Low Tube Voltage Multi-slice Spiral CT in Evaluation of Malignant Obstruction in Metal Biliary Stents / 中国医学影像学杂志

ABSTRACT

Purpose In order to find out a means that can both meet clinical requirements and reduce radiation dosage in the diagnosis of malignant biliary obstruction, the study aims to evaluate the image quality and the radiation dose of low tube voltage enhanced CT (100 kVp) in displaying malignant biliary obstruction in metal stents. Materials and Methods Between January 2012 and March 2014, 9 patients with highly suspected recurrent occlusion after biliary stent procedure were admitted in Peking Union Medical College Hospital and underwent high resolution three-phase dynamic enhanced CT scan. The CT images on portal veinal phase were reconstructed through the curved planar reformation and the CT values of 184 slices were evaluated along the pathway of the biliary stent. The reconstructed image quality was analyzed when the tube voltage was 140 kVp and 100 kVp respectively, and the different tumor-to-liver contrast-to-noise ratio (CNR) for each lesion, mean image noise, and figure of merit (FOM) between the two data sets were also compared. Results As the tube voltage decreased from 140 to 100 kVp, image noise increased from (19.88±3.62) HU to (24.22±4.24) HU (P<0.001), CNR increased by 15% and FOM improved by 50%. Conclusion A low tube voltage CT technique (100 kVp) improves tumor-to-liver CNR and significantly reduces radiation dose, therefore it is valuable in the manifestation of malignant obstruction in metal stents.