Neck CT Scan Procedure and Protocol

Thursday, November 17, 2016

Neck CT scan Protocols

Routine scanning of the neck is typically performed with the patient supine and the neck slightly extended. It is most often performed in the helical mode. To reduce artifacts that degrade images in the lower neck, the patient should be instructed to lower the shoulder as much as possible. In some cases and institution scanning of the neck are acquired while the patient performs a modified Vasalva maneuver. This maneuver requires the patient to blow the chest out. This technique helps to distend the pyriform sinuses. Another technique that has been used to evaluate the aryepiglottic folds and pyriform sinuses is to ask the patient to pronounce a prolonged “e” during scanning.

Neck CT Scan with Contrast

Unless contraindicated, intravenous contrast media is used when scanning the neck. The goals in CT scanning of the neck are to allow sufficient time after contrast administration for mucosa, lymph nodes, and pathologic tissue to enhance, yet acquire images while the vasculature remains opacified. Scanning too early after the contrast media injection could result in certain types of neoplastic and inflammatory processes going undetected. However, by delaying scan acquisition the injected contrast agent will no longer opacify the vasculature.

Spit Bolus Technique

One strategy for addressing these contradictory goals is a contrast injection technique is a contrast injection technique referred to as spit bolus technique. The total contrast dose is spit, often in half. The first dose is given and a delay of about 2 minutes is observed. This duration allows time for structures that are slower to enhance to be opacified. The delay is followed by a second bolus containing the remainder of the contrast. Scanning is initiated soon after the second injection is complete, using this second injection to more fully opacify the vessels. The split bolus injection technique is also frequently used for maxillofacial studies in which contrast media is indicated.

Computed Tomography of the Neck

Unless contraindicated, CT examination of the neck are done with the IV administration of contrast media. Artifacts caused by dental work often obscure surrounding structures at some levels. Some facilities split the data acquisition into two groups so that the gantry can be angled to reduce artifact. However, many MDCT systems do not allow the gantry to be angled in the helical mode, so this is not always possible.