Comparative analysis of stent design and vessel tissue performance through the novel application of OCT imaging and kinematic analysis
Mentor: Dr. John Karanian
Director of FDA Center for Cardiovascular and Interventional Therapeutics
Mr. Charles Ashcraft
Glenelg High School
This project investigated the implantation of OCT scanning modalities in the treatment of cardiovascular vessel failure through the implantation of stent devices. By applying advanced imaging technology in the scanning of vasculature, a far greater degree of detail may be reached, allowing unprecedented incite and understanding to the various facets of vessel change and failure. Focusing on the application of OCT imaging technology in both reevaluating old data and finding new intravascular trends, this study aimed to clarify and gain understanding of the effectiveness of both new and old imaging technology in the analysis of vessel failure. Additionally, highlighting the various forms of motion deformation under which vessels change and shift, analysis of vasculature through the application of OCT technology represents a crucial component in understanding how vessels move and react to changes in their physical environment. The application of computer modeling also remains a significant step in visualizing the internal structure and orientation of the subject, using manipulation of the scan in order to most appropriately understand vessel behavior. Further research, including the direct development of patient data specifically collected for the purpose of analyzing the effectiveness of OCT technology, is needed in order to gain a more detailed understanding of the protocols through which the technology is applied and utilized within the current body of research.
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OCT technology utilizes the development of new higher resolution imaging algorithms and the application of near-infrared light in order to more effectively process images of biological tissue with unprecedented precision and accuracy.1 Representing an alternative to traditional methods such as magnetic resonance imaging (MRI) and intravascular ultrasound (IVUS), OCT technology is non-invasive by nature, delivering far more detailed images without the interference commonly felt by patients with the use of older imaging methods. Demonstrating a far greater degree of sensitivity, OCT technology also remains highly adaptable and retains the ability to reach magnification exceeding micrometer resolution. Applied primarily in the imaging of atherosclerotic change, OCT retains a profound ability in enabling physicians to distinguish between various forms of plaque formation.2
In addition to the precision of OCT, the technology also offers the ability to image internal vasculature in real time, without the need of contrast agents. As a result, changes in vessel characteristics over various ranges of motion, including length, elipticity, torque, and twist, can now be viewed at far more detailed levels, increasing the data available to researchers and their understanding of vascular kinematics.2 Understanding the various factors contributing to the deformation and change of vessel characteristics remains to be a prominent factor in developing intravascular therapeutics for the treatment of vessel failure. By gaining the ability to precisely track the change of vessel lumen over time as well as the position of stents within the vessel, new devices may be developed that more efficiently handle the restraints of various biological environments (femoral artery, carotid artery, etc).
In addition to imaging shifts in vasculature and forms of deformation, OCT technology also offers the ability to investigate the neointimal tissue surrounding intravascular structures, which compose a key role in the protection of the vessel through the elimination of inflammation.3 Although some issues exist in regards to the development of surgical protocols accounting for interferences such as muscular contractions (such as the heart) and blood flow, some experiments have been completed regarding the use of saline solution as a solution to providing a optically preferable environment under which OCT scanning modalities may operate. Overall, while OCT holds great promise in delivering unrivaled imaging precision, it continues to require further adjustment in increasing its abilities to operate within the wide range of environments found within any biological system.
This project focused primarily upon the investigation and analysis of current OCT scanning protocols applied within both the surgical and clinical setting. Although not able to develop proprietary OCT scans, this study utilized data from various other projects in order to effectively research the effectiveness of current applications. Comparing the collected data to other traditional scanning modalities (MRI, CT, IVUS), observations were made regarding the quality of the images taken. Observing a dramatic increase in resolution when using OCT technology, it was also noticed that under certain conditions, OCT did not remain applicable due to unfavorable scanning environments. Resorting to the extraction of vessel sections in order to bypass OCT restrictions, several studies noted the inability of OCT to gather valuable data under conditions in which blood flow and muscle movement were present.4
In terms of Kinematic analysis, computer modeling remains essential in developing 3-dimensional models of vessel scans. As a result, an in-depth perspective of the vasculature is gained, increasing the ability of researchers to identify indicators of restenosis and neointimal inhibition. In doing so, stents may then be evaluated stringently for identifying factors such as embedded medications, now known to cause neointimal inhibition and restenosis.5
Optical Coherence Tomography represents an immense shift in the imaging capabilities of modern science and holds the potential to alter the development of interventional devices and implantation protocols on a large scale. In a study completed on the effectiveness of IVUS and OCT scanning technology in capturing images of intracoronary stenting, it was found that OCT consistantly outscored IVUS technology in detecting stent dissection, tissue prolapse, incomplete apposition, and devices exhibiting irregular stents. As seen in Figure 1, OCT scans continually provided images of higher quality than those taken by intravascular ultrasound. Representing the detail and precision of Optical Coherence Tomography, these images also uncover the ability of OCT to magnify stent struts, which, if broken or even slightly skewed, could possibly cause the entire device to fail. In holding the ability to visualize this, stent failure may be caught earlier and before the patient enters a period of immediate harm.
In Figure 2, an OCT and IVUS scan of a stent suffering from tissue prolapse is contrasted. Clearly showing the growth of tissue over several stent struts, the OCT image once again provides much needed detail, which without, could have led to the lack of a prognosis as seen with the IVUS image.
The continued application of Optical Coherence Tomography within the field of medicine represents a significant improvement over previous scanning modalities. With its dramatically increased ability to capture detail, OCT gives both doctors and researchers alike the information needed to correctly diagnose intravascular failure, thereby avoiding the possibility of misdiagnosis. By effectively implementing new design and implantation protocols for the use of OCT, more effective interventional devices could be developed, allowing for an increase patient safety and the accuracy of new research. Overall, by implementing OCT, the application and development of stent devices could be vastly improved bringing a new generation of cardiovascular devices and vascular treatments to those in need.
I would like to thank Dr. John Karanian, Director of the FDA’s center for cardiovascular and interventional therapeutics, for giving me the incredible opportunity to experience the most advanced medical device development and regulation program currently being completed in the field of interventional therapeutics. I also would like to thank Mr. Charles Ashcraft, Director of the Glenelg Gifted and talented research program, for his invaluable help in the development of this research project, and much needed guidance that has led to such a successful year. Finally, I would like to thank my father, Dr. John Baker, for making this project possible and his continued support throughout the duration of the school year.
The above in-vivo image of a partially dissected stent contrasts a OCT scan (right) and IVUS scan (left)
The above image depicts a scan of a stent experiencing tissue prolapse (Marked by arrows), OCT (Left), IVUS (Right)
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