BACKGROUND Our aim was to compare CT images from native, nephrographic and excretory phases using image quality criteria as well as the detection of positive pathological findings in CT Urography, to explore if the radiation burden to the younger group of patients or patients with negative outcomes can be reduced. METHODS This is a retrospective study of 40 patients who underwent a CT Urography examination on a 192-slice dual source scanner. Image quality was assessed for four specific renal image criteria from the European guidelines, together with pathological assessment in three categories: renal, other abdominal, and incidental findings without clinical significance. Each phase was assessed individually by three radiologists with varying experience using a graded scale. Certainty scores were derived based on the graded assessments. Statistical analysis was performed using visual grading regression (VGR). The limit for significance was set at p = 0.05. RESULTS For visual reproduction of the renal parenchyma and renal arteries, the image quality was judged better for the nephrogram phase (p < 0.001), whereas renal pelvis/calyces and proximal ureters were better reproduced in the excretory phase compared to the native phase (p < 0.001). Similarly, significantly higher certainty scores were obtained in the nephrogram phase for renal parenchyma and renal arteries, but in the excretory phase for renal pelvis/calyxes and proximal ureters. Assessment of pathology in the three categories showed no statistically significant differences between the three phases. Certainty scores for assessment of pathology, however, showed a significantly higher certainty for renal pathology when comparing the native phase to nephrogram and excretory phase and a significantly higher score for nephrographic phase but only for incidental findings. CONCLUSION Visualisation of renal anatomy was as expected with each post-contrast phase showing favourable scores compared to the native phase. No statistically significant differences in the assessment of pathology were found between the three phases. The low-dose CT (LDCT) seems to be sufficient in differentiating between normal and pathological examinations. To reduce the radiation burden in certain patient groups, the LDCT could be considered a suitable alternative as a first line imaging method. However, radiologists should be aware of its limitations.

中文翻译：

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CT泌尿系造影的图像质量和病理学评估：低剂量系列何时足够？

背景技术我们的目的是使用图像质量标准比较自然，肾病和排泄期的CT图像，以及在CT泌尿系造影中检测阳性病理结果，以探讨对年轻患者或阴性结果患者的放射负荷是否可以减少。方法这是一项回顾性研究，对40例在192层双源扫描仪上进行了CT尿路造影检查的患者进行了回顾性研究。根据欧洲指南评估了四个特定的肾脏图像标准的图像质量，并进行了三类病理评估：肾脏，其他腹部和偶然发现，但无临床意义。每个阶段均由三名放射医师根据不同的评分标准分别评估。确定性分数是根据分级评估得出的。使用视觉分级回归（VGR）进行统计分析。显着性极限设定为p = 0.05。结果对于肾实质和肾动脉的视觉再现，肾图相被认为图像质量更好（p <0.001），而排泄相与自然相相比，肾盂/肾盏和近端输尿管的再现质量更好（p <0.001）。同样，在肾实质和肾动脉的肾图检查阶段，在肾盂/肾盂和近端输尿管的排泄阶段，确定性评分明显更高。对这三个类别的病理学评估显示，这三个阶段之间没有统计学上的显着差异。但是，可以通过确定性评分来评估病理 比较原始阶段与肾图和排泄期相比，肾脏病理学具有更高的确定性，而肾脏造影阶段的得分显着更高，但仅针对偶然发现。结论肾解剖的可视化符合预期，与天然期相比，每个造影后期均显示出良好的评分。在这三个阶段之间，在病理学评估中没有发现统计学上的显着差异。低剂量CT（LDCT）似乎足以区分正常检查和病理检查。为了减少某些患者组的辐射负担，可以将LDCT视为第一线成像方法的合适替代方案。但是，放射科医生应意识到其局限性。