Background
Transcatheter aortic valve replacement (TAVR) procedural success relies heavily on
volumetric reconstruction imaging, particularly ECG-gated multi-detector row computed
tomography. We postulated that single examination using fast low-angle shot (FLASH)
dual source CT scanning (DS-CTA) could provide lower dose than ECG-gated CTA while
maintaining the image quality.
Methods
In this single-centre cohort study, all patients who underwent ECG-gated and FLASH
DS-CTA were evaluated. Volumetric reconstructions were performed for both ECG-gated
and FLASH DS-CTA to obtain nonsagittal views of the structures. ECG-gated cardiac
CT was obtained to evaluate the aortic annular size while FLASH DS-CTA was obtained
to examine the aortic and iliac vasculature as part of TAVR imaging protocol. We evaluated
measures of aortic annulus, coronaries and sinus of Valsalva using ECG-gated and FLASH
DS-CTA scanning protocols. Image quality assessments were performed using aortic root
region-of-interest signal-to-noise ratio.
Results
A total of 130 patients (mean age 81.5 ± 9.2 years, 46.2% female, and 99.2% white)
underwent both ECG-gated CT and FLASH DS-CTA. There were excellent correlations between
aortic annular area (R2 = 0.934) and aortic annular perimeter (R2 = 0.923) measured by the two protocols. Only 2 (1.5%) patients had >10% difference
between aortic annular measurements by ECG-gated and FLASH DS-CTA, while none of the
patients had a >10% difference between aortic annular perimeter measured by ECG-gated
and FLASH DS-CT scans. There was no significant difference in signal-to-noise ratio
between the two methods (mean difference 13.4; 95% CI −2.1–28.8, p = 0.09). There was significantly lower radiation dose for FLASH DS-CTA than ECG-gated
CT scan (mean dose-length product difference 404.38; 95% CI 328.9–479.87, p <0.001). The measurements by the two scans led to the same transcatheter valve size
selection in majority of the 128 (98.5%) patients by balloon expandable valve sizing
recommendations and 130 (100%) of patients by self-expanding valve sizing recommendations.
Conclusion
Overall, FLASH DS-CTA and ECG-gated CT scans provided comparable image quality and
aortic annular dimensions for pre-TAVR evaluation. DS-CTA additionally provided the
necessary angiographic imaging of the aorta and peripheral access vessels while still
maintaining a lower radiation dose. We propose that a single non-ECG gated FLASH DS-CTA
could be utilized to provide all the necessary pre-TAVR imaging information without
a gated CT scan.
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Article Info
Publication History
Published online: September 22, 2020
Accepted:
August 25,
2020
Received in revised form:
August 24,
2020
Received:
June 6,
2020
Identification
Copyright
© 2020 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.