3D ultrasound shear wave elastography quantifies myocardial stiffness and anisotropy in the human heart

Myocardial stiffness (MS) is a key property of diastolic cardiac function which is altered in various cardiomyopathies. Its quantitative evaluation remains challenging due to the myocardium's complex anisotropic fiber architecture and dynamic contraction. We developed a novel 3D shear wave elastography (3D-SWE) system suitable for clinical translation based on 3D ultrafast volumetric imaging for the quantitative assessment of myocardial stiffness in the human heart. Validation was performed on calibrated phantoms and ex vivo in porcine hearts compared to standard 2D-SWE. In vivo feasibility was demonstrated on healthy volunteers and patients with transthyretin cardiac amyloidosis. We demonstrated that 3D shear wave propagation can be observed in vivo and that 3D-SWE provides quantitative assessment of myocardium anisotropy through shear wave velocities along and across fibers and fractional anisotropy. In addition, myocardial stiffness was significantly elevated in cardiac amyloidosis patients compared to normal myocardium, whereas the fractional anisotropy was decreased. The feasibility of volumetric myocardial stiffness mapping on the human heart was demonstrated showing the potential of 3D-SWE as a clinically oriented tool for early diagnosis of cardiomyopathies such as cardiac amyloidosis.