Anatomical Road Mapping Using CT and MR Enterography for Ultrasound Molecular Imaging of Small Bowel Inflammation in Swine.

Objectives: To evaluate the feasibility and time saving of fusing CT and MR enterography with ultrasound for ultrasound molecular imaging (USMI) of inflammation in an acute small bowel inflammation of swine.

Methods: Nine swine with ileitis were scanned with either CT (n = 3) or MR (n = 6) enterography. Imaging times to load CT/MR images onto a clinical ultrasound machine, fuse them to ultrasound with an anatomical landmark-based approach, and identify ileitis were compared to the imaging times without anatomical road mapping. Inflammation was then assessed by USMI using dual selectin-targeted (MB) and control (MB) contrast agents in diseased and healthy control bowel segments, followed by ex vivo histology.

Results: Cross-sectional image fusion with ultrasound was feasible with an alignment error of 13.9 ± 9.7 mm. Anatomical road mapping significantly reduced (P < 0.001) scanning times by 40%. Localising ileitis was achieved within 1.0 min. Subsequently performed USMI demonstrated significantly (P < 0.001) higher imaging signal using MB compared to MB and histology confirmed a significantly higher inflammation score (P = 0.006) and P- and E-selectin expression (P ≤ 0.02) in inflamed vs. healthy bowel.

Conclusions: Fusion of CT and MR enterography data sets with ultrasound in real time is feasible and allows rapid anatomical localisation of ileitis for subsequent quantification of inflammation using USMI.

Key Points: • Real-time fusion of CT/MRI with ultrasound to localise ileitis is feasible. • Anatomical road mapping using CT/MRI significantly decreases the scanning time for USMI. • USMI allows quantification of inflammation in swine, verified with ex vivo histology.