Multistage preclinical evaluation of a retrievable 3 T MR-resonant inferior vena cava filter and snare loop for MRI-guided interventions.

BACKGROUND

Fluoroscopy-guided inferior vena cava (IVC) filter implantation and retrieval involve ionizing radiation and iodinated contrast agents. MRI-guided interventions may provide a radiation-free alternative with direct visualization of filter position and hook accessibility. This study evaluated the feasibility of MRI-guided implantation and snare loop (SNL)-assisted retrieval of a dedicated MR-resonant IVC filter at 3 T.

METHODS

MR-resonant devices were assessed in a three-stage protocol. Device visibility was investigated in a saline phantom using balanced steady-state free precession (bSSFP) imaging at 3 T with the IVC filter oriented parallel to the main magnetic field B0 and assessed at different longitudinal-axis rotations and flip angles. MRI-guided IVC filter implantation was performed in a polymer-based vessel phantom. Finally, MRI-guided IVC filter implantation and SNL-assisted retrieval were performed in porcine models (n = 5).

RESULTS

MR-resonant signal enhancement enabled reliable visualization of the IVC filter in phantom and in vivo experiments. Eight filters were successfully implanted in five animals, and SNL-assisted retrieval followed by re-implantation was achieved in all retrieval attempts (3/3). Quantitative signal analysis of the saline phantom experiments demonstrated significant effects of flip angle (p < 0.001), rotation angle (p < 0.001), and filter diameter (p = 0.032) on normalized signal intensity, with the strongest signal enhancement observed at a flip angle of 10°.

CONCLUSIONS

MRI-guided implantation and SNL-assisted retrieval of an MR-resonant IVC filter at 3 T demonstrated feasibility within a multistage preclinical workflow. Phantom and in vivo experiments showed reliable visualization and procedural guidance, supporting further development toward clinically applicable MRI-guided caval interventions.