Calculating resistance boundary conditions from PC-MRI data

[Justin Tso]

Hi all,

Is there a strategy for deriving the resistance outlet boundary condition in a patient-specific case given only PC-MRI data? From what I see in the clinical and user guides, it seems that you need to have some sort of approximate pressure value, or the resistance is just given, but from the PC-MRI data I can obtain, I may only have flow and velocity at a certain plane. For example, for something simple like a vertical stretch of the descending aorta, which is basically cylindrical, I could obtain the velocity profile for the inlet, but would I need extra data at the outlet, or is it still possible to model this and get accurate results that aren't simply guesses?

Thanks,
Justin

[Weiguang Yang]

For modeling the aorta, in addition to PCMRI data at the inlet, having PCMRI for the descending data helps you know how much resistance should be applied to the outlet of the descending aorta to match the flow in the descending aorta. If you don't have measurements for other branches such as the innominate, left carotid, and left subclavian arteries, you need to make some assumptions about the flow distribution. Pressure information is still needed to determine resistance values even if you have flow rate data for each outlet unless you don't care if the pressures are physiologic.
You can take a look at the following study.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3705983/