Low injection rate for 3D moving-table bolus-chase MR angiography: initial experience with 3-T imaging to allay venous contamination in the calf.

Objective: The purpose of this study was to evaluate the potential for improving the image quality of 3D bolus-chase peripheral MR angiography by injecting contrast medium at a slow rate.

Subjects And Methods: Using similar imaging parameters in all cases, we performed bolus-chase MR angiography of the abdominal and lower limb arteries of 80 patients. The injection protocol for 40 patients had three parts: 20 mL of gadopentetate dimeglumine at 2 mL/s, 8 mL of gadopentetate dimeglumine at 1 mL/s, and 20 mL of saline solution at 1 mL/s. For the other 40 patients, the injection protocol was 20 mL of gadopentetate dimeglumine at 1.2 mL/s, 8 mL of gadopentetate dimeglumine at 0.7 mL/s, and 20 mL of saline solution at 0.7 mL/s. Using independent Student's t tests between groups, we compared signal-to-noise and contrast-to-noise ratios in the abdomen and pelvis, the thigh, and the calf. Arterial visibility and venous contamination on 3D images of the calf were graded and compared.

Results: The lower injection rate increased arterial visibility (p < 0.001), reduced venous contamination in the calf (p < 0.001), and increased the contrast-to-noise ratio in the calf (p < 0.001). At the upper levels, signal-to-noise and contrast-to-noise ratios did not differ between the two groups.

Conclusion: At 3-T MRI, a lower injection rate may alleviate venous contamination and increase arterial visibility in the calf while signal-to-noise and contrast-to-noise ratios at higher levels are maintained.