Optical flow-based B-mode elastography: Application in the hypertensive rat carotid

Aims-The present paper introduces a new iterative OF-based elastography (OFBE) method devoted to B-mode data. The first OFBE iteration computes axial and lateral displacement fields. Such displacement fields are used for data rigid registration, prior to the second OFBE iteration which computes the 2D strain tensor. Methods-The OFBE method was validated in the common carotid artery of rat hypertension models. The effect of aging on carotid stiffness was investigated in female recombinant inbred rats (RI-17, n = 2) in the first experiment. The outcomes of low/high-salt diets were examined in young male Dahl saltsensitive rats (SS, n = 6; SM12, n = 6; SM9, n = 6) in the second experiment. Results-Good concordance was observed between left and right carotid axial strain measurements with 11.4% relative error, whereas 4.6% relative error occurred between diastolic and systolic axial strain measurements. Old (80 and 85 weeks) RI-17 carotids were determined to be twice as stiff with 5.70 ± 0.97% (strain ± std) as young carotids (30 and 34 weeks) with 13.26 ± 2.73%, p <; 0.001. Carotid axial strain measurement also indicated that salt diets had a significant impact on SS (p = 0.008) and SM12 (p <; 0.001) but not on SM9 (p = 0.881) rats. Conclusion- This work demonstrated that MicroNIVE is feasible as a potential tool to phenotype hypertension in rat models. In addition, we discuss its potential to characterize vascular sequelae of Kawasaki disease in pediatric patients, under current investigation by our team.