David B Hackney

How did you come to choose medicine? What drew you to neuroradiology?

I cannot remember when I did not think I would be a doctor. It was always part of my persona since I was a small child. I loved science; I liked the idea of having a direct impact, as opposed to only doing research, so medicine seemed the natural choice. I considered being a scientist, but ultimately I viewed the ability to be effective as less certain in science. Many people who take faculty jobs in the life sciences do not achieve the early career funding or research success required to get tenure. They end up not having the academic careers they have envisioned. Physicians in the same position can justify their existence by practicing clinical medicine. I thought that getting an MD was a far less risky career choice. Once I was in medicine, radiology and then neuroradiology appealed to me because of the constant innovation, and the direct influence on patient care. Neuroradiology in particular combined increasingly high tech methods with understanding the anatomy and biology of the central nervous system.

Which innovations in interventional neuroradiology have had significant impact on patient care?

The ability to treat aneurysms has changed the demands on diagnostic neuroradiologists, as have advances in treating arteriovenous malformations. Carotid stenting, if it survives current doubts about its efficacy relative to endarterectomy, also has made accurate diagnosis and monitoring more important.

Who were your mentors in the field and what do you still remember from their wisdom?

I have been fortunate to have a number of wonderful mentors over the years.

My first mentor was not a neuroradiologist. Boris Magasanik was my undergraduate advisor in biochemistry when I was a student at Harvard and he was the head of the Biology Department at MIT. He studied microbial physiology and regulation of gene expression. I suppose the most important thing I remember learning from him was his emphasis on the importance of studying data, rather than accepting the interpretations provided to me. He frequently would have me read older papers, the primary sources for what was at the time taught in textbooks. These were well done studies whose data were completely reliable, but for which the interpretation of the results had changed dramatically over the years.

My first mentor in neuroradiology was Charles Kerber at the University of California, San Diego. He is an interventional neuroradiologist and he taught me the importance of meticulous technique in performing procedures. During my fellowship, Kenneth Davis at Massachusetts General Hospital was my most important influence. When I started on the faculty at the University of Pennsylvania, as a newly-minted assistant professor, I worked with four senior faculty members: Drs Robert Zimmerman, Larissa Bilaniuk, Herbert Goldberg, and most important for me, Robert Grossman. I learned a great deal of practical neuroradiology from all of them, but Bob Grossman probably had the greatest impact on my career. I have benefited from my relationship with other neuroradiologists, most notably Robert Quencer, at the University of Miami, and scientist collaborators Robert Lenkinski, now at the University of Texas, Southwestern, and Felix Wehrli, at the University of Pennsylvania.

Which innovations in neuroradiology have shaped your career?

The constant advances in magnetic resonance have had the most impact on my career. Diffusion imaging and derivatives such as q-space imaging were particularly important.

Can you describe a memorable case?

For the things that interest me, the most memorable insights have not been from individual cases. Perhaps the most important was the realisation that we could use various MR methods to infer structure at a spatial scale far finer than the nominal resolution of the images. Thus, even with relatively large pixel sizes, one can interpret the studies in terms of changes in tissue architecture on the order of microns, or less. This decoupling of voxel size from spatial resolution meant that we could directly relate MR results to microscopic histopathology. Since there are many known implications of the pathologic changes at this scale, MR opened the door to in vivo imaging of these effects.

What are three key questions in neuroradiology that you would like to see answered?

I will share four. ­This is not related to my work, but I think neuroradiology will have a critical future role in diagnosing patients with cognitive decline and evaluating their response to therapy. One might include in this goal not only the dementias, but also common and severe psychiatric disorders such as depression and schizophrenia. This work is in its infancy, but perhaps I might simply express this as a wish—I hope to see neuroradiology contribute to a far better understanding of normal and abnormal cognition.

I hope neuroradiology can characterise changes in the glia and extracellular matrix of the central nervous system. One might think of the first goal, understanding cognition, as studying neurons and their interactions. Since the glia and matrix are also fundamental to neurological function, we should be able to provide a fairly comprehensive, spatially localised, description of the status of these components of the central nervous system.

The third goal I would ask is improved ability to predict stroke risk based on the status of the central nervous system vessels, including atheromatous disease, risk of plaque rupture, collateral supply, and the resilience of the brain itself. This could include guiding revascularisation therapy in the setting of acute stroke, but hopefully it would also help reduce the incidence of stroke and prevent many strokes before they occur.

Lastly, I hope neuroradiology can help with emerging studies of central nervous system tissue regeneration and axon guidance.