Left Ventricular Morphology in Patients with Aortic Coarctation and Bicuspid Aortic Valve: Novel Insights from a Statistical Shape Modelling Framework

Background The functional implications of left ventricular (LV) morphological characterization in congenital heart disease (CHD) are not widely explored. This study qualitatively and quantitatively assessed LV shape associations with a) LV function and b) thoracic aortic morphology in patients with aortic coarctation (CoA) with/without bicuspid aortic valve (BAV). Methods A statistical shape modelling (SSM) framework was employed to analyse three-dimensional (3D) LV shapes from cardiac magnetic resonance (CMR) data in isolated CoA (n=25), CoA+BAV (n=30), isolated BAV (n=30), and age-matched healthy controls (n=25). Average 3D templates and deformations were computed. Correlations between shape data and CMR-derived morphometric parameters (i.e. sphericity, conicity) or global and apical strain values were assessed to elucidate possible functional implications. The relationship between LV shape features and arch architecture was also explored. Results The LV template was shorter and more spherical in CoA patient and LV sphericity was associated (p≤0.04) with lower global longitudinal, radial and circumferential strain, irrespective of the presence of aortic stenosis and/or regurgitation. Conversely, LV strain was not associated with arch architecture. Conclusions Differences in LV morphology were observed between CoA and BAV patients. Increasing LV sphericity was associated with reduced strain, independent of aortic arch architecture and functional aortic valve disease.

Statistical shape modelling to analyse the talus in paediatric clubfoot

One fifth of idiopathic clubfoot deformities cannot be fully corrected by Serial Ponseti casting and deformity recurs in 20%–30% of cases. To avoid x-ray exposure, the joints with largely unossified bones are diagnosed with magnetic resonance images (MRI). Typically, geometric measurements are made in the MRI planes; however, this method is inaccurate compared to measurements on three-dimensional (3D) models of the joint. More accurate measurements using the 3D bone shapes may be better at identifying differences between groups; and therefore, improve diagnosis. The entire set of shape features from MRI can be analysed simultaneously through statistical shape modelling (SSM) which assesses bone morphology of clubfoot in a more sensitive way. A method for SSM of the talus is developed in this study and the shape of the normal talus is compared with the one in clubfeet with residual deformity through both geometric measurements and SSM. Significant differences between two groups were found by both methods; and therefore, might contribute to improve diagnosis of clubfoot.