The vessel age is calculated using the measurements of the intima-media thickness and epidemiologic data. An increased vascular age suggests an increase in the risk for cardiovascular events. Various ultrasound machine manufacturers offer calculation packages that will automatically calculate and assign vascular age based on the intima-media thickness measurements. Automatic calculation tools built into these packages will also measure the average of the intima-media throughout an area designated by a sample box of; generally 10 mm applied to the area to be measured. Manual measurements of the posterior wall can also be obtained utilizing caliper measurements in the ultrasound machine; however, this may be difficult with the vessel wall usually measuring less than 1 mm. There is also independent third-party software available that will calculate the CIMT from various different types of machines by uploading the images into the software program. This technique is widely used in the research arena to evaluate the CIMT in response to diseases and treatments.
In general, a CIMT greater than 0.9 mm is considered an abnormal thickness. As a patient ages, the normal range also changes, increasing as the patient gets older. A CIMT thickness greater than or equal to 1.5 mm suggests the patient is at intermediate risk of future cardiovascular events. A CIMT thickness greater than or equal to 2.5 mm suggests the patient is at significant risk of future cardiovascular events.
