An iterative approach to respiratory self‐navigated whole‐heart coronary MRA significantly improves image quality in a preliminary patient study. Issue 4 (8th May 2015) - Ginami, Giulia
Abstract : Purpose: In respiratory self‐navigated coronary MRA, the selection of a reference position may have a direct effect on image quality. While end‐expiration is commonly used as reference, it may be ill defined in cases of irregular breathing. Here, an iterative self‐navigation approach that operates without a reference position was implemented and tested in healthy volunteers and patients. Methods: Data were acquired in 15 healthy volunteers and in 23 patients. Images obtained with end‐expiratory self‐navigation were compared with those obtained with the iterative approach that incorporates cross‐correlation to iteratively minimize a global measure of respiratory displacement. Vessel sharpness, length, signal‐to‐noise ratio (SNR), and contrast‐to‐noise ratio (CNR) were evaluated while differences in breathing patterns between the two sub‐groups were assessed, too. Results: Vessel sharpness and length were similar for both methods in healthy volunteers. In patients, a significant improvement in vessel sharpness and length was obtained using the iterative approach. SNR and CNR remained constant. While end‐expiration was the most frequent respiratory phase in healthy volunteers (57.6 ± 16.2%), intermediate respiratory phases (43.4 ± 30.1%) were predominantly found in patients. Conclusion: An iterative approach to respiratory motion correction in self‐navigation may lead to significant improvements in coronary MRA image quality in patients with a less consistent end‐expiratory respiratory phase.Magn Reson Med 75:1594–1604, 2016. © 2015 Wiley Periodicals, Inc.