental high tracer uptake was observed in a 26 × 23 mm left thyroid nodule. A benign tumor of the thyroid (oncocytic adenoma of thyroid) was diagnosed after left loboisthmectomy.