The CTA 3-D data set can be postprocessed and manipulated perpendicular to the flow lumen, allowing for accurate measurements for longitudinal evaluation of aortic growth and lumen diameters as well as planning for endovascular or surgical treatment [87,94,95]. Even though the maximum diameter of the aorta is the most consistent predictor of future rupture, other CTA findings, such as luminal contrast heterogeneity, intraluminal thrombus volume, aortic wall distensibility, and aneurysm geometry, help identify patients at risk for rupture [96-98]. Geometric models from CTA examinations can be used to create computational flow dynamics, which may also be useful in identifying patients with thoracic aortic aneurysms who are at risk for rupture [99]. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature for the use of FDG-PET/CT imaging as an initial evaluation of degenerative or atherosclerotic aortic diseases. MRA Chest and Abdomen Similar to MRA without IV contrast, MRA without and with IV contrast can be used to obtain hemodynamic information about aortic aneurysms from computational flow dynamics or 4-D flow MRI [99]. The addition of IV contrast improves visualization of the aorta and great vessels and decreases overall acquisition time [100-104]. However, there is no definitive evidence that the addition of IV contrast improves the overall accuracy of MRA for degenerative aortic diseases. MRI without IV contrast using double-inversion recovery T1-weighted imaging and balanced steady-state free- precession MRA allows for imaging of the aorta, especially when acquisition is ECG-gated [105]. The accuracy of balanced steady-state free-precession MRA is close to 100% for detecting thoracic aortic aneurysm, dissection, intramural hematoma, and penetrating aortic ulcer when measured against the reference standard of MRA with IV contrast material [101,106]. It can be used to evaluate the entire thoracic aorta and its branches [107].
Nontraumatic Aortic Disease. The CTA 3-D data set can be postprocessed and manipulated perpendicular to the flow lumen, allowing for accurate measurements for longitudinal evaluation of aortic growth and lumen diameters as well as planning for endovascular or surgical treatment [87,94,95]. Even though the maximum diameter of the aorta is the most consistent predictor of future rupture, other CTA findings, such as luminal contrast heterogeneity, intraluminal thrombus volume, aortic wall distensibility, and aneurysm geometry, help identify patients at risk for rupture [96-98]. Geometric models from CTA examinations can be used to create computational flow dynamics, which may also be useful in identifying patients with thoracic aortic aneurysms who are at risk for rupture [99]. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature for the use of FDG-PET/CT imaging as an initial evaluation of degenerative or atherosclerotic aortic diseases. MRA Chest and Abdomen Similar to MRA without IV contrast, MRA without and with IV contrast can be used to obtain hemodynamic information about aortic aneurysms from computational flow dynamics or 4-D flow MRI [99]. The addition of IV contrast improves visualization of the aorta and great vessels and decreases overall acquisition time [100-104]. However, there is no definitive evidence that the addition of IV contrast improves the overall accuracy of MRA for degenerative aortic diseases. MRI without IV contrast using double-inversion recovery T1-weighted imaging and balanced steady-state free- precession MRA allows for imaging of the aorta, especially when acquisition is ECG-gated [105]. The accuracy of balanced steady-state free-precession MRA is close to 100% for detecting thoracic aortic aneurysm, dissection, intramural hematoma, and penetrating aortic ulcer when measured against the reference standard of MRA with IV contrast material [101,106]. It can be used to evaluate the entire thoracic aorta and its branches [107].