Related Experiment Video
Updated: Dec 30, 2025
Improved Registration of 3D CT Angiography with X-ray Fluoroscopy for Image Fusion During Transcatheter Aortic Valve Implantation
Published on: June 3, 2018
Feasibility and Accuracy of Aortic Valve Calcium Quantification on Computed Tomographic Angiography in Aortic
Niraj Nirmal Pandey1, Sanjiv Sharma1, Priya Jagia1
1Department of Cardiovascular Radiology and Endovascular Interventions, All India Institute of Medical Sciences, New Delhi, India.
Background:
Traditionally, quantification of aortic valve calcium (AVC) has been performed with noncontrast computed tomography (NCCT) using the Agatston method. This study sought to derive and validate a systematic method enabling AVC quantification using computed tomographic angiography (CTA) in patients with aortic stenosis (AS).
Methods:
The study included 134 consecutive patients with AS who underwent both NCCT and CTA and were subdivided into derivation (n = 71) and validation cohorts (n = 63). AVC on NCCT (AVCNCCT) was quantified using the Agatston method using the software developed for semiautomatic assessment of coronary calcium. On CTA, the mean contrast attenuation of the aorta in Hounsfield units (AortaHU) and SD was measured in the region of interest at the level of the sinotubular junction.
Results:
Using an adjusted calcium detection threshold of AortaHU + 2 SD, we calculated AVC on CTA (AVCCTA) using the same software without modifying other variables. Correlation between AVCNCCT and AVCCTA in the derivation cohort was excellent (r = 0.9679; P < .001). We used a linear regression model to derive a formula for predicting AVCCTA that enabled conversion of AVCCTA to AVCDerived (AVCDerived = 1.821 × AVCCTA). Applying this formula in validation cohort, we calculated AVCDerived, which showed excellent agreement with AVCNCCT (intraclass correlation coefficient, 0.9648; 95% confidence interval, 0.9427-0.9782). Excellent correlation was also found between categorized AVCNCCT and AVCDerived scores (κ = 0.9044; 95% confidence interval, 0.7989-1.0000), with 95.24% (60 of 63) of scores falling within the same severity category.
Conclusions:
AVC quantification on CTA is feasible with high accuracy and reliability and shows excellent agreement with the standard AVCNCCT score. With the systematic approach using "dynamic thresholds" being largely independent of the scan acquisition protocol, AVCDerived can potentially replace AVCNCCT, eliminating the need for separate NCCT acquisition solely for AVC quantification.
Related Concept Videos
01:25Imaging Studies for Cardiovascular System VI: Calcium -Scoring CT
01:28Imaging Studies for Cardiovascular System V: CT
01:20Imaging Studies for Cardiovascular System III: X-Ray
Definition and Purpose
An X-ray, or radiograph, is a non-invasive method that uses ionizing radiation to take images of internal structures. It is mainly used in cardiac imaging to examine the heart, lungs, and major blood vessels, aiming to identify abnormalities in the heart's size, shape, and position, such as heart failure, congenital defects, and vascular...