A Monte Carlo model of coronary artery plaque growth for use in computational phantoms
Virtual imaging trials (VITs) are a crucial tool that have surfaced as an alternative to traditional clinical trials for the evaluation and optimization of medical imaging technologies. In VITs, a computational phantom is sent through software to simulate an imaging procedure, allowing for analysis of the resulting images. Compared to clinical trials, VITs have the benefits of lower cost, reduced ethical concern, and access to the known ground truth of patient anatomy. For these VITs to be as effective as possible, patient anatomy and physiology must be accurately reflected in computational phantoms. One commonly used computation phantom is the four-dimensional extended cardiac-torso (XCAT) phantom, a comprehensive model that represents human anatomy and physiology. However, the XCAT phantom lacks a detailed model for coronary artery plaques, limiting its use in cardiac VITs. The purpose of this work is to create a Monte Carlo plaque growth algorithm for use with the XCAT phantom. To model plaque growth, a healthy vessel is created, and the plaque is seeded at a random location within the intima. At each iteration, probabilities of plaque growth are assigned to each voxel. This simulation continues for a user-defined number of iterations, at the end of which the plaque is post-processed to reduce small heterogeneities and ensure continuity in the vessel wall. In this study, two plaques were generated and extracted at three timepoints. One of these plaques was inserted into an XCAT coronary tree at two timepoints. Synthetic CT scans of each XCAT were generated with a validated CT simulation software. The resulting images were visually inspected to determine the conspicuity of the inserted plaques. Results show that the growth algorithm creates diverse plaques that can successfully be inserted into the XCAT phantom and used to simulate CT scans, facilitating future evaluation, optimization, and development of diagnostic tools in cardiac CT.
