Abstract：
OBJECTIVE: The aim of this feasibility study was to evaluate the diagnostic accuracy of ultra-low-dose CT colonography using iterative reconstruction algorithms with reference to standard colonoscopy.
METHODS: Prior to this study, a phantom study was performed to investigate the optimal protocol for ultra-low-dose CT colonography. A total of 206 patients with average/high risk of colorectal cancer were recruited. After undergoing full bowel preparation, the patients were scanned in the prone and supine positions with the CT conditions set to 120 kV, standard deviation 45 to 50, and an adaptive iterative reconstruction algorithm applied. Two expert readers read the images independently. The main outcome measures were the per-patient and per-polyp accuracies for the detection of polyps ≥ 10 mm, with colonoscopy results as the reference standard.
RESULTS: Two hundred patients (102 females, mean age 67.5 years) underwent both ultra-low-dose CT colonography and colonoscopy on the same day. The mean radiation exposure dose was 0.64 ± 0.34 mSv. On colonoscopy, 39 patients had 45 polyps ≥ 10 mm (non-polypoid morphology 7), including 4 cancers. Per-patient sensitivity, specificity, and accuracy of CT colonography for polyps ≥ 10 mm were 0.74, 0.96, and 0.92 for reader one, and 0.74, 0.99, and 0.94 for reader two, respectively. Per-polyp sensitivities for polyps ≥ 10 mm were 0.73 for reader one and 0.71 for reader two. On subgroup analysis by morphology, non-polypoid polyps ≥ 10 mm were not detected by both readers.
CONCLUSIONS: Extreme ultra-low-dose CT colonography had an insufficient diagnostic performance for the detection of polyps ≥ 10 mm, because it was unable to detect non-polypoid polyps. This study showed that the problem with ultra-low-dose CT colonography was the lack of detectability of small-size polyps, especially non-polypoid polyps. To use ultra-low-dose CT colonography clinically, it is necessary to resolve the problems identified by this study.
METHODS: Prior to this study, a phantom study was performed to investigate the optimal protocol for ultra-low-dose CT colonography. A total of 206 patients with average/high risk of colorectal cancer were recruited. After undergoing full bowel preparation, the patients were scanned in the prone and supine positions with the CT conditions set to 120 kV, standard deviation 45 to 50, and an adaptive iterative reconstruction algorithm applied. Two expert readers read the images independently. The main outcome measures were the per-patient and per-polyp accuracies for the detection of polyps ≥ 10 mm, with colonoscopy results as the reference standard.
RESULTS: Two hundred patients (102 females, mean age 67.5 years) underwent both ultra-low-dose CT colonography and colonoscopy on the same day. The mean radiation exposure dose was 0.64 ± 0.34 mSv. On colonoscopy, 39 patients had 45 polyps ≥ 10 mm (non-polypoid morphology 7), including 4 cancers. Per-patient sensitivity, specificity, and accuracy of CT colonography for polyps ≥ 10 mm were 0.74, 0.96, and 0.92 for reader one, and 0.74, 0.99, and 0.94 for reader two, respectively. Per-polyp sensitivities for polyps ≥ 10 mm were 0.73 for reader one and 0.71 for reader two. On subgroup analysis by morphology, non-polypoid polyps ≥ 10 mm were not detected by both readers.
CONCLUSIONS: Extreme ultra-low-dose CT colonography had an insufficient diagnostic performance for the detection of polyps ≥ 10 mm, because it was unable to detect non-polypoid polyps. This study showed that the problem with ultra-low-dose CT colonography was the lack of detectability of small-size polyps, especially non-polypoid polyps. To use ultra-low-dose CT colonography clinically, it is necessary to resolve the problems identified by this study.
摘要：
目的：本可行性研究的目的是参考标准结肠镜检查，使用迭代重建算法评估超低剂量CT结肠造影的诊断准确性。
方法：在本研究之前，我们进行了一项体模研究,以研究超低剂量CT结肠成像的最佳方案.共招募了206例结直肠癌平均/高风险患者。经过充分的肠道准备后，在CT条件设置为120kV的情况下，患者在俯卧位和仰卧位进行扫描，标准偏差45到50，并应用了自适应迭代重建算法。两位专家读者独立阅读图像。主要结果指标是检测息肉≥10mm的每位患者和每位息肉的准确性，以结肠镜检查结果为参考标准。
结果：两百名患者（102名女性，平均年龄67.5岁)在同一天接受了超低剂量CT结肠成像和结肠镜检查。平均辐射暴露剂量为0.64±0.34mSv。在结肠镜检查中，39例患者有45个息肉≥10mm（非息肉形态7），包括4种癌症。每个患者的敏感度，特异性，≥10mm息肉的CT结肠造影准确度分别为0.74、0.96和0.92，读者二为0.74、0.99和0.94，分别。对于≥10mm的息肉，每个息肉的敏感性对于阅读器1为0.73，对于阅读器2为0.71。在形态学的亚组分析中，两位读者均未发现≥10mm的非息肉样息肉.
结论：极端超低剂量CT结肠成像对≥10mm息肉的诊断性能不足，因为它无法检测到非息肉样息肉。这项研究表明，超低剂量CT结肠成像的问题是缺乏小尺寸息肉的可检测性，尤其是非息肉样息肉。临床应用超低剂量CT结肠成像,有必要解决本研究发现的问题。
方法：在本研究之前，我们进行了一项体模研究,以研究超低剂量CT结肠成像的最佳方案.共招募了206例结直肠癌平均/高风险患者。经过充分的肠道准备后，在CT条件设置为120kV的情况下，患者在俯卧位和仰卧位进行扫描，标准偏差45到50，并应用了自适应迭代重建算法。两位专家读者独立阅读图像。主要结果指标是检测息肉≥10mm的每位患者和每位息肉的准确性，以结肠镜检查结果为参考标准。
结果：两百名患者（102名女性，平均年龄67.5岁)在同一天接受了超低剂量CT结肠成像和结肠镜检查。平均辐射暴露剂量为0.64±0.34mSv。在结肠镜检查中，39例患者有45个息肉≥10mm（非息肉形态7），包括4种癌症。每个患者的敏感度，特异性，≥10mm息肉的CT结肠造影准确度分别为0.74、0.96和0.92，读者二为0.74、0.99和0.94，分别。对于≥10mm的息肉，每个息肉的敏感性对于阅读器1为0.73，对于阅读器2为0.71。在形态学的亚组分析中，两位读者均未发现≥10mm的非息肉样息肉.
结论：极端超低剂量CT结肠成像对≥10mm息肉的诊断性能不足，因为它无法检测到非息肉样息肉。这项研究表明，超低剂量CT结肠成像的问题是缺乏小尺寸息肉的可检测性，尤其是非息肉样息肉。临床应用超低剂量CT结肠成像,有必要解决本研究发现的问题。
