Transjugular intrahepatic portosystemic shunt in an infant.

A 15-month-old girl, who presented with biliary cirrhosis secondary to cystic fibrosis with refractory ascites and recurrent intestinal bleeding, underwent percutaneous transjugular intrahepatic portosystemic shunting. Immediately following the procedure the ascites disappeared and no further bleeding occurred. The stent shunt was patent on Doppler ultrasound until the 22nd day. The patient died on day 22 because of liver failure due to a low-flow syndrome with severe hepatic ischaemia, but with no recurrence of bleeding or ascites.

Hepatic iron overload: diagnosis and quantification with MR imaging.

OBJECTIVE: The aim of this study was to assess the sensitivity of MR imaging in the diagnosis of liver hemochromatosis and its ability to quantify hepatic iron concentration (HIC). SUBJECTS AND METHODS: MR images were prospectively obtained in 58 patients suspected to have hemochromatosis. We used a scanner with a 0.5-T magnet and two sequences: gradient-echo T1-weighted (400/12 [TR/TE], 90 degrees flip angle) and gradient-echo T2*-weighted (700/30, 30 degrees flip angle) sequences. Measurement of the liver-to-muscle signal-intensity ratio was compared with the HIC value measured at biopsy for each patient. RESULTS: Both MR sequences showed significant correlation between decreased signal-intensity ratios and increased HIC (r = -.87 for T1-weighted sequences and r = -.74 for T2*-weighted sequences). The sensitivity and specificity of the T2*-weighted sequence (signal-intensity ratio < 0.8) to detect iron overload (HIC > 36 mumol/g) were 91% and 88%, respectively. The best correlation was obtained with T2*-weighted sequences, when patients had an HIC less than 100 mumol/g (r = -.71); with T1-weighted sequences, the best correlation was obtained when patients had an HIC of 100-324 mumol/g (r = -.67). We found a significant correlation between the HIC revealed on MR images, calculated from both sequences, and that measured at biopsy when patients had an HIC of less than 300 mumol/g (r = -.93, p < .01). CONCLUSION: MR imaging shows promise in differentiating normal from abnormal hepatic iron concentration and in grossly quantifying moderate degrees of hepatic iron overload.

[Factors of image quality in spiral x-ray computed tomography]. / Facteurs de qualité de l'image en scanner spiralé.

In helical CT, there are 4 mains factors of quality: The in-plane spatial resolution that is the same in conventional CT; The spatial resolution on the Z axis, which is the slice thickness. The increase factor of the slice thickness between a conventional and a helical CT depends on the pitch and the reconstruction algorithm. The value of the increase factor can be easily calculated; The signal to noise ratio which depends on the collimation, the mA, the KV and the reconstruction algorithm. The signal to noise ratio is not depending on the table speed; The reconstruction interval which can be less than the slice thickness. Then the contrast of small lesion is improved and stair-step artifacts are reduced in 3D reformations.