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Abstract：
OBJECTIVE: To assess the feasibility of using virtual non-contrast (VNC) images derived from dual-energy computed tomography (DECT) to replace true non-contrast (TNC) images of papillary thyroid carcinoma (PTC) patients.
METHODS: Images of 96 PTC patients were retrospectively analyzed. TNC images were acquired under the single-energy mode of DECT after the plain scanning. The arterial and venous phase VNC (VNC-a and VNC-v) images were generated by the post-processing algorithm from the arterial phase and venous phase of contrast-enhanced CT images, respectively. Mean attenuation values, image noise, number and length of calcification were measured. Radiation dose was also calculated. Last, subjective score of image quality was evaluated by a 5-point scale.
RESULTS: Signal-to-noise ratio (SNR) of each tissue in TNC images is significantly higher than that of VNC images (p<0.050). Contrast-to-noise ratio (CNR) of fat, muscle, thyroid nodules and internal carotid artery in TNC images is significantly higher than that of VNC images, while CNR in TNC images is lower for cervical vertebra (p<0.001). Calcification is detected on TNC images of 44 patients, while it is omitted on VNC images of 14 patients (31.8%). The subjective score of TNC images is higher than VNC images (p<0.001). The effective dose reduction is 47.6% by avoiding plain scanning.
CONCLUSIONS: Considering the different attenuation value, SNR, CNR and especially reduced detection rate of calcification, we deem that VNC images cannot be directly used to replace TNC images in PTC patients, despite the reduced radiation dose.
METHODS: Images of 96 PTC patients were retrospectively analyzed. TNC images were acquired under the single-energy mode of DECT after the plain scanning. The arterial and venous phase VNC (VNC-a and VNC-v) images were generated by the post-processing algorithm from the arterial phase and venous phase of contrast-enhanced CT images, respectively. Mean attenuation values, image noise, number and length of calcification were measured. Radiation dose was also calculated. Last, subjective score of image quality was evaluated by a 5-point scale.
RESULTS: Signal-to-noise ratio (SNR) of each tissue in TNC images is significantly higher than that of VNC images (p<0.050). Contrast-to-noise ratio (CNR) of fat, muscle, thyroid nodules and internal carotid artery in TNC images is significantly higher than that of VNC images, while CNR in TNC images is lower for cervical vertebra (p<0.001). Calcification is detected on TNC images of 44 patients, while it is omitted on VNC images of 14 patients (31.8%). The subjective score of TNC images is higher than VNC images (p<0.001). The effective dose reduction is 47.6% by avoiding plain scanning.
CONCLUSIONS: Considering the different attenuation value, SNR, CNR and especially reduced detection rate of calcification, we deem that VNC images cannot be directly used to replace TNC images in PTC patients, despite the reduced radiation dose.
摘要：
目的：评估使用来自双能计算机断层扫描（DECT）的虚拟非对比（VNC）图像替代甲状腺乳头状癌（PTC）患者的真实非对比（TNC）图像的可行性。
方法：对96例PTC患者的图像进行回顾性分析。在平面扫描后，在DECT的单能量模式下获取TNC图像。通过后处理算法从对比增强CT图像的动脉期和静脉期生成动脉期和静脉期VNC(VNC-a和VNC-v)图像,分别。平均衰减值,图像噪声,测量钙化的数量和长度。还计算了辐射剂量。最后,图像质量的主观评分采用5分制。
结果：TNC图像中每个组织的信噪比（SNR）显着高于VNC图像（p<0.050）。脂肪的对比噪声比(CNR)，肌肉，甲状腺结节和颈内动脉的TNC图像明显高于VNC图像,而颈椎TNC图像中的CNR较低(p<0.001)。在44名患者的TNC图像上检测到钙化，而在14例患者的VNC图像上省略了它（31.8％）。TNC图像的主观评分高于VNC图像(p<0.001)。通过避免平面扫描，有效剂量减少了47.6％。
结论：考虑到不同的衰减值，SNR,CNR尤其降低了钙化的检出率，我们认为VNC图像不能直接用来代替PTC患者的TNC图像,尽管减少了辐射剂量。
方法：对96例PTC患者的图像进行回顾性分析。在平面扫描后，在DECT的单能量模式下获取TNC图像。通过后处理算法从对比增强CT图像的动脉期和静脉期生成动脉期和静脉期VNC(VNC-a和VNC-v)图像,分别。平均衰减值,图像噪声,测量钙化的数量和长度。还计算了辐射剂量。最后,图像质量的主观评分采用5分制。
结果：TNC图像中每个组织的信噪比（SNR）显着高于VNC图像（p<0.050）。脂肪的对比噪声比(CNR)，肌肉，甲状腺结节和颈内动脉的TNC图像明显高于VNC图像,而颈椎TNC图像中的CNR较低(p<0.001)。在44名患者的TNC图像上检测到钙化，而在14例患者的VNC图像上省略了它（31.8％）。TNC图像的主观评分高于VNC图像(p<0.001)。通过避免平面扫描，有效剂量减少了47.6％。
结论：考虑到不同的衰减值，SNR,CNR尤其降低了钙化的检出率，我们认为VNC图像不能直接用来代替PTC患者的TNC图像,尽管减少了辐射剂量。
