[The impact of large vessel proximity on effectiveness of radiofrequency ablation of hepatocellular carcinoma: a controlled study]. / Influence de la proximité des gros vaisseaux sur les résultats du traitement des carcinomes hépato-cellulaires par radiofréquence: une étude contrôlée.

PURPOSE: To evaluate the risk of radiofrequency ablation treatment failure for hepatocellular carcinomas (HCC) next to large vessels. MATERIALS AND METHODS: Between May 2000 and October 2002, from a total of 83 patients treated by radiofrequency ablation for HCC in a single center, 13 patients with tumoror=3 mm in diameter (Group A) were matched with 13 patients with similar size tumors located away from large vessels (Group B). Immediate response and recurrence rate were evaluated on CT. RESULTS: After mean follow-up interval of 39+/-16.5 months for Group A and 39+/-14 months for Group B, local recurrence rates were 7/12 versus 1/12 respectively (p=0.03). For Group A, 6/7 local recurrences clearly contacted a large vessel. CONCLUSION: The cooling effect from flowing blood in large vessels markedly increases the rate of local failure of radiofrequency ablation for small HCC located near large vessels.

[Susceptibility weighted imaging. Theory and applications]. / L'imagerie de susceptibilité magnétique: théorie et applications.

Susceptibility Weighted Imaging (SWI) is a new MR imaging technique using the BOLD effect (Blood Oxygen Level Dependent) and the differences of susceptibility between tissues. It is a 3D gradient echo, fully velocity compensated sequence. The echo time is chosen to maximize the signal cancellation in veins and a specific post-processing is applied using the phase images as a complementary source of contrast. It is very useful for the visualization of veins either normal or abnormal. It shows hemorrhage, even of small quantity, better than conventional gradient echo sequences. Its use is still limited by a long acquisition time and some remaining artifacts.

Spinal subdural haematoma: a study of three cases.

AIMS: To define the clinical, computed tomography (CT) and magnetic resonance imaging (MRI) features and the role of MRI in the follow-up of spinal subdural haematoma (SSH), and to compare these findings with those of spinal epidural haematomas (SEH). METHODS: We report three cases of SSH (two women, one male, age: 50-74 years). Two patients were on anticoagulant therapy; in the other case the SSH was spontaneous. All the patients were examined 1-3 days after the onset of the symptoms. All of them had CT, two had MRI and one had angiography. Two patients underwent surgery. RESULTS: The haematoma was located in the thoracolumbar region (two) and in the thoracic region (one), extending from five (two) to 11 vertebral body levels (one). The haematomas were posteriorly located with lateral extension. The transverse shape differed with the level: biconvex, biloculated or circumferential. The haematomas were hyperdense on CT. On MRI, SSH yielded high signal on both T1 and T2. The integrity of the posterior fat pads, which was well shown on CT and MRI, and the visualization of the dura mater demonstrated the intradural location of these collections, making them easily distinguishable from spinal epidural haematoma. MRI provides better evaluation of the longitudinal extent. Our results are compared with those reported in the literature. CONCLUSION: MRI is superior to CT for diagnosis and follow-up of SSH. Our findings and those reported in the literature show that the MR features of SSH are quite specific and allow differentiation from SEH.