AAAs can be incidentally diagnosed on both contrast- and noncontrast-enhanced CT scans performed for various other clinical indications [4,5,21-23]. In determining maximum aortic diameter on CT, the OTO aortic diameter perpendicular to the long axis of the aorta is recommended [7]. This is obligatory for noncontrast CT images in which the aortic wall and lumen cannot be distinguished. Noncontrast CT has been found to be more sensitive than ultrasound (US) in identifying AAAs [24]. CTA Abdomen and Pelvis CTA abdomen and pelvis with IV contrast and CTA abdomen and pelvis without and with IV contrast provide rapid image acquisition of submillimeter, isotropic, 3-D data sets of the aorta and its branch vessels with high spatial resolution [25-27]. Measurement of the maximal aortic diameter based on the OTO wall diameter perpendicular to the long axis of the aorta on CTA is considered the reference standard for AAA diagnosis and management decision making [7]. CTA is also the imaging procedure of choice for preoperative assessment before endovascular or open surgical repair [10,13,26,28]. The scan range should include the iliofemoral arteries to evaluate the access vessels and also the chest in patients with thoracoabdominal AAA. Pulsatile Abdominal Mass CT, preferably CTA, is recommended for evaluation of symptomatic patients who present with acute onset abdominal or back pain, particularly in the presence of a pulsatile abdominal mass or significant risk factors for AAA [7]. Whether CTA should be the initial imaging modality used for evaluation of asymptomatic patients suspected to have an AAA is less clear. Dual-energy CTA, which allows for simultaneous acquisition of CT data with 2 different photon energy spectra, can be used to characterize AAAs with reduced IV iodinated contrast dose without compromising imaging quality [29,30].
Pulsatile Abdominal Mass Suspected Abdominal Aortic Aneurysm. AAAs can be incidentally diagnosed on both contrast- and noncontrast-enhanced CT scans performed for various other clinical indications [4,5,21-23]. In determining maximum aortic diameter on CT, the OTO aortic diameter perpendicular to the long axis of the aorta is recommended [7]. This is obligatory for noncontrast CT images in which the aortic wall and lumen cannot be distinguished. Noncontrast CT has been found to be more sensitive than ultrasound (US) in identifying AAAs [24]. CTA Abdomen and Pelvis CTA abdomen and pelvis with IV contrast and CTA abdomen and pelvis without and with IV contrast provide rapid image acquisition of submillimeter, isotropic, 3-D data sets of the aorta and its branch vessels with high spatial resolution [25-27]. Measurement of the maximal aortic diameter based on the OTO wall diameter perpendicular to the long axis of the aorta on CTA is considered the reference standard for AAA diagnosis and management decision making [7]. CTA is also the imaging procedure of choice for preoperative assessment before endovascular or open surgical repair [10,13,26,28]. The scan range should include the iliofemoral arteries to evaluate the access vessels and also the chest in patients with thoracoabdominal AAA. Pulsatile Abdominal Mass CT, preferably CTA, is recommended for evaluation of symptomatic patients who present with acute onset abdominal or back pain, particularly in the presence of a pulsatile abdominal mass or significant risk factors for AAA [7]. Whether CTA should be the initial imaging modality used for evaluation of asymptomatic patients suspected to have an AAA is less clear. Dual-energy CTA, which allows for simultaneous acquisition of CT data with 2 different photon energy spectra, can be used to characterize AAAs with reduced IV iodinated contrast dose without compromising imaging quality [29,30].