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.
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