- Poster presentation
- Open Access
- Published:
Transmurality mapping of left ventricular scar: impact of spatial resoluton
Journal of Cardiovascular Magnetic Resonance volume 13, Article number: P163 (2011)
Purpose
To generate scar transmurality maps, to study the impact of spatial resolution on these maps.
Introduction
Left ventricular (LV) scar is associated with ventricular tachycardia (VT), related to regions of slow conduction. Endocardial LV voltage maps reveal regions of low voltage near the site of VT origin, corresponding to myocardial fiber bundles trapped in areas of extensive fibrosis. Scar transmurality (i.e. the percent of myocardial wall thickness which is scarred, measured in 6-12 sectors around the LV myocardium) is an indicator of myocardial viability after reperfusion (1). Intermediate infarct transmurality has been correlated with non-ischemic VT (2). Furthermore, lower voltages are found in regions of more transmural scarring (3). We have expanded the transmurality concept to generate LGE transmurality maps of the LV.
Methods
3D LGE studies (4) from 8 patients with prior myocardial infarction were obtained on a 1.5T Achieva CMR system (Philips Healthcare, Best, NL). Imaging parameters were: 0.2mmol/kg Gd-DPTA, inversion recovery gradient echo sequence with fat-saturation, with ECG and NAV-gating: TR/TE/θ=5.6ms/2.6ms/25°, 4-6 minutes/scan. Figure 1 illustrates the processing to generate 3D endocardial transmurality maps, using original high (1.3 x 1.3 x 4mm3) and processed lower (2 x 2 x 8mm3) resolution images. All processing was performed in Matlab (v7.1, Mathworks, Natick, MA), with visualization using Paraview (v3.8 Kitware, Clifton Park, NY). Bipolar voltage maps, obtained by electrophysiological (EP) catheter mapping, were compared with transmurality maps visually. High and low resolution transmurality maps were compared visually. Average transmurality of scarred sectors was compared, using a paired t-test.
A) Starting with a short axis LGE image (A), scar and myocardium are segmented (B). Scar transmurality is calculated in 100 sectors in each slice (C), which provides an endocardial representation of LV scar (D). E) Scar transmurality map (1= 100%) transmural) is displayed in 3D. F) The corresponding bipolar voltage maps shows strong similarity (scale=0.5/0.05mV).
Results
In 4 subjects with voltage maps, regions with greater transmurality had lower voltage electrograms (Fig 1E,F). Low resolution data produced greater transmurality by visual assessment in 88% of subjects (Figure 2). Quantitatively, the average scar transmurality in scarred sectors for high and low resolution transmurality maps were 30 ±4% and 37±5%, p=0.001, respectively.
Conclusions
We present a novel method for displaying transmurality of enhancement from 3D LGE images. The relationship between transmurality maps and voltage must be further in explored in a larger cohort, using quantitative means. Maps derived from higher resolution images demonstrated less transmural scar. Since scar that encompasses surviving myocardium (i.e. almost transmural scar) may be related to VT genesis, high resolution transmurality mapping might be useful in detecting the true arrhythmogenic substrate.
References
Kim RJ: NEJM. 2001
Nazarian S: Circ. 2005
Wolf T, et al: JACC. 2001
Peters DC, et al: JMRI. 2009
Author information
Authors and Affiliations
Rights and permissions
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.
About this article
Cite this article
Peters, D.C., Liu, F., Tan, A. et al. Transmurality mapping of left ventricular scar: impact of spatial resoluton. J Cardiovasc Magn Reson 13 (Suppl 1), P163 (2011). https://doi.org/10.1186/1532-429X-13-S1-P163
Published:
DOI: https://doi.org/10.1186/1532-429X-13-S1-P163
Keywords
- Ventricular Tachycardia
- Arrhythmogenic Substrate
- Bipolar Voltage
- Myocardial Wall Thickness
- Scar Transmurality