Vpliv kovinskih kirurških sponk na učinkovitost zdravljenja tumorjev v jetrih z ireverzibilno elektroporacijo

CINDRIČ, HELENA (author), Kos, Bor (mentor)

V zadnjem času se povečuje zanimanje za uporabo ireverzibilne elektroporacije za ablacijo globlje ležečih tumorjev, npr. v jetrih. Pri bolnikih s ponavljajočimi se metastazami so zaradi predhodnih posegov v jetrih pogosto prisotne kovinske kirurške sponke, kar lahko negativno vpliva na učinkovitost terapije. Cilj magistrske naloge je bil numerično ovrednotiti vpliv kovinskih kirurških sponk v bližini področja ablacije na učinkovitost zdravljenja tumorjev v jetrih z ireverzibilno elektroporacijo. Numerična študija je temeljila na devetih kliničnih primerih zdravljenih tumorjev – štirih s kovinskimi kirurškimi sponkami v bližini področja ablacije in petih brez kovinskih sponk. Za vsak obravnavani primer smo na podlagi medicinskih slik in kliničnih podatkov izdelali tridimenzionalni anatomski numerični model ter rekonstruirali potek zdravljenja z ireverzibilno elektroporacijo. Študija je temeljila na analizi električnega polja, saj je pokritje celotne prostornine tumorja in varnostnega pasu z dovolj visokim električnim poljem ključno za uspeh terapije. Za numerične izračune smo uporabili predhodno razvito numerično ogrodje za načrtovanje terapij, ki temeljijo na elektroporaciji. Izračuni so pokazali, da je vpliv kovinskih kirurških sponk zelo lokalen. Spremembe v električnem polju opazimo le v radiju nekaj milimetrov okoli sponke, pri čemer se na nekaterih mestih polje zmanjša, na drugih pa poveča. Sponke se v obravnavanih kliničnih primerih niso nahajale neposredno v tumorju, temveč na robu ali v okolici tumorja, zato niso bistveno vplivale na pokritje tumorjev. Spremembe električnega polja so bile bolj očitne v varnostnem pasu, kar pa je prav tako lahko kritično za uspeh terapije, saj se v okolici tumorja lahko nahajajo mikrometastaze. Kljub nekaterim pomanjkljivostim modelov je bila korelacija med kliničnimi in numeričnimi rezultati dobra. Glede na izračune prisotnost sponk pri večini primerov ni bila glavni oz. edini vzrok za neuspeh zdravljenja, kljub temu pa lahko zaključimo, da kovinske kirurške sponke v nekaterih primerih lahko negativno vplivajo na učinkovitost terapije z elektroporacijo, zato njihova prisotnost v bližini področja ablacije ni zaželena.

• Language: Slovenian
• Keywords: ireverzibilna elektroporacija, numerično modeliranje, numerična rekonstrukcija, načrtovanje terapij, metastaze v jetrih
• Work type: Master's thesis/paper
• Organization: FE - Faculty of Electrical Engineering
• Year: 2018
• PID: 20.500.12556/RUL-101886
• Publication date in RUL: 09.07.2018

Secondary language

• Language: English
• Title: Influence of metallic surgical clips on the efficacy of treatment of liver tumors with irreversible electroporation

Abstract

Irreversible electroporation has seen increasing use for ablation of deep-seated tumors, for example in the liver. Patients with recurring metastases often have metallic surgical clips present in the liver due to previous treatment, which may cause a decrease in efficiency of an electroporation-based treatment. The aim of this master thesis was to numerically evaluate the potential influence of metallic surgical clips in vicinity of the ablation zone on the efficacy of treatment of liver tumors with irreversible electroporation. Nine clinical cases of liver tumors were used for this numerical study – four with metallic surgical clips present in vicinity of the ablation zone and five without clips. For each case an anatomically correct numerical model was built based on patients' medical images and the irreversible electroporation treatment was reconstructed using the patient specific clinical data. The analysis was based on electric field distribution in the tumor and safety margin, since complete coverage with sufficiently high electric field is a prerequisite for successful ablation with irreversible electroporation. A previously designed numerical framework for treatment planning of electroporation-based therapies was used for the numerical computations. Numerical calculations showed distortions in electric field only in the immediate vicinity of the clip in a range of a few millimeters. Surgical clips were not present directly in the tumor volume but rather on the margin or more often near the tumor. Due to a very local influence on the field, the presence of clips did not drastically affect the tumor coverage itself. However, distortions in electric field were more evident in the ablation safety margin, which can also be critical for treatment success, since micrometastases can be present in vicinity of the tumor. Despite some limitations of the reconstructed models, a good concordance between clinical and numerically calculated outcomes has been achieved. According to calculations, the presence of clips was not the major or sole cause for treatment failure in the majority of cases. However, based on our results we can conclude that in some cases the presence of metallic surgical clips can negatively affect the treatment outcome and is therefore not desired.

• Keywords: irreversible electroporation, numerical modelling, numerical reconstruction, treatment planning, liver metastases