Department of Radiology, Seoul National University Hospital, 101 Daehangno, Jongno-gu, Seoul, 03080, Korea.
Department of Radiology, Seoul National University College of Medicine, 101 Daehangno, Jongno-gu, Seoul, 03080, Korea.
Eur Radiol. 2018 Dec;28(12):5258-5266. doi: 10.1007/s00330-018-5545-5. Epub 2018 Jun 8.
To assess the feasibility of ultra-low dose computed tomography colonography (CTC) using knowledge-based iterative reconstruction (IR) and to determine its effect on polyp detection.
Forty-nine prospectively-enrolled patients underwent ultra-low dose CTC in the supine (100 kVp/20 mAs) and prone positions (80 kVp/20 mAs), followed by same-day colonoscopy. Thereafter, images were reconstructed using filtered back projection (FBP) and knowledge-based IR (IMR; Philips Healthcare, Best, Netherlands) algorithms. Effective radiation dose of CTC was recorded. Pooled per-polyp sensitivity and positive predictive value of three radiologists was analysed and compared between FBP and IMR. Image quality was assessed on a five-point scale and image noise was recorded using standard deviations.
Mean effective radiation dose of ultra-low dose CTC was 0.90 ± 0.06 mSv. Eighty-nine polyps were detected on colonoscopy (mean, 8.5 ± 4.7 mm). The pooled per-polyp sensitivity for polyps 6.0-9.9 mm (n = 22) on CTC reconstructed with IMR (36/66, 54.5%) was not significantly different with that using FBP algorithm (34/66, 51.5%) (p = 0.414). For polyps ≥10 mm (n = 35), however, the pooled per-polyp sensitivity on CTC with IMR (73/105, 69.5%) was significantly higher than that with FBP (55/105, 52.4%) (p < 0.001). In particular, the difference of per-polyp sensitivity was statistically significant in intermediate (p = 0.014) and novice (p = 0.003) reviewers. Furthermore, mean image noise of IMR (8.4 ± 6.2 HU) was significantly lower than that of FBP (37.5 ± 13.9 HU) (p < 0.001) and image quality with IMR was significantly better than with FBP in all evaluated segments in all reviewers (all ps < 0.001).
Sub-mSv CTC reconstructed with IMR was feasible for the detection of clinically significant polyps, demonstrating 70% per-polyp sensitivity of polyps ≥10 mm, while allowing significant noise reduction and improvement in image quality compared with FBP reconstruction.
• Sub-mSv CTC using IMR demonstrated 70% per-polyp sensitivity for polyps ≥10 mm. • CTC using IMR significantly outperformed CTC reconstructed with FBP. • IMR allows significantly more noise reduction and improvement in image quality than FBP.
评估基于知识的迭代重建（IR）在超低剂量 CT 结肠成像（CTC）中的可行性，并确定其对息肉检测的影响。
49 名前瞻性入组患者接受仰卧位（100 kVp/20 mAs）和俯卧位（80 kVp/20 mAs）超低剂量 CTC 检查，随后当天行结肠镜检查。然后，使用滤波反投影（FBP）和基于知识的 IR（IMR；荷兰飞利浦医疗保健公司）算法重建图像。记录 CTC 的有效辐射剂量。分析并比较三位放射科医生的 FBP 和 IMR 图像的每息肉敏感度和阳性预测值。使用标准偏差评估图像质量，并记录图像噪声。
超低剂量 CTC 的平均有效辐射剂量为 0.90 ± 0.06 mSv。结肠镜检查共检出 89 个息肉（平均大小 8.5 ± 4.7 mm）。对于 IMR 重建的 CTC 上 6.0-9.9mm（n=22）的息肉（36/66，54.5%），与 FBP 算法（34/66，51.5%）相比，每息肉敏感度无显著差异（p=0.414）。然而，对于≥10mm 的息肉（n=35），IR 重建的 CTC 每息肉敏感度（73/105，69.5%）显著高于 FBP（55/105，52.4%）（p<0.001）。特别是，中级（p=0.014）和新手（p=0.003）观察者的每息肉敏感度差异具有统计学意义。此外，IMR 的平均图像噪声（8.4 ± 6.2 HU）显著低于 FBP（37.5 ± 13.9 HU）（p<0.001），并且在所有评估的节段中，IMR 的图像质量均显著优于 FBP（所有 p<0.001）。
使用 IMR 重建的亚毫希 CTC 可行，可检测到临床意义上的息肉，对≥10mm 的息肉具有 70%的每息肉敏感度，同时与 FBP 重建相比，可显著降低噪声并改善图像质量。
使用 IMR 的亚毫希 CTC 对≥10mm 的息肉具有 70%的每息肉敏感度。
使用 IMR 的 CTC 显著优于 FBP 重建的 CTC。
IMR 可显著降低噪声并改善图像质量，优于 FBP。
