Determining Epicardial Surface Motion Using Elastic Registration: Towards Virtual Reality Guidance of Minimally Invasive Cardiac Interventions

Abstract

Abstract.Minimally invasive cardiac surgery is performed on the beating heart, through inter-costal ports. The two major limitations of these procedures are: selecting port locations for optimal target coverage (based on chest x-rays and angiograms), and navigating surgical tools through a dynamic and confined environment using a 2D endoscope. To supplement the current surgery planning and guidance strategies, we continue developing VCSP -a virtual reality, patient-specific, thoracic cavity model derived from 3D pre-procedural images. In this work, we apply elastic image registration to 4D images of the heart to model the epicardial surface over the cardiac cycle. We validated our registration algorithm on CT images of a dynamic cardiac phantom and of normal canine hearts, and found the error to be 1.14 ± 0.31 mm and 0.61 ± 0.12 mm, respectively. We believe this method of modeling the epicardial surface is sufficiently accurate to be applied in cardiac surgery planning and guidance.

Mapping Template Heart Models to Patient Data Using Image Registration

“…We also plan to perform validation studies on excised hearts, which can easily be segmented if scanned in air, and then surrounded by tissue-mimicking materials to model the heart surroundings in-vivo. Furthermore, we will combine this work and our previous approach [9] to investigate the effects of template registration error on model dynamics, to fully characterize the accuracy of our patient-specific, dynamic models of the heart.…”

“…(1.5 3 mm 3 voxels). The signal-to-noise ratio (SNR) in the higher resolution image was enhanced by registering the four adjacent image frames of the complete 4D data to the image at ED using the algorithm described in [9], and by averaging the resulting five images. This specialized image is a part of a separate project aimed at generating a dynamic cardiac MR dataset with high resolution and high SNR [10].…”

“…We perform validation experiments on various MR and CT images, with manual segmentation of the target images acting as the gold standard. Following customization, any given model can be animated using the complete 4D data, as described in our previous work [9]. The final, patient-specific, dynamic model can then be easily integrated with VCSP.…”

A High Resolution Dynamic Heart Model Based on Averaged MRI Data

“…After correcting for breath-hold misalignments, the SNR was improved by a combination of image registration and image intensity averaging. An elastic image registration algorithm developed in our laboratory [9] was used for this purpose. The acquisition of multiple MRI volumes of the heart throughout the cardiac cycle allows unique opportunities when using the averaging process to improve SNR.…”

The implementation of an integrated computer‐assisted system for minimally invasive cardiac surgery

“…On the other hand, the entire traditional minimally invasive cardiac surgery procedure is guided solely by a 2D video thoracoscope, which only has a small field of view (10). It lacks real-time 3D guidance, which leads to the result that the surgeon can not locate the thoracoscope and surgical instruments accurately and establish the relative positions between the thoracoscope, the surgical instruments and the patient's anatomical structures.…”