RÉSUMÉ
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.
RÉSUMÉ
<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>