Noninvasive Carotid Imaging

The management of carotid stenosis has been based on major prospective trials that have used arteriography. However, noninvasive methods of evaluation have been sought because angiography has a significant risk of major complications and a high cost. Availability, low cost, and high diagnostic accuracy make duplex ultrasound the first line of investigation when carotid disease is suspected. Duplex ultrasound is limited by operator and machine variability. Magnetic resonance angiography in coordination with duplex ultrasound has increased accuracy and should be done after an equivocal or inadequate duplex ultrasound exam. Magnetic resonance angiography accuracy has improved with the use of contrast and threedimensional time-of-flight techniques over a two-dimensional time-of-flight method. Computed tomographic angiography can also validate the duplex ultrasound exam and give additional information for the arch and intracranial vessels. Axial reconstruction has shown the greatest accuracy. Future studies defining the prognosis of area stenosis, plaque volume, and composition will further improve treatment that is based on noninvasive imaging.