Application of lung ultrasound surface wave elastography in the evaluation of diffuse lung diseases

The evaluation of diffuse lung disease invariably involves chest computerized tomography (CT). The detailed information obtained is often equivalent to that from lung biopsies. It, however, involves exposure to ionising radiation which limits its repeated application in monitoring and follow up. Ultrasound techniques offer potentially safer/cheaper alternatives and lung ultrasound surface wave elastography (LUSWE) is a novel, noninvasive, and clinically feasible technique to quantify lung stiffness, an important biomechanical property that changes in diffuse fibrotic and infiltrative lung diseases. We have developed a sensitive, accurate and reproducible technique to measure changes in lung surface stiffness by using surface wave transmission speed and demonstrated its value in detecting and staging the degree of fibrosis in diffuse interstitial lung diseases, specifically idiopathic pulmonary fibrosis and progressive systemic sclerosis associated lung disease, as well as changes in heart failure. The technique consists of ultrasound detection of the propagation speed of a wave generated by the vibrations from an indenting shaker in multiple intercostal spaces to provide a representative assessment of both lungs. It offers the prospect of simple, radiation-free, repetitive assessment of changes in acute and chronic diffuse lung diseases with the potential for easy and rapid bedside use, all important considerations in clinical practice.