Engineering on Anatomy to Avoid the Necessity of Invasive Imaging in Medical 3D Printing: Examples from Pediatric Cardiology

Abstract Background: 3D printed models of pediatric hearts with congenital heart disease (CHD) have been proven helpful in simulation training of diagnostic and interventional catheterization. However, anatomically accurate 3D printed models are traditionally based on real 2D scans of patients requiring specific imaging techniques, i.e. computer tomography (CT) or magnetic resonance imaging (MRI). In small children both imaging technologies often require deep sedation and involve radiation (CT) being of special impact in this population. Hence, cardiac image data acquired by these invasive technologies is rare in pediatrics where minimization of radiation and sedation is key. Therefore, an alternative solution to create variant 3D printed heart models for teaching and hands-on training has been established. Methods: In this study different methods utilizing image processing and computer aided design (software: Mimics Innovation Suite, Materialise NV) have been established to overcome this shortage and to allow unlimited variations of 3D heart models based on a single patient scan. Patient-specific models based on a CT or MRI image stack were modified by performing virtual engineering on the original shape and structure of the heart. Thereby, 3D hearts including several pathological findings were created and CHD training models were adapted to training level and aims of hands-on classes, particularly for invasive procedures such as interventional cardiology. Results: By changing the shape and structure of the 3D anatomy various training models were created of which four examples are presented in this paper: 1. a heart model with a patent ductus arteriosus (PDA) augmented by perimembranous ventricular septal defect (pmVSD) and muscular ventricular septal defect (mVSD), 2. a model of solely the right heart with pulmonary valve stenosis (PS) augmented by the left heart and myocardium, 3. a series of heart models with atrial septal defect (ASD) showing the hemodynamic effect on the right atrial and ventricular wall, 4. a model of solely the left heart with isthmus stenosis augmented with an engineered aortic valve. All presented models have been successfully utilized in teaching or hands-on training courses. Conclusions: It has been demonstrated that structure and shape of 3D heart models can be modified virtually by engineering on anatomy. Therefore, anatomical variants can be created without the necessity for real, patient-specific CT or MRI imaging. Further investigations are required to evaluate the resemblance of reality of non-patient-specific 3D models and to prove the effectiveness of training using these designed heart models.