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Aortic and vascular disease
Original research article
High-pitch versus conventional cardiovascular CT in patients being assessed for transcatheter aortic valve implantation: a real-world appraisal
  1. Tevfik F Ismail1,
  2. Emma Cheasty2,
  3. Laurence King3,
  4. Sahar Naaseri2,
  5. Olga Lazoura2,
  6. Natalie Gartland2,
  7. Simon Padley2,4,
  8. Michael B Rubens2,4,
  9. Isabel Castellano3,4 and
  10. Edward D Nicol2,4
  1. 1 Division of Imaging Sciences and Biomedical Engineering, King's College London, London, UK
  2. 2 Radiology Department, Royal Brompton Hospital, London, UK
  3. 3 Medical Physics Department, Royal Marsden Hospital, London, UK
  4. 4 Department of Medicine, Imperial College London, London, UK
  1. Correspondence to Dr Edward D Nicol; e.nicol{at}rbht.nhs.uk

Abstract

Objective High-pitch protocols are increasingly used in cardiovascular CT assessment for transcatheter aortic valve implantation (TAVI), but the impact on diagnostic image quality is not known.

Methods We reviewed 95 consecutive TAVI studies: 44 (46%) high-pitch and 51 (54%) standard-pitch. Single high-pitch scans were performed regardless of heart rate. For standard-pitch acquisitions, a separate CT-aortogram and CT-coronary angiogram were performed with prospective gating, unless heart rate was ≥70 beats/min, when retrospective gating was used. The aortic root and coronary arteries were assessed for artefact (significant artefact=1; artefact not limiting diagnosis=2; no artefact=3). Aortic scans were considered diagnostic if the score was >1; the coronaries, if all three epicardial arteries scored >1.

Results There was no significant difference in diagnostic image quality for either the aorta (artefact-free high-pitch: 31 (73%) scans vs standard-pitch: 40 (79%), p=0.340) or the coronary tree as a whole (10 (23%) vs 15 (29%), p=0.493). However, proximal coronary arteries were less well visualised using high-pitch acquisitions (16 (36%) vs 30 (59%), p=0.04). The median (IQR) radiation dose was significantly lower in the high-pitch cohort (dose-length product: 347 (318–476) vs 1227 (1150–1474) mGy cm, respectively, p<0.001), and the protocol required almost half the amount of contrast.

Conclusions The high-pitch protocol significantly reduces radiation and contrast doses and is non-inferior to standard-pitch acquisitions for aortic assessment. For aortic root assessment, the high-pitch protocol is recommended. However, if coronary assessment is critical, this should be followed by a conventional standard-pitch, low-dose, prospectively gated CT-coronary angiogram if the high-pitch scan is non-diagnostic.

  • CT scanning
  • valvular disease
  • aortic valve disease
  • percutaneous valve therapy
  • coronary angiography

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/

https://doi.org/10.1136/openhrt-2017-000626

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    Footnotes

    • TI and EC contributed equally and are joint first author

    • Contributors All authors contributed significantly to the work. TFI, EC and EDN devised and planned the study. TFI and EC performed clinical image analysis. LK and IC performed image noise/CNR evaluation, statistical analysis and dosimetry work. TFI drafted the manuscript. EC, LK, SN, OL, NG, SP, MBR, IC and EDN critically reviewed and revised the manuscript for important intellectual content. EDN was responsible for overall study supervision.

    • Funding No funding was required for this work.

    • Competing interests None declared.

    • Ethics approval Research and Development Office, Royal Brompton Hospital.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Data sharing statement No additional data are available.