Online Heart Model Creation for Magnetocardiographic Measurements

We have developed an online system for creating patient specific heart models for Magnetocardiographic measurements (MCG). The heart model is created from fluoroscopy images and ultrasound measurements. Because the images are taken on the same operating table as MCG,the patient in not moved between the measurements. The objective is to create a 3D heart model corresponding to the patient's geometry during the MCG session. The epicardium is segmented manually from two orthogonal digital fluoroscopy images. Then an a priori 3D model is deformed to these outlines. The model is a mean generated from segmented Magnetic Resonance (MR) datasets taken from 16 subjects. The model includes the epicardium, the ventricles and the atria. Thereafter, several measurements are defined from ultrasound images and the model is further refined to match these measurements by deforming it locally. Finally,the model is attached to the MCG coordinate system with a grid of markers that are visible in the fluoroscopy images. The system is capable of producing relatively accurate heart models in a matter of minutes on a common PC. In our approach, expensive and time-consuming MR imaging is not required. In an ongoing clinical validation the best 3D accuracy achievable by a skilled cardiologist using our online model is compared using MR images.