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

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

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

Preoperative localization of parathyroid glands in secondary hyperparathyroidism: correlations between 99mTc-MIBI-SPECT/CT, ultrasound, and pathological characteristics

Objective

To investigate the association between imaging findings and histopathological characteristics of parathyroid glands in patients with secondary hyperparathyroidism (SHPT).

Methods

Seventy-four glands from 21 patients with SHPT who underwent parathyroidectomy were evaluated for their pathological characteristics. The detection rates of parathyroid glands using ultrasound (US) and 99Tc-MIBI-SPECT/CT (MIBI) were compared. Glands were classified as either US-positive or US-negative, and MIBI-positive or MIBI-negative. Morphological and pathological differences between the positive and negative groups were systematically analysed.

Results

The detection rates for parathyroid glands were 71% with US, 65% with MIBI, and 82% when combining both methods. US and MIBI showed similar localization accuracy in SHPT (P = .38). MIBI-positive glands had significantly larger oxyphil nodules compared with MIBI-negative glands (area: 10.92 mm² vs 3.09 mm², P < .01; area proportion: 61% vs 30%, P = .002), while no significant differences were found in chief nodules. The US-positive group had fewer and smaller chief nodules (number: 2 vs 9, P = .005; area: 1.53 mm² vs 11.08 mm², P = .033) and a higher percentage of oxyphil nodules (74% vs 33%, P = .003) compared with the US-negative group. Thirteen glands undetected by both US and MIBI had smaller oxyphil nodule areas (3.59 vs 13.24 mm²) and lower oxyphil nodule area percentages (25% vs 68%). These pathological features, including adipose infiltration, intra-gland haemorrhage, cyst formation, and calcification, showed no correlation with the gland's imaging results.

Conclusion

US and MIBI had similar value in preoperative localization of SHPT. Parathyroid glands with more and larger oxyphil nodules were more likely to be detected by both MIBI and US.

Endocrinology application of molecular imaging: current role of PET/CT

BACKGROUND

In recent years, nuclear medicine imaging methods have proven to be of paramount importance in a wide variety of diseases, particularly in oncology, where they are crucial for assessing the extent of disease when conventional methods fall short. Moreover, nuclear imaging modalities are able to better characterize lesions using target agents related to specific pathways (e.g. glucose metabolism, cellular proliferation, amino acid transport, lipid metabolism, specific receptor ligands). The clinical presentation of endocrine diseases encompasses a broad spectrum of sign and symptoms. Moreover, endocrine tumors show varying degrees of aggressiveness from well differentiated and indolent to highly aggressive cancers, respectively.

RATIONALE

With the application of new medicinal radio-compounds and increasingly advanced tomographic imaging technology, the utility of Positron Emission Tomography/Computed Tomography (PET/CT) in the field of endocrine diseases is expanding.

AIM

This review aims to analyze and summarize the primary indications of PET/CT, providing a practical approach for clinicians. A comprehensive literature search on PubMed was conducted to provide an updated overview of the available evidence regarding the use of PET/CT in endocrinology. Within this review, we will discuss the applications of PET/CT, compare different radiopharmaceuticals and highlight the uptake mechanism, excluding neuroendocrine carcinomas from discussion.

CONCLUSIONS

PET/CT is a valuable tool in diagnosing and managing endocrine disorders due to its capacity to furnish both functional and anatomical information, facilitate early lesion detection, guide treatment decisions, and monitor treatment response. Its non-invasive nature and precision make it an integral component of modern endocrine healthcare. This review aims to provide physicians with a clear perspective on the role of PET/CT imaging, discussing its emerging opportunities and appropriateness of use in endocrinological diseases.

A Positive Parathyroid Washout May Obviate the Need for Nuclear Scintigraphy in Parathyroid Adenoma Localization: A Retrospective Study

BACKGROUND

Minimally invasive parathyroidectomy (MIP) in patients with a parathyroid adenoma (PA) requires imaging modalities for precise localization. Parathyroid hormone assay on ultrasound-guided fine-needle aspiration washout, or PTH washout, can be used for this purpose. It is unclear whether PTH washout complements traditional PA localization techniques such as a sestamibi (MIBI) scan or diminishes its need. This study aims to determine whether a positive PTH washout obviates the need for an MIBI scan in the preoperative localization of a PA.

METHOD

A multi-center retrospective, comparative review comprised adult patients who underwent MIP at 2 McGill University teaching hospitals between 2018 and 2022. Patients who had both PTH washout and MIBI scan for preoperative localization of PA, final histopathology reports available, and preoperative/postoperative results recorded were included in the final analysis.

RESULTS

Of the 193 patients' charts reviewed, 87 were included in this study. Of these 87 patients, 74.7% (65/87) had a positive PTH washout result. Among those, MIBI correctly detected 90.8% (59/65) of the PAs. The MIBI scan did not contribute meaningful information for any of the 65 patients who had positive PTH washout results.

CONCLUSION

These findings strongly support the use of preoperative dedicated ultrasound as the initial standard procedure. When a PA candidate on ultrasound is found, a PTH washout should be performed. If positive, it could suffice as the sole localization method for MIP surgery. When a PA was identified on ultrasound and confirmed with PTH washout, the MIBI scan did not add more information. Benefits include fewer patient tests, less exposure to ionizing radiation, and reduced healthcare expenses.

Pitfalls of DualTracer 99m-Technetium (Tc) Pertechnetate and Sestamibi Scintigraphy before Parathyroidectomy: Between Primary-Hyperparathyroidism-Associated Parathyroid Tumour and Ectopic Thyroid Tissue

Diagnosis of primary hyperparathyroidism (PHP) is based on blood assessments in terms of synchronous high calcium and PTH (parathormone), but further management, particularly parathyroid surgery that provides the disease cure in 95-99% of cases, requires an adequate localisation of the parathyroid tumour/tumours as the originating source, with ultrasound and 99m-Technetium (99m-Tc) sestamibi scintigraphy being the most widely used. We aimed to introduce an adult female case diagnosed with PHP displaying unexpected intra-operatory findings (ectopic thyroid tissue) in relation to concordant pre-operatory imaging modalities (ultrasound + dual-phase 99m-Tc pertechnetate and sestamibi scintigraphy + computed tomography) that indicated bilateral inferior parathyroid tumours. A sudden drop in PTH following the removal of the first tumour was the clue for performing an extemporaneous exam for the second mass that turned out to be non-malignant ectopic thyroid tissue. We overviewed some major aspects starting from this case in point: the potential pitfalls of pre-operatory imaging in PHP; the concordance/discordance of pre-parathyroidectomy localisation modalities; the need of using an additional intra-operatory procedure; and the clues of providing a distinction between pathological parathyroids and thyroid tissue. This was a case of adult PHP, whereas triple localisation methods were used before parathyroidectomy, showing concordant results; however, the second parathyroid adenoma was a false positive image and an ectopic thyroid tissue was confirmed. The pre-operatory index of suspicion was non-existent in this patient. Hybrid imaging modalities are most probably required if both thyroid and parathyroid anomalies are suspected, but, essentially, awareness of the potential pitfalls is mandatory from the endocrine and surgical perspectives. Current gaps in imaging knowledge to guide us in this area are expected to be solved by the significant progress in functional imaging modalities. However, the act of surgery, including the decision of a PTH assay or extemporaneous exam (as seen in our case), represents the key to a successful removal procedure. Moreover, many parathyroid surgeons may currently perform 4-gland exploration routinely, precisely to avoid the shortcomings of preoperative localisation.