Radiology Section, Nagasaki Kamigoto Hospital, Minamimatsuura, Shinkamigoto, Nagasaki, Japan.
Department of Gastroenterology, Nagasaki Harbor Medical Center, Nagasaki, Japan.
Jpn J Radiol. 2022 Aug;40(8):831-839. doi: 10.1007/s11604-022-01266-1. Epub 2022 Mar 28.
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.
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.
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.
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.
本可行性研究旨在评估使用迭代重建算法的超低剂量 CT 结肠成像的诊断准确性，并将其与标准结肠镜检查进行比较。
在本研究之前，我们进行了一项体模研究，以探讨超低剂量 CT 结肠成像的最佳方案。共招募了 206 名结直肠癌平均/高危患者。在进行充分的肠道准备后，患者分别以仰卧位和俯卧位进行扫描，CT 条件设置为 120kV、标准偏差为 45 至 50，应用自适应迭代重建算法。两名专家读者独立阅读图像。主要观察指标为每位患者和每个息肉的检测准确率，以结肠镜检查结果为参考标准。
200 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。结肠镜检查发现 39 名患者有 45 个≥10mm 的息肉（非息肉样形态 7 个），其中 4 例为癌症。CT 结肠成像对≥10mm 息肉的每位患者的敏感性、特异性和准确性，读者 1 分别为 0.74、0.96 和 0.92，读者 2 分别为 0.74、0.99 和 0.94。每个≥10mm 息肉的敏感性为读者 1 的 0.73 和读者 2 的 0.71。通过形态学亚组分析，两位读者均未检测到非息肉样≥10mm 的息肉。
极端超低剂量 CT 结肠成像对≥10mm 息肉的检测性能不足，因为它无法检测到非息肉样息肉。本研究表明，超低剂量 CT 结肠成像的问题在于无法检测到小尺寸的息肉，尤其是非息肉样息肉。要在临床上使用超低剂量 CT 结肠成像，有必要解决本研究中发现的问题。
