Volume 16 Supplement 1
Infarct size by SS-SSFP vs. IR-GRE: influence of imaging time after contrast administration and infarct age, and implications for clinical trials
© McAlindon et al.; licensee BioMed Central Ltd. 2014
Published: 16 January 2014
Myocardial late gadolinium enhancement (LGE) imaging is conventionally acquired using a gradient-echo inversion recovery (IR-GRE) sequence 15-20 min after contrast administration. However, this method can be limited by poor breath holding or arrhythmias. Free-breathing single shot steady state free precession (SS-SSFP) sequence is an alternative LGE imaging technique which can overcome some of the IR-GRE limitations but at the expense of lower resolution. The ideal imaging timing for LGE SS-SSFP, and whether it can be used interchangeably with IR-GRE has not yet been established. The aim of our study was to investigate acute and chronic infarct size: 1) Comparing LGE by SS-SSFP vs. IR-GRE at 15 min. 2) Comparing LGE SS-SSFP imaging at 5 vs. 10 vs. 15 min after contrast administration vs. IR-GRE at 15 min.
36 patients were prospectively recruited for CMR day 2 and 3 months following reperfused STEMI. IR-GRE images were acquired 15 minutes following gadolinium contrast administration (Gadovist 0.1 mmol/kg). Free-breathing SS-SSFP images were obtained 5, 10 and 15 min following contrast. LGE was calculated and infarct size was expressed in grams. Agreement between the 2 sequences was assessed by the Bland Altman method. Differences between time following contrast for both acute and chronic infarct size were assessed using paired t-tests. All patients provided informed written consent and the study was approved by the regional ethics committee.
LGE Imaging by SS-SSFP vs. IR-GRE 15 min after contrast administration.
p = 0.006
p = 0.54
LGE Imaging by SS-SSFP at multiple time points after contrast administration.
5 vs 10 min p = 0.13,
10 vs 15 min p = 0.02,
5 vs 15 min p = 0.01
5 vs 10 min p = 0.09,
10 vs 15 min p = 0.35,
5 vs 15 min p = 0.04
Our study demonstrates both acute and chronic infarct size with SS-SSFP changes significantly between 5 vs. 10 vs. 15 min, demonstrating that the time of imaging after contrast administration is important for this sequence too. The ideal timing for imaging acute and chronic infarct size by SS-SSFP and IR-GRE are different. In particular, when imaging at 15 min after contrast, LGE by SS-SSFP can underestimate acute infarct size. In chronic infarctions time after contrast injection for LGE by SS-SSFP seems less critical but infarct size at 15 min best correlated with LGE by IR-GRE. LGE by SS-SSP offers a valid alternative in clinical practice for the (visual) assessment of myocardial infarction but in clinical trials it should not be used interchangeably with LGE IR-GRE
This work was funded by the NIHR Bristol 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. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.