MR-IMAGING IN INFERIOR VENA-CAVA THROMBOSIS

Purpose: To prospectively evaluate the efficacy of MR imaging in inferior vena cava (IVC) thrombosis; to differentiate acute from non-acute thrombus, and to identify the presence of changes in the morphology and signal intensity during medical treatment. Methods and materials: Seventeen patients with suspected IVC thrombosis underwent 30 MR examinations. The IVC thromboses were subdivided into two groups (acute and non-acute) according to onset of clinical symptoms. MR imaging of the IVC was analyzed and when an IVC thrombus was identified, a qualitative and quantitative assessment of the thrombus on spin-echo sequences with magnitude and phase reconstruction was performed to evaluate the relationship between signal intensity and the time elapse since the onset of clinical symptoms. Venography and/or CT scan proof was available in all cases. Results: IVC thrombus was correctly identified in 19 MR examinations which showed the size, localization and the degree of lysis during follow-up. No differences were found in the signal intensity of the thrombus related to time. The pattern of the signal intensity was homogeneous in six (86%) acute thrombus and heterogeneous in nine (75%) thrombus of more than 1 week duration. A significant statistical relationship (P < 0.01) existed between the thrombus age and differences in the pattern of signal intensity. Conclusions. MR imaging is accurate to assess the localization and size of IVC thrombus, similar to the imaging techniques of reference. In addition, MR also provides useful information about the age and the morphological variations of thrombus during medical treatment.