Coronary artery imaging in a 0.5-Tesla scanner: Implementation of real-time, navigator echo-controlled segmented k-space FLASH and interleaved-spiral sequences

• Published in: Magnetic resonance in medicine Vol. 41; no. 2; pp. 392 - 399
• Main Authors: Keegan, J., Gatehouse, P.D., Taylor, A.M., Yang, G.Z., Jhooti, P., Firmin, D.N.
• Format: Journal Article
• Language: English
• Published: New York John Wiley & Sons, Inc 01.02.1999; Williams & Wilkins
• Subjects: Adult; Biological and medical sciences; coronary angiography; Coronary Vessels - anatomy & histology; fast low-angle shot sequences; Humans; interleaved-spiral sequences; Investigative techniques, diagnostic techniques (general aspects); Magnetic Resonance Angiography - instrumentation; Magnetic Resonance Angiography - methods; Medical sciences; navigator echo; Radiodiagnosis. Nmr imagery. Nmr spectrometry; Respiration; respiratory monitoring; Respiratory system; Time resolution; Angiography; Coronary artery; Circulatory system; Respiration; Real time; Nuclear magnetic resonance imaging; Spatial resolution; Monitoring; Optimization; Signal to noise ratio
• ISSN: 0740-3194; 1522-2594
• DOI: 10.1002/(SICI)1522-2594(199902)41:2<392::AID-MRM25>3.0.CO;2-Q

Coronary angiography techniques have been implemented on a 0.5‐Tesla scanner with a view to performing coronary artery imaging. Slice‐followed, segmented k‐space FLASH sequences and interleaved‐spiral sequences have been employed with acquisitions under real‐time navigator echo control with patient feed back, enabling poor signal‐to‐noise levels to be overcome by averaging data acquired over multiple, variable‐length, reproducible breath holds. Good‐quality, millimetre‐resolution coronary images were obtained in ten normal subjects with both techniques. The mean percent of data segments or interleaves acquired with the navigator echo within the 5‐mm diaphragm acceptance window was 57% [standard deviation (S.D.), 11%; range, 38–85%], and the average image‐acquisition times were 123 ± 22 sec and 71 ± 14 sec for segmented FLASH and interleaved‐spiral imaging, respectively. In addition to shorter acquisition times, the interleaved‐spiral sequence has superior temporal resolution, allowing the acquisition of limited, multislice data sets. However, the sequence is particularly sensitive to the off‐resonance effects of residual epicardial fat surrounding the artery and to field nonuniformities, both of which lead to image blurring and, unlike segmented FLASH acquisitions (which are very robust), the spiral data sets generally require postprocessing. Magn Reson Med 41:392–399, 1999. © 1999 Wiley‐Liss, Inc.