Four-dimensional transcatheter intra-arterial perfusion MR imaging before and after uterine artery embolization in the rabbit VX2 tumor model

Purpose: To test the hypothesis that four-dimensional (4D) transcatheter intra-arterial perfusion (TRIP) MR imaging can measure uterine fibroid perfusion changes immediately before and after uterine artery embolization (UAE) in the rabbit VX2 tumor model. Materials and Methods: Eight VX2 uterine tumors were grown in six rabbits. After positioning a catheter within the uterine artery, we performed 4D TRIP-MRI measurements with 3-mL injections of 2.5% gadopentetate dimeglumine. We used a dynamic 3D spoiled-gradient echo sequence with in vivo B₁-field correction for improved accuracy during perfusion quantification. We performed UAE using 1 mL of gelatin microspheres (2 × 10⁶ particles; diameter 40-120 μm). Two regions-of-interest were drawn within each tumor upon perfusion maps. Functional embolic endpoints were reported as the mean percent reduction in fibroid tumor perfusion. Measurements before and after UAE were compared using paired t-tests (α = 0.05). Results: VX2 uterine tumor perfusion decreased significantly from 27.1 at baseline to 7.09 after UAE (mL/min/ 100 mL of tissue, P < 0.0001). Overall perfusion reduction was 76.3% (95% confidence interval: 66.3-86.3%). Conclusion: Four-dimensional TRIP MRI can objectively quantify uterine fibroid perfusion reductions during UAE in VX2 rabbits. This technique could be used clinically to potentially determine an optimal embolic endpoint with the long-term goals of improving UAE success rates and minimizing procedure-related ischemic pain.