Purpose

We sought to evaluate inter-scan and inter-reader agreement of coronary calcium (CAC) scores obtained from dedicated, ECG-gated CAC scans (standard CAC scan) and ultra-low-dose, ungated computed tomography attenuation correction (CTAC) scans obtained routinely during cardiac PET/CT imaging.

Methods

From 2928 consecutive patients who underwent same-day ⁸²Rb cardiac PET/CT and gated CAC scan in the same hybrid PET/CT scanning session, we have randomly selected 200 cases with no history of revascularization. Standard CAC scans and ungated CTAC scans were scored by two readers using quantitative clinical software. We assessed the agreement between readers and between two scan protocols in 5 CAC categories (0, 1–10, 11–100, 101–400, and > 400) using Cohen’s Kappa and concordance.

Results

Median age of patients was 70 (inter-quartile range: 63–77), and 46% were male. The inter-scan concordance index and Cohen’s Kappa for readers 1 and 2 were 0.69; 0.75 (0.69, 0.81) and 0.72; 0.8 (0.75, 0.85) respectively. The inter-reader concordance index and Cohen’s Kappa (95% confidence interval [CI]) was higher for standard CAC scans: 0.9 and 0.92 (0.89, 0.96), respectively, vs. for CTAC scans: 0.83 and 0.85 (0.79, 0.9) for CTAC scans (p = 0.02 for difference in Kappa). Most discordant readings between two protocols occurred for scans with low extent of calcification (CAC score < 100).

Conclusion

CAC can be quantitatively assessed on PET CTAC maps with good agreement with standard scans, however with limited sensitivity for small lesions. CAC scoring of CTAC can be performed routinely without modification of PET protocol and added radiation dose.

中文翻译：

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PET/CT 衰减图定量冠状动脉钙化评分的可重复性：与 ECG 门控 CT 扫描的比较

目的

我们试图评估从专用的心电门控 CAC 扫描（标准 CAC 扫描）和超低剂量、非门控计算机断层扫描衰减校正（CTAC）扫描获得的冠状动脉钙化（CAC）评分的扫描间和读者间一致性在心脏 PET/CT 成像期间常规进行。

方法

我们从 2928 名连续接受同一天⁸² Rb 心脏 PET/CT 和门控 CAC 扫描的同一混合 P​​ET/CT 扫描患者中，随机选择了 200 名没有血运重建史的病例。两位读者使用定量临床软件对标准 CAC 扫描和非门控 CTAC 扫描进行评分。我们使用 Cohen 的 Kappa 和一致性评估了读者之间以及 5 个 CAC 类别（0、1–10、11–100、101–400 和 > 400）中两个扫描协议之间的一致性。

结果

患者的中位年龄为 70 岁（四分位间距：63-77 岁），46% 为男性。读者 1 和读者 2 的扫描间一致性指数和 Cohen's Kappa 为 0.69；0.75 (0.69, 0.81) 和 0.72；分别为 0.8（0.75、0.85）。标准 CAC 扫描的读者间一致性指数和 Cohen 的 Kappa（95% 置信区间 [CI]）更高：分别为 0.9 和 0.92 (0.89, 0.96)，而 CTAC 扫描：0.83 和 0.85 (0.79, 0.9)对于 CTAC 扫描（ Kappa 差异p  = 0.02）。两种方案之间的大多数不一致读数发生在低度钙化（CAC 分数 < 100）的扫描中。

结论

CAC 可以在 PET CTAC 图上进行定量评估，与标准扫描具有良好的一致性，但对小病变的敏感性有限。CTAC 的 CAC 评分可以常规进行，无需修改 PET 协议和增加辐射剂量。