Justus E. Roos MD, Presenter: Nothing to Disclose

Sivaram Kaushik MS, Abstract Co-Author: Nothing to Disclose

H. Page McAdams MD, Abstract Co-Author: Research Grant, General Electric Company Consultant, MedQIA Author, Reed Elsevier Author, UpToDate, Inc

Bastiaan Driehuys PhD, Abstract Co-Author: Research support, General Electric Company Royalties, General Electric Company Stockholer, Polarean, Inc

Inhaled hyperpolarized 129Xe diffuses across the alveolar-capillary membrane and dissolves into two compartments: interstitium (barrier) and red blood cells (RBC). This results in an almost 200 ppm frequency shift in 129Xe resonance. The aim of this study is to quantify global and regional pulmonary gas-transfer using hyperpolarized (HP) 129Xe gas transfer MR spectroscopy and MRI, in healthy volunteers and subjects with IPF.

This IRB-approved and HIPAA compliant study was performed on a 1.5T GE clinical scanner. Gas transfer spectra were acquired in 11 healthy volunteers (HV) and 6 IPF subjects using 200-mL of HP 129Xe. Global gas-transfer was quantified using the ratio of the areas under the curves of the RBC and barrier resonance spectra. This RBC:Barrier ratio was correlated with DLCO. In two IPF subjects, 3D images of gas transfer to RBCs were reconstructed using a 1-point Dixon acquisition. Regional gas-transfer defects on RBC images were visually scored by dividing each lung into 16 regions (32 per subject). Presence or absence of 129Xe RBC signal in each region was correlated with the extent of fibrosis in the same region on CT (scored as no, mild, or severe fibrosis).

The RBC:Barrier ratio in IPF subjects was significantly reduced (0.16±0.03) when compared to healthy volunteers (0.55±0.13, p<0.05). Compared to healthy volunteers, IPF patients had significantly greater 129Xe signal in the barrier and less 129Xe signal in RBCs. The RBC:Barrier ratio correlated significantly with DLCO (r=0.89, p<0.05). RBC gas transfer defects within a total of 64 regions were in 28% (23/64) in regions with no fibrosis, in 39% (25/64) in regions with mild fibrosis and 33% (21/64) in regions with severe fibrosis by CT.

Gas-transfer MR spectroscopy and imaging using HP 129Xe can detect global and regional diffusion impairment in IPF patients and may correlate with extent of pulmonary fibrosis depicted by CT. 129Xe MRI can provide a radiation-free method for sensitive assessment of regional gas transfer and may be a useful biomarker to assess response to therapy.

Inhaled hyperpolarized 129Xe diffuses across the alveolar-capillary membrane and dissolves in the pulmonary red blood cells (RBC). This closely mimics the diffusion of O2 and hence imaging of 129Xe in RBCs can depict pulmonary gas exchange.

Roos, J, Kaushik, S, McAdams, H, Driehuys, B, Hyperpolarized 129Xe Gas-Transfer Spectroscopy and Imaging: Initial Experience in Patients with Idiopathic Pulmonary Fibrosis (IPF).  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14011561.html