Background

Coronary artery calcium scoring (CACS) for coronary artery disease requires true noncontrast (TNC) CT alongside contrast-enhanced coronary CT angiography (CCTA). Photon-counting CT provides an algorithm (PureCalcium) for reconstructing virtual noncontrast images from CCTA specifically for CACS.

Purpose

To assess CACS differences based on PureCalcium images derived from contrast-enhanced photon-counting CCTA compared with TNC images and evaluate the impact of these differences on the clinically relevant classification of patients into plaque burden groups.

Materials and Methods

Photon-counting CCTA images acquired between August 2022 and May 2023 were retrospectively identified. Agatston scores were derived from both TNC and PureCalcium images and tested for differences with use of the Wilcoxon signed-rank test. The agreement was assessed with use of equivalence tests, Bland-Altman analysis, and intraclass correlation coefficient. Plaque burden groups were established based on Agatston scores, and agreement was evaluated using weighted Cohen kappa. The dose-length product was analyzed.

Results

Among 170 patients (mean age, 63 years ± 13 [SD]; 92 male), 111 had Agatston scores higher than 0. Median Agatston scores did not differ between TNC and PureCalcium images (4.8 [IQR, 0–84.4; range, 0.0–2151.8] vs 2.7 [IQR, 0–90.7; range, 0.0–2377.1]; P = .99), with strong correlation (intraclass correlation coefficient, 0.98 [95% CI: 0.97, 0.99]). The equivalence test was inconclusive, with a 95% CI of 0.90, 1.19. Bland-Altman analysis showed wide repeatability limits, indicating low agreement between the two scores. With use of the PureCalcium algorithm, 125 of 170 patients (74%) were correctly classified into plaque burden groups (excellent agreement, κ = 0.88). Patients without plaque burden were misclassified at higher than normal rates (P < .001). TNC image acquisition contributed a mean of 19.7% ± 8.8 of the radiation dose of the entire examination.

Conclusion

PureCalcium images show potential to replace TNC images for measuring Agatston scores, thereby reducing radiation dose in CCTA. There was strong correlation in calcium scores between TNC and PureCalcium, but limited agreement.

© RSNA, 2024

Supplemental material is available for this article.

See also the editorial by Sakuma in this issue.

中文翻译：

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使用来自光子计数冠状动脉 CT 血管造影的虚拟与真实非对比图像进行冠状动脉钙评分

背景

冠状动脉疾病的冠状动脉钙化评分 (CACS) 需要真正的平扫 (TNC) CT 以及增强冠状动脉 CT 血管造影 (CCTA)。光子计数 CT 提供了一种算法 (PureCalcium)，用于从 CCTA 中专门为 CACS 重建虚拟非造影图像。

目的

旨在评估基于对比增强光子计数 CCTA 的 PureCalcium 图像与 TNC 图像相比的 CACS 差异，并评估这些差异对患者斑块负荷组的临床相关分类的影响。

材料和方法

回顾性鉴定了 2022 年 8 月至 2023 年 5 月期间获取的光子计数 CCTA 图像。 Agatston 分数源自 TNC 和 PureCalcium 图像，并使用 Wilcoxon 符号秩检验测试差异。使用等价检验、Bland-Altman 分析和组内相关系数来评估一致性。根据 Agatston 评分建立斑块负担组，并使用加权 Cohen kappa 评估一致性。分析剂量长度乘积。

结果

在 170 名患者中（平均年龄，63 岁 ± 13 [SD]；92 名男性），111 名患者的 Agatston 评分高于 0。TNC 和 PureCalcium 图像之间的 Agatston 评分中位数没有差异（4.8 [IQR，0–84.4；范围，0.0） –2151.8] vs 2.7 [IQR，0–90.7；范围，0.0–2377.1]；P = .99），具有很强的相关性（组内相关系数，0.98 [95% CI：0.97, 0.99]）。等效性检验尚无结论，95% CI 为 0.90、1.19。 Bland-Altman 分析显示出广泛的重复性限制，表明两个分数之间的一致性较低。通过使用 PureCalcium 算法，170 名患者中的 125 名 (74%) 被正确分类为斑块负荷组（非常一致，κ = 0.88）。无斑块负担的患者被错误分类的比例高于正常水平 ( P < .001)。 TNC 图像采集贡献了整个检查辐射剂量的平均 19.7% ± 8.8。

结论

PureCalcium 图像显示出替代 TNC 图像来测量 Agatston 评分的潜力，从而减少 CCTA 中的辐射剂量。 TNC 和 PureCalcium 之间的钙评分有很强的相关性，但一致性有限。

© 北美放射学会，2024

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