The Diagnostic Utility of Multiphase-CT (4D CT) in Localising Parathyroid Adenomas Following Negative or Discordant 99mTc-Sestamibi SPECT/CT and Ultrasound Imaging.

OBJECTIVES

To quantify the diagnostic utility of multiphase-CT as a second line imaging modality for parathyroid adenoma localisation including assessing the differences between patients undergoing second line imaging due to negative or discordant first-line imaging (MIBI SPECT/CT) results.

METHODS

Patients undergoing multiphase-CT following negative or discordant first-line imaging were collected retrospectively over a 5-year period from 2019-2023. 73 patients were included. Sensitivity, specificity, positive predictive value, negative predictive value, accuracy, positive and negative likelihood ratios of multiphase CT for preoperative parathyroid adenoma lateralisation (correct side) and localisation (correct quadrant) were calculated. Results for the whole cohort, negative imaging cohort and discordant imaging cohorts were compared.

RESULTS

Fifty-eight of the included patients were female, and 15 were male. Mean age was 56.2 ± 11.8. One-hundred and eighty-three quadrants and 98 sides were explored surgically. 69.8% patients underwent a minimally invasive surgical procedure. Across the whole cohort, multiphase CT demonstrated a sensitivity of 70.4% (95% CI 58-81) and specificity of 86.4% (79-92). For lateralisation, performance was higher with sensitivity 82.6% (72-91) and specificity 86.2% (68-96). Moderate positive likelihood ratios were also recorded as 5.26 (localisation) and 5.99 (lateralisation).

CONCLUSIONS

Multiphase CT provided reliable diagnostic accuracy for localisation and lateralisation of parathyroid adenomas in the context of discordant or negative first-line imaging. Its high specificity and moderate positive likelihood ratios make it a valuable rule-in tool that enables targeted surgical approaches.

ADVANCES IN KNOWLEDGE: This study provides one of the largest datasets in the literature. Positive results suggest that CT can be considered in cases of negative or discordant first-line imaging if minimally invasive surgical techniques are desired.