Computed tomography angiography (CTA) and, to a slightly lesser extent, magnetic resonance angiography (MRA) are now the preferred modalities in the assessment of the thoracic aorta given superior anatomic accuracy, capacity to discern relevant complications, and ability to infer dynamic vascular information [36]. Catheter angiography has largely been replaced by CTA and MRA for diagnostic evaluation but remains a useful tool in cases where acute intervention is required. Ultrasound (US), echocardiography, radiography, and select nuclear medicine studies currently play an adjunctive role in the evaluation and follow-up of thoracic aortic disease and are principally utilized to answer specific anatomic and prognostic questions. A variety of factors contributes to the appropriateness of each imaging study, including acuity of the pathologic process, planned intervention, patient age, medical comorbidities, and endograft composition. For the purposes of distinguishing between CT and CTA, ACR AC topics use the definition in the Practice Parameter for the Performance and Interpretation of Body Computed Tomography Angiography (CTA) [37]: All elements are essential: 1) timing, 2) reconstructions/reformats, and 3) 3-D renderings. Standard CTs with contrast also include timing issues and reconstructions/reformats. Only in CTA, however, is 3-D rendering a required element. This corresponds to the definitions that the Centers for Medicare & Medicaid Services has applied to the Current Procedural Terminology codes. Discussion of Procedures by Variant Variant 1: Planning for pre-thoracic endovascular repair (TEVAR) of thoracic aorta disease. CTA Multidetector CT is the imaging modality of choice for preoperative assessment before TEVAR because of short scan times and superior spatial and temporal resolution [38,39]. CTA is unmatched in its ability to provide isotropic data as well as robust and homogeneous intraluminal contrast enhancement [36].
Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up. Computed tomography angiography (CTA) and, to a slightly lesser extent, magnetic resonance angiography (MRA) are now the preferred modalities in the assessment of the thoracic aorta given superior anatomic accuracy, capacity to discern relevant complications, and ability to infer dynamic vascular information [36]. Catheter angiography has largely been replaced by CTA and MRA for diagnostic evaluation but remains a useful tool in cases where acute intervention is required. Ultrasound (US), echocardiography, radiography, and select nuclear medicine studies currently play an adjunctive role in the evaluation and follow-up of thoracic aortic disease and are principally utilized to answer specific anatomic and prognostic questions. A variety of factors contributes to the appropriateness of each imaging study, including acuity of the pathologic process, planned intervention, patient age, medical comorbidities, and endograft composition. For the purposes of distinguishing between CT and CTA, ACR AC topics use the definition in the Practice Parameter for the Performance and Interpretation of Body Computed Tomography Angiography (CTA) [37]: All elements are essential: 1) timing, 2) reconstructions/reformats, and 3) 3-D renderings. Standard CTs with contrast also include timing issues and reconstructions/reformats. Only in CTA, however, is 3-D rendering a required element. This corresponds to the definitions that the Centers for Medicare & Medicaid Services has applied to the Current Procedural Terminology codes. Discussion of Procedures by Variant Variant 1: Planning for pre-thoracic endovascular repair (TEVAR) of thoracic aorta disease. CTA Multidetector CT is the imaging modality of choice for preoperative assessment before TEVAR because of short scan times and superior spatial and temporal resolution [38,39]. CTA is unmatched in its ability to provide isotropic data as well as robust and homogeneous intraluminal contrast enhancement [36].