Indications for and experience with placement of endovascular stent grafts in the thoracic aorta are still evolving. Recent advances in imaging technologies have drastically boosted the role of pre-procedural imaging. The accepted diagnostic gold standard, digital subtraction angiography, is now being challenged by the state-of-the-art computed tomography angiography (CTA), magnetic resonance angiography (MRA) and trans-oesophageal echocardiography (TEE). Among these, technological advancements of multidetector computed tomography (MDCT) have propelled it to being the default modality used, optimising the balance between spatial and temporal resolutions and invasiveness. MDCT angiography allows the comprehensive evaluation of thoracic lesions in terms of morphological features and extent, presence of thrombus, relationship with adjacent structures and branches as well as signs of impending or acute rupture, and is routinely used in these settings. In this article, we review the current state-of-the-art radiological imaging for thoracic endovascular aneurysm repair (TEVAR), especially focusing on the role of MDCT angiography. After analysing the technical aspects for optimised imaging protocols for thoracic aortic diseases, we discuss pre-procedural determinants of candidacy, and how to formulate interventional plans based on cross-sectional imaging.

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We would like to congratulate the authors on their review of imaging for thoracic aortic disease. 1 However, we would like to comment on the section regarding dissection. Multidetector contrast-enhanced computed tomography (CT) remains the most widely available modality for imaging patients with this disease, but has some limitations which may be misleading. The images acquired are a representation of one moment in the cardiac cycle and these static images may not illustrate the complex anatomical and functional changes occurring in aortic dissection. The dimensions of the true and false aortic lumens will vary with systole and diastole and this will have an effect on factors such as device sizing and determining dynamic from static obstruction. Magnetic resonance imaging (MRI) with ECG-gating is able to give static and dynamic high-resolution information in a single examination.False lumen thrombosis is accepted as an important factor in determining the prognosis of patients presenting with dissection, and is diagnosed on CT by the absence of contrast in the false lumen on first pass imaging. 2 A delayed second scan may detect late enhancing structures but the ideal timing for this will be related to both the cardiac output and local flow conditions.MRI is able to deliver anatomical and functional information in a single scan and compared with multidetector contrast-enhanced CT and has the added benefit of not using ionising radiation. The next generation of endoluminal devices will be more conformable to the aortic arch and MRI generated data will allow the use of shorter endoluminal devices in patients requiring intervention.

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