MDCT angiography of peripheral arteries: technical considerations and impact on patient management

With the introduction of MDCT with 16 or more detector rows, CTA of aortoiliac and peripheral run-off vessels has become a routine clinical tool. Rapid scan times of approximately 30 s for the entire peripheral vascular tree combined with thin slices (1-2 mm) allow high-resolution 3-D reconstruction. The short scan duration requires injection of a relatively small volume of contrast material. We recommend a monophasic contrast bolus of 100 mL Iomeprol 400 (Bracco, Italy) and 50 mL normal saline at a rate of 4 mL/s. This approach provides strong enhancement and adequate visualization of small peripheral vessels, including 93% of arteries below the knee and 84% of pedal arteries. The best synchronization of contrast bolus and scan acquisition is achieved with a table feed of 40-48 mm/s; this approach provides significantly stronger and more homogeneous enhancement along the z-axis than faster or slower approaches, and largely avoids problems associated with overriding of the bolus or venous overlay (<3%). Postprocessing of CTA datasets is crucial for adequate documentation and communication of anatomy and pathology. We prefer MIP reconstructions after bone removal and curved MPR. In a recent comparative study performed in 50 patients (958 lesions) to determine the accuracy of 16-slice CTA compared to DSA for detection of clinically relevant (>50%) stenoses, we obtained sensitivity and specificity values of 90.1-93.3% and 95.6-96.5%, respectively. Patient management decisions (conservative, intervention, or surgery) based on CTA were the same as after DSA in 49 of the 50 patients. CTA is an accurate, noninvasive alternative to DSA of the aorto-iliac and peripheral run-off arteries.