Clinical Scanning: Cervical Vascular Ultrasound and Anatomy
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Cervical Vascular Anatomy
Common Carotid Artery: The main arterial trunk of the head and neck, with one on each side (left and right). The dilated upper end of the common carotid artery divides into the internal carotid artery and the external carotid artery.
The internal jugular vein is the largest venous trunk in the neck. Superiorly, it is continuous with the sigmoid sinus in the cranial cavity at the jugular foramen. It travels together with the internal carotid artery and the common carotid artery within the carotid sheath. Inferiorly, it unites with the subclavian vein behind the sternocleidomastoid joint to form the brachiocephalic vein.
After arising from the common carotid artery, the external carotid artery initially lies medial to the internal carotid artery, then passes anterior to the internal carotid artery and curves around to its lateral side. It mainly supplies blood to the facial and scalp tissues.
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Examination Methods and Sections
1. The patient is placed in a supine position with a pillow under the neck and the head tilted back to expose the neck. A 7 MHz–10 MHz linear array probe is selected.
2. For routine two-dimensional detection, start the examination from the root of the neck, and then inspect the common carotid artery (CCA), internal carotid artery (ICA), and external carotid artery (ECA) in sequence upward, probing as far as possible to the highest point of the neck.
3. Measure the vascular inner diameter in the transverse section.
4. Observe the changes in the vascular wall and whether there are morphological abnormalities such as plaques, stenosis, and occlusion in the lumen.
5. Measure the size of the residual lumen and calculate the percentage of area stenosis.
6. Longitudinal scanning of cervical blood vessels (the head is turned to the opposite side, and the probe is placed on the anterior or posterior side of the neck for anterior and posterior lateral longitudinal scanning).
7. Measure the intima-media thickness (IMT) in the longitudinal section.
8. Measure the length and thickness of the plaque, and observe its surface and internal characteristics.
9. Color Doppler Flow Imaging (CDFI): Under the display of two-dimensional real-time images, observe the blood flow direction, properties (laminar flow, turbulent flow, and vortex flow), as well as the presence of filling defects, stenosis, blood flow interruption, and regurgitation.
10. Place the sample volume at the center of the blood vessel to be examined, and the angle between the ultrasound beam and the blood flow direction should be < 60°. After the spectrum is displayed, continuously observe 20–30 cardiac cycles. Adjust the sample volume to the optimal size and minimize the angle. After determining the clearest blood flow velocity spectrum curve, observe the morphology of the velocity curves of the CCA and ICA, and measure the blood flow parameters: systolic peak velocity (SPV), end-diastolic velocity (EDV), and calculate the resistance index (RI).
11. Observe the blood flow filling status and the location of stenosis or occlusion; measure the percentage of diameter stenosis.
12. An appropriate room temperature must be maintained during vascular ultrasound examination. Excessively low room temperature can cause vasoconstriction and affect the examination results.
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Sonographic Findings
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Key Points of Detection
Measurement of Intima-Media Thickness (IMT): The normal IMT of the carotid artery is less than 1 mm, and that at the dilated segment is less than 1.2 mm. A thickness greater than this indicates early atherosclerosis.
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Clinical Significance
Ultrasound examination can objectively evaluate the location, scope, severity of cervical vascular lesions, as well as extracranial cerebral circulation abnormalities.
1. Evaluate the normal anatomical structure and hemodynamic information of cervical blood vessels, including whether the vascular course is normal, and whether there is dilation, stenosis, tortuosity or compression of the lumen.
2. Evaluate the changes in vascular structure and hemodynamics caused by carotid artery stenosis or occlusive lesions due to various reasons, such as the presence of intima-media thickening or plaque formation, evaluation of plaque stability, and grading of the degree of arterial stenosis.
3. Evaluate the position, expansion degree, residual stenosis of the stent after interventional treatment for carotid artery stenosis, as well as the related anatomical structure and hemodynamic changes after treatment.
4. Detect the changes in vascular structure and hemodynamics such as aneurysms and arteriovenous fistulas.