Reduction of contrast medium for transcatheter aortic valve replacement planning using a spectral detector CT: a prospective clinical trial

Isabel L Langenbach; Marcel C Langenbach; Thomas Mayrhofer; Borek Foldyna; David Maintz; Konstantin Klein; Hendrik Wienemann; Kathrin B Krug; Martin Hellmich; Matti Adam; Claas P Naehle

doi:10.1007/s00330-023-10403-x

Reduction of contrast medium for transcatheter aortic valve replacement planning using a spectral detector CT: a prospective clinical trial

Eur Radiol. 2023 Nov 18. doi: 10.1007/s00330-023-10403-x. Online ahead of print.

Authors

Isabel L Langenbach^#^{1

2}, Marcel C Langenbach^#^{3

4}, Thomas Mayrhofer^{3

5}, Borek Foldyna³, David Maintz⁴, Konstantin Klein⁴, Hendrik Wienemann⁶, Kathrin B Krug⁴, Martin Hellmich⁷, Matti Adam⁶, Claas P Naehle⁸

Affiliations

¹ Cardiovascular Imaging Research Center, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, 165 Cambridge Street, Suite 400, Boston, MA, 02114, USA. ilangenbach@mgh.harvard.edu.
² Institute for Diagnostic and Interventional Radiology, University Hospital Cologne, Cologne, Germany. ilangenbach@mgh.harvard.edu.
³ Cardiovascular Imaging Research Center, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, 165 Cambridge Street, Suite 400, Boston, MA, 02114, USA.
⁴ Institute for Diagnostic and Interventional Radiology, University Hospital Cologne, Cologne, Germany.
⁵ School of Business Studies, Stralsund University of Applied Sciences, Stralsund, Germany.
⁶ Clinic III for Internal Medicine, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany.
⁷ Institute of Medical Statistics and Computational Biology, Medical Faculty, University of Cologne, Cologne, Germany.
⁸ Radiologische Allianz, Hamburg, Germany.

^# Contributed equally.

PMID: 37979008
DOI: 10.1007/s00330-023-10403-x

Abstract

Introduction: This study investigated the use of dual-energy spectral detector computed tomography (CT) and virtual monoenergetic imaging (VMI) reconstructions in pre-interventional transcatheter aortic valve replacement (TAVR) planning. We aimed to determine the minimum required contrast medium (CM) amount to maintain diagnostic CT imaging quality for TAVR planning.

Methods: In this prospective clinical trial, TAVR candidates received a standardized dual-layer spectral detector CT protocol. The CM amount (Iohexol 350 mg iodine/mL, standardized flow rate 3 mL/s) was reduced systematically after 15 patients by 10 mL, starting at 60 mL (institutional standard). We evaluated standard, and 40- and 60-keV VMI reconstructions. For image quality, we measured signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and diameters in multiple vessel sections (i.e., aortic annulus: diameter, perimeter, area; aorta/arteries: minimal diameter). Mixed regression models (MRM), including interaction terms and clinical characteristics, were used for comparison.

Results: Sixty consecutive patients (mean age, 79.4 ± 7.5 years; 28 females, 46.7%) were included. In pre-TAVR CT, the CM reduction to 40 mL is possible without affecting the image quality (MRM: SNR: -1.1, p = 0.726; CNR: 0.0, p = 0.999). VMI 40-keV reconstructions showed better results than standard reconstructions with significantly higher SNR (+ 6.04, p < 0.001). Reduction to 30 mL CM resulted in a significant loss of quality (MRM: SNR: -12.9, p < 0.001; CNR: -13.9, p < 0.001), regardless of the reconstruction. Across the reconstructions, we observed no differences in the metric evaluation (p > 0.914).

Conclusion: Among TAVR candidates undergoing pre-interventional CT at a dual-layer spectral detector system, applying 40 mL CM is sufficient to maintain diagnostic image quality. VMI 40-keV reconstructions improve the vessel attenuation and are recommended for evaluation.

Clinical relevance statement: Contrast medium reduction to 40 mL in pre-interventional transcatheter aortic valve replacement CT using dual-energy CT maintains image quality, while 40-keV virtual monoenergetic imaging reconstructions enhance vessel attenuation. These results offer valuable recommendations for interventional transcatheter aortic valve replacement evaluation and potentially improve nephroprotection in patients with compromised renal function.

Key points: • Patients undergoing transcatheter aortic valve replacement (TAVR), requiring pre-interventional CT, are often multimorbid with impaired renal function. • Using a spectral detector dual-layer CT, contrast medium reduction to 40 mL is feasible, maintaining diagnostic image quality. • The additional application of virtual monoenergetic image reconstructions with 40 keV improves vessel attenuation significantly in clinical practice.

Keywords: Aortic valve; Aortic valve stenosis; Contrast media; Tomography (X-ray computed); Transcatheter aortic valve replacement.