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Semi-automatic CT-angiography based evaluation of the aortic annulus in patients prior to TAVR: interchangeability with manual measurements

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Abstract

To compare a semi-automatic software tool for the measurement of aortic annulus dimensions with manual measurements by expert readers and to analyze whether and to what extent interchangeability exists between semi-automatic and manual measurements. We retrospectively included 374 consecutive patients with high-grade aortic stenosis who had undergone CT-angiography of the heart prior to trans-catheter aortic valve replacement (TAVR). In independent analyses, two expert readers manually measured aortic annulus dimensions (long axis, short axis, circumference, area) as well as the distance of the coronary ostia from the annulus plane. A third independent reader performed annulus evaluation using a software tool for semi-automatic detection and measurement of the annulus plane. Intraclass correlation coefficients (ICC) and Bland–Altman analysis was used to compare both manual measurements as well as manual and semi-automatic measurements of annulus parameters. Using the respective measurements we simulated size selection for a Sapien XT transcatheter heart valve (THV). Interchangeability of methods was addressed by calculation of the estimated individual equivalence index γ. There was excellent agreement between both expert observers in manual measurements of the annulus with ICC’s in the range 0.89–0.94 for all anatomic parameters. Similar high agreements were observed between semi-automatic and manual measurements, with ICC’s in the range of 0.89–0.95. THV size recommendation based on manual versus semiautomatic measurements agreed in 80.7% of cases while agreement between both expert readers concerning THV size recommendation was 80.6%. Semi-automatic measurements of anatomic parameters of the aortic root show high agreement and interchangeability with manual measurements in CT-angiography prior to TAVR.

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Authors and Affiliations

  1. Abteilung für Diagnostische und Interventionelle Radiologie, Universitätsklinikum Tübingen, Tübingen, Germany

    Dominik Zinsser, Fabian Bamberg & Konstantin Nikolaou

  2. Klinik und Poliklinik für Radiologie, LMU München, Munich, Germany

    Alena B Baumann, Katharina Stella Winter & Maximilian Reiser

  3. Medizinische Klinik und Poliklinik I, LMU München, Munich, Germany

    Philipp Lange

  4. Klinik und Poliklinik für Innere Medizin I, TU München, Munich, Germany

    Christian Kupatt

  5. Klinik für Diagnostische und Interventionelle Radiologie und Neuroradiologie, Klinikum Augsburg, Stenglinstr. 2, 86156, Augsburg, Germany

    Thomas Kröncke & Florian Schwarz

Authors
  1. Dominik Zinsser
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  2. Alena B Baumann
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  3. Katharina Stella Winter
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  4. Fabian Bamberg
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  5. Philipp Lange
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  6. Konstantin Nikolaou
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  7. Maximilian Reiser
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  8. Christian Kupatt
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  9. Thomas Kröncke
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  10. Florian Schwarz
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Corresponding author

Correspondence to Florian Schwarz.

Ethics declarations

Conflict of interest

Konstantin Nikolaou, Fabian Bamberg and Florian Schwarz have received speaker honoraria from Siemens Healthineers. Konstantin Nikolaou has received speaker honoraria from Bracco Imaging Deutschland GmbH. Fabian Bamberg has received an unrestricted research grant from Bayer Healthcare AG. All other authors declare that they have no conflicts of interest.

Ethical approval

All procedures performed were in accordance with the ethical standards of the institutional and national research committee and with the 1964 Helsinki declaration and its later amendments. This article does not contain any studies with animals performed by any of the authors.

Informed consent

All patients gave informed consent for MDCT. Due to the retrospective nature of this study, the local IRB waived the necessity to obtain informed consent beyond these routine clinical requirements.

Appendices

Appendix 1

Agreement between manual measurements of the aortic root by reader 1 and reader 2 reported as intraclass correlation coefficient and Bland–Altman-analysis parameters in image quality subgroups.

