The ratio of aortic diameter (or area or volume) and pulse pressure yields a derivative for in vivo measurable stiffness, called distensibility. Distensibility was calculated by means of the formula:

Amax−AminAmin×(Pmax−Pmin)\frac{A_{max} - A_{min}}{A_{min} \times (P_{max} - P_{min})}

Groenink, M., De Roos, A., Mulder, B. J. M., Spaan, J. A. E., & Van Der Wall, E. E. (1998). Changes in aortic distensibility and pulse wave velocity assessed with magnetic resonance imaging following beta-blocker therapy in the marfan syndrome. The American Journal of Cardiology, 82(2), 203–208. https://doi.org/10.1016/S0002-9149(98)00315-4