Meeting Abstract

P3.169  Monday, Jan. 6 15:30  Phase-contrast MRI analysis of Diapsid respiratory flow patterns in situ CIERI, R.L.*; FARMER, C.G.; University of Utah; University of Utah bob.cieri@gmail.com

The study of fluid flow in biological structures has historically been hindered by the difficulty of observing realistic fluid motion in situ. Respiratory flow is especially difficult to study because body tissues that affect ventilation, such as the bones and muscles involved in costal ventilation, prevent direct observation of flow and artificial ventilation of excised respiratory structures may produce ventilatory patterns different from those in vivo. Here we present a novel method of observing flow patterns in diapsid lungs. The respiratory systems of euthanized and intubated animals encased in airtight PVC chambers are filled with water. Ventilation of water at a biologically-relevant Reynolds number is then accomplished by programmed changes in air pressure on the lizard body to more accurately simulate in vivo inhalation and exhalation. The direction of respiratory system fluid flow is recorded in three planes with phase-contrast (PC) MRI throughout several ventilatory cycles. These data are then integrated into whole-lung vector maps in MATLAB. Our results confirm unidirectional airflow patterns previously discovered in Varanus exanthamaticus using heated thermistor air flow probes and provide additional information on regional flow patterns in the lungs of V. exanthematicus. This method should enable accurate determination of ventilatory flow patterns in a diverse range of taxa with costal ventilation, providing for a more accurate phylogenetic placement for the origin of unidirectional airflow patterns in the lung. In addition, because PC MRI flow data is collected at each point during the entire ventilatory cycle and the duration and speed are easily variable, this method may help to determine the morphological and behavioral parameters influencing lung flow patterns.