[Evaluation of Contrast Enhancement Uniformity and Contrast Media Optimization in Chest-to-lower Extremity CTA Using Variable Helical Pitch Scanning].

PURPOSE: This study aimed to evaluate the usefulness of variable helical pitch scanning (vHP) on the uniformity of contrast enhancement in wide-range computed tomography angiography (CTA) from the chest to the lower extremities using contrast media administered at 400 mgI/kg over 20 seconds.

METHODS

Using the double-level test bolus injection (DLTI) method to determine the contrast arrival time, CTA scans were performed with a fixed-HP method (n=20) and a variable-HP method using vHP (n=20). The CT numbers at five major arterial regions were compared, and a visual assessment was also conducted.

RESULTS

Compared with the fixed-HP method, the variable-HP method significantly increased the CT number in the abdominal aorta and femoral arteries (p<0.05) and improved the uniformity of contrast enhancement along the body axis. The visual assessment also showed significantly higher ratings for the variable-HP method (p<0.05).

CONCLUSION

The protocol combining DLTI and vHP techniques is useful for achieving more uniform contrast enhancement from the chest to lower extremities in CTA while reducing the contrast medium volume, and is expected to improve diagnostic performance.