Portal system evaluation with 3D dynamic contrast enhanced Magnetic Resonance angiography: technique and results = Angiografia con Risonanza Magnetica con tecnica tridimensionale dinamica dopo mezzo di contrasto nello studio del sistema portale: tecnica e risultati

Purpose. To evaluate the feasibility of a contrast enhanced MR angiography (MRA) technique, using the latest 1.5 T MR tomoscan, to obtain optimal imaging of the portal system and compare the angiographic images with those obtained by color-Doppler and DSA. Material and methods. Thirty patients (9 women and 21 men: average 53 years old) underwent contrast MRA of the portal vein, after portal hypertension had been diagnosed on the basis of clinical and chemical data and by color-Doppler. We used a dynamic 3D FFE T1-weighted breath - hold sequence during the arterial and venous phase after administering. 0.2 mmol/Kg of gadolinium-DTPA were at the rate of 2 ml/s. The contrast bolus was monitored using a 2D FFE T1-weighted sequence on a coronal plane. A FFE T1-weighted sequence was performed on axial plane before and after the dynamic sequence to obtain evaluate the a hepatic parenchyma. In the post processing phase MIP (maximum intensity projection) were reconstructed. We considered the patency of the portal venous system and the presence of cavernomatous and collateral circles; portal thrombosis was classified as partial or complete and as proximal or distal. Results. Good quality MR angiographic images were obtained in 28 of the 30 cases examined; in 2 patients movement artefacts compramised the image quality. We observed a concardance between MRA and Doppler ultrasound in 79 vessels out of 84(94%). A 97.5% concordance was found between MRA and DSA (82 vessels out of 84) with a sensitivity of 100% and a specificity of 97.3%. MRA was superior to DSA aad Doppler ultrasound for evaluating large collateral shunts, above all gastro-esophageal and paraumbilical shunts, and complex anatomical conditions. Conclusions. Where available, advanced MRA technology with contrast enhancement should be used as a routine modality to study the anatomy and pathology and the portal system in all patients in whom Doppler ultrasound has yielded doubtful information. MRA is well-suited to obtain good vascular imaging before surgical or interventional procedures.