Atlas-Based Ventricular Shape Analysis for Understanding Congenital Heart Disease

Abstract

Congenital heart disease is associated with abnormal ventricular shape that can affect wall mechanics and may be predictive of long-term adverse outcomes. Atlas-based parametric shape analysis was used to analyze ventricular geometries of eight adolescent or adult single-ventricle CHD patients with tricuspid atresia and Fontans. These patients were compared with an "atlas" of non-congenital asymptomatic volunteers, resulting in a set of z-scores which quantify deviations from the control population distribution on a patient-by-patient basis. We examined the potential of these scores to: (1) quantify abnormalities of ventricular geometry in single ventricle physiologies relative to the normal population; (2) comprehensively quantify wall motion in CHD patients; and (3) identify possible relationships between ventricular shape and wall motion that may reflect underlying functional defects or remodeling in CHD patients. CHD ventricular geometries at end-diastole and end-systole were individually compared with statistical shape properties of an asymptomatic population from the Cardiac Atlas Project. Shape analysis-derived model properties, and myocardial wall motions between end-diastole and end-systole, were compared with physician observations of clinical functional parameters. Relationships between altered shape and altered function were evaluated via correlations between atlas-based shape and wall motion scores. Atlas-based shape analysis identified a diverse set of specific quantifiable abnormalities in ventricular geometry or myocardial wall motion in all subjects. Moreover, this initial cohort displayed significant relationships between specific shape abnormalities such as increased ventricular sphericity and functional defects in myocardial deformation, such as decreased long-axis wall motion. These findings suggest that atlas-based ventricular shape analysis may be a useful new tool in the management of patients with CHD who are at risk of impaired ventricular wall mechanics and chamber remodeling.

Keywords: CHD; atlas; cardiac; shape analysis; single-ventricle.

Figure 1

Modeling tool for atlas-based ventricular shape modeling using cMRI.

Figure 2

The first five modes of asymptomatic shape variation at ED. Mean, −2SD, and +2SD shapes are shown to illustrate the geometric meaning of the modes.

Figure 3

The first five modes of asymptomatic shape variation at ES. Mean, −2SD, and +2SD shapes are shown to illustrate the geometric meaning of the modes.

Figure 4

The first five modes of variation in the wall motion between ED and ES. Mean, −2SD, and +2SD are shown to illustrate the physical meaning of the modes. Modes of variation in the displacement vectors are illustrated as an LV shape that describes the systolic deformation from the mean ED shape (shown as a gray wireframe).