ABSTRACT
Objective To evaluate the feasibility of dual-source low-dose computed tomography (CT) of the paranasal sinus in children, with acquisition at an ultra-low tube voltage (70 kVp) combined with the Flash scan. Methods CT scans of the paranasal sinus were performed on 80 pediatric patients who were divided into two groups according to different protocols (70 kVp protocol with Flash scan mode and the iterative reconstruction, pitch 3, the experimental group (group A), n = 40; 80 kVp protocol with conventional spiral mode, pitch 1.5, control group (group B), n = 40). For each examination, the CT dose index (CTDIvol), dose-length product (DLP) and effective dose (ED) were estimated. The image noise, signal-to-noise ratio (SNR) and overall subjective diagnostic image quality were also evaluated. Results The images of these two groups were all satisfied for the clinical diagnosis. For radiation dose, the CTDIvol (mGy), DLP (mGycm) and ED (mSv) values of the 70 kVp protocol were significantly lower than those of the 80 kVp protocol [CTDIvol: 0.39 ± 0.004 vs1.57 ± 0.009 mGy, P < 0.001; DLP: 6.31 ± 0.52 vs 19.88 ± 2.01 mGycm, P < 0.001; ED: 0.024 ± 0.005 vs 0.079 ± 0.016 mSv, P < 0.001. Compared with those of the 80-kVp protocol, the image noise and the SNRbone increased, the SNRsoft-tissue decreased. There was no statistical difference in the subjective scores of the two groups of image quality by the two physicians (P > 0.05). Conclusion When diagnosing the paranasal sinus in children, an ultralow tube voltage (70 kVp) combined with the Flash scan technique can reduce the radiation dose significantly while maintaining diagnostic image quality with clinically acceptable image noise.
ABSTRACT
Objective To explore the diagnosis value of dual energy CT in severity analysis of acute pancreatitis.Methods Pancreas CT perfusion images of 60 patients were formatted using the method of Siemens dual energy CT.According to the severity of the acute pancreatitis,60 patients were divided into 3 groups:normal control (NC)group,mild acute pancreatitis (MAP)group and severe acute pancreatitis (SAP)group.Every group had 20 patients.Blood flow(BF),blood volume(BV),permeability of capillary surface (PS)and mean transit time(MTT)were calculated by Siemens MMWP workstation post process software.The meaning of these CT perfusion parameters for severity of acute pancreatitis was analyzed.Results Compared to the NC group,BF and BV in MAP,SAP group were reduced significantly (P 0.05).We also found in ≥45 years old patients,MTT in both MAP and SAP groups were higher than NC group(P <0.05).Conclusion (1)BF and BV are useful in diagnosis of acute pancreatitis and analysis of severity of it.(2)PS is useful in diagnosis of acute pancreatitis.(3)MTT is useful in diagnosis of acute pancreatitis in elderly patients (≥45 years old).