MRI of slow flow in artificial duct in swine.

Our aim was to evaluate whether it is possible to visualize slow flow within a small catheter placed inside a living animal. We used a flow-sensitive, single-shot turbo spin-echo (SS-TSE) MRI sequence, developed in house, based on diffusion-weighted (DW) techniques. Four anesthetized pigs were used as models. A plastic catheter was surgically placed within the common bile duct (CBD). To mimic flow, the catheter was filled with Ringer's acetate and connected to a pump. b factors (s/m(2)) of 0, 6, and 12, with flow velocities raging from 0 to 1.32 cm/s, were used. A total of 375 images were obtained and examined. After correction for bowel movement artifacts, all images displayed the catheter on zero flow. With a flow of 0.66 cm/s or higher, no images displayed the catheter with a b factor of 6 or 12. On the slower flow velocities, it was variable whether the catheter was visible or not, but at b=6 and flow 0.17 cm/s all catheters were viewable. This method made it possible to perform a semiquantitative evaluation of flow velocities in vivo, dividing flow into three groups.