Department of Radiological Sciences, University of California, Irvine, California, USA.
Med Phys. 2023 Aug;50(8):4930-4942. doi: 10.1002/mp.16326. Epub 2023 Mar 17.
Agatston scoring, the traditional method for measuring coronary artery calcium, is limited in its ability to accurately quantify low-density calcifications, among other things. The inaccuracy of Agatston scoring is likely due partly to the arbitrary thresholding requirement of Agatston scoring.
A calcium quantification technique that removes the need for arbitrary thresholding and is more accurate, sensitive, reproducible, and robust is needed. Improvements to calcium scoring will likely improve patient risk stratification and outcome.
The integrated Hounsfield technique was adapted for calcium scoring (integrated calcium mass). Integrated calcium mass requires no thresholding and includes all calcium information within an image. This study utilized phantom images acquired by G van Praagh et al., with calcium hydroxyapatite (HA) densities in the range of 200-800 mgHAcm to measure calcium according to integrated calcium mass and Agatston scoring. The calcium mass was known, which allowed for accuracy, reproducibility, sensitivity, and robustness comparisons between integrated calcium mass and Agatston scoring. Multiple CT vendors (Canon, GE, Philips, Siemens) were used during the image acquisition phase, which provided a more robust comparison between the two calcium scoring techniques. Three calcification inserts of different diameters (1, 3, and 5 mm) and different HA densities (200, 400, and 800 mgHAcm ) were placed within the phantom. The effect of motion was also analyzed using a dynamic phantom. All dynamic phantom calcium inserts were 5.0 ± 0.1 mm in diameter with a length of 10.0 ± 0.1 mm. The four different densities were 196 ± 3, 380 ± 2, 408 ± 2, and 800 ± 2 mgHAcm .
Integrated calcium mass was more accurate than Agatston scoring for stationary scans ( , ) and motion affected scans ( , ). On average, integrated calcium mass was more reproducible than Agatston scoring for two of the CT vendors. The percentage of false-negative and false-positive calcium scores were lower for integrated calcium mass (15.00%, 0.00%) than Agatston scoring (28.33%, 6.67%). Integrated calcium mass was more robust to changes in scan parameters than Agatston scoring.
The results of this study indicate that integrated calcium mass is more accurate, reproducible, and sensitive than Agatston scoring on a variety of different CT vendors. The substantial reduction in false-negative scores for integrated calcium mass is likely to improve risk-stratification for patients undergoing calcium scoring and their potential outcome.
阿加斯顿评分法是测量冠状动脉钙的传统方法，其在准确量化低密度钙化等方面存在局限性。阿加斯顿评分法的不准确性可能部分归因于阿加斯顿评分法的任意阈值要求。
需要一种不需要任意阈值且更准确、更灵敏、更可重复和更稳健的钙定量技术。钙评分的改进可能会改善患者的风险分层和结果。
适应了钙评分的综合亨氏技术（综合钙质量）。综合钙质量不需要阈值，并且包括图像中的所有钙信息。本研究利用 G van Praagh 等人获得的体模图像，使用钙羟磷灰石（HA）密度在 200-800mgHAcm 范围内，根据综合钙质量和阿加斯顿评分法测量钙。钙质量是已知的，这使得可以在综合钙质量和阿加斯顿评分法之间进行准确性、可重复性、灵敏度和稳健性比较。在图像采集阶段使用了多个 CT 供应商（佳能、通用电气、飞利浦、西门子），这为两种钙评分技术之间提供了更稳健的比较。在体模内放置了三个不同直径（1、3 和 5 毫米）和不同 HA 密度（200、400 和 800mgHAcm）的钙化插入物。还使用动态体模分析了运动的影响。所有动态体模钙插入物的直径均为 5.0±0.1 毫米，长度为 10.0±0.1 毫米。四个不同的密度分别为 196±3、380±2、408±2 和 800±2mgHAcm。
在静止扫描（ ， ）和受运动影响的扫描（ ， ）中，综合钙质量比阿加斯顿评分法更准确。平均而言，对于两个 CT 供应商，综合钙质量比阿加斯顿评分法更具可重复性。综合钙质量的假阴性和假阳性钙评分百分比（15.00%，0.00%）低于阿加斯顿评分法（28.33%，6.67%）。综合钙质量比阿加斯顿评分法更能抵抗扫描参数的变化。
本研究结果表明，在各种不同的 CT 供应商中，综合钙质量比阿加斯顿评分法更准确、更可重复、更灵敏。综合钙质量假阴性评分的大幅减少可能会改善接受钙评分的患者的风险分层及其潜在结果。
