Sectional Anatomy Neck Vasculature

Objectives List vessels found in the neck region Identify the locations of and relationships between neck vasculature Differentiate between neck and spine scans After watching this presentation, you should be able to: List vessels found in the neck region Identify the locations of and relationships between neck vasculature Differentiate between neck and spine scans

Neck Imaging AP and lateral scout images are typically obtained when performing a scan of the neck or cervical spine. This is an AP scout image.

Neck Imaging This is a lateral neck scout image. The reference lines have been placed identifying that the scan begins above the level of the EAM and concludes when through the thoracic inlet or lung apices. Notice that there are also angled slices that will be completed at the end of the scan. These slices are angled to minimize streak artifact coming from the metal present in the patient’s dental work. Often times, there will be scans angled in both cephalic and caudal directions depending upon the radiologist’s preferences and exam protocol design.

Neck vs. Cervical Spine Neck Spine Before evaluating neck vasculature, let’s first differentiate between soft tissue neck and cervical spine scans. A soft tissue neck CT is often performed to evaluate enlarged lymph nodes or lymphadenopathy. A patient may palpate a lump in the soft tissue of the neck, or a lump is identified upon physical examination by a physician. If a patient has soft tissue swelling or a possible abscess, a soft tissue neck scan is needed to evaluate the extent of infection and the patency of the airway. Often times, an abscess can impede the airway, the patient will be intubated, and the abscess is drained. Cervical spine scans are performed following trauma. In many facilities, trauma c-spine x-rays are completed first followed by a CT. Fracture and subluxation are often reasons for performing a cervical spine CT. One defining difference between a soft tissue neck and cervical spine CT is the use of contrast media. An injection of intravenous contrast media is used for a soft tissue neck to opacify vessels, identify masses, locate abscesses, and display lymphadenopathy. Cervical spine scans do not use a contrast injection because bone is the primary area of interest when evaluating for fracture or subluxation. Neck Spine

Neck Vasculature Vertebral Arteries Carotid Arteries Internal/External Carotid Arteries Internal/External Jugular Veins There are numerous anatomical structures presented in a soft tissue neck including muscles, salivary glands, bony landmarks, and vasculature. This presentation will focus on the main vessels demonstrated in a soft tissue neck following the injection of contrast media. Identifying neck vasculature and understanding their spatial relationships is essential when completing CTA or angiography studies. Often times, the radiologic technologist may utilize specialized software, such as Smart Prep in GE scanners, to ensure an optimal bolus of contrast will be in the area of interest. This requires the technologist to recognize where these vessels are located to set up the scan for peak enhancement in the vasculature. In this presentation, we will identify the vertebral and carotid arteries. Additionally, we will recognize branches from the carotid arteries including the internal and external carotids. Finally, we will locate the internal and external jugular veins which are important to venous circulation.

A CT soft tissue neck typically begins superior to the level of the EAM. All areas of the pharynx are included on a soft tissue neck scan beginning with the nasopharynx. The vertebral arteries labeled with blue arrows ascend up the neck via the transverse foramina in the cervical spine. These vessels contribute to the posterior blood circulation in the brain. The internal jugular vein is a major vessel accepting venous drainage from the dural sinuses in the brain. In the chest, the internal jugular veins merge with the brachiocephalic veins to become the superior vena cava. The internal jugular vein is noted by the green arrow in this image. Adjacent to the internal jugular vein is the internal carotid artery marked with a yellow arrow. The internal carotid artery is an essential vessel comprising the Circle of Willis in the brain.

As the scan moves inferiorly down the neck, the vertebral arteries, identified with a blue arrow, assume their place within the transverse foramina of the cervical spine. The external jugular vein is laterally placed in reference to the sternocleidomastoid muscle. It is identified with the black arrow on the image. The external and internal carotid arteries along with the internal jugular vein have a close association with one another as demonstrated on this image. These vessels are presented in a row with the internal jugular appearing as the largest of the three vessels. On this image, the external carotid artery is displayed with a purple arrow, the internal carotid artery is in the center with the yellow arrow, and the internal jugular vein is most lateral of the three in this axial image identified with a green arrow.

In this image, the external carotid and internal carotid arteries along with the internal jugular vein are well demonstrated and opacified with contrast. The internal carotid artery is in the middle of the three vessels marked with a yellow arrow. Other structures of interest are the mandible creating the anterior aspect of the image and the cervical vertebra forming the posterior aspect of the image. Additionally, the epiglottis and oropharynx are demonstrated at the midline of the image.

The internal and external carotid arteries are demonstrated on this image along with the internal jugular vein. Remember, the internal jugular appears the largest of the three vessels and the internal carotid artery is centrally placed between the external carotid artery and internal jugular vein. This image is at the level of the oropharynx. The tongue is visualized along with a portion of the mandible anteriorly. The vertebral arteries are seen on each side of the cervical vertebral body, located within the transverse foramina of the cervical spine.

In this image, the last part of the pharynx, the larynx, is visualized In this image, the last part of the pharynx, the larynx, is visualized. The thyroid cartilage is seen encasing the area of the larynx. The common carotid artery, marked with a red arrow, has replaced the internal and external carotid arteries in this image. The common carotid arteries bifurcate into the internal and external carotids at approximately the fourth cervical vertebra. Since the internal and external carotid arteries are not visualized, the scan is inferior to the level of this bifurcation.

The larynx with surrounding cricoid cartilage is viewed anteriorly and the trapezius muscle helps to form the posterior aspect of this image. Again, the internal jugular vein and common carotid artery is within view. Forming the perimeter around these vessels are the sternocleidomastoid muscle and the thyroid gland.

For this image, the air-filled trachea is an anteriorly placed at the midline. Notice the proximity of the thyroid gland to the trachea. If a patient has a thyroid mass, the trachea could appear compressed or deviated. The internal jugular vein, noted with a green arrow, and the common carotid artery, identified with the red arrow, are seen side by side. When in the thorax, the internal jugular and subclavian veins merge to form the brachiocephalic veins bilaterally. The right and left brachiocephalic veins will then merge together forming the superior vena cava which will empty into the right atrium of the heart. As the scan moves inferiorly, it is noted that the cervical spinous processes become longer in appearance as there is a transition into the cervicothoracic region.

This image demonstrates the internal jugular vein noted with a green arrow in close proximity with the common carotid artery identified with the red arrow. Other anatomical landmarks include the air-filled trachea and the thyroid gland located anteriorly on this axial image. The soft tissue neck continues inferiorly through the thoracic inlet until the lung apices are well within view.

Reformatted Coronal Images CT images are primarily completed in the axial or transverse plane. Images are routinely formatted into coronal and sagittal images, providing the radiologists a multiplanar view of anatomical structures. These images are coronal reformats of a soft tissue neck. Reformatting the transverse or axial images does not require additional radiation dose to patients. The patient is scanned one time and the images are post processed into multiple anatomical planes.