PhD Defence Jorian Krol | Preoperative Imaging Pathway Optimisation in Primary Hyperparathyroidism; a focus on 4DCT and F-18-choline PET/CT

Preoperative Imaging Pathway Optimisation in Primary Hyperparathyroidism; a focus on 4DCT and F-18-choline PET/CT

Jorian Krol is a PhD student in the Department of Robotics and Mechatronics. (Co)Promotors are prof.dr.ir. C.H. Slump from the Faculty of Electrical Engineering, Mathematics and Computer Science (UT), prof.dr. W.J.G. Oyen from the Radboud University Nijmegen and dr. M.L.E. Bernsen from Rijnstate Hospital.

This thesis examines optimal imaging strategies for preoperative localisation of parathyroid adenomas in patients with primary hyperparathyroidism (PHPT), a prerequisite for minimally invasive parathyroidectomy. While ultrasonography (US) and technetium-99m sestamibi scintigraphy (MIBI) have traditionally been used, their limitations prompted investigation of advanced imaging techniques, particularly 4DCT and hybrid modalities. The primary research question addressed the preferred imaging pathway for localising parathyroid adenomas, supported by several secondary questions. Overall, the findings demonstrate that 4DCT outperforms the conventional combination of US and MIBI as first[1]line imaging, offering superior spatial and temporal resolution and improved localisation, especially when interpreted by experienced radiologists. Several protocol optimisations were evaluated. Subtraction or enhancement maps derived from 4DCT may improve lesion conspicuity and diagnostic confidence, particularly in complex cases. Protocol tailoring based on radiologist experience was shown to be important: a two-phase 4DCT protocol (non-enhanced and arterial phases) is sufficient for experienced neuroradiologists, reducing radiation exposure without compromising accuracy, while a three-phase protocol is suggested for less experienced readers. The thesis also assessed advanced techniques. Dual-layer spectral 4DCT did not provide additional diagnostic benefit over conventional 4DCT, and virtual non-contrast images were not reliable substitutes for true non-enhanced scans. Consequently, routine use of spectral imaging in this context is not recommended. Finally, the feasibility of combining 4DCT with F-18-choline PET/CT as a “one-stop shop” imaging approach was demonstrated. A protocol using two-phase 4DCT plus F-18-choline PET/CT offers complementary diagnostic information with a lower overall radiation dose than traditional multi-phase 4DCT and prior combined imaging strategies. This approach may benefit both patients and healthcare systems. In conclusion, the thesis endorses 4DCT as the preferred initial imaging modality in PHPT, underscores practical protocol enhancements, dismisses the routine application of dual-layer spectral CT, and points to combined F-18-choline PET/4DCT as a promising future approach. Further multicentre, multireader studies, cost analyses, and exploration of artificial intelligence applications are recommended to refine and validate a patient-centred, efficient “one-stop shop” imaging pathway.