Develop a standard technique and demonstrate adequate precision for measurement of intima-media thickness (IMT) for routine clinical use.

IMT is measured using software to analyze ECG-gated US image sequences acquired using a standard protocol. Two sonographers acquire images and measure IMT for 100 vessels. IMT technique standard deviation (SD) is determined by assuming normally distributed measurements, and dividing the SD of the 100 (paired) IMT differences by sqrt(2). This SD will be taken as measures of precision of the IMT technique.

Inclusion Criteria:

• Must have an appointment at either the Cardiovascular Health Clinic or scheduled for a carotid ultrasound.

Exclusion Criteria:

• Carotid endarterectomy,carotid stenting, carotid repair, less than 45 degree range of motion in the neck, and/or cannot lie flat on back.
• Participants Enrolled who are found after imaging not to exhibit a ~1cm long common carotid far wall region free of focal plaque in which to measure IMT will not have their data analyzed further.

75 Men and 75 women, ages 35-65, being seen either at the Mayo Clinic Cardiovascular Clinic, or having an appointment for a carotid duplex ultrasound.