Intima media thickness:
Common carotid:
Vertebral arteries:
Vertebral arteries:
Flow red in both CCA and vertebral arteries: antegrade flow:
Common carotid spectral Doppler:
Mixed effect of both ECA and ICA:
ECA: higher PSV, lower diastolic flow:
IMT:
The normal intima-media thickness (IMT) of the common carotid artery is less than 0.8 mm in men and less than 0.7 mm in women. IMT is a measure of the thickness of the inner layer of the carotid artery, which is called the intima. An increase in IMT is a sign of atherosclerosis, a buildup of plaque in the carotid artery.
Factors that can increase IMT:
* Age
* High blood pressure
* High cholesterol
* Smoking
* Diabetes
* Family history of heart disease
In some cases, an increased IMT may require treatment with surgery to remove plaque from the arteries.
More about IMT:
* IMT is a screening test, not a diagnostic test. If IMT is increased, it does not mean atherosclerosis. However, an increased IMT is a risk factor for atherosclerosis, and it can help identify people who are at increased risk of developing heart disease or stroke.
* IMT can change over time. If you have an increased IMT, it is important to have your IMT checked regularly to see if it is getting worse.
Normal spectral Doppler parameters:
Common carotid artery:
* Peak systolic velocity (PSV): <125 cm/s
* End diastolic velocity (EDV): <40 cm/s
* Pulsatility index (PI): <2.0
Internal carotid artery:
* PSV: 40-80 cm/s
* EDV: 20-40 cm/s
* PI: 1.0-2.0
External carotid artery:
* PSV: 50-100 cm/s
* EDV: 20-40 cm/s
* PI: 1.5-2.5
Vertebral arteries:
* PSV: 50-100 cm/s
* EDV: 20-40 cm/s
* PI: 1.5-2.5
Differences ECA and ICA:
The normal spectral Doppler waveform of the external carotid artery (ECA) and internal carotid artery (ICA) are different. The ECA has a higher resistance waveform with less diastolic flow than the ICA.
The ICA has a low resistance waveform with continuous forward diastolic flow. This is because the ICA supplies blood to the brain, which has a low resistance vascular bed. The ECA supplies blood to a variety of tissues, including the face, scalp, and neck, which have a higher vascular resistance.
Vertebral arteries:
The direction of flow in the normal vertebral and common carotid arteries on color Doppler ultrasound is antegrade, meaning that the blood is flowing towards the head. This is because the vertebral and common carotid arteries supply blood to the brain.
In some cases, the direction of flow in the vertebral and common carotid arteries may be reversed. This is called retrograde flow and it can be a sign of a problem, such as a stenosis or occlusion of an artery.
It is important to note that the direction of flow in the vertebral and common carotid arteries can be affected by a number of factors, such as the patient's position, the angle of the ultrasound beam, and the presence of atherosclerotic plaque.
More details:
Vertebral arteries: The vertebral arteries are a pair of arteries that supply blood to the brainstem and cerebellum. The direction of flow in the vertebral arteries is always antegrade.
However, in some cases, the direction of flow in the vertbral artery may be reversed. This is called subclavian steal syndrome; and it occurs when there is a stenosis or occlusion of the subclavian artery. In subclavian steal syndrome, blood flows retrograde from the vertebral artery to the subclavian artery in order to supply blood to the arm.
Common carotid arteries: The common carotid arteries are a pair of arteries that supply blood to the head and neck. The direction of flow in the common carotid arteries is usually antegrade.
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