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Computed tomographic imaging and mechanical analysis of cellophane banding secured with locking polymer clips for portosystemic shunts in canine cadavers

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  • 1 Department of Clinical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331.
  • | 2 Department of Clinical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331.
  • | 3 School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, NSW 2052, Australia.
  • | 4 School of Mechanical, Industrial, and Manufacturing Engineering, Oregon State University, Corvallis, OR 97331.
  • | 5 Department of Clinical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331.
  • | 6 Department of Clinical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331.
  • | 7 Department of Clinical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331.

Abstract

OBJECTIVE To determine whether cellophane banding secured with locking polymer clips on cadaveric splenic veins would cause less CT imaging artifact and achieve equivalent mechanical strength, compared with cellophane banding secured with metal vascular clips.

ANIMALS 10 canine cadavers.

PROCEDURES Clips of each material were applied to each cadaver in a crossover design study. Triple-layer cellophane bands secured with 4 medium-large or large polymer or metal clips were placed on cadaveric splenic veins and evaluated by use of CT. Beam-hardening artifact was assessed by artifact length, attenuation, and a subjective grading scale ranging from 1 to 3 for mild to severe imaging artifacts. Secured cellophane bands were mechanically tested to determine force-deformation curves and yield forces. Findings for clip methods were compared with a 1-way ANOVA with a Tukey post-test.

RESULTS For metal clips, beam-hardening artifact lengths and subjective artifact grades were significantly higher, whereas attenuation values were significantly lower, than findings for polymer clips. Polymer clips were significantly lower in strength than metal clips with mean ± SD yield loads of 1.9 ± 0.6 N (medium-large polymer clips), 2.8 ± 1.3 N (large polymer clips), 6.0 ± 1.9 N (medium-large metal clips), and 8.4 ± 2.7 N (large metal clips).

CONCLUSIONS AND CLINICAL RELEVANCE Use of locking polymer clips to secure cellophane banding resulted in less CT imaging artifact and mechanical strength, compared with use of metal vascular clips. Use of locking polymer clips may allow improved assessment of postoperative CT imaging in dogs with extrahepatic portosystemic shunts, which warrants in vivo clinical evaluation.

Contributor Notes

Address correspondence to Dr. Townsend (katy.townsend@oregonstate.edu).