Power mode ultrasound in preocclusive stenosis of the internal carotid artery.

Purpose: To evaluate the accuracy of power mode (PM) vascular ultrasound in preocclusive (> 90%) stenosis of the extracranial internal carotid artery (ICA) compared to other diagnostic methods and to operative findings. Material and Methods: 50 patients with preocclusive stenosis have been examined in a prospective study by power mode and color flow duplex ultrasound, by triplane aortic arch and four plane selective DSA. In 11 cases a MR angiography (time-of-flight) was available. Diagnostic findings were compared to operative results. Results: There was an agreement in findings in 50/50 patients (100%) for selective DSA, in 47/50 (94%) for power mode ultrasound, in 38/50 (76%) for aortic arch DSA, in 31/50 (62%) for color flow duplex ultrasound, and in 5/11 for MR angiography. In contrast to all other methods, ultrasound showed best the true extent of non-calcified atheromatous plaques. In extended vascular calcifications or kinking, however, only parts of the lumen of the vessel could be demonstrated. Conclusion: Power mode ultrasound shows preocclusive stenosis of the ICA in a faster and more simple way than color flow duplex ultrasound and has diagnostic results near to those of selective DSA. It improves preoperative diagnostic screening.