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Portal Vein Embolization with Radiolabeled Polyvinyl Alcohol Particles in a Swine Model: Hepatic Distribution and Implications for Pancreatic Islet Cell Transplantation

  • Richard J. OwenEmail author
  • John R. Mercer
  • Faisal Al-Saif
  • Michele Molinari
  • Robert A. Ashforth
  • Ray V. Rajotte
  • Barbara Conner-Spady
  • A. M. James Shapiro
Laboratory Investigation

Abstract

The distribution of radiolabeled polyvinyl alcohol microspheres (PVAMs) when infused into the portal vein of domestic swine was investigated, with the purpose of assessing implications for pancreatic islet cell transplantation. PVAMs measuring 100–300 μm (Contour SE) and labeled with 99mTc were infused into the main portal vein of 12 swine, with intermittent portal venous pressure measurements. The infusion catheter was introduced antegradely via direct or indirect cannulation of the portal vein. The liver was subsequently divided into anatomical segments. Radioactivity (decay corrected) was measured for 99mTc microsphere synthesis, dose preparation, gross organ activities, tissue samples, and blood. Particulate labeling, catheter positioning, and infusion were successful in all cases. The number of particles used was (185,000 ± 24,000) with a volume of 1 ml. Mean portal pressure at 5 min was significantly higher than baseline, but without a significant difference at 15 min. Extrahepatic tissue and serum radioactivity was negligible. A significant difference in number of radioactive particles per gram was detected between segments 6/7 and segments 5/8. Intrasegmental activity was analyzed, and for segments 2/3 a significant difference in the percentage dose per gram across samples was demonstrated (P = 0.001). Effective and stable radiolabeling of PVAMs with 99mTc-sulfur colloid was demonstrated. Portal venous infusion of 100- to 300-μm particles showed entrapment in the sinusoidal hepatic system with transient portal pressure elevation. Preferential embolization into the right lateral and posterior segments occurs, suggesting that flow dynamics/catheter tip position plays a role in particle distribution.

Keywords

Portal vein embolization Radiotracer Polyvinyl alcohol Microspheres Islet cell 

Notes

Acknowledgments

This work was supported by a grant from CHAR (Canadian Heads of Academic Radiology) and from the University of Alberta, Faculty of Medicine. The authors thank Tracey Clare, Christine Cook, and Shannon Erichsen for their invaluable assistance in this project. We are also grateful for the assistance of engineers and sales representatives of Boston Scientific Ltd. in supplying the samples and data on the Contour SE microspheres. The study was carried out in the animal labs of the Surgical-Medical Research Institute, University of Alberta.

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Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  • Richard J. Owen
    • 1
    Email author
  • John R. Mercer
    • 2
  • Faisal Al-Saif
    • 3
  • Michele Molinari
    • 3
  • Robert A. Ashforth
    • 1
  • Ray V. Rajotte
    • 4
  • Barbara Conner-Spady
    • 1
  • A. M. James Shapiro
    • 5
  1. 1.Department of Radiology and Diagnostic Imaging, Faculty of Medicine, Walter Mackenzie Health Sciences CenterUniversity of AlbertaEdmontonCanada
  2. 2.Department of Oncologic Imaging, Faculty of MedicineUniversity of AlbertaEdmontonCanada
  3. 3.Department of SurgeryUniversity of Alberta HospitalEdmontonCanada
  4. 4.Surgical-Medical Research InstituteUniversity of AlbertaEdmontonCanada
  5. 5.Clinical Islet Transplant ProgramUniversity of AlbertaEdmontonCanada

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