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Preoperative diagnosis of biliary obstruction mainly depends on imaging examination.Percutaneous transhepatic cholangiography (PTC) is a common method in detecting biliary obstruction.PTC combined with computed tomography (CT) could enhance the diagnostic rate.From April 2009 to April 2011,8 patients with biliary obstruction were admitted to the Shenzhen Hospital of Peking University.Contrast solution (30 ml of iodine solution at a concentration of 1.5％ -2.0％)was injected through a PTC tube,and then CT scan was performed.An iohexol contrast solution at a concentration of 300 mgl/ml was injected at a dosage of 1.5 ml/kg and at 3-5 ml/s,then the arterial phase,venous phase and delayed phase were scanned.The original data were uploaded to Vitrea 2 workstation for multiplane reconstruction,maximum intensity projection and volume rendering.The procedure was successfully performed on all patients,and the position of the biliary obstruction was identified in 7 patients.Five patients were diagnosed as with hilar cholangiocarcinoma,1 with sclerosing cholangitis and 2 with adenoma of the distal common bile duct.The patients' symptoms were alleviated after percutaneous transhepatic biliary drainage.
ABSTRACT
Objective To explore a new scanning technique to reduce and avoid image artifacts of thoracoabdominal CT and improve image quality for patients who cannot raise their arms. Methods Sixty-one patients with arm-raising disability between March 2004 and May 2009 were enrolled in the study. Thirty-one cases before June 2007 were scanned with their arms beside their body (control group), 30 cases after June 2007 were scanned with their arms shifting to different imaging planes of the spine(study group), and another 30 patients who can raising their arms were taken as routine group. The images artifacts were blindly evaluated by 5-points scale (severe, less severe, moderate, minimum and no artifact) by 2 experienced CT technologists and one radiologist and compared between the three groups (χ~2 test). CT values and its noise of the liver with or without artifact of the three groups were measured and analyzed by one-way ANOVA test. Results In the control group, 11 cases had severe, 15 cases had less severe, 5 cases had moderate. In the study group, 6 cases had moderate, 15 cases had minimum, 9 cases had no artifact. In the routine group, 8 cases minimum and 22 cases had no artifact. Image quality was significantly improved in the study group compared to the conventional group where χ~2 = 95.32 and P <0.01. CT value and the noise of the liver without artifact were (54.5±3.0) HU and 10. 7±2.4 in the control group, (52.0±3.5) HU and 10.7±0.5 in the study group, (53.7±3.1) HU and 9.9±0.5 in the routine group, respectively. CT value and noise of the liver with artifact were (41.7±8.4) HU and 17.9±2.6 in control group, (53.1±6.9) HU and 11.0±0.7 in the study group, (54.1±2.4) HU and 9.9±0.5 in the routine group, respectively. The CT value and its noise variation with artifact were significantly higher in the control group than the study group and the control group, where F = 36.352,235. 848, respectively and P <0.01. Conclusion The image quality can be improved and the artifact can be minimized for the patients with arm-raising disability by shifting their arm position to the different imaging planes of the spine.
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Objective Retrospectively evaluate the effect of Z-axis tube-current modulation technique with desired noise level to improve image quality (image noise level) and decrease radiation doses of MSCT (16-slice CT) in chest scanning. Methods Consecutive two hundred patients whose CT scan projection radiographs showed no significant abnormal were randomly divided into two groups by the examination order: Z-axis tube-current modulation (ZTCM) group (odd number, test group) and constant tube-current (CTC) group (even number, contrast group). The desired noise level of ZTCM group was 10HU and the machine automatically set the dynamic tube-current in scanning according to attenuated information of chest acquired in scan projection radiographs, the tubo-current of CTC group was set at 200mA, while the other scan parameters remained totally the same. The maximum tube-current value,CTDIvol, DLP and the tube-current of the slice at the maximum breast level of female patients were recorded respectively. The noise of image at upper lung, aorta arch, left atrium and bottom lung level were measured and compared. The qualities of Images were classified in three levels (excellent, good, poor) with double blind method. Results The mean value of maximum mA, CTDIvol, DLP and mA of the slice at the maximum breast level of ZTCM group were (178.5±125.6) mA, (10.5±3.8) mGy, (231.6±24.3)mGy/cm and (116.0±22.5) mA, those of CTC were 200.0 mA, 12.8 mGy, (274.7±18.4)mGy/cm and 200.0 mA, ZTCM group decreased by 10.8%, 19.9%, 15.7% and 42.0%,respectively, as compared with CTC group. The image quality at upper lung and bottom lung level in ZTCM group was improved significantly (P < 0.05) and the cases of excellent images in ZTCM group was significantly higher than that of CTC group (P < 0.05). Conclusion ZTCM technique not only contributes to more rational distribution of radiation doses but also realizes individuation, decreases the total radiation doses and improves image quality in chest CT scanning. It is valuable and promising in chest CT scan.
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<p><b>OBJECTIVE</b>To analyze the cause of atypical manifestation of hepatocellular carcinoma (HCC) in triple-phase spiral CT enhanced scan.</p><p><b>METHODS</b>Triple-phase spiral CT scan was performed in 75 patients with HCC. The hepatic arterial phase (HAP), portal venous phase (PVP) and delayed phase (DP) images were started at 25 to 30 s, 65 to 70 s and 3 tp 5 min after injection of contrast medium. The contrast enhanced patterns of lesion were observed and analyzed.</p><p><b>RESULTS</b>Ninety-two lesions were found in 75 patients. Typical enhanced findings such as hyperdense in HAP and hypodense in PVP and DP was found in 60 of 92 lesions. Atypical enhanced findings were observed in the other 32 lesions. Fourteen of 32 atypical enhanced lesions were hyperdense in HAP and isodense in PVP, of which 8 were seen in liver cirrhosis and 3 in fatty liver. In DP, 10 were hypodense and 4 still isodense. Eight of the 32 lesions were hyperdense both in HAP and PVP, of which 6 were seen in fatty liver. In DP, 3 were isodense and 5 were hypodense. Six of 32 lesions were isodense in HAP which became hypodense in PVP and DP. Four of 32 lesions were all hypodense in HAP, PVP and DP.</p><p><b>CONCLUSION</b>Multiple atypical enhanced manifestations are present by triple-phase spiral CT scan in HCC. Pattern of blood supply, scanning technique and pathophysiologic status are usually the cause of these findings.</p>