Effect of contrast medium concentration on MR perfusion weighted imaging of hepatic VX₂ carcinoma: an experimental study in rabbits

Objective: To optimize the contrast medium concentration for MR perfusion weighted imaging (PWI) of hepatic VX₂ carcinoma in rabbits, and to evaluate the diagnostic value of MR PWI. Methods: Twenty New Zealand White rabbits with VX₂ carcinoma were divided into 5 groups in a randomized block design, and T₂^*-weighted imaging with gradient-echo EPI was performed in rabbits after intravenous administration of contrast agent (Gadodiamide Injection, Gd-DTPA-BMA) with five different concentrations (0.05, 0.10, 0.20, 0.30, 0.50 mmol/kg) at a injection rate of 2 ml/s. Quantitative and qualitative evaluations were performed in blood perfusion of VX₂ carcinoma and normal hepatic parenchyma. Results: The time of peak (TOP) and the time to peak (TFP) of perfusion in VX₂ carcinoma were shortened, the maximum signal reduction ratio (SRR_max) increased gradually and the mean transit time (MTT) elongated obviously with the increase of contrast medium concentration. MR perfusion in VX₂ carcinoma was characterized by early TOP (12.50 s), short TTP (7.50 s), satisfactory SRR_max(54.33%) and adequate MTT (35,00 s) with the concentration of 0.20 mmol/kg. The TOP, TTP and MTT of VX₂ carcinoma were significantly different from those of normal hepatic parenchyma (P≤0.05). Conclusion: The 0.20 mmol/kg is the most optimized concentration for PWI of rabbits hepatic VX₂ carcinoma. (authors)