Measuring Pulmonary Gas Exchange with Hyperpolarized 129Xe Chemical Shift Saturation Recovery Spectroscopy and Imaging

Motivation: Chemical shift saturation recovery (CSSR) is a useful tool for measuring pulmonary gas exchange, but lacks regional information and error quantification. Goal(s): To perform CSSR spectroscopy and imaging with an improved analysis pipeline in humans. Approach: CSSR spectroscopy was performed in eight healthy volunteers and two systemic sclerosis patients. A simultaneous gas-phase/dissolved-phase 129Xe 2D gradient echo sequence was used for CSSR imaging in three healthy volunteers. Spectroscopy and imaging data were fitted to the Patz model using bootstrapping to estimate parameter uncertainties. Results: The mean error on the alveolar septal thickness (from spectroscopy) was 10%. The CSSR imaging maps agreed quantitatively with spectroscopy. Impact: Error quantification of CSSR parameters is important for clinical utility and interpretation. Dynamic CSSR gas uptake imaging allows for regional quantification of alveolar septal thickness, which could help identify fibrosis in heterogeneous lung disease.