University of Twente Student Theses


Improvement of imaging techniques during the radiofrequency ablation procedure in benign thyroid nodules in the short term

Went, J. and Sterkenburg, I.P.J. and Aukema, L.M.N. (2020) Improvement of imaging techniques during the radiofrequency ablation procedure in benign thyroid nodules in the short term.

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Abstract:Background - Treatment of benign thyroid nodules consists of radiofrequency ablation (RFA) monitored by 2D ultrasound (2D-US). The clinical problem of this technique is its reliability on the subjective opinion of the operator. Therefore, to improve its objectivity, spatial anatomic insights and knowledge of the exact nodule volume are required. Objectives - The primary aim of this study is to evaluate the differences in ablation volume and its patterns after RFA procedure. Thereby, comparing the standard method 2D-US to the use of innovative 3D ultrasound (3D-US). Secondary, the calculated target volumes acquired with 2D calculations and Virtual Organ Computer- aided Analysis (VOCAL) are compared to the actual volume obtained with macroscopic slices, to investigate if these methods measure the actual volume of a target in Tissue-Mimicking Thermochromic Phantoms (TMTCPs) in an accurate fashion. Method - 22 TMTCPs are included of which 11 are ablated by an experienced radiologist using 2D-US and 11 using 3D-US. After RFA, slices are made and analysed in MATLAB regarding the following parameters: the ablated percentage, ablated volume outside the target, estimation of the operator, and systematic patterns. Besides, the volume of a target is calculated using 2D calculations and VOCAL which is compared to the macroscopic volume. Results - The ablated percentage is significantly 14,3% (95%-CI: 4,4-24,1%) higher for 2D-US compared to 3D-US (p=0,007). Further, the ablated volume outside the target shows no significant difference (p=0,172). In addition, the estimation of the operator shows a significantly bigger difference for 3D-US (p=0,000). A systematic pattern is found; the lower part of the target shows less tissue ablation, resulting in an unablated shell for both 2D and 3D-US. Furthermore, both 2D calculations (p=0,000) and VOCAL (p=0,003) give an overestimation of the actual volume of the target. Conclusions - In conclusion, 2D-US monitoring results in a more accurate representation of the ablated percentage and operator estimation compared to 3D-US. No significant difference is found regarding the ablated volume outside the target. Moreover, 2D calculations and VOCAL both overestimate the actual volume of a target respectively with 1,7 mL and 1,4 mL. Recommendations - Results show 3D-US currently offers no improvement over the standard 2D-US regarding the monitoring of RFA. To reach the aim of objectification of the RFA procedure, it is recommended to evaluate other techniques such as fusion imaging and needle tracking technology, both based on electromagnetic tracking.
Item Type:Essay (Bachelor)
Faculty:TNW: Science and Technology
Subject:44 medicine
Programme:Technical Medicine BSc (50033)
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