Adjudication committee
- First opponent: Senior Lecturer Sonia Nielles-Vallespin, Imperial College London, UK
- Second opponent: Director Marius Widerøe, NTNU: Norwegian University of Science and Technology,
- Third member and chair of the evaluation committee: Professor II Atle Bjørnerud, University of Oslo
Chair of the Defence
Professor II Mona-Elisabeth Rootwelt-Revheim, University of Oslo
Principal Supervisor
Emil Knut Stenersen Espe, University of Oslo
Summary
This thesis is within the field of cardiology and investigates the relationship between cardiomyocyte organization and regional myocardial function post-myocardial infarction (MI).
The primary hypothesis of the thesis is that alterations in cardiomyocyte orientations due to MI correlate with changes in regional myocardial function.
Our hypothesis was tested in a post-MI rat model, utilizing advanced magnetic resonance imaging (MRI) techniques. MRI’s sensitivity to molecular diffusion was utilized to assess cardiomyocyte orientations, as water molecules in the myocardium diffuse more freely along the principal direction of cardiomyocytes. Tissue phase mapping (TPM) MRI was used to measure myocardial velocities, from which regional myocardial strains were derived. In order to assess myocardial function with the required level of detail to study the structure-function relationship of the post-MI heart, we developed an accelerated TPM technique that allowed the whole left ventricle to be measured within a single scan session. Additionally, an image processing framework was developed to enable evaluation of regional myocardial function with a high level of spatial detail.
Our results indicated that post-MI remodelling of cardiomyocyte orientation near the infarct correlated with changes in regional strain, in a way that suggests a causal relationship where strain aligns with the remodelled cardiomyocyte directions. These findings suggest that knowledge about the changes in cardiomyocyte organization is crucial to understanding post-MI cardiac function.
