MRI of slow flow in artificial duct in swine

Abstract

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.

Magnetic resonance-assisted imaging of slow flow in the pancreatic and common bile duct in healthy volunteers

“…Initial tests in an experimental study showed that semi-quantitative evaluation of flow was possible (6). This paper presents the first results in humans, using healthy volunteers.…”

“…The MRI sequences have been presented previously (Fig. 1) (5,6). A Phillips Gyroscan ACS-NT (1.5T; Best, The Netherlands) with Powertrack 6000 gradient system was used.…”

“…We have previously published a pulse sequence to visualize slow flow, using a single-shot turbo spin-echo (SS-TSE) sequence based on diffusion-weighted (DW) MRI techniques (5). Application of this MRI technique in an experimental in vivo study in swine showed that semi-quantitative evaluation of flow was possible in the range of 0.0-1.32 cm/s (6). The aim of the present study was therefore to apply the slow-flowsensitive sequence in healthy volunteers, attempting semi-quantitative detection of flow in the CBD and PD.…”

The Secretory Flow of Pancreatic Juice in the Main Pancreatic Duct: Visualization by Means of MRCP with Spatially Selective Inversion-Recovery Pulse

“…Additionally, this technique is not physiologic because it requires the injection of secretin. Other reports have suggested that pancreatic juice fl ow could be detected by using a single-shot turbo spin-echo sequence based on a diffusion-weighted MR imaging technique (18)(19)(20). In this approach, the stationary pancreatic fl uid appears bright, while the moving pancreatic fl uid loses signal intensity as the b value used increases and appears as a fl ow void.…”

Visualization of pancreatic juice movement using unenhanced MR imaging with spin labeling: Preliminary results in normal and pathophysiologic conditions

“…As another method to assess the pancreatic juice movement, Hellund et al (20, 21) reported that diffusion‐based sequence could detect pancreatic juice flow. However, their method showed visualization of pancreatic juice movement indirectly as a flow void.…”