WE-E-134-10: Correlation of Cognitive Function with Ultrasound Strain Indices

Abstract

Purpose: Instability in vulnerable plaque that generates microemboli, may be related to cognitive decline. Strain imaging to detect plaque vulnerability may be able to determine cognitive impairment. Methods: Plaque instability may be characterized by increased strain variations. Radiofrequency signals for ultrasound strain imaging was acquired on the carotid arteries of 24 human subjects using a Siemens S2000 with a 18L5 transducer. These patients were also scored for cognitive function using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Plaque regions were segmented by a radiologist at end-diastole using the medical interaction toolkit (MITK). A hierarchical block-matching motion tracking algorithm was utilized to estimate the cumulated axial, lateral, and shear strains within the imaging plane. Maximum, minimum and peak-to-peak strain indices in the plaque computed from the mean cumulated strain over a small region of interest (ROI) in the plaque with large deformations (10–20 data points), were obtained. Maximum and peak-to-peak mean cumulated strain over the entire plaque region was also computed. All the strain indices were then correlated to the total RBANS score and a Pearson coefficient along with significance was obtained. Results: Our results indicate correlations of the total RBANS score with maximum axial strain (r=−0.491, p=0.014), peak-to-peak axial strain (r=−0.401, p=0.041), maximum lateral strain (r=−0.501, p=0.012), and peak-to-peak lateral strain (r=−0.507, p=0.011). There was no significant correlation between the total RBANS score and shear strain, and strain indices averaged over the entire identified plaque. Conclusion: Results reveal a direct relationship between the maximum axial and lateral strain indices in carotid plaque with cognitive impairment. Ultrasound strain imaging estimates deformation and elastic properties of plaque, predicting the probability of plaque rupture, which in turn causes emboli. The correlation study indicates that these microemboli may be related to cognitive impairment. This work was supported in part by NIH grants R21 EB010098-02, R01 NS064034-04, and 2R01 CA112192-06.