Dall'Armellina, Erica

Ferreira, Vanessa M

Piechnik, Stefan K

Robson, Matthew D

English

PubMed

Stefan K Piechnik

Erica Dall'Armellina

Vanessa M Ferreira

Matthew D Robson

Springer - Publisher Connector

POSTER PRESENTATION Open Access
Gaussian modelling for operator-independent
and threshold-free volumetric segmentation of
phase sensitive inversion recovery late
gadolinium enhanced images
Stefan K Piechnik*, Erica Dall’Armellina, Vanessa M Ferreira, Matthew D Robson
From 2011 SCMR/Euro CMR Joint Scientific Sessions
Nice, France. 3-6 February 2011
Aim
To objectively determine the volume of damage mea-
sured by late Gadolinium enhancement (LGE) using
threshold-free statistical fit to the distribution of image
intensities to reflect the tissue heterogeneity, presence of
noise and partial volume effects.
Background
Infarct size following STEMI carries prognostic signifi-
cance. Current CMR methods for measuring abnormal
myocardium are based on detecting pixels above a cer-
tain intensity threshold. This threshold is often defined
from a ROI as the mean plus a number (nSD) of stan-
dard deviations. This method assumes that the ROI is
“normal” and not affected by disease, and is sensitive
both to the choice of the ROI and the nSD multiplier.
Objective determination of the volume of damage on
LGE images may be desirable.
Material and methods
17 STEMI patients aged 56±9 years underwent 3T CMR
imaging within 48h post PCI using a phase-sensitive
late-gadolinium enhanced inversion recovery (PSIR)
method. Histograms of myocardial signal intensities
were calculated in each patient and fitted with a sum of
two Gaussians. We calculated the relative volume frac-
tion (VfGauss) as the area under the Gaussian distribu-
tion with the higher peak divided by the total area
under both peaks. For comparison, traditional threshold
segmentation was performed based on ROI placed in
remote myocardium and varying the threshold nSD
from 0 to 6, to determine the traditional volume fraction
(VfnSD).
Results
All LGE histograms were accurately described by just two
Gaussian components with a high coefficient of explained
variation R2=0.89-0.98 (Fig. 1). The lower Gaussian
curves were consistently centered near zero (SI = -16±38
scanner units[su]) and relatively narrow in distribution
(SD=39±12[su]). The Upper Gaussian had a greater
University of Oxford, Oxford, UK
Figure 1 LGE-PSIR pixel intensity histogram fitted with 2 gaussian
distributions.
Piechnik et al. Journal of Cardiovascular Magnetic Resonance 2011, 13(Suppl 1):P43
http://jcmr-online.com/content/13/S1/P43
© 2011 Piechnik et al; licensee 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.
signal intensity (182±89[su]), and a significantly wider
distribution (SD=81±34[su], p<0.001) than the Lower
Gaussian. Average VfGauss was 49±14%, which corre-
sponds best to the traditional Vf calculated by using a
threshold of about 1.0SD (Fig. 2 Arrow in Fig. 3). Tradi-
tional VfnSD strongly depended on nSD as expected, and
there was a significant difference between VfnSD and
VfGauss (p>0.05) except for nSD=0.8-1.8 (Fig. 3).
Conclusions
Gaussian modelling splits the signal intensity distribu-
tion consistently into two distinct components: the nar-
row “normal” peak centred about the null point and a
more heterogenous “abnormal” hyperintense pixel distri-
bution. This directly leads to lesion volume fractions
that are free from arbitrary choice of ROI or any thresh-
olds, which may improve the consistency and objectivity
of LGE image analysis.
Published: 2 February 2011
doi:10.1186/1532-429X-13-S1-P43
Cite this article as: Piechnik et al.: Gaussian modelling for operator-
independent and threshold-free volumetric segmentation of phase
sensitive inversion recovery late gadolinium enhanced images. Journal
of Cardiovascular Magnetic Resonance 2011 13(Suppl 1):P43.
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Figure 2 Volume fractions agree for nSD=1, but correlation is weak.
Figure 3 Impact of nSD on traditional volume fraction. VfGauss is a
constant.
Piechnik et al. Journal of Cardiovascular Magnetic Resonance 2011, 13(Suppl 1):P43
http://jcmr-online.com/content/13/S1/P43
Page 2 of 2


Gaussian modelling for operator-independent and threshold-free volumetric segmentation of phase sensitive inversion recovery late gadolinium enhanced images

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Journal of Cardiovascular Magnetic Resonance

Ferreira Vanessa M

Dall'Armellina Erica

Piechnik Stefan K

Robson Matthew D

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Gaussian modelling for operator-independent and threshold-free volumetric segmentation of phase sensitive inversion recovery late gadolinium enhanced images

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