- Poster presentation
- Open Access
- Published:
Performance of automated ECV maps versus conventionally calculated ECV
Journal of Cardiovascular Magnetic Resonance volume 17, Article number: P56 (2015)
Background
The extracellular volume fraction (ECV) is a surrogate marker for diffuse myocardial fibrosis. ECV is calculated from pre- and post-contrast T1 maps and corrected for hematocrit (Hct). Current workflows are cumbersome, but an automated ECV map tool simplifies this and could promote adoption into routine clinical practice. We assessed the performance of automated ECV maps versus conventional manual ECV quantification in a population of healthy volunteers using a Modified Look-Locker Inversion Recovery (MOLLI) technique.
Methods
45 healthy volunteers [mean age 43±12 years, 21 (47%) males] underwent CMR at 1.5T. with T1 mapping using MOLLI. MOLLI T1 maps with motion correction [pre-contrast 5s(3s)3s; post-contrast 4s(1s)3s(1s)2s] were acquired in the 4 chamber (4Ch) and a mid-ventricular short-axis (SA) pre and 15 minutes post contrast (Dotarem 0.1 mmol/kg). A region of interest was manually drawn on the pre-contrast T1 map and a) exported to the post contrast T1 map and b) exported to the ECV map (Figure 1). The ECV map was automatically generated from the source images of the pre and post contrast T1 maps with re-MOCOing and calibrated by blood hematocrit (Kellman JCMR 2012, 14:63). For the manual method, the averages of the ROIs were used in the ECV equation: ECV= (Δ[1/T1myo] / Δ[1/T1blood]) * [1-hematocrit]). For the ECV map, the ROI pixel average was the average ECV.
Results
ECV maps resulted in a higher ECV in the SA than in the 4Ch (27.0±3.5% vs 25.9±2.8%; p=0.007); this difference did not reach significance in the manual technique (27.1±2.8% vs 26.6±2.9%; p=0.075).
In the 4Ch, ECV was higher using the manual rather than the automatic technique (26.6±2.9% vs 25.9±2.8%, p<0.001). There was excellent correlation between both techniques (R=0.92; p<0.001). Bland Altman analysis revealed minimal bias and no significant variability (bias -0.6%, 95% CI ±2.2%) (Fig. 2B).
In the mid-SA, ECV was not significantly different between manual and automatic technique (27.1±2.8% vs 27.0±3.5%; p=0.546) with excellent correlation (R= 0.89; p<0.001). Bland Altman analysis revealed no bias or variability (bias -0.15, 95% CI ±3.2%) (Fig. 2A).
Conclusions
Automated ECV maps significantly improve workflow and show good agreement with the manual method. Application in the short axis showed no difference to the manual approach, but result in slightly higher ECV with more variability than in the 4 chamber. Further validation in health and disease with wider ECV ranges is needed.
Funding
TAT and MF are supported by doctoral research fellowships by the National Institute of Health Research and British Heart Foundation, respectively.
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/4.0), 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.
About this article
Cite this article
Rosmini, S., Treibel, T.A., Abdel-Gadir, A. et al. Performance of automated ECV maps versus conventionally calculated ECV. J Cardiovasc Magn Reson 17 (Suppl 1), P56 (2015). https://doi.org/10.1186/1532-429X-17-S1-P56
Published:
DOI: https://doi.org/10.1186/1532-429X-17-S1-P56
Keywords
- Bland Altman Analysis
- Automatic Technique
- Post Contrast
- Minute Post
- British Heart Foundation