Abstract
BackgroundThe associations between cardiovascular disease (CVD) risk factors and the biventricular geometry of the right ventricle (RV) and left ventricle (LV) have been difficult to assess, due to subtle and complex shape changes. We sought to quantify reference RV morphology as well as biventricular variations associated with common cardiovascular risk factors.MethodsA biventricular shape atlas was automatically constructed using contours and landmarks from 4329 UK Biobank cardiovascular magnetic resonance (CMR) studies. A subdivision surface geometric mesh was customized to the contours using a diffeomorphic registration algorithm, with automatic correction of slice shifts due to differences in breath-hold position. A reference sub-cohort was identified consisting of 630 participants with no CVD risk factors. Morphometric scores were computed using linear regression to quantify shape variations associated with four risk factors (high cholesterol, high blood pressure, obesity and smoking) and three disease factors (diabetes, previous myocardial infarction and angina).ResultsThe atlas construction led to an accurate representation of 3D shapes at end-diastole and end-systole, with acceptable fitting errors between surfaces and contours (average error less than 1.5 mm). Atlas shape features had stronger associations than traditional mass and volume measures for all factors (p < 0.005 for each). High blood pressure was associated with outward displacement of the LV free walls, but inward displacement of the RV free wall and thickening of the septum. Smoking was associated with a rounder RV with inward displacement of the RV free wall and increased relative wall thickness.ConclusionMorphometric relationships between biventricular shape and cardiovascular risk factors in a large cohort show complex interactions between RV and LV morphology. These can be quantified by z-scores, which can be used to study the morphological correlates of disease.
Highlights
The associations between cardiovascular disease (CVD) risk factors and the biventricular geometry of the right ventricle (RV) and left ventricle (LV) have been difficult to assess, due to subtle and complex shape changes
We developed an automated framework to customize a 3D subdivision surface mesh to contour and landmark positions manually defined at end-diastole (ED) and end-systole (ES) in over 4000 participants of the UK Biobank cardiovascular magnetic resonance (CMR) imaging extension
Patient-specific biventricular mesh The biventricular mesh template was successfully customized to all cases using the fully automatic process (Fig. 2)
Summary
The associations between cardiovascular disease (CVD) risk factors and the biventricular geometry of the right ventricle (RV) and left ventricle (LV) have been difficult to assess, due to subtle and complex shape changes. Atlas-based analysis can provide detailed information on shape variations and their relationships with disease processes. These methods have enabled robust and precise quantification of relationships between LV shape and risk factors in the asymptomatic population [9, 10], and remodeling after myocardial infarction [11]. Changes in RV geometry and function are important in many cardiovascular diseases [14,15,16,17] but are less well understood due to the complex shape of the chamber
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