Synonyms Helical CT; Spiral CT

Replaces While it does not replace other CT examinations it may be indicated in some clinical situations. Indications are at the discretion of the diagnostic radiologist. The advantages of this technology include shortened examination time, improved visibility of vascular structures, better enhancement of parenchymal organs, and improved image reformatting.

Procedure Commonly Includes Conventional CT generates single section scan punctuated by an inter scan delay to facilitate patient respiration. Spiral CT is characterized by high speed scanning and continuous table motion allowing continuous data acquisition over a variable length of the patient's torso during a single breath hold.

Indications The improved visibility of vascular structures has led to application of this technique in the evaluation of the pulmonary arteries (identification of a central embolic disease), the thoracic and abdominal aorta (diagnosis of aortic dissection and aneurysmal dilatation). The technique has also been applied to evaluation of the pancreas, the portal venous system, the carotid arteries, and the staging of pediatric neoplasms.

Contraindications Patient cooperation is of the utmost importance

Patient Preparation The reader is referred to patient preparation for the area of anatomic interest (eg, for liver, see Computed Transaxial Tomography, Abdominal Studies).

Equipment Only those standard commercial available CT scanners with spiral/helical scanning capabilities

Technique The technique will vary depending on the area to be examined. Care must be taken to ensure the correct temporal window between delivery of contrast material and commencement of scanning. The speed of table motion is another variable to be considered when tailoring the examination.

References