Skip to content

Advertisement

  • Poster presentation
  • Open Access

Synthetic LGE derived from cardiac T1 mapping for simultaneous assessment of focal and diffuse cardiac fibrosis

  • 1,
  • 1,
  • 1,
  • 2,
  • 2 and
  • 1
Journal of Cardiovascular Magnetic Resonance201416 (Suppl 1) :P362

https://doi.org/10.1186/1532-429X-16-S1-P362

  • Published:

Keywords

  • Contrast Ratio
  • Normal Myocardium
  • Myocardial Scarring
  • Simultaneous Assessment
  • Diffuse Fibrosis

Background

While late gadolinium enhanced (LGE) MRI is the gold standard for detection of focal myocardial scarring [1], it is less effective than cardiac T1 mapping (ECV) for detection of diffuse fibrosis. LGE, in principle, can be synthesized from cardiac T1 maps. We sought to derive synthetic LGE images from saturation-recovery based cardiac T1 maps for simultaneous assessment of focal and diffuse cardiac fibrosis.

Methods

We imaged 6 mongrel dogs with lesions created by RF ablation on a 3T MRI system (Verio, Siemens), using arrhythmia-insensitive-rapid (AIR) cardiac T1 mapping [2] and standard LGE MRI during equilibrium of Gd-BOPTA (slow infusion at 0.002 mmol/kg/min), in order to compare standard and synthetic LGE images acquired at identical concentration of Gd-BOPTA. Both LGE MRI and cardiac T1 mapping were acquired with identical spatial resolution = 1.4×1.4×7 mm. After calculating the AIR cardiac T1 maps, as previously described[2], a synthetic LGE image was subsequently synthesized using the Bloch equation describing an ideal inversion recovery: Mz = 1 - 2*exp(-TI/T1), where Mz is the longitudinal magnetization, inversion time (TI) to null the normal myocardium was calculated by rearranging the above equation as TI = T1M × log(2), where T1M is the mean T1 of normal myocardium. For quantitative analysis, we calculated the contrast ratio, as defined as the signal difference (e.g., lesion-myocardium) divided by lesion (see Table 1). Same analysis was performed for the blood-myocardium pair. This analysis enabled us to compare standard and synthetic LGE data sets with different intensity scales. Pair-wise t-test was used to compare the two groups (standard vs. synthetic LGE).
Table 1

Summary of contrast ratio of lesion-myocardium and blood-myocardium pairs.

Tissue Pair

Standard LGE (%)

Synthetic LGE (%)

p-value

Percent Change (%)

Lesion vs. Myocardium

89.8 ± 4.2

96.1 ± 2.2

< 0.001

7.0

Blood vs. Myocardium

88.1 ± 4.8

95.9 ± 2.4

< 0.001

8.9

Results

Our pooled data contained 21 short-axis planes with different RF lesions. Figure 1 shows representative standard and synthetic LGE images with a lesion. The two LGE images showed comparable image quality. As summarized in Table 1, synthetic LGE yielded higher (p < 0.001) contrast ratio of the lesion-myocardium and blood-myocardium pairs than standard LGE, but the magnitude of the differences was less than 10%.
Figure 1
Figure 1

Comparison (left) standard LGE with (middle) synthetic LGE derived from (right) T 1 map. Red arrows point to RF ablation lesion created hours before with a catheter.

Conclusions

We propose a new approach to simultaneously assess focal and diffuse cardiac fibrosis using cardiac T1 mapping, with no need for separate acquisition of standard LGE images. This approach is also compatible with inversion-recovery based cardiac T1 mapping methods. Synthetic LGE derived from T1 mapping may be particularly useful for infarct size and area at risk calculations, because it is inherently insensitive to signal variation due to confounders such as RF excitation and receive inhomogeneities.

Funding

Ben B. and Iris M. Margolis Foundation.

Authors’ Affiliations

(1)
UCAIR, Radiology, University of Utah, Salt Lake City, Utah, USA
(2)
Division of Cardiology, Internal Medicine, University of Utah, Salt Lake City, Utah, USA

References

  1. Kim RJ, et al: Circulation. 1999, 100: 1992-2002. 10.1161/01.CIR.100.19.1992.View ArticlePubMedGoogle Scholar
  2. Fitts M, et al: MRM. 2012, DOI: 10.1002/mrm.24586Google Scholar

Copyright

© Hong 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.

Advertisement