Quantitative assessment of aortic sclerosis using ultrasonic backscatter

Abstract

Background: The development of therapeutic interventions to prevent progressive valve damage is more likely to limit the progression of structural damage to the aortic valve with normal function (aortic sclerosis [ASC]) than clinically apparent aortic stenosis. Currently, the ability to appreciate the progression of ASC is ompromised by the subjective and qualitative evaluation of sclerosis severity. Methods: We sought to reveal whether the intensity of ultrasonic backscatter could be used to quantify sclerosis severity in 26 patients with ASC and 23 healthy young adults. Images of the aortic valve were obtained in the parasternal long-axis view and saved in raw data format. Six square-shaped 11 × 11 pixel regions of interest were placed on the anterior and posterior leaflets, and calibrated backscatter values were obtained by subtracting the regions of interest in the blood pool from the averaged backscatter values obtained from the leaflets. Results: Mean ultrasonic backscatter values for sclerotic valves exceeded the results in normal valve tissue (16.3 ± 4.4 dB vs 9.8 ± 3.3 dB, P < .0001). Backscatter values were greater (22.0 ± 3.5 dB) in a group of 6 patients with aortic stenosis. Within the sclerosis group, the magnitude of backscatter was directly correlated (P < .05) with a subjective sclerosis score, and with transvalvular pressure gradient. Mean reproducibility was 2.4 ± 1.8 dB (SD) between observers, and 2.3 ± 1.7 dB (SD) between examinations. Conclusion: Measurement of backscatter from the valve leaflets of patients with ASC may be a feasible means of following the progression and treatment response of aortic sclerosis.