The Role of 4D-CT in Hyperparathyroidism with Negative Scintigraphy: Identifying Causes of Diagnostic Challenges

Objective: The objective of this study is to evaluate the efficacy of four-dimensional computed tomography (4D-CT) in detecting parathyroid lesions not detected by scintigraphy, based on surgical findings, determine the frequency of lesions that go unnoticed or are evaluated as false positives (FP) and identify the causes thereof. Methods: The population of this retrospective study consisted of 44 patients diagnosed as having hyperparathyroidism in our tertiary university hospital between August 2022 and January 2024, underwent scintigraphy, and had a 4D-CT scan upon negative scintigraphy results. A number of preoperative parameters, including demographic, laboratory, and clinical characteristics and imaging results of 38 patients included in the study sample, were analyzed. The patients’ preoperative 4D-CT and surgical findings were compared in terms of abnormal parathyroid lesions. Results: The mean age of the sample was 54.8±13.1 years. Twenty (52.6%) patients were asymptomatic, and 18 (47.4%) were symptomatic. 4D-CT imaging results revealed that the diagnoses of 36 (76.6%) patients were true positive (TP), 5 (10.6%) were FP, and 6 (12.8%) were false negative (FN). There were significant differences between the TP, FP, and FN groups in age, preoperative calcium levels, maximum lesion diameter, and short-to-long axis ratio of the lesion. Conclusion: The 4D-CT demonstrates high accuracy in detecting parathyroid lesions in patients with scintigraphy-negative hyperparathyroidism. Factors such as preoperative calcium levels, age, and lesion size significantly influence diagnostic outcomes. The integration of 4D-CT into preoperative evaluation can enhance lesion localization, improving surgical planning and management.