Sound transmission in human thorax through airway insonification: an experimental and computational study with diagnostic applications

Abstract

Pulmonary diseases and injury lead to structural and functional changes in the lung parenchyma and airways, often resulting in measurable sound transmission changes on the chest wall surface. Additionally, noninvasive imaging of externally driven mechanical wave motion in the chest (e.g., using magnetic resonance elastography) can provide information about lung stiffness and other structural property changes which may be of diagnostic value. In the present study, a comprehensive computational simulation (in silico) model was developed to simulate sound wave propagation in the airways, parenchyma, and chest wall under normal and pathological conditions that create distributed structural (e.g., pneumothoraces) and diffuse material (e.g., fibrosis) changes, as well as a localized structural and material changes as may be seen with a neoplasm. Experiments were carried out in normal subjects to validate the baseline model. Sound waves with frequency content from 50 to 600 Hz were introduced into the airways of three healthy human subjects through the mouth, and transthoracic transmitted waves were measured by scanning laser Doppler vibrometry at the chest wall surface. The computational model predictions of a frequency-dependent decreased sound transmission due to pneumothorax were consistent with experimental measurements reported in previous work. Predictions for the case of fibrosis show that while shear wave motion is altered, changes to compression wave propagation are negligible, and thus insonification, which primarily drives compression waves, is not ideal to detect the presence of fibrosis. Results from the numerical simulation of a tumor show an increase in the wavelength of propagating waves in the immediate vicinity of the tumor region.

Breath sound analyses of infants with respiratory syncytial virus acute bronchiolitis

“…9 Recently, the utility of a breath sound analysis as a simple, safe, and noninvasive lung function test has been studied, and technological progress in this field has been remarkable. 10,11 Clinically, current reports have suggested that new breath sound analyses can be used in the clinical evaluation of airway changes, 12 and have evaluated an assessment of airway obstruction using breath sound analyses in children. 13 The possibility to objectively evaluate the airway condition in infants has also been reported.…”

Breath sound analyses of infants with respiratory syncytial virus-induced acute bronchiolitis

“…Recent advances in breath sound analyses have been remarkable 10,11) . In clinical practice, attempts have been made to use breath sound analyses for the obstructive evaluation of airway narrowing 23,24) , and the technique is improving 18,22) .…”

“…Recently, the utility of a breath sound analysis as a simple, safe and non-invasive lung function test has been studied, and technological progress in this field has been remarkable 10,11) . Clinically, current reports have suggested that new breath sound analyses can be used in the clinical evaluation of airway changes 12) , and have evaluated the lung function using breath sound analyses in children 13) .…”

Image Human Thorax Using Ultrasound Traveltime Tomography with Supervised Descent Method

“…At this band, the thorax model is established and verified by simulations and experiments, see [30,31]. The feasibility of diagnosing pulmonary diseases using sound at this band is also researched, see [32,33]. Sound of frequency between 1 and 10 kHz is hard to permeate thorax.…”