Wessling Johannes, Esseling Rainer, Raupach Rainer, Fockenberg Stefanie, Osada Nani, Gerss Joachim, Heindel Walter, Fischbach Roman
Department of Clinical Radiology, University of Muenster, Germany.
Eur Radiol. 2007 Jul;17(7):1885-91. doi: 10.1007/s00330-006-0545-2. Epub 2007 Jan 12.
The purpose of this study was to assess the effect of dose reduction and the potential of noise reduction filters on image quality and the detection of liver lesions using MSCT. Twenty-nine patients with a total of 40 liver lesions underwent 16-slice CT (120 kV; 180 mAs). Virtual noise was added to CT raw datasets simulating effective mAs levels of 155, 130, 105, 80, 55, 30 and 10 mAs. All datasets were post-processed with an edge-preserving noise-reduction filter (ANR-3D), yielding a total of 15 datasets per patient. Ten radiologists performed independent evaluations of image quality, the presence of liver lesions and diagnostic confidence. Quantitative noise and contrast-to-noise ratios (CNR) were obtained. Superior image quality (P < 0.02), reduction of image noise (P < 0.001) and the increase of lesion-to-liver CNR (P < 0.001) were observed in images processed with the ANR-3D filter. Sensitivity for lesion detection remained unchanged down to 105 mAs (CTDI(w) 6.6 mGy) without filter and 80 mAs (CTDI(w) 5.1 mGy) with ANR-3D. Confidence was rated significantly higher for datasets reconstructed with ANR-3D. The use of a noise-reducing, but edge-preserving filter (ANR-3D) is a promising option to reduce further the radiation dose in liver CT.
本研究的目的是评估剂量降低以及降噪滤波器对使用多层螺旋CT（MSCT）的图像质量和肝脏病变检测的影响。29例共有40个肝脏病变的患者接受了16层CT扫描（120 kV；180 mAs）。在CT原始数据集中添加虚拟噪声，模拟有效mAs水平分别为155、130、105、80、55、30和10 mAs。所有数据集均使用保边降噪滤波器（ANR-3D）进行后处理，每位患者共生成15个数据集。10名放射科医生对图像质量、肝脏病变的存在情况和诊断置信度进行独立评估。获得了定量噪声和对比噪声比（CNR）。在用ANR-3D滤波器处理的图像中，观察到图像质量更佳（P < 0.02）、图像噪声降低（P < 0.001）以及病变与肝脏的CNR增加（P < 0.001）。在不使用滤波器时，低至105 mAs（CTDI(w) 6.6 mGy），使用ANR-3D时低至80 mAs（CTDI(w) 5.1 mGy），病变检测的灵敏度保持不变。对于用ANR-3D重建的数据集，置信度评分显著更高。使用一种既能降噪又能保边的滤波器（ANR-3D）是进一步降低肝脏CT辐射剂量的一个有前景的选择。
