Quantification of Calcium Amount in a New Experimental Model: A Comparison between Ultrasound and Computed Tomography

Abstract

PurposeCalcification is an important prognostic factor in aortic valve stenosis. However, there is no ultrasound (US) method available to accurately quantify calcification in this setting to date. We aimed to validate a new US method for measuring the amount of calcium in an in vitro model, and compare it to computed tomography (CT), the current imaging gold standard.Materials and MethodsAn agar phantom (2% agar) was made, containing 9 different amounts of calcium-hydroxyapatite Ca5(PO4)3OH (2 to 50mg). The phantoms were imaged with micro-CT and US (10 MHz probe). The calcium area (areacalcium) and its maximum pixel value (PVmax) were obtained. These values were summed to calculate CT and US calcium scores (∑(areacalcium × PVmax)) and volumes (∑areacalcium). Both US- and CT-calcium scores were compared with the calcium amounts, and with each other.ResultsBoth calcium scores correlated significantly with the calcium amount (R2 = 0.9788, p<0.0001 and R2 = 0.8154, p<0.0001 for CT and US respectively). Furthermore, there was a significant correlation between US and CT for calcium volumes (R2 = 0.7392, p<0.0001) and scores (R2 = 0.7391, p<0.0001).ConclusionWe developed a new US method that accurately quantifies the amount of calcium in an in vitro model. Moreover it is strongly correlated with CT.

Pulsed Cavitational Ultrasound Softening

“…The histological analyses showed a fragmentation of calcifications with the preservation of the leaflet superficial structures. Micro-CT imaging, which can be considered as a gold standard for the valvular calcification evaluation15,16, confirmed that micro-fragmentations appeared inside the calcification after PCU. This micro-fragmentation of large calcifications could explain the overall change of biomechanical properties which leads to the improvement of the leaflet motion.…”