| Background and PurposeBudd-Chiari syndrome (BCS) focuses on the middle and lower reaches of the Yellow River and the Huai River in China, especially in the eastern parts of Henan province, which has been one of the high occurrence areas. In recent years, with the development of image technology, the discovery rates of BCS display gradually increase. Digital subtraction angiography (DSA) has been considered extensively as the golden standard for diagnosing vascular diseases. However, it is an expensive, complex and invasive technique, and it can only show the intravascular status, which limits the clinical application of DSA. With the rapid development of Multi-slice spiral CT (MSCT), it has been widely applied in diagnosis of BCS. MSCTA angiography (MSCTA) not only clearly shows the lesion location, the degree of stenosis and the collateral circulation, but also displays the hepatic anatomy and diseases, which guides clinical diagnosis and treatment. However, BCS by itself is a type of complex vessel disease with multiple differences on intrahepatic blood circulation time, which has been usually diagnosed by the conventional tri-phase enhancing scanning phase of MSCT, which will lead to the decrease of accuracy of imaging diagnosis. In this study, the MSCTA scanning technique of Budd-Chiari syndrome was optimized to obtain the best scanning phase, get technically quality images and reduce the dose of contrast and radiation effectively.Materials and methodsOne hundred and four cases of BCS diagnosed with clinical or ultrasound were randomly selected from March 2010 to October 2010 in the First Affiliated Hospital of Zhengzhou University, and all the cases all diagnosed by MSCTA were divided into three groups including A, B groups (experimental group) and C group (control group). The experimental groups adopted the new scanning techniques [individual contrast agent's total dosage (G), dual-flow injection (4.0ml/s-80%G,2.0ml/s-20%G, 2.0ml/s-20ml physiological saline) and portal trigger scanning (threshold-100Hu)]. Control group adopted the conventional tri-phase scanning technique (delay time:25s-30s,65s-75s,130s-140s).25 cases in A group included 14 cases of males and 11 cases of females with average ages 43.32±10.33 years old and average weights 64.74±12.12 kg, and contrast agent's total dosage was 2.0 ml/kg. Meanwhile, 49 cases in B group included 32 cases of males and 17 cases of females with average ages 43.82±14.44 years old and average weights 65.16±10.67 kg, and contrast agent's total dosage was 1.8 ml/kg. Additionally,30 cases in C group included 18 cases of males and 12 cases of females with average ages 47.27±12.06 years old and average weights 63.96±11.51 kg, and contrast agent's total dosage was 100ml.Scan parameters of the GE 64-slices VCT such as tube voltage (120 kV), tube current (Auto-mA technical,240-500mA), pitch (0.984:1), speed of table (39.37mm/rot), tube rotation time (0.8s), noise index (8.10), slice thickness and increment (5.0mm), and collimation (64×0.625mm) were adopted in the new scanning technical.Every patient performed both plain scan and contrast enhanced scans, iodinated contrast medium (100ml,350mgI.ml-1) adopted dual-flow injection technique using stellant dual-syringe injector (Medrad, USA) and the scan range was set from 2.0cm above the midriff to the subhepatic region. Smart-prep scanning technology was used on contrast enhanced scans, the experimental groups adopted scan triggering by monitoring portal venous whereas the control group monitored aorta abdominalis. All the original data adopted standardized algorithm and the reconstructed slice thickness and increment was both 0.625 mm, and then were transmitted to ADW 4.4 workstation to deal with the three-dimensional images of vessels, hepatic parenchyma and collateral circulation by the techniques of VR (volume rendering), MIP (maximum intensity projection), MinIP (minimum intensity projection), MPVR (Mutiplanar volume reformation), MPR (multiplanar reformation) and CPR (curved planer reformation).The image quality of portal vein (PV), aorta abdominalis, hepatic vein (HV) and inferior vena cava (IVC) were compared, and the optimal scanning time of PV, HV and IVC were analyzed in three groups. The CT image quality and diagnostic accuracy of HV and IVC were compared with DSA in three