Feature Of The Week 5/20/12: Dresden University of Technology Investigates Precision Lung Dynamics Using Four-Dimensional OCT
The treatment of urgent lung diseases, such as the acute respiratory distress syndrome and the acute lung injury, requires the development of protective ventilation strategies with the help of numerical simulations. For this purpose, information about the structure of lung tissue and its dynamics is required on an alveolar level. Optical coherence tomography (OCT) can obtain high resolution cross-sectional and volumetric data of lung tissue using rodent models. Access to the lung tissue is obtained by preparing a transparent thorax window. In previous studies, OCT imaging was limited by the depth scan rate and three-dimensional information has been obtained by the acquisition of lateral adjacent cross-sections in subsequent ventilation cycles. Additionally, triggering on pressure levels yields virtual four-dimensional information. However, the triggering on pressure levels causes a jitter between adjacent cross-sections, which requires a registration to compose three-dimensional stacks. Furthermore, deviations in the periodical structural changes over the acquisition time period of many ventilation cycles may hinder the reconstruction.
To overcome these obstacles, we propose four-dimensional OCT imaging for the visualization of the alveolar structural changes during single ventilation cycles. Thereby, a high-speed OCT system, based on Fourier domain mode locking technology, was utilized and provided a depth scan rate of 122.6 kHz. The acquisition of three-dimensional stacks was possible with a rate of 17 stacks per ventilation cycle. The reconstructed four-dimensional data did not exhibit perceptible image artifacts, emphasizing that the three-dimensional alveolar structure were directly accessible without registration and that the image acquisition time window of one single ventilation cycle is sufficient to obtain the entire four-dimensional information. Furthermore, the provided data allowed a quantitative evaluation. The volume pressure curve could be determined for single alveoli allowing the calculation of the alveolar compliance. Thus, four-dimensional OCT imaging is proposed as a suitable tool for the investigation and quantitative evaluation of alveolar tissue dynamics in animal models.
For more information see recent Article. Courtesy Lars Kirsten from the Dresden University of Technology.