Journal of Cardiovascular Computed Tomography (2011) 5, 293–300

Pictorial Essay

Computed tomography evaluation for transcatheter aorticvalve implantation (TAVI): Imaging of the aortic rootand iliac arteries

Paul Schoenhagen, MD*, Samir R. Kapadia, MD, Sandra S. Halliburton, PhD,Lars G. Svensson, MD, E. Murat Tuzcu, MD

Cleveland Clinic Foundation, 9500 Euclid Ave, Desk J 1-4, Cleveland, OH 44195, USA

KEYWORDS:Transcatheter aortic valveimplantation;Computed tomography;Imaging;Aortic stenosis;Iterative reconstruction

Conflict of interest: The authors rep

from Phillips Healthcare and Siemens M

Supplementary material for this art

CardiacCTjournal.com

* Corresponding author.

E-mail address: schoenp1@ccf.org

Submitted January 16, 2011. Accept

1934-5925/$ - see front matter � 2011

doi:10.1016/j.jcct.2011.04.007

Abstract. For patients with severe aortic stenosis, open-heart surgical valve replacement remains thecurrent clinical standard with documented, excellent long-term outcome. Over the past few years,transcatheter aortic valve implantation (TAVI) has developed into a treatment alternative for high-risk patients with severe aortic stenosis. Because transcatheter valvular procedures are characterizedby lack of exposure of the operative field, image guidance is critical. This Pictorial Essay describesthe role of 3-dimensional imaging with multidetector row computed tomography for detailed recon-structions of the aortic valve, aortic root, and iliac arteries in the context of TAVI.� 2011 Society of Cardiovascular Computed Tomography. All rights reserved.

Degenerative valvular heart disease is a major cause ofmorbidity and mortality in the aging population of indus-trialized countries. For patients with severe aortic stenosis,open-heart surgical valve replacement remains the currentclinical standard with documented, excellent long-termoutcome. However, some older patients may not be con-sidered surgical candidates because of a high prevalence ofsignificant comorbidities.1 These patients have poor out-come with medical management.2 Over the past few years,transcatheter aortic valve implantation (TAVI) has devel-oped into a treatment alternative for these high-risk patients

ort departmental research support

edical Solutions.

icle may be found at http://www.

ed for publication April 29, 2011.

Society of Cardiovascular Computed

with severe aortic stenosis (Fig. 1). Recently publishedtrials have shown favorable outcome after transcathetervalve implantation.3,4

Because transcatheter valvular procedures are character-ized by lack of exposure of the operative field, preproceduralplanning, intraoperative decision making, and follow-uprelies on image guidance. Standard 2-dimensional (2D)imaging with conventional angiography and echocardiogra-phy are critically important for patient selection and proce-dural guidance.5 In addition, novel 3-dimensional (3D)imaging approaches, including CT, magnetic resonanceimaging, 3D echocardiography, and C-arm CT are increas-ingly used.6–8 The role and relative importance of thesemodalities are evolving. This Pictorial Essay describes therole of 3D imaging with multidetector row CCT (MDCT)for detailed reconstructions of the aortic valve, aortic root,and iliac arteries in the context of TAVI.9

Because of the relatively large diameter of the deliverysheaths (R18 French), appropriate vascular access is

Tomography. All rights reserved.

Figure 1 This figure shows the 2 most established TAVI systems, the Edwards-Sapien valve (Edwards Lifesciences, left) and theCoreValve (Medtronic, right).

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critical. Small luminal diameter, dense and circumferentialcalcification, and severe tortuosity are common in thispatient population and increase the risk of access site

Figure 2 Images of the infrarenal abdominal aorta and iliac arteries sh.8 mm. The patient was an 81-year-old woman with body mass index

complications (Fig. 2) and central embolization.10–12 De-tailed analysis of the aortic valve and aortic root allowsASSESSMENT OF the aortic valve area (AVA) by

ows dense calcification of the iliac arteries with luminal diameterof 23 kg/m2 and creatinine of 0.8 mg/dL.

Figure 3 Images of the aortic root allows planimetry of aortic valve area, cross-sectional measurements at the annulus, sinuses of Val-salva, and sinotubular junction (STJ). At the annulus, minimum and maximum diameters are reported. At the sinuses of Valsalva, all 3diameters (cusp to commissure) are measured, and typically the largest is reported if the root is symmetric. If the root is asymmetric(eg, bicuspid valve) the largest and smallest diameter are reported. The patient was an 81-year-old woman with body mass index of 23kg/m2 and creatinine of 0.8 mg/dL.

Figure 4 The images also allow measurement of the distance between the annulus and ostia of the left main (LM) and right coronaryartery (RCA). The patient was an 81-year-old woman with body mass index of 23 kg/m2 and creatinine of 0.8 mg/dL.

Schoenhagen et al CT Imaging for TAVI 295

Figure 5 Orientation of reformatted oblique CT images can be described with angiographic planes. The image in the right upper quadrant(green line [online version] left upper quadrant) is equivalent to an angiographic left anterior oblique (LAO) 10-degree, caudal 8-degreeangulation. The patient is an 86-year-old man with a body mass index of 22 kg/m2 and creatinine of 0.8 mg/dL. LCC, left coronarycusp; RCC, right coronary cusp; NCC, noncoronary cusp.

