Role of sonography for implantation and sequential evaluation of a VX2 rabbit liver tumor model

We investigated the role of sonography in the implantation process of a VX2 rabbit liver tumor model and sequential evaluation.

Fifty rabbits were divided into 2 groups. Animals in group I underwent surgical implantation, whereas those in group II received percutaneous sonographically guided implantation. At 7, 14, 21, and 28 days after implantation, respectively, 5 rabbits in each group were examined with conventional, color Doppler (CD), contrast-enhanced (CE) pulse inversion harmonic (PIH), and CE CD sonography. Pathologic examination was performed with hematoxylin-eosin, nicotinamide adenine dinucleotide phosphate-diaphorase, and succinic dehydrogenase stains.

Twenty-one rabbits with tumors survived in group I, and 22 with tumors survived in group II. The mean duration of implantation +/- SD in group II was 16.9 +/- 3.4 minutes, whereas that in group I was 21.5 +/- 4.1 minutes (P < .05). The tumor volume measured by conventional sonography increased from 0.28 +/- 0.14 cm(3) at 7 days to 16.49 +/- 5.50 cm(3) at 28 days in group I and from 0.31 +/- 0.19 to 19.79 +/- 4.70 cm(3) in group II, whereas no significant difference existed between the groups. On CD, CE PIH, and CE CD sonography, most tumors were hypervascular before 14 days and after 14 days had peripheral vessels and central hypovascular areas, which were shown as necrotic areas by pathologic examination.

Sonographically guided implantation achieved a good success rate with convenient inoculation performance. Conventional gray scale, CD, CE PIH, and CE CD sonography were useful in sequential evaluation of tumor growth and characteristic vascularity.