CT and MR imaging prior to transcatheter aortic valve implantation: standardisation of scanning protocols, measurements and reporting—a consensus document by the European Society of Cardiovascular Radiology (ESCR)

Fig. 1. CT images of a Medtronic self-expandable Corevalve (a) and Edwards Lifesciences balloon-expandable Sapien valve (d). After deployment, a self-expandable valve will conform itself to the normal annular contour, acquiring an oval cross-sectional morphology (b). Compared with a balloon-expandable valve, the self-expandable Corevalve is larger in size and contains an inflow (I), waist (w), and outflow (O) functional part (c). This outflow part is by design intended to extend into the ascending aorta, covering but not obstructing the coronary ostia. The balloon-expandable Sapien valve (d) is shorter, with a mostly circular cross-sectional contour after deployment (e) as it forces this circular morphology on the annulus through the radial forces of the expanding balloon. In contrast to the self-expandable Corevalve, it remains within the aortic sinus (f). Within both THVs, the pericardial leaflets can be appreciated as fine hypodense linear structures (arrowheads in c, f), its visibility dependent on image quality. Small interposing calcifications (arrows in b, e) have in these examples only a minimal effect on THV expansion. Reused from reference [40], with permission

Fig. 2. 3D volume rendering CT image of the heart containing the aortic root. The aortic root has a double-oblique orientation within the heart. Therefore, standard orthogonal imaging planes, like the axial plane indicated with the dotted white line, are not suitable to correctly visualise the aortic root and containing structures. For this reason, intrinsic 3D imaging modalities like CT are necessary to correctly assess the aortic root and annulus and obtain accurate measurements

Fig. 3. The aortic sinus contains the aortic valve, in most patients composed of three leaflets (asterisk in a, coloured dotted lines in b, c). They are named according to the adjacent sinus of Valsalva (a): right coronary sinus (red), left coronary sinus (green) and non-coronary sinus (blue). As such, we distinguish (b, c) a right coronary cusp (red), left coronary cusp (green) and non-coronary cusp (blue). The dotted dark blue line in (c) indicates the sinotubular junction, marking the roof of the aortic sinus

Fig. 4. Most TAVI candidates will present with an aortic valve containing significantly calcified valve leaflets. The majority of patients will have a clearly identifiable tricuspid aortic valve (a). However, a significant portion will have a bicuspid aortic valve, which is an important feature to report as its presence is associated with some specific complications. However, in some cases, valve cuspidity can be difficult to assess in heavily degenerated valves, where extensive calcification can make differentiation between tricuspid and (functionally) bicuspid valves difficult (b)

Fig. 5. Incomplete and asymmetric deployment of a self-expandable THV due to interposition of extensive native leaflet calcifications (arrow in a, b) between the prosthetic valve and the wall of the aortic sinus. Severe calcifications can complicate prosthesis deployment as in this case, leading to a deformed THV. Nevertheless, caution should be taken when extrapolating morphological findings into a potential dysfunction. While in this case the residual gap between the THV and the aortic wall would suggest a severe paravalvular leakage, this was not the case on Doppler echocardiography examination, with the calcification apparently acting as an additional seal. Valvular function was acceptable, and no further intervention was deemed necessary

Fig. 6. Incorrect positioned THV, which is tilted and does not fully extend into the aortic annulus. As such, parts of the native right aortic valve leaflet is protruding into the inflow part of this self-expandable THV (arrow), causing a residual valve gradient on Doppler echocardiography. CT is very useful in detecting the cause of THV dysfunction in cases where Doppler echocardiography does not provide an answer. In this case, function was improved after balloon dilatation of the inflow part of the THV, further crushing the remaining valve leaflets against the adjacent aortic wall

Fig. 7. Relation between the coronary ostia and the deployed THV. Both self-expandable and balloon-expandable THVs are designed not to obstruct the coronary ostia, with self-expandable Corevalve and Evolut protheses extending into the ascending aorta by design, leaving the coronary ostia open (a, b). When coronary obstruction occurs, it is not by the THV but secondary to displaced calcified native leaflet remnants that migrate during deployment of the THV in the aortic sinus to the vicinity of the coronary ostia. Nevertheless, while CT can detect these migrated calcifications in or near the coronary ostia (c), the evaluation of luminal patency is less obvious, mostly dependent on local expertise and the quality of the CT scanner used

Fig. 8. CT images of the aortic valve illustrating different degrees of valvular calcification depositions: none (a), mild (b), moderate (c) and severe (d). Also note the differences in the affected cusps and distribution (leaflet edges, commissures and attachment sites)

Fig. 9. Double-oblique CT image of the aortic root in a TAVI candidate. While most calcification will be on a supra-annular level (arrowhead), occasionally, calcifications can also be found on an infra-annular subvalvular level (arrow). Reporting of these latter calcifications is important, as they can hamper proper deployment and attachment of the prothesis

Fig. 10. 3D CT image of the aortic root containing the sinuses of Valsalva (asterisk). As the aortic valve leaflets extend within these sinuses up to the sinotubular junction, connecting their most basal attachment sites forms a virtual ring which is named the aortic annulus (red dotted line, arrows). It also marks the transition to the LVOT

Fig. 11. a Schematic drawing illustrating the crownlike suspension of the aortic valve leaflets within the aortic root extending across the length of the aortic sinus (a). AR, virtual annular ring representing the annulus (green), formed by joining the basal attachments of the aortic valve leaflets; STJ, sinotubular junction (blue); VAJ, ventriculo-arterial junction (yellow). Red, aortic leaflet insertion sites in the sinus of Valsalva forming a crownlike ring. b Coronal contrast-enhanced CT image demonstrates the levels of the sinotubular junction (STJ) (blue line), ventriculo-arterial junction (VAJ) (yellow line) and annular ring (AR) (green line). Double-headed arrow, anatomic range of the sinuses of Valsalva. CAU, caudal; CRA, cranial. c–f Double-oblique reformatted images further clarify the changing shape of the aortic root contour. c The sinotubular junction forms the top of the crown, where the outlet of the aortic root in the ascending aorta (Ao) is a true circle. A, anterior; P, posterior; L, left; R, right. d The aortic root gradually becomes less circular, with a more cloverleaf shape at its midportion (i.e. at the sinuses of Valsalva). At this level, the aortic valve leaflets…

Fig. 12. For all measurements of the aortic root as illustrated in Figs. 12, 13 and 14, the use of a (simple) multiplanar reconstruction viewer is mandatory. The three imaging planes should be perpendicular to each other at 90° angles and the reference lines should be “locked” so rotating one reference line automatically rotates the other planes. Care should be taken to have the screen layout setting in such a way that all three imaging planes (starting with axial, coronal and sagittal) are visible simultaneously. The CTA dataset (preferably a systolic phase) is loaded into the viewer. a First, in the coronal plane the aortic valve is located and the centre of the reference lines is placed approximately at the centre of the aortic valve. In the coronal image plane, the references lines are rotated so one of the two lines is at approximately 45° to the horizontal level. This results in the images seen in b. In the plane that was the original sagittal reconstruction (middle panel in b), the reference line is also rotated to be approximately parallel to the aortic valve. This generally provides a pretty good imaging plane that is perpendicular to the aortic valve (right panel in b). The…