Mathematical model of the post-ablation enhancement zone as a tissue-level oedematic response
Journal
International Journal of Hyperthermia
Journal Volume
33
Journal Issue
2
Pages
111-121
Date Issued
2017
Author(s)
Abstract
Purpose: A hyperdense rim is commonly observed at the periphery of ablation zones during post-ablation imaging (e.g. ultrasound) in tumours. A mathematical model has been developed here to investigate the occurrence of this enhanced rim, caused by the ablated cells, giving an indication of the location of the final ablation region. Materials and methods: The enhanced rim has been assumed here to be due to a tissue-level oedematic response of viable cells, which necessitated coupling multiple modelling elements in a spatially distributed system: thermal cell death, tissue-state dependent ion concentration dynamics, ion transport in the extracellular space, and osmotic cell volume regulation. Results: In response to the imposed temperature function, an ablation zone was predicted, distinguishing the tissue state between ‘dead’ and ‘alive’. A disturbance in intracellular/extracellular ion concentrations was induced due to ion redistribution, which acted as an osmotic stress and contributed to significant cell swelling in a thin rim at the periphery of the ablation zone. It was also found that the rim size only changed slightly with varying lesion size, in response to different temperature profiles. Conclusions: The study presents a novel mathematical model to understand the enhanced rim surrounding the ablation zone by assuming tissue-level cell oedema as the primary potential cause. The model links the direct response to thermal injury to an observable secondary response, which could be of clinical value in that the location of this bright ring could potentially be used for more accurate determination of the extent of the ablation zone. ? 2016 Informa UK Limited, trading as Taylor & Francis Group.
Subjects
apoptosis
Article
cell swelling
cell viability
cell volume
controlled study
extracellular space
ion current
ion transport
mathematical model
membrane conductance
membrane potential
membrane steady potential
osmotic pressure
osmotic stress
radiofrequency ablation
temperature
Type
journal article