Rofo 2020; 192(12): 1174-1182
DOI: 10.1055/a-1150-7646
Heart

Radiation Dose Reduction in Preprocedural CT Imaging for TAVI/TAVR Using a Novel 3-Phase Protocol: A Single Institution’s Experience

Strahlendosisreduktion der präprozeduralen CT-Bildgebung für TAVI/TAVR mittels eines neuartigen 3-Phasen-Protokolls
Seyd Shnayien
Radiology, Charité-Universitätsmedizin Berlin, Germany
,
Keno Kyrill Bressem
Radiology, Charité-Universitätsmedizin Berlin, Germany
,
Nick Lasse Beetz
Radiology, Charité-Universitätsmedizin Berlin, Germany
,
Patrick Asbach
Radiology, Charité-Universitätsmedizin Berlin, Germany
,
Bernd Hamm
Radiology, Charité-Universitätsmedizin Berlin, Germany
,
Stefan Markus Niehues
Radiology, Charité-Universitätsmedizin Berlin, Germany
› Author Affiliations

Abstract

Purpose To retrospectively investigate the effectiveness of a novel 3-phase protocol for computed tomography (CT) before transcatheter aortic valve implantation/transcatheter aortic valve replacement (TAVI/TAVR) in terms of radiation dose and image quality.

Materials and Methods A total of 107 nonrandomized patients (81 ± 7.4 years) scheduled for TAVI/TAVR underwent preprocedural CT on an 80-row CT scanner. 55 patients underwent a combined ECG-synchronized spiral scan of the chest and non-ECG-synchronized spiral scan of the abdomen/pelvis as recommended by the Society of Cardiovascular Computed Tomography (SCCT). 52 patients underwent an updated 3-phase variable helical pitch (vHP3) protocol combining a non-ECG-synchronized spiral scan of the upper thoracic aperture, followed by a prospective ECG-synchronized spiral scan of the heart, and a non-ECG-synchronized abdominal/pelvic spiral scan. The radiation dose was determined from an automatically generated protocol based on the CT dose index (CTDI). Objective image quality in terms of vessel attenuation and image noise was measured, and the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Subjective image quality was evaluated using a 4-point scale and compared for interrater agreement using Cohen’s weighted kappa coefficient (κw). All data were compared and statistically analyzed.

Results Use of the novel 3-phase vHP3 protocol reduced the dose-length product (DLP) from 1256.58 ± 619.05 mGy*cm to 790.90 ± 238.15 mGy*cm, reducing the effective dose (E) from 21.36 ± 10.52 mSv to 13.44 ± 4.05 mSv and size-specific dose estimates (SSDE) from 20.85 ± 7.29 mGy to 13.84 ± 2.94 mGy (p < 0.001). There were no significant differences in objective and subjective image quality between the two protocols and between the two readers.

Conclusion The novel 3-phase vHP3 protocol significantly reduces the radiation dose of preprocedural TAVI/TAVR CT without a loss of image quality.

Key Points:

  • The use of a novel 3-phase protocol for preprocedural TAVI/TAVR CT reduces radiation dose by 37 % compared to a combined ECG-synchronized and non-ECG-synchronized spiral CT protocol.

  • Objective image quality remains unaffected as image noise, SNR, and CNR did not differ significantly between the two protocols. The average attenuation of the aortic root and abdominal aorta exceeded 450 HU in both protocols.

  • The average subjective image quality ratings were good to excellent for both protocols with almost perfect to substantial interrater agreement.

Citation Format

  • Shnayien S, Bressem KK, Beetz NL et al. Radiation Dose Reduction in Preprocedural CT Imaging for TAVI/TAVR Using a Novel 3-Phase Protocol: A Single Institution’s Experience. Fortschr Röntgenstr 2020; 192: 1174 – 1182

Zusammenfassung

Ziel Diese retrospektive Studie untersuchte die Wirksamkeit eines neuen 3-Phasen-Protokolls für die präprozedurale Computertomografie (CT) vor einer Transkatheter-Aortenklappenimplantation (TAVI; engl.: TAVR) in Bezug auf die Strahlenbelastung und diagnostische Bildqualität.

Material und Methoden 107 nichtrandomisierte Patienten (81 ± 7,4 Jahre) erhielten vor der geplanten TAVI/TAVR eine präinterventionelle CT an einem 80-Zeilen-Gerät. Davon wurden 55 Patienten mit einem kombinierten EKG-synchronisierten und nicht EKG-synchronisierten Spiral-CT-Protokoll entsprechend der Empfehlungen der Society of Cardiovascular Computing Tomography (SCCT) untersucht, während 52 Patienten die CT-Bildgebung nach dem neuen, aktualisierten 3-Phasen-Protokoll (vHP3; variabler Pitch-Faktor 3) erhielten. vHP3 kombiniert eine nicht EKG-synchronisierte Spiral-CT des oberen Thorax mit einer anschließenden EKG-synchronisierten Spiral-CT des Herzens und einer nicht EKG-synchronisierten Abdomen/Becken-Spiral-CT. Die Strahlendosis wurde anhand eines automatisch generierten Protokolls basierend auf dem CT-Dosisindex (CTDI) bestimmt. Die objektive Bildqualität in Bezug auf Gefäßkontrastierung und Bildrauschen wurde gemessen und SNR und CNR berechnet. Die subjektive Bildqualität wurde unter Verwendung einer 4-Punkt-Skala bewertet und mittels Cohens-Kappa-Koeffizienten (κw) auf Interrater-Reliabilität überprüft. Alle Daten wurden verglichen und statistisch ausgewertet.

Ergebnisse Die Verwendung des neuartigen 3-Phasen-vHP3-Protokolls reduzierte das Dosislängenprodukt (DLP) von 1256,58 ± 619,05 mGy*cm auf 790,90 ± 238,15 mGy*cm, die effektive Dosis (E) von 21,36 ± 10,52 mSv auf 13,44 ± 4,05 mSv und die größenspezifische Dosisabschätzung (SSDE) von 20,85 ± 7,29 mGy auf 13,84 ± 2,94 mGy (p < 0,001). Hierunter zeigten sich keine signifikanten Unterschiede in der objektiven und subjektiven Bewertung der Bildqualität zwischen beiden Gruppen.

Schlussfolgerung Das neue 3-Phasen-vHP3-Protokoll ermöglicht die Durchführung einer präprozeduralen CT vor TAVI/TAVR mit einer signifikanten Reduzierung der Strahlendosis ohne Minderung der Bildqualität.

Kernaussagen:

  • Die Verwendung eines neuartigen 3-Phasen-Protokolls für die präprozedurale TAVI-CT reduziert die Strahlendosis um 37 % verglichen mit einem kombinierten EKG-synchronisierten und nicht EKG-synchronisierten Spiral-CT-Protokoll.

  • Die objektive Bildqualität bleibt unbeeinträchtigt, da Bildrauschen, SNR und CNR keinen signifikanten Unterschied zwischen beiden Protokollen aufweisen und die durchschnittliche Gefäßkontrastierung der Aorta jeweils 450 HU übersteigt.

  • Die subjektive Bildqualität wird für beide Protokolle mit fast perfekter bis zu erheblicher Interrater-Reliabilität als gut bis ausgezeichnet bewertet.



Publication History

Received: 21 August 2019

Accepted: 08 March 2020

Article published online:
16 April 2020

© 2020. Thieme. All rights reserved.

Georg Thieme Verlag KG
Rüdigerstraße 14, 70469 Stuttgart, Germany

 
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