Application of ultrasonic thermal imaging in IVUS systems

Sudden disruption of vulnerable coronary plaque is considered by pathologists as the most frequent cause of acute coronary syndromes. These plaques are characterized by a large lipid-rich core with abundant inflammatory cells and a thin fibrous cap, which can be potentially detected with thermal strain imaging (TSI) using IVUS. A phantom experiment using an IVUS array demonstrates the concept and results agree reasonably well with predictions. The in vivo application of this technique faces the major challenge of tissue motion. We propose a practical imaging scheme to minimize mechanical strains caused by tissue motion based on a linear least squares fitting strategy. To test this scheme, thermal strains were artificially superimposed on computed mechanical strain images from clinical data, and results suggest a 1-2°C temperature rise is possible for in vivo plaque detection.