Acoustic imaging of the human chest

Study objectives: A novel method for acoustic imaging of the human respirat ory system is proposed and evaluated. Design: The proposed imaging system uses simultaneous multisensor recording s of thoracic sounds from the chest wall, and digital, computer-based postp rocessing. Computer simulations and recordings from a life-size gelatin mod el of the human thorax are used to evaluate the system in vitro. Spatial re presentations of thoracic sounds from 8-microphone and 16-microphone record ings from five subjects (four healthy male adults and one child with lung c onsolidation) are used to evaluate the system in vivo. Results: Results of the in vitro studies show that sound sources can be ima ged to within 2 cm, and that the proposed algorithm is reasonably robust wi th respect to changes in the assumed sound speed within the imaged volume. The images from recordings from the healthy volunteers show distinct patter ns for inspiratory breath sounds, expiratory breath sounds, and heart sound s that are consistent with the assumed origin of the respective sounds. Spe cifically, the images support the concept that inspiratory sounds are produ ced predominantly in the periphery of die lung while expiratory sounds are generated more centrally. Acoustic images from the subject with lung consol idation differ substantially from the images of the healthy subjects, and l ocalize the abnormality. Conclusions: Acoustic imaging offers new perspectives to explore the acoust ic properties of the respiratory system and thereby reveal structural and f unctional properties for diagnostic purposes.