Biomedical subjects

S Y James Chen

Publications and source records attributed to S Y James Chen.

4 recordsLinked to original sources

PubMed2004

Three-dimensional analysis of in vivo coronary stent--coronary artery interactions.

Stent implantation results in important three-dimensional (3D) changes in arterial geometry which may be associated with adverse events. Previous attempts to quantify these 3D changes have been limited by two-dimensional techniques. Using a 3D reconstruction technique, vessel curvatures at end-diastole (ED) and end-systole (ES) were measured before and after stent placement of 100 stents (3 stent cell designs, 6 stent types). After stenting, the mean curvature at ED and ES decreased by 22 and 21%, respectively, and represents a straightening effect on the treated vessel. This effect was proportional to the amount of baseline curvature as high vessel curvature predicted more profound vessel straightening. When analyzed by stent cell design, closed-cell stents resulted in more vessel straightening than other designs (open cell or modified slotted tubes). Stent implantation resulted in the transmission of shape changes to stent ends and generated hinge points or buckling. Stent implantation creates 3D changes in arterial geometry which can be quantified using a 3D reconstruction technique.

Blood Vessel Prosthesis Implantation↗

PubMed2003

Kinematic and deformation analysis of 4-D coronary arterial trees reconstructed from cine angiograms.

In the cardiovascular arena, percutaneous catheter-based interventional (i.e., therapeutic) procedures include a variety of coronary and other vascular system interventions. These procedures use two-dimensional (2-D) X-ray-based imaging as the sole or the major imaging modality for procedure guidance and quantification of key parameters. Coronary vascular curvilinearity is one key parameter that requires a four-dimensional (4-D) format, i.e., three-dimensional (3-D) anatomical representation that changes during the cardiac cycle. A new method has been developed for reconstruction and analysis of these patient-specific 4-D datasets utilizing routine cine angiograms. The proposed method consists of three major processes: 1) reconstruction of moving coronary arterial tree throughout the cardiac cycle; 2) establishment of temporal correspondence with smoothness constraints; and 3) kinematic and deformation analysis of the reconstructed 3-D moving coronary arterial trees throughout the cardiac cycle.

Algorithms↗

PubMed2003

Stress analysis using anatomically realistic coronary tree.

Plaque rupture with superimposed thrombosis is the main cause of the acute coronary syndromes of unstable angina, myocardial infarction, and sudden death. Endothelial disruption leading to plaque rupture may relate to mechanical fatigue associated with cyclic flexion of plaques. A novel method is proposed to assess stress and strain distribution using the finite element (FE) analysis and in vivo patient-specific dynamic 3D coronary arterial tree reconstruction from cine angiographic images. The local stresses were calculated on the diseased arterial wall which was modeled as consisting of a central fibrotic cap subjected to the cyclic flexion from cardiac contraction. Various parameters characterizing the plaque were chosen including vessel diameter, percentage narrowing, and lesion length. According to the FEA simulations, the results show that the smaller vessel diameter, greater percentage narrowing, and/or larger lesion size may result in higher stress on the plaque cap, with the vessel diameter as the dominant factor.

Arteries↗

PubMed2002

Quantitative analysis of reconstructed 3-D coronary arterial tree and intracoronary devices.

Traditional quantitative coronary angiography is performed on two-dimensional (2-D) projection views. These views are chosen by the angiographer to minimize vessel overlap and foreshortening. With 2-D projection views that are acquired in this nonstandardized fashion, however, there is no way to know or estimate how much error occurs in the QCA process. Furthermore, coronary arteries possess a curvilinear shape and undergo a cyclical deformation due to their attachment to the myocardium. Therefore, it is necessary to obtain three-dimensional (3-D) information to best describe and quantify the dynamic curvilinear nature of the human coronary artery. Using a patient-specific 3-D coronary reconstruction algorithm and routine angiographic images, a new technique is proposed to describe: 1) the curvilinear nature of 3-D coronary arteries and intracoronary devices; 2) the magnitude of the arterial deformation caused by intracoronary devices and due to heart motion; and 3) optimal view(s) with respect to the desired "pathway" for delivering intracoronary devices.

Algorithms↗