[Exploration of vessels of the lower limbs by magnetic resonance angiography (MRA)].

Abstract

Interesting results are beginning to be published in the literature concerning the capacities of MRA in arterial disease and thrombophlebitis of the lower limbs. The acquisition techniques reported in the limited number of papers published in the literature are unfortunately too disparate to be applied to routine diagnostic activity. Most teams agree on the fact that the axial plane is the most suitable to visualize arteries of the lower limbs in patients with arterial disease, using 2D acquisition with or without intravenous injection of paramagnetic contrast agent. Based on the experience acquired with the use of multiple sequences obtained in 24 subjects (4 healthy volunteers, 12 patients with arterial disease and 8 cases of suspected thrombophlebitis) and a review of the literature, the potential applications and limits of MRA have been defined as a function of the capacities of current machines. MRA is able to detect venous thrombi and can also provide a complete assessment of arterial stenosis and occlusions in arterial disease of the lower limbs. The only drawback of the technique in arterial disease is the number of sections required, as only the axial plane can be used for acquisition. Consequently, MRA is tending to be developed in specific indications such as topography of arteries suitable for bypass procedures, rather than as a substitute to classical angiographic arterial mapping, although it appears to be superior to arteriography of the lower limbs in some cases in terms of the information it provides on the distal blood supply in the case of proximal occlusion. The problem which remain to be resolved are the reduction of the number of sections and the choice of the optimal field of view. Assuming that the technique is accepted by vascular surgeons, examinations composed of non-contiguous sections would appear to constitute a sufficient diagnostic solution. In thrombophlebitis, the problem is not so much the blood flow as extent of the thrombus. The diagnosis is easy in the case of fresh thrombus (which has a high-intensity signal, like subacute haematoma), but appears difficult or even impossible in the case of phlebitic sequelae.