6533b824fe1ef96bd1280961

RESEARCH PRODUCT

Helical computed tomographyangiography: Technical considerations and clinical applications

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Abstract A combination of volume acquisition techniques (helical CT), dedicated protocolsfor bolus injections of contrast medium, and postprocessing modalities have paved the way for computed tomography (CT) angiography. To obtain optimum results the collimation must be adapted to the vascular territory of interest, and the reconstruction of overlapping source images from the volume data set is advantageous for further postprocessing. Strong intravascular opacification is indispensable for the evaluation of vascular abnormalities and pathology and is also helpful for image postprocessing, where different modalities can be applied: multiplanar reconstruction, maximum intensity projection, segmentation and 3-D reconstruction. The technique yielding the best results varies according to the vascular territory to be examined. Acquisition and injection protocols for the most important regions (intracranial vessels, carotid, pulmonary and renal arteries, aorta and iliac arteries) are presented. Helical CT angiography (CTA) is now an established modality for the renal and pulmonary arteries as well as the aorta and the iliac arteries. CTA compares reasonably well with angiography, which is invasive. Thus, CTA can be recommended as a screening tool for renal artery stenosis, pulmonary embolism and stenosis or occlusion of the carotids.