From the Department of Radiology and Biomedical Imaging, University of California, San Francisco, 513 Parnassus Ave, San Francisco, CA 94117 (M.M.O., C.A., A.S., Y.S., Z.J.W., B.M.Y.); and Department of Radiology, Albert Einstein College of Medicine, Montefiore Medical Center, New York, NY (J.Y.).
Radiology. 2020 Oct;297(1):99-107. doi: 10.1148/radiol.2020200032. Epub 2020 Jul 28.
Background Limited cathartic preparations for CT colonography with fecal tagging can improve patient comfort but may result in nondiagnostic examinations from poorly tagged stool. Dual-energy CT may overcome this limitation by improving the conspicuity of the contrast agent, but more data are needed. Purpose To investigate whether dual-energy CT improves polyp detection in CT colonography compared with conventional CT at different fecal tagging levels in vitro. Materials and Methods In this HIPAA-compliant study, between December 2017 and August 2019, a colon phantom 30 cm in diameter containing 60 polyps of different shapes (spherical, ellipsoid, flat) and size groups (5-9 mm, 11-15 mm) was constructed and serially filled with simulated feces tagged with four different iodine concentrations (1.26, 2.45, 4.88, and 21.00 mg of iodine per milliliter), then it was scanned with dual-energy CT with and without an outer fat ring to simulate large body size (total diameter, 42 cm). Two readers independently reviewed conventional 120-kVp CT and 40-keV monoenergetic dual-energy CT images to record the presence of polyps and confidence (three-point scale.) Generalized estimating equations were used for sensitivity comparisons between conventional CT and dual-energy CT, and a Wilcoxon signed-rank test was used for reader confidence. Results Dual-energy CT had higher overall sensitivity for polyp detection than conventional CT (58.8%; 95% confidence interval [CI]: 49.7%, 67.3%; 564 of 960 polyps vs 42.1%; 95% CI: 32.1%, 52.8%; 404 of 960 polyps; < .001), including with the fat ring (48% and 31%, < .001). Reader confidence improved with dual-energy CT compared with conventional images on all tagging levels ( < .001). Interrater agreement was substantial (κ = 0.74; 95% CI: 0.70, 0.77). Conclusion Compared with conventional 120-kVp CT, dual-energy CT improved polyp detection and reader confidence in a dedicated dual-energy CT colonography phantom, especially with suboptimal fecal tagging. © RSNA, 2020.
背景 用于 CT 结肠成像的有限促泻准备可以改善患者的舒适度，但可能会导致粪便标记不佳导致检查结果不可诊断。双能 CT 可以通过提高对比剂的对比度来克服这一限制，但需要更多的数据。
目的 本研究旨在调查在体外不同粪便标记水平下，与常规 CT 相比，双能 CT 是否能提高 CT 结肠成像中的息肉检测率。
材料与方法 本研究符合 HIPAA 规定，于 2017 年 12 月至 2019 年 8 月期间，构建了一个直径为 30 厘米的结肠体模，其中包含 60 个不同形状（球形、椭圆形、扁平形）和大小（5-9 毫米、11-15 毫米）的息肉。然后，该体模用模拟粪便进行了连续填充，这些粪便用 4 种不同的碘浓度（1.26、2.45、4.88 和 21.00 毫克/毫升）进行了标记，然后使用带有和不带有外脂肪环的双能 CT 进行了扫描，以模拟较大的体型（总直径为 42 厘米）。两名读者独立地对常规 120 kVp CT 和 40 keV 单能双能 CT 图像进行了回顾，以记录息肉的存在和信心（三点量表）。使用广义估计方程比较常规 CT 和双能 CT 的敏感性，使用 Wilcoxon 符号秩检验比较读者的信心。
结果 与常规 CT 相比，双能 CT 对息肉检测的总体敏感性更高（58.8%；95%置信区间[CI]：49.7%，67.3%；960 个息肉中的 564 个 vs 42.1%；95%CI：32.1%，52.8%；960 个息肉中的 404 个；<.001），包括带有脂肪环时（48%和 31%；<.001）。与常规图像相比，双能 CT 提高了读者对所有标记水平的信心（<.001）。两位读者的一致性较高（κ=0.74；95%CI：0.70，0.77）。
结论 与常规 120 kVp CT 相比，双能 CT 提高了专用双能 CT 结肠成像体模中的息肉检测率和读者信心，尤其是在粪便标记效果不理想的情况下。
