University of Twente Student Theses


Improving preoperative imaging of parathyroid adenomas and exploring the benefits of surgical navigation during parathyroidectomy.

Veerbeek, T. (2022) Improving preoperative imaging of parathyroid adenomas and exploring the benefits of surgical navigation during parathyroidectomy.

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Abstract:Introduction: In patients with primary hyperparathyroidism (pHPT), the most preferred cure is minimally invasive excision of the hyperfunctioning gland (MIP). Adequate preoperative localization of the parathyroid adenoma (PA) is essential for successful treatment. Currently, four-dimensional computed tomography (4DCT) has emerged as new imaging modality for its high sensitivity and specificity, but is not able to guarantee preoperative localization. Its main drawback is inadequate differentiation of PAs from mimics such as thyroid nodes and lymph nodes. Moreover, the relative high radiation exposure of four CT scans makes it less favorable. In this study, we propose several concepts to (1) improve preoperative PA localization using (spectral) 4DCT, (2) reduce its radiation dose, and (3) explore the benefit of surgical navigation during MIP. Method: For our first aim, we introduce three concepts to improve tissue differentiation, based on the characteristic contrast enhancement patterns of PAs, as it is a highly vascularized organ, and the advantages of spectral CT. For the second aim, we examine the use of a three-phase protocol by replacing the true non-contrast (TNC) phase for a virtual non-contrast (VNC) reconstruction. For the third aim, we analyze the safety and feasibility of surgical navigation during MIP using three-dimensional (3D) models based on preoperative imaging. Results: Our first aim demonstrates that arterial contrast enhancement patterns can differentiate PAs from thyroid tissue. Hotspot maps express the difference in tissue contrast from the non-contrast phase and arterial phase. PAs have high contrast wash-in and can be distinguished from other tissues on this map. For the spectral reconstructions, the results were equal to the conventional scans. The second aim indicates that the VNC reconstruction did not have similar tissue contrast (in Hounsfield Units [HU]) compared to the TNC. However, alternative interpretation of the VNC reconstruction show differentiation of PAs from thyroid tissue (p = 0.008 for VNC¬¬VEN). For the surgical navigation project, our third aim, a 3D model was created successfully for each individual. All PAs were excised and confirmed by pathology. No complications connected to the navigation system were reported. Conclusion: We have introduced an index, based on the arterial enhancement of parathyroid adenomas that can improve differentiation. Hotspot maps have high potential and can support the radiologists to locate PAs. The advantages of spectral CT were not apparent in our study. In regard to the dose reduction, the tissue contrast of VNC reconstructions were not one-on-one comparable to the TNC. However, alternative interpretations of the VNC allow replacement of the TNC scan. Surgical navigation was safe and feasible. The surgeon states that the 3D model supports the interpretation of preoperative imaging and the navigation system accelerates identification of the PA intraoperatively.
Item Type:Essay (Master)
Faculty:TNW: Science and Technology
Subject:44 medicine
Programme:Technical Medicine MSc (60033)
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