groups.All the data was analyzed by SPSS 15.0 software package, and the significant level of test was set as a=0.05. Quantitative data and intergroup comparison adopted chi-square test and Bonferroni test, respectively. The qualitative data used Kruskal-Wallis H rank-sum test.Results1. Comparison of the peak intensity of PV, HV, IVC and Aorta abdominalis in three groupsThe average CT value of PV, HV, IVC and Aorta abdominalis between experimental groups and control group had significant difference (P<0.001), however, there was no difference between A and B groups (P>0.05).The average CT values of PV, HV and IVC of experimental groups were significantly higher than that of control group (P<0.001). Average CT value of PV and HV in A, B and C groups were 210.7±28.1 and 174.3±30.0 Hu,203.0±32.6 and 161.9±35.2 Hu and 145.3±23.8 and 125.3±24.0 Hu, respectively. CT value of IVC in three groups was similar to that of HV.Aorta abdominalis could be clearly showed at PV phase in experimental groups, the average CT values were 259.4±63.6 Hu in group A and 250.5±58.1 Hu in group B, which were significantly lower than that in group C (333.5±68.6 Hu). 2. Optimal scanning time of experimental groups and delayed scanning time between HV phase and PV phaseOptimal scanning times in A and B groups were 51.9±6.7s and 47.5±9.6s, respectively, and there was statistical difference between A and B groups (P=0.044<0.05). Delayed scanning times of HV and IVC were 80.8±16.0s and 88.2±20.5s, respectively, and there was no difference (P=0.119>0.05). Scanning after a delay time from PV phase ranged between 24s-34s in group A and 35s-46s in group B (95% confidence interval) could predominantly get the best image of HV and IVC.3. Comparison of satisfaction of PV and HV in three groupsThe image of PV and HV in the experimental group was obviously superior to that in the control group; and PV (6-9 orders) and HV (4-7 orders) in the experimental groups could be clearly showed.Comparison of PV:There were significant differences among three groups (H=10.232, P=0.006<0.05). There was no difference between A and B group (H=0.001, P=0.978>0.05), and the difference in A and C groups was statistical significance (H=4.694,P=0.030<0.05), meanwhile the difference in B and C groups was statistical significance (H=8.156, P=0.004<0.05). The excellent rate of vessels in A and B group were both above 95%.Comparison of HV:There were significant differences among three groups (H=20.447, P=0.0001<0.05). There was no difference between A and B group (H=0.008, P=0.927>0.05), and the difference in A and C groups was statistical significance (H=10.488, P=0.001<0.05), meanwhile the difference in B and C groups was statistical significance (H=17.318,P=0.0001<0.05). The excellent rate of vessels in A and B group were both above 90%, which was superior to C group (63%).4. Comparison of average contrast agent's dosage between two experimental groupsThe contrast agent's dosage in A and B groups were 126.2±16.3ml vs 116.6±17.8ml, and there was significant difference (P=0.027<0.05).5. Comparison of CTA image and diagnostic accuracy of DSAThe diagnostic accuracies in A and B groups both reached 100%, whereas the diagnostic accuracy in C group was only 80%. In addition, display accuracies of HV and IVC in A and B groups reached above 95%, whereas C group was only 76%.6. Radiation doseCompared to three-phase enhanced scanning, two-phase enhanced scanning could reduce radiation dose about 7.84±1.07 mGy in B group。Conclusion1. MSCTA with rapid scanning, clear image and accuracy diagnosis has important significance to diagnosis of BCS. In addition, MSCTA not only show the vascular disease clearly but also diagnose the hepatic primary disease.2. The scanning methods combined with individual contrast agent's dosage (1.8ml/kg), dual-flow injection and portal trigger scanning is a more reasonable MSCTA scanning technique of BCS. Adopting the new scanning techniques can be effectively completed with two-phase scanning, which to some extent reduces the dose of contrast and the incidence of nephrotoxicity. Compared with the conventional tri-phase scanning technique, the new technique can reduce radiation doses, get higher quality images and guide the clinical diagnosis and treatment more efficiently. |
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