Spirometry-based reconstruction of real-time cardiac MRI: Motion control and quantification of heart–lung interactions

Abstract

Purpose: To test the feasibility of cardiac real-time MRI in combination with retrospective gating by MR-compatible spirometry, to improve motion control, and to allow quantification of respiratory-induced changes during free-breathing. Methods: Cross-sectional real-time MRI (1.5T; 30 frames/s) using steady-state free precession contrast during free-breathing was combined with MR-compatible spirometry in healthy adult volunteers (n = 4). Retrospective binning assigned images to classes that were defined by electrocardiogram and spirometry. Left ventricular eccentricity index as an indicator of septal position and ventricular volumes in different respiratory phases were calculated to assess heart–lung interactions. Results: Real-time MRI with MR-compatible spirometry is feasible and well tolerated. Spirometry-based binning improved motion control significantly. The end-diastolic epicardial eccentricity index increased significantly during inspiration (1.04 ± 0.04 to 1.19 ± 0.05; P