MDCT of the abdominal aorta: basics, technical improvements, and clinical applications

Conclusion

Multiple diagnostic techniques have been proposed for the evaluation of the abdominal aorta and iliac arteries so as to avoid the use of DSA.

The development of MDCT has improved the assessment of the aorta and its branches allowing increasingly faster acquisition of thin sections. The increasing speed of the acquisition requires more attentive administration of iodinated contrast agent, at higher flow rates and with higher iodine concentration so that a homogeneous enhancement throughout the acquisition is achieved. Compared to other techniques, MDCT angiography has several advantages related to transverse data acquisition and the possibility of performing multiplanar interactive reconstructions. Furthermore, the rapid diffusion of MDCT scanners worldwide, not followed by the diffusion of high-field-strenght MR systems, enable to perform high quality MR angiography, has allowed an increasing number of CT angiography examinations to be performed.

There are two major limitations of MDCT angiography in the evaluation of patients with peripheral arterial disease: the use of ionizing radiation and iodinated contrast agents. Regarding the radiation issue, it has been recently noted that it is not that important in older individuals who are the typical patients with peripheral arteriopathy, and that the radiation dose, compared with that of DSA, is significantly lower. Furthermore, as shown in other areas, it might be possible to reduce the radiation dose to the patient by optimizing the acquisition protocol. Concerning the use of iodinated contrast agents, it must be noted that several patients present with poor renal function and cannot tolerate administration of a possibly nephrotoxic agent; nevertheless, the nephrotoxicity of nonionic contrast agents has been significantly reduced as compared with ionic contrast agents and their administration can be considered safe and well tolerated, even in high-risk populations. Furthermore, the amount of iodinated contrast agent needed for MDCT angiography is significantly lower than that of single-slice spiral CT angiography, and the further increase in speed of new multidetector-row CTs will allow the use of even smaller amounts.