Characterization of pulmonary microcirculation according to hemodynamic changes with computed tomography

Abstract

The common and important change of pulmonary hemodynamics is represented by increased or decreased pulmonary blood flow (PBF) and increased pulmonary vascular resistance (PVR). We made 3 hemodynamic models in 5 dogs, that is, increased and decreased PBF model and increased PVR model. CT perfusion scan was performed.Perfusion parameters including blood flow (BF), blood volume (BV), mean transit time (MTT), and maximal slope (MS) were analyzed. In normal state, blood flow was affected by gravity and dependent area showed higher BF, BV and lower MS, MTT than non-dependent area. First, decreased PBF model showed no significant change in BV and elongation of MTT. Secondly, increased PBF model showed slightly increased BV and decreased MTT. Thirdly, increased PVR model showed significant decrease of BF, BV, and MS and slight increase of MTT without statistical significance. However, it was noticeable that the distribution of MTT according to gravity in normal lung was completely reversed in increased PVR model. In conclusion, on the basis of our understanding of perfusion characteristic in normal state, we can detect and evaluate the abnormal regional hemodynamic change in lung.Predicting the change of pulmonary vascular resistance should be possible by thorough analysis of CT perfusion parameters.