Ultrasound Strain Measurements for Evaluating Local Pulmonary Ventilation

Local lung function is difficult to evaluate, because most lung function estimates are either global in nature, e.g. pulmonary function tests, or require equipment that cannot be used at a patient's bedside, such as computed tomograms. Yet, local function measurements would be highly desirable for many reasons. In a recent publication [1], we were able to track displacements of the lung surface during breathing. We have now extended these results to measuring lung strains during respiration as a means of assessing local lung ventilation. We studied two normal human volunteers and 12 mice with either normal lung function or experimentally induced pulmonary fibrosis. The difference in strains between the control, normal mice and those with pulmonary fibrosis was significant (p < 0.02), while the strains measured in the human volunteers closely matched linear strains predicted from the literature. Ultrasonography may be able to assess local lung ventilation.