MR imaging during arterial portography: an experimental study / 中华放射学杂志

ABSTRACT

Objective To evaluate the optimization of perfusing artery and contrast agent dose, and to determine the effect of precontrast injection of papaverine into the perfusing artery or not on the degree of contrast enhancement of the hepatic parenchyma during MRAP in dog models. Methods Sixteen dogs were included in this study and distributed to three study groups (perfusing artery, dose of Gd-DTPA and use of papaverine or not). Animals were anesthetized with Thiopental Sodium. After placement of a 5F end hole angiography catheter with no metal parts into the perfusing artery, the dogs were transferred immediately to the MR imaging unit. Unenhanced GRE MR and MRAP images were performed with a 2.0 T superconducting magnet. Signal intensity of liver parenchyma was measured with 6 different regions of interest. Relative value (%) of liver parenchymal enhancement was measured and compared. Time-enhancement curves were created and compared. Results MRAP images with good quality were obtained in all 16 dogs. The peak relative value of liver parenchymal enhancement and the time to the peak enhancement was similar in the superior mesenteric artery (SMA) group and in the splenic artery (SA) group. The peak relative value of liver parenchymal enhancement was the lowest in the 0.025 mmol/kg group among all groups. There was no statistical difference in the time to relative peak liver enhancement across the four groups. The time to relative peak liver enhancement in the group with papaverine injection was statistically earlier than that in the group without papaverine injection. Conclusion MRAP is a new and feasible imaging technique to detect hepatic masses before operation. When a 20 ml mixed solution of Gd-DTPA(0.050 -0.100 mmol/kg)was injected into perfusing artery at the rate of 1 ml/s, MRAP image of best liver parenchymal enhancement in dogs could be obtained at 21-28 s after the start of injection of Gd-DTPA. We can place catheters in SMA or SA and there was no statistical difference on MRAP images and time-enhancement curves. The dose of 0.050-0.100 mmol/kg Gd-DTPA was sufficient for MRAP. Application of papaverine precontrast advanced the time to peak liver enhancement, but the peak value of liver enhancement was not affected.