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131 Reduced-Dose Dual-Source Coronary Computed Tomography Angiography (CCTA): Is Raw-Data-Based Iterative Reconstruction able to Maintain Diagnostic Confidence?
  1. Francois Pontana1,
  2. Isabel Castellano2,
  3. Tevfik Ismail3,
  4. Natalie Gartland3,
  5. Michael Rubens3,
  6. Edward Nicol3
  1. 1Lille University Hospital
  2. 2The Royal Marsden NHS Foundation Trust
  3. 3Royal Brompton Hospital

Abstract

Purpose To evaluate image quality and diagnostic confidence of a raw-data-based iterative reconstruction technique (SAFIRE) in reduced-dose CCTA images in comparison with standard-dose filtered back projection (FBP) images.

Materials and methods 107 consecutive patients (72 males; 35 females), referred for a CCTA were prospectively included using a dual-source CT system in a high pitch (n = 51) or a sequential mode (n = 56) according to heart rate (mean DLP = 204.6 mGy.cm). From each acquisition, three series of images were reconstructed: standard-dose images reconstructed with FBP and considered as the reference standard (Group 1); and two series of reduced-dose images obtained with prototype software simulating a 30% dose reduction, and reconstructed with FBP (Group 2) or SAFIRE (Group 3). Two readers blindly evaluated each series for (a) objective noise and CNR; (b) coronary border sharpness, lesion severity; and (c) diagnostic confidence level using a 5-point scale.

Results In Group 2, there was a significant increase in noise compared to Group 1 (36.8 HU ±6.73 vs 30.4 HU ±5.20; p < 0.0001) and a CNR impairment (15.6 ± 4.3 vs 18.7 ± 4.5; p < 0.0001). In Group 3, despite the 30% dose reduction, SAFIRE restored the objective image quality: mean noise = 31.1 HU ±5.4 (p = 0.8) and CNR = 18.5 ± 5.0 (p = 0.7). However the diagnostic confidence was altered when compared with Group 1 (p < 0.0001), mainly rated as moderate with a blurred aspect of the coronary borders (81/107 [75.7%], p < 0.0001) and a significant number of artefactual non-flow-limiting soft plaques described in vessels considered as normal in Group 1 (105/428 [24.5%], p < 0.0001).

Conclusion Raw-data-based iterative reconstruction allowed significant noise reduction but may be associated with blurring of the coronary luminal borders, which can decrease diagnostic confidence. When reporting reduced-dose CCTA with iterative reconstruction, false smooth plaque artefacts must be considered in diagnostic assessment and subsequent patient management.

  • Coronary CT angiography
  • Iterative Reconstruction
  • Dose reduction

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