 

Diameter long axis

Diameter short axis

Annulus circumference

Annulus area

Distance of left coronary ostium

Distance of right coronary ostium

Sub-group IQ 4 or 5 (n = 258)

 ICC (95% CI)

0.90 (0.87; 0.92)

0.89 (0.86; 0.91)

0.94 (0.92; 0.95)

0.94 (0.93; 0.96)

0.79 (0.74; 0.83)

0.78 (0.72; 0.82)

 Mean difference

0.00 cm

0.01 cm

0.05 cm

0.03 cm2

0.02 cm

0.06 cm

 SD of differences

0.12 cm

0.11 cm

0.23 cm

0.26 cm2

0.18 cm

0.24 cm

Sub-group IQ 2 or 3 (n = 97)

 ICC (95% CI)

0.88 (0.83; 0.92)

0.89 (0.84; 0.93)

0.93 (0.90; 0.95)

0.95 (0.92; 0.96)

0.74 (0.64; 0.82)

0.65 (0.52; 0.75)

 Mean difference

0.00 cm

0.00 cm

0.11 cm

0.07 cm2

0.01 cm

0.04 cm

 SD of differences

0.14 cm

0.12 cm

0.26 cm

0.29 cm2

0.19 cm

0.25 cm

p for difference in ICC’s

0.42

1.0

0.51

0.44

0.32

0.03

Appendix 2

Agreement between manual and semiautomatic measurements in various subgroups:

Signal-to-noise ratio (SNR)

 

Diameter long axis

Diameter short axis

Annulus circum-ference

Annulus area

Distance of left coronary ostium

Distance of right coronary ostium

SNR > SNRmedian (n = 167)

 ICC (95% CI)

0.89 (0.86; 0.92)

0.86 (0.81; 0.89)

0.95 (0.93; 0.96)

0.95 (0.94; 0.96)

0.69 (0.62; 0.76)

0.75 (0.68; 0.81)

 Mean difference

0.03 cm

0.01 cm

0.01 cm

0.08 cm2

0.01 cm

0.04 cm

 SD of differences

0.13 cm

0.13 cm

0.22 cm

0.26 cm2

0.23 cm

0.26 cm

SNR < SNR25th percentile (n = 87)

 ICC (95% CI)

0.88 (0.82; 0.92)

0.88 (0.82; 0.92)

0.92 (0.88; 0.95)

0.93 (0.90; 0.95)

0.75 (0.64; 0.83)

0.74 (0.64; 0.82)

 Mean difference

0.01 cm

0.03 cm

0.02 cm

0.04 cm2

0.03 cm

0.03 cm

 SD of differences

0.12 cm

0.12 cm

0.29 cm

0.31 cm

0.23 cm

0.26 cm

p value for difference of ICC’s

0.73

0.54

0.07

0.20

0.35

0.87

Degree of calcification

 

Diameter long axis

Diameter short axis

Annulus circum-ference

Annulus area

Distance of left coronary ostium

Distance of right coronary ostium

Calcifications = 1 (n = 97)

 ICC (95% CI)

0.88 (0.82; 0.92)

0.86 (0.80; 0.90)

0.92 (0.89; 0.95)

0.93 (0.90; 0.95)

0.63 (0.49; 0.73)

0.79 (0.71; 0.85)

 Mean difference

0.02 cm

0.02 cm

0.01 cm

0.10 cm

0.00 cm

0.06 cm

 SD of differences

0.12 cm

0.12 cm

0.25 cm

0.27 cm

0.24 cm

0.24 cm

Calcifications = 2 (n = 205)

 ICC (95% CI)

0.89 (0.86; 0.92)

0.86 (0.82; 0.89)

0.95 (0.94; 0.96)

0.95 (0.94; 0.96)

0.71 (0.64; 0.76)

0.71 (0.63; 0.77)

 Mean difference

0.02 cm

0.05 cm

0.01 cm

0.05 cm

0.00 cm

0.04 cm

 SD of differences

0.13 cm

0.27 cm

0.22 cm

0.27 cm

0.23 cm

0.26 cm

Calcifications = 3 (n = 53)

 ICC (95% CI)

0.90 (0.84; 0.94)

0.85 (0.76; 0.91)

0.94 (0.90; 0.97)

0.95 (0.92; 0.97)

0.76 (0.61; 0.85)

0.81 (0.69; 0.88)

 Mean difference

0.03 cm

0.03 cm

0.02 cm

0.08 cm2

0.04 cm

0.02 cm

 SD of differences

0.12 cm

0.11 cm

0.24 cm

0.26 cm2

0.22 cm

0.23 cm

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Zinsser, D., Baumann, A.B., Winter, K.S. et al. Semi-automatic CT-angiography based evaluation of the aortic annulus in patients prior to TAVR: interchangeability with manual measurements. Int J Cardiovasc Imaging 34, 1657–1667 (2018). https://doi.org/10.1007/s10554-018-1377-2

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