Hyperpolarized 129Xe MRI of Gas-Flow and Gas-Exchange Dynamics to Improve Treatment Planning and Detection of Treatment Complications in Oncology

Hyperpolarized (HP) 129Xe Magnetic Resonance Imaging (MRI) is an area of increasing interest in a wide variety of pulmonary diseases, including Chronic Obstructive Pulmonary Disease (COPD), asthma, cystic fibrosis, and interstitial lung disease. It may also potentially be used to detect areas of collateral ventilation and disease in patients with lung cancer to aid surgical and radiotherapy planning.

In healthy lungs, HP 129Xe-MRI demonstrates homogeneous signal intensities when imaged using a conventional breath-hold interval of 10-20s (static ventilation imaging). We have developed a novel dynamic HP 129Xe-MRI k-space sampling method to capture the dynamics of gas-flow during an entire breath cycle using interleaved-spiral readout trajectories. This new approach was optimized using finite element modelling of a gas-flow phantom. The feasibility of a rapid HP 129Xe-MRI approach on capturing the gas-flow dynamics was investigated on six subjects; three healthy and three COPD subjects.

HP 129Xe MR spectroscopy techniques have also been reported to potentially be a sensitive technique for capturing gas exchange dynamics due to the solubility and chemical shift of 129Xe gas in the Pulmonary Tissue-Blood Plasma (PTBP) and Red Blood Cell (RBC) compartments of the lungs. Our novel interleaved spiral k-space sampling technique has also been modified to enable imaging of the gas exchange dynamics in the lungs as a unique biomarker for gas ventilation, PTBP, and RBC compartments using the 4-point IDEAL (Iterative Decomposition of water and fat with Echo Asymmetry and Least-square estimation) approach. These biomarkers might be used to clinically detect and assess chemotherapy and radiation induced pneumonitis earlier than is currently possible, and potentially enable treatment modification.