Abstract：Objective: To determine the optimal biphasic bolus rate based on automated table movement for aorto-iliac and lower extremity arteries of contrast-enhanced magnetic resonance angiography(CE MRA). Materials and Methods: Fifteen healthy volunteers were given CE MRA examinations in aorto-iliac and lower extremity arteries in three station technique. A 1.5T scanner with a 3D SPGRE was used; the whole body coil was selected for the entire study. Total 30～40ml gadopentetate dimeglumine was administered automatically by a power injector. A biphasic bolus protocol was designed, the first half of the contrast agent volume was injected at a rate of 2.0ml/s, and the second half was injected at a rate of 1.0ml/s in group 1(n=5), 0.8ml/s in group 2(n=5), 0.5ml/s in group 3(n=5), then was flushed with 20ml of normal saline at a rate of 2.0ml/s. For automated table movement and bolus-chase MR angiography, commercially available software was used. The qualitative and quantitative data of image quality were analyzed using student t test analysis. Statistical significance was established at P<0.05. Results: The entire arterial tree from the aorto-iliac arteries to the dorsal calf arteries was displayed. All MR angiographic examinations yielded good results with diagnostic image quality. Signal noise ratio(SNR) and contrast noise ratio(CNR) were calculated on the basis of signal intensity measurements in region of interest. There were no significant differences for SNR and CNR values among all the groups(P>0.05), but the highest SNR and CNR values were found in group 3. The venous enhancement in the calf and thigh was most obvious in group 1, partially seen in group 2, and few showed in group 3. There were statistical differences between venous enhancement scores in group 3 and those in group 1 and group 2(P<0.05). Conclusion: These findings suggest that with the biphasic bolus rate of 2.0ml/s followed by 0.5ml/s, optimal image quality is acquired and venous enhancement is minimized.
2008, Vol. 19 
