In vivo real-time microangiography of the liver in mice using synchrotron radiation

The aim of this study was to visualize hepatic microvessels (less than 100 microm in diameter) in vivo, which could not be visualized by conventional X-ray angiography, by using synchrotron radiation (ultra-bright and monochromatic X-ray).

Five female Balb/c nu/nu mice were used. To investigate the hepatic microvessels under nearly physiologic conditions, we performed in vivo aortography under anesthesia with 370 mgI/ml nonionic iodine contrast medium using monochromatic 17-keV X-rays generated by a synchrotron. Images were captured with a pixel matrix size of 1024 x 1024 at a rate of 30 pictures/s. The field of view was 7 mm x 7 mm and thus the pixel size was approximately 7 microm. Captured images were evaluated both qualitatively and quantitatively.

Small hepatic arterial and portal venous branches of the liver were visualized separately during one sequential aortogram. The minimum diameter of the vessels observed was approximately 20 microm, and the vessels which ran parallel to the hepatic artery were observed and it seemed to be intrahepatic peribiliary arterial plexus.

Our new experimental model would be useful for visualization of changes in the hepatic microcirculation under nearly physiologic conditions.