Non-invasive Estimation of Localized Dynamic Luminal Pressure Change by Ultrasound Elastography in Arteries with Normal and Abnormal Geometries.

Wang, Yahua; Lee, Wei-Ning

Arterial wall deformation, stiffness, and luminal pressure are well-recognized predictors of cardiovascular diseases but intertwined. Establishing a relationship among these three predictors is therefore important for comprehensive assessment of the circulatory system, but very few studies focused on this. In this study, we first derived a mathematical description for localized luminal pressure change (p) as a function of arterial wall strain () and transverse shear modulus (_T); the arterial wall was modelled as a transversely isotropic and piecewise linearly-elastic material. Finite element simulations (FES) and in vitro fluid-driven inflation experiments were performed on arteries with both normal and abnormal geometries and _T in the experimental study were estimated by an ultrasound elastographic imaging framework (UEIF). FES results showed good accuracy (percent errors 6.42%) of the proposed method for all simulated artery models. Experimental results showed excellent repeatability and reproducibility. Estimated (p) _pp values (average peak-to-peak pressure change) compared with pressure meter measurements in two normal geometry phantoms and an excised aorta were 65.95 4.29 mmHg vs. 66.45 3.80 mmHg, 60.49 1.82 mmHg vs. 59.92 2.69, and 36.03 1.90 mmHg vs. 38.8 3.21 mmHg, respectively. For the artery with abnormal geometry mimicking a simple plaque shape, the feasibility of the proposed method for p estimation was also validated. Results demonstrated that UEIF with the proposed mathematical model, which lumped wall deformation, stiffness and luminal pressure, could estimate the localized dynamic luminal pressure change noninvasively and accurately.