Combining Hyperpolarized 129Xe MR Imaging and Spectroscopy to Estimate Pulmonary Vascular Resistance

Motivation: Pulmonary hypertension (PH) and reduced capillary blood volume, VC’, have competing effects on oscillations of the hyperpolarized 129Xe red blood cell (RBC) resonance, rendering it difficult to distinguish PH. Goal(s): Our goal was to correct RBC oscillations for reduced VC', then use corrected oscillations to estimate pulmonary vascular resistance (PVR). Approach: We developed a model of RBC oscillations as a function of VC’ in a cohort without known PH and used this model to derive a correction factor. Corrected oscillations were regressed against known PVR in a cohort with suspected PH. Results: Corrected oscillations improved PH sensitivity and were significantly correlated to PVR. Impact: Correcting oscillations in the hyperpolarized 129Xe red blood cell resonance for reduced pulmonary capillary blood volume improves sensitivity to pulmonary hypertension and permits estimation of pulmonary vascular resistance, thereby offering a non-invasive diagnostic alternative to right heart catheterization.