Volume 14 Supplement 1
Field-of-view zoom during a single-shot short-axis image for cardiac contraction correction
© Gatehouse and Firmin; licensee BioMed Central Ltd. 2012
Published: 1 February 2012
Evaluate a new method correcting for cardiac contraction during each single-shot image.
Cardiac motion during a single-shot image causes blurring along the phase-encode axis and dark rim artefact (1). We attempt to correct for myocardial contraction during short-axis single-shot acquisition, to optimise subendocardial myocardium.
A myocardial perfusion sequence (balanced SSFP) was modified to vary field-of-view and in-plane offsets during each single-shot rawdata acquisition to “zoom” in [or out] following myocardial contraction [filling]. FOV-zoom varied linearly during raw data acquisition, and for each phase-encode line p scaled the FOV and in-plane offsets by factor Sc(p) = 1 + ((Db - De)/De) x (p-N/2)/N where Db and De were LV short-axis diameter at the begin and end of the single-shot scan, and N was the total phase encode lines (96) for each single-shot. The diameters Db and De were measured using a short-axis cine pre-scan in the same slice. The sequence acquired 300x225mm FOV (2.3x2.3x6mm). For in-vitro tests, a conical cup of fluid was imaged in circular cross-section. The slice was shifted along the cone during acquisition, so that the apparently changing diameter modelled contraction of a short-axis LV. In healthy volunteers without contrast agent, T2-preparation was used for endocardial image contrast (1). Each 200ms perfusion image was acquired during ventricular contraction, starting 80ms after the R-wave, repeated with and without FOV-zoom.
Some local improvement of subendocardial clarity by FOV-zoom was seen, and ghosting from other tissues was not problematic. However, reliable implementation of this idea remains a challenge.
NIHR Cardiovascular Biomedical Research Unit.
This article is published under license to BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.