Is the first step for carotid artery disease an ultrasound?

Yes, generally: Ultrasound is the best screening tool for carotid disease. It is non-invasive and gives flow data in real time. Carotid ultrasound is advised for people with multiple risk factors (age over 65, high blood pressure, high cholesterol, diabetes, strong family history, smoking), people with symptoms of stroke or an abnormal noise (bruit) in the neck on exam.

Yes: Doing an ultrasound test or what is called duplex ultrasound is the best non invasive test to diagnose carotid disease . Sometime you may need additional testing with ct scan , MRI or even an angiogram which is the most invasive but most most accurate test.