Application of a Novel Motion Resistant Phase Ordering Technique to Segmented 2D Imaging of the Heart

Introduction Prospective navigator-echo controlled scans are a widely used as an alternative to breath-hold acquisitions, generating respiratory motion free images with minimal patient co-operation. Such acquisitions require the setting of a navigator acceptance window (normally 5mm), usually about the end expiratory pause position, resulting in a scan efficiency during steady free-breathing of typically around 40 45%. Phase ordering and weighting techniques have been shown to improve image quality for a given acceptance window (2,3) and these have been used for conventional 2D and segmented (multiple kJ 3D acquisitions. Changes in the breathing pattern during the scanning period however are common and may result in unacceptable reductions in the scan efficiency, resulting in the need to abort the scan and reposition the acceptance window. This is a considerable drawback of any navigator technique relying on the definition of an acceptance window. The aim of this work is to investigate the application of a novel phase ordering technique to segmented (multiple kJ 2D acquisitions. The proposed technique does not require the setting of an acceptance window and is resistant to changes in the breathing pattern over the scan duration.