MRI Image-Guided Tumor Ablation: Model to Predict Cell Death from MRI Temperature Images

Miyuki Breen, Biomathematics

Solid tumors and other pathologies can be treated using laser thermal ablation under magnetic 
resonance imaging (MRI) guidance. We are investigating the ability of MRI to monitor ablation 
treatments by comparing modeled tissue damage from MRI temperature images to histologically 
assayed cellular damage. We developed a model to predict cell death from MRI thermometry 
measurements and applied it to in vivo rabbit brain data. An open MRI system was used to guide 
an ablation laser fiber into rabbit brains and acquire a sequence of MRI temperature images 
during heating and MRI lesion images post-ablation. Ablation occurred by heating the tissue with 
a laser power source. We aligned the post-ablation MRI lesion image to the post-ablation MRI 
lesion images, and used the outer boundary of the hyperintense rim in the MRI lesion image as 
the boundary for cell death, as verified from histology. Model parameters were simultaneously 
estimated using an iterative optimization algorithm applied to every interesting voxel in over 
185 images from multiple experiments having various temperature histories. The model gave a 
voxel sensitivity and specificity of 86.9% and 98.8%, respectively. Mislabeled voxels typically 
were within one voxel of the segmented necrotic boundary. This is good evidence that MRI 
temperature maps can be used with our model to predict therapeutic regions in real-time.






Title: Mechanistic Model of Escherichia Coli Cell Death under Acidic
Conditions

By:

Althea Smith, Biomathematics

Abstract:
By processing acidified vegetable products, e.g. pickles, there is risk of
contamination by microbial pathogen such as Escherichia coli. We have
developed a mechanistic mathematical model which can be used to understand
the mechanism behind the killing of these deadly bacteria. Our model
predicts that killing of E. coli is due to the low levels of intracellular
pH. The continued development of this model will aid in enhancing safety
for acidified food production.