Study of effectiveness and safety of portal vein embolization using a new liuid embolic material (Embol-78-12) in pigs

To evaluate the effectiveness and safety of a new liquid embolic material, Embol-78-12, in portal vein embolization (PVE) in pigs. A total of 13 pigs were used in this study. The test material, Embol-78-12, was obtained by hydrolysis of polyvinyl acetate (PVAc) and dissolved in a mixture of 45% ethanol and 55% nonionic water-soluble contrast medium (Ultravist 370) (v/v). Its radioopacity was good. PVE involved the use of 5cc of Embol-78-12 in the left lobe (left and left paramedian segments) of the liver ; to prevent reflux of the embolic material through the percutaneous transhepatic route, an occlusion balloon catheter was used. Six pigs were sacrified immediately after PVE and formed a normal control group, used to determine the average volume ratio of the right and left lobe of the pig. Follow up study was performed in the other seven pigs ; changes in body temperature and liver function test (GOT, GPT, and total bilirubin) at 0, 3, 6, 10, 14 days after PVE were recorded. Four pigs were sacrificed at 2 weeks, and three at 4 weeks. The embolization rate, changes in the volume ratio of the right and left lobe, the atrophy ratio of the embolized lobe and regeneration rate of the non-embolized lobe were evaluated. In the left lobe, PVE was successfully completed in all pigs. Follow-up study revealed evidence of increased body temperature in only one of six pigs and virtually no change in GOT, GPT, and bilirubin levels. In the control group, average liver volume was 511± 43cm3 ; volume percentage of the right and left lobe of the liver was 55 ± 2% and 45± 1, respectively. The embolization rate in this study was 45± 1%. When the animals were sacrificed at 2 and 4 weeks, embolized left portal vein showed complete occlusion. Volume percentage of the right and left lobe of the liver was 71 ± 3 and 29 ± 3 at 2 weeks, and 84 ± 3 and 16 ± 3% at 4 weeks. The atrophy ratio of the embolized lobe was 22% at 2 weeks (average decrease : 51cm3) and 49% at 4 weeks (average decrease : 114cm3). The regeneration rate of non-embolized lobe was 12.6cm3/day (176cm3 for 2 weeks) during the first 2 weeks and 8.9cm3/day(125cm3 for 2 weeks) during the next 2 weeks. In normal pig liver, embol-78-12 used with occlusion balloon catheter is an effective and safe material for PVE. We believe it is suitable for PVE in the clinical field and will be used in many clinical applications in the field of interventional radiology