107 Small field of view black-blood imaging of the human heart using local excitation
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Meeting abstract
107 Small field of view black-blood imaging of the human heart using local excitation Khaled Z Abd-Elmoniem*, Evert-Jan Vonken and Matthias Stuber Address: Johns Hopkins University, Baltimore, USA * Corresponding author
from 11th Annual SCMR Scientific Sessions Los Angeles, CA, USA. 1–3 February 2008 Published: 22 October 2008 Journal of Cardiovascular Magnetic Resonance 2008, 10(Suppl 1):A8
doi:10.1186/1532-429X-10-S1-A8
Abstracts of the 11th Annual SCMR Scientific Sessions - 2008
Meeting abstracts – A single PDF containing all abstracts in this Supplement is available here. http://www.biomedcentral.com/content/pdf/1532-429X-10-S1-info.pdfThis abstract is available from: http://jcmr-online.com/content/10/S1/A8 © 2008 Abd-Elmoniem et al; licensee BioMed Central Ltd.
Introduction Black-blood-prepared fast spin-echo (FSE) imaging is a widely used technique for cardiovascular imaging. To avoid fold-over artifacts, a sufficiently large field of view (FOV) in fold-over direction has to be selected. Nevertheless, respiratory artifacts originating from the moving chest wall are commonly observed. While enlarging the FOV leads to an increase in scanning time, motion artifacts have a detrimental impact on image quality. To address these issues, limiting the FOV in fold-over direction using pre-pulses has been proposed [1,2]. While promising results have been obtained, additional prepulses are required and the quality of the suppression outside of the desired FOV is T1-dependent.
Purpose To develop, implement and test an MRI method that integrates local excitation for small-FOV imaging into the imaging part of an FSE sequence.
Methods Concept In conventional FSE imaging, a slice-selective 90° pulse is typically followed by a train of slice-selective 180° refocusing pulses. If the initial slice selective 90° pulse is replaced by a 2D-selective cylindrical excitation perpendicular to the imaging plane, the resultant signal will originate from a 'disc' located at the intersection between the 90° cylindrical pulse and the slice selective 180° pulses. Such local excitation enables small-FOV imaging without fold-over artifacts and avoids motion artifacts originating from structures outside of the 2D-selective pulse.
Implementation A 2D-selective 90° excitation was implemented as part of an FSE imaging sequence (Fig. 1) on a commercial 3 T Philips Achieva MRI system. Localization, angulations, and the diameter of the cylindrical excitation are prescribed on the graphical user interface of the system. Black-blood dual-inversion was combined with the modified FSE sequence. To suppress respiratory motion, a realtime navigator was combined with the local excitation technique. Phantom experiments Phantom measurements were obtained using conventional 2D FSE imaging (TR = 2 s, slice thickness = 4 mm, flip-angle = 90°, echo train length (ETL) = 12, TE = 13 ms, interecho spacing = 6.3 ms). This reference image without local excitation had a FOV of 380 mm and a matrix of 544 ×
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