Goo Hyun Woo
Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 88, Olympic-ro 43-gil, Songpa-gu, Seoul, 05505, Republic of Korea.
Pediatr Cardiol. 2022 Jun;43(5):1104-1113. doi: 10.1007/s00246-022-02830-2. Epub 2022 Feb 2.
Optimal enhancement of the Fontan pathway is crucial for the accurate CT evaluation. Current guidelines for contrast-enhanced CT protocols are rather inconsistent in scan delays and injection methods. This single-center, retrospective study was performed to compare objective measures of contrast enhancement between 1- and 3-min scan delays (41 and 36 patients, respectively) to determine a better contrast-enhanced CT protocols for evaluating the Fontan pathway. In both groups, a biphasic injection protocol, in which 50% diluted contrast agent (the amount of iodinated contrast agent: 2.0 mL/kg; the amount of saline: 2.0 mL/kg) was injected at the injection rate of 0.5‒2.5 mL/s for 50 s followed by a saline flush at the same injection rate (0.5‒2.5 mL/s), was used. The degree and heterogeneity of cardiovascular enhancement, image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were quantitatively evaluated. The mean densities of all cardiovascular structures were significantly higher in the 1-min delay protocol than in the 3-min delay protocols (p < 0.001). Heterogeneous enhancement (normalized standard deviation > 0.70) in the Fontan pathway was significantly more frequent in the 1-min delay protocol (p < 0.001). No significant differences were found in image noise (p > 0.141) and the frequency showing suboptimal noise (p = 1.000) between the two protocols. SNR and CNR were significantly lower in the 3-min delay protocol (p < 0.001). Compared with the 1-min delay protocol, the 3-min delay protocol achieved more homogeneous enhancement in the Fontan pathway on CT but showed lower contrast enhancement, SNR, and, CNR, indicating the need for further improvement.
Fontan通路的最佳强化对于CT的准确评估至关重要。目前关于对比增强CT方案的指南在扫描延迟和注射方法上相当不一致。本单中心回顾性研究旨在比较1分钟和3分钟扫描延迟（分别为41例和36例患者）之间对比增强的客观指标，以确定用于评估Fontan通路的更好的对比增强CT方案。两组均采用双相注射方案，即先以0.5‒2.5 mL/s的注射速率注射50%稀释的对比剂（碘化对比剂用量：2.0 mL/kg；生理盐水用量：2.0 mL/kg）50秒，然后以相同注射速率（0.5‒2.5 mL/s）进行生理盐水冲洗。对心血管强化的程度和异质性、图像噪声、信噪比（SNR）和对比噪声比（CNR）进行了定量评估。1分钟延迟方案中所有心血管结构的平均密度显著高于3分钟延迟方案（p < 0.001）。Fontan通路中异质性强化（标准化标准差>0.70）在1分钟延迟方案中明显更常见（p < 0.001）。两种方案在图像噪声（p > 0.141）和次优噪声出现频率（p = 1.000）方面未发现显著差异。3分钟延迟方案中的SNR和CNR显著更低（p < 0.001）。与1分钟延迟方案相比，3分钟延迟方案在CT上Fontan通路的强化更均匀，但对比增强、SNR和CNR更低，表明需要进一步改进。
