Magnetic Resonance-Guided Angioplasty With Delivery of Contrast-Media Doped Solutions to the Vessel Wall : An Experimental Study in Swine

Objectives: To assess the feasibility of magnetic resonance (MR)-guided delivery of a solution containing contrast-medium and immediate online monitoring of its distribution to the vessel wall during MR-guided angioplasty in peripheral arteries. Materials and Methods: In 3 pigs, the feasibility of MR-guided atraumatic delivery of a solution containing contrast-medium and tissue dye (0.05 mmol/mL Gd-DTPA, 3% Evans blue dye) into the vessel wall of the iliac arteries was tested using a permeable balloon catheter (8 mm). Catheter placement was monitored using a steady-state free precession real-time imaging sequence. Additionally, in 5 pigs, surgically created bilateral stenoses in the external iliac artery were dilatated with the porous balloon. In these animals, contrast-enhanced MR angiography was performed before and after the interventions to assess the degree of the stenosis. In all animals, the vessel wall was delineated before and after dilatation using a Tl-weighted gradient echo (GE) sequence. Results: In the 3 animals without stenosis, contrast medium was successfully applied to the vessel wall. On the GE images, the normalized signal intensity of the vessel wall was 0.95 ± 0.015 arbitrary units (a. u.) prior and 2.15 ± 0.105 a. u. after the intervention (P < 0.01). In the animals with stenosis, MR angiography performed before and after the intervention demonstrated successful dilatation of 9 of the 10 stenoses. Before the intervention, 7 stenoses were severe (76%-99%) and 3 moderate (50%-75%), and after the intervention, 4 stenoses were completely removed and 5 mild (<50%). Also in these 5 animals, the solution was visible in the vessel wall of the arteries on the Tl-weighted GE MR images (normalized signal intensity prior the intervention 1.33 ± 0.16 a. u. and 2.97 ± 0.23 after angioplasty; P < 0.05). Histology demonstrated the distribution of the Evan's blue dye within the vessel wall in all animals. Conclusions: MR-guided delivery of a contrast-medium containing solution and immediate online assessment of its distribution to the vessel wall during angioplasty in peripheral arteries is feasible.