Abstract

Objective: The preoperative assessment represents one of the most important goals for improved understanding and surgical treatment of cardiac congenital anomalies. Digital imaging modalities such as magnetic resonance and electron beam computed tomography allow both, high spatial and temporal resolution and digital image processing including 3D-reconstruction. This study shows the usefulness of the reconstruction tools for the cardiac surgeon using various examples of congenital anomalies.

Methods: Preoperatively, patients with the diagnosis of atrial myxoma, atrial septal defect, subvalvular aortic stenosis, coronary anomalies, lipoma and double aortic arch were examined using magnetic resonance and electron beam computed tomography. The image data were transferred using the teleradiology system MEDICUS. The algorithms for digital image postprocessing included segmentation of cardiac structures and volumes by region growing and the 3D-reconstruction using a volume orientated raytracing algorithm.

Results: Every desired view of the 3D-reconstructed images could be achieved by 'taking' an appropriate point of view within the 3D-heart. Volumes and spatial extension (ASD, tumours) and localization of the great vessels (double aortic arch) could be determined. Infiltration of the aorta could be ruled out (lipoma). Also, mechanism of obstruction could be shown to be functional (subvalvular aortic stenosis): it could be attributed to the movement of the hypertrophied posterior papillary muscle (fig. 1).
 

Fig. 1: Two examples of three-dimensional reconstruction of electron beam CT data. A, Subvalvular aortic stenosis. Top vue on LVOT at enddiastole, after 250 ms and at endsystole B, visualized from 45° left. red, LV pink, LA gray, myocardium C, Retrocardial lipoma. Visualization of aorta (red) and lipoma (yellow) fron right, posterior, left and anterior positions. There is no aortic infiltration by the tumour.

Conclusions: The examples of various congenital anomalies demonstrate the benefit of 3D-reconstruction of digital image data for preoperative operation planning in cardiac surgery. Future improvements include the standardization of visualizations and the implementation of algorithms allowing online quantification within the three-dimensional reconstruction.