Conventional imaging techniques plus 18F-Fluorocholine PET/CT: a comparative study of diagnostic accuracy in localizing parathyroid adenomas in primary hyperparathyroidism

Abstract

Background: Currently ¹⁸F-Fluorocholine (FCH)-PET/CT is a choice beyond widely used techniques like ultrasound (US) and technetium-99m sestamibi (MIBI) for primary hyperparathyroidism (pHPT). It remains uncertain how FCH-PET/CT collaborates with those two traditional modalities. This study aims to prospectively evaluate the effectiveness of individual, complementary, and combined utilization of FCH-PET/CT for preoperative localization.

Methods: All participants underwent US, MIBI, and FCH-PET/CT examinations, and eligible patients underwent parathyroid surgery based on surgical indications and patient preferences. McNemar's test compared diagnostic performance between imaging techniques and Spearman's rank correlation correlated FCH-PET/CT parameters with lesion volume, laboratory, and histological features.

Results: 63 out of 83 recruited patients underwent parathyroidectomy. Histologically confirmed parathyroid lesions were found in 69 glands among 63 patients. FCH-PET/CT exhibited higher sensitivity than US, MIBI, and US/MIBI combination (87.0% vs. 49.3%, P <0.001; vs. 49.3%, P <0.001; vs. 66.7%, P=0.006). As a second-line modality after US, MIBI, and US/MIBI combination, FCH-PET/CT achieved sensitivities of 88.6%, 77.1%, and 80.9% in detecting US-negative lesions, MIBI-negative lesions, and lesions with negative or conflicting US/MIBI results, respectively. Among various imaging combinations, the combined use of US and FCH-PET/CT showed significantly higher sensitivity than FCH-PET/CT alone (94.2% vs. 87.0%, P=0.025) and similar sensitivity with higher specificity than the combination of all three modalities (sensitivity: 94.2% vs. 95.7%, P=0.317; specificity: 98.9% vs. 95.1%, P=0.008).

Conclusions: FCH-PET/CT is effective as a first-line or complementary technique, irrespective of prior US, MIBI or US/MIBI combination. US combined with FCH-PET/CT appears to be the most effective localization strategy among the modalities evaluated in this study. Our findings support an ultrasound-first approach for localizing primary hyperparathyroidism, with FCH-PET/CT referral in uncertain cases to enhance success rates.

Keywords: 18F-Fluorocholine PET/CT; neck ultrasound; parathyroid hormone; primary hyperparathyroidism; technetium-99m sestamibi scintigraphy.

Figure 1

Participant flow diagram. 83 participants were recruited in this study and underwent all three parathyroid localization techniques. Twenty patients declined referral for parathyroidectomy and opted for periodic monitoring, whereas sixty-three patients underwent parathyroid surgery. Parathyroid neoplasms were confirmed in 69 lesions from these 63 patients.

Figure 2

Clinical decision flowchart. In the current approach (a), minimally invasive parathyroidectomy has become the preferred surgical treatment option following successful localization using US and MIBI. Other imaging modalities, such as 4D-CT, MRI, PET, and venous sampling, are typically reserved for cases with negative or inconclusive results from traditional methods. The choice of these methods depends on their cost-effectiveness and resource availability. In contrast, the proposed US/FCH-PET/CT combined strategy (b) supports using US as the primary modality, reserving FCH-PET/CT for cases where US results are inconclusive. Under this approach, the additional value of MIBI is minimal.