Improving the stratification power of cardiac ventricular shape

Revealing differences in anatomical remodelling of the systemic right ventricle

E.Zacur1, J.Wong2, R.Razavi2, T.Geva3, G.Greil2, P.Lamata1

1 Dept. Biomedical Engineering, Kings College London, UK2 Div. Imaging Sciences, Kings College London, London, UK3 Boston Childrens Hospital, Harvard Medical School, USA

Take home messagesModels to reveal biomarkers

Shape biomarkerModel: smooth ellipsoidUnveil differences in development

OverviewHLHS: the clinical problem and hypothesis

Coping with data

Revealing growth differences

How good is the picture?

HLHS

Hypoplastic Left Heart Syndrome (I)

4 in 10.000 births

Hypoplastic Left Heart Syndrome (II)Challenges:Complex surgery - different schoolsSmall numbers many factorsOpportunity: huge impact for life

Shunts: two schools

modified Blalock-Taussig (MBT)right ventricle-to-pulmonary artery (RVPA)

Impact of shunt choice?Outcome (transplantation free) [1]:Early outcome: RVPA betterMid outcome (32 months): equal

Hypothesis: scar in RVPA introduces an adverse remodelling (growth) and impaired RV function as compared to MBT.[1] Frommelt et al (2014). "Impact of initial shunt type on cardiac size and function in children with single right ventricle anomalies before the Fontan procedure: the Single Ventricle Reconstruction Extension Trial", JACC 64(19):2026-2035.

Computational Anatomy is able to reveal differences in RV growth caused by a choice of shunt technique.

clinicalDataModel fittingPrincipal Component Analysis

Model: ellipsoidMinimise acquisition / segmentation artefacts

Mesh personalization[2] Lamata P et al (2011), An accurate, fast and robust method to generate patient-specific cubic Hermite meshes. Med Image Anal. 15(6):801-13[3] Lamata P et al (2014), An automatic service for the personalization of ventricular cardiac meshes. J R Soc Interface. 11(91):20131023.

Common shape changes?Shape variation due to:Errors, artefactsPhysiological causesDecompose shape in orthogonal componentsReduce dimensionalityGet the salient modes

M

1

2

3

4

5

113

128

Revealing growth differences

Mean

34

Mode 1

Modes 2, 3, 4

RVPA shunt

MBT shunt

Mode 1

Stage I (all) vs MBT

Stage I (all) vs RVPA

How good is the picture?

Better than traditionalDifferences never revealed beforeRisk: black boxMitigation plan: map of regional changes

Function correlates with shape (remodelling) Impaired contraction in RVPA [4]

[4] Wong et al (2015). "Using cardiac magnetic resonance and computational modelling to assess the systemic right ventricle following different Norwood procedures: a dual centre study", J Card Mag Res, 17(Suppl 1):M12.

Still a blurry pictureData issues: short axis stack, etcProcessing issues. Fitting error / LV length = 1.43/78 mmAdult LV: 1.28/95 mm

Take home messagesModels to reveal biomarkers

Shape biomarkerModel: smooth ellipsoidUnveil differences in development

Acknowledgements