title: Phase-contrast MRI and CFD modeling of apparent ³He gas flow in rat pulmonary airways.
abstract: Phase-contrast (PC) magnetic resonance imaging (MRI) with hyperpolarized ³He is potentially useful for developing and testing patient-specific models of pulmonary airflow. One challenge, however, is that PC-MRI provides apparent values of local ³He velocity that not only depend on actual airflow but also on gas diffusion. This not only blurs laminar flow patterns in narrow airways but also introduces anomalous airflow structure that reflects gas-wall interactions. Here, both effects are predicted in a live rat using computational fluid dynamics (CFD), and for the first time, simulated patterns of apparent ³He gas velocity are compared with in vivo PC-MRI. Results show (1) that correlations (R²) between measured and simulated airflow patterns increase from 0.23 to 0.79 simply by accounting for apparent ³He transport, and (2) that remaining differences are mainly due to uncertain airway segmentation and partial volume effects stemming from relatively coarse MRI resolution. Higher-fidelity testing of pulmonary airflow predictions should therefore be possible with future imaging improvements.
authors: Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352, USA. kevin.minard@pnnl.gov
authors: Kevin R
authors: KR
authors: Minard
authors: Andrew P
authors: AP
authors: Kuprat
authors: Senthil
authors: S
authors: Kabilan
authors: Richard E
authors: RE
authors: Jacob
authors: Daniel R
authors: DR
authors: Einstein
authors: James P
authors: JP
authors: Carson
authors: Richard A
authors: RA
authors: Corley
mesh_terms: D000465:Algorithms; D000818:Animals; D019985:Benchmarking; D002138:Calibration; D005583:Fourier Analysis; D006371:Helium; D007091:Image Processing, Computer-Assisted; D008168:Lung / Q000502:physiology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D019047:Phantoms, Imaging; D012123:Pulmonary Ventilation / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012121:Respiration, Artificial
chemical_list: D006371:Helium