Elsevier

Medical Image Analysis

Volume 60, February 2020, 101627
Medical Image Analysis

Non-invasive estimation of relative pressure in turbulent flow using virtual work-energy

https://doi.org/10.1016/j.media.2019.101627Get rights and content
Under a Creative Commons license
open access

Highlights

  • vWERP-t uses virtual work-energy to accurately assess turbulent relative pressure.

  • In-vitro, vWERP-t shows 1:1 agreement with invasive measurements of relative pressure.

  • In transient flow, vWERP-t shows significant improvement compared to other approaches.

  • vWERP-t guarantees divergence free flow even in turbulent fields, improving accuracy.

Abstract

Vascular pressure differences are established risk markers for a number of cardiovascular diseases. Relative pressures are, however, often driven by turbulence-induced flow fluctuations, where conventional non-invasive methods may yield inaccurate results. Recently, we proposed a novel method for non-turbulent flows, νWERP, utilizing the concept of virtual work-energy to accurately probe relative pressure through complex branching vasculature. Here, we present an extension of this approach for turbulent flows: νWERP-t. We present a theoretical method derivation based on flow covariance, quantifying the impact of flow fluctuations on relative pressure. νWERP-t is tested on a set of in-vitro stenotic flow phantoms with data acquired by 4D flow MRI with six-directional flow encoding, as well as on a patient-specific in-silico model of an acute aortic dissection. Over all tests νWERP-t shows improved accuracy over alternative energy-based approaches, with excellent recovery of estimated relative pressures. In particular, the use of a guaranteed divergence-free virtual field improves accuracy in cases where turbulent flows skew the apparent divergence of the acquired field. With the original νWERP allowing for assessment of relative pressure into previously inaccessible vasculatures, the extended νWERP-t further enlarges the method's clinical scope, underlining its potential as a novel tool for assessing relative pressure in-vivo.

Keywords

Relative pressure
4D flow MRI
Virtual work-energy
Turbulence
Turbulent energy dissipation
Fluid mechanics

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