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  • Open Access

MOLLI T1 mapping versus T2 W-SPAIR at 3T: myocardial area at risk measurements and the influence of microvascular obstruction

  • 1,
  • 1,
  • 2, 1,
  • 1,
  • 1,
  • 1,
  • 1,
  • 1 and
  • 1
Journal of Cardiovascular Magnetic Resonance201416 (Suppl 1) :O22

https://doi.org/10.1186/1532-429X-16-S1-O22

  • Published:

Keywords

  • Receiver Operator Characteristic
  • Acute Myocardial Infarction
  • Late Gadolinium Enhancement
  • STEMI Patient
  • Microvascular Obstruction

Background

Robust CMR imaging is required for the delineation of myocardial area at risk (AAR), so that the success of reperfusion therapies can be evaluated. In this work, we investigate the performance of T1 mapping in assessing AAR one week post-STEMI, and explore the effect of microvascular obstruction (MVO) on T1 relaxation times.

Methods

CMR imaging was conducted on a Philips 3T Achieva MRI scanner. T2W-weighted spectral attenuated inversion recovery (T2WW-SPAIR), modified look-locker inversion recovery (MOLLI) T1 mapping and late gadolinium enhancement (LGE) sequences were applied as short axis stacks in 10 healthy volunteers and 62 STEMI patients. Receiver operator characteristic (ROC) analysis was applied to calculate a cut-off T1 to to discriminate AAR from normal myocardium. The presence of LGE was used as the positive ROC test state, while healthy myocardium, as measured in volunteers, was used as the negative ROC test state. For comparison with T1 mapping, the AAR was also measured on T2WW images using a threshold signal intensity > 2SD greater than remote. The derived myocardial edema volumes and salvage indices were compared between MVO+ and MVO- groups.

Results

For T1 mapping, ROC analysis gave a significantly larger area-under-the-curve (AUC) as compared to T2WW-SPAIR for delineating myocardial edema (AUC = 0.89 vs 0.83, p = 0.009) as well as better sensitivity/specificity (83/83% vs 73/73%). Neither method was significantly affected by the presence of MVO. The calculated ROC cut-off for T1 mapping was 1243 ms, and this gave a significantly larger AAR than that measured with a T2W-SPAIR 2SD threshold (p = 0.006). Using the T1 mapping cut-off, patients with MVO had a significantly larger AAR and a poorer salvage index than patients without MVO (p < 0.05 for both). The AAR measured using each of the two methods is illustrated in Figure 1, and AAR and salvage index measurements are shown in Table 1.
Figure 1
Figure 1

The area at risk as delineated by (A) MOLLI T 1 mapping and (B) T 2 -weighted SPAIR.

Table 1

Area at Risk and Salvage Index

Method

All Patients

MVO+

MVO-

T2W-SPAIR 2SD AAR Volume (%)

40 (16)

28 (11)†

48 (13)†

T1 Mapping ROC AAR Volume (%)

55 (7)*

57 (7)*

53 (8)

Salvage Index by T2W-SPAIR 2SD

0.66 (0.23)

0.75 (0.17)

0.59 (0.25)

Salvage Index by T1 Mapping ROC

0.73 (0.22)

0.89 (0.08)*†

0.63 (0.22)†

Area at risk volume and salvage index measured using T2W-SPAIR and T1 mapping - * denotes a statistically significant difference between T1 mapping and T2W-SPAIR techniques; † denotes a statistically significant difference between MVO+ and MVO- groups (p values in the text). Data is presented as mean (SD).

Conclusions

T1 mapping at 3T can be used to automatically delineate AAR one week post-STEMI. It delimits larger volumes of edema and demonstrates less variability than T2WW-SPAIR. MVO did not significantly affect the discriminatory power of either of these techniques at seven days post-STEMI.

Funding

This study was supported by a Medical Research Council (UK) grant, as a sub-study of Nitrites in Acute Myocardial Infarction, NCT01388504.

Authors’ Affiliations

(1)
University of Aberdeen, Aberdeen, UK
(2)
The Queen Elizabeth Hospital, Adelaide, South Australia, Australia

Copyright

© Cameron et al.; licensee BioMed Central Ltd. 2014

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.

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