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planimetry and measurements of aortic root dimensions.Particular important measurements are those of the typi-cally oval-shaped aortic annulus (Fig. 3) and the distancebetween the annulus and the coronary arteries (Fig. 4).Dedicated analysis is important for correct selection ofprosthesis size and type. This appears important to avoiddamage at the annulus with subsequent heart block and cor-onary occlusion during the procedure.5,13,14 In addition, theCT data allow one to predict angiographic planes perpen-dicular to the valve for coaxial implantation (Fig. 5).15,16

Functional valvular assessment with CT is possible andshows the relationship between valve calcification andleaflet motion (Movies 1–4). However, despite superiorspatial resolution (0.5 mm), assessment is limited second-ary to the relatively low temporal resolution (.75 millisec-onds). Other limitations of CT are the need for iodinatedcontrast administration and ionizing radiation expo-sure.17,18 In patients with significant renal dysfunction, aCT of the chest and abdomen without contrast can definesize and calcification of the aortic valve,19 aorta, and iliacarteries (Fig. 6). A CT scan of the pelvis after low-dose in-tra-arterial contrast injection into the infrarenal abdominalaorta allows detailed assessment of iliac anatomy (Fig. 7

and Fig. 8).20 However, the risk of contrast-induced ne-phropathy may differ between intravenous and intra-arterial injection.21 Postprocedural imaging provides an as-sessment of the valve position (Fig. 9).

Advances in scanner technology and improved imagingprotocols increasingly allow imaging at lower effectiveradiation doses, although radiation exposure may be a lesscritical concern in the elderly patient populations currentlyconsidered for TAVI.22 Such developments include axialimaging with prospective triggering, volume imaging(256–320 slice), high-pitch helical acquisition, and novelimage reconstruction (Fig. 10; Movies 1–3; Table 1).23–25

Most importantly, further evaluation of the clinicalIMPACT of MDCT and other 3D imaging modalities isnecessary, anticipating future growth of transcatheterprocedures. Similar to recent guidelines developed forthe procedures itself,26 this evaluation of the role of imag-ing should be guided by international consensus.

Supplementary data

Supplementary data related to this article can be foundonline at doi:10.1016/j.jcct.2011.04.007.

Figure 6 Noncontrast CT acquisition. These noncontrast images show a severely calcified aortic valve and allow one to assess size of theaortic root and the origin of the coronary ostia. The right lower panel shows calculation of the aortic valve calcium score (Agatston equiv-alent, threshold 130 HU). The patient was an 88-year-old man with chronic renal insufficiency, body mass index of 20 kg/m2, and creatinineof 1.6 mg/dL.

Figure 7 Intra-arterial contrast injection through pigtail catheter left in the infrarenal aorta after cardiac catheterization. Volume-renderedimages show extensive aortic calcification (left panel), the catheter tip (middle panel), and images after intra-arterial injection (right panel).The patient was an 88-year-old man with chronic renal insufficiency, body mass index of 20 kg/m2, and creatinine of 1.6 mg/dL.

Schoenhagen et al CT Imaging for TAVI 297

Figure 8 Centerline image processing of the iliac arteries (upper panels) and cross-sectional images at the different levels allow assess-ment of dimensions, calcification, and angulation. The patient was an 88-year-old man with chronic renal insufficiency, body mass index of20 kg/m2, and creatinine of 1.6 mg/dL.

Figure 9 Images after TAVI implantation showing the annulus and sinuses of Valsalva, including the position and expansion of the stent/graft. The arrow shows the calcified valve pushed toward the sinus by the stent.

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Figure 10 Iterative image reconstruction of an 80-year-old woman with a body mass index of 22 kg/m2 and creatinine of 1.0 mg/dL.Images are reconstructed with standard filtered back projection and iterative reconstruction (IR; iDose4, Philips Medical Systems, Cleve-land, OH).16 The IR images have significantly reduced noise.

Table 1 Acquisition technique and radiation dose of scan area in figures and movies

Contrast,mL

Acquisitionmode ECG-gating

Tubevoltage, kVp

Effective tubecurrent-timeproduct, mAs CTDIvol, mGy DLP, mGy ! cm

Figs. 2–4*Total 140 1354Root 80 Helical RG 120 710 47 640Aorta 60 Helical NG 120 150 10 689

Fig. 5† and Movies 1–3Total 150 714Root 80 Axial PT 100 332/rot 25 343Aorta 70 Helical NG 100 120 5 342

Figs. 6–8‡

Total 15 447Chest 0 Helical PT 100 100 6 197Pelvis 15 Helical NG 120 105 6 250

Fig. 10*Total 140 1054Root 80 Helical RG 120 444 30 468Aorta 60 Helical NG 120 147 8 556

RG, retrospectively gated; PT, prospectively triggered; NG, nongated acquisition; CTDIvol, volume CT dose index; DLP, dose-length-product [effective

dose (mSv) is calculated as: DLP ! 0.014 (for chest)].

*Images obtained with a Philips Brilliance iCT 256-slice scanner.†Images obtained with a Siemens Definition Flash 2 ! 128-slice dual-source scanner.‡Images obtained with a Philips Brilliance 64-slice scanner.

Schoenhagen et al CT Imaging for TAVI 299

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