University of Twente Student Theses


A dynamic heart phantom based on Polyvinyl Alcohol Cryogel for Temperature Validation after Radiofrequency Ablation

Doest, S.L. (2023) A dynamic heart phantom based on Polyvinyl Alcohol Cryogel for Temperature Validation after Radiofrequency Ablation.

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Abstract:Background Atrial fibrillation is the most common type of cardiac arrhythmias, which can lead to irregular heart rhythms. A new advancement in the treatment is radio-frequency ablation (RFA). This treatment involves applying a radiofrequency energy to create controlled tissue damage. Post-ablation assessment of the temperature changes is possible through T1 and T2 mapping. Besides that, real-time MR thermometry is a promising technique for the guidance of the procedure. The development of a phantom is necessary to simulate the heart’s dielectric properties for effective RFA training and validation. In this study, a phantom composed of the temperature sensitive material polyvinyl alcohol (PVA) has been developed. Methods To study the relationship between temperature and T1/T2 relaxation times, 33 spherical phantoms were heated in a water bath to different temperatures. A rectangular phantom was used to perform needle ablation from which 3D T1/T2 maps could be obtained and converted into temperature maps. Two final cardiac phantoms underwent radiofrequency catheter ablation and were also evaluated using 3D T1/T2 maps, from which the temperature maps could be generated. All imaging was done on a Siemens 1.5T MRI scanner with specific scanning protocols for T1 and T2 mapping. Results A positive, and linear correlation has been established between elevated temperatures and the increase in T1 relaxation times. This linear relationship with temperature does not entirely apply for T2 relaxation times. The ablated areas can be visualized, but not yet validated correctly, by deriving temperature maps from the T1 and T2 maps. Conclusion A dynamic heart phantom composed of PVA and salt has the potential for validation and training in RFA procedures, serving as a basis for the development of monitoring techniques.
Item Type:Essay (Bachelor)
Faculty:TNW: Science and Technology
Programme:Biomedical Technology BSc (56226)
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