CT Artifacts of the Proximal Aortic Neck:An Important Problem in Endograft Planning

Computed tomography scanning for endograft planning: evolving toward three-dimensional, single source imaging

One of the most fundamental differences between open surgical repair of aortic aneurysms and treatment by endograft exclusion is the dependency on imaging for all critically important aspects of the endovascular approach. Patient selection and preprocedure planning for device selection and sizing depend on imaging. Computed tomography (CT) scanning for endograft planning is capable of providing accurate and complete measurement data. There are problems with diameter, length, and angulation measurement when using conventional two-dimensional (2D) axial CT images that can be partly overcome by expert interpretation. However, when computerized 3D programs that include easy-to-use measurement tools process CT data, the problems of 2D CT scan data are relieved. In addition, virtual simulation of various endograft choices can be modeled within computerized renderings of patient-specific anatomy that allow testing of alternatives and provide an intuitive understanding during the planning phase.

Prediction of aortoiliac stent graft length: comparison of a semiautomated computed tomography angiography method and calibrated aortography

OBJECTIVE

The aim of this study is to compare multislice computed tomography (MSCT) in combination with a newly developed semiautomated software program with calibrated aortography in patients who are scheduled for endovascular aortic stent graft placement.

METHODS

From November 2000 until December 2001, seven patients with an abdominal aortic aneurysm (AAA) underwent both calibrated aortography and MSCT for preoperative endovascular stent graft planning. Both studies were performed within 14 days. Further, length measurements were performed with a semiautomated computerized tomographic angiography (CTA) calibration method and a conventional calibrated aortography technique using three differently configured tubes with variable tortuosity. The AAA length measurements of the semiautomated CTA calibration method and the calibrated aortography were compared.

RESULTS

Statistical analysis included linear regression analysis and revealed a probability value of 0.000381 and an r2 value of 0.93. Using phantoms, it is proven by the authors that the accuracy of the semiautomated CTA calibration method increases with increasing tortuosity when compared with the conventional calibrated aortography technique.

CONCLUSIONS

Our preliminary results show that the semiautomated CTA calibration method has a potentially advantageous role in preoperative stent graft planning regarding the aortic length measurements and seems to be more accurate than calibrated aortography, especially in extremely tortuous vessels. Further studies have to be performed, however.