"Per ardua ad astra" (J.S. Yule)

This thesis is dedicated to:

• My father, Wolfgang Hundertmark, who passed away too soon and will never be forgotten.

• My mother, Jutta Hundertmark, without whose support I would neither have been able to become a doctor in the first place nor going to Oxford and pursuing my motivation to become a better researcher.

• My sister, Katrin Hundertmark, who even offered refuge and dog sitting during the final and rather demanding writing phase of this Thesis.

• My wife, Claudia Hundertmark, who I would not have met without going to Oxford in the first place and who has become a rock solid part of my life.

• My dog , Leia, who reminded me of the importance of enthusiasm for life and daily exercise

The 'DPhil-Experience' at the University of Oxford was nothing short but life-changing for me.

During these 5 years, life events happened at an impressively fast pace:

• A global pandemic (the first in 100 years)

• Witnessing the devastating effects of the entirely new syndrome called COVID-19 first hand while volunteering on the COVID-Ward at the John Radcliffe Hospital with amazing colleagues

• Falling ill with COVID myself

• Meeting my wife, Claudia, and getting married and becoming a family with her son Luis.

While the necessity to permanently invest a tremendous amount of work and time to finally prevail and finish the DPhil are obvious, this intends to show that it is not necessarily the destination but mostly the journey creating (beautiful and not so beautiful) memories. Nevertheless, I would not want to miss any of them.

I always had the desire to really deepen my knowledge in a specific area of research but never knew what exact topic might interest me the most. Having spent the last years working in a combination of applied biochemistry, physiology, imaging and heart failure in the context of clinical trials, I do now.

I consider myself very privileged having been able to conduct research in a unique place like the Oxford Centre for Clinical Magnetic Resonance Research (OCMR). It provides a link for doctors, physicists, engineers and biochemists all working together on ground-breaking research and will certainly remain the epicentre of the global cardio-metabolic patient-facing research.

I was presented with countless challenges throughout the previous 5 years and luckily, I was fortunate enough to receive constant support and helpful advice, regardless of the underlying issue. For that, they will always have my deepest respect and gratitude.

During my training in Germany, the person inspiring me to sustain my research interest despite the stressful every-day hospital duties on weekends and nights and thus, someone I can easily call my mentor is the admirable and inspirational

I would not have made my way to Oxford without him and thus, I am forever grateful for his support.

The research was always accompanied by improving clinical skills in imaging or heart failure care and cardiomyopathies and this would have never been possible without the crucial guidance given to me by:

Many cherished colleagues have provided me with plenty opportunities for growth. For this I am thankful to:

I was also blessed to meet many people I am proud to call friends now. They have deeply impressed me with their intelligence, kindness and always offered support and an open ear in case of problems:

• Dr. Mark Peterzan

• Dr. Marco Spartera

• Dr. Matt Burrage

• Dr. Andrew Apps

• Dr. Arjun Jayaswal

• Dr. William Watson

• Dr. Marzia Rigolli

• Dr. Emmanuel Selvaraj

Thank you to the Radiographers and all admin staff within OCMR, especially Joana Leal Pelado, Jane Francis and Karen Whatley.

A special and sincere thanks to the OCMR Research Nurse Team, especially Judith DeLosSantos, Roser Farras-Araya, Marion 'Maz' Galley and Catherine Krasopoulos.