Ultrasound transmission at reduced frequencies in human lungs: a novelty for pulmonary diagnosis and monitoring

Conventional sonography cannot permeate the chest. Aerated lung tissue strongly scatters ultrasound and thus inhibits a significant penetration. Even thin slices of in vitro lung samples are opaque for any ultrasound from 10kHz to several MHz. As a common consensus, alternative technologies (X-ray, magnetic resonance imaging) are required for thoracic imaging. Interestingly, human lungs in vivo were never explicitly probed with ultrasound at lower frequencies below one MHz. In contrary to the expected opacity, this study reports a noticeable transparency: Apparently, ultrasound below one MHz can pervade the